Small Cell In-Band Wireless Backhaul in Massive MIMO Systems: A Cooperation of Next-Generation Techniques.

Massive Multiple-Input Multiple-Output (MIMO) systems, dense Small-Cells (SCs), and full duplex are three candidate techniques for next-generation communication sys- tems. The cooperation of next-generation techniques could offer more benefits, e.g., SC in-band wireless backhaul in massive MIMO systems. In this paper, three strategies of SC in-band wireless backhaul in massive MIMO systems are introduced and compared, i.e., Complete Time-Division Duplexing (CTDD), Zero-Division Duplexing (ZDD), and ZDD with Interference Rejection (ZDD-IR). Simulation results demonstrate that SC in-band wireless backhaul has the potential to improve the throughput for massive MIMO systems. Specifically, among the three strategies, CTDD is the simplest one and could achieve decent throughput improvement. Depending on conditions, with the self-interference cancellation capability at SCs, ZDD could achieve better throughput than CTDD, even with residual self- interference. Moreover, ZDD-IR requires the additional interfer- ence rejection process at the BS compared to ZDD, but it could generally achieve better throughput than CTDD and ZDD.