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Joint User Scheduling, Base Station Clustering, and Beamforming Design Based on Deep Unfolding Technique

IEEE TRANSACTIONS ON COMMUNICATIONS 2023年第10期71卷 5831-5845页

作者： Xu, Chunmei Jia, Yuanqi He, Shiwen Huang, Yongming Niyato, Dusit Southeast Univ Sch Informat Sci & Engn Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 210096 Peoples R China Cent South Univ Sch Comp Sci & Engn Changsha 410083 Peoples R China Nanyang Technol Univ Sch Comp Sci & Engn Singapore 639798 Singapore

In this paper, we investigate joint user (UE) scheduling, base station (BS) clustering and beamforming design in a dense network. To reduce the computation burden, we propose a deep unfolding UE scheduling, BS clustering and beamforming (DU-USBCB) method based on the iterative weighted minimum mean square error (WMMSE) algorithm, where the UE scheduling and BS clustering are represented by the group sparsity of the transmit beamforming vectors. The proposed DU-USBCB neural network layer comprises receive coefficient, weight and transmit beamforming vector modules, the former two of which have closed-form expressions. For the third module, the group sparse transmit beamforming vectors are obtained by multiple steps of projected gradient descent and nonlinear sparsification, where the step-sizes are learned through unsupervised learning. We also propose a distributed UE selection (DUS) algorithm, which helps reduce the computation workload. Simulation results verify the effectiveness of the proposed DU-USBCB and DUS methods. The learned step-sizes are directly applied in the testing scenarios with different numbers of UEs, BSs and antennas as well as incomplete channel state information. Besides, our proposed methods can achieve comparable performance but with about 53% and 89% computation reduction compared to the RSRP-WMMSE and SWMMSE methods respectively.

关键词： Array signal processing Processor scheduling Wireless communication Optimal scheduling Backhaul networks Clustering algorithms computational complexity Cross-layer design user scheduling base station clustering beamforming design deep unfolding

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Unbounded parallel-batch scheduling with drop-line tasks

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JOURNAL OF SCHEDULING 2019年第4期22卷 449-463页

作者： Gao, Yuan Yuan, Jinjiang Wei, Zhigang Zhengzhou Univ Sch Math & Stat Zhengzhou 450001 Henan Peoples R China Zhengzhou XindaJiean Informat Technol Co Ltd Zhengzhou 450001 Henan Peoples R China

In this paper, we study unbounded parallel-batch scheduling with drop-line tasks to minimize a regular objective function, where by drop-line tasks we mean that the completion time of each task (job) is equal to the sum of the starting time of the batch containing the task and the processing time of the task. In the problems considered in this paper, we assume that the tasks have individual release dates and the general regular objective function to be minimized is either of the sum-form or of the max-form. We then study the computational complexity of these problems on an unbounded parallel-batch processor. We show that (i) the problems are binary NP-hard and are solvable in pseudo-polynomial times, and (ii) when the number of processing times or release dates is a constant, the problems are solvable in polynomial times. We also point out some consequences of approximation algorithms.

关键词： Parallel-batch scheduling Drop-line tasks Release dates computational complexity

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Multivariable optimisation approach for power allocation in OFDM-DCSK system

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IET COMMUNICATIONS 2019年第13期13卷 1869-1876页

作者： Mobini, Majid Zahabi, M. Reza Babol Noshirvani Univ Technol Dept Elect Engn Babol Sar Iran

This study proposes some multivariable approaches for power allocation in orthogonal frequency multiple access-based differential chaos shift keying (OFDM-DCSK) system. The objective is to minimise the overall bit error rate (BER) under the total transmission power limit. There is some literature focusing on the power allocation for OFDM-DCSK systems, but all of them have only addressed the case where the power allocated to the reference subcarrier is assumed to be equal to one to simplify the problem to a single-variable optimisation problem. In this study, the authors simultaneously take the reference and data-bearing subcarriers power into consideration. They formulate a multivariable optimisation problem and solve it using Lagrange relaxation to derive a closed form solution. As the main contribution, the problem is converted to a cubic equation which is solved theoretically. Since the equation is non-convex, they solve it again using a genetic algorithm (GA)-based method for additive white Gaussian noise channel as a case study. The heuristic algorithm validates the theoretical approach. As another conclusion, the simulation results indicate that both of the proposed approaches outperform algorithms relaxing the reference power in terms of the BER performance, but the analytical solution leads to less time complexity in comparison with the GA-based method.

