Wireless Ad Hoc And Sensor Networks Research Articles

A Distributed Evolutionary algorithm for detecting minimum vertex cuts for wireless ad hoc and sensor networks

A minimum vertex cut (MVC) of a graph G is the smallest subset of vertices whose removal creates at least two disconnected group of other vertices. Detecting nodes in MVCs in wireless ad hoc and sensor networks (WASNs) provides valuable information about their robustness and critical parts. There is a wide variety of central algorithms that find or estimate MVCs of graphs, but to the best of our knowledge the existing distributed algorithms can only estimate the cardinality of MVCs, or k, from local neighborhood information. Regardless of the fact that MVCs remain unknown in these algorithms, local estimation of k may produce wrong values, far from the real k. We propose a distributed algorithm, which uses an adapted meta heuristic method, to detect the nodes in MVCs. In the proposed algorithm, all nodes find their available paths to the sink (root node) and determine the minimum subset of nodes that their failure disconnects all detected paths. The smallest detected sets by the nodes will be MVCs of the WASN. Besides finding the union of MVCs with up to 89% average accuracy, the testbed and simulation results show that the correct detection ratio of k in the proposed algorithm is up to 37% more than the existing distributed algorithms.

Incorporating privacy and security in military application based on opportunistic sensor network

Wireless ad-hoc and sensor networks (WASN) or opportunistic sensor networks (Oppnets) have been improving their availability in providing secure communication between military candidates in military applications. The existing work has not addressed this issue effectively. This paper proposes secure route selection and three different encryption algorithms for Commando-Commando (CC), Soldier-Soldier (SS) and Commando-Soldier (CS) communication. Routing is based on path protected hop-by-hop routing protocol (PPHH) by which a secure path is selected with authentication by certificate authority (CA). The cryptography algorithms used are code-based cryptography, hyperelliptic curve cryptography, and design-based cryptography. The proposed strategy in this paper shows improvements in security, energy consumption, throughput, packet overhead and network reliability.

Directional Medium Access Control (MAC) Protocols in Wireless Ad Hoc and Sensor Networks: A Survey

This survey paper presents the state-of-the-art directional medium access control (MAC) protocols in wireless ad hoc and sensor networks (WAHSNs). The key benefits of directional antennas over omni-directional antennas are longer communication range, less multipath interference, more spatial reuse, more secure communications, higher throughput and reduced latency. However, directional antennas lead to single-/multi-channel directional hidden/exposed terminals, deafness and neighborhood, head-of-line blocking, and MAC-layer capture which need to be overcome. Addressing these problems and benefits for directional antennas to MAC protocols leads to many classes of directional MAC protocols in WAHSNs. These classes of directional MAC protocols presented in this survey paper include single-channel, multi-channel, cooperative and cognitive directional MACs. Single-channel directional MAC protocols can be classified as contention-based or non-contention-based or hybrid-based, while multi-channel directional MAC protocols commonly use a common control channel for control packets/tones and one or more data channels for directional data transmissions. Cooperative directional MAC protocols improve throughput in WAHSNs via directional multi-rate/single-relay/multiple-relay/two frequency channels/polarization, while cognitive directional MAC protocols leverage on conventional directional MAC protocols with new twists to address dynamic spectrum access. All of these directional MAC protocols are the pillars for the design of future directional MAC protocols in WAHSNs.

BOOTSTRAP PERCOLATION ON RANDOM GEOMETRIC GRAPHS

Bootstrap percolation (BP) has been used effectively to model phenomena as diverse as emergence of magnetism in materials, spread of infection, diffusion of software viruses in computer networks, adoption of new technologies, and emergence of collective action and cultural fads in human societies. It is defined on an (arbitrary) network of interacting agents whose state is determined by the state of their neighbors according to a threshold rule. In a typical setting, BP starts by random and independent “activation” of nodes with a fixed probabilityp, followed by a deterministic process for additional activations based on the density of active nodes in each neighborhood (θ activated nodes). Here, we study BP on random geometric graphs (RGGs) in the regime when the latter are (almost surely) connected. Random geometric graphs provide an appropriate model in settings where the neighborhood structure of each node is determined by geographical distance, as in wirelessad hocand sensor networks as well as in contagion. We derive boundspc′,pc″ on the critical thresholds such that for allp > p″cfull percolation takes place, whereas forp < p′cit does not. We conclude with simulations that compare numerical thresholds with those obtained analytically.

