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International Symposium on Networks, Computers and Communications (ISNCC)

作者： Liu, Yilun Zhu, Lidong Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu Sichuan Peoples R China

ISBN: (纸本)9781538637784

In a massive Low Earth Orbit(LEO) satellite network without inter-satellite links(ISLs), connection between source node and destination node can be established through satellite-ground links. Utilizing satellite network topology in time virtualization algorithm and assuming that the current traffic of satellite-ground links which is used as the value of the topology correlation matrix can be perceived, the network uses the Dijkstra algorithm to obtain the shortest path of the current total network traffic and thus implements load balancing of the constellation system. Due to the large number of satellites, the network topology is complex and time varying, it is difficult to find the optimal path in a short time, so a suboptimal routing algorithm based on network topology is proposed in this paper. The local network topology is obtained by using the positions of the source and destination gateway, and the number of satellites and gateways used to establish the correlation matrix of the Dijkstra algorithm is reduced. Through the simulation analysis, the average computational complexity of this algorithm is much lower than that of the global optimal routing algorithm, and the average propagation delay of routing is almost the same. When the network load is normal, the system performance is almost the same with the global optimal routing algorithm.

关键词： LEO satellite massive constellation topology routing algorithm suboptimal algorithm Dijkstra algorithm

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Optimal and suboptimal algorithms in set membership identification

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MATHEMATICAL AND COMPUTER MODELLING OF DYNAMICAL SYSTEMS 2005年第2期11卷 159-169页

作者： Kacewicz, B AGH Univ Sci & Technol Dept Appl Math PL-30059 Krakow Poland

We discuss in this paper optimality properties of identification algorithms in a set membership framework. We deal with restricted-complexity (conditional) identification, where approximations (models) to a possibly complex system are selected from a low dimensional space. We discuss the worst- and average-case settings. In the worst-case setting, we present results on optimality, or suboptimality, of algorithms based on computing the unconditional or conditional Chebyshev centres of an uncertainty set. In the average-case setting, we show that the optimal algorithm is given by the projection of the unconditional Chebyshev centre. We show explicit formulas for its average errors, allowing us to see the contribution of all problem parameters to the minimal error. We discuss the case of weighted average errors corresponding to non-uniform distributions over uncertainty sets, and show how the weights influence the minimal identification error.

关键词： identification worst-case setting average-case setting weights optimal algorithm suboptimal algorithm

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A new approximate cluster deletion algorithm for diamond-free graphs

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JOURNAL OF COMBINATORIAL OPTIMIZATION 2020年第2期39卷 385-411页

作者： Malek, Sabrine Naanaa, Wady Univ Sfax Fac Econ & Management Sfax Sfax Tunisia Univ Tunis El Manar Natl Engn Sch Tunis Tunis Tunisia

The cluster deletion problem (CD) asks for transforming a given graph into a disjoint union of cliques by removing as few edges as possible. CD is among the most studied combinatorial optimization problem and, for general graphs, it is NP-hard. In the present paper, we identify a new polynomially solvable CD subproblem. We specifically propose a two-phase polynomial-time algorithm that optimally solves CD on the class of (butterfly,diamond)-free graphs. For this latter class of graphs, our two-phase algorithm provides optimal solutions even for another clustering variant, namely, cluster editing. Then, we propose a 2-optimal CD algorithm dedicated to the super-class of diamond-free graphs. For this class, we also show that CD, when parameterised by the number of deleted edges, admits a quadratic-size kernel. Finally, we report the results of experiments carried out on numerous diamond-free graphs, showing the effectiveness of the proposed approximate algorithm in terms of solution quality.

