Effect of Introducing Predictive CIR on Throughput Performance in HSDPA Networks

Predicting wireless environment parameters as correctly and timely as possible is of practical importance to optimal resource allocation in wireless systems. For example, as the realtime wireless condition information is not available in reality due to delay, the latest historic wireless environment parameters are used to determine the users´ instantaneous transmission rate in most of the existing systems in high-speed downlink packet access (HSDPA) networks. However, the wireless condition variation during this delay (e.g., 6 ms) sometimes results in unsuitable determination of the instantaneous transmission rate and eventually influences the user and system performance. It is shown by simulation results that compared with using the ideal realtime wireless environment information, using the latest available historic information will introduce about 10%-15% throughput performance damage averagely. Therefore, in this paper, in order to mitigate such performance degradation, a simple linear prediction of the current wireless environment parameters is introduced. Simulation results demonstrate that nearly 10% improvement can be achieved under several well-known scheduling algorithms in a HSDPA network when the predictive environment parameter is applied to determine the instantaneous transmission rate