Fairness of scheduling algorithms for real-time UMTS traffic in case of IP link congestion

In order to achieve end-to-end Quality of Service for next generation of mobile phones that will be all-IP based, IP QoS mechanism such as DiffServ should be applied to UMTS technology. A mapping of UMTS classes to DiffServ Code Points can be used in order to get efficient PHB configurations. DiffServ have limitation problems regarding implementation of PHB groups and choosing the appropriate traffic scheduling algorithm. This paper presents evaluation results of a simulation based study on the fairness of traffic scheduling algorithms for UMTS real time traffic that passes through UMTS core network and external IP backbone network, based on DiffServ. In this paper link congestion effect on critical performance metrics of conversational and streaming traffic classes is investigated in case that WFQ, WRR, PQ and LLQ are implemented as schedulers at network nodes. The aim of simulation is to determine which scheduling algorithm has the best performances and provides IPTD, IPDV and IPLR for conversational and streaming traffic classes below standard defined values, but not to completely exhaust bandwith for interactive and background traffic classes.