Note: Descriptions are shown in the official language in which they were submitted.
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A Surface Wave Power Line Communications System and Method
Cross Reference to Related Applications
[0001] This application claims priority under 35 U.S.C. ~ 119(e) to U.S.
Provisional Patent Application Serial No. 60/511,260 filed October 15, 2003
(Attorney
Docket No. CRNT-0207), which is incorporated herein by reference in its
entirety.
Field of the Invention
[0002] The present invention generally relates to data communications over a
power distribution system and more particularly, to a power line communication
system
employing surface wave communications and conductive communications and method
of using the same.
Background of the Invention
[0003] Well-established power distribution systems exist throughout most of
the United States, and other countries, which provide power to customers via
power
lines. With some modification, the infrastructure of the existing power
distribution
systems can be used to provide data communication in addition to power
delivery,
thereby forming a power line communication system (PLCS). In other words,
existing
power lines, that already have been run to many homes and offices, can be used
to
carry data signals to and from the homes and offices. These data signals are
communicated on and off the power lines at various points in the power line
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communication system, such as, for example, near homes, offices, Internet
service
providers, and the like.
[0004] While the concept may sound simple, there are many challenges to
overcome in order to use power lines for data communications. Such lines also.
Overhead power lines are not designed to provide high speed data
communications and
are a relatively high impedance communication medium to conductive
transmission
frequencies used to carry high speed communications. Conductive communications
on
overhead power lines also are very susceptible to interference. Additionally,
federal
regulations limit the amount of radiated energy of a power line communication
system,
which therefore limits the power of the data signal that can be injected onto
power lines.
[0005] Power distribution systems include numerous sections, which transmit
power at different voltages. The transition from one section to another
typically is
accomplished with a transformer. The sections of the power distribution system
that are
connected to the customers premises typically are low voltage (LV) sections
having a
voltage between 100 volts(V) and 240V, depending on the system. In the United
States, the LV section typically is about 120V. The sections of the power
distribution
system that provide the power to the LV sections are referred to as the medium
voltage
(MV) sections. The voltage of the MV section is in the range of 1,OOOV to
100,OOOV.
The transition from the MV section to the LV section of the power distribution
system
typically is accomplished with a distribution transformer, which converts the
higher
voltage of the MV section to the lower voltage of the LV section.
[0006] Power system transformers are one obstacle to using power distribution
lines for conductive data communications. Transformers act as a low-pass
filter,
passing the low frequency signals (e.g., the 50 or 60 Hz) power signals and
impeding
the high frequency signals (e.g., frequencies typically used for data
communication). As
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such, power line communication systems face the challenge of communicating the
data
signals around, or through, the distribution transformers.
[0007] Furthermore, up to ten (and sometimes more) customer premises will
typically receive power from one distribution transformer via their respective
LV power
lines. However, all of the customer premises LV power lines typically are
electrically
connected at the transformer. Consequently, a power line communications system
must be able to tolerate the interference produced by many customers. In
addition, the
power line communication system should provide bus arbitration and router
functions for
numerous customers who share a LV subnet (i.e., the customer premises that are
all
electrically connected to the power lines extending from the LV side of the
transformer)
and a MV power line.
[0008] In addition, components of the power line communication system must
electrically isolate the MV power signal from the LV power lines and the
customer
premises. In addition, a communication device of the system should be designed
to
facilitate bi-directional communication and to be installed without disrupting
power to
customers. These and other advantages are provided by various embodiments of
the
present invention.
Summary of the Invention
[0009] The present invention provides a power line communication system
employing surface wave communications and conductive communications and method
of using the same that is comprised of a plurality of network elements, which
may take
the form of wave couplers, amplifiers, regenerators, communication interface
devices,
backhaul devices, aggregation points and others. In one embodiment, surfaces
wave
communications are used to communicate data on the MV power lines and
conductive
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communications are used to communicate data on the LV power lines to and from
the
customer premises.
Brief Description of the Drawings
[0010] The invention is further described in the detailed description that
follows,
by reference to the noted drawings by way of non-limiting illustrative
embodiments of
the invention, in which like reference numerals represent similar parts
throughout the
drawings. As should be understood, however, the invention is not limited to
the precise
arrangements and instrumentalities shown. In the drawings:
[0011] Figure 1 is a diagram of an exemplary embodiment of the present
invention;
[0012] Figure 2 is a diagram of components of one embodiment of the present
invention;
[0013] Figure 3 is a schematic of an embodiment of an amplifier of the present
invention;
[0014] Figure 4 is a diagram of a number of example antenna configurations in
accordance with an embodiment of the present invention;
[0015] Figure 5 is a diagram of a number of example antenna configurations in
accordance with an embodiment of the present invention;
[0016] Figures 6 is a functional block diagram of a portion of a communication
interface device, in accordance with an embodiment of the present invention;
[0017] Figure 7 is a diagram of an example embodiment of a medium voltage
transducer of the present invention;
[0018] Figure 8 is a diagram of an example embodiment of a wave coupler of
an embodiment of the present invention;
[0019] Figure 9 is a diagram of another example embodiment of a medium
voltage transceiver of an embodiment of the present invention;
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[0020] Figure 10 illustrates another embodiment of a medium voltage
transducer and communication interface device, in accordance with another
embodiment of the present invention;
[0021] Figure 11 is a schematic of a portion of a power line communication
system in accordance with an embodiment of the present invention; and
[0022] Figure 12 is a schematic of a portion of a power line communication
system in accordance with another embodiment of the present invention.
Detailed Description of Illustrative Embodiments
[0023] In the following description, for purposes of explanation and not
limitation, specific details are set forth, such as particular networks,
communication
systems, computers, terminals, devices, components, techniques, data and
network
protocols, software products and systems, operating systems, development
interfaces,
hardware, etc. in order to provide a thorough understanding of the present
invention.
[0024] However, it will be apparent to one skilled in the art that the present
invention may be practiced in other embodiments that depart from these
specific details.
Detailed descriptions of well-known networks, communication systems,
computers,
terminals, devices, components, techniques, data and network protocols,
software
products and systems, operating systems, development interfaces, and hardware
are
omitted so as not to obscure the description of the present invention.
System Architecture and General Design Concepts
[0025] Power distribution systems typically include components for power
generation, power transmission, and power delivery. A transmission substation
typically
is used to increase the voltage from the power generation source to high
voltage (HV)
levels for long distance transmission on HV transmission lines to a
substation. Typical
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voltages found on HV transmission lines range from 69 kilovolts (kV) to in
excess of 800
kV.
[0026] In addition to HV transmission lines, power distribution systems
include
MV power lines and LV power lines. As discussed, MV typically ranges from
about
1000 V to about 100 kV and LV typically ranges from about 100 V to about 240
V.
Transformers are used to convert between the respective voltage portions,
e.g.,
between the HV section and the MV section and between the MV section and the
LV
section. Transformers have a primary side for connection to a first voltage
(e.g., the MV
section) and a secondary side for outputting another (usually lower) voltage
(e.g., the
LV section). Such transformers are often referred to as distribution
transformers or a
step down transformers, because they "step down" the voltage to some lower
voltage.
Transformers, therefore, provide voltage conversion for the power distribution
system.
Thus, power is carried from substation transformer to a distribution
transformer over one
or more MV power lines. Power is carried from the distribution transformer to
the
customer premises via one or more LV power lines.
[0027] In addition, a distribution transformer may function to distribute one,
two,
three, or more phase currents to the customer premises, depending upon the
demands
of the user. In the United States, for example, these local distribution
transformers
typically feed anywhere from one to ten homes, depending upon the
concentration of
the customer premises in a particular area. Distribution transformers may be
pole-top
transformers located on a utility pole, pad-mounted transformers located on
the ground,
or transformers located under ground level.
[0028] One embodiment the present invention communicates data to and from
communication devices at the customer premises via conductive communications
through the LV power lines. In addition, the embodiment may communicate data
signals over the MV power line via surface wave communications.
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[0029] The present invention employs surface waves (otherwise known as
GouBau waves) and conductive communications to communicate data signals over
power lines, and preferably, to provide broadband communications for data,
voice,
video, audio, and telephony. Such transmissions may be Internet protocol
packets in
some embodiments. As discussed, power lines provide a relatively high
impedance to
high frequency conductive transmissions, which means the data signals are
attenuated
over distance. Because higher frequencies correlate to higher data rates,
network
designers have had to make a design choice as to whether to design PLC
networks for
higher data rates or for greater distances. Repeaters have been used to
periodically
repeat data signals resulting in significant costs.
[0030] In contrast, power line surface wave communications do not suffer from
the propagation difficulties associated with power line conductive
transmissions. Thus,
the present invention makes use of surface waves to facilitate high speed
communications over the power lines.
[0031] As shown in Figures 1 and 2, one example embodiment of the present
invention comprises a first communication interface device (CID) 10a that is
in
communication with a first medium voltage transceiver (MVT) 20a. The first MVT
20a is
in communication with a second MVT 20b via surface wave communications over
the
MV power line. The second MVT 20b is in communication with a second CID 10b.
[0032] A CID 10 may include a transceiver and a low voltage interface, which
are in communication with each other. As will be described in more detail
below, a CID
may also include a power supply which receives power from the low voltage
power
lines via the low voltage interface and supplies power to other functional
components of
the CID 10.
[0033] In this example embodiment, the transceivers of the CIDs 10 are 2.4
GHz transceivers and may also be in communication with a directional parabolic
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antenna 11a. The low voltage interfaces of the CIDs 10 may be communicatively
coupled to the low voltage power lines (external) of the customer premises.
While only
two customer premises are depicted in Figure 1, the low voltage interfaces
(LVI) of the
CIDs 10 may be communicatively coupled to a plurality of customer premises
through
numerous (e.g., ten or more) low voltage power lines.
[0034] The CIDs 10 also may include one or more signal conditioning circuits
(e.g., one for the LVI and one for the transceiver) and a controller (e.g., a
processor and
associated programming), which may perform routing, media access control
processing,
measuring low voltage power line voltages (e.g., via an A/D converter),
bandwidth
tiering, user auto provisioning (e.g., assigning and transmitting an address
such as an
IP address), filtering, receive software updates via the power line,
prioritizing certain
types of data (e.g., voice over data) and all those functions performed by the
controller
of the bypass device described in U.S. Appl. No. 10/641,689 entitled "A Power
Line
Communication System and Method of Operating the Same," filed August 14, 2003,
which hereby incorporated in its entirety by reference.
[0035] In this example, the directional parabolic antennas 11 have a three
degree beam with a gain of 23dBi. In essence, the antenna 11 concentrates the
power
output of the transceiver into a very small area.
[0036] The antennas 11 of CIDs 10 are directed towards the antennas 21 of
their associated MVTs 20. In this embodiment, antenna 21 also has a three
degree
beam with a gain of 23dBi. Antenna 21 is communicatively coupled to a wave
communicator 22 via a coaxial cable (or other suitable medium). The wave
communicators 22, which may be a dielectric coated metal cone, are fitted
around the
MV power line. Alternately, the wave communicators may be plastic with metal
embedded therein.
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[0037] MVT 20b includes a first wave communicator 22b and a second wave
communicator 23b, and a directional parabolic antenna 21 b that communicate
with each
other via a length of coaxial cable. Specifically, wave communicator 23b is in
bi-
directional communication with wave communicator 22b and antenna 21 b. The
communication may be accomplished via coaxial cable extending between wave
communicators 22b and 23b with a "T" connector that connects to another
coaxial cable
which also connects to the antenna 21 b. Alternately, a first conductor may
extend
between the first and second wave communicators 22b, and 23b and a second
conductor may extend between the second wave communicator 23b and the antenna
21 b.
[0038] CID 10b may be comprised of substantially the same components, and
operate substantially the same as CID 10a as described above.
[0039] MVT 20c may be comprised of substantially the same components as
MVT 20a.
[0040] Backhaul device 70 is comprised of a directional antenna 71
(substantially similar to antenna 11 ), a controller (substantially similar to
the controller of
CID 10 and operable to perform the functions of the backhaul device of the
reference
incorporated above) and a backhaul transceiver that is communicatively coupled
to a
backhaul link 80 for communications (direct or indirect) with point of
presence, which
provides access to the Internet and/or a voice communications provider.
[0041] Backhaul transceiver may be a fiber optic transceiver and be
communicatively coupled to a fiber optic cable, which may form backhaul link
80 in this
embodiment. Alternately, backhaul transceiver may be a wireless transceiver, a
coaxial
modem, a DSL modem, or other transceiver for communicating through the
available
communications medium. The backhaul device 70 may include a power supply and
be
coupled to a low voltage power line to draw power therefrom, and also, but not
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necessarily, may provide communications to customer premises coupled to those
low
voltage power lines.
[0042] As another alternative backhaul link 80, unidirectional MVT 20c may be
replaced with a bi-directional MVT such as MVT 20b. Thus, the MV power line
may
provide the backhaul link and the backhaul device 70 may transmit data
upstream
through its bi-directional MVT via surface waves. The backhaul upstream data
signals
may be transmitted in the same or a different frequency band (e.g., in the 5
GHz range).
Operation for Downstream Communications
[0043] Data received by the backhaul device 70 via the backhaul link 80 may
be processed and a representative data signal transmitted to the MVT 20c via a
wireless 2.4 GHz transmission from antenna 71, which is received by antenna
21c and
communicated to wave communicator 22c (via the coaxial cable). Wave
communicator
22c communicates the data signal over the MV power line via surface wave
transmissions where the data signal is received by wave communicator 22b of
MVT
20b. Wave communicator 22b converts the surface wave to a conductive
transmission
and conductively communicates the data signal to antenna 21 b via the coaxial
cable.
Antenna 21 b communicates the data signal (via a 2.4 GHz wireless
transmission) for
reception by antenna 11 b of CID 10b. Wave communicator 22b also communicates
the
data signal to wave communicator 22b, which transmits the data signal as a
surface
wave (a 2.4 GHz transmission) over the MV power line for reception by wave
communicator 22a of MVT 20a.
[0044] Similarly, wave communicator 22a of MVT 20a converts the surface
wave to a conductive communication and conductively communicates the data
signal to
antenna 21a. Antenna 21a transmits the data signal (a 2.4 GHz wireless
transmission)
for reception by antenna 11a of CID 10a.
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[0045] When a CID 10 (e.g., 10a or 10b) receives data via its associated
antenna 11, the CID 10 may perform the processing described in the application
incorporated above. Such processing may include, but is not limited to,
demodulating,
decoding, decryption, and routing. If the address of the data matches the
address of a
device on the CID's low voltage subnet, the data may then be transmitted via
the LVI
over the low voltage power lines for reception by the addressed device.
Operation for Upstream Communications
[0046] Data received by CID 10a via the low voltage power line may be
processed (as described in more detail below) and a representative data signal
transmitted to the MVT 20a via a wireless 2.4 GHz transmission from antenna
11a,
which is received by antenna 21a and conductively communicated to wave
communicator 22a (via the coaxial cable).
[0047] Wave communicator 22a communicates the data signal up the MV
power line via surface wave transmissions where it is received by wave
communicator
23b of MVT 20b. Wave communicator 23b converts the surface wave transmission
to a
conductive signal and conductively communicates the data signal to wave
communicator 22b via the coaxial cable. Wave communicator 22b converts the
conductive signal to a surface wave transmission and communicates the data
signal as
surface wave transmission (a 2.4 GHz transmission) up the MV power line for
reception
by wave communicator 22c of MVT 20c.
[0048] Wave communicator 22c communicates the data signal to antenna 21 c
which broadcasts the data signal (a 2.4 GHz wireless transmission) for
reception by
antenna 71 of backhaul device 70. Backhaul device 70 receives the data signal,
processes the data signal (e.g., as described below) and may transmit the data
through
the backhaul link 80 to the destination address.
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[0049] In an alternate embodiment, in whicf,~ antenna 21 b also receives data
signals from wave communicator 23b, the data signal is transmitted to antenna
11 b for
processing by CID 10b. CID 10b, however, does not transmit the data over its
associated low voltage power lines. For example, the data received may be
encrypted
with a different encryption key than the key used by CID 10b, which would
prevent CID
10b from decrypting the data. Such data signals would be discarded.
Alternately, the
router of CID 10b may discard the data after determining that the destination
address of
the data packet does not correspond to a device on its subnet or that the
source
address of the data packet is not that of the backhaul device 70.
[0050] In any of the above embodiments, each CID may be configured to
receive data signals in a different frequency range (frequency division
multiplexing) and,
therefore, each CID 10 may include a band pass filter tuned to a different
band than
other CIDs. Likewise, each CID 10 may be configured to transmit data signals
in a
different frequency range (frequency division multiplexing), with the backhaul
device 70
transmitting and receiving in each of the bands.
MVT
[0051] As will be evident to those skilled in the art from this description,
the
MVTs 20 of this example embodiment are passive devices that do not require an
energy
source. Consequently, the description that includes "broadcasting" or
"transmitting" is
simply meant to convey a direction of communication - either along a power
line or to
an antenna - and do not necessarily require transmitting by adding energy to
the signal.
[0052] The medium voltage power line carries power signals that have a
voltage component in the thousands of volts (greater than one thousand volts
and often
greater than five thousand volts). One challenge to using the MV power lines
as a
communication medium is coupling the data signals to and from the MV power
line,
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while prohibiting the thousand plus volt power signal from being conducted or
in other
words, isolating the power signal of the MV power line.
[0053] As will be evident to those skilled the art, the MVTs described herein
are
electrically isolated from the other components. In other words, the MVTs are
not
electrically connected to any other device that is also not electrically to
the MV power
line (e.g., such as CIDs). Communications between the MVTs and the CIDs is
accomplished via a non-conductive communication link - a wireless link in the
above
example - which provides electrical isolation and permits data communications.
[0054] As an alternate embodiment, the non-conductive communication link
could be a fiber optic link, a laser link, an inductive link (e.g., a
transformer formed by a
winding around toroids around an insulated underground distribution cable
whose
center conductor is coupled to the wave communicator), a capacitive link
(e.g., a
lightning arrestor), or other suitable link that does not normally conduct the
power signal
carried by the MV power line.
[0055] While the above MVT 20 is a passive device, it may desirable to use a
powered MVT, for example, to amplify and transmit the data signals on the MV
power
line or to communicate data through the non-conductive communication medium to
the
CID at greater power. However, a MVT that includes a power supply must derive
power
in a manner that provides isolation of the MV power signal (i.e., does not
provide an
electrical path for voltages on the MV power line). For example, if the MVT
circuit is
disposed adjacent the MV power line, it would be unsafe to simply connect a LV
power
line (and ground) to the MV circuit as the MV power line must be kept in
spaced apart
relation from grounds and the LV power line.
[0056] Thus, the MVT power supply must derive power in a manner that will
provide electrical isolation of the MVT. One manner of providing such power
would be
by employing photocells (solar cells) to derive power from ambient light.
Another would
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be to connect a fiber optic conductor to the MVT photocells and transmit light
energy to
the MVT power supply. Such a power supply is described in U.S. Pat.
No.10/292,745,
entitled "Floating Power Supply and Method of Using the Same," filed November
12,
2002, which is hereby incorporated by reference in its entirety.
[0057] In another embodiment, the power supply may employ magnetically
permeable toroids (perhaps enclosed in hinged casing) that are fastened around
the MV
power line. A winding around the toroids provides a second winding of the
transformer
(the MV power line through the toroids is the first winding) so that power is
inductively
derived from the power signal carried by the MV power line. The device may
include a
battery, or a battery back-up (e.g., for when ambient light is insufficient or
when the
current through the MV power line is too low to provide sufficient inductive
power) which
is recharged periodically (e.g., during the day in the case of a solar powered
MVT or
during peak power usage times in the case of an inductively power supply).
[0058] In another embodiment, the CID supplies power through a wireless
transmission (either using the same or a second set of antennas) such as 2.4
GHz or 5
GHz transmission, which is received and rectified by the amplifying MVT to
amplify the
data signals traversing the MV power line and also to wirelessly transmit the
data
signals to the CID. Such an embodiment is shown in Figure 7.
[0059] In another embodiment, the power supply may receive power
transmitted via a Tesla coil.
Wave Coupler
[0060] As is known in the art, surface waves tend to travel well along a
substantially straight conductor. However, bends can cause signal loss and
sharp turns
in the conductor can cause significant signal loss. Likewise, objects on and
along the
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power line can disrupt the surface wave transmission resulting in signal loss.
One way
of managing such signal attenuators is to bypass them.
[0061] A wave coupler may be comprised a first and second wave
communicator coupled together via a coaxial cable. In essence, the wave
coupler is
comprised of substantially the same components of MVT 20b (in Figure 2), but
does not
employ an antenna 21 b. As shown in Figure 8, a wave coupler allows the
surface wave
transmission to bypass insulators, bends in the MV conductor at the insulator,
and the
distribution transformer connection. The wave coupler may also be used to
bypass a
sharp bend in the power line, a switch, a capacitor bank, and other
attenuators. The
wave coupler may also be used to communicate the data signal down both
branches
(which may require a first wave communicator on the main branch and a wave
communicator on each branch leg coupled to the main branch wave communicator
via
coaxial cable).
[0062] If not used at a juncture, much of the power of the surface wave signal
may tend to travel down the leg that is substantially in alignment with the
main branch
(and not down the other branch legs). So the wave coupler can be used to more
evenly
disseminate the power down the desired branch legs. In addition, the wave
coupler
may be used to couple from one phase conductor to another and to couple from a
phase conductor to a neutral conductor.
Amplifier
[0063] Another system component is the amplifier. Figure 3a illustrates one
example embodiment of an amplifier for a frequency division multiplexing PLC
system.
In this embodiment, upstream data signals are transmitted in a first frequency
band and
downstream data signals are transmitted in a second frequency band. The
amplifier of
Figure 3a includes a first wave communicator 22 that receives the data signal
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provides it to the first Band Pass Filter (BPF1 ) for filtering for tf ie
upstream data signals.
The output of the first BPF1 feeds to an amplifier (AMP1 ) which amplifies the
signal and
feeds the amplified signal to the second wave communicator 23 for transmission
as a
surface wave.
[0064] Similarly, the second wave communicator 23 receives downstream data
signals (in a different frequency band) and provides them to a second band
pass filter
BPF2, which filters for the second frequency band. The output of BPF2 is
supplied to a
second amplifier (AMP2) that supplies the amplified data signal to the first
wave
communicator 22 for transmission as a surface wave.
[0065] The amplifier may designed to receive power in order to amplify the
data signals. As shown in Figure 3a, the power may be transmitted via a
wireless link.
Alternately, the amplifier may include one or more toroids (e.g., in a hinged
enclosure)
that fasten around the MV (or LV) power line. A winding through the toroids
forms a
transformer that inductively draws power from the power line supplying power
to a
power supply to power the device. The amplifier may be powered by any suitable
means that provides the necessary isolation such as those described for the
MVT 20
above.
[0066] Like wave couplers, amplifiers provide a data bypass around
attenuators and therefore may be suitably positioned (although not necessarily
so) at
the places described for the wave couplers (e.g., around bends, at branches,
at
insulators, etc.).
[0067] As shown in Figure 3b, the amplifier itself may be isolated from the MV
power line and receive the signal to be amplified through an isolation
communication
link such as a wireless link. After amplification, the signal is wirelessly
transmitted to the
wave communicators for transmission on the MV power line. In this embodiment,
the
power may be derived from the LV power line. Also, this embodiment may be
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integrated into or form part of a CID 10, for example, in a network in which
the CIDs are
communicatively daisy chained together.
[0068] A pulse repeater may also be used to increase the power of the signal.
A pulse repeater may improve the signal to noise ratio (in contrast to the
amplifier), but
does not require demodulation and remodulation of the data signal.
Regenerator
[0069] A regenerator filters the signal, demodulates the data signal,
modulates
the data (in the same or a different frequency band as the received data
signal) and
then amplifies and transmits the data. Thus, a regenerator may include a first
and
second modem, which also may include one or more additional functional
submodules
such as an Analog-to-Digital Converter (ADC), Digital-to-Analog Converter
(DAC), a
memory, source encoder/decoder, error encoder/decoder, channel
encoder/decoder,
MAC (Media Access Control) controller, encryption module, and decryption
module.
These functional submodules may be omitted in some embodiments, may be
integrated
into a modem integrated circuit (chip or chip set), or may be peripheral to a
modem
chip. The regenerator function may be performed by (or integrated into) a CID
10, or
backhaul device 70, or a stand alone regenerator device. In one embodiment,
the
regenerator receives the data signals to be regenerated via a wireless link
from an MVT
and is powered from a LV power line. The regenerator may be used at locations
in the
system where the signal-to-noise ration (SNR) needs improvement such that
amplification may not suffice to further communicate the signal. .
Antennas
[0070] As discussed, one embodiment of the present invention employs a
wireless link between the MVT 20 and its associated CID 10. This wireless link
may
cause a certain amount of signal loss as the wireless data signal travels
through air. In
order to reduce and mitigate this loss, the described embodiment may employ
spaced
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apart directional antennas that are directed toward each other. Consequently,
the more
accurately the two antennas are aligned, the less the loss of the link.
[0071] Each antenna may be attached to the other via a rigid member such as
a cylinder. Figure 4 illustrates a number of antenna configurations. In Figure
4a, each
antenna 11 and 21 is attached to the other via first and second alignment
braces 111 to
keep the antennas in proper alignment with each other. Additionally, each
antenna
includes a mounting bracket 112 attached thereto to attach the antennas to the
utility
pole or other structure.
[0072] After the antennas are mounted to the utility pole, the alignment
braces
111 may be removed to prevent snow, ice, and water that might come to rest on
the
braces 111 from creating a conductive path between the two antennas. In some
embodiments (or environments), the braces 111 may be designed to prevent a
conductive path from forming and the braces 111 may remain attached after
installation
and during operation.
[0073] Figure 4b illustrates a configuration in which the antennas are coupled
to each other via an enclosure, which in this embodiment is a cylinder 115
that keeps
the antennas in alignment. The cylinder may be metallic or of another
material, which
may reflect RF radiation. Alternately, the cylinder 115 may be designed from
material to
absorb RF radiation, such as a metal or other material coated with an RF
absorbing
material such as Eccosorb TM. These configurations may reduce RF emissions and
allow compliance with FCC regulations at greater transmission power. If the
cylinder
115 conducts electricity (e.g., is a metal or poor insulator), it may be
desirable to
insulate the antennas from the inside of the cylinder, such as using insulator
113.
Alternately, the cylinder 115 may be non-metallic and employed primarily for
alignment
of the antennas.
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[0074] The cylinder may or may not be removed after installation depending on
the environment, isolation requirements, the material of the cylinder, the
design and
purpose of the cylinder, and other factors. If the cylinder or other enclosure
includes an
apex on the top side and/or the configuration is mounted at a 60 degree angle
to
prevent a conductive path from forming between the antennas by water, snow,
and ice,
it may be viable to leave the cylinder in place after installation to keep the
antennas in
alignment.
[0075] Figure 4c illustrates a configuration in which the antennas are
disposed
in a dielectric or metal enclosure shaped to have a substantially square cross
section.
While a dielectric provides a resistance to the passage of electricity, a high
enough
voltage can pierce through a dielectric. To prevent the flow of electricity
through the
dielectric or metal enclosure, the cables entering the enclosure are
surrounded by an
insulator 114. In an alternate embodiment, the antennas also may be insulated
from the
interior of the enclosure via insulators (such as insulator 113 in Figure 4b).
[0076] In each of these embodiments, the cables) may be a conventional
coaxial cable, a coaxial underground residential distribution (URD) power line
cable
(e.g., which may have the outer concentric neutral removed), or other cable.
Additionally, these illustrations are merely schematic representations and
while the
antennas illustrated throughout this description are shown as substantially
conical in
shape, they may be of any shape, size, or configuration desired.
[0077] Also, while the antennas illustrated in the figures are configured
horizontally and vertically, they may be tilted to any angle such as a forty-
five degrees,
sixty degrees, or thirty degree angles, which may to allow debris, rain,
water, snow and
ice to slide off the outer surface of the antenna.
[0078] The disclosed embodiments may employ a 2.4 or 5 GHz wireless link or
a wireless link in another frequency range. For example, the wireless link may
be at a
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frequency band of 30-50 MHz. However, FCC regulations provide more severe
emission restrictions at these frequencies. Consequently, it may be necessary
to
employ an antenna enclosure that reduces RF radiation.
[0079] Figure 5a illustrates one embodiment of such an enclosure. The
enclosure is comprised of a non-metallic container 109, which houses the
antennas 11
and 21. The container 109 is lined with a conductive RF absorbing material
116, which
are well known in the art. The regions around the cables is lined with a non-
conductive
RF absorbing material 117 (such as Eccosorb), which, while more expensive than
the
conductive RF absorbing material, provides electrical isolation between the
cable
entering the enclosure and the surrounding conductive RF absorbing material
116.
Thus, the entire interior of the container 109 is lined with RF absorbing
material.
[0080] An alternative to this embodiment is shown in Figure 5b. in which the
container 109 is conductive (e.g., metallic), and may be externally coated
with an
insulator or plastic. As shown in Figure 5b, the container is grounded.
Additionally, the
aperture through which the cables entering the container 109 pass is fitted
with the non-
conductive RF absorbing material 117 (such as Eccosorb) thereby isolating the
cables
from the metal box. The extraneous RF radiation emitted by the antennas is
absorbed
by the conductive RF absorbing material 116, conducted to the metal container
109 and
grounded (e.g., through a shielded ground conductor). This embodiment may be
further
altered to remove the by the conductive RF absorbing material 116 so that the
metal
box simply conducts the radiation to ground. In any of these embodiments, a
fuse (such
as a cut-out fuse assembly) may be installed serially into the cable (e.g.,
which may be
a URD cable) attached to the MV power line to provide additional safety in
case of a
fault.
[0081] Finally, at the frequencies of this embodiment (the 30-50MHz range),
surface waves may not be practical and the more conventional data signals may
be
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communicated using a power line coupler (as opposed to the above described
wave
communicator) as described in U.S. Pat. No. 10/348,164. entitled "Power Line
Coupling
Device and Method of Using the Same" and filed January 21, 2003, which hereby
incorporated in its entirety by reference.
CID Embodiment
[0082] As shown in Figure 6, the CID 10 may include a low volt interface (LVI)
that includes a low voltage power line coupler, a low voltage signal
conditioner, and a
low voltage modem. Additionally, the CID 10 may include a controller that
includes a
processor and software functioning as a router. A detailed description of
these
components and their operation is described in U.S. Appl. No. 10/641,689
entitled "A
Power Line Communication System and Method of Operating the Same," filed
August
14, 2003, which was incorporated above. In addition, the CID 10 may include a
medium
voltage modem, medium voltage signal conditioner and an antenna, which
cooperate to
communicate over the medium voltage power line (e.g., via surface wave
transmissions).
Upstream Data Flow through CID
LV Modem
[0083] For upstream data traffic the output of the LV signal conditioner 420
is
supplied to the LV modem 450, which includes a modulator and demodulator. The
LV
modem 450 also may include one or more additional functional submodules such
as an
Analog-to-Digital Converter (ADC), Digital-to-Analog Converter (DAC), a
memory,
source encoder/decoder, error encoder/decoder, channel encoder/decoder, MAC
(Media Access Control) controller, encryption module, and decryption module.
These
functional submodules may be omitted in some embodiments, may be integrated
into a
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modem integrated circuit (chip or chip set), or may be peripheral to a modem
chip. In
the present example embodiment, the LV modem 450 is formed, at least in part,
by part
number INT5130, which is an integrated power line transceiver circuit
incorporating
most of the above-identified submodules, and which is manufactured by
Intellon, Inc. of
Ocala, Florida.
[0084] The incoming signal from the LV signal conditioner is supplied to the
ADC to convert the incoming analog signal to a digital signal. The digital
signal is then
demodulated. The LV modem 450 then provides decryption, source decoding, error
decoding, channel decoding, and media access control (MAC) all of which are
known in
the art and, therefore, not explained in detail here.
[0085] With respect to MAC, however, the LV modem 450 may examine
information in the packet to determine whether the packet should be ignored or
passed
to the router 310. For example, the modem 450 may compare the destination MAC
address of the packet with the MAC address of the LV modem 450 (which is
stored in
the memory of the LV modem 450). If there is a match, the LV modem 450 removes
the MAC header of the packet and passes the packet to the router 310. If there
is not a
match, the packet may be ignored.
[0086] For downstream data flow, the data is received from the router 310. The
LV modem 450 then provides MAC processing, which may comprise adding a MAC
header that includes the source MAC address (which may be the MAC address of
the
LV modem 450) and the destination MAC address (which may be the MAC address of
the PLM corresponding to the user device identified by the destination IP
address of the
packet).
[0087] To determine the MAC address of the PLM that provides
communications for the user device identified by the destination IP address of
the
packet, the LV modem 450 first determines if the destination IP address of the
packet is
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an IP address stored in its memory (e.g., stored in its bridging table). If
the IP address
is stored in memory, the LV modem 450 retrieves the MAC address for
communicating
with the destination IP address (e. g., the MAC address of the PLM 50) from
memory,
which will also be stored therein. If the IP address is not stored in memory,
the LV
modem 450 transmits a request to all the devices to which it is coupled via
the low
voltage power line (e.g., all the PLIDs). The request is a request for the MAC
address
for communicating with the destination IP address of the packet. The device
(e.g., the
PLM) that has the MAC address for communicating with the destination IP
address will
respond by providing its MAC address. The LV modem 450 stores the received MAC
address and the IP address for which the MAC address provides communications
in its
memory (e.g., in its bridging table). The LV modem 450 then adds the received
MAC
address as the destination MAC address for the packet.
[0088] The packet is then channel encoded, source encoded, error encoded,
and encrypted. The data is then modulated and provided to the DAC to convert
the
digital data to an analog signal
Router
[0089] In the upstream direction of data flow, the data packet from the LV
modem 450 may be supplied to the router 310, which forms part of the
controller 300.
The router 310 performs prioritization, filtering, packet routing, access
control, and
encryption. The router 310 of this example embodiment of the present invention
uses a
table (e.g., a routing table) and programmed routing rules stored in memory to
determine the next destination of a data packet. The table is a collection of
information
and may include information relating to which interface (e.g., LVI or MVI)
leads to
particular groups of addresses (such as the addresses of the user devices
connected to
the customer LV power lines), priorities for connections to be used, and rules
for
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handling both routine and special cases of traffic (such as voice packets
and/or control
packets).
[0090] The router 310 will detect routing information, such as the destination
address (e.g., the destination IP address) and/or other packet information
(such as
information identifying the packet as voice data), and match that routing
information with
rules (e.g., address rules) in the table. The rules may indicate that packets
in a
particular group of addresses should be transmitted in a specific direction
such as
through the LV power line (e.g., if the packet was received from the MV power
line and
the destination IP address corresponds to a user device connected to the LV
power
line), repeated on the MV line (e.g., if the CID 10 is acting as a
regenerator), or be
ignored (e. g., if the address does not correspond to a user device connected
to the LV
power line or to the CID 10 itself).
[0091] As an example, the table may include information such as the IP
addresses (and potentially the MAC addresses) of the user devices on the CID's
LV
subnet, the MAC addresses of the power line modems on the CID's LV subnet, the
MV
subnet mask (which may include the MAC address and/or IP address of the CID's
backhaul device), and the IP address of the LV modem 450 and MV modem 280.
Based on the destination IP address of the packet (e.g., an IP address), the
router may
pass the packet to the MV modem 280 for transmission on the MV power line.
Alternately, if the IP destination address of the packet matches the IP
address of the
CID 10, the CID 10 may process the packet as a request for data or a command.
[0092] In other instances, such as if the user device is not provisioned and
registered, the router may prevent packets from being transmitted to any
destination
other than a DNS server or registration server. In addition, if the user
device is not
registered, the router 310 may replace any request for a web page received
from that
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user device with a request for a web page on the registration server (the
address of
which is stored in the memory of the router).
[0093] The router 310 may also prioritize transmission of packets. For
example, data packets determined to be voice packets may be given higher
priority for
transmission through the CID than data packets so as to reduce delays and
improve the
voice connection experienced by the user. Routing and/or prioritization may be
based
on IP addresses, MAC addresses, subscription level, or a combination thereof
(e.g., the
MAC address of the power line modem or IP address of the user device).
MV Modem
[0094] Similar to the LV modem 450, for upstream data flow the MV modem
280 receives data from the router 310 and includes a modulator and
demodulator. In
addition, the MV modem 280 also may include one or more additional functional
submodules such as an ADC, DAC, memory, source encoder/decoder, error
encoder/decoder, channel encoder/decoder, MAC controller, encryption module,
and
decryption module. These functional submodules may be omitted in some
embodiments, may be integrated into a modem integrated circuit (chip or chip
set), or
may be peripheral to a modem chip. In the present example embodiment, the MV
modem 280 is formed of an integrated modem transceiver circuit incorporating
most of
the identified submodules. In this embodiment, them modem modulates a 2.4 GHz
carrier band, but in alternate embodiment could use a 5 GHz carrier band.
[0095] The incoming signal from the router 310 (or controller) is supplied to
the
MV modem 280, which provides MAC processing, for example, by adding a MAC
header that includes the MAC address of the MV modem 280 as the source address
and the MAC address of the backhaul device 70 (and in particular, the MAC
address of
the MV modem of the backhaul device) as the destination MAC address. In
addition,
the MV modem 280 also provides channel encoding, source encoding, error
encoding,
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and encryption. The data is then modulated and provided to the DAC to convert
the
digital data to an analog signal.
First MV Signal Conditioner
[0096] The modulated analog signal from MV modem 280 is provided to the
MV signal conditioner 260, which may provide filtering (anti-alias, noise,
and/or band
pass filtering) and amplification. In addition, in other embodiments the MV
signal
conditioner 260 may provide frequency translation. Methods of frequency
translation
are well known in the art and, therefore, not described in detail. The output
of the MV
Signal conditioner is supplied to the antenna 11 for wireless transmission to
the MVT
20.
Downstream Data Flow throucth CID
MV Modem
[0097] In the downstream data flow, upon reception of a data packet, the MV
modem 280 of the CID 10 will determine if the destination MAC address of the
packet
matches the MAC address of the MV modem 280 and, if there is a match, the
packet is
passed to the router 310. If there is no match, the packet is discarded.
Router
[0098] In this embodiment, the router 310 analyzes packets having a
destination IP address to determine the destination of the packet which may be
a user
device or the CID 10 itself. This analysis includes comparing the information
in the
packet (e.g., a destination IP address) with information stored in memory,
which may
include the IP addresses of the user devices on the CID 10 LV subnet. If a
match is
found, the router 310 routes the packet through to the LV modem 450 for
transmission
on the LV power line. !f the destination IP address matches the IP address of
the CID
10, the packet is processed as a command or data intended for the CID 10
(e.g., by the
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Command Processing software described below) and may not be passed to the LV
modem 450.
[0099] The term "router" is sometimes used to refer to a device that routes
data
at the IP layer (e.g., using IP addresses). The term "switch" is sometimes
used to refer
to a device that routes at the MAC layer (e.g., using MAC addresses). Herein,
however,
the terms "router", "routing", "routing functions" and the like are meant to
include both
routing at the IP layer and MAC layer. Consequently, the router 310 of the
present
invention may use MAC addresses instead of, or in addition to, IP addresses to
perform
routing functions.
[0100] For many networks, the MAC address of a network device will be
different from the IP address. Transmission Control Protocol (TCP)/IP includes
a facility
referred to as the Address Resolution Protocol (ARP) that permits the creation
of a table
that maps IP addresses to MAC addresses. The table is sometimes referred to as
the
ARP cache. Thus, the router 310 may use the ARP cache or other information
stored in
memory to determine IP addresses based on MAC addresses (and/or vice versa).
In
other words, the ARP cache and/or other information may be used with
information in
the data packet (such as the destination IP address) to determine the routing
of a
packet (e.g., to determine the MAC address of the power line modem
communicating
with the user device having the destination IP address).
[0101] In an alternate embodiment using IP address to route data packets, all
packets received by the MV modem 280 may be supplied to the router 310. The
router
310 may determine whether the packet includes a destination IP address that
corresponds to a device on the CID's LV subnet (e.g., an address corresponding
to a
user device address or the CID's address). Specifically, upon determining the
destination IP address of an incoming packet, the router 310 may compare the
identified
destination address with the addresses of the devices on the subnet, which are
stored
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in memory. If there is a match between the destination address and the IP
address of a
user device stored in memory, the data is routed to the LV power line for
transmission to
the user device. If there is a match between the destination address and the
IP address
of the CID 10 stored in memory, the data packet is processed as a command or
information destined for the CID 10.
[0102] In addition, the router 310 may also compare the destination address
with the IP address of the backhaul device, other CIDs, or repeaters (for
example, if the
CID is also acting as a repeater). If there is no match between the
destination address
and an IP address stored in memory, the packet is discarded (ignored).
[0103] According to any of these router embodiments, if the data is addressed
to an address on the CID's LV or MV subnet (the network of devices with which
the CID
can communicate and/or for which the CID has an address (MAC or IP) stored
therein),
the router may perform any or all of prioritization, packet routing, access
control,
filtering, and encryption.
[0104] As discussed, the router 310 of this example embodiment of the present
invention may use a routing table to determine the destination of a data
packet. Based
on information in the routing table and possibly elsewhere in memory, the
router 310
routes the packets. For example, voice packets may be given higher priority
than data
packets so as to reduce delays and improve the voice connection experienced by
the
user. The router 310 supplies data packets intended for transmission along the
LV
power line to the LV modem 450.
Software
[0105] The PLCS also may include a power line server (PLS) that is a
computer system with memory for storing a database of information about the
PLCS
and includes a network element manager (NEM) that monitors and controls the
PLCS.
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The PLS allows network operations personnel to provision users and network
equipment (e.g., CIDs), manage customer data, and monitor system status,
performance and usage. The PLS may reside at a remote operations center to
oversee
a group of communication devices via the Internet. The PLS may provide an
Internet
identity to the network devices by assigning the devices (e. g., user devices,
CIDs 10,
(e.g., the LV modems and MV modems of CIDs), repeaters/regeneragtors, backhaul
devices, and AP) an IP address and storing the IP address and other device
identifying
information (e.g., the device's location, address, serial number, etc.) in its
memory. In
addition, the PLS may approve or deny user devices authorization requests,
command
status reports and measurements from the CIDs, repeaters, and backhaul
devices, and
provide application software upgrades to the communication devices (e.g.,
CIDs,
backhaul devices, repeaters, and other devices). The PLS, by collecting
electric power
distribution information and interfacing with utilities' back-end computer
systems may
provide enhanced distribution services such as automated meter reading, outage
detection, load balancing, distribution automation, Volt/Volt-Amp Reactance
(Volt/VAr)
management, and other similar functions. The PLS also may be connected to one
or
more APs and/or core routers directly or through the Internet and therefore
can
communicate with any of the CIDs, repeaters, user devices, and backhaul
devices
through the respective AP and/or core router.
PLS Command Processing Software
[0106] The PLS and CID 100 (or CID also acting as a regenerator) may
communicate with each other through two types of communications: 1 ) PLS
Commands
and CID responses, and 2) CID Alerts and Alarms. TCP packets are used to
communicate commands and responses. The commands typically are initiated by
the
NEM portion of the PLS. Responses sent by the CID 10 (or repeater) may be in
the
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form of an acknowledgement (ACK) or negative acknowledgement (NACK), or a data
response depending on the type of command received by the CID (or repeater).
Commands
[0107] The PLS may transmit any number of commands to the CID 10 to
support system control of CID functionality. As will be evident to those
skilled in the art,
most of these commands are equally applicable for repeaters. For ease of
discussion,
however, the description of the commands will be in the context of a CID only.
These
commands may include altering configuration information, synchronizing the
time of the
CID 10 with that of the PLS, controlling measurement intervals (e.g., voltage
measurements of an ADC in the CID that is electrically connected to the LV
power line),
requesting measurement or data statistics, requesting the status of user
device
activations, and requesting reset or other system-level commands. Any or all
of these
commands may require a unique response from the CID 10, which is transmitted
by the
CID 10 (or repeater) and received and stored by the PLS.
Alerts
[0108] In addition to commands and responses, the CID 10 (or repeater) has
the ability to send Alerts and Alarms to the PLS (the NEM) via User Datagram
Protocol
(UDP), which does not require an established connection but also does not
guarantee
message delivery.
[0109] Alerts typically are either warnings or informational messages
transmitted to the NEM in light of events detected or measured by the CID 10.
Alarms
typically are error conditions detected by the CID 10. Due to the fact that
UDP
messages may not be guaranteed to be delivered to the PLS, the CID 10 may
repeat
Alarms and/or Alerts that are critically important to the operation of the
device.
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[0110] One example of an Alarm is an Out-of-Limit Alarm that indicates that an
out-of-limit condition and has been detected at the CID 10, which may indicate
a power
outage on the LV power line, a temperature measurement inside the CID 10 is
too high,
and/or other out-of-limit condition. Information of the Out-of-Limit
condition, such as the
type of condition (e.g., a LV voltage measurement, a CID temperature), the Out-
of-Limit
threshold exceeded, the time of detection, the amount (e.g., over, under,
etc.) the out of
limit threshold has been exceeded, is stored in the memory of the CID 10 and
may be
retrieved by the PLS.
Software Upgrade Handler
[0111] The Software Upgrade Handler software may be started by the PLS
Command Processing software in response to a PLS command. Information needed
to
download the upgrade, including for example the remote file name and PLS IP
address,
may be included in the parameters passed to this software module (or task)
from the
Software Command Handler.
[0112] Upon startup, this task may open a file transfer program such as
Trivial
File Transfer Protocol (TFTP) to provide a connection to the PLS and request
the file.
The requested file is then downloaded to the CID 10. For example, the PLS may
transmit the upgrade through the Internet, through the backhaul device 70,
through the
MV power line to the CID where the upgrade may be stored in a local RAM buffer
and
validated (e.g., error checked) while the CID 10 continues to operate (i.e.,
continues to
communicate packets to and from PLMs and the backhaul device 70). Finally, the
task
copies the downloaded software into a backup boot page, and transmits an Alert
indicating successful installation to the PLS. A separate command transmitted
from the
PLS, processed by the Command Processing software of the CID 10, may make the
newly downloaded and validated program code the primary software operating the
CID
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10. If an error occurs, the CID 10 issues an Alert indicating the download was
not
successful.
ADC Scheduler
[0113] The ADC Scheduler software, in conjunction with the real-time operating
system, creates ADC scheduler tasks to perform ADC sampling according to
configurable periods for each sample type. Each sample type corresponds with
an ADC
channel. The ADC Scheduler software creates a scheduling table in memory with
entries for each sampling channel according to default configurations or
commands
received from the PLS. The table contains timer intervals for the next sample
for each
ADC channel, which are monitored by the ADC scheduler.
ADC Measurement Software
[0114] The ADC Measurement Software, in conjunction with the real-time
operating system, creates ADC measurement tasks that are responsible for
monitoring
and measuring data accessible through the ADC. Each separate measurable
parameter may have an ADC measurement task. Each ADC measurement task may
have configurable rates for processing, recording, and reporting for example.
[0115] An ADC measurement task may wait on a timer (set by the ADC
scheduler). When the timer expires the task may retrieve all new ADC samples
for that
measurement type from the sample buffer, which may be one or more samples. The
raw samples are converted into a measurement value. The measurement is given
the
timestamp of the last ADC sample used to make the measurement. The measurement
may require further processing. If the measurement (or processed measurement)
exceeds limit values, an alarm condition may be generated. Out of limit Alarms
may be
transmitted to the PLS and repeated at the report rate until the measurement
is back
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within limits. An out of limit recovery Alert may be generated (and
transmitted to the
PLS) when the out of limit condition is cleared (i.e., the measured value
falls back within
limit conditions).
[0116] The measurements performed by the ADC, each of which has a
corresponding ADC measurement task, may include CID inside temperature, LV
power
line voltage, and LV power line current (e.g., the voltage across a resistor)
for example.
[0117] As discussed, the CID 10 includes value limits for most of these
measurements stored in memory with which the measured value may be compared.
If
a measurement is below a lower limit or above an upper limit (or otherwise out
of an
acceptable range), the CID may transmit an Out-of-Limit Alarm, which is
received and
stored by the PLS. In some instances, one or more measured values are
processed to
convert the measured values) to a standard or more conventional data value.
[0118] The measured data (or measured and processed data) is stored in the
memory of the CID. This memory area contains a circular buffer for each ADC
measurement and time stamp. The buffers may be read by the PLS Command
Processing software task in response to a request for a measurement report.
The
measurement data may be backed up to flash memory by the flash store task.
[0119] The LV power line voltage measurement may be used to provide
various information. For example, the measurement may be used to determine a
power
outage, or measure the power used by a consumer or by all of the consumers
connected to that distribution transformer. In addition, it may be used to
determine the
power quality of the LV power line by measuring and processing the measured
values
over time to provide frequency, harmonic content, and other power line quality
characteristics.
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Traffic Monitoring Software
[0120] The Traffic Monitoring software may collect various data packet traffic
statistics, which may be stored in memory including the amount of data (i.e.,
packets
and/or bytes) communicated (i.e., transmitted and received) through the MV
power line,
and/or through the LV power line; the amount of data (packets and/or bytes)
communicated (transmitted and received) to and/or from the PLS; the number of
Alerts
and Alarms sent to the PLS; the number of DHCP requests from user devices; the
number of failed user device authentications; the number of failed PLS
authentications;
and the number of packets and bytes received and/or transmitted from/to each
user
device (or PLM).
Data Filtering Software
[0121] The Data Filtering software provides filtering of data packets
transmitted
to and/or from a user device (or PLM). The filtering criteria may be supplied
from the
PLS (which may be based on requests received from the user) and is stored in
memory
of the CID 10 and may form part of the routing table. The Data Filtering
software may
analyze the data packets and may prevent the transmission of data packets
through the
CID) that are transmitted to the user device from a particular source (e.g.,
from a
particular person, user, domain name, email address, or IP or MAC source
address); 2)
that are transmitted from the user device to a particular destination (e.g.,
to a particular
person, email address, user, domain name, or IP or MAC destination address);
3) that
have particular content (e.g., voice data or video data); 4) based on the time
of
transmission or reception (e.g., times of the day and/or days of the week); 5)
that
surpass a threshold quantity of data (either transmitted, received, or
combination
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thereof) for a predetermined window of time (e.g., a day, week, month, year,
or
subscription period); or 7) some combination thereof.
Auto-Provision and Activation of Network Components
[0122] "Auto-Provisioning" is the term used that may be used to refer to the
steps performed to get a new network element (e.g., a CID 10, repeater, or
backhaul
device) onto the PLCS network. While skilled in working with power lines,
personnel
installing the CIDs (linemen) often have little or no experience in working
with
communication networks. Consequently, it is desirable to have a system that
permits
easy installation of the CIDs without the need to perform network
configuration or other
network installation procedures.
(0123] In the present example embodiment, each network element includes a
unique identifier, which may be a serial number. In this embodiment, the
enclosure of
the CID 10 has a barcode that the installer scans to record the serial number.
The
installer also records the location of the installed device. This information
(the
identifying information and location) is provided to a network administrator
to input the
information into the PLS. Alternately, the installer may wirelessly transmit
the
information to the PLS for reception and storage by the PLS.
(0124] In one example embodiment, after being physically installed and
powered up, the CID transmits a request, such as a dynamic host configuration
protocol
(DHCP) request, to the backhaul device with whom the communication device is
physically or functionally connected. In response to the request, the BD
assigns and
transmits an IP address to the MV interface (i.e., assigns an IP address to be
used to
communicate with the MV modem 280), and the MV subnet mask. In addition, the
BD
transmits the IP address of the BD 70 to be used as the CID's network gateway
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address, and the IP address for the PLS. The CID 10 receives the information
from the
BD and stores it in its non-volatile memory.
[0125] The CID 10 then transmits an Alive Alert to the PLS (using the IP
address received in response to the DHCP request) indicating that the CID is
running
and connected to the network. The Alive Alert may include information
identifying the
CID, network configurations of the CID (e.g., MAC addresses of the LV modem
450 and
MV modem 280), the IP address of the MV Interface (i.e., the IP address
assigned to
the MV modem 280 received from the BD 70) and MV subnet mask for use by the
communication device's backhaul interface (much of which was received from the
BD
70). This information is stored by the PLS in the network elements database.
[0126] In response, the PLS may activate the CID 10 by assigning and
transmitting the CID 10 a LV subnet mask and a LV Interface IP address (i.e.,
the IP
address used to communicate with the LV modem 450). If there are customers
present
on the LV subnet, the PLS will transmit customer information to the CID 10,
which may
include such information as data filtering information, keys (e.g., encryption
keys), user
device IP addresses, and subscription levels for the various users and/or user
devices.
In addition, the PLS may configure the CID by transmitting DNS addresses
(e.g., a first
and second DNS address), and a registration server IP address. This
information is
stored by the PLS (in the network elements database) and the CID 10. As
discussed
below, until a user device is registered, the CID 10 may be programmed to
allow the
user device to access only the domain name servers and registration server.
Provisioning a New User Device
(0127] Similarly, when a user installs a new user device on the LV subnet
attached to the CID 10, the user device may need to be provisioned to identify
itself on
the network. To do so in this embodiment, the new user device transmits a DHCP
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request, which is received and routed by the CID 10 to a DHCP server running
in the
controller 300 of the CID 10. In response to the request, the CID 10 may
respond by
transmitting to the user device the IP address and subnet mask for the user
device, the
gateway IP address for the device's network interface to be used as the
network
gateway (e.g., the IP address of the LV modem 450 of the CID 10), and the IP
addresses of the Domain Name Servers (DNS) all of which are stored in memory
by the
user device. In addition, the CID may transmit a new user device Alert to the
PLS.
[0128] After provisioning, it may be necessary to register the user device
with
the network, which may require providing user information (e.g., name,
address, phone
number, etc.), payment information (e.g., credit card information or power
utility account
information), and/or other information to the registration server. The
registration server
may correlate this information with information of the utility company or
Internet service
provider. The registration server may form part of, or be separate from, the
PLS. Until
registered, the CID 10 prevents the user device (through its PLM) from
communicating
with (receiving data from or transmitting data to) any computer other than the
registration server or the two DNSs. Thus, until the user device is
registered, the CID
may filter data packets transmitted to and/or from the user device that are
not from or
to the registration server or a DNS. In addition, requests (such as HTTP
requests) for
other Internet web pages may be redirected and transmitted as a request for
the
registration web page on the registration server, which responds by
transmitting the
registration web page. Control of access of the user device may be performed
by
limiting access based on the IP address of the user device to the IP addresses
of the
registration server and DNSs.
[0129] After registration is successfully completed, the registration server
communicates with the PLS to provide registration information of the user
device to the
PLS. The PLS transmits an activation message for the user device (or PLM) to
the BD.
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In response, the CID 10 removes communication restrictions and permits the
user
device (and PLM) to communicate through the PLCS to all parts of the Internet.
As will
be evident to those skilled in the art, filtering of data and controlling
access of the user
device may be performed by limiting access based on the IP address of the user
device
(or depending on the network communication protocol, the MAC address of the
user
device) or the MAC address of the PLM to which the user device is connected.
Thus,
the CID 10 may compare the source IP address (or MAC address) with information
in its
memory to determine if the IP address (or MAC address) is an address that has
been
granted access to the PLCS. If the source address is not an address that has
been
granted access to the PLCS (e.g., by registering, which results in an
activation message
from the PLS to the CID 10), the CID 10 may replace the destination IP address
of the
packet with the IP address of the registration server and transmit the packet
to the
backhaul device. The procedure above, or portions of the procedure, with
respect to
provisioning user devices may be used to provision a PLID instead of or in
addition to a
user device.
Backhaul Device
[0130] As discussed, the present invention also may employ a backhaul device
70. The backhaul device 70 may comprise a controller, a MV interface, and a
network
interface. Thus, the MV interface of the device would be much the same as that
described in the context of the CID 100 and may include an antenna, a MV
signal
conditioner, and a MV modem.
[0131] The controller may include a router coupled to the network interface.
The network interface may include a network modem, a signal conditioner
adapted to
condition signals for communication through the network connected to the
backhaul
device, which may be a wired connection. In addition to or instead of a wired
connection, the backhaul device 70 may include a transceiver such as a
wireless
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transceiver for communicating with the AP wirelessly (e.g., an 802.11 wireless
link) or a
fiber optic transceiver for communicating with the AP via a fiber optic cable.
In addition,
the controller of this embodiment may include substantially the same software
and
functionality as that described with respect to the CID 100 and modifications
thereto
would be readily apparent to one skilled in the art. Specifically, the
backhaul device
may include substantially the same functionality with respect to monitoring
data, taking
measurements (e.g., temperature measurement), receiving and invoking software
upgrades, transmitting data to the PLS, processing PLS commands (e.g.,
resets), and
transmitting Alerts and Alarms.
Alternate Embodiments
[0132] As discussed, the CID 10 of the above embodiment communicates data
signals to user devices via the LV power line. Rather than communicating data
signals
to the PLM and/or user devices via the LV power line, the CID 10 may use
another
communication medium. For example, the CID may convert the data signals to a
format
for communication via a telephone line, fiber optic, cable, or coaxial cable
line. Such
communication may be implemented in a similar fashion to the communication
with LV
power line as would be well known to those skilled in the art.
[0133] In addition, the CID (or MVT) may convert the data signal to radio
signals for communication over a wireless communication link to the user
device at the
customer premises. In this case, user device may be coupled to a radio
transceiver for
communicating through the wireless communication link. The wireless
communication
link may be a wireless local area network implementing a network protocol in
accordance with an IEEE 802.11 (e.g., a, b, or g) standard.
[0134] Alternatively, the CID 10 may communicate with the user device via a
fiber optic link. In this alternative embodiment, the CID 10 may convert the
data signals
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to light signals for communication over the fiber optic link. In this
embodiment, the
customer premises may have a fiber optic cable for carrying data signals,
rather than
using the internal wiring of customer premise.
[0135] In an alternate embodiment of the BD 70, the BD 70 may be
communicatively coupled to a plurality of MV power lines. For example, the BD
70 may
be installed at a location where the MV power lines intersect in a "T". This
alternate
embodiment may include three MV interfaces with each having its own antenna
and
MVT. Each MV antenna may be communicatively coupled to one of the branches.
[0136] In addition and as discussed above, the BD 70 may have a wireless
transceiver for providing a wireless link to the AP (or distribution point as
the case may
be) and be a wireless BD. The wireless link to the AP (or distribution point)
may be a
direct wireless link or may include a wireless repeater in the link between
the BD and
the upstream device. The wireless repeater may be wirelessly coupled to the AP
(or
distribution point), although the communication link could also be a wired
link or fiber
optic link as desired.
[0137] In addition, the BD 70, in some instances, may also act as a CID 10
serving those customer premises that receive power from the distribution
transformer to
which the BD 70 is coupled. Thus, a BD 70 may act as a backhaul device to the
other
CIDs that are communicatively coupled to the MV power line. However, this BD
70 also
is perceived as a CID 10 to the user devices of the LV power lines to which
the BD is
communicatively coupled. Likewise, a wired BD 70 (that communicates upstream
via
fiber, coaxial cable, or via another wired means) also may service customers
via the LV
power lines (or wirelessly). In addition, a wireless repeater upstream from
the BD 70
may have a wired (or fiber optic) link to the AP (or DP) instead of a wireless
link and
communicate with only the BD wirelessly.
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[0138] Figure 9 illustrates an alternate embodiment of a MVT that includes
additional wave communicators. Specifically, this MVT provides communications
on
multiple conductors, which may be communicated in different frequency bands.
While
not shown there may be a band pass filter at each wave communicator to permit
the
passage only of the designated communications (e.g., frequencies) and thereby
conserve power. Such filters would prevent an upstream transmission received
at wave
communicator 24 from being transmitted down the conductor via wave
communicator
22. The filters may alternately be disposed in a housing through which
communications
of all the wave communicators pass.
[0139] Also, while the MVT 20 of Figure 9 is passive, an alternate embodiment
could include a power supply (e.g., supplied power from CID 10 via RF
transmissions)
for amplifying and/or processing (e.g., routing, demodulating/modulating,
etc.)
communications through the MVT 20.
[0140] Figure 10 illustrates another embodiment of an MVT and a CID 10. The
MVT 30 is comprised of two wave communicators 22, 23, with each being coupled
to an
antenna 21, 26. The CID 10 in this embodiment includes two antennas 11 and 17.
[0141] Communications upstream to the CID 10 (from the left in Figure 10)
traverse through wave communicator 22, the coaxial cable, antenna 21, and
antenna 11
to the CID 10. Communications from upstream to the CID 10 (from the right in
Figure
10) traverse through wave communicator 23, the coaxial cable, antenna 26, and
antenna 17 to the CID 10. In this embodiment, the CID 10 may include an
amplifier or
repeater therein to regenerate the data signals (e.g., in the same or
different frequency
band) for further communications along the MV power line.
Network Topologies
[0142] In one embodiment of the present invention, the CIDs may act as
regenerators to regenerate the signals for reception by a nearby or the next
CID along
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the MV power line (e.g., a daisy chain configuration). Such as design may be
well
suited to electrical distribution topologies that have numerous attenuators.
In another
embodiment, one or more amplifiers and/or wave couplers are disposed between
regenerators (which may formed by a CIDs). Thus, the regeneration of the data
signals
increases the signal to noise ratio.
[0143] One backhaul device 70 may communicate over numerous sets of MV
power lines to numerous CIDs 10 on each set of MV power lines. Thus, the
communications may be point-to-multipoint or daisy chained.
[0144] In order to reduce the cost of the network, it is desirable to minimize
the
number of network elements, such as amplifiers, repeaters, regenerators, which
may be
required when attenuation of the data signal along the transmission path
becomes too
great and/or the SNR becomes to low.
[0145] Depending on the frequency of transmitted data signals, the distance
between the overhead conductors, the size of the conductors, and other facts,
the data
signals may couple from one phase conductor to another through the ambient
air.
While there will be some associated loss with such coupling, the network
designer can
use this coupling effect in designing the network. Thus, the system can be
designed to
transmit data signals on one conductor and to receive them on one or more
other
conductors and vice versa.
(0146] As will be evident to those skilled in the art, each device on the MV
power line - such as the wave communicators - may result in a through loss.
And as
discussed above, in order to reduce the cost of the network, it is desirable
to minimize
the number of amplifiers and repeaters. One topology reducing such costs is
shown in
Figure 11 in which data signals transmitted by wave communicator 22a on phase
B
coupled through air to phase A and phase C and are received by wave
communicators
22b and 23c, respectively.
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[0147] Additionally, the data signals are received by wave communicator 23d,
which is also on phase B. Because wave communicators 22b and 23c are not on
phase
B, they do not attenuate data signals between wave communicators 22a and 23d
and
therefore do not increase the likelihood that a amplifier or regenerator may
be
necessary.
[0148] Figure 12 is a schematic representation of an example of a network
topology employing the present invention. The squares shown in Figure 12
represent
backhaul devices 70 and the circles represent CIDs 10. While not shown in the
figure,
each CID and each backhaul device also has an associated MVT that allows the
device
to couple data to and from the MV power line for surface wave communications
thereon.
[0149] In this embodiment, the CIDs and their respective backhaul device can
be logically divided into Groups A, B, and C. The CIDs communicate only with
their
own backhaul device 70. Said communications may be direct or through
amplifiers,
regenerators, and/or other CIDs (e.g., either point to point or daisy
chained). It may
desirable to provide isolation between the groups so that a CID of Group A
does cannot
communicate with the backhaul device or CIDs of Group B. Consequently, a first
group
(e.g., Groups A and C) may communicate using a first frequency band (e.g., 2.4
GHz)
that is different from a second frequency band (e.g., 5 GHz) used by an
adjacent group
(e.g., Group B). Alternately, adjacent groups could use different or unique
encryption
keys to prevent unintended network devices from receiving the data.
[0150] In this embodiment, the backhaul devices are daisy chained together
and communicate over phase A, which has fewer CIDs 10 installed. Other
embodiments, may communicate over a phase that has no CIDs, that has some CIDs
that regenerate or amplify the backhaul link data, and may use the neutral
conductor as
the backhaul link.
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[0151] Other conductors may also be used to transmit surface waves such as
high voltage transmission lines which often travel very straight for long
distances. In
addition to the above alternate embodiments, the neutral conductor (e.g., the
neutral of
a MV or HV power line) may used to transmit surface waves. Transmitting over a
neutral alleviates the need to provide isolation between the MVT and the CID.
Specifically, the CID 10 may be directly coupled to the MVT via a coaxial
cable
alleviating the need of the antennas 11 and 21. Thus, the CID may be
communicatively
coupled to first and second wave communicators (that are directed in opposite
directions along the conductor) through separate coaxial cables or via a
signal cable
and T connector that connects both wave communicators. Other conductors, such
as
twisted pair may also be used to communicate the surface waves (e.g., to
supply the
backhaul link).
[0152] In some instances, it may be desirable to include an isolator on the
power line between the two wave communicators to prevent data signals intended
for
one wave communicator from propagating further along the power line to a
second
wave communicator. Such an isolator may take the form of a substantially
circular
material (perhaps conductive) that is sized proportional to the wavelength of
the carrier
frequency (e.g., having a radius at least 1/8, '/4, 1/3, or'/z of the largest
wavelength).
[0153] In addition, the CIDs and/or backhaul devices may include system
network management protocol (SNMP) capabilities. Also, an overhead power line
may
be used to communicate surface waves as described herein which is converted to
conductive communications for communications through URD power lines (e.g., at
a
tap). Thus, the overhead surface wave signals may be converted to a conductive
signals for communication over the URD power line at the pole riser (or over a
coaxial
cable extending up the pole) to the network element at the first URD
transformer.
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[0154] While the above embodiments employ a conically shaped wave
communicator, any suitable device for receiving and transmitting surface waves
may be
employed. Throughout this description, the terms "repeater" and "regenerator"
are both
intended to refer the same type of devices. Where wireless links are discussed
herein,
such as between a CID and MVT, as the backhaul link, and to the customer
premises
(e.g., a home or business), any suitable wireless link may be employed
including, but
not limited to, 802.11 a, b, or g, or 802.16.
[0155] Also, the CID may communicate with the customer premises via a
conductor (such as a coaxial cable) using an 802.11 communication. Also, the
CID 10
may employ a separate modem for upstream and downstream communications or use
a
single modem for each. In addition, instead of communicating with the CID, the
MVT
may communicate directly with the customer premises device via a directional
antenna
disposed at the customer premises. Preferably, this embodiment may employ a
powered MVT.
[0156] As is known in the art, surface waves generally adhere to conductors
better that have a dielectric coating than those that do not. However,
overhead power
lines typically are not insulated and are not manufactured with a dielectric
coating. In
order to increase the "adhesion" of the surface wave around a bend, at the
apex of the
wire at a utility pole, at an insulator, or at another attenuator, the
conductor may be
coated with a dielectric. The dielectric may be applied via a compressed (or
aerosol)
spray or via an adhesive (e.g. as in insulating tape). In addition, depending
on the
surroundings in the trench or conduit, surface waves may be communicated over
URD
power lines in a manner consistent with that described herein.
[0157] While in the above embodiments the communication links between the
backhaul device and CIDs are surface wave transmissions, alternate embodiments
may
also include conductive transmissions. Consequently, the MV power line may be
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to transmit convention conductive transmissions and surface wave transmissions
simultaneously, thereby creating orthogonal channels. One type of transmission
(e.g.,
conductive) may be used to transmit data between the backhaul point and its
CIDs, and
the other type of transmission (e.g., surface wave) may be used to daisy chain
multiple
backhaul devices together and/or used as the backhaul link.
[0158] Finally, ultra wide band (UWB) pulses may be used in conjunction with,
or instead of, the surface wave and conductive transmissions described herein.
For
example, UWB pulses may be used to communicate between the CID and the
customer
premises or to communicate over the backhaul link (e.g., which may be the
neutral
conductor or an MV phase conductor). Alternately, UWB pulses may be used for
communications at sections of the electric power distribution network that
include
substantial number of attenuators (bends, insulators, etc.) instead of surface
wave
transmission.
[0159] It is to be understood that the foregoing illustrative embodiments have
been provided merely for the purpose of explanation and are in no way to be
construed
as limiting of the invention. Words used herein are words of description and
illustration,
rather than words of limitation. In addition, the advantages and objectives
described
herein may not be realized by each and every embodiment practicing the present
invention. Further, although the invention has been described herein with
reference to
particular structure, materials and/or embodiments, the invention is not
intended to be
limited to the particulars disclosed herein. Rather, the invention extends to
all
functionally equivalent structures, methods and uses, such as are within the
scope of
the appended claims. Those skilled in the art, having the benefit of the
teachings of this
specification, may affect numerous modifications thereto and changes may be
made
without departing from the scope and spirit of the invention.
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