A Distributed Virtual Backbone Development Scheme for Ad-Hoc Wireless Networks

Due to node mobility, the ad hoc network topology is dynamical so that on-demand routing protocols are more fit than other routing protocols. Most secure on-demand routing protocols are designed that the destination or source is able to detect the attacks on routing paths after accepting routing requests or routing replies. In this paper, we present a secure on-demand source routing protocol without the assumption of a specific cryptographic system provides per-hop broadcast authentication in routing discovery phase and security in communication phase and takes effect on our trust-based ad hoc environment. Our hop by hop broadcast authentication provides forwarding routing packets with their trust levels for abstaining from unreliable or malicious nodes. Through security analysis and discussion, we characterize our mechanism and show that it is effectively and efficiently.

The on-demand routing schemes in mobile ad hoc networks are appealing because of the lower routing overhead, compared with traditional proactive schemes. The on-demand routing protocols introduce routing overhead only in the presence of data packets that need routes. However, the control overhead of on-demand routing schemes increases with node geographic density and traffic pattern density. In fact, this is an undesirable feature for the scalable routing protocols whose control overhead should be under control to keep up with increasing offered load. As a solution for such a drawback of current reactive routing schemes, we propose the selective intermediate nodes mechanism. In this protocol, each node adaptively propagates routing information based on the local load level and cluster status. The local load level (local load status), based on channel utilization and queue size, reflects the load of the node in question and of all of its neighbors; the cluster status denotes the role of a node in a cluster (i.e., a cluster head, gateway or ordinary node). We demonstrate the effectiveness of our enhancement by applying it to ad hoc on-demand distance vector routing (AODV) and dynamic source routing (DSR). Simulation results show that the proposed idea significantly reduces the control overhead and improves the overall performance and scalability of the routing protocols.

Ad hoc networking is one of the enabling technologies for wireless pervasive computing. We study the issue of constructing an energy-efficient virtual backbone for broadcast communication in wireless ad hoc networks. When nodes use constant and identical transmission power, energy-efficient broadcasting amounts to minimizing the backbone size. Typically, algorithms for backbone construction rely on either adding nodes to the backbone, or pruning nodes from the backbone. We present a distributed hybrid algorithm in which a node is allowed to join the backbone as well as to prune itself from the backbone. In addition, a node may perform these two types of operations repeatedly, if necessary. We present numerical experiments in which we evaluate the performance of the distributed hybrid algorithm and several other algorithms. The experiments show that our algorithm performs well in terms of constructing a backbone of small size. Moreover, the number of times that the algorithm repeats its steps before converging to a stable backbone is small in relation to backbone size.

An Efficient Backbone Based Quick Link Failure Recovery Multicast Routing Protocol

Now a days, mobile users like to use their own consumer electronic devices anywhere and at anytime to access multimedia data. Consumer electronic devices have evolved depending on user needs. Users want to use compact and portable devices such as cellular phones, laptop computers, Personal Digital Assistants (PDAs), etc. anywhere and at anytime to download multimedia data or to access realtime traffic. The mobile Ad Hoc networks have several salient characteristics, such as Dynamic topologies, Bandwidth-constrained, Variable capacity links, Energy-constrained operation and Limited physical security. Due to these features, mobile Ad Hoc networks are particularly vulnerable to denial of service attacks launched through compromised node. The communication in mobile AdHoc networks comprises of two phases, the route discovery and the data transmission. In a hostile environment, adversarial nodes can try to disrupt communication in both the two phases. However, consumer electronic devices generally operate on limited battery power and therefore are vulnerable to security threats like data flooding attacks. Flooding attack is a novel and powerful attack against on-demand Ad Hoc routing protocols. At present, FAP (Flooding Attack Prevention) is the single scheme proposed to resist such attack. But it may not give quality of service. In this paper, we present a Period Based Defense mechanism against data flooding attack in wireless AdHoc network. This is the new technique to defend the flooding attack. This scheme is based on the periods and uses a blacklist to efficiently prevent the data flooding attack. The main aim of this paper is to enhance the throughput of burst traffic. As a result of which, many data packets are forwarded at a high rate for the whole duration. The simulation results show that the proposed scheme enhances the throughput of burst traffic.

