Patent Publication Number: US-11385695-B2

Title: Methods and apparatus relating to the supply of power to power over ethernet devices

Description:
PRIORITY 
     This application is a continuation of and claims priority to U.S. patent application Ser. No. 16/287,853, filed Feb. 27, 2019 and entitled “Methods and Apparatus Relating to the Supply of Power to Power Over Ethernet Devices.” The contents of this prior application is considered part of this application, and are hereby incorporated by reference in their entirety 
    
    
     FIELD 
     The present application relates to communications systems, and more particularly, method and apparatus related to the supply of power to Power over Ethernet access points. 
     BACKGROUND 
     Various standards relate to the supply of power over Ethernet lines. In accordance with such systems at least two lines in a cable are normally used to supply power to a device. The device being powered is often referred to as a Powered Device (PD) with the device supplying the power sometimes being referred to as a Power Sourcing Equipment (PSE). 
     The distance between a PD, such as an Access Point (AP), and a PSE, e.g., switch, may vary from one PD to another. This makes the delivery of power to the PD, somewhat unpredictable given that the line loss is unknown. While voltage and/or power may be monitored at a PSE, the actual amount of power delivered to the PD is not reliably known to the PSE due to line loss and/or other operating conditions that may affect the amount of power reaching the PD(s) or to which power is being supplied. 
     Not only is the unpredictable nature of power loss during transmission a factor in the amount of power that may have to be supplied to a pair of power lines connected to the PD, the amount of power required by a PD will vary from time to time based on a variety of factors such as temperature or features in use on the PD. 
     In order to ensure that PDs attached to a PSE receive adequate power, the PDs often request more power than they actually need or are provisioned based on the assumption that the PDs will require more power than they will actually need. By providing PDs power based on worst case expectations the number of PDs that can be supplied at a given time may be less than could otherwise be supported and/or some PDs are denied power which they could use, e.g., they are lower priority PDs than PDs which are being over provisioned with power based on the lack of reliable power requirement information. 
     In view of the above discussion it should be appreciated that there is a need for methods and apparatus for reliability determining power needs and/or communicating power needs to Power Sourcing Equipment (PSE) supplying power in an Ethernet system. 
     SUMMARY 
     In various embodiments, sensors are provided within PDs to measure power needs for determining information which can be communicated to a PSE and be used in determining line loss and/or transmission loss so that such losses can be factored into making power supply decisions. 
     In some embodiments, PDs include a voltage sensor, e.g. a voltmeter, that is used to measure a voltage across a sense resister that is connected to a PoE power input. Based on the measured voltage drop across the sense resistor and the known value of the sense resistor, the input current to the PD is determined. Voltage is also measured on the PD PoE power input, e.g., the input line voltage at the PD is determined. In embodiments, input power is determined in the PD using the measured current and measured voltage. In some embodiments, a temperature sensor is also included in the PDs allowing for temperature measurements at the PDs. The PDs include detectors which may be included in a processor, or external to a processor, for detecting peripheral devices coupled to the PD. 
     In some but not necessarily all embodiments the measured input current, and measured input line voltage and/or temperature measured at the PD is provided to a processor in the PD. The processor controls the reporting of these measurements to the PSE along with power requests. The processor in the PD determines the amount of power to be required for a given time period based on the detected peripheral devices coupled to the PD, the detected input voltage, the detected input current, and when measured, the detected temperature. In cases where the PD is a wireless device such as an AP, the required amount of power may be and sometimes is determined based on a number of transmitters and/or receives to be powered during a given time period. The number of transmitters and/or receives to be powered during a given time period may be determined based on a traffic load, e.g., the amount of traffic to be transmitted to devices and/or received from devices. 
     After determining the amount of power to be requested, the PD sends a request to the PSE for the requested amount of power, e.g., a number of watts. The measured input line voltage, current, and/or temperature at the PD may be communicated with the PoE power request or separately from the PoE power request. 
     The PSE, e.g., a PoE switch, receives the PoE power request from one or more PDs and, in some cases, the measured line voltage, current, and/or temperature at the requesting device. The PSE takes into consideration the received measurement information, e.g., voltage at the PD, current at the PD, and/or temperature. In some embodiments the PSE estimates the amount of power loss to the device due to transmission loss and takes this into consideration when determining the amount of power to be supplied to the requesting device. For example, the amount of power expected to be lost due to transmission may be added to the amount of power requested when determining the requesting PDs actual power needs. 
     Based on the amount of power available at the PSE, the requested amount of power and reported measurement information from one or more PDs, the PSE determines the amount of power to be provided to individual PDs requesting power. In some cases, depending on the priority of the device and/or the number of devices requesting power, the PSE may or may not grant a PD all the power it is requesting. 
     The amount of power granted to individual PDs is communicated from the PSE to the PDs to which power grants are made. The power grant may, and in some embodiments does, not take into consideration the amount of power the PD allocated to transmission loss. The amount of power indicated as being granted to a PD that is subject to a large transmission loss may be lower, e.g., one or several watts lower, than the actual amount of power allocated by the PSE. In this way. PDs can make power requests based on their actual expected needs, potentially plus some safety factor, without having to worry if they will suffer from extensive transmission power loss due to whether they are connected to the PSE by a short or long set of lines. 
     A PD which receives a power grant that is less than a requested amount may, and in some embodiments does, select peripheral devices and/or components in the PD to de-power or operate at reduced power so that its operation stays within the allocated amount of power. For example, a PD, which is an AP, may choose to de-power a camera attached to the AP or de-power one or more receivers or transmitters in the AP to avoid using more than the allocated amount of power. 
     The voltage, current, and/or temperature measuring steps may be performed periodically, e.g., every 30 seconds, based on some sort of schedule or as power requirements or measured values change. By providing a PSE such as a PoE switch with information about the voltage, current, and/or temperature at the PD to which power is being supplied, the PSE can make more accurate determinations of the amount of required power to a requesting PD and/or increase the reliability of the system by supplying the amount of power needed to overcome transmission losses to devices which may be located at any of a variety of different distances away from the PSE. 
     A exemplary method, in accordance with some embodiments, comprises: measuring, in an access point, an input current for the access point; measuring, in the access point, a voltage on a Power Over Ethernet (PoE) power input of the access point; determining, in the access point, based on the measured current, measured voltage, and information about power requirements of access point components or devices coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested; and communicating, from the access point, a power request to a Power Sourcing Equipment (PSE) indicating the determined power requirement. 
     An exemplary access point, in accordance with some embodiments, comprises: a plurality of wireless interfaces; a Power over Ethernet (PoE) power input; one of a: current sense resistor or an inductive current sensor for measuring the input current to the access point provided via the POE power input; a voltage measurement device for measuring at least one of: i) a voltage on a Power Over Ethernet (PoE) power input of the access point or ii) a voltage drop across said sense resistor; a processor configured to determine, in the access point, based on the measured current, measured voltage, and information about power requirements of access point components or devices coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested; and an interface for communicating, from the access point, a power request to a Power Sourcing Equipment (PSE), the power request indicating the determined power requirement. 
     While various features discussed in the summary are used in some embodiments it should be appreciated that not all features are required or necessary for all embodiments and the mention of features in the summary should in no way be interpreted as implying that the feature is necessary or critical for all embodiments. 
     Numerous additional features and embodiments are discussed in the detailed description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a drawing of an exemplary communications system including a Power Sourcing Equipment (PSE), a plurality of wireless access points (APs), each AP coupled to the PSE via a Power over Ethernet (PoE) cable, and a plurality of user equipment (UE) devices, in accordance with an exemplary embodiment. 
         FIG. 2  is a drawing of a portion of an exemplary communications system including a power sourcing equipment (PSE) coupled to a wireless access point (AP) via a Power over Ethernet (PoE) cable, in accordance with an exemplary embodiment, said wireless access point implemented to measure access point input current using a sense resistor, determine an amount of power to be requested based on the measured current, and communicate a power request to the PSE. 
         FIG. 3  is a drawing of a portion of an exemplary communications system including a power sourcing equipment (PSE), e.g., a network switch, coupled to a wireless access point (AP) via a Power over Ethernet (PoE) cable, in accordance with an exemplary embodiment, said wireless access point implemented to measure access point input current using an inductive current sensor, determine an amount of power to be requested based on the measured current determine an amount of power to be requested based on the measured current, and communicate a power request to the PSE. 
         FIG. 4A  is a first part of an exemplary method of operating a communications system including a wireless access point coupled to a PSE via a PoE cable, in accordance with an exemplary embodiment, said exemplary method including power control related operations. 
