wimax performance evaluation and traffic analysis
TRANSCRIPT
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WIMAX PERFORMANCE EVALUATION AND TRAFFIC ANALYSIS
This thesis paper is submitted to theDepartment of Electrical and Electronic Engineering
Stamford University Bangladesh
In Partial Fulfillment of the Requirement for theDegree of
Bachelor of Science in Electrical and Electronic Engineering
ByMd. Sahadat Hossain
EEE 042 06574Kazi Mahidul Islam
EEE 042 06559Khandakar Ashraful Azam Shovo
EEE 042 06567Sanzida Azam Sami
EEE 042 06565
Supervised by:Dr. Dilshad Mahjabeen
Assistant Professor,Department of Electrical & Electronic Engineering,
Stamford University Bangladesh
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DECLARATION
We are Md. Sahadat Hossain, Kazi Mahidul Islam, Khandakar Ashraful Azam Shovo and Sanzida Azam Sami the student of Bachelor of Science in Electrical and Electronic Engineering hereby solemnly declare that, the work presented in this thesis has been carried out by us and has not previously been submitted to any other University/College/Organization for any academic qualification /certificate/diploma/degree. We warrant that the present work does not breach any copyright.
We further undertake to indentify the university against any loss or damage arising from breach of the foregoing obligations.
……………………..Md. Sahadat HossainEEE 042 06574
……………………..Kazi Mahidul IslamEEE 042 06559
……………………..Khandakar Ashraful Azam ShovoEEE 042 06567
……………………..Sanzida Azam SamiEEE 042 06565
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Approval
The thesis title “WiMAX Performance Evaluation and Traffic Analysis” submitted by Md. Sahadat Hossain, ID: EEE- 042 06574; Kazi Mahidul Islam, ID: EEE-042 06559; Khandakar Ashraful Azam Shovo, ID: EEE- 042 06567; Sanzida Azam Sami, ID:EEE- 042 06565 of the department of Electrical and Electronic Engineering has been satisfactorily accepted in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering on March 2014.
Signature of the Supervisor Signature of the Chairman
Dr. Dilshad Mahjabeen Prof. Dr. Md. Aynal Haque
Assistant Professor Chairman
Deptartment of EEE Department of EEE
Stamford University Bangladesh Stamford University Bangladesh
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Acknowledgement
First of all, we would like to show our highest gratitude to the Almighty
ALLAH for his kindness on us that make it possible for us to complete the study
and preparation of this thesis. We have worked with a great number of people
whose contribution in assorted ways to research and making of the thesis deserved
special mention. It is a pleasure to convey our gratitude to them all in our humble
acknowledgement. We would like to record our gratitude to our supervisor Dr.
Dilshad Mahjabeen, Assistant professor of EEE department for her supervision,
advice and guidance from the very early stage of this research as well as giving us
extraordinary experiences throughout the work.
We gratefully acknowledge Professor Dr. Md. Aynal Haque, Chairman,
department of EEE Stamford University Bangladesh for his advice and
encouragement. We would like to thank all of our teachers in our University and
WiMAX provider companies for their continuous support in different context.
At the end, we are also grateful to our family for their moral support
throughout our education life.
THE AUTHORS
Md. Sahadat Hossain
Kazi Mahidul Islam
Khandakar Ashraful Azam Shovo
Sanzida Azam Sami
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Abstract
WiMAX which represents World Interoperability for Microwave Access is a major part of broadband wireless network having IEEE 802.16 standard provides innovative fixed as well as mobile platform for broadband internet access, which provides Seamless connectivity anytime, anywhere broadband access solution. Ultimately, WiMAX is intended to serve as the next step in the evolution of 3G mobile phones, via a potential combination of WiMAX and CDMA standards called 4G. Bangladesh is also an emerging market for WiMAX technology. WiMAX is a dynamic solution to establishing long-haul data communication link to distant areas. Different parameters of traffic engineering are discussed here. Based on these parameters traffic analysis of a WiMAX provider is also done different time period and perspectives. For Bangladesh here, Alexa Traffic Rank, Load Time, Page Rank, SEO Rank, Home Page Link, Indexed Page Link, Website with Similar Rank, Social Network, Page view per user daily, Similar website, Backward link are taken into consideration for different months of the year. The graphs are presented and from this the traffic analysis is done. Comparative analysis is also done with other countries of the world for the same WiMAX provider. From the discussion, it is provided that if WiMAX are designed in a proper network planning which is helpful to offer better throughput broadband wireless connectivity at a much lower cost with the help of existing architecture and available resources.
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Contents
1. Introduction 14-27
1.1 Communication System 14-14
1.2 Elements of Communication System (Communication Process) 15-16
1.3 Types of Communication 16-19
1.3.1 Analog Communication
1.3.2 Digital Communication
1.3.3 Wired Communication
1.3.4 Wireless Communication
1.3.5 Different Types of Wireless
Communication System
1.4 Generation of Wireless Mobile Systems 19-25
1.4.1 First Generation (1G)
1.4.2 Second Generation (2G)
1.4.3 Interim Generation (2.5G)
1.4.4 Third Generation (3G)
1.4.5 Fourth Generation (4G)
1.5 WiMAX 25-26
1.6 History of WiMAX 26-26
1.7 Necessity of WiMAX 26-27
1.8 Tele-traffic Engineering 27-27
2. Basic WiMAX Technology 28-422.1 WiMAX 28-28
2.2 Types of WiMAX 29-30
2.2.1 Fixed WiMAX
2.2.2 Mobile WiMAX
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2.3 Network Architecture of WiMAX 30-33
2.4 How WiMAX Works 33-35
2.5 The Protocol Layers of WiMAX 35-37
2.6 Duplexing Scheme in WiMAX: TDD or FDD 37-38
2.7 WiMAX Frequencies and Spectrum Allocations 39-39
2.8 Advantages of WiMAX 40-41
2.8.1 QoS: A Powerful WiMAX Advantage
2.8.2 Improved User Connectivity
2.8.3 Link Adaptation: Provides High Reliability
2.8.4 Intelligent Bandwidth Allocation: Provides
Guaranteed
2.8.4.1 Service Levels
2.8.4.2 NLOS Support
2.8.4.3 Highly Efficient Spectrum Utilization
2.8.4.4 Secured Data Exchange
2.9 WiMAX versus 3G and Wi-Fi 41-42
3. Traffic Engineering 43-60
3.1 Network Traffic Load and Parameters 43-44
3.2 Tradeoff between Effectiveness and Simplicity 44-45
3.3 Service Guarantees 45-46
3.4 Resource Management Policy 46-47
3.4.1 Traffic Model
3.4.2 Network Model
3.4.3 Performance Model
3.5 Hierarchical Resource Management Model 47-52
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3.5.1 Physical and Virtual Network Layer
3.5.2 Call Layer
3.5.3 Burst and Packet Layer
(a) Packet Scheduling
(b) Buffer Allocation
3.5.4 Modeling of Burst Traffic
3.6 QoS Evaluation 52-52
3.6.1 Link Qos Models
3.6.2 Grade of Service Models
3.7 CAC and Routing 53-53
3.8 Network Design 53-54
3.8.1 Network Topology
3.8.2 Network Link Capacities
3.9 Delay Systems 54-55
3.10 Application of Tele-traffic Engineering 55-57
3.10.1 In PSTN Architecture
3.10.2 In Call Centers
3.10.3 In Broadband Networks
3.10.4 Logic-tail Traffic
3.11 Different Traffic Parameters for WiMAX 57-60
3.11.1 Alexa Rank
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3.11.2 Load Time
3.11.3 Page Rank
3.11.4 SEO Rank
3.11.5 Home Page Link
3.11.6 Indexed Page Link
3.11.7 Website with Similar Rank
3.11.8 Social Network Analysis
3.11.9 Page View per User Daily
3.11.10 Similar Website
3.11.11 Backward Link
4. WiMAX Traffic Analysis, Results and Discussion 61-75
4.1 Analysis of Different Traffic Parameters for WiMAX 61-61
4.1.1 Alexa Traffic Rank
4.1.2 Website Load Time
4.1.3 Page Rank
4.1.4 SEO Score
4.1.5 Home Page Rank
4.1.6 Indexed Page Link
4.1.7 Website with Similar Rank
4.1.8 Social Network
4.1.9 Page View per User Daily
4.1.10 Similar Website
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4.1.11 Backward Link
5. Conclusion 76-77
5.1 Concluding Remarks 76-77
5.2 Future Scope 77-77
6. References 78-84
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List of Figures
1. Introduction
Fig. 1.1 Elements of communication system 15
Fig. 1.2 EM wave generation 20
Fig. 1.3 Evolution of cellular systems 22
Fig. 1.4 Samples of mobile phones from the three generations 24
2. Basic WiMAX TechnologyFig. 2.1 Types of WiMAX 30
Fig. 2.2 IP-Based WiMAX Network Architecture 31
Fig. 2.3 Functions performed across reference points 33
Fig. 2.4 WiMAX operation 34
Fig. 2.5 Fixed WiMAX Using CPE 35
Fig. 2.6 The Seven-layer OSI model for networks 36
Fig. 2.7 Protocol layers of the 802.16 BWA standards 37
Fig. 2.8 Downlink and Uplink 37
Fig. 2.9 Frequency Division Duplex (FDD) - full duplex mode 38
Fig. 2.10 Time Division Duplex (TDD) 38
Fig. 2.11 Current major spectrum allocations for WiMAX worldwide 39
3. Traffic Engineering
Fig. 3.1 Resource management policy 46
Fig. 3.2 Hierarchical traffic model 47
Fig. 3.3 Hierarchical resource management model 49
Fig. 3.4 Elements of a queuing system 55
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4. WiMAX Traffic Analysis, Results and Discussion
Fig. 4.1 Daily Global Alexa Traffic Rank Graph 62
Fig. 4.2 Graph of Country basis Alexa Rank 63
Fig. 4.3 Monthly graph of Average load time 65
Fig. 4.4 Graph of Monthly Google page rank 66
Fig. 4.5 Graph of some WiMAX providers SEO 67
Fig. 4.6 Graph of monthly internal and external home page link 68
Fig. 4.7 Indexed page link Graph 69
Fig. 4.8 Graph of website with similar rank 71
Fig. 4.9 Graph of Socials analysis 72
Fig. 4.10 Graph Daily page views per user 73
Fig. 4.11 Graph of similar website 74
Fig. 4.12 Graph of monthly basis Backward links analysis 75
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List of Tables
1. Introduction
Table 1.1 Generation of Wireless Technology 25
4. WiMAX Traffic Analysis, Results and Discussion
Table 4.1 Daily Basis Global Alexa Traffic Rank (7 Days) 62
Table 4.2 Country basis Alexa Traffic rank 63
Table 4.3 Monthly average website load time from 1 Nov,2011-20 Feb,2014 64
Table 4.4 Monthly Page Rank by Google page rank 65
Table 4.5 SEO scores of some different WiMAX provider 66
Table 4.6 Monthly internal and external home page link 67
Table 4.7 Indexed page link 69
Table 4.8 Websites with similar rank between #16,922 and #16,930 70
Table 4.9 Socials analysis 71
Table 4.10 Daily page view per user 72
Table 4.11 Similar website 73
Table 4.12 Monthly basis Backward links analysis 75
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Chapter 01
Introduction1.1 Communication SystemIn telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union. Telecommunications is a method of communication (e.g., for sports broadcasting, mass media, journalism, etc.). A communications subsystem is a functional unit or operational assembly that is smaller than the larger assembly under consideration [1].
Communication is the process of establishing connection or link between two points for information exchange. OR The purpose of communication system is to transmit information bearing signals from a source located at one point to a user destination located at another point some distance away.
Communication is simply the process of conveying message at a distance or communication is the basic process of exchanging information. The electronic equipment’s which are used for communication purpose, are called communication equipment’s. Different communication equipment’s when assembled together form a communication system.
Typical examples of communication systems are line telephony and line telegraphy, radio telephony and radio telegraphy, radio broadcasting, point-to-point communication and mobile communication, computer communication, radar communication, television broadcasting, radio aids to navigation, radio aids to aircraft landing etc.
The earliest communication system namely line-telegraphy originated in eighteen forties (1840s). In addition to this, line telephony came a few decades later whereas radio-communication could become possible in the beginning of twent ieth century on invention of triode valve. Radio communication was further greatly improved during World War II. It becomes more widely used through the invention of transistor, integrated circuits (ICS) and other Semiconductor devices in the subsequent years. Also in recent years, communication has become more widespread with the use or satellites and fiber optics. Today, there has been an increasing emphasis on the use of computer in communication.
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1.2 Elements of Communication System (communication Process)
Figure 1.1: Elements of communication system
The essential components of communication system are information source, input transducer, transmitter, communication channel, receiver and destination.
1.2.1. Information source: We know that a communication system serves to communicate a message signal or information. The information or message signal is originated from information source. Source of information generates message signal examples of which are human voice, telephone pictures, teletype data, atmospheric temperature and pressure in the above example.In short, we can say that the function of information source is to produce required message signal which has to be transmitted.
1.2.2 Input Transducer: A transducer is a device which converts one form of energy into another form. The message from the information source may or may not electrical in nature. In a case when the message signal produced by information source is not electrical in nature, an input transducer is used to convert it into a time varying electrical signal. For example, in case of radio-broadcasting, a microphone converts the information or message which is in the form of sound waves into corresponding electrical signal.
