gain, and higher spatial diversity. The massive MIMO, as shown in Fig. 4.1, by using simple linear transmit processing schemes (e.g., ZFR/ZFT and MRC/MRT) can cancel co-channel interference, which significantly improves their SE with reduced complexity [4-9]. 4.4 Multi-hop Communication Multi-hop communication (commonly called as relay-based communication) has been extensively investigated to increase data rate, improve diversity, and expand coverage [10-14]. Consider a situation, where the user transmits a signal toward an intended receiver. In the absence of LoS, the received signal may experience higher probability of error. In such scenario, a third device known as relay is placed generally somewhere in between the transmitter and receiver. The relay receives the signal from the transmitter and retransmits toward the intended receiver. Figure 4.2 shows some practical relay deployments, resulting in increased coverage and capacity. Most commonly, relay either uses decode-and-forward or amplify- and-forward protocol. In decode-and-forward, the signal received at the relay is decoded first and then retransmitted to the receiver. On the contrary, with amplify- and-forward, the received signal is amplified and then forwarded to the receiver. Decode-and-forward relay has higher complexity due to the additional hardware E. Sharma and P. Singh Fig. 4.2 Installation of relays to extend coverage and capacity required for decoding, whereas amplify-and-forward relay suffers from amplified noise. 4.4.1 Full-Duplex Multi-Hop Communication Traditional wireless technologies transmit information by employing either frequency-division or time-division approach. This results in half-duplex communication. Full-duplex communication, on the other hand, as shown in Fig. 4 Full-Duplex Multi-Hop Communication for Beyond 5G Two-way communication Fig. 4.3 Two-way communication using full-duplex-capable devices 4.3, transmits and receives on the same time/frequency resource, doubling the SE of half-duplex system [15-21]. The full-duplex