关键词： Cluster deletion (CD) Polynomial algorithm (Butterfly diamond)-free graphs Maximal clique suboptimal algorithm Diamond-free graphs

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Spreading sequence estimation algorithms based on ML detector in DSSS communication systems

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IET SIGNAL PROCESSING 2018年第6期12卷 802-809页

作者： Mehboodi, Saeed Jamshidi, Ali Farhang, Mahmoud Shiraz Univ Sch Elect & Comp Engn Shiraz Iran

In this study, the authors address the spreading sequence estimation in direct-sequence spread-spectrum signals. At first, the maximum-likelihood (ML) estimator is derived. In order to alleviate the greater computational complexity of the ML estimator, an innovative algorithm based on the ML method is proposed. The authors' proposed algorithm uses an initial estimation with low complexity and low estimation accuracy as a result. In the second step, the estimation accuracy increases using the ML decision rule. They analyse their proposed algorithm and they derive an analytical approximation for the error probability of the proposed suboptimal algorithm. Simulation and analytical results show great performance and acceptable complexity of the proposed method.

关键词： code division multiple access spread spectrum communication maximum likelihood detection maximum likelihood estimation communication complexity probability spreading sequence estimation algorithm ML detector DSSS communication system direct-sequence spread-spectrum signal maximum-likelihood estimator ML estimator computational complexity ML decision rule error probability suboptimal algorithm

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Joint beamforming and power allocation for secure communication in cognitive radio networks

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IET COMMUNICATIONS 2016年第10期10卷 1156-1162页

作者： Chen, Tao Yuan, HuaQiang Zhao, TieZhu Zhang, ZuSheng Ao, Xin Dongguan Univ Technol Dept Comp Coll Dongguan Peoples R China

In this study, secure communication in cognitive radio networks is investigated. A cooperative jammer is utilised to transmit artificial noise for interfering with the eavesdropper. The authors' objective is to maximise the available secrecy rate of the secondary user (SU) under the interference power constraint at the primary user and the global transmit power constraint at the transmitters. In that case, beamforming vectors of the SU transmitter and the cooperative jammer, and power allocation between them need to be optimised. However, the optimisation problem is non-convex and hard to solve. In order to tackle it, two suboptimal algorithms are proposed: complete orthogonal projection and partial orthogonal projection. In these algorithms, the original optimisation problems are first decoupled into two sub-problems, which deal with the transmit beamforming vectors and power allocation, respectively. Then, the optimal solution is obtained by iteration alternately. Finally, simulation results verify the effectiveness of the proposed algorithms.

关键词： cognitive radio telecommunication security array signal processing cooperative communication concave programming radiofrequency interference joint beamforming-power allocation scheme secure communication cognitive radio networks cooperative jammer artificial noise eavesdropper available secrecy rate secondary user SU transmitter interference power constraint primary user global transmit power constraint beamforming vector nonconvex optimisation problem suboptimal algorithm complete orthogonal projection partial orthogonal projection transmit beamforming vector iteration

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Combination of Throughput-Optimal Scheduling and Network Utility Maximization in NOMA Systems With Flow-Level Dynamics

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2023年第11期72卷 14573-14588页

作者： Chen, Yunpei Zhu, Qi Guo, Caili Yuan, Yifei Feng, Chunyan Nanjing Univ Posts & Telecommun Engn Res Ctr Hlth Serv Syst Based Ubiquitous Wire Jiangsu Key Lab Wireless Commun Minist Educ Nanjing 210003 Peoples R China Beijing Univ Posts & Telecommun Sch Informat & Commun Engn Beijing Key Lab Network Syst Architecture & Conve Beijing 100876 Peoples R China China Mobile Res Inst Future Mobile Technol Lab Beijing 100053 Peoples R China

In wireless networks, the network queue stability (throughput-optimality) and the network utility maximization are two crucial tasks for network operators. Besides, new techniques of mobile communications, e.g. the non-orthogonal multiple access (NOMA), have emerged endlessly to meet coming challenges. In this article, we for the first time, investigate a downlink NOMA system with flow-level dynamics, where long-lived flows and short-lived flows exist simultaneously, and formulate an optimization problem of user selection and power allocation. We aim to maximize the network utility at each time slot and simultaneously guarantee the throughput-optimality, under the quality of service (QoS) constraints. Considering the practicability of algorithm, the suboptimal algorithm containing two stages, is proposed. And we analyze the complexity of proposed algorithm. In the performance evaluation, the benchmark algorithm is provided for comparison. And we take the energy efficiency (EE) as an example of the network utility and define the scheduling delay (SD). Simulation results show that the suboptimal algorithm is throughput-optimal, and understandably, its performances could be better than those in the benchmark algorithm in terms of EE and SD, as long as the appropriate parameter is set.

