The roadside network system for ITS services uses microcells in its access infrastructure. For the roadside network that provides the uninterrupted communication using microcells such as DSRC, an effective communication control scheme must be established so as to manage the communication passes to vehicles in the network. One of the fundamental requirements for the communication control scheme for the roadside network is to assure fault-tolerance, which means in this system that the communication control mechanism needs to be managed even in part of the base stations in the network might be in fault. On the other hand, for the communication control in the roadside network using microcells, issues to be solved are the handover mechanism for taking over connection information to provide uninterrupted communication environment, which causes the degradation of the end-to-end throughput. In order to solve those problems, the authors developed a communication control scheme. We implemented the scheme as the specific 'ADS algorism' to control the communication zone dynamically, which works effectively on the Autonomous Decentralized System (ADS) communication platform. Furthermore, we also developed the specific ADS algorism to assure fault-tolerance for the communication zone control, which can reconfigure the communication zone in case the BSs in the roadside network are in fault and can keep the operations by the reconfigured communication zone. We evaluated the ADS algorism for the communication zone control by computer simulation. The results show the effectiveness of the ADS algorism for the dynamic communication zone control mechanism and for the fault-tolerant mechanism for communication zone reconfiguration on fault.

System needs of growing systems including heterogeneous functions and operations are increased. High assurance system that achieves high reliability and high availability is very important for such systems. In order to realize high assurance system, we developed the assurance technology based on ADS (Autonomous Decentralized System). When a growing system changes or grows, its reliability may be lowered. In this paper, we clarify the risk factors which lower the reliability and quality of a growing system when the system is modified. We will then examine the technology to eliminate or mitigate those risk factors, and propose adaptive assurance technology that can minimize the risk. We also applied this technology to ATOS for Tokyo Metropolitan Railway Network as an example of really changing and growing system and mention its effectiveness. ATOS; Autonomous Decentralized Transport Operation Control System.

The heterogeneous autonomous decentralized system technology offers a way to integrate different types of context-related autonomous decentralized (sub) systems into a coherent system. The aim of this research is to model and evaluate the communication capacity among the subsystems connected by communication gateways of a heterogeneous autonomous decentralized system. Failures of subsystems and communication gateways in the system are taken into account. We use graphs to represent the topologies of heterogeneous autonomous decentralized systems and use the residual connectedness reliability (RCR) to characterize the communication capacity among its subsystems connected by its gateways. This model enables us to share research results obtained in residual connectedness reliability study in graph theory. Not to our surprise, we learnt soon that computing RCR of general graphs is NP-hard. But to our surprise, there exist no efficient approximation algorithms that can give a good estimation of RCR for an arbitrary graph when both vertices and edges may fail. We proposed in this paper a simulation scheme that gave us good results for small to large graphs but failed for very large graphs. Then we applied a theoretical bounding approach. We obtained expressions for upper and lower bounds of RCR for arbitrary graphs. Both upper and lower bound expressions can be computed in polynomial time. We applied these expressions to several typical graphs and showed that the differences between the upper and lower bounds tend to zero as the sizes of graphs tend to infinite. The contributions of this research are twofold, we find an efficient way to model and evaluate the communication capacity of heterogeneous autonomous decentralized systems; we contribute an efficient algorithm to estimate RCR in general graph theory.

A new architecture and methods for an enhanced autonomous decentralized production system (EADPS) are described. This EADPS was developed to ensure high flexibility of production systems consisting of intelligent devices based on the autonomous decentralized system model and to guarantee the time used for communication to simultaneously maintain high productivity. The system architecture of the EADPS guarantees the time by managing groups of nodes and the priorities in these groups. A bit-arbitration method is used to prevent collision of messages. The nodes autonomously check the waveforms in the network and terminate transmission when the nodes with a higher priority are transmitting. A parallel-filtering method is used to speed up message acceptance. The nodes check the identifiers of the messages using parallel-filtering circuits and each node determines autonomously where a message should be accepted or not. Implementing the system architecture and these methods as circuits and integrating the circuits into a chip using system LSI technologies resulted in low-cost implementation of the system. Experimental evaluation demonstrated the effectiveness of this system.

Over recent years, "Internet-able" applications and architectures have been used to support domains where there are multiple interconnected systems that are both decentralized and autonomous. In enterprise-level data management domains, both the schema of the data repository and the individual query needs of the users evolve over time. To handle this evolution, the resulting architecture must enforce the autonomy in systems that support the client needs and constraints, in addition to maintaining the autonomy in systems that support the actual data schema and extraction mechanisms. At the MITRE Corporation, this domain has been identified in the development of a composite data repository for the Center for Advanced Aviation System Development (CAASD). In the development of such a repository, the supporting architecture includes specialized mechanisms to disseminate the data to a diverse evolving set of researchers. This paper presents the motivation and design of such an architecture to support these autonomous data extraction environments. This run-time configurable architecture is implemented using web-based technologies such as the Extensible Markup Language (XML), Java Servlets, Extensible Stylesheets (XSL), and a relational database management system (RDBMS).