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2-Layer Interference Coordination Framework Based on graph coloring algorithm for a Cellular System With Distributed MU-MIMO

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2023年第3期72卷 3557-3568页

作者： Ge, Chang Xia, Sijie Chen, Qiang Adachi, Fumiyuki Tohoku Univ Sch Engn Sendai 9808579 Japan Tohoku Univ Int Res Inst Disaster Sci Sendai 9808572 Japan

In this study, a cellular system with a large-scale distributed multi-user multi-input multi-output (MU-MIMO) is considered, in which a large number of distributed antennas are deployed spatially over each base station coverage area (cell) and user clusters are formed in each cell to perform cluster-wise distributed MU-MIMO in parallel. In such a cellular system, the intercell and intracell interferences coexist and limit the link capacity. In this study, a 2-layer interference coordination (IC) framework that can effectively mitigate the two types of interferences simultaneously is proposed. In the 1st layer, the intercell IC is performed in a centralized manner by the non-real-time (non-RT) radio access network intelligent controller (RIC), and then in the 2nd layer, under the condition of the results in the 1st layer, intracell IC is done by each near-RT RICs in a decentralized manner. Furthermore, a restricted conditional graph coloring algorithm (RCGCA) suitable for this 2-layer IC framework is proposed. The proposed RCGCA is designed to be applied on a partial pre-colored graph, such that when it is applied in the 2-layer IC framework, it satisfies the requirement that the 2nd layer coloring must be applied under the condition of the pre-coloring results of the 1st layer. In addition, by restricting the total number of colors, the RCGCA can tradeoff between improving the capacity due to interference mitigation and degrading the capacity due to bandwidth partition, thereby maximizing the link capacity. We compare the link capacity achievable by the proposed 2-layer IC framework based on RCGCA with that achievable by the well-known fractional frequency reuse (FFR) scheme, no interference coordination case, fully centralized framework, and fully decentralized framework. Computer simulations confirm that our proposed 2-layer IC framework based on RCGCA can significantly improve the link capacity.

关键词： Interference Computer architecture Microprocessors Color Antenna arrays Intercell interference Bandwidth Interference coordination graph coloring algorithm distributed MU-MIMO O-RAN computational geometry ultra-dense cellular network

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An Improved Method in graph coloring algorithm for Interference Coordination in Cluster-wise Ultra-dense RAN

An Improved Method in Graph Coloring Algorithm for Interfere...

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International Symposium on Antennas and Propagation (ISAP)

作者： Ge, Chang Xia, Sijie Chen, Qiang Adachi, Fumiyuki Tohoku Univ Dept Commun Engn Sendai Miyagi Japan Tohoku Univ Res Org Elect Commun Sendai Miyagi Japan

ISBN: (纸本)9784885523267

In our previous study, we proposed a Restricted Color Number (RCN) algorithm based on graph coloring for interference coordination in cluster-wise distributed MU-MIMO in ultra-dense RAN. In this algorithm, we applied Delaunay Triangulation to help decide the interference relationship, which is different from the common-used threshold setting method. In this paper, we will discuss about the advantages of the Delaunay Triangulation method over the threshold method in graph coloring algorithm for interference coordination.

关键词： Ultra-dense RAN Cluster-wise MU-MIMO graph coloring algorithm Interference coordination Delaunay Triangulation

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A graph-coloring Based Time Slot Scheduling for STDMA Aeronautical Ad Hoc Networks 24

A Graph-Coloring Based Time Slot Scheduling for STDMA Aerona...

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3rd International Conference on Cryptography, Network Security and Communication Technology (CNSCT)

作者： Zhang, Ji Liu, Haitao Civil Aviat Univ China Tianjin Key Lab Adv Signal Proc Tianjin Peoples R China

ISBN: (纸本)9798400716959

Aiming at the problem of resource wastage in the Media Access Control (MAC) protocols for Spatial Reuse TDMA(STDMA) Aeronautical Ad Hoc Networks (AANET), a centralized scheduling method utilizing graph coloring is proposed. First, a protocol interference network model and a mathematical model for link-oriented scheduling are provided. Furthermore, it provides formulae for the average delay and slot reuse efficiency. Then, an STDMA scheduling method is proposed, which combines the scheduling problem with graph coloring algorithms. Finally, the simulation results demonstrate the correctness and timeliness of the method. It is proved that the method can significantly reduce average delay and increase slot reuse efficiency.

