Connected dominating sets in disk graphs with bidirectional links

In this paper, we study the connected dominating set (CDS) problem in disk graphs. The CDS problem has a significant impact on an efficient design of routing protocols in wireless networks. This problem has been studied extensively in unit disk graphs, in which each node has the same transmission range. However, in wireless ad hoc networks, the transmission ranges of all nodes are not necessary equal. In this paper, we introduce the CDS problem in disk graphs and present a constant approximation algorithm which can be implemented as a distributed algorithm.     

A new distributed approximation algorithm for constructing minimum connected dominating set in wireless ad hoc networks

In recent years, constructing a virtual backbone by nodes in a connected dominating set (CDS) has been proposed to improve the performance of ad hoc wireless networks. In general, a dominating set satisfies that every vertex in the graph is either in the set or adjacent to a vertex in the set. A CDS is a dominating set that also induces a connected sub‐graph. However, finding the minimum connected dominating set (MCDS) is a well‐known NP‐hard problem in graph theory. Approximation algorithms for MCDS have been proposed in the literature. Most of these algorithms suffer from a poor approximation ratio, and from high time complexity and message complexity. In this paper, we present a new distributed approximation algorithm that constructs a MCDS for wireless ad hoc networks based on a maximal independent set (MIS). Our algorithm, which is fully localized, has a constant approximation ratio, and O(n) time and O(n) message complexity. In this algorithm, each node only requires the knowledge of its one‐hop neighbours and there is only one shortest path connecting two dominators that are at most three hops away. We not only give theoretical performance analysis for our algorithm, but also conduct extensive simulation to compare our algorithm with other algorithms in the literature. Simulation results and theoretical analysis show that our algorithm has better efficiency and performance than others. Copyright © 2005 John Wiley & Sons, Ltd.     

A distributed battery recovery aware topology control algorithm for wireless sensor networks

Battery recovery effect is a phenomenon that the available capacity of a battery could increase if the battery can sleep for a certain period of time since its last discharging. Accordingly, the battery can work for a longer time when it takes some rests between consecutive discharging processes than when it works all the time. However, this effect has not been considered in the design of energy‐efficient topology control algorithms for wireless sensor networks. In this paper, we propose a distributed battery recovery effect aware connected dominating set constructing algorithm (BRE‐CDS) for wireless sensor networks. In BRE‐CDS, each network node periodically decides to join the connected dominating set or not. Nodes that have slept in the preceding round have priority to join the connected dominating set in the current round while nodes that have worked in the preceding round are encouraged to take sleep in the current round for battery recovery. Detailed algorithm design is presented. The computational complexity of BRE‐CDS is deduced to be O(D²), where D is node degree. Simulation results show that BRE‐CDS can significantly prolong the network lifetime as compared with existing work. Copyright © 2016 John Wiley & Sons, Ltd.     

Connected Dominating Sets in Wireless Networks with Different Transmission Ranges

Since there is no fixed infrastructure or centralized management in wireless ad hoc networks, a Connected Dominating Set (CDS) has been proposed to serve as a virtual backbone. The CDS of a graph representing a network has a significant impact on the efficient design of routing protocols in wireless networks. This problem has been studied extensively in Unit Disk Graphs (UDG), in which all nodes have the same transmission ranges. However, in practice, the transmission ranges of all nodes are not necessarily equal. In this paper, we model a network as a disk graph and introduce the CDS problem in disk graphs. We present two efficient approximation algorithms to obtain a minimum CDS. The performance ratio of these algorithms is constant if the ratio of the maximum transmission range over the minimum transmission range in the network is bounded. These algorithms can be implemented as distributed algorithms. Furthermore, we show a size relationship between a maximal independent set and a CDS as well as a bound of the maximum number of independent neighbors of a node in disk graphs. The theoretical analysis and simulation results are also presented to verify our approaches.     

Greedy construction of load‐balanced virtual backbones in wireless sensor networks

Inspired by the backbone concept in wired networks, a virtual backbone is expected to bring substantial benefits to routing in wireless sensor networks (WSNs). A connected dominating set (CDS) is used as a virtual backbone for efficient routing and broadcasting in WSNs. Most existing works focus on constructing a minimum CDS, a k‐connect m‐dominating CDS, a minimum routing cost CDS, or a bounded‐diameter CDS. However, the load‐balance factor is not considered for CDSs in WSNs. In this paper, a greedy‐based approximation algorithm is proposed to construct load‐balanced CDS in a WSN. More importantly, we propose a new problem: the Load‐balanced Allocate Dominatee problem. Consequently, we propose an optimal centralized algorithm and an efficient probability‐based distributed algorithm to solve the Load‐balanced Allocate Dominatee problem. For a given CDS, the upper and lower bounds of the performance ratio of the distributed algorithm are analyzed in the paper. Through extensive simulations, we demonstrate that our proposed methods extend network lifetime by up to 80% compared with the most recently published CDS construction algorithm. Copyright © 2012 John Wiley & Sons, Ltd.     

