Zero-Forcing Precoding With Partial CSI in Multibeam High Throughput Satellite Systems

Precoding has emerged as a prominent technique to mitigate interbeam interference (IBI) in the forward link of a multibeam high throughput satellite system. In this paper, we consider zero-forcing (ZF) precoding to mitigate IBI. To reduce the channel state information (CSI) feedback from the user terminals, which consequently reduces the latency and signaling overheads, we design a ZF precoder with matrix and vector normalizations using partial CSI and analyze its ergodic SR performance. We consider a practical scenario where the links between the satellite and user terminals are affected by rain fading attenuation and derive an analytical expression, upper and lower bounds, and asymptotic (in terms of transmit power) approximations for the ergodic SR achieved by this ZF precoder. Many important insights are obtained from these results. Also, the robustness of this ZF precoder to CSI estimation errors is numerically analyzed.