Combined Interference Cancellation and Avoidance over the Downlink of Spectrum-Sharing LTE HetNet

Abstract

In a spectrum-sharing heterogeneous network (Het- Net), low-power small cells such as femtocells are deployed jointly with macrocells. This new cell layer generates interference that degrades network performance. To mitigate this critical issue in HetNets, we combine both interference cancellation and interference avoidance to benefit from their respective advantages on the downlink of LTE (Long Term Evolution). On one hand, a new downlink interference cancellation (DL-IC) strategy reduces the interference impact on users by optimizing their received signal to interference plus noise ratio (SINR). On the other hand, a new low-power almost-blank subframes (LP- ABS) policy minimizes the effect of downlink interference on femtocells and neighboring macrocells by reducing the transmit power of macrocells during special subframes. When implementing DL-IC and LP-ABS separately, 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 complexity can be achieved by combining newly proposed DL-IC and LP-ABS interference mitigation strategies.