Along with the growth of the Internet of Things (IoT), the number of wireless devices and mobile nodes significantly increases and they are connected among them over wireless links. Many application software and network system software for these wireless devices/mobile nodes are being developing. However, we cannot confirm a wireless connection between the two adjacent devices, the network topology which consists of these devices, and the node status of a wireless device which is not equipped with the display for a software developer while the software is running. In this paper, we propose the design of a visualizing software to visualize the network topology and the node status by utilizing the Augmented Reality (AR) technology, and then present the demonstration of the prototype development.

Most of mobile nodes and wireless devices are equipped with 4G/LTE cellular connections and WiFi short range connections. Along with the growth of the Internet of Things (IoT) and M2M communication, in case that these nodes/devices use cellular connections simultaneously to access to the mobile core network, there is the possibility that many of them cannot establish the cellular connections due to the limited wireless resources of the cellular base stations. In this paper, at first, we introduce an autonomous clustering-based two-layered structure in wireless networks. Each node communicates with the other nodes within the transmission range by using WiFi short range connections as ad hoc connections and configures a Mobile Ad hoc NETwork (MANET) without depending the mobile core network as the MANET layer. In the MANET layer, all nodes are divided into multiple groups (clusters) and one cluster head node is selected in each cluster by autonomous clustering. Only cluster head nodes can establish the cellular connections as super peers, and also these super peer nodes configure the P2P network as the P2P layer. Next, we propose a mobile core network load reduction method based on the two-layered structure for information dissemination, and then evaluate the proposed method and the effect of the two-layered structure from the viewpoint of information dissemination. In the proposed method each node can use a cellular connection and an ad hoc connection according to the network condition and node density. Finally, we can confirm that the proposed method reduces the mobile core network load as well as provides the reliable information dissemination from a node to the other nodes through simulation experiments.

Mobile ad hoc networks (MANETs) are networks consisting of wireless communication terminals such as cell phones and smartphones without any communication infrastructures (e.g. base stations). Therefore, MANETs can be utilized for networks in disasters. Moreover, there are some MANET-oriented applications that are developed for day-to-day life. In this paper, we propose a new self-organized communication method with delay and disruption tolerance using Bluetooth, which has advantages in both energy conservation and resilience against radio interference. Our proposed method is also able to adapt to the varying node density within the networks in a self-organized manner. In our proposed method, a node switches its communication method depending on the connectivity of adjacent nodes. We implemented and measured our proposed method on user information dissemination systems. These tests demonstrated our method works on networks with various node densities. Furthermore, we have confirmed that our method can improve the propagation speed of packets in real situations.

A mobile ad hoc network (MANET) is a network that consists of mobile wireless terminals without the aid of the base station. It is expected that MANETs are utilized for various purpose such as traffic jam information announce for vehicles and safety confirmation system in the disaster. Each MANET uses a routing protocol adaptive for the purpose of use. Therefore, utilizing the common routing protocol for multiple MANETs is difficult, and each MANET uses a different routing protocol. In this paper, we propose an Autonomous Clustering based Inter-Domain Routing protocol to communicate between different MANETs. Because of the autonomous clustering, the proposed inter-domain routing scheme can adaptively change the network gateways between MANETs according to the network topology change.

Mobile ad hoc networks (MANETs) that consist of smartphones can be configured easily because most of them are equipped with cellular (3G/LTE) connections as well as WiFi/Bluetooth connections, and then new network systems and services over MANETs can be developed and implemented. However, the performance of the new network systems and services should be evaluated in MANET field experiments. In this paper, we develop a real-time system on Android terminals for visualizing network topology and packet flow in the network to conduct efficient MANET field experiments. Whenever Android terminals communicate with the neigh boring terminals over MANETs, each Android terminal can grasp the information on the neigh boring terminals, and then it sends the information on the neigh boring terminals and the packet reception logs to the log management server. Each terminal can visualize the network topology and packet flow based on these information obtained from the server in real time through cellular connections. As a result, thanks to the visualizing system, the network topology and the packet flow in the network can be confirmed in real time, and then the MANET field experiments can be conducted more efficiently. Finally, we can analyze the log data in the server to evaluate the MANET-based application software after we conducted the MANET field experiments.

