EELE 5490, Fall, 2009 Wireless Communications

EELE 5490, Fall, 2009

Wireless Communications

Ali S. Afana

Department of Electrical Engineering

Class 2

Oct. 2nd, 2009

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OutlineOutline 2.5G cellular networks

3G cellular networks

WMAX: LMDS

WLAN

WPAN– Bluetooth

– UWB

Ad Hoc Networks

Sensor Networks

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2.5G2.5G HSCSD: high speed circuit switched data: multiple time slots, realtime 57.6 kbps

GPRS: general packet radio service: non-realtime, 171.2 kbps

EDGE: Enhanced Data

Rates for GSM Evolution

Multiple modulation and

coding schemes (MCS)

New hardware 384kbps

IS-95B: multiple code

Medium data rate (MDR)

Up to 8 codes, 64kbps

Easy to update

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WCDMA-UMTSWCDMA-UMTS 8k-2.048 Mbps per user, future 8Mbps

Spectrum 5MHz, so complete change for hardware and software

Each channel, 100-350 voice call

Chip rate: 16Megachips per second

6 times spectrum efficiency than GSM

2010-2015 to finish updating, slow

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IMT-2000IMT-2000 GSM world: http://www.gsmworld.com

UMTS world: http://www.umtsworld.com

3GPP

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CDMA2000CDMA2000 1.25MHz, seamless for CDMAone, IS95B, CDMA2000

Higher data rate

Seamlessly and less expensive update

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TD-SCDMATD-SCDMA China, 8 millions per month

Time Division Synchronous CDMA

GSM based infrastructure

1.6 MHz, 384 kbps

Smart antenna, several time better spectrum efficiency than GSM

TDD

Cheap to update

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Wireless Local LoopWireless Local Loop Last mile technology

Ramp to highway

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Local Multipoint Distribution ServiceLocal Multipoint Distribution Service

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LMDSLMDS IEEE 802.16 WIMAX

HIPERACESS

Line of sight

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WMAN StructureWMAN Structure

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Rain AttenuationRain Attenuation

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Rain AttenuationRain Attenuation

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802.11802.11 2.4G-2.4835G, 5.725-5.825G

802.11a/g, OFDM, 802.11b: CDMA

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ChannelChannel 11, 5.5, 2, 1Mbps

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Channelization schemeChannelization scheme channels

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802.11802.11 802.11a/g: 54, 48, 36, 24, 18, 6Mbps

802.11e -MAC Enhancements-Security/QoS

802.11f- Inter-Access Point Protocol

802.11h- Spectrum Managed 5Ghz

802.11i- Enhanced Security (TKIP and 802.1x)Application

Presentation

Session

Transport

Network

Data Link

Physical

ISOOSI7-layermodel Logical Link Control

Medium Access (MAC)

Physical (PHY)

IEEE 802standards

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Wireless hotpot plannerWireless hotpot planner Wireless valley

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Design ProcedureDesign Procedure

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Future WIFIFuture WIFI

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Signal to Noise Ratio at homeSignal to Noise Ratio at home

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Personal Area NetworksPersonal Area Networks 802.15

– Master-slave piconets

– Capable of connecting a mix of multiple piconets into “scatternet”

– Service discovery protocol allows invisible interaction of various “trusted” devices

– Less susceptible to interference

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BluetoothBluetooth Wireless LAN technology (10 meters) or PAN 2.4GHz band with 1Mbps speed Spread spectrum frequency-hopping “always on” user-transparent cable-replacement Combination of packet-switching & circuit-switching (good for

data & voice) 3 voice channels - 64Kbps each Low power, low cost Transparently connects “office” devices

– Laptop, Desktop, PDA, Phone, printer

Bridging capability: network-pda-phone

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Ultra Wide BandUltra Wide Band High speed at short range

– 480 Mb/s at ~3m. Does not penetrate walls

Wireless USB

IP over UWB

1.6 1.9 2.4

Bluetooth,802.11b WLANCordless PhonesMicrowave Ovens

PC

S

5

802.11a WLANCordless Phones

-41 dBm/Mhz“FCC Part 15 Limit”

Frequency (Ghz)

EmittedSignalPower

10.63.1Note: not to scale

UWB Spectrum

U-N

II b

and

ISM

ban

d

GP

S

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SummarySummary Trend

– 802.11 - 802.15 - cellular wireless technologies all competing for customers

– 802.11 WLANs offer “hotspots” at nominal cost (sometimes “free”)

– Cellular services used worldwide

– 802.15 Bluetooth offers bridging options for WLAN and cellular services

Alliances, Partnerships, Coalitions,…– AT&T, Intel, IBM (and investors) form “Cometa”, a company to provide

wireless hot spots across the country

– Motorola, Proxim and Avaya form partnership to provide seamless roaming between WiFi and cellular networks

