Balancing system throughput and fairness in multi-user OFDMA-TDD using busy bursts

This paper analyses busy burst (BB) enabled interference avoidance for multi-user orthogonal frequency division multiple access (OFDMA) in a Manhattan grid deployment scenario. Upon successful reception of data, the receiver transmits a BB in a time-multiplexed mini-slot. Exploiting the channel reciprocity of time division duplex (TDD), an exclusion region around a victim receiver is established, where potential transmitters are denied access to reserved resources. The size of the exclusion region is determined by a threshold parameter, known to the entire network. System level simulations compare the system and user throughput of BB enabled interference avoidance with greedy resource allocation that does not attempt to avoid interference. It is shown that by adjusting the BB threshold parameter, system throughput can be traded with fairness in terms of cell-edge user throughput. By tuning the BB threshold, either up to 45% increase in system throughput or up to 7-fold increase in cell-edge user throughput are feasible compared to greedy resource allocation. Moreover, by an appropriate adjustment of the BB power further gains in system throughput without compromising fairness are achieved.