Receiver design in multicarrier direct-sequence CDMA communications

Multicarrier direct-sequence code-division multiple access (MC-DS-CDMA) has emerged recently as a promising candidate for the next generation broad-ba nd mobile networks. In this paper, we consider the design of multiuser rece ivers for MC-DS-CDMA communications over fading channels. We present a clas s of spreading codes that enables the simple despreading-combining receiver to achieve the performance of optimum multiuser linear receiver. These cod es are shown to be optimum for independent fading channels under a code des ign criterion derived. Also derived are analytic solutions of optimum sprea ding codes for any given channel fading statistics. Simulation results are provided to demonstrate the significant gains in performance and simplicity due to the proposed techniques.