关键词： Ad Hoc Network Spatial reuse TDMA graph coloring algorithm average delay slot reuse efficiency

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An Innovational Jacobian-Split Newton-Krylov Method Combining the Advantages of the Jacobian-Free Newton-Krylov Method and the Finite Difference Jacobian-Based Newton-Krylov Method

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NUCLEAR SCIENCE AND ENGINEERING 2024年第10期198卷 1911-1934页

作者： Liu, Lixun Zhang, Han Peng, Xinru Dou, Qinrong Wu, Yingjie Guo, Jiong Li, Fu Tsinghua Univ Inst Nucl & New Energy Technol Collaborat Innovat Ctr Adv Nucl Energy Technol Key Lab Adv Reactor Engn & SafetyMinist Educ Beijing 100084 Peoples R China

The Jacobian-free Newton-Krylov (JFNK) method is a widely used and flexible numerical method for solving the neutronic/thermal-hydraulic coupling system. The main property of JFNK is that the Jacobian-vector product is evaluated approximately by finite difference, avoiding the forming and storage of Jacobian explicitly. However, the lack of an efficient preconditioner is a major bottleneck for the JFNK method, leading to poor convergence. The finite difference Jacobian-based Newton-Krylov (DJNK) method is another advanced numerical method, in which the Jacobian matrix is formed and stored explicitly. The DJNK method can provide a better preconditioner for Krylov iteration than JFNK. However, how to compute the Jacobian matrix efficiently and automatically is a key issue for the DJNK method. By fully utilizing the sparsity of the Jacobian matrix and graph coloring algorithm, the Jacobian can be computed efficiently. Unfortunately, when there are dense rows/blocks, a huge computational burden will emerge due to the lack of sparsity, resulting in the extremely poor efficiency of Jacobian computation. In this work, a Jacobian-split Newton-Krylov (JSNK) method is proposed to resolve the dense row/block problem by combining the advantages of JFNK and DJNK. The main feature of the JSNK method is to split the Jacobian matrix into sparse and dense parts. The sparse part of the Jacobian matrix is explicitly constructed using the graph coloring algorithm while for the dense part, the Jacobian-vector product is approximated by finite difference. The computational complexity of the JSNK method is analyzed and compared to the JFNK method and the DJNK method from theoretical and experimental aspects and under different meshes. A simplified two-dimensional (2-D) high-temperature gas-cooled reactor (HTR) model and a simplified 2-D pressurized water reactor model are utilized to demonstrate the superiority of the JSNK method. The numerical results show that the JSNK method successful

关键词： Newton-Krylov method sparse Jacobian graph coloring algorithm dense rows/blocks Jacobian-free Newton-Krylov method

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Learning Based on graph: A Joint Interference Coordination for Cluster-Wise Distributed MU-MIMO

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IEEE COMMUNICATIONS LETTERS 2023年第3期27卷 871-875页

作者： Ge, Chang Xia, Sijie Chen, Qiang Adachi, Fumiyuki Tohoku Univ Sch Engn Sendai 9808579 Japan Tohoku Univ Int Res Inst Disaster Sci Sendai 9808572 Japan

In a cellular system with distributed MU-MIMO, an application of cluster-wise distributed MU-MIMO reduces the computational complexity. However, both the intracell interference and the intercell interference are produced. Considering the scalability of the system, in this letter, we propose a fully decentralized interference coordination (IC) which jointly applies the graph coloring algorithm (GCA) and the deep reinforcement learning (DRL). Based on online training with consideration of the time-varying wireless environment, our proposed joint IC can adapt quickly to the changing environment. The simulation reveals that our proposed joint IC can significantly improve the capacity compared to the no IC case.

关键词： Integrated circuits Interference Intercell interference Integrated circuit modeling Color Training MIMO communication Interference coordination deep reinforcement learning graph coloring algorithm distributed MU-MIMO

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Multidimensional data visualization applying a variety-oriented scatterplot selection technique

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JOURNAL OF VISUALIZATION 2023年第1期26卷 199-210页

作者： Itoh, Takayuki Nakabayashi, Asuka Hagita, Mariko Ochanomizu Univ Bunkyo Ku 2-1-1 Otsuka Tokyo 1128610 Japan

Multidimensional data visualization is one of the most active research topics in information visualization since various information in our daily life forms multidimensional datasets. Scatterplot selection is an effective approach to represent essential portions of multidimensional data in a limited display space. Various metrics for evaluating scatterplots, such as scagnostics, have been applied to scatterplot selection. One of the open problems of this research topic is that various scatterplots cannot be selected if we simply apply one of the metrics. In other words, we may want to apply multiple metrics simultaneously in a balanced manner when we want to select a variety of scatterplots. This paper presents a new scatterplot selection technique that solves this problem. First, the technique calculates the scores of scatterplots with multiple metrics and then constructs a graph by connecting pairs of scatterplots that have similar scores. Next, it uses a graph coloring algorithm to assign different colors to scatterplots that have similar scores. We can extract a set of various scatterplots by selecting them that the specific same color is assigned. This paper introduces two case studies: the former study is with a retail transaction dataset while the latter study is with a design optimization dataset.

