Throughput improvement by precoding-based vertical plane beam control and cooperative MIMO transmission

Cellular mobile communication systems reuse the same frequency channel in geographically distant areas to improve the spectrum efficiency. However, co-channel interference among cells remains a critical issue. Mitigating co-channel interference leads to a further improvement in spectrum efficiency. To reduce the co-channel interference we proposed vertical plane beam control using precoding and cooperative MIMO transmission. Vertical plane beam control, which controls the vertical plane beam of base station antennas with the use of precoding, can improve overall cell capacity since SINR (Signal-to-Interference plus Noise Ratio) at each mobile station in the coverage area can be significantly improved. In cooperative MIMO transmission, adjacent base stations coordinate to transmit signals to cell-edge mobile stations. This technique can improve cell edge capacity, especially in low SINR areas. If the two techniques are used simultaneously, a synergetic effect can be expected; improved capacity in both the whole cell and cell edge. We propose here a method that combines vertical plane beam control with cooperative MIMO transmission. A computer simulation shows that the spectrum efficiency of the proposed system is approximately 2 times higher for the whole cell and 3 times higher for cell edge users than the conventional system.