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10th European-Alliance-for-Innovation (EAI) International Conference on Wireless and Satellite Systems (WiSATS)

作者： Wu, Jingjing Wu, Shaochuan Zuo, Rundong Zhang, Wenbin Harbin Inst Technol Sch Elect & Informat Engn Harbin Peoples R China

ISBN: (纸本)9783030191566;9783030191559

5G research gradually focus on non-orthogonal multiple access technology, owing to huge traffic, more mobile terminals, and explosive growth of throughput capacity in recent years. Sparse code multiple access (SCMA) is a multi-dimensional codebook-based non-orthogonal multiplexing technique proposed to address the above requirements. This paper investigates the message passing algorithm (MPA) in the receiver of SCMA and proposes two multi-user detection algorithms with low computational complexity in uplink. Improved Variable message passing algorithm (IVMPA) reduces computational complexity compared to Variable message passing algorithm (VMPA) by changing the users iteration order. Incomplete Iterative message passing algorithm (IIMPA) is proposed to reduce the number of iteration for users with high signal-to-noise ratio (SNR) and reduces computational complexity compared to MPA.

关键词： SCMA Multi-user detection message passing algorithm Complexity

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User Activity Detection-based Large SCMA System for Uplink Grant-Free Access

User Activity Detection-based Large SCMA System for Uplink G...

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IEEE International Conference on Communications (IEEE ICC)

作者： Sharma, Sanjeev Deka, Kuntal Hong, Yi Monash Univ Dept Elect & Comp Syst Engn Clayton Vic 3800 Australia IIT Goa Sch Elect Sci Veling 403401 Goa India

ISBN: (纸本)9781728123738

Sparse code multiple access (SCMA) is a promising non-orthogonal multiple access (NOMA) technology for next generation wireless networks to achieve higher spectral efficiency and lower latency in massive machine type communication systems. In the massive uplink grant-free communications, users can conduct uplink instant transmissions without grant to reduce signaling overhead as well as the latency. Multiusers' data symbols are detected using the message passing algorithm (MPA) aided by the exact a priori information of the active users. However, prior knowledge of the active users is impractical in a grant-free communication system due to randomness in users' activity. Therefore, in this paper, we propose a compressive sensing based SCMA system for grant-free massive machine type communications. In the proposed large SCMA system, the active users are detected using a two-phase procedure and then MPA-based receiver is adopted for active users' data symbol detection. The ability of user detection, false detection probability, and bit error rate performances are analyzed over additive white Gaussian noise (AWGN) and Rayleigh fading channels. The corresponding results provide useful insight to design a large SCMA system in situations such as massive machine type communications where prior user-activity information is not readily available.

关键词： NOMA SCMA message passing algorithm compressive sensing user activity estimation grant-free system

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MC-CDMA and SCMA Performance and Complexity Comparison in Overloaded Scenarios

MC-CDMA and SCMA Performance and Complexity Comparison in Ov...

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IEEE Colombian Conference on Communications and Computing (COLCOM)

作者： Frison, Celso Iwata Carvajal Mora, Henry de Almeida, Celso Pontifical Univ Catholic Minas Gerais Elect Engn Dept Campus Pocos De Caldas PUC MINAS Pocos De Caldas MG Brazil Univ Amer UDLA Telecommun Engn Fac Engn & Appl Sci FICA Quito Ecuador Univ Estadual Campinas UNICAMP Elect & Comp Engn Fac FEEC Campinas SP Brazil

ISBN: (纸本)9781728135038

In 5G wireless networks, the perspective of very large number of simultaneous connections is challenging. In this sense, an overloaded system is a basic scenario of 5G multiple access techniques, that is, the number of active users is greater than the number of system subcarriers. Some schemes of non-orthogonal multiple access (NOMA) have been proposed in the literature and, two of them are compared in this paper. These NOMA techniques are the multi-carrier code division multiple access (MC-CDMA) and sparse code multiple access (SCMA). The performance, in terms of the mean bit error rate, and the decoding complexity, in terms of number of mathematical operations are evaluated. In MC-CDMA, the multi-user maximum likelihood detector (MU-MLD) implemented via sphere decoding (SD) algorithm is considered, which is the optimum receiver, but with polynomially complexity. In SCMA, a near optimal receiver is used, named as message passing algorithm (MPA), which is based on the sum-product algorithm, whose complexity does not depend, directly, on the number of users. Monte Carlo simulations and theoretical expressions are used to compare both multiple access techniques in the uplink of a cellular scenario. Results show that, for an equivalent spectral efficiencies, MC-CDMA performs better than SCMA and SD algorithm is less complex than MPA.

