Study on transmission over Nakagami-m fading channel for multiple access scheme without orthogonal signal

In this paper, a downlink performance in non-orthogonal multiple access (NOMA) system is considered. With regard to different priority for two NOMA users, we exploit the closed-form expressions of outage probability over wireless fading channel following Nakagami-m fading. The fixed power allocation factor scheme is examined to reduce the complexity in computation regarding performance analysis. In our analysis, perfect successive interference cancellation (SIC) is applied in order to achieve perfect signal decoding operation. Simulation results show that the considered NOMA downlink scheme is affected by transmit SNR, power allocation factors, fading parameters

A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond

Today's wireless networks allocate radio resources to users based on the orthogonal multiple access (OMA) principle. However, as the number of users increases, OMA based approaches may not meet the stringent emerging requirements including very high spectral efficiency, very low latency, and massive device connectivity. Nonorthogonal multiple access (NOMA) principle emerges as a solution to improve the spectral efficiency while allowing some degree of multiple access interference at receivers. In this tutorial style paper, we target providing a unified model for NOMA, including uplink and downlink transmissions, along with the extensions tomultiple inputmultiple output and cooperative communication scenarios. Through numerical examples, we compare the performances of OMA and NOMA networks. Implementation aspects and open issues are also detailed.Comment: 25 pages, 10 figure

Improving performance of far users in cognitive radio: Exploiting NOMA and wireless power transfer

In this paper, we examine non-orthogonal multiple access (NOMA) and relay selection strategy to benefit extra advantage from traditional cognitive radio (CR) relaying systems. The most important requirement to prolong lifetime of such network is employing energy harvesting in the relay to address network with limited power constraint. In particular, we study such energy harvesting CR-NOMA using amplify-and-forward (AF) scheme to improve performance far NOMA users. To further address such problem, two schemes are investigated in term of number of selected relays. To further examine system performance, the outage performance needs to be studied for such wireless powered CR-NOMA network over Rayleigh channels. The accurate expressions for the outage probability are derived to perform outage comparison of primary network and secondary network. The analytical results show clearly that position of these nodes, transmit signal to noise ratio (SNR) and power allocation coefficients result in varying outage performance. As main observation, performance gap between primary and secondary destination is decided by both power allocation factors and selection mode of single relay or multiple relays. Numerical studies were conducted to verify our derivations.Web of Science1211art. no. 220

Efficient Transmission in Multi-user Relay Networks with Node Clustering and Network Coding

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordThis paper investigates the communication problem in a class of multi-user dual-hop networks in which multiple source terminals desire to distribute their independent messages to multiple destinations through the assistance of multiple relay terminals. We consider an efficient transmission strategy that combines network coding and non-orthogonal transmission techniques to balance the achievability of spatial diversity and channel utilization. Specifically, in addition to applying a class of finite-field network codes in the relays, we divide the sources and the relays into clusters such that terminals within each cluster can access the same channel resource. The achievable error performance under Nakagami-m fading environment is derived and is shown to significantly outperform the conventional transmission methods.National Natural Science Foundation of ChinaEuropean Union Horizon 202

Outage Performance of Generalized Cooperative NOMA Systems with SWIPT in Nakagami-m Fading

This paper investigates cooperative non-orthogonal multiple access (NOMA) with simultaneous wireless informationand power transfer (SWIPT) radio networks. A decode-andforward relay deserves a base station to transmit informationto two users. Two access schemes are addressed: direct andrelay assisted transmission (DRAT) where a line-of-sight existsbetween the source and destination, and non-direct and relayassisted transmission (nDRAT) where the only access to the finalusers is through the relay. New closed-form expressions of outageprobability are derived at these schemes. A generalization usingNakagami-m fading channels in considered, in order to present acomplete cover of relayed NOMA systems with energy harvestingbehavior in small scale fading.We consider the impact of time splitting fraction, power allocation and channel parameters on system maintainability andevaluate its maximum data rate transmission with full autonomy.By comparing the two schemes, cooperative NOMA with energyharvesting (EH) in nDRAT scenario outperforms transmissionwith direct link in terms of outage probability and transmissiondata rate