Kenji Tei

Geographically bound mobile agent in MANET

A location-specific data retrieval, which is data retrieval from nodes in a designated region at the time, is an attractive application in a mobile ad-hoc network (MANET). However, almost all nodes in a MANET are powered by batteries, the location-specific data retrieval should involve a small number of messages. In this paper, we use a mobile agent to retrieve the location-specific data. A mobile agent migrates to a node in a designated region, and retrieves data from nodes in this region. Since, after migration, the agent can communicate with nodes in the designated region through low overhead short length hops, the mobile agent can retrieve data at low message cost for long periods, even if the owner of this agent moves around. However, even after migrating to node in the designated region, in order to stay near this region, a mobile agent should migrate to other nodes in response to the movement of the node hosting this agent. In this paper, we propose the geographically bound mobile agent (GBMA) which is a mobile agent that periodically migrates in order to always be located in a designated region. In order to clarify where the GBMA should be located and when the GBMA starts to migrate, two geographic zones are set to the GBMA: required zone and expected zone. The required zone ease tracking of the GBMA, and the expected zone ease adjustment of the GBMA migration timing.

Applying Design Patterns to Wireless Sensor Network Programming

Middleware for wireless sensor network (WSN) abstracts a network as an entity and hides programming difficulties from programmers. Many middlewares have been proposed, but they use different programming languages to manipulate functions in WSNs. This inhibits usability when manipulating multiple WSNs managed by different middlewares, because the primitives of each language have different descriptive capabilities. In this paper, we propose and apply design patterns in WSN programming to complement the capabilities of language primitives, and discuss the effectiveness of these design patterns. First, we discuss major middleware languages and compare the capabilities of their primitives. Second, we extract design patterns from the representative middlewares to cover the missing capabilities identified in the comparison. Finally, we discuss the effectiveness of design patterns for WSN programming. The discussion indicates that design patterns improve the usability of manipulating multiple WSNs.

Region-Based Sensor Selection for Wireless Sensor Networks

In a sensor network, the technique that limits the number of sensors used for observation is effective to reduce the energy consumption of each sensor. To limit the number of sensors without sacrificing observation accuracy, an appropriate sensor combination must be selected by evaluating the observation effectiveness of various combinations. However, the computational workload for evaluating all the sensor combinations is quite large. We can define a parameter related to the optimal size of a region around an observation target by making a trade-off between accuracy and the computational workload. In region-based sensor selection, a combination of sensors is selected from that is near the observation target. Accuracy is better in a larger region with a lot of sensors, but the computational workload is heavier. In contrast, a smaller region with fewer sensors has poorer accuracy, but a lighter workload. The size of the region controls the trade-off between accuracy and the computational workload. We define a parameter related to the optimal size of a region, and use it to dynamically adjust the regions size. Our simulations confirmed that region-based sensor selection reduces the computational workload and improves accuracy in comparison to existing techniques.

Using Mobile Agent for Location-Specific Data Retrieval in Manet

Location-specific data retrieval is an attractive application in a Mobile Ad-hoc Network (MANET). Simple solution for it is that an observer retrieves the data by geocasting from an observer node, but its overhead highly depends on location of the observer and the designated region. We propose a mobile agent approach. A mobile agent migrates from the observer node to a node in the designated region, retrieves data from there, and summarizes, filters, and compresses the retrieved data, This data is sent back to the observer, when the observer request. Since the data is retrieved by the mobile agent located near the data sources, the data retrieval in the mobile agent approach would involve low overhead, even if the observer is far from the target region or moves around. In the MANET, however, even after the first migration, to stay near data sources, a mobile agent should migrate to another node in response to node movements.. In this paper, we propose the Geographically Bound Mobile Agent (GBMA) which is a mobile agent that migrates to always be located in a designated region. Moreover, to clarify where the GBMA should be located and when the GBMA starts to migrate, we introduce two geographic zones: required zone and expected zone. Compared with the conventional methods with geocast or with a conventional mobile agent, the GBMA with these zones for retrieving location-specific data can reduce the total number of messages.

Introducing Auction Scheme to Route Allocation to Prolong the Lifetime of Ad-Hoc Networks

Prolonging a network lifetime is one of crucial issues of message routing protocol in mobile ad-hoc networks (MANETs), because MANETs consist of mobile devices powered by batteries. Previous routing protocols focus on route selection by a message sender to balance message forwarding load. However, in this approach, message routes determined by different senders cannot be coordinated, because each sender selects its message route independently. In this paper, we propose an auction-based route allocation scheme where message routes are determined by auctions between message senders and forwarders, and apply the route allocation scheme to the Dynamic Source Routing protocol. Simulation results show the DSR protocol with our allocation scheme can prolong the network lifetime comparing with the routing protocol proposed in the previous works.

