Hybrid User Pairing for Spectral and Energy Efficiencies in Multiuser MISO-NOMA Networks With SWIPT

Abstract

In this paper, we propose a novel hybrid user pairing (HUP) scheme in multiuser multiple-input single-output nonorthogonal multiple access networks with simultaneous wireless information and power transfer. In this system, two information users with distinct channel conditions are optimally paired while energy users perform energy harvesting (EH) under non-linearity of the EH circuits. We consider the problem of jointly optimizing user pairing and power allocation to maximize the overall spectral efficiency (SE) and energy efficiency (EE) subject to userspecific quality-of-service and harvested power requirements. A new paradigm for the EE-EH trade-off is then proposed to achieve a good balance of network power consumption. Such design problems are formulated as the maximization of nonconcave functions subject to the class of mixed-integer non-convex constraints, which are very challenging to solve optimally. To address these challenges, we first relax binary pairing variables to be continuous and transform the design problems into equivalent non-convex ones, but with more tractable forms. We then develop low-complexity iterative algorithms to improve the objectives and converge to a local optimum by means of the inner approximation framework. Simulation results show the convergence of proposed algorithms and the SE and EE improvements of the proposed HUP scheme over state-of-the-art designs. In addition, the effects of key parameters such as the number of antennas and dynamic power at the BS, target data rates, and energy threshold, on the system performance are evaluated to show the effectiveness of the proposed schemes in balancing resource utilization.

Multi-User Angle-Domain MIMO-NOMA System for mmWave Communications

“…As seen in (13b), R depends on the PA coefficients γ = {γ l,c , c ∈ C n , l ∈ K c } and on the UEs' channel qualities ζ = {ζ l,c , c ∈ C, l ∈ K c } built using FCSI h l,c as shown in (7). Therefore, R can be improved by carefully designing a user clustering (UC) algorithm and a power allocation (PA) technique, including inter-cluster PA p = {p c , c ∈ C} and intra-cluster PA γ strategies.…”

“…(14) includes the gain α 1,l,c and the spatial angle θ 1,l,c of the LoS path. By substituting ( 14) in (7), we obtain the following channel qualityζ l,c of UE l,c…”

Joint user pairing and power allocation scheme based on transmission mode switching between NOMA based maximum ratio transmission and MMSE beamforming in downlink MISO systems

“…(16) and (17) can be combined into one equation. We substitute (22) into (16) and (17), and then (24) and (25) into (16) and (17), respectively. Subsequently, by combining (16) and 17, we can obtain (11).…”

“…Dynamic user clustering and user pairing are effective methods to achieve the viable benefits of NOMA in providing high spectral efficiency [15][16][17]. In [15], the impact of user pairing on the performance of the twouser NOMA systems, is characterized.…”

“…To be spectrally-efficient, the tensor model was introduced to optimize uplink users' decoding order and downlink users' clustering. In [17], a novel hybrid user pairing beamforming (HUP) scheme was proposed to maximize the achievable spectral and energy efficiencies for Multiuser MISO-NOMA downlink systems with simultaneous wireless information and power transfer (SWIPT). In the proposed HUP scheme, two information users with distinct channel conditions are paired while energy users located nearby the BS perform energy harvesting.…”