UP	Paper 1783	US-M-W	DOWN
Performance of Generalized Diversity Combining System for Coded Transmissions
Wang,Zhengdao		Iowa State University
Kim,Sang Wu		Iowa State University
Diversity combining is an important technique for combating fading in wireless communications. Generalized diversity combining selects a subset of diversity branches and combines them coherently. It has been established that when the transmission is uncoded, the optimal generalized diversity combining in the sense of minimizing bit error rate is to select branches that offer the maximum sum log-likelihood ratio (LLR). In the coded case, such diversity combining is not optimal any more. We present in this paper an upper bound result on the bit error rate performance of coded transmissions over general memoryless channels, and apply the analysis to the diversity selection problem. The resulting semi-analytical method for evaluating performance of coded diversity combining schemes offers insight on the difference between the performances of the coded and uncoded systems. It is shown via a numerical example that a scheme that selects individually &096;&096;strong'' branches (in the sense of large LLR) can out-perform a scheme that selects branches that are jointly &096;&096;strong''.
Zhengdao Wang received his B.S. degree in Electrical Engineering and Information Science from the University of Science and Technology of China (USTC), 1996, the M.Sc. degree in Electrical and Computer Engineering from the University of Virginia, 1999, and Ph.D. in Electrical and Computer Engineering from the University of Minnesota, 2002. He is now with the Department of Electrical and Computer Engineering at the Iowa State University. His interests are in the areas of signal processing, communications, and information theory. He currently serves as an associate editor for IEEE Transactions on Vehicular Technology and IEEE Signal Processing Letters.