Fundamentals of Software Development

Introduction to NetworkingCT043-3-1Wireless NetworksTopic & Structure of the lessonIntroduction to Wireless LANsBands of OperationBluetooth

2Asia Pacific University College of Technology and Innovation#Learning OutcomesAt the end of this module, YOU should be able to:

Explain the advantages and disadvantages of WLANs.

Explain the standards and implementation of IEEE802 networks.

Explain the various radio frequency spectrum and bands of operation.

Describe the standards and architecture of Bluetooth technology.

Describe the considerations and implications of implementing Bluetooth technology.

Describe the security aspects and techniques for Bluetooth technology.

3Asia Pacific University College of Technology and Innovation#Key Terms you must be able to useIf you have mastered this topic, you should be able to use the following terms correctly in your assignments and exams:

WLANsDesign goals802.11MAC addressFrequency spectrumFrequency bandsISM bandsUnlicensed bands4Asia Pacific University College of Technology and Innovation#Main Teaching PointsIntroduction to Wireless LANsBands of Operation

5Asia Pacific University College of Technology and Innovation# Introduction The global goal of WLANs is to replace office cabling, to enable connectionless access to the internet and to introduce a higher flexibility for ad-hoc communication. Some advantages of WLANs are: Flexibility Within radio coverage, nodes can communicate without further restriction. Radio waves can penetrate walls, senders and receivers can be placed anywhere. Planning Only wireless ad-hoc networks allow for communication without previous planning, any wired network needs wiring plans.

Introduction to Wireless LANs6Asia Pacific University College of Technology and Innovation# Design Wireless networks allow for the design of small, independent devices which can for example be put into a pocket. Cables not only restrict users but also designers of small PDAs, notepads etc. RobustnessWireless networks can survive disasters or users pulling a plug. Networks requiring a wired infrastructure will usually break down completely. Cost After providing wireless access to the infrastructure via an access point for the first user, adding additional users to a wireless network will not increase the cost.

Introduction to Wireless LANs7Asia Pacific University College of Technology and Innovation# However, WLANs also have several disadvantages: Quality of serviceWLANs typically offer lower quality than their wired counterparts. The main reasons for this are the lower bandwidth due to limitations in radio transmission, higher error rates due to interference, and higher delay/delay variation due to extensive error correction and detection mechanisms. Proprietary solutions Due to slow standardization procedures, many companies have come up with proprietary solutions offering standardized functionality plus many enhanced features. Restrictions All wireless products have to comply with national regulations. Several government and non-government institutions worldwide regulate the operation and restrict frequencies to minimize interference. Introduction to Wireless LANs8Asia Pacific University College of Technology and Innovation# Safety and security Using radio waves for data transmission might interfere with high-tech equipment in, e.g., hospitals. Special precautions have to be taken to prevent safety hazards. Many different, and sometime competing, design goals have to be taken into account for WLANs to ensure their commercial success: Global operation WLAN products should sell in all countries so, national and international frequency regulations have to be considered. Low power Devices communicating via a WLAN are typically also wireless devices running on battery power. The LAN design should take this into account and implement special power-saving modes and power management savings. Introduction to Wireless LANs9Asia Pacific University College of Technology and Innovation# Protection of investment A lot of money has already been invested into wired LANs. The WLANs should protect this investment by being interoperable with the existing networks. Safety and security Wireless LANs should be safe to operate, especially regarding low radiation if used e.g., in hospitals. Users cannot keep safety distances to antennas. Transparency for application Existing applications should continue to run over WLANs, the only difference being higher delay and lower bandwidth.Introduction to Wireless LANs10Asia Pacific University College of Technology and Innovation# Overview of IEEE 802.11 Networks A basic introduction is often necessary when studying networking topics because the number of acronyms can be overwhelming With 802.11 there is a host of additional background needed to appreciate how 802.11 adapts traditional Ethernet technology to a wireless world Wireless network interface cards are assigned 48-bit MAC addresses, and, for all practical purposes, they look like Ethernet network interface cards In fact, the MAC address assignment is done from the same address pool so that 802.11 cards have unique addresses even when deployed into a network with wired Ethernet stations To outside network devices, these MAC addresses appear to be fixed, just as in other IEEE 802 networksIntroduction to Wireless LANs11Asia Pacific University College of Technology and Innovation#

