Multiplex communications – Diagnostic testing – Path check
Reexamination Certificate
1998-03-28
2001-10-02
Vincent, David R. (Department: 2661)
Multiplex communications
Diagnostic testing
Path check
C370S244000, C370S254000, C370S395430, C370S230000
Reexamination Certificate
active
06298043
ABSTRACT:
RELATED PATENT APPLICATIONS
The present application is related to: i) co-pending U.S. patent application Ser. No. 08/907,521 [Applicant's reference FPUS97518/ID0722] filed on Aug. 8, 1997 in the name of J. F. B. Cable et al. and assigned to Northern Telecom Limited, which co-pending U.S. patent application is further identified by its title “SYSTEM AND METHOD FOR ESTABLISHING A COMMUNICATION CONNECTIONS”; and ii) co-pending UK patent application number 9720920.9 [Applicant's reference PUK97674/ID0835] filed on Oct. 1, 1997 in the name Northern Telecom Limited, which co-pending UK patent application is further identified by its title “COMMUNICATION SYSTEM ARCHITECTURE AND OPERATING METHODS THEREOF” and the first named inventor R. H. Mauger.
BACKGROUND TO THE INVENTION
This invention relates, in general, to a communication system architecture and a connection verification mechanism therefore, and is particularly, but not exclusively, applicable to a network and mechanism that can confirm that connections have been established and are maintained correctly end-to-end across the network for the duration of a call. The invention has application in combination networks that integrate narrowband call structures with broadband functionality, although the invention is equally applicable to isolated narrowband or isolated broadband system.
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, multimedia digital networks (such as the Universal Mobile Telecommunication System (UMTS)) having broadband capabilities. Indeed, radio frequency (RF) and wireline systems are being merged together to enhance the information transfer mechanism, while still providing some flexibility with respect to mobility within the network. For example, broadband (typically fiber-optic based) infrastructure connections are being utilised to support information (both voice and data) transfer between cellular RF coverage areas. The transition to broadband systems is, in fact, necessarily required to support higher data rate communications, including video and Internet applications that are presently being both considered and made available to subscribers to the service. 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 freestanding 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 reimplemented 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. More especially, the sixty-four kbps bearer channels, typically encoded with a pulse code modulation, are communicated between the base station sub-system (BSS) and the mobile service switching center (MSC) over an E
1
link. Indeed, each bearer channel can be framed to support four voice calls of sixteen kbps comprised from thirteen kbps of sampled and encoded speech and three kbps 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, although other fabric arrangements are equally applicable. 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 of the succeeding 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) DSS1 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 nar
Brueckheimer Simon Daniel
Cable Julian Frank Barry
Mauger Roy Harold
Lee, Mann, Smith McWilliams, Sweeney and Ohlson
Nortel Networks Limited
Vincent David R.
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