Unified power control, error correction coding and scheduling for aCDMA downlink system

Abstract

Transmitting multimedia data over a CDMA channel presents a new set of challenges. Sometimes, data demands will exceed the system capacity, in which case the system must make the most efficient use of its limited resources. The resources we consider are: fixed bandwidth available for each user and the transmit power budget for each cell. In this paper, we present our approach for unifying power control, variable forward error correction (VFEC), and scheduling for a downlink system by allocating the system resources. Our objective is to maximize the overall system satisfaction, which we call “system utility”. This objective is achieved by applying a distributed algorithm which divides the overall optimization problem into a hierarchy of three levels (system, cell and user). At each level, the system performs independent and parallel optimizations; the critical information is then passed to the higher level for further optimization. Finally, an iterative and distributed algorithm is applied at the system level to achieve the overall system optimization.