1. Introduction to 802.11 Protocol(WLan Standard) In the name of God University of Tehran School of Electrical and Computer Engineering 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 2

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] 3

4. IEEE 802.11 Protocol: 4 Covers physical and data link layer acc. to OSI Physical layer: Data Link layer Spread Spectrum FHSS DSSS 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 [5]

6. IEEE 802.11 standards : IEEE 802.11 b 6 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 7 [5]

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

9. IEEE 802.11 standards : 9 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 : 10 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) 11 TransmitterReceiver [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. 12 [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 13 [5]

14. IEEE 802.11 standards : IEEE 802.11 g 14 Frequency= 2.4 GHz Maximum Speed = 54 Mbps Range = about 38 meters(Varies) Encoding Scheme = OFDM www.cisco.com [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 15 [5]

16. IEEE 802.11 standards : IEEE 802.11n 16 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) 17 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 : 18 [1]

19. ATHEROS Product : 19 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. 20 [2]

21. References : 21 1.www.atheros.com/pt/bulletins/ar9285Bulletin.pdfwww.atheros.com/pt/bulletins/ar9285Bulletin.pdf 2.www.howstuffworks.com/wireless-network.htmwww.howstuffworks.com/wireless-network.htm 3.Panko’s,“Tutorial Wireless LANs (WLANs)”, Business Data Networks and Telecommunications, 2007 4.Pablo brenner,”A technical tutorial of the IEEE 802.11 protocol ”,2007 5. http://en.wikipedia.org/wiki/802.11http://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.IEEE Sensor Array and Multichannel Signal Processing Workshop, Cambridge, MA, Mar, pp. 149-152,2000. 8.Tanenbaum Andrews,”Computer networks (fourth edition) book” 9. Hardware Implementation of a ٨٠٢.١١n MIMO OFDM Transceiver, Zoha Pajouhi, Seid Mehdi Fakhraie, Seid Hamidreza Jamali. IEEE ٢٠٠٨

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