Wireless Lan Ap's Mac Layer Protocol And Hardware Design

The paper works on the central MAC protocols of IEEE802.11 WLAN, then brings up an implementation of WLAN AP MAC hardware circuit, and works out the PCB of it.Firstly, the basic framework of WLAN is built on the basis of the introduction of elements and related conceptions of IEEE802.11 WLAN. The services of IEEE802.11 are introduced in two types: distribution services (DS) and station services (SS), and their relationships and messages to support them are also presented. Then the primitives of MAC asynchronous data service and the structure of MAC frames are illustrated.Secondly, the functional architecture of MAC sublayer is discussed. The whole functional architecture is first introduced, then is the distributed coordination function (DCF) and the point coordination function (PCF). In DCF, we put special emphasis on the carrier-sense mechanism, MAC-Level acknowledgments, interframe space (IFS), random backoff time, and DCF access procedure, then we use Markoff chain to analyze the performance of DCF access. In PCF, we put effort into CFP structure and timing, PCF access procedure, PCF transfer procedure, polling list operation. The fragmentation and defragmentation and multiple rate support are also presented.Thirdly, we talk about the secure-WLAN , and the objects being researched in it, as well as the reason of the design. After a detailed introduction of Linux and MPC860, an embedded system of WLAN AP MAC hardware board based on Linux OS (Operating System) and MPC860 microprocessor is brought forward. Then the circuit of MPC860 module, power module, clock module, BDM interface module, memory module, serial port module, 100M Ethernet interface module, and PCMCIA interface module are given.Finally, the PCB implementation of the AP MAC and the plan of the debugging scheme are discussed. We research the process to get PCB form schematic, and the principles to be abided in the design of PCB, according to which the layout of MAC PCB, the layer stack structure, and the routing result are shown. At the end of this paper, the debugging scheme is also presented.