Spectrum Resource and Power Allocation With Adaptive Proportional Fair User Pairing for NOMA Systems

Ken Long,Wei Li,Pengyu Wang,Dejian Chen

doi:10.1109/access.2019.2908673

Ken Long, Wei Li + Show 2 more

Open Access

https://doi.org/10.1109/access.2019.2908673

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Abstract

In this paper, we investigate the spectrum resource and power allocation problem for the tradeoff between maximizing the sum rate and minimum rate requirements of users in non-orthogonal multiple access (NOMA) system. First, we formulate the NOMA techniques, basic principles, and double-objective optimization (DOO) problem. Then, the non-convexity of the DOO problem is converted into a single-objective optimization (SOO) problem by power discretization method. Global optimal search (GOS) algorithm is applied to solve the user-subchannel matching and power allocation problem. Due to its high complexity and unfairness among users, it is only suitable for determining the upper bound of users throughput performance. Finally, yet importantly, a spectrum resource and power allocation algorithm with adaptive proportional fair (APF) user pairing is proposed to convert the original optimization problem into user pairing, sub-channel, and power allocation. The users paired on the sub-channel are determined by the scheduling priority which is based on the equivalent channel gain. The BS dynamically adjusts the forgetting factor in the APF algorithm based on the variance of all the users' scheduling priorities so as to influence the update of users' scheduling weights. The power allocation stage proposes three power allocation schemes to ensure the users' minimum data rate requirements under the condition that effectively guarantees the correct execution of successive interference cancellation (SIC). The simulation results demonstrate that it can not only approach the throughput performance compared with the global optimal search and the classical water-filling (WF) power allocation using matching theory but also can improve the fairness of the users.

Highlights

In the coming decades, more and more application scenarios and emerging technologies will place higher demands on 5G networks, such as Artificial Intelligence (AI), Internet of Things (IoT) and Big Data (BD). 5G will develop current mobile and fixed networks into new, integrated and ultra-flexible energy-efficient networks [1]
OPTIMIZATION PROBLEM FORMULATION for the capacity optimization problem of user pairing and resource allocation in non-orthogonal multiple access (NOMA) downlink system, we assume that the number of users multiplexed on each sub-channel is M, the throughput achieved by the multiplexing user n on the sub-channel k is expressed as [10]
SIMULATION SCENARIO SETUP we evaluate the performance of the proposed global optimal search algorithm, spectrum resource and power allocation with adaptive proportional fair user pairing algorithm, and compare their performance with the most classical matching theory with water-filling power allocation algorithm and orthogonal frequency division multiple access (OFDMA) scheme

Summary

INTRODUCTION

More and more application scenarios and emerging technologies will place higher demands on 5G networks, such as Artificial Intelligence (AI), Internet of Things (IoT) and Big Data (BD). 5G will develop current mobile and fixed networks into new, integrated and ultra-flexible energy-efficient networks [1]. In [24], the authors proposed a low complexity water-filling power allocation algorithm, which is applied to the proportional fair scheduler of the downlink NOMA system. In [25], in order to maintain SC-FDM attributes and reduce the scheduling complexity of non-orthogonal multiplexing users with continuous resource allocation, the authors adopted an enhanced proportional fair scheduling scheme. B. MOTIVATION AND CONTRIBUTIONS For the downlink NOMA system, effective user pairing and resource allocation algorithm can significantly affect system throughput performance and user fairness. In order to achieve maximum system throughput under conditions that ensure proper detection of the successive interference cancellation, the second power allocation scheme firstly meets the minimum power requirements of the paired users, and the remaining power on the sub-channel is allocated to the high channel gain user.

FUNDAMENTALS OF DOWNLINK NOMA

INTRA-SUB-CHANNEL USER PARING AND POWER ALLOCATION

THREE POWER ALLOCATION SCHEMES

COMPLEXITY ANALYSIS

CONCLUSION