Joint Power Allocation and User Scheduling for Device-to-Device-Enabled Heterogeneous Networks With Non-Orthogonal Multiple Access

Abstract

Device-to-device (D2D) communications-enabled dense heterogeneous networks (HetNets) with non-orthogonal multiple access (NOMA) are promising solutions to meet the high-throughput requirement and support massive connectivity. In this paper, we propose a novel framework on the D2D-enabled HetNets with NOMA, where small cells underlay the uplink spectrum of macrocells to make full use of spectrum resources, NOMA technique is invoked to serve more downlink users simultaneously, and D2Denabled multi-hop transmission is established to enhance signal reception of the far users (FUs) on cell edge. We investigate joint power allocation and user scheduling to maximize the ergodic sum rate of the near users (NUs) in the small cells while guaranteeing the quality-of-service requirements of the FUs and the macro-cell users. The optimal solution to this problem is complexity-prohibitive especially with large numbers of users and small base stations (SBSs) because it requires an exhaustive search over all possible combinations of SBSs, NUs, and FUs. To simplify the solution, we develop a two-step approach by decomposing the original problem into a power allocation problem and a user scheduling problem. We derive the closed-form solution of the power allocation problem via analyzing the objective function and constraints. The user scheduling problem is a joint user pairing and access point assignment problem. To solve it, we propose an SBS-NU-FU matching algorithm to obtain a near-optimal one-to-one three-sided matching of SBSs, NUs, and FUs. The simulation results show that the two-step method gets around 95% of the system throughput of the optimal one and can significantly improve the spectral efficiency of the D2D-enabled HetNets.

Non-Orthogonal Random Access and Data Transmission Scheme for Machine-to-Machine Communications in Cellular Networks

“…Tan et al [23] investigate a dedicated millimeter-wave-based hybrid energy harvesting mechanism with NOMA transmission to increase network throughput. Liu et al [24] investigate a joint power allocation and user scheduling scheme for Device-to-Device(D2D) communications-enabled heterogeneous networks with NOMA to maximize the ergodic sum rate of small-cell near users. To analyze the performance of the NOMA scheme, the outage performance and the achievable sum data rate are theoretically analyzed [25]- [27].…”

Two policies for wireless non‐orthogonal multiple access systems: System model and performance enhancement of far user

“…The outage probability of device FU can be defined as the probability that the instantaneous data rate of FU falls below a predefined target data rate 28‐31 …”

“…In the uplink phase, the D2D group reuses the resource of the CUE. To improve signal reception of the FUs on cell‐edge area, the D2D‐enabled HetNets with NOMA was explored in Liu et al, 28 where small cells underlay the uplink spectrum of macrocells to employ full use of spectrum resources. Particularly, NOMA scheme is invoked to support more downlink users in the same time, and D2D‐enabled multihop transmission is required.…”

Performance of D2D Aided Uplink Coordinated Direct and Relay Transmission Using NOMA

“…On the one hand, for resource allocation, a proposed D2D-aided and NOMA-based mobile edge computing system has been considered and a joint power, computing resource and channel assignment scheme has also been investigated to decrease the system energy consumption and delay [32]. For D2D-enabled dense HetNets, a joint power assignment and user scheduling which can improve the system SE has been studied [33]. Furthermore, four spectrum sharing modes have been proposed for achieving a large performance gain in NOMA-and-D2D integrated networks [34].…”