Abstract
In this paper, the problem of joint subcarrier assignment and global energy-efficient power allocation (J-SA-GEE-PA) for energy-harvesting (EH) two-tier downlink non-orthogonal multiple-access (NOMA) heterogeneous networks (HetNets) is considered. Particularly, the HetNet consists of a macro base-station (MBS) and a number of small base-stations (SBSs), which are solely powered via renewable-energy sources. The aim is to solve the J-SA-GEE-PA maximization problem subject to quality-of-service (QoS) per user as well as other practical constraints. However, the formulated J-SA-GEE-PA problem happens to be non-convex and NP-hard, and thus is computationally-prohibitive. In turn, problem J-SA-GEE-PA is split into two sub-problems: (1) subcarrier assignment via many-to-many matching, and (2) GEE-maximizing power allocation. In the first sub-problem, the subcarriers are assigned to users via the Gale-Shapley deferred acceptance mechanism. As for the second sub-problem, the GEE-PA problem is solved optimally via a low-complexity algorithm. After that, a two-stage solution procedure is devised to efficiently solve the J-SA-GEE-PA problem, while ensuring stability. Simulation results are presented to validate the proposed solution procedure, where it is shown to efficiently yield comparable network global energy-efficiency to the J-SA-GEE-PA scheme, and superior to that of OFDMA; however, with lower computational-complexity. The algorithmic designs presented in this work constitute a step towards filling the gap for computationally-efficient and effective resource allocation solutions to guarantee a fully autonomous and grid-independent operation of EH two-tier downlink NOMA HetNets.
Highlights
The ever increasing demand for massive connectivity, spectral- and energy-efficiency, low latency, andThe associate editor coordinating the review of this manuscript and approving it for publication was Wei Wang .higher throughput—while meeting quality-of-service (QoS) requirements for cellular users—have become motivating factors for designing effective resource allocation solutions for fifth-generation (5G) cellular networks and beyond
The heterogeneous networks (HetNets) consists of a macro base-station (MBS) and a number of small base-stations (SBSs), which are solely powered via renewable-energy sources
Consider a two-tier downlink HetNet consisting of a macro base-station (MBS) and M small base-stations (SBSs), where the downlink transmission is achieved via non-orthogonal multiple-access (NOMA)
Summary
The ever increasing demand for massive connectivity, spectral- and energy-efficiency, low latency, and. To the best of the authors’ knowledge, no prior work has considered joint subcarrier assignment and global energy-efficient power allocation for EH two-tier downlink NOMA HetNets, and provided a computationally-efficient two-stage solution procedure. Devised a two-stage solution procedure to solve the J-SA-GEE-PA problem, which solves the subcarrier assignment and GEE-maximizing power allocation problem in the MBS- and SBS-tiers, while guaranteeing two-sided exchange-stability via a polynomial-time complexity swap matching algorithm. The energyefficient resource allocation is decoupled into two problems, one for small-cells, and the other for the macro-cell; whereas in our work, the subcarrier assignment is decoupled from the global energy-efficient power allocation, and are performed over two stages in the MBS- and SBS-tiers.
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