The present invention relates in general to telecommunication networks, and is particularly directed to a multi-mode backplane architecture, that is configured to support both multiplexed communication circuits and non-multiplexed (loop repeater) circuits in the same equipment shelf, and thereby provide either or both types of telecommunication connectivity between the network and subscriber circuits served by the network.
Prior to the advent of multiplexedxe2x80x94digital communications, telephony service providers provided telecommunication connectivity to their subscribers by way of dedicated, point-to-point analog copper wire loops, extending from line cards installed in an equipment bank of a service, facility, such as a central office to telephone equipment installed at a customer site. With continuing improvements in digital communication equipment and transport protocols, these conventional point-to-point loops have been augmented by time division multiplexed (TDM) digital circuits, that are capable of transporting a wide variety of communication signals (audio/voice, video and data) to multiple customer premise equipments.
Because multiplexed digital circuits require a backplane architecture different than that employed for legacy loop circuit line card equipment racks, telecommunication service providers currently employ two respectively different types of line card equipment shelvesxe2x80x94one for legacy loop circuits; the other for multiplexed circuits. Now even though it is anticipated that the number of multiplexed equipment installations will continue to grow, and may eventually become the predominant mode of network communication circuit, it is still necessary that each telecommunication equipment installation have the capability of providing service for both types of circuits. This means that each line circuit installation facility must be equipped with both multiplexed and loop repeater mode backplane shelves, irrespective of the degree to which each is populated, which increases both the complexity and cost of the installation.
In accordance with the present invention, the above problem is effectively obviated by a new and improved multi-mode backplane architecture, that is configured to simultaneously support and provide telecommunication connectivity for both multiplexed communication circuits and non-multiplexed (loop repeater) circuits in the same equipment shelf, so that both signalling modes are available in the same equipment shelf between the network and subscriber circuits connected to the backplane. For this purpose, the backplane architecture of the present invention comprises a set of redundant (for improved reliability) network interface multiplexers, each of which provides both time division multiplexing and point-to-point multiplexing connectivity between the network and line access modules to which subscriber circuits served by the network are selectively ported.
On the network side, each redundant network interface multiplexer is ported to a pair of high speed multiplexed network communication links that transport standard high speed multiplexed digital telecommunication signals, such as but not limited to DSX, STS-1, OC-X signals. On the line circuit side, each network interface multiplexer is coupled to a time division multiplexed communication bus, along which a plurality of line access module card slots are distributed, and to a plurality of point-to-point communication links, that are ported to respective ones of the line access module card slots.
Each network interface multiplexer contains a data buffer that is ported between each of the pair of high speed multiplexed network communication links and a signal path routing control processor. The routing control processor is coupled to a data matrix, that is ported to respective ones of the line access modules, and a time division multiplexed port, that is coupled to the time division multiplexed communication bus. The signal path routing control processor and the data matrix are controlled by a multiplexer control digital signal processor. Once provisioned by the system controller unit, the multiplexer control processor is operative to control the execution of the intended multiplexed telecommunication signalling functionality between the high speed multiplexed network communication links and the line access modules.
Each access module card slot is configured to receive a line circuit access module that is programmably configurable to provide a selected mode (multiplexed mode or loop repeater mode) of telecommunication connectivity between the network and a subscriber circuit served by the network. For external loop mode connectivity, a plurality of point-to-point communication links are respectively ported between external loop ports of the access module card slots and associated loop ports of a plurality of non-multiplexed interface connectors. Each non-multiplexed interface connector is configured for connection to non-multiplexed communication links of the network and non-multiplexed communication links (e.g., two-wire loops) of subscriber circuits served by the network.
A system controller unit, such as a desktop computer terminal, is coupled to each of the redundant network multiplexers and the line circuit access modules for allowing network service personnel to program backplane connectivity configuration parameters into the redundant network multiplexers and the line circuit access modules, and thereby enable any line access module to provide either multiplexed or loop repeater mode telecommunication connectivity between the network and subscriber circuit to which that line access module is ported.
In order to provide a selected mode of telecommunication connectivity, such as but not limited to ISDN, HDSL, ADSL, T1 office repeater, fractional T1, optical DS2, DSX-1, DDS, DAML, DAML POTS, etc., between the network and a subscriber circuit served by the network, a respective line circuit signal access module contains a processor controlled input/output multiplexer arrangement, that is buffered between each network interface multiplexer and respective sets of non-multiplexed communication links that are ported to the non-multiplexed interface connectors.
For this purpose, a multiplexed signal input buffer has a set of inputs ported to the TDM bus and point-to-point links from the network interface multiplexers, and a set of outputs ported to multiplexed inputs of an input multiplexer portion of the input/output multiplexer arrangement. On the non-multiplexed signalling side, a non-multiplexed signal input buffer has a set of non-multiplexed signal-associated inputs ported to point-to-point loops of the non-multiplexed interface connectors. On its output side, the non-multiplexed signal input buffer has a set of outputs ported to associated input ports of the input multiplexer portion of the input/output multiplexer arrangement. The input multiplexer has a plurality of outputs associated with respective ones of its multiplexed and non-multiplexed inputs coupled to corresponding inputs of a protocol conversion, network/subscriber circuit connectivity-defining, signal processing circuit.
The signal processing circuit is preferably implemented as a digital signal processor that is programmably configurable by the system controller unit to execute protocol conversion functionality for effecting one of loop repeater and time division multiplex connectivity between selected ones of its input and output ports, so as to provide a selected mode and type of telecommunication connectivity, such as those referenced above. The signal processing circuit has a plurality of output ports coupled to corresponding inputs of an output multiplexer portion of the input/output multiplexer.
On the multiplexed signal side, the line access module""s output multiplexer has TDM output bus ports respectively coupled to TDM bus ports, and point-to-point output bus ports respectively coupled to associated inputs of the multiplexed signal input buffer. Likewise, on the non-multiplexed signal side, the output multiplexer has a set of non-multiplexed output ports coupled to respective non-multiplexed signal-associated input ports of the non-multiplexed signal input buffer. The mode of connectivity through and operation of the line access module""s input/output multiplexer arrangement and its protocol conversion, network/subscriber circuit connectivity-defining, signal processing circuit is controlled by an access module control processor that is coupled to the backplane""s system controller unit. Since each line access module is selectively connectable to and individually programmable for providing connectivity and protocol conversion for either multiplexed or loop mode signalling paths of both network and subscriber connections, the backplane enjoys complete flexibility in terms of types of circuit and mode of operation that may be emulated by each line access module.