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In multicast delivery in a network environment with various bandwidth limitations, it is effective to apply the layered multicast technique, which realizes delivery at a reception rate matched to each receiver, although the rate is set discretely. This paper assumes a multimedia session such as a multichannel broadcast or a video conference, composed of multiple streams. In such an application, it is desirable from the viewpoint of efficient use of bandwidth that not only should the streams be transmitted with stable quality, but that the rate should be assigned according to requests, such as attention to the speaker. However, it is difficult to achieve the above goal by directly applying the conventional layered multicast rate control technique, since each stream controls the rate independently. From such a viewpoint, this paper presents a session level mechanism covering multiple layered streams. A multiple streams controller (MSC) is introduced into each receiver, and each MSC autonomously controls the reception rate with interstream coordination in the session. The MSC monitors the reception state of the multiple streams simultaneously and estimates the bandwidth information on the bottleneck link and the set of transiting streams, based on the detected congestion data. Based on the estimation, the learning efficiency of the reception rate is improved and rate assignment control over the streams is applied. An evaluation is performed by computer simulation, and it is shown that the reception quality of the stream is improved by applying the proposed method, and that the reception rate can be coordinated among the streams. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(8): 18–31, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20142 [ABSTRACT FROM AUTHOR]

This paper proposes Full-Net (Flexible Multi-QoS Logical ATM Network), a simple, flexible, and cost-effective network architecture that will enable the development of an advanced multimedia communications network. The backbone of this Full-Net is a VP (virtual path) network where mesh interconnection is made possible between all VCH (virtual channel handler) switches. End-to-end QoS (quality of service) control is executed at access points to the VP network to map out each optimum VC (virtual channel) according to the VCs' respective service characteristics. This is done independently and simultaneously on the same physical ATM network. In the proposed network, a relatively small size switching system is utilized as a transit switch or a local switch depending on the service request. That is, the logical topology of the VC network is altered in response to individual service requests, and multiple VC networks are realized by overlapping them on the same physical network. In order to assure high QoS and construct an optimum VC network, two parameters which characterize the VC network topology are introduced; one is the disjoint route D and the other is the hop limit H. Traffic reliability is the most important QoS factor, and it is shown that an optimum disjoint number D can be determined to maximize the network resource. In the Full-Net, it is clearly shown that it is possible to control easily the end-to-end delay characteristic, also a critical QoS factor, at one or two VCH access points to VP network. The flexible node system PUN (programmable unified node) used in the Full-Net is also described in this paper. The Full-Net described is proposed as an efficient solution for sophisticated network architectures which will satisfy the demand for new services and will flexibly meet the varying demands of the future multimedia age. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(6): 47–58, 1997 [ABSTRACT FROM AUTHOR]

To achieve efficient and highly reliable network operation requires a mechanism to monitor and control the states of remote a mechanism to monitor and control the states of remote terminals (nodes) automatically by control operation system (OpS). This paper is an attempt to obtain such a mechanism. Operation and maintenance (OAM) cell is defined that contains the connection information for remote monitoring and the control path to be set. By successively transferring OAM cells according to the connection information, remote monitoring and control virtual paths (VPs) can be obtained autonomously. Based on the proposed idea, this paper discusses the structure of the OAM cell, the functions to be provided in the cross-connect system, and transmission algorithms for the OAM cell. The proposed system well utilizes the unique feature of the ATM cell. The cell routing information (VPI) is transferred within itself. [ABSTRACT FROM AUTHOR]

Recently, broadband applications such as data grids and IP-Storage Area Network have been proliferating. In these applications it is necessary to exchange large amounts of data quickly over networks with a capacity of several gigabits per second. For this purpose, various kinds of congestion control have been proposed for use in such broadband networks. In these kinds of congestion control, the idle bandwidth of the network can be used quickly by increasing the communications speed at the time of communications. On the other hand, complicated forms of congestion are generated in the network. Therefore, when these kinds of congestion control and the existing TCP communications coexist, the existing TCP communication is strongly compressed. In the present paper, TCP with multiple congestion control policies (TCP-MP) is proposed in order to make swift use of idle bandwidths in the network. In TCP-MP, an additional congestion control policy is provided in addition to using a form of congestion control similar to that in conventional TCP, so that information on the variation of the RTT between the transmitter and the receiver can be used to estimate the idle bandwidth of the network and the communications speed is chosen in such a way that the idle bandwidth is used up. Hence, it is possible to quickly use the bandwidth of the network within the range in which the existing TCP communications is compressed. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(1): 45–57, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20310 [ABSTRACT FROM AUTHOR]

