Abstract:
Devices and systems for providing reduced cost and increased reliability power line communications (PLC) and electrical power to a network device using a PLC supply unit via a single cable with 2 wires are disclosed. The PLC supply unit receives a PLC power and data signal, extracts the power signal, the data signal and generates a timing signal based on the power signal. The PLC supply converts the electrical power signal from an alternating current (AC) to a direct current (DC) electrical power signal and then recombines the DC electrical power signal with the data signal and the timing signal and sends the composite signal to the network device. The network device receives the composite signal and uses the DC electrical power signal to power the network device and, at an internal PLC processing module, processes the data signal for communication with other network devices using the timing data.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure claims priority to U.S. Provisional App. No. 61/480,226 for “Power Line Communications over DC power supply cable” filed Apr. 28, 2011, and U.S. Provisional App. No. 61/522,176 for “Power Line Communications over DC power supply cable” filed Aug. 10, 2011, both of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     BACKGROUND 
     Particular embodiments generally relate to systems, circuits, and devices for communicating data signals over increased voltage direct current (DC) power line cables. 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     In an attempt to simplify the implementation and deployment of data transmission and networking infrastructures, various systems exist for sending data over power transmissions lines. Data transmission systems that use existing power transmission lines and wires for data communication are referred to as power line communication (PLC) systems. PLC systems have the distinct advantage of reducing the cost and complexity associated with deploying, installing, and maintaining separate data transmission wires or fiber optic cable required for other physical connection-based networking systems, such as Ethernet, digital subscriber lines (DSL) or high-speed internet cable or fiber optic systems. However, transmitting and receiving data and power on the same wires or cables presents a particular set of problems and drawbacks. 
     For example, receiving data over a power line, such as a conventional household electrical system of wires, breakers, switches and outlets, requires specialized transceivers that can both receive the composite power/data signals and separate or filter the data signal from the alternating current (AC) or the direct current (DC) electrical power delivered at a particular voltage.  FIG. 1  shows a simplified schematic of a conventional system  100  for transmitting and receiving data over electrical power lines. As shown, the system  100  includes transmitter/receiver or transceiver  105  coupled to the supply unit  120  via the power wires  110 . The power wires are typically the wires of a residential or commercial electrical system and include isolated positive and negative wires. The actual electrical power signal can be generated, transmitted and routed to transceiver  105  by another entity, such as a municipal or private electrical power company. In such systems, the electrical power can be provided in a variety of voltages, currents, and signal types and the transceiver  105  can be coupled to that existing electrical power supply system at a location local or remote to the supply unit  120 . Typical household electrical power in North America is provided at approximately 50 Hz AC, 120V and 15 A, while in Europe and Asia, electrical power is provided at 50-60 HZ AC, 220-240V and 10-20 A. 
     Inside the supply unit  120 , is a collection of components used for converting the received electrical power from one voltage to another, from one current to another, and/or from AC to DC, while also detecting any included data signals from the transceiver  105 . As shown, supply unit  120  includes an AC/DC and DC/DC converter  121  coupled to power wires  110  to convert the received electrical power to the voltage, current, and type of power required by the network device  130  over DC supply line  113 . The supply box  120  also includes a zero-crossing detection module  123  coupled to the power lines  110 . The zero-crossing detection module  123  can sense the frequency of an AC power signal by determining the number of times the AC power signal goes from the positive to negative and negative to positive in a given time period. The zero-crossing can be counted or otherwise sensed in both the positive-to-negative direction and negative-to-positive direction, or in only one of the directions. In any scenario, the zero-crossing detector  123  can provide the zero-crossing events to the digital base-band unit  127  over connection  111  data for PLC timing purposes. 
     Also connected to the power lines  110  is the PLC analog front-end module  125 . PLC analog front end module  125  can receive both the electrical power signal and the data signal over the electrical wires  110  from transceiver  105 . PLC analog front end module  125  filters the data signal from the electrical power signal. PLC analog front end module  125  sends the data signal filtered from the composite electrical power and data signal to the digital base-band module  127 . Digital baseband module  127  can then send a modulated digital data signal to a network device  130  over a network connection  115 . Network connection  115  can be any type of data for network communication including, but not limited to USB, Ethernet, IEEE 1394, IEEE 1903, IEEE 1901, and other data and network cables, wires and connections. 