Weighted Steiner Connected Dominating Set and its Application to Multicast Routing in Wireless MANETs

In this paper, we first propose three centralized learning automata-based heuristic algorithms for approximating a near optimal solution to the minimum weight Steiner connected dominating set (WSCDS) problem. Finding the Steiner connected dominating set of the network graph is a promising approach for multicast routing in wireless ad-hoc networks. Therefore, we present a distributed implementation of the last approximation algorithm proposed in this paper (Algorithm III) for multicast routing in wireless mobile ad-hoc networks. The proposed WSCDS algorithms are compared with the well-known existing algorithms and the obtained results show that Algorithm III outperforms the others both in terms of the dominating set size and running time. Our simulation experiments also show the superiority of the proposed multicast routing algorithm over the best previous methods in terms of the packet delivery ratio, multicast route lifetime, and end-to-end delay.     

The first constant factor approximation for minimum partial connected dominating set problem in growth-bounded graphs

The idea of virtual backbone has emerged to improve the efficiency of flooding based routing algorithms for wireless networks. The effectiveness of virtual backbone can be improved as its size decreases. The minimum connected dominating set (CDS) problem was used to compute minimum size virtual backbone. However, as this formulation requires the virtual backbone nodes to connect all other nodes, even the size of minimum virtual backbone can be large. This observation leads to consider the minimum partial CDS problem, whose goal is to compute a CDS serving only more than a certain portion of the nodes in a given network. So far, the performance ratio of the best approximation algorithm for the problem is \(O(\ln \varDelta ),\) where \(\varDelta\) is the maximum degree of the input general graph. In this paper, we first assume the input graph is a growth-bounded graph and introduce the first constant factor approximation for the problem. Later, we show that our algorithm is an approximation for the problem in unit disk graph with a much smaller performance ratio, which is of practical interest since unit disk graph is popular to abstract homogeneous wireless networks. Finally, we conduct simulations to evaluate the average performance of our algorithm.     

时延和能耗均衡的强连通支配集构造算法

针对无线传感器网络中链路的非对称性,提出时延约束的强连通支配树(SDTT,strongly connected dominating tree with bounded transmission delay)问题,给出在有向图上构建传输时延和能量消耗均衡的强连通支配集的强连通支配树(SCDT,distributed strongly connected dominating tree)算法。首先在单位圆图(UDG)模型的基础上构建极大独立集(MIS),然后在具有双向权值的有向图上基于最小支撑树和最短路径树实现分布式SCDT算法,同时满足时延和能耗均衡的约束条件要求。理论算例分析和仿真结果表明提出的算法能有效地解决SDTT问题,构造联合约束的强连通支配集,形成时延和能耗均衡的虚拟骨干。     

Network coding over connected dominating set: energy minimal broadcasting in wireless ad hoc networks

Energy efficient broadcast is indispensable for many applications in wireless ad hoc networks. It has been proved that network coding has great potential to improve performance in terms of energy consumption in wireless ad hoc networks. However, the power of network coding depends on the availability of coding opportunities, which in turns depends on how routing paths are established. It is thus beneficial to establish paths in such a way that more coding opportunities are created. By combining network coding and connected dominating set (CDS), we explore energy minimal broadcast protocols in wireless ad hoc networks. The rationale behind this combination is that CDS provides better chances for data flows to intersect, which means more coding opportunities. We design a scheme, named NCDS, that uses network coding over connected dominating set, to reduce energy consumption. Analysis and experimental results show that NCDS outperforms broadcast algorithms that use CDS or network coding alone.     

Construction and maintenance of virtual backbone in wireless networks

In ad hoc wireless networks, there is no predefined infrastructure and nodes communicate with each other via peer communications. In order to make routing efficient in such networks the connected dominating set (CDS) can act as virtual backbone for the network. A smaller virtual backbone suffers less from the interference problem and incurs less maintenance overhead. Computing minimum CDS backbone is proven to be NP-Hard, it is therefore desirable to use efficient heuristic algorithms to find a virtual backbone of small size. Diameter and average backbone path length (ABPL) are other major criteria for evaluation of the backbone produced by an algorithm. In this paper, after giving a brief survey of classical CDS algorithms, two new centralized algorithms are described for the construction of the virtual backbone and their performance has been compared with five recent algorithms (two centralized and three distributed) along the parameters: size, diameter, and ABPL. The new algorithms perform better on most of the criteria. The re-construction of entire CDS upon movement or failure of a few nodes is very costly in terms of processing power, battery utilization, bandwidth utilization etc., as compared to maintaining the CDS for the affected nodes, since the re-construction of the CDS is to be performed for the whole network while maintenance involves the affected nodes and their neighbours only. A new distributed algorithm is described that maintains the virtual backbone on movement or failure of a single node. The overhead of CDS maintenance with this algorithm compares very favourably against that of re-construction.     

