Hybrid NOMA/OMA Broadcasting-and-Buffer-State-Based Relay Selection

Abstract

In this paper, we propose a novel buffer-aided relay selection scheme that is capable of amalgamating the concepts of non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) in the context of two-hop cooperative networks supporting multiple relays. This is enabled by allowing relay nodes to share a common information packet in their buffers with the aid of a source-to-relay broadcasting mode. Hence, the proposed relay selection scheme switches between diverse modes of uplink NOMA, downlink NOMA, unicast, source broadcasting, and cooperative beamforming. The theoretical bounds of the outage probability, throughput, average delay, and diversity order are derived for the proposed scheme, based on a Markov chain model. Through our analytical and numerical results, it is demonstrated that the proposed scheme is capable of switching to one of the best modes in an adaptive manner while outperforming the conventional buffer-aided cooperative schemes.

Performance Analysis of Hybrid Buffer-Aided Cooperative Protocol Based on Half-Duplex and Virtual Full-Duplex Relay Selections

“…To expound a little further, it may be readily possible to include other transmission modes, such as the NOMA mode [28,29,49], the bidirectional mode [50,51], and the underlay cognitive mode [27], into our scheme. However, our focus is on the introduction of the SIC-based VFD mode with the aid of packet sharing among the relay nodes.…”

“…Cases of Θ i,j = ∅ By contrast, when any of the constraints (C1)-(C3) is not satisfied, one of the four HD modes is selected based on the priorities of the available SR and RD links corresponding to BSI. Similar to [20,26,27,29], let us introduce the target number of packets stored in the buffer of the kth relay node as ζ k . More specifically, ζ k provides the priority to the selection of RD link or SR link, depending on whether the number of packets stored at the relay nodes exceeds ζ k or not.…”

“…The performance of the ML scheme was also investigated for a multi-hop wireless network in [24]. The idea of broadcast-based packet sharing is exploited in several other contexts, such as in amplify-and-forward relaying [25], physical layer security [26], cognitive radio [27], and nonorthogonal multiple access (NOMA) [28,29]. Furthermore, in [20], cooperative beamforming was incorporated into the G-ML protocol, where the outage probability is further reduced by the explicit benefit of the beamforming gain.…”

Research on Energy Efficiency of NOMA–SWIPT Cooperative Relay Network Using GS-DinkelBach Algorithm

“…Due to the adoption of the relay cooperation scheme, under the multi-relay model, the reasonable formulation of the relay selection methods can effectively improve the network performance. A novel buffer-aided relay selection scheme is proposed in [ 25 ], and the corresponding performance in different communication links and modes is analyzed. In [ 26 ], a single-source, randomly located multi-relay network is examined to compare the communication performance in direct-link and cooperative relay.…”

Hybrid Buffer-Aided Relay Selection Based on Half-Duplex and Virtual Full-Duplex Transmission

“…This increases the degree of freedom, which provide a better performance in term of an outage probability and an average end-to-end packet delay than the conventional MMRS, ML, and BSB counterparts. Furthermore, in [11] and [12], the cooperative beamforming and non-orthogonal multiple access (NOMA) techniques were incorporated into the G-ML protocol, where the average delay and the average throughput are further reduced, respectively.…”