On the performance of full-duplex relaying schemes for point-to-point MIMO with large antenna arrays

The performance of full-duplex (FD) decode-and-forward (DF) relaying systems for point-to-point multi-antenna transmission is considered. Three different relaying schemes are investigated: co-located, distributed cooperative and distributed non-cooperative. To mitigate the effects of loop interference (LI) caused by FD operation at the relay, a digital cancellation scheme based on pilot-aided channel estimation is used. Asymptotic analysis shows that all considered systems are inter-pair and LI free when the number of antennas at the source and destination grows without bound while the relay has a finite number of antennas. More careful analysis of the achievable rate reveals, however, that the LI has a significant impact on the performance of finite sized systems. The numerical results illustrate that non-cooperative distributed relaying suffers severely from FD operation under realistic scenarios, while cooperation allows for efficient LI cancellation and improved spectral efficiency over half-duplex (HD) systems. The results also demonstrate that the optimal number of antennas used by a FD relay is only 10%-30% of the size of the array used at the source and destination, while HD relaying benefits from fractions of up to 50%