Telecommunication equipment support of ISDN communication...

Details Telecommunication equipment support of ISDN communication... Telecommunication equipment support of ISDN communication...

1999-02-25

2003-02-11

Vanderpuye, Ken (Department: 2732)

Multiplex communications

Pathfinding or routing

Through a circuit switch

C370S420000, C370S463000

Reexamination Certificate

active

06519253

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to telecommunication line termination equipment and in particular to Integrated Services Digital Network (ISDN) line termination equipment.
There is an ever pressing need to provide consumers of telecommunication services with high speed data services. Many subscribers use plain old telephone services (POTS) lines to carry data communication signals between computer devices employing modems to communicate via the public switched telephonic network. Unfortunately, the maximum data rate using modems of a POTS subscriber line is limited by many factors including the sampling rate, bandwidth, and the analog to digital signal conversion rate for the line cards which terminate the POTS lines.
Other subscriber lines are available, however, which provide higher data rates. Integrated Services Digital Network (ISDN) lines provide a subscriber with telephone services generally at a higher data rate than conventional POTS lines. Subscribers utilize an ISDN line to carry digital signals controlled by a personal computer to another ISDN set, modem or ISDN modem pool via the public switched telephone network. It will be appreciated that the maximum data rate which can be transmitted using modems over an ISDN subscriber line is limited to 144 kilobits per second.
Subscribers can lease special lines from their telephone providers which accommodate higher data rates than are supported by conventional dial-up subscriber lines or by ISDN lines. Recently, Asymmetric Digital Subscriber Line (ADSL) technology has evolved which provide even higher data transmission speeds than ISDN technology. The known ADSL technique which is supported by available equipment provides a significantly higher data rate to a subscriber over a conventional copper two-wire subscriber line. Proper terminating equipment at the consumer location and the telephone service provider central office is required to employ ADSL technology.
Referring now to
FIG. 1
, currently available services for subscribers using conventional two wire copper loops are illustrated. Equipment to the right of dashed line
10
represents customer premises equipment (CPE); equipment to the left of line
10
represents central office line termination equipment. The ISDN line interface
12
also known as a line card, provides an interface between digital incoming and outgoing communication lines
14
and
16
, and analog signals carried on subscriber line
18
. For example, lines
14
and
16
may carry 2-64 kilobits per second (kbps) and 1-16 kbps signals representative of information received from and transmitted to line
18
. A main distribution frame (MDF)
20
is used to interconnect a plurality of incoming subscriber lines to various terminating equipment at the central office. In this example, line
18
is connected through an ISDN splitter
19
and MDF
20
to subscriber line
22
. A conventional ISDN station set or instrument
24
at the consumer's premises is connected through ISDN splitter
23
to subscriber line
22
.
FIG. 1
also illustrates another service to the subscriber which provides a high speed data capability. An ADSL interface circuit
26
provides an interface between the central office and the subscriber for transmitting and receiving data at rates up to several Megabits per second. Lines
28
and
30
provide inbound and outgoing digital data communications representative of information to and from the subscriber carried on line
32
. Line
32
is connected via ISDN splitter
19
and MDF
20
to subscriber line
22
. An ADSL interface
36
provides an interface between conventional digital data communicated with a user's personal computer
38
and ADSL analog format signaling communicated on line
37
. The ISDN splitter
23
couples the ADSL signal between ADSL interface
36
and subscriber line
22
. The advantage to the user is that the ADSL facilities support a substantially higher data rate than would be available if the subscriber utilized communications terminated via the ISDN line interface
12
.
A disadvantage illustrated in
FIG. 1
is that ISDN splitters
19
and
23
are required. These known ISDN splitters function to separate the higher frequency signals associated with ADSL signaling from the lower frequency signals (typically <80-110 kilohertz) associated with the conventional ISDN communications. The conventional ISDN splitter consist of a lattice of inductors and capacitors that provides the needed filtering while maintaining the ISDN signals. The components (inductors and capacitors) used in the ISDN splitter occupy a relatively large volume. Thus, a conventional ISDN splitter occupies a significant amount of space.
Unfortunately, conventional ISDN termination equipment is complex (especially in wiring devices) and is not highly integrated when employing ADSL technology. Moreover, bulky splitters are required taking up a significant amount of space in the terminating equipment cabinets. The size of the splitters and the wiring associated with connecting them to the MDF, ADSL interface and the ISDN line interface take up precious space which is limited. The problem is magnified as more and additional subscribers request services. Accordingly, there is a need to provide highly integrated equipment enabling high speed ADSL technology services on ISDN lines while minimizing space and wiring requirements.
SUMMARY OF INVENTION
It is an object of the present invention to address the above referenced need by providing a solution which minimizes the space and wiring associated with the central office terminating equipment for high speed data services.
In accordance with one embodiment of the present invention, access interface units terminate subscriber lines by which the corresponding subscribers can utilize ISDN services and/or high speed data services such as ADSL. The access interface units support both types of service without utilizing a conventional ISDN splitter. The access interface units include a line support circuit wherein two way communications on the subscriber loop are separated into inbound and outbound communications on separate channels. The inbound communications are split into first and second signals. The first signal is low pass filtered and converted into digital format signals by a conventional ISDN receiver. The second signal is high pass filtered and converted into digital format signals by a high speed data receiver. The outbound communication is the summation of third and fourth analog signals from an ISDN transmitter and high speed data transmitter. An important aspect of this invention resides in the ability to use conventional low voltage, low current passive and active components for the low pass and high pass filters.


REFERENCES:
patent: 5781728 (1998-07-01), Rybicki et al.
patent: 6144659 (2000-11-01), Nye et al.
patent: 6236164 (2001-05-01), Erreygers

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