We consider the minimum energy unicast problem in ad-hoc wireless networks. A source node wants to transmit a sequence of messages to a single destination node. Other nodes in the network may operate as relay nodes. The problem is to do this with the minimum overall power consumption in the network. In this paper we investigate the power saving that can be achieved by using advanced relay-channel signaling rather than traditional multi-hop routing. Under the assumptions that carrier level synchronization is not available and every intermediate node uses a decode-forward scheme, we show that any optimal relaying structure can be converted to a sequential path, for which we find a simple optimal power-allocation policy. Finding an optimal sequential path is still complex, and we therefore present two polynomial heuristic algorithms to find good cooperative routes. Our simulation results show that they can achieve average power savings of up to 3 dB for a network size of 60 nodes in low attenuation regimes. For high attenuation regimes, cooperative routing exhibits limited gain and traditional multi-hop operation is a reasonable choice.

In wireless mobile ad-hoc networks, data packets have to be relayed hop by hop from a given source node to a destination node. This means that some or all of the mobile nodes must accept to forward information for the benefit of other nodes. It has been shown by F. Nait-Abdesselam, et al., (2003) that this ability of forwarding packets leads to a new unfairness problem in wireless ad-hoc networks, where a node which is forwarding other node's packets gets less bandwidth, for its own use, than a node which is not participating to the routing service. The proposed RAMAC scheme by F. Nait-Abdesselam, et al., (2003), has shown all its effectiveness to cope with this unfairness problem. However, an extra bandwidth is sometimes allowed to the routing node's own traffic comparing to other nonrouting node's own traffics, and the routing node's routed traffic gets much less bandwidth. This is explained by the fact that at the upper layer (for instance the IP layer) does not differentiate between the routing and the own traffics, and that the multiplicative factor used to compute the new contention window is too aggressive. In this paper, an enhanced RAMAC scheme is proposed, by taking into account the differentiation on top of the MAC layer, between the and routed traffics within a routing node, and by smoothing the multiplicative factor used to compute the new contention window. The simulation results obtained showed a good improvement of the original RAMAC scheme, leading to better approximate equal bandwidth share among all the mobile nodes in the wireless ad-hoc network.

The development of practical, localization algorithms is probably the most needed and most challenging task in wireless ad-hoc sensor networks (WASNs). Localized algorithms are a special type of distributed algorithms where only a subset of nodes in the WASN participate in sensing, communication, and computation. We have developed a generic localized algorithm for solving optimization problems in wireless ad-hoc networks that has five components: (i) data acquisition mechanism, (ii) optimization mechanism, (iii) search expansion rules, (iv) bounding conditions and (v) termination rules. the main idea is to request and process data only locally and only from nodes who are likely to contribute to rapid formation of the final solution. The approach enables two types of optimization: The first, guarantees the fraction of nodes that are contacted while optimizing for solution quality. The second, provides guarantees on solution qualities while minimizing the number of nodes that are contacted and/or amount of communication. The localized optimization approach is applied to two fundamental problems in sensor networks: location discovery and exposure-based coverage. We demonstrate its effective-ness on a number of examples

Wireless ad hoc networks are an emerging and popular technology to the world; however, the benefits of them are actually their fragility, too. Owing to mobile node movement, the link break problem always occurs in the network. The problem greatly influences the throughput, delay, jitter, and lots of performance issues of a routing protocol. Hence, this article is proposed to evaluate the influence of link break problem on two categories of most popular routing protocols, i.e. table-driven and on-demand routing protocols. This article briefly discusses the main differences, building up mathematical model, setting up simulation environment, running the simulation, and finally presenting the simulation results and analyzing the performance. We found that the update probability of table-driven routing protocols increase exponentially with the number of mobile nodes but linearly with moving speed. On the contrary, the update probability of on-demand routing protocol increase both linearly with the number of mobile nodes and moving speed. We conclude that the effect of link break problem on table-driven routing protocols is much serious than that on on-demand routing protocols since the former has to maintain each link of the network but the latter only the links of a specific route. Table-driven routing protocols are not scalable; however, on-demand routing protocols are.

The term wireless Ad Hoc network is used for the type of network that is established between communicating nodes for the specified period of time. After sometime, the nodes involve in the network move to the other location. This happens due to the wireless ad hoc network is made up of multiple mobile nodes. However, each time user changes location, the device of the user become hidden for the other nodes involved in the network to which the user’s node was connected. This sometimes becomes large problem named collision. This study provides the information related to hidden node problem and it also enlists some of the mechanism to avoid the hidden node problem. Moreover, if the hidden node problem occurred in network, even if after applying these mechanism some of the solutions to be applied to solve this problem. This study discussed about some of the protocols called MAC protocols to solve Hidden problems in wireless networks.

