Near-far resistance of linear receivers in chip asynchronous CDMA systems with random signatures

This paper examines the robustness of the linear receivers, such as the MMSE and the decorrelating receivers, against the near-far problem in chip asynchronous random DS/CDMA systems. In asynchronous CDMA systems, both of those linear receivers achieve the optimum near-far resistance by employing infinite-bit-long observation windows. We develop simple tight upper and lower bounds on the average optimum near-far resistance. It is shown that the average optimum near-far resistance of the asynchronous system is upper bounded by that of the synchronous system. These bounds converge to the average optimum near-far resistance of the synchronous system as the processing gain and the number of users approach infinity. A simulation study was performed to characterize the average optimum near-far resistance for finite processing gain systems