Interference Suppression Strategy for Cell-Edge Users in the Downlink

In this paper we focus on the cell-edge users whose performance is severely limited by the interfering signals of diverse rates and strengths. In contrast to the suboptimal single-user detection, we propose an interference suppression strategy based on a low complexity matched filter (MF) based receiver. This proposed receiver exploits the structure of dominant interference in the detection process, instead of assuming it to be Gaussian and merging it in noise. This receiver is also characterized by the reduction of one complex dimension in the detection process thereby making it low complexity receiver structure. For comparison purposes, we also include the analysis of MMSE receiver and show that while MMSE detection loses one diversity order in the presence of one interferer, the proposed receiver recuperates the lost order of diversity. We further show that MMSE detection suffers from a coding loss as the interference gets stronger while the proposed receiver exhibits a coding gain as either the interference gets stronger or its modulation order decreases. Based on these results, we further propose a novel fractional frequency reuse (FFR) scheme for cellular systems.