In wireless communications, relaying is well known as an efficient way to mitigate wireless fading by exploiting spatial diversity However, typically these studies were based on the ideal assumption of communicating arbitrarily reliably at Shannons channel capacity, i.e., coding is assumed to be performed over an infinite blocklength. In the finite blocklength (FBL) regime, especially when the blocklength is short, the error probability (due to noise) becomes significant. To address this issue, an accurate approximation of achievable coding rate was identified by Polyanskiy for a single-hop transmission system while taking the error probability into account. As shown in Fig. 1, a significant performance gap is observed in the comparison between the two performance model, i.e., the Shannon capacity is not accurate for low-latency short blocklength systems. Subsequently, Polyanskiys initial work regarding AWGN channels were extended to Gilbert-Elliott Channels, quasistatic fading channels, quasi-static fading channels with retransmissions , as well as spectrum sharing networks. However, all these works focused on single-hop non-relaying systems, leaving the analysis of relaying in the finite blocklength regime an open problem.

Scientific Approach

We provide a detailed analysis of the performance of single-relay networks, multi-relay networks, relay assisted multi-terminal indstrial network, relay-assisted non-orthogonal multiple access (NOMA) network, relay-enabled simultaneous wireless information and power transferring (SWIPT). Moreover, the obtained analytical insights will be utilized to derive guidelines for the design of QoS-efficient and reliable networks. Instead of simply following the Shannon capacity or the accumulated mutual information model, we in particular consider the finite blocklength (low latency) impart on the system performance.

Selected results

Invited and award-winning conference papers:

Journal publication/submissions:


Yulin Hu, Anke Schmeink.

© ISEK at RWTH Aachen