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A Low-complexity SCMA Detector Based on Discretization

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第4期17卷 2333-2345页

作者： Zhang, Chenchen Luo, Yuan Chen, Yan Shanghai Jiao Tong Univ Dept Comp Sci & Engn Shanghai 200240 Peoples R China Huawei Technol Co Ltd Shanghai 200040 Peoples R China

As a new multiple access technique, sparse code multiple access (SCMA) combines quadrature amplitude modulation mapper and spreading together and thus significantly improves spectral efficiency. However, the computation complexity of most existing detection algorithms increases exponentially with d (f) (the degree of the resource nodes). The parameter d (f) must be designed to be very small, which largely limits the choice of codebooks. Even if the codebooks are designed to have low density, the detection still takes considerable time. In this paper, a new detection algorithm is proposed by discretizing the probability density functions (PDFs) in the layer nodes. Actually, the PDFs are updated according to the constraints in the factor graph after discretization. Compared with the conventional message passing algorithm (MPA) detector, the proposed detector only takes polynomial time to update one message in resource nodes instead of exponential time with negligible performance loss. In particular, it only needs near-linear time, if the real part is independent with the imaginary part in SCMA system. Furthermore, this paper presents a new design for codebooks by greedy strategy and exhaustive search in each step. The search is feasible with the help of discretization, and the resulting codebooks have good performance in the proposed detection algorithm, as well as in the conventional MPA.

关键词： SCMA detection complexity discretization constraints in factor graph codebook design

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Enabling High Order SCMA Systems in Downlink Scenarios With a Serial Coding Scheme

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IEEE ACCESS 2018年 6卷 33796-33809页

作者： Han, Yuxi Zhou, Wuyang Zhao, Ming Zhou, Shengli Univ Sci & Technol China Chinese Acad Sci Key Lab Wireless Opt Commun Hefei 230027 Anhui Peoples R China Univ Connecticut Dept Elect & Comp Engn Storrs CT 06269 USA

In the future fifth generation communication systems, sparse code multiple access (SCMA) shows strong competitiveness as a novel non-orthogonal multiple access (NOMA) technique. Attributing to multi-dimensional codebooks, the SCMA can obtain shaping gain and provide a better performance than some other NOMA schemes, such as pattern division multiple access, low-density signature (LDS), and so on. However, under higher user load, each orthogonal resource in high-order SCMA systems is occupied by more users and the constellations of these systems possess smaller Euclidean distances, both of which will degrade the link performance. The iterative algorithm employed in SCMA decoding, namely message passing algorithm, will also bring an exponential growth of computational complexity. In this paper, a scheme with serial codes for system order reduction in downlink scenarios, namely serial SCMA, is proposed to tackle these issues. Based on the idea of hierarchical coding, the processes of encoding and decoding in a high-order system are decomposed into several processes in low-order systems. Specific mapping modules are designed to recover the original user binary bits. Simulation results show that serial SCMA will substantially cut down the detection complexity and enjoy better link performance while maintaining sparser codebooks. Besides, it still inherits the advantages of original SCMA systems such as overloading and average aggregate energy efficiency over OMA and other NOMA schemes.

关键词： High order SCMA systems serial SCMA pattern matrix Log-MPA detection complexity

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A New Constellation Diagram-Based Signal detection for GSM-MIMO Systems

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IEEE COMMUNICATIONS LETTERS 2018年第3期22卷 502-505页

作者： Wu, Shijuan Tao, Xiaofeng Chen, Yu Beijing Univ Posts & Telecommun Natl Engn Lab Mobile Network Technol Wireless Technol Innovat Inst Beijing 100876 Peoples R China

The generalized spatial modulation is a multi-input multi-output modulation technique that improves spectral and energy efficiency, but also increases receivers' detection complexity. In this letter, we first propose a new constellation diagram, and then realize: a joint detection of modulated and zero-power signals and a companion detection algorithm based on this new diagram. Simulation results show that our algorithm can achieve near maximum likelihood bit error rate performance and reduce complexity at a maximum rate of 42% compared with the conventional ordered block minimum mean-squared error algorithm.

