Diversity techniques for reverse link of cellular DS/CDMA

Several diversity combining techniques are employed in a direct-sequence code-division multiple access (DS/CDMA) cellular system. The diversity receptions are combined using maximal ratio combining (MRC), equal gain combining (EGG), second-order selection combining (SC2) and a simplified version of MRC (SVM) that is simply a compromise between MRC and EGG. When the path loss exponent r=4, our results indicate that only MRC can significantly improve the system performance with a capacity gain of about 160% as compared to conventional detection with perfect power control. The other techniques investigated cannot improve the cellular CD/CDMA performance. However, when r is reduced to 2, all combining methods studied can enhance the cellular capacity dramatically. These diversity techniques are found to be effective in combating the problem associated with imperfect power control in cellular DS/CDMA