Joint user scheduling and power control for cell-edge performance improvement in backhaul-constrained network MIMO

Intercell interference severely degrades the performance of cell-edge users in cellular networks. To effectively manage the intercell interference, a heuristic scheme that jointly considers user scheduling and power control is proposed for multicell orthogonal frequency division multiple-access (OFDMA) networks with BS cooperation and limited backhaul capacity. First, a greedy user scheduling is proposed, taking both channel gain and the cost of directional cooperation into consideration. This scheme schedules the cell-edge users of all cells in the same subchannels. Second, under the guiding of user scheduling, the interference among cell-edge users of different cells can be preferentially cancelled with zero-forcing precoding. Third, a two-step power control is conducted to further improve cell-edge users performance. In the first step, with the strong duality of the nonconvex optimization subproblem, we obtain the minimum power consumption that guaranteeing the cellcenter users' rate requirement. In the second step, the residual power of per cell can be utilized to maximize cell-edge users performance. Then, with the fixed user scheduling, the iteration among interference cancelation and power control can be conducted until the backhaul capacity constraints are satisfied. Performance analysis proves the convergence of the proposed algorithm, and shows the effectiveness of the user scheduling. Simulation results show that, the proposed algorithm achieves a significant improvement of sum-rate for cell-edge users with negligible rate degradation for cell-center users.