Diversity combining in antenna array base station receiver for DS/CDMA system

This paper analyses a few schemes for combining base station antenna array signals in wireless DS/CDMA. The performances of equal gain combining (EGC), likelihood rank test (LRT) and a modified rank test (MRT) are evaluated using simulation studies. The results indicate that, under certain assumptions on the multiple access interference statistics, the probability of error of the MRT is lower than that of EGC, if a few high power interfering users are present along with a low power user of interest. If there are a moderately large number of users and if the received power of all the users are nearly the same, then EGC outperforms the MRT. In fact, under this condition, the performance of EGC is close to that of the optimal likelihood ratio test.