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China communications 2024年第3期21卷 230-246页

作者： Tong Minglei Li Song Han Wanjiang Wang Xiaoxiang School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China key Laboratory of universal wireless communications Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing 100876China School of Information and Control Engineering China University of Mining and TechnologyXuzhou 221116China School of Computer Science(National Pilot Software Engineering School) Beijing University of Posts and TelecommunicationsBeijing 100876China

Mobile edge computing(MEC)-enabled satellite-terrestrial networks(STNs)can provide Internet of Things(IoT)devices with global computing ***,the network state information is uncertain or *** deal with this situation,we investigate online learning-based offloading decision and resource allocation in MEC-enabled STNs in this *** problem of minimizing the average sum task completion delay of all IoT devices over all time periods is *** decompose this optimization problem into a task offloading decision problem and a computing resource allocation problem.A joint optimization scheme of offloading decision and resource allocation is then proposed,which consists of a task offloading decision algorithm based on the devices cooperation aided upper confidence bound(UCB)algorithm and a computing resource allocation algorithm based on the Lagrange multiplier *** results validate that the proposed scheme performs better than other baseline schemes.

关键词： computing resource allocation mobile edge computing satellite-terrestrial networks task offloading decision

Cooperative Distributed Beamforming Design for Multi-RIS Aided Cell-Free Systems

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ZTE communications 2024年第2期22卷 99-106页

作者： ZHU Yuting XU Zhiyu ZHANG Hongtao key Lab of universal wireless communications Ministry of Education of ChinaBeijing University of Posts and TelecommunicationsBeijing 100876China ZTE Corporation Shenzhen 518057China

Cell-free systems significantly improve network capacity by enabling joint user service without cell boundaries,eliminating intercell ***,to satisfy further capacity demands,it leads to high-cost problems of both hardware and power *** this paper,we investigate multiple reconfigurable intelligent surfaces(RISs)aided cell-free systems where RISs are introduced to improve spectrum efficiency in an energy-efficient *** overcome the centralized high complexity and avoid frequent information exchanges,a cooperative distributed beamforming design is proposed to maximize the weighted sum-rate *** particular,the alternating optimization method is utilized with the distributed closed-form solution of active beamforming being derived locally at access points,and phase shifts are obtained centrally based on the Riemannian conjugate gradient(RCG)manifold *** results verify the effectiveness of the proposed design whose performance is comparable to the centralized scheme and show great superiority of the RISs-aided system over the conventional cellular and cell-free system.

关键词： cell-free systems reconfigurable intelligent surface cooperative distributed beamforming Riemannian conjugate gradient

Multimodal fusion recognition for digital twin

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Digital communications and Networks 2024年第2期10卷 337-346页

作者： Tianzhe Zhou Xuguang Zhang Bing Kang Mingkai Chen key Laboratory of Broadband wireless Communication and Sensor Network Technology Ministry of EducationNanjing University of Posts and TelecommunicationsNanjing210003China

The digital twin is the concept of transcending reality,which is the reverse feedback from the real physical space to the virtual digital *** hold great prospects for this emerging *** order to realize the upgrading of the digital twin industrial chain,it is urgent to introduce more modalities,such as vision,haptics,hearing and smell,into the virtual digital space,which assists physical entities and virtual objects in creating a closer ***,perceptual understanding and object recognition have become an urgent hot topic in the digital *** surface material classification schemes often achieve recognition through machine learning or deep learning in a single modality,ignoring the complementarity between multiple *** order to overcome this dilemma,we propose a multimodal fusion network in our article that combines two modalities,visual and haptic,for surface material *** the one hand,the network makes full use of the potential correlations between multiple modalities to deeply mine the modal semantics and complete the data *** the other hand,the network is extensible and can be used as a universal architecture to include more *** show that the constructed multimodal fusion network can achieve 99.42%classification accuracy while reducing complexity.

