Centralised Approaches to Subcarrier Allocation for OFDM-based 802.16 Systems Operating in License-exempt Mode

In this paper, three approaches to allocating resources between interfering IEEE 802.16 systems operating in license exempt mode are described. The schemes differ in terms of how they implement the fairness/utilisation trade-off. The three schemes are Throughput Maximisation (ThM), Maximum Fairness (MaF), and a Neighbour Based Resource Allocation (NBRA) approach which produces an approximately fair allocation, but makes more efficient use of any unallocated resources. The three schemes are compared in terms of their overall throughput and the fairness they can deliver. They are also compared with results obtained by a distributed algorithm we proposed in previous work. It is shown that the NBRA approach gives the best throughput/fairness trade-off. Also, the results show that the distributed approach significantly underperforms the full-knowledge resource allocation schemes described here.