关键词： genetic algorithms OFDM modulation error statistics AWGN channels chaotic communication computational complexity power allocation OFDM-DCSK system bit error rate total transmission power limit reference subcarrier single-variable optimisation problem data-bearing subcarriers power multivariable optimisation problem reference power multivariable optimisation approach orthogonal frequency multiple access genetic algorithm cubic equation additive white Gaussian noise channel differential chaos shift keying

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ON THE PROBABILISTIC DEGREES OF SYMMETRIC BOOLEAN FUNCTIONS

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SIAM JOURNAL ON DISCRETE MATHEMATICS 2021年第3期35卷 2070-2092页

作者： Srinivasan, Srikanth Tripathi, Utkarsh Venkitesh, S. Indian Inst Technol Dept Math Bombay Maharashtra India

The probabilistic degree of a Boolean function f : {0, 1}(n) -> {0, 1} is defined to be the smallest d such that there is a random polynomial P of degree at most d that agrees with f at each point with high probability. Introduced by Razborov [Mat. Zametki, 41 (1987), pp. 598-607], upper and lower bounds on probabilistic degrees of Boolean functions-specifically symmetric Boolean functions-have been used to prove explicit lower bounds, design pseudorandom generators, and devise algorithms for combinatorial problems. In this paper, we characterize the probabilistic degrees of all symmetric Boolean functions up to polylogarithmic factors over all fields of fixed characteristic (positive or zero).

关键词： probabilistic degree symmetric Boolean function computational complexity

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Graphs with maximal induced matchings of the same size

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DISCRETE APPLIED MATHEMATICS 2017年第Part1期216卷 15-28页

作者： Baptiste, Philippe Kovalyov, Mikhail Y. Orlovich, Yury L. Werner, Frank Zverovich, Igor E. Ecole Polytech Lab Informat CNRS LIX F-91128 Palaiseau France Natl Acad Sci Belarus United Inst Informat Problems 6 Surganova Str Minsk 220012 BELARUS Belarusian State Univ Fac Appl Math & Comp Sci Dept Discrete Math & Algorithm Nezavisimosti Ave 4 Minsk 220030 BELARUS Otto Von Guericke Univ Inst Math Optimizat Univ Pl 2 D-39106 Magdeburg Germany Belarusian State Univ Fac Mech & Math Dept Math Cybernet Nezavisimosti Ave 4 Minsk 220030 BELARUS

A graph is well-indumatched if all its maximal induced matchings are of the same size. We first prove that recognizing whether a graph is well-indumatched is a co-NP-complete problem even for (2P(5), K-1,K-5)-free graphs. We then show that decision problems INDEPENDENT DOMINATING SET, INDEPENDENT SET, and DOMINATING SET are NP-complete for the class of well-indumatched graphs. We also show that this class is a co-indumatching hereditary class, i.e., it is closed under deleting the end-vertices of an induced matching along with their neighborhoods, and we characterize well-indumatched graphs in terms of forbidden co-indumatching subgraphs. We prove that recognizing a co-indumatching subgraph is an NP-complete problem. We introduce a perfectly well-indumatched graph, in which every induced subgraph is well-indumatched, and characterize the class of these graphs in terms of forbidden induced subgraphs. Finally, we show that the weighted versions of problems INDEPENDENT DOMINATING SET and INDEPENDENT SET can be solved in polynomial time for perfectly well-indumatched graphs, but problem DOMINATING SET is NP-complete. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Induced matching Well-covered graph Optimization problem computational complexity Forbidden induced subgraph

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Implementing confidential transactions with lattice techniques

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IET INFORMATION SECURITY 2020年第1期14卷 30-38页

作者： Zhang, Huang Zhang, Fangguo Wei, Baodian Du, Yusong Sun Yat Sen Univ Sch Data & Comp Sci Guangzhou Guangdong Peoples R China Guangdong Key Lab Informat Secur Guangzhou Guangdong Peoples R China

The notion of confidential transactions plays a central role in ensuring the confidentiality of transaction amounts in a block-chain-based cryptocurrency. Past researches have confirmed that the access policy of transaction amounts influences the anonymity of a cryptocurrency. Most of the current techniques of confidential transactions are based on the discrete logarithm problem. Because of the threats from quantum algorithms, clients are eager to enjoy security guarantees in a post-quantum scenario. Lattices are an ideal source of hardness, due to its exclusive worst-case to the average-case phenomenon. Nevertheless, the distinctions between the discrete logarithm problem and lattice problems build an obstacle in the way of borrowing the ideas from the former to the latter directly. In this study, inspired by the notion of commitments to polynomials and zero-knowledge arguments of knowledge for the inhomogeneous short integer solution problem, the authors give an approach to implement confidential transactions using lattice techniques.

关键词： search problems quantum cryptography computational complexity telecommunication security digital signatures cryptography confidential transactions lattice techniques confidentiality transaction amounts block-chain-based cryptocurrency discrete logarithm problem lattice problems

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Low-complexity Decision Feedback Equalization for Single-Carrier Massive MIMO Systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2024年第11期73卷 17316-17330页

作者： Zhang, Xiaohui Xing, Ling Wu, Honghai Ji, Baofeng Zhang, Gaoyuan Henan Univ Sci & Technol Sch Informat Engn Luoyang 471023 Peoples R China

Decision feedback equalization (DFE) has demonstrated its potential to achieve near-optimal performance in signal detection within single-carrier massive MIMO systems. However, matrix-inversion-based DFE schemes are not suitable for massive MIMO systems due to their prohibitively high computational complexity. In this paper, we investigate frequency domain DFE for signal detection in single-carrier massive MIMO systems with the goal of reducing computational complexity for practical applications. We propose a low-complexity implicit DFE scheme for single-carrier massive MIMO systems, which mitigates inter-stream and inter-symbol interference by leveraging the Neumann series (NS) expansion for matrix inversion approximation (MIA). The proposed scheme performs DFE implicitly by recursively computing forward/feedback signals using the NS expansion, thereby avoiding computationally intensive matrix inversions and forward/feedback filters calculation. Simulation and analysis results indicate that, compared to matrix-inversion-based DFE schemes, the proposed implicit DFE scheme can significantly reduce computational complexity while achieving similar performance in single-carrier massive MIMO systems. Moreover, it outperforms existing low-complexity detection methods under stringent channel conditions while maintaining similar or even lower complexity.

关键词： Decision feedback equalizers Massive MIMO computational complexity Frequency-domain analysis Filters Signal detection Loading Single-carrier massive MIMO decision feedback equalization low-complexity signal detection frequency domain equalization

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Joint range and velocity estimation for orthogonal frequency division multiplexing-based high-speed integrated radar and communications system

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IET COMMUNICATIONS 2022年第9期16卷 1005-1019页

作者： Wang, Xiaojiang Zhang, Zhenkai Jiangsu Univ Sci & Technol Ocean Coll Zhenjiang 212003 Jiangsu Peoples R China

The integrated radar and communications (IRC) waveform can simultaneously estimate the range and velocity of other targets while communicating with other facilities. In high-speed scenarios, the IRC echo signal based on orthogonal frequency division multiplexing (OFDM) needs to consider the intra-symbol and inter-subcarrier Doppler effects. This paper first builds a receiving model of the integrated echo signal by including the intra-symbol and inter-subcarrier Doppler effects. On this basis, we propose a two-step joint range and velocity estimation method, where rough estimation is performed by an improved estimating the signal parameters via the rotational invariance technique (ESPRIT), and a least-square weighted (LSW) method is applied for fine estimation. The Cramer-Rao lower bound (CRLB) of the receiving model is also provided, and the computational complexity of the proposed method is analyzed. Simulation results demonstrate the superiority of the proposed method.

关键词： Doppler effect radar applications receiving model intrasymbol Doppler effects. least-square weighted method signal parameters OFDM modulation integrated echo signal direction-of-arrival estimation joint range and velocity estimation method computational complexity IRC echo signal based on orthogonal frequency division multiplexing high-speed integrated radar and communications system parameter estimation intersubcarrier Doppler effects

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Reed-Solomon Coding Algorithms Based on Reed-Muller Transform for Any Number of Parities

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IEEE TRANSACTIONS ON COMPUTERS 2023年第9期72卷 2677-2688页

作者： Yu, Leilei Lin, Sian-Jheng Hou, Hanxu Li, Zhengrui Univ Elect Sci & Technol China Shenzhen Inst Adv Study Chengdu 610056 Peoples R China Huawei Technol Co Ltd Cent Res Inst Theory Lab 2012 Labs Hong Kong Peoples R China Dongguan Univ Technol Sch Elect Engn & Intelligentizat Dongguan 523820 Peoples R China Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Peoples R China

Based on the Reed-Muller (RM) transform, this paper proposes a Reed-Solomon (RS) encoding/erasure decoding algorithm for any number of parities. Specifically, we first generalize the previous RM-based syndrome calculation, which allows only up to seven parities, to support any number of parities. Then we propose a general encoding/erasure decoding algorithm. The proposed encoding algorithm eliminates the operations in solving linear equations, and this improves the computational efficiency of existing RM-based RS algorithms. In terms of erasure decoding, this paper employs the generalized RM-based syndrome calculation and lower-upper (LU) decomposition to accelerate the computational efficiency. Analysis shows that the proposed encoding/erasure decoding algorithm approaches the complexity of [lg T] + 1XORs per data bit with N increasing, where T and N denote the number of parities and codeword length respectively. To highlight the advantage of the proposed RM-based algorithms, the implementations with Single Instruction Multiple Data (SIMD) technology are provided. Simulation results showthat the proposed algorithms are competitive, as compared with other cutting-edge implementations.

关键词： Reed-Solomon code Vandermonde matrix Reed-Muller transform storage erasure codes computational complexity

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Practical linear precoder design for finite alphabet multiple-input multiple-output orthogonal frequency division multiplexing with experiment validation

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IET COMMUNICATIONS 2013年第9期7卷 836-847页

作者： Zheng, Yahong Rosa Wang, Mingxi Zeng, Weiliang Xiao, Chengshan Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA

A low complexity precoding method is proposed for practical multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. Based on the two-step optimal precoder design algorithm that maximises the lower bound of the mutual information with finite-alphabet inputs, the proposed method simplifies the precoder design by fixing the right singular vectors of the precoder matrix, eliminating the iterative optimisation between the two steps, and discretising the search space of the power allocation vector. For a 4 x 4 channel, the computational complexity of the proposed precoder design is reduced to 3 and 6% of that required by the original two-step algorithm with quadrature phase shift keying (QPSK) and 8 phase-shift keying (8PSK), respectively. The proposed method achieves nearly the same mutual information as the two-step iterative algorithm for a large range of signal-to-noise ratio (SNR) region, especially for large MIMO size and/or high constellation systems. The proposed precoding design method is applied to a 2 x 2 MIMO-OFDM system with 2048 subcarriers by designing 1024 precoders for extended channel matrices of size 4 x 4. A transceiver test bed implements these precoding matrices in comparison with other existing precoding schemes. Indoor experiments are conducted for fixed-platform non-line-of-sight channels, and the data processing results show that the proposed precoding method achieves the lowest bit error rate compared with maximum diversity, classic water-filling and channel diagonalisation methods.

关键词： channel coding codecs computational complexity indoor radio iterative methods linear codes MIMO communication multiplexing OFDM modulation optimisation phase shift keying precoding radio transceivers transceivers channel diagonalisation methods water-filling methods maximum diversity bit error rate precoding method data processing fixed-platform nonline-of-sight channels indoor experiments precoding matrices transceiver test bed extended channel matrices MIMO-OFDM system MIMO size SNR region 8PSK QPSK quadrature phase shift keying two-step algorithm computational complexity precoder matrix finite-alphabet inputs two-step optimal precoder design algorithm MIMO OFDM systems low complexity precoding method frequency division multiplexing experiment validation finite alphabet multiple-input multiple-output orthogonal linear precoder design

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