Asad Amir Pirzada

Performance comparison of trust-based reactive routing protocols

Ad hoc networks, due to their improvised nature, are frequently established in insecure environments and hence become susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. A number of secure routing protocols have recently been proposed, which make use of cryptographic algorithms to secure the routes. However, in doing so, these protocols entail a number of prerequisites during both the network establishment and operation phases. In contrast, trust-based routing protocols locate trusted rather than secure routes in the network by observing the sincerity in participation by other nodes. These protocols thus permit rapid deployment along with a dynamically adaptive operation, which conforms with the current network situation. In this paper, we evaluate the performance of three trust-based reactive routing protocols in a network with varying number of malicious nodes. With the help of exhaustive simulations, we demonstrate that the performance of the three protocols varies significantly even under similar attack, traffic, and mobility conditions. However, each trust-based routing protocol has its own peculiar advantage making it suitable for application in a particular extemporized environment.

Trust Establishment In Pure Ad-hoc Networks

An ad-hoc network is a set of limited range wireless nodes that function in a cooperative manner so as to increase the overall range of the network. Each node in the network pledges to help its neighbours by passing packets to and fro, in return of a similar assurance from them. All is well if all participating nodes uphold such an altruistic behaviour. However, this is not always the case and often nodes are subjected to a variety of attacks by other nodes. These attacks range from naive passive eavesdropping to vicious battery draining attacks. Routing protocols, data, battery power and bandwidth are the common targets of these attacks. In order to overcome such attacks a number of routing protocols have been devised that use cryptographic algorithms to secure the routing mechanism, which in turn protects the other likely targets. A limiting requirement regarding these protocols is the reliance on an omnipresent, and often omniscient, trust authority. In our opinion, this reliance on a central entity is against the very nature of ad-hoc networks, which are supposed to be improvised and spontaneous. We present in this paper, a trust-based model for communication in ad-hoc networks that is based on individual experience rather than on a third party advocating trust levels. The model introduces the notion of belief and provides a dynamic measure of reliability and trustworthiness in pure ad-hoc networks.

Wireless Mesh Networks for Public Safety and Crisis Management Applications

Wireless mesh networks (WMNs) are multihop wireless networks with self-healing and self-configuring capabilities. These features, plus the ability to provide wireless broadband connectivity at a comparatively low cost, make WMNs a promising technology for a wide range of applications. While discussing the suitability of WMN technology for public safety and crisis management communication, this article highlights its strengths and limitations and points to current and future research in this context.

Evaluation of multi-radio extensions to AODV for wireless mesh networks

Due to their self-configuring and self-healing capabilities, as well as their low equipment and deployment cost, Wireless Mesh Networks (WMNs) based on commodity hardware present a promising technology for a wide range of applications. Currently, one of key challenges that WMN technology faces is the limited capacity and scalability due to high levels of interference, which is typical for multi-hop wireless networks. A simple and relatively low-cost approach to address this problem that has recently been proposed is the use of multiple wireless network interfaces (radios) per node. Operating the radios on each node on different, non-overlapping channels allows making more efficient use of the radio spectrum and thereby reducing interference and contention. In this paper, we evaluate the performance of the Ad-hoc On-demand Distance Vector (AODV) routing protocol in a Multi-Radio Wireless Mesh Network. Our simulation results show that under high traffic load conditions, Multi-Radio AODV (AODV-MR) is able to efficiently utilize the increased spectrum, and proves to be far superior to single radio AODV. We therefore believe that AODV-MR is a promising candidate for multi-radio WMNs.

Trust-based routing for ad-hoc wireless networks

An ad-hoc wireless network is formed by a number of mobile nodes having limited communication range. The dynamic source routing (DSR) protocol is frequently used to extend the effective range of these nodes through mutual cooperation. The accurate execution of the DSR protocol demands sustained benevolent behaviour by all participating nodes. However, as ad-hoc networks are created in improvised environments, the realization of such altruistic behaviour is virtually impossible to achieve. In fixed networks, trust infrastructures like certification authorities and key distribution centres are generally used to provide default trust relationships. However, the creation of such an entity in an ad-hoc network is considered neither feasible nor pragmatic. In this paper, we propose a novel mechanism for establishing trust based routing in ad-hoc networks without necessitating a trust infrastructure. We accentuate, that the proposed mechanism is most suitable for ad-hoc networks that can be created on the fly without making any suppositions or imposing pre-configuration requirements.