Construction of low weighted and fault-tolerant topology for wireless ad hoc and sensor network

To preserve network connectivity is an important issue especially in wireless ad hoc and sensor networks (WASN), where wireless links are easy to be disturbed and tiny sensors are very easy to fail accidently. Therefore, it is necessary to design a fault–tolerant network. A feasible method is to construct a k–connected (k–vertex connected) topology. In this paper, we consider k–connectivity of wireless network and propose a simple global algorithm (GAFTk) which preserves the network k–connectivity and reduces the maximal transmission power (TP). The average degree expectation of the topology generated by GAFTk is O ((k + 3)²) and the expected weight is O( (k+3)² ) 12(√πnnε) Based on GAFTk, we further propose an efficient localised algorithm (LAFTk) which preserves k–vertex connectivity while maintaining bi–directionality of the network. In addition, both algorithms achieve significant reductions in energy consumption. Our simulation results show that GAFT/LAFT have better performance than some other current fault–tolerant protocols.

Effect of Multipath Fading and Propagation Environment on the Performance of a Fermat Point Based Energy Efficient Geocast Routing Protocol

Energy efficiency is a much talked about thing in the domain of geocast routing protocols for Wireless Ad Hoc and Sensor Networks (WASNs). Fermat point based protocols are capable of reducing the energy consumption of a WASN by reducing the total transmission distance in a multi hop-multi sink scenario. Presently, there are quite a handful of them but many of them have not considered the effect of changing propagation environment around the considered network while measuring the performance of the protocol. Congested environment around a WASN increases the chance of multipath propagation and it in turn introduces multipath fading. In this paper, the effects of both of these factors are considered on the performance of I-Min routing protocol designed for WASNs.

I-Min: An Intelligent Fermat Point Based Energy Efficient Geographic Packet Forwarding Technique for Wireless Sensor and Ad Hoc Networks

Energy consumption and delay incurred in packet delivery are the two important metrics for measuring the performance of geographic routing protocols for Wireless Adhoc and Sensor Networks (WASN). A protocol capable of ensuring both lesser energy consumption and experiencing lesser delay in packet delivery is thus suitable for networks which are delay sensitive and energy hungry at the same time. Thus a smart packet forwarding technique addressing both the issues is thus the one looked for by any geographic routing protocol. In the present paper we have proposed a Fermat point based forwarding technique which reduces the delay experienced during packet delivery as well as the energy consumed for transmission and reception of data packets.

RF-Power Overlapping Control for Connectivity Awareness in Wireless Ad-Hoc and Sensor Networks

In this paper a novel power control scheme for establishing end-to-end connectivity over Wireless Ad-Hoc and Sensor Networks (WASN) is presented. Based on a deterministic connectivity model, the proposed scheme exploits overlapping information related to the properties of the network's Delaunay graph and localization. Sufficient conditions for establishing end-to-end connectivity over the WASN are provided; these are strongly attached to the properties of the network's Delaunay graph, formed by the nodes’ spatial distribution. Under the provision of the Delaunay-related overlapping information to the network's operating nodes, these sufficient conditions are utilized for the construction of a distributed Shortest Path-like algorithm. Without any additional network interaction, the resulting Distributed Delaunay Connectivity Algorithm (DDelCA) is capable of adjusting the nodal transmission power to the minimum value that establishes the network's end-to-end connectivity. Extensive simulation results are offered to evaluate the network's performance using the DDelCA transmission power configuration and highlight the benefits of the DDelCA scheme.