HK1185462B - Systems and methods for ethernet passive optical network over coaxial (epoc) power saving modes - Google Patents

Abstract

Systems and methods for Ethernet Passive Optical Network Over Coaxial (EPOC) power saving modes are provided. The EPOC power savings modes allow an EPOC coaxial network unit (CNU) to enter a sleep mode based on user traffic characteristics. The sleep mode may include powering down one or more module of the EPOC CNU, including radio frequency (RF) transmit/receive circuitry and associated circuitry. In embodiments, the EPOC CNU may enter sleep mode based on instructions from an optical line terminal (OLT) or based on its own determination. Embodiments further include systems and methods that allow the EPOC CNU to maintain synchronization with a servicing coaxial media converter (CMC) when it enters a sleep mode.

Description

System and method for power saving mode of coaxial cable Ethernet passive optical network

Cross reference to related patent

The present application claims priority to U.S. provisional application No. 61/594,787 filed on 3/2/2012 and U.S. non-provisional application No. 13/436,100 filed on 30/3/2012, the contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates generally to ethernet networks.

Background

A Passive Optical Network (PON) is a single shared fiber that uses inexpensive splitters to split the single fiber into individual strands that are provided to individual subscribers. Ethernet PON (epon) is a PON based on the ethernet standard. EPONs provide simple and manageable connections for ethernet-based IP equipment, both at customer premises and at the central office. As with other gigabit ethernet media, EPONs are well suited for carrying packet traffic (packetized traffic). An Ethernet Passive Optical Network Over Coax (EPOC) is a Network that enables an EPON connection Over a coaxial Network.

Disclosure of Invention

(1) A coaxial cable ethernet passive optical network (EPOC) Coaxial Network Unit (CNU), comprising:

an Ethernet Passive Optical Network (EPON) Media Access Control (MAC) module configured to receive a control message containing an instruction to enter a sleep mode;

a traffic detection module configured to determine a traffic characteristic of user traffic at the Ethernet over coax passive optical network coaxial network unit in response to the control message; and

a power manager module configured to determine a power profile from the determined traffic characteristics and to control one or more modules of the Ethernet over coax passive optical network coaxial network unit according to the power profile.

(2) The coax ethernet passive optical network coax network unit of (1), wherein said traffic characteristics represent one or more of: there is uplink data traffic, no uplink data traffic, there is downlink data traffic, no downlink data traffic, there is an active connection multicast group, and uplink bandwidth capacity usage.

(3) The coaxial cable ethernet passive optical network coaxial network unit according to (2), further comprising:

a Radio Frequency (RF) module configured to couple the Ethernet passive optical network over coax unit to a coaxial cable, comprising:

RF Transmit (TX) circuitry configured to transmit a first RF signal on the coaxial cable; and

RF Receive (RX) circuitry configured to receive a second RF signal from the coaxial cable;

a digital-to-analog converter (DAC) coupled to the RF transmit circuit; and

an analog-to-digital converter (ADC) coupled to the RF receiving circuit.

(4) The Ethernet over coax passive optical network coaxial network unit of (3), wherein said traffic characteristics indicate an absence of upstream data traffic, and wherein said power manager module is configured to power down said RF transmit circuitry and said digital-to-analog converter for a duration defined by said sleep mode.

(5) The Ethernet over coax passive optical network coaxial network unit of (3), wherein said traffic characteristics indicate an absence of downstream data traffic, and wherein said power manager module is configured to power down said RF receive circuitry and said analog-to-digital converter for a duration defined by said sleep mode.

(6) The Ethernet over coax passive optical network coaxial network unit of (3), wherein said traffic characteristics indicate that upstream bandwidth capacity usage is below a predetermined threshold, and wherein said power manager module is configured to electrically power down said RF transmit circuitry, said digital-to-analog converter, said RF receive circuitry, and said analog-to-digital converter for a duration defined by said sleep mode.

(7) The coaxial cable ethernet passive optical network coaxial network unit according to (3), further comprising:

an EPOC PHY module coupled between the Ethernet passive optical network media access control module and the radio frequency module,

wherein the traffic characteristics indicate that upstream bandwidth capacity usage is below a predetermined threshold, and wherein the power manager module is configured to control the EPOC PHY to reduce one or more of: (a) the number of frequency subcarriers used for uplink transmission; (b) a frequency of a frequency subcarrier used for uplink transmission; (c) a modulation order for uplink transmission; and (d) a symbol rate for uplink transmission.

