Research Of 802.11 Protocol

The ATM synthesize the advantage of circuit mode and package mode and base technology foundation for synthetic access of various multimedia service and high transport of information. With the development of mobile communication, people now expect to expand the use of ATM from traditional-optical fibre into wireless, that is WATM.But up to now there are no standard on the structure and protocol of WATM, also we have no idea on how to realize the material air access of WATM, thus it's a rush problem to solve the air access of WATM. In this paper, we use WLAN to solve the air access of WATM.First we introduce the feather of WLAN, e.g. transport mode, topology, technological demands and so on. Compared with other wireless technology, 802.11 and 802.11b are fit for using in the air access of WATM. Then we study the 802.11 protocol and use FPGA to realize the WEP algorithm of the MAC layer and function of the PHY layer, mainly in base band. Finally we study the technology of Complementary Code Keying, it's a key technology to improve the transport rate of 802.11 to that of 802.11b. We research the modulation and demodulation of CCK, and use MATLAB to simulate the material modulation and demodulation of CCK in AWGN channel. The simulation result is similar to the theoretic curve. From this result, we can see that the method we used to realize the modulation and demodulation of CCK is feasible.