Wcdma System, Power Control, Rate Control And System Capacity

Transmission power control is one of the key techniques in CDMA systems. It can solve the "near-far problem" and reduce the Multiple-Access Interface (MAI) thus improve the system capacity greatly. In the future third generation communication system, it is endued with new requirements. In this paper, we discuss the power control, rate control and system capacity in WCDMA system. On the basis of all the existing works in narrow band CDMA communication systems, we adopt the forward link partial-balance power control algorithm and the reverse link distributed power control algorithm, which can provide necessary quality of service (QoS)(time delay and BER requirements) for multimedia traffics in WCDMA multimedia wireless system. Both of the two approaches can maximize the Eb /I0 of the services withlower priority orders at the condition for guaranteeing the QoS requirements of the services with higher priority orders. We also use the integrated transmission rate and power control algorithm according to the traffics' priority orders. It can maximize the channel usage and reduce the network block. At the end, based on the model of non-uniform distributions of users in multi-cell environment, this paper acquires the optimal received power of each traffic by iteration under ideal power control, then we analyze the received power under the condition of heavy loaded traffic and light loaded traffic in system.