Outage analysis of underlay cognitive NOMA system with cooperative full duplex relaying

Abstract

This paper investigates the outage performance of secondary users (SUs) in underlay cognitive radio-based nonorthogonal multiple access (CR-NOMA) networks. We consider down link scenario for the secondary network, which consists of a secondary transmitter (ST) and two SUs, ie, a near user and far user. The ST uses NOMA signaling to transfer the information to the down link SUs. A dedicated node is used as the full-duplex decode-and-forward (DF) relay for delivering the message to the far-user. We derive exact expressions for the outage probabilities experienced by the SUs for full duplex (FD)/half duplex (HD)-based CR-NOMA networks, in independent, nonidentically distributed Rayleigh fading channels. The maximum transmit power constraint of the secondary nodes and the tolerable interference power constraint at the primary receiver are considered for the analysis. We compare the performance of the proposed FD/HD-based CR-NOMA networks against that of a CR network, which use conventional orthogonal multiple access (OMA) scheme. We establish that the performance of CR-NOMA network is better as compared to CR-OMA networks. We then consider finding the optimal location for the FD relay node that minimizes the outage probability of far-user. We formulate an optimization problem that is solved using genetic algorithm. Numerical results show that optimized relay location significantly improves the outage performance of the far-user. The analytical results are validated by extensive simulation studies.Trans Emerging Tel Tech. 2019;30:e3701.wileyonlinelibrary.com/journal/ett

Performance analysis of cooperative nonorthogonal multiple access with improved time switching simultaneous wireless information and power transfer protocol

“…According to the theory of DL NOMA, S transmits a superimposed composite signal towards UE 1 and UE 2 during phase‐1 simultaneously, where ( p 1 , p 2 ) and ( x 2 , x 3 ) are the power allocation factors and the data symbols, respectively 18,26,28,29 . It is noted that ( x 2 , p 1 ) and ( x 3 , p 2 ) are assigned to UE 1 and UE 2 , respectively.…”

“…Proof According to the concept of DL NOMA, the user with good channel condition ( UE 1 because d S ,1 < d S ,2 ) performs SIC to decode the symbol with highest power ( x 3 ) and then it is subtract from the received signal () to decode x 2 . UE 1 received the superimposed signal during t 1 through h S ,1 channel 11,26,28,29 . The outage event of UE 1 during t 1 can be occur whenever UE 1 is unable to decode either x 3 or x 2 (or both) 11,26,28,29 .…”

“… UE 1 received the superimposed signal during t 1 through h S ,1 channel 11,26,28,29 . The outage event of UE 1 during t 1 can be occur whenever UE 1 is unable to decode either x 3 or x 2 (or both) 11,26,28,29 . If such a situation take place, UE 1 cannot successfully performs SIC, hence UE 1 is in outage.…”

“…In addition, optimal power allocation for capacity maximization technique is also proposed in Reference 27 for DL NOMA. Furthermore, adaptive NOMA and NOMA with cooperative full‐duplex relaying were proposed in recent researches to enhance the channel capacity and reduce the OP of the users, respectively 28,29 . However, CNOMA‐SWIPT was not considered in References 27‐29.…”

“…Furthermore, adaptive NOMA and NOMA with cooperative full‐duplex relaying were proposed in recent researches to enhance the channel capacity and reduce the OP of the users, respectively 28,29 . However, CNOMA‐SWIPT was not considered in References 27‐29. Moreover, the energy efficiency improvement and secrecy analysis were performed for the CNOMA‐SWIPT network in References 30,31.…”