In this paper, we present an outline of the new Information Delivery System During a Major Disaster for People Who are Deaf (IDDD) designed using a web platform such as node.js and GCM (Google Cloud Message), and explain the performance measurement results. Especially, a new implementation method using web system for embedded system and M2M system is explained. Also, we explained delay to provide disaster information to a user and spreading that information to multiple displays are shorter than previous IDDD.

The traffic congestion frequently occurs in urban transportations. In order to alleviate the traffic congestion, the vehicle information and communication system (VICS) has been developed. However, since each vehicle can obtain global information on traffic congestion using VICS, all vehicles in the congested areas tend to move to non-congested areas. As a result, the non-congested areas become congested areas. To avoid such the oscillation between the congested and non-congested areas, this paper proposes a novel method based on the vehicle ad hoc network (VANET) for alleviating traffic congestion in urban transportations. In the proposed method, since each vehicle independently collects local information on traffic congestion using VANET, traffic can be distributed from congested areas to non-congested areas. Through simulation experiments, this paper shows that the proposed method provides faster velocity and shorter trip time than VICS in the environments that traffic varies temporally and spatially, which occur in urban transportations.

Mobile ad hoc networks need routing protocols which are adaptive to network environments where node mobility and node density change with time and space. In order to evaluate such routing protocols, simulation experiments using the Random Waypoint are usually conducted. However, since node movement and node placement that obey that model are random in time and space, respectively, it is impossible to evaluate routing protocols in the environments of biased node mobility and node density. In order to solve this problem, first, this paper proposes a new network model, in which users can change node mobility and node density at any time and any area as simulation time goes on. Next, this paper defines change rate of node mobility and node density in each area as a new metric for evaluating routing protocols in a unified way. Finally, this paper presents simulation results for routing protocols which are adaptive to network environments of biased node mobility and node density to show effectiveness of the proposed network model.

Nowadays, broadband services using smart phones and tablet terminals become popular and their users increase. Accordingly, the traffic volume through networks becomes tremendously large and heavily unbalanced. In large networks, a network is usually divided into small subnetworks for its efficient management. However, traffic elevation often occurs to specific divided subnetworks, the throughput suddenly decreases and in the worst case communication is not assured. In order to cope with the congestion problem, this paper proposes a dynamic hierarchization method for traffic variation in wireless mesh networks. In the proposed method, the subnetworks are divided and integrated adaptively to rapid traffic variation in wireless mesh networks. Simulation experimental results show that timely division of the proposed method reduces packets loss due to buffer overflow and a high throughput is maintained.

A new service discovery scheme using mobile agents for mobile ad hoc networks (MANETs) we have proposed are effective for dissemination and collection of service information because mobile agents can migrate among nodes in spite of topology change in MANETs. In the proposed scheme, mobile agents migrate to one of neighboring nodes in which the number of services collected in the predefined time (called service collection time) is the lowest. This paper investigates the property of the proposed mobile agent based scheme for realtime service dissemination and collection in MANETs through simulation experiments. The simulation results show that the service collection time has the impact on the dissemination time of the proposed scheme in imbalanced location of services, and that the proposed scheme can achieve real-time service dissemination and collection by autonomously adjusting the service collection time.

An ad hoc network is a decentralized network that consists of mobile nodes with wireless communication devices without the aid of access points. A Vehicular Ad-hoc NETwork (VANET) is one of the representative applications of the ad hoc network. Epidemic routing has been proposed as a routing protocol based on Store-Carry-Forward mechanism for VANET environment. However, in epidemic routing, network resources such as packet buffer of a node are significantly consumed because data packets are spread across the network. Therefore, this paper proposes a new autonomous clustering-based data transfer scheme using positions and moving direction of vehicles for VANETs. The autonomous clustering configures multiple clusters in the network and then only the cluster head that manages the cluster stores data packets. Whenever the cluster meets a new cluster, the cluster head of the cluster decides whether it should forward data packets to the new cluster based on Vehicle Information consisting of its own position, the destination node's position, and moving direction of the cluster. Finally, this paper presents the simulation results to show the effectiveness of the proposed scheme.

SUMMARY In order to realize hierarchical routings that should be executed in large‐scaled mobile ad hoc networks that vary their topologies considerably with time, we have developed autonomous clustering with high scalability and adaptability. In autonomous clustering, an entire network is divided into disjoint subnetworks (called clusters), and they are maintained by periodically sending messages within the clusters. This paper proposes real‐time self‐organizing autonomous clustering, in which interval and power for transmitting such messages are dynamically changed depending on variation of mobility and density of the clusters. Because their mobility and density can be estimated by local information obtained in the clusters, and according to their respective change the clusters are self‐organized in real‐time way, the proposed real‐time self‐organizing autonomous clustering can contribute to enhancement of its scalability and adaptability. Copyright © 2011 John Wiley & Sons, Ltd.

