Robust Interference Exploitation-Based Precoding Scheme With Quantized CSIT

We propose a new precoding scheme that can exploit interference constructively when a base station (BS) is provided with quantized channel state information (CSI) in multiuser multiple-input single-output (MU-MISO) systems. In the proposed scheme, interference is decomposed into predictable interference, manipulated constructively by a BS, and unpredictable interference, caused by the quantization error. To reduce performance loss by unpredictable interference, we first derive the upper bound of the unpredictable interference. Then, the BS aligns the predictable interference so that its power is much greater than the derived upper bound. During this process, to intensify the received signal power, the BS simultaneously aligns the predictable interference so that it is constructively superimposed with the desired signal. Simulation results show that the proposed scheme achieves improved symbol error rates (SERs) compared with existing precoding schemes, especially with a high modulation level.