关键词： Generalized spatial modulation (GSM) new constellation diagram OB-MMSE detection complexity

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Generalised differential scheme for spatial modulation systems

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IET COMMUNICATIONS 2017年第13期11卷 2020-2026页

作者： Kadathlal, Kavish Xu, HongJun Pillay, Narushan Univ KwaZulu Natal Sch Engn Elect Elect & Comp Engn Durban 4041 South Africa

Spatial modulation (SM) is an efficient transmission scheme based on multiple-input multiple-output systems. SM, by nature, requires coherent detection to achieve optimal error performance. This requires that the receiver has full knowledge of the channel state information (CSI), however, determining the CSI results in an increase in the detection complexity at the receiver. Differential modulation systems are capable of performing detection without knowledge of the CSI at the receiver, however, they suffer a 3dB error performance penalty as compared to their coherent counterparts. In this study, the authors present a generalised differential scheme for SM (GD-SM) based on generalised differential modulation, which is capable of reducing the performance penalty incurred through optimal power allocation. Furthermore, they extend the architecture of GD-SM and optimal power allocation to conventional differential SM. The architecture of the proposed systems, advantageously permits the use of either M-ary quadrature amplitude modulation or M-ary phase shift keying constellations. Simulation and theoretical results demonstrate that GD-SM incurs only about 0.5dB performance loss as compared to coherent SM when the frame length is 400.

关键词： MIMO communication signal detection modulation generalised differential scheme spatial modulation systems transmission scheme multiple-input multiple-output systems coherent detection optimal error performance channel state information CSI detection complexity error performance penalty GD-SM generalised differential modulation optimal power allocation M-ary quadrature amplitude modulation M-ary phase shift keying constellation conventional differential SM

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Layered Space Shift Keying Modulation Over MIMO Channels

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第1期66卷 159-174页

作者： Fang, Shu Li, Lei Hu, Su Tang, Jianhua Yue, Zongdi Feng, Gang Pandharipande, Ashish Univ Elect Sci & Technol China Dept Natl Key Lab Commun Chengdu 611731 Peoples R China Singapore Univ Technol & Design Singapore 487372 Singapore Philips Res High Tech Campus NL-5656 AE Eindhoven Netherlands

Space shift keying (SSK) modulation is an emerging transmission technique for multiple-input multiple-output (MIMO) wireless channels, which exploits the spatial domain to convey information. In this paper, we present a layered space shift keying (LSSK) modulation scheme to fully exploit the spatial domain to transmit information bits, where a layered architecture is developed to achieve spatial multiplexing transmission in an SSK system. Specifically, LSSK leverages the rotated signals predetermined at the transceiver to identify different layers and improve thebit-error-rate (BER) performance. The layered signals are directly generated by the proposed LSSK modulation method with a low computational overhead. Furthermore, we propose a layered-and-joint (LJ) near-optimal detection algorithm based on the layered architecture of LSSK to reduce the detection complexity. In LJ detection, layered detection is performed to find a set of detection candidates for each layer, and then, joint detection is performed with these candidates. We show that the performance of LJ detection is quite close to that of optimal maximum-likelihooddetectionwith significantly reduced detection complexity for high-spectrum-efficiency scenarios. Results demonstrate that the proposed LSSK scheme substantially improves the spectrum efficiency of an SSK system and outperforms other existing MIMO schemes.

关键词： detection complexity layered space shift keying (LSSK) modulation maximum likelihood (ML) detection multiple-input multiple-output (MIMO) space shift keying (SSK) modulation

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Channel detection in Coded Communication

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第10期63卷 6364-6392页

作者： Weinberger, Nir Merhav, Neri Technion Israel Inst Technol IL-32000 Haifa Israel Tel Aviv Univ IL-69978 Tel Aviv Israel

The problem of block-coded communication where in each block the channel law belongs to one of two disjoint sets is considered. The decoder is aimed to decode only messages that have undergone a channel from one of the sets, and thus has to detect the set which contains the underlying channel. The simplified case where each of the sets is a singleton is studied first. The decoding error, false alarm, and misdetection probabilities of a given code are defined, and the optimum detection/decoding rule in a generalized Neyman-Pearson sense is derived. Sub-optimal detection/decoding rules are also introduced which are simpler to implement. Then, various achievable bounds on the error exponents are derived, including the exact single-letter characterization of the random coding exponents for the optimal detector/decoder. The random coding analysis is then extended to general sets of channels, and an asymptotically optimal detector/decoder under a worst case formulation of the error probabilities is derived, as well as its random coding exponents. The case of a pair of binary symmetric channels is discussed in detail.

关键词： detection complexity error exponents expurgated bounds false alarm joint detection/decoding misdetection mismatch detection random coding universal detection

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Outage Analysis for Group Detectors in MIMO Fading Channels 17

Outage Analysis for Group Detectors in MIMO Fading Channels

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17th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

作者： Ismail, Amr Tosato, Filippo Toshiba Res Europe Ltd 32 Queen Sq Bristol BS1 4ND Avon England

ISBN: (纸本)9781509017492

Multiple-input multiple-output (MIMO) techniques are now being commonplace in wireless communication systems as they provide diversity and spatial multiplexing gains compared to single-input single-output (SISO) systems. Due to the induced high complexity of maximum likelihood (ML) detection for MIMO systems, suboptimal detection is usually employed but at a performance loss. This loss has been fully characterized for linear receivers, namely, zero-forcing (ZF) and minimum mean square error (MMSE) detectors. Interestingly, it has been noticed that in case of coding across transmit antennas, the MMSE receiver showed significant improvement over ZF in terms of outage probability at low spectral efficiencies, whereas for high spectral efficiencies, both receivers showed similar behaviour. We fill the gap between the two extreme cases (i.e., ML and linear receivers) through relaxing the linearity constraint by considering group receivers (viz. group zero-forcing (GZF) and group minimum mean square error (GMMSE) detectors) with coding across transmit antennas. We first derive the diversity-multiplexing tradeoff (DMT) for those group detectors. Next, we characterize the peculiar rate-dependent outage behaviour of the GMMSE, where it is found that tolerating additional detection complexity provides performance advantage w.r.t the MMSE at specific ranges of spectral efficiency. We corroborate our theoretical analysis via numerical simulations.

关键词： Multiple-input multiple-output systems detection complexity outage probability group decoding

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Outage Analysis for Group Detectors in MIMO Fading Channels

Outage Analysis for Group Detectors in MIMO Fading Channels

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IEEE International Workshop on Signal Processing Advances in Wireless Communications

作者： Amr Ismail Filippo Tosato Toshiba Research Europe Ltd 32 Queen Square Bristol BS1 4ND UK

ISBN: (纸本)9781509017508

关键词： Multiple-input multiple-output systems detection complexity Outage probability Group decoding

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Study of various space time codes for MIMO systems

Study of various space time codes for MIMO systems

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2015 IEEE International Conference on Computational Intelligence & Communication Technology (CICT 2015)

作者： Singh, Garima Kumar, Arvind Natl Inst Technol Dept ECE Kurukshetra 136119 Haryana India

ISBN: (纸本)9781479960224

In this paper, a comparative analysis of various space time codes that are used in multiple input multiple output (MIMO) systems to achieve high data rate at high quality of service is presented. MIMO systems are analyzed under fading environment and their performance in terms of diversity gain, data rate, detection complexity, size of signal constellations, bit error rate, coding gain and peak -to-average power ratio is evaluated.

关键词： Diversity detection complexity fading MIMO systems peak-to-average power space-time coding spatial multiplexing

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Near-optimum detection scheme with relay selection technique for asynchronous cooperative relay networks

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IET COMMUNICATIONS 2014年第8期8卷 1347-1354页

作者： Qaja, Walid Mohamed Elazreg, Abdulghani M. Chambers, Jonathon A. Univ Loughborough Sch Elect Elect & Syst Engn Loughborough LE11 3TU Leics England Mil Technol Coll Syst Engn Dept Muscat Oman

A new near-optimum detection scheme for asynchronous wireless relay networks is proposed to cancel the interference component at the destination node caused by timing misalignment from the relay nodes. The detection complexity at the destination node as compared with a previous sub-optimum detection scheme is reduced. Closed-loop extended orthogonal space time block coding and outer convolutive coding are utilised to maximise end-to-end performance. A relay selection technique is also proposed in this study for two dual-antenna relay nodes to enhance the system performance by selecting the best links and the smallest time delay error among the relay nodes. Simulation results confirm that the proposed near-optimum detection scheme with relay selection is very effective at removing intersymbol interference at the destination node and achieving full cooperative diversity with unity data transmission rate between the relay nodes and the destination node.

关键词： relay networks (telecommunication) cooperative communication interference suppression intersymbol interference space-time block codes convolutional codes near-optimum detection scheme relay selection technique asynchronous wireless cooperative relay networks interference cancellation detection complexity closed-loop extended orthogonal space time block coding outer convolutive coding two dual-antenna relay nodes time delay error full cooperative diversity intersymbol interference

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