Virtual Backbone In Wireless Networks Research Articles

On construction of quality virtual backbone in wireless networks using cooperative communication

An extended connected dominating set (ECDS) in a wireless network with cooperative communication (CC) is a subset of nodes such that its induced subgraph is connected and each node outside the ECDS is covered by either one neighbor or several quasineighbors in the ECDS. Traditionality, the size of virtual backbone (VB) is the only factor considered in the problem of CDS construction. However, diameter is also an important factor to evaluate VB. In this paper we consider the problem of constructing quality ECDSs in unit disk graphs under CC with both of these two factors. We propose a two-phase centralized algorithm BD-ECDS to construct an ECDS for a given UDG with CC, which has a constant performance ratio (PR) and diameter. To obtain the PR of this two-phase centralized algorithm, we first give an upper bound of the EDS and use this upper bound to prove that the size of the ECDS under CC generated by the centralized algorithm is no greater than 120|ECDSopt|−2, where ECDSopt is the size of the minimum ECDS. Furthermore, our theoretical analysis and simulation results show that our algorithm BD-ECDS is superior to previous approaches.

Efficient Connected Dominating Set Construction with Maximum Lifetime in the Cognitive Radio Networks

Connected dominating set (CDS) is the most representative technology for constructing a virtual backbone in wireless networks and plays an important role in wireless applications including broadcasting, routing and so on. In a cognitive radio networks, the lifetime and efficiency are two important indices for measuring CDS algorithms due to the random activities of primary users (PUs). However, to the best of our knowledge, the existing algorithms for CDS construction in CRNs ignore the execution effectiveness instead of lifetime. In this paper, we propose a four-phase distributed algorithm to maximize the lifetime of CDS while guaranteeing the effectiveness of the algorithm. The proposed algorithm terminates in O(N3 log N) timeslots, which is more effective than that of O(N4).

Construction of higher spectral efficiency virtual backbone in wireless networks

One promising solution to improve the efficiency of wireless networks is to control the number of nodes involved in multi-hop routing by employing virtual backbone. On the one hand, a virtual backbone becomes more efficient as its size is getting smaller. However, as the size of a virtual backbone is getting smaller, the throughput of the virtual backbone is degraded since the length of a routing path between a pair of nodes through the virtual backbone can be much longer than their hop distance in the original network. Due to the reason, several efforts are recently made to identify a virtual backbone including a shortest path between every pair of nodes in the original graph. In this paper, we investigate a new strategy to compute higher throughput virtual backbone in wireless networks. We employ a new information theoretic metric called spectral-efficiency by Chen et al. and propose a new virtual backbone computation algorithm in homogeneous wireless networks with some interesting theoretical analysis. Our simulation results indicate our algorithm produces a virtual backbone with higher spectral-efficiency than the existing alternatives. We also conduct another simulation using OMNet++ and show the virtual backbone produced by our algorithm has the highest throughput.

On dominating sets whose induced subgraphs have a bounded diameter

We study dominating sets whose induced subgraphs have a bounded diameter. Such sets were used in recent papers by Kim et al. and Yu et al. to model virtual backbones in wireless networks where the number of hops required to forward messages within the backbone is minimized.We prove that for any fixed k≥1 it is NP-complete to decide whether a given graph admits a dominating set whose induced subgraph has diameter at most k.On the upside, we give a characterization of the chordal graphs that admit such a dominating set. It turns out that in this characterization, the dominating set X can be chosen such that any shortest path between two members of the dominating set is entirely contained in X. Moreover, the characterization yields an O(mn) algorithm to compute, for a given connected chordal graph G on n vertices and m edges, the minimum k for which G has a dominating set whose induced subgraph has diameter at most k. Such a dominating set can be efficiently computed.

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.

构建最小<italic>k</italic> 重控制集的概率算法

A k -fold dominating set of a graph G is a node subset D of V ( G ) such that every node in V ( G )- D has at least k neighbors in D . Minimum k -fold dominating sets (M k DS) are utilized to build robust virtual backbones in wireless networks. In this paper, we propose a fast distributed probabilistic algorithm to construct an M k DS. The expected size of the k -dominating set which we construct is no more than O ( k 2 ) times of the optimal, and the time complexity is O ((Δ logΔ + log log n ) n ), where Δ = max | D ( p )|, D ( p ) is the set of nodes falling into the disk with center p and radius 1, and the maximum is taken over all p in the given set.

ANALYSIS ON THEORETICAL BOUNDS FOR APPROXIMATING DOMINATING SET PROBLEMS

Connected Dominating Set is widely used as virtual backbone in wireless networks to improve network performance and optimize routing protocols. Based on special characteristics of ad-hoc and sensor networks, we usually use unit disk graph to represent the corresponding geometrical structures, where each node has a unit transmission range and two nodes are said to be adjacent if the distance between them is less than 1. Since every Maximal Independent Set (MIS) is a dominating set and it is easy to construct, we can firstly find an MIS and then connect it into a Connected Dominating Set (CDS). Therefore, the ratio to compare the size of an MIS with a minimum CDS becomes a theoretical upper bound for approximation algorithms to compute CDS. In our paper, with the help of Voronoi diagram and Euler's formula, we improved this upper bound, so that improved the approximations based on this relation.

On the construction of 2-connected virtual backbone in wireless networks

Virtual backbone has been proposed as the routing infrastructure to alleviate the broadcasting storm problem in ad hoc networks. Since the nodes in the virtual backbone need to carry other node's traffic, and node and link failure are inherent in wireless networks, it is desirable that the virtual backbone is fault tolerant. In this paper, we propose a new algorithm called Connecting Dominating Set Augmentation (CDSA) to construct a 2-connected virtual backbone which can resist the failure of one wireless node. We show that CDSA has guaranteed quality by proving that the size of the CDSA constructed 2-connected backbone is within a constant factor of the optimal 2-connected virtual backbone size. Through extensive simulations, we demonstrate that in practice, CDSA can build a 2-connected virtual backbone with only small overhead.