关键词： NOMA Wireless networks Dynamic scheduling Scheduling algorithms Heuristic algorithms Quality of service Downlink Throughput-optimality network utility maximi- zation non-orthogonal multiple access suboptimal algorithm

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Paired-relay-selection schemes for two-way relaying with network coding

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IET COMMUNICATIONS 2015年第6期9卷 888-896页

作者： Jiang, Yunxiang Lau, Francis Chung Ming Sattar, Zeeshan Ho, Ivan Wang-Hei Zhou, Qing Feng Hong Kong Polytech Univ Dept Elect & Informat Engn Hong Kong Hong Kong Peoples R China HeFei Univ Technol HFUT Sch Comp & Informat Dept Commun Engn Hefei Peoples R China Hong Kong Polytech Univ Shenzhen Res Inst Hong Kong Hong Kong Peoples R China

To exchange information between two sources in a two-way relaying network with multiple potential relays, most researches focus on two-hop relay system with single-relay-selection (SRS) scheme. Comparing with SRS scheme, the authors first design a paired-relay-selection (PRS) scheme in which a pair of best' relays broadcast network-coded information to other nodes (source or relay). They propose an optimal selection algorithm and a suboptimal algorithm that selects the pair of best' relays in the PRS scheme and they describe how the nodes exchange information in a frame consisting of four timeslots. Both the analytical and simulation results show that when the pathloss exponent is large and/or there is a sufficient number of relays to choose from, using two relay nodes can provide a lower outage compared with using only one relay node even under the same total transmit power in uniformly distributed relay networks. In addition, to reduce the overhead of the PRS scheme, they propose an iterative-PRS (I-PRS) scheme in which the paired relay is selected in an iterative and opportunistic way. Simulation results show that the I-PRS scheme has nearly the same outage performance as the PRS scheme under time-invariant channels and significantly outperforms the PRS scheme under time-varying channels.

关键词： relay networks (telecommunication) network coding broadcast communication iterative methods time-varying channels wireless channels paired-relay-selection scheme two-way relaying network multiple potential relay two-hop relay system single-relay-selection scheme SRS scheme broadcast network-coded information optimal selection algorithm suboptimal algorithm one-dimensional space 1D space 2D space path-loss exponent uniformly distributed relay network iterative-PRS scheme I-PRS scheme iterative method time-invariant channel scheme time-varying channel

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Joint resource allocation with subcarrier pairing in cooperative OFDM DF multi-relay networks

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IET COMMUNICATIONS 2015年第1期9卷 78-87页

作者： Li, Xueyi Zhang, Qi Zhang, Guangchi Cui, Miao Yang, Liang Qin, Jiayin Guangdong Univ Technol Sch Informat Engn Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Dept Elect & Commun Engn Guangzhou 510006 Guangdong Peoples R China China Elect Technol Grp Corp 7 Res Inst Guangzhou 510310 Guangdong Peoples R China

For conventional subcarrier pairing scheme in cooperative orthogonal frequency division multiplexing decode-and-forward multi-relay networks, to avoid interference, each subcarrier pair (SP) is assigned to a single relay. Over a specific subcarrier, the destination receives signals transmitted from the relay. In this study, to better exploit the degrees of spatial freedom, the authors propose to assign each SP to multiple relays. Thus, over a specific subcarrier, the destination receives signals transmitted from multiple relays. Under the total network power constraint, to maximise the sum transmission rate, they propose a joint resource allocation scheme, in which they jointly optimised the four types of resources: assisting relays selection, transmission mode selection, subcarrier pairing and power allocation. They further propose a suboptimal algorithm which can significantly reduce the computational complexity of the aforementioned optimal allocation scheme with sacrificing little on the performance. It is shown from simulation results that the author's proposed schemes have significant performance improvement over the resource allocation schemes in the literature.