     As can be seen in  FIG. 1 , to deliver both electrical power signals and data signals from the supply unit  120  to the network device  130  requires two physical wire connections; DC supply connection  113  and network connection  115 . To simplify the connection between the supply unit  120  and the network device  130 , some conventional solutions have reduced the number of physical wire connections between the supply unit and the network device from two to one.  FIG. 2  shows one conventional solution (for example Power-over-Ethernet) for a simplified connection between supply unit  122  and network device  131  that using a single composite power/data connection or cable  117 . In such solutions, the converted electrical power signal from AC/DC+DC/DC converter  121  is sent via dc supply connection  113  to be combined with the data signal filtered from the incoming composite electrical power and data signal. 
     In the example shown, the PLC module  129  includes both the analog front-end and the digital base-band capabilities. The PLC module  129  performs the same functions as PLC front-end module  125  and digital base-band module  127  described in reference to  FIG. 1 , and then sends the data signal and the zero-crossing data from the zero-crossing detector  123  to the network device  131  that is configured to receive a composite electrical power and digital data signal via composite power/data cable  117 . Since power/data cable  117  is usually an Power-over-Ethernet cable, the power supplied is limited to approximately 100 mA. Such limited electrical power is often insufficient especially for many network devices, such as network gateways, network access points, network routers, Internet-enabled or multi-media television set-top boxes, and personal computers, because such devices usually require electrical power with voltages on the order of 1V to  10   y.    
     Drawbacks of using either of the solutions described in reference to  FIGS. 1 and 2 , stem from the inclusion of the AC/DC or DC/DC power converter  121  and the PLC module functionality in the same physical box as shown in supply units  120  and  122 . Inexpensive and mass-produced AC/DC or DC/DC power converter  121  are more often than not the point of failure in supply units such as supply units  120  or  122 . The cost of replacing a supply unit can be high based on the fact that the entire supply unit, including the expensive PLC module components, need to be replaced each time the commoditized AC/DC or DC/DC power converter  121  fails. Furthermore, inexpensive AC/DC or DC/DC power converters are often not designed with data communication in mind, so such AC/DC or DC/DC power converters can also generate internal electrical noise that can interfere with the data signal sent to the network device  130  or  131 . 
     SUMMARY 
     Various embodiments include a power line communication supply having an input/output (I/O) terminal configured to receive a composite electrical power and data input signal. The power line communication supply can include an electrical power signal converter, a power line communication module, and a timing module, each of which is coupled to the I/O terminal. The power line communication supply also includes a composite output terminal coupled to each of the electrical power signal converter, the power line communication module, and the timing module. The composite output terminal can be configured to send, to a network device comprising a power line communication processing module, a composite output signal that includes a converted electrical power signal from the electrical power signal converter, a data signal from the power line communication module, and a timing data signal from the timing module. 
     Other embodiments include a network device having a composite input/output (I/O) terminal and a power line communication processing module configured to receive, via the composite I/O terminal, a composite direct current (DC) electrical power and data signal from a power line communication supply. The power line communication supply includes an input/output (I/O) terminal configured to receive an alternating current (AC) electrical power and power line communication data input signal from a transmitter. The power line communication supply also includes an electrical power signal converter, a power line communication module, and a timing module, each of which is coupled to the I/O terminal. The power line communication module further includes a composite output terminal coupled to the electrical power signal converter, the power line communication module, the timing module, and the composite I/O terminal of the network device. 
     Another embodiment includes a system having a network device that includes a composite input/output (I/O) terminal, and a power line communication processing module configured to receive, via the composite I/O terminal, a composite direct current (DC) electrical power, and data signal. Such embodiments also include a power line communication supply having an input/output (I/O) terminal configured to receive an alternating current (AC) electrical power and power line communication data input signal from a transmitter. Such a power line communication supply also includes an electrical power signal converter, a power line communication module, and a timing module, each coupled to the I/O terminal. The power line communication supply further includes a composite output terminal coupled to the electrical power signal converter, the power line communication module, the timing module, and the composite I/O terminal of the network device. 