关键词： Digital twin Multimodal fusion Object recognition Deep learning Transfer learning

Improving amplify-and-forward relay selection algorithm based on partial relay link

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The Journal of China Universities of Posts and Telecommunications 2010年第1期17卷 56-61页

作者： WANG Fei-fei LIU Yuan-an LIN Xiao-feng XIE Gang key labomty of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

This article addresses the design problem of selecting an appropriate relay in amplify-and-forward （AF） cooperative diversity systems. In this regard, this article focuses on relay selection based on partial channel knowledge only across the source and relay links. In particular, the two fundamental questions will be answered, that is, whether to cooperate and whom to cooperate with. Through answering these two questions, an improved relay selection strategy based on partial relay link, which emphasizes that cooperation happens when necessary, is proposed to aim at maximizing the average mutual information. Then a joint optimization, in terms of power allocation and relay selection, is employed to guarantee a robust performance for relay selection based on partial relay link. Optimum power is allocated between the source and the selected relay to maximize the output signal-to-noise （SNR） at the destination. Simulation results turn out that the improved scheme can achieve better performance than previous work and the robust performance can be guaranteed by employing joint optimization.

关键词： cooperative diversity amplify-and-forward relay relay selection average mutual information

Efficient caching strategy based on graph coloring for moving users in ultra dense networks

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 1-7页

作者： Hu Chengjia Li Xi Ji Hong Zhang Heli key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

Caching popular files in small-cell base stations(SBSs) is considered as a promising technique to meet the demand of ever growing mobile data traffic in ultra dense networks(UDNs). Considering the limited cache capacity and dense deployment of SBSs, how to support uninterrupted and successful caching downloading for moving users is still a challenging problem. In this paper, a graph-coloring-based caching(GCC) algorithm in UDN for moving user under limited SBS storage capacities is proposed. Firstly, considering there may be downloading interruption or even failure due to the random moving of users and small coverage of SBSs, graph coloring algorithm(GCA) is employed for grouping the SBS to cache fragments of several files. Then, the problem of how to conduct caching placement on SBSs is formulated aiming to maximize the amount of data downloaded from SBSs. Finally, an efficient heuristic solution is proposed to get an optimal result. Simulation results show that the algorithm performs better than other caching strategies in prior work, in terms of reducing both backhaul traffic and user download delay.

关键词： ultra dense network graph coloring caching moving user download delay

End-to-end energy-efficient resource allocation in device-to-device communication underlaying cellular networks

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The Journal of China Universities of Posts and Telecommunications 2015年第1期22卷 24-30页

作者： Xu Quansheng Ji Hong Li Xi Xiong Danni key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

A proposed resource allocation （RA） scheme is given to device-to-device （D2D） communication underlaying cellular networks from an end-to-end energy-efficient perspective, in which, the end-to-end energy consumptions were taken into account. Furthermore, to match the practical situations and maximize the energy-efficiency （EE）, the resource units （RUs） were used in a complete-shared pattern. Then the energy-efficient RA problem was formulated as a mixed integer and non-convex optimization problem, extremely difficult to be solved. To obtain a desirable solution with a reasonable computation cost, this problem was dealt with two steps. Step 1, the RU allocation policy was obtained via a greedy search method. Step 2, after obtaining the RU allocation, the power allocation strategy was developed through quantum-behaved particle swarm optimization （QPSO）. Finally, simulation was presented to validate the effectiveness of the proposed RA scheme.

关键词： energy-efficiency resource allocation D2D communication mixed integer and non-convex optimization problem

Iterative list decoding approach for Reed-Solomon codes

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 8-14,24页

作者： Zhang Zhijun Niu Kai Dong Chao key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

A novel adaptively iterative list decoding(ILD) approach using for Reed-Solomon(RS) codes was investigated. The proposed scheme is exploited to reduce the complexity of RS Chase algorithm(CA) via an iterative decoding attempt mode. In each decoding attempt process, a test pattern is generated by flipping the bits of the least reliable positions(LRPs) within the received hard-decision(HD) vector. The ILD algorithm continues until a test pattern is successfully decoded by the underlying Berlekamp-Massey algorithm(BMA) of RS codes. Flipping within the same bits, the ILD algorithm provides the same test pattern set as the conventional RS CA, thus there is no degradation in error-rate performance. Without decoding all test patterns, the ILD algorithm can simplify the decoding complexity by its early termination. Simulation results show that the average complexity of the ILD algorithm is much lower than that of the conventional RS CA(and is similar to that of BMA decoding) at high signal-to-noise ratio(SNR) region with no less to the RS CA decoding error-rate performance.