(8) The coaxial cable ethernet passive optical network coaxial network unit according to (3), further comprising:

an EPOC PHY module coupled between the Ethernet passive optical network media access control module and the radio frequency module, an

Wherein the radio frequency module further comprises a pilot recovery module configured to extract a pilot tone from the second RF signal and provide the pilot tone to the EPOC PHY module.

(9) The coaxial cable ethernet passive optical network coaxial network unit according to (1), further comprising:

a physical layer (PHY) module configured to couple the Ethernet over coax passive optical network coax network unit to a User Network Interface (UNI),

wherein the traffic detection module is configured to determine traffic characteristics of the user traffic by monitoring a bit stream within the physical layer module.

(10) The coax ethernet passive optical network coaxial network unit of (1), wherein the control messages comprise operations, administration, and maintenance (OAM) messages.

(11) A method for saving power within an ethernet over coax passive optical network (EPOC) Coaxial Network Unit (CNU), comprising:

receiving a control message, wherein the control message comprises an instruction for entering a sleep mode;

determining a traffic characteristic of user traffic at the coax Ethernet passive optical network coax network unit in response to the control message;

determining a power distribution from the determined flow characteristics; and

controlling one or more modules of the Ethernet over coax passive optical network coaxial network unit according to the power profile.

(12) The method of (11), wherein the traffic characteristics represent one or more of: there is uplink data traffic, no uplink data traffic, there is downlink data traffic, no downlink data traffic, there is an active connection multicast group, and uplink bandwidth capacity usage.

(13) The method of (12), wherein the traffic characteristic is indicative of an absence of upstream data traffic, and wherein the controlling comprises powering down Radio Frequency (RF) Transmit (TX) circuitry and a digital-to-analog converter (DAC) of the ethernet over coax passive optical network coaxial network unit for a duration defined by the sleep mode.

(14) The method of (12), wherein the traffic characteristic is indicative of an absence of downstream data traffic, and wherein the controlling comprises powering down Radio Frequency (RF) Receive (RX) circuitry and an analog-to-digital converter (ADC) of the coax ethernet passive optical network coax unit for a duration defined by the sleep mode.

(15) The method of (12), wherein the traffic characteristic indicates that upstream bandwidth capacity usage is below a predetermined threshold, and wherein the controlling comprises powering down Radio Frequency (RF) Transmit (TX) circuitry, digital-to-analog converter (DAC), RF Receive (RX) circuitry, and analog-to-digital converter (ADC) of the ethernet over coax passive optical network coaxial network unit for a duration defined by the sleep mode.

(16) The method of (12), wherein the traffic characteristics indicate that upstream bandwidth capacity usage is below a predetermined threshold, and wherein the controlling comprises performing one or more of: (a) reducing the number of frequency subcarriers used for uplink transmission; (b) reducing the frequency of frequency subcarriers used for uplink transmission; and (c) reducing the modulation order used for uplink transmission.

(17) The method of (11), wherein determining a flow characteristic comprises:

the data packets are examined according to configurable criteria to determine the traffic characteristics according to one or more packet selection types.

(18) A method for saving power in an ethernet over coax passive optical network (EPOC) Coaxial Network Unit (CNU), comprising:

monitoring uplink data traffic in the coaxial cable Ethernet passive optical network coaxial network unit;

comparing the data rate of the uplink data traffic with the available uplink bandwidth capacity;

selecting a power distribution of the coax Ethernet passive optical network coax units based on the comparison of the data rate of the upstream data traffic and the available upstream bandwidth capacity; and

and controlling the coaxial cable Ethernet passive optical network coaxial network unit to enter the power distribution.

(19) The method of (18), wherein a data rate of the upstream data traffic is below a predetermined threshold of the available upstream bandwidth capacity, and wherein controlling the Ethernet over coax passive optical network coaxial network unit comprises:

controlling a physical layer (PHY) module of the Ethernet passive optical network over coax network unit to reduce a number of frequency subcarriers used by the Ethernet passive optical network over coax network unit for upstream transmission.

(20) The method of (18), wherein a data rate of the upstream data traffic is below a predetermined threshold of the available upstream bandwidth capacity, and wherein controlling the Ethernet over coax passive optical network coaxial network unit comprises:

controlling a physical layer (PHY) module of the Ethernet passive optical network over coax unit to reduce a frequency of a frequency subcarrier used by the Ethernet passive optical network over coax unit for upstream transmission.