In this paper, we consider a mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Mobile nodes outside the transmission range of the gateway can continue to communicate with the gateway via their neighboring nodes over multihop paths. On-demand routing schemes are appealing because of their low routing overhead in bandwidth restricted mobile ad hoc networks, however, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the ad hoc on-demand distance vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Simulation results show that as traffic increases, our proposed LB-AODV routing protocol has a significantly higher packet delivery fraction, a lower end-to-end delay and a reduced routing overhead when compared with both AODV and gossip-based routing protocols.

Routing problems in mobile ad-hoc networks (MANET) have been receiving increasing attention in the last few years. Most of the proposed routing protocols concentrate on finding and maintaining routes in the face of changing topology caused by mobility or other environmental changes. More recently, power-aware routing protocols and topology control algorithms have been developed to address the issue of limited energy reserve of the nodes in ad-hoc networks. We consider the routing problem in MANET with the goal of maximizing the life time of the network. We propose a distributed routing algorithm that reaches the optimal (centralized) solution to within an asymptotically small relative error. Our approach is based on the formulation of multicommodity flow, and it allows to consider different power consumption models and bandwidth constraints. It works for both static and slowly changing dynamic networks.

Recent development has a tremendous growth in the ad-hoc wireless networks. Ad-hoc wireless networks are dynamic topology networks organized by a collection of mobile nodes that utilize multi-hop radio relaying and are capable of operating without the support of any fixed infrastructure. Ad-hoc wireless networks are very useful in emergency operations, collaborative and distributed computing and military applications. Multicasting plays an important role in the ad-hoc wireless networks, where nodes form groups to carry out certain tasks that require point-to-multipoint and multipoint-to-multipoint voice and data communication. The biggest challenge in the ad-hoc wireless networks is to find an optimized path between the two nodes. In this paper, we present an ant colony based metaheuristic multicast routing protocol for ad-hoc wireless networks, in that we analyzed the performance of dynamic core based multicast routing protocol (DCMP). This approach maps the solution capability of swarm intelligence to mathematical and engineering problems. The DCMP is highly adaptive, efficient and scalable. The performance of these protocols has been examined under realistic scenarios using NS 2, the network simulator tool. Performance has been analyzed for the metrics packet delivery ratio and control overheads with the multicast routing protocol. The proposed ant colony based routing protocol reduce the overheads in routing.

A selection problem is among the basic communication primitives in networks. In this problem at most k participating stations have to broadcast successfully their messages. This problem is especially important in packet radio networks, where simultaneous transmissions of many neighbors result in interference among delivered messages. This work focuses on a single-hop radio networks with n-stations, also called a multiple access channel, and considers both static and dynamic versions of the selection problem. We construct a family of efficient oblivious deterministic protocols based on selectors, one of them with selection time cO(klog(n/k)), and the second explicit construction with selection time cO(k polylog n). The first construction matches the lower bound Ω(klog(n/k)) on deterministic oblivious selection, while the second one is the first known explicit construction better than Θ(k2). In the dynamic case we introduce the model of dynamic requests, called k-streams, which generalizes the static model and the dynamic requests with at most k participants. We prove that each oblivious deterministic protocol has latency Ω(k2/log k), and on the other hand we prove the existence of the oblivious deterministic protocol with latency cO(k2log n). In view of the existence of the randomized oblivious protocol with expected latency cO(klog(n/k)), this shows that randomization is substantially better than determinism for dynamic setting. Selection problem can be applied to implement other communication primitives --- we demonstrate it in the example of broadcast problem in multi-hop ad-hoc radio networks. In particular, we design an adaptive deterministic protocol broadcasting in time cO(nlog D) in every D-hop radio network of n-stations.

A wireless sensor network (WSN) is a collection of energy constrained sensor node forming a network which lacks infrastructure or any kind of centralized management. In such networks, virtual backbone has been proposed as the routing infrastructure which can alleviate the broadcasting storm problem occurring due to consistent flooding performed by the sensor node, to communicate their sensed information. As the virtual backbone nodes needs to carry other nodes’ traffic, they are more subject to failure. Hence, it is desirable to construct a fault tolerant virtual backbone. Most of recent research has studied this problem in homogeneous networks. In this chapter, we propose solutions for efficient construction of a fault tolerant virtual backbone in a WSN where the sensor nodes have different transmission ranges. Such a network can be modeled as a disk graph (DG), where link between the two nodes is either unidirectional or bidirectional. We formulate the fault tolerant virtual backbone problem as a k-Strongly Connected m-Dominating and Absorbing Set (k, m) SCDAS problem. As the problem is NP-hard, we propose an approximation algorithm along with the theoretical analysis and conjectured its approximation ratio.