Coordinated precoding and proactive interference cancellation in mixed interference scenarios

In heterogeneous cellular networks, cross-tier inter-cell interference is often in mixed interference scenario where the macro-cell causes strong interference to pico-cells while pico-cells only cause weak interference to the macro-cell. In this scenario, the popular interference coordination schemes using power control or time/frequency division multiplexing are far from achieving the spectrum efficiency potential. Exploiting the difference of transmit powers and channel gains in heterogeneous networks, the transmission schemes based on interference cancelation have great opportunity to gain more throughput benefit. In this paper, we propose a coordinated precoding and proactive interference cancelation scheme, where the precoding design is based on the known decoding order and is to maximize the sum-rate of two interfering users. Since the optimization problem is non-convex, we find a local maximum by constructing a concave lower bound of the objective function and iteratively tightening it. Simulation results show that the network throughput is remarkably improved in mixed interference scenarios relative to orthogonal division scheme and coordinated multipoint transmission scheme with zero forcing precoding.