1.2.3 Transmitter: The function of transmitter is to process the electrical signal from different aspects. The signal received from the information source after converting it into electrical signal is not suitable for transmission over the channel. The message signal requires same processing like filtering and modulation etc., so that it is suitable for the transmission over the channel. Inside the transmitter, signal processing such as restriction of range of audio frequencies, amplification and modulation are achieved. All these processing of the message signal are done just to ease the transmission of the signal through the channel.
1.2.4 Channel: The physical connection between transmitter output and receiver input is provided by the channel. There are mainly two types of channels.
a. Point to point channel b. Broad cast channel
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a. Point to point channel: The point to point channels are wire lines, microwave links, optical fibers. The wire lines are operated by guided electromagnetic waves used in local telephone transmission. In microwave links, the transmitted signal is radiated as an electromagnetic wave in free space and or used in long distance communication. An optical fiber is lawless well controlled, guided optical medium used in optical fiber communication system.
b. Broadcast channel: Broadcast channels provide a capability where several receiving stations can be reached simultaneously from a single transmitter. An example of Broadcast channels is a satellite in geostationary orbit, which covers one third of earth’s surface.
1.2.5 Noise: Noise is an unwanted signal which tends to interface with the required with the required signal. Noise signal is always random in character. Noise may interfere with signal at any point in a communication system. However, the noise has its greatest effect on the signal in the channel.
1.2.6 Receiver: The signal received at the output of the channel consists of noise along when information carrying signals must be separated from carrier wave and noise introduce by the channel. The receiver performs the estimation of original message signal. This operation of receiver is called demodulation.
1.2.7 Destination: Destination is the final stage which is used to convert an electrical message signal into its original form. For example in radio broadcasting, the destination is a loudspeaker which works as a transducer i.e. it converts the electrical signal form of original sound signal.
1.3 Types of CommunicationTypes of Communication System can be classified as
a. Analog Communication and b. Digital Communication
1.3.1 Analog CommunicationAnalog Communication is that type of communication in which the message or information signal i.e. transmitted is analog in nature. This means that in analog communication modulating signal (i.e. baseband signals) is analog signal. This analog message signal may be obtained from sources such as speech, video shooting etc.
In analog communication, the analog message signal modulates some high carrier frequency inside the transmitter to produce modulating signal. This modulated signal is then transmitted with the help of a transmitting antenna to travel through the transmission channel. At the receiver, this modulated signal is received and processed to recover the original message signal. Presently all the AM, FM radio transmission and TV transmission are examples of analog communication system [2].
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1.3.2 Digital communication
Data transmission, digital transmission, or digital communications is the physical transfer of data (a digital bit stream) over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication channels, and storage media. The data are represented as an electromagnetic signal, such as an electrical voltage, radio wave, microwave, or infrared signal.
While analog transmission is the transfer of a continuously varying analog signal, digital communications is the transfer of discrete messages. The messages are either represented by a sequence of pulses by means of a line code (baseband transmission), or by a limited set of continuously varying wave forms (pass band transmission), using a digital modulation method. The pass band modulation and corresponding demodulation (also known as detection) is carried out by modem equipment. According to the most common definition of digital signal, both baseband and pass band signals representing bit-streams are considered as digital transmission, while an alternative definition only considers the baseband signal as digital, and pass band transmission of digital data as a form of digital-to-analog conversion.
Data transmitted may be digital messages originating from a data source, for example a computer or a keyboard. It may also be an analog signal such as a phone call or a video signal, digitized into a bit-stream for example using pulse-code modulation (PCM) or more advanced source coding (analog-to-digital conversion and data compression) schemes. This source coding and decoding is carried out by codec equipment [3].
Based on transmission media communication system can be classified as
1. Wired communication system2. Wireless communication system
1.3.3 Wired communication
Wired communication refers to the transmission of data through a wire medium of communication technology.
The term “wire communication” or “communication by wire” means the transmission of writing, signs, signals, pictures, and sounds of all kinds by aid of wire, cable, or other like connection between the points of origin and reception of such transmission, including all instrumentalities, facilities, apparatus, and services (among other things, the receipt, forwarding, and delivery of communications) incidental to such transmission [4].
Examples include telephone networks, cable television or internet access, and fiber-optic communication. Also waveguide (electromagnetism), used for high-power applications, is considered as wired line.
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1.3.4 Wireless communication
Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor.
The most common wireless technologies use electromagnetic wireless telecommunications, such as radio. With radio waves distances can be short, such as a few meters for television or as far as thousands or even millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones.
Wireless operations permit services, such as long-range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls etc.) which use some form of energy (e.g. radio waves, acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.
1.3.4.1 Different Types Of Wireless Communication Systems
Over the last few decades there has been a considerable rise in the development of wireless communication systems. This rise is predominantly owing to the prevalent acceptance of wireless local area networks and cellular mobile radio systems. Wireless communication system can be of many types and each type consists of several different components. Let us take a look at some of these varieties.
a) A power line communication system is a system that transmits data electronically from a single or multiple sources to the respective destinations. These systems are comparatively lower in cost than others. The cable television is a well-known example of this type electronic system. It provides wide number of channels to homes and is also used to gain access to the internet.
b) A radio communication system is one type of communication operations. It makes use of electromagnetic waves to transfer information. The frequencies of these waves are lower than that of visible light. A transmitter at the end of the radio system transfers the information and converts it electronically into radio waves. This type of communication network then receives these types of waves. The system is designed to detect these waves, decode them and then also convert them into a format that is recognizable. A good example of such a system is a walkie- talkie which makes use of 2 hand-held transceivers.
c) A third type of wireless communication system is the optical communication system. This system is well-known for its revolutionary contribution to the telecommunications industry. Optical fiber is generally used to transfer signals of this type. For comparatively short distances like a couple of miles, signals can also be sent by way of air. They
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provide better quality and efficiency than other types of systems. This is mainly because light is the medium that is used in optical systems. Light is known to be clearer, faster and also more reliable than radio signals and electrical signals.
d) Finally, there is also the hybrid communication networks which are networks that utilize two or more than two media to transmit data. For instance, communication networks can make use of satellite, wireless, cellular and internet technologies to transfer information. These communication systems highly differ in performance, complexity, types of services provided and cost.
Wireless communication systems are being constantly evolved by researchers through the use of different combinations of systems. These systems are highly preferred because they are portable in nature and highly convenient to use [5].
1.4 Generations of Wireless Mobile Systems
Wireless communication is basically transmitting and receiving voice and data using electromagnetic waves in open space. The origin of wireless communications can be traced back to the year 1857, when the behavior of electromagnetic waves was explained mathematically using four equations by James Clerk Maxwell. Maxwell’s four equations describe the electric and magnetic fields arising from varying distributions of electric charges and currents, and how those fields change with time.
The equations were the mathematical representation of decades of experimental observations of the electric and magnetic effects of charges and currents. According to Maxwell, an accelerated charge creates a magnetic field in its neighborhood which in turn creates an electric field in the same area.
A moving magnetic field produces an electric field and vice versa. These two fields vary with time, so they act as sources of each other. Thus, an oscillating charge having non-zero acceleration will emit an electromagnetic (EM) wave and the frequency of the wave will be same as that of the oscillation of the charge. Though the electromagnetic waves were first discovered as a communication medium at the end of the nineteenth century, these were put in use for the masses later.
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Figure 1.2: EM wave generation
Twenty years later, in the period 1879–1886, after a series of experiments, Heinrich Hertz came to the conclusion that an oscillatory electrical charge q = q0sin t radiates EM waves and these waves carry energy. Hertz was also able to produce EM waves of frequency 3 ×1010 Hertz. The experimental setup is shown in the Figure1.2. To detect EM waves, he used a loop S, which is slightly separated from EM wave generator as shown in the figure.
Hertz’s radio system consists of a switch and an induction coil to generate a spark across two electrodes. The receiver was a loop(S) made from a copper wire around 35 cm in diameter, with a small gap in the loop. When the “transmitter” generated a spark, a small spark was seen to jump the gap in the receiving coil. This is the basis for the antenna theory. In 1895–1897, Jagdish Bose also succeeded in generating EM waves of very short wavelength (∼25 mm).
The father of today’s mobile radio systems is G. Marconi, born in Italy in 1874. He demonstrated the first radio-based wireless transmission successfully using electromagnetic waves in 1901 over a distance of 1 mile. However, the bandwidth of these transmission systems was very small; the transmission of information was very slow. Over the next couple of decades, Marconi was a leading pioneer in establishing long-range wireless communication standards and his efforts led to the deployment of first radio-based telephony system for conversations between ships in 1915.
A technological breakthrough was the development of frequency modulation (FM) in the mid-1930s by Edwin Howard Armstrong. The Second World War battlefields were a major test bed for portable two-way FM radio technologies. The first systems offering mobile telephone service (MTS) (car phone) were introduced in the late 1940s in the United States and in the early 1950s in Europe. These single cell systems were severely constrained by restricted mobility, low capacity, limited service, and poor speech quality. Also, the equipment was heavy, bulky, expensive, and susceptible to interference.
In 1964, Bell Laboratories introduced the improved mobile telephone service (IMTS) which added full-duplex features to the old MTS. In 1968 and 1970, the Federal Communication Commission (FCC) realizing the huge potentials of mobile telephony, reallocated the frequency spectrum (40 MHz band in the 800 to 900 MHz frequency range) for cellular use. The cell covers a service area where a group of mobiles or terminals (referred to as users) are served primarily by one BS – usually located at the Centre of the cell.
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In addition, AT&T proposed a cellular mobile scheme in 1968 to the FCC which was approved in 1974. The cellular concept of using the same frequency at different places was introduced by MacDonald in 1979. The next evolutionary steps begin in the early 1980s with the deployment of the first generation (1G) analogue networks based on frequency division multiplexing (FDM). In addition to the original 40 MHz band, an additional 10 MHz band was allocated in 1988 and called as the expanded spectrum (ES). Cellular communication is full duplex and the frequency band is divided between both communications: 25MHz is allocated to the forward path or downlink, which is the path for BS to mobile unit and the other half is for the mobile to BS. The paths are separated by a 45 MHz guard band in order to avoid interference between transmission and reception channels.
The increased demand for mobile communication led to the evolution of second generation (2G) digital networks in the early 1990s. The introduction of time-division multiplexing (TDM) on top of the existing FDM, an essential feature of 2G, increased the number of served subscribers per geographical area. In addition, voice quality was improved as well, with the introduction of newer voice coding algorithms. Finally, at the beginning of the third millennium, the first 2.5G networks, which are an upgrade of 2G and the 3G networks were implemented in most countries worldwide. And now the research is on the next-generation mobile technology with more advanced features that is 4G, which is expected to be available in the market by 2012–2015. For clear understanding of the evolution of analogue and digital cellular technology, their broad features are illustrated in Figure 1.3.
1.4.1 First generation (1G)
The first 1G mobile phone system was introduced in 1980 in the United States. Before 1G, “0G” refers to pre-cellular mobile telephony technology, such as radio telephones that we had in cars before the advent of cell phones.
Analogue circuit-switched technology is used for this system, with frequency division multiple accesses (FDMA), as an air channel multiple access technique, and worked mainly in the 800–900 MHz frequency bands. The 1G mobile phone had only voice facility.
Examples of 1G system are analogue mobile phone systems (AMPS) and total access communication systems (TACS). The AMPS was implemented in North America and the TACS was used in Europe.
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Figure 1.3: Evolution of cellular systems
In AMPS, two 25-MHz bands are allocated. One 25-MHz band is for communication from BS to mobile unit and the other for communication from mobile unit to BS.
The following are the limitations of 1G:
Supports only speech Low traffic capacity Unreliable handover Long-call setup time and frequent call drops Inefficient use of bandwidth and poor battery life Poor voice quality and large phone size Allows users to make voice calls in 1 country only
1.4.2 Second generation (2G)
The need for more user capacity per cell led to the development of 2G technologies. 2G systems are digital cellular systems and were introduced in the late 1980s and were in use till the late 1990s. 2G technology supports data, speech, FAX, SMS, and WAP services. The frequency bands used by GSM are 890–960 MHz and 1710–1880 MHz In the 890–960 MHz frequency band, the band at 890–915 MHz is dedicated to uplink communications from the mobile station (MS) to the BS, and the band at 935–960 MHz is used for the downlink communications from the BS to the MS. 2G digital technology is divided into two standards: time division multiple access (TDMA) and code-division multiple access (CDMA).
Global system for mobile (GSM) was the first commercially operated digital cellular system and uses TDMA/frequency-division duplexing (FDD)
IS-95 is commonly referred to as CDMA one standard and is used in North America and some parts of Asia
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The following are limitations of 2G:
Provides low data rates ranging from 9.6 kbps to 28.8 kbps. Circuit-switched network, where the end systems are dedicated for the entire call session.
This causes reduction in usage of bandwidth and resources. Too many 2G standards globally (e.g. GSM, CDMA, PDC, and PHS )
1.4.3 Interim generation (2.5G)
The need for increased throughput data rates in data transfer (such as web browsing and e-mail) led to the evolution of 2.5G which is between 2G and 3G.
