Mobile Networks A hybrid multirate MAC protocol providing trade-off between throughput and fairness in future TD-CDMA networks

In this paper, a hybrid, frequency division duplex (FDD), time division–code division multiple access (TD-CDMA), medium access control (MAC) protocol is proposed. Both multicode (MC) and orthogonal variable spreading factor (OVSF) transmission modes are used in order to utilise the system resources more efficiently. Moreover, a new rate-scheduling algorithm is developed, aimed at providing a trade-off between throughput maximisation and fairness, while satisfying QoS requirements. The above scheme is formulated as a constrained optimisation problem, which maximises the sum of normalised rates instead of throughput in order to achieve fairer rate allocations, while maintaining throughput at a high value. A new optimisation constraint is introduced in order to deal with the discrete set of available rates that the hybrid MC-OVSF scheme supports. Copyright © 2009 John Wiley & Sons, Ltd.