         FIG. 4B  is a second part of an exemplary method of operating a communications system including a wireless access point coupled to a PSE via a PoE cable, in accordance with an exemplary embodiment, said exemplary method including power control related operations. 
         FIG. 4  comprising the combination of  FIG. 4A  and  FIG. 4B . 
         FIG. 5A  is a drawing of a first part of an exemplary assembly of components which may be included in an exemplary wireless access point in accordance with an exemplary embodiment. 
         FIG. 5B  is a drawing of a second part of an exemplary assembly of components, which may be included in an exemplary wireless access point in accordance with an exemplary embodiment. 
         FIG. 5  comprises the combination of  FIG. 5A  and  FIG. 5B . 
         FIG. 6  is a drawing of exemplary data/information which may be included in a wireless access point in accordance with an exemplary embodiment. 
         FIG. 7  is a drawing of an exemplary assembly of components, which may be included in an exemplary wireless access point in accordance with an exemplary embodiment. 
         FIG. 8  is a drawing of exemplary data/information which may be included in an exemplary power sourcing equipment (PSE), e.g., a network switch, in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a drawing of an exemplary communications system  100  including a Power Sourcing Equipment (PSE)  102 , e.g., a network switch, a plurality of wireless access points (APs) ( 104 ,  106 ,  108 , . . .  110 ), each AP coupled to the PSE  102  via a Power over Ethernet (PoE) cable, and a plurality of user equipment (UE) devices, in accordance with an exemplary embodiment. The plurality of wireless access points include wireless access point  1   104 , wireless access point  2   106 , wireless access point  2   106 , wireless access point  3   108 , and wireless access point n  110 . In the exemplary system  100  of  FIG. 1 , each of the wireless access points ( 104 ,  106 ,  108 , . . .  110 ) is a WiFi/Bluetooth, e.g., Bluetooth Low energy, access point, which is an Ethernet Powered Device (PD). In some embodiments, different APs coupled to the PSE  102  have different capabilities, e.g., different types of radios, different numbers of radios, different external ports for powering additional powered devices and/or different power requirements. 
     Wireless access point  1   104  is coupled to PSE  102  via Power over Ethernet (PoE) cable  105 . Wireless access point  2   106  is coupled to PSE  102  via Power over Ethernet (PoE) cable  107 . Wireless access point  3   108  is coupled to PSE  102  via Power over Ethernet (PoE) cable  109 . Wireless access point n  110  is coupled to PSE  102  via Power over Ethernet (PoE) cable  111 . In some embodiments, at least some of the PoE cables ( 105 ,  107 ,  109 ,  111 ) are different lengths. 
     System  100  includes a plurality of user equipment (UE) devices including (UE  1 A  120 , UE NA  122 , UE  1 B  124 , UE NB  126 , UE  1 C  128 , UE NC  1   130 , UE  1 D  132 , UE ND  134 ). At least some of the UEs ( 120 ,  122 ,  124 ,  126 ,  128 ,  130 ,  132 ,  134 ) are wireless device which may move around the communications system and be connected to different wireless access points at different times. In the example of  FIG. 1 , UE  1 A  120  and UE NA  122  are shown as being coupled to wireless access point  1   104  via wireless links  121 ,  123 , respectively. In the example of  FIG. 1 , UE  1 B  124  and UE NB  126  are shown as being coupled to wireless access point  2   106  via wireless links  125 ,  127 , respectively. In the example of  FIG. 1 , UE  1 C  128  and UE NC  130  are shown as being coupled to wireless access point  3   108  via wireless links  129 ,  131 , respectively. In the example of  FIG. 1 , UE  1 D  132  and UE ND  134  are shown as being coupled to wireless access point  4   110  via wireless links  133 ,  135 , respectively. 
     There may be, and sometimes are one or more external devices connected to an access point which can be, and sometimes are powered, e.g., conditionally powered, by the access point. One or more of external devices (device  1   a    140 , . . . , device Na  142 ) may be, and sometimes are, connected to AP  1   104 , and powered, e.g., conditionally powered, by AP  1   104 . One or more of external devices (device  1   b    144 , . . . , device Nb  146 ) may be, and sometimes are, connected to AP  2   106 , and powered, e.g., conditionally powered, by AP  2   106 . One or more of external devices (device  1   c    148 , . . . , device Nc  150 ) may be, and sometimes are, connected to AP  3   108 , and powered, e.g., conditionally powered, by AP  2   106 . One or more of external devices (device  1   d    152 , . . . , device Nd  154 ) may be, and sometimes are, connected to AP n  110 , and powered, e.g., conditionally powered, by AP n  110 . 
     In the exemplary system  100  of  FIG. 1 , at least one of the wireless access points ( 104 ,  106 ,  108 ,  110 ) includes the capability to measure input current, measure input voltage. determine, based on the measured current, measured voltage and information about power requirements of access point components or devices coupled to the access point, a power requirement of the access point, and communicate a power request to a Power Sourcing Equipment (PSE) indicating the determined power requirement. In some such embodiments, the access point further communicates: i) measured input voltage and measured input current, or ii) measured input power, to the PSE, which allocates power grants to the access point based on information received from the access point. 
       FIG. 2  is a drawing of a portion  200  of an exemplary communications system including a power sourcing equipment (PSE)  201 , e.g., a network switch, coupled to a wireless access point (AP)  202 , e.g. a WiFi/Bluetooth AP, which is a powered device (PD), via a Power over Ethernet (PoE) cable  203 . In one exemplary embodiment PSE  201  of  FIG. 1  is PSE  102  of  FIG. 1 , wireless access point  202  of  FIG. 2  is one of the wireless APs ( 102 ,  104 ,  106 ,  110 ) of  FIG. 1 , and PoE cable  203  of  FIG. 2  is a corresponding one of the PoE cables ( 105 ,  107 ,  109 ,  111 ) of  FIG. 1 , respectively. 
     PSE  201  includes a PoE plus (PoE+) interface  204 , a transmitter  205 , a DC power supply  206 , a receiver  207 , a processor  208 , an assembly of hardware components  2081 , e.g., an assembly of circuits, and memory  209 . The transmitter  205 , DC power supply  206 , receiver  207 , processor  208 , assembly of components  2081  and memory  209 , are coupled together via a bus  210 , over which the various components may exchange data and information. PoE+ interface  204  includes TX+ connection point  211 , a TX− connection point  212 , a first B+ connection point  213 , a second B+ connection point  214 , a first B− connection point  215 , a second B− connection point  216 , a RX+ connection point  217  and a RX− connection point  218 . The TX+/TX− connection point pair ( 211 ,  212 ) is coupled to the transmitter  205 . The two B+ connection points ( 213 ,  214 ) are coupled together and connected to a high side output of DC power supply  206 . The two B− connection points ( 214 ,  215 ) are coupled together and connected to a low side output of DC power supply  206 , which is connected to PSE ground  290 . 
     Wireless AP  202  includes PoE+ interface  219 , receiver  220 , wireless interfaces (I/Fs)  221 , transmitter  222 , processor  223 , e.g., a CPU, an assembly of components (AOC)  2231 , e.g. an assembly of hardware components, e.g., circuits, and memory  224 . Memory  224  includes a current determination component  224 , e.g. a current determination routine, and a power determination component  245 , e.g., a power determination routine. The receiver  220 , wireless interfaces (I/Fs)  221 , transmitter  222 , processor  223 , and memory  224  are coupled together via a bus  2210  over which the various elements may interchange data and information. Wireless AP  202  further includes a sense resistor  235 , a filter circuit  226 , Dc/DC convertor  227 , monitoring device  228 , and a reference voltage generation circuit  225 , coupled together as shown in  FIG. 2 . Filtering circuit  226  includes a common mode choke  246 , and capacitors  247 ,  248 ,  249 . 
     Monitoring device  228 , e.g., an integrated circuit chip, includes a voltage measurement device  250 , a temperature sensing device  251 , an analog to digital converter  252 , a processor  253 , memory  254  and a digital I/O interface  255 , e.g., a I2C interface, coupled together as shown in  FIG. 2 . The digital I/O interface includes a clock input  256 , and a Data input/output (I/O)  257 . In some embodiments, monitoring device  228  is, e.g., an integrated circuit chip such as, e.g., a high-side current-sense amplifier with an Analog-to-Digital Converter (ADC) and Operational amplifier (Op Amp) and gain block. 
