Downlink Soft Handover Using Multi-Cell MIMO for 4G-LTE Smart-Phones

A downlink soft handover scheme is proposed for cell edge users in 4G-LTE systems. To avoid capacity loss in cell edge areas the proposed handover scheme uses multi-cell MIMO cooperated by multiple base stations. In the proposed scheme, different multi-cell MIMO transmissions are adaptively exploited based on the spatial correlation of a downlink channel and path loss of adjacent cells by comparing ergodic link level capacity. Unlike single-cell adaptive MIMO transmission, the proposed scheme optimizes the subset of antennas from two or more base stations to exploit the spatial decorrelation. Numerical results show that the proposed handover scheme significantly improves the cell edge capacity over the single-cell adaptation in the presence of spatial correlation particularly for handover regions.