A conventional IP network is a connectionless, best effort network, but has difficulty guaranteeing the Quality of Service (QoS). To guarantee end-to-end QoS, the Internet Engineering Task Force (IETF) has proposed bandwidth reservation protocols such as the Resource ReSerVation Protocol (RSVP), but a protocol that guarantees all bandwidth reservation requests has not been realized. To address this, with the objective of implementing bandwidth reservation capable of reliably accepting the bandwidth reservation requests regardless of the size of the requested bandwidth, the authors proposed Waiting Bandwidth Reservation Communication, which is an extension of RSVP. By using this method, we verified that excellent results compared to conventional RSVP are obtained when all bandwidth reservation communications pass over a special path and the bandwidth reservation requests exceed the bandwidth available for reservation along that path. On the other hand, in a wide-area network such as the Internet, the problems are that all of the bandwidth reservation communications are not along special paths and unnecessary waits are generated when waiting for bandwidth reservations. With the objective of solving these problems, in this paper, we propose RSVP that considers the waiting time until the start of bandwidth reservation and demonstrate through simulations how the proposed method solves these problems. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(8): 71–81, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10103 [ABSTRACT FROM AUTHOR]

IP multicast over ATM is considered interesting as a technique to realize multicast communication in ATM network. Proposed methods to realize IP multicast over ATM are the server method and the mesh method. The server method has the problem that a certain delay is required in reconstructing AAL5 SDU in the server. The mesh method has the problem that the point-to-multipoint VC must be set in the receiver group from all senders. This paper proposes the multi VC data server method as follows, as a new method to solve these problems. Multiple point-to-multipoint VC are prepared in the server. When multiple data are transmitted in parallel, different VC are used to reduce greatly the delay produced in the server method. The performances of the multi VC server method, the server method, and the mesh method are compared, and it is shown that the multi VC server method is effective in the sense that the data are transmitted with the shortest data transmission delay. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(6): 11–18, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10070 [ABSTRACT FROM AUTHOR]

Recently, the spread of multicast communication is expected from the perspective of the efficient utilization of the network. Since the connection state of multicast communication clearly differs from that of conventional unicast communication, the optimum network topology is believed to change if multicast communication spreads in the future. The authors studied the network topology used when unicast communication and multicast communication are mixed. It was found that the Delta-Star topology was optimal compared to the Star topology currently used in the lowest level of the network. In this paper, we studied the performance of each topology from the perspective of the required capacity of the equipment and the costs required to construct the network when a circuit switching or a connection service was assumed and the multicast traffic increased. Furthermore, we proposed a network extension method that changed the topology from the Star to the Delta-Star topology and evaluated the performance. We found that by using a relatively simple extension method to set the locations of the transmission route link extensions, adequate cost performance was obtained. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(6): 69–83, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1166 [ABSTRACT FROM AUTHOR]

A network interconnecting facility such as a router and a bridge may convert protocol data units passing through it. For example, ATM networks convey 53-byte fixed size cells. On the other hand, variable-length packets are transmitted on legacy LANs such as 10BASE, FDDI, and so on. Thus, an edge device at the boundary of an ATM network must perform segmentation and reassembly of packets. In this paper, we focus on packet reassembly at an edge device under the condition that interactive and noninteractive data-transfer traffics coexist. Via simulation of a queuing model, we investigate the influences of traffic load, packet length, and service priority on packet loss and delay characteristics. The result shows that one should determine the reassembly-buffer size taking into account the packet size for noninteractive service when the interactive service has high priority. Furthermore, one should determine the priority levels of both services depending on their delay characteristics when the bursty nature of the ATM traffic is reduced by flow control. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 84(1): 40–48, 2001 [ABSTRACT FROM AUTHOR]

The basic service categories necessary for the information highway, namely, VLL (virtual leased line), VCS (virtual circuit switching), COPS (connection oriented packet switching), and CLPS (connectionless packet switching), have been proposed [9]. In this paper, we propose simplified practical design and control methods for the ATM systems to implement these categories of service. VLL may be realized by a cross-connecting technology of transmission systems. For VCS, the transmission speed is designed so as to satisfy the average call loss rate by applying a multidimensional traffic model. For COPS, using the call blocking probability as the call level QoS (quality of service), the maximum number of virtual channels (VCs) is designed to satisfy the QoS requirement. With the cell level QoS, the cell loss rate and mean cell delay, the transmission line speed and the buffer size are designed to satisfy the QoS requirement. In a system integrating COPS and CLPS, COPS is given nonpreemptive priority over CLPS, the latter being served on a best effort basis. In overload traffic conditions, a control method is proposed in which the number of assigned VCs is reduced so as to meet the cell level QoS requirement. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(10): 1–10, 2000 [ABSTRACT FROM AUTHOR]

