Jointly Optimized Beamforming and Power Allocation for Full-Duplex Cell-Free NOMA in Space-Ground Integrated Networks

Abstract

Space-ground integrated networks (SGINs) have attracted substantial research interests due to their wide area coverage capability, where spectrum sharing is employed between the satellite and terrestrial networks for improving the spectral efficiency (SE). We further improve the SE by conceiving a cellfree system in SGINs, where the full-duplex (FD) multi-antenna APs simultaneously provide downlink and uplink services at the same time and within the same frequency band. Furthermore, power domain (PD) non-orthogonal multiple access (NOMA) is employed as the multiple access (MA) technique in the cell-free system. To achieve a performance enhancement, the sum-rate maximization problem is formulated for jointly optimizing the power allocation factors (PAFs) of the NOMA downlink (DL), the uplink transmit power, and both the beamformer of the satellite and of the APs. Successive convex approximation (SCA) and semi-definite programming (SDP) are adopted to transform the resultant non-convex problem into an equivalent convex one. Our simulation results reveal that 1) our proposed system outperforms the well-known approaches (i.e., frequency division duplex (FDD) and small cell systems) in terms of its SE; 2) our proposed optimization algorithm significantly improves the networking performance; 3) the conceived SIC order design outperforms the fixed-order design at the same complexity.

Design of Delay-Optimal Robust Edge Computing in 6G Wireless Networks

“…which represents that the signal of the k ′ -th GUE at the m-th BS is decoded and eliminated from the received signal before the k ′′ -th GUE [30]. Based on the principle of SIC that the GUE signal with a high channel quality is decoded first, the data transmission rate from the k-th GUE to the m-th BS is given by…”

Leveraging Common User Clustering for Improved Performance in Cell-Free NOMA Networks

“…This has resulted in the attainment of higher data rates and increased coverage for a greater number of UEs [6][7][8][9][10][11]. These investigations have focused on various aspects such as AP selection strategies [7] and power allocation [8], as well as studying the SE maximization [9] in cell-free NOMA networks. In cell-free NOMA networks, UEs are categorized into separate clusters, where the signals transmitted within each cluster are generally designed to be orthogonal to those in other clusters.…”

“…Notably, the Max-min rate and sum rate are considered the most crucial criteria. The solution to power allocation in cell-free NOMA networks, employing the Max-min rate criteria, has been addressed in [11], [19], while the approach based on sum rate criteria has been resolved in [20], [21]. In [19], A closed-form SINR expression is derived under Rayleigh fading and used to formulate a max-min quality-of-service power control problem.…”

“…In recent years, extensive research has been carried out on the advantages presented by the integration of both cell-free and NOMA technologies. This has resulted in the attainment of higher data rates and increased coverage for a greater number of UEs [6][7][8][9][10][11]. These investigations have focused on various aspects such as AP selection strategies [7] and power allocation [8], as well as studying the SE maximization [9] in cell-free NOMA networks.…”

“…The issue of power allocation in cell-free NOMA networks is an important issue that highly affects the performance of the network. This has been extensively discussed in the literature [19], [20], [21]. The optimal solution of power allocation can be achieved through various criteria.…”