Framework for Analysis of Transmission Rate Scheduling for Wireless CDMA Data Networks

Abstract

The optimal utilization of network resources and the capacity to fulfill quality of service requirements are key requirements for 3rd G networks operations. Several burst admission and transmission rate scheduling algorithms are proposed in the literature. In this study, we develop an analytical framework for the downlink transmission rate scheduling problem for CDMA networks employing discrete service bit rates. The framework uses the average downlink transmit power as the system state and develops a K-dimensional Markov chain representing all possible states in the system. In addition, the transition probabilities due to arrivals of burst requests are made a function of the power utilization and the average power required to support the new burst taking into account the path loss model. The study assumes a transmission rate assignment scheme where the maximum possible system bit rate is assigned given the current system state and the subscriber's eligibility profile for particular system service rates. The analytical model provides performance metrics such as system throughput, average power utilization, average number of simultaneous transmissions, burst request blocking probability, and mean burst service time. While the developed model is applicable for a general CDMA based network with arbitrary discrete system service bit rates, the model is evaluated for the example of a cdma2000 1xRTT network. A comparison between simulation and analytic results to assess the accuracy of the model is provided.