Nikos Migas

Mobile agents for routing, topology discovery, and automatic network reconfiguration in ad-hoc networks

Wireless networks and the usage of mobile devices are becoming popular in recent days, especially in creating ad-hoc networks. There is thus scope for developing mobile systems, where devices take an active part of creating a network infrastructure, and can actually be used to route data between networks. This research proposes to assess different models of the usage of static and mobile agents to determine the best route through ad-hoc networks. The determination of this route is a complex one, and requires research into the best metrics to identify the best path, such as memory capacity, network performance, processing capabilities, cost, and so on. One model is to use a mixture of mobile and static agents to gather relevant information. These agents could perform important tests, which could be used to generate the best route through a network. This research looks at different models for the deployment of these agents, which balance the usage of static and mobile agents. These are appraised in the terms of performance, reconfigurability, and ease of installation.

Protecting mobile agents from external replay attacks

This paper presents a protocol for the protection of mobile agents against external replay attacks. This kind of attacks are performed by malicious platforms when dispatching an agent multiple times to a remote host, thus making it reexecute part of its itinerary. Current proposals aiming to address this problem are based on storing agent identifiers, or trip markers, inside agent platforms, so that future reexecutions can be detected and prevented. The problem of these solutions is that they do not allow the agent to perform legal migrations to the same platform several times. The aim of this paper is to address these issues by presenting a novel solution based on authorisation entities, which allow the agent to be reexecuted on the same platform a number of times determined at runtime. The proposed protocol is secure under the assumption that authorisation entities are trusted.

Migration of mobile agents in ad-hoc, wireless networks

This paper focuses on the design and development of a novel architecture called MARIAN, which utilises static agents, mobile agents, and also a hybrid approach, in order to perform routing, network discovery, and automatic network reconfiguration, in wireless ad-hoc networks. The paper shows that, in most cases, the static agent approach is faster than the mobile agent approach in retrieving data from a wireless remote database. However, if the amount of data to be retrieved is relatively large, such as in the gathering of data for routing information, the mobile agents are more capable of filtering data according to the required preferences. It also shows that the time taken to gather routing information can be significantly reduced using a mobile agent approach, as compared with the static agent approach.

Individualized Tourism Brochures as a Novel Approach to Mass Customization

ABSTRACT Tourism is an information intensive business and technological advances have transformed the way in which information is stored, managed and transmitted to potential visitors. Despite the wide adoption of Internet technologies in tourism marketing, information is still largely disseminated through printed brochures that have remained unchanged and unaffected by personalization trends. This conceptual paper argues that technological innovations such as digital printing allow the creation of dynamic, customized brochures at a lower cost than that of conventional tourist brochures. The main aim of this paper is to propose a framework for cross-media customization of tourism and travel brochures. The paper concludes that empirical research is necessary to assess the optimum levels of individualization for tourism brochures.

Analysis of an agent-based metric-driven method for ad-hoc, on-demand routing

Ad-hoc networks could bring many benefits over traditional, fixed networks. Unfortunately, they have many difficulties, including the selection of the optimal route, the availability of routes as mobile nodes move around the physical space, and problems related to the routing capabilities of mobile devices. This paper outlines an agent-based method which allows tests to be run on nodes within an ad-hoc network, which determines their fitness to route data. These tests are related to important routing parameters, such as data processing performance, memory buffering capabilities, system utilisation, network performance, and so on. A key element is the usage of the battery on mobile networks, and the performance of an ad-hoc network can be affected by mobile nodes leaving the network due to lack of battery power. The paper outlines the tests that could be used on devices, and presents results which can be used to assess the fitness of a device to route data through an ad-hoc network. The overall architecture uses a three-layered model where static agents gather the fitness information, which is then passed to domain agents, which are either static or mobile agents, who are then responsible for collecting the information for inter-domain routing agents, who are responsible for electing gateway agents. A key factor in the determination of routing metrics is the performance of the device, where a device could be used to route certain types of data, based on their routing performance. The results show practical results on how well a range of devices respond to important tests, such as memory buffering capabilities, network performance and battery usage. This is especially important when limited-power devices, such as PDAs, are used in the ad-hoc network. The results also show, clearly, how a typical iPAQ PDA copes with these tests, against high-powered PCs. An important result is in battery usage which shows that it varies with the type of processing and network activities that is being performed on the device. From these results reliable models could be built which predicts battery usage for differing types of activities, especially in routing data.

Metric evaluation of embedded Java-based proxies on handheld devices in cluster-based ad-hoc routing

Ad-hoc wireless networks, which use ad-hoc routing methods may prove a good solution in certain applications, especially where networks have to be constructed where there is no possibly of creating a network backbone, and in emergency situations. They may also lead to more flexible networks, which require reduced configuration, and allow for optimised routes. There is thus a requirement to use mobile devices as intermediate routing devices, which forward data from one device to another. One of the best methods is to run a proxy server on the mobile device, as it allows for a simple implementation on the device. A key factor in this is determining the fitness of a mobile device, especially a limited one, such as a handheld PDA. This paper discusses the metrics that could be used to assess the potential of devices and their environment to route certain types of data, and presents results from iPAQ devices using a range of differing operating systems. It shows how performance of a proxy device varies depending on several factors including the Java environment used, and the operating system used. The paper shows that Linux versions for handheld devices out-perform the equivalent Windows systems for the key performance metrics for proxy devices, such as battery usage and network performance.

Ad hoc routing metrics and applied weighting for QoS support

In the vast majority of ad-hoc routing protocols, the hop-counting mechanisms for identifying the optimal route are dominant. However, this approach oversimplifies such a complex decision by ignoring the fact that participating devices may have considerably unequal performance characteristics and current utilisation status. Accordingly, it is possible for an optimal route to be composed of devices with high utilisation status, or, low battery reserves, which results in an overall unreliable route. This research work tackles this by identifying the best metrics that can describe any route within a graph, in terms of overall throughput, reliability, and minimum energy consumption. Simulations were carried out by varying critical factors of mobile devices such as battery reserves, memory and CPU utilisation, and results recorded the effect that this has on the devices overall routing metric. This paper also presents the threshold values, which turn the device from routing-capable to routing-incapable state.

Ad-hoc Routing Metrics and Applied Weighting for QoS support

In the vast majority of ad-hoc routing protocols, the hop-counting mechanisms for identifying the optimal route are dominant. However, this approach oversimplifies such a complex decision by ignoring the fact that participating devices may have considerably unequal performance characteristics and current utilisation status. Accordingly, it is possible for an optimal route to be composed of devices with high utilisation status, or, low battery reserves, which results in an overall unreliable route. This research work tackles this by identifying the best metrics that can describe any route within a graph, in terms of overall throughput, reliability, and minimum energy consumption. Simulations were carried out by varying critical factors of mobile devices such as battery reserves, memory and CPU utilisation, and results recorded the effect that this has on the devices overall routing metric. This paper also presents the threshold values, which turn the device from routing-capable to routing-incapable state.

An auto-configurable, and, adaptable, metric-driven cluster-head organisation for hybrid multi-hop routing

Multi-hop ad-hoc routing is a challenging issue, because of the dynamic network topology, and limited capabilities of resource-constrained mobile devices. This paper proposes a metric-driven clustering organisation of participating nodes which provides an effective way to reduce network overhead, in contrast to traditional flooding methods. This novel method creates a network backbone for data routing and location management, which is composed of the fittest nodes. The key metrics are: mobility, buffering capabilities, throughput, network state, utilisation, and battery reserves. The paper presents the overall agent-based model, and describes the adaptability of the cluster-head metrics, and the automated reconfigurability of an ad-hoc network