Analysis of interference-aware receivers in heterogeneous LTE networks

The concept of heterogeneous networks (HetNets) has been introduced in LTE-Advanced systems in order to improve overall capacity and cell-edge user performance. However, such uncoordinated deployments sharing the same spectrum present new interference issues that are difficult to combat with conventional interference management schemes. In this paper interference issues in a macro-femto scenario in LTE-Advanced downlink, where all eNodeBs allocate the same resources, have been investigated. The interference-unaware Maximum Ratio Combining (MRC) receiver, the MRC receiver with prewhitening and an interference-aware receiver with switching principle are applied at the user equipment (UE) and their performance investigated for different interference levels using Monte-Carlo simulations. The results have shown that the interference-unaware MRC receiver is not suitable in HetNet deployments, as it saturates in error-floor at an intolerable bit error ratio. The MRC receiver with prewhitening mitigates the impact of interference and delivers acceptable performance. However, further improvements can be achieved by applying the interference-aware receiver with switching principle. To combat interference in interference rich scenarios, a switching principle between the MRC receiver with prewhitening and non-linear interference cancellation with prewhitening has been introduced and its performance investigated. The results have shown that by cancelling the interference only when necessary, the interference-aware receiver with switching principle can guarantee robust and reliable performance in interference rich scenarios. When the amount of interference decreases, the MRC receiver with prewhitening is sufficient for data reception.