Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Reexamination Certificate
1999-01-05
2003-09-16
Ngo, Ricky (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
C370S216000, C370S254000
Reexamination Certificate
active
06621831
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to transmission of signals, and, more particularly, to verifying and correcting error in transmission path of signals.
2. Description of the Related Art
The telecommunications sector is undergoing a major metamorphosis. The change has been induced by three primary factors. First is the growing number of users demanding more bandwidth for faster data transmission. Second is the congestion in the Plain Old Telephone Service (POTS), designed for transmission of voice signals in analog form. Third is the Telecommunications Reform Act, which is fostering broader competition through deregulation. All three of the aforementioned factors call for a more effective and efficient means for transporting data at high speeds.
To meet the demand for high-speed communication, designers are seeking innovative and cost-effective solutions that take advantage of the existing network infrastructure. Several technological advancements have been made in the telecommunications industry that make use of the existing network of telephone wires. The most promising of these technologies is the Digital Subscriber Line (DSL) technology.
DSL is making the existing network of telephone lines more robust and versatile. Once considered virtually unusable for broadband communications, an ordinary twisted pair equipped with DSL interfaces can transmit videos, television, and very high-speed data. The fact that more than six hundred million telephone lines exist around the world is a compelling reason that these lines will serve as the primary transmission conduits for at least several more decades. Because DSL utilizes telephone wiring already installed in virtually every home and business in the world, it has been embraced by many as one of the more promising and viable options.
There are now at least four popular versions of DSL technology, namely Asymmetrical Digital Subscriber Line (ADSL), Integrated Services Digital Network Digital Subscriber Line (IDSL), Very High-Speed Digital Subscriber Line (VDSL), and Symmetric Digital Subscriber Line (SDSL). Although each technology is generally directed at different types of users, they all share certain characteristics. For example, all four DSL systems utilize the existing, ubiquitous telephone wiring infrastructure, deliver greater bandwidth, and operate by employing special digital signal processing. The variations of DSL technologies are commonly referred to as xDSL technology. Because xDSL technology is well known in the art, they will not be described in detail herein.
DSL, as well as its later siblings, is making it possible for users to communicate over normal telephone wires at a much faster rate than before. The different flavors of DSL will converge around specific market niches and applications. For example, home users may favor ADSL for uses such as video-on-demand and Internet access. On the other hand, small businesses could find IDSL attractive for telecommuting and high-speed data transmission. Large businesses might choose VDSL to deliver Internet traffic or limited multimedia traffic to large businesses. DSL technologies leave Plain Old Telephone Service undisturbed. Traditional analog voice band interfaces use the same frequency band, 0-4 Kilohertz (KHz), as telephone service, thereby preventing concurrent voice and data use. A DSL interface, on the other hand, operates at frequencies above the voice channels, from around 30 KHz to 1.1 Megahertz (MHz). Thus, a single DSL line is capable of offering simultaneous channels for voice and data.
DSL systems use digital signal processing (DSP) to increase throughput and signal quality through common copper telephone wire. It provides a downstream data transfer rate Iraq from the DSL Point-of-Presence (POP) to the subscriber location at speeds of up to 8 Mega-bits per second (MBPS). The transfer rate of 1.5 MBPS, for instance, is fifty times faster than a conventional 28.8 kilobits per second (KBPS).
Although DSL and POTS systems can co-exist on one line (e.g., also referred to as “subscriber line”), the xDSL traffic is not passed through the POTS circuitry due to the different bandwidth, voltage, and power needs between the two systems. The xDSL signal is typically driven onto the subscriber line by a separate driver than is the POTS signal because the two signals are very different. The xDSL signal has a lower voltage, wider bandwidth, and often requires a different number of bits of resolution when digitized.
FIG. 1
illustrates a stylized block diagram of a communications system
100
that supports both xDSL and POTS technology. The communications system
100
depicts a typical xDSL and POTS installation between a Customer Premise (CP)
110
and Central Office (CO)
105
. A subscriber line
120
links the CO
105
to the CP
110
. The transmission of data signals over the subscriber line
120
from the CO
105
to CP
110
is typically referred to as a “downstream” transmission and the transmission of data signals from the CP
110
to CO
105
as an “upstream” transmission.
As can be seen in
FIG. 1
, both the CP
110
and CO
105
utilize splitters
125
,
130
to separate the different frequency bands that are transmitted over the subscriber line
120
. In the illustrated communications system
100
, the splitters
125
,
130
separate the voice band frequencies from the data band frequencies. Accordingly, splitters
125
,
130
comprise a voice filter
135
,
140
, which is typically a low-pass filter, and a data filter
145
,
150
, which is typically a high-pass filter. At the CO
105
, the voice filter
135
substantially removes the data band frequencies from the signal on the subscriber line
120
before providing a signal on a line
155
to a CODEC
160
. The data filter
145
at the CO
105
, conversely, substantially removes the voice band frequencies and provides a signal on a line
165
to an xDSL processor
170
. At the CP
110
, the voice filter
140
substantially removes the data band frequencies from the signal on the subscriber line
120
before providing a signal on a line
175
to either a telephone
180
or a modem
182
. The data filter
150
at the CP
110
, conversely, substantially removes the voice band frequencies and provides a signal on a line
185
to an XDSL processor
190
.
The communications system
100
of
FIG. 1
suffers from several shortcomings in that it does not allow for an easy means to verify the connectivity between the CO
105
and CP
110
, particularly with respect to the connectivity between the two xDSL processors
170
,
190
. Furthermore, the communications system
100
does not offer a quick and cost-efficient means for self-correcting the error, in case a connectivity error is detected. For example, one common connectivity error encountered is the incorrect installation of the splitters
125
,
130
, particularly the ones that are located at the CP
110
. Splitters
125
,
130
that are incorrectly installed (i.e. the connections to the data filter
145
,
150
and the voice filter
135
,
140
are reversed) prevent the voice/modem
180
/
182
and xDSL processor
170
,
190
from receiving the voice and data band frequencies, respectively.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
SUMMARY OF THE INVENTION
In one aspect of the present invention, a method is provided. The method includes providing an enable signal to a configuration device for generating a preselected signal, providing the preselected signal to a peer station over a subscriber line, and adjusting a transmission path of a signal to the peer station through the subscriber line in response to the preselected signal.
In one aspect of the present invention, an apparatus having a first and second terminal is provided. The apparatus includes a first switching device, a second switching device, and a configuration device. The first switching device includes an enable input terminal and an output terminal connected t
Legerity Inc.
Ngo Ricky
Williams Morgan & Amerson P.C.
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