802.11 MAC addresses go into ARP tables alongside Ethernet addresses, use the same set of vendor prefixes, and are otherwise indistinguishable from Ethernet addresses The devices that comprise an 802.11 network (access points and other 802.11 devices) know better There are many differences between an 802.11 device and an Ethernet device, but the most obvious is that 802.11 devices are mobile ; they can easily move from one part of the network to another The 802.11 devices on your network understand this and deliver frames to the current location of the mobile stationIntroduction to Wireless LANs12Asia Pacific University College of Technology and Innovation#Bands of Operation Radio Frequency Spectrum Wireless devices are constrained to operate in a certain frequency band Each band has an associated bandwidth, which is simply the amount of frequency space in the bandBandwidth has acquired a connotation of being a measure of the data capacity of a link A great deal of mathematics, information theory, and signal processing can be used to show that higher-bandwidth slices can be used to transmit more information As an example, an analog mobile telephony channel requires a 20-kHz bandwidth. TV signals are vastly more complex and have a correspondingly larger bandwidth of 6 MHz13Asia Pacific University College of Technology and Innovation# Radio spectrum allocation is rigorously controlled by regulatory authorities through licensing processes Most countries have their own regulatory bodies, though regional regulators do exist. In the U.S., regulation is done by the Federal Communications Commission (FCC) Many FCC rules are adopted by other countries throughout the Americas. European allocation is performed by the European Radio communications Office (ERO) Other allocation work is done by the International Telecommunications Union (ITU)To prevent overlapping uses of the radio waves, frequency is allocated in bands, which are simply ranges of frequencies available to specified applications

Bands of Operation14Asia Pacific University College of Technology and Innovation# The following lists some common frequency bands used in the U.S.:BandFrequency rangeUHF ISM902-928 MHzS-Band2-4 GHzS-Band ISM2.4-2.5 GHzC-Band4-8 GHzC-Band satellite downlink3.7-4.2 GHzC-Band Radar (weather)5.25-5.925 GHzC-Band ISM5.725-5.875 GHzC-Band satellite uplink5.925-6.425 GHzX-Band8-12 GHzX-Band Radar (police/weather)8.5-10.55 GHzKu-Band12-18 GHzKu-Band Radar (police)13.4-14 GHz 15.7-17.7 GHzBands of Operation15Asia Pacific University College of Technology and Innovation# The ISM bands There are three bands labeled ISM, which is an abbreviation for industrial, scientific, and medical ISM bands are set aside for equipment that, broadly speaking, is related to industrial or scientific processes or is used by medical equipment Perhaps the most familiar ISM-band device is the microwave oven, which operates in the 2.4-GHz ISM band because electromagnetic radiation at that frequency is particularly effective for heating water 802.11 operates in the ISM bands, along with many other devices Common cordless phones operate in the ISM bands as wellBands of Operation16Asia Pacific University College of Technology and Innovation# Other unlicensed bands Additional spectrum is available in the 5 GHz range The United States was the first country to allow unlicensed device use in the 5 GHz range, though both Japan and Europe followed There is a large swath of spectrum available in various countries around the world: 4.92-4.98 GHz (Japan) 5.04-5.08 GHz (Japan) 5.15-5.25 GHz (United States, Japan) 5.25-5.35 GHz (United States) 5.47-5.725 GHz (United States, Europe) 5.725-5.825 GHz (United States)Bands of OperationBluetoothIntroductionCompared to the WLAN technologies, the Bluetooth technology discussed here aims at so-called ad-hoc piconets, which are local area networks with a very limited coverage and without the need for an infrastructureThis is a different type of network needed to connect different small devices in close proximity (about 10 m) without expensive wiring or the need for a wireless infrastructureThe Swedish IT-company Ericsson initiated some studies in 1994 and renamed to Bluetooth because of the liking for a Viking called Harald Gormsen (i.e., the King of Denmark)18Asia Pacific University College of Technology and Innovation# In 1998, five companies (Ericsson, Intel, IBM, Nokia, Toshiba) founded the Bluetooth consortium with the goal of developing a single-chip, low-cost, radio-based wireless network technologyIn 2001, the first products hit the mass market, and many mobile phones, laptops, PDAs, video camera etc. are equipped with Bluetooth technologyAt the same time wireless personal area network (WPAN) was initiated by IEEE 802.11 and addressed the following criteria:Market potential: How many applications, devices, vendors, customers are available for certain technology?BluetoothCompatibility : Compatibility with IEEE 802Distinct identity: The study group did not want to establish a second 802.11 standard. However, topics such as, low cost, low power, or small form factor are not addressed in the 802.11 standardTechnical feasibility: Prototypes are necessary for further discussion, so the study group would not rely on paper workEconomic feasibility: Everything developed within this group should be cheaper than other solutions and allow for high-volume productionUser scenariosDifferent applications of piconets or WPANs:Bluetooth20Asia Pacific University College of Technology and Innovation#Connection of peripheral devices: Today, most devices are connected to a desktop computer via wires (e.g. keyboard, mouse, etc.). This type of connection has several disadvantages: each device has its own type of cable, different plugs are needed, wires block office spaceSupport of ad-hoc networking: Students might join a lecture, with the teacher distributing data to their personal digital assistants (PDAs). Wireless networks can support this type of interaction; small devices might not have WLAN adapters following the 802.11, but cheaper Bluetooth chips built inBluetooth21Asia Pacific University College of Technology and Innovation#Bridging of networks: Using wireless piconets, a mobile phone can be connected to a PDA or laptop in a simple way. Mobile phones will not have full WLAN adapters built in, but could have a Bluetooth chip. The mobile phone can then act as a bridge between the local piconet and e.g., the global GSM networkArchitectureLike IEEE 802.11b, Bluetooth operates in the 2.4 GHz ISM band with 1 MHz carrier spacing. However, MAC, physical layer and the offered services are completely differentEach device performs frequency hopping with 1,600 hop/s in a pseudo random fashionBluetooth