     Wireless I/Fs  221  includes four wireless radios (WiFi radio  1   259 , WiFi radio  2   260 , WiFi radio  3   261 , Bluetooth Low Energy (BLE) radio  262 ). In some embodiments, each wireless radio ( 259 ,  260 ,  261 ,  262 ) is considered a wireless interface. WiFi radio  1   259 , e.g., a 2.4 GHz radio, includes a wireless receiver  2591 , a wireless transmitter  2592  and power control circuitry  255 . WiFi radio  2   260 , e.g., a 5 GHz radio, includes a wireless receiver  2601 , a wireless transmitter  2602  and power control circuitry  266 . WiFi radio  3   261 , e.g., a dual band radio, includes a wireless receiver  2611 , a wireless transmitter  2612  and power control circuitry  267 . BLE radio  262  includes a wireless receiver  2621 , a wireless transmitter  2622  and power control circuitry  268 . At different times different sets of wireless radios or different sets of transmitters of the wireless radios may be powered on (energized) or powered off (de-energized). Each of the radios ( 259 ,  260 ,  261 ,  262 ) of the wireless interface  221  may be, and sometimes is, coupled to one or more of a plurality of antenna (antenna  1   263 , . . . , antenna M  264 ), via which the receivers ( 2591 ,  2601 ,  2611 ,  2621 ), respectively, may receive wireless signals, e.g., from UE devices. Each of the radios ( 259 ,  260 ,  261 ,  262 ) of the wireless interfaces  221 , may be, and sometimes is, coupled to one or more of the plurality of antenna (antenna  1   263 , . . . , antenna M  264 ), via which the transmitters ( 2592 ,  2602 ,  2612 ,  2622 ), respectively may transmit wireless signals, e.g., to UE devices. Different WiFi radios may, and sometimes do, use different antennas. In some embodiments, different antennas are used for transmit and receive. In some embodiments, at least some of the WiFi radios ( 259 ,  260 ,  261 ,  262 ) support MIMO operations. In some embodiments, wireless radios, wireless radio transmitters, and/or MIMO circuitry can be, and sometimes are, selectively de-energized to reduce power, e.g., via power control circuitry ( 265 ,  266 ,  267 ,  268 ), e.g., under the direction of processor  223 . 
     PoE+ interface  219  includes RX+ connection point  236 , a RX− connection point  237 , a first B+ connection point  238 , a second B+ connection point  239 , a first B− connection point  240 , a second B− connection point  241 , a TX+ connection point  242  and a TX− connection point  243 . The RX+/RX− connection point pair ( 236 ,  237 ) is coupled to the receiver  220 . The two B+ connection points ( 238 ,  239 ) are coupled together and connected to an input side of current sense resistor  235 . The output side of the current sense resistor  235  is connected to an input high side of the common mode choke  246  of the filter circuit. The two B− connection points ( 240 ,  241 ) are coupled together and connected to a Power Device (PD) ground (GND)  291  and to an input low side of the common mode choke  246  of the filter circuit. The Hi side output of the common mode choke is connected to the Hi side input of the DC/DC converter  227 . The low side output of the common mode choke  246  is connected to forward ground  292  and to the low side input of the Dc/DC convertor. The DC/DC converter  227  generates a plurality of DC voltages (V 1 , V 2 , . . . VN)  297  which are output to power the wireless access points internal components and devices, external to the wireless access point, which are being powered by the wireless access point, e.g., USB powered devices, Internet of Things (IoT) devices, and/or an additional PoE Powered Device, e.g., another wireless base station or another type of PoE PD. 
     Wireless access point  202  further includes Internet of Things (IoT) ports  229  coupled to IoT port circuitry  230 . IoT port circuitry  230  includes detection circuitry  230 , sometimes referred to as sense (S) circuitry, for detecting: one of more of the following: i) if one or more IoT devices are connected to the IoT ports, ii) the number of IoT connected devices, iii) information used to identify and/or characterize the type of device detected, e.g., in terms of power draw, or iv) a measured level of power draw. IoT port circuitry  230  further includes power control circuitry  275 , e.g., activating or de-activating a IoT device, e.g., de-powering a connected IoT device, under control of processor  223  to reduce power draw. One or more IoT devices (device  1 B  269 , . . . , device NB  270 ) may, be and sometimes are coupled to the access point  202  via IoT ports  229 . 
     Wireless access point  202  further includes a module ports  231  coupled to module port circuitry  232 . Module port circuitry  232  includes detection circuitry  276 , sometimes referred to as sense (S) circuitry, for detecting: one of more of the following: i) if a powered device, e.g., a PoE Powered Device is connected to the module port ii) information used to identify and/or characterize the type of device detected, e.g., in terms of power draw, or iii) a measured level of power draw. Module port circuitry  232  further includes power control circuitry  279 , e.g., for activating or de-activating a PD, e.g., de-powering a connected PD, under control of processor  223  to reduce power draw. A PD  271 , e.g., another PoE access point or another type of PD may, be and sometimes is coupled to the access point  202  via module ports  231 . 
     Wireless access point  202  further includes USB ports  233  coupled to USB ports circuitry  234 . USB ports circuitry  234  includes detection circuitry  278 , sometimes referred to as sense (S) circuitry, for detecting: one of more of the following: i) if one or more USB devices are connected to the IoT ports, ii) the number of USB connected devices, iii) information used to identify and/or characterize the type of device(s) detected, e.g., in terms of power draw, or iv) a measured level(s) of power draw. USB ports circuitry  234  further includes power control circuitry  279 , e.g., for activating or de-activating a USB device, e.g., de-powering a connected USB device, under control of processor  223  to reduce power draw. One or more USB devices (external device  1 A  272 , . . . , external device NA  273 ) may, be and sometimes are coupled to the access point  202  via USB ports  233 . 
     PoE+ cable  203  includes line  280  which connects TX+  211  of PSE  201  to RX+  236  of access point  202 . PoE+ cable  203  further includes line  281  which connects TX−  212  of PSE  201  to RX−  237  of access point  202 . Power allocation message signals  288 , which generated and sent by transmitter  205  of PSE  201 , are communicated via cable line pair ( 280 ,  2281 ) of cable  203 , to wireless access point  202 , and the signals are received by receiver  230  of the access point  202 . The receiver  220  communicates the received power allocation message  288  to processor  223 . 
     PoE+ cable  203  further includes line  282  which connects B+  213  of PSE  201  to B+  238  of access point  202 . PoE+ cable  203  further includes line  283  which connects B+  214  of PSE  201  to B+  239  of access point  202 . PoE+ cable  203  further includes line  284  which connects B−  215  of PSE  201  to B−  240  of access point  202 . PoE+ cable  203  further includes line  285  which connects B−  216  of PSE  201  to B−  241  of access point  202 . Power is supplied from PS  201  to wireless access point via lines ( 282 ,  283 ,  284 ,  285 ), e.g., with 2 lines ( 282 ,  283 ) being the high side and two lines ( 285 ,  285 ) being the Low or return side. In some embodiments, only 2 lines are used to supply power (one B+ line and one B− line), rather than 4 lines. The embodiment with 4 power lines can support higher power levels than the embodiment with only 2 power lines. 
     The input voltage (VIN)  299  of the wireless access point  202  is shown across the common connection point of B+  238  and B+  239  with respect to the common connection point of B−  240  and B−  241 . The input voltage (VIN)  299  of the access point  202  is measured by the access point. The input current TIN  298 , which is the current through current sense resistor  235 , is also measured by the access point  202 . In this exemplary embodiment, the voltage measurement device  250  of measurement device, receives as inputs V+ and V−, which are sense points one both sides of sense resistor  250 . Voltage measurement device  250  measures the voltage drop across sense resistor  235 , e.g. (the value of V+ with respect to PD In GND)−(the value of V− with respect to PD In GND). The measured voltage drop across the sense resistor is output from voltage measurement device, e.g., a voltage measurement circuit, and input to ADC  252 , where the analog measurement is converted to a digital value. The digital value representing the voltage drop across the sense resistor is input to processor  253 . In some embodiments, the monitoring device  228  knows the value of the sensor resistor  235 , and computes an input current, e.g., where input current=measured voltage drop across sense resistor/value of the sense resistor. In other embodiments, the monitoring device  228  is not aware of the value of the sense resistor and outputs the measured voltage drop across the sense resistor or a scaled value corresponding to the measured voltage drop across the sense resistor to process or  233 , which determines the input current. For example, the CPU  223  retrieves the value of the sense resistor, which is stored in memory, and CPU  223  calculates the value of the input current, where input current=voltage drop across the sense resistor/sense resistor value. 