To utilize a shared buffer efficiently, a shared buffer ATM switch with multicast function should not replicate a multicast cell at the arrival time, but should replicate it at the departure time. In such a switch, however, a multicast cell occupies the buffer for a long time, since it must stay there until the copy is sent out to all destinations. In this paper, we propose an ATM switch which can flexibly change the service mode. In the switch, if the buffer becomes congested, it serves the unicast cells prior to the multicast cells, which can reserve more vacant buffer spaces for the arriving cells. To do so, the switch has two dedicated address queues, one for the unicast cells and the other for the multicast cells. We evaluate cell loss characteristics under various load conditions via simulation. The switch is shown to provide a lower cell loss probability than the previously proposed switches. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(10): 1–9, 1999 [ABSTRACT FROM AUTHOR]

With the improvement of the speed of computers in recent years, there is required a local area network (LAN) that can realize a high-speed] broadband communication. For this purpose, asynchronous transfer mode (ATM) LANs bassed on ATM technique is considered important. This paper considers the bandwidth reservation control as a means of traffic control in ATM LAN and evaluates the performance by simulation. The evaluation as made for the following methods of congestion control: ACK/NACK method,based on the ACK/NACK signal which is results when the bandwidth reservation succeeds/ fails; the dynamic ACK/NACK method, which is an improvement so that the control can S adapted to the traffic load; and control method based on the link information from the switch. It is shown for the single-stage switching network that the dynamic ACK/NACK methode has a better performance when the traffic is low but the control method based on the link information has the highest performance when the traffic is high. It also is shown for the three-stage switching network that the control method based on the link information has the highest performance. [ABSTRACT FROM AUTHOR]

This paper proposes an access protocol with a high throughput for the ultrahigh-speed local area network (LAN) and metropolitan area network (MAN) with the transmission capacity exceeding 100 Mbps. The slottedring configuration is suited to the access method for the ultrahigh-speed LAN/MAN. Several protocols have been proposed, such as DQDB and ATMR, which, however, have problems in that the throughput in DQDB cannot reach the transmission capacity and the throughput in ATMR decreases when the traffic is nonuniform. In the proposed protocol, the reset signal circulates the ring and the fairness of the access is ensured by limiting the number of slots to be sent by each node by the window size. The number of slots to be sent is not limited if none of the downstream nodes has data to be sent. This helps to realize a high throughput independently of the traffic situation. As the result of performance evaluation, it is verified that the proposed protocol is useful in the following two points: (1) approximately 1.8 times higher throughput is realized compared to the existing protocols when the traffic concentrates to a particular node; and (2) the delay time is suppressed to a low value for burst traffic such as video. [ABSTRACT FROM AUTHOR]

In realization of high-speed and broadband networks of the next century, expectations are toward optical switching and a linear lightwave network (LLN) is proposed as one of the possibilities. Using LLNs, this paper proposes a multicast routing system in which a tree structure is formed with no loop inside the network. In this way, the waste of bandwidth caused by transmission of signals to unintended destinations is avoided. The scheme in which the tree is settled dynamically in case of generation of a call is proposed and its function is evaluated through simulations. As the results, the possibility of the efficient use of the unused links and realization of call setup control of equitable terminals are shown. Further, because of inherent LLN characteristics, the generated call blockings are small and superior performance is achieved in comparison to the previously proposed methods. [ABSTRACT FROM AUTHOR]

With the advent of broadband integrated services digital network (B-ISDN), there is the increasing need for high-speed multimedia systems also in the area of local area networks (LANs). It is obvious that the conventional systems such as CSMA/CD or token ring cannot cope with those requirements. At present, several new access control methods are proposed for slotted ring (or bus) LANs suited to transmission rates above 155 Mbps. This paper reviews the characteristics of those methods in a systematic way and proposes a new access control method called distributed reset algorithm (DRA). DRA can provide high throughput while maintaining the almost strict access fairness by using a new control called ‘access bit control’ in addition to the already known window control. [ABSTRACT FROM AUTHOR]

