Variable quality of service in CDMA systems by statistical power control

The low bandwidth and high error rates of the wireless channel make joint source-channel coding desirable for optimizing resource usage. The authors argue that a mechanism for providing variable quality of service (QOS) is essential for joint source-channel coding, and show that its implementation by way of power control is a natural choice for CDMA. Present-day power control techniques focus on controlling interference. The authors present a power control algorithm which simultaneously minimizes interference and provides variable QOS contracts for different traffic types in a CDMA system. The algorithm accommodates different QOS requirements by assigning different power levels to each traffic type, and can add or drop connections dynamically while ensuring that QOS specifications are satisfied. Both the uplink and downlink are analyzed, and the scheme is statistically formulated to handle variable-rate traffic.