     In some embodiments, the voltage measurement device  250  measures the input voltage Vin  299 , which is V+ with respect to PD IN GND, directly, outputs, the analog measurement to the ADC  252 , which converts it to a digital representation, forwards the result to the processor  253 , which sends the measured voltage in a message to CPU  223 . 
     In some embodiments, the voltage measurement device  250  measures an average voltage of V+ and V−, sometimes referred to as an input common mode voltage for device  228 , sends the measured average voltage to ADC  252 , where the ADC converts the analog measurement to a digital representation. Then the result is forwarded to the processor  253 , which sends the average voltage (common mode input voltage) to CPU  223  in a message. In some embodiments, processor  223  uses the average voltage (common mode input voltage) as a reasonable representation of VIN, since the voltage drop across the sense resistor is relatively small. In other embodiments, the CPU  223  adjusts the received average voltage (common mode input voltage) taking into account the voltage drop across the sense resistor, based on the measured current through the sense resistor and the known value of the sense resistor. 
     Temperature sensing device  251 , e.g., a temperature sensing circuit including a calibrated temperature sensitive component, e.g., resistor with a known resistance vs temperature curve, or a thermocouple, measures the temperature of access point  202  and outputs and analog signal indicative of the measured temperature to ADC  252 , which converts the analog signal to a digital representation of the temperature, and sends the digital representation to processor  253 . In some embodiments, access point power use increases as temperature increases, e.g., because one or more cooling fans are turned-on and/or operate at a higher on/off duty cycle ratio. 
     Clock input  256  of Digital I/O interface  255  receives clock signals  293  from processor  233 . Serial data line  294  couples Data I/O  257  of monitoring device  228  to processor  223 . Exemplary signals  295  sent from processor  228  to Data I/O  257  over serial I/O  294  include configuration and control messages, e.g., messages selecting types of measurements to be performed, rates of measurements to be performed, scale factors to be used, which messages are to be output, rate of messages to be output, and format of output messages. Exemplary signals  296  sent from data I/O  257  to processor  223  include, e.g., a messages communicating a measured or determined current, a message communicating measured voltage, a message communicating a voltage drop across the sense resistor, a message communicating a common mode input voltage, and a message communicating a measured temperature at the access point. 
       FIG. 2  has been described for an embodiment in which 4 lines are used for power (two B+ lines and two B− lines). In some embodiments, only two lines are used for power (one B+ line and one B− line).  FIG. 2  has been described for an exemplary implementation using PoE+; however, the methods and apparatus described in this application are also well suited for other Power over Ethernet implementations, e.g., an earlier PoE implementation using lower maximum power levels than PoE+, or a newer PoE implementation using higher maximum power levels than PoE+. 
       FIG. 3  is a drawing of a portion  300  of an exemplary communications system including a power sourcing equipment (PSE)  201 , e.g., a network switch, coupled to a wireless access point (AP)  202 ′, e.g. a WiFi/Bluetooth AP, which is a powered device (PD), via a Power over Ethernet (PoE) cable  203 . In one exemplary embodiment PSE  201  of  FIG. 3  is PSE  102  of  FIG. 1 , wireless access point  202 ′ of  FIG. 3  is one of the wireless APs ( 102 ,  104 ,  106 ,  110 ) of  FIG. 1 , and PoE cable  203  of  FIG. 3  is a corresponding one of the PoE cables ( 105 ,  107 ,  109 ,  111 ) of  FIG. 1 , respectively. 
       FIG. 3  is similar to  FIG. 2 ; however, wireless access point  202 ′ of  FIG. 3  is slightly different from wireless access point  202  of  FIG. 2 . The difference between access point  202  of  FIG. 2  and access point  202 ′ of  FIG. 3  will now be described. Access point  202  of  FIG. 2  includes a sense resistor  235  and monitoring device  228  performs a voltage drop measurement across sense resistor  235 , which is used to measure input current IIN  298 . Access point  202 ′ of  FIG. 3  does not include sense resistor  235 , but rather includes an inductive current sensor  235 ′, e.g. an inductive pick-up, around an input power feed line as shown in  FIG. 3 , and monitoring device  228 ′ includes a current measurement device  2501 , which is coupled to inductive current sensor  235 ′, which determines a current value based on the received signal from the inductive current sensor  235 ′. The current measurement device  2501  outputs an analog signal indicative of the input current to ADC  252 , which converts the analog measurement to a digital value, which is sent to processor  253 . Voltage measurement device  250 ′ of monitoring device  228 ′ measures Vin  299  and outputs an analog signal indicative of the measured voltage to the ADC  252 , which converts the analog measurement to a digital value, which is sent to processor  253 . 
       FIG. 4 , comprising the combination of  FIG. 4A  and  FIG. 4B , is a flowchart  400  of an exemplary method, e.g., a method of operating a communications system including a Power Sourcing Equipment (PSE) and an access point which is a Powered Device (PD), in accordance with an exemplary embodiment. Operation starts in step  402  in which the communications system is powered on and initialized. Operation proceeds from step  402  to step  404 . 
     In step  404  an access point measures, at the access point, an input current for the access point. In some embodiments, step  404  includes step  406 ; while in other embodiments, step  404  includes step  408 . 
     In step  406  the access point measures, in the access point, a current through a sense resistor, said sense resistor being in series with a power over Ethernet (PoE) power input of the access point. In some embodiments, step  406  includes steps  410  and  412 . In step  410  the access point measures a voltage drop across said sense resistor. Operation proceeds from step  410  to step  412 . In step  412  the access point determines the current based on the voltage drop across the sense resistor and the known value of the sense resistor. For example, current (in amps)=measured drop across the sensor resistor (in volts)/value of sense resistor (in ohms). 
     In step  408  the access point measures, in the access point, a current through an input power feed line coupled to a power over Ethernet (PoE) power input of the access point, said current measurement being performed using an inductive sensor. 
     Operation proceeds from step  404  to step  414 . In step  414  the access point measures, in the access point, a voltage on a power over Ethernet (PoE) power input of the access point. For example, the access point measures the on the B+ power input line with respect to ground (e.g., the B− power input line). 
     Steps  416 ,  418 , and  420  are optional steps. In some embodiments, one or more or all of steps  416 ,  418 , and  420 , are performed. In some embodiments, one or more or all of optional steps  416 ,  418 , and  420  are not performed, and the step is bypassed in the sequence of steps. The flow will now be described for an embodiment, in which each of steps  416 ,  418  and  420  are performed. Operation proceeds from step  414  to step  416 . In step  416 , the access point measures, a temperature at the access point. Operation proceeds from step  416  to step  418 , In step  418  the access point, determines a number of wireless transmitters to be powered on based on a traffic load to be communicated. In some embodiments, the determination of the number of wireless transmitter to be powered on is further based on the device capabilities of user devices to be serviced by the access point. Operation proceeds from step  418  to step  420 . In step  420  the access point detects peripheral devices attached to the access point. Operation proceeds from step  420  to step  422 . 
     In step  422  the access determines, based on the measured current, measured voltage, and information about power requirements of access point components or devices, e.g., peripheral devices, coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested. In some embodiments, the devices coupled to the access point include one or more of: another PD, e.g., an additional PoE AP or another type of PoE coupled to the access point via a module port, one or more USB powered devices coupled to the access point via a USB port, or one or more Internet of Things (IoT) devices coupled to the access point via a IoT port. 
     In some embodiments, step  422  includes one or more or all of steps  424 ,  426  and  428 . In step  424  the access point determines the power requirement of the access point based on the measured temperature in addition to the measured current, measured voltage and the power requirements of access point components or devices coupled to the access point. In step  426  the access point determines the amount of power to be requested based on the determined number of wireless transmitters to be powered on. In step  428  the access point determines the amount of power to be requested based on the peripheral devices which are detected as being attached to the access point. 
     Operation proceeds from step  422 , via connecting node A  430 , to step  432 . In step  432  the access point communicates, from the access point, at least one of: the measured current and measured voltage or ii) measured power to the power sourcing equipment (PSE), wherein the measured power equals the measured voltage multiplied by the measured current. Operation proceeds from step  432  to step  434 . In step  434  the access point communicates from the access point, a power request to the power sourcing equipment (PSE) indicating the determined power requirement. Operation proceeds from step  434  to step  436 . 
     In step  436  the PSE determine at least one of: a current, a voltage or power to apply to the power lines used to supply power to the access point based on the requested amount of power and at least one of: i) the communicated measured current and measured voltage or ii) the communicated measured power. For example, the PSE can take in consideration voltage drop/power loss on the line to determine the power to be applied at the PSE, e.g., the access point may not be aware of the amount of line loss, but once i) AP measured current and AP measured voltage or ii) AP measured power is reported to the PSE, the PSE can factor into its power calculations the power loss since the PSE measures voltage at its location on the lines being used to supply power to the AP. Operation proceeds from step  436  to step  438 . 
