Downlink beamforming algorithms with inter-cell interference in cellular networks

We study the application of antenna arrays at the base stations in a multi-cell environment. Simulation results demonstrate that the inter-cell interference significantly degrades the system performance in terms of packet loss probability (PLP) and total throughput. In order to cope with the presence of inter-cell interference in multi-cell networks we propose two algorithms: the first algorithm replaces the noise term in the beamforming algorithm by the sum of average inter-cell interference and noise, and is shown to perform well for certain type of link curves. We derive an expression for the average PLP as a function of the target SINR value corresponding to the target PLP. This expression tells us that the average PLP does not equal the target PLP in general, and offers an explanation for the good performance of the first algorithm for some link curves. Based on this expression, the second proposed algorithm makes use of more than just the mean of the SINR distribution in the beamforming algorithm. The experimental results demonstrate that this algorithm achieves the target PLP with general link curves and different scheduling algorithms under various wireless channel models. We characterize the inter-cell interference distribution for different scheduling and beamforming algorithms under various channel models. It is shown that the inter-cell interference can be well approximated by a log-normal random variable and exhibits weak temporal correlation.