Topology Control Scheme Research Articles

Joint network lifetime and delay optimization for topology control in heterogeneous wireless multi-hop networks

The network lifetime maximization and the end-to-end delay minimization are tackled by jointly considering the two topology performance indexes in wireless multi-hop networks. Based on the existing eligibility metric for energy efficiency, as well as the new defined metrics for fair energy consumption and end-to-end delay, a new eligibility metric is modeled as ψtup (or ψtdown). From a node’s view point, the estimation over the neighboring nodes is made according to their ψtup (or ψtdown). The Lifetime and Delay based localized Topology Control (LDTC) algorithm is proposed to construct the topology, in which each node keeps its k physical neighbors with maximum ψtup (or ψtdown) as its logical neighbors. Then the Distributed Topology Symmetry (DTS) algorithm is proposed to enforce topology symmetry. Finally, we present the Distributed Logical Neighbor Adjustment (DLNA) algorithm, by which each node adjusts its logical neighbors during the interval between two successive executions of the LDTC and DTS algorithm in order to have nodes exhaust their energy fairly. The simulation results confirm that, under the most simulation settings, our topology control scheme has the minimized imbalance energy reserve and end-to-end delay when compared with the existing similar works. These results show that our topology control scheme suits to prolong the lifetime of the network and also satisfies the demand for low end-to-end delay.

Selection of Efficient Relay for Energy-Efficient Cooperative Ad Hoc Networks

The Cooperative Communication (CC) is a technology that allows multiple nodes to simultaneously transmit the same data. It can save power and extend transmission coverage. However, prior research work on topology control considers CC only in the aspect of energy saving, not that of coverage extension. This paper identify the challenges in the development of a centralized topology control scheme, named Cooperative Bridges, which reduces transmission power of nodes as well as increases network connectivity. Previous research on topology control with CC only focuses on maintaining the network connectivity, minimizing the transmission power of each node, whereas ignores the energy efficiency of paths in constructed topologies. This may cause inefficient routes and hurt the overall network performance in cooperative ad hoc networks. With the help of studied topology control problem for energy-efficient topology with cooperative communication. This paper proposed optimum relay nodes selection for CC network to reduce overall power consumption of network.

A Complex Network Approach to Topology Control Problem in Underwater Acoustic Sensor Networks

Underwater acoustic sensor networks (UASNs) have been developed for a set of underwater applications, including resource exploration, pollution monitoring, and tactical surveillance. Topology control techniques of UASNs are significantly different from those of terrestrial wireless sensor networks, due to the properties of underwater environments and acoustic communications. This research begins with a scale-free network model for calculating edge probability, which is used to generate initial topology randomly. Subsequently, a topology control strategy based on complex network theory (TCSCN) is put forward to construct a double clustering structure, where there are two kinds of cluster-heads to ensure connectivity and coverage, respectively. The performance of TCSCN is analyzed through simulation experiments that indicate a well-constructed topology, where (1, $\xi$ )-Coverage and (1, $\zeta$ )-Connectivity can be achieved while optimizing energy consumption and propagation delay as much as possible.

Topology Control for Harvesting Enabled Wireless Sensor Networks: A Design Approach

While there has been a lot of research on energy efficient topology control protocols destined for different applications, topology control has never been explored in the presence of harvesting enabled sensors. Largely, researchers in this domain have considered a fixed battery design. We argue that arrival of harvesting enabled sensors necessitates rethink of topology control. The objective of topology control in this context should not be to minimize the spent energy and maintain a reduced topology, but to maximize fault tolerance in the network and increase the sensing coverage region. In this work, we first describe a taxonomy of existing topology control schemes and analyze the impact of reduced topology over fault tolerance and sensing coverage. We then describe the necessity of new design parameters in the presence of harvest-able ambient energy. We also outline guiding principles for designing a harvesting enabled topology control scheme. To cater for whether such a scheme is feasible or not, an insight is also provided onto the solar energy availability from solar radiations for near perpetual operation--as an example of available ambient energy. Based on the insight gained from the solar radiations availability, we explain why new design parameters are required for performance measurement of harvesting enabled sensors. The mathematical and empirical findings reveal that the topology control strategies, which do not take into account harvesting opportunity, are unable to provide better results in terms of fault tolerance and sensing coverage.