     In step  438 , the access point receives a response to said power request, said response being sent from said PSE. Operation proceeds from step  438  to step  440 . 
     In step  440  the access point determines if the received response indicates a power grant that is less than the determined amount of power that was previously requested by the access point. If the access point determines the received response indicates a power grant that is less than the determined amount of power that was requested by the access point, then operation proceeds from step  440 , to step  442 ; otherwise, operation proceeds from step  440 , via connecting node B  446  to step  404 . 
     In step  442  the access point selects one or more access point components or devices coupled to the access point to de-power, when said response from the PSE indicated a power grant less that the amount of power that was requested. Operation proceeds from step  442  to step  444 . In step  444  the access point de-powers the selected one or more access point components or devices coupled to said access point. Operation proceeds from step  444 , via connecting node B  446 , to step  402 . The access point proceeds through the steps of the flowchart again, repeating the previously described steps, e.g., including the steps of: measuring input current for the access point (repeat step  402 ), measuring voltage on a PoE power input of the access point (repeat step  404 ), determining based on the measured current, measured voltage, and information about power requirements of access point components or devices coupled to the access point, an amount of power to be requested (repeat step  422 ), communicating at least one of: the measured current and measured voltage or ii) measured power to the power sourcing equipment (PSE) (repeat step  432 ), and communicating the power request to the PSE (repeat step  434 ), etc. 
     In various embodiments, the access point is a powered device (PD). In some such embodiments, the access point is powered by the PSE. In some such embodiments, the PSE supports PoE plus (PoE+) and the access point is a PoE+ device. 
       FIG. 5 , comprising the combination of  FIG. 5A  and  FIG. 5B , is a drawing of an exemplary assembly of components  500 , comprising part A  501  and Part B  503 , which may be, and sometimes is, included in an exemplary wireless access point in accordance with an exemplary embodiment. Exemplary assembly of components  500 , which may be included in a wireless access point which is a power device (PD) such any of the exemplary wireless access points ( 104 ,  106 ,  108 ,  110  of  FIG. 1 , wireless access point  202  of  FIG. 2 , and/or wireless access point  202 ′ of  FIG. 3 , implement steps of an exemplary method, e.g., steps of the method of the flowchart  400  of  FIG. 4 , which are performed by a wireless access point. 
     Assembly of components  500  can be, and in some embodiments is, used in a wireless access point of  FIG. 1 , e.g. wireless access point  1   104  of  FIG. 1 , wireless access point  202  of  FIG. 2  and/or wireless access point  202 ′ of  FIG. 3 . The components in the assembly of components  500  can, and in some embodiments are, implemented fully in hardware within the processor  223 , e.g., as individual circuits. The components in the assembly of components  500  can, and in some embodiments are, implemented fully in hardware within the assembly of components (AOC)  2231 , e.g., as individual circuits corresponding to the different components. In other embodiments some of the components are implemented, e.g., as circuits, within the processor  223  with other components being implemented, e.g., as circuits within assembly of components  2231 , external to and coupled to the processor  223 . As should be appreciated the level of integration of components on the processor and/or with some components being external to the processor may be one of design choice. Alternatively, rather than being implemented as circuits, all or some of the components may be implemented in software and stored in the memory  224  of the wireless access point, with the components controlling operation of the wireless access point to implement the functions corresponding to the components when the components are executed by a processor, e.g., processor  223 . In some such embodiments, the assembly of components  500  is included in the memory  224 . In still other embodiments, various components in assembly of components  500  are implemented as a combination of hardware and software, e.g., with another circuit external to the processor  223  providing input to the processor  223  which then under software control operates to perform a portion of a component&#39;s function. While processor  223  is shown in the  FIGS. 2 and 3  embodiments as a single processor, e.g., computer, it should be appreciated that the processor  223  may be implemented as one or more processors, e.g., computers. 
     When implemented in software the components include code, which when executed by the processor  223 , configure the processor  223  to implement the function corresponding to the component. In embodiments where the assembly of components  500  is stored in the memory  224 , the memory  224  is a computer program product comprising a computer readable medium comprising code, e.g., individual code for each component, for causing at least one computer, e.g., processor  223 , to implement the functions to which the components correspond. 
     Completely hardware based or completely software based components may be used. However, it should be appreciated that any combination of software and hardware, e.g., circuit implemented components may be used to implement the functions. As should be appreciated, the components illustrated in  FIG. 5  control and/or configure the wireless access point, e.g., wireless access point  202  or  202 ′ or elements therein such as the processor  223 , to perform the functions of corresponding steps illustrated and/or described in the method of one or more of the flowcharts, signaling diagrams and/or described with respect to any of the Figures. Thus the assembly of components  500  includes various components that perform functions of corresponding one or more described and/or illustrated steps of an exemplary method, e.g., steps of the method of flowchart  400  of  FIG. 4  and/or described or shown with respect to any of the other figures. In some embodiments, some of the components included in assembly of components  500  are included in processor  253 , memory  254 , or in hardware components shown in  FIG. 2  or  FIG. 3 . 
     Assembly of components  500  includes a component  504  configured to operate the access point to measure, in the access point, an input current for the access point. In some embodiments, e.g., the embodiment of  FIG. 2  including wireless access point  202  which includes current sense resistor  235 , component  504  includes a component  506  configured to operate the access point to measure, in the access point, a current through a sense resistor, said sense resistor being in series with a Power over Ethernet (PoE) power input of the access point. Component  506  includes a component  510  configured to operate a voltage measurement device, e.g., voltage measurement device  250 , e.g., a voltage measurement circuit, to measure a voltage drop across said sense resistor, and a component  512  configured to determine the current based on the measured voltage drop across the sense resistor and the known value (known resistance) of the sense resistor. In some embodiments, e.g., the embodiment of  FIG. 3  including wireless access point  202 ′ which includes inductive current sensor  235 , component  504  includes a component  508  configured to control a current measurement device, e.g., current measurement device  2501 , which uses inductive current sensor  235 , to measure, in the access point, a current through an input power feed line coupled to a Power over Ethernet (PoE) power input of the access point. 
     Assembly of components  500  further includes a component  514  configured to control a voltage measure device, e.g., voltage measurement device  250  or  250 ′, which may be a voltage measurement circuit, to measure, in the access point, a voltage on a PoE power input of the access point, e.g., with respect to PD IN ground, and a component  518  configured to control a device, e.g., a temperature sensing device  251 , to measure in the access point a temperature at the access point. 
     Assembly of components  500  further includes a component  518  configured to determine a number wireless transmitters to be powered on based on a traffic load to be communicated, a component  520  configured to detect, at the access point, peripheral device(s) attached to the access point, e.g., based on input received from device detection circuits, sometimes referred to as external device sense circuits,  274 ,  276 ,  278 . 
     Assembly of components  500  further includes a component  522  configured to determine in the access point, based on the measured current, measured voltage, and information about power requirements of access point components (e.g., including TX  2592 , TX  2601 , TX  2612 , TX  2622 ) or devices (e.g., one or more of devices  259 ,  270 ,  271 ,  272 ,  283 ) coupled to the access point, a power requirement of the access point, said power requirement being an amount of power to be requested. Component  522  includes a component  524  configured to determine the power requirement of the access point based on the measured temperature in addition to the measured current, measured voltage and the power requirements of the access point or device coupled to the access point, a component  526  configured to determine the amount of power to be requested based on the number of wireless transmitters to be powered on  526 , and a component  528  configured to determine the amount of power to be requested based on the peripheral devices which are detected as being attached to the access point. 
     Assembly of components  500  further includes a component  531  configured to generate a message communicating at least one of: i) the measured current and measured voltage or ii) a measured power to the PSE, wherein the measured power equals the measured voltage multiplied by the measured current, a component  532  configured to operate the access point to send, e.g., via a transmitter  222 , to said PSE said generated message communicating at least one of: i) the measured current and the measured voltage or ii) a measured power to the PSE, wherein said measured power equals the measured voltage multiplied by the measured current, a component  533  configured to generate a message communicating a power request to the power sourcing equipment (PSE) indicating the determined power requirement, and a component  534  configured to operate the access point to send, e.g., via a transmitter  222 , to said PSE said generated message communicating from the access point, a power request, to the power sourcing equipment (PSE) indicating the determined power requirement. 