The mobile technology using GPRS standard has been termed as 2.5G.
The 2.5G was started in 1998 with added GPRS and enhanced data rates for GSM evolution (EDGE). In addition to the hypertext transfer protocol (HTTP), it supports the wireless access protocol (WAP) through which web pages can be viewed on the small screen of a mobile phone or a handheld device, which led to mobile commerce (m-commerce).
1.4.4 Third generation (3G)
The need for high-speed internet access, live video communications, and simultaneous data and voice transmission led to the development of 3G cellular networks. The 3G technology has added multimedia facilities to 2.5G phones. 3G operates in the frequency band of 1710–2170 MHz It provides high transmission rates from 348 Kbps in a moving vehicle to 2 Mbps for stationary or mobile users.
The aim of 3G systems is to provide communication services from person-to-person at any place (global roaming) and at any time through any medium with guaranteed quality of service.
Examples of 3G system are universal mobile telecommunication systems (UMTS) and international mobile telecommunications at 2,000 MHz (IMT-2000).
UMTS are designed to provide different types of data rates, based on the following circumstances: up to 144 kbps for moving vehicles, 384 kbps for pedestrians, and 2 Mbps for indoor or stationary users. UMTS will integrate all the services offered by different mobile communication systems such as mobile phone, cordless telephone, and satellite radio in one service. Japan was the first country to introduce 3G system IMT-2000 network nationally, and in Japan the transition to 3G was completed in the year 2006.
Figure1.4 illustrates the mobile phone samples of 1G, 2G, and 3G cellular network generations. Figure1.4 (a) is the first handheld device from Motorola Company which was available in 1984 in 1G network. Figure1.4 (b) is Ericsson GH218 which was introduced in 1994 and operated in 2G networks. Figure1.4(c) is the LG U8110 that was introduced in 2004 and is operating in 3G networks.
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The following are the drawbacks of 3G system:
High bandwidth requirement High spectrum licensing fees Expense and bulk size of 3G phones Lack of 2G mobile user buy in for 3G wireless service Lack of network coverage because it is still a new service High prices of 3G mobile services in some countries
1.4.5 Fourth generation (4G)
Even though the 3G networks have been deployed since 2001, the true broadband access will be achieved with the 4G mobile phones. The 4G mobile communications will have transmission rates up to 20 Mbps higher than that of 3G.
4G technology is expected to provide very smooth global roaming universally with lower cost. Theoretically, 4G is set to deliver 100 Mbps to a roaming mobile device globally, and up to 1 Gbps to a stationary device. 4G will bring almost the perfect real world wireless internetworking called “WWWW: World Wide Wireless Web”
Figure1.4: Samples of mobile phones from the three generations
With the expected features in mind, 4G allows for video conferencing, streaming picture-perfect video (e.g. tele-medicine and tele-geo processing application) and much more. Since the 4G is a research item for the next-generation wide-area cellular radio, the technology is expected to be available around 2012–2015. The following modulation techniques are proposed to be used in the 4G cellular phones.
Variable spreading factor-orthogonal frequency and code division multiplexing (VSF-OFCDM).
Variable spreading factor code-division multiple access (VSF-CDMA).[6]
Summarizes the generations of wireless technology [7].
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Table 1.1: Generation of wireless technology
1.5 WiMAXWiMAX (Worldwide Interoperability for Microwave Access) is a technology standard for long-range wireless networking. WiMAX equipment exists in two basic forms - base stations, installed by service providers to deploy the technology in a coverage area, and receivers, installed in clients.
WiMAX supports several networking usage models:
1. A means to transfer data across an Internet service provider network, commonly called backhaul)
2. A form of fixed wireless broadband Internet access, replacing satellite Internet service
3. A form of mobile Internet access that at one time competed directly with LTE technology.
While at one time WiMAX was envisioned to be a leading form of Internet communications across all three of the areas above, its adoption has been limited.
WiMAX is developed by an industry consortium, overseen by a group called the WiMAX Forum. The Forum certifies WiMAX equipment to ensure it meets the technology standards. Its technology is based on the IEEE 802.16 set of wide-area communications standards. WiMAX signals can function over a distance of several miles (kilometers) with data rates reaching up to 75 megabits per second (Mb/s). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz.
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Primarily due to its much higher cost, WiMAX is not a replacement for Wi-Fi home networking or Wi-Fi hotspot technologies [8].
1.6 History of WiMAX
In the mid 1990's cell phone companies and service providers started to work on wireless broadband connection technology. This technology was envisioned as a way to maintain the speed and security of a hardwired network, but still maintain the low cost of a wireless network. In 1999 the 802.16 standard was developed by the Institute of Electrical and Electronics Engineers, or the IEEE. This technology was released in 2001 but had a small range and was limited to line-of-sight transmissions. Also in 2001 the WiMAX forum was started which would act as a way to market and promote the use of the 802.16 standard. This forum is a non-profit organization that consists of members of over 520 companies that share a similar goal to integrate WiMAX technologies into businesses and with consumers around the world. As this technology has grown over the years it has seen many spurts of growth. One of the biggest monumental periods of growth was in 2005 when the standard 802.16e was released. This was the first mobile WiMAX system. This technology is continuing to grow rapidly and we will soon see even faster speeds and more coverage as WiMAX technology continues to innovate internet capabilities [9].
1.7 Necessity of WiMAXWiMAX, also known as 4G technology, uses the same basic technology that cell phones use, though it is distinctly different. That is, you can't use older cell phone technology to connect to the internet. New infrastructure needs to be installed in your city in order for you to have access to this service. That means that this new way of connecting to the internet is not available everywhere at the moment, though its coverage area is constantly expanding. The best way to find out if it's available in your area is to head over to a provider's website and input your zip code.
So what make it so special? For starters, it's a wireless connection to the internet. It's not like cable, DSL or even dial-up where you need to physically connect your computer with a wire to your internet service provider. Instead it's just like using your cell phone in that the internet is beamed directly to your computer at home. It's tempting to think that since no wires are involved the connection would not be able to keep pace with other broadband connections. But to the contrary, wireless technologies have really come of age in the last couple of years and are just as fast as their wired counterparts. Essentially, that means you'll be able to download large files in minutes instead of hours like with dial-up. You'll be able to do anything that you want with your internet. You'll be able to stream movies, upload pictures and video to Facebook and even video conference with your friends and family using an application such as Skype.
The question of reliability often arises too. But again a comparison can be drawn to cell phones. People use cell phones every day to talk with other people and they seem to be doing just fine. As long as they have signal then can talk for as long as they want. Similarly, as long as you have
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a 4G signal, you can use the internet for as long as you want. This also means that if you stray too far from the coverage area you may lose signal, and thus internet.
WiMAX also has something that other connections don't have. Subscribers have the option of using a USB modem or PC card to connect their mobile computing device to the internet anywhere in the coverage area. Essentially, you plug the USB modem or PC card into your laptop and you've got the internet. Now you can use the internet at your favorite restaurant, at a friend's place, at the local park, and even inside a moving vehicle. This feature is often the reason why most people end up signing up for this revolutionary service [10].
1.8 Tele-traffic EngineeringA telecommunications network consists of expensive hardware (trunks, switches, etc.) with the function of carrying telecommunications traffic (phone calls, data packets, etc.). The physical network is fixed, but the traffic that it is designed to carry is random. That is, the times at which calls are generated are unpredictable (except in a statistical sense), and, similarly, the lengths of time that the calls will last are unpredictable; yet, the network designers must decide how many resources to provide to accommodate this random demand. If the resources are provided too sparingly, then the quality of service will be low (e.g., too many calls will be lost because the required resources are not available when needed); but, if the resources are provided too generously, then the costs will be too high. Tele-traffic theory deals with the mathematical analysis of models of telecommunications systems and with the interrelationships among the provision of resources, the random demand, and the quality of service; Tele-traffic engineering addresses the art and science of the application of this theory to the design of real telecommunications systems [11].
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Chapter 02
Basic WiMAX Technology
WiMAX technology provides both fixed and mobile Internet access, the latter of which can support mobility in vehicular networks with possibly very few handoffs because of its large coverage range. The mobile WiMAX is based on IEEE 802.16e standard, which supports the soft and hard handover between base stations. It promises to open new, economically viable market opportunities for operators, wireless Internet service providers and equipment manufacturers. Compared with Wi-Fi technology, the relative high throughput, scalability and long-range features of WiMAX make it a more suitable choice for meeting the demand of vehicular applications [13].
The mobile WiMAX provides high speed data rate, which could support up to 100Mbit/s rates to mobile users, while the uplink throughput could reach 50Mbit/s. Operating at the maximum range of 50 km, WiMAX technology minimizes the number of handoff and reduces the time consumed on reconnection. Thus, it is a suitable wireless technology for potential applications like portable mobile broadband connectivity across cities and countries [12].
There has been some investigation into the performance of fixed and mobile WiMAX under different propagation environments [14] shows the comparison between the simulation and experiment results obtained on throughput, and demonstrated that the street level operating range for mobile WiMAX system can be up to 2100m. Based on the Received Signal Strength Indication data and Signal to Noise Ratio measurements, [15] analyzes and evaluates the physical performance of fixed WiMAX in a typical urban area and proposes its path loss model. However, little research analyses the performance of a vehicular network that uses WiMAX infrastructure. Also, in [16], researchers from Seoul tested the TCP performance over mobile WiMAX by putting mobile nodes on more than 5000 vehicles. They found that the downlink TCP throughput could reach 1.9Mbps, and the uplink throughput was up to 300Kbps.
2.1 WiMAXWiMAX, the Worldwide Interoperability for Microwave Access, represents a paradigm shift in telecommunications technology. It offers the promise of cheaper, smaller, and simpler technology compared to existing broadband options such as DSL, cable, fiber, and 3G wirelesses [17].
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2.2 Types of WiMAX
There are 2 main types of WiMAX
Fixed WiMAX Mobile WiMAX
2.2.1 Fixed WiMAX
Using the 2 to 11 GHz frequencies which can penetrate walls and other dense objects, 802.16-2004 provides transmission to stationary devices and replaces prior 802.16 and 802.16a specifications. Higher frequencies require line of sight. 802.16-2004 was previously 802.16d.
What makes WiMAX so exciting is the broad range of applications it makes possible but not limited to broadband internet access, T1/E1 substitute for businesses, voice over Internet protocol (VoIP) as telephone company substitute, Internet Protocol Television (IPTV) as cable TV substitute, backhaul for Wi-Fi hotspots and cell phone towers, mobile telephone service, mobile data TV, mobile emergency response services, wireless backhaul as substitute for fiber cable.
WiMAX provides fixed, portable or mobile non-line-of sight service from a base station to a subscriber station, also known as customer premise equipment (CPE). Some goals for WiMAX include a radius of service coverage of 6 miles from a WiMAX base station for point-to-multipoint, non-line-of-sight service. This service should deliver approximately 40 megabits per second (Mbps) for fixed and portable access applications. That WiMAX cell site should offer enough bandwidth to support hundreds of businesses with T1 speeds and thousands of residential customers with the equivalent of DSL services from one base station.
2.2.2 Mobile WiMAX
802.16e is an extension of 802.16-2004 for mobile use in the 2 to 6 GHz band. It allows people to communicate while walking or riding in cars and provides a mobile voice over IP (VoIP) and higher-speed data alternative to the cellular networks (GSM, TDMA, CDMA).
Mobile WiMAX takes the fixed wireless application a step further and enables cell phone-like applications on a much larger scale. For example, mobile WiMAX enables streaming video to be broadcast from a speeding police or other emergency vehicle at over 70 MPH. It potentially replaces cell phones and mobile data offerings from cell phone operators such as EvDo and HSDPA. In addition to being the final leg in a quadruple play, it offers superior building penetration and improved security measures over fixed WiMAX. Mobile WiMAX will be very
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valuable for emerging services such as mobile TV and gaming [18].
Figure 2.1: Types of WiMAX
2.3 Network Architecture of WiMAX
The IEEE 802.16e-2005 standard provides the air interface for WiMAX but does not define the full end-to-end WiMAX network. The WiMAX Forum’s Network Working Group, is responsible for developing the end-to-end network requirements, architecture, and protocols for WiMAX, using IEEE 802.16e-2005 as the air interface.
The WiMAX NWG has developed a network reference model to serve as an architecture framework for WiMAX deployments and to ensure interoperability among various WiMAX equipment and operators. The network reference model envisions unified network architecture for supporting fixed, nomadic, and mobile deployments and is based on an IP service model. Figure 2.2 shows a simplified illustration of IP-based WiMAX network architecture. The overall network may be logically divided into three parts: (1) mobile stations used by the end user to access the network, (2) the access service network (ASN), which comprises one or more base stations and one or more ASN gateways that form the radio access network at the edge, and (3) the connectivity service network (CSN), which provides IP connectivity and all the IP core network functions.
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Figure 2.2: IP-Based WiMAX Network Architecture
The architecture framework is defined such that the multiple players can be part of the WiMAX service value chain. More specifically, the architecture allows for three separate business entities: (1) network access provider (NAP), which owns and operates the ASN;
(2) network services provider (NSP), which provides IP connectivity and WiMAX services to subscribers using the ASN infrastructure provided by one or more NAPs; and
(3) application service provider (ASP), which can provide value-added services such as multimedia applications using IMS (IP multimedia subsystem) and corporate VPN (virtual private networks) that run on top of IP. This separation between NAP, NSP, and ASP is designed to enable a richer ecosystem for WiMAX service business, leading to more competition and hence better services.
The network reference model developed by the WiMAX Forum NWG defines a number of functional entities and interfaces between those entities. (The interfaces are referred to as reference points.) Figure 2.3 shows some of the more important functional entities.
Base station (BS): The BS is responsible for providing the air interface to the MS. Additional functions that may be part of the BS are micro mobility management functions, such as handoff triggering and tunnel establishment, radio resource management, QoS policy enforcement, traffic classification, DHCP (Dynamic Host Control Protocol) proxy, key management, session management, and multicast group management.
Access service network gateway (ASN-GW): The ASN gateway typically acts as a layer 2 traffic aggregation points within an ASN. Additional functions that may be part of the ASN gateway include intra-ASN location management and paging, radio resource management and admission control, caching of subscriber profiles and encryption keys, AAA client functionality,
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establishment and management of mobility tunnel with base stations, QoS and policy enforcement, and foreign agent functionality for mobile IP, and routing to the selected CSN.
Connectivity service network (CSN): The CSN provides connectivity to the Internet, ASP, other public networks, and corporate networks. The CSN is owned by the NSP and includes AAA servers that support authentication for the devices, users, and specific services. The CSN also provides per user policy management of QoS and security.
The CSN is also responsible for IP address management, support for roaming between different NSPs, location management between ASNs, and mobility and roaming between ASNs. Further, CSN can also provide gateways and interworking with other networks, such as PSTN (public switched telephone network), 3GPP, and 3GPP2.
The WiMAX architecture framework allows for the flexible decomposition and/or combination of functional entities when building the physical entities. For example, the ASN may be decomposed into base station transceivers (BST), base station controllers (BSC), and an ASN-GW analogous to the GSM model of BTS, BSC, and Serving GPRS Support Node (SGSN).
It is also possible to collapse the BS and ASN-GW into a single unit, which could be thought of as a WiMAX router. Such a design is often referred to as a distributed, or flat, architecture. By not mandating a single physical ASN or CSN topology, the reference architecture allows for vendor/operator differentiation.
In addition to functional entities, the reference architecture defines interfaces, called reference points, between function entities. The interfaces carry control and management protocols—mostly IETF-developed network and transport-layer protocols—in support of several functions, such as mobility, security, and QoS, in addition to bearer data. Figure 2.3.2 shows an example.
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Figure 2.3: Functions performed across reference points
The WiMAX network reference model defines reference points between: (1) MS and the ASN, called R1, which in addition to the air interface includes protocols in the management plane, (2) MS and CSN, called R2, which provides authentication, service authorization, IP configuration, and mobility management, (3) ASN and CSN, called R3, to support policy enforcement and mobility management, (4) ASN and ASN, called R4, to support inter-ASN mobility, (5) CSN and CSN, called R5, to support roaming across multiple NSPs, (6) BS and ASN-GW, called R6, which consists of intra-ASN bearer paths and IP tunnels for mobility events, and (7) BS to BS, called R7, to facilitate fast, seamless handover [19].
2.4 How WiMAX WorksThe WiMAX network uses an approach that is similar to that of cell phones. Coverage for a geographical area is divided into a series of overlapping areas called cells. Each cell provides coverage for users within that immediate vicinity. When subscriber travels from one cell to another, the wireless connection is handed off from one cell to another.
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A WiMAX system consists of two parts:
A Base station, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km).is mounted on a tower or tall building to broadcast the wireless signal.
A WiMAX subscriber device, these could be WiMAX enabled notebook, mobile Internet device (MID), or even a WiMAX modem by using the subscriber receives the signals.
The user pays the service provider for wireless Internet access, just as they would for a normal Internet connection via a cable network. The service provider provides the end user with the software, a login and a password. Most of the laptop manufacturers today equip high-end models with a built in antenna bundled with the required software for the unit to be WiMAX compatible. The service provider beams the internet signals from the base station. The antenna at the user end catches the signals, providing uninterrupted internet as long as the signal is available. With a laptop quipped with an antenna you could be connected to the Internet wherever the signal is available from the base station. As with mobile station that catch a signal from the nearest tower of the particular service provider, so is it with new generation WiMAX services. One WiMAX base station can send signals over distances of several miles depending on the terrain. The more flat the terrain, more the coverage. If end user moves from one base station area to another, your laptop receiver will hook up to the other base station (of the same service provider) with a stronger signal.
Figure 2.4: WiMAX operation
For fixed WiMAX deployments, service providers supply Customer Premises Equipment (CPE) that acts as a wireless “modem” to provide the interface to the WiMAX network for a specific location, such as a home, cafe, or office. WiMAX is also well Suited for emerging markets as a cost-effective way to deliver high speed Internet [20] [21].
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Figure 2.5: Fixed WiMAX Using CPE
2.5 The Protocol Layers of WiMAX
The IEEE 802.16 BWA network standard applies the so-called Open Systems Interconnection (OSI) network reference seven-layer model, also called the OSI seven-layer model. This model is very often used to describe the different aspects of a network technology. It starts from the Application Layer, or Layer 7, on the top and ends with the Physical (PHY) Layer, or Layer 1, on the bottom (see Figure 2.5).
The OSI model separates the functions of different protocols into a series of layers, each layer using only the functions of the layer below and exporting data to the layer above. For ex- ample, the IP (Internet Protocol) is in Layer 3, or the Routing Layer. Typically, only the lower layers are implemented in hardware while the higher layers are implemented in software.
The two lowest layers are then the Physical (PHY) Layer, or Layer 1, and the Data Link Layer, or Layer 2. IEEE 802 splits the OSI Data Link Layer into two sub layers named Logical Link Control (LLC) and Media Access Control (MAC). The PHY layer creates the physical connection between the two communicating entities (the peer entities), while the MAC layer is responsible for the establishment and maintenance of the connection (multiple access, scheduling, etc.).
The IEEE 802.16 standard specifies the air interface of a fixed BWA system supporting multimedia services. The Medium Access Control (MAC) Layer supports a primarily point- to-multipoint (PMP) architecture, with an optional mesh topology. The MAC Layer is structured to support many physical layers (PHY) specified in the same stan- dard. In fact, only two of them are used in WiMAX.
The protocol layers architecture defined in WiMAX/802.16. It can be seen that the 802.16
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standard defines only the two lowest layers, the Physical Layer and the MAC Layer, which is the main part of the Data Link Layer, with the LLC layer
Figure 2.6: The seven-layer OSI model for networks. In WiMAX/802.16, only the two first layers are defined
Very often applying the IEEE 802.2 standard. The MAC layer is itself made of three sub- layers, the CS (Convergence Sub layer), the CPS (Common Part Sub layer) and the Security Sub layer.
The dialogue between corresponding protocol layers or entities is made as follows. A Layer X addresses an XPDU (Layer X Protocol Data Unit) to a corresponding Layer X (Layer X of the peer entity). This XPDU is received as an (X-1) SDU (Layer X-1 Service Data Unit) by Layer X-1 of the considered equipment. For example, when the MAC Layer of a sends an MPDU (MAC PDU) to corresponding equipment, this MPDU is received as a PSDU (Physical SDU) by the Physical Layer (see Figure 2.5.2).
In this chapter, the different layers are introduced. Each of these layers or sub layers and many of their functions are described in the following sections [22].
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Figure 2.7: Protocol layers of the 802.16 BWA standards. (From IEEE Std. 802.16-2004
2.6 Duplexing Scheme in WiMAX: TDD or FDDDuplexing refers to the way downlink and uplink data is arranged in a two-way wireless transmission. The downlink carries information from a Base Station (BS) to Subscriber Stations (SSs). Downlink is also known as forward link. The uplink carries information from a SS to a BS. It is also called reverse link. There are two types of duplexing scheme, i.e. FDD and TDD.
Figure 2.8: Downlink and UplinkDownlink and uplink traffic in a 2-way communication.
FDD (Frequency Division Duplex) requires two distinct channels for transmitting downlink sub-frame and uplink sub-frame at the same time slot. FDD is suitable for bi-directional voice service
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since it occupies a symmetric downlink and uplink channel pair. FDD is commonly used in cellular networks (2G and 3G). Meanwhile, WiMAX supports full-duplex FDD and half-duplex FDD (HFDD or HD-FDD). The difference is in full-duplex FDD a user device can transmit and receive simultaneously, while in half-duplex FDD a user device can only transmit or receive at any given moment.
Figure 2.9: Frequency Division Duplex (FDD) - full duplex modeDownlink and uplink sub-frames are transmitted at the same time in two adjacent channels.
FDD is inefficient for handling asymmetric data services since data traffic may only occupy a small portion of a channel bandwidth at any given time. TDD (Time Division Duplex) is another duplexing scheme that requires only one channel for transmitting downlink and uplink sub-frames at two distinct time slots. TDD therefore has higher spectral efficiency than FDD. Moreover, using TDD downlink to uplink (DL/UL) ratio can be adjusted dynamically. TDD can flexibly handle both symmetric and asymmetric broadband traffic.
Figure 2.10: Time Division Duplex (TDD)Downlink and uplink sub-frames are transmitted at different time slots in one channel.
Most WiMAX implementations either on licensed or license-exempt bands will most likely use TDD. The reasons are TDD uses half of FDD spectrum hence saving the bandwidth, TDD system is less complex and thus cheaper, and WiMAX traffic will be dominated by asymmetric data. The first release of Fixed WiMAX profiles support both TDD and FDD, while Mobile WiMAX profiles only include TDD [23].
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2.7 WiMAX Frequencies and Spectrum Allocations
The IEEE 802.16 WiMAX standard allows data transmission using multiple broadband frequency ranges. The original 802.16a standard specified transmissions in the range 10 - 66 GHz, but 802.16d allowed lower frequencies in the range 2 to 11 GHz. The lower frequencies used in the later specifications means that the signals suffer less from attenuation and therefore they provide improved range and better coverage within buildings. This brings many benefits to those using these data links within buildings and means that external antennas are not required.
Different bands are available for WiMAX applications in different parts of the world. The frequencies commonly used are 3.5 and 5.8 GHz for 802.16d and 2.3, 2.5 and 3.5 GHz for 802.16e but the use depends upon the countries: [24]
Figure 2.1: Current major spectrum allocations for WiMAX worldwide.
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2.8 WiMAX Advantages
2.8.1 QoS: A Powerful WiMAX Advantage
Several features of the WiMAX protocol ensure robust quality-of-service (QoS) protection for services such as streaming audio and video. As with any other type of network, users have to share the data capacity of a WiMAX network, but WiMAX’ QoS features allow service providers to manage the traffic based on each subscriber’s service agreements on a link-by-link basis. Service providers can therefore charge a premium for guaranteed audio/video QoS, beyond the average data rate of a subscriber’s link [25].
2.8.2 Improved User Connectivity
WiMAX keeps more users connected by virtue of its flexible channel widths and adaptive modulation. Because it uses channels narrower than the fixed 20 MHz channels used in 802.11, the 802.16-2004 standards can serve lower-data-rate subscribers without wasting bandwidth. When subscribers encounter noisy conditions or low signal strength, the adaptive modulation scheme keeps them connected when they might otherwise be dropped [25].
2.8.3 Link Adaptation: Provides High Reliability
WiMAX provides adaptive modulation and coding — subscriber by subscriber, burst by burst, and uplink and downlink. Transmission adaptation with the help of modulation depending on channel conditions provides high reliability to the system. Further, this feature imparts differential service provision, making the system economically more appealing to operators. [25].
2.8.4 Intelligent Bandwidth Allocation: Provides Guaranteed
2.8.4.1 Service Levels:Terminals have a variety of options available to them for requesting bandwidth, depending on the QoS and traffic parameters of their services. The option of bandwidth on demand (frame by frame) by reallocation of frequency band makes WiMAX flexible as well as efficient [25].
2.8.4.2NLOS Support: Provides Wider Market and Lower Costs WiMAX solves or mitigates the problems resulting from NLOS conditions by using multiple frequency allocation support from 2 to 11 GHz, orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) for NLOS applications (licensed and license-exempt spectrum), sub channelization, directional antennas, transmit and receive diversity, adaptive modulation, error correction techniques, and power control [25].
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2.8.4.3Highly Efficient Spectrum Utilization:In WiMAX, the MAC is designed for efficient use of spectrum and incorporates techniques for efficient frequency reuse, deriving a more efficient spectrum usage of the access system [25].
2.8.4.4Secured Data Exchange:WiMAX proposes the full range of security features to ensure secured data exchange: terminal authentication by exchanging certificates to prevent rogue devices, user authentication using the Extensible Authentication Protocol (EAP), data encryption using the Data Encryption Standard (DES) or Advanced Encryption Standard (AES), both of which are much more robust than the Wireless Equivalent Privacy (WEP) standard initially used by WLAN. Furthermore, each service is encrypted with its own security association and private keys [25].
2.9 WiMAX versus 3G and Wi-FiHow does WiMAX compare with the existing and emerging capabilities of 3G and Wi-Fi? The throughput capabilities of WiMAX depend on the channel bandwidth used. Unlike 3G systems, which have a fixed channel bandwidth, WiMAX defines a selectable channel bandwidth from 1.25MHz to 20MHz, which allows for a very flexible deployment. When deployed using the more likely 10MHz TDD (time division duplexing) channel, assuming a 3:1 downlink-to-uplink split and 2 2 MIMO, WiMAX offers 46Mbps peak downlink throughput and 7Mbps uplink.
The reliance of Wi-Fi and WiMAX on OFDM modulation, as opposed to CDMA as in 3G, allows them to support very high peak rates. The need for spreading makes very high data rates more difficult in CDMA systems.
More important than peak data rate offered over an individual link is the average throughput and overall system capacity when deployed in a multicellular environment. From a capacity standpoint, the more pertinent measure of system performance is spectral efficiency. The fact that WiMAX specifications accommodated multiple antennas right from the start gives it a boost in spectral efficiency.
In 3G systems, on the other hand, multiple-antenna support is being added in the form of revisions. Further, the OFDM physical layer used by WiMAX is more amenable toMIMO implementations than are CDMA systems from the standpoint of the required complexity for comparable gain. OFDM also makes it easier to exploit frequency diversity and multiuser diversity to improve capacity. Therefore, when compared to 3G, WiMAX offers higher peak data rates, greater flexibility, and higher average throughput and system capacity. Another advantage of WiMAX is its ability to efficiently support more symmetric links—useful for fixed applications, such as T1 replacement—and support for flexible and dynamic adjustment of the downlink-to-uplink data rate ratios. Typically, 3G systems have a fixed asymmetric data rate ratio between downlink and uplink. What about in terms of supporting advanced IP applications, such as voice, video, and multimedia? How do the technologies compare in terms of prioritizing traffic and controlling quality?
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The WiMAX media access control layer is built from the ground up to support a variety of traffic mixes, including real-time and non-real-time constant bit rate and variable bit rate traffic, prioritized data, and best-effort data. Such 3G solutions as HSDPA and 1x EV-DO were also designed for a variety of QoS levels.
Perhaps the most important advantage for WiMAX may be the potential for lower cost owing to its lightweight IP architecture. Using an IP architecture simplifies the core network—3G has a complex and separate core network for voice and data—and reduces the capital and operating expenses. IP also puts WiMAX on a performance/price curve that is more in line with general-purpose processors (Moore’s Law), thereby providing greater capital and operational efficiencies. IP also allows for easier integration with third-party application developers and makes convergence with other networks and applications easier.
In terms of supporting roaming and high-speed vehicular mobility, WiMAX capabilities are somewhat unproven when compared to those of 3G. In 3G, mobility was an integral part of the design; WiMAX was designed as a fixed system, with mobility capabilities developed as an add-on feature.
In summary, WiMAX occupies a somewhat middle ground between Wi-Fi and 3G technologies when compared in the key dimensions of data rate, coverage, QoS, mobility, and price[26].
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Chapter 03
Traffic Engineering
Traffic engineering provides the basis for the analysis and design of telecommunication networks. The calculations of blocking probability due to the no availability of switching paths were based on a quantity that specified the function of the time for which a subscriber line may be busy. In practice, the situation is much more complex. It is not only the switching element but also many other common shared subsystems in a telecommunication network that contribute to the blocking of a subscriber call. In a telephone network these include digit receiver, inter stage switching links, and call processors and trunks between exchanges. The load and the traffic pattern on the networks vary during the day with heavy traffic at certain times and low traffic at other times. The tasks of designing cost effective networks that provide the required quality of service under varied traffic conditions demands a formal scientific basis. Such a basis is provided by traffic engineering or Tele-traffic theory. Traffic engineering analysis enables one to determine the ability of a telecommunication network to carry a given traffic at a particular loss probability. It provides a means to determine the quantum of common equipment’s required to provide a particular level of service for a given traffic pattern and volume [27].
3.1 Network Traffic Load and ParametersThe originating call amplitudes are relative and the actual values depend on the area of where the statistics is collected. The traffic pattern, however, is the same irrespective of the area considered. Obviously, there is little use of the network 0 to 6 hours when most of the population is sleep. There is a large peak around mid-forenoon and mid-afternoon signifying busy office activities. The afternoon peak is, however, slightly smaller. The load is low during the lunch-hour period, i.e. 12.00-14.00 hours. The period 17.00-18.00 hours is characterized by low traffic signifying that the people are on the move from office to their residences. The peak of domestic calls occurs after 18.00 hours when persons reach home and reduced tariff applies. In many countries including India, the period during which the reduced tariff applies has been changed to begin later than 18.00 hours and one may expect the domestic call patterns also to change accordingly. Generally there is a peak of calls around 10.00 hours just before people leave their homes on outings and another peak occurs again in the evening.
In a day, the 60-minute interval in which the traffic is the highest is called the busy hour (BH). The busy hours may vary from exchange to exchange depending on the location and the community interest of the subscriber. The busy hours may also show seasonal, weekly and in some places even daily variations. In addition to these variations, there are also unpredictable
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peaks caused by stock market or money market activity, weather, natural disaster, international events, sporting events etc. to take into account such fluctuations while designing switching networks, three types of busy hours are defined by CCITT in its recommendations E.600:
i. Busy Hours: Continuous 1- hour period lying wholly in the time interval concerned, for which the traffic volume or the number of call attempts is greatest.
ii. Peak Busy Hour: The busy hour this day; it usually varies from day to day, or over a number of days.
iii. Time Consistent Busy Hour: The 1-hour period starting at the same time each day for which the average traffic volume or the number of call attempts is greatest over the days under consideration.
For ease of record, the busy hour is taken to commence on the hour or half-hour only.
1. Complete or Success Call: Not all call attempts materialize into actual conversations for a variety of reasons such as called line busy, no answer from the called line, and blocking in the trunk groups or the switching centers. A call is attempts said to be successful or completed if the called party answers.
2. Call Completion Rate (CCR): Call completion rate is defined as the ratio of successful calls to the number of call attempts. This parameter is used in dimensioning the network capacity. Networks are usually designed to provide an overall CCR of over 0.70. a CCR value of 0.75 is considered excellent and attempts to further improve the value is generally not cost effective.
3. Busy Hours Call Attempts (BHCA): The number of call attempts in the busy hours is called busy hour call attempts. This is an important parameter in deciding the processing capacity of a common control or a stored program control system of an exchange.
4. Busy Hour Calling Rate: A related parameter that is often used in traffic engineering calculations is busy hour calling rate which is defined as the average number of calls originated by a subscriber during the busy hour [27].
3.2 Tradeoff between Effectiveness and Simplicity
TE is concerned with finding an efficient tradeoff between effectiveness (in terms of proximity to optimality) and simplicity (in terms of time and space complexity) for the TE solution. A highly effective TE solution is desired since it means that fewer call requests needs to be rejected leading to increased revenue. Moreover, expansion of the network capacity is driven by the increase in network demand. An effective TE solution allows longer time periods between capacity upgrades which means longer time periods for the depreciation of the capital expenditures.
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However, increased effectiveness normally requires a more complex computer-based solution. A complex solution has larger capital expenditures (e.g. implementation costs) and operational expenditures (e.g. system maintenance costs). A complex solution is based on a more complex system model and/or computation algorithm that requires longer execution times and/or larger memory space. Note that the system response time requirements restrict the complexity of the TE algorithms. Therefore, the chosen TE solution should provide a good balance between the potential for large revenue (measured by TE effectiveness) against the expected costs (measured by TE complexity). TE planning involves finding the set of TE algorithms with maximal effectiveness that provides the desired TE complexity.
3.3 Service Guarantees
The network is offered flows from several service classes. Each service class should be given end-to-end performance guarantees in terms of QoS and GoS metrics on the packet/burst and call level respectively. QoS metrics include loss, delay, delay-jitter and throughput guarantees. Packet loss can occur due to buffer overflow or delay bound violation. Packet delay is composed of a fixed part due to packetization, propagation, transmission, reassembly, switching, and a variable part due to stochastic queueing effects. Packet service specifies QoS by loss probability, delay quantile, and delay-jitter quantile, while a deterministic service specifies QoS by zero loss, worst-case delay, and maximum difference between delays of any two packets. GoS metrics includes flow request blocking probability and flow setup delay specified as delay-jitter is defined as the difference between delays of any two packets. A statistical quantile. The service-level specification (SLS) is part of the service-level agreement (SLA) negotiatedat flow set up. The contents of the SLS include the essential QoS-related parameters, including scope and flow identification, traffic conformance parameters, and service guarantees [28]. Specifically, the traffic conformance parameters include five parameters: the peak rate p (bytes/s), maximum burst size b (bytes), mean rate r (bytes/s), minimum policed unit m (bytes), and maximum packet size M (bytes).
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Figure 3.1: Resource management policy
3.4 Resource Management PolicyThe resource management policy relies on a relationship between three models: traffic model, network model, and performance model, see Figure 3.1. To enable effective and efficient control of network resources (router CPU and buffer capacities, link capacities) all these models need to be sufficiently accurate but also simple enough to limit the delay for processing of flow requests.
3.4.1 Traffic model
A realistic traffic model is a prerequisite for accurate performance evaluation. The traffic model consists of five layers: physical network, virtual network, call, burst, and packet layers [29], see Figure 3.1. Internet traffic measurements and advancements in modeling the last two decades have revealed that traffic arrivals on all five layers could be self-similar. This means the statistical variability in the arrival process carries over from small to larger time scales. Likewise, the traditional models for call holding times used in telephone networks are not adequate for some significant Internet services.
3.4.2 Network model
We adopt the TE and QoS optimization network model outlined by Ash: [30].
• Physical network (PN) implemented by optical cross connects and fibers;
• Virtual networks (VNs) implemented by GMPLS;
• IP transport within each VN implemented by MPLS; and
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• Differentiated services.
Diffuser manages aggregates of flows to achieve scalability. The per-hop-behavior (PHB) of the aggregate flow defines its scheduling treatment in the routers 1 and the traffic conditioning rule at ingress and egress boundary nodes. We assume the network runs the IP/MPLS [31] or IP/ATM protocols [32]. MPLS is a technology that integrates label-swapping paradigm with network-layer routing. The Label Switching Router (LSR) has the same function as the ATM switch. The LSP between two routers can be the same as the layer 3 hop-by-hop route, or the sender LSR can specify an explicit route for the LSP. LSPs in MPLS networks are similar to Virtual Channel Connection (VCCs) in ATM networks. Traffic engineered (TE) LSPs in MPLS networks correspond to Virtual Path Connections (VPCs) in ATM networks. TE-LSPs carry multiple LSPs in MPLS networks. VPCs carry multiple VCCs in ATM networks.
3.4.3 Performance model
The choice of performance model involves an accuracy-simplicity dilemma. The model needs to be both accurate and simple. High accuracy is desired to admit correct and efficient control/allocation decisions. High simplicity (low computational complexity) is required since decisions should be made fast enough to be acceptable by the users. To obtain a solution feasible in real-time, approximations are normally introduced. However, this will reduce the network utilization and thereby the revenue for the network operator.
3.5 Hierarchical Resource Management ModelHierarchical layers of dynamic resource management are performed at decreasing time scales, see Figure 3.5.2. Resource management at the higher layer aims at providing sufficient performance at the lower layer. Resource management at each layer can be done at regular time intervals or be triggered by changes in traffic or capacity at the higher layer.
Figure 3.2: Hierarchical traffic mode
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3.5.1 Physical and virtual network layer
We assume a set of virtual networks (VNs) overlay the physical domain network. A VN consists of a set of VN nodes interconnected by a set of VN links. The topology of the VN may be different from the physical network topology. A VN link defines a path (consisting of one or more physical links) between two VN nodes. The Virtual Path (VP) concept may be used in IP/MPLS and IP/ATM networks [33].
A VP provides transport of TE-LSP and carries multiple LSPs. A series of VN links defines the VP routing path. On the packet layer, the division of physical link capacity among multiple VNs is efficiently handled by the WFQ packet scheduler due to its sharing and isolation capabilities. On the call layer, the division of physical link capacity can be implemented by complete sharing, complete partitioning or partial sharing.
Network design is a crucial function in our TE framework. The design is carried out on the physical network, virtual network and call layer. Design on the physical and virtual network layers determines the topology and the set of link capacities. Physical network design is carried out on the long-term time scale. Virtual network design is carried out on multiple times [34].
• Successive capacity reallocation redistributes capacity on a fixed virtual network topology;
• Successive topology reconfiguration establishes and/or tears down TE-LSPs, within an Existing virtual network topology;
• Global reconfiguration consists of both global capacity reconfiguration and global topology reconfiguration. This activity potentially affects all the TE-LSPs in the network;
• Long-term planning derives a static (or general) set of TE-LSPs and initial or minimum Capacity assignments for them.
Successive capacity reallocation relies on policies for set up and teardown of TE-LSPs, and the policy for routing of the new TE-LSPs [35].Constraint-based routing selects a network path in the physical network for the TE-LSP subject to a set of constraints[36] Constraint based routing generalizes QoS routing by finding routes for traffic trunks instead of micro flows.
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Figure 3.3: Hierarchical resource management model
3.5.2 Call layer
Multi-constrained optimal path problem
QoS routing can be modeled as a multi-contained optimal path (MCOP) problem. We formulate the MCOP problem as follows [37]. Let G (V,E) denote a network topology, where V is the set of nodes and E is the set of links. The origin and destination nodes are denoted s and d, respectively. The number of QoS measures is denoted by m. Each link is characterized by an m-dimensional link weight vector, consisting of m nonnegative QoS weights as components. Stochastic QoS weights are represented by a probability distribution function. Deterministic QoS weights are represented by a constant value. QoS measures can be classified into additive (e.g. cost, delay), concave (e.g. bandwidth, policy flags) or multiplicative (e.g. loss). In case of an additive deterministic measure, the QoS value of a path is equal to the sum of the corresponding weights of the links along the path. In case of an additive stochastic measure, the QoS value of a path is equal to the mathematical convolution of per-link QoS distributions. For a concave measure, the QoS value of the path is the minimum (or maximum) link weight along that path. A multiplicative measure can be transformed into an additive measure by taking the logarithm. In
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general, concave measures can easily be dealt with by pruning from the graph all links that do not satisfy the requested QoS constraint. Additive measures cause more difficulties.
Definition 1: Multiconstrained path (MCP) problem: Consider a network G(V,E).Each link (u, v) 2 E is associated with m additive weights wi(u, v) _ 0, i = 1, . . . ,m. Givenm constraints Li, i = 1, . . . ,m, the problem is to find a path P from s to d such that:
For i = 1, . . . ,m. A path obeying the above condition is said to be feasible. Note that there may be multiple feasible paths between s and d. A modified (and more difficult) version of the MCP problem is to retrieve the shortest “length” path among the set of feasible paths. This problem is known as the multi-constrained optimal path problem, and is attained by adding a second condition on the path P definition 1: l(P) _ l(Q) for any feasible path Q between s and d, where l(˙) is a path length (or cost) function.
3.5.3 Burst and packet layer
Packet scheduling
The routers are assumed to be non-blocking, i.e. when packets arrive at an input link, they can be routed directly to the appropriate output links without switching conflicts. Packet destined for different output links do not interfere with each other, and queuing occurs only at the output ports of the router. The service disciplines deployed at the output links allocate three types of resources: bandwidth (which packets get transmitted), promptness (when those packets gets transmitted) and buffer space (which packets gets discarded). The bandwidth, promptness and buffer allocation policy affects, in turn, the QoS parameters loss, delay, jitter and throughput.The packet scheduling schemes deployed at the output links at the routers must be able to support multiple service classes. Possible schemes include First-Come-First-Served (FCFS), Strict Priority (SP), Weighted Fair Queuing (WFQ), and Earliest Deadline First (EDF)[36].FCFS, SP, WFQ, and EDF provide long-term bandwidth guarantees. However, the WFQ scheme has the advantage of also giving a short-term bandwidth guarantee, given by the class weight, to each class. The isolation means that less jitter is introduced in the output packet stream.
FCFS, SP and WFQ are known to be suboptimal in comparison to EDF scheduling, for both deterministic and statistical end-to-end guarantees [37].To implement EDF a complex sorting mechanism is required [38]. PGPS is often preferred over EDF due to its simplicity. However, optimal GPS scheduling requires dynamic re-synchronization of bandwidth weights which is considered costly in switches of today [39].
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The ideal GPS scheme assumes packets are infinitesimally divisible and that the server can serve multiple packets simultaneously. The WFQ scheme has a server that serves the packets from the backlogged sessions in the order of service completion under the GPS scheme, or equivalently, bit-by-bit round robin. For the WF2Q discipline, the server does not consider all the backlogged packets; rather it considers only those packets that have already started service, and possibly finished, under GPS. WF2Q is the most fair packet-by-packet scheduler known.In the WFQ and WF2Q disciplines, computing the tag for selecting the next packet to be transmitted may be too complex for high speed networks. The Self-Clocked Fair Queuing (SCFQ) and Start-Time Fair Queuing (SFQ) are approximate methods computing such a tag in an simple but less fair manner [38].
In Class Based Queuing (CBO) the priority level of each packet selects a dedicated scheduler which can be of any type. Floyd and Van Jacobsen used a modified deficit version of Weighted Round Robin (WRR) [40], while Millet and Mammary used WFQ [41]. Parekh and Gallagher analyzed the worst case delay in an network with PGPS schedulers and leaky-bucket constrained session flows [42]. The worst case end-to-end delay was found to be a sum of per-link delay metrics. Quintiles of the end-to-end delay distribution, for statistical delay and jitter guarantees, can be computed by convolution of per-link queuing delay distributions.
Buffer allocation
There are basically three types of buffer allocation schemes [43]; complete partitioning (CP), complete sharing (CS), and partial sharing (PS). It has been shown that, e.g. [44], under a relatively balanced input condition, the CS scheme can achieve a lower blocking probability than the CP scheme. When the inputs are unbalanced, however, the buffer space may not be efficiently used by the users. The PS scheme provides a good trade-off between buffer utilization and loss probabilities among the users.
3.5.4 Modeling of burst traffic
Recent studies of high-quality, high-resolution traffic measurements have revealed a new phenomenon with potentially important ramifications to the modeling, design, and control of multi-service networks. These include an analysis of hundreds of millions observed packets over an Ethernet LAN in a R & D environment at Bell core [45], an analysis of few millions of observed frame data generated by VBR video services [46]. In these studies, the packet arrival process appears to be statistically self-similar.
A self-similar (or fractal) phenomenon exhibits structural similarities across a wide range of time scales. In the case of packet traffic, self-similarity is manifested in the absence of natural length of a burst: at every time scale ranging from a few milliseconds to minutes to hours, similar-looking traffic bursts are evident. Taqqu, Willinger and Sherman showed in [45] that the superposition of many ON/OFF sources whose ON periods and OFF periods exhibit the Noah effect (i.e. have high variability or infinite variance) produces aggregate network traffic that features the Joseph effect (i.e. is self-similar or long-range dependent).
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The superposition converges after scaling to fractional Brownian motion (FBM), as the number of users tends to infinity.
3.6 QoS Evaluation
3.6.1 Link QoS models
The fluid flow queuing model captures the behavior of burst scale congestion. Hence, performance measures derived from the fluid flow queuing model are accurate in the case of large buffers. For smaller buffer sizes, the queue analysis should be performed assuming Markovmodulated Poisson process (MMPP) packet arrivals. The MMPP queuing model captures the behavior of both packet and burst scale congestion. The original fluid flow model for the FCFS queue with constant service rate was proposedby Kosten [47] and further developed by Anick, Mitra and Sondhi. The model has been extended to handle producers and consumers coupled by a buffer by Mitra, rate-based congestion control by Elwalid and Mitra, service priorities by Elwalid and Mitra, Kulkarni and Gautam, loss priorities by Elwalid and Mitra, and GPS scheduling by Presti, Zhang, and Towsley. The tradional assumption in fluid flow models is exponentially distributed activity periods. Recently, a fluid flow model for the FCFS queue with heavy-tailed activity-period distributions was proposed Boxma and Dumas. Borst et al., Jelenkovic et al, Pereira et al. and Kotopoulos et al. analyzed the GPS system fed by heavy-tailed ON/OFF fluid sources. Nagaraja, Kurose and Towsley and Baiocchi et al [48] approximated the superposed arrival process by a two-state MMPP. Nagaraja, Kurose and Towsley calculated the MMPP parameters by matching of statistical moments. Baiocchi et al. applied a method called asymptotic matching to obtain the MMPP parameters. Both papers analyzed the multiplexer performance using a MMPP/D/1/K queuing model.
End-to-end QoS models
Lelarge et al. derived results on the asymptotic tail distribution of end-to-end delay in networks of queues with self-similar (FBM) cross traffic [49]. Approximative results for the packet delay variation are outlined by Korpeoglu et al. [50]. Ying et al. analyzed the change in burstiness as the flow traverses multiple hops. The performance distortions at each node were found the be legibly small: around 1% for mean delay and 5 % for overflow probability [51].
3.6.2 Grade of Service models
End-to-end GoS models
End-to-end GoS models for loss networks operating under Least Loaded Routing (LLR) or Markov Decision Process (MDP) routing, with Poisson flow arrival processes to the OD pairs, and exponentially distributed flow service times, have been proposed in [52] and [53], respectively. The end-to-end GoS measures are obtained by solving a set of Erlang fixedpoint equations, also called reduced load approximation. Besides the flow traffic model and the network capacity model, the routing algorithm strongly affects the end-to-end GoS model.
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3.7 CAC and RoutingMDP-based QoS routing
State-dependent link costs can be determined from a Markov decision process (MDP) model of the the flow-level behavior of each link. With MDP-derived costs, the network is able select hop-by-hop or explicitly routed paths that maximize the long-term operator revenue. MDP routing has recently been applied to per-flow QoS routing with on-demand flow set up and/or delayed flow set up. Lea evaluated MDP-based QoS routing for on-demand flow set up for IntServ domain networks [54]. Chang studied MDP-based QoS routing for on demand flow set up for ATM networks with three level PNNI hierarchy [55]. We analyzed MDP-based QoS routing with mixed on-demand and delayed flow set up [56]. In summary, MDP-based QoS routing works as follows. First, the CACQoS function finds the set of feasible paths that satisfies the end-to-end QoS and administrative constraints of the requested flow class. Second, the routing function selects a minimum MDP cost path for the new flow. Third, the CACGoS function accepts (rejects) this choice if the minimum path cost is smaller (larger) than the expected reward from serving this flow. Numerical experiments carried out by several authors show that MDP-based routing gives higher average revenue rate than Least Loaded Routing (LLR), Event Dependent Routing(EDR), and sequential routing [57]. MDP-based routing is not implemented in any real network around the world, which is explained by the modest improvement of average revenue rate, and the theoretical complexity of algorithm. To implement MDP-based routing it makes sense to have a bandwidth broker (BB) distributed among the edge routers. The origin (edge) node is connected to a set of destination (edge) nodes via a routing network. The state of this routing network provides the basis for generic (preliminary) CAC and routing decisions for new calls between the OD-pairs. Signaling is then done along the chosen network path to check the actual state of each link (actual CAC). It is desirable that the state of the routing network is known with reasonable accuracy. The update of link states can be done periodically or driven by some event process. Paths which are lightly loaded can be evaluated as feasible without exact state information; as paths become more loaded the decision becomes more critical and the state update frequency should increase.
3.8 Network Design
3.8.1 Network topology
The second function in network design is the design of the topological structure of the network,i.e. where to place the nodes and how to interconnect them.
Harms et al. [58] studies the global topological reconfiguration problem for physical networks.For ATM and MPLS physical networks in most cases the result of the topologicaldesign phase will lead to a partly or fully meshed backbone network structure.
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Anjali et al. have proposed a successive topology reconfiguration policy for the VN MPLS network. Srikitja et al. analyze the global topological reconfiguration problem for VNsover MPLS [59].
3.8.2 Network link capacitiesGroskinkky et al. propose a method for successive capacity reallocation based on analysis of a time-dependent loss queueing system . Global capacity reconfiguration determines, given the network topology, traffic demand and GoS requirements, the capacities of the physical and virtual network links. The objective used in design of link capacities in virtual and physical networks can be of several types. Two common examples are maximization of the average revenue rate and minimization of total network link cost. The GoS constraints for each flow class are expressed in an absolute or relative manner. The global capacity reconfiguration task can be formulated as an optimization problem with non-linear objective function subject to a set of non-linear constraints. The optimization task requires a model of the network GoS, which besides from the traffic and capacity model, also depends on the CAC and routing policy.
3.9 Delay SystemsClass of telecommunication networks, such as data networks, places the call or message arrivals in a queue in the absence of resources, and services them as and when resources become available. Servicing is not taken up until the resource becomes available.
Such systems are known as delay systems which are also called lost call delayed (LCD) systems.
Delay systems are analyzed using queuing theory which is sometimes known as waiting line theory.
Although the foundations of queuing theory were laid by early Tele-traffic researchers, the theory now-a-days used for the analysis of a wide variety of applications outside telecommunications.
Examples of delay systems in telecommunications include the following:
Message switching Packet switching Digit receiver access Automatic call distribution Call processing.
The element of a queuing system is shown in figure. There is a large population of sources that generate traffic or service requests to the network.
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Offered traffic Source Queue
Figure 3.4: Elements of a queuing system
This is a service facility that contains a number of identical servers, each of which is capable of providing the desired service to a request. When all the servers are busy, a request arriving at the network placed in a queue until a server become available. While analyzing queuing systems, we have to deal with a number of random variables such as the number of waiting request, interarrival times between requests, and spent by a request in the system. Some of the important variables associated with a queuing system. The number of requests present in the system or the state of the system is given by the sum of the requests in the queue and those being served. No request can be pending in the queue unless all the servers are busy.
A queued operation enables better utilization of servers than does a loss system. Queuing has the effect of smoothing out the traffic flow as far as servers are concerned. Peaks in the arrival process build up the queue lengths. Since there is no statistical limit on the number of arrivals occurring in a short period of time, there is a need for infinite queuing capacity of there were to be no loss of traffic. In a particular system, only finite queue capacities are possible and hence there is a probability, however small it may be, of blocking in delay systems [60].
3.10 Application of Tele-traffic Engineering
3.10.1 In PSTN architectures
The measurement of traffic in a public switched telephone network (PSTN) allows network operators to determine and maintain the quality of service (QoS) and in particular the grade of service (GoS) that they promise their subscribers. The performance of a network depends on whether all origin-destination pairs are receiving a satisfactory service.
Server 1
Server 1
Server R
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Networks are handled as:
loss systems where calls that cannot be handled are given equipment busy tone or Queuing systems where calls that cannot be handled immediately are queued.
Congestion is defined as the situation when exchanges or circuit groups are inundated with calls and are unable to serve all the subscribers. Special attention must be given to ensure that such high loss situations do not arise. To help determine the probability of congestion occurring, operators should use the Erlang formulas or the Engset calculation.
Exchanges in the PSTN make use of trunking concepts to help minimize the cost of the equipment to the operator. Modern switches generally have full availability and do not make use of grading concepts.
Overflow systems make use of alternative routing circuit groups or paths to transfer excess traffic and thereby reduce the possibility of congestion.
A very important component in PSTNs is the SS7 network used to route signaling traffic. As a supporting network, it carries all the signaling messages necessary to set up, break down or provide extra services. The signaling enables the PSTN control the manner in which traffic is routed from one location to another..
Transmission and switching of calls is performed using the principle of time-division multiplexing (TDM). TDM allows multiple calls to be transmitted along the same physical path, reducing the cost of infrastructure.
3.10.2 In call centers
A good example of the use of teletraffic theory in practice is in the design and management of a call center. Call centers use teletraffic theory to increase the efficiency of their services and overall profitability through calculating how many operators are really needed at each time of the day.
Queuing systems used in call centers have been studied as a science. For example completed calls are put on hold and queued until they can be served by an operator. If callers are made to wait too long, they may lose patience and default from the queue (hang up), resulting in no service being provided.
3.10.3 In broadband networks
Teletraffic Engineering is a well-understood discipline in the traditional voice network, where traffic patterns are established, growth rates can be predicted, and vast amounts of detailed
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historical data are available for analysis. However, in modern broadband networks, the teletraffic engineering methodologies used for voice networks are inappropriate [61].
3.10.4 Long-tail traffic
Of great importance is the possibility that extremely infrequent occurrences are more likely than anticipated. This situation is known as long-tail traffic. In some designs, the network might be required to withstand the unanticipated traffic.
3.11 Different Traffic Parameters for WiMAX
3.11. 1. Alexa Rank:
In simple terms, Alexa Traffic Rank is a rough measure of a website's popularity, compared with all the others out there on the internet, taking into account
1. The number of visitors and 2. The number of pages viewed on each visit.
Alexa collects traffic data on a daily basis from millions of users who have installed the Alexa toolbar, and other sources, and then uses a complex mathematical formula on three months’ worth of data to arrive at the ranking for each site.
This can be interpreted as the website’s position in a massive league table based on both visitor numbers and the number of pages viewed by each visitor. The ‘most popular’ site is given a rank of 1, the second ‘most popular’ a rank of 2, and so on down to the millions of websites that receive relatively few visitors [62].
3.11. 2. Load Time
The role of load metric in load balancing algorithms is to estimate whether a system is balanced or not. Hence, it should be able to describe the load situation of the system accurately regarding to the utilization of shared resources. The shared resources in the radio link of an OFDMA system, such as WiMAX networks are time, frequency, and power. The consumption of these resources depends on the transmission power and the modulation and coding scheme (MCS) Load metric has been defined in several ways based on the features of the networks. The most common metrics which were used in traditional cellular networks are the number of calls and the probability of call blocking, while packet loss, throughput and delay were used in wireless networks such as wireless LAN (WLAN) [63].
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3.11. 3. Page Rank
PageRank is an algorithm used by Google Search to rank websites in their search engine results. PageRank was named after Larry Page, one of the founders of Google. Page Rank is a way of measuring the importance of website pages. According to Google:
“PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites” [64].
3.11. 4. SEO Rank
Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a search engine's "natural" or un-paid ("organic") search results. In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine's users. SEO may target different kinds of search, including image search, local search, video search, academic search, news search and industry-specific vertical search engines.
As an Internet marketing strategy, SEO considers how search engines work, what people search for, the actual search terms or keywords typed into search engines and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content, HTML and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic.
The plural of the abbreviation SEO can also refer to "search engine optimizers", those who provide SEO services [65].
3.11. 5 Home Page Link
Main page of a website which gives detailed information on its owner and provides links to its other parts. Usually it is the first page seen by every visitor, but some sites (such as those of newspapers or portals) display a fresh page every day, custom-tailored to the individual visitor's preferences [66].
3.11.6 Indexed Page Link
Indexed page link means how many subpages are included in search engine. It mentioned that:
Only pages can be indexed. A large collection of indexed pages can give the impression of authority to search engines. Websites with large amounts of content and indexed pages are often ranked better than small sites [67].
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3.11.7 Website with Similar Rank
A ranking is a relationship between a set of items which are measured based on particular characteristics.
3.11.8 Social Network Analysis
Social network analysis (SNA) is the analysis of social networks. Social network analysis views social relationships in terms of network theory, consisting of nodes (representing individual actors within the network) and ties (which represent relationships between the individuals, such as friendship, kinship, organizations, sexual relationships, etc.)These networks are often depicted in a social network diagram, where nodes are represented as points and ties are represented as lines [68] [69].
3.11.9 Page View per User Daily
Page views measure the number of pages viewed by Alexa Toolbar users. Multiple page views of the same page made by the same user on the same day are counted only once. The page views per user numbers are the average numbers of unique pages viewed per user per day by the users visiting the site. The page view rank is a ranking of all sites based solely on the total number of page views (not page views per user). The three-month changes are determined by comparing a site's current page view numbers with those from three month ago.
Page views per million indicates what fraction of all the page views by toolbar users go to a particular site. For example, if yahoo.com has 70,000 page views per million, this means that 7% of all page views go to yahoo.com. If you summed the fractional page views over all sites, you would get 100% (this is not true of reach, since each user can of course visit more than one site) [70].
3.11.10 Similar Website
The word similar means having a general likeness or resemblance, having some or all of the same characteristics. In geometry, it means that a polygon has the same angles and relative dimensions as another polygon, although they may differ in scale [71].
Similar website means, which websites contain one or more categories which are similar with each other.
3.11.11 Backward Link
A backward link is a link from another website that links to your website.
One of the most important aspects to SEO optimization is getting good quality, relevant backward links. In fact, Google values the worth of a web page by the number of links coming into it - (inbound links). This is perhaps a little simplistic as Google also looks at a number of other factors including:
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The worth of the page that has your link on it - if that page has a high PageRank then the link is worth more
The content of the page linking to you - is this information relevant to your website
The content of your web page
In other words, if your site is about cell phones and you have a link coming into it from a site on cell phone accessories with a high PageRank then that is a boost in value for your site. On the other hand, if you have a link coming in from a website about dog training then the relevancy of the content is not there and Google will most likely not value this link as highly as it would the first link [72].
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Chapter 04
WiMAX Traffic Analysis, Results and Discussion
The goal of this chapter is to highlight and analyze traffic parameters of Worldwide Interoperability for Microwave Access (WiMAX) for different time period considering various perspectives. We collect the data traffic of a renowned and popular WiMAX provider Company of Bangladesh. Then the data are represented graphically and analyzed.
4.1 Analysis of Different Traffic Parameters for WiMAXHere we consider different traffic parameters for WiMAX like:
1. Alexa Traffic Rank.2. Load Time.3. Page Rank.4. SEO Rank.5. Home Page Link.6. Indexed Page Link.7. Website with Similar Rank.8. Social Network.9. Page view per user daily.10. Similar website.11. Backward link.
The data are collected from a popular WiMAX provider company of Bangladesh. This information’s are taken into account for different time periods considering various situations of real world application like Bangladesh. Also traffic analysis is done for different countries. The traffic parameters are described in chapter 3. Here we represent the tables and the graphs of those parameters based on data.
4.1.1. Alexa Traffic Rank
Here we observe the quality of visitors for a particular time being using WiMAX for different countries with the almost same Alexa ranking. A low rank means that this website gets lots of visitors.
Here we represent the tables and the graphs of those parameters based on data collected from a well-known WiMAX provider company Of Bangladesh.
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Here Alexa Traffic is analyzed for 7(Seven) days. The values are collected daily basis and the values and graph are given to the flowing table 4.1. and figure 4.1..
Table 4.1: Daily Basis Global Alexa Traffic Rank (7 Days)
Day User
Day 01 [27Feb,14] 20400
Day 02 [28Feb,14] 18000
Day 03 [1Mar,14] 14400
Day 04 [2Mar,14] 13000
Day 05 [3Mar,14] 17600
Day 06 [4Mar,14] 17600
Day 07 [5Mar,14] 20600
Day 01 [2
7Feb,14]
Day 02 [2
8Feb,14]
Day 03 [1
Mar,14]
Day 04 [2
Mar,14]
Day 05 [3
Mar,14]
Day 06 [4
Mar,14]
Day 07 [5
Mar,14]
0
5000
10000
15000
20000
25000
User
User
Figure 4.1: Daily Global Alexa Traffic Rank Graph.
From the graph, the maximum Value is 20600 in day 7(5March,2014) and the minimum value is 13000 in day 4(2March,2014). Average value is 17371. The trend is initially increasing and then it gradually decreasing.
Also comparative analysis of Alexa traffic rank has been done for three different countries like Bangladesh, United State,India.
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Table 4.2 : Country basis Alexa Traffic rank.
Country Name Rank
Bangladesh #70
United States #127,773
India #223,860
Bangladesh United States India0
50000
100000
150000
200000
250000
70
127773
223860
Figure 4.2: Graph of Country basis Alexa Rank.
Here low value is #70 for Bangladesh which means that it provides the better performance, as low rank means that website gets lots of visitors.
4.1.2 Website load time
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Website load time is the time required for website visitors open, the less load time and means to open the site faster.
The website from Nov’11 to Feb’14 was observed which is given in Table 4.3.
Table 4.3: Monthly average website load time from 1 November, 2011 to 20 February, 2014.
Months Average load time01,Nov 2011 1.91120,nov 2011 1.56118,dec 2011 1.6606,jan 2012 1.49321,jan 2012 1.49306,feb 2012 1.27521,feb 2012 1.27506,mar 2012 1.35905,apr 2012 1.22517,may 2012 1.23425,jun 2012 1.40419,jan 2013 1.15323,mar 2013 1.20605,apr 2013 1.19206,may 2013 1.13803,jun 2013 1.13824,jun 2013 1.24301,aug 2013 1.21906,sept 2013 1.23915,nov 2013 1.23929,dec 2013 1.20215,jan 2014 1.21120,feb 2014 1.086
65
0
0.5
1
1.5
2
2.5 Average load time
Average load time
Figure 4.3: Monthly graph of Average load time.
From the above figure, it is found that visitors needs 1.086 seconds to open websites, faster than 72% of websites. The highest load time is 1.911, the lowest load time is 1.086, and the average load time is 1.31.
4.1.3 Page Rank
In this section data are collected for using Google Search Engine to evaluate the importance of a webpage.
Table 4.4: Monthly Page Rank by Google page rank.
Month Rank14,nov 2011 318,dec 2011 321,jan 2012 321,feb2012 3
20,mar 2012 319,apr 2012 317,may 2012 325,jun 2012 3
10, July 2012 325,Aug 2012 31, Sep 2012 32, Oct 2012 3
28, Nov 2012 315, Dec 2012 319,jan 2013 3
21, Feb 2013 3
66
23,mar 2013 305,apr 2013 306,may 2013 324,jun 20`13 301,aug 2013 306,sept 2013 315,nov 2013 329,dec 2013 315,jan 2014 320,feb 2014 3
14,nov 2011
06,jan 2011
06,feb 2012
06,mar
2012
20,mar
2012
19,apr 2
012
17,may
2012
11, Jun 2012
10, July
2012
1, Sep
2012
3, Nov 2
012
28, Nov 2
012
19,jan 2013
04, mar
2014
05,apr 2
013
03,jun 2013
01,aug 2
013
15,nov 2013
15,jan 2014
0
0.5
1
1.5
2
2.5
3
3.5
Rank
Rank
Figure 4.4: Graph of Monthly Google page rank.
We found this site’s Google page rank is 3. It remains same for all the time being.
4.1.4 SEO Score
SEO score is observed for different WiMAX provider companies of different countries.
Table 4.5: SEO scores of some different WiMAX provider.
Company Name Country SEO scoreBanglalion wimax.com.bd Bangladesh 55.3%
Qubee.com.bd Bangladesh 52.6%Ollo.com.bd Bangladesh 36.8%
Docomo-ne-jp-asia.mobi Japan 77%Clooe.com United States 38.9%
67
Bangla
lion wim
ax.co
m.bd[Bangla
desh]
Qubee.com.bd[Ban
gladesh
]
Ollo.co
m.bd[Bangla
desh]
Docomo-ne-jp-as
ia.mobi[Ja
pan]
Clooe.com[Unite
d State
s]0%
10%20%30%40%50%60%70%80%90%
55.00% 52.60%
36.60%
77.00%
38.90%
Figure 4.5: Graph of some WiMAX providers SEO.