     The following detailed description and accompanying drawings provide a more detailed understanding of the nature and advantages of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a simplified schematic of one solution for providing power line communications. 
         FIG. 2  shows simplified schematic of another solution for providing power line communications. 
         FIG. 3  shows a simplified schematic of a system for providing power line communications according to one embodiment. 
         FIG. 4  shows a simplified schematic of a network that can be implemented using various embodiments. 
         FIG. 5  shows a waveform of an alternating current (AC) electrical power signal and an associated zero-crossing digital waveform or data that can be used in various embodiments. 
         FIG. 6  shows a simplified schematic of a network device for use in power line communications according to various embodiments. 
         FIG. 7  shows a simplified schematic of a network device for use in power line communications according to various embodiments. 
         FIG. 8  shows a schematic of a supply unit for providing power line communications according to various embodiments. 
         FIG. 9  shows a schematic of a network for receiving power line communications according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are techniques for systems, devices and methods for providing simplified power line communications. In the following description, for purposes of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. Particular embodiments as defined by the claims may include some or all of the features in these examples alone or in combination with other features described below, and may further include modifications and equivalents of the features and concepts described herein. 
     As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
       FIG. 3  shows a schematic of a system  300  for providing simplified power line communication (PLC) with increased systematic reliability and reduced maintenance/replacement costs according to various embodiments of the present disclosure. System  300  includes a transceiver  105  for sending electrical power signals and data signals over electrical power wires  110  to supply unit  320 . Supply unit  320  can convert the electrical power signal from the transceiver  105  to a form required by the associated network device  132 , to which it is coupled by composite electrical power and data cable  317 , which can be a single cable with only 2 wires. Supply unit  320  can also receive and forward the data signal over composite electrical power and data cable  317  to network device  132 . In related embodiments, the supply unit  320  can detect the frequency at which the received AC electrical power signal crosses zero as it alternates between positive and negative voltages and send such zero-crossing data to the network device  132 . In such embodiments, the converted composite electrical signal, the detected data signal, and the zero-crossing data can be combined and sent to the network device  132  via composite electrical power and data cable  317 . 
     In some embodiments, the transceiver  105  is a device that can be situated at a remote location, such a power generation or relay station, while in other embodiments, the transceiver can be situated at the same site as the supply unit  320  and network device  132 , such as in a residential or commercial building. In such embodiments, the transceiver can be coupled to the electrical power transmission wires  110  and configured to transmit and receive digital or analog data signals at frequencies separated or otherwise isolated from the frequency of the AC electrical power signal. Accordingly, transceiver  105  can include appropriately configured devices used in the deployment of high-speed internet access, residential and commercial networking, as well as high quality media broadcasting. In networking embodiments, transceiver  105  can be another PLC network device. 
     As shown, supply unit  320  can include an number of internal components or modules for receiving, processing, analyzing, converting and retransmitting the received composite electrical power and data signal to a network device  132 . For example, supply unit  320  can include an electrical power signal converter  121  coupled to the electrical power wires  110 . The converter  121  can be configured to receive and convert the electrical power signal from the transceiver  105 . In such embodiments, the converter  121  can be configured to convert an AC electrical power signal to a direct current (DC) electrical power signal, convert a received DC electrical power signal to another DC electrical power signal. In converting the received electrical power signal, the converter  121  can change or condition the voltage, current, or alternating frequency to a form required or expected by a network device  132 . 
     Also shown in supply unit  320 , is a broadband coupling module  322 , coupled to the electrical power wires  110 , for receiving and processing the PLC data signal. The broadband coupling module  322  can also be configured to up or down convert the received PLC data signal based on requirements of system  300  or network device  132 . For example, network device  132  might be configured to detect and process data signals in a frequency spectrum higher or lower than that in which the original PLC data signal was transmitted from transceiver  105 . Similarly, broadband coupler  322  can also be configured to boost or otherwise amplify the received PLC data signal. Broadband coupling module  322  can then transmit the PLC data on wires  113  to combine the PLC data signal with the converted electrical power signal and timing data extracted from the received composite electrical power and data signal by zero-crossing detector  324  and/or local oscillator  325 . 