In 2007, the Ministry of Internal Affairs and Communications of Japan tested 16 different models of a safety support system for children on school routes. One of the models was constructed and tested at a school in an area of the city of Hiroshima from September to December of 2007. For the model project, we developed a new safety support system for children on school routes by using a mobile ad hoc network constructed from mobile phones with the Bluetooth function. The support system provided good performance and accuracy in maintaining the safety of students on the way to school. The basic idea of the safety support system is the grouping of children and volunteers using a mobile ad hoc network. In this paper, we present an outline of this system and evaluate the performance of grouping and the effectiveness of our approach.

Assurance networks are designed to realize trustable Internet-Of-Things including terminal devices/infrastructure service applications for new generation networks. This paper proposes a unified design model for assurance networks and demonstrates the model, methodology and its application to mobile ad hoc networks. In the unified design model, in order to realize the assurance networks, an overall network is partitioned into sub networks and real-time self-organized control functions are incorporated into each sub network for resilience to dynamic change, faults possibly causing failure and attacks to security. In the application of the proposed unified design model to mobile ad hoc networks, a real-time self-organizing autonomous clustering is presented. The simulation experimental results show that the presented autonomous clustering is resilient to a diversity of node mobility and its variation.

Traffic congestion frequently occurs at main roads in Japan. Traffic congestion causes economic loss and makes energy efficient worse. Therefore untying traffic congestion is required. In Japan, vehicle information and communication system (VICS) is famous for a congestion avoidance system. However, VICS depends on infrastructures. On the other hand, vehicle ad hoc networks (VANETs) are independent from such infrastructures. In this paper, we propose a route discover method for alleviating traffic congestions. Since growing traffic congestions makes trip time long, the proposed method provides a driving route whose trip time becomes short. Also we show results of the simulation experiments in this paper.

In a MANET protocol, links between any two nodes are not always bi-directional because nodes can move around the network and their communication ranges are different. In order to detect unidirectional links, some mechanisms such as blacklist are introduced into the protocol. We call such a protocol unsymmetric. By node mobility over time, a unidirectional link can be changed to the bi-directional link and vice versa. Therefore, whenever directionality of any link changes, the protocol has to correctly detect whether the link is unidirect or bidirect. Even if a node receives the same kind of packet from its neighbor node, behavior of the node is different by the unidirectional or bi-directional link through which the node receives a packet. When testers perform conformance testing for these protocols, testers have to use FSM representing different behaviors of a node depending on directionality of the links. In general, the size of FSM grows exponentially along with increase of neighbors of a node. FSM for unsymmetric protocols is more complicated than that for symmetric protocols. Hence, the number of states and the number of transitions in FSM further increase for unsymmetric protocols. In this paper, we propose a new efficient method to solve this problem by treating both input and output as sets. The proposed method redefines a given FSM to an FSM in which the number of states and the number transitions are drastically reduced.

Hiroshima City Children Tracking System is a safety support system for children based on ad hoc network technologies. Field experiments have been conducted in cooperation with an elementary school in Hiroshima. In this paper, we propose a new generation children tracking system which is based on experiences and findings of the field experiments for Hiroshima City Children Tracking System. Our proposed system consists of Android terminals which has Wireless LAN device and Bluetooth device with the ad hoc communication function. Our system manages groups of Android terminals using Autonomous Clustering technique. In this paper, we show the system requirements for our children tracking system and describe the implementation features to satisfy the system requirements. Finally, we provide some preliminary implemented results for our proposed system.

VANET (Vehicular Ad-hoc Network) that is used for vehicular-to-vehicular and vehicular-to-roadside communication is well known as one of the representative application of ad hoc networks. One of the representative mechanisms is Epidemic Routing that adopts the concept of Store-Carry-Forward. However, in Store-Carry-Forward mechanism, each node stores data packets in the buffer, and whenever the node meets at another node, it forwards the duplicated data packets. Therefore, this paper proposes a new reliable data forwarding mechanism that combines Epidemic routing, and the positioning information and moving direction of a node obtained from Global Positioning System (GPS) to reduce widespread forwarded data packets. The proposed scheme forwards data packets using the Store-Carry-Forward mechanism to the neighboring nodes that are determined by the positioning information and moving direction of a node. As a result, we confirmed that the proposed scheme has better performance than Epidemic routing with respect to the total volume of forwarded packets and consumed packet buffer through simulation experiments.

