About this Research Topic
Driven by the rapid growth of mobile network and Internet of Things (IoT), future wireless networks anticipate an explosive demand for massive connectivity over limited radio resources. To this end, a number of energy and spectrally efficient technologies have been proposed, including massive multiple-input multiple-output (MIMO), millimeter wave communications, ultra-dense networks, and non-orthogonal multiple access (NOMA). Among these prospective technologies, NOMA plays a crucial role for providing large system throughput, high reliability, improved coverage, and enhanced user fairness given the scarce bandwidth resources. For its promising features, NOMA has been included in the 3GPP long term evolution advanced (LTE-A) standard and highlighted in many fifth generation (5G) white papers produced by industrial and academic bodies, which further underlines its importance for future wireless networks.
Since the first generation (1G) wireless network, orthogonal multiple access (OMA), which allocates the communication resources to different users orthogonally in at least one radio resource dimension, e.g., frequency, time, code, etc., has been widely deployed. Despite its effectiveness to mitigate multiple access interference, the number of active users allowed access to the OMA system is strictly limited by the number of available orthogonal resources, which becomes less useful for supporting massive connectivity and achieving user fairness. In contrast to OMA, NOMA simultaneously accommodates a multitude of users with the same radio resource by introducing controllable interference via non-orthogonal resource allocation at the expense of a tolerable increase in receiver complexity, supporting large number of connections and high overloading transmission. The recently emerged power-domain NOMA, sparse code multiple access (SCMA), and pattern division multiple access (PDMA) are the three popular realizations of the NOMA concept.
Considering its potential application in future wireless networks, NOMA will receive even more research interest from both academia and industry. However, there are still a number of open issues remaining to be solved before NOMA can be successfully applied in practical systems. This Research Topic aims to bring together leading researchers in both academia and industry from diversified backgrounds to unlock the potential of NOMA for future wireless networks.
The themes of interest include, but are not limited to:
● Emerging applications of NOMA in B5G, IoT, V2X, and UAV
● Cooperative NOMA systems
● Resource allocation in NOMA networks
● Energy efficiency optimization for NOMA systems
● Grant-free NOMA system design
● Cross-layer design of NOMA
● Channel coding and modulation schemes for NOMA
● Security provisioning in NOMA
● Multiple antenna techniques for NOMA
● NOMA assisted wireless caching and mobile edge computing
● Machine learning for NOMA
● NOMA in wireless powered communications
● NOMA for Terahertz communications
● Compatibility of NOMA with other 5G key technologies
● Reconfigurable intelligent surfaces for NOMA
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Keywords: NOMA, wireless networks, grant-free, spectral efficiency, massive connectivity
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