Coloured Petrinet for Modelling and Validation of Dynamic Transmission Range Adjustment Protocol for Ad Hoc Network

The IEEE 802.11 standard defines two operational modes for WLANs: infrastructure based and infrastructureless or ad hoc. A wireless ad hoc network comprises of nodes that communicate with each other without the help of any centralized control. Ad hoc implies that the network does not rely on a pre-existing infrastructure but rather each node participates in routing by forwarding data for other nodes. The decentralized nature improves the scalability of wireless ad hoc network as compared to wireless managed networks. Each node acts as either a host or router. A node that is within the transmission range of any other node can establish a link with the later and becomes its immediate neighbour. However, the nodes in the ad hoc networks are constrained with limited resources and computation capability. So it may not be possible for a node to serve more number of neighbours at some instant of time. This enforces a node to remain connected or disconnected with few of its existing neighbours supporting the dynamic restructuring of the network. The presence of dynamic and adaptive routing protocol enables ad hoc networks to be formed quickly. The Dynamic Transmission Range Adjustment Protocol (DTRAP) provides a mechanism for adjusting transmission range of the ad hoc nodes. They maintain a threshold number of registered neighbours based on their available resources. The node protects its neighbourhood relationship during data communication by controlling its transmission range. It registers or de-registers a communicating node as its neighbour by dynamically varying the transmission range. However a node has a maximum limit on its transmission range. If the distance between the node and its neighbour is less than the transmission range and; 1)if the number of neighbours of a node falls short of threshold value, the node dynamically increases its transmission range in steps until it is ensured of an optimal number of neighbours 2)if the number of neighbours of a node exceeds the threshold value, the node dynamically decreases its transmission range in steps until it is ensured of an optimal number of neighbours. Coloured Petri nets (CP-nets) is the modelling language tool used for systems having communication, synchronisation and resource sharing as significant aspects. It provides a framework for the design, specication, validation, and verication of systems. It describes the states in which the system may be in and the transition between these states. The CPN combines Petri nets and programming languages. Petri nets amalgamate the use of graphical notation and the semantical foundation for modelling in systems. The functional programming language standard ML provides the primitives for the definition of data types and manipulation of data values. Besides providing the strength of a graphical modelling language, CP-nets are theoretically well-founded and versatile enough to be used in practice for systems of the size and complexity of industrial projects

Analysis and Design of Protocols for Clustering in Mobile Ad Hoc Networks

Communication in mobile ad hoc networks (MANET) without having any fixed infrastructure has drawn much attention for research. The infrastructure based cellular architecture sets up base stations to support the node mobility. Thus, mapping the concepts of base stations into MANET could meet its challenges like limited battery power, scalability, available band width etc..This leads to the design of logical clusters, where the cluster heads in every cluster play the role of base station. The cluster heads also form the virtual back bone for routing the packets in the network. In this thesis, simulation based survey has been made to study the strengths and weaknesses of existing algorithms that motivated for the design of energy efficient clustering in MANET. Neighbour Detection Protocol (NDP) has been designed to help the nodes to probe their immediate neighbours. In this protocol, every node broadcasts its own information to the network, so that it is received by a node that lies within its transmission range. The receiver senses its neighbours and updates its neighbour table from time to time. This protocol is validated through simulation by using Colour Petri Nets (CPN) prior to its implementation. Topology Adaptive Clustering Algorithm (TACA) has been proposed, that uses the node mobility and its available battery power for calculating the node weights. A node having the highest weight among its immediate neighbours declares itself as the volunteeer cluster head. As the current head consumes its battery power beyond a threshold, non-volunteer cluster heads are selected locally. The algorithm aims to utilise the battery power in a fairly distributed manner so that the total network life time is enhanced with reduced cluster maintenance overhead. During the process of clustering, some isolated heads without having any members are formed. This increases the delay in communication as the number of hops in the routing back bone is increased. A ransmissiion Range Adjustment Protocol (TRAP) has been proposed, that allows the isolated nodes to adjust their ranges to remain connected with existing cluster heads. The results show that, TRAP reduces the delay in communication by reducing the number of cluster heads in the network. Validation for the base protocol NDP and algorithm TACA are made through simulation by using the CPN tools. Each of the proposed work is evaluated separately to analyse their performances and compared with the competent results

