On the Capacity of Relaying With Finite Blocklength

In this paper, relaying performance is studied under the finite-blocklength regime. The overall error probability of relaying is derived. Moreover, we investigate the blocklength-limited capacity (BL-capacity) of relaying. We prove that the BL-capacity of relaying is quasiconcave in the overall error probability. Therefore, the BL-capacity has a global maximum value, which can be achieved by choosing an appropriate error probability. Through numerical investigations, we validate our analytical model and compare the performance of relaying under the finite-blocklength regime versus the Shannon capacity regime.