Norihiko Shinomiya

Hybrid Link/Path-Based Design for Translucent Photonic Network Dimensioning

The advancement of ultralong-haul transmission technology has dramatically enhanced the all-optical reaches. However, the actual situations of installed fiber and sites for terrestrial network often prevent implementing a purely transparent network, and thus, opaque reshaping retiming regenerating (3R) regeneration is required to guarantee optical signal reachability. Since 3R regenerators based on optical/electrical/optical conversion tend to dominate the total network costs, an efficient network design method that allocates a minimum number of 3R regenerators to optimum locations is essential to build a cost-effective photonic network. In this paper, we propose such a network-dimensioning method by combining the advantages of link-based and path-based design approaches. It first guarantees optical signal reachability for any possible traffic demand in each segmented linear link. After combining all the links, excessive regenerators are eliminated based on the optical signal quality check with -factor calculation for each wavelength path. A trial design of a large-scale mesh network demonstrated a significant cost savings of more than 30% in comparison with a conventional link-based design. In the trial, the impact of fiber loss coefficient over the total network cost was investigated quantitatively, addressing the importance of such quantitative modeling and analysis.

A theory of tie-set graph and its application to information network management

This paper presents a new circuit theoretical concept based on the principal partition theorem for distributed network management focusing on loops of an information network. To realize a simple network management with the minimum number of local agents, namely the topological degrees of freedom of a graph, a reduced loop agent graph generated by contracting the minimal principal minor is proposed. To investigate the optimal distribution of the loop agents, a theory of tie-set graph is proposed. Considering the total processing load of loop agents, a complexity of a tie-set graph is introduced to obtain the simplest tie-set graph with the minimum complexity. As for the simplest tie-set graph search, an experimental result shows that the computational time depends heavily on the nullity of the original graph. Therefore, a tie-set graph with the smallest nullity is essential for network management. Copyright

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.

Distributed control based on tie-set graph theory for smart grid networks

This paper introduces tie-set graph theory and its application to smart grid networks. Tie-sets stand for loop structure in a network. Tie-set graph theory, which aims to realize distributed control in local units, provides the theoretical nature of loops. In mesh topological networks, all the nodes and links are covered with a fundamental system of tie-sets, which is created by a tree defined by graph theory. If tie-sets are used as local management units in a network, an entire network can be controlled in an orderly fashion due to the graph theoretical basis. Distributed control based on tie-sets has some merit such as easy communication and reduction of electricity loss. In this paper, we propose the unique graph theory on tie-sets, its relationship with smart grid networks, and autonomous configurations based on tie-sets. In addition, we suggest distributed algorithms for an electricity distribution problem as a conceivable issue, and basic simulations and experiments are also conducted.

An Autonomous Distributed Control Method for Link Failure Based on Tie-Set Graph Theory

This study proposes an autonomous distributed control method for single link failure based on loops in a network. This method focuses on the concept of tie-sets defined by graph theory in order to divide a network into a string of logical loops. A tie-set denotes a set of links that constitutes a loop. Based on theoretical rationale of graph theory, a string of tie-sets that cover all the nodes and links can be created by using a tree, even in an intricately-intertwined mesh network. If tie-sets are used as local management units, high-speed and stable fail-over can be realized by taking full advantage of ring-based restoration. This paper first introduces the notion of tie-sets, and then describes the distributed algorithms for link failure. Experiments are conducted against Rapid Spanning Tree Protocol (RSTP), which is generally used for fault recovery in mesh topological networks. Experimental results comparing the proposed method with RSTP suggest that our method alleviates the adverse effects of link failure with a modest increase in state information of a node.

Implementation and Evaluation of Emulator for Testing Service Programs in MANET

Debugging of service programs using a real MANET requires enormous number of devices, a vast testing space, and a lot of people. For this reason, many MANET emulators have been proposed so far. However, these emulators have some drawbacks and advantages. In this article, a new emulator is proposed to effectively test service programs for MANET. Moreover, we implemented the emulator to evaluate the performance and to compare it with existing emulators. The comparative results show that the proposed emulator can realize more efficient and larger range of the test.

Distributed control for link failure based on tie-sets in information networks

This study proposes distributed control for link failure based on loops in a network to conduct local management. A loop can be expressed by a set of links, which is called a tie-set. More local and high-speed recovery is considered to be possible if failure is resolved within some tie-sets. This paper introduces the tie-set concept first, and then describes the distributed algorithms for link failure. Experiments to compare against RSTP are also conducted.

An autonomous distributed control method based on tie‐set graph theory in future grid

SUMMARY In future power grids where electricity flows bidirectionally, the essential problem is to maximize the total efficiency of distributed energy resources. In complicated and large-scale systems such as modern power distribution networks, maximizing the efficiency of the entire system as a whole is extremely difficult. To solve the global optimization problem of such a complex network, this paper proposes an efficient distributed control method for future grid on the basis of tie-set graph theory, where a tie-set is a set of all the edges in a loop of a graph. On the basis of tie-set graph theory, global optimization of an entire network can be realized as a result of local optimization in μ-dimensional liner vector space, where μ is the nullity of the underlying graph of a power network. Although each tie-set has its limited local information, an entire network is gradually optimized in an orderly manner because of the theoretical basis of a tie-set graph. Simulation results of several thousand-node networks demonstrate balanced allocation of dispersed energy resources and thus effectiveness of the proposed method. Copyright

A Hetero-core Spliced Optical Fiber Sensor Network for Remote Monitoring of Agricultural Enviroment

This paper describes an integration of hetero-core spliced optical fiber sensor network for remotely monitoring agricultural environment with a cloud service. A hetero-core spliced optical fiber SPR sensor introduced in our study is able to provide both data communications and sensing functions in the same fiber line simultaneously. Our study uses a fiber sensor covered with Tantalum Pent oxide (Ta2O5) that allows the data transmission distance to be extended with a wavelength of 1310nm for a wide area monitoring. Our novel sensor system can gather remotely-observed environmental data from the monitoring points and deliver them to an operator on a real-time basis.

A Study on Sensor Multiplicity in Optical Fiber Sensor Networks

We have developed a novel optical fiber sensor network system with hetero-core spliced fiber optic sensors. Our previous work demonstrated that the system can play a dual role as a gigabit-class communication network and a sensing system when a limited number of sensors are used. However, optical devices are generally expensive. Thus, in order to use the devices efficiently, it is required that the system allow more sensors to be inserted into a fiber line. In this paper, we propose an enhanced system that can improve sensor multiplicity. The system utilizes a new type of sensor module that generates optical loss only for a short time. We analyze the relationship between sensor multiplicity and communication quality when using such sensor modules, and present results of the performance of this enhanced system in simulated experiments.