Performance of forward link broadband OFCDM packet wireless access using MMSE combining scheme based on SIR estimation

摘要

This paper elucidates the throughput performance, i.e., the number of simultaneously multiplexed code-channels of OFCDM (Orthogonal Frequency and Code Division Multiplexing), when employing a MMSE (Minimum Mean Square Error) combining scheme based on SIR estimation in a broadband channel to achieve maximum throughput above 100 Mbps. In the proposed MMSE combining scheme, the combining weights of each sub-carrier are derived from the channel gain, noise power, and number of multiplexed codes, which are estimated using the time-multiplexed common pilot channel and the coded data channel. Simulation results elucidate that the required average received E{sub}b/N{sub}0 for the average packet error rate (PER) = - 10{sup}(-2) can be improved by 0.6 and 1.2 dB by using MMSE combining instead of a conventional equal gain combining (EGC) in a 24-path Rayleigh fading channel (exponentially distributed path model, maximum delay time is approximately 1 μsec) in a single cell environment, when the number of multiplexed codes = 8 and 32, respectively, with the spreading factor of SF = 32. Furthermore, when the average received E{sub}b/N{sub}0 = 10 dB, the number of multiplexed codes for the average PER = 10{sup}(-2) in the MMSE combining is increased by approximately 1.3 fold that of the conventional EGC.