     Assembly of components  500  further includes a component  538  configured to operate the access point to receive, e.g., via a receiver  220 , a response to said power request, said response sent from the PSE, said response including a power grant to the access point. Assembly of components  500  further includes a component  540  configured to determine if the received response indicates a power grant that is less than the determined amount that was request and to control operation as a function of the determination, a component  542  configured to select one or more access point components or devices coupled to the access point to de-power, when said response from the PSE indicated a power grant less than the amount of power that was requested, and a component  544  configured to operate the access point to de-power the selected one or more access point components or devices coupled to the access point. 
     Assembly of components  500  further includes a component  546  configured to control a monitoring device, e.g., monitoring device  228  or  228 ′, included in the access point. Component  546  includes a component  548  configured to generate and send configuration and control messages to the monitoring device, a component  550  configured to generate and send a clock signal to the monitoring device, and a component  552  configured to receive messages communicating current, voltage and/or temperature from the monitoring device. Assembly of components  554  further includes a component configured to determine received power based on the input current and input voltage. 
       FIG. 6  is a drawing of exemplary data/information  600  which may be included in an exemplary wireless access point in accordance with an exemplary embodiment. Data/information  600  is, e.g., included in memory  224  of wireless access point  202  of  FIG. 2  or included in memory  224  of wireless access point  202 ′ of  FIG. 3 . 
     Data/information  600  includes, in some embodiments, e.g., the embodiment of  FIG. 2 , a resistance value  602  of the current sense resistor included in the access point which is used to measure input current. Data/information  600  further includes a generated configuration message(s) to a monitoring device including in the access point, e.g., to a monitoring chip including in the AP. Exemplary information included in a configuration message includes, e.g., information identifying, specifying or selecting measurements to be performed by the monitoring device, e.g., input voltage measurement, input current measurement, voltage drop across a sense resistor coupled to the monitoring device, monitoring device input common mode voltage, temperature, power, etc., information identifying, specifying or selecting measurement rates, information identifying specifying or selecting information to be included in output messages including, e.g. a measured voltage drop across the sense resistor, a measured input current, a measured input voltage, a measured common mode monitoring device input voltage, a measured temperature, etc., information identifying, specifying or selecting gain factors, e.g. scaling used in the messages, information identifying, specifying or selecting message format, and information identifying, specifying or selecting output message rate. 
     Data/information  600  further includes received message(s)  606  from the monitoring device included in the AP, said received messages communicating measured voltage(s), measured current, and/or measured temperature. In some embodiments, a received message  606  included measured input power, e.g., determined by the monitoring device. 
     Data/information  600  further includes received measurements for the monitoring device included in the wireless access point  608 , e.g., recovered from received messages  606 . Received measurements  608  includes one or more or all of: measured access point input voltage  610 , measured access point input current  611 , measured access point input power  612 , measured access point voltage drop across the sense resistor  613 , measured common mode monitoring device input voltage  614 , e.g., the average of the voltage on monitoring device V+ input and the voltage on monitoring device V− input, and measured temperature of the AP  616 . In some embodiments, data/information  600  further includes one or more or all of: a determined access point input voltage  618 , e.g., determined by the AP based on a measured common mode monitoring device input voltage and the determined input current, a determined access point input current  620 , e.g., determined by the AP based on the measured voltage drop across the sense resistor reported by the monitoring device and the known resistance value of the sense resistor, and a determined access point input power  622 , e.g., determined by the access point by multiplying the measured input current by the measured input voltage. 
     Data/information  600  further includes a generated message  623  to be sent to the PSE communicating measured voltage, measured current, and/or measured power, a determined or estimated traffic load  624 , a determined number of wireless transmitters to be powered on  626  based on the traffic load and/or based on device capabilities of UEs connected to the AP, information identifying detected peripheral devices attached to the AP  628 , a detected number of peripheral devices attached to the AP  630 , information characterizing the detected peripheral devices, e.g., including power load information, temperature vs power information  634 , e.g., to be used in the power request determination with the measured temperature, internal access point components vs power information  636 , e.g., information specifying amounts of power corresponding to one or more internal AP components such as wireless radios or wireless transmitters included in wireless radios, which may be, and sometimes are, selectively de-powered. 
     Data/information  600  further includes a determined amount of power to be requested  638 , a generated power request message  640  to be sent to the PSE, a received response message from the PSE including a power grant to the AP  642 , a determination as to whether or not the grant is less than the requested power level  644 , a selected set of access point components and/or external devices coupled to the AP, which are to be de-powered or not received power, in response to the grant being less than the requested power level, and generated control signals to de-power selected AP components and/or external devices coupled to the access point  648 . 
       FIG. 7  is a drawing of an exemplary assembly of components  700  which may be, and sometimes is, included in an exemplary power sourcing equipment (PSE), e.g., a network switch, in accordance with an exemplary embodiment.  FIG. 7  is a drawing of an exemplary assembly of components  700 , which may be, and sometimes is, included in an exemplary Power Sourcing Equipment (PSE), e.g., a network switch, in accordance with an exemplary embodiment. Exemplary assembly of components  700 , which may be included in a PSE such PSE  101  of  FIG. 1  and/or PSE  201  of  FIGS. 2 and 3 , implement steps of an exemplary method, e.g., steps of the method of the flowchart  400  of  FIG. 4 , which are performed by a power serving equipment and/or described with respect to any of the Figures. 
     Assembly of components  700  can be, and in some embodiments is, used in a PSE  101  of  FIG. 1  and/or PSE  201  of  FIG. 2  or  FIG. 3 . The components in the assembly of components  700  can, and in some embodiments are, implemented fully in hardware within the processor  208 , e.g., as individual circuits. The components in the assembly of components  700  can, and in some embodiments are, implemented fully in hardware within the assembly of components (AOC)  2018 , e.g., as individual circuits corresponding to the different components. In other embodiments some of the components are implemented, e.g., as circuits, within the processor  2018  with other components being implemented, e.g., as circuits within assembly of components  2018 , external to and coupled to the processor  208 . As should be appreciated the level of integration of components on the processor and/or with some components being external to the processor may be one of design choice. Alternatively, rather than being implemented as circuits, all or some of the components may be implemented in software and stored in the memory  209  of the power sourcing equipment, with the components controlling operation of the PSE to implement the functions corresponding to the components when the components are executed by a processor, e.g., processor  208 . In some such embodiments, the assembly of components  700  is included in the memory  209 . In still other embodiments, various components in assembly of components  700  are implemented as a combination of hardware and software, e.g., with another circuit external to the processor  208  providing input to the processor  208  which then under software control operates to perform a portion of a component&#39;s function. While processor  208  is shown in the  FIGS. 2 and 3  embodiments as a single processor, e.g., computer, it should be appreciated that the processor  208  may be implemented as one or more processors, e.g., computers. 
     When implemented in software the components include code, which when executed by the processor  208 , configure the processor  208  to implement the function corresponding to the component. In embodiments where the assembly of components  700  is stored in the memory  209 , the memory  209  is a computer program product comprising a computer readable medium comprising code, e.g., individual code for each component, for causing at least one computer, e.g., processor  208 , to implement the functions to which the components correspond. 
     Completely hardware based or completely software based components may be used. However, it should be appreciated that any combination of software and hardware, e.g., circuit implemented components may be used to implement the functions. As should be appreciated, the components illustrated in  FIG. 7  control and/or configure power sourcing equipment, e.g., PSE  101  or PSE  201  or elements therein such as the processor  208 , to perform the functions of corresponding steps illustrated and/or described in the method of one or more of the flowcharts, signaling diagrams and/or described with respect to any of the Figures. Thus the assembly of components  700  includes various components that perform functions of corresponding one or more described and/or illustrated steps of an exemplary method, e.g., steps of the method of flowchart  400  of  FIG. 4  and/or described or shown with respect to any of the other figures. 
     Assembly of comments  700  further includes a component  702  configured to operate the PSE to receive, e.g., via receiver  207 , from the access point, at least one of: i) the measured current and measured voltage it ii) a measured power to the PSE, wherein the measured power equals the measured current multiplied by the measured voltage, a component  703  configured to determine an amount of power lost on the PoE cable (e.g., power loss over power lines ( 282 ,  283 ,  284 ,  285 ) of PoE cable  203 ) coupling the PSE to the access point, e.g., based on received voltage, current, and/or power measurement information from the access point and known power supply output information at the PSE, and component  704  configured to operate the PSE to receive, e.g., via receiver  207 , from the access point, a power request indicating a determined power requirement. Assembly of components  700  further includes a component  706  configured to determine at least one of a current, voltage or power to apply to the power lines used to supply power to the access point based on the request amount of power and at least one of: the communicated measured current and measured voltage or ii) the communicated measured power. Assembly of components  700  further includes a component  708  configured to generate a response to said received power request from the access point, said response communicating a power grant to the access point, and a component  710  configured to operate the PSE to send, e.g, via transmitter  205 , said generated response to said received power request from the access point, said response communicating a power grant to the access point. Assembly of components  712  further includes a component  712  configured to operate the PSE, e.g., control DC power supply  206 , to supply power to the access point in accordance with the power grant. In some embodiments controlling the DC power supply includes adjusting the voltage level across the B+ ( 213 / 214 ) with respect to B− ( 215 / 216 ). 
