A multirate DS-CDMA system

Abstract

A rapidly growing interest in third generation Personal Communication Networks has underlined the importance of wireless multimedia systems that can support voice, video, images, files, or any combinations thereof. In order to ensure satisfactory quality of service (QoS) for individual multimedia traffic, a new analysis with a new user model based on circuit-switched direct-sequence Code Division Multiple Access (DS-CDMA) system is presented. The new user model is introduced to allow users to transmit data at multiple bit rates and to switch to other bit rates at any time. To facilitate performance analysis, each traffic type with rate s is assumed a probability ps for user k. To ensure satisfactory QoS, a new power control scheme is further proposed for a multimedia circuit-switched DS-CDMA system. Specifically, a new closed-form power control function is introduced to ensure quality of service for each traffic type and to achieve a better overall throughput at the same time. Central to the new closed-form power control function is a parameter called the traffic exponent. By introducing this parameter, the difficulty in obtaining an optimal closed-form power control function is reduced which simplifies the information feedback process from the base station to the mobile stations.