(21) The method of (18), wherein a data rate of the upstream data traffic is below a predetermined threshold of the available upstream bandwidth capacity, and wherein controlling the Ethernet over coax passive optical network coaxial network unit comprises:

controlling a physical layer (PHY) module of the coax Ethernet passive optical network coax network unit to reduce a modulation order used by the coax Ethernet passive optical network coax network unit for upstream transmission.

Drawings

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present disclosure and, together with the detailed description, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure.

Fig. 1 illustrates an exemplary hybrid Ethernet Passive Optical Network (EPON) -coaxial ethernet passive optical network (EPOC) network architecture;

fig. 2 illustrates another exemplary hybrid EPON-EPOC network architecture;

fig. 3 illustrates an exemplary EPOC portion of a hybrid EPON-EPOC network in accordance with one embodiment of the present disclosure;

fig. 4 illustrates an EPOC power save mode according to one embodiment of the present disclosure;

fig. 5 illustrates an exemplary EPOC Coaxial Network Unit (CNU) having a sleep mode in accordance with one embodiment of the present disclosure;

fig. 6 illustrates an exemplary CNU RF module according to one embodiment of the present disclosure;

fig. 7 illustrates a process flow diagram of a method of conserving power within an EPOC CNU according to one embodiment of the present disclosure;

fig. 8 illustrates another process flow diagram of a method of conserving power within an EPOC CNU according to one embodiment of the present disclosure.

The present disclosure will be described with reference to the accompanying drawings. In general, the drawing in which a component first appears is indicated generally by the leftmost digit(s) in the corresponding reference number.

Detailed Description

Fig. 1 illustrates an example hybrid Ethernet Passive Optical Network (EPON) -ethernet over coax passive optical network (EPOC) network architecture 100, according to one embodiment of this disclosure. As shown in fig. 1, the exemplary network architecture 100 includes an Optical Line Terminal (OLT) 102, an optional passive splitter 106, a communication node 110 including a Coax Media Converter (CMC), an optional amplifier 116, an optional coax splitter 118, a Coax Network Unit (CNU) 122, and a plurality of customer media devices 124.

The OLT102 is located at the Central Office (CO) of the network and is coupled to fiber lines 104. The OLT102 may implement a DOCSIS (data over cable service interface specification) mediation layer (DML) that allows the OLT102 to provide DOCSIS provisioning and management to network elements (e.g., CMCs, CMUs, Optical Network Units (ONUs)). In addition, OLT102 implements an EPON Media Access Control (MAC) layer (e.g., ieee802.3 ah).

Optionally, a passive splitter 106 may be used to split the fiber-optic line 104 into a plurality of fiber-optic lines 108. This allows multiple users in different geographical areas to be served by the same OLT102 according to a point-to-multipoint topology.

The communication node 110 serves as a converter (or switch/repeater) between the EPON side and the EPOC side of the network. Thus, node 110 is coupled to fiber-optic line 108a from the EPON side of the network and to coaxial cable 114 from the EPOC side of the network. In one embodiment, communications node 110 includes a Coax Media Converter (CMC) 112 that allows for duplication and conversion from EPON to EPOC and vice versa.

CMC112 performs physical layer (PHY) conversion from EPON to EPOC (and vice versa). In one embodiment, the CMC112 includes a first interface (not shown in fig. 1) coupled to the optical fiber line 108 and configured to receive a first optical signal from the OLT102 and generate a first bit stream having a first physical layer (PHY) encoding. In one embodiment, the first PHY encoding is EPON PHY encoding. CMC112 also includes a PHY conversion module (not shown in fig. 1) coupled to the first interface and configured to perform PHY layer conversion of the first bitstream to generate a second bitstream having a second PHY encoding. In one embodiment, the second PHY encoding is an EPOC PHY encoding. Moreover, the CMC112 includes a second interface (not shown in fig. 1) coupled to the PHY conversion module and the coaxial cable 114, configured to generate a first Radio Frequency (RF) signal from the second bitstream and transmit the first RF signal on the coaxial cable 114.

In EPOC-to-EPON conversion (i.e., while conducting upstream communications), the second interface of the CMC112 is configured to receive the second RF signal from the CNU122 and generate therefrom a third bit stream having a second PHY encoding (e.g., EPOC PHY encoding). The PHY conversion module of the CMC112 is configured to perform PHY layer conversion of the third bitstream to generate a fourth bitstream having the first PHY encoding (e.g., EPON PHY encoding). Subsequently, the first interface of the CMC112 is configured to generate a second optical signal from the fourth bit stream and transmit the second optical signal over the optical fiber line 108 to the OLT 102.

