Note: Descriptions are shown in the official language in which they were submitted.
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Network for telephony and data communication
This application is a Divisional of Application Ser. No. 2,362,781 filed in
Canada
on March 2, 2000.
FIELD OF THE INVENTION
The present invention relates to the field of wired communication
systems, and. more specifically. to the networking of devices using
telephone lines.
BACKGROUND OF THE INVENTION
Figure 1 shows the wiring configuration for a prior-art telephone
system 10 for a residence or other building, wired with a telephone line 5.
Residence telephone line 5 consists of single wire pair which connects to a
junction-box 16, which in turn connects to a Public Switched Telephone
Network (PSTN) 18 via a cable 17. terminating in a public switch 19.
apparatus which establishes and enables telephony from one telephone to
another. The term "analog telephony" herein denotes traditional analog
low-frequency audio voice signals typically tinder 3KHz. sometimes
referred to as "POTS" ("plain old telephone service"), whereas the term
"telephony" in general denotes any kind of telephone service. including
digital service such as Integrated Services Digital Network (ISDN). The
term "high-frequency" herein denotes any frequency substantially above
such analog telephony audio frequencies. such as that used for data. ISDN
typically uses frequencies not exceeding 100KHz (typically the energy is
concentrated around 40KHz). The term "telephone device" herein denotes,
without limitation, any apparatus for telephony (including both analog
telephony and ISDN), as well as any device using telephony signals, such
as fax, voice-modem, and so forth.
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Junction box 16 is used to separate the in-home circuitry from the
PSTN and is used as a test facility for troubleshooting as well as for wiring
new telephone outlets in the home. A plurality of telephones 13a. 13b. and
Be connects to telephone line 5 via a plurality of outlets 11a. lib. I ic, and
11d. Each outlet has a connector (often referred to as a `,jack"). denoted in
Figure 1 as 12a, 12b. 12c. and 12d. respectively. Each outlet may be
connected to a telephone via a connector (often referred to as a "plug"),
denoted in Figure 1 (for the three telephone illustrated) as 14a. 14b. and
t4e. respectively. It is also important to note that lines 5a. 5b, Sc. 5d. and
5e are electrically the same paired conductors.
There is a requirement for using the existing telephone infrastructure
for both telephone and data networking. This would simplify the task of
establishing a new local area-network in a home or other building. because
there would be no additional wires and outlets to install. U.S. Patent
4.766.402 to Crane (hereinafter referred to as "L rane'") teaches a way to
form a LAN over two wire telephone lines. but without the telephone
service.
The concept of frequency domain / division multiplexing (FDM) is
well-known in the art, and provides a means of splitting the bandwidth
carried by a wire into a low-frequency band capable of carrying an analog
telephony signal and a high-frequency band capable of carrying data
communication or other signals. Such a mechanism is described for
example in U.S. Patent 4.785,448 to Reichert et at (hereinafter referred to as
"Reichert"). Also is widely used are xDSL systems. primarily Asymmetric
Digital Subscriber Loop (ADSL) systems.
Relevant prior art in this field is also disclosed in U.S. Patent
5,896.443 to Dichter (hereinafter referred to as "Dichter"). Dichter is the
first to suggest a method and apparatus for applying such a technique for
residence telephone wiring. enabling simultaneously carrying telephone and
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data communication signals. The Dichter network is illustrated in Figure 2,
which shows a network 20 serving both telephones and a local area
network. Data Terminal Equipment (DTE) units 24a, 24b and 24c are
connected to the local area network via Data Communication Equipment
(DCE) units 23a, 23b and 23c. respectively. Examples of Data
Communication Equipment include modems. line drivers, line receivers,
and transceivers. DCE units 23a. 23b and 23c are respectively connected to
high pass filters (HPF) 22a, 22b and 22c. The i-IPF's allow the DCE units
access to the high-frequency band carried by telephone line 5. In a first
embodiment (not shown in Figure 2). telephones 13a. 13b and 13c are
directly connected to telephone line 5 via connectors 14a. 14b and 14c.
respectively. However. in order to avoid interference to the data network
caused by the telephones, a second embodiment is suggested (shown in
Figure 2). wherein low pass filters (LPF's) 21a. 21b and 21c are added to
isolate telephones 13a, 13b and 13c from telephone line 5. Furthermore, a
low pass filter must also be connected to Junction-Box 16. in order to filter
noises induced from or to the PSTN wiring 17. As is the case in Figure 1, it
is important to note that lines 5a. 5b. 5c. 5d and Se are electrically the
same
paired conductors.
The Dichter network suffers from degraded data communication
performance, because of the following drawbacks:
1. Induced noise in the band used by the data communication
network is distributed throughout the network. The telephone line
within a building 'serves as a long antenna, receiving electro-
magnetic noise produced from outside the building or by local
equipment such as air-conditioning systems, appliances, and so
forth. Electrical noise in the frequency band used by the data
communication network can be induced in the extremities of the
telephone line 5 (line 5e or 5a in Figure 2) and propagated via the
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telephone line 5 throughout the whole system. This is liable to
cause errors in the data transportation.
2. The wiring media consists of a single long wire (telephone line
5). In order to ensure a proper impedance match to this
transmission-line. it is necessary to install terminators at each end
of the telephone line 5.- One of the advantages of using the
telephone infrastructure for a data network. however. is to avoid
replacing the internal wiring. Thus. either such terminators must
be installed at additional cost. or suffer the performance problems
associated with an impedance mismatch.
3. In the case where LPF 21 is not fitted to the telephones 13. each
connected telephone appears as a non-terminated stub. and this is
liable to cause undesirable signal reflections.
4. In one embodiment an LPF 21 is to be attached to each
telephone 13. In such a configuration. an additional modification
to the telephone itself is required. This further makes the
implementation of such system complex and costly, and defeats
the purpose of using an existing telephone line and telephone sets
.as is' for a data network.
5. The data communication network used in the Dichter network
supports only the 'bus` type of data communication network,
wherein all devices share the sane physical media. Such
topology suffers from a number of drawbacks. as described in
U.S. Patent 5.841.360 to the present inventor, which is
incorporated by reference for all purposes as if fully set forth
herein. Dichter also discloses drawbacks of the bus topology,
including the need for bus mastering and logic to contend with
the data packet collision problem. Topologies that are preferable
to the bus topology include the Token-Ring (IEEE 803). the PSIC
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network according to U.S. Patent 5.841.360, and other
point-to-point networks known in the art (such as a serial
point-to-point 'daisy chain' network). Such networks are in most
cases superior to 'bus' topology systems.
The above drawbacks affect the data communication performance of
the Dichter network. and therefore limit the total distance and the maximum
data rate such a network can support. In addition. the Dichter network
typically requires a complex and therefore costly transceiver to support the
data communication system. While the Reichert network relies on a star
topology and does not suffer from these drawbacks of the bus topology. the
star topology also has disadvantages. First, the star topology requires a
complex and costly hub module, whose capacity limits the capacity of the
network. Furthermore. the star configuration requires that there exist wiring
from every device on the network to a central location, where the hub
module is situated. This may be impractical and/or expensive to achieve,
especially in the case where the wiring of an existing telephone system is to
be utilized. The Reichert network is intended for use only in offices where a
central telephone connection point already exists. Moreover, the Reichert
network requires a separate telephone line for each separate telephone
device, and this. too. may be impractical and/or expensive to achieve.
There is thus a widely-recognized need for. and it would be highly
advantageous to have, a means for implementing a data communication
network using existing telephone lines of arbitrary topology, which
continues to support analog telephony while also allowing for improved
communication characteristics by supporting a point-to-point topology
network.
.. ....... ... .
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SUMMA.R.Y OF THE INVENTION
The present invention provides a method and apparatus for using the
telephone line wiring system within residence or other building for both
analog telephony service and a local area data network featuring a serial
"daisy chained'' or other arbitrary topology. First. the regular outlets are
modified or substituted to allow splitting of the telephone line having two
wires into segments such that each segment connecting two outlets is fully
separated from all other segments. Each segment has two ends. to which
various devices. other segments. and so forth. may be connected. A low
pass filter is connected in series to each end of the segment. thereby
Forming a low-frequency path between the external ports of the low pass
filters, utilizing the low-frequency hand. Similarly. a high pass filter is
connected in series to each end of the segment, thereby forming a
high-frequency path between the external ports of the high pass filters,
utilizing the high-frequency band. The bandwidth carried by the segments is
thereby split into non-overlapping frequency hands, and the distinct paths
can be interconnected via the high pass filters and low pass filters as
coupling and isolating devices to form different paths. Depending on how
the devices and paths are selectively connected. these paths may be
simultaneously different for different frequencies. A low-frequency band is
allocated to regular telephone service (analog telephony), while a
high-frequency band is allocated to the data communication network.. In the
low-frequency (analog telephony) band. the wiring composed of the
coupled low-frequency paths appears as a normal telephone line, in such a
way that the low-frequency (analog telephony) hand is coupled among all
the segments and is accessible to telephone devices at any outlet, whereas
the segments may remain individually isolated in the high-frequency (data)
band, so that in this data band the communication media, if desired, can
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appear to be point-to-point (such as a serialized "daisy chain'") from one
outlet to the next. The term "low pass filter' herein denotes any device that
passes signals in the low-frequency (analog telephony) band but blocks
signals in the high-frequency (data) band. Conversely, the term "high pass
filter" herein denotes any device that passes signals in the high-frequency
(data) band but blocks signals in the low-frequency (analog telephony)
band. The term "data device" herein denotes any apparatus that handles
digital data, including without .limitation modems. transceivers, Data
Communication Equipment. and Data Terminal Equipment.
A network according to the present invention allows the telephone
devices to be connected as in a normal telephone installation (i.e., in
parallel over the telephone lines). but can be configured to virtually any
desired topology for data transport and distribution, as determined by the
available existing telephone line wiring and without being constrained to
any predetermined data network topology. Moreover. such a network offers
the potential, for the improved data transport and distribution performance
of a point-to-point network topology. while still allowing a bus-type data
network topology in all or part of the network if desired. This is in contrast
to the prior art, which constrains the network topology to a predetermined
type.
A network according to the present invention may be used
advantageously when connected to external systems and networks. such as
xDSL. ADSL. as well as the Internet.
In a first embodiment, the high pass filters are connected in such a
way to create a virtual 'bus' topology for the high-frequency band. allowing
for a local area network based on DCE units or transceivers connected to
the segments via the high pass filters. In a second embodiment, each
segment end is connected to a dedicated modem. hence offering a serial
point-to-point daisy chain network. In all embodiments of the present
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8a
invention, DTE units or other devices connected to the DCE units can
communicate over the telephone
line without interfering with, or being affected by, simultaneous analog
telephony service. Unlike prior-
art networks, the topology of a network according to the present invention is
not constrained to a
particular network topology determined in advance, but can be adapted to the
configuration of an existing
telephone line installation. Moreover, embodiments of the present invention
that feature point-to-point
data network topologies exhibit the superior performance characteristics that
such topologies offer over
the bus network topologies of the prior art such as the Dichter network and
the Crane network.
Therefore, according to one embodiment of the present invention there is
provided a device for
coupling a data unit to a digital data signal and for coupling a service unit
to an analog service signal, for
use with a service wire pair installed in walls of a building, the service
wire pair concurrently carrying a
bi-directional digital data signal and an analog service signal carried over a
service signal frequency band,
using frequency division multiplexing, and the digital data signal is carried
over a frequency band distinct
from the service signal frequency band, and the device comprises a single
enclosure and, within the single
enclosure:
a wiring connector for connecting to the service wire pair;
a first filter coupled to the wiring connector for passing only the analog
service signal;
a standard service connector coupled to the first filter and connectable to
the service unit for
coupling the service unit to the analog service signal;
a second filter coupled to the wiring connector for passing only the digital
data signal;
a modem coupled to the second filter for transmitting the digital data signal
to the service wire
pair and for receiving the digital data signal from the service wire pair;
a standard data connector connectable to the data unit;
a transceiver coupled to the standard data connector for coupling packet-based
bi-directional
digital data to the data unit;
a multiport device that is a selected one of a bridge, a router and a gateway
coupled to pass data
between the modem, and the transceiver for coupling the digital data carried
by the digital data signal and
the packet based digital data; and
a power supply coupled to the modem and the transceiver for powering the modem
and the
transceiver.
According to another embodiment of the present invention there is provided a
device for coupling
a first data unit and a second data unit to first and second distinct Internet-
based data streams carried over
a single xDSL connection using time division multiplexing, for use with a
telephone wire pair
concurrently carrying xDSL and analog telephony signals using frequency
division multiplexing, and the
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xDSL signal is carried over a high frequency band and the analog telephony
signal is carried over a low
frequency band, and the device comprises a single enclosure and, within the
single enclosure:
a telephone connector for connecting to the telephone wire pair;
a high pass filter coupled to the telephone connector for passing only the
xDSL signal;
a xDSL modem coupled to the high pass filter for transmitting and receiving
the xDSL signal;
a first standard data connector connectable to the first data unit;
a first data transceiver coupled with the first standard data connector for
first Internet-based data
stream communication with the first data unit;
a second standard data connector connectable to the second data unit;
a second data transceiver coupled with the second standard data connector for
second Internet-
based data stream communication with the first data unit; and
a multipart device that is a selected one of a bridge, a router and a gateway
coupled to the xDSL
modem, and the first and second data transceivers for coupling the xDSL signal
and the first and second
Internet-based data streams,
According to another embodiment of the present invention there is provided a
device for coupling
first and second bi-directional digital data signals, each carried over a
distinct wiring, to each other and to
a data unit, for use with a telephone wire pair at least in part in a
building, the telephone wire pair
concurrently carrying first bi-directional digital data using a xDSL signal
containing the first bi-
directional digital data and an analog telephone signal over a telephone
signal frequency band, and the
xDSL signal is carried over a frequency band distinct from and higher than the
telephone signal frequency
band, and a service wire pair installed at least in part in walls within a
building, the service wire pair
concurrently carrying a second bi-directional digital data signal containing
second bi-directional digital
data and an analog service signal carried over an analog service signal
frequency band, using frequency
division multiplexing wherein the second bi-directional digital data signal is
carried over a frequency
band distinct from the analog service signal frequency band, and the device
comprising a single enclosure
and, within the single enclosure:
a telephone connector for connecting the device to the telephone wire pair;
a high pass filter coupled to the telephone connector for passing only the
xDSL signal;
a xDSL modem coupled to the high pass filter for coupling with the first bi-
directional data
signal;
a service wiring connector for connecting the device to the service wire pair;
a filter coupled to the service wiring connector for passing only the second
bi-directional data
signal;
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a service wiring modem coupled to the filter for coupling with the second bi-
directional data
signal;
a multiport unit that is one of a bridge, a router and a gateway coupled to
the xDSL modem and
service wiring modem and operative to couple the first and second bi-
directional digital data to each
other; a standard data interface coupled to the multiport unit for coupling a
standard data interface signal
to at least one of the xDSL signal and the second bi-directional digital data
signal; and
a standard data connector coupled to the standard data interface and
connectable to a data unit for
coupling the standard data interface signal to the data unit.
According to another embodiment of the present invention there is provided a
device for coupling
a first data unit and a second data unit to respective first and second
distinct data streams, for use with a
wiring concurrently carrying over the same wires a power signal and a digital
data signal, the digital data
signal including the first and second distinct data streams carried using time
division multiplexing, and
the device comprises a single enclosure and, within the single enclosure:
a wiring connector for connecting to the wiring;
a wiring modem coupled to the wiring connector for coupling to the digital
data signal;
a first standard data connector connectable to the first data unit;
a first data transceiver coupled to the first standard data connector for data
communication with
the first data unit;
a second standard data connector connectable to the second data unit;
a second data transceiver coupled to the second standard data connector for
data communication
with the second data unit; and
a multiport unit coupled to the wiring modem and the first and second data
transceivers for
coupling only the first data stream to the first data transceiver and for
coupling only the second data
stream to the second data transceiver, and
wherein at least part of the device is coupled to the wiring connector to be
powered by the power
signal.
According to another embodiment of the present invention there is provided a
device for coupling
a first data unit and a second data unit to respective first and second
distinct data streams, for use with a
wiring at least in part in walls of a building and carrying a digital data
signal, the digital data signal
including the first and second distinct data streams carried using time
division multiplexing, and the
device comprises a single enclosure and, within the single enclosure:
a wiring connector for connecting to the wiring;
a modem coupled to the wiring connector for coupling to the digital data
signal;
a first standard data connector connectable to the first data unit;
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a first data transceiver coupled to the first standard data connector for data
communication with
the first data unit;
a second standard data connector connectable to the second data unit;
a second data transceiver coupled to the second standard data connector for
data communication
with the second data unit; and
a multiport unit coupled to the modem and the first and second data
transceivers for coupling only
the first data stream to the first data transceiver and for coupling only the
second data stream to the
second data transceiver, and
wherein at least one of the modem and the first and second data transceivers
comprises power
consuming components.
According to another embodiment of the present invention there is provided an
apparatus for
configuring a network in a building, the network having first and second
wiring segments, each wiring
segment comprising at least two conductors installed at least in part in a
wall of the building, the first
wiring segment carrying a frequency domain multiplexed first packet-based
digital data signal and a first
analog signal, and the second wiring segment carrying a frequency domain
multiplexed second packet-
based digital data signal and a second analog signal, the apparatus
comprising:
first and second ports each connectable to a respective one of the first and
second wiring
segments;
first and second data filters each coupled to a respective one of the first
and second ports, each
having a data signal port operative to pass only a respective one of the first
and second digital data
signals;
first and second modems each coupled to the data signal port of a respective
one of the first and
second filters, and each operative for bi-directionally conducting a
respective packet-based data signal
over a respective one of the first and second wiring segments;
at least one data connector operative for establishing a data signal
connection with a data unit;
a multiport unit coupling the first and second modems to the at least one data
connector for data
transfer between the modems and the at least one data connector, the multiport
unit being constituted by
one of a repeater; a bridge; and a router;
first and second analog filters each coupled to a respective one of the first
and second ports, each
having a respective analog signal port and each operative to pass only a
respective one of the first and
second analog signals; and
a single enclosure housing the ports, the data filters, the modems, the at
least one data connector,
the multiport unit and the analog filters,
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wherein the analog signal ports of the first and second analog filters are
coupled to each other for
coupling the first and second analog signals to each other,
According to another embodiment of the present invention there is provided an
apparatus for
configuring a network in a building, for use with first and second wiring
segments, each wiring segment
comprising at least two conductors installed at least in part in a wall of the
building, the first wiring
segment carrying a frequency domain multiplexed first packet-based digital
data signal and a first analog
signal, the second wiring segment carrying a frequency domain multiplexed
second packet-based digital
data signal and a second analog signal, the apparatus comprising:
first and second ports each connectable to a respective one of the first and
second wiring
segments;
first and second data filters each coupled to a respective one of the first
and second ports, each
having a data signal port operative to pass only a respective one of the first
and second digital data
signals;
first and second modems each coupled to the data signal port of a respective
one of the first and
second filters, and each operative for bi-directionally conducting a
respective packet-based data signal
over a respective one of the first and second wiring segments;
at least one data connector operative for establishing a data signal
connection with a data unit;
a multiport unit coupling the first and second modems to the at least one data
connector for data
transfer between the modems and the at least one data connector, the multiport
unit being constituted by
one of, a repeater; a bridge; and a router;
an analog filter coupled to the first port and having an analog signal port
and operative to pass
only the first analog signal;
an analog connector operative for establishing an analog signal connection
with an analog unit,
the analog connector being coupled to the analog signal port of the analog
filter; and
a single enclosure housing the ports, the data filters, the modems, the at
least one data connector,
the multiport unit, the analog filter and the analog connector.
According to another embodiment of the present invention there is provided an
apparatus for
configuring a network in a building, for use with first and second wiring
segments, each wiring segment
comprising at least two conductors installed at least in part in a wall of the
building, the first wiring
segment carrying a frequency domain multiplexed first packet-based digital
data signal and a first analog
signal, the second wiring segment carrying a frequency domain multiplexed
second packet-based digital
data signal and a second analog signal, the apparatus comprising:
first and second ports each connectable to a respective one of the first and
second wiring
segments;
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first and second data filters each coupled to a respective one of the first
and second ports, each
having a data signal port operative to pass only a respective one of the first
and second digital data
signals;
first and second modems each coupled to the data signal port of a respective
one of the first and
second filters, and each operative for bi-directionally conducting a
respective packet-based data signal
over a respective one of the first and second wiring segments;
at least one data connector operative for establishing a data signal
connection with a data unit;
a multiport unit coupling the first and second modems to the at least one data
connector for data
transfer between the modems and the at least one data connector, the multiport
unit being constituted by
one of. a repeater, a bridge; and a router;
a telephone connector connectable to a telephone device, the telephone
connector being coupled
to the first port; and
a single enclosure housing the ports, the data filters, the modems, the at
least one data connector,
the multiport unit and the telephone connector.
According to another embodiment of the present invention there is provided a
network interface
device for coupling data units to the Internet over pre-existing PSTN wiring,
for use with a first telephone
wire pair at least in part external to a building and connected to a PSTN
network and connected for
carrying an xDSL signal and with a second telephone wire pair at least in part
in a wall of the building
and connected to a telephone outlet, the second telephone wire pair being
connected for concurrently
carrying an analog telephone signal in an analog telephone frequency band,
frequency multiplexed with a
bi-directional serial digital data signal in a digital data frequency band,
the digital data frequency band
being distinct from, and higher than, the analog telephone frequency band, the
device comprising;
a first port for connecting to the first telephone wire pair;
an xDSL modem coupled to the first port for conducting xDSL-based full-duplex
serial digital
data over the first telephone pair;
a second port for connecting to the second telephone wire pair;
a third port for connecting to a source of an analog telephone signal;
a first low pass filter connected between the second and third ports for
substantially passing
signals in the analog telephone frequency band and for substantially stopping
signals in the digital data
frequency band;
a telephone line modem connected for conducting the bi-directional serial
digital data signal in
the digital data frequency band over the second telephone wire pair;
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a first high pass filter coupled between the second port and the telephone
line modem for
substantially passing signals in the digital data frequency band and for
substantially stopping signals in
the analog telephone frequency band;
a digital data connector for connecting to a data unit; a local area network
transceiver coupled to
the digital data connector for packet-based bi-directional digital data
communication with the data unit;
a router coupled to the xDS1:. modem, the telephone line modem and the local
area network
transceiver for packet-based data transfer between the xDSL modem, the
telephone line modem and the
local area network transceiver; and
a single enclosure housing the first, second and third ports, the xDSL modem,
the low pass filter,
the high pass filter, the telephone line modem, the digital data connector and
the router, wherein the single
enclosure is mountable to a wall of the building.
According to another embodiment of the present invention there is provided an
apparatus for
configuring a local area network in a building for the transport of digital
packet-based data signals and
analog signals across a wiring using frequency domain multiplexed analog and
digital packet-based data
signals, and the wiring including at least first and second wiring segments
each including at least two
conductors, the apparatus comprising:
first and second ports each connectable to a respective one of the first and
second wiring
segments;
first and second data filters each coupled to a respective one of the first
and second ports, each
having a digital data signal port operative to pass only digital packet-based
data signals;
first and second modems each coupled to the digital data signal port of a
respective one of the
first and second filters, operative for bi-directional digital packet-based
data signal communication with a
respective one of the first and second wiring segments;
at least one data connector operative for establishing a bi-directional
digital packet-based data
connection with a data unit;
a multiport unit coupling the first and second modems to the at least one data
connector for
packet-based data transfer between the modems and the at least one data
connector, the multiport unit
being constituted by one of a bridge and a router; and
a single enclosure housing the ports, the data filters, the modems, the at
least one data connector
and the multipart unit,
According to another embodiment of the present invention there is provided a
device for coupling
a digital data signal to a first data unit, for use with a telephone wire pair
installed at least in part in walls
of a building, the telephone wire pair being connected for carrying a bi-
directional digital data signal in a
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digital data frequency band distinct from, and higher than, an analog
telephone frequency band, and the
device comprises a single enclosure and, within the single enclosure:
a telephone connector for connecting to the telephone wire pair;
a modem connected for transmitting to and receiving the bi-directional digital
data signal over the
telephone wire pair;
a high pass filter coupled between the telephone connector and the modem for
substantially
passing signals in the digital data frequency band;
a data connector connectable to the first data unit;
a transceiver coupled to the data connector for transmitting and receiving
packet-based bi-
directional digital data with the first data unit; and
a router or a gateway coupled to pass digital data between the modem and the
transceiver for
handling protocol layers above the physical layer.
BRIEF DESCRIPTION OF THE DRAWTN S
In order to understand the invention and to see how the same may be carried
out in practice, some
preferred embodiments will now be described, by way of non-limiting example
only, with reference to the
accompanying drawings, wherein:
Figure 1 shows a common prior art telephone line wiring configuration for a
residence or other
building.
Figure 2 shows a prior art local area network: based on telephone line wiring
for a residence or
other building.
Figure 3 shows modifications to telephone line wiring according to the present
invention for a
local area network.
Figure 4 shows modifications to telephone line wiring according to the present
invention to
support regular telephone service operation.
Figure 5 shows a splitter according to the present invention.
Figure 6 shows a local area network based on telephone lines according to the
present invention
wherein the network supports two devices at adjacent outlets.
Figure 7 shows a first embodiment of a local area network based on telephone
lines according to
the present invention, wherein the network 25 supports two devices at non-
adjacent outlets.
Figure 8 shows a second embodiment of a local area network based on telephone
lines according
to the present invention, wherein the network supports three devices at
adjacent outlets.
CA 02630013 2008-05-13
-f3-
Figure 9 shows third embodiment of a local area network based on
telephone lines according to the present invention. wherein the network is a
bus type network.
Figure 10 shows a node of local area network based on telephone
lines according to the present invention.
Figure 11 shows a fourth embodiment of a local area network based
on telephone lines according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The principles and operation of a network according to the present
invention may be understood with reference to the drawings and the
accompanying description. The drawings and descriptions are conceptual
only. In actual practice, a single component can implement one or more
functions: alternatively. each function can be implemented by a plurality of
components and circuits. In the drawings and descriptions, identical
reference numerals indicate those components which are common to
different embodiments or configurations.
The basic concept of the invention is shown in Figure 3. A network
30 is based on modified telephone outlets 31a. 31b. 31c and 31d. The
modification relates to wiring changes at the outlets and substituting the
telephone connectors, shown as connectors 32a. 32b. 32c and 32d in outlets
31a, 31b. 31c and 31d respectively. No changes are required in the overall
telephone line layout or configuration. The wiring is changed by separating
the wires at each outlet into distinct segments of electrically-conducting
25" media. Thus, each segment connecting two outlets can be individually
accessed from either end. In the prior art Dichter network, the telephone
wiring is not changed, and is continuously conductive from junction box 16
throughout the system. According to the present invention, the telephone
line is broken into electrically distinct isolated segments 15a, 15b, 15c, 15d
CA 02630013 2008-05-13
and 15e, each of which connects two outlets. In order to fully access the
media. each of connectors 32a. 32b. 32c and 32d must support four
connections. two in each segment. This modification to the telephone line
can be carried out by replacing each of the outlets 31a. 31b. 31c and 31d.
replacing only the connectors 32a. 32b. 32c and 32d. or simply by cutting
the telephone line wiring at the outlet. As will he explained later, these
modifications need be performed only to those outlets which connect to
data network devices, but are recommended at all other outlets. A minimum
of two outlets must be modified. enabling data communication between
those outlets only.
Figure 4 shows how a network 40 of the present invention continues
to support the regular telephone service. by the installation of jumpers 41.a.
41b. 41c and 41d in modified outlets 31a. 31b, 31c and 31d respectively.
At each outlet where they are installed, the jumpers connect both segment
ends and allow telephone connection to the combined segment. Installation
of a jumper effects a re-connection of the split telephone line at the point
of
installation. Installation of_jumpers at all outlets would reconstruct the
prior
art telephone line configuration as shown in Figure 1. Such jumpers can be
add-ons to the outlets, integrated within the outlets, or integrated into a
separate module. Alternately, a jumper can be integrated within a telephone
set. as part of connector 14. The term "jumper" herein denotes any device
for selectively coupling or isolating the distinct segments in a way that is
not specific to the frequency band of the coupled or isolated signals. Jumper
41 can be implemented with a simple electrical connection between the
connection points of connector 32 and the external connection of the
telephone.
As described above. jumpers 41 are to be installed in all outlets
which are not required for connection .to the data communication network.
Those outlets which are required to support data communication
CA 02630013 2008-05-13
connections, however. will not use jumper 41 but rather a splitter 50. shown
in Figure 5. Such a splitter connects to both segments in each modified,
outlet 31 via connector 32. using a port 54 for a first connection and a port
55 for a second connection. Splitter 50 has two LPF's for maintaining the
continuity of the audio / telephone l()w-frequencv band. After low pass
filtering by LPF 51a for the port 54 and LPF 51b for port 55. the analog
telephony signals are connected together and connected to a telephone
connector 53. Hence, from the point of view of the telephone signal, the
splitter 50 provides the same continuity and telephone access provided by
the jumper 41. On the other hand. the data communication network employs
the high-frequency band. access to which is made via HPF's 52a and 52b.
HPF 52a is connected to port 54 and HPF 52b is connected to port 55. The
high pass filtered signals are not passed from port 54 to port 55, but are
kept
separate. and are routed to a connector 56 and a connector 57. respectively.
The term "splitter" herein denotes any device for selectively coupling or
isolating the distinct segments that is specific to the frequency band of the
coupled or isolated signals.
Therefore, when installed in an outlet. the splitter 50 serves two
functions. With respect to the low-frequency analog telephony band, splitter
50 establishes a coupling to effect the prior-art configuration shown in
Figure 1. wherein all telephone devices in the premises are connected
virtually in parallel via the telephone line. as if the telephone line were
not
broken into segments. On the other hand, with respect to the high-frequency
data communication network, splitter 50 establishes electrical isolation to
effect the configuration shown in Figure 3. wherein the segments are
separated, and access to each segment end is provided by the outlets. With
the use of splitters, the telephone system and the data communication
network are actually decoupled. with each supporting a different topology.
CA 02630013 2008-05-13
Figure 6 shows a first embodiment of a data communication network
60 between two DTE units 24a and 24b. connected to adjacent outlets 31b
and 31c. which are connected together via it single segment 15c. Splitters
50a and 50b are connected to outlets 31 b and 31 c via connectors 32b and
32c. respectively. As explained above. the splatters allow transparent audio /
telephone signal connection. Thus. for analog telephony. the telephone line
remains virtually unchanged, allowing access to telephone external
connection 17 via junction box 16 for telephones 13a and 13c. Likewise.
telephone 13b connected via connector 14b to it connector 53a on splitter
50a. is also connected to the telephone line. In a similar way. an, additional
telephone can be added to outlet 31c by connecting the telephone to
connector 53b on splitter SOb. It should be clear that connecting a telephone
to an outlet, either via jumper 41 or via splitter 50 does not affect the data
communication network.
Network 60 (Figure 6) supports data communication by providing a
communication path between port 57a of splitter 50a and port 56b of
splitter 50b. Between these ports there exists a point-to-point connection for
the high-frequency portion of the signal spectrum. as determined by HPF
52a and 52b within splitters 50 (Figure 5). This path can be used to
establish a communication link between DTE units 24a and 24b. by means
of DCE units 23a and 23b. which are respectively connected to ports 57a
and 56b. The communication between DTE units 24a and 24b can be
unidirectional, half-duplex, or full-duplex. The only limitation imposed.on
the communication system is the capability to use the high-frequency
portion of the spectrum of segment 15c. As an example. the implementation
of data transmission over a telephone line point-to-point system described
in Reichert can also be used in network 60. Reichert implements both LPF
and HPF by means of a transformer with a capacitor connected in the
CA 02630013 2008-05-13
center-tap, as is well known in the art. Similarly. splitter 50 can be easily
implemented by two such circuits. one for each side.
It should also be apparent that HPF 52a in splitter 50a and HPF 52b
in splitter 50b can be omitted. because neither port 56a in splitter 50a nor
port 57b in splitter 50b is connected.
Network 60 provides clear auvantages over the networks described
in hitherto-proposed networks. First. the communication media supports
point-to-point connections, which are known to he superior to multi-tap
(bus) connections for communication performance. In addition, terminators
can be used within each splitter or DCE unit. providing a superior match to
the transmission line characteristics. Furthermore. no taps (drops) exists in
the media, thereby avoiding impedance matching problems and the
reflections that result therefrom.
Moreover, the data communication system in network 60 is isolated
from noises from both the network. and the 'left- part of the telephone
network (Segments 15a and 15b). as well as noises induced from the 'right'
portion of the network (Segments 15d and 15e). Such isolation is not
provided in any prior-art implementation. Dichter suggests installation of a
low pass filter in the junction box. which is not a satisfactory solution
since
the junction box is usually owned by the telephone service provider and
cannot always be accessed. Furthermore. safety issues such as isolation.
lightning protection, power-cross and other issues are involved in such a
modification.
Implementing splitter 50 by passive components only, such as two
transformers and two center-tap capacitors. is also advantageous. since the
reliability of the telephone service will not be degraded, even in the case of
failure in any DCE unit, and furthermore requires no external power. This
accommodates a `life-line' function, which provides for continuous
CA 02630013 2008-05-13
telephone service even in the event of other system malfunction . (e.g.
electrical failures).
The splitter 50 can be integrated into outlet 31. In such a case. outlets
equipped with splitter 50 will have two types of connectors: One regular
telephone connector based on port 53. and one or two connectors providing
access to ports 56 and 57 (a single quadruple-circuit connector or two
double-circuit connectors). Alternatively, splitter 50 can be an independent
module attached as an add-on to outlet 31. In another embodiment, the
splitter is included as part of DCE 23. However. in order for network 60 to
operate properly. either jumper 41 or splitter 50 must be employed in outlet
31 as modified in order to split connector 32 according to the present
invention, allowing the retaining of regular telephone service.
Figure 7 also shows data communication between two DTE units
24a and 24b in a network 70. However, in the case of network 70, DTE
units 24a and 24b are located at outlets 31b and 31d. which are not directly
connected, but have an additional outlet 31c interposed therebetween.
Outlet 31c is connected to outlet 31b via a segment 15c. and to outlet 31d
via a segment 15d.
In one embodiment of network 70. a jumper (not shown, but similar
to jumper 41 in Figure 4) is connected to a connector 32c in outlet 31c. The
previous discussion regarding the splitting of the signal spectrum also
applies here, and allows for data transport.between DTE units 24a and 24b
via the high-frequency portion of the spectrum across segments .15c and
15d. When only jumper 41 is connected at outlet 31c, the same
point-to-point performance as previously discussed can be expected; the
only influence on communication performance is from the addition of
segment 15d, which extends the length of the media and hence leads to
increased signal attenuation. Some degradation. however, can also be
expected when a telephone is connected to jumper 41 at outlet 31c. Such
CA 02630013 2008-05-13
degradation. can be the result of noise produced by the telephone in the
high-frequency data communication band. as well as the result of the
addition of a tap caused by the telephone connection. which usually has a
non-matched termination. Those problems can he overcome by installing a
low pass filter in the telephone.
In a preferred embodiment of network 70. a splitter 50b is installed
in outlet 31c. Splitter 50b provides the LPF functionality, and allows for
connecting a telephone via connector 53b. However, in order to allow for
continuity in data communication. there must be a connection between the
circuits in connectors 56b and 57b. Such a connection is obtained by a
.jumper 71. as shown in Figure 7. Installation of spotter 50b and jumper 71
provides good communication performance. similar to network 60 (Figure
6). From this discussion of a system wherein there is only one unused outlet
between the outlets to which the DTE units are connected, it should be clear
l5 that the any number.of unused outlets between the outlets to which the DTE
units are connected can he handled in the same manner.
For the purpose of the foregoing discussions. only two
communicating DTE units have been described. However, the present
invention can be easily applied to any number of DTE units. Figure 8
illustrates a network 80 supporting three DTE units 24a, 24b and 24c,
connected thereto via DCE units 23a. 23b and 23c. respectively. The
structure of network 80 is the same as that of network 70 (Figure 7). with
the exception of the substitution of jumper 71 with a jumper 81. Jumper 81
makes a connection between ports 56b and 57b in the same way as does
jumper 71. However, in a manner similar to that of jumper 41 (Figure 4),
jumper 81 further allows for an external connection to the joined circuits,
allowing the connection of external unit. such as a DCE unit 23c. In this
way, segments 15c and 15d appear electrically-connected for high-
frequency signals, and constitute media for a data communication network
CA 02630013 2008-05-13
connecting DTE units 24a. 24b and 24c. Obviously. this configuration can
he adapted to any number of outlets and DTE units. In fact, any data
communication network which supports a "bus' or multi-point connection
over two-conductor media. and which also makes use of the
higher-frequency part of the spectrum can be used. In addition, the
-discussion and techniques explained in the Dichter patent are equally
applicable here. Some networks. such as Ethernet IEEE 802.3 interface
IOBaseT and 100BaseTX. require a four-conductor connection. two
conductors (usually single twisted-wire pair) for transmitting, and two
conductors (usually another twisted-wire pair) for receiving. As is known in
the art, a four-to-two wires converter (commonly known as hybrid) can be
used to convert the four wires required into two. thereby allowing network
data transport over telephone lines according to the present invention.
As with jumper 41 (Figure 4. jumper 81 can be an integral part of
splitter 50, an integral part of DCE 23, or a separate component.
In order to simplify the installation and operation of a network. it is
beneficial to use the same equipment in all parts of the network. One such
embodiment supporting this approach is shown in for a set of three similar
outlets in Figure 8, illustrating network 80. In network 80. outlets 31 b.
31c.
and 31d are similar and are all used as part of the data communication
network. Therefore for uniformity. these outlets are all coupled to splitters
50a. 50b, and 50c respectively, to which jumpers are attached. such as a
jumper 81 attached to splitter 50b (the corresponding jumpers attached to
splitter 50a and splitter 50c have been omitted from Figure 8 for clarity),
and thus provide connections to local DCE units 23a. 23c, and 23b,
respectively. In a preferred embodiment of the present invention, all outlets
in the building will be modified to include both splitter 50 and jumper 81
functionalities. Each such outlet will provide two connectors: one connector
..............
CA 02630013 2008-05-13
-21-
coupled to port 53 for a telephone connection. and the other connector
coupled to.jumper 81 for a DCE connection.
In yet another embodiment. DCE 23 and splitter 50 are integrated
into the housing of outlet 31, thereby offering a direct DTE connection. In a
preferred embodiment, a standard DTE interface is employed.
In most 'bus' type networks- it is occasionally required to split the
network into sections, and connect the sections via repeaters (to compensate
for long cabling), via bridges (to decouple each section from the others), or
via routers. This may also be done according to the present invention, as
illustrated in Figure 9 for a network 90. which employs a repeater / bridge
router unit 91. Unit 91 can perform repeating. bridging. routing, or any
other function associated with a split between two or more networks. As
illustrated, a splitter 50b is coupled to an outlet 31 c. in a manner similar
to
the other outlets 'and. splitters of network 90. However, at splitter 50b, no
jumper is employed. Instead, a repeater / bridge/ router unit 91 is connected
between port 56b and port 57b, thereby providing a connection between
separate parts of network 90. Optionally. unit 91 can also provide an
interface to DTE 24c for access to network 90.
Figure 9 also demonstrates the capability of connecting to external
DTE units or networks, via a high pass filter 92 connected to a line 15a.
Alternatively, HPF 92 can be installed in junction box 16. HPF 92 allows
for additional external units to access network 90. As shown in Figure 9.
HPF 92 is coupled to a DCE unit 93. which in turn is connected to a
network 94. In this configuration, the local data communication network in
the building becomes part of network 94. In one embodiment, network 94
offers ADSL service, thereby allowing the DTE units 24d. 24a. 24c and
24b within the building to communicate with the ADSL network. The
capability of communicating with external DTE units or networks is equally
CA 02630013 2008-05-13
applicable to all other embodiments of the present invention, but for clarity
is omitted from the other drawings.
While the foregoing relates to data communication networks
employing bus topology. the present invention can also support networks
where the physical layer is distinct within each communication link. Such a
network can be a Token-Passing or 'token-Ring network according to IEEE
802. or preferably a PSIC network as described in U.S. Patent 5,841.360 to
the present inventor, which details the advantages of such a topology.
Figure 10 illustrates a node 100 for implementing such a network. Node
100 employs two modems 103a and 103b. which handle the
communication physical layer. Modems 103a and .103b are independent.
and couple to dedicated communication links 104a and 104b, respectively.
Node 100 also features a DTE interface 101 for connecting to a DTE unit
(not shown). A control and logic unit 102 manages the higher OSI layers of
the data communication above the physical layer. processing the data to and
from a connected DTE and handling the network control. Detailed
discussion about such node 100 and the fiinctioning thereof can be found in
U.S. Patent 5.841.360 and other sources known in the art.
Figure 11 describes a network 110 containing nodes 100d. 100a,
100b and 100c coupled directly to splitters 50d. 50a. 50b and 50c, which in
turn are coupled to outlets 31a, 31b. 31c and 31d respectively. Each node
100 has access to the corresponding splitter 50 via two pairs of contacts,
one of which is to connector 56 and the other of which is to connector 57.
In this way, for example. node 100a has independent access to both
segment 15b and segment 15c. This arrangement allows building a network
connecting DTE units 24d. 24a. 24b and 24c via nodes 100d, 100a, 100b
and 100c, respectively.
For clarity, telephones are omitted from Figures 9 and 11. but it will
be clear that telephones can be connected or removed without affecting the
CA 02630013 2008-05-13
- 12 ^
data communication network. Telephones can be connected as required via
connectors 53 of splitters 50. In general. according to the present invention,
a telephone can be connected without any modifications either to a splitter
50 (as in Figure 8) or to a jumper 41 (as in Figure 4).
Furthermore, although the present invention , has so far been
described with a single DTE connected to a single outlet. multiple DTE
units can be connected to an outlet, as long as the corresponding node or
DCE supports the requisite number of connections. Moreover, access to the
communication media can he available for plurality of users using
multiplexing techniques known in the art. In the case of time domain /
division multiplexing (TDM) the whole bandwidth is dedicated to a specific
user during a given time interval. In the case of frequency domain / division
multiplexing (FDM). a number of users can share the media
simultaneously, each using different non-overlapping portions of the
frequency spectrum.
In addition to the described data communication purposes, a network
according to the present invention can be used for control (e.g. home
automation), sensing, audio, or video applications. and the communication
can also utilize analog signals (herein denoted by the term "analog
communication"). For example. a video signal can be transmitted in analog
form via the network.
While the present invention has been described in terms of outlets
which have only two connections and therefore can connect only to two
other outlets (i.e., in a serial, or 'daisy chain" configuration), the concept
can also be extended to three or more connections. In such a case, each
additional connecting telephone line must be broken at the outlet, with
connections made to the conductors thereof. in the same manner as has been
described and illustrated for two segments. A splitter for such a multi-
CA 02630013 2008-05-13
segment application should use one low pass filter and one high pass filter
for each segment connection.
The present invention has also been described in terms of media
having a single pair of wires, but can also be applied for more conductors.
For example. ISDN employs two pairs for communication. Each pair can be
used individually for a data communication network as described above.
Also as explained above. an outlet 31 according to the invention
(Figure 3) has a connector 32 having, at least four connection points. As an
option, Jumper 41 (Figure 4), splitter 50 (Figure 5). or splitter 50 with
Jumper 81 (Figure 8), low pass filters. high pass filters, or other additional
hardware may also be integrated or housed internally within outlet 31.
Alternatively, these devices may be external to the outlet. Moreover, the
outlet may contain standard connectors for devices. such as DTE units. In
one embodiment, only passive components are included within the outlet.
For example, splitter 50 can have two transformers and two capacitors (or
an alternative implementation consisting of passive components). In another
embodiment, the outlet may contain active. power-consuming components.
Three options can be used for providing power to such circuits:
1. Local powering: In this option. supply power is fed locally to
each power-consuming outlet. Such outlets must be modified to
support connection for input power.
2. Telephone power: In both POTS and ISDN telephone networks,
power is carried in the lines with the telephone signals. This
power can also be used for powering the outlet circuits. as long as
the total power consumption does not exceed the POTS / ISDN
system specifications. Furthermore, in some POTS. systems the
power consumption is used for OFF-HOOK/ON-HOOK
signaling. In such a case. the network power consumption must
not interfere with the telephone logic.
CA 02630013 2008-05-13
-2-5-
Dedicated power carried in the media: In this option, power for
the data communication related components is carried in the
communication media. For example. power can be distributed
using 5 kHz signal. This frequency is beyond the telephone signal
bandwidth. and thus does not interfere with the telephone service.
The data communication bandwidth. however.- be above this
5 kHz frequency. again ensuring that there is no interference
between power and signals.
While the invention has been described with respect to a limited
number of embodiments, it will be appreciated that many variations.
modifications and other applications of the invention may be made.
