Tadashi Ohta

A Broadcasting Method considering Battery Lifetime and Distance between Nodes in MANET

This paper proposes a broadcasting method considering the residual battery lifetime of each node and distance between relay nodes in MANET (Mobile Ad-hoc Networks). In the method, broadcasting packets are sent with high reachability, low network load and low broadcasting latency to a whole network. So far, many broadcasting methods have been proposed. But, since most methods do not take into consideration the residual battery lifetime of each node, there is a possibility that reachability decreases with time lapse. As a method which considers the residual battery lifetime of each node, FBC (Fair Battery Consumption) has been proposed. However, there is a possibility that the number of dead nodes rapidly increases because the difference between the residual battery lifetimes of each node decreases with time lapse. By simulation, the proposed method is compared with existing methods and the effectiveness of the proposed method was confirmed.

Feature interaction detection contest of the Fifth International Workshop on feature interactions

Abstract A feature interaction detection contest was held for the Fifth International Workshop on Feature Interactions. The contest had two phases. The first phase required the contestants to analyze interactions among ten features, which were published on 15 February 1998, and to submit their results by 15 July 1998. The second phase, begun on 15 July 1988, required analysis of the interactions among two new features and the original 10, to be submitted by 1 August 1988. Six contestants submitted entries, to be judged in August and September, with the winner to be announced at the workshop. This body of this paper outlines the contest instructions.

A feature interaction benchmark for the first feature interaction detection contest

Abstract The feature interaction problem is an inherently difficult problem that affects the entire software life cycle for development of new features for reactive systems. A considerable body of work has been created over the last 10 years addressing this problem. To encourage testing and comparing different approaches to the problem, a feature interaction detection contest was held for the Fifth International Workshop on Feature Interactions in Telecommunications and Software Systems. The contest required the participants to use automated tools to address the feature interaction problem in the requirements phase of feature development. The participants were required to discover the pair-wise feature interactions inherent in the requirements for a collection of features. This special issue of COMNET contains the best papers from the participants in that contest. Although there could be only one winner of the contest, all of the approaches represented here provide useful insight into how to approach the feature interaction problem as it affects the requirements phase of feature development. We hope that subsequent contests will provide opportunities to refine these approaches and to address other phases of feature development.

Secure end-to-end delegations in distributed systems

Delegation of tasks represents an important aspect of a distributed system, which sustains the availability of services offered by such a system. A necessary requirement of delegations is that they be performed in a secure and manner. This paper presents a delegation scheme based on an adapted ZS-3 public key cryptosystem^2^4. The scheme allows an originator of the delegation to specify the executor of the delegated task and the intermediaries that participate in the event. It also features the ability of the executor to verify that all participating intermediaries remain uncompromised. The scheme attains a level of security against internal and external attacks, which is equivalent to the solving of instances of the discrete logarithm problem, thus making it an attractive candidate for delegations in distributed systems from the point of view of security.

Home Appliance Virtualization Software Configuration for Home Network Services

Recently, there have been extensive studies on home networks, mainly undertaken by the home appliance industry. Service programs and device control programs of current home network systems are dependent on vendors and devices. In this study, we virtualize each home network device so that it can be considered to contain a number of logical devices, and propose a new software configuration based on this virtualization concept. Programs are written using logical interfaces, which define what types of information are exchanged. The proposed software configuration makes programs independent of vendors or physical devices. We have developed a prototype home network system and home network service programs, and confirmed the effectiveness of the new software configuration.

Programmable Ad hoc Networks

This paper proposes a mobile node for ad hoc networks where users can create new services by themselves. In the proposed method, a rule-based language ESTR is adopted as a service description language so that end users, who are non-experts in network and programming, can create new services easily. An emulator for ad hoc network experiments, which can provide multiple pseudo-mobile nodes using one actual mobile node and multiple pseudo-zones using one actual radio zone, is also proposed

Reduction of the number of terminal assignments for detecting feature interactions in telecommunication services

Telecommunication systems are typical complex systems. Services that independently operate normally will behave differently when simultaneously initiated with another service. This behavior is called feature interaction and is recognized to affect the dependability. This article proposes a method of dramatically reducing the computation time required for detecting feature interactions in telecommunication services. One of the knotty problems in defecting feature interactions at the specification design stage is terminal assignment. For the same service specifications, occurrence of feature interactions depends on how to assign real terminals to terminal variables in the specifications. Consequently, all terminals connected to the network have to be considered in order to detect all interactions. As a result, the number of combinations of terminal assignments is enormous. This causes huge expansion of computation time needed for detection of feature interactions. By considering equivalent states, the proposed method can reduce the number of terminal assignments to one 400th compared with that of the conventional method.

A method of automatic state acquisition for conflict detection of telecommunication service descriptions

Abstract The detection and elimination of telecommunication service interactions are still urgent problems. Conflict, which is discussed in this paper, is one of the problems that comes under heading of telecommunication service interactions. The main problem in detecting conflict is due to the difficulty of grasping and predicting states when services are combined. This paper describes a method of automatically acquiring these states. Telecommunication service behaviors are assumed to be described as a set of rules. When acquiring the states by applying rules, it is necessary to know whether an arbitrary terminal state is synchronized with the other terminal states. Although determining synchronization among multiple terminal states is ordinarily difficult for the designer, by using the proposed method, states can be automatically generated without the designers intervention.

Home Network Service Programs described in a Rule-based Language

Rule-based languages allow programs to be easily described at a high and abstract level, however, they suffer from long execution times. A state transition model, one of a standard model for developing telecommunication services programs, can be used to simply described home network services. To reduce the complexity of development, this paper proposes a method for describing service programs using a rule-based language. In this paper the easy-of-use of this method for novice users is tested using a home network to control a robot toy.

Avoidance of Feature Interactions at Run-Time

Many researches for detecting feature interactions of telephony services have been discussed all over the world. But, there is no guarantee that all detected feature interactions can be resolved. In fact, services must be provided with unresolved feature interactions still remained. Consequently, a method for avoiding feature interactions at run-time is required. However, as far as the authors know, any effective solutions for avoiding feature interactions at run-time have not yet been proposed. In this article, it is clarified that even for services between which feature interactions occur, in some terminal assignments, feature interactions do not occur. Based on this fact, a method for avoiding feature interactions is proposed, where service initiation is prevented only when a terminal assignment causes feature interactions.