基于极大独立集的最小连通支配集的分布式算法

全网范围的广播在无线传感器网络和移动自组织网络中有着广泛的应用.为节省网络资源,减少冗余转发节点成为广播中需解决的关键问题.广播过程中最小化参与转发节点数问题与图论中求解最小连通支配集问题等价,而在任意图中求解最小连通支配集是NP完全问题.本文基于极大独立集,提出了一种求解最小连通支配集的分布式算法(MISB),并证明了算法的正确性.仿真结果表明,使用该算法能得到较小的连通支配集,从而有效减少网络广播过程中的转发节点数,大大节省了网络资源.     

Rotation of CDS via Connected Domatic Partition in Ad Hoc Sensor Networks

Wireless ad hoc and sensor networks (WSNs) often require a connected dominating set (CDS) as the underlying virtual backbone for efficient routing. Nodes in a CDS have extra computation and communication load for their role as dominator, subjecting them to an early exhaustion of their battery. A simple mechanism to address this problem is to switch from one CDS to another fresh CDS, rotating the active CDS through a disjoint set of CDSs. This gives rise to the connected domatic partition (CDP) problem, which essentially involves partitioning the nodes V(G) of a graph G into node disjoint CDSs. We have developed a distributed algorithm for constructing the CDP using our maximal independent set (MIS)-based proximity heuristics, which depends only on connectivity information and does not rely on geographic or geometric information. We show that the size of a CDP that is identified by our algorithm is at least lfloor{frac{delta+1}{beta(c+1)}}rfloor-f, where delta is the minimum node degree of G, betaleq 2, cleq 11 is a constant for a unit disk graph (UDG), and the expected value of f is epsilondelta|V|, where epsilon ll 1 is a positive constant, and delta geq 48. Results of varied testing of our algorithm are positive even for a network of a large number of sensor nodes. Our scheme also performs better than other related techniques such as the ID-based scheme.     

RECA: Referenced energy‐based CDS algorithm in wireless sensor networks

Connected dominating sets (CDS) can be used to form virtual backbones for the hierarchical routing to save energy in the wireless sensor networks. The existing algorithms for CDS can only be used to the topologies that have larger vertex connective degrees. Besides, most of them do not consider the energy characteristics of the virtual backbones constructed by the dominating sets. In this paper, a referenced energy‐based CDS algorithm (RECA) is proposed, which can generate smaller CDS in random topologies without the limitation of vertex connective degrees. At the same time, the algorithm introduces Referenced Energy as a parameter for nodes when making the decision whether they are chosen to be the dominators or not. Therefore, as the experimental results show, the energy characteristic of the dominating set is improved and routing in the virtual backbones constructed by such CDSs will have a better performance. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation and improvement of CDS-based topology control for wireless sensor networks

The connected dominating set (CDS) principle has emerged as the predominant method for energy-efficient discovery and clustering of power-/location-unaware WSN nodes. While many CDS discovery protocols have been proposed recently, a one-to-one comparative evaluation of these protocols has not been performed on judicious metrics. In this paper, we perform a simulation-based evaluation of three prominent CDS based protocols (CDS Rule K, EECDS and A3) on the basis of message and energy overhead, residual energy, number of unconnected nodes, and convergence time. Our analysis shows that the protocols’ performances vary significantly with different maintenance techniques and none of the existing protocols can outperform the others on all metrics. Based on this result, we identify some performance-improving guidelines for CDS-based topology discovery and utilize them to propose a new protocol, clique-based CDS discovery (CCDS). We show that CCDS provides considerably better performance than existing protocols in most operational scenarios.     

AN EFFICIENT DISTRIBUTED ALGORITHM FOR CONNECTED DOMINATING SET CONSTRUCTION IN WIRELESS SENSOR NETWORKS

Efficient broadcasting protocols based on Connected Dominating Set （CDS） are frequently used; hence the entire broadcast domain is restricted to nodes in the CDS. This letter proves that a node must be a CDS node, if its neighbors with larger keys cannot cover it together. Then a simple distributed CDS construction algorithm is proposed, which is more effective than the existing algorithms in reducing the dominating set size and the computation complexity at the same time. Simulation results also confirm this, especially in relatively dense networks.     

