Uplink Co-Channel Interference Analysis and Cancellation in Femtocell Based Distributed Antenna System
In wireless systems, coverage and capacity is a major challenge especially in high buildings. The need to reuse the limited available spectrum results in cochannel interference. Cochannel interference is a very critical factor affecting system performance. It limits the uplink coverage and capacity of wireless networks such as femtocells. Joint processing of the received signal among cochannel receivers has recently been shown to be very beneficial from an interference cancellation point of view. This paper proposes a femtocell based distributed antenna system (DAS) for uplink transmission in high buildings where distributed antenna units deployed on each floor of the building are connected to femto base stations (BS). The femto BSs can cooperate through joint signal processing for all cells in order to estimate the received signal, reduce cochannel interference introduced by frequency reuse among the femtocells and maintain high spectral efficiency. Analysis and numerical results show remarkable gains especially when interference cancellation is employed at each cooperative femto BS, leading to many more simultaneous users being supported on the same frequency and resulting in large capacity increase when compared with the traditional system with no interference cancellation technique.