Performance enhancement of DS-CDMA system using overlapping sectors with interference avoidance

A cellular system with overlapping sectors is proposed to enhance system performance through interference avoidance. In such system, users lie within the coverage of more than one sector, yet each user only chooses one sector for signal transmission and reception. The choices of sectors among different users affect the interference level experienced by others. It is shown in this paper that their mutual interference is minimized by choosing good sector combination. We investigate the potential benefits of proposed technique in two scenarios: orthogonal and non-orthogonal CDMA system. In the former case, spreading code allocation combined with sector selection reduces the required number of code to support all users compared to conventional non-overlapping sector system. For non-orthogonal CDMA system, the enhancement takes the form of multiple access interference reduction. Simulations results show that its improvement is pronounced and can be further enhanced by increasing the number of overlapping sectors.