     In some embodiments, network device  132  can synchronize data transmission and reception with other PLC network devices connected in a network configuration over electrical power transmission wires or cables, like the network shown in  FIG. 4 . In the network  400  shown in  FIG. 4 , multiple PLC network devices, like supply unit  320  in combination with network device  132 , can be connected to one another via a network of electrical power transmission wires  110 . In such networks each device can use the characteristics of an electrical power signal that exists on the electrical power transmission wires  100 . Specifically, in some embodiments, each PLC network device can determine the frequency at which the AC electrical power signal crosses 0V as it alternates from positive to negative voltages. 
       FIG. 5  show an example of a how an AC electrical power signal  500  can be detected and used to generate a digital timing signal  510  that can be used by networked PLC network devices to synchronize or organize data communications over new and existing electrical power transmission lines. As the voltage of AC electrical power signal  500  crosses from negative to positive at point  511 , digital timing signal  510  can be made to go “high” or positive, and when the voltage of the AC electrical power signal  511  goes from positive to negative at point  512 , the digital timing signal  510  can be made to go “low” or negative. As shown, the digital timing signal  510  can be made to go high on the rising edge zero-crossing of the AC electrical power signal  500 , but in other embodiments, the digital timing signal  510  can be made to go high on falling edge zero-crossing. Accordingly, in either such determinations of the AC electrical power signal  500  zero-crossings, the digital timing signal  510  can be used as the zero-crossing data by the AC coupler or zero-crossing detector  324  shown in  FIG. 3 . 
     In alternative embodiments, AC coupler or zero-crossing detector  324  can generate an attenuated version or image of the AC electrical power signal. This attenuated AC electrical power signal is an lower amplitude image of the AC electrical power signal which can then be used as the timing information sent in the composite electrical power and data cable to the network device  132  coupled to the supply unit  320 . 
     In some embodiments, the zero-crossing detector  324  can detect the zero-crossing frequency from the received AC electrical power signal and generate the digital timing signal or the AC electrical signal image and send either of such signals to AC coupling module  323  via connection  115 , modulator  119 , and connection  114 . In such embodiments, the digital timing signal or the AC electrical power signal image is sent at the original or natural frequency determined directly from the AC electrical power signal. In other embodiments, however, it is desirable to shift the frequency of the digital timing signal or the AC electrical power signal image to avoid interference with the PLC data signal provided by the broadband coupling module  322 . 
     For example, where the PLC data signal provided by the broadband coupling module  322  can have a range of frequencies, the digital timing signal or the AC electrical power signal image can be multiplied using modulator  119  with an numerically controlled oscillating signal from local oscillator  325  via connections  116 . Depending on the spacing of the range of frequencies of the PLC data signal, the 0 Hz converted DC electrical power signal and other signals potentially included on the AC electrical power transmission wires, the timing signal, either a digital timing signal determined from the zero-crossings of the received AC electrical power signal or an attenuated image of the AC electrical power signal, can be frequency shifted to be above or below the PLC data signal frequency range to avoid interference. 
     The PLC data signal from broadband coupling module  322 , the timing signal from AC coupler or zero-crossing detector  324 , and the converted DC electrical power signal from converter  121  can be combined on wires  113  and then transmitted to network device  132  via composite cable  317 . Network device  132  can include a PLC module  140 . In some embodiments, the PLC module  140  can be a single integrated circuit that performs both the analog front-end and digital base-band functions for sending and receiving PLC data signals over the composite cable  317 . In other embodiments, the PLC module  140  can include a number of electronic components or integrated circuits to perform the analog front-end and digital base-band functions. In related embodiments, the PLC module  140  can also handle receiving and distributing the DC electrical power received on the composite cable  317 . 
     Such PLC module  140  equipped networks devices  132  can be network gateways, television set-top boxes for delivering data and media to one or more televisions, and other standalone network devices such as personal computers and server computers. An advantage of system  300  includes the configuration show in  FIG. 3  that separates converter  121  from being in the same housing or enclosure as PLC module  140 . The separation of converter  121  from PLC module  140  not only simplifies setup of the system and avoids any potential electrical interference between the two modules, but also provides for a supply unit  320  with a reduced bill of materials and, accordingly, a reduced cost of replacement in the event that the commoditized converter  121  fails. 
