In this work, for a CDMA communication, the per user carrier-to-interference ratio (CINR) enhancement in the Reverse Link (mobile to base station) is analyzed using different antenna array spatial combining algorithms: Optimal Combining (OC) Versus Maximal Ratio Combining (MRC) in a multi-rate (combined voice and data users) multi-antenna scenario. The ratio of the CINR for OC vs. MRC is directly analyzed, i.e. Z=CINROC/CINRMRC. Exact solutions are derived for the statistics of a per user CINROC/CINRMRC improvement, as a function of the high-level interference power to background noise, the gain ratio CINROC/CINRMRC is evaluated in a flat Rayleigh fading communications system with multiple interferers, when the number of interferences L is no less than the number of antenna elements M (L M). The gain ratio is derived providing a simple means to determine when OC will exhibit significant gains over MRC. simulations are done to find out the BER performance of optimum combining diversity in correlated Nakagami-m channels and compare with the BER performance of MRC and the influence of interference for MRC and OC are analyzed and discussed"

Wireless technology provides an array of applications viz wireless phones, wireless Internet access &WLAN.These systems are prone to performance degradation due to multipath fading, pol. mismatch So Service, Quality, Security and Capacity are of primary importance.To solve these space time processing is used, that is signal processing performed on a system in both the spatial and temporal dimensions of the radio cannel.These can be applied at the Tx or Rx or both.At the Receiver MIMO techniques are used.Rx Diversity schemes are MRC, EGC &SC.Of these MRC is considered as it provides the maximum SNR at the output.In MRC the output signal is the weighted sum of the input signals present at the input of the array.In a practical combiner the channel can never be estimated perfectly because of multipath fading. This results in errors in channel estimation which effect the weighing factors of the combiner.The performance of the MRC degrades w.r.t.output SNR and BER. Here the effects of imperfect channel estimation resulting in gaussian errors in the weights of MRC are studied.Performance of MRC in different fading channels with imperfect channel estimates & digital mod.tech. is analyzed.