Energy-Efficient Topology Control With Selective Diversity in Cooperative Wireless Ad Hoc Networks: A Game-Theoretic Approach

Due to the scarce bandwidth and limited power supply in mobile terminals, performance and energy consumption in wireless communications must be continually focused upon. Cooperative transmissions improve the capacity performance of wireless ad hoc networks (WANETs). However, when energy efficiency is considered, the advantage of user cooperation over non-cooperation does not always exist since it involves multiple nodes with more energy consumption in transmissions. To exploit the benefits of user cooperation in cooperative WANETs, we propose a distributed energy-efficient selective diversity (EESD) topology control to improve energy efficiency, which jointly considers network capacity and energy consumption in terms of bits per Joule . EESD forms transmission coalitions via cooperative manner (i.e, diversity) selection, by taking into account the cost of channel information exchange. We then formulate EESD as a coalition game and propose an adaptive coalition formation algorithm for EESD with proved convergence property and stable coalition structures. Simulation results show the performance improvement of EESD in energy efficiency and network lifetime compared to the existing topology control schemes.

Energy-Efficient Topology Management With Interference Cancellation in Cooperative Wireless Ad Hoc Networks

With recent advances in parallel cooperative trans- missions between multiple source-destination pairs, interference cancellation (IC) can be achieved to improve the capacity per- formance of wireless networks. However, from energy efficiency perspective, user cooperation may not be always appealing, since the increased data rate of one user comes at the price of the energy consumed by another user. In this paper, we study the potential benefits/drawbacks of cooperative communications on network-level issues, such as the capacity and the energy efficiency. We show that, in terms of network energy efficiency, coopera- tive communications do not always outperform non-cooperative communications, and cooperative communications should be dy- namically applied in topology control to optimize the overall net- work energy efficiency. Specifically, we propose an energy-efficient topology control scheme by jointly considering the capacity and energy consumption of non-cooperative and cooperative commu- nications. Simulation results are presented to show the effective- ness of the proposed scheme.

Energy Efficient Topology Control Protocol for Wireless Sensor Networks

One major problem in the area of Wireless Sensor Networks (WSNs) is the topology control. Topology control protocols in WSNs construct an optimized network topology structure to satisfy the application requirements, such as network connectivity and coverage. In this paper, we deal with the topology control problem by adjusting the transition radius of the sensor nodes. We produce a cluster-based topology control scheme and propose a new Energy Efficient Topology Control Protocol called EETCP. In this protocol, proper transition radius can be determined using Harmony Search (HS) algorithm. The proposed protocol dynamically adjusts transition radius of nodes (unlike some previous protocols which should select radius values among predefined values). Thus, the proposed protocol has some advantage compared to the previous protocols. EETCP has less average number of neighbors compared to the existing protocols. Also, the energy consumption in EETCP is less than other protocols and the network lifetime will be prolonged. In addition, the network connectivity in EETCP is in the acceptable level. The proposed protocol is simulated and the above advantages are demonstrated by the simulation results.

New power sharing scheme with correlation control for input‐parallel–output‐series‐based interleaved resonant inverters

High-frequency AC power distribution system reveals more merits than low or medium frequency system. The resonant inverter in series or parallel is commonly used as high-frequency power source. However, the topology design and control scheme are complicated for high frequency source formed by multiple resonant inverters. In this study, a modified input-parallel-output-serial topology with the unified resonant tank is presented to boost output capacity and optimise synchronisation. A small signal-based control scheme is analysed for power sharing and magnitude control. Besides, a correlation control is adopted for harmonics suppression and efficiency improvement over a wide operating scope. In a word, the proposed topology and control scheme provide high quality output, flexible power capacity and wide operation range. The performance is evaluated by a two-module prototype with a rated output power of 120 W and output frequency of 25 kHz. The experimental results are accorded with simulation and theoretical analysis.

Application of the One-Cycle Control Technique to a Three-Phase Three-Level NPC Rectifier

The three-phase three-level neutral-point-clamped (NPC) topology is widely employed in rectifiers, active power filters, and electric machine drives. This paper proposes an alternative control strategy for the NPC topology based on the one-cycle control technique and the hybrid pulsewidth modulation strategy. Optimal unbalanced load compensation is achieved with the proposed scheme, of which the principal advantages are simplicity, robustness, and low cost. Experimental results confirm the feasibility of the proposed controller.

Research on User-Side Distributed Power System Control Strategy

Distributed power system, especially the distributed power and micro-grid system in the mountain villages, islands and remote areas, has many advantages, which can be used as an effective supplement of grid to help solve the problem of electricity supply. The connected-grid inverter needs to be able to work in both grid mode and island operation mode in order to ensure the safety of the local critical load. The paper proposed the seamless switching control strategy for two modes of switching. The experimental results verify the property of the topology structure and control strategy.

