Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1998-09-23
2001-08-28
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S352000, C370S467000
Reexamination Certificate
active
06282194
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of telecommunications networks, and in particular, a transit trunk subnetwork which is established between existing narrowband switches to expand bearer traffic capacity.
BACKGROUND OF THE INVENTION
There are a number of significant challenges facing public carriers in telecommunications markets, including a rapidly growing demand for Internet data access over the public switched telephone network (PSTN). The demand for Internet access has been so great that there has been a considerable increase in call holding times on calls to Internet service providers and delays in making connections to the PSTN. In addition, even when connections are made to the Internet, the bandwidth demand imposed by the increasing number of users has strained conventional narrowband network systems and has deteriorated existing service on the PSTN, particularly in North America.
Deregulation and growth in the use of wireless systems, particularly cellular telephones and portable data communications devices, has also strained existing network systems and has created a demand for trunking growth. As more users connect into analog and digital cellular systems, telecommunications carriers will have to expand existing network switching systems and increase trunking capacity between switching systems.
A problem with existing networks is that the interexchange trunks in those networks serve as traffic capacity choke points in the system. That is, the trunks limit the amount of traffic that can be passed between access tandems in the PSTN. In order to handle a large call volume, or the increased call volume due to the sudden growth of the usage of the network for data services, the trunks need to be provisioned with a capacity to handle high call volumes. If the trunk capacity of the access tandems is exceeded, then access tandems also have to be added to the network. Not only is the provisioning of access tandems and interexchange trunking very expensive, such facilities are generally not adapted to support other services during off-peak hours.
The above-mentioned problems typically cause switch port capacity exhaustion in the tandem layer of a voice network. This problem has been addressed by deploying solutions to redirect the traffic to a data network at an access interface or an end office. One such solution is proposed in U.S. Pat. No. 5,483,527 to Doshi et al., issued Jan. 9, 1996. One of the principles behind this patent is to accumulate voice signals from synchronous transfer mode switches (STMs) and form asynchronous transfer mode (ATM) cells from the signals. After a pre-determined number of signals are received, the cell is transferred over an ATM switching system, and the data is converted back to synchronous transfer mode voice signals.
A drawback of the Doshi et al. system is that it essentially imposes a synchronous transfer mode architecture on the ATM network. Telephone calls are transferred through the ATM network using permanent virtual circuits and each of the asynchronous transfer mode switches in the network is provided with a signal processor and call processor that receive common channel signaling messages and transfer those messages on to a next switch in the ATM call path or the destination switch in the telephone network, as appropriate. Since every single ATM switch requires those signal and call processors, this configuration is expensive to implement. It also leads to an inefficient usage of available bandwidth on the network. Therefore, a need exists in the telecommunications markets for a system which can improve bearer traffic capacity using ATM facilities, while permitting efficient usage of available bandwidth on the ATM network. A need also exists for a system which can increase bearer traffic capacity using an ATM network control system that readily integrates with various types of TDM switches that exist in the PSTN network. An additional need exists for a subnetwork which can absorb additional growth in call volumes so as to prevent the need for provisioning trunks with a capacity to handle high call volumes. A further need exists for a subnetwork which eliminates the requirement to provision high capacity trunking connection in existing synchronous transfer mode (STM) networks.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system that permits narrowband traffic to be directed through asynchronous transfer mode (ATM) networks.
It is another object of the present invention to provide a transit trunk subnetwork which establishes a virtual network of signaling trunks between existing narrowband switches using ATM facilities to efficiently expand the traffic capacity of existing narrowband switches.
It is another object of the present invention to provide a transit trunk subnetwork which can be linked together with other transit trunk subnetworks to provide interconnected virtual networks of trunks between existing narrowband switches to multiply the traffic capacity of existing narrowband switches.
It is a further object of the present invention to provide a transit trunk subnetwork which interconnects end offices of telecommunications carriers such that the transit trunk subnetwork functions as a virtual access tandem interconnecting end office.
According to a first broad aspect, the invention provides a transit trunk subnetwork for interconnecting a first synchronous transfer mode (STM) access switching system to a plurality of other synchronous transfer mode switching systems. The transit trunk subnetwork includes an asynchronous transfer mode (ATM) network connected by a first communications trunk to a first STM switching system and by second communications trunks to other STM switching systems. The transit trunk subnetwork also includes interfaces respectively connecting the first and second trunks with the ATM network, and converts STM data to ATM cells and ATM cells back to STM data. The transit trunk subnetwork further includes a signal controller for interpreting common channel signaling messages and for mapping the movement of the signaling messages between the first and second STM switching systems, as well as a management system for managing bandwidth demand at the interfaces. The signal controller and management system are independent of the STM switching systems and the ATM switching systems, though they are nodes in the ATM network and have ATM addresses.
According to a second broad aspect, the invention provides a transit trunk subnetwork for enhancing the bearer traffic capacity of an existing network. The transit trunk subnetwork includes an ATM network, interfaces connected between exchange carriers and the ATM network, and between access tandem switching systems and the ATM network. The transit trunk subnetwork further includes a signal controller and management system, where the signal controller and management system are independent of the exchange carriers and the access tandem switching systems.
In accordance with a third broad aspect, the invention provides a networked system which includes two or more transit trunk subnetworks, the networked system being utilized for interconnecting a first STM switching system to a plurality of other STM switching systems. Each of the transit trunk subnetworks include an ATM network connected by a first communications trunk to a first STM switching system and by second communications trunks to other STM switching systems. The network system also includes interfaces connecting the first and second communications trunks with the STM switching systems, as well as a signal controller for interpreting signaling messages and for mapping the movement of signaling messages between the first and second trunks. A management system manages bandwidth demand at the interfaces with the ATM network. Each of the subnetworks are interconnected via ATM switches within the ATM network.
In accordance with a fourth broad aspect, the invention provides a virtual tandem switch comprising a transit trunk subnetwork for interconnecting end offic
Cheesman Julian Francis
Constantinof Cristian
Holmes Kim Brian
Kahnert Michael C.
Alston & Bird LLP
Nortel Networks Limited
Olms Douglas
Vanderpuye Ken
LandOfFree
Transit trunk subnetwork system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Transit trunk subnetwork system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transit trunk subnetwork system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2534594