802.11standards

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Introduction to

802.11 Protocol(WLan Standard)

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Outline:

Introduction

IEEE 802.11 Protocol Layers

IEEE 802.11 standards

ATHEROS Product

Summary

References

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Introduction:

Access anytime, anywhere internet.

IEEE 802.11 is a set of standards for wireless Local Area Networks

(WLANs) computer communication, developed by the IEEE

LAN/MAN Standards Committee.

1997 working group approved IEEE 802.11 as the worlds first

wireless LAN standard.

IEEE 802.11 is a subset of IEEE 802 LAN standard.

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IEEE 802.11 Protocol:

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Covers physical and data linklayer acc. to OSI

Physical layer:

Data Link layer

Spread Spectrum

FHSS

DSSS

Logic Link Control (LLC)

Media Access Control (MAC)

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IEEE 802.11 standards :

IEEE 802.11 standards IEEE 802.11 b

IEEE 802.11 a

IEEE 802.11 g

IEEE 802.11 n

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IEEE 802.11 b

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Frequency = 2.4 GHz (ISM band)

Maximum Speed =11 Mbps

Range = about 38meters(Varies)

Encoding Scheme = DSSS

Modulation Technique= BPSK(1 Mbps),

DQPSK(2 Mbps), CCK(5.5 Mbps,11Mbps)

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www.cisco.com

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IEEE 802.11 a

IEEE 802.11 g

IEEE 802.11 n

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IEEE 802.11 a

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Frequency = 5 GHz

Maximum Speed = 54 MbpsRange = about 35 meters(Varies)

Encoding Scheme = OFDM

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IEEE 802.11 a

Multipath Effect(Mul tipath Fading)

is simply a term used to describe the multiple

Paths the radio wave may follow between

transmitter and receiver

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IEEE 802.11 a

OrthogonalFrequencyDivisionMultiplexing(OFDM)

OFDM a digital multi-carrier modulation method. A large

number of closely-spaced orthogonal sub-carriers are used to

carry data.

Although the principles and some of the benefits havebeen known since the 1960s, OFDM is popular for

wideband communications today by way of low-cost digital

signal processing components that can efficiently calculate

the FFT. [6]

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IEEE 802.11 aA simple idealized OFDM system

(Implementation using FFT Algorithm)

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TransmitterReceiver

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IEEE 802.11 a

OFDM Pros &Cons

Robust against narrow-band co-channel interference.

Robust against intersymbol interference (ISI) and fading caused by multipath

propagation.High spectral efficiency as compared to conventional modulation schemes, spread

spectrum, etc.

Efficient implementation using Fast Fourier Transform (FFT).

Sensitive to Doppler shift.Sensitive to frequency synchronization problems.

High peak-to-average-power ratio (PAPR), requiring linear transmitter circuitry, which

suffers from poor power efficiency.

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IEEE 802.11 a

IEEE 802.11 g

IEEE 802.11 n

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IEEE 802.11 g

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Frequency= 2.4 GHz Maximum Speed = 54 Mbps

Range = about 38 meters(Varies)


www.cisco.com

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IEEE 802.11 a

IEEE 802.11 g

IEEE 802.11 n

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IEEE 802.11n

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Frequency = 5 GHz,2.4 GHz

Modulation = OFDM Addition of Mimo

Maximum Speed = 150 Mbps

Range = about 70 meters(Varies)


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IEEE 802.11 nMultipleInputMultiple Output(MIMO)

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In radio, Multiple-input andMultiple-output is used of

multiple antennas at both the

transmitter and receiver to

improve communicationperformance. It is one of

several forms of smart antenna

technology.

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ATHEROS Product :

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ATHEROS Product :

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ATHEROS 9285 Spec:

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Summary:

IEEE 802.11n standard Significantly improves throughput and range

compared with older 802.11 standards.

802.11n is the only 802.11standard that operates in either the 2.4

GHz and 5 GHz frequency bands.

It is the first to standardize the use of multiple input, multiple output

(MIMO) antenna design.

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References :

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1. www.atheros.com/pt/bulletins/ar9285Bulletin.pdf

2. www.howstuffworks.com/wireless-network.htm

3. Pankos,Tutorial Wireless LANs (WLANs), Business Data Networks and

Telecommunications, 2007

4. Pablo brenner ,A technical tutorial of the IEEE802.11protocol ,2007

5. http://en.wikipedia.org/wiki/802.11

6. Dr.S.Srikanth , Tutorial on OFDM,AU-KBC Research Centre Anna University

Chennai,2007

7. K. F. Lee and D. B. Williams, A space-frequency coded transmitter

diversity technique for frequency selective fading channels, in Proc.IEEESensor Array and Multichannel Signal Processing Workshop, Cambridge, MA, Mar, pp.

149-152,2000.

8. TanenbaumAndrews ,Computer networks (fourth edition) book

9. Hardware Implementation of a . n MIMO OFDM Transceiver, Zoha

Pajouhi, Seid Mehdi Fakhraie, Seid Hamidreza Jamali. IEEE
http://www.atheros.com/pt/bulletins/ar9285Bulletin.pdfhttp://www.howstuffworks.com/wireless-network.htmhttp://en.wikipedia.org/wiki/802.11http://en.wikipedia.org/wiki/802.11http://en.wikipedia.org/wiki/802.11http://www.howstuffworks.com/wireless-network.htmhttp://www.howstuffworks.com/wireless-network.htmhttp://www.howstuffworks.com/wireless-network.htmhttp://www.atheros.com/pt/bulletins/ar9285Bulletin.pdfhttp://www.atheros.com/pt/bulletins/ar9285Bulletin.pdfhttp://www.atheros.com/pt/bulletins/ar9285Bulletin.pdfhttp://www.atheros.com/pt/bulletins/ar9285Bulletin.pdf

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802.11standards

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