Relay Selection and Power Allocation for Energy Efficiency Maximization in Hybrid Satellite-UAV Networks With CoMP-NOMA Transmission

Abstract

Non-orthogonal multiple access (NOMA) and coordinated multi-point (CoMP) are two fundamental techniques considered for the fifth generation (5G) of wireless communications. In this paper, a hybrid satellite-unmanned aerial vehicle (UAV) relay network (HSURN) is proposed where the UAV relays (URs) employ CoMP transmission to serve the terrestrial users (UEs). Furthermore, all UEs associated with the CoMP-URs form a single NOMA cluster. For this model, an optimization problem is formulated subject to the minimum quality of services (QoSs) requirements of the UEs, transmission power budgets and, successive interference cancellation (SIC), to select URs and allocate their transmission powers for the energy efficiency (EE) maximization. With this insight, first, a computationally efficient sub-optimal UR selection scheme is proposed. Then, the powers are allocated to the selected URs via the Lagrange multipliers optimization (LMO) method. Due to the non-convex nature of the considered problem, it is relatively difficult to be solved. Hence, a metaheuristic teaching-learning-based optimization (TLBO) algorithm is employed to achieve an efficient solution. Simulation results are provided to verify the effectiveness of the proposed sub-optimal relay selection scheme and the TLBO-based power allocation method compared to the LMO conventional method. Besides, the obtained results also reveal that the CoMP-NOMA transmission in the proposed scenario significantly improves the spectral efficiency (SE) and outage probability (OP) of the system compared to non-comp NOMA transmission case.Index Terms-Non-orthogonal multiple access (NOMA), Coordinated multi-point (CoMP) transmission, energy efficiency (EE), UAV relay selection, satellite terrestrial network, outage probability (OP). I. INTRODUCTIONThe 5G-satellite networks in the integrated architecture have emerged as a valuable infrastructure to meet the future radio access of smart devices. Combining satellite components into wireless systems is not only an indispensable way to provide seamless coverage and large capacity for users all over the world but also to ensure high QoS expectations [1]. Mobile satellite networks have been viewed as a promising technique for the smart grid, internet-of-thing (IoT), wireless sensor

Trajectory Optimization and Power Allocation for Cell-Free Satellite-UAV Internet of Things

“…The authors in [25] propose an iterative algorithm based on the variable substitution, successive convex optimization techniques, and the block coordinate decent algorithm to solve the nonconvex optimization problem. Reference [26] proposes a hybrid satelliteunmanned aerial vehicle relay network where the UAVs act as the relay from the satellite to the terrestrial users. In [26], the joint resource allocation in terms of the relay selection and power allocation is considered and then a metaheuristic teaching-learning based optimization algorithm is employed to optimize the problem.…”

Optimal power allocation for non‐orthogonal multiple access enabled full‐duplex underlay cognitive relay networks under partial relay selection

“…In the literature, several authors have investigated the performance of FD cooperative NOMA systems. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] In Reference 28, the authors have studied the outage probability and ergodic rate performance of downlink users in cooperative NOMA systems, where the near user is configured as FD relay to improve the reliability of the far user, while the authors of Reference 29 have studied the outage probability and ergodic rate performance of downlink users in cooperative NOMA systems, where a dedicated FD relay node is used to improve the reliability of the downlink users. In Reference 30, the authors have studied the outage probability and outage sum capacity of a cooperative NOMA system, where two source-destination pairs share a dedicated FD relay, while the authors of Reference 31 have considered the application of uplink NOMA in a cooperative relay system.…”

“…Recently, many researchers have investigated the performance of multiple HD/FD relay-aided cooperative NOMA system with appropriate relay selection methods. [43][44][45][46][47][48] In Reference 43, the authors have considered a hybrid satellite-unmanned aerial vehicle (UAV) relay network (HSURN), where the UAV relays (URs) employ coordinated multi-point (CoMP)-NOMA transmission to serve the terrestrial users (UEs). A suboptimal UR selection policy and an OPA policy were formulated in order to maximize the energy efficiency.…”

“…In the literature, several authors have investigated the performance of FD cooperative NOMA systems 28‐47 . In Reference 28, the authors have studied the outage probability and ergodic rate performance of downlink users in cooperative NOMA systems, where the near user is configured as FD relay to improve the reliability of the far user, while the authors of Reference 29 have studied the outage probability and ergodic rate performance of downlink users in cooperative NOMA systems, where a dedicated FD relay node is used to improve the reliability of the downlink users.…”

“…The results reported in Reference 44‐48 have shown that, compared to fixed relaying, the use of multiple relays for cooperation can lead to performance enhancement, as it provides additional degrees of freedom for cooperation. However, the main drawbacks of the above research papers 28‐48 is that, all of them consider the conventional cooperative NOMA system (ie, a non‐cognitive scenario) while the focus of the present work is on NOMA enabled FD cognitive relay networks.…”