In mobile ad hoc networks, the status of the network changes over time due to the movement of terminals, the battery level of terminals, and so on. To construct assurance networks, it is necessary to consider requirements such as dependability, security, and adaptability against changes in the network. We had proposed a routing method, which is referred to as RSR (Route-Split Routing) for mobile ad hoc networks. With RSR, serious drawbacks occur when a node exhausts its battery. In this paper, we have proposed a new SMN (Sub route Management Node) configuration scheme and a dynamic new method where the SMN role changes to adjacent nodes. To evaluate the effectiveness of our method, we have implemented our method with a simulator and have conducted simulation experiments. The results indicate that our method is effective when nodes have various levels of battery power and power consumption.

An ad hoc network is a decentralized network that consists of mobile nodes with wireless communication devices without the aid of access points. A Vehicular Ad-hoc Networks (VANETs) is one of the representative application of ad hoc networks. Epidemic Routing has been proposed as a routing protocol based on Store-Carry-Forward mechanism for VANETs environment. However, in Epidemic Routing, network resources such as packet buffer of a node are significantly consumed because data packets are spread across the network. Therefore, this paper proposes a new data forwarding scheme that combines Epidemic Routing and autonomous clustering for VANETs environment. The proposed scheme configures multiple clusters in the network and then only the cluster head that manages the cluster stores and forwards data packet to mitigate the consumption of network resources. Finally, this paper presents the simulation results to show the effectiveness of the proposed scheme.

In a sensor network, saving electronic power is an important issue. This is because sensor nodes would be batterydriven and it is not practical to exchange or recharge a battery for hundreds or more sensor nodes. Therefore many studies on expanding sensor network's lifetime have been performed. We focus on autonomous/adaptive routing for sensor networks to expand the networks lifetime. In this paper, we propose an autonomous method for aggregating primary paths and reserving backup paths in sensor networks. In the proposed method, primary paths and backup paths such that they are not overlapped with each other as much as possible are simultaneously reserved at first. When a battery of a node in a primary path has run out, switching a primary path to one of backup paths is rapidly performed with smallest control packets.

Recently, in Japan, crimes against children become atrocious and brutal. In some cases, children are attacked on the way to and back from school. Many technologies using ubiquitous networks have been developed to prevent crimes against children on their way to and back from school. Existing technologies, however, are not powerful to prevent crimes against children and helpful for parents since it is difficult to take information of children as a group. If the system can provide group information of children on the way to and back from school, it is easy for parents to know their safety level. This paper proposes a new technology for children tracking system based on mobile ad hoc networks and describes outline of children tracking system in Hiroshima City. The field experiments using the children tracking system have been performed and the effectiveness of the system is shown by data analysis for the experimental results.

In wireless sensor networks, sensor nodes have limited computational power and memory size. The data is vulnerable to attack due to the nature of the systems, so maintaining confidentiality is an important problem. Most security methods are based on common or public key cryptosystems. However, these methods have problems with encryption of data. When nodes try to encrypt data, they must preestablish keys. When nodes send data to the sink node, all of the exchanged information will concentrate in the sink node. This creates a single point of failure. In this paper, we propose a new distribution method resilient against node capture attacks using the secret sharing scheme. In addition, we will confirm the ability of our method to improve resiliency against node capture attacks, comparing it with TinySec, which is the major security architecture of wireless sensor networks. Also, we compare the resiliency to existing pairwise key establishment methods.

Recently, the embedded software, which is implemented in high definition TVs, recorders and cellar phones and so on, are complicated. There are several reasons. One of the reasons is that embedded software will be implemented with libraries for concurrent processing such as pthread in C language. Developers have to be aware that concurrent programming by using multithread, multi-process and so on. However, concurrent programming is harder than sequential programming. It is possible to cause defects such as race conditions, dead lock and so on. In this paper, we employ ACP (all concurrent paths) and CMFG (concurrent module flow graph) to execute white box testing for the source code of the concurrent software. The number of test cases of ACP becomes huge when the number of blocks increases. In this paper, we propose to suppress the number of test cases of ACP and measure the coverage of ACP by a tool.

