Abstract:
A system and method for enabling power over Ethernet (PoE) for legacy devices. Legacy devices often represent a large installed base of devices. This installed base of devices (e.g., mobile computing devices) may have little or no PoE functionality. It is a feature of the present invention that an external device (e.g., dongle) can be used to retrofit such an installed base of devices for use with state of the art PoE functionality.

Description:
[0001]    This application is a continuation of non-provisional patent application Ser. No. 11/960,908, filed Dec. 20, 2007, which is incorporated by reference herein, in its entirety, for all purposes. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to Power over Ethernet (PoE) and, more particularly, to a system and method for enabling PoE for legacy devices. 
         [0004]    2. Introduction 
         [0005]    The IEEE 802.3af and 802.3at PoE specifications provide a framework for delivery of power from power sourcing equipment (PSE) to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc. 
         [0006]    In the PoE process, a valid device detection is first performed. This detection process identifies whether or not it is connected to a valid device to ensure that power is not applied to non-PoE capable devices. 
         [0007]    After a valid PD is discovered, the PSE can optionally perform a power classification. In a conventional 802.3af allocation, each PD would initially be assigned a 15.4 W power classification after a Layer 1 discovery process. An optional classification process could then reclassify the PD to a lower power level. In more complex PoE schemes, a Layer 2 classification engine can be used to reclassify the PD. Layer 2 classification processes can be included in PoE systems such as 802.3af, 802.3at or proprietary schemes. In general, Layer 2 communication (e.g., LLDP) can be used to enable a determination of an amount of power to be allocated to a PD. Where a PD such as a computing device has rapidly changing power needs, the Layer 2 communication can be used to transmit various power management information relevant to the PD&#39;s current or anticipated needs. Examples of such power management information include battery information, computing device component information, external device information, user information, application information, or the like. 
         [0008]    Legacy computing devices (e.g., laptop computers) that have limited or no PoE functionality typically represent a large percentage of the installed base of devices. In rolling out PoE functionality into a corporate environment, the upgrading of the large installed base of legacy devices represents a prohibitive expense. What is needed therefore is a mechanism that enables PoE functionality for such legacy devices. 
       SUMMARY 
       [0009]    A system and/or method for enabling PoE for legacy devices, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0011]      FIG. 1  illustrates an embodiment of a PoE system. 
           [0012]      FIG. 2  illustrates an embodiment of a PoE accessory. 
           [0013]      FIG. 3  illustrates another embodiment of a PoE accessory. 
           [0014]      FIG. 4  illustrates an example mechanism of generating a power request and priority. 
           [0015]      FIG. 5  illustrates a flowchart of a process of enabling PoE for legacy devices. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention. 
         [0017]    The deployment of power over Ethernet (PoE) systems in an enterprise environment is expected to produce significant benefits. By eliminating the reliance on AC power cords, devices can be flexibly deployed throughout the enterprise environment using a single Ethernet cable for connectivity. This flexibility in deployment also produces significant cost savings as excess electrical wiring, conduits, and outlets need not be installed. 
         [0018]    As noted, one example of a device that can benefit from the installation of a PoE system is a computing device. In general, computing devices that are connected to enterprise networks are often connected on a non-permanent basis. For example, a corporate conference room can be designed with network cabling and corresponding power outlets to support the computing devices of 5-20 conference participants. With a PoE system installed, many of the power outlets can be eliminated as power can be alternatively supplied through the existing Ethernet connection. 
         [0019]    In realizing the benefits of a PoE system, a computing device would require the inclusion of certain PoE functionality.  FIG. 1  illustrates those PoE elements that would enable a computing device to operate as a PD. As illustrated, the PoE system includes power sourcing equipment (PSE)  120  that transmits power to device  130 . Power delivered by the PSE to device  130  is provided through the application of a voltage across the center taps of transformers that are coupled to a transmit (TX) pair and a receive (RX) pair of wires carried within an Ethernet cable. In general, the TX/RX pair can be found in, but not limited to structured cabling. The two TX and RX pairs enable data communication between Ethernet PHYs  110  and  131  in accordance with 10BASE-T, 100BASE-TX, 1000BASE-T, 10 GBASE-T and/or any other layer 2 PHY technology. 
         [0020]    As is further illustrated in  FIG. 1 , device  130  includes PoE module  132 . PoE module  132  includes the electronics that would enable computing device  130  to communicate with PSE  120  in accordance with a PoE standard such as IEEE 802.3af, 802.3at, legacy PoE transmission, or any other type of PoE transmission. Device  130  also includes pulse width modulation (PWM) DC:DC controller  133  that controls power FET  134 , which in turn provides constant power to load  135 . 
