Closed-loop power control for DS-CDMA

Abstract

DS-CDMA is a multiplexing technique where a number of users simultaneously and asynchronously access a channel by modulating and spreading their information-bearing signals with preassigned signature sequences. Due to the near-far problem, the users' signals vary at the base station and this limits the performance of DS-CDMA systems. In this work, a Closed-Loop Power Control (CLPC) algorithm is proposed to balance the signal powers. The user powers are first estimated using correlation values and then they are iteratively equated at the receiver. Training bits are used to accurately estimate the user powers in the proposed algorithm. It is shown that the algorithm is effective in improving the performance of the system by reducing the Bit Error Rate (BER) in near-far situations.