Adaptive Duty-Cycling to Enhance Topology Control Schemes in Wireless Sensor Networks

To prolong the network lifetime, various scheduling approaches that schedule wireless devices of nodes to switch between active and sleep states have been studied. Topology control schemes are one of the scheduling approaches that can extend the network lifetime and reduce the additional communication delays at the same time. However, they do not guarantee that all nodes have the same lifetime. They reduce the network coverage and prevent seamless communications. This paper proposes an adaptive duty-cycling (ADC) scheme to solve the unbalanced energy consumption generated from the conventional topology control schemes. Our scheme can be applied as a subprocess of them and enable well-balanced energy consumption among all nodes by applying a different duty-cycle to each group based on group size. Therefore, ADC scheme reduces the coverage reduction and maintains the communication delay as a constant throughout the network lifetime. Simulation results show that our scheme extends the network lifetime by at least 25%. This paper also proposes t-ADC scheme. It can be more effectively applied to various environments by adjusting the duty-cycle determined by the ADC scheme which is based on the network traffic amount. We show that t-ADC scheme prolongs the lifetime up to 17% compared to ADC scheme in a low traffic network.

Four hundred Hertz shunt active power filter for aircraft power grids

To fulfill the high reliability of the aeronautical application, a novel three-phase four-wire shunt active power filter (APF) is proposed in this study. In this proposed configuration, traditional phase-leg which is composed of two power switches is replaced by the novel leg composed of one power switch and one diode. The annoying ‘shoot-through’ phenomenon is eliminated by using this novel configuration. Meanwhile, better efficiency and better performance brought by this novel configuration benefit the improvement of the compensation performance. Moreover, operation principle of the APF is analysed in detail; current control strategy and the voltage balance control strategy for the split-capacitor topology are studied as well. Finally, a prototype with the compensating capacity of 3 kVA is designed. Simulation and experimental results are shown to confirm the validity and feasibility of the novel aeronautical APF.

Distributed Cooperative Topology Control for WANETs With Opportunistic Interference Cancelation

Cooperative communications has received tremendous interests in wireless systems. The communication performance of a single source-destination pair can be enhanced via the help of relays in traditional cooperative communications. Recent advances in interference cancelation (IC) can further enhance the performance of parallel cooperative transmissions between multiple source-destination pairs. Although some works have been done on cooperative communications, most existing works are focused on link-level physical-layer issues. Consequently, the potential benefits of cooperative communications on network-level upper layer issues, such as topology control, are largely ignored in existing works. In this paper, we study the impacts of cooperative communications, particularly IC-based cooperative communications, on topology control in wireless ad hoc networks (WANETs). We propose a distributed cooperative topology control scheme with opportunistic IC (COIC) to improve network capacity in WANETs by jointly considering both upper layer network capacity and physical-layer cooperative communications with IC. We show that the benefits brought by cooperative communications are opportunistic, which rely on network structures and channel conditions. These opportunistic advantages have significant impacts on network capacity, and our proposed COIC can effectively capture these opportunities to substantially improve network capacity.

Efficient topology control scheme for wireless ad-hoc networks

An ad-hoc network considers an automatic network formation and maintenance of critical services as nodes come closer or go far away from each other. There is no wired infrastructure or cellular network in wireless ad-hoc network. Each mobile node has an adjustable transmission range. A node n can receive signal from another node m if node n is within the transmission range of the sender m otherwise, two nodes communicate by relaying the message using intermediate nodes. In this paper, we studied how to construct a sparse spanner efficiently for wireless ad-hoc network topology. For any given pair of nodes there is a power efficient path. Power values may be assigned to the nodes in ad-hoc networks, to tackle the topology control issue. This paper considers topology control problems under optimisation objectives to include minimising the maximum power and also overall power. We have tackled the topology control problem, by formulating as a linear programming for the traffic loads and an optimal solution was computed. Theoretical analysis and simulation study verify that the proposed scheme is better up to some extent.

Energy-aware topology control for reliable data delivery in solar-powered WSNs

Solar power is a valuable source of power for wireless sensor networks, but it periodically requires an appropriate energy management strategy. We introduce a scheme that constructs and maintains a fault-tolerant wireless sensor network topology that can make the best use of solar energy. This topology control scheme is based on a simple model of the availability of solar energy and matches the connectivity of each node with the energy left in its battery. Operating locally, our scheme constructs and maintains a k-connected backbone of energy-rich nodes that handles most of the network’s traffic reliably, without depleting the reserves of energy-poor nodes. Simulation results demonstrate the effectiveness of our scheme.

