Scheduling Techniques for Improving Call Capacity for VoIP Traffic in MIMO-OFDMA Networks

Fourth generation networks will almost invariably adopt OFDMA (orthogonal frequency division multiple access) and MIMO (multiple input-multiple output) technologies, in order to meet high data rate and quality of service (QoS) requirements. The worldwide interoperability for microwave access (WiMAX) MAC Layer, which is based on the IEEE 802.16 standard, is designed to support a variety of applications, including voice and multimedia services. The problem of providing QoS in broadband wireless systems is one of managing radio resources effectively. Efficient scheduling algorithms that balance the QoS requirements of each application and user with the available radio resources need to be developed. This paper considers a number of scheduling policies concentrating on real-time voice over IP (VoIP) traffic. Via numerical results we show that the conventional notion of fairness fails to guarantee service for low latency applications such as VoIP for an increasing traffic load. We show better QoS is achieved via a greedy scheduling approach that manages to serve packets faster.