This paper proposes an implementation scheme for the self-healing function in ATM networks and assesses its performance. First, our proposed ATM self-healing scheme is described. This scheme realizes more rapid restoration of failed virtual paths than other self-healing algorithms, supports the node failure case, and minimizes the spare resources required. Next, an implementation scheme is proposed. We propose that the self-healing function be implemented as a software process, and that OAM cells are utilized for fast message transmission. Next, results of a prototype system that we implemented on an ATM cross-connect system are discussed. The fundamental characteristics of restoration performance are measured using an experimental network. Based on these results, an NE processing system analysis and computer simulation for estimating the characteristics as applied to a real-scale network are discussed. Finally, a management scheme for self-healing is proposed based on the TMN concept.

The paper presents a new ATM transport network technique that realizes the direct virtual path configuration by using path bandwidth control and the virtual path group concept. Direct virtual paths link local switches directly and enable channel set up processing to be eliminated from transit nodes. However, this configuration, which employs no toll switches, suffers from several problems such as reduced utilization of virtual path bandwidth and increased difficulty of localized network management based on network segmentation. The authors introduce virtual path bandwidth control and the virtual path group concept into ATM transport networks to realize the direct virtual path configuration in a very efficient manner. Virtual path bandwidth control enables the optimum balance between switching and transmission systems to be struck. Virtual path groups make it possible to provide a localized network management capability in a way similar to that available in a conventional network.>

This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed.>

A credible introduction strategy for B-ISDN is described. The first step is the introduction of asynchronous transfer mode (ATM) techniques into the path layer. The strategy is shown to be effective, since it enables not only the realization of a cost-effective and flexible network infrastructure, but also the provision of high-speed multimedia leased line services. The service advantages possible with virtual paths are also demonstrated. The authors' technical advances, including ATM network resource management techniques and network utilization enhancement techniques, are highlighted.>

The structure of the error correction coding schemes and a reconstruction method for lost cells are derived. The performance analysis includes transmission efficiency, interleave delay, and cell loss compensation performance. The results show that effective compensation performance, with high transmission efficiency and small interleave delay, is obtained by applying the proposed coding parameter selection. The cell loss compensation schemes yield high-quality performance with low cell loss probability.>

Broadband transport techniques and network architectures based on the virtual path concept are examined. ATM (asynchronous transfer mode) techniques, when coupled with recent technological innovations, are expected to pave the way for future universal transport networks. The virtual path concept, which exploits the ATM's capabilities, is proposed to construct an efficient and economic network. The concept matches current and anticipated technological trends well. Characteristics and implementation techniques of virtual paths are discussed. Advantages of the virtual path concept and its impact on the transport network architecture are demonstrated. The virtual path strategy is also shown to provide efficiently for networks with dynamic reconfiguration capability which will enhance network performance. Some basic analytical results on the dynamic control effects of virtual paths are provided.>

The development and system design of a new synchronous DS4 multiplexer with cross-connect function is described. This new multiplexer is expected to provide cost reductions due to more efficient use of transmission facilities, and rapid circuit provisioning. The multiplexer consists of three kinds of digital cross-connect blocks, a transmission terminating block, an intraoffice-interface block, and a controler. It is also expected to provide improved network maintenance, higher network reliability, and greater system versatility for new services.

Demand for high-speed wide-band telecommunication services is rapidly growing due to the remarkable progress in office, factory, and laboratory automation. These services are expected to be first introduced in leased circuits and then extended, to high-speed switched services. This paper presents the users' demands for such high-speed services and the NTT design concepts for the high-speed digital data transmission system (HDDTS) in NTT to provide such high-speed leased circuit service. The ISDN user-network interface is adopted. The basic high-speed pointto-point transmission service started in October 1984, and enhanced leased circuit service involving multiplexed interfaces and muitipoint circuits will be introduced in the fall of 1985.

The design objectives and test results of a new services integrated system using a packetized speech technique are presented. First, several important design parameters are investigated through theoretical analysis and computer simulation. Second, an experimental system for confirming the choice of design parameters as well as measuring the speech and data communication quality is described, and the test results of this system are discussed.