Recently in ad hoc networks, routing schemes using location information which is provided by GPS (Global Position System) have been proposed. This paper proposes a new hierarchical routing protocol based on the autonomous clustering scheme using the location information of nodes and shows the effectiveness of the proposed hierarchical routing in comparison with GPSR, Hi-AODV and AODV through simulation experiments with respect to the amount of control packets and the data delivery ratio.

When ubiquitous networks pervade in future, applications such as file transfer and Web browsing will be used also on ad-hoc networks. End-to-end reliable communication is necessary for these applications, and TCP has usually been used as a transport protocol. However, it is known that the performance of fairness and transfer rate decreases when TCP is used on ad hoc networks. Particularly, multi-connection flows of TCP have danger of unfair communication among all flows sharing a wireless link. Then, we pay attention to the multistream mechanism of SCTP to improve unfair communication of TCP multi-connection. SCTP can manage multiple data streams in one association by using the multi-stream mechanism. The performance of reliable transport protocols such as TCP and SCTP easily suffers from frequent route failures and contention on the wireless channel. To improve the problem for mobile ad hoc networks, we propose a scheme which adds the mechanism of Fixed RTO and dynamic delayed SACK to SCTP (shortly, the proposal). And, we evaluated the proposal by a network simulator QualNet.

Recently sophisticated protocols for routing in ad hoc networks have been proposed, but there is still little work on service discovery in such volatile environments. In this paper a mobile agent-based scheme for service discovery in ad hoc networks is introduced. Mobile agents are traveling through the network, collecting the dynamically changing service information. The travel route and the number of travel agents are adjusted according to the information state and the change of network topology. In a quantitative analysis the proposed algorithm is compared with the flooding scheme. The usefulness of the approach is proved by an implementation for mobile devices using J2ME and Bluetooth.

In a sensor network, saving electronic power is an important issue. This is because sensor nodes would be battery-driven and it is not practical to exchange or recharge a battery for hundreds or more sensor nodes. Therefore many studies on expanding sensor network's lifetime have been performed. We focus on autonomous/adaptive routing for sensor networks to expand the networks lifetime. In this paper, we propose an autonomous method for aggregating and repairing paths in sensor networks. In the proposed method, a sensor node broadcasts a special message when the sensor node's battery has run out. The special message is a trigger of repairing path process bypassing the node whose battery has run out. We have evaluated the proposed method and simulation results show expanding sensor network's lifetime with small overhead, i.e. more than twenty data packets are obtained for a control packet

In mobile ad hoc networks, routing schemes using location information have been proposed. Most of these schemes assume that the source node already knows the location information of the destination node. However, since all nodes are always moving, it is difficult to apply this assumption to the real mobile ad hoc environment. In order to cope this difficulty, this paper presents a new routing scheme HRLI, a Hybrid Routing with Location Information, which using the threshold for the communication range of all nodes. And it considers the location and velocity information of the destination node and the neighboring nodes. In HRLI, when a source node creates a route to a destination node, the future location of the destination node predicted by the source node is calculated using these location and velocity information. And the source node sends data packets based on the predicted location information of destination node and neighboring nodes. This paper shows that HRLI achieves high data delivery ratio and fewer overheads for using the threshold of communication range and the predicted location through simulation experiments

In order to make routing efficient for large-scaled ad hoc networks, we have proposed the autonomous clustering scheme and the hierarchical routing called Hi-AODV based on the autonomous clustering. Since, in the current autonomous clustering, a tree rooted at a clusterhead which manages a cluster is constructed for each cluster, data and control packets always pass through the clusterhead in the hierarchical routing and the overhead of the clusterhead becomes much higher. Therefore, in order to reduce the number of data and control packets which each clusterhead handles, this paper proposes an efficient on-demand hierarchical routing protocol based on the autonomous clustering for ad hoc networks

Telecommunications are powerful tools to reduce loss of life and property damage during disasters. Especially, for the people with disabilities, information provided through their own telecommunication devices is indispensable to move to a place of refuge safely and rapidly. In this paper, we propose the wireless system to send information on disasters to people with disabilities (especially deaf people) and to identify their location at the refuge when they are evacuated. The system consists of cellular phone, web server and electronic display, which are concatenated by Short Message Service (SMS) and Bluetooth. By using these devices and public network services, the system provides a function to send appropriate information to people with disabilities rapidly. The system provides the network platform to share information about their whereabouts with related persons. Finally, we summarize results from demonstration of our system to the deaf people experienced large earthquake.

