Krishna Paul

A distributed mechanism for topology discovery in ad hoc wireless networks using mobile agents

Summary form only given. We have discussed a mobile multi-agent based framework to address the aspect of topology discovery in ad hoc wireless network environment. In other words, we have designed a multi-agent based protocol to make the nodes in the network topology aware. Our primary aim is to collect all topology-related information from each node in the network and distribute them periodically (as updates) to other nodes through mobile agents. The notion of stigmergic communication has been used through the implementation of a shared information cache in each node. Moreover, we have used a concept of link stability and information aging based on which a predictive algorithm running on each node can predict the current network topology based on the current network information stored at that node. We have demonstrated through performance evaluation of a simulated system that the use of mobile multi-agent framework would be able to make each node in the network topology aware without consuming large portion of network capacity. This would eventually help us to implement a proactive routing protocol without much overhead. Moreover, as a direct outcome of infiltrating topology information into the nodes, the foundations for designing distributed network management and implementing communication awareness get automatically laid.

Charging support for ad hoc stub networks

Wired equivalent security is difficult to provide in ad hoc networks due to high dynamics, wireless link vulnerability, and the requirement of complete decentralization. Especially mutual authentication among nodes in a self-organized mode of ad hoc network, where a single definition of trust is hard to build, is very difficult. This leads to several loopholes in previously established security architectures and intrusion detection systems if employed to ad hoc networks. Also, typical to ad hoc routing major security lacks are unfair participation of nodes in the system, and frequent attacks to the routing protocols by ad hoc nodes that do not want to forward foreign packets but use other nodes to forward their own packets. Contrary to detection-based approaches to tackle this situation, we propose a motivation-based approach, which does not require mutual authentication. We enable this by providing (a) a realistic architecture of ad hoc access network to an Internet Service Provider, (b) a workable business model for charging in this architecture and (c) a necessary security protocol to implement the charging scheme. For the latter we give a formal validation.

Communication-aware mobile hosts in ad-hoc wireless network

A mobile, multi-hop wireless computer network, also termed an ad-hoc network, can be envisioned as a collection of routers, equipped with wireless transmitter/receiver, which are free to move about arbitrarily. The basic assumption in an ad-hoc network is that some nodes willing to communicate may be outside the wireless transmission range of each other but may be able to communicate if other nodes in the network are willing to forward packets from them. However, the successful operation of an ad-hoc network will be hampered if an intermediate node, participating in a communication between two nodes, moves out of range suddenly or switches itself off in between message transfer. The objective of this paper is to introduce a parameter, affinity that characterizes the strength of relationship between two nodes and to propose a distributed routing scheme between two nodes in order to find a set of paths between them which are more stable and less congested in a specific context. Thus, the communication in an ad-hoc wireless network can be effective by making the nodes in the system communication-aware in the sense that each node should know its affinity with its neighbors and should be aware of the impact of its movement on the communication structure of the underlying network.

Improving quality-of-service in ad hoc wireless networks with adaptive multi-path routing

The objective of this paper is to propose a mechanism for adaptive computation of multiple paths to transmit a large volume of data packets from a source s to a destination d in ad hoc wireless networks. We consider two aspects in this framework. The first aspect is to perform preemptive route re-discoveries before the occurrence of route errors while transmitting a large volume of data from s to d. Consequently, this helps find out dynamically a series of multiple paths in the temporal domain to complete the data transfer. The second aspect is to select multiple paths in the spatial domain for data transfer at any instant of time and to distribute the data packets in sequential blocks over those paths in order to reduce congestion and end-to-end delay. The performance of this approach has been evaluated to show the improvement in the quality of service. It has been observed that the mechanism allows any source to transmit a large volume of data to a destination without degradation of performance due to route errors. Additionally, it would help reduce significantly the end-to-end delay and the number of route-rediscoveries needed in this process.

Evaluating the performance of mobile agent-based message communication among mobile hosts in large ad hoc wireless network

In ad-hoc wireless network, each node acts as a mobile router, equipped with a wireless transmitter / receiver, which is free to move about arbitrarily. In this configuration, even if two nodes are outside the wireless transmission range of each other, they can still be able to communicate with each other in multiple hops. However, the dynamics of these networks as a consequence of mobility and disconnection of mobile hosts pose a number of problems in designing routing schemes for effective communication between any source and destination. Thus, even off-line communication between source and destination (e-mail, for example) would be inefficient, if not impossible, in a large ad hoc network structure. This paper introduces a scheme using mobile agent to address this issue. Mobile agent in this context would act as a messenger that would migrate from a source and carry the message from a source to a destination. A mobile agent can migrate off a source node with a message and navigate autonomously throughout the network to find out the destination in order to deliver this message. From the performance evaluation, it has been concluded that the proposed scheme consumes much less network resource compared to other routing schemes proposed in the context of highly dynamic large ad hoc network.

