Research On OFDM System And Key Coding Technology Based On IEEE 802.11a Standard

WLAN (Wireless Local Area Network) is an important part of future mobile communications systems. As a choice of wireless access technology, WLAN taking the IEEE 802.11 series as the representative is popular in lots of customers and merchants who deal in access network, and gets a large development. On the other hand, the research on the core techniques of the next generation WLAN is becoming one of the hotspots in communications market, which extensive expert and scholar pay attention to. And it's to be the inevitable choice for the next generation wireless mobile communications, that is the combination of MIMO(Multiple-Input Multiple-Output) taking space-time coding as its key technique and OFDM (Orthogonal Frequency Division Multiplexing) .This thesis mainly investigates the physical system of IEEE802.11a which adopts OFDM . MIMO technique and a kind of high performance channel codes (Multiple single parity check codes) apply to 802.11a system, in order to realize possibility systems with higher credibility and greater possibility. This paper mainly presents three parts. The first part, taking IEEE 802.11a as background, is focused on the research of several key techniques of OFDM, including synchronization, channel estimation and reducing peak-to average power ratio. The parameter and physical layer simulator are designed based on 802.11a,then carry out the performance simulation; The second part studies one special multiple concatenated Turbo block codes which employ single parity check codes as their component codes (also be called multiple single parity check codes). Using three series single parity check codes(3-SC-SPC) to replace convolution codes , set up a new OFDM system based on IEEE 802.11a ; The last part pays more attention to space-time code including LSTC, STTC and STBC, and does research on MIMO-OFDM based on space-time coding, then sets up a new MIMO-OFDM system based on IEEE 802.11a.We attain main conclusions on the following two aspects: (1) multiple single parity check codes with different coding structures have different but regular performance variation, performance of series coding structure is distinctly better than convolution coding. Therefore, it's considered that using series single parity check coding with simple encoding structure to replace already mature convolution code.(2)The two new systems, OFDM and MIMO-OFDM systems setting up based on IEEE 802.11a, have more improvement than the original 802.11a system on performance.