The constraint-based routed label distribution protocol (CR-LDP) is a well-known traffic engineering technologies in MPLS networks. CR-LDP is a signaling protocol for establishing a label switching path (LSP) and has a function such that CR-LDP coordinates LSPs that conflict (for example, the LSPs share a link). However CR-LDP coordinates such LSPs only. Therefore such coordination (i.e. rerouting a LSP) would result in other conflicts (i.e. the rerouted LSP would share a link with other LSPs). This paper proposes a new traffic engineering method which is called the "multiagent-based path rerouting method (MPRM)". When a conflict occurs, MPRM coordinates all LSPs without concerning the conflict in order to avoid new conflicts caused by dissolving the conflict. For avoidance of new conflicts, MPRM performs not only rerouting of LSPs that make the conflict but also rerouting some LSPs that result in no conflicts. This paper also evaluates basic performance of CR-LDP and MPRM.

This paper discusses multicast routing in ad hoc networks. The multicast routing is defined as routing such that the same message is delivered from a node to a set of more than one node called multicast group. Since nodes move around in the ad hoc networks and members join and leaves from the multicast group, it is difficult to manage the multicast group and to maintain routes along which the same message is delivered to the multicast group. We have proposed an autonomous and adaptive clustering scheme to keep sets of connected nodes as clusters. In order to cope with the difficulties mentioned above, this paper proposes a new hierarchical multicast routing protocol to which the autonomous and adaptive clustering is applied in ad hoc networks. Simulation results show that the proposed protocol is effective from the viewpoint of the numbers of control packets and delivered data packets in comparison with a typical core-based multicast routing protocol MAODV.

File-sharing Peer-to-Peer systems are effective for autonomous information retrieval over the networks. However, the previous information retrieval schemes such as Gnutella and Local Indices have bad performance and large overhead. In order to solve these drawbacks, this paper proposes a dynamic information retrieval scheme, in which indices are dynamically allocated in appropriate nodes adaptively to variation of traffic patterns caused by query messages. The simulation experimental results show that the proposed scheme has good performance with reasonable overhead even when the traffic patterns vary as time proceeds.

Clustering of the ad hoc networks is an important technique for introducing a hierarchical structure into the network. In the previous work we have proposed an autonomous clustering scheme for highly mobile large ad hoc networks, which is adaptive to change of the network topology. In this scheme, the network is logically divided into sets of mobile nodes called clusters, however, is not always geographically divided. As a result, non-preferable situations may occur among clusters. In order to avoid these situations, this paper proposes an improved autonomous clustering scheme for highly mobile large ad hoc networks without using geographic location information on mobile nodes. The simulation results show that the proposed scheme is effective for a geographical division of the network in the sense that the number of gateways among clusters is much decreased and the shape of clusters becomes roundish.

A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. (1) The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on the local information. (2) The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the network, which satisfy the above requirements.

Recently, software testers have relied more on automated testing to test software. Automated testing method consists of three modules: test case design, execution, and verification. Yet, to accomplish these three phases, we are always in a dilemma due to a lack of a verification function. Nearly all the commercial automated testing tools cannot efficiently compare graphical objects though GUI (Graphic User Interface) software is now more crucial than text based user interface. This research develops a technique that aids automatic behavior verification for a particularly difficult problem: determining the correction of screen and paper output. Methodology to capture and compare the output is presented and a case study using Microsoft/spl reg/ PowerPoint/spl reg/ is described.

A method of preparing a backup virtual path (VP) for each primary VP is popular for establishing a reliable computer network. In the case of multiple failures, however, it is possible that multiple failures happen on both a primary VP and a pairwise backup VP. In order to solve the above problem, the paper proposes a new multiagent based method where more than one backup VP is prepared for each primary VP.

In order to make the ATM network fault-tolerant and the network service flexible, a method for setting up backup virtual paths (VPs for short) using multiagents is effective with respect to adaptability to the change of network resource and user requirements, examples of which are failure of nodes and links and addition of VPs, respectively. In the method, under the assumption that candidates of backup VPs between different pairs of source and destination nodes are given, the optimum backup VPs are obtained by exchanging information among agents autonomously. First, this paper proposes a new measure for determining backup VPs between different pairs of source and destination nodes. The measure shows a degree of fault-tolerance for backup VPs and addition of VPs. Next, this paper presents simulation results to evaluate the adaptability of the method. The results show that the method efficiently obtains the optimum backup VPs even when the number of backup VPs increases and that different idle time at each destination node enables to shorten the total processing time while keeping complete detection of shared links.

