Base station beamforming technique using multiple signal-to-interference plus noise ratio balancing criteria

The authors propose a coordinated multi-cell beamforming technique for signal-to-interference plus noise ratio (SINR) balancing under multiple base station power constraints. Instead of balancing SINR of all users in all cells to the same level, the authors´ propose a new approach to balance SINR of users in various cells to different maximum possible values. This has the ability to allow users in cells with relatively more transmit power or better channel condition to achieve a higher balanced SINR than that achieved by users in the worst-case cells. This multi-level SINR balancing problem is solved using SINR constraints based SINR balancing criterion and subgradient method. The simulation results support the optimality of the results through comparison with semi-definite programming-based optimisation.