– HP and Transat Technologies collaborating on project to link 2G/3G to WiFi “hotspots”

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Wireless TechnologiesWireless Technologies

PAN(Personal Area

Network)

LAN(Local Area Network)

WAN(Wide Area Network)

MAN(Metropolitan Area Network)

PAN LAN MAN WAN

Standards Bluetooth802.15.3

802.11802.11802.16802.20

GSM, CDMA, Satellite

Speed < 1 Mbps 11 to 54 Mbps 10-100+ Mbps 10 Kbps–2 Mbps

Range Short Medium Medium-Long Long

Applications Peer-to-PeerDevice-to-Device

Enterprise Networks

Last Mile AccessMobile Data

Devices

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Ad Hoc NetworkAd Hoc Network Mobile Ad Hoc Networks (MANETs)

– An autonomous collection of mobile users that communicate over relatively bandwidth constrained wireless links.

– Since the nodes are mobile, the network topology may change rapidly and unpredictably over time.

– The network is decentralized, where all network activity including discovering the topology and delivering messages must be executed by the nodes themselves, MANETs need efficient distributed algorithms to determine network organization, link scheduling, and routing.

– The set of applications for MANETs is diverse, ranging from small, static networks that are constrained by power sources, to large-scale, mobile, highly dynamic networks

– In a military environment, preservation of security, latency, reliability, intentional jamming, and recovery from failure are significant concerns

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MANET ExamplesMANET Examples Ad hoc mode of WIFI

Military

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Wireless Sensor NetworkWireless Sensor Network Consists of a number of sensors spread across a geographical area.  Each

sensor has wireless communication capability and some level of intelligence for signal processing and networking of the data. – Military sensor networks to detect and gain as much information as

possible about enemy movements, explosions, and other phenomena of interest.

– Sensor networks to detect and characterize Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE) attacks and material. 

– Sensor networks to detect and monitor environmental changes in plains, forests, oceans, etc.

– Wireless traffic sensor networks to monitor vehicle traffic on highways or in congested parts of a city. 

– Wireless surveillance sensor networks for providing security in shopping malls, parking garages, and other facilities. 

– Wireless parking lot sensor networks to determine which spots are occupied and which are free.

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Wireless Sensor NetworksWireless Sensor Networks Classification: whether or not the nodes are individually

addressable and whether the data in the network is aggregated. Goals and Tasks

– Determine the value of some parameter at a given location: In an environmental network, one might one to know the temperature, atmospheric pressure, amount of sunlight, and the relative humidity at a number of locations.  This example shows that a given sensor node may be connected to different types of sensors, each with a different sampling rate and range of allowed values.

– Detect the occurrence of events of interest and estimate parameters of the detected event or events:  In the traffic sensor network, one would like to detect a vehicle moving through an intersection and estimate the speed and direction of the vehicle.

– Classify a detected object:  Is a vehicle in a traffic sensor network a car, a mini-van, a light truck, a bus, etc.

– Track an object: In a military sensor network, track an enemy tank as it moves through the geographic area covered by the network.

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WSN RequirementWSN Requirement Large number of (mostly stationary) sensors:  Aside from the deployment of sensors on the

ocean surface or the use of mobile, unmanned, robotic sensors in military operations, most nodes in a smart sensor network are stationary.  Networks of 10,000 or even 100,000 nodes are envisioned, so scalability is a major issue.

Low energy use:  Since in many applications the sensor nodes will be placed in a remote area, service of a node may not be possible.  In this case, the lifetime of a node may be determined by the battery life, thereby requiring the minimization of energy expenditure.

Network self-organization:  Given the large number of nodes and their potential placement in hostile locations, it is essential that the network be able to self-organize; manual configuration is not feasible.  Moreover, nodes may fail (either from lack of energy or from physical destruction), and new nodes may join the network.  Therefore, the network must be able to periodically reconfigure itself so that it can continue to function.  Individual nodes may become disconnected from the rest of the network, but a high degree of connectivity must be maintained. 

Collaborative signal processing:  Yet another factor that distinguishes these networks from MANETs is that the end goal is detection/estimation of some events of interest, and not just communications.  To improve the detection/estimation performance, it is often quite useful to fuse data from multiple sensors.  This data fusion requires the transmission of data and control messages, and so it may put constraints on the network architecture. 

Querying ability:  A user may want to query an individual node or a group of nodes for information collected in the region.  Depending on the amount of data fusion performed, it may not be feasible to transmit a large amount of the data across the network.  Instead, various local sink nodes will collect the data from a given area and create summary messages.  A query may be directed to the sink node nearest to the desired location.

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Wireless Sensor NetworksWireless Sensor Networks

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HomeworkHomework Read Chapter 2

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Questions?Questions?