On the Performance of Zero-Forcing Processing in Multi-Way Massive MIMO Relay Networks

We consider a multi-way massive multiple-input multiple-output relay network with zero-forcing processing at the relay. By considering the time-division duplex protocol with channel estimation, we derive an analytical approximation of the spectral efficiency. This approximation is very tight and simple, which enables us to analyze the system performance, as well as to compare the spectral efficiency with zero-forcing and maximum-ratio processing. Our results show that by using a very large number of relay antennas and with the zero-forcing technique, we can simultaneously serve many active users in the same time-frequency resource, each with high spectral efficiency.