Optionally, the amplifier 116 and the second splitter 118 may be located in a path between the communication node 110 and the CNU 122. The amplifier 116 amplifies the radio frequency signal on the coaxial cable 114 before being split by the second splitter 118. The second splitter 118 splits the coaxial cable 114 into a plurality of coaxial cables 120, allowing coaxial cable service to several subscribers within the same or different geographic vicinity.

The CNUs 122 are typically located at user terminals of the network. In one embodiment, CNU122 implements the EPON MAC layer to terminate an end-to-end EPON MAC link with OLT 102. Thus, the CMC112 is capable of implementing end-to-end provisioning, management, and quality of service (QoS) functions between the OLT102 and the CNUs 122. CNU122 also provides multiple ethernet interfaces ranging between 10Mbps and 10Gbps to connect user media devices 124 to the network. Further, the CNU122 enables gateway integration for various services including VOIP (voice over internet protocol), MoCA (multimedia over coax alliance), HPNA (home phone line network alliance), Wi-Fi (Wi-Fi alliance), and the like. At the physical layer, the CMC112 may perform physical layer conversion from coax to another medium while maintaining the EPON MAC layer.

Depending on the implementation, EPON-EPOC conversion may be performed anywhere within the path between OLT102 and CNU122 to provide various service configurations depending on the desired service or infrastructure available to the network. For example, the CMC112 may be integrated within the OLT102, the amplifier 116, or an Optical Network Unit (ONU) (not shown in fig. 1) located between the OLT102 and the CNU122, rather than being integrated within the node 110.

Fig. 2 illustrates another exemplary hybrid EPON-EPOC network architecture 200 according to one embodiment of the present disclosure. In particular, the exemplary network architecture 200 enables both FTTH (fiber to the home) and multi-tenant building EPOC service configuration.

The exemplary network architecture 200 includes similar elements as described with reference to the exemplary network architecture 100 above, including the OLT102, the passive splitter 106, the CMC112, and one or more CNUs 122 located within a CO hub. The OLT102, splitter 106, CMC112, and CNU122 operate in the same manner as described above with reference to fig. 1.

The CMC112 is located, for example, in a basement of the multi-tenant building 204. Likewise, the EPON side of the network extends as far as the subscribers, and the EPOC side of the network provides only a short coaxial connection between the CMC112 and CNU units 122 located in the individual apartments of the multi-tenant building 204.

Further, the exemplary network architecture 200 includes an Optical Network Unit (ONU) 206. The ONUs 206 are coupled to the OLT102 by an all-fiber link that includes fiber lines 104 and 108 c. The ONU206 implements FTTH services for the home 202, allowing the fiber optic line 108c to reach the boundary of the living space of the home 202 (e.g., a box on the outside wall of the home 202).

Thus, the exemplary network architecture 200 enables an operator to service both ONUs and CNUs using the same OLT. This includes end-to-end provisioning, management, and QoS with a single interface for both fiber and coax users. Furthermore, the exemplary network architecture 200 allows for elimination of the conventional two-tier management architecture that manages users using media cells (media cells) and manages media cells using the OLT on the end-user side.

Fig. 3 illustrates an exemplary implementation 300 of an EPOC portion of a hybrid EPON-EPOC network. Exemplary implementation 300 may be an embodiment of the EPOC portion of exemplary EPON-EPOC network 100 described in fig. 1, or may be an embodiment of the EPOC portion of exemplary EPON-EPOC network 200 described above in fig. 2. As shown in fig. 3, the EPOC section includes EPOC CMC112 and EPOC CNU122 connected via a coax network 304.

The EPOC CMC112 includes an optical transceiver 308, a serializer and deserializer (SERDES) module 310, an EPOC PHY module 312 (including a CMC interface Field Programmable Gate Array (FPGA) 314 and a sub-band frequency division multiplexing (SDM) FPGA316 in one embodiment), a controller module 318, an analog-to-digital converter (ADC) 322, a digital-to-analog converter (DAC) 320, and a Radio Frequency (RF) module 326 (including RF Transmit (TX) circuitry 336 and RF Receive (RX) circuitry 338).

The optical transceiver 308 may include a digital optical receiver configured to receive optical signals on the fiber optic cable 302 coupled to the CMC112 and to generate electrical data signals therefrom. The fiber optic cable 302 may be part of an EPON network that connects the CMC112 and an OLT (e.g., OLT 102). The optical transceiver 308 may also include a digital optical laser to generate an optical signal from the electrical data signal and transmit the optical signal through the fiber optic cable 302.

