Abstract
Non-orthogonal multiple access (NOMA) has been widely recognized as a promising way to scale up the number of users, enhance the spectral efficiency, and improve the user fairness in wireless networks, by allowing more than one user to share one wireless resource. NOMA can be flexibly combined with many existing wireless technologies and emerging ones including multiple-input multiple-output (MIMO), massive MIMO, millimeter wave communications, cognitive and cooperative communications, visible light communications, physical layer security, energy harvesting, wireless caching, and so on. Combination of NOMA with these technologies can further increase scalability, spectral efficiency, energy efficiency, and greenness of future communication networks. This paper provides a comprehensive survey of the interplay between NOMA and the above technologies. The emphasis is on how the above techniques can benefit from NOMA and vice versa. Moreover, challenges and future research directions are identified.
Highlights
M ULTIPLE access techniques allow multiple users to share the same communication resource and are Manuscript received March 24, 2019; revised June 27, 2019; accepted July 30, 2019
Research Directions: In the related prior research on Non-orthogonal multiple access (NOMA)-enabled massive multiple-input multiple-output (MIMO) [17], [35]–[47], [49]–[52], [61], [63]–[66], [68], [69], the spatial domain has solely been exploited in designing pilot allocations, user groupings/pairings, and related signal processing techniques
Deep learning techniques by virtue of artificial neural networks can be a useful tool in enhancing the efficiency of data/model-driven transmitter/receiver designs for NOMAaided massive MIMO
Summary
M ULTIPLE access techniques allow multiple users to share the same communication resource and are Manuscript received March 24, 2019; revised June 27, 2019; accepted July 30, 2019. By allowing multiple users to simultaneously access the same wireless resources, NOMA offers a promising solution to the need for massive connectivity in 5G and beyond. This term was coined by Saito et al [2], where the authors showed that simultaneous transmission of users’ signal can improve system throughput and user-fairness over a singleinput single-output (SISO) channel when using orthogonal frequency-division multiple access (OFDMA). NOMA is actively being investigated by academia, standardization bodies, and industry [11] This owes, partly, to the advances in processing power which make interference cancellation at user equipment viable. While recent advances in processor capabilities have made SIC, and NOMA, feasible, significant research challenges remain to be addressed before NOMA can be deployed commercially
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