Transformation matrix algorithm for reducing the computational complexity of multiuser receivers for DS-CDMA wireless systems

Abstract

Multiuser detection is an important technology in wireless CDMA systems for improving both data rate as well as user capacity. However, the computational complexity of multiuser detection prevents the widespread use of this technique. Most of the CDMA systems today and in the near future will continue to use the conventional matched filter with its comparatively low user capacity and a slow data rate. However, if we could lower the computational complexity of multiuser detectors, most of the CDMA systems would be likely to take advantage of this technique in order to gain increased system capacity and a better data rate. In this paper, a novel approach for reducing the computational complexity of multiuser receivers is proposed. It utilizes the transformation matrix technique to improve the performance of multiuser detectors. We show that the mathematical computations of the implementation complexity can turn in overall less complex system that has strong impact on the system's signal to noise ratio (SNR) and the bit error rate (BER). The performance measure adopted in this paper is the achievable bit rate for a fixed probability of error (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> ) and consistent values of SNR.