Patent Publication Number: US-2023155710-A1

Title: Optical network power consumption mitigation

Description:
RELATED APPLICATIONS 
     This Application is continuation of U.S. application Ser. No. 16/003,349 filed on Jun. 8, 2018, which is a continuation of U.S. application Ser. No. 13/170,413 filed on Jun. 28, 2011, which claims the benefit of U.S. Provisional Application 61/358,996 filed on Jun. 28, 2010, the contents of which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Passive Optical Networks (PONs) may be used as part of the implementation of next-generation access networks. With the large bandwidth of optical fibers, PONs can accommodate broadband voice, data, and video traffic simultaneously. Moreover, PONs can be built with existing protocols, such as Ethernet and Asynchronous Transfer Mode (ATM), which facilitate interoperability between PONs and other network equipment. 
     Transmissions wittlin a PON are typically performed between an Optical Line Terminal (OLT) and Optical Network Units (ONUs). The OLT generally resides in a Central Office (CO) and couples the optical access network to a backbone, which can be an external network belonging to, for example, an Internet Service Provider (ISP) or a local exctlange carrier. The ONU can reside in the residence or workplace of a customer and couples to the customer&#39;s network through a Customer- Premises Equipment (CPE). 
     PON communications can include downstream traffic and upstream traffic. Downstream traffic refers to the direction from an OLT to one or more ONUs, and upstream traffic refers to the direction from an ONU to the OLT. In the downstream direction, data packets may be broadcast by the OLT to all ONUs and are selectively extracted by their destination ONUs. In the upstream direction, the ONUs share channel capacity and resources, because there is generally only one link coupling the passive optical coupler to the OLT. 
     As the popularity of PONs increases, the number of deployed ONUs will increase. As a result, the power consumption of each ONU can no longer be ignored, and adding power mitigating features to ONU designs becomes increasingly important. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference number in different instances in the description and the figures may indicate similar or identical items. 
         FIG.  1    illustrates an exemplary implementation of a Passive Optical Network (PON). 
         FIG.  2    illustrates an exemplary implementation of an Optical Network Unit Transmission system. 
         FIG.  2 A  illustrates a detailed view of the laser driver introduced in  FIG.  2   . 
         FIG.  3    illustrates an exemplary downstream frame. 
         FIG.  4    illustrates an exemplary laser or optical transmitter activation and deactivation procedure. 
         FIG.  5    is an illustrative computing device that may be used to implement ttle devices, modules, apparatuses, and other hardware. 
     
    
    
     DETAILED DESCRIPTION 
     The following description describes implementations related to using an optical transmitter to transmit upstream data in a Passive Optical Network (PON). In various implementations, the optical transmitter may be designed to mitigate power consumption. For example, the optical transmitter may be designed to receive signals that may be used to energize or power on transmitter components downstream from the optical transmitter at some advance time before an upstream timeslot assigned thereto is to occur. Advance energizing or powering on of the transmitter components of the optical transmitter may be configurable to take into consideration various optical transmitter types, aging of components in the transmitter, temperature variations, and the like. The optical transmitter may also be designed to receive instructions that cause the optical transmitter to transmit an upstream data burst about or at the start of the upstream timeslot. Furthermore, the optical transmitter may be designed to receive instructions that cause the transmitter components to power down or enter a reduced power operating mode at the end or near the end of the upstream timeslot. Enabling the transmitter components of the optical transmitter a determined time before the beginning of an assigned timeslot duration may reduce the amount of power consumed by apparatuses and devices deployed in the PON. Similarly, disabling the transmitter subsystem and components of the optical transmitter after a timeslot ends may reduce the amount of power consumed by apparatuses and devices deployed in the PON. 
       FIG.  1    illustrates an exemplary implementation of a PON  100 . The PON  100  may include Optical Network Units (ONUs)  102 ,  104  and  106  coupled to an Optical Line Terminal (OLT)  108  via an optical splitter  110 . Traffic data transmission may be achieved, for example, by using Ethernet frames received and transmitted over two optical wavelengths, respectively, one for the downstream direction and another for the upstream direction. Downstream transmission from OLT  108  may be broadcast to all ONUs  102 ,  104  and  106 . Each ONU  102 ,  104  and  106  may filter its respective data according to various known techniques. The ONUs  102 ,  104  and  106  may transmit respective upstream data to the OLT  108  during different timeslots allocated by the OLT  108  for each ONU  120 . The splitter  110  may be used to split a single line into multiple lines. 
     PONs may be classified into one of the following: an ATM PON (APON), a Broadband PON (BPON), an Ethernet PON (EPON or GE-PON), and a Gigabit PON (GPON). The APON uses the ATM protocol; the BPON is designed to provide broadband services over an ATM protocol; the EPON accommodates an Ethernet protocol; and the GPON is utilized when accommodating both the ATM protocol and the Ethernet protocol. Each type of PON is a standardized technology. The PON  100  illustrated in  FIG.  1    may be suet, a standardized PON, or a PON that has yet to be standardized by a standard determining body. 
       FIG.  2    illustrates an exemplary implementation of an ONU transmission system  200 . The ONUs  102 ,  104  and  106  may be implemented to include at least the ONU transmission system  200  illustrated in  FIG.  2   . Some or all of the elements and modules illustrated in  FIG.  2    may be integrated on one chip. Alternatively, some or all of the elements illustrated may be discrete elements associated with one or more chips. 
     The ONU transmission system  200  may include a processor  202 . A storage  204 , a frame generator  208  and a laser driver, transmit physical layer or optical driver  210  may be coupled to the processor  202 . The laser driver  210  may be coupled to a laser  212 . The laser driver  210  may be capable of putting ttle laser  212  in an active or inactive state. Furthermore, the laser driver  210  may include circuitry that may be enabled, in preparation for upstream transmission of data, some period of time before the laser  212  is activated to transmit data. Such circuitry may also be disabled after the laser  212  has completed a data burst transmission. The laser  212  may be a laser diode or other type of optical transmission apparatus. 
     The ONU transmission system  200  may also include a prediction engine  214 . The prediction engine  214  may be coupled to the storage  204 , the frame generator  208  and the laser driver  210 . The prediction engine  214  may send instructions to the laser driver  210  that cause the laser driver  210  to instruct the laser  212  to transition from an inactive state to an active state, or vice versa. Furthermore, the prediction engine  214  may send instructions to the laser driver  210  to prepare or power up various circuitry of the laser driver  210  prior to activating the laser  212  to transmit data. The prediction engine  214  may also send instructions to the laser driver  210  to power down various circuitry of the laser driver  210  after deactivating the laser  212 . The prediction engine  214  may also receive or access information in the storage  204  and the frame generator  208 . The prediction engine  214  may use some of all of the information to derive the instructions that the engine  214  sends to the laser driver  210 . The laser driver  210  may incorporate a power supply that provides voltage to the laser driver  210  and its associated circuitry. Ttle power supply may be an integral part of the laser driver  210 , or an external device. Furthermore, the prediction engine  214  may provide software enabled instructions to the laser driver  210  to enable control of the power supply. Alternatively, the prediction engine  214  may provide software enabled instructions directly to ttle power supply to achieve the transition from an inactive state to an active state, or vice versa. 
     The frame generator  208  may generate upstream data frames that are for transmission to the OLT  108 . These upstream data frames may be sent to the laser driver  210 , which in turn may transmit the upstream data frames to the OLT  108  via the laser  212 . In one implementation, the upstream data frames are transmitted to the OLT  108  in bursts, where each upstream data frame has a burst length defined by, for example, an upstream bandwidth map. 
       FIG.  2 A  illustrates an exemplary detailed view of the laser driver  210  introduced in  FIG.  2   . The laser driver  210  may include subsystem components, such as, a control logic  220 , a modulation module  222  and a laser enable module  224 . The control logic  220  may be coupled to the prediction engine  214 . The modulation module  222  and the laser enable module  224  may each be coupled to ttle laser  212 . Those of skill in the art understand that the subsystem components may also include clock trees, data serializers and other active components and circuit elements. 
     The control logic  220  may generate control and data signals that are communicated to the modulation module  222 . These signals may cause the modulation module  222  to generate a modulation current that provides a burst of upstream data to the laser  212 . The control logic  220  may also generate a control signal that causes the laser enable module  224  to generate a laser enable current that activates the laser  212  to produce an optical output signal to optically transmit the burst of upstream data associated with the modulation current. Signals generated by the control logic  220  may also cause ttle modulation module  222  and the laser enable module  224  to enter into a powered down state or a reduced power state. 
     The modulation module  222  may include a current source that generates the modulation current In one implementation, the modulation current is switched through a laser diode after being generated by the current source. A current control circuit may be coupled to the current source. This current control circuit may be controlled by the control logic  220  in a stepwise manner to adjust a level of the modulation current. The laser enable module  224  may include a current source that generates the laser enable current. In one implementation, the laser enable current is switched through a laser diode after being generated by the current source. A current control circuit may be coupled to the current source of the laser enable module  224 . This current control circuit may be controlled by the control logic  220  in a stepwise manner to adjust a level of the laser enable current. 
       FIG.  3    illustrates an exemplary downstream frame  300 . The downstream frame  300  may be associated with the PON  100 . The downstream frame  300  may include a header  302 , an upstream bandwidth map  304  and a payload  306 . The upstream bandwidth map  304  may include an ONU ID field  308 , a start field  310  and an end field  312 . The fields  308 - 312  are used to indicate a start position and an end position of each ONU upstream timeslot Each ONU (e.g., ONUs  102 - 106 ) is to send an upstream burst packet to the OLT  108  in accordance wittl ttle timeslot information assigned thereto. For example, the upstream bandwidth map  304  may include timeslot information for the ONU  102 . The start field  310  may identify that the start position of the upstream timeslot is the initial or 1st timeslot and the end field  312  may identify that the end position of the upstream timeslot is ttle 100th timeslot. Using this information, the ONU  102  is aware that it may send one or more upstream burst packets starting at the  1 st timeslot and ending at the  100 th timeslot. 
     The upstream bandwidth map  304  may be stored in the storage  204 . However, the exemplary downstream frame  300  does not necessarily include the upstream bandwidth map  304 . Rather, the downstream frame  300  may carry the ONU ID field  308 , the start field  310  and the end field  312  in other portions of the frame  300  or in another packaged format other than the upstream bandwidth map  304 . Furthermore, the information carried in fields  308 - 312  may be included in a plurality of downstream frames or other frame types. 
     Specifics of exemplary procedures are described below. However, it should be understood that certain acts need not be performed in the order described, and may be modified, and/or may be omitted entirely, depending on the circumstances. Moreover, the acts described may be implemented by a computer, processor or other computing device based on instructions stored on one or more computer-readable storage media. The computer-readable storage media can be any available media that can be accessed by a computing device to implement the instructions stored thereon. The exemplary procedures described below may reference one or more of the exemplary devices described in  FIGS.  1 - 3   . Therefore, one or more of the devices and information illustrated in  FIGS.  1 - 3    may be used to implement the described procedures. However, the referenced devices are not limiting of the described procedures. 
       FIG.  4    illustrates an exemplary optical transmitter subsystem activation and deactivation procedure. At block  402 , a start position of an upstream timeslot and an end position of the upstream timeslot may be determined. In one exemplary embodiment, the predictive engine  214  obtains the start position and end position of the upstream timeslot from the storage  204 . The predictive engine  214  may estimate or determine temporal related information that coincides with the start position and the end position of the upstream engine  214 . Such temporal related information may take into consideration how long it takes the optical transmitter subsystem components (e.g., the modules  302  and  304 ) to power up to a ready state such that the modulation and laser enable currents may be supplied to the laser  212  in sufficient time to cause the laser  212  to transmit an upstream data burst at the start position of the upstream timeslot. In one implementation, the optical transmitter subsystem components may include some or all of the components associated with a transmit physical layer. 
     At block  404 , an optical transmitter (e.g., the laser  212 ) is enabled at or about at a time the start position of the upstream timeslot is to occur. In one exemplary embodiment, the predictive engine  214  sends instructions to the laser driver  210  that may be used thereby to cause the laser  212  to transmit an upstream data burst at the start position of the upstream timeslot. These instructions may be based on information received or otherwise obtained from the storage  204 . The instructions from the predictive engine  214  may also enable the laser driver  210  to disable the laser  212  at the end position of the upstream timeslot, as is indicated at block  406 . 
