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Introduction to

In the name of God University of Tehran School of Electrical and Computer Engineering. Introduction to. 802.11 Protocol(WLan Standard). By : Noushin Behboudi 810188190 Supervisor : Prof. S. M. Fakhraei Spring 2010.

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Introduction to

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  1. In the name of God University of Tehran School of Electrical and Computer Engineering Introduction to 802.11 Protocol(WLan Standard) By: Noushin Behboudi 810188190 Supervisor : Prof. S. M. Fakhraei Spring 2010 Class presentation for the course: “Custom Implementation of DSP Systems” All the materials are copy rights of their respective authors as listed in references.

  2. Outline: • Introduction • IEEE 802.11 Protocol Layers • IEEE 802.11 standards • ATHEROS Product • Summary • References

  3. 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 world’s first • wireless LAN standard. • IEEE 802.11 is a subset of IEEE 802 LAN standard. • [5]

  4. IEEE 802.11 Protocol: • Covers physical and data link layer acc. to OSI • Physical layer: • FHSS • DSSS • Data Link layer Spread Spectrum • Logic Link Control (LLC) • Media Access Control (MAC) • [5]

  5. IEEE 802.11 standards : • IEEE 802.11 standards • IEEE 802.11 b • IEEE 802.11 a • IEEE 802.11 g • IEEE 802.11 n • [5]

  6. IEEE 802.11 standards : IEEE 802.11 b • 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) • [5] www.cisco.com

  7. IEEE 802.11 standards : • IEEE 802.11 standards • IEEE 802.11 b • IEEE 802.11 a • IEEE 802.11 g • IEEE 802.11 n • [5]

  8. IEEE 802.11 standards : IEEE 802.11 a • Frequency = 5 GHz • Maximum Speed = 54 Mbps • Range = about 35 meters(Varies) • Encoding Scheme = OFDM • [5] www.cisco.com

  9. IEEE 802.11 standards : IEEE 802.11 a Multipath Effect(Multipath Fading) is simply a term used to describe the multiple Paths the radio wave may follow between transmitter and receiver • [7]

  10. IEEE 802.11 standards : IEEE 802.11 a Orthogonal Frequency Division Multiplexing(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 have • been 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]

  11. IEEE 802.11 standards : IEEE 802.11 a A simple idealized OFDM system (Implementation using FFT Algorithm) Transmitter Receiver • [6]

  12. IEEE 802.11 standards : • 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. • [6]

  13. IEEE 802.11 standards : • IEEE 802.11 standards • IEEE 802.11 b • IEEE 802.11 a • IEEE 802.11 g • IEEE 802.11 n • [5]

  14. IEEE 802.11 standards : IEEE 802.11 g www.cisco.com • Frequency= 2.4 GHz • Maximum Speed = 54 Mbps • Range = about 38 meters(Varies) • Encoding Scheme = OFDM • [5]

  15. IEEE 802.11 standards : • IEEE 802.11 standards • IEEE 802.11 b • IEEE 802.11 a • IEEE 802.11 g • IEEE 802.11 n • [5]

  16. IEEE 802.11 standards : IEEE 802.11n • Frequency = 5 GHz,2.4 GHz • Modulation = OFDM • Addition of Mimo • Maximum Speed = 150 Mbps • Range = about 70 meters(Varies) • Encoding Scheme = OFDM • [5]

  17. IEEE 802.11 standards : IEEE 802.11 n Multiple Input Multiple Output(MIMO) • In radio, Multiple-input and • Multiple-output is used of • multiple antennas at both the • transmitter and receiver to • improve communication • performance. It is one of • several forms of smart antenna • technology. • [4]

  18. ATHEROS Product : • [1]

  19. ATHEROS Product : ATHEROS 9285 Spec: • [1]

  20. 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. • [2]

  21. References : www.atheros.com/pt/bulletins/ar9285Bulletin.pdf www.howstuffworks.com/wireless-network.htm Panko’s,“Tutorial Wireless LANs (WLANs)”, Business Data Networks and Telecommunications, 2007 Pablo brenner ,”A technical tutorial of the IEEE 802.11 protocol ”,2007 http://en.wikipedia.org/wiki/802.11 Dr.S.Srikanth ,” Tutorial on OFDM’’,AU-KBC Research Centre Anna University Chennai,2007 K. F. Lee and D. B. Williams, “A space-frequency coded transmitter diversity technique for frequency selective fading channels,” in Proc.IEEE Sensor Array and Multichannel Signal Processing Workshop, Cambridge, MA, Mar, pp. 149-152,2000. Tanenbaum Andrews ,”Computer networks (fourth edition) book” 9. Hardware Implementation of a ٨٠٢.١١n MIMO OFDM Transceiver, Zoha Pajouhi, SeidMehdiFakhraie, SeidHamidrezaJamali. IEEE ٢٠٠٨

  22. Thanks for your attention ! Any Question?

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