The HTTP/2 and HTTP/3 protocols are commonly used as techniques for minimizing webpage load time by enabling the simultaneous retrieval of multiple webpage components. Despite their effectiveness in retrieving components from a single server, their performance degrades when interfacing with multiple servers due to the increased number of connections required. To address this challenge, our team introduced the notion of “co-occurrence”, which reflects the repeated appearance of certain components on different webpages, quantified as the “degree of co-occurrence”. Previous research has demonstrated the potential application of this concept in cache control schemes. Consequently, this article presents a new cache control methodology that utilizes the concept of co-occurrence, particularly when dealing with multiple cache servers supporting HTTP/2 and HTTP/3. The proposed method aims to consolidate co-occurring components on a single cache server as much as possible. The proposed method was evaluated by computer simulation and confirmed to improve the effectiveness of object aggregation while suppressing the degradation of hit rate.

Information-Centric Networking (ICN) is gaining attention as the next generation network for efficient content delivery. ICN is deployed by each Internet Service Provider (ISP) based on its management decision. Since ISPs pay each other transit fees based on the amount of traffic they receive, the deployment of ICN has a significant impact on the profits of ISPs. Therefore, it is necessary to analyze the process of ICN adoption by ISPs in order to clarify the potential of ICN adoption. In this study, we use publicly available measured Autonomous System (AS) connection topology data and Multi-Agent Simulation (MAS) to clarify the feasibility of ICN deployment for ISPs, taking into account economic efficiency. We will also clarify the mechanisms necessary for the diffusion of ICN.

Wildlife has been damaging crops in mountainous areas where it is difficult to access commercial power sources. Therefore, a power-saving system for monitoring harmful wildlife has been proposed that combines multiple sensor nodes with different levels of power consumption. A sensor with higher power consumption capable of obtaining more detailed information is activated step by step after a sensor with low power consumption detects approaching harmful wildlife. However, such a method does not consider the coordination among multiple sensor nodes deployed in a region. An autonomous recording unit (ARU) uses sound to monitor wildlife intermittently for long-term operation to reduce power consumption. However, events are not captured when the ARU is in standby mode. Therefore, we propose a wildlife monitoring system that improves the probability of event acquisition while reducing power consumption by only activating sensor nodes in a target area. Other sensors are activated in standby mode by receiving wake-up calls sent by those sensor nodes when they detect events. We also evaluate the ability of event detection and power consumption of the proposed method.

In large-scale disasters such as earthquakes, a quick and safe evacuation is necessary. For this purpose, it is important to smoothly share information about damaged roads among evacuees. However, in large-scale disasters, the communication infrastructure might become damaged to the point of being unusable or subject to a loss of power. As alternatives means of communications, various methods using the delay tolerant network (DTN) concept, in which mobile terminals directly communicate without using a communication infrastructure, have been proposed for disaster communication. However, when using the DTN, nearby mobile terminals need to exchange road information many times, so their power consumption will increase. Moreover, when a blackout occurs in a disaster, it may become impossible to charge the mobile battery, so it is important to reduce its power consumption. In this paper, we propose to place information boxes at multiple locations that store the information on road locations that have sustained damage. By exchanging such road information through the information boxes, i.e., uploading and downloading the information at the information boxes, one can expect to dramatically reduce the power consumption of mobile terminals. We also propose a method of determining the placement of the information boxes that considers the estimated number of evacuees passing through and their separation. A numerical evaluation using a multi-agent simulation shows the effectiveness of the proposed method.

Information on evacuation shelters and routes is important for evacuees to evacuate safely and promptly when a disaster occurs. To take appropriate evacuation routes, evacuees need to gather information on roads that are damaged. However, in large-scale disasters, network infrastructure can be damaged and become unusable in many cases. To solve this problem, some existing studies propose providing evacuation routes by collecting road information from mobile terminals of evacuees by using a delay tolerant network (DTN) without using network infrastructure. However, in the existing works, congestion caused by evacuees concentrating on a specific route is a problem. This congestion is caused by identical evacuation routes being presented to all evacuees. Therefore, in this paper, we propose recommending different routes to evacuees on the basis of evacuee attributes (e.g. age) to alleviate congestion on roads. We numerically evaluate the proposed method by multi-agent simulation (MAS) and show that it achieves a 22% or greater reduction in the average evacuation distance and 44% or greater reduction in the average evacuation time where the number of evacuees was 30% of the daytime population.

The Ethernet frame goes round and round when an Ethernet network includes loop links. To solve this problem, the spanning tree protocol(STP) has been proposed for constructing a virtual tree network on an Ethernet network when the Ethernet network includes loop links. The STP is implemented on various Ethernet switches. The STP suspends some physical links to construct the tree network. These suspended physical links stand by, and they are used for backup when there is trouble on a tree network link. Therefore, all traffic is concentrated on the virtual tree network. Even if traffic is jammed on the network, the suspended physical links are usually still not used. Therefore, in this work, we describe a method that uses Ethernet Bypass Nodes(EBN) so that only communications between specific nodes can pass through the physical links suspended by STP as a bypass to improve communication quality.