SecurityBleutooth offers mechanisms for authentication and encryption on the MAC layer, which must be implemented in the same way within each device

The main security features offered by Bluetooth include a challenge-response routine for authentication, a stream cipher for encryption, and a session key generation

Each connection may require a one-way, two-way, or no authentication using the challenge-response routine

Bluetooth23Asia Pacific University College of Technology and Innovation#The following diagram shows several steps in the security architecture of Bluetooth:DataPIN (1 16 byte)E2Link key (128 bit)Encryption key (128 bit)E3Keystream generatorPayload keyCipheringEncryptionAuthenticationPairingEncryption key generationUser input (initialization)Cipher dataPIN (1 16 byte)E2Link key (128 bit)Encryption key (128 bit)E3Keystream generatorPayload keyDataBluetooth24Asia Pacific University College of Technology and Innovation#Pairing: To set up trust between the two devices a user can enter a secret PIN into both devices. This PIN can have a length of up to 16 byteAuthentication: Is a challenge-response process based on the link key, a random number generated by a verifier, and the device address of the claimant (the device that is authenticated)Encryption: Based on the encryption key (with a maximum size of 128 bits and can be individually generated), the device address and the current clock, a payload key is generated for ciphering user dataCiphering: The payload key is a stream of pseudo-random bits. The ciphering process is a simple XOR of the user data and the payload keyBluetoothCellular telephone networksThe objective of personal communication systems (PCS) or personal communication networks (PCN) is:to provide ubiquitous wireless communications coverage,enabling users to access the telephone network,enabling users to access the Internet for different communication needs. Anywhere and anytime regardless of user and information locationThe mobile and fixed networks will be integrated to provide universal access to the network and its databases A large amount of signaling will be required for efficient working of these networks

Cellular infrastructure why ??Cells with different frequencies allow devices to move between these cellsThe device just informing what frequency they are communicating atCellular communications can only travel a certain distanceCell sizes are flexibleExamples in the TUK TACS system were up to 50 Miles!

Mobile Switching CenterPublic telephonenetwork, andInternet

Mobile Switching CenterComponents of cellular network architecture connects cells to wide area net manages call setup (more later!) handles mobility (more later!)MSC covers geographical region base station (BS) analogous to 802.11 AP mobile users attach to network through BS air-interface: physical and link layer protocol between mobile and BScellwired network29Asia Pacific University College of Technology and Innovation#

Single Cell Multiple AccessComponents of cellular network architecture

correspondentMSCMSCMSCMSCMSCwired public telephonenetworkdifferent cellular networks,operated by different providers31Asia Pacific University College of Technology and Innovation#Principles of cellular networkCellular radio is a technique that was developed to increase the capacity available for mobile radio telephone service

Each cell is allocated a band of frequencies and is served by the base station, consisting of transmitter, receiver and control unit.