     At block  404 , ttle predictive engine  214  may also send instructions to the laser driver  210  that may be used by the control logic  220  to power on, increase supplied power to, or “wakeup” various optical transmitter subsystem components at some calculated, determined or estimated time before biasing the laser  212  to transmit an upstream data burst. Such transmitter subsystem components may include, for example, the current source associated with the modulation module  222 , the current source associated with the laser enable module  224 , clock trees associated with the laser driver  210 , and the current control circuits in the modules  302  and  304 . The calculated, determined or estimated time generated by the predictive engine  214  takes into account when the laser  212  must be enabled to transmit the upstream data burst and how long it will take the optical transmitter subsystem components to reach the necessary operational state sufficient to supply the necessary current to the laser  212 . Depending on the implementation and design particulars, it may be desirable to reduce an amount of energy or power consumed by the optical transmitter subsystem components by a particular percentage, as opposed to fully or nearly fully powering down those components. In such an implementation, the calculated, determined or estimated time generated by the predictive engine  214  may be stlorter as compared to a calculated, determined or estimated time required to energize or power on subsystem components that are substantially in a powered off state. 
     As should be readily understood from the foregoing, the predictive engine  214  may supply instructions that include distinct instruction sets. One instruction set indicates when the laser driver  210  is to cause the laser  212  to transmit an upstream data burst and when the laser  212  should be disabled. Another instruction set instructs the control logic  220  to, in anticipation of an impending upstream data burst transmission, wake, energize or other otherwise enable one or more transmitter subsystem components so that those components are ready to supply the necessary currents to the laser  212  at or around the start position of the upstream data burst Furthermore, the another instruction set may include instructions that instruct the control logic  200  to reduce the power consumed by the subsystem components once the laser  212  completes the upstream data burst. The instructions to actually transmit an upstream data burst may originate from, for example, ttle frame generator  208  as opposed to the predictive engine  214 . 
       FIG.  5    is an illustrative computing device that may be used to implement the devices, modules, apparatuses, processes, procedures and hardware discussed herein. In a very basic configuration, the computing device  500  includes at least one processing unit  502  and system memory  504 . Depending on the exact configuration and type of computing device  500 , the system memory  504  may be volatile (such as RAM), non-volatile (such as ROM and flash memory) or some combination of the two. The system memory  504  typically includes an operating system  506 , one or more program modules  508 , and may include program data  510 . 
     For the present implementations, the program modules  508  may realize the various elements described as being associated with the architectures and implementations herein. Other modules and device functionalities described herein may also be part of the program modules  508 . The computing device  500  may have additional features or functionality. And, the computing device  500  may also include additional data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks, or tape. Such additional storage is illustrated in  FIG.  5    by removable storage  520  and non-removable storage  522 . Computer storage media may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. The system memory  506 , removable storage  520  and non-removable storage  522  are all examples of computer storage media. Thus, computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computing device  500 . Any such computer storage media may be part of the device  500 . Computing device  500  may also have input device(s)  524  such as keyboard, mouse, pen, voice input device, and touch input devices. Output device(s)  526  such as a display, speakers, and printer, may also be included. These devices are well known in the art and need not be discussed at length. 
     The computing device  500  may also contain a communication connection  528  that allow the device to communicate with other computing devices  530 , such as over a network. The communication connection may also enable the computing device  500  to wirelessly communicate with many different types of wireless service providers and medium. 
     Various modules and techniques may be described herein in the general context of computer-executable instructions, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, and so forth, for performing particular tasks or implement particular abstract data types. These program modules and ttle like may be executed as native code or may be downloaded and executed, such as in a virtual machine or other just-in-time compilation execution environment. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments. An implementation of these modules and techniques may be stored on or transmitted across some form of computer readable media. 
     For the purposes of this disclosure and the claims that follow, the terms “coupled” and “connected” have been used to describe how various elements interface. Such described interfacing of various elements may be either direct or indirect. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as preferred forms of implementing the claims. The specific features and acts described in this disclosure and variations of these specific features and acts may be implemented separately or may be combined.