关键词： 5G MC-CDMA message passing algorithm Overload Scenarios SCMA Sphere Decoder

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Position and Velocity Estimations of Mobile Device Incorporate GNSS

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IEEE ACCESS 2018年 6卷 31141-31147页

作者： Rana, Md M. Xiang, Wei Li, Xuehua James Cook Univ Coll Sci & Engn Cairns Qld 4870 Australia Beijing Informat Sci & Technol Univ Beijing 100192 Peoples R China

Today, the global navigation satellite system (GNSS) is usually integrated into smart mobile devices for necessary communication with the possibility of locating users accurately in the surrounding environment. In contrast to the traditional estimation approaches, this paper proposes a message passing algorithm for position and velocity estimations of the mobile device incorporate GNSS. First, the smart mobile device incorporate GNSS is modeled as a state-space framework. Then the message passing scheme is proposed considering the Bayesian tree structure. In this scheme, the messages are shifted between forward and backward nodes so that the estimation error is minimized. The simulation results show that the proposed algorithm provides significant performance improvement compared with the existing Kalman filter.

关键词： Bayesian tree structure position and velocity estimation global navigation satellite system message passing algorithm mobile device

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Spatial Modulation Aided Sparse Code-Division Multiple Access

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第3期17卷 1474-1487页

作者： Liu, Yusha Yang, Lie-Liang Hanzo, Lajos Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

In order to support high-user-load multiple-access (MA), we propose a non-orthogonal MA scheme based on a beneficial amalgam of spatial modulation (SM) and sparse code-division multiple-access (SCDMA), which is termed the SM-SCDMA. Hence, SM-SCDMA inherits both the merits of SM with single radio-frequency MIMO transceiver implementation and the advantages of SCDMA relying on low-complexity signal detection. In this paper, we evaluate the potential of SM-SCDMA as well as its low-complexity near-optimum signal detection. Given these objectives, we consider both the maximum likelihood detection and the message passing algorithm aided detection (MPAD) that is derived based on the maximum a posteriori principles. In order to evaluate the performance of large SM-SCDMA without relying on time-consuming simulations, we propose new approaches for analyzing the performance of SM-SCDMA systems. A range of formulas that are valid in the signal-to-noise ratio region of practical interest are derived. Finally, the performance of SM-SCDMA systems is investigated by addressing diverse design concerns. Our studies and performance results show that SM-SCDMA constitutes a promising MA scheme for the future ultra dense systems. Assisted by the MPAD, it is capable of supporting high-user-load MA transmission associated with a normalized user-load factor of two.

关键词： CDMA NOMA spatial modulation low density signature maximum a posteriori detection maximum-likelihood detection message passing algorithm performance analysis

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Low-Complexity Detectors for Uplink SCMA: Symbol Flipping and Dynamic Partial Marginalization-Based MPA 87

Low-Complexity Detectors for Uplink SCMA: Symbol Flipping an...

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87th IEEE Vehicular Technology Conference (VTC-Spring)

作者： Wei, Li Huang, Bo Zheng, Jianping Xidian Univ State Key Lab Integrated Serv Networks Xian Peoples R China

ISBN: (纸本)9781538663554

In this paper, two low-complexity detectors for uplink sparse code multiple access (SCMA) systems are proposed. The first, called symbol flipping algorithm (SFA), is an analogy of the bit-flipping decoding algorithm in the low-density parity check code field. Specifically, the local hard-decision detection is first performed at each resource node, and the decided signal in the least reliable resource node is flipped. The second is an improved partial marginalization (PM)-based message passing algorithm (MPA). Based on the reliability definition introduced in SFA, the variable nodes to be marginalized are determined dynamically during the MPA iteration procedure, and the resulted detector is termed as dynamic PM-based MPA. Simulation results show that the proposed hard-decision SFA can achieve a numerous complexity reduction and the proposed dynamic PM-based MPA has better performance than the conventional PM-based MPA.

关键词： Sparse code multiple access multi-user detection bit flipping message passing algorithm complexity

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A Low Complexity SCMA Detector Based on Avoiding Redundant Iterations 12

A Low Complexity SCMA Detector Based on Avoiding Redundant I...

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12th International Symposium on Medical Information and Communication Technology (ISMICT)

作者： Hao, Shuliang Su, Xin Zeng, Jie Ma, Xin Lv, Tiejun Chongqing Univ Posts & Telecommun Chongqing Peoples R China Beijing Gongjin Elect Co Ltd Beijing Peoples R China Beijing Gongjin Elect Co Ltd Beijing Peoples R China Beijing Univ Posts & Telecommun Beijing Peoples R China

ISBN: (纸本)9781538633892

Sparse code multiple access (SCMA), a competitive air-interface technology with the message passing algorithm (MPA) employed at the receiver, has a broad application prospect. However, the computational complexity of MPA is still an extreme challenge for SCMA decoding. In this paper, a low complexity multiuser detection algorithm based on avoiding redundant iterations, namely Avoiding Redundant Iterations-MPA (ARI-MPA), is proposed for the uplink SCMA system. ARI-MPA can achieve low complexity by avoiding redundant iterations, in which the number of iterations required is determined by the convergence rate of codeword probability. Numerical results demonstrate that the proposed scheme can achieve an affordable trade-off between bit error ratio (BER) performance and decoding complexity for the SCMA system.

关键词： Sparse code multiple access message passing algorithm avoiding redundant iterations multiuser detection

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Overview of Sparse Graph for Multiple Access in Future Mobile Networks

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FREQUENZ 2017年第11-12期71卷 601-610页

作者： Lei, Jing Li, Baoguo Li, Erbao Gong, Zhenghui Natl Univ Def Technol Sch Elect Sci & Engn Deya Rd 47 Changsha 410073 Hunan Peoples R China

Multiple access via sparse graph, such as low density signature (LDS) and sparse code multiple access (SCMA), is a promising technique for future wireless communications. This survey presents an overview of the developments in this burgeoning field, including transmitter structures, extrinsic information transform (EXIT) chart analysis and comparisons with existing multiple access techniques. Such technique enables multiple access under overloaded conditions to achieve a satisfactory performance. message passing algorithm is utilized for multi-user detection in the receiver, and structures of the sparse graph are illustrated in detail. Outlooks and challenges of this technique are also presented.

关键词： sparse graph multiple access multi-user detection mobile networks EXIT chart message passing algorithm

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message passing-Based Decoding of Convolutional Codes: Performance and Complexity Analysis

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IEEE COMMUNICATIONS LETTERS 2016年第2期20卷 216-219页

作者： Mani, Hossein Saeedi, Hamid Tarbiat Modares Univ Dept Elect & Comp Engn Tehran 14115194 Iran

In this letter, we propose to apply message passing algorithms to decode standard convolutional codes and assess the resulting performance and the required complexity compared to conventional decoding algorithms for convolutional codes by concentrating on the Viterbi algorithm (VA). We show that, in contrast to the VA for which the decoding complexity increases exponentially with m, the number of memory blocks for the proposed framework, such an increase, is only linear in m. This suggests that applying message passing algorithms can provide considerable savings in the required computational power if it can also exhibit a comparable bit-error-rate performance to that of the VA. In this letter, we show via simulations that this is in fact the case for convolutional codes.

关键词： Convolutional codes message passing algorithm low-density parity-check codes

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Low Complexity Iterative Receiver Design for Sparse Code Multiple Access

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IEEE TRANSACTIONS ON COMMUNICATIONS 2017年第2期65卷 621-634页

作者： Wei, Fan Chen, Wen Shanghai Jiao Tong Univ Shanghai Key Lab Nav Locat Based Serv Minhang 200240 Peoples R China Guilin Univ Elect Technol Sch Elect Engn & Automat Guilin 541000 Peoples R China

Sparse code multiple access (SCMA) is one of the most promising methods among all the non-orthogonal multiple access techniques in the future 5G communication. Compared with some other non-orthogonal multiple access techniques, such as low density signature, SCMA can achieve better performance due to the shaping gain of the SCMA code words. However, despite the sparsity of the code words, the decoding complexity of the current message passing algorithm utilized by SCMA is still prohibitively high. In this paper, by exploring the lattice structure of SCMA code words, we propose a low-complexity decoding algorithm based on list sphere decoding (LSD). The LSD avoids the exhaustive search for all possible hypotheses and only considers signal within a hypersphere. As LSD can be viewed a depth-first tree search algorithm, we further propose several methods to prune the redundancy-visited nodes in order to reduce the size of the search tree. Simulation results show that the proposed algorithm can reduce the decoding complexity substantially while the performance loss compared with the existing algorithm is negligible.

关键词： Non-orthogonal multiple access SCMA message passing algorithm list sphere decoding node pruning

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