Number Of Communication Links Research Articles

Evaluating the Effect of the Communication Link of the Relays on the Operation Time of the Protection System

In case of an error in the power system, it is the duty of the protection relays to isolate the faulty part from the rest of the system as soon as possible. Overcurrent and distance relays are usually used to protect the transmission and super distribution systems. The optimum coordination of these relays is very important. In this article, communication links are used to improve the optimal coordination of overcurrent and distance relays. In the proposed plan, the overcurrent relays on both sides of the line are equipped with a communication link for immediate action in the event of an error. Using this communication link, the complete coverage of the line is also provided by distance relays. The number and place of installation of the communication link greatly affect the operation time of overcurrent relays and the distance and coordination between them. The coordination problem is formulated by considering the location and number of communication links, and to solve it, the combined optimization algorithm of genetics and linear programming will be used. With the help of the genetic algorithm, the location and setting of the second zone of the distance relay, and by using the linear programming algorithm, the setting of the overcurrent relays is determined. The proposed method has been tested on the IEEE 14-bus (the simulation in MATLAB software) network and its results examined, and it will be seen how much the existence of a communication link can improve the performance time of the protection system.

Performance analysis of a millimeter wave MIMO channel estimation method in an embedded multi-core processor

The emerging Multi-Processor System-on-Chip (MPSoC) technology, which combines heterogeneous computing with the high performance of field programmable gate arrays (FPGA), is a promising platform for a large number of applications, including wireless communications and vehicular technology. In this specific application context, when multiple-input multiple-output (MIMO) scenarios are considered, the system usually has to manage a large number of communication links among sensors and antennas involving different vehicles and users. Millimeter wave (mmWave) communications are one of the key technology enablers toward achieving high data rates in beyond 5G systems (B5G). Communication at these frequency bands usually involves the use of large antenna arrays, often requiring high computational resources. One of the candidate platforms able to manage a huge number of communications is the Xilinx Zynq UltraScale+ EG Heterogeneous MPSoC, which is composed of a dual-core Cortex-R5, a quad-core ARM Cortex-A53, a graphics processing unit (GPU) and a high-end FPGA. This work analyzes the computational performance that requires a recent mmWave MIMO channel estimation algorithm in a platform of this kind. As a first approach, we will focus our work on the performance that can be achieved via the quad-core ARM Cortex-A53. To this end, we will use the libraries for numerical algebra (BLAS and LAPACK). The results show that our reference implementation is able to manage a large MIMO communication system with 256 antennas without exhausting platform resources.

Scale-Free Features in Collective Robot Foraging

In many complex systems observed in nature, properties such as scalability, adaptivity, or rapid information exchange are often accompanied by the presence of features that are scale-free, i.e., that have no characteristic scale. Following this observation, we investigate the existence of scale-free features in artificial collective systems using simulated robot swarms. We implement a large-scale swarm performing the complex task of collective foraging, and demonstrate that several space and time features of the simulated swarm—such as number of communication links or time spent in resting state—spontaneously approach the scale-free property with moderate to strong statistical plausibility. Furthermore, we report strong correlations between the latter observation and swarm performance in terms of the number of retrieved items.

Observer‐based attack‐resilient control for linear systems against FDI attacks on communication links from controller to actuators

SummaryFor the adversarial attacks on the communication links from the controller to the actuators, most of the existing attack‐resilient control results focus on denial‐of‐service attacks. Unlike the existing results, this paper studies the observer‐based attack‐resilient control problem for linear systems with false data injection attacks and process disturbances. Due to limited resources, the malicious attacker is assumed to only manipulate a certain number of communication links from the controller to the actuators. A novel control architecture is proposed, which consists of an attack‐resilient state observer, a controller gain scheme, and a supervisory switching strategy. The observer is developed based on the maximin strategy, and state estimation will be used to construct the controller. The switching strategy is designed to pick an appropriate controller gain and prevent the attack signals from entering the plant automatically. It is shown that the closed‐loop system is stable with an attack‐resilient performance. Finally, to verify the effectiveness of the proposed controller, simulation results on a linearized reduced‐order aircraft system and an IEEE six‐bus power system are provided.

