Distributed Scheduling for QoS Control in Uplink CDMA

The enhancement of transmission speed of third generation cellular systems is yielded by packet scheduling techniques, which enlarge system capacity and improve bandwidth utilization by choosing the most suitable packet to be sent according to the instantaneous channel condition of mobile stations. However, since different types of traffic require different channel quality, considering the difference of quality-of-service (QoS) is important for designing a scheduling algorithm. Furthermore, the necessity of scheduling schemes to be able to handle for uplinks, in the future, will be much greater. In this paper, we propose heuristic QoS control for CDMA (HCQ), which is a distributed scheduling method for uplinks using channel information. In HCQ, MSs themselves decide when they should send their packets, and each MS independently adjusts the threshold to decide the packet-sending timing. Moreover, the threshold is modified based on the traffic type of sent packets. HCQ needs no complicated calculation and no extra overhead, and provides high effective throughput and delay performance. We evaluate the proposed scheme through computer simulations, and validate it from the results.