       FIG. 8  is a drawing of exemplary data/information which may be included in an exemplary power sourcing equipment (PSE), e.g., a network switch, in accordance with an exemplary embodiment. Data/information  800  is, e.g., included in memory  209  of PSE  201  of  FIG. 2  or  FIG. 3 . 
     Data/information  800  includes a received message from an access point communicating measured voltage, measured current and/or measured power  802 , e.g., communicating access point measured voltage across its input power lines, access point measured input current, and/or access point measured received power. Data/information  800  further includes a received message from the access point communicating a power request from the access point  804 , a determined power loss over the PoE cable coupled the PSE to the access point  806 , and a determined amount of power to be granted to the access point  808 . 
     In some embodiments, data/information  800  includes a determined current to apply to the power lines, e.g., current to sent into one or more B+ lines to the AP, to supply power to the access point based on the requested amount of power and at least one of: i) the communicated measured current and voltage or ii) the communicated measured power  810 . In some embodiments, data/information  800  includes a determined current to voltage to the power lines, e.g., voltage to be applied across the B+ line(s) with respect to the B− line(s) coupled to the AP, to supply power to the access point based on the requested amount of power and at least one of: i) the communicated measured current and voltage or ii) the communicated measured power  812 . In some embodiments, data/information  800  includes a determined power to apply to the power lines, to supply power to the access point based on the requested amount of power and at least one of: i) the communicated measured current and voltage or ii) the communicated measured power  814 . 
     Data/information  800  further includes a response message to the access point communicating a power grant to the access point  816 , and generated control signal(s) to control the PSE to output power toward the access point in accordance with the grant, e.g., control signals to control the PSE power supply  206  to supply power to the AP in accordance with the grant. 
     The PSE, e.g., a PoE switch, receives the PoE power request from one or more PDs and, in some cases, the measured line voltage, current, and/or temperature at the requesting device. The PSE takes into consideration the received measurement information, e.g., voltage at the PD, current at the PD, and/or temperature. In some embodiments the PSE estimates the amount of power loss to the device due to transmission loss and takes this into consideration when determining the amount of power to be supplied to the requesting device. For example, the amount of power expected to be lost due to transmission may be added to the amount of power requested when determining the requesting PDs actual power needs. 
     Based on the amount of power available at the PSE, the requested amount of power and reported measurement information from one or more PDs, the PSE determines the amount of power to be provided to individual PDs requesting power. In some cases, depending on the priority of the device and/or the number of devices requesting power, the PSE may or may not grant a PD all the power it is requesting. 
     The amount of power granted to individual PDs is communicated from the PSE to the PDs to which power grants are made. The power grant may, and in some embodiments does, not take into consideration the amount of power the PD allocated to transmission loss. The amount of power indicated as being granted to a PD that is subject to a large transmission loss may be lower, e.g., one or several watts lower, than the actual amount of power allocated by the PSE. In this way. PDs can make power requests based on their actual expected needs, potentially plus some safety factor, without having to worry if they will suffer from extensive transmission power loss due to whether they are connected to the PSE by a short or long set of lines. 
     NUMBERED LIST OF EXEMPLARY METHOD EMBODIMENTS 
     Method Embodiment 1 
     A method, the method comprising: measuring ( 404 ), in an access point, an input current for the access point; measuring ( 414 ), in the access point, a voltage on a Power Over Ethernet (PoE) power input of the access point; determining ( 422 ), in the access point, based on the measured current, measured voltage, and information about power requirements of access point components or devices (e.g., peripheral devices) coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested; and communicating ( 434 ), from the access point, a power request to a Power Sourcing Equipment (PSE) indicating the determined power requirement. 
     Method Embodiment 2 
     The method of Method Embodiment 1, wherein measuring ( 404 ), in an access point, an input current for the access point includes: measuring ( 406 ), in the access point, a current through a sense resistor, said sense resistor being in series with a Power over Ethernet (PoE) power input of the access point. 
     Method Embodiment 3 
     The method of Method Embodiment 1, wherein measuring ( 402 ), in an access point, an input current for the access point includes: measuring ( 408 ), in the access point, a current through an input power feed line coupled to a Power over Ethernet (PoE) power input of the access point, said current measurement being performed using an inductive sensor. 
     Method Embodiment 4 
     The method of Method Embodiment 1, wherein said access point is a Powered Device (PD). 
     Method Embodiment 5 
     The method of Method Embodiment 4, wherein said access point is powered by said PSE. 
     Method Embodiment 6 
     The method of Method Embodiment 5, wherein said PSE supports PoE+, and wherein said access point is a PoE+ device. 
     Method Embodiment 7 
     The method of Method Embodiment 2, wherein measuring ( 406 ) a current through a sense resistor includes: measuring ( 410 ) a voltage drop across said sense resistor; and determining ( 412 ) the current based on the measured voltage drop across the sense resistor and the known value of the sense resistor. 
     Method Embodiment 8 
     The method of Method Embodiment 1, wherein said devices coupled to said access point include: one or more of: other powered PDs (an additional PoE APs or a different type of PoE device), USB powered devices, and Internet of Things (IoT) devices. 
     Method Embodiment 9 
     The method of Method Embodiment 1, further comprising: measuring ( 416 ), in the access point, a temperature at the access point; and wherein determining ( 422 ), a power requirement at the access point includes determining ( 424 ) the power requirement of the access point based on the measured temperature in addition to the measured current, measured voltage, and the power requirements of access point components or devices coupled to the access point. 
     Method Embodiment 10 
     The method of Method Embodiment 1, further comprising: communicating ( 432 ), from the access point, at least one of: i) the measured current and measured voltage or ii) a measured power to the PSE, wherein said measured power equals the measured voltage multiplied by the measured current. 
     Method Embodiment 11 
     The method of Method Embodiment 10 further comprising: operating ( 436 ) the PSE to determine at least one of a current, voltage, or power to apply to power lines used to supply power to the access point based on the requested amount of power and one of: i) the communicated measured current and measured voltage or ii) the communicated measured power. (PSE can take into consideration voltage drop/power loss on line to determine the power to be applied at the PSE, e.g., the access point may not be aware of the amount of line loss but once i) access point measured voltage and current or ii) access point measured power is reported to the PSE, the PSE can factor into its power calculations the power loss since the PSE measures voltage at its location on the lines being used to supply power to the AP). 
     Method Embodiment 12 
     The method of Method Embodiment 1, further comprising: determining ( 418 ), at the access point, a number of wireless transmitters to power on based on a traffic load to be communicated; and wherein said step of determining ( 422 ) the amount of power to be requested is further based on the determined number of wireless transmitters to be powered on ( 426 ). 
     Method Embodiment 13 
     The method of Method Embodiment 12, further comprising: detecting ( 420 ), at the access point, peripheral devices attached to said access point; and wherein said step of determining ( 422 ) the amount of power to be requested is further based on the peripheral devices which are detected as being attached to said access point ( 428 ). 
     Method Embodiment 14 
     The method of Method Embodiment 9, further comprising: receiving ( 228 ), at the access point, a response to said power request from the PSE; and selecting ( 442 ), at the access point, one or more access point components or devices coupled to the access point to de-power when said response to said power request from the PSE indicated a power grant that is less than the determined amount of power that was requested. 
     Method Embodiment 15 
     The method of Method Embodiment 14, further comprising: operating ( 444 ) the access point to de-power the selected one or more access point components or devices coupled to the access point. 
     Method Embodiment 16 
     The method of Method Embodiment 9, further comprising: repeating said steps of measuring (repeat  402 ), in said access point, an input current; measuring (repeat  404 ), in the access point, a voltage on the PoE input of the access point; determining (repeat  422 ), in the access point, based on the measured current, measured voltage, and information about power requirements of access point components or devices (e.g., peripheral devices) coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested; and communicating (repeat  434 ), from the access point, a power request to the Power Sourcing Equipment (PSE) indicating the determined power requirement. 