关键词： iterative decoding soft-decision decoding Reed-Solomon codes low-complexity decoding

Optimal transmission mode proportion for heterogeneous networks of cellular and device-to-device communications

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The Journal of China Universities of Posts and Telecommunications 2013年第4期20卷 21-27页

作者： LIU Zi-yang PENG Tao WANG Wen-bo key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

This paper discusses about the optimal mode allocation for the heterogeneous networks, in which the network can schedule users working in the device-to-device （D2D） mode or cellular mode. The D2D user is allowed to reuse the uplink resource of cellular system and the problem is formed as a sum-capacity optimization issue with outage constraints for both cellular and D2D links. The method for the optimal user proration is proved to be divided into three cases according to the total user density： when the total user density is small, the optimal proration trends to all users utilizing one mode; when the total user density is large, the optimal proration is all of users choosing D2D mode; and when the total user density situates in the between, there is a unique optimal transmission mode proportion for the hybrid networks to maximize its sumcapacity. The simulation results demonstrate the validity of the conclusions in the analysis part.

关键词： device-to-device mode proration sum-capacity optimization

Performance analysis of opportunistic amplify-and-forward two-way relaying in two-wave with diffuse power fading channels

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The Journal of China Universities of Posts and Telecommunications 2015年第2期22卷 7-14页

作者： Zhou Jia Wang Xiaoxiang Qi Yanyan key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

This paper considers cooperative amplify-and-forwards （AF） two-way relay networks （TWRNs） with opportunistic relay selection （ORS） in two-wave with diffuse power （TWDP） fading channels. To investigate the system performance, we first derive an easy-to-computer approximated expression for the exact outage probability to reduce computational cost. Furthermore, we presented compact expressions for the asymptotic outage probability and asymptotic symbol error rate, which characterizes two factors goveming the network performance at high signal-to-noise ratio （SNR） in terms of diversity order and coding gain. Additionally, based on the asymptotic outage probability, we determine the optimal power allocation solution between the relay and the sources to minimize the overall outage probability under the assumption that both the sources have identical transmit power. The correctness of the analysis is validated through Monte Carlo simulations. Our derived results can be applied to general operating scenarios with distinct TWDP fading parameters which encompass Rayleigh and Rician fading as special cases and arbitrary number of relays.

关键词： two-way relay opportunistic relay TWDP TWDP AF

Energy efficiency enhancement in heterogeneous networks:a joint resource allocation approach

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The Journal of China Universities of Posts and Telecommunications 2015年第4期22卷 74-80页

作者： Sun Yujing Wang Yongbin Li Yi key Laboratory of universal wireless communications Beijing University of Posts and Telecommunications

To support the drastic growth of wireless multimedia services and the requirements of ubiquitous access, numerous wireless infrastructures which consume enormous energy, such as macrocell, small cell, distributed antenna systems and wireless sensor networks, have been deployed. Under the background of environmental protection, improving the energy efficiency（EE） in wireless networks is becoming more and more important. In this paper, an EE enhancement scheme in heterogeneous networks（Het Nets） by using a joint resource allocation approach is proposed. The Het Nets consists of a mix of macrocell and small cells. Firstly, we model this strategic coexistence as a multi-agent system in which decentralized resource management inspired from Reinforcement Learning are devised. Secondly, a Q-learning based joint resource allocation algorithm is designed. Meanwhile, with the consideration of the time-varying channel characteristics, we take the long-term learning reward into account. At last, simulation results show that the proposed decentralized algorithm can approximate to centralized algorithm with low-complexity and obtain high spectral efficiency（SE） in the meantime.

关键词： heterogeneous networks energy efficiency reinforcement learning decentralized resource allocation joint resource allocation appr