Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1997-12-16
2002-05-07
Jung, Min (Department: 2663)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S463000
Reexamination Certificate
active
06385196
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates, in general, to a communication system architecture having a management control agent and management control protocol therefor, and is particularly, but not exclusively, applicable to providing a communication interface between a narrowband network and a broadband network. More especially, the present invention creates a new management interface between a call server (that oversees system operation) and fabric control software that influences and controls operation of an asynchronous transmission mode system (termed an “ATMS”).
SUMMARY OF THE PRIOR ART
Globally, telecommunication systems are, generally, in a transitional phase between second generation, narrowband digital networks (such as the Global System for Mobile (GSM) cellular communication system) and future, multi-media digital networks (such as the Universal Mobile Telecommunication System (UMTS)) having broadband capabilities. This transition is necessarily required to support higher data rate communications, including video and internet applications, presently being proposed and made available. Unfortunately, this transitional phase also presents system operators with several dilemmas, and prejudices immediate implementation of such broadband systems. For example, until such a time when a free-standing broadband system becomes an accepted and freely available standard for all subscriber terminals (such as cellular telephones and data transmission devices), system operators are reticent to write-off their significant investments in current narrowband infrastructure technology. Indeed, such narrowband infrastructure technology already provides a rich set of services and service creation environments that would have to be re-implemented for deployment in broadband networks. Consequently, present-day narrowband systems must be adapted to accommodate both narrowband and broadband. users; with this statement particularly relevant to service and system management, call establishment and inter-working procedures between these different forms of network.
For an effective migration between narrowband and broadband systems (for the transitional phase), system operators must particularly consider an inter-working scenario when all subscribers connect to a narrowband network, but one or more intermediate broadband networks are used to relay information between these narrowband subscribers. Any interim solution should also optimise service and system management, while also providing infrastructure equipment that can be re-used in a fully-fledged broadband environment.
In more detail, telecommunication networks comprise nodes connected by communication resources (usually termed “links”), with a particular network technology characterised by the means of transmission of user and control information along these links and also by the routing and relaying functions embodied in the nodes. The term routing is used to describe the process of determining the path the information will take through the network, while relaying is the process of transferring information from one link to another, i.e. the information is merely passed, without alteration, from one channel resource to another. Routing and relaying functions are therefore core to the development of an efficient system having optimised service capabilities, with operator profits and subscriber service charges inherently entwined with such optimisation.
Taking GSM as an exemplary form of a narrowband digital network, user and control information (or “data”) is interleaved, using time division multiplexing (TDM), on a 64 kbit per second (kbps) pulse code modulated (PCM) bearer channel. Indeed, these bearer channels can each be framed to support four voice calls of 16 kbps, comprised from 13 kbps of sampled and encoded speech and 3 kbits of ancillary information, such as parity check and correction bits (and the like) and synchronisation information. Data is then relayed across a node by some form of synchronous TDM switching fabric, often of the ‘time-space-time’ type. Control information (e.g. call set-up and tear-down messages) logically follows the same path (although not always the same physical path) through the network as user information, and is terminated in each node for routing purposes. Routing is conventionally performed, in each node, on a ‘hop-by-hop’ basis using long lived routing tables, i.e. the node is sufficiently intelligent to determine an optimum route for the succeeding network connection.
Control information is regulated by a signalling scheme that is distinctive to the type of network employed. Particularly, public signalling systems are used between nodes of a public network and between public networks of different operators. Signalling System No. 7 is the only important example of a public signalling system. Access signalling systems are used between subscribers and edge nodes of public networks, e.g. between a radiotelephone and a base station subsystem (BSS). In fact, the most common digital access signalling schemes are Common Channel Signalling Systems, such as the Integrated Service Digital Network (ISDN) DSS
1
signalling schemes (and its predecessors) and Channel Associated Signalling schemes that are both derived from analog signalling. Private schemes are generally derived from access schemes but provide richer functionality within personal networks, such as within a secure private branch exchange (PBX).
On the other hand, broadband digital networks are characterised in that user and control information is transmitted in fixed or variable length “packets” or “cells”, with these packets prepended with headers that contain bearer channel identification. In contrast with narrowband systems, user information is relayed across a node via an asynchronous switching fabric that examines each packet in turn (using some kind of fairness algorithm) and directs it to the appropriate output link in response to the input link and bearer channel identification. Routing and control information transmission is, however, similar to that for the narrowband case, and differs only inasmuch as the signalling schemes are technology specific.
Another significant problem associated with prior art narrowband-broadband interfaces arises with architectural change. For example, the introduction of new or up-graded infrastructure can have unwanted ramifications throughout the entire communication system because changes in the inter-working relationships between the network controller (e.g. a call server) and the narrowband-broadband interface can potentially alter network identities and addresses. More particularly, the configuration of the narrowband-broadband interface may change (as a result of either the inclusion of additional equipment, the up-grading of existing equipment, or the failure of a particular system entity), while the call server remains oblivious to this change because of the uniform fabric application interface between the call server and the fabric control software. Consequently, the system (generally) may not necessarily be exploited and optimised to its greatest potential. Network providers may therefore also be discouraged from implementing the further development of existing networks since global system changes may be required, with such system changes being both time consuming and complex in nature.
To facilitate use of broadband networks and the migration of communication networks to high data rate technologies (e.g. the 2 Mbps rate envisaged within UMTS), there is a need to provide an effective mechanism for interconnecting narrowband networks through a transparent broadband ether, while also providing an easy migration to more advanced systems. Indeed, the broadband ether must accommodate and support narrowband signalling schemes Without affecting either data integrity or in any way inhibiting data flow or interconnection. Furthermore, to encourage subscription to broadband services, operators must provide a reliable but relatively low-cost (and hence optimised) communication system architecture.
Cable Julian Frank Barry
Evans Stephen Rhylant
Hayball Clive Colin
Jung Min
Lee Mann Smith McWilliams Sweeney & Ohlson
Nortel Networks Limited
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