         [0021]    In the example of the IEEE 802.3af standard, PSE  120  can deliver up to 15.4 W of power to a plurality of PDs (only one PD is shown in  FIG. 1  for simplicity). In the IEEE 802.at specification, on the other hand, a PSE can deliver up to 30 W of power to a PD over 2-pairs or 60 W of power to a PD over 4-pairs. Other proprietary solutions can potentially deliver even higher levels of power to a PD. In general, high power solutions are often limited by the limitations of the cabling. 
         [0022]    As would be appreciated, the incorporation of PoE elements  132 ,  133 ,  134  into an installed base of computing devices would be prohibitive. This is especially true when considering that the PoE functionality does not represent a core function of the computing device, but rather a measure of convenience for users. The principles of the present invention seek to address the need to accelerate the rollout of PoE functionality in a manner that does not require an overhaul of an installed base of devices. 
         [0023]      FIG. 2  illustrates an embodiment of an accessory  210  that can be used to enhance the PoE functionality of a device. In general, the device may have no PoE functionality resident therein, or could have a lower level of PoE functionality that is sought to be upgraded. Regardless of the level of PoE functionality of the device, the principles of the present invention can be used to enhance the level of PoE functionality in a low cost manner. 
         [0024]    In general, accessory  210  is designed to provide an interface between a PSE and device  220 , which needs upgraded PoE functionality. In the illustrated embodiment, accessory  210  includes transformers  211  designed to receive the wire pairs in an Ethernet cable. The TX and RX wire pairs are passed on to Ethernet port  212 , while the center taps of transformers  211  are coupled to PD  216 . As noted above, PD  216  can include a PoE module, which contains a signature detection component that enables detection by the PSE, a power controller that controls delivery of power received from the PSE, and circuitry that enables the relay of power demand information to the PSE (e.g., via Layer 2 communication). As illustrated, the resulting power that is extracted by PD  216  from the Ethernet link is forwarded to a power port on device  220 . In one embodiment, the power port can represent a standard DC power input port on device  220 . 
         [0025]    In one embodiment, accessory  210  can be designed to simply produce a DC power output from an Ethernet input. No other communication port need be used. In one scenario, this embodiment can be used in those contexts where device  220  has no PoE functionality. For example, accessory  210  can be designed with basic 802.3af Layer 1 functionality that is designed to get as much power as possible from the PSE to deliver to device  220 . In this example, accessory  210  need contain only transformers  211  and PD  216 . In another example, accessory  210  can be designed with more advanced Layer 2 functionality to negotiate a power request on behalf of device  220 . In this example, accessory  210  could be used to augment non-existent PoE functionality or primitive Layer 1 PoE functionality in device  220 . To facilitate this type of functionality, accessory  210  would also include Ethernet port  212  and a processor (not shown) to perform the power request negotiation. In yet another example, accessory  210  can be applied to a legacy device that may already have basic two-pair PoE functionality (e.g., 802.3af). In this example, accessory  210  can be used to provide additional power via alternative pairs (e.g., 802.3at), wherein the additional amount of power can be modulated via Layer 2 communication. 
         [0026]    In another embodiment, accessory  210  can be designed to support a communication connection with device  220  in addition to the power connection discussed above. To support the communication connection, accessory  210  also includes switch  213 . In the illustrated embodiment, switch  213  is at least a three-port switch that can support Ethernet port  212 , communication port  214 , and internal port  215 . Ports  212 ,  214 , and  215  can support full duplex links such that traffic can be coming from either direction at the same time. Traffic can also be switched to two ports simultaneously. For example, internal port can add traffic to either or both of ports  212 ,  214 , or receive traffic from either or both of ports  212 ,  214 . In one example, traffic to/from Ethernet port  212  and internal port  215  can support PoE power request/priority negotiation between accessory  210  and the PSE, while traffic to/from internal port  215  and communication port  214  can support the exchange of power management information between accessory  210  and device  220 . 
         [0027]    As noted, the principles of the present invention can also be applied to legacy PDs that lack Layer 2 communication. In the embodiment of  FIG. 3 , accessory  320  can incorporate PD  322  that faces an advanced (e.g., 802.3at) PSE  310 , and PSE  324  that faces legacy (e.g., 802.3af) PD  330 . Accessory  320  can then power PSE  324 , initially requesting the power it detects on PD  330  via Layer 1, and requesting that amount of power from PSE  310  using PD  322 . In one scenario, accessory  320  can then override the hardware classification of legacy PD  330  and provide the required dynamic power, which can be negotiated over the communication channel between accessory  320  and legacy PD  330 , to advanced PSE  310  using PD  322 . 