Modeling and performance analysis of AODV routing protocol using coloured petri nets

The growth of interest in mobile ad-hoc networks is increasing exponentially. In a Mobile Ad hoc Network(MANET), wireless transmissions can happen in such a way that mobile nodes can send messages directly to one another through wireless links. The protocols which establish their routes dynamically on demand are called reactive protocols. One of the such reactive protocols defined for MANETs is AODV (Ad hoc On-demand Distance Vector) routing protocol. Since the nodes are mobile in nature, the topology of the network does not remain constant, it keeps on changing frequently. Thus it is very much necessary for every node in the network to keep track of change so that an efficient packet transmission can be done. In this thesis, AODV is modeled using Coloured Petri nets, various performance measures like workload, number of packets sent and received, efficiency of the protocol are evaluated using monitors. The same routing protocol is again simulated using well known NS2 tool. The results of the modeled CPN are compared with NS2 simulator output. We have assumed that all the nodes have sufficient energy while participating in the routing process

A Review: Clumping in Mobile Adhoc Networks

ABSTRACT: Mobile ad hoc networks (MANETs) consist of mobile devices that form the wireless networks without any fixed infrastructure or centralized administration. The infrastructure based cellular architecture sets up base stations to support the node mobility. Mapping the concepts of base stations into MANET leads to the design of logical clump, where the clump heads in every clump play the role of base station. Clumping in MANET is the virtual partitioning of the dynamic nodes into various groups. In this paper, we have proposed protocols and algorithms for efficient design of clumping in MANET. Closer Clump Detection Protocol (CCDP) has been designed to help the nodes to probe their immediate neighbours. Energy Based Clumping Algorithm (EBCA) has been proposed that uses the node mobility and its available battery power for calculating the node weights. A Broadcasting Range Adjustment Protocol (BRAP) has been proposed which allows the isolated nodes to adjust their ranges to remain connected with existing clump heads. Each of the work is evaluated separately to analyse their performances and compared with the competent results

Novel Approaches for the Performance Enhancement of Cognitive Radio Networks

This research is dedicated to the study of the challenges faced by Cognitive Radio (CR) networks, which include self-coexistence of the networks in the spectral environment, security and performance threats from malicious entities, and fairness in spectrum contention and utilization. We propose novel channel acquisition schemes that allow decentralized CR networks to have multiple channel access with minimal spectrum contentions. The multiple channel acquisition schemes facilitate fast spectrum access especially in cases where networks cannot communicate with each other. These schemes enable CR networks to self-organize and adapt to the dynamically changing spectral environment. We also present a self-coexistence mechanism that allows CR networks to coexist via the implementation of a risk-motivated channel selection based deference structure (DS). By forming DS coalitions, CR networks are able to have better access to preferred channels and can defer transmission to one another, thereby mitigating spectrum conflicts. CR networks are also known to be susceptible to Sybil threats from smart malicious radios with either monopolistic or disruptive intentions. We formulate novel threat and defense mechanisms to combat Sybil threats and minimize their impact on the performance of CR networks. A dynamic reputation system is proposed that considerably minimizes the effectiveness of intelligent Sybil attacks and improves the accuracy of spectrum-based decision-making processes. Finally, we present a distributed and cheat-proof spectrum contention protocol as an enhancement of the adaptive On-Demand Spectrum Contention (ODSC) protocol. The Modified On-Demand Spectrum Contention (MODSC) protocol enhances fairness and efficiency of spectrum access. We also show that there is substantial improvement in spectrum utilization with the incorporation of channel reuse into the MODSC protocol