Information Sciences,

Caching techniques can be used to reduce bandwidth consumption and data access delay in wireless ad hoc networks. When cache is used, cache consistency issues must be addressed. To maintain strong cache consistency in some strategic scenarios (e.g., battle fields), the invalidationbased approach is preferred due to its low overhead. However, this approach may suffer from some security attacks. For example, a malicious node (intruder) may drop, insert or modify invalidation messages to mislead the receivers to use stale data or unnecessarily invalidate the data that is still valid. In this paper, we propose a solution based on the IR-based cache invalidation strategy to prevent intruders from dropping or modifying the invalidation messages. Although digital signatures can be used to protect IRs, it has significantly high overhead in terms of computation and bandwidth consumption. To address this problem, we propose a family of randomized grouping based schemes for intrusion detection and damage recovery. Extensive analysis and simulations are used to evaluate the proposed schemes. The results show that our solution can achieve a good level of security with low overhead.

Abstract—Ad hoc networks are characterized by multihop wireless connectivity, frequently changing network topology and the need for efficient dynamic routing protocols. We compare the performance of three routing protocols for mobile ad hoc networks: Dynamic Source Routing (DSR), Ad Hoc On-Demand Distance Vector Routing (AODV), location-aided routing (LAR1).Our evaluation is based on energy consumption in mobile ad hoc networks. The performance differentials are analyzed using varying network load, mobility, and network size. We simulate protocols with GLOMOSIM simulator. Based on the observations, we make recommendations about when the performance of either protocol can be best. Keywords—Ad hoc Network, energy consumption, Glomosim, routing protocols.

A mobile ad hoc network is a collection of wireless terminals that can be deployed rapidly. Its deficiencies include limited wireless bandwidth efficiency, low throughput, large delays, and weak security. Integrating it with a wellestablished cellular network can improve communication and security in ad hoc networks, as well as enrich the cellular services. This research proposes a cellular-aided mobile ad hoc network (CAMA) architecture, in which a CAMA agent in the cellular network manages the control information, while the data is delivered through the mobile terminals (MTs). The routing and security information is exchanged between MTs and the agent through cellular radio channels. A position-based routing protocol, the multi-selection greedy positioning routing (MSGPR) protocol, is proposed. At times due to the complicated radio environment, the position information is not precise. Even in these cases, the MT can still find its reachable neighbors (the association) by exchanging "hello" messages. This association is used in complement with the position information to make more accurate routing decisions. Simulation results show that the delivery ratio in the ad hoc network is greatly improved with very low cellular overhead. The security issues in the proposed architecture and the corresponding solutions are addressed. The experimental study shows that CAMA is much less vulnerable than a pure ad hoc network.

Abstract Recently, it became apparent that group-oriented services are one of the primary applicationclasses targeted by MANETs. As a result, several MANET-specific multicast routing protocols have been proposed. Although these protocols perform well under specific mobility scenarios,traffic loads and network conditions, no single protocol has been shown to be optimal in all scenarios. The goal of this paper is to characterize the performance of multicast protocols overa wide range of MANET scenarios. To this end, we evaluate the performance of mesh- and treebased multicast routing schemes relative to flooding and recommend protocols most suitable forspecific MANET scenarios. Based on the analysis and simulation results, we also propose two variations of flooding:scoped flooding and hyper flooding as means to reduce overhead and increase reliability, respectively. Another contribution of the paper is a simulation-based comparative study of theproposed flooding variations against plain flooding, mesh-, and tree-based MANET routing. In our simulations, in addition to "synthetic " scenarios, we also used more realistic MANETsettings, such as conferencing and emergency response. Key Words: Ad-Hoc Networks, Mobile Computing, Multicast, Routing protocols, Wireless 1 Introduction Mobile multi-hop ad hoc networks (MANETs) are characterized by lack of any fixed network infrastructure. In a MANET, there is no distinction between a host and a router, since all nodes can be sources as well as forwarders of traffic. Moreover, all MANET components can be mobile.

Using location information to help routing is often proposed as a means to achieve scalability in large mobile ad-hoc networks. However, location based routing is difficult when there are holes in the network topology and nodes are mobile. Terminode routing, presented here, addresses these issues. It uses a combination of location based routing (Terminode Remote Routing, TRR), used when the destination is far, and link state routing (Terminode Local Routing, TLR), used when the destination is close. TRR uses anchored paths, a list of geographic points (not nodes) used as loose source routing information. Anchored paths are discovered and managed by sources, using one of two low overhead protocols: Friend Assisted Path Discovery and Geographical Map-based Path Discovery. Our simulation results show that terminode routing performs well in networks of various sizes. In smaller networks, the performance is comparable to MANET routing protocols. In larger networks that are not uniformly populated with nodes, terminode routing outperforms existing location-based or MANET routing protocols.

Owing to limited bandwidth, how to reduce the control overhead of routing protocols is an important issue in mobile ad hoc networks. In this paper, an Efficient and Robust Location-Aided Route Protocol (ER_LAR) is proposed. The ER_LAR includes Sector-Broadcast Mechanism, Route Maintenance, and Bi-directional Route Repair.

hoc networks are collections of mobile nodes with links that are made or broken in an arbitrary way. They have no fixed infrastructure and, usually, have constrained resources. The next generation of IT applications is expected to rely heavily on such networks. However, before they can be successfully deployed several major security threats must be addressed. These threats are due mainly to the ad hoc nature of such networks. As a result it may be much harder (or even impossible) to establish routing paths that can tolerate Byzantine faults. Recently a Byzantine faults tracing protocol has been proposed. This combines a reliability metric based on passed history with an adaptive probing technique. In this paper we first show that such an approach is fundamentally flawed and cannot be used to detect malicious faults. We then propose a new tracing algorithm that exploits a basic property of broadcast channels, ping channels, and authentication mechanisms, to locate Byzantine faults.

Patiala, is an authentic record of my own work carried out under the supervision of Mr. Anil Kumar Verma. The matter presented in this thesis has not been submitted for the award of any other degree of this or any other university.

We designed the terminode routing protocol with the objective to scale in large mobile ad hoc networks where the topology, or node distribution, is irregular. Our routing protocol is a combination of two protocols: Terminode Local Routing (TLR- to reach a close destination) and Terminode Remote Routing (TRR- to send data to remote destinations). TRR is the key element to achieve scalability and reduce dependence on intermediate systems. Terminode routing uses anchored paths, a list of geographic points- that are not affected by nodes mobility-, rather than conventional paths of nodes. Terminode routing is completed by a low-overhead distributed method for discovering of anchored paths, and by a method for handling the inaccuracy of the location information. The presented simulation results confirm that terminode routing performs well in different sized networks. In smaller ad hoc networks performance of terminode routing is comparable to MANET routing protocols. In larger networks, where MANETlike routing protocols break, terminode routing performs well; moreover, in larger networks that are not uniformly populated with nodes, terminode routing outperforms the existing location-based routing protocols.