Sparsely distributed sliding mode control for interconnected systems

This paper proposes a framework for the design of sparsely distributed output feedback discrete-time sliding mode control (ODSMC) for interconnected systems. The major target here is to develop an observer based discrete-time sliding mode controller employing a sparsely distributed control network structure in which local controllers exploit some other sub-systems’ information as well as its own local information. As the local controllers/observers have access to some other sub-systems’ states, the control performance will be improved and the applicability region will be widened compared to the decentralised structure. As the first step, a stability condition is derived for the overall closed-loop system obtained from applying ODSMC to the underlying interconnected system, by assuming a priori known structure for the control/observer network. The developed LMI based controller design scheme provides the possibility to employ different information patterns such as fully distributed, sparsely distributed and decentralised patterns. In the second step, we propose a methodology to identify a sparse control/observer network structure with the least possible number of communication links that satisfies the stability condition given in the first step. The boundedness of the obtained overall closed-loop system is analysed and a bound is derived for the augmented system state which includes the closed-loop system state and the switching function.

Optimal Design of a Wide Area Measurement System for Improvement of Power Network Monitoring Using a Dynamic Multiobjective Shortest Path Algorithm

Wide area measurement system (WAMS) usually contains three dependent infrastructures called management, measurement, and communication. For optimal operation of a power system, it is necessary to design these infrastructures suitably. In this paper, measurement and communication infrastructures in a wide area network are designed independently from a management viewpoint, considering an adequate level of system observability. In the first step, optimal placement of measurement devices is determined using an integer linear programming (ILP) solution methodology while taking into account zero-injection bus effects. In the next step, new dynamic multiobjective shortest path (MOSP) programming is presented for the optimal design of communication infrastructure. The best architecture design is introduced in terms of optical fiber power ground wire (OPGW) coverage for the suggested central control bus and the number of phasor measurement units (PMUs). The applicability of the proposed model is finally examined on several IEEE standard test systems. The simulation results show better performance of the proposed method compared with other conventional methods. The numerical results reveal that applying the proposed method could not only reduce the OPGW coverage cost, the number of PMUs, and the number of communication links but could also improve the system technical indexes such as latency as subsidiary results of the optimization process.

Fixed Mode Elimination by Minimum Communication Within an Estimator-Based Framework for Distributed Control

A distributed control scheme is considered, where each subsystem estimates a part of the state space and uses a state feedback-based controller to actuate a subset of the system’s inputs. The estimated parts of the state space are overlapping and thus provide some information about the neighboring subsystems to the local controllers. The number of communication links which are added to improve performance is a design choice. However, a minimum of communication is needed if there are fixed modes (FMs), which are eigenvalues of the closed-loop system that cannot be changed under the given structural constraints. Mild conditions on the overlapping structure are given under which there exists a communication topology of measurements or estimates to eliminate all FMs. The problem of finding the minimum communication to eliminate all FMs is formulated as a minimum cost coverage problem with submodular constraints. Based on this result, an algorithm for the FM elimination is proposed and compared to the greedy algorithm. A numerical example illustrates the results.

Multi-channel time division multiple access timeslot scheduling with link recovery for multi-hop wireless sensor networks

In this article, we propose a time division multiple access scheduling algorithm for end-to-end on-time packet delivery in multi-hop wireless sensor networks. Our proposed algorithm establishes a new communication path to substitute the old path including the link failed and schedules communication links on the new path by allocating timeslots satisfying end-to-end delay bound. Max–min optimization is employed to maximize the number of dedicated timeslots to establish the substitute path in the event of the next link failure. We evaluate the performance of the proposed algorithm using QualNet network simulator and compare it with the performance of the algorithm that minimizes the end-to-end delay. Our numerical results show that the path survival ratio of the proposed algorithm is approximately two times higher when large number of communication links fails. In addition, we apply the global recovery and local recovery schemes to observe the increase in the overhead message exchanges. Compared to the global recovery scheme, local recovery scheme requires six times less control messages to establish the substitute path when a small number of link failures occur, whereas more than 90% communication paths survive.

Sparse Observer-Based Sliding Mode Control For Networked Control Systems

This paper is devoted to the problem of designing a sparse distributed output feedback discrete-time sliding mode control (ODSMC) for the networked systems. A distributed structure is employed in the discrete-time sliding mode control framework by exploiting other sub-systems’ information to improve the performance of each local controller/observer so that it can widen the applicability region of the given scheme. As the first step, a stability condition is derived for the overall closed-loop system obtained from applying ODSMC to the underlying interconnected system, by assuming a given structure for the control/observer network. In the second step, we explore a methodology to obtain a sparse control/observer network structure with the least possible number of communication links that satisfies the stability condition given in the first step. The boundedness of the obtained overall closed-loop system is analyzed and a bound is derived for the augmented system state which includes the closed-loop system state and the switching function.

