UBC Theses and Dissertations
Performance analysis of some new and existing transmit and receive antenna diversity schemes Feng, Xiaoyan Sarina
A well-known method for symbol detection involving signals received over a number of independent diversity branches perturbed by additive white Gaussian noise is Maximum Ratio Combining (MRC). Two other diversity schemes, Simple Transmit Diversity (STD) and Maximum Ratio Transmission (MRT), have recently been proposed. The performances of these three schemes are compared. The STD scheme, which is applicable only to two transmit antennas, is shown to have the same error performance as MRC with the same diversity order when perfect channel estimates are available. The MRT scheme with N transmit and one receive antennas is shown to have the same performance as MRC with N receive antennas, but MRT with one transmit and N > 1 receive antennas or MRT with N > 1 transmit and M > 1 receive antennas do not perform as well as MRC. The performance degradations of MRC, STD and MRT due to errors in estimating the channel parameters are analyzed and compared. It is found that STD is significantly more susceptible than MRC and MRT to errors in the channel estimates. An improved scheme for MRT (IMRT) and a new optimal maximum ratio transmission and combining scheme (MRTC) are proposed. In the IMRT scheme, the same transmit weighting functions are used as in MRT. At the receiver, MRC combining rules are used to choose the weights for the received signals. The MRTC scheme maximizes the SNR using optimal transmit and receive weighting factors. Simulation results indicate that both IMRT and MRTC provide significant performance improvements over MRT.
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