The SERDES module 310 performs parallel-to-serial and serial-to-parallel data conversion between the optical transceiver 308 and the EPOC PHY 312. The electrical data received from the optical transceiver 308 is converted from serial to parallel for further processing by the EPOCPHY 312. Likewise, electrical data from the EPOC PHY312 is converted from parallel to serial for transmission by the optical transceiver 308.

EPOC PHY module 312 (optionally along with other modules of CMC 112) forms a bidirectional PHY conversion module. In the downstream direction (i.e., traffic to be transmitted to EPOC CNU 122), EPOC PHY312 performs PHY level conversion from an EPON PHY to a coax PHY and spectral shaping of the downstream traffic. For example, CMC interface FPGA314 may perform line coding functions, Forward Error Correction (FEC) functions, and framing functions to convert EPON PHY encoded data into coax PHY encoded data. Sdmpga 316 may perform SDM functions including determining subcarriers for downlink transmission, determining the width and frequency of the subcarriers, selecting a modulation order for downlink transmission, and dividing the downlink traffic into multiple data streams, each for transmission onto a respective one of the subcarriers. In the upstream direction (i.e., traffic received from EPOC CNU 122), EPOC PHY312 performs traffic assembly and PHY level conversion from coax PHY to EPON PHY. For example, SDM FPGA316 may assemble streams received on multiple subcarriers to generate a single stream. CMC interface FPGA314 may then perform line coding functions, FEC functions, and framing functions to convert coax PHY encoded data into EPON PHY encoded data. A detailed description of an exemplary implementation and operation of CMC112, including the functions performed by EPOC PHY312, may be found in U.S. application No. 12/878,643, filed 9/2010, the entire contents of which are incorporated herein by reference.

As will be appreciated by those skilled in the art in light of the teachings herein, the SDM described above may comprise any transmission technique that transmits/receives data over multiple carriers, including, for example, multi-carrier techniques such as Orthogonal Frequency Division Multiplexing (OFDM), wavelet OFDM, discrete wavelet multi-tone multiplexing (DWMT), or single carrier techniques that utilize channel bonding, such as multiple bonded Quadrature Amplitude Modulation (QAM) channels.

The controller module 318 provides software configuration, management, and control of the EPOC PHY312 (including the CMC interface FPGA314 and the SDM FPGA 316). Further, the controller module 318 registers the CMC112 with the OLT serving the CMC 112. In one embodiment, the controller module 318 is an ONU chip that includes an EPON MAC module.

DAC320 and ADC322 are located in the data path between EPOC PHY312 and RF module 326 and provide digital-to-analog and analog-to-digital data conversion between EPOCPHY312 and RF module 326, respectively. In one embodiment, the RF module 326 performs Pulse Amplitude Modulation (PAM) encoding on the plurality of subcarriers formed by the SDM FPGA 316.

The RF module 326 allows the CMC112 to transmit/receive RF signals over the coaxial network 304. In other embodiments, the RF module 326 may be located outside of the CMC 112. The RF module 326 sets the operating frequency and RF power level on the coaxial cable 114. RF tx circuitry 336 includes an RF transmitter and associated circuitry (e.g., mixers, frequency synthesizers, Voltage Controlled Oscillators (VCOs), Phase Locked Loops (PLLs), Power Amplifiers (PAs), analog filters, matching networks, RF power level detection, Automatic Gain Control (AGC), etc.). The RF RX circuitry 338 includes an RF receiver and associated circuitry (e.g., mixers, frequency synthesizers, VCOs, PLLs, Low Noise Amplifiers (LNAs), Automatic Gain Control (AGC), analog filters, etc.).

EPOC CNU122 includes RF module 326 (including RF TX circuitry 336 and RF RX circuitry 338), DAC320, ADC322, EPOC PHY module 328 (including SDM FPGA316 and CNU interface FPGA 330), EPOC MAC module 332, and PHY module 334.

The RF module 326, DAC320, ADC322, and SDM FPGA316 may be similar to those described above with respect to the EPOC CMC 112. Thus, operations performed in processing downstream traffic (i.e., traffic received from the CMC 112) and upstream traffic (i.e., traffic to be sent to the CMC 112) are omitted, as should be apparent to one of ordinary skill in the art in view of the teachings herein.

The CNU interface FPGA330 provides an interface between the SDM FPGA316 and the EPON MAC 332. Likewise, CNU interface FPGA330 may perform coax PHY level decoding functions, including line decoding and FEC decoding. EPON MAC module 332 implements the EