Telephonic communications – Subscriber line or transmission line interface
Reexamination Certificate
1998-04-01
2001-08-07
Hudspeth, David (Department: 2641)
Telephonic communications
Subscriber line or transmission line interface
C370S493000, C370S535000
Reexamination Certificate
active
06272219
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to telecommunications, and more particularly to access network with an integrated splifter.
Telephone customers are moving in an evolutionary way to higher bandwidths, from sharing POTS (Plain Old Telephone Service) and modem on one line to dedicated analog modem line at 33.6 kbps, to dedicated analog modem line at 56 kbps, and then to ISDN BA (Basic Access). Now, ADSL (asymmetrical digital subscriber line) has been introduced, and the ADSL modems have become proven technology. ADSL refers to the two way capability of a twisted copper pair with analog to digital conversion at the subscriber end and an advanced transmission technology. Ordinary twisted pair equipped with ADSL modems can transmit movies, television, dense graphics, and very high speed data. For all its capacity, ADSL leaves POTS (Plain Old Telephone Service) undisturbed. A single ADSL line therefore offers simultaneous channels for personal computers, televisions, and telephones. With ADSL, telephone companies can connect almost every home and business to exciting new interactive broadband services. The recent announcement of the Universal ADSL has accelerated the interest in the UADSL technology and will speed up of introducing UADSL in large volume.
The ISDN and ADSL services are different. ISDN provides two voice channels or a 128 kbps data channel while ADSL is predominantly a data pipe providing an asymmetrical bandwidth of up to 9 Mbps downstream and 800 kbps upstream. An ADSL access network will be an overlay network and therefore not require the expensive and time-consuming switch upgrades that held ISDN back for so long.
The customers for ADSL most likely already have a dedicated modem line or ISDN. A large proportion of the future customers will be connected to pair gain systems in the US or to ISDN in Europe.
FIG. 1
shows a standard ADSL configuration. At a telephone company location
100
, a central office terminal (COT)
2
, such as a line card, provides an analog telephone line POTS. An ADSL modem
4
, which receives broadband data from the Internet, for example, provides ADSL. Both the POTS and ADSL are connected to a splifter
6
, which provides both the POTS and ADSL services to a customer premise
200
. A splitter
8
receives the POTS and ADSL signals and separates them. The ADSL provided from splitter
8
is connected to an ADSL modem
10
, which is connected to either ATM
25
(asynchronous transfer mode 25 Mbps) or Ethernet. Splitters
6
and
8
are bidirectional. In other words, splitter
8
also integrates the POTS and ADSL into a single pair of lines. The single pair of lines is connected to splitter
6
, which separates it to POTS and ADSL lines and provides them to COT
2
and ADSL modem
4
, respectively. In this configuration, two splitters
6
and
8
are needed, one at telephone company location
100
and the other at customer premise
200
.
FIG. 2
shows a configuration of UADSL, i.e., splitterless ADSL. In this configuration, no splitter is required at customer premise
200
. A UADSL modem
14
is connected in parallel with an analog telephone equipment
12
. UADSL modem
14
will work simultaneously with telephone equipment
12
, i.e. also during ringing, dial pulsing, etc. The bit rate of UADSL modem
14
will be significantly lower compared to full-rate ADSL, but there will still be an improvement of 20-25 times over the actually achievable bit rates with analog modems.
FIG. 3A
shows a configuration of ADSL over a pair gain system. In this configuration, at telephone company location
100
, COT
2
provides two pairs of POTS lines to a pair gain line card (LC) system
16
, which converts the two pairs into one DSL (Digital Subscriber Line). The DSL and ADSL supplied from ADSL modem
4
are connected to splitter
18
, which provides DSL and ADSL services to customer premise
200
on a single pair of lines. At customer premise
200
, splitter
20
separates the DSL from the ADSL. The DSL is provided to a pair gain remote terminal (RT)
22
, which provides two analog POTS lines. The ADSL is provided to ADSL modem
24
, which is connected to either ATM
25
or Ethernet. Because of the difference in frequency use, remote power feeding, etc., there will always be a need for splitter
20
at customer premise
200
side with pair gain systems even with UADSL transmission. In the case of providing ADSL over ISDN BA (basic access), pair gain remote terminal
22
can also be an ISDN NT
1
(network termination
1
).
FIG. 3B
shows a standard remote terminal
22
. Connectors
1
,
2
and DSL are connected to POTS
1
, POTS
2
, and DSL lines, respectively.
In the conventional configurations, such as shown in
FIGS. 1 and 3A
, an external splitter is required at customer premise
200
. The external splitter is usually located in a sealed box. However, an external splitter at the customer premise means an extra box at or in the house. Furthermore, using an external splitter as a separate device involves a number of operational and administrative issues, such as ordering, provisioning, maintenance, customer service, billing, testing, etc. Thus, when a customer orders ADSL service, all these issues need to be resolved. This presents significant operational and administrative costs to Telecom operators.
Therefore, there is need for an integrated remote terminal that reduces the operational and administrative costs associated with providing ADSL services to customers.
SUMMARY OF THE INVENTION
The present invention provides an effective way for Telecom operators to provide ADSL service to customers who are receiving POTS service over a pair gain system or who are connected to ISDN.
According to one embodiment of the invention, an ADSL/DSL (Very High Speed DSL) splitter is integrated in the remote terminal of a pair gain system or in the NT
1
(Network Termination
1
) of an ISDN BA (Basic Access). Therefore, no extra box on the house and no extra truck roll is required when the customer orders ADSL service. Integrating the splitter makes the telephone line upwards compatible with UADSL since UADSL can be directly connected to an analog telephone line.
According to another embodiment of the invention, both the splitter and ADSUUADSL modems are integrated in the remote terminal of a pair gain system or in the NT
1
of an ISDN BA. The splifter in the telephone company location may also be integrated in the central office terminal (COT) of the pair gain system.
According to a further embodiment of the invention, the UADSL signal output of an ADSL splitter in the remote terminal of a pair gain system is connected to an analog POTS port, with appropriate filtering. According to this embodiment, the UADSL signal is connected to all POTS lines coming out of a remote terminal. Connecting the UADSL output of the splitter to the POTS output eliminates the need for additional wiring in the customers house.
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T. Kessler et al., “Simulation of ADSL Over ISDN on German Subscriber Line”,IEEE Communications Letters, vol. 1, No. 5, Sep. 1, 1997, pp. 124-126.
Aware Inc., “Splitterless DMT System Design and Measurements”, ITU-T Telecommunication Standardization Sector of ITU, Oct. 29, 1997, entire document.
G. T. Hawley, “System considerations for the use of xDSL technology for data access”, IEEE Communications Magazine, vol. 35, No. 3, Mar. 1997, pp. 56 to 60.*
K. Sistanizadeh, “spectral compatibility of asymmetrical digital subscriber lines (ADSL) with basic rate DSLs, HDSLs, and T1 lines,” Global Telecommunications Conference, 1991, vol. 3, Dec. 1991, pp. 1969 to 1973.
De Bruycker Erwin
Erreygers Jan
Hudspeth David
Lerner Martin
Terayon Communications Systems, Inc.
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