This paper proposes an asynchronous transfer made (ATM) switch architecture to realize a large-scale ATM exchange to be used for the future spreading era of ATM networks. The proposed switch architecture is based on a three-stage Clos network which consists of many element switches to obtain a large-scale ATM switch. In the proposed ATM switch, the switches at the first- and lad-stage of the Clos network are the shared buffering ATM switches; the elements switches at the second stage are the input buffering ATM switches. Because it is preferable to build various capacities of ATM switches in the same way with the three-stage Clos network architecture, the element switches of the second stage of Clos network should be scalable. Therefore, it is proposed that the second stage switches are the input buffering ATM switches. On the other hand, the first- and last-stage switches are the shared buffering ATM switches to prevent degradation of cell loss rate. The proposed architecture has been evaluated by computer simulations, and it shows that internal link speed-up and flow control prevent the degradation of cell loss rate. It also shows that degradation of cell loss rate can be ignored even when the ATM switch aim is expended. [ABSTRACT FROM AUTHOR]

In an asynchronous transfer mode (ATM) network, various calls with different transmission quality requirements ranging from tow bit-rate data signals to high bit-tare motion picture signals are applied. Therefore, it is important to determine how to allocate network resources to those calls and to judge whether those calls can be accepted. This paper proposes a can admission control scheme based upon a data table that holds the relationship between average bit-rate and needed bandwidth for aggregated signals in each quality class obtained beforehand by simulation. This proposed scheme assumes broadband services where the aver-age bit rate and burstiness of aggregated signals can be estimated clearly with predictable value ranges. This proposed scheme uses a conventional scheme for service quality class control. The following characterizes this proposed scheme: (1) it is suitable for real time call processing because it has small table search processing and a simple table search algorithm; (2) it realizes more accurate control due to a decreased data volume requirement and more precise data preparation than is the case for some of the conventional schemes; (3) it can be expanded easily to handle increases in the number of quality classes; and (4) it provides control in terms of statistic multiplexing effects between each quality class (also found in some of the conventional schemes). [ABSTRACT FROM AUTHOR]

This paper considers a new transmission method (quasisynchronous transfer mode, Q-STM), as a means to eliminate both the cell loss and the network delay fluctuation in an ATM network. The concept of time-switch in circuit switching is introduced into the ATM switching framework. A switching structure and the call establishment procedure are proposed. In the proposed method, the time-switch is introduced, which eliminates in principle the output port contention in the ATM switching fabric. By preparing a buffer with a certain capacity, cell loss due to buffer overflow in the output port of the ATM switch can be completely eliminated. The concept of subframe is newly introduced, which serves as the unit of time-switching. A three-layered structure is applied to the frame structure, composed of the frame, the subframe, and the slot. This helps to reduce delay due to time-switching, compared to the case in which the concept of subframe is not introduced, while maintaining the flexibility of bandwidth allocation. Additionally, the method is based on ATM switching, and the ordinary ATM cells not bound to the frame can be transmitted and ATM-switched by the idle slot in the frame. This enhances the features of ATM, i.e., effective use of the circuit by the statistical multiplexing effect. The basic characteristics concerning the quality of the ordinary ATM cell are analyzed by simulation. [ABSTRACT FROM AUTHOR]

This paper describes a hitless path switching technique that utilizes fully the benefits of an ATM. First, hitless path protection switching in ATM networks is discussed. It is shown that for the path configuration of working and preestablished protection paths, the best switching method switches on the transmitting side. Then the proposed switching algorithm is described, along with several examples of its application to mesh and ring networks. A cell interval compression method suitable for hitless path switching is proposed that empties and disconnects the transmission delay difference absorption buffer. Finally, an approximate formula is proposed that directly determines the multinode queuing delay. This delay is needed to calculate the capacity of the delay difference absorption buffer. The accuracy of the formula is confirmed by simulations. [ABSTRACT FROM AUTHOR]

This paper considers the application of the modulation level-controlled variable capacity radio channel to asynchronous transfer mode (ATM) networks and analyzes the cell loss characteristic. A system is proposed in which the transmission capacity of the overall system can be enlarged by controlling the number of modulation levels. This helps to enhance the absorption effect for the traffic variation in ATM networks. Therefore, the proposed system can reduce the cell loss probability. As a result of quantitative analysis of the system. it is shown that the cell loss improvement is by the factor of several hundreds to several thousands compared to the virtual path fixed-capacity transmission system and several to several thousands compared to the virtual path capacity control system proposed up to present. [ABSTRACT FROM AUTHOR]

The Virtual Path concept has several beneficial features to construct an economical and efficient Asynchronous Transfer Mode (ATM) network. The Virtual Path capacity control technique can increase network flexibility and improve transmission efficiency through statistical sharing of facilities. This paper presents an adaptive virtual path capacity control method which maximizes transmission efficiency under the condition of limited processing load. Evaluation shows that the proposed method successfully im- proves network transmission efficiency with a slight increase in processing load compared to the fixed virtual path capacity scheme. [ABSTRACT FROM AUTHOR]