     Exemplary embodiments of network devices configured for receiving composite PLC data, DC electrical power, and timing composite signals will now be discussed.  FIG. 6  shows a simplified schematic of a network device  600  that can be used in combination with supply units that provide attenuated AC electrical power signal images as a timing information signals in the composite power/data signal sent over a composite cable, according to various embodiments of the present disclosure. As shown the composite signal is received over composite cable  317 . AC coupling module  610  can couple the analog receiver  615  to the incoming composite signal. The AC electrical power signal image is frequency shifted up or down using the multiplier  620  that references local oscillator  650 . The frequency shifted AC electrical power signal image can then be sent to zero-crossing detector  630  to generate a timing signal as in conventional PLC solutions. The digital based module  640  can then use the timing signal from zero-crossing detector  630  to decode the PLC data signal received via AC coupling module  610  and analog receiver  615 . Meanwhile, the AC blocking module  660  can filter out any alternating current signals and provide the converted DC electrical power signal to the rest of the components internal and external to the to the network device  600  on wires  618 . 
       FIG. 7  shows a simplified schematic of a network device  700  that can be used in combination with supply units that provide a digital timing data as a timing information signal in the composite signal sent over a composite cable, according to various embodiments of the present disclosure. In such embodiments, the composite signal is sent through the reception chain that includes the AC coupling module  610  and the analog receiver  615  and the digital timing signal is extracted in the digital base-band module  740  in reference to an internal local oscillator  750  and multiplier  720 . In such embodiments, the local oscillator  750  can be a numerically-controlled oscillator (NCO). 
       FIG. 8  shows a schematic of a supply box  800  according to an embodiment of the present disclosure. As shown, supply box  800  includes an AC/DC supply  810  that can include transformer  811 . While not shown in  FIG. 8 , the AC/DC supply  810  can be configured to provide additional regulation and filtering. The output of the AC/DC supply  810  is a DC electrical power signal. To reduce high frequency noise in the output DC electrical power signal, each terminal of transformer  810  can be coupled to the terminals of capacitor  812  that can then be coupled to one of inductors  813  and  814  as shown in box  860 . The inductors  813  and  814  provide high impedance for high frequency noise in the output DC electrical power signal. The converted and filtered output DC electrical power signal can then be fed into the composite cable  880 . 
     Also connected to the incoming AC electrical power and PLC data signal on connection  820  is the PLC transfer circuit  830 . PLC transfer circuit  830  can include capacitors  815 ,  816 ,  817 , and  818  and a transformer  831  connected to one another as shown  FIG. 8 . Capacitors  815  and  816  couple the input terminals of transformer  831  to the incoming composite AC electrical power signal wires  820 . The capacitors  817  and  818  couple the output terminals of transformer  831  to the composite cable  880  to include the PLC data signal in the composite output PLC electrical power and data signal. The inclusion of capacitors  817  and  818  ensures that output of AC/DC converter circuit  810  does not short circuit with the input composite AC PLC electrical power and data signal. The capacitors  817  and  818  can be sized to avoid any attenuation in the PLC node fall off frequency. The step ratio of the transformer  831  can include any number of step-up and step-down ratios. For various embodiments of the present disclosure, the step ratio of the transformer  831  can be one-to-one. 
     The other circuit or module that can be included in the supply unit  800  is for determining and/or generating the timing data that can be sent to the intended network device over composite cable  880  in a manner analogous to the functionality described in reference to AC coupler or zero-crossing detector  324 . As shown, opto-coupler  845  is also coupled to the incoming input PLC AC electrical power and data signal. The opto-coupler  845  can generate an attenuated AC electrical power signal image (i.e. a low amplitude sinusoidal AC signal having the same zero-crossing frequency as the AC electrical power signal on wires  820 ). In other embodiments, the opto-coupler can generate a digital timing signal (i.e. a square-wave signal in which the signal goes high or low when the incoming AC electrical power signal crosses over from positive to negative). In either scenario, the opto-coupler  845  can send the timing data signal to mixer  855  where it can be mixed, up-converted or down-converted to a frequency above or below the frequency range of the PLC data signal to avoid interference using a signal provided by voltage controlled oscillator (VCO)  850 . The timing data signal can then be added to composite cable  880  via transformer  840 . Accordingly, composite cable  880  can carry a composite electrical power and data signal that includes, the DC electrical power signal, the PLC data signal and the timing data signal. 
