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.
Highlights
N ON-ORTHOGONAL multiple access (NOMA) [1]–[5] enables flexible resource allocation in comparison to the conventional orthogonal multiple access (OMA) counterpart
We assumed that the buffers of all nodes are initially empty and a sufficient number of packets are transmitted to attain the steady state in each Monte Carlo simulation, as verified in [27]
We proposed novel NOMA/OMA-hybrid multimode buffer-state-based cooperative schemes
Summary
N ON-ORTHOGONAL multiple access (NOMA) [1]–[5] enables flexible resource allocation in comparison to the conventional orthogonal multiple access (OMA) counterpart. In [25]–[30], broadcasting an information packet from a source node to multiple relay nodes was introduced in the context of the aforementioned buffer-aided cooperative communications; this allows relay nodes to share a common information packet, increasing the degree of freedom in buffer states. KOCHI et al.: HYBRID NOMA/OMA BROADCASTING-AND-BUFFER-STATE-BASED RELAY SELECTION outperforming the conventional buffer-aided cooperative schemes. Communication delay was kept at the minimum while achieving the high reliability of buffer-aided relay selection Such broadcasting- and buffer-state-based (BBSB) relay selection schemes were developed in the context of decode-and-forward (DF) [25] and amplify-and-forward (AF) relaying scenarios [26]. While in [29], the DL-NOMA concept was incorporated into the relaying phase of the buffer-aided relay selection for the multi-user downlink, cooperative beamforing and the NOMA mode in the source transmission phase were not exploited. Through our analytical and numerical performance results, it is demonstrated that the proposed scheme is capable of successfully switching to one of the best modes in an adaptive manner,
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