Propagating trust in ad-hoc networks for reliable routing

Ad-hoc networks emerge when a number of mobile wireless nodes agree to mutually cooperate with each other in order to establish communication over a wide region. All nodes in the network execute a pre-agreed routing protocol to pass packets for other nodes. The dynamic source routing (DSR) protocol is one of the unique routing protocols for ad-hoc wireless networks, where each transmitted data packet contains the complete route that it has to traverse. This is due to the fact that during route discovery, all intermediate nodes contribute faithfully to the route generation process. Such an altruistic behaviour is though difficult to realize in realistic environments and so a number of malicious nodes may also participate in the route discovery process only to sabotage the network. In this paper we present a unique mechanism for establishing trusted routes in a DSR based ad-hoc network. The proposed mechanism is specifically designed for improvised networks where the establishment of a fixed or mobile trust infrastructure is considered impractical.

Trusted Greedy Perimeter Stateless Routing

Ad-hoc networks generally comprise of mobile wireless nodes having limited communication and computation resources. These nodes execute special routing protocols, which help to establish multi-hop communication despite a dynamic topology. The greedy perimeter stateless routing (GPSR) protocol is one such routing protocol that is frequently used to establish routes in an ad-hoc or sensor network. However, for its precise execution, it is imperative that all nodes depict sustained benevolent behaviour. However, such an altruistic setting would never work in a wireless environment, which is intrinsically physically insecure. Consequently, participating malicious nodes may launch an array of attacks against the routing protocol leading to route severing, elongation or loop creation. In this paper, we present an improved variant of the GPSR protocol that uses the inherent characteristics of the routing process to assess the trust in the network nodes. These trust levels are then used to influence the routing decisions so as to circumvent malevolent nodes in the network. Extensive simulations indicate that the packet delivery ratio of the trusted GPSR protocol surpasses that of the standard GPSR by as much as 30% when as many as 50% of the nodes are acting maliciously in the network.

Performance analysis of multi-radio AODV in hybrid wireless mesh networks

Wireless Mesh Networks (WMNs), based on commodity hardware, present a promising technology for a wide range of applications due to their self-configuring and self-healing capabilities, as well as their low equipment and deployment costs. One of the key challenges that WMN technology faces is the limited capacity and scalability due to co-channel interference, which is typical for multi-hop wireless networks. A simple and relatively low-cost approach to address this problem is the use of multiple wireless network interfaces (radios) per node. Operating the radios on distinct orthogonal channels permits effective use of the frequency spectrum, thereby, reducing interference and contention. In this paper, we evaluate the performance of the multi-radio Ad-hoc On-demand Distance Vector (AODV) routing protocol with a specific focus on hybrid WMNs. Our simulation results show that under high mobility and traffic load conditions, multi-radio AODV offers superior performance as compared to its single-radio counterpart. We believe that multi-radio AODV is a promising candidate for WMNs, which need to service a large number of mobile clients with low latency and high bandwidth requirements.

Secure Routing with the AODV Protocol

Ad-hoc networks, due to their improvised nature, are frequently established in insecure environments, which makes them susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. Ad-hoc on-demand distance vector (AODV) is one of the widely used routing protocols that is currently undergoing extensive research and development. AODV is based on distance vector routing, but the updates are shared not on a periodic basis but on an as per requirement basis. The control packets contain a hop-count and sequence number field that identifies the freshness of routing updates. As these fields are mutable, it creates a potential vulnerability that is frequently exploited by malicious nodes to advertise better routes. Similarly, transmission of routing updates in clear text also discloses vital information about the network topology, which is again a potential security hazard. In this paper we present a novel and pragmatic scheme for securing the ad-hoc on-demand distance vector routing protocol that protects against a number of attacks carried out against mobile ad-hoc wireless networks

High Performance AODV Routing Protocol for Hybrid Wireless Mesh Networks

Hybrid wireless mesh networks are multi-hop networks consisting of two types of nodes, mesh routers and mesh clients. Mesh routers are more static and less resource constrained than mobile mesh clients, and form the wireless backhaul of the network. Routing in hybrid wireless mesh networks is a challenging task as both type of nodes participate in the routing and forwarding of packets. In this paper, we present extensions to the ad-hoc on-demand distance vector (AODV) routing protocol with the aim to exploit the heterogeneity of hybrid wireless mesh networks. As demonstrated via extensive simulations, our extensions achieve a more than 100% improvement over the standard multi-radio AODV in terms of key performance metrics such as packet delivery ratio, routing overhead and latency.