0 user pairs and N = 64,256 relay antennas. Pi = PR/2K, for 1,..., 2K, i.e., equal power to all users. the SI at the relay OLIR as well as the SI and IUI at the user = 0 dB for k, i = 1,...2K with respect to o2. Figures 4.8 and 4.9 show the SE versus SNR and SE versus K comparison of MRC/MRT and ZFR/ZFT beamforming for full-duplex multi-pair system. Note that SE saturates for high SNR values, since the relay SI increases proportionally upon increasing system SNR. The SE initially increases, but for large K it starts decreasing. This is because of the increased inter-pair interference coming from increased number of user pairs. Figure 4.10 compares the SE versus N for half-duplex and full-duplex system with MRC/MRT beamforming. In our framework, SE of half-duplex massive MIMO relaying can be obtained by substituting the SI and IUI to zero. We see that for full-duplex systems, as we increase the value of SI and IUI, i.e., LIL and ou, the SE of full-duplex system decreases. We see from Fig. 4.10 that the full-duplex system has higher SE than a half-duplex system for = = 0 dB. For lower SI suppression, i.e., = oul = 10 dB, the half-duplex performs better than full-duplex. Note that with the increase in N, the rate of increase of SE in case of half-duplex relay is lower as compared to its half-duplex counterpart. E. Sharma and P. Singh Monte-Carlo (MRC/MRT) Monte-Carlo (ZFR/ZFT) SNR [dB] Fig. 4.8 SE versus PR comparison of MRC/MRT and ZFR/ZFT beamforming, where K = 10 ZFR/ZFT SNR=10dB MRC/MRT MRC/MRT SNR=-10dB ZFR/ZFT Number of user pairs (K) Fig. 4.9 SE versus K with N = 128 4 Full-Duplex Multi-Hop Communication for Beyond 5G Fig. 4.10 SE versus N for MRC/MRT processing, 02 - 10 dB, =-10 dB- comparing half-duplex and full-duplex systems. Here 200BB SNR = 10 dB 2 10 dB, 2 5 dB Half-duplex Full-duplex Number of relay antennas (N) 4.11 Summary and Future Works This chapter considered a system model in which multiple pairs of full-duplex users want to communicate with each other via full-duplex massive MIMO two- way rela