Patent Application
20140355610
1. Field
The present disclosure relates generally to power line communication systems, and more particularly, to a switched power line communication network.
2. Background
Power line communication (PLC) is a technology that encodes data in a signal and transmits the signal on existing electricity power lines in a band of frequencies that are not used for supplying electricity. Accordingly, PLC leverages the ubiquity of existing electricity networks to provide extensive network coverage. Since PLC enables data to be accessed from conventional power-outlets, no new wiring needs to be installed in a building (or different parts of a building). Accordingly, PLC offers the additional advantage of reduced installation costs.
In some dwellings, PLC communications may be the best option for servicing communications, e.g., wireless communications incapable of penetrating walls or other structure, wireless communications deemed too insecure, installing wiring for other communication types is too expensive, etc. In many structures, however, the power mains, which service multiple differing dwellings, offices, etc., are serviced by a common feed, which allows PLC signals to propagate in undesired manners, which can limit the capacity available for PLC communications and to allow PLC signals to propagate to undesired locations and devices.
In an aspect of the disclosure, a method, a computer program product, and an apparatus for power line communication (PLC) are provided. The apparatus receives a first packet, selects a bus from a plurality of PLC buses, each PLC bus being isolated from other buses of the plurality of buses, and forwards the first packet to a destination PLC modem connected to the selected bus.
In another aspect, a method and system for switched power line communication (PLC) are provided. The system provides power to a plurality of PLC buses via a main circuit breaker, each PLC bus isolated from other buses of the plurality of buses, receives a first signal for communicating to a PLC bus, selects a PLC bus from the plurality of buses based on the first signal, communicates a second signal to the selected PLC bus, the second signal based on the first signal, and filters the second signal communicated to the selected PLC bus to prevent the second signal from passing through the main circuit breaker.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
Several aspects of power line communication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.
By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.
Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and floppy disk where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
Power line wiring may be electrically analogous to a network of transmission lines connected together in a large tree-like configuration. The power line wiring may have differing terminating impedances at the end of each stub of the network. As a consequence, the transfer function of a power line transmission channel may have substantial variations in gain and phase across the frequency band. Further, the transfer function between a first pair of power outlets may differ from that between a second pair of power outlets. The transmission channel can be fairly constant over time. Changes in the channel may occur when electrical devices are plugged into or removed from the power line (or occasionally when the devices are powered on/off). When used for networking devices in a power line communication network, the frequencies used for communication typically are well above the 60-cycle AC power line frequency. Therefore, a desired communication signal spectrum may be separated from a real power-bearing signal in a receiver connected to the power line network.
Another consideration in the power line environment is noise and interference. Many electrical devices create large amounts of noise on the power lines. Therefore, it is preferable that a power line networking system be capable of tolerating the noise and interference present on the power lines. The power line interference may be frequency selective. Frequency selective interference causes interference at specific frequencies (e.g., signals operating at specific frequencies may be interfered while other signals may experience no interference). The power line interference may also be impulsive by nature. Impulsive interference may span a broad range of frequencies but occurs in short time bursts. Some power line interference may be a hybrid of frequency selective interference and impulsive interference.
Noise may be neither uniform nor symmetrical across the power lines. For example, noise proximate a first device may cause the first device to be unable to receive data from a more distant second device. However, the second device may be able to receive data from the first device. The second device may be able to receive information from the first device because the noise at the receiver of the second device may be attenuated as much as is the desired signal. However, because the noise at the receiver of the first device is not as attenuated as is the desired signal (because the noise source is much closer to the first device than the second device), the first device will be unable to receive information from the second device.
A Power Line Communication (PLC) network may be bus-structured with a number of taps to which PLC modems may be connected. A switched PLC network splits a larger collision domain into smaller domains through PLC signal isolation using low-pass filters to permit simultaneous PLC signal transmissions in the smaller domains. This reduces a collision probability and improves overall throughput. A number of circuit breakers through which a PLC signal has to travel is also reduced. Circuit breakers significantly attenuate PLC signals. Therefore, by reducing the number of circuit breakers through which the PLC signal has to travel, the adverse effects of signal attenuation caused by the circuit breakers is minimized.
Splitting a large PLC collision domain into smaller domains may be referred to as segmentation. Network segments (e.g., PLC buses) may be connected through a switch such as an Ethernet switch (or PLC gateways). In case of using an Ethernet switch, a PLC modem may also include an Ethernet interface.
Referring to
In the PLC network 200, a PLC signal sent from a PLC modem (e.g., PLC modem 216 or PLC modem 218) to the switch 230, or sent from the switch 230 to the PLC modem (e.g., PLC modem 216 or PLC modem 218), does not travel through any of the circuit breakers 202, thus minimizing signal attenuation. The PLC signal may be prevented from traveling through a circuit breaker 202 by filtering the PLC signal using a filter 240 prior to reaching the circuit breaker 202. For example, if a circuit breaker 202 normally operates at 60 Hz AC, then a filter 240 isolating signals above 60 Hz may be used to prevent the PLC signal from passing through the circuit breaker 202.
In an aspect, the multiple panels of the PLC communication network 300 may be segmented at an individual circuit breaker level (as discussed with respect to
In an aspect, a network segment may contain a number of legs (e.g., PLC buses). The number of PLC buses may be isolated from each other with respect to PLC communication. However, the number of PLC buses may not be isolated from each other with respect to power distribution. For example, the number of PLC buses 312 may be connected to a same main circuit breaker 310. Communication between any devices within a panel may travel across two circuit breakers 308. Moreover, communication between any devices of two different panels may also travel across two circuit breakers 308. The communication may be performed by conveying a message or data packet. Signaling used to convey the message or data packet may vary. For some segments of the communication path, the signaling may be PLC signaling. For other segments of the communication path, the signaling may be some other type of data signaling (e.g., Ethernet signaling). For example, a message or data packet sent from a PLC bus 312 connected to the panel-1 302 may travel across a circuit breaker 308 of the panel-1 302 to a PLC modem 316 connected to a switch 322. The switch 322 may then send the message or data packet to either a PLC modem 318 or a PLC modem 320 depending on which PLC bus the PLC signal is destined for. Accordingly, if the message or data packet is destined for a PLC bus 312 connected to the panel-2 304, the switch 322 will send the message or data packet to the PLC modem 318 for forwarding across a circuit breaker 308 of the panel-2 304 to the appropriate PLC bus 312 connected to the panel-2 304. If the message or data packet is destined for a PLC bus 312 connected to the panel-3 306, the switch 322 will send the message or data packet to the PLC modem 320 for forwarding across a circuit breaker 308 of the panel-3 306 to the appropriate PLC bus 312 connected to the panel-3 306.
Still referring to
Different switching architectures may also be applied. Because the panel-A 402 is separated from the panel-B 404, either a new Ethernet cable may be installed or a power wire 406 used to connect the two panels may be used for switching. The two panels may be segmented using filters. For example, referring to
In an aspect, two PLC modems may be respectively attached to each end of the power wire 406 in conjunction with any of the filters described above. The Ethernet interfaces of the two PLC modems may be each connected to either an Ethernet interface of a switch port or that of a PLC modem, depending on a switching architecture used. Although
At step 502, the system provides power to a plurality of PLC buses via a main circuit breaker. Each PLC bus may be isolated from other buses of the plurality of buses. In an aspect, the plurality of PLC buses may be isolated from each other with respect to PLC communication. However, the plurality of PLC buses may not be isolated from each other with respect to power distribution. For example, the plurality of PLC buses may be connected to a same main circuit breaker. Moreover, each PLC bus may include a plurality of connected PLC modems communicating with each other. A PLC modem may be utilized by a device to communicate with other devices connected to the system.
At step 504, the system receives a first signal for communicating to a PLC bus. The first signal may be received by receiving a message or data packet. Signaling used to receive the message or data packet may vary. For some segments of the communication path, the signaling may be PLC signaling. For other segments of the communication path, the signaling may be some other type of data signaling (e.g., Ethernet signaling). In an aspect, to minimize signal attenuation, the system may filter the first signal to prevent the first signal from passing through the main circuit breaker prior to being further processed by the system. At step 506, the system selects a PLC bus from the plurality of buses based on the first signal. The first signal may be received from the Internet. Alternatively, the first signal may be received from one of the plurality of buses other than the selected bus. The system may select the PLC bus based on an address associated with the first signal. The address may correspond to a destination PLC modem that is one of a plurality of PLC modems connected to the selected bus.
At step 508, the system communicates a second signal to the selected PLC bus. In particular, the system may communicate the second signal to a destination PLC modem connected to the selected bus. The second signal may be communicated via a message or data packet. Signaling used to communicate the message or data packet may vary. For some segments of the communication path, the signaling may be PLC signaling. For other segments of the communication path, the signaling may be some other type of data signaling (e.g., Ethernet signaling). The second signal may be based on the first signal. For example, the second signal may be the same as the received first signal. Hence, the second signal may be a message or data packet communicated via the same type of signaling (e.g., PLC signaling, Ethernet signaling, etc.) used to receive the first signal. Alternatively, the second signal may be a deconstructed or reconstructed version of the received first signal. That is, the first signal may be a first message or data packet received via a first type of signaling (e.g., PLC signaling, Ethernet signaling, etc.) and the second signal may be a second message or data packet generated based on the first message or data packet, but communicated via a second type of signaling (e.g., PLC signaling, Ethernet signaling, etc.) different from the first type of signaling.
At step 510, the system filters the second signal communicated to the selected PLC bus to prevent the second signal from passing through the main circuit breaker. Filtering prevents a signal (e.g., message or data packet) from being provided to a destination bus more than once. For example, a signal may be provided to a destination bus a first time via switching, and provided to the destination bus a second time when an original signal travels through connected power wiring and through circuit breakers on its way to the destination bus of the power wiring. Accordingly, by preventing the second signal from passing through the main circuit breaker, the filtering at step 510 prevents interference and helps ensure that the second signal is provided to the selected PLC bus no more than once.
An example of a hardware implementation for performing each of the steps of the algorithm in the aforementioned flow chart of
Referring to
In an aspect, the exemplary network 200 includes at least one PLC modem (e.g., PLC modem 216) connected to an electric outlet 214 of one of the PLC buses (e.g., PLC bus 208) and at least one other PLC modem (e.g., PLC modem 218) connected to an electric outlet 214 of another one of the PLC buses (e.g., PLC bus 212). Accordingly, the at least one PLC modem (e.g., PLC modem 216) may communicate a signal with the at least one other PLC modem (e.g., PLC modem 218) via a switch 230.
The switch 230 may receive a first signal for communicating to a PLC bus, and select a PLC bus from the plurality of PLC buses 208, 210, and 212 based on the first signal. In an aspect, to minimize signal attenuation, at least one of the plurality of filters 240 may filter the first signal to prevent the first signal from passing through the main circuit breaker 206 prior to being received by the switch 230. A respective filter 240 of the plurality of filters may be connected between a corresponding PLC bus and the main circuit breaker 206. The respective filter 240 may also be connected between the switch 230 and the main circuit breaker 206.
The switch 230 may select the PLC bus based on an address associated with the first signal. The address may correspond to a destination PLC modem (e.g., PLC modem 216) that is one of a plurality of PLC modems connected to the selected bus (e.g., PLC bus 208).
In an aspect, the switch 230 may receive the first signal from the Internet 234. Alternatively, the switch 230 may receive the first signal from one of the plurality of buses other than the selected bus. For example, if the selected bus is the PLC bus 208, then the switch 230 may receive the first signal from the PLC bus 210 or the PCL bus 212.
Upon the switch 230 receiving the first signal and selecting a bus, the switch 230 may communicate a second signal to the selected PLC bus (e.g., PLC bus 208). In particular, the switch 230 may communicate the second signal to a destination PLC modem 216 connected to the selected bus 208. The second signal may be based on the first signal. For example, the second signal may be the same as the received first signal. Alternatively, the second signal may be a deconstructed or reconstructed version of the received first signal. A filter 240 may filter the second signal communicated to the selected PLC bus 208 to prevent the second signal from passing through the main circuit breaker 206.
The network 200 may include additional modules that perform each of the steps of the algorithm in the aforementioned flow chart
In one configuration, the network 200 for power line communication includes means for providing power to a plurality of PLC buses via a main circuit breaker, each PLC bus isolated from other buses of the plurality of buses, means for receiving a first signal for communicating to a PLC bus, means for selecting a PLC bus from the plurality of buses based on the first signal, means for communicating a second signal to the selected PLC bus, the second signal based on the first signal, and means for filtering the second signal communicated to the selected PLC bus to prevent the second signal from passing through the main circuit breaker. The aforementioned means may be one or more of the aforementioned modules/components of the network 200 configured to perform the functions recited by the aforementioned means.
In an aspect, each of the PLC buses of the plurality of PLC buses may be connected to a main circuit breaker providing power. Furthermore, each PLC bus may be isolated from other buses of the plurality of buses. For example, the plurality of PLC buses may be isolated from each other with respect to PLC communication, but may not be isolated from each other with respect to power distribution.
In a further aspect, the switch selects a bus based on an address portion of the first packet. The address portion may correspond to a destination PLC modem that is one of a plurality of PLC modems connected to the selected bus.
At step 606, the switch forwards the first packet to a destination PLC modem connected to the selected bus. The first packet may then be forwarded from the destination PLC modem to a device via an Ethernet connection or Layer 2 signaling.
The receiving module 704 receives a first packet. The selecting module 706 selects a bus (e.g., selected bus 712) from a plurality of PLC buses. The selected bus 712 may include a plurality of connected PLC modems communicating with each other. The first packet may be received from the Internet 714. Alternatively, the first packet may be received from one of the plurality of buses other than the selected bus (e.g., PLC bus 710).
In an aspect, each of the PLC buses of the plurality of PLC buses may be connected to a main circuit breaker providing power. Furthermore, each PLC bus may be isolated from other buses of the plurality of buses. For example, the plurality of PLC buses may be isolated from each other with respect to PLC communication, but may not be isolated from each other with respect to power distribution.
In a further aspect, the selecting module 706 selects a bus based on an address portion of the first packet. The address portion may correspond to a destination PLC modem that is one of a plurality of PLC modems connected to the selected bus 712.
The sending module 708 forwards the first packet to a destination PLC modem connected to the selected bus 712. The first packet may then be forwarded from the destination PLC modem to a device via an Ethernet connection or Layer 2 signaling.
The apparatus 702 may include additional modules that perform each of the steps of the algorithm in the aforementioned flow chart of
The processing system 814 includes a processor 804 coupled to a computer-readable medium 806. The processor 804 is responsible for general processing, including the execution of software stored on the computer-readable medium 806. The software, when executed by the processor 804, causes the processing system 814 to perform the various functions described supra for any particular apparatus. The computer-readable medium 806 may also be used for storing data that is manipulated by the processor 804 when executing software. The processing system further includes at least one of the modules 704, 706, and 708. The modules may be software modules running in the processor 804, resident/stored in the computer readable medium 806, one or more hardware modules coupled to the processor 804, or some combination thereof. The processing system 814 may be a component of the switch 230 (
In one configuration, the apparatus 702/702′ for power line communication includes means for receiving a first packet, means for selecting a bus from a plurality of PLC buses, each PLC bus being isolated from other buses of the plurality of buses, and means for forwarding the first packet to a destination PLC modem connected to the selected bus. The aforementioned means may be one or more of the aforementioned modules of the apparatus 702 and/or the processing system 814 of the apparatus 702′ configured to perform the functions recited by the aforementioned means.
It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
