PERFORMANCE ENHANCEMENT THROUGH JOINT DETECTION OF COCHANNEL SIGNALS USING DIVERSITY ARRAYS

Joint detection based on exploiting differences among the channels emp loyed by several users allows a receiver to distinguish cc,channel sig nals without reliance on spectrum spreading. This paper makes a number of new contributions to the topic: it provides an analytical expressi on for the union bound on average symbol-error rate for an arbitrary n umber of users and diversity antennas in a fading environment, for bot h perfect and imperfect channel state information (CSI), and it compar es the performance of joint detection with diversity antennas against classical maximum-mean-square-error (MMSE) combining. The performance is remarkable. With accurate CSI, several users can experience good pe rformance with only a single antenna; moreover, for perfect CSI, only a 2-dB penalty is incurred for each additional user, With several ante nnas, many more users than the number of antennas mag be supported wit h a slow degradation in performance for each additional user. Furtherm ore, high accuracy is not required from the channel estimation process . In all cases, the performance of joint detection exceeds that of MMS E combining by orders of magnitude.