关键词： Multidimensional data visualization Scatterplot selection graph coloring algorithm Retail transaction data Design optimization data

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Research on global register allocation for code containing array-unit dual-usage register names

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2023年第19期35卷

作者： Hu, Yonghua Zhang, Xin Wang, Shuying Liang, Wei Li, Kuan-Ching Hunan Univ Sci & Technol Sch Comp Sci & Engn Xiangtan Peoples R China Hunan Key Lab Serv Comp & Novel Software Technol Xiangtan Peoples R China Hunan Univ Sci & Technol Sch Comp Sci & Engn Xiangtan 411201 Peoples R China

Array-unit dual-usage register is a kind of register resource that can be read or written as a whole or individually. It is mainly configured in processors with SIMD processing units and provides register-level speed data transfer between the scalar and vector processing units. To improve the efficiency of algorithms by using an array-unit dual-usage register, we investigate in this article the problem of adapting register allocation to code containing array-unit dual-usage register names. We propose a corresponding global register allocation method by combining the allocation of regular registers with array-unit dual-usage register, ensuring that the names of array-unit dual-usage register can be used in the input code of register allocation. Moreover, we present the processing framework of this method and the specific algorithms of some related vital aspects and demonstrate the working principles of the algorithms by an example. Experimental studies were conducted on a platform based on the FT-M7002 DSP core, and showing that our register allocation method can effectively handle codes containing array-unit dual-usage register names and support relevant application algorithms to improve their data transfer scheme. For some typical algorithms with input matrix, substantial performance improvements of twofold or higher are achieved.

关键词： compilation technology global register allocation graph coloring algorithm VLIW

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An Approach for Data Rate Maximization and Interference Mitigation in Massive MIMO Communication Systems Using SRPWGC-PD algorithm

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WIRELESS PERSONAL COMMUNICATIONS 2020年第1期115卷 499-525页

作者： Poddar, Jaitashri Subhashini, K. R. Natl Inst Technol Rourkela Dept Elect Engn Rourkela India

Increasing usage of wireless communication systems and demand for higher data speed is appealing newer generations of cellular communication systems to provide higher data rate along with a reliable system, i.e. system which is free from interference. 5G Communication systems are believed to provide at least ten times betterment in area throughput, i.e. data rate by increasing the spectral efficiency. Massive MIMO (multiple-input multiple-output) is a key 5G technology that uses massive antenna arrays to provide a very high beamforming gain and spatial multiplexing of users and hence increases the spectral and energy efficiency. However, although Massive MIMO suppresses intra-cell interference and uncorrelated noise to a significant amount, it cannot mitigate the Pilot Contamination (PC) which is caused by reusing the same set of pilot signals in adjacent cells. In this paper, a new Pilot Decontamination (PD) technique, named as Softly Reused Pilot Weighted graph coloring-based Pilot Decontamination (SRPWGC-PD) has been introduced. In the proposed scheme, a scheme named soft pilot reusing is applied to separate the users in cells into two (inner and outer) zones, and then outer-zone users are allocated with orthogonal pilots;whereas a special pilot allocation scheme named weighted graph coloring algorithm is applied to the inner zone users to make generated PC as less as possible. Simulation and numerical analysis provide an insight that the proposed scheme outperforms in most of the performance indices, when compared to the existing schemes reported in the literature.

关键词： Massive MIMO Channel State Information (CSI) Pilot Contamination(PC) Pilot Contamination Severity (PCS) Soft Pilot Reuse (SPR) graph coloring algorithm Edge Weighted Interference graph (EWIG)

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Resource efficiency improved approach for shared path protection in EONs

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PHOTONIC NETWORK COMMUNICATIONS 2017年第1期33卷 19-25页

作者： Liu, Huanlin Li, Ruiyan Chen, Yong Wang, Xin Chongqing Univ Posts & Telecom CQUPT Sch Commun & Informat Engn Key Lab Opt Commun & Network Chongwei Rd 2 Chongqing 400065 Peoples R China

For improving the resource efficiency of dynamic shared path protection in elastic optical networks, a survivable RSA (SRSA)-based heuristic algorithm is proposed in the paper. In SRSA, an adaptive adjustment link cost function is devised to effectively select working and protection paths. The cost function sufficiently considers available spectrum resources and the length of light paths for both working and protection paths. In order to achieve high resource efficiency, a spectrum allocation strategy named minimal cost stable set is proposed to allocate spectrum for protection paths with respect to the resource efficiency in the link cost function. And the graph coloring algorithm is introduced to select the shared protection path with the highest resource efficiency for the request. Compared with the shared path protection and dynamic load balancing shared path protection, simulation results show that the proposed SRSA decreases bandwidth blocking probability and achieves high resource efficiency.

关键词： EONs Shared path protection Spectrum allocation Minimal cost stable set graph coloring algorithm

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NP-Hard Task Schedules and Methods of Its Decision 11

NP-Hard Task Schedules and Methods of Its Decision

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11th IEEE International Conference on Application of Information and Communication Technologies (AICT)

作者： Diveev, A., I Bobr, O., V RUDN Univ Peoples Friendship Univ Russia Russian Acad Sci Fed Res Ctr Comp Sci & Control Moscow Russia RUDN Univ Peoples Friendship Univ Russia Moscow Russia

ISBN: (纸本)9781538605011

Methods of solving the problem of the schedule problem are examined, the advantages and disadvantages of these methods are identified, the formulation of the problem and modified genetic algorithm are given, which solutions with small variations of basic solution finds the optimal solution. The result of computational experiment is also given.

关键词： University scheduling graph coloring algorithm integer programming simulated annealing method simulation genetic algorithm

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