proposed comparative study of qos in lte vs. 2g & 3g networks

7/28/2019 Proposed Comparative Study of QoS in LTE vs. 2G & 3G Networks

1/8

PROPOSAL

Title: Comparative Study of QoS in LTE vs. 2G & 3G Networks

ABSTRACT

Telecom networks have increasingly become the network choice for communication in an ever-

growing globalized world. However the technology is fraught with a lot of cons. Due to the ever

evolving nature of the technology underlying telecom networks still has a lot of issues relating to

quality which needs dealing with. The core network of every network infrastructure is an area of

very high speed which amongst other things greatly determines the overhead efficiency of the

network. The quality of voice and data services is a very important area which network providers

spare no expense in trying to optimize. Quality of Service (QoS) is the term used to aggregate the

overall performance of a network. For telecom networks to be very efficient, one of the very

important issues needed to be dealt withby the network provider is QoS at the aggregate end of

the network.

A model was developed which was used to compare three very important networking

technologies; LTE, 2G & 3G, with a view of developing benchmarks which will be used by

network engineers and scientists to deploy solution technology at the core end of the network

with the ultimate aim of providing optimal QoS infrastructures at the core.


2/8

INTRODUCTION

1.1 OverviewIn practice, the term telecommunication covers all form of distance and conversion of the

original communication including radio, telephony, telegraphy, television, data communication

and computer networking. People often separate the communication of voice and data into two

categories, using the term telecommunications to denote the transmission of voice signals and data

communication to refer to the transmission of data signals (Cole, 2000). But generally, voice

communication, data communication, and video communication all belong to the larger group or

classification: telecommunication.

The rapid growth of telecommunication networks has been witnessed from new services and

emerging technologies in the past years especially data related services. As social and business

activities rely increasingly on wireless communications, wireless access networks become

crucial to providing the mobile users with un-tethered access to resources that reside primarily in

data-only networks (e.g., the Internet, etc.). Typical telecom networks only provide voice-related

services.

The increasing popularity of data technology indicates that telecom network links will play an

important role in future inter-networks. 3G network is the most commonly available type of

telecom transmission and backhaul network in existence today. TCP and Time Division


3/8

Multiplexing (for 2G networks) are the ubiquitous transport protocol used in the telecom world.

TCP is a reliable transport protocol that is used to support applications like telnet, ftp and http. It is

tuned to perform well in habitual networks made up of links with low bit-error rates. It runs above

the connectionless Internet Protocol (IP) layer and provide a connection oriented end-to-end

reliable delivery of application data. TCP was originally designed for wired networks, where loss

of data is assumed to be due to congestion. A future model such as LTE seeks to increase the

capacity and speed of wireless data networks using newer signal processing and modulation

techniques based on an all-IP network.

Networks with wireless and other lossy links also suffer from significant losses due to high bit

error rates and handoff. But the assumption made by TCP, that loss of data is due to congestion in

wireless environment causes degraded end-to-end performance. Hence a variety of mechanisms

were proposed to improve TCP performance over wireless links. The proliferation of wireless

networks into more complex environments has introduced many new demands upon the existing

wireless protocols.

Wireless systems are being asked to function in multiple types of environments. Currently there

are two distinct types of wireless networks: cellular and ad-hoc. Although improvements have

been made to both wireless models allowing them to function well in specific environments,

neither system is presently robust enough to satisfy the demands of all environments. (Kevin,

2000)

With emerging telecom network technologies, handheld devices and laptops have become very

common. Most of these devices interconnect using wireless links. Some of the applications

running on these devices require reliable data transfer. Transmission Control protocol (TCP) is


4/8

the most widely accepted reliable, connection-oriented, full duplex, byte stream transport level

protocol that is in use today (Stevens, 1994). It is an end-to-end protocol in telecom networks

that support flow and congestion control.

There are millions of network applications that have already been built on top of TCP and will

continue to be in the foreseeable future. It is important to improve its performance in wireless

networks without any modification to the application interface provided by TCP on fixed hosts.

This is the only way by which mobile devices communicating on wireless links can seamlessly

integrate with the rest of the Internet.

Network congestion occurs when offered traffic load exceeds available capacity at any point in a

network. In wireless networks, congestion causes overall channel quality to degrade and loss

rates to rise, leads to buffer drops and increased delays (as in wired networks), and tends to be

grossly unfair toward nodes whose data has to traverse a larger number of radio hops.

Congestion control in wired networks is usually done using end-to-end and network-layer

mechanisms acting in concert. However, this approach does not solve the problem in wireless

networks because concurrent radio transmissions on different links interact with and affect each

other, and because radio channel quality shows high variability over multiple time-scales.

Usually, a central tenet of the current Internet architecture is that congestion control is performed

mainly by TCP at end hosts. However, as new applications (which may not deploy TCP for

congestion control), e.g. continuous media applications, become widely deployed on the Internet,

it becomes difficult, if not impossible, to exclusively rely on end hosts to perform end-to-end


5/8

congestion control. It has been agreed upon that the network itself must now participate in

congestion control and resource management.

1.2 Statement of the ProblemThe next generation telecommunication networks are posited to support large scale data

applications. Implementing end-to-end TCP in such networks faces two problems. First, it is well

known that TCP cannot distinguish packet losses due to link failures and that due to network

congestion. Second, TCP congestion control mechanism does not deal effectively with large

amount of out-of-order packet retransmissions; this problem has actually received less attention

in past literatures and research works.

Therefore, this project work presents a more effective mechanism that deals with the second

problem of retransmission of large amount of out-of-order packets.

1.3 Aims and ObjectivesThe aim of this project work is to carry out a performance evaluation using QoS metrics such as

TCP throughput and more over wireless links within LTE networks and 2G & 3G networks. The

specific objectives are therefore:

To simulate this new LTE-TCP congestion control model that takes care of the inherentproblem of the present existing algorithms.

To compare the performance of this model with existing TCP congestion control modelssuch as those used in current 2G & 3G networks.


6/8

1.4 MethodologyWith the research objectives in perspective, the execution of this study is divided into phases as

follows:

Reviewing existing TCP models and algorithms and taking note of their limitations Modifying both the sender and the receiver Class Agent and other related files. Simulation of this modified model using NS-2 simulator under Linux environment Performance comparison of the future LTE model with existing 2G & 3G schemes.

Congestion in this project is going to be monitored at the aggregate base station. This therefore

has to do with congestion as a result of traffic flow between the aggregate base station and the

radio base stations. It is a state of congestion recovery from an already congested network and

making sure that after retransmitting lost packets, the congestion state is recovered from in the

state of large out-oforder packets. This is how the design works.

1.5 Scope of ResearchThe performance of TCP depends on its congestion control mechanisms for packet loss

experience in the network. The congestion control mechanism for congestion losses is not very

effective for corruption losses, which are more prevalent in wireless networks. However, this

work is limited to proving that the future LTE mechanism is more effective and reliable for

dealing with large amount of out-of-order packet retransmission.


7/8

It however, does not offer a solution to the first problem of TCP not being able to distinguish

between packet losses due to link failures and that due to network congestion. The problem is

however described.

1.6 JustificationThe assumption that statistical multiplexing can be used to improve the link utilization is that the

users do not reach their peak rate simultaneously, but since the traffic demands are stochastic and

cannot be predicted, congestion is usually termed to be unavoidable. Each of this has their own

limitations and hence the need for the desire of better and more efficient congestion controls

algorithms with greater throughput.

Whenever the total input rate is greater than the output link capacity, congestion occurs. When

the network becomes congested, the queue lengths may become very large in a short time,

resulting in buffer overflows and cell loss. The congestion control algorithms respond to this by

reducing the congestion window, thereby reducing the rate of flow of packets.

Implementing end-to-end TCP in such networks where large data application is desired presents

the challenge of effectively dealing with the retransmission of large out-of-order packets. This is

what this project work tends to problem. The reduction in congestion window is a necessity

when network is experiencing congestion to avoid congestion collapse on the wireless cellular

network. Congestion control is therefore necessary to ensure that users get the negotiated Quality

of Service (QoS).
http://d/wiki/Stochastichttp://d/wiki/Quality_of_Servicehttp://d/wiki/Quality_of_Servicehttp://d/wiki/Quality_of_Servicehttp://d/wiki/Quality_of_Servicehttp://d/wiki/Stochastic


8/8

1.7 Report LayoutThis entire project report is made up of five chapters. Chapter one is the introductory chapter and

it provides the necessary background on congestion on a telecommunication network, as well as

understanding TCP over wireless network. Also included in this chapter are statement of

problem, aims and objectives, and scope of research and its justification, Chapter two is the

literature review containing the TCP protocol structures, its various control algorithms and

schemes; as well as description of the various congestion control mechanism and their

limitations.

Chapter three contains the project methodology, including both model description and model

development. In Chapter four, the system design, implementation and simulation of the model,

as well as the result and model analysis are shown. Finally in Chapter five, the conclusion and

recommendation of future work on this project are presented.

proposed comparative study of qos in lte vs. 2g & 3g networks

Documents