Pizza Party Algorithm for Real Time Distortion Management in Downlink Single-Cell CDMA Systems
Zhu Han, Andres Kwasinski, K. J. Ray Liu, Nariman Farvardin · 2003
In the interference-limited CDMA networks, the maximal number of users of real time applications can be increased by smoothly increasing the end-to-end distortions. In this paper, each user can accept a range of carefully controlled distortions. We develop a system protocol to control each user’s distortion by adapting the resources like source coding rate, channel coding rate, transmit rate, and transmitted power. We want to reduce the overall distortion in downlink single-cell systems, under the constraints of users’ maximal distortions and the maximal transmitted power from the base station. In order to solve such a difficult problem, inspired by an event of everyday life, we develop a heuristic and fast adaptive algorithm to allocate these resources for different users. The idea is to initialize the resource allocation with the maximal distortion for all users, and then allocate the remaining transmitted power quota first to the user who can most easily be satisfied when reducing its distortion. This user must have a high distortion, have a good channel condition, or generate small interferences to others. The allocation process is continued, until the transmitted power is used up. From the simulation results, our proposed algorithm fundamentally reduces the distortions and the necessary maximal transmitted power when the number of users is large, compared with a traditional CDMA scheme (with no distortion control).