Localization in the Parking Lot by Parked-Vehicle Assistance

Vehicular ad hoc networks represent a promising solution to vehicle navigation in parking lots. Many proposed architectures so far rely upon the roadside units (RSUs) around the parking lot for localization purposes. In this paper, we present a parked-vehicle assistance (PVA)-based position estimation scheme. The many PVA links we exploit significantly increase the number of communication links and range measurements used for localization. This way, we alleviate the constraint imposed by the usually limited number of RSUs. While the proposed method serves as a promising candidate to achieve accurate vehicle localization particularly in parking lots, the range measurements from the parked vehicles may suffer from severe non-line-of-sight (NLOS) conditions native to the parking lot topologies. In response, we propose a two-step algorithm to efficiently detect the NLOS links. This way, we can exploit the benefits offered by PVA, while keeping a reasonable computational load by efficiently differentiating the range measurements. Indeed, our simulation results demonstrate a significant increase in terms of the position accuracy compared with the RSU-based scheme.

Ultra-Dense Networks: A Survey

The exponential growth and availability of data in all forms is the main booster to the continuing evolution in the communications industry. The popularization of traffic-intensive applications including high definition video, 3-D visualization, augmented reality, wearable devices, and cloud computing defines a new era of mobile communications. The immense amount of traffic generated by today’s customers requires a paradigm shift in all aspects of mobile networks. Ultradense network (UDN) is one of the leading ideas in this racetrack. In UDNs, the access nodes and/or the number of communication links per unit area are densified. In this paper, we provide a survey-style introduction to dense small cell networks. Moreover, we summarize and compare some of the recent achievements and research findings. We discuss the modeling techniques and the performance metrics widely used to model problems in UDN. Also, we present the enabling technologies for network densification in order to understand the state-of-the-art. We consider many research directions in this survey, namely, user association, interference management, energy efficiency, spectrum sharing, resource management, scheduling, backhauling, propagation modeling, and the economics of UDN deployment. Finally, we discuss the challenges and open problems to the researchers in the field or newcomers who aim to conduct research in this interesting and active area of research.

Synthesizing Robust Communication Networks for Unmanned Aerial Vehicles With Resource Constraints

In this article, we address the problem of synthesizing communication networks for unmanned aerial vehicles (UAVs) in the presence of resource constraints. UAVs can be deployed as backbone nodes in ad hoc networks that can be central to civilian and military applications. The cost of operation of the network depends on the resources that are used such as the total power consumption associated with the network and the number of communication links in the network. The objective of the problem is to synthesize a communication network that maximizes connectivity subject to the cost of operation being within the specified budget for the resources. It is known that algebraic connectivity is a measure of robust connectivity and hence, it is chosen as an objective for optimization. We pose the network synthesis problem as a mixed-integer semidefinite program (MISDP): (1) provide an algorithm for computing optimal solutions using cutting plane methods; (2) develop lower bounds by posing the problem as a binary semidefinite program; and (3) construct feasible solutions using heuristics and estimate their quality. The network synthesis problem is a nondeterministic polynomial--time (NP)-hard problem. We provide some computational results to corroborate the performance of the proposed algorithms.

Implementing the weakest failure detector for solving the consensus problem

The concept of unreliable failure detector was introduced by Chandra and Toueg as a mechanism that provides information about process failures. This mechanism has been used to solve several agreement problems, such as the consensus problem. In this paper, algorithms that implement failure detectors in partially synchronous systems are presented. First two simple algorithms of the weakest class to solve the consensus problem, namely the Eventually Strong class (⋄S), are presented. While the first algorithm is wait-free, the second algorithm is f-resilient, where f is a known upper bound on the number of faulty processes. Both algorithms guarantee that, eventually, all the correct processes agree permanently on a common correct process, i.e. they also implement a failure detector of the class Omega (Ω). They are also shown to be optimal in terms of the number of communication links used forever. Additionally, a wait-free algorithm that implements a failure detector of the Eventually Perfect class (⋄P) is presented. This algorithm is shown to be optimal in terms of the number of bidirectional links used forever.

A method for designing the communication structure of networked controllers

The paper analyses the command-following behaviour of synchronised systems in dependence upon the communication structure of the networked controller. Its focus lies on the transient behaviour before the subsystems reach a common trajectory. It considers the dynamics of the subsystems as the main reason for the delay that the information about the reference trajectory is exposed to between the leader and the followers on a communication path, whereas the communication network is assumed to provide instantaneous information transmission. An abstract model of the overall system is introduced that represents the coupling structure of the agents together with a quantitative delay measure. This model is used to determine communication structures in which all agent outputs follow the reference trajectory with small delay. It helps to find a trade-off between the number of communication links and the quality of the system performance. The results are illustrated by its application to a robot formation problem.

