For several years, Fujitsu has been researching and developing high-speed packet switching networks, the result being an integrated multimedia information networks architecture. This architecture has already been applied to LAN systems and can now be applied to wide area corporate networks thanks to the new developments described in this paper. The most important technology-the bus matrix switch-provides a quantum leap in processing capacity up to several Gbit/s (few millions of packets every second), while keeping a very low switching delay. The performance evaluation based on our prototype models is also considered in detail. For example, a voice delay of less than 20 ms is obtained for five-hop communication. The new technologies will greatly improve for computer networks and will also enable basic and broadband ISDN.

Integrated Services Packet Network Using Bus Matrix Switch

A communication method and packet switching system in which packets comprising logical addresses and voice/data information are communicated through the system by packet switching network (116) which are interconnected by high-speed digital trunks (118) with each of the latter being directly terminated on both ends by trunk collectors (131, 140). During initial call setup of a particular call, central processors (115) associated with each network (116) in the desired route store the necessary logical to physical address information in the controllers which perform all logical to physical address translations on packets of the call. Each network comprises stages of switching nodes which are responsive to the physical address associated with a packet by a controller to communicate this packet to a designated subsequent node. The nodes provide for variable packet buffering, packet address rotation techniques, and intranode and internode signaling protocols. Each packet has a field which is automatically updated by the controllers for accumulating the total time delay incurred by the packet in progressing through the networks. Each processor has the capability of doing fault detection and isolation on the associated network, trunks, and controllers by the transmission of a single test packet. The testing is done solely in response to the test packet and no preconditioning of controllers or network is necessary.

Fast packet switching system

This paper focuses on network delays as they apply to voice traffic. First the nature of the delay problem is discussed and this is followed by a review of enhanced circuit, packet, and hybrid switching techniques: these include fast circuit switching (FCS), virtual circuit switching (VCS), buffered speech interpolation (SI), packetized virtual circuit (PVC), cut-through switching (CTS), composite packets, and various frame management strategies for hybrid switching. In particular, the concept of introducing delay to resolve contention in SI is emphasized, and when applied to both voice talkspurts and data messages, forms a basis for a relatively new approach to network design called transparent message switching (TMS). This approach and its potential performance advantages are reviewed in terms of packet structure, multiplexing scheme, network topology, and network protocols. The paper then deals more specifically with the impact of variable delays on voice traffic. In this regard the importance of generating and preserving appropriate length speech talkspurts in order to mitigate the effects of variable network delay is emphasized. The results indicate that a desirable length of talkspurt "hangover" of about 200 ms will accomplish this without unduly affecting speech activity, and that, under these circumstances, the perceptable threshold of variable talkspurt delay can be as high as about 200 ms average. As such, the results provide a useful guideline for integrated services system designers. Finally, suggestions are made for further studies on performance analysis and subjective evaluation of advanced integrated services systems.

Delay Related Issues in Integrated Voice and Data Networks

A utility for enabling real-time, point-to-point communications over computer networks between users having dynamically assigned Internet Protocol addresses includes the ability to identify incoming communications, and, based on the identity of the incoming communication, selectively responding. In one embodiment, an information profile contained within an incoming signal is compared to a plurality of information profiles contained within the personal directory of a user, and, if a match occurs, the notification signal associated with the matched profile is generated. In an alternative embodiment, the information profile contained within the incoming communication includes an identifier of a notification signal which is used to select from a number of predefined notification signals resident within the user's private directory.

Method and apparatus for providing caller identification based responses in a computer telephony environment

A multiserver queueing system with two classes of customers is considered: a type-1 (narrowband, NB) customer requires a single server, while each type-2 (wideband, WB) customer requests n of the m servers (n is not random) Severs allocated to a type-2 customer are seized and released simultaneously Service times are exponentially distributed with mean 1//sub mu i/ for type i customers (i=1, 2) Blocked type-1 customers are cleared while blocked type-2 customers may be delayed in an infinite waiting room A type-1 customer enters service immediately upon arrival if at least one server is free, irrespective of the status of the type-2 queue WB customers have restricted access to the service facility; a cutoff parameter specifies the maximum number of type-2 customers that can be in service at the same time Two approaches, moment-generating functions and matrix-geometric techniques, are considered for the computation of the system performance, that is, the mean waiting time in queue and the probability of delay (ie nonzero waiting time) for type-2 customers, as well as the probability of blocking for type-1 customers >

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A multiserver queue with narrow- and wide-band customers and wide-band restricted access

A new subscriber communication system and its design philosophy are described. In addition to telephone communication, the system is simultaneously able to offer data communication, still picture communication, etc. The system is composed of a packetized voice/data terminal, a multi-service switching equipment and the digital subscriber loop connecting between them. The system utilizes the existing subscriber line efficiently and is entirely suitable for coming telephone and data public digital network. 64 kbit/s PCM coded voice conversation and 48 kbit/s data communication were achieved simultaneously over 96 kbit/s digital subscriber line which was spanned up to 2 km.

An Approach to Multi-Service Subscriber Loop System Using Packetized Voice/Data Terminals

This paper outlines the features of a new integrated switching system for voice and data. It is composed of integrated subscriber terminals, integrated subscriber lines, an integrated digital switching system, and integrated storage facilities. This paper shows that the introduction of the integrated storage facility can create various new service utilities and improve the traffic capacity of the system.

Integrated Digital Switching System with Queueing Storage Facility

In tomorrow's automated offices, an important role will be played by voice storage systems which enable telephone communication at any time. This paper discusses the problems and technical consideration in designing a flexible voice storage system featuring a distributed structure whose capacity can be expanded at will. Recent advances in microprocessors and magnetic minidisk devices have made this kind of system economically feasible. An efficient new method of real-time accessing of distributed files is proposed which guarantees continuous storing and forwarding of voice messages. A simple method of estimating the required file capacity is also given on the basis of a voice message traffic analysis.

A Design Model for a Real-Time Voice Storage System

To improve the ratio of successful calls, a new switching system permitting callers to store messages when the called party is busy or does not answer can be constructed by adding a message storing function to the conventional circuit switching system. The mutual traffic influences exerted by this combination of circuit and message switching systems have not yet been clarified. This paper considers a two-stage loss system traffic model consisting of a circuit switching system that has a message switching system connected to it. The traffic characteristics of this model are analyzed using the nonindependent state transition probability, which depends upon the interacting states of the circuit and message switching system. A method of solving the state equations by determining the state transition probabilities of the message switching system from the state probabilities of the circuit switching system is proposed. Using this method, the mutual traffic influence of the circuit and message switching systems is evaluated.

S. Hattori

Papers

An Approach to Multi-Service Subscriber Loop System Using Packetized Voice/Data Terminals

Integrated Digital Switching System with Queueing Storage Facility

A Design Model for a Real-Time Voice Storage System

Traffic Analysis of Delayed Delivery Services Considering the Correlation Between Circuit Switching and Message Switching