Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1999-06-02
2001-06-12
Ton, Dang (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
Reexamination Certificate
active
06246699
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to communication networks and systems for transporting digital telecommunication signals, and is particularly directed to a new and improved cross-connect routing scheme for a distributed backplane architecture of a time division multiplex (TDM)-based telecommunication system equipment shelf, card installation slots of which may include different bandwidth telecommunication circuits, (DS0) time slots among which are stored in a relational database and assigned for transport by a supervisory control processor resident on a backplane controller card. This database is scanned onto a control bus in synchronous step with the TDM slots it administers, resulting in a simple hardware-based interconnection from their source and destination circuits.
BACKGROUND OF THE INVENTION
Digital network communication systems enable telecommunication service providers to supply multiple types of information channels from a sourcing site, such as a central office, to a network termination interface at a remote site serving a number of customer premises equipments (CPEs). A reduced complexity example of such a digital communication network architecture is diagrammatically illustrated in
FIG. 1
as comprising a TDM communication link (such as an optical fiber)
10
, through which a central office (CO)
20
at a ‘west’ end of the TDM link
10
transmits and receives digital telecommunication (e.g., T1 (1.544 Mb/s)) traffic with respect to customer premises equipments served by a remote termination site
30
at an ‘east’ end of the PCM link
10
. The central office
20
may include a central office switch
21
(such as a 5ESS switch manufactured by AT&T), that contains a plurality of line terminations
22
, each of which is coupled over digital facilities and distributed onto a local loop (twisted tip/ring pair) to a respective local DS0 customer site.
As shown in
FIG. 2
, to provide telecommunication service to remote customer equipments, the equipment shelf of a remote terminal
30
terminating the ‘east’ end of the PCM link
10
contains a network interface unit (NIU)
31
, that is coupled over an internal bus or backplane
32
to a plurality of circuit cards
33
installed in the interface unit's backplane
34
. Historically, each circuit card
33
was dedicated to providing telecommunication service for a particular piece of remote customer premises equipment, via a local loop
35
between the circuit
33
card and DS0 digital communication equipment
37
installed at a respective customer premises.
However, with improvements in integration circuit density and signal processing speed, digital telecommunication circuit manufacturers now offer a variety of multiple port devices having a wide range of operational bandwidth and digital subscriber line termination capabilities. Now although these enhanced bandwidth capability devices can transport a substantially increased amount of information, and/or enable a single card to service a relatively large number of terminating devices, their diverse configurations have required that transport connectivity among devices be effected by means of point-to-point communication links, which prevents their integration into an equipment shelf having a distributed backplane architecture.
SUMMARY OF THE INVENTION
In accordance with the present invention, this distributed bus integration problem is successfully remedied by a centralized cross-connect (DS0-time slot) routing scheme, that is executed by a supervisory control card of a time division multiplex (TDM)-based communication system equipment shelf having a distributed bus architecture, that allows any card slot of the backplane to interface any type of communication circuit card, irrespective of its bandwidth capability relative to the bandwidth capabilities of other circuit cards installed in the backplane.
By distributed routing is meant that all DS0 channels are assigned to TDM time slots by a common supervisory control processor, rather than being necessarily transported in the fixed order of the sequential card slot positions of the backplane. This means that any DS0 channel of any port of any card may be transported during any time slot. In a backplane architecture having multibit control, data and address links distributed among a plurality of card slots, one or more of the card slots contains a control card that supervises the operation of the equipment
1
shelf (including the DS0 channel routing scheme of the invention).
For purposes of providing a non-limiting example, the centralized communication channel—time slot routing scheme of the invention will be described for DS0 channels of an eight bit-wide telecommunication bus, having a transport bandwidth of 131.072 Mb/s (2048 time slots per 125 &mgr;sec extended superframe). Non-limiting examples of different bandwidth transceiver cards with which the invention may be used include basic DS-1 rate signaling cards, VT1.5 format cards, TU12 and VC12 format cards, AU-3 and STS-1 format cards and OC-3 format cards.
As will be described, the DS0-time slot routing scheme of the invention employs a relational database among the time slots of the backplane available for DS0 channel transport, each communication circuit card slot address, the port address of each communication circuit card, and the DS0 channels of each port. In particular, each of the available backplane time slots is assigned a DS0 channel for transport by means of an associated N bit wide addressable memory location of a time slot memory, which stores all information necessary to fully associate each time slot with a corresponding DS0 channel being serviced. This relational database is scanned onto a distributed control bus in time synchronization with the distributed TDM bs.
A first portion of a time slot-assigning word stored in a respective time slot memory location contains the identification of the card slot, in which the digital communication card that transmits/receives a respective DS0 byte during its associated time slot is installed. A second portion of the data word contains the identification of the particular port of that communication card, through which the associated DS0 channel is interfaced for the time slot. A third portion of the data word contains the identification of the DS0 byte. To automatically rout the time slots for data transport, the backplane's communication controller card simply scans the time slot memory (relational database). As data is read out of the successive memory locations, DS0 channels are automatically associated with the successive time slots. Since DS0 channels are not necessarily assigned in the order of sequential card slot position, any DS0 channel may be transported during any time slot.
REFERENCES:
patent: 4679191 (1987-07-01), Nelson et al.
patent: 5490252 (1996-02-01), Macera et al.
O'Shea Thomas E.
Wartski Mark C.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Pliant Systems, Inc.
Ton Dang
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