Opportunistic QoS Enhanced Scheduler for Real-Time Traffic in Wireless Communication Systems

The task of a packet scheduler for real-time traffic is to ensure that packet arrivals satisfy certain quality of service (QoS) requirements. At the same time, it is necessary to make efficient use of the limited capacity of the time-varying wireless fading channel. These two requirements are often in conflict to each other. Most existing schedulers either concentrate on the effective use of the radio resource, or only focus on QoS provisioning. By introducing the concept of flexible time and urgent time period, we propose an opportunistic QoS enhanced scheduler (OQES) which tries to maximize system throughput by exploiting the time-varying channel by applying multi-user diversity as well as a "meets delay" requirement. To avoid wasting bandwidth, a simple proactive packet discarding mechanism has also been introduced to discard packets that are to be dropped. Simulation results show that OQES outperforms existing schedulers for realtime traffic.