Interference Nomenclature in Wireless Mesh Networks

The Quality of Service of Multi-Channel Multi-Radio Wireless Mesh Networks is adversely affected by the complex behavior of interference patterns present between the sender and receiver of a link. This behavior is usually captured using wireless channel interference models. The accuracy of the interference model is highly dependent on the interaction of the Carrier Sense Multiple Access with Collision Avoidance Medium Access Control (CSMA/CA MAC) protocol based on the geometric location of the sender and receiver of the link. Therefore, this paper presents a nomenclature of interference modeling schemes available in Wireless Mesh Network (WMN) literature with respect to the geometric location of the sender and receiver of a link. The behavior and limitations of each model are analyzed with the help of empirical examples. The results indicate that Garetto’s model of interfering links is the best choice to model wireless channel interference in WMNs. In addition, this study provides an interference analysis of Garetto’s model for the two link case by computing the conditional packet loss probability of each class of interfering link. The probability analysis concluded that the links with disconnected senders are highly interfering compared to sender connected links. Further, the analysis will assist researchers and engineers in relay node placement, capacity analysis, channel assignment, and topology control schemes in the WMN.

A survivable routing protocol for two-layered LEO/MEO satellite networks

Due to the rapid development of space communication, satellite networks will be confronted with more complex space environment in future, which poses the important demand on the design of the survivable and efficient routing protocols. Among satellite networks, two-layered Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) satellite networks (LMSNs) have become an attractive architecture for their better communication service than single-layered satellite networks. To determine the topological dynamics of LMSN, the satellite group and group manager (SGGM) method is a prevalent strategy. However, it can not precisely capture the topological dynamics of the LEO layer, which may result in the unreliability of data transmission. Besides, most existing routing protocols based on the SGGM method will collapse once any top satellite fails. To overcome both limitations, this paper proposes a new topology control strategy for LMSNs. The proposed strategy determines the snapshot in terms of the topological change of the LEO layer, which ensures the topological consistency of routing calculation. Moreover, a new survivable routing protocol (SRP) is presented for LMSNs by combining both centralized and distributed routing strategies. The SRP can provide strong survivability under the LEO or MEO satellite failure. Besides, it can also achieve the minimum delay routing provided the MEO layer can effectively work. The performance of SRP is also evaluated by simulation and analysis.

Analysis and Simulation of Fault Characteristics of Power Switch Failures in Distribution Electronic Power Transformers

This paper presents research on the voltage and current distortion in the input stage, isolation stage and output stage of Distribution Electronic Power transformer (D-EPT) after the open-circuit and short-circuit faults of its power switches. In this paper, the operational principles and the control methods for input stage, isolation stage and output stage of D-EPT, which work as a cascaded H-bridge rectifier, DC-DC converter and inverter, respectively, are introduced. Based on conclusions derived from the performance analysis of D-EPT after the faults, this paper comes up with the effects from its topology design and control scheme on the current and voltage distortion. According to the EPT fault characteristics, since the waveforms of relevant components heavily depend on the location of the faulty switch, it is very easy to locate the exact position of the faulty switch. Finally, the fault characteristics peculiar to D-EPT are analyzed, and further discussed with simulation on the Saber platform, as well as a fault location diagnosis algorithm.

Distributed cooperative control for deployment and task allocation of unmanned aerial vehicle networks

In this study, the authors consider the deployment of unmanned aerial vehicle networks for task accomplishment within a closed region. Each agent with limited sensing range and communication range needs to take charge of the task accomplishment within a part of the whole region. The main objective is to optimise the deployment of the agents such that the maximum travelling time the agents take to reach a place within the surveillance region is minimised. The deployment issue is formulated as the worst-case disc-covering problem and a distributed cooperative control strategy is designed for agents with limited mobility. It is proven that by the proposed control strategy the network configuration converges to a local optimum configuration. Moreover, a combined optimisation approach is developed to improve the performance by optimising the initial configuration. To guarantee the proper working of the designed control strategy and K -connectivity of the network, a distributed topology control scheme is proposed. Finally, the effectiveness of the proposed control strategy is testified by simulation.

A PSO-Optimized Minimum Spanning Tree-Based Topology Control Scheme for Wireless Sensor Networks

Wireless sensor networks (WSNs) are networks of autonomous nodes used for monitoring an environment. Topology control is one of the most fundamental problems in WSNs. To overcome high connectivity redundancy and low structure robustness in traditional methods, a PSO-optimized minimum spanning tree-based topology control scheme is proposed in this paper. In the proposed scheme, we transform the problem into a model of multicriteria degree constrained minimum spanning tree (mcd-MST) and design a nondominated discrete particle swarm optimization (NDPSO) to deal with this problem. To obtain a better approximation of true Pareto front, the multiobjective strategy with a fitness function based on niche and phenotype sharing function is applied in NDPSO. Furthermore, a topology control scheme based on NDPSO is proposed. Simulation results show that NDPSO can converge to the non-dominated front quite evenly, and the topology derived under the proposed topology control scheme has lower total power consumption, higher robust structure, and lower contention among nodes.