     Composite cable  880  can then be connected to a network device such as network device  900  shown in  FIG. 9 . According to some embodiments, network device  900  can extract the DC electrical power signal received from composite cable  880  using inductors  910  and  911  and capacitor  912 . For example, the internal components can be powered by the 12V DC signal on wire  960  and reference the Vss on  970 . While 12V DC is a typical voltage for many network devices, other voltages can be used without deviating from the spirit and scope of the present disclosure. 
     Network device  900  can also include an AC coupling module  920  to extract the PLC data signal from the received composite cable  880 . In some embodiments, the AC coupling module  920  comprises a pair of capacitors or a transformer to relay the PLC data signal to the PLC module  930 . The AC coupling module  920  can then send the PLC data signal to PLC module  930 . PLC module  930  can include a number of components on one or more integrated circuits. 
     As shown, PLC module  930  can include a PLC analog front-end module  931  and a digital bas-band module  932 . The PLC analog front-end and digital base-band can be used to receive and send PLC data signals over composite cable  880 . In some embodiments, the PLC module  930  can send and receive PLC data signals in synchronization with other network devices on a PLC time division multiple access (TDMA) network. 
     The PLC module  930  can reference timing data from timing circuit  950 . In PLC TDMA networks, all of the network devices can be synchronized by the AC electrical power signal cycle, as represented by the zero-crossing digital timing signal or attenuated AC electrical power signal image, discussed above. In some embodiments of PLC TDMA networks, a beacon sending station (BSS) manager can periodically send a beacon message to all of the network devices with various of network information. 
     For example, a BSS manager can send out beacon signals or messages with network information, such as contention free periods and time slot distributions between the network devices to exchange the data. Since BSS manager is the network time reference, it is beneficial for the all the network devices on a PLC TDMA network to be synchronized with BSS manager. After the transmission of beacon message signal, the PLC TMDA network can include a carrier sensing multiple access time (CSMA) time slot in which new stations that are not yet synchronized with the BSS manager can transmit request messages in order to join the PLC TDMA network. After the CSMA time slot, there is a TDMA time slot during which network devices on the PLC TDMA network can exchange data. A PLC network time period including the time for beacon message to be sent, the CSMA time slot, and the TDMA time slot can be defined in terms of the number of AC electrical signal cycles. For example, in some embodiments, the PLC network time period can occur within two AC electrical power signal cycles. Two AC electrical power signal cycles can be defined as occurring between an zeroth zero-crossing and a fourth zero-crossing. In such embodiments, the PLC network time period can include a predetermined or fixed time offset after the zeroth zero-crossing and the beacon message signal is sent. 
     Timing circuit  950  includes two capacitors  953  and  954  coupled to composite cable  880  and disposed in series with resistors  955  and  956  to couple the composite AC electrical power and PLC data signal to mixer  952  and the PLC module  930 . The timing circuit  930  can also include a voltage controlled oscillator  951  that can be used in combination with mixer  952  to provide an up-converted or down converted timing signal to PLC module  930  to avoid interference with the 
     Inductor  814  can be coupled to a capacitor  817  that is also coupled to an output terminal of transformer  830 . In other embodiments, more noise filters like the circuit in box  860  can be included in multiple stages to further reduce any high frequency noise the output DC electrical power signal. 
     The above description illustrates various embodiments of the present invention along with examples of how aspects of the present invention may be implemented. The above examples and embodiments should not be deemed to be the only embodiments, and are presented to illustrate the flexibility and advantages of the present invention as defined by the following claims. Based on the above disclosure and the following claims, other arrangements, embodiments, implementations and equivalents may be employed without departing from the scope of the invention as defined by the claims.