7 introduction-wireles lan
TRANSCRIPT
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
What is a wireless LAN?
A wireless LAN is a data transmission system
designed to provide location-independent
network access between computing devices by
using radio waves rather than a cable
infrastructure.
Usually implemented as the final link between
existing wired network and group of client
computers.
Wireless LAN = LAN without wires. Anytime,
anywhere
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Infrastructure Network
Point-to-multipoint
Ad hoc network
Ethernet bridge
Point-to-point
Application of Wireless LAN
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Wireless LAN Standards
IEEE 802.11Established by IEEE in June 1997
Specifies 2.4GHz frequency of 1 Mbps and 2 Mbps.
Two more specifications came up in Late 1999.
IEEE 802.11b Uses CCK and provides data ratesup-to 11 Mbps
IEEE 802.11a& g Uses OFDM and provides data
rates up-to 54 Mbps
HiperLAN
It is primarily used in Europe countries. It operates in
5GHz radio band. There are 2 specifications
namely
HiperLAN/1 and HiperLAN/2
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Features of IEEE 802.11a and b
Direct sequence spread spectrum Operates in the 2.4GHz band 14 Channels spaced 5 MHz apart The United States support the first 11
channels Data rates 11, 5.5, 2 and 1 Mbps
IEEE802.11b standard
IEEE802.11a standard
Orthogonal Frequency Division
Multiplexing Operates in the 5GHz band Data rates 54, 48, 36, 24, 18, 12, and 6
Mbps 6, 12, and 24 are Mandatory
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Specifications same as 802.11a:
Frequency of operation = 2.4 GHz like 802.11b.
Hence signal attenuation is low, unlike in the 5GHz band. Orthogonal Frequency Division Multiplexing Operates in the 5GHz band Data rates 54, 48, 36, 24, 18, 12, and 6 Mbps
6, 12, and 24 are Mandatory Systems are under development
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
IEEE 802.11 g
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Wireless Metropolitan
Area Networks (MANs)
BS
Company
HomeApartment
Office
PDA Up to 35 miles
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Prof. R. V. Raja Kumar Dept. of E & ECE
WMAN ApplicationsIIT
Kharagpur
1. Broadband connectivity to fixed, portable and
nomadic users.
2. Traditional voice communication.
3. Video distribution.
4. Video conferencing.
5. Streaming media services.
6. Last mile local connection to internet.
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MMDS Point to Multipoint (2.5 2.7 GHz)
LMDS Point to Multipoint (28 & 31 GHz)
Point-to-multipoint with sector antennas Point-to-point with directional antennas
Throughput to 60 Mbps shared per sector (5.8 GHz)
Multiple manufacturers (non-standards based today)
TDM
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
LMDS and MMDS
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Prof. R. V. Raja Kumar Dept. of E & ECE
Other FeaturesIIT
Kharagpur
Broad bandwidth
Up to 134 Mbit/s in a 28 MHz channel (in 10-66 GHz air interface)
Point-to-multipoint topology, with mesh extensions
Supports multiple services simultaneously with full QoS
Efficiently transport IPv4, IPv6, ATM, Ethernet, etc.
Bandwidth on demand (frame by frame) MAC designed for efficient use of spectrum (TDM and TDMA)
Supports multiple frequency allocations from 2-66 GHz
ODFM and OFDMA for non-line-of-sight applications
TDD and FDD
Link adaptation: Adaptive modulation and coding
Subscriber by subscriber, burst by burst, uplink and downlink
Extensions to mobility are coming next.
Coexistance with 4G?
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Prof. R. V. Raja Kumar Dept. of E & ECE
WMAN StandardsIIT
Kharagpur Standard 802.16 802.16a/d 802.16e 802.20
Status 2001 2004 2005 2005-06
Target App. WMAN WMAN WMAN WWAN
Range Average CellRadius 1-3 mi
Average CellRadius 4-6 mi
Average CellRadius 1-3 mi
Channel
Conditions
LOS NLOS NLOS NLOS
Spectrum 10-66 GHzLicensed
2-11 GHz 2-6 GHz
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The last mile access solution Alternative to DSL, cable modem, leased lines,
fiber and other broadband network access
technologies
Ability to transfer data, voice, and video atspeeds of up to 70 Mbps
The 802.16e will support subscriber stations
moving at pedestrian and vehicular speeds
(speeds of 120 to 150 Kmph) Has potential to be deployed far faster, less
expensively, and more flexibly than similar
wireline installations
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
IEEE 802.16
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Prof. R. V. Raja Kumar Dept. of E & ECE
Multiaccess and ModulationIIT
Kharagpur
OFDM (WirelessMAN-OFDM Air Interface) 256-point FFT with TDMA (TDD/FDD)
OFDMA (WirelessMAN-OFDMA Air Interface) 2048-point FFT with OFDMA (TDD/FDD) Single-Carrier (WirelessMAN-SCa Air
Interface) TDMA (TDD/FDD) BPSK, QPSK, 4-QAM, 16-QAM, 64-QAM, 256-
QAM
Most vendors will use Frequency-DomainEqualization
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Metropolitan area network (MAN) protocol Real-time data transmission at DSL/Cable
speeds (1Mbps or more) based on cell range Cell ranges of up to 15 kilometers or more Mobile users even when they are traveling at
speeds up to 250 Kmph (802.20 is an option for
deployment in high-speed trains) The 802.16e will support subscriber stations
moving at pedestrian and vehicular speeds(speeds of 120 to 150 Kmph).
