Relaying with finite blocklength: Challenge vs. opportunity

On the performance of ultra-reliable decode and forward relaying under the finite blocklength

“…In this scenario, S sends the message to D and R in the broadcasting phase by employing n S channel uses. Afterwards, if R decodes the data packet accurately, the message transfers to D in the relaying phase through n R channel uses [2], [17]. In the broadcasting phase, the received signals at D and R are y 1 " h 1 x `w1 and y 2 " h 2 x `w2 respectively.…”

“…In the broadcasting phase, the received signals at D and R are y 1 " h 1 x`w 1 and y 2 " h 2 x`w 2 respectively. If R successfully collaborates with S, the received signal at D is y 3 " h 3 x`w 3 , where the transmitted signal is x and the AWGN noise vector with power N 0 " 1 is denoted by w i , where i P tX, Y, Zu [2], [17]. In a DF-based relaying protocol, the instantaneous SNR depends on the total power constraint P " P S`PR " ηP`p1´ηqP , which is given by Z " ηP |h 1 | 2 {N 0 , X " ηP |h 2 | 2 {N 0 and Y " p1´ηqP |h 3 | 2 {N 0 for the direct link, broadcasting link and relaying link respectively, where 0 ă η ď 1 is the power allocation factor.…”

Performance analysis of ultra-reliable short message decode and forward relaying protocols

“…They indicate that the performance loss increases if the outage probability of the source-to-relay link is higher than the overall outage probability. The efficiency of multi-relay DF scenario under the assumption of perfect channel-state-information (CSI) and partial CSI is provided in [28]. Authors show that with perfect CSI, the throughput of IFB is smaller than the throughput with FB coding.…”

Ultra-reliable short message cooperative relaying protocols under Nakagami-m fading

“…Authors in [16] propose cooperative relaying as a way to meet the high reliability and latency requirements. In [17], authors examine the performance of a multi-relay DF protocol with FB under the perfect CSI and partial CSI. They indicate that with perfect CSI, the throughput of FB coding is higher than the throughput of IFB coding.…”

“…In this scenario, first S sends data to D and R which is known as broadcasting phase. Thereafter, in the relaying phase, R forwards to D only if it decoded the message correctly [15], [17]. The received signals are written as y 1 " h 1 x `w1 and y 2 " h 2 x `w2 at D and R respectively, and if R participates, the received signal at D is y 3 " h 3 x `w3 , where x is the transmitted signal with power P and w i is the AWGN noise vector with power N 0 " 1 where i P tX, Y, Zu.…”