Full-Duplex Relay in High-Reliability Low-latency Networks Operating with Finite Blocklength Codes

We consider a full-duplex (FD) relaying network operating with finite blocklength (FBL) codes. Based on Polyanskiy's FBL model, we characterize the FBL reliability of the relaying network under both decode-and-forward (DF) and amplify-and-forward (AF) relaying schemes. Following the model, we provide reliability-optimal designs via optimal power allocation for both schemes. In particular, for the FD DF relaying scheme, we prove that the (tightly approximated) overall error probability is convex in the transmit power at the relay. In addition, we show that minimizing the overall error probability of the FD AF relaying is equivalent to maximizing the overall signal to interference plus noise ratio (SINR), and further prove that this SINR is pseudo-concave in the transmit power of the FD AF relay. Via numerical analysis, we validate our analytical model and illustrate the performance of the considered FD relaying networks with different latency constraints, power levels of the residual loop interference, and data packet sizes. Moreover, we compare the performances of FD AF and FD DF relaying schemes, while the performance of direct transmission is provided as a reference.