         [0028]    In one embodiment, communication port  214  is an Ethernet port. In this embodiment, Ethernet traffic from the switch can be passed without modification from port  212  to port  214 , and on to device  220 . In other embodiments, communication port  214  can be embodied as a Bluetooth port, serial port, parallel port, USB port, or any other device-to-device communication mechanism. 
         [0029]    As noted, communication port  214  can be used to support the exchange of power management information between accessory  210  and device  220 . In one example, device  220  can be configured to provide accessory  210  with information that enables accessory  210  to determine the power needs of device  220 . For example, device  220  can be configured to transmit parameters such as battery capacity, battery life, etc. that enables accessory  210  to make a priority decision based on a priority and allocation algorithm. 
         [0030]    In another example, device  220  can be configured to perform a priority and allocation algorithm using parameters known to device  220 .  FIG. 4  illustrates an example of such a mechanism that can be implemented in software, hardware, and/or firmware. As illustrated, various power management information can be used as inputs to power need determination  410 . In this example, the power management information includes user parameters (e.g., management, engineering, admin, etc.); computing device parameters (e.g., battery capacity, battery life, system states, processor states, device states, etc.); application parameters (e.g., mode of operation, application load, etc.); IT parameters (e.g., computing device model, IT policies, performance characteristic data, etc.); and network parameters (e.g., length of cable, type of cable, etc.). With this set of power management information, power need determination  410  can then produce a power request and power priority for the device. This power request/priority information can then be communicated to accessory  210  for use in performing a power negotiation with the PSE. With this framework, device  220  plays a role in the PoE process, yet need not have the PoE hardware installed within. Device  220  can therefore leverage the various PSE deployments/upgrades without being reconfigured in hardware. Support for such PSE deployments/upgrades is enabled through the functionality of accessory  210 . 
         [0031]    To further illustrate the features of the present invention, reference is now made to the flowchart of  FIG. 5 . As illustrated, the process of  FIG. 5  begins at step  502  where the PoE accessory is attached to a device needing PoE enhancement. In one example, the attachment is based solely on a DC power connection. In another example, the attachment is based on a DC power connection and a communication connection (e.g., Ethernet, Bluetooth, serial, parallel, USB, etc.). At step  504 , the accessory is then coupled to a PSE via an Ethernet cable. 
         [0032]    The positioning of the accessory between the PSE and the device enables the accessory to act as a PD on behalf of the device. In other words, the accessory can be detected as a PD using the signature detection component incorporated within the accessory. Upon detection of the accessory as a PD, the accessory can then negotiate a power request on behalf of the device at step  506 . In one embodiment, the accessory can negotiate the power request independently of the device. In this embodiment, the accessory can request the maximum allowed power that is available from the PSE. Whatever amount of power that is approved can then be transferred to the device using the DC power connection. In another embodiment, the accessory can negotiate the power request using input from the device. In one example, the device can forward power management parameters to the accessory for determination of a power request/priority. In another example, the device can determine the power request/priority using various power management information available to the device, and forward the determined power request/priority to the accessory. Regardless of the type or amount of input that is provided by the device to the accessory, the accessory represents a low-cost mechanism of leveraging new or upgraded PoE capabilities of the PSE without requiring commensurate upgrades at the device. 
         [0033]    At step  508 , after the accessory has negotiated the power request on behalf of the device, the accessory can then extract power that is delivered to the accessory via the Ethernet cable. The power is extracted using the power controller and power FET in the accessory and delivered to the device at step  510  using the DC power connection. 
         [0034]    As has been described, the accessory of the present invention can provide the benefits of the latest PoE technologies to any type of device that needs power. These benefits can be realized without requiring a hardware upgrade of the device. Specifically, any device that has an external DC power port can potentially benefit from the principles of the present invention. 
         [0035]    These and other aspects of the present invention will become apparent to those skilled in the art by a review of the preceding detailed description. Although a number of salient features of the present invention have been described above, the invention is capable of other embodiments and of being practiced and carried out in various ways that would be apparent to one of ordinary skill in the art after reading the disclosed invention, therefore the above description should not be considered to be exclusive of these other embodiments. Also, it is to be understood that the phraseology and terminology employed herein are for the purposes of description and should not be regarded as limiting.