Norio Shiratori

GAMAN: A GA Based QoS Routing Method for Mobile Ad-Hoc Networks

The Mobile Ad Hoc Networks (MANETs) are useful in many applications environments and do not need any infrastructure support. Much work has been done on routing in MANETs. However, the proposed routing solutions only deal with the best effort data traffic. Connections with Quality of Service (QoS) requirements, such as voice channels with delay and bandwidth constraints, are not supported. The QoS routing has been receiving increasingly intensive attention in the wireline network domain. However, these QoS routing algorithms can not be applied directly to MANETs, because of the bandwidth constraints and dynamic network topology of MANETs. Searching for the shortest path with minimal cost and finding delay constrained least-cost paths are NP-complete problems. For this reason, approximated solutions and heuristic algorithms should be developed for multi-path constraints QoS routing. Also, to cope with changing of MANET topology, routing methods should be adaptive, flexible, and intelligent. In this paper, w...

A QoS routing method for ad-hoc networks based on genetic algorithm

A lot of work has been done on routing in MANETs. However, the proposed routing resolutions deal only with the best effort data traffic. Connections with quality of service (QoS) requirements are not supported. QoS routing has been receiving increasingly intensive attention in the wireline network domain. However, for MANETs only few QoS algorithms are proposed to be developed and QoS routing algorithms should be adaptive, flexible, and intelligent. We propose a genetic algorithm (GA) based routing method for Mobile Ad-Hoc Networks (GAMAN). Robustness rather that optimality is the primary concern of GAMAN. The GAMAN uses two QoS parameters for routing. The performance evaluation via simulations shows that GAMAN is a promising QoS routing algorithm for MANETs.

An interactive protocol synthesis algorithm using a global state transition graph

An interactive synthesis algorithm, to construct two communicating finite-state machines (protocols), is presented. The machines exchange messages over two unidirectional FIFI (first-in first-out) channels when the function of the protocol has been given. The synthesis algorithm first constructs the global state transition graph (GSTG) of a protocol to be synthesized and then produces the protocol. It is based on a set of production rules and a set of deadlock avoidance rules, which guarantee that complete reception and deadlock freeness capabilities are provided in the interacting process. This synthesis algorithm prevents a designer from creating unspecified reception and nonexecutable transition, avoids the occurrence of deadlocks, and monitors for the presence of buffer overflow. >

A neural network approach to multicast routing in real-time communication networks

Real-time communication networks are designed mainly to support multimedia applications, especially the interactive ones, which require a guarantee of Quality of Service (QoS). Moreover, multicasting is needed as there are usually more than two peers who communicate together using multimedia applications. As for the routing, the network has to find an optimum (least cost) multicast route, that has enough resources to provide or guarantee the required QoS. This problem is called QoS constrained multicast routing and was proved to be an NP-complete problem. In contrast to the existing heuristic approaches, in this paper we propose a modified version of a Hopfield neural network model to solve QoS (delay) constrained multicast routing. By the massive parallel computation of neural networks, it can find a near optimal multicast route very fast, when implemented in hardware. Simulation results show that the proposed model has performance near to the optimal solution and comparable to existing heuristics.

AMUSE: an agent-based middleware for context-aware ubiquitous services

In ubiquitous computing environment, different kinds of system components including hardware elements, software components and network connections are required to cooperate with each other to provide services that fulfil user requirements. This paper proposes an agent-based middleware for ubiquitous environment that consists of computers and home electric appliances. The middleware, called AMUSE, can take QoS (quality of service) in ubiquitous environment into consideration by coping with not only user context but also resource context, using agent-based computing technology. In this paper, we describe concept, design and initial implementation of AMUSE. Simulation results of experimental ubiquitous service using AMUSE has been shown to prove the effectiveness of our proposed scheme.

Analysis of the Bluetooth device discovery protocol

Device discovery and connection establishment are fundamental to communication between two Bluetooth (BT) devices. In this paper, we give an analytical model of the time it takes for the master in a piconet to discover one slave. We show that, even in the absence of packet interference, the discovery time can be long in some instances. We have simulated the discovery protocol by actually implementing it to validate the analytical model. By means of simulations, we show how discovery time is affected by (i) the presence of multiple potential slaves, and (ii) changes in the maximum backoff limit. Using simulation studies we observed the effectiveness of two proposed improvements to device discovery, namely, (i) avoiding repetitions of the A and B trains before a train switch, and (ii) eliminating the idea of random backoff, or reducing the backoff limit. We show that discovery time can be reduced by avoiding repetitions of the A and B trains before a train switch. However, complete elimination of the random backoff is not a good idea, as discovery time will be too long when the number of BT devices is large. Instead, choosing a small backoff limit of 250–300 slots is highly effective in reducing discovery time even in the presence of a large number (say, 50) of potential slaves.

Protocol Test Systems

In this paper, we deal with semantic problems of test specification in the OSI Conformance Testing Methodology and Framework, especially in the test notation TTCN. They concern mainly the PCO model and the test purposel test verdict complex. In either case, we identify several open questions. We show up merits and disadvantages of various ways to fill the remaining gaps in standardization, and recommend some specific solutions.

Routing with multiple QoS requirements for supporting multimedia applications

Distributed multimedia applications usually require multiple QoS performance guarantees. However, in general, searching such a route in the network, to support multimedia applications, is known to be NP‐complete. In this paper, we propose a new heuristic QoS routing algorithm, called “QoSRDKS”, for supporting multimedia applications in high‐speed networks. QoSRDKS is a modification of rule‐based Fallback routing and Dijkstra algorithms. It can search a unicast route that would have enough network resources so that multiple QoS requirements (bandwidth, delay, and delay jitter) of the requested flow could be guaranteed. Its worst case computation time complexity is the same as that of the Dijkstra algorithm, i.e., O(❘V❘2), where ❘V❘ is the number of nodes in the network. Extensive simulations were done with various network sizes, upto 500 nodes networks, where each node uses Weighted Fair Queueing (WFQ) service discipline. Results show that QoSRDKS is very efficient. It could always find the QoS satisfying route, whenever there exists one (success rate is optimal), and its average computation time is near to simple shortest path Dijkstra algorithm.

A flexible videoconference system based on multiagent framework

We present a design and implementation of a flexible videoconference system (VCS) using multiagent computing technology. The proposed system, we named FVCS, aims to reduce the burden of the users under the operational environment with insufficient computational resources, such as the Internet environment with small-scale computers at homes and offices, by embedding flexibility to the conventional videoconference system. In this paper, we design and implement FVCS with knowledge-based multiagent framework to realize adaptability of FVCS. We also evaluate the adaptability of the prototype systems of FVCS based on an operational situation observed in its experiments. From the result of the experiments, we conclude that the multiagent-based design and implementation is reasonable for construction of FVCS.

Framework of a flexible computer communication network

With the increasing speed of computers and communication links, and the successful convergence of both fields, computers connected by high speed links now represent an enormously large distributed computing system. At the same time, communication between man and machine is also becoming more diverse and personalized. Networking issues such as evolution of user services, seamless communication between hosts, failure recovery and integration of new technologies arise daily. Problem-specific approaches and corresponding solutions are available at considerable cost. However, a common requirement is adaptability of the computer network to a variety of changes. In this paper, we propose Flexible Computer Communication Networks (FN) as a uniform solution to most of these networking problems. The framework of Flexible Networks can be considered as an intelligent shell enclosing existing networking architectures. An agent-oriented implementation of a flexible network is outlined. The conversion of existing networks to flexible networks is shown to be incremental, and therefore practicable.