Abstract
Non-orthogonal multiple access (NOMA) is expected as a promising technology for satisfying massive connectivity requirements in Internet of Things (IoT). Besides, short-packet communications are a notable characteristic in IoT for low delay transmissions or massive machine-type communications (MTC). The co-channel interference from NOMA and packet error caused by finite packet will reduce system performance. In view of this, this article adopts automatic repeat request (ARQ) to assist short-packet communications for NOMA networks where a near user (NU) and a far user (FU) are paired to share the same non-orthogonal communication resources. The closed-form expressions for average packet error rate (APER) and effective throughput (ET) of both NU and FU are derived over Nakagami-$m$ channels. For gaining an insight into system performance, the performance of the scheme without ARQ is also studied. Results show that ARQ improves APER for both NU and FU, and an optimal power allocation factor or packet length exists for achieving higher ET.
Highlights
Internet of Things (IoT) provides an envision that everything in this world is connected to a unified network
Cao et al.: automatic repeat request (ARQ) Assisted Short-Packet Communications for Non-orthogonal multiple access (NOMA) Networks Over Nakagami-m Fading Channels constraints, where the transmit rates and power allocation factors are optimized; the results show that NOMA can achieve higher effective throughput (ET) than orthogonal multiple access (OMA) with the same packet length or lower delay with the same ET
The average packet error rate (APER) of the cell-edge user is derived and the results show that the cooperative NOMA scheme achieves lower APER than the traditional NOMA scheme and cooperative OMA scheme
Summary
Internet of Things (IoT) provides an envision that everything in this world is connected to a unified network. F. Cao et al.: ARQ Assisted Short-Packet Communications for NOMA Networks Over Nakagami-m Fading Channels constraints, where the transmit rates and power allocation factors are optimized; the results show that NOMA can achieve higher effective throughput (ET) than orthogonal multiple access (OMA) with the same packet length or lower delay with the same ET. In our previous work [26], ARQ is adopted to short-packet communications in cooperative networks for improving reliable transmission performance. We employ ARQ to improve the performance of short-packet communications in NOMA networks. Different from [22] where relay system is considered and infinite packet length is assumed, we focus on recruiting ARQ to improve transmission reliability and efficiency of short-packet communications for NOMA networks.
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