A Dominating-Set-Based Routing Scheme in Ad Hoc Wireless Networks

Efficient routing among a set of mobile hosts (also called nodes) is one of the most important functions in ad hoc wireless networks. Routing based on a connected dominating set is a promising approach, where the searching space for a route is reduced to nodes in the set. A set is dominating if all the nodes in the system are either in the set or neighbors of nodes in the set. In this paper, we propose a simple and efficient distributed algorithm for calculating connected dominating set in ad hoc wireless networks, where connections of nodes are determined by their geographical distances. We also propose an update/recalculation algorithm for the connected dominating set when the topology of the ad hoc wireless network changes dynamically. Our simulation results show that the proposed approach outperforms a classical algorithm in terms of finding a small connected dominating set and doing so quickly. Our approach can be potentially used in designing efficient routing algorithms based on a connected dominating set.     

Distributed Construction of Connected Dominating Set in Wireless Ad Hoc Networks

Connected dominating set (CDS) has been proposed as virtual backbone or spine of wireless ad hoc networks. Three distributed approximation algorithms have been proposed in the literature for minimum CDS. In this paper, we first reinvestigate their performances. None of these algorithms have constant approximation factors. Thus these algorithms cannot guarantee to generate a CDS of small size. Their message complexities can be as high as O(n ²), and their time complexities may also be as large as O(n ²) and O(n ³). We then present our own distributed algorithm that outperforms the existing algorithms. This algorithm has an approximation factor of at most 8, O(n) time complexity and O(nlogn) message complexity. By establishing the (nlogn) lower bound on the message complexity of any distributed algorithm for nontrivial CDS, our algorithm is thus message-optimal.     

Adaptive Filtering Algorithm in Clock Calibration System

In wireless sensor network (WSN), data transfer from source to the destination needs an optimized network with less energy consumption. However, the optimized network with connected dominating set (CDS) of graph theory plays an important role in WSN for virtual backbone network formation. The connected dominating set is NP-hard problem with larger in size. However, the problem of the size of the network and NP-hard makes the researchers concentrate to improve the algorithms for virtual backbone. In this paper, we propose a semigraph contiguous prevalent set (SCPS) algorithm for semigraph structure to reduce NP-hard and size of the virtual backbone. The virtual back bone with SCPS algorithm applies with various protocols such as AODV, DSR, and DSDV for performance evaluation. From simulation result, we observe the network parameters such as size, diameter, average hoping and waiting time between the nodes are reduced. The proposed SCPS construction method retains the best performance ratio of \((2 + \ln \Delta_{a} )|opt|,\) whereas \(|opt|\) is the size of any optimal adjacent dominating set (ADS) and \(\Delta_{a}\) is the maximum adjacent degree of all nodes of the network and has the low time complexity of O(n ² ), whereas n denotes the network size. Furthermore, the proposed SCPS virtual backbone in hardware implementation proves the network life time increases about 86% of 9 V battery of the node.     

Zone-based virtual backbone formation in wireless ad hoc networks

Efficient protocol for clustering and backbone formation is one of the most important issues in wireless ad hoc networks. Connected dominating set (CDS) formation is a promising approach for constructing virtual backbone. However, finding the minimum CDS in an arbitrary graph is a NP-Hard problem. In this paper, we present a novel zone-based distributed algorithm for CDS formation in wireless ad hoc networks. In this Zone algorithm, we combine the zone and level concepts to sparsify the CDS constructed by previous well-known approaches. Therefore, this proposed algorithm can significantly reduce the CDS size. Particularly, we partition the wireless network into different zones, construct a dominating tree for each zone and connect adjacent zones by inserting additional connectors into the final CDS (at the zone borders). Our comprehensive simulation study using a custom simulator shows that this zone-based algorithm is more effective than previous approaches. The number of nodes in the CDS formed by this Zone algorithm is up to around 66% less than that constructed by others. Moreover, we also compare the performance of Zone algorithm with some recently proposed CDS formation protocols in ns2 simulator.     

基于连通支配集的OBS网络多粒度业务疏导机制

针对目前光网络核心节点的交换速度无法匹配单波长的传输速度难以满足大量的业务请求而拥塞,为了提高核心节点交换效率使其具有大容量数据交换的能力,本文提出了一种基于连通支配集(CDS)的光突发交换(OBS)网络稀疏节点疏导机制(CDS-TG).主要思路是:首先在OBS核心网络中根据改进的连通支配集算法选取疏导节点;其次在疏导...