LoLA4SOR: A Low-Latency Algorithm for Successive Opportunistic Relaying

Buffer-aided (BA) relaying has been proposed as an efficient way to improve the diversity of multi-hop networks. Nonetheless, it results in increased end-to-end delay, as packets tend to reside in the relays' buffers for many time-slots. In order to enable the adoption of BA relays in delay-intolerant applications, the combination with successive relaying can increase the number of packets that are transmitted. In this work, hybrid relay selection algorithms are studied, where delay- and diversity aware (DDA) half-duplex algorithms are complemented with successive BA relaying. Moreover, a hybrid DDA algorithm is presented, namely LoLA4SOR that adapts to the transmit conditions, switching between half-duplex (HD) and successive relaying (SuR). The performance of LoLA4SOR is compared to several HD, successive and hybrid algorithms, in terms of outage probability, throughput and delay. The results indicate that LoLA4SOR provides superior outage and throughput performance, while its delay performance is not affected by the buffer size and, as the number of relays increase, its delay reduces due to the high probability for successive transmissions.