关键词： cooperative communication relay networks (telecommunication) OFDM modulation resource allocation subcarrier pairing scheme cooperative orthogonal frequency division multiplexing SP decode-and-forward multirelay networks interference avoidance degrees of spatial freedom total network power constraint OFDM computational complexity reduction performance improvement suboptimal algorithm power allocation transmission mode selection relays selection joint resource allocation scheme sum transmission rate

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Proportional fairness resource allocation scheme based on quantised feedback for multiuser orthogonal frequency division multiplexing system

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IET COMMUNICATIONS 2014年第16期8卷 2925-2932页

作者： Xu, Lei Li, Ya-ping Yang, Yu-wang Zhang, Xiaofei Tang, Zhen-min Lan, Shao-hua Nanjing Univ Sci & Technol Sch Comp Sci & Engn Nanjing Jiangsu Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Econ & Management Nanjing Jiangsu Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Elect & Informat Engn Nanjing Jiangsu Peoples R China

This work addresses the resource allocation problem with the proportional fair constraint condition based on quantised feedback for multiuser orthogonal frequency division multiplexing access system. The resource allocation problem is converted as an optimisation problem with maximising the lower bound of the total average throughput and this formulation provides the low complexity of solving the above resource allocation problem. Tailored for the above optimisation problem, the authors design the codebook of equivalent channel quantisation threshold and the codebook of power and rate according to the equal probability quantiser and the Lagrange multiplier method, respectively. Further, they develop a suboptimal algorithm based on the stochastic approximate method. The proposed algorithm not only satisfies the constraint condition of the proportional fair very well, but also reduces the feedback overhead of the resource allocation result greatly. Moreover, the average throughput of the proposed algorithm is very close to that of the optimal resource allocation algorithm with full feedback when the equivalent channel gain in every subcarrier is quantised by 4 bit.

关键词： OFDM modulation optimisation probability proportional fairness resource allocation scheme quantised feedback multiuser orthogonal frequency division multiplexing access system proportional fair constraint condition total average throughput optimisation problem equivalent channel quantisation threshold equal probability quantiser Lagrange multiplier method suboptimal algorithm stochastic approximate method

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Lattice reduction-ordered successive interference cancellation detection algorithm for multiple-input-multiple-output system

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IET SIGNAL PROCESSING 2015年第7期9卷 553-561页

作者： Song, Yunchao Liu, Chen Lu, Feng Nanjing Univ Posts & Telecommun Sch Elect Sci & Engn Nanjing 210003 Jiangsu Peoples R China

Lattice reduction (LR) is a powerful technique for improving the performance of linear multiple-input-multiple-output detection methods. The efficient LR algorithms can largely improve the performance of the linear detectors (LDs). Note that the ordered successive interference cancellation (OSIC) system can decrease the interference between antennas and provide performance gain of the LDs. In this paper, a novel LR-aided algorithm called NLR-OSIC improving the performance of the OSIC system has been proposed. Most existing LR algorithms are designed to improve the orthogonality of channel matrices, which is not directly related to the error performance of the OSIC system. While the authors' algorithm maximises the signal-to-interference-plus-noise ratio (SINR) of the detected symbol in each stage of the OSIC system, thus exhibiting improved error rate than the previous LR-aided LDs and their corresponding OSIC algorithms. In each stage, the authors verify that maximising the SINR of the detected symbol can be formulated as a shortest vector problem which is solved by a suboptimal algorithm in this study. In the end of this study, the error rate performance of the proposed algorithm as well as the required complexity has been demonstrated through extensive computer simulations.

关键词： MIMO communication antenna radiation patterns signal detection interference suppression radiofrequency interference wireless channels matrix algebra rdered successive interference cancellation detection algorithm lattice reduction algorithm multiple input multiple output antenna system linear detector NLR-OSIC system channel matrix orthogonality signal-to-interference-plus-noise ratio LR-aided LD SINR shortest vector problem suboptimal algorithm

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