Research On Key-Technique In PHY Of IEEE802.16d System

In this paper, we researched on the key technique of physical layer in IEEE802.16d system. First we introduced the development and characteristic of IEEE802.16d standard, then the principle of OFDM and OFDMA technique are given. In OFDMA PHY of 802.16d, we mainly investigated the space-time block coded OFDMA system and carrier-frequency offset estimation for 802.16d system. After analyze the principle of space-time block coded OFDMA system, in order to guarantee symbol recovery regardless of channel nulls, we introduced linear precoding to the space-time block coded OFDMA system. Simulation results display that this method can enhance the performance of system. Then the two carrier frequency offset estimation methods for OFDMA system of 802.16d were investigated, ML estimation algorithm and Structure-based estimation algorithm. Aimed at the disadvantage of the Structure-based estimation algorithm under low SNR conditions, we adopt the multiple receive antennas method to improve the performance of Structure-based estimation algorithm. Simulation results prove that receiver diversity can improve the precision of estimation algorithm.