Interference Precancellation in Multiuser Vector Broadcast Channels Using PSK Modulation

The low cost, energy efficiency, and resilience of constant-envelope modulations to power amplifier nonlinearity make them appealing for multi-antenna multiuser systems in 5G and beyond. This paper proposes a linear zero-forcing (ZF) and a non-linear ZF Tomlinson-Harashima precoder (THP) based precoding scheme for downlink multiuser MIMO systems with arbitrary-sized PSK modulation. The proposed scheme achieves perfect persymbol multi-user interference (MUI) cancellation, enabling high throughput with minimal delay, cost, and complexity. The precoder structure is relatively easy to implement, involving straightforward matrix calculations. Analytical and simulation results demonstrate that the MUI is perfectly cancelled, and the bit-error rate decreases unboundedly with increasing SNR.