Downlink beamforming algorithms with inter-cell interference in cellular networks

We study the issue of handling unknown inter-cell interference in multi-cell environments with antenna arrays at the base stations. First, we demonstrate that the presence of unknown inter-cell interference that cannot be predicted accurately, can significantly degrade the system performance when unaccounted for. Second, we propose two algorithms that are aimed at providing a quality-of-service guarantee in the form of packet error rate (PER) in the presence of unknown inter-cell interference. The first algorithm is based on a derived expression for average PER as a function of the distribution of experienced signal to interference and noise ratio and dynamically adjusts the input parameters based on the channel condition and interference. The second algorithm makes use of the observation that the distribution of inter-cell interference experienced by a mobile can be well approximated by a log-normal distribution. We demonstrate that these algorithms achieve the target PER