Topology Discovery in Ad Hoc Wireless Networks Using Mobile Agents

Extensive research on mobile agents has been rife with the growing interests in network computing. In this paper, we have discussed a mobile multi-agent-based framework to address the aspect of topology discovery in ad hoc wireless network environment. In other words, we have designed a multi-agent based protocol to make the nodes in the network topology aware. Our primary aim is to collect all topology-related information from each node in the network and distribute them periodically (as updates) to other nodes through mobile agents. The notion of stigmergic communication has been used through the implementation of a shared information cache in each node. Moreover, we have defined a concept of link stability and information aging based on which a predictive algorithm running on each node can predict the current network topology based on the current network information stored at that node. We have demonstrated through performance evaluation of a simulated system that the use of mobile multi-agent framework would be able to make each node in the network topology aware, without consuming large portion of network capacity. As a direct outcome of infiltrating topology information into the nodes, the foundations for designing efficient routing scheme, distributed network management and implementing communication awareness get automatically laid.

MARP: A Multi-Agent Routing Protocol for Mobile Wireless Ad Hoc Networks

Supporting mobility in a multi hop wireless environment like the MANET still remains a point of research, especially in the context of time-constrained applications. The incapacity of ad hoc networks to offer services of the likes of static or infratructured networks may be attributed to two major reasons. One, unpredictable mobility of hosts cause location-transparent-packet-delivery to be implemented only at the expense of large control overhead. Two, the lack of central control causes connection management and scalability to be major problems in the multi hop environment. In this paper we propose an efficient agent based routing mechanism that not only incurs minimal overhead, but also lays the foundation for additional functionalities as network management and real time applications. In other words, we show that the agent framework makes the MANET robust and survivable under stringent system constraints.

A stability-based distributed routing mechanism to support unicast and multicast routing in ad hoc wireless network

An ad hoc network can be envisioned as a collection of mobile routers, each equipped with a wireless transceiver, which are free to move about arbitrarily. In ad hoc wireless networks, even if two nodes are outside the wireless transmission range of each other, they may still be able to communicate in multiple hops using other intermediate nodes. However, the dynamics of these networks, as a consequence of mobility and disconnection of mobile hosts, pose a number of problems in designing routing schemes for effective communication between any pair of source and destination. In this paper, a stability-based unicast routing mechanism, that considers both link affinity and path stability in order to find out a stable route from source to destination, is proposed. It is then extended to support multicast routing as well where only local state information (at source) is utilized for constructing a multicast tree. The performance of the proposed scheme is evaluated on a simulated environment to show that the stability-based scheme provides a unified framework for both unicast and multicast routing and reduces the probability of route error drastically in both the cases.

Survivability Analysis of Ad Hoc Wireless Network Architecture

Mobile ad hoc wireless networks are generating novel interests in mobile computing. The dynamism in network topology has thrown up multifarious issues, requiring a fresh look into the aspects of system design and networking protocols. As a direct consequence of injecting mobility into a static network, the formal relationships between several governing parameters have undergone changes. In this paper we have assayed the behavior of the ad hoc network as a whole and analyzed trends in the inter-parameter dependencies, with the objective of addressing to the survivability issues. We have finally drawn out an operating region of survivability for mobile ad hoc wireless networks in terms of user declared specifications. Our own simulator has been operative through the work. We have derived our survivability constraints from several runs of the network simulator.

An adaptive framework for QoS routing through multiple paths in ad hoc wireless networks

We propose an adaptive framework for computing multiple paths in temporal and spatial domains to transmit a large volume of data packets from a source s to a destination d in ad hoc wireless networks. The objective is to achieve quality of service (QoS) by minimizing end-to-end delay for packet delivery. We consider two aspects in this framework. The first aspect is to perform preemptive route rediscoveries before the occurrence of route errors while transmitting a large volume of data from s to d. This helps us to find out dynamically a series of possible paths in temporal domain to complete the data transfer. The second aspect is to select multiple paths in spatial domain for data transfer at any instant of time, and to distribute the data packets in sequential blocks over those paths in order to reduce congestion and end-to-end delay. A notion of link stability and path stability is also defined, and a unified mechanism is proposed to address the above two aspects that relies on evaluating a path based on link and path stability. Our solution method uses Lagrangean relaxation and subgradient heuristics to solve an optimization formulation of the problem in order to compute the paths and the corresponding data distribution, both in temporal and spatial domains. Simulation experiments demonstrate that the proposed framework helps in significantly reducing the end-to-end delay and the required number of route-rediscoveries.