The ICN (Information-centric networking) is a new network architecture that uses named information rather than IP address for content retrieval and delivery. Owing to the built-in multicast and in-network caching capabilities, ICN is expected to achieve efficient content delivery. Actually, however because the cache capacity of the router is limited, there is a possibility that ICN performance may not be as good as expected. This paper, taking NDN (Named Data Networking) as a study target, analyses the overload characteristics of NDN network and clarify performance deterioration mechanism caused by excessive content requests. Based on these results, it proposes the content caching control as well as the request forwarding control that adapt to the network state. By these controls, link congestion is mitigated and content acquisition time is significantly improved. It also reveals that the control effect varies considerably depending on the topological relationship between the location of the publisher and users.

Heart disease has the second high mortality rate behind cancer in Japan, and requires quick treatment. To take a part in emerging mHealth, we developed a wearable heart disease monitoring and alerting system “Dentan”. Dentan continuously monitors patient's ECG in his/her daily activities and issues an alert to the patient as well as surrounding people if it detects abnormal heart behavior. Dentan consists of a wireless ECG sensor and a smartphone to achieve light-weighted, low-cost system that does not degrade the patient's Quality of Life. In parallel, we developed ECG analysis algorithm to detect R-wave as well as arrhythmia and performed demonstration experiments to validate its effectiveness. We implemented these algorithms in wireless ECG sensor rather than in smartphone to save power consumption of ECG sensor caused by radio communication.

If IP network only uses conventional routing protocols such as open shortest path first (OSPF), some portions of the network become congested while other portions remain underutilized depending on the variations of traffic demand. MPLS that provides explicit routing along pre-determined path can improve load balancing throughout the network, thus achieves effective network resource utilization. In this paper, we introduce the overlay path that passes through strategically placed relay-node. By selecting a suitable relay-node dynamically, the network can proactively keep pace with changing traffic demand. We show that relay-node based load balancing can achieve almost equivalent network performance as global optimization by Linear Programming, while reallocating only 20% of total traffic. Furthermore, by selecting two kinds of path, namely primary path as the shortest path and overlay path as a detour path, in reference to VPN label, service differentiation is achieved, thus realize user-centric network.

TCP performance over high-speed ATM networks is evaluated. In TCP over UBR (unspecified bit rate), packet losses caused by congestion deteriorates throughput and fairness. Even if early packet discard (EPD) is added, fairness still remains as a problem as long as cell loss occurs. TCP over ABR(ER) (available bit rate-explicit rate) can provide high performance by suppressing cell loss, as long as ABR rate control does not interact with TCP flow control. Coarse timer granularity and large window size can avoid the interaction. When end-to end ABR is not available, further enhancement of TCP control using implicit or explicit congestion notification is needed for performance improvement.

This paper investigates the characteristics of ABR explicit rate control algorithms in the WAN environment. We also propose two new control algorithms based only on traffic measurement. An ABR service is expected to make it possible to utilize bandwidth effectively by closed-loop congestion control, and several control algorithms have been proposed. However, for WAN environment, a long propagation control delay will affect the effectiveness of control algorithms. Additionally, if a network supports large numbers of connections, some of the algorithms may not work well. Thus, we first categorize the aim and mechanism of control algorithms, including our proposed algorithms. Then, we evaluate their characteristics by simulation in WAN environment from the viewpoint of throughput, robustness, quickness, stability, and fairness. Using this analysis, we discuss their effectiveness in WAN environment.

A granulated broadband network (GBN) is proposed as an intermediate asynchronous transfer mode (ATM) based platform to be part of an evolution scenario toward B-ISDN. The GBN enables various types of services to be provided including 64-kb/s-based services and broadband services. In the GBN, information is transformed into ATM cells at subscriber line terminals or at customer premises and is transferred through ATM networks; consequently, the cost feasibility of a single-channel cell assembly/deassembly device is a significant factor in economically providing ATM-based conventional services and interworking between STM and ATM networks. Various virtual path capacities with a fine degree of granularity can be provided in a mesh structure between transit modes in the GBN. Economic feasibility studies of the GBN, by simulating on certain large-size real networks in the greater Tokyo area, indicate the possibility of a more than 50% cost reduction in transit networks.>

The authors discuss the architecture and protocol for broadband ISDN (B-ISDN) based on the CCITT standards. The discussion attempts to address the general concept of B-ISDN architecture and protocol and, whenever possible, present alternatives and the rationale for decisions in the selection of the protocol. B-ISDN is presented as a network evolution, and the impact of the asynchronous transfer mode (ATM) on the network is described. The role of virtual channel and virtual path in B-ISDN is discussed. The B-ISDN protocol structure and lower layer functions comprising the physical, ATM, and adaptation layers are presented, and the tentative trends of signaling and traffic control for the B-ISDN are delineated.>

The traffic characteristics of an asynchronous transfer mode (ATM) network are analyzed by theoretical methods. A new method is proposed to express the burstiness of the cell arrival process. Both statistical multiplexing and statistical bandwidth allocation are quantitatively evaluated. When packetized video traffic and voice traffic are multiplexed, the number of multiplexable sources strongly depends on the peak bit rate of the multiplexed video sources, and statistical bandwidth allocation is ineffective without control. On the other hand, lowering the peak bit rate of video traffic effectively improves bandwidth utilization.>

The history and achievements of ISDN (integrated services digital network) standardization in the CCITT are reviewed. Two of the most important developments, ISDN basic and supplementary services and broadband ISDN, are focused upon. The underlying concepts in the discussions of ISDN standardization are briefly explained.>