From the Figure 4.5, it is found that, Docomo of Japan has highest value of 77% which means that through this site searching is more effective. Among difference WiMAX provider, Banglalion is in the top SEO score (55.3%) in Bangladesh.
4.1.5 Home Page Link
Home page link gives the detailed information on its owner and provider links to its other parts.
Here the website’s internal and external home page link from Nov’11 to Feb’14 was observed which is given in the Table.4.6.
Table 4.6: Monthly internal and external home page link. (1,nov 2011 to 20,feb 2014).
Month Internal links External links1,nov 2011 25 220,nov2011 25 218,dec 2011 25 206,jan 2011 26 221,jan 2012 26 202,feb 2012 26 2
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21,feb2012 28 206,mar 2012 28 220,mar 2012 29 205,apr 2012 29 219,apr 2012 30 23,may 2012 31 2
17,may 2012 32 21, Jun 2012 34 2
11, Jun 2012 35 225,jun 2012 34 3
10, July 2012 34 424, July 2012 34 425,Aug 2012 32 41, Sep 2012 36 42, Oct 2012 36 43, Nov 2012 34 415, Dec 2012 34 419,jan 2013 35 4
21, Feb 2013 36 423,mar 2013 35 405,apr 2013 35 406,may 2013 35 503,jun 2013 35 524,jun 20`13 35 506,sept 2013 35 515,nov 2013 37 2129,dec 2013 37 1420,feb 2014 36 25
1,nov 2011
18,dec 2011
21,jan 2012
21,feb2012
20,mar
2012
19,apr 2
012
17,may
2012
11, Jun 2012
10, July
2012
25,Aug 2012
2, Oct
2012
15, Dec
2012
21, Feb 2013
05,apr 2
013
03,jun 2013
06,sept 2
013
29,dec 2013
05
10152025303540
Internal linksExternal links
Figure 4.6: Graph of monthly internal and external home page link. (1 Nov 2011 to 20 Feb 2014).
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From the above Figure 4.6 it is found that, this site had 25 external links. The highest value is 25, the lowest value is 2, and the average is 5. This site had 36 internal links. The highest value is 37, the lowest value is 25, and the average is 32.
4.1.6 Indexed Page Link
Indexed page link means how many subpages are included in search engine. Here we observed in the Table 4.7 how many subpages are included in Google, Yahoo, and Bing from Nov’11 to Feb’14.
Table 4.7: Indexed page link
MonthIndexed Pages
1, Nov 2011 36(Google) 2688(Bing)20, Nov 2011 31(Google) 2750(Bing)18, Dec 2011 31(Google)6, Jan 2013 31(Google)
21, Jan 2012 31(Google)6, Feb 2012 31(Google)
21, Feb 2012 39(Yahoo)6, Mar 2012 40(Yahoo)
20, Mar 2012 46(Yahoo)5, Apr 2012 40(Yahoo)
19, Apr 2012 50(Yahoo)3, May 2012 46(Yahoo)
17, May 2012 53(Yahoo)1, Jun 2012 31(Google)
11, Jun 2012 31(Google)25, Jun 2012 31(Google)10, Jul 2012 31(Google)24, Jul 2012 31(Google)
25, Aug 2012 31(Google)1, Sep 2012 31(Google)2, Oct 2012 39(Yahoo)3,Nov 2012 31(Google)
15, Dec 2012 31(Google)19, Jan 2013 31(Google)15, Nov 2013 31(Google)29, Dec 2013 252(Google) 15(Bing)15, Jan 2014 252(Google) 20(Bing)20, Feb 2014 11800(Google) 16(Bing)
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Figure 4.7: Indexed page link Graph.
Here we observed from the Figure 4.7, Google had Indexed this site 11,800 pages. The highest value is 11,800, the lowest value is 31, and the average is 467. Yahoo had Indexed this site 13 pages. The highest value is 53, the lowest value is 1, and the average is 22. Bing had Indexed this site 16 pages. The highest value is 2,750, the lowest value is 5, and the average is 203.
4.1.7 Websites with Similar Rank
Here we observe the quality of visitors for a particular time being using WiMAX for different countries with the almost same Alexa ranking.
These websites which ranked between #16,922 and #16,930 on the web.
Table 4.8: Websites with similar ranke between #16,922 and #16,930.
Rank Homepage Prymary Traffic
#16,923 Kuku123.com China
#16,924 Drweb.de Germany
#16.925 Subaru.com United States
#16,926 Banglalionwimax.com Bangladesh
#16,927 Articlerich.com India
71
16,92116,92316,92516,927
16,923 16,92316,925
16,927
Figure4.8: graph of website with similar rank.
Here we observed China website [Kuku123.com] rank is #16923, Germany website [Drweb.de] rank is #16924, United States website [Subaru.com] rank is # 16925, Bangladeshi website [Banglalionwimax.com] rank is #16926, India’s website [Articlerich.com] rank is #16926. Here all are low rank website and a low rank means that this website gets lots of visitors.
4.1.8 Social Network
Here the observation is done for social reviews through a particular WiMAX provider for a particular time period (per day average) different types of social medium like Twitter, Facebook, Google+ and many more are used.
Table 4.9: Socials analysis
Social FollowsTwitter: 35
Facebook Likes: 164Facebook Shares: 731
Facebook Comments: 136Linkedin: 12Google +: 19Delicious: 33
Stumbleupon: 2Pinterest: 0
72
Twitter:
Faceb
ook Like
s:
Faceb
ook Share
s:
Faceb
ook Commen
ts:
Linked
in:
Google +:
Delicious:
Stumbleu
pon:
:0
100200300400500600700800
Follows
Follows
Figure 4.9: Graph of Socials analysis
From above graph, it is shown that maximum user follows Facebook shares and the value is 731. Others highest values are 164, 136 by Facebook likes, Facebook comments etc. the lowest value is 0 (zero) by Pinterest. Other values vary Between 35 to 12.
4.1.9 Page View per User Daily
Here daily page views per user are observed for a particular time like six months (from January’13 to June’13).
Table 4.10: Daily page view per user.
Month Daily Page Views per User
January 5
February 6
March 6
April 5
May 4.5
June 5
73
January
February
March
AprilMay June
0
1
2
3
4
5
6
7
Daily Page Views per User
Daily Page Views per User
Figure 4.10: Graph Daily page views per user.
From the graph, it is found that the trend of daily page viewing per user is almost same. The value varies between 6 and 4.5.
4.1.10 Similar Website
In this section we analyze those websites contain one or more categories like load time, Alexa rank, SEO score, homepage link etc.
We found 9 related website and they are given following Table 4.11.
Table 4.11: Similar website
Rank Website Primary Traffic#11,137,184 Dekibike.com Singapore
#1,204 Clicksor.com India#17,869,464 Ingegneriainformatica.com Italy#2,770,595 Silversmoke.eu Denmark
#584 nfl.com United States#805 Linkwithin.com United States#217 Pandora.com United States#2 Grzechhair.com Poland#2 Elmattorneys.com United States
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Dekibike
.com [S
ingapore]
Clickso
r.com [In
dia]
Ingegneri
ainform
atica.
com [It
aly]
Silvers
moke.eu
[Den
mark]
nfl.com [U
nited St
ates]
Linkw
ithin.co
m [Unite
d State
s]
Pandora.
com [U
nited St
ates]
Grzech
hair.co
m [Polan
d]0
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
14,000,000
16,000,000
18,000,000
20,000,000
11,137,184
1,204
17,869,464
2,770,595
584 805 217 2 2
Rank
Figure 4.11: Graph of similar website.
From the above graph, it is shown that, the Ingegneriainformatica.com have maximum rank is #17,869,464. The Grzechhair.com andElmattorneys.com have the lowest rank which is #2.
4.1.11 Backward Links
Here backward link analysis is done on monthly basis from Nov’11 to Feb’14 was observed which is given in the Table 4.12.
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Table 4.12: Monthly basis Backward links analysis.
Months Backward links20,nov 2011 305,apr 2012 15517,may 2012 16625,jun 2012 16219,jan 2013 16023,mar 2013 16905,apr 2013 16906,may 2013 17524,jun 2013 18301,aug 2013 18306,sept 2013 18315,nov 2013 18329,dec 2013 21515,jan 2014 21120,feb 2014 207
20,nov 2011
05,apr 2
012
17,may
2012
25,jun 2012
19,jan 2013
23,mar
2013
05,apr 2
013
06,may
2013
24,jun 2013
01,aug 2
013
06,sept 2
013
15,nov 2013
29,dec 2013
15,jan 2014
20,feb 2014
0
50
100
150
200
250
Backward links
Backward links
Figure 4.12: Graph of monthly basis Backward links analysis.
From the above figure4.1.11.1 we found this site had 207 backward links. The highest value is 215, the lowest value is 3, and the average is 159.
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Chapter 05Conclusion
WiMAX technology brought revolution in both fixed and mobile wireless communication. In present communication world, wireless communication does not mean only data and voice transmission. It also supports high data rate transmission which supports various types of service (voice, data, multimedia). Since, WiMAX supports high data rate transmission. So it can fulfill the demand of the present end users.
5.1 Concluding Remarks:In this work traffic parameters of WiMAX are highlighted and analyzed. The considering parameters are Alexa Traffic Rank, Load Time, Page Rank, SEO Rank, Home Page Link, Indexed Page Link, Website with Similar Rank, Social Network, Page view per user daily, Similar website, Backward link.
In Alexa traffic analysis , Alexa traffic is analyzed for 7(Seven) days. The values are collected daily basis and the values and graph are given. From the graph, the maximum Value is 20600 in day 7(5March,2014) and the minimum value is 13000 in day 4(2March,2014). Average value is 17371. The trend is initially increasing and then it gradually decreasing. Also comparative analysis of Alexa traffic rank has been done for three different countries like Bangladesh, United State,India. Here low value is #70 for Bangladesh which means that it provides the better performance, as law rank means that website gets lots of visitor. Website load time analysis is done from nov’11 to feb’14 where it is found that that visitors needs 1.086 seconds to open websites, faster than 72% of websites. The highest load time is 1.911, the lowest load time is 1.086, and the average load time is 1.31. Google page rank is 3 is found in page rank analysis. SEO score is observed for different WiMAX provider companies of different countries. it is found that, Docomo of Japan has highest value of 77% which means that through this site searching is more effective. Among difference WiMAX provider, Banglalion is in the top SEO score (55.3%) in Bangladesh.
Home page link analysis shows that, the detailed information on its owner and provider links to its other parts.Here the website’s internal and external home page link from Nov’11 to Feb’14 was observed. It is found that, this site had 25 external links. The highest value is 25, the lowest value is 2, and the average is 5. This site had 36 internal links. The highest value is 37, the lowest value is 25, and the average is 32. In indexed page link analysis Google had Indexed this site 11,800 pages. The highest value is 11,800, the lowest value is 31, and the average is 467. Yahoo had Indexed this site 13 pages. The highest value is 53, the lowest value is 1, and the average is 22. Bing had Indexed this site 16 pages. The highest value is 2,750, the lowest value is 5, and the average is 203.
A comparative analysis is also done for websites which ranked between #16,922 and #16,930 on the web. From comparison it is found that China website [Kuku123.com] rank is #16923, Germany website [Drweb.de] rank is #16924, United States website [Subaru.com] rank is #
77
16925, Bangladeshi website [Banglalionwimax.com] rank is #16926, India’s website [Articlerich.com] rank is #16926. Here all are low rank website and a low rank means that this website gets lots of visitors. Social Network analysis show that the maximum user follows Facebook shares and the value is 731. Others highest values are 164, 136 by Facebook likes, Facebook comments etc. the lowest value is 0 (zero) by interest. Other values vary Between 35 to 12. Page view per user daily analysis gives the result that the trend of daily page viewing per user is almost same. The value varies between 6 and 4.5. Among the similar websites, comparative study is done for different countries which shows that the Ingegneriainformatica.com have maximum rank is #17,869,464. The Grzechhair.com and Elmattorneys.com have the lowest rank which is #2. Finally backward link are taken into account and term this it is found that the site had 207 backward links. The highest value is 215, the lowest value is 3, and the average is 159.
In Bangladesh, three companies are providing WiMAX service namely Banglalion wimax, Qubee and ollo. Their growth rate is 178 percent and number of visitors 200,000 more. Bangladesh Telecommunication Regulatory Commission (BTRC) had already gives WiMAX license at year 2008. In the world many WiMAX company Provide WiMAX service. Among them Dokomo from Japan is in the top position.
Wi-Fi system is widely being used in the first world countries. WiMAX embedded devices support the Wi-Fi standards. So the people who are using Wi-Fi can easily switch to WiMAX technology. Moreover in the developing countries where high data rate wireless communication infra-structure is not strong enough. WiMAX can be a good solution for these countries which is more secured, reliable and cheap. For these reasons the user of this technology is increasing day by day. As WiMAX is the latest technology and better solution in the wireless communication world, we have chosen this technology for our thesis.Design a security system based on WiMAX technology.
5.2 Future Scope1. Traffic analysis of different WiMAX providers of Bangladesh.2. Traffic analysis of WiMAX providers between rural and urban area.3. Traffic analysis of WiMAX providers between different environments.4. Traffic analysis of WiMAX providers between worldwide WiMAX Providers Company.5. Establishment of LTE (Long Term Evolution) & their traffic analysis.
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