Imprecise computation is one of the promising schemes in real time systems to adapt the quality of computations to the change of load, keeping the deadlines of tasks in the systems. When overload occurs in the systems, the minimum requirements on the deadline are assured by decreasing the quality of the computation. This paper describes how to apply the concept of imprecise computation to automobile control in the expressway assuming the intelligent transportation system (ITS). The deadline violation of tasks for automobile control in the expressway induces collision of automobiles. Regardless of whether the expressway is congested or not, collision of automobiles must be avoided. To satisfy such requirement, the concept of imprecise computation is effective. This paper proposes a flexible scheduling using imprecise computation to avoid collision of automobiles and increase throughput.

Responsive communication protocols must incorporate both real-time and fault-tolerant properties. In this paper, we propose a new method for detecting design faults in specifications of responsive communication protocols based on real-time temporal logic. We also present a case study where a connection establishment protocol for a plant control system is dealt with.

This paper discusses how a backup virtual path (VP) between each pair of a source node and a destination node is set up such that when some nodes and links in primary VP's fail, primary VP's are changed to backup VP's rapidly. Then, this paper proposes a multiagent-based method for such rapid restoration from primary VP's to backup VP's. The proposed method consists of the following three steps. The first step enumerates candidates of backup VP between each pair of a source node and a destination node. In the second step, capacities of shared links in backup VP candidates between different pairs of a source node and a destination node are obtained. The last step determines a backup VP with the minimum capacities of shared links between each pair of a source node and a destination node. The proposed method has potentially good adaptability for change of both network resource such as topology and link capacity and resource requirements such as capacities of primary VP and backup VP.

The responsiveness verification of a given communication protocol is to check whether the given protocol can recover from any abnormal state to a normal state within a permissible time or not. In order to make practical discussions, we assume that the lower and upper bounds of execution time are given for each message transfer and event. We propose a new responsiveness verification method which executes several events concurrently based on residual times of events, and develop a simulator which implements the proposed method. Then we present an experience which applies the simulator to the design of an actual connection establishment protocol for a certain plant control system. The system adopts the client server model and real time constraints exist on connection establishments. In the experience, we first specify the protocol straightforwardly. Then we apply the simulator to the specification and detect design faults against responsiveness. Next, we revise the specification successfully based on the state sequences generated by the simulator. The results of the experience conclude that the proposed method is effective for the case study.

Design of practical routing protocols is complex and difficult due to complicated requirements of fault tolerance and flexibility. The protocol is defined to be fault-tolerant if messages can be rerouted via another path when the communication channel fails. In this paper, we propose a new synthesis method for generating a fault-tolerant routing protocol for a given service specification and a network topology. The routing protocol thus obtained adopts a multipath routing augmented with sets, where each set stores the next nodes for routing, and updates the sets according to network topology changes. Additionally, the routing protocol can attain flexibility by the multipath routing mechanism in the sense that only a small amount of changes is needed for addition or deletion of nodes. Finally, we show the effectiveness of the proposed method through an application to a typical routing service of message delivery from a source node to a destination node.

The non-deterministic behavior in telecommunication services are well-known as one of the most typical feature interactions, and they should be detected and eliminated from the telecommunication service specifications. The conventional analysis method of this non-determinism is based on reachability analysis. Since the method must exhaustively enumerate all reachable global states, it cannot be applied to the complex communication services which include many users. We propose an alternative method based on a Petri-net model. The method constructs a logically equivalent Petri-net for a given service specification, and obtains a set of states which cause the non-deterministic behavior using rules in the service specification. Then, the method identifies states in the set which are not reachable from the initial state using the P-invariant of the Petri-net, and deletes them from the set. As the P-invariant is utilized as the necessary condition, we must finally apply reachability analysis to states in the resultant set. Since the number of states in the resultant set may be reduced to a relatively small value the new method enables us to analyze the more complex services.

