Enhanced energy-efficient downlink resource allocation in green non-orthogonal multiple access systems

Abstract

Non-orthogonal multiple access (NOMA) technique has the ability to support multiple transmissions simultaneously using the same physical resource, the idea of which achieves much enhanced performance for a system compared to the conventional orthogonal multiple access (OMA) techniques. Despite numerous advantages, this phenomenon of NOMA technique can bring additional interference for the neighboring ultra-dense networks if the power consumption of the system is not properly optimized. While targeting on the green communication concept, in this paper, we propose an energy-efficient downlink resource allocation scheme for a NOMA-equipped cellular network. The objective of this work is to allocate subchannels and power of the base station among the users so that the overall energy efficiency is maximized. Since this problem is NP-hard, we attempt to find an elegant solution with reasonable complexity that provides good performance for some realistic applications. To this end, we decompose the problem into a subchannel allocation subproblem followed by a power loading subproblem that allocates power to each user's data stream on each of its allocated subchannels. We first employ a many-to-many matching model under the assumption of uniform power loading in order to obtain the solution of the first subproblem with reasonable performance. Once the the subchanneluser mapping information is known from the first solution, we propose a geometric programming (GP)-based power loading scheme upon approximating the energy efficiency of the system by a ratio of two posynomials. The techniques adopted for these subproblems better exploit the available multi-user diversity compared to the techniques used in an earlier work. Having observed the computational overhead of the GP-based power loading scheme, we also propose a suboptimal computationally-efficient algorithm for the power loading subproblem with a polynomial time complexity that provides reasonably good performance. Extensive simulation has been conducted to verify that our proposed solution schemes always outperform the existing work while consuming much less power at the base station.

A New Green Prospective of Non-orthogonal Multiple Access (NOMA) for 5G

“…Power domain Resource allocation [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Energy harvesting and transfer [36][37][38][39][40][41][42][43][44][45][46][47][48][49] Interference cancellation techniques [50][51][52][53][54][55] Sleep/wake modes [56][57][58][59][60] Code domain Sparse code multiple access (SCMA) [61,62] Space time block coding (STBC) [56,63] Polar codes [64][...…”

“…A lot of literature discussed on the resource allocation to achieve energy efficiency of NOMA [16,[18][19][20][21][22][23][24][25][26][27][28]. Resource allocation is a key area to achieve the full potential of communication systems with NOMA [19].…”

Energy-efficient non-orthogonal multiple access for wireless communication system

“…Because of that, green communications need to be applicable to reduce the carbon footprint caused by the networking sector. Resultantly, green communication can be adapted to the networking system by applying energy efficient approaches [6]. Various algorithms have been developed by many researchers for enhancing the EE of NOMA systems.…”

Joint Computational Offloading and Data-Content Caching in NOMA-MEC Networks

“…Using the same frequency resources, multiple users may offload their computational tasks to the MEC server simultaneously. Therefore, integrating NOMA into MEC systems can enhance the computation-offloading efficiency and performance, i.e., reduce the delay and energy consumed in computational offloading, increasing the number of offloading users [13]- [15], [17]. Several studies on NOMA-MEC systems have centered on the issue of computational offloading optimization.…”