Analysis and management of heterogeneous user mobility in large-scale downlink systems

Modern cellular networks need to serve user terminals with large disparities in mobility, which incurs different accuracy of the channel state information for each user. The impact of such heterogeneous mobility on the multi-cell downlink is analyzed in this paper. The base stations serve a multitude of users by coordinated beamforming. We derive deterministic equivalents for the user performance in a large scale system where the number of transmit antennas and user terminals grow large at a fixed ratio. We show that low and high mobility users can coexist and be served simultaneously, since the CSI imperfections of a user only harms the performance of this particular user. Simulations are used to verify the applicability of our large scale approximations for systems of practical dimensions. Furthermore, we show that the performance of high mobility users can be improved by explicitly managing the user priorities in the network.