In this paper we propose a new model for conformance testing of real-time protocols. First, we point out necessary properties for the model with respect to the following attributes: (1) the description and testing of the time constraints, (2) time-out processing. Although communicating finite state machine (CFSM) and its extension TCFSM are widely accepted as models for communication protocols, these models do not satisfy the necessary conditions, and are not suitable for testing real-time properties. Then we propose a new model CFSM-T which defines a new time constraint [l,u,d] to resolve time difference between clock (logical time) and timer (physical time) and changes the scope of description to processes only. Finally, we apply it to specify the alternating bit protocol. The result shows that the new model CFSM-T would be an effective model of real-time protocols for protocol conformance testing.

We propose a timed reachability analysis method in order to generate system states of two classes of EFSM-based communication protocols; one class C1 consists of events such that the lower and upper bounds are all the same and the other class C2 consists of events such that they may be different. The proposed method enumerates only sequences of system states that are obtained through parallel execution of all possible events. Then, in order to evaluate the efficiency of the proposed method, we develop a verification tool based on the proposed method, and then apply the tool to a broadcasting protocol. The experimental results show that the total number of states generated by the proposed method is much less than that by the previous method.

The trend toward the enrichment of communication services in ISDN and IN has greatly increased the size and complexity of communication protocols which realize the services. A large and complex protocol is constructed by integrating components, each of which corresponds to a subfunction specified in a service specification. The conventional approach to this construction is to integrate components on the protocol level using the existing protocol integration methods. In this approach, the reachability analysis of protocol components is required in the integration stage. So if the size of components becomes large, the integration stage would be a bottleneck because of the state explosion problem of the reachability analysis. Therefore, we propose a new approach to construct the target protocol which, at first integrates components on the service specification level and then transforms an integrated service specification into the target protocol by the protocol synthesis technique. As a result, the construction of the target protocol from the component service specifications can be efficiently effected in a small state space without paying special attention to the timing of protocol messages.

In this paper, we present a routing protocol for finding two node-disjoint paths between each pair of nodes in a computer network. In the proposed protocol, each node in the network has the same procedure, which is driven by local information with respect to the network topology such as an adjacent node on a spanning tree in the network. Thus, the execution of the protocol can continue after changes of the network topology and load. The concept of spanning tree-based kernel construction is introduced to synchronize procedures under the distributed control of the protocol. The routing scheme based on the protocol possesses the enhanced capabilities of alternate routes and load splitting, which cope with failures and load variations in the network. Furthermore, even if topology changes occur which damage the obtained disjoint paths, the paths themselves can be updated efficiently.

Protocol synthesis is used to derive a protocol specification based on a service specification. In the previous protocol synthesis methods, if the service specification includes simultaneous transmission of primitives, then the derived protocol specification includes protocol errors of unspecified receptions caused by message collisions. This paper extends a class of derived protocol specifications to include message collisions which often happen in real communication protocols, and proposes a protocol synthesis method such that (1) simultaneous transmission of primitives causing message collisions can be described in the service specifications, and (2) transitions for avoiding protocol errors of unspecified receptions can be generated by new transition synthesis rates. This paper also proposes a verification method for determining a real-time bound in the synthesized protocol specification using the task scheduling algorithm for multiprocessor systems.>

The authors propose an integrated approach to protocol specification design and a new method of synthesis of protocol specifications with more than one software module for the approach. In this approach, after designers specify protocols without any restrictions, errors included in the protocol specifications are automatically detected by the acyclic-expansion-based protocol validation and efficiently corrected by the component-based protocol synthesis. In the validation, incomplete specification parts consisting of executable state transition sequences to reach errors in each process are obtained. In the synthesis, the incomplete specification parts are completed by applying certain components which are provided as fundamental parts of correct specifications. The proposed approach has been implemented as an integrated system consisting of CAPE (computer-aided protocol engineering) tools for protocol validation and synthesis. The effectiveness of this approach has been confirmed experimentally. The proposed approach is expected to enhance the productivity of protocol specification design.>

For the development of communications software composed of many modules, protocol validation is considered essential to detect errors in the interactions among the modules. Protocol validation techniques previously proposed have required validation time that is too long for many actual protocols. The authors propose a novel fast protocol validation technique to overcome this drawback. The proposed technique is to construct the minimum acyclic form of state transitions in individual processes of the protocol, and to detect protocol errors such as system deadlocks and channel overflows fast. The authors also present a protocol validation system based on the technique to confirm its feasibility and show validation results for some actual protocols. As a result, the protocol validation system is expected to improve productivity in the development and maintenance of communications software.>