A SURVEY OF THE EFFECT OF NETWORK PARAMETERS ON COMMUNICATION LINKS IN WIRELESS SENSOR NETWORKS

In the wireless sensor networks, the communication links between sensor nodes is important. This paper presents the analysis on the effect of parameters of network size, number of nodes and communication ranges on the number of communication links in the sensor network systems. The MATLAB tool is used for deployment of sensor nodes in various area fields.

An abstract model for designing the communication structure of networked controllers

Networked controllers are used to synchronise autonomous agents by driving the agent states towards a common trajectory. This paper analyses the command-following behaviour of leader-follower systems in dependence upon the communication structure of the controller. It introduces a quantitative measure of the delay that information is exposed to while it is transmitted from the leader agent through the network. This measure can be used to find communication structures in which all agent outputs follow the reference trajectory with small delays. It helps to find a trade-off between the number of communication links and the quality of the system performance. The results are illustrated by a robot formation problem.

Exact Quantum Algorithms for the Leader Election Problem

This article gives a separation between quantum and classical models in pure (i.e., noncryptographic) computing abilities with no restriction on the amount of available computing resources, by considering the exact solvability of the leader election problem in anonymous networks, a celebrated unsolvable problem in classical distributed computing. The goal of the leader election problem is to elect a unique leader from among distributed parties. In an anonymous network, all parties with the same number of communication links are identical. It is well-known that no classical algorithm can exactly solve (i.e., in bounded time without error) the leader election problem in anonymous networks, even if the number of parties is given. This article devises a quantum algorithm that, if the number of parties is given, exactly solves the problem for any network topology in polynomial rounds with polynomial communication/time complexity with respect to the number of parties, when the parties are connected with quantum communication links and they have the ability of quantum computing. Our algorithm works even when only an upper bound of the number of parties is given. In such a case, no classical algorithm can solve the problem even under the zero-error setting, the setting in which error is not allowed but running time may be unbounded.

Throughput and Error Analysis of a Space-Time Resource Management Scheme for Multi-Gbps Millimeter-Wave WPAN System

In this paper, throughput and error performance analysis is conducted on the proposed space-time resource management (STRM) scheme to realize a multi-Gbps millimeter-wave wireless personal area network (WPAN) system. The proposed STRM allows multiple peer-to-peer communication links to occupy the same time-division-multiple-access (TDMA) time slot, in contrary to the conventional TDMA system that allocates only one time slot to one communication link. Theoretical analysis is performed to investigate the achievable system throughput in the presence of co-channel interference (CCI) generated by communication links co-sharing the same time slot. To increase accuracy, the analysis results are validated by Monte Carlo simulations. Firstly, it is found that the upper bound of the achievable throughput increases linearly with the number of communication links sharing the same time slot. However, optimum throughput exists corresponding to the CCI present in the system. Secondly, by manipulating a parameter that controls the allowable CCI in the network, the system throughput can be optimized. Lastly, it is also found that in a millimeter-wave band system, a victim system with transmitter-receiver separation of 1-meter can achieve bit error rate (BER) of 10- 6 provided that the interferer is at least 6-meters away.

Deployment of a team of biomimetic searching agents based on limited communication quantity

AbstractThis paper presents a dispersion movement design for a multi‐agent team inspired by the behavior of creatures. The goal of the dispersion algorithm is to maintain the communication network between agents and to enlarge the coverage area as widely as possible. The communication density, or the number of communication links, is the only information needed. A dispatch rule for releasing agents at a base station is also designed based on the dispersion algorithm. The proposed algorithms have been extensively tested by software simulation. Statistics concerning the coverage area, network partition rate, and spending time are analyzed to verify the feasibility and advantages of the algorithms. Potential applications of the proposed algorithms include rescue in a damaged area, planetary exploration, military reconnaissance, and geophysical mapping. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Emergence of a Small-World Like Communication Network Through Local Ad Hoc Negotiation

Focusing on an algorithm for realizing a small-world (SW) like ad hoc communication network among autonomous mobile agents, we discuss how the ad hoc network emerges through local negotiation without a central manager. We have started procedures that lend emerging networks the SW property, resulting in effective, low-cost communication. We formulate the expected number of communication links and degrees of agents, verifying the feasibility of our proposal through simulation.