Performance analysis of CDMA systems with integrated services

This paper analyzes the performance of unslotted code-division multiple-access schemes with integrated services, namely real-time voice services and nonreal-time data services. In order to support integrated services using common infrastructure, we apply dedicated mode transmission for real-time services and common channel transmission for nonreal-time services with varying processing gain. Most of the previous work covers the analysis of the system for fixed or exponential packet length, infinite population and infinite buffer size, where the results mainly depend on the mean values of the traffic. In this paper, we remove these assumptions and analyze the behavior of the system with respect to voice and data users for the more general and realistic case of finite population, finite buffers, and variable data-packet length. The emphasis is placed on the study of the effect of system parameters and user characteristics such as packet-length distribution on the system performance. Specifically, we show via analysis and simulation that even when the mean data-packet length is small, the system can have bottlenecks due to the packet-length characteristics and, therefore, dynamic adaptation and control of the system is required. Furthermore, we demonstrate that our analytical tool can be used to develop and analyze optimal resource-allocation strategies to maximize throughput of wireless systems with integrated services. It is shown that optimum variable system parameters (e.g., users' rate and power vectors, maximum packet length to be transmitted, number of users admitted to system) can be found when the system parameters (e.g., bandwidth) and quality-of-service requirements of multimedia services (e.g., delay and loss bounds) are given.