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
IEEE 802.20
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Prof. R. V. Raja Kumar Dept. of E & ECE
WiMax Forum
IIT
Kharagpur
NEOTEC
An industry-led, non-profit corporation formed to
promote and certify compatibility and interoperability of
broadband wireless products.wide acceptance of the IEEE 802.16 and ETSI HiperMAN
wireless MAN standards.
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IITKharagpur
Prof. R. V. Raja Kumar, Amit Kumar Dept. of E & ECE
Bluetooth
It is a wireless personal area network
for connecting closely spaced
devices in a range of 10m.
Cost effective Standardized by IEEE 802.15 Conceived by Ericsson in 1985. Works in 2.4 GHz unlicensed band Connects PDAs, headset, mobile
phones, USB, PCs printers etc. 1 Mbps, FHSS (2.402+k) MHz (k=0,1,2,,78); 1600 hops/Sec. GFSK modulation
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Ultra Wideband Systems
Unmodulated baseband signals are used
for a short range communication at very
low powers. The interference caused is
negligible.
Typical bandwidth 2-10 GHz.
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
UWB Signals
Typically UWB signals are modulated pulse trains Very short pulse duration (
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Large Bandwidth of UWB
UWB is a form of extremely wide spread spectrum where RFenergy is spread over GHz of spectrum
Wider than any narrowband system by orders of mag. UWB power seen by a narrowband system is a fraction of
the total
UWB signals can be designed to look like imperceptiblerandom noise to conventional radios
Narrowband (32 KHz)
Wideband (5 MHz)
UWB ( a few GHz)
Part 15 limit
Frequency, f
PSD
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
0.96 1.61
1.99
3.1 10.6
GPS
Band
Power Spectral Density Limits
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
RF Tags
Passive and active RF tagsApplication in Ware houses
Very low power Very low range (eg.: 10m)
Very low cost (eg.: 10 cents)
Detection, identification and location of tagged
items (eg.: boxes)
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Owner Motorola
Satellites 66, 11/orbit
Orbits 900km, 6 polar orbits
Type Big LEO
MAC method FDMA\TDMARound trip
delay10 ms approx.
Start ofService
1998
Services Voice, Data (2.4 Kbps), FAX,
GPS
Mobile Sat. Comm. (Irridium)
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Each satellite is like a BS for
40min-120 min. Relay Station switching Comm. distance ~ 200km Attenuation almost 40000
times less as compared toGeo Stationary path
Low power requirements=>
smaller (& cheaper) handsets Cost compensated in the
deployment of manysatellites and on handover
technology6 X 11 LEO polar orbit
Satellites for global coverage
Low Earth Orbit Satellites
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Technology
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Handsets
Nokia 9110
3COM
Palm VII
Nokia
3G visionPCMCIAWLAN Card
The newEricsson R380
phone, which
features wireless
data functions
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Transceiver of a Wireless System
Source
coder
Channel
CoderInter-
leaver
Amp.
& Tx.
filter
Freq.synthesizer
Source
decoder
Channel
Decoder
Modu-
latorADC Mixer
Rx.
filter &
LNAMixer
Amp &
DAC
Deinte-
rleaver
Equal.,
demod.
AGC &
Synch.
Protocolprocessor &
Controller
DSP /
contro-ller
Digital
ASICs
Analog /
mixed SP
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IITKharagpur
Prof. R. V. Raja Kumar, Amit Kumar Dept. of E & ECE
RF
Front
end
Base-
Band
Proce-ssor
Protocol,
LogicalCh. Proc.
&
Control
HS
ADCDAC
Aud.
codec
Implementation
RF ASICs: LNA, Mixer, Freq.
Syth., Power amplifier
Data conversion: ADC, DAC
Digital ASICs: Basebandprocessors,
DSPs: Baseband proc.,
source coding,
proc.s /controllers:Protocol processing, System
controlling
System on a
Chip
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
VLSI Technology
Roadmap
Characteristic 1999 2001 2004 2008
Process technology (nm) 180 130 90 60
Logic transistors (millions) 23.8 47.6 135 539
Across-chip clk. Speed(MHz)
1200 1600 2000 2655
Die-area (sq. mm) 340 340 390 468
Wiring levels 6 7 8 9
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
System on a Chip
(SoC)
Evolution of ASICs into SoCs The use of pre-designed IP blocks Technology for future systems
RF CMOStechnology
low cost High performance and low power chips for
portable applications
Ex.: PDA
100 mW(2mW st. by)
300 MOPs to
2500 MOPs
SoCRF
Base-
band
Network
Proc.Memory
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Libraries of different standards like, Radio frequency bands, Intermediate frequency (IF) bandwidth, Modulation schemes,
Coding schemes, Access methods, Cryptographic standards, Network protocols like MAC,
Frequency hopping to find secure channels.
Provides features that are useful for intelligence
gathering and other tasks defense comm.
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
SDR Subsystem
Library
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New energy-efficient algorithms, Reconfigurable architectures based on ASICs
(application-specific integrated circuits),
Digital signal processing for SDRs, Use of FPGAs (field-programmable gate arrays)
for SDR silicon.
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Research Issues in
Software Defined Radio
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IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Capacity Enhancement and
Enabling Techniques
Multiuser detection (MUD)
Antenna array
Transmit diversity
Transmission power control (TPC)
Turbo Codes
Software radio (SWR)
High Performance DSPs
High energy rechargeable batteries
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MAC Enhancements Physical layer issues (eg.: equalization) Smart antennas Multiple-input-multiple-output systems Space-time coding Dynamic packet assignment Multiaccess methods (eg.: MC-DS-CDMA) Software radio
High performance DSPs and ASICs
IITKharagpur
Prof. R. V. Raja Kumar Dept. of E & ECE
Some Research Areas
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Thank You