In a spectrum-sharing heterogeneous network (HetNet), low-power cells such as femtocells are deployed jointly with macrocells, thereby generating interference. To tackle this critical issue in HetNets, we advocate a new interference mitigation concept that combines uncoordinated use of both interference cancellation and interference avoidance at the receiver and transmitter sides, respectively, to benefit from their relative advantages of higher throughput and lower cost, respectively. The resulting new strategy, MUCICA for Mitigation through Uncoordinated Co-channel Interference Cancellation and Avoidance, aims at enhancing the overall system capacity with least increase in computational cost and/or coordination overhead. As one concrete materialization of the new MUCICA concept, we propose on one hand a new downlink interference cancellation (DL-IC) strategy for spectrum-sharing LTE (Long Term Evolution) HetNet that reduces the interference impact on users by optimizing their received signal to interference plus noise ratio (SINR). On the other hand, we propose a dynamic interference avoidance strategy with macrocells' reduced power subframes referred to as dynamic low-power almost blank subframes (DLP-ABS) with reduced transmission power at some specific subframes. When implementing either DL-IC or DLP-ABS, system-level simulations do suggest that both global network performance and user experience in terms of total throughput and received SNR or link-level throughput, respectively, are significantly enhanced, indeed. However, much more significant gains both in performance and cost can be achieved under the new MUCICA concept by properly combining both new DL-IC and DLP-ABS interference mitigation strategies. Indeed, the latter do not require any extra coordination overhead in between and instead adopt each a relatively less stringent operation setup whose relaxation becomes possible owing to the simultaneous operation and unsupervised assistance of the other.
['Raouia Nasri', 'Sofiene Affes', 'Alex Stephenne']
MUCICA: A novel interference mitigation concept for HetNets — Application to the LTE downlink