Cooperative non-orthogonal multiple access with physical layer network coding

Physical layer network coding (PNC) has been proposed for information exchange between a pair of users assisted by a relay. However, the spectral efficiency of PNC reduces when the number of user pairs increases due to the requirement of orthogonal channels for multi-pair operation. This paper proposes the use of cooperative non-orthogonal multiple access (NOMA) and PNC to improve the spectral efficiency and outage performance of multi-pair information exchange. Specifically, a cognitive radio inspired NOMA is considered. The quality of service of the primary user pair is guaranteed through dynamic power allocation policy, while the secondary user pair is served on best effort basis. The simulation result shows that the proposed cognitive radio inspired NOMA scheme with PNC achieves higher spectral efficiency and better outage performance if compared with the existing orthogonal multiple access schemes with PNC

Joint RSMA and IDMA-Based NOMA system for downlink Communication in 5G and Beyond Networks

Future communication networks may encounter various issues in order to facilitate heavy heterogeneous data traffic and large number of users, therefore more advanced multiple access (MA) schemes is required to meet the changing requirements. Recently, a promising physical-layer MA technique has been suggested for multi-antenna broadcast channels, namely Rate Splitting Multiple Access (RSMA). This new scheme has the ability to partially decode the interference and partially treat the remaining interference as noise which makes it to cope with wide range of user deployments and network loads. On the other hand, interleave division multiple access (IDMA) has already been recognized as a potential code domain NOMA (non-orthogonal multiple access) scheme, suitable for 5G and beyond communication network. Hence, in this paper, a new approach of multiple access scheme is proposed to get the grip on new challenges in future communication (6G). The proposed framework consists the joint processing of RSMA and IDMA (code domain NOMA), in which the transmitter involves an IDMA as encoder and allows rate splitting to split the message in two parts i.e. common part and private part, before the actual transmission. The mathematical modeling of proposed system is elaborated in the paper and for simulation purpose the downlink communication scenario has been considered where users faced diverse channel conditions. The weighted sum rate (WSR) performance is evaluated for the proposed scheme which validate the quality of service (QoS) of the joint RS-IDMA system

Backscatter Assisted NOMA-PLNC Based Wireless Networks

In this paper, sum capacity maximization of the non-orthogonal multiple access (NOMA)-based wireless network is studied in the presence of ambient backscattering (ABS). Assuming that ABS is located next to far nodes, it improves the signal strength of far node cluster. By applying suitable successive interference cancellation (SIC) operation, far node cluster act as an internet of things (IoT) reader. Moreover, to improve the uplink performance of the nodes, a physical layer network coding (PLNC) scheme is applied in the proposed network. Power optimization is employed at the access point (AP) to enhance the downlink performance with total transmit power constraint and minimum data rate requirement per user constraint using Lagrangian’s function. In addition, end-to-end outage performance of the proposed wireless network is analyzed to enhance each wireless link capacity. Numerical results evident that the outage performance of the proposed network is significantly improved while using the ABS. Furthermore, the average bit error rate (BER) performance of the proposed wireless network is studied to improve the reliability. Simulation results are presented to validate the analytical expressions