Amplify And Forward Full Duplex Relay OFDM Transmission Scheme

Recently, relay-assisted wireless communication system has been undergoing extensive development in both industry and academia. By receiving, processing, and retransmitting radio signals, relay networks oer an energy efficient and low cost solution to expand coverage of wireless connections. The two most typical relaying protocols are AF and decode-and forward (DF). The AF protocol outperforms the DF counterpart in terms of less computational demand and shorter processing delay.
An in-band full-duplex relay performs concurrent reception and transmission in the same frequency band, hence improving the spectral eciency signicantly. However, practical realization and implementation of full-duplex networks still confront numerous
challenges. One of the most noticeable problem is the so termed self-interference (SI), which directly results from the concurrent transmission and reception at the same frequency. The strong SI looped back from the transmitter at the relay node can easily diminish the throughput gain of the full-duplex relay system. A substantial amount of effort has been paid to the SI suppression techniques. For instance, directional antennas, or sufficient large separation distance between transmit and receive antennas, should be taken to partially remove the SI. A combination of RF interference cancellation, baseband digital interference cancellation as well as some other additional cancellation mechanisms, are also required to suppress the SI to a fairly low level.
Although the SI can be minimized by interference suppression techniques, residual self-interference still poses a main issue in reality and residual self-interference management is an indispensable requirement in the designs of all practical full-duplex relay networks.