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RIS-Aided SCMA-Based SWIPT Systems: Design and Optimization

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2023年第5期72卷 6238-6252页

作者： Chai, Lingyun Bai, Lin Bai, Tong Choi, Jinho Zhang, Wei Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Beihang Univ Sch Cyber Sci & Technol Beijing 100191 Peoples R China Beihang Univ Beijing Lab Gen Aviat Technol Beijing 100191 Peoples R China Deakin Univ Sch Informat Technol Geelong Vic 3220 Australia Univ New South Wales Sch Elect Engn & Telecommun Sydney NSW 2052 Australia

The amalgamation of sparse code multiple access (SCMA) and simultaneous wireless information and power transfer (SWIPT) is envisioned to be a promising solution to massive connectivity while providing both information and power to myriads of wireless machines and sensors in Internet-of-Things (IoT) application. However, the benefit of the SCMA-based SWIPT system has not been fully exploited yet, especially when the communications link is hostile. Fortunately, the propagation-induced impairment can be mitigated by the emerging technique of reconfigurable intelligent surface (RIS). In this paper, we investigate the beneficial role of RIS in SCMA-based SWIPT systems, where $K$ single-antenna information receivers and one signal-antenna energy receiver are served by a multiple-antenna base station over $J$ orthogonal subcarriers with the aid of RIS. We propose transmit power minimization algorithms for both i) the perfect and ii) the imperfect channel state information (CSI) scenarios, by jointly optimizing the codebook assignment, the BS active beamforming, as well as RIS reflection coefficients, relying on advanced techniques both of alternating optimization and of successive convex approximations, and on the robust design framework. Furthermore, we compare and evaluate the detection performance of the system considered. The numerical results demonstrate that our proposed RIS-aided SCMA-based SWIPT system significantly outperforms the conventional SCMA-based SWIPT system without RIS and is capable of adapting to the imperfect full channel estimation results.

关键词： NOMA Wireless communication Downlink Optimization Base stations Array signal processing Wireless sensor networks sparse code multiple access simultaneous wireless information and power transfer reconfigurable intelligent surface imperfect channel state information

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Design of SCMA codebooks Based on Golden Angle Modulation

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2019年第2期68卷 1501-1509页

作者： Mheich, Zeina Wen, Lei Xiao, Pei Maaref, Amine Univ Surrey 5G Innovat Ctr Inst Commun Syst Guildford GU2 7XH Surrey England Natl Univ Def Technol Dept Commun Engn Coll Elect Sci & Engn Changsha 410073 Hunan Peoples R China Huawei Technol Co Ltd Canada Res Ctr Ottawa ON K2K 3J1 Canada

In this paper, we propose to use golden angle modulation (GAM) points to construct codebooks for uplink and downlink sparse code multiple access (SCMA) systems. We provide two categories of codebooks with one and two optimization parameters, respectively. The advantages of the proposed design method are twofold: 1) the number of optimization variables is independent of codebook and system parameters;and 2) it is simple to implement. In the downlink, we use GAM points to build a multidimensional mother constellation for SCMA codebooks, while in the uplink GAM points are directly mapped to user codebooks. The proposed codebooks exhibit good performance with low peak to average power ratio compared to the codebooks proposed in the literature based on constellation rotation and interleaving.

关键词： sparse code multiple access codebook design golden angle modulation mapping PAPR reduction

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SGMA: Semi-granted multiple access for non-orthogonal multiple access (NOMA) in 5G networking

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JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 2018年 112卷 115-125页

作者： Yang, Mao Li, Bo Bai, Zhicheng Yan, Zhongjiang Northwestern Polytech Univ Sch Elect & Informat Xian Shaanxi Peoples R China

With the rapid prosperity of mobile Internet, proliferating smart terminals, and deep penetration of Internet of things (IoTs), the fourth generation mobile communication system (4G) has become increasingly unable to meet the human needs. Therefore, the fifth generation mobile communication system (5G), being studied world-widely, needs to directly face to ultra-huge network capacity and the massive wireless connectivity. Non-orthogonal multiple access (NOMA), enabling different user equipments (UEs) sharing overlapping wireless resources, is regarded as one of the most promising key technologies of 5G, and has attracted great attention in both industry and academia in recent years. In order to guarantee the quality of service (QoS) and achieve low access latency and signaling overhead, NOMA needs to support two kinds of access methods: scheduling access and random access, named granted access and grant-free access respectively. However, how to efficiently support both granted and grant-free access simultaneously becomes a tricky challenge. In this article, we propose semi-granted multiple access, named SGMA. Other than strictly separating the wireless resources between granted and grant-free access, SGMA allows both of them to share the same resources. SGMA is a general method that can be used in several potential NOMA solutions. We also model SGMA and analyze the performance. Moreover, a heuristic resource allocation algorithm for SGMA is proposed. The simulation results show that SGMA further improves the network capacity and user connectivity of NOMA in 5G networking, and also adapts to the dynamic time-varying services. To the best of our knowledge, this is the first work to propose a multiple access method to allow the granted and grant-free access sharing the same wireless spectrum and further design the resource allocation algorithm in 5G NOMA system.

