The Research Of Wireless LAN IEEE802.11b Baseband Technology

The demand for broadband wireless communication motivates the development of wireless local-area-network(LAN). Several years ago, however, wireless LAN products from a variety of vendors were incompatible, so the market developed slowly and the products were expensive and were only used in the situations where cabling was impractical or impossible. With the maturing of industry standards, especially after IEEE 802.11 protocol being proposed, WLAN achieves a fast development. More and more companies are involved in the technology research and market promoting work of WLAN, and WLANs play a more important role in the communication market.This thesis focuses on the baseband technology of IEEE 802.11/1 Ib physical layer, which includes the characteristics of indoor multipath channel IEEE 802.11 confronts, estimation of this type of channel, modulation and receiver structure. The main contents are as follow:Chapter 1 is an introduction of IEEE 802.11's history and IEEE 802.11 network's architecture.Chapter 2 presents some specification of IEEE802.11/1 Ib baseband, and introduces the whole simulation link we designed, and give some explanation when necessary.Chapter 3 expresses characteristics and the model of the indoor wireless channel IEEE802.11 confronts, explains the principles of the channel estimation method adopted.Chapter 4 is the important part of this thesis. In this chapter, CCK codeword has been described. Following this are the algorithm of CCK receiver scheme, includeing Maximum likelihood receiver under AWGN channel- RAKE and RAKE-ISI receiver based on the channel matched filter and Decision Feedback Equalizer.Chapter 5 is a report about the receivers performance simulations. At first, the conditions of simulations are given, then the results of simulations are listed, finally, the comparison and analysis are giver.In chapter 6, the research work is summarized, the existing problems are pointed and possible solutions are given. In the meanwhile, the development of Wireless LAN in the future is prospected.