This paper analyzes the performance of a number of MAC protocols m high-speed ring-type networks and determines the suitable region for each protocol. The authors previously have evaluated the slotted rings, register-insertion rings and register-insertion-type slotted rings, and begin with the analysis of the token ring in this report. To compare the results of the various analyses, the models of each MAC protocol are constructed under the same set of conditions and evaluated with the same method (EPA). Since the nodes of each model are assumed to have buffers to finite capacity, the discussion of buffer overflow is made possible. The results obtained from analysis matched closely with simulation results verifying the accuracy of the analysis. The MAC protocols also are analyzed under high-speed network conditions, and a comparison of the results reveals the most suitable protocols for various environments keeping m mind the issue of buffer overflow. [ABSTRACT FROM AUTHOR]

With the widespread use of high-speed broadband communication, nonblocking switching networks in video distribution and other applications for the broadcast distribution connection will be required. Numerous studies have been made of performance analysis for switching networks for one-to-one switching connections, but it is anticipated that a future study is needed for one-to-many switching connections. This paper presents a construction for the copy distribution stage, which copies the cell for the broadcast distribution. The copy distribution stage is composed of a multistage connection network. The basic principle of operation is that the cells are arranged appropriately and are copied by the differential address driving. The proposed network is suited to high-speed operation since nonblocking self-routing is realized and the control logic is simple. The proposed network assumes that it precedes the network for one-to-one switching connection. Then one-to-many broadcast distribution connection is realized. [ABSTRACT FROM AUTHOR]

The NUCLEI (Nagasaki University codec using large interframe prediction errors as important parts) method is proposed in this paper as a new interframe coding method for the asynchronous transfer model (ATM). Characteristics of this method are as follows: 1) interframe predictions are done using a full band, considering the high coding efficiency during the normal state; 2) interframe predictions are done even after toll loss, considering the high coding efficiency after cell loss; and 3) utilizing the fact that the small moving areas are less important than the large moving areas in dynamic images (motion pictures), large moving areas or blocks with large interframe differences are allocated to priority (higher priority) cells as priority blocks and comparatively small blocks are allocated to nonpriority (lower priority) cells as nonpriority blocks. These characteristics are realized by assigning frame memories for storing priority block signals in addition to frame memories storing all images. It is shown by computer simulations that good interframe coding characteristics can be realized in both during the normal state and after a cell loss. [ABSTRACT FROM AUTHOR]

This paper discusses the technical feasibility of the multimedia metropolitan area network based on the tree-shaped broad- band network, employing two-way CATV technology. In the proposed network, all information can flow on any transmission line through the head end. This leads to the following features, which cannot be realized in the star network as in the telephone net- work: (1) Flexible services are provided. (2) An efficient information communication service can easily be realized. (3) It is easy to provide the high- speed broadband service at a low cost. (4) The security of the network can be improved. The following systems were developed by the authors as examples of the information communication services utilizing those features: TDMA circuit switching service using "time-slotted bus with control window." CSMA/CD packet switching service using "beat signal level detection," and TDMA video switching service, where several video signals are multiplexed as analog signals. Those services can be provided to were than 101000 subscribers in a service area of diameter 20 km or more. The system is expected to provide the basis for the information communication in local communities, together with the widespread use of urban-type CATV. [ABSTRACT FROM AUTHOR]

With the widespread use of broadband communication, the nonblocking N:1 multiconnection switching network is required in video distribution and in other applications. In most off the N:1 multiconnection nonblocking switching networks, some rearrangements or simultaneous origination of multiconnection calls must be assumed. For the switching network which is nonblocking for any N:1 multiconnections under no conditions, only a few studies have been made on the three-stage switching network. This paper proposes an efficient method of constructing a switching network which can realize arbitrary nonblocking N:1 multi- connections. First, the construction of a d:1 connection network is shown which serves as the fundamental component of the proposed structure. Then it is shown that by connecting several d:1 connection networks an N:1 multiconnection switching network which can realize arbitrary N:1 connection can be constructed. The number of cross points required in the switching network is calculated. [ABSTRACT FROM AUTHOR]

This paper will present a method of constructing a broadband ring network using multiple transmission lines. It is called the shuffle ring (SR) network because all nodes that have a function similar to that of a switch element in a shuffle switch are distributed systematically over the ring. The SR network employs a simple and autonomous routing algorithm at each node which is connected with only a part of the total ring lines. In spite of this simplicity, it shows some excellent throughput vs. delay characteristics as well as high reliability and flexibility. [ABSTRACT FROM AUTHOR]