Wireless Communications(and Networks)
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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 handware and software
Each channel, 1000-350 voice call
Chip rate: 16Megachips per second
6 times spectrum efficiency than GSM
Dual mode, tri mode: TDMA, EDGE, WCDMA
Dual band, tri band
2010 to finish updating, slow
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IMT-200IMT-200 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
1xRTT: instantaneous 307kbps for a user, constant rate 144kbps
1x means 1.25MHz, 3x means 3.75MHz
1xEV: Qualcomm. – 1xEV-DO: data only, up to 2.4Mbps, but depends.
– 1xEV-DV: data and voice, 144kbps, double the voice users
3xRTT: 2Mbps
Seamlessly and less expensive update
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IMT-2000IMT-2000 CDMA developers Groups
http://www.cdg.org
3GPP2
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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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IMT-2000IMT-2000 3G spectrum auction: England, 35.4B, German 46B
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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
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GP
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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?