Adaptive Geographically Bound Mobile Agents

With the spread of mobile phones, the use of Mobile Ad- hoc NETworks (MANETs) for disaster recovery finally becomes feasible. Information retrieval from the catastrophic place is attended in an energy-efficient manner using the Geographically Bound Mobile Agent (GBMA) model. The GBMA, which is a mobile agent on MANETs that retrieves geographically bound data, migrates to remain in a designated region to maintain low energy consumption for data retrieval, and provides location based migration scheme to eliminate needless migration to reduce energy consumption. In the data retrieval using the GBMA model, survivability of the agent is important. In a MANET, a GBMA with retrieved data may be lost due to its host’s death. The lost of the agent causes re-execution of the retrieval process, which depraves energy efficiency. We propose migration strategies of the GBMA to improve its survivability. In the migration strategies, the selection of the next host node is parameterized by node location, speed, connectivity, and battery level. Moreover, in the strategies, multiple migration trigger policies are defined to escape from a dying node. We present the implementation of migration strategies and confirm the achievements with several simulations. This finally leads to the adaptive Geographically Bound Mobile Agent model, which consumes even less energy.

A Sensor Middleware for Lightweight Relocatable Sensing Programs

Wireless sensor networks (WSNs) have attracted attention in recent years. Many sensors will be equipped in buildings and provide data about the context of buildings in the future. We can provide many kinds of services that use various context information acquired from wireless sensor networks. However, sensing programs may not be able to be executed concurrently on the same sensor node because of sensors resource restrictions. So, sensing programs sometimes have to relocate to other sensors if necessary. In this paper, we suggest a middleware for the relocation of a sensing program. Considering severe resource restrictions in a wireless sensor network, we can make a sensing program with a small code footprint.

Coordination Protocol Composition Approach Using Metadata in Multi-agent Systems

In e-business, agents need to coordinate with each other. Coordination protocols that specify the defining orders of message passing are very important. The scale of e-Business grows with the advancement of technology, and the number of agents involved continues to increase. Specifying the coordination protocols for so many participating agents is a complex task. A coordination protocol composition approach reduces the complexity of specifying such a coordination protocol. It treats coordination protocols as individual parts and composes them to construct the intended protocols. However, existing approaches do not sufficiently reduce the complexity when a coordination protocol is composed several times, because too many configurations are required to specify a composition. A new approach is proposed that uses metadata to specify the compositions by specifying only one configuration. It can reduce the number of configurations when a coordination protocol is composed several times.

An efficient node selection metric for in-network process deployment

In-network processing is a powerful technique for reducing network traffic in an ad hoc network where network efficiency is a critical issue. When an in-network process collects data from multiple data sources, the node hosting the in-network process should be carefully selected to reduce network traffic. Existing metrics used to select the host node are unsatisfactory in this case, because they do not consider differences in the amount of data provided by each data source. In this paper, we propose a node selection metric called COLOR to solve this problem. COLOR value is derived from locations of data sources and the amount of data provided by them so that a data source that provides more data than the others has a stronger effect. Moreover, the communication overheads associated with COLOR are small, because parameters involved by COLOR can be collected during a data retrieval phase, which generally occurs in in-network processing. Simulation results show that data retrieval using COLOR produces less network traffic than that retrieved using existing metrics in environments where placements of data sources and the amount of data are nonuniform.

A Flexible Protocol Composition for Multi-party Coordination Protocols in Multi-agent Systems

Multi-agent systems need protocols to coordinate among agents implemented by different owners. However, specifying coordination protocols for many participating agents is a complex task. A protocol composition approach, which can reduce the complexity of specifying such a coordination protocol, must specify how to compose coordination protocols in a composition configuration. Current protocol compositions cannot sufficiently reduce the complexity because composing a protocol several times requires the specification of too many configurations. We propose a protocol composition approach that can specify composition configurations in an abstract way. We assign metadata to the messages in a coordination protocol and use the metadata to specify the configuration. An abstract configuration using metadata can be applied to various protocol compositions and can reduce the number of specifications required for configuration composition.