LoLa4SOR: Leveraging Successive Transmissions for Low-Latency Buffer-Aided Opportunistic Relay Networks

Abstract

Buffer-aided (BA) relaying improves the diversity of cooperative networks often at the cost of increasing end-to-end packet delays. This characteristic renders BA relaying unsuitable for delay-sensitive applications. However, the increased diversity makes BA relaying appealing for ultra-reliable communications. Towards enabling ultra-reliable low-latency communication (URLLC), we aim at enhancing BA relaying for supporting delay-sensitive applications. In this paper, reliable full-duplex (FD) network operation is targeted and for this purpose, hybrid relay selection algorithms are formulated, combining BA successive relaying (SuR) and delay-and diversity-aware (DDA) half-duplex (HD) algorithms. In this context, a hybrid FD DDA algorithm is presented, namely LoLa4SOR, switching between SuR and HD operation. Additionally, a low-complexity distributed version is given, namely d-LoLa4SOR, providing a trade-off among channel state information requirements and performance. The theoretical analysis shows that the diversity of LoLa4SOR equals to two times the number of available relays K, i.e. 2K, when the buffer size L is greater than or equal to 3. Comparisons with other HD, SuR and hybrid algorithms reveal that LoLa4SOR offers superior outage and throughput performance while, the average delay is reduced due to SuR-based FD operation and the consideration of buffer state information for relay-pair selection. d-LoLa4SOR, as one of the few distributed algorithms in the literature, has a reasonable performance that makes it a more practical approach.

Throughput Maximization for Wireless Powered Buffer-Aided Successive Relaying Networks

“…Figure 6 presents the data buffer lengths of the relay R 2 and the total data buffer length of both relays with different V, in which λ 2 is set to 0:6,1:0,1:4, respectively. A larger λ 2 results in the smaller data buffer lengths, which is consistent with the performance analysis in Section 5.3, and the average data buffer length tends to be linearly proportional to V, which complies with the analysis in (49). In addition, the maximal data buffer length at the relay R 2 is just a litter larger than the parameter V/λ 2 , which indicates that the instantaneous data buffer length is always bounded, which complies with Lemma 9.…”

“…Full-duplex relaying (FDR) [33][34][35][36][37] and successive relaying (SR) [38][39][40][41][42][43][44][45][46][47][48][49][50][51] are two representative techniques to further improve the spectral efficiency. Since sophisticated fullduplex circuits and self-interference suppression technology are no longer needed, SR provides us with an effective solution that simultaneously selects two relays to receive information from the source and forward the message to the destination, such that it can be interpreted as a virtual FDR.…”

“…The aforementioned research works aim to either analyze or optimize the achieved performance and do not attempt to exploit the great benefit of the bufferaided communication strategy. For a buffer-aided successive relaying network, the transmission policy design and resource scheduling were studied in [44][45][46][47][48][49] without energy harvesting. In [50], the relays of an EH-based SR network were provisioned with data buffers and energy storages, and the network throughput was maximized in the absence of inter-relay-interference (IRI).…”

“…Nonetheless, the data buffer at the relay was not exploited. In [44][45][46][47][48][49], the achieved performance and resource management for a buffer-aided SR network were investigated without considering energy harvesting capability. Under the complete interference cancellation assumption, the throughput maximization problem of an EH-based SR network without inter-relay-interference (IRI) was studied in [50] by considering both the data buffer and energy storage at relay.…”

Secrecy Performance of Buffer-Aided Hybrid Virtual Full-Duplex and Half-Duplex Relay Activation

“…Furthermore, interference between transmitting and receiving relay nodes, referred to as inter-relay interference (IRI), is eliminated with the aid of multiple antennas equipped at the relay nodes [50,51]. In [52], Nomikos et al proposed the reduced-latency successive opportunistic relaying algorithm in the presence of strong IRI, where the HD transmission is activated for transmission. Furthermore, In [53], Lin et al proposed the hybrid VFD and HD transmissions for multidata streaming, where multi-antenna are quipped with both source and destination nodes, and each relay node is equipped with a single antenna.…”