A simple minimum rate supporting scheduler for UTRA/TDD high speed downlink packet access

Abstract

A Minimum Rate Supporting Scheduler (MRSS) is proposed in this paper. MRSS guides the user selection in order to provide, if any, a prespecified minimum rate for each user. The minimum rate, however, is not always guaranteed especially when the traffic offered in downlink is heavy or excessive. In this case, additional call admission control is necessary, which falls outside the scope of the present paper. MRSS is numerically evaluated to show to what extent of the offered traffic the scheduler could provide the minimum rate. A main advantage of MRSS is its simplicity. MRSS causes little attendant increase in complexity compared to Proportional Fairness Rate Scheduler (PFRS) that is currently implemented in cdma2000 1xEV. Thus, MRSS is also implementable. Numerical evaluation of the performance for MRSS is done under UTRA/TDD HSDPA environments. The results show that it support to keep the minimum rate up to fairly high traffic load where existing methods fall and achieves better throughput than PFRS. Therefore, MRSS is a simple, minimum rate supporting, and performance-enhanced scheduler that is possibly used in practical 3G mobile systems.