     NUMBERED LIST OF EXEMPLARY APPARATUS EMBODIMENTS 
     Apparatus Embodiment 1 
     An access point ( 104  or  202  or  202 ′) comprising: a plurality of wireless interfaces ( 259 ,  260 ,  261 ,  262 ); a Power over Ethernet (PoE) power input ( 238 / 239 ); one of a: current sense resistor ( 235 ) or an inductive current sensor ( 235 ′) for measuring the input current (IIN  298 ) to the access point provided via the POE power input ( 238 / 239 ); a voltage measurement device ( 250  or  250 ′) for measuring at least one of: i) a voltage (VIN  298 ) on a Power Over Ethernet (PoE) power input ( 238 / 239 ) of the access point (e.g., with respect a PoE power input low side ( 240 / 241 ) and/or PD input ground ( 291 )) or ii) a voltage drop (e.g., (value at V+)−(value at V−)) across said sense resistor ( 235 ); a processor ( 223 ) configured to determine, in the access point, based on the measured current, measured voltage, and information about power requirements of access point components or devices (e.g., peripheral devices) coupled to the access point a power requirement of the access point, said power requirement being an amount of power to be requested; and an interface ( 219 ) for communicating ( 434 ), from the access point, a power request to a Power Sourcing Equipment (PSE) ( 201 ), the power request indicating the determined power requirement. 
     Apparatus Embodiment 2 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 1, further comprising: a monitoring device ( 228  or  228 ′); and wherein said monitoring device ( 228  or  228 ′) includes said voltage measurement device ( 250  or  250 ′). 
     Apparatus Embodiment 3 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 2, wherein said monitoring device ( 228  or  228 ′) is an integrated circuit chip (e.g., chip including a high side current-sense amplifier with an integrated ADC and a gain block). 
     Apparatus Embodiment 4 
     The access point ( 104  or  202 ′) of Apparatus Embodiment 2, wherein said monitoring device ( 228 ′) further includes: a current measurement device ( 2501 ) (e.g., current measurement circuitry coupled to said inductive current sensor ( 235 ′)). 
     Apparatus Embodiment 5 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 1, further comprising: a temperature sensor ( 251 ), in the access point, for measuring a temperature at the access point; and wherein the processor ( 223 ) is further configured to use the measured temperature when determining the power requirement at the access point in addition to the measured current, measured voltage, and the power requirements of access point components or devices coupled to the access point. 
     Apparatus Embodiment 6 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 1, further comprising: a transmitter ( 222 ) for transmitting signals through said interface ( 219 ); wherein said interface ( 219 ) is a POE interface (e.g., a PoE+ interface); and wherein the processor ( 223 ) is further configured to control the transmitter ( 222 ) to send from the access point, at least one of: i) the measured current and measured voltage or ii) a measured power to the PSE, wherein said measured power equals the measured voltage multiplied by the measured current. 
     Apparatus Embodiment 7 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 6, wherein the processor ( 223 ) is further configured to: determine a number of wireless transmitters ( 2592 ,  2602 ,  2612 ,  2622 ) to power on based on a traffic load to be communicated; and use the number of wireless transmitters to be powered on as part of determining the amount of power to be requested. 
     Apparatus Embodiment 8 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 7, further comprising: a receiver ( 220 ) for receiving a response from the PSE ( 201 ) to said power request; and wherein the processor ( 223 ) is further configured to select, at the access point, one or more access point components ( 2592 ,  2602 ,  2612 ,  2622 ) or devices ( 269 ,  270 ,  271 ,  272 ,  273 ) coupled to the access point to de-power when said response to said power request from the PSE indicated a power grant that is less than the determined amount of power that was requested. 
     Apparatus Embodiment 9 
     The access point ( 104  or  202  or  202 ′) of Apparatus Embodiment 7, wherein the processor ( 223 ) is further configured to: de-power the selected one or more access point components or devices coupled to the access point. 
     Numerous variations on the above described methods and apparatus are possible. 
     The techniques of various embodiments may be implemented using software, hardware and/or a combination of software and hardware. Various embodiments are directed to apparatus, e.g., Power Sourcing Equipments (PSEs), e.g., network switches supporting Power over Ethernet, PoE powered devices, such as wireless access points, base stations, PoE cables, etc, and communications systems. Various embodiments are also directed to methods, e.g., method of controlling and/or operating a communications device or devices, e.g., PD such as a wireless access point, a PSE such as a network switch, and/or communications systems. Various embodiments are also directed to non-transitory machine, e.g., computer, readable medium, e.g., ROM, RAM, CDs, hard discs, etc., which include machine readable instructions for controlling a machine to implement one or more steps of a method. 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. 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. 
     In various embodiments devices and nodes described herein are implemented using one or more components to perform the steps corresponding to one or more methods, for example, input voltage measurement at an PoE input of a wireless AP, which is a PD, input current measurement of the current being received at the wireless AP, which is a PD, power measurement, determination of required power for a PD, determination of the number of wireless transmitters in an AP to be powered on, determination of the number of external devices coupled to an access point which are to be powered via the access point, determination as to whether or not an AP has received the previously requested amount of power in a response including a power grant, determination of cable power loss by a PSE, determination of an amount of power to be granted to a PD by an PSE, selection of components or devices to de-power within a PD in response to a power grant being less than a request, controlling power at the PSE taking inti account power loss over the PoE cable and reported measured power at the PD, signal generation, transmitting, processing, analyzing, and/or receiving steps. Thus, in some embodiments various features are implemented using components. Such components may be implemented using software, hardware or a combination of software and hardware. In some embodiments each component is implemented as an individual circuit with the device or system including a separate circuit for implementing the function corresponding to each described component. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RANI, floppy disk, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., in one or more nodes. Accordingly, among other things, various embodiments are directed to a machine-readable medium e.g., a non-transitory computer readable medium, including machine executable instructions for causing a machine, e.g., processor and associated hardware, to perform one or more of the steps of the above-described method(s). Some embodiments are directed to a device including a processor configured to implement one, multiple or all of the steps of one or more methods of the invention. 
     In some embodiments, the processor or processors, e.g., CPUs, of one or more devices, e.g., communications devices such as wireless access points, which are PoE PD devices, or PSE devices, such as network switches supporting PoE, are configured to perform the steps of the methods described as being performed by the devices. The configuration of the processor may be achieved by using one or more components, e.g., software modules, to control processor configuration and/or by including hardware in the processor, e.g., hardware modules, to perform the recited steps and/or control processor configuration. Accordingly, some but not all embodiments are directed to a communications device, e.g., user equipment, with a processor which includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. In some but not all embodiments a communications device includes a component corresponding to each of the steps of the various described methods performed by the device in which the processor is included. The components may be implemented purely in hardware, e.g., as circuits, or may be implemented using software and/or hardware or a combination of software and hardware. 
     Some embodiments are directed to a computer program product comprising a computer-readable medium comprising code for causing a computer, or multiple computers, to implement various functions, steps, acts and/or operations, e.g. one or more steps described above. Depending on the embodiment, the computer program product can, and sometimes does, include different code for each step to be performed. Thus, the computer program product may, and sometimes does, include code for each individual step of a method, e.g., a method of operating a communications device, e.g., a wireless access point which is a PoE PD, a PSE such as a network switch, which supports PoE, a communications system in which PoE is used, etc. The code may be in the form of machine, e.g., computer, executable instructions stored on a computer-readable medium such as a RAM (Random Access Memory), ROM (Read Only Memory) or other type of storage device. In addition to being directed to a computer program product, some embodiments are directed to a processor configured to implement one or more of the various functions, steps, acts and/or operations of one or more methods described above. Accordingly, some embodiments are directed to a processor, e.g., CPU, configured to implement some or all of the steps of the methods described herein. The processor may be for use in, e.g., a communications device or other device described in the present application. 
     While described in the context of a communications system including cellular, WiFi, Bluetooth and BLE, at least some of the methods and apparatus of various embodiments are applicable to a wide range of communications systems including many non-OFDM and/or non-cellular systems. 
     Numerous additional variations on the methods and apparatus of the various embodiments described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within the scope. The methods and apparatus may be, and in various embodiments are, used with CDMA, orthogonal frequency division multiplexing (OFDM), WiFi, Bluetooth, BLE, and/or various other types of communications techniques which may be used to provide wireless communications links between access nodes and wireless nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with user equipment devices, e.g., mobile nodes, using WiFi, Bluetooth, BLE, OFDM and/or CDMA. In various embodiments the wireless nodes are implemented as notebook computers, personal data assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods.