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A study on persistent scheduling for VoIP services in UMB system

In next-generation cellular systems including 3.9G and IMT-advanced systems, voice-over-IP (VoIP) services will be provided to users instead of conventional circuit switch-based voice calls. VoIP packets have peculiar characteristics that the packet length is short and packets are frequently generated. These phenomena require significant radio resources to send control channels in which resource assignment messages are conveyed ahead of VoIP packets transmission. In order to deal with this issue, persistent scheduling was proposed. There are several reports on persistent scheduling; however, sufficient study on it has not yet been conducted. This paper proposes persistent scheduling schemes that allow multiple resource usages using a threshold of queuing latency and then shows performance results based on ultra mobile broadband (UMB) system, which was standardized by the Third Generation Partnership Project 2 (3GPP2) as a 3.9G cellular system. Through computer simulations, it turns out that the proposed persistent scheduler gives improvement of 30% in terms of VoIP capacity compared to the basic persistent scheduler.