Each cell has a base transceiver. The transmission power is carefully controlled to allow communication within the cell using a given frequency while limiting the power at that frequency that escapes the cellinto adjacent ones.

The objective is to use the same frequency in other near by cells, thus allowing the frequency to be used for multiple simultaneous conversations.

Cellular ArchitectureAllows the area to be broken into smaller cellsThe mobile device then connects to the closest cellCellCellCellCellCellCellCellCellCellCellCellCellCellCellCellCellCellular Architecture continued

Cellular architecture requires the available frequency to be distributed between the cellsIf 2 cells next to each other used the same frequency each would interfere with each otherCellCellCellCellCellFrequency 900MHzCellular Architecture continued

There must be a distance between adjoining cellsThis distance allows communications to take place CellCellCellCellCellCellCellCellFrequency 900Frequency 920Frequency 940Frequency 960MHzCellular Architecture continued

This is referred to as the Minimum Frequency Reuse FactorThis requires proper planning and can be an issue for all radio based wireless communicationsPlanning the radio cell and how far a signal may goCellCellCellCellBorder Gateway Protocol(BGP)It is astandardizedexterior gateway protocoldesigned to exchange routing and reachability information betweenautonomous systems(AS) on theInternet.Makes routing decisions based on paths, network policies or rule-sets configured by anetwork administrator, and is involved in making coreroutingdecisions.It is the routing protocol that makes the Internet work. MostInternet service providers(ISPs) must use BGP to establish routing between one another.Most of the routers in the service provider core networks have to exchange information about several hundred thousand IP prefixes. In many cases, there will be multiple routes to the same destination. BGP therefore uses path attributes to decide how to route traffic to specific networks.The routing table contains a list of known routers, the addresses they can reach, and a costmetricassociated with the path to each router so that the best available route is chosen.Hosts using BGP communicate using the Transmission Control Protocol (TCP) and send updated router table information only when one host has detected a change.

it easy to use Classless Inter-Domain Routing (CIDR), which is a way to have more addresses within the network than with the currentIP addressassignment scheme.

Multiprotocol Label Switching(MPLS)It is a mechanism in high-performancetelecommunications networksthat directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in arouting table.In an MPLS network, data packets are assigned labels. Packet-forwarding decisions are made solely on the contents of this label, without the need to examine the packet itself. MPLS operates at a layer that is generally considered to lie between traditional definitions of layer 2 (data link layer) and layer 3 (network layer), and thus is often referred to as a "layer 2.5" protocol.MPLS allows mostpacketsto be forwarded atLayer 2(the switching level) rather than having to be passed up toLayer 3(the routing level).Each packet gets labeled on entry into theservice provider'snetwork router.All the subsequentrouting switchesperform packet forwarding based only on those labelsthey never look as far as theIP header.Finally, theISPsrouter removes the label(s) and forwards the original IP packet toward its final destination.The label determines which pre-determined path the packet will follow. The paths allow service providers to decide ahead of time what will be the best way for certain types of traffic to flow within a private or public network.the Benefits of MPLS NetworksImprove Uptime- by sending data over an alternative path in less than 50 milliseconds (if one exists). MPLS also reduces the amount of manual intervention your ISP has to do to create a WAN, reducing the likelihood of human error bringing down your circuit.

Improve User Experience- by prioritising time-sensitive traffic such as VoIP. Multi-Protocol Label Switching offers multiple Classes of Service, enabling you to apply separate settings to different types of traffic.Improve Bandwidth Utilisation- by putting multiple types of traffic on the same link, you can let high priority traffic borrow capacity from lower priority traffic streams whenever required. Conversely, when the lower priority traffic needs to burst beyond its usual amount of bandwidth, it can use any capacity that's not being used by higher priority services.

Hide Network Complexity- anMPLSconnection between two sites can be configured to act like a long Ethernet cable, with the hops involved hidden from view. This is sometimes known asVPLS(Virtual Private LAN Service).

Reduce Network Congestion- Sometimes the shortest path between two locations isn't the best one to take, as congestion has made it less attractive (at least for the time being). MPLS offers sophisticated traffic engineering options that enable traffic to be sent over non-standard paths. This can reduce latency (the delay in sending/receiving data). It also reduces congestion on the paths that have just been avoided as a result of traffic engineering.

Q & AQuestion and Answer Session