关键词： Non-orthogonal multiple access NOMA sparse code multiple access SCMA Resource allocation Random access 5G

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A Low-Complexity Energy-Minimization-Based SCMA Detector and Its Convergence Analysis

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2018年第12期67卷 12398-12403页

作者： Yuan, Weijie Wu, Nan Yan, Chaoxing Li, Yonghui Huang, Xiaojing Hanzo, Lajos Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China Univ Technol Sydney Fac Engn & Informat Technol Sydney NSW 2007 Australia Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

sparse code multiple access (SCMA) has emerged as a promising non-orthogonal multiple access technique for the next-generation wireless communication systems. Since the signal of multiple users is mapped to the same resources in SCMA, its detection imposes a higher complexity than that of the orthogonal schemes, where each resource slot is dedicated to a single user. In this paper, we propose a low-complexity receiver for SCMA systems based on the radical variational free energy framework. By exploiting the pairwise structure of the likelihood function, the Bethe approximation is utilized for estimating the data symbols. The complexity of the proposed algorithm only increases linearly with the number of users, which is much lower than that of the maximum a posteriori detector associated with exponentially increased complexity. Furthermore, the convergence of the proposed algorithm is analyzed, and its convergence conditions are derived. Simulation results demonstrate that the proposed receiver is capable of approaching the error probability performance of the conventional message-passing-based receiver.

关键词： sparse code multiple access variational free energy Bethe approximation convergence analysis

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Joint SCMA and waveform optimisation for WPDM-based logging cable telemetry systems under sampling clock offset

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IET COMMUNICATIONS 2019年第3期13卷 345-353页

作者： Cui, Qian Shuang, Kai China Univ Petr Coll Geophys & Informat Engn Beijing 102249 Peoples R China China Univ Petr State Key Lab Petr Resources & Prospecting Beijing 102249 Peoples R China

This study introduces sparse code multiple access (SCMA) and wavelet packet division multiplexing (WPDM) to logging cable telemetry systems (LCTSs). The authors study the feasibility of SCMA for LCTSs and provide a WPDM-based system model, as well as the associated optimal waveform design under sampling clock offset (SCO) via a genetic algorithm. The performance advantages of the designed scheme over the conventional WPDM and orthogonal frequency division multiplexing (OFDM) are demonstrated by both analytical and simulation methods. Numerical results show the performance of the SCMA-based mapping method over quadrature amplitude modulation in terms of improved spectral efficiency. Furthermore, the new scheme outperforms conventional WPDM and OFDM in bit error rate performance and transmission rate under SCO. Such advantages with the flexible design of basis functions make SCMA and WPDM a significant candidate for LCTSs.

关键词： quadrature amplitude modulation OFDM modulation genetic algorithms error statistics wavelength division multiplexing telecommunication cables radiotelemetry code division multiple access joint SCMA waveform optimisation sparse code multiple access WPDM-based system model associated optimal waveform design SCO OFDM SCMA-based mapping method bit error rate performance sampling clock offset wavelet packet division multiplexing LCTS orthogonal frequency division multiplexing WPDM-based logging cable telemetry systems genetic algorithm quadrature amplitude modulation spectral efficiency transmission rate

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Iterative Receivers for Downlink MIMO-SCMA: Message Passing and Distributed Cooperative Detection

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第5期17卷 3444-3458页

作者： Yuan, Weijie Wu, Nan Guo, Qinghua Li, Yonghui Xing, Chengwen Kuang, Jingming Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China Univ Wollongong Sch Elect Comp & Telecommun Engn Wollongong NSW 2522 Australia Univ Sydney Sch Elect & Informat Engn Ctr Excellence Telecommun Sydney NSW 2006 Australia

The rapid development of mobile communications requires even higher spectral efficiency. Non-orthogonal multiple access (NOMA) has emerged as a promising technology to further increase the access efficiency of wireless networks. Among several NOMA schemes, it has been shown that sparse code multiple access (SCMA) is able to achieve better performance. In this paper, we consider a downlink MIMO-SCMA system over frequency selective fading channels. For optimal detection, the complexity increases exponentially with the product of the number of users, the number of antennas and the channel length. To tackle this challenge, we propose near optimal low-complexity iterative receivers based on factor graph. By introducing auxiliary variables, a stretched factor graph is constructed and a hybrid belief propagation (BP) and expectation propagation (EP) receiver, named stretch-BP-EP, is proposed. Considering the convergence problem of BP algorithm on loopy factor graph, we convexify the Bethe free energy and propose a convergence-guaranteed BP-EP receiver, named conv-BP-EP. We further consider cooperative network and propose two distributed cooperative detection schemes to exploit the diversity gain, namely, belief consensus-based algorithm and the Bregman alternative direction method of multipliers (ADMM)-based method. Simulation results verify the superior performance of the proposed conv-BP-EP receiver compared with other methods. The two proposed distributed cooperative detection schemes can improve the bit error rate performance by exploiting the diversity gain. Moreover, Bregman ADMM method outperforms the belief consensus-based algorithm in noisy inter-user links.

关键词： sparse code multiple access multiple-input multiple-output belief propagation expectation propagation variational free energy distributed cooperative detection

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Backtracking codebook Matching Algorithm Based on codebook Correlation for Uplink SCMA System

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IEEE COMMUNICATIONS LETTERS 2017年第7期21卷 1597-1600页

作者： Dai, Yanpeng Sheng, Min Liu, Junyu Liu, Lei Li, Jiandong Xidian Univ Inst Informat Sci State Key Lab Integrated Serv Networks Xian 710071 Peoples R China

In this letter, we have investigated the frequency diversity gain of a sparse code multiple access (SCMA) system to improve spectrum utilization by exploiting the codebook correlation in the SCMA system. To this end, a backtracking codebook matching (BCM) algorithm is proposed, whereby there are more successfully scheduled users, which are allocated the low-correlated codebooks. Simulation results exhibit the superiority of the BCM algorithm and the impact of codebook correlation on scheduling.

关键词： sparse code multiple access frequency diversity gain codebook correlation resource allocation

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Rate and Energy Maximization in SCMA Networks With Wireless Information and Power Transfer

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IEEE COMMUNICATIONS LETTERS 2016年第2期20卷 360-363页

作者： Zhai, Daosen Sheng, Min Wang, Xijun Li, Yuzhou Song, Jiongjiong Li, Jiandong Xidian Univ Inst Informat Sci State Key Lab Integrated Serv Networks Xian 710071 Peoples R China

In this letter, we investigate the fundamental tradeoff between rate and energy for sparse code multiple access (SCMA) networks with wireless power transfer. A weighted rate and energy maximization problem by jointly considering power allocation, codebook assignment, and power splitting, is formulated. To solve the hard problem, an iterative algorithm based on the univariate search technique is proposed, which has good performance with low complexity. Specifically, we analyze the special structure of the problem and exploit it to obtain the optimal power splitting ratio and resource allocation strategy when one of them is fixed. Simulation results indicate that our algorithm achieves a better rate-energy tradeoff compared to other schemes.

关键词： sparse code multiple access simultaneous wireless information and power transfer energy harvesting

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A Novel Spectrally-Efficient Uplink Hybrid-Domain NOMA System

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IEEE COMMUNICATIONS LETTERS 2020年第11期24卷 2609-2613页

作者： Quan, Chen Yadav, Animesh Geng, Baocheng Varshney, Pramod K. Poor, H. Vincent Syracuse Univ Dept Elect Engn & Comp Sci Syracuse NY 13244 USA Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

This letter proposes a novel hybrid-domain (HD) non-orthogonal multiple access (NOMA) approach to support a larger number of uplink users than the recently proposed code-domain NOMA approach, i.e., sparse code multiple access (SCMA). HD-NOMA combines the code-domain and power-domain NOMA schemes by clustering the users in small path loss (strong) and large path loss (weak) groups. The two groups are decoded using successive interference cancellation while within the group users are decoded using the message passing algorithm. To further improve the performance of the system, a spectral-efficiency maximization problem is formulated under a user quality-of-service constraint, which dynamically assigns power and subcarriers to the users. The problem is non-convex and has sparsity constraints. The alternating optimization procedure is used to solve it iteratively. We apply successive convex approximation and reweighted l(1) minimization approaches to deal with the non-convexity and sparsity constraints, respectively. The performance of the proposed HD-NOMA is evaluated and compared with the conventional SCMA scheme through numerical simulation. The results show the potential of HD-NOMA in increasing the number of uplink users that can be supported in a given time-frequency resource.

关键词： Uplink NOMA Decoding Silicon carbide Optimization Resource management Message passing sparse code multiple access non-orthogonal multiple access wireless communications

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SCMA codebook for Uplink Rician Fading Channels

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IEEE COMMUNICATIONS LETTERS 2023年第2期27卷 527-531页

作者： Lei, Tuofeng Ni, Shuyan Cheng, Naiping Chen, Shimiao Song, Xin Space Engn Univ Dept Elect & Opt Engn Beijing 101416 Peoples R China

In this letter, the codebook design criteria for uplink Rician fading channels are explored. The probability distribution of the weighted sums of the Rician random variables from each frequency resource is derived based on the independent non-central circular complex Gaussian random variable. Then, considering the pairwise error probability, the key performance indicators of multidimensional constellations for uplink Rician channels are explored. A sub-optimal optimization approach is deployed to generate an enhanced codebook for various Rician scenarios. Finally, numerical results are provided to verify the key performance indicators in the uplink Rician fading channels.

关键词： Rician channels Uplink Rayleigh channels NOMA Symbols Signal to noise ratio Euclidean distance sparse code multiple access uplink Rician channel key performance indicators codebook design

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