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Proceedings of the 23rd International Conference on Autonomous Agents and Multiagent Systems

作者： Yashovardhan S. Chati Ramasubramanian Suriyanarayanan Arunchandar Vasan Tata Consultancy Services Research Pune India Tata Consultancy Services Research Chennai India

ISBN: (纸本)9798400704864

Flight delays can significantly affect airline operations. Airlines use inline recovery actions (e.g., speeding up aircraft cleaning) to mitigate the effect of flight delays. Inline (or tactical) recovery for disruptions mostly relies on human expertise that is locally optimal (e.g., at an airport-level). Because an airline is a complex and stochastic network of dependencies, a locally optimal action may be globally sub-optimal. Considering global effects for inline recovery is computationally challenging with conventional algorithmic approaches for optimization. We complement existing approaches with Stochastic Minplus with State (SMS), a novel agent-based approach for inline recovery. SMS generalizes message passing algorithms for a state-dependent stochastic airline network with resource constraints. We evaluate our approach on a real-world airline network with around 4,000 flights per day for two regimes with 1) normal delays, and 2) interrupted operations. As baselines, we use approaches based on greedy local optimality, integer programming (IP), and constraint programming (CP). Our evaluation shows that: 1) a globally informed SMS improves over greedy locally optimal approach by 24.7% in quality, 2) SMS achieves solutions that are better by 14.1% (10.6%) in quality and 7x (9x) in computation time over IP (CP) with timeout, and 3) SMS achieves solutions within 5% of the optimal solution for simpler problem instances.

关键词： airline operations inline optimization irregular operations recovery message passing algorithm

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On the estimation of percolation thresholds for real networks

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CHAOS SOLITONS & FRACTALS 2022年 158卷

作者： Rong, Qingnan Zhang, Jun Sun, Xiaoqian Wandelt, Sebastian Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Adv Res Inst Multidisciplinary Sci Beijing Inst Technol Beijing 100081 Peoples R China

The percolation threshold is the critical point at which a giant connected component emerges for the first time in the percolation process. Its theoretical estimation has recently gathered much attention, especially for real networks with complicated structures. However, the theoretical methods so far mainly provide lower bounds of the percolation threshold with non-negligible errors. In this paper, we first generalize the existing message passing algorithm by considering the independence of variables in iteration equations. We then give the exact implicit expressions of the site and bond percolation thresholds based on the correction delta s (b) . The experimental results show that the correction is strongly related to network structural properties so that we can predict it by the gradient boosting regression model. Finally, we take the predicted correction delta s (b) to our theoretical framework and show that our estimates of site and bond percolation thresholds on 209 real networks are more accurate than those of the state-of-the-art methods.

关键词： Percolation threshold message passing algorithm Correction Regression model

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Adaptive Resource Allocation Based on Factor Graphs in Non-Orthogonal Multiple Access 24

Adaptive Resource Allocation Based on Factor Graphs in Non-O...

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24th International Symposium on Wireless Personal Multimedia Communication (WPMC) - Paving the Way for Digital and Wireless Transformation

作者： Yamagami, Taichi Denno, Satoshi Hou, Yafei Okayama Univ Grad Sch Nat Sci & Technol Okayama Japan

ISBN: (纸本)9781665427609

In this paper, we propose a non-orthogonal multiple access with adaptive resource allocation based on factor graphs. The proposed non-orthogonal multiple access assigns multiple frequency resources for each device to send their packet. Even if the number of the devices is more than the frequency resources, the proposed non-orthogonal access allows all the devices to transmit their packets simultaneously for high capacity massive machine type communication (mMTC). Furthermore, this paper proposes adaptive resource allocation based on factor graphs that adaptively allocates the frequency resources to the devices for improvement of the transmission performances. This paper proposes two allocation criteria for the proposed adaptive allocation. This paper shows that the proposed non-orthogonal multiple access achieves superior transmission performance in 4-path Rayleigh fading channel with overloading ratio of 1.5, even without the adaptive resource allocation. The adaptive resource allocation enables the proposed non-orthogonal access to attain a gain of about 5 dB at the BER of 10(-4).

关键词： Non-Orthogonal Multiple Access message passing algorithm Factor Graphs Log-Likelihood Ratio

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Link-level Performance Evaluations of Sparse Code Multiple Access for PC5-based Cellular-V2X with Heterogeneous Channel Estimation Errors 93

Link-level Performance Evaluations of Sparse Code Multiple A...

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IEEE 93rd Vehicular Technology Conference (VTC-Spring)

作者： Hirai, Takeshi Spasojevic, Predrag Nagoya Univ Grad Sch Informat Nagoya Aichi Japan Rutgers State Univ Wireless Informat Network Lab New Brunswick NJ USA

ISBN: (纸本)9781728189642

This paper presents the link-level performance of sparse code multiple access (SCMA) for PC5-based cellular-vehicle-to-everything (C-V2X) with different channel estimation errors (CEEs) for every user, called a heterogeneous CEE, due to user mobility. Such a CEE may cause decoding error propagation for users experiencing no CEEs through the message passing algorithm used in SCMA due to the non-orthogonality. First, we analyze the error propagation in a basic heterogeneous CEE model, in which a specific user provides a Gaussian CEE. Our analysis shows that the error propagation depends on the edge connectivity with the specific user on the Factor graph;its directly connected users' signals show worse decoding performance than its indirectly connected users' signals. Next, we evaluate the link-level performance of each user in the heterogeneous CEE model to confirm the impacts of the error propagation. Our evaluation results demonstrated that the error propagation degraded 8.1 times worse bit error rate performance of the indirectly connected user at a CEE variance of 0.1 than no CEE for all users. Through our simulation results, this paper highlights that error propagation is a potential challenge for SCMA in PC5-based V2X.

关键词： PC5-based C-V2X sparse code multiple access message passing algorithm error propagation channel estimation errors

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Iterative Gaussian-Approximated message passing Receiver for MIMO-SCMA System

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2019年第3期13卷 753-765页

作者： Dai, Jincheng Niu, Kai Lin, Jiaru Beijing Univ Posts & Telecommun Minist Educ Key Lab Universal Wireless Commun Beijing 100876 Peoples R China

Sparse code multiple access (SCMA) and multiple-input multiple-output (MIMO) are viewed as two key techniques to address the high spectral efficiency requirements for the 5G wireless system. However, the complexity of standard message passing algorithm (MPA) for the MIMO-SCMA detection yet increases exponentially with the degree of resource nodes d(f) and the number of transmit antennas N-t. In this paper, to tackle this problem, we design two types of low-complexity MPA over the MIMO-SCMA extended factor graph to perform joint multiuser and MIMO detection. The main idea of the proposed algorithms is approximating the discrete interferences at function nodes (FNs) as the continuous Gaussian messages so that the traversal enumeration at the FN update can be avoided. The symbol level Gaussian approximated MPA (GAMPA-S) updates the symbol likelihood during the detector's inner-loop iterations which is similar to the standard MPA, and this algorithm is compatible to any SCMA codebooks. The bit level Gaussian approximated MPA (GAMPA-B) updates the bit likelihood ratio which shows lower complexity compared to the GAMPA-S. However, the GAMPA-B requires that the SCMA code books can satisfy the bit significance expansion property. In the receiver, the proposed detectors are combined with users' decoders to form the outer-loop structure, in which a critical clamping factor (DF) is designed to compress the amplitude of extrinsic information exchanged between the detector and decoders. The extrinsic information transform chart is introduced to optimize the DF. Consequently, the complexity of the proposed receiver just increases linearly with d(f) and N-t while its performance is comparable or even better than the conventional receiver. This would effectively boost the practical use of MIMO-SCMA techniques.

关键词： MIMO-SCMA message passing algorithm Gaussian approximation complexity reduction damping factor

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Edgewise Serial message passing Detection of Uplink SCMA Systems for Better User Fairness and Faster Convergence Rate

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IEEE WIRELESS COMMUNICATIONS LETTERS 2019年第4期8卷 1285-1288页

作者： Ma, Lei Tong, Sheng Zheng, Huijuan Bai, Baoming Dai, Xiaoming Xidian Univ Xian 710071 Shaanxi Peoples R China Xian Univ Posts & Telecommun Xian 710065 Shaanxi Peoples R China Univ Sci & Technol Beijing Beijing 100107 Peoples R China

Sparse code multiple access (SCMA) is a promising non-orthogonal multiple access (NOMA) scheme proposed for the upcoming 5G system. Multiuser detection using the message passing algorithm (MPA) with parallel and serial schedules has been considered for SCMA systems. Although serial schedules provide faster convergence rates compared to the parallel schedule, the existing user-wise serial MPA detectors are found to have a user unfairness phenomenon in terms of BER performance, especially at small iteration numbers. To address this issue and to further accelerate the convergence rate, this letter proposes a class of edgewise serial schedules (ESSs). Simulations results demonstrate that optimized ESSs can not only improve the user fairness significantly but also achieve faster convergence rate compared to user-wise serial schedules.

关键词： Sparse code multiple access (SCMA) multiuser detection message passing algorithm message passing schedule

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Spatial Modulated Multicarrier Sparse Code-Division Multiple Access

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2020年第1期19卷 610-623页

作者： Liu, Yusha Yang, Lie-Liang Xiao, Pei Haas, Harald Hanzo, Lajos Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England Univ Surrey Fac Engn & Phys Sci Home 5G Innovat Ctr 5GIC Inst Commun Syst Guildford GU2 7XH Surrey England Univ Edinburgh Inst Digital Commun IDCOM Edinburgh EH9 3JL Midlothian Scotland

This paper proposes a novel spatial-modulated multicarrier sparse code-division multiple access (SM/MC-SCDMA) system for achieving massive connectivity in device-centric wireless communications. In our SM/MC-SCDMA system, the advantages of both MC signalling and SM are amalgamated to conceive a low-complexity transceiver. Sparse frequency-domain spreading is utilized to mitigate the peak-to-average power ratio (PAPR) of MC signalling, as well as to facilitate low-complexity detection using the message passing algorithm. We then analyze the single-user bit error rate performance of SM/MC-SCDMA systems communicating over frequency-selective fading channels. Furthermore, the performance of SM/MC-SCDMA systems is evaluated based on both Monte-Carlo simulations and analytical results. We demonstrate that our low-complexity SM/MC-SCDMA transceivers are capable of achieving near-maximum likelihood (ML) performance even when the normalized user-load is as high as two, hence constituting a variable solution to support massive connectivity in device-centric wireless systems.

关键词： Multiaccess communication Peak to average power ratio Frequency-domain analysis Frequency-selective fading channels NOMA Transmitters Multicarrier CDMA sparse spreading spatial modulation maximum a posteriori detection message passing algorithm performance

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Low complexity receiver of sparse code multiple access based on dynamic trellis

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IET COMMUNICATIONS 2020年第9期14卷 1420-1427页

作者： Peng, Xiaohuan Pan, Zhipeng Lai, Ke Wen, Lei Lei, Jing Natl Univ Def Technol Coll Elect Sci Dept Commun Engn Rd Deya 109 Changsha Hunan Peoples R China

Sparse code multiple access (SCMA) is one of the non-orthogonal multiple access schemes to meet the demands of massive connection and high spectral efficiency in the 5G communications. Since the sparsity of the codebook, the message passing algorithm (MPA) can be utilised for multi-user detection. However, the high computational complexity of MPA hinders the practical application of SCMA. The extended Max-Log MPA (EML-MPA) and the channel-adaptive extended Max-Log MPA (CAD-EML-MPA) help to reduce the complexity of conventional Log-MPA with trellis representation. On this basis, the authors propose a dynamic trellis based MPA (DT-MPA) in this study. DT-MPA selects symbols dynamically according to a specific threshold tau in each iteration of MPA. The impact of the threshold on the complexity and convergence behaviour is analysed. Simulation results show that the DT-MPA with variable tau which is related to bit signal-to-noise can achieve better bit error rate performance and lower complexity than EML-MPA and CAD-EML-MPA.

关键词： multiuser detection error statistics multi-access systems message passing trellis codes 5G mobile communication communication complexity wireless channels iterative methods radio receivers message passing algorithm computational complexity SCMA schemes CAD-EML-MPA DT-MPA low complexity receiver sparse code multiple access schemes nonorthogonal multiple access schemes high spectral efficiency channel-adaptive extended max-log MPA 5G communications multiuser detection dynamic trellis based MPA bit error rate performance

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A Multi-Node Detection algorithm Based on Serial and Threshold in Intelligent Sensor Networks

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SENSORS 2020年第7期20卷 1960页

作者： Zhang, Guanghua Gu, Zonglin Zhao, Qiannan Ren, Jingqiu Han, Shuai Lu, Weidang Northeast Petr Univ Sch Elect Engn & Informat Daqing 163318 Peoples R China Harbin Inst Technol Commun Res Ctr Harbin 150080 Peoples R China Zhejiang Univ Technol Coll Informat Engn Hangzhou 310014 Peoples R China

With the continuous progress of science and technology, intelligent wireless sensor network (IWSN) communication has become indispensable in its role in production and life because of its convenient network settings and flexible use. However, with the widespread availability of intelligent wireless sensor networks, the use of many wireless sensor nodes constitutes a multi-node wireless communication system, which turns the accuracy and low complexity of multi-node detection in sensor networks into a problem. Although the traditional algorithm has excellent performance, it cannot give consideration to both accuracy and complexity. Therefore, a maximum logarithm message passing algorithm based on serial and threshold (S-T-Max-log-MPA) for multi-mode detection in IWSN is proposed in this paper. In this algorithm, the threshold is used to determine the necessary conditions of sensor node stability first, and then the sensor node information updating is integrated into the resource node information updating, so that the system can maintain good accuracy, performance, and change the situation of poor system accuracy at low threshold. Compared with the traditional algorithm, the proposed algorithm significantly changes the algorithm complexity reduction rate of the system multi-node detection. Simulation results show that the algorithm has a good balance between accuracy and complexity reduction rate.

关键词： intelligent sensor message passing algorithm threshold serial complexity

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On the Design of Near-Optimal Sparse Code Multiple Access Codebooks

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IEEE TRANSACTIONS ON COMMUNICATIONS 2020年第5期68卷 2950-2962页

作者： Chen, Yen-Ming Chen, Jian-Wei Natl Sun Yat Sen Univ Inst Commun Engn Kaohsiung 80424 Taiwan Natl Sun Yat Sen Univ Dept Elect Engn Kaohsiung 80424 Taiwan Realtek Semicond Corp Hsinchu 30076 Taiwan

Sparse code multiple access (SCMA) is one of the competitive non-orthogonal multiple access (NOMA) techniques for the next generation of communication systems. In this paper, a systematic construction procedure for the design of SCMA codebooks under various channel environments is proposed in order to achieve near-optimal designs, especially for cases which consider small-scale SCMA parameters. The procedure includes the rotation angle design, the construction of multi-dimensional codebooks, and the design of labelling rules. The detailed design criteria and the related properties are derived and investigated. A low-complexity construction algorithm is further proposed for the cases of fading channels. Numerical results show that the designed SCMA codebooks provide improvements in error performance for all of the considered channel conditions, when compared to the codebooks presented in the prior literature.

关键词： Fading channels Downlink Uplink NOMA Constellation diagram Systematics Sparse code multiple access (SCMA) non-orthogonal multiple access (NOMA) codebook design message passing algorithm

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