Investigation on Advanced Receiver Employing Interference Rejection Combining in Asynchronous Network for LTE-Advanced Downlink

The interference rejection combining (IRC) receiver, which can suppress inter-cell interference, is effective in improving the cell-edge user throughput. The IRC receiver is typically based on the minimum mean square error (MMSE) criteria, which requires highly accurate channel estimation and covariance matrix estimation that includes the inter-cell interference. To do this, the channel estimation and covariance matrix must be averaged within a subframe, i.e., 1 msec. However, the source of the inter-cell interference is changed within one subframe of the covariance matrix estimation due to the change in the user allocation at the interfering cells if asynchronous networks are employed. This affects the performance gain of the IRC receiver. This paper investigates the impact on asynchronous networks and the gain from the IRC receiver in terms of the downlink user throughput performance. Simulations results based on a 57-cell model environment, i.e., a cellular environment in the LTE-Advanced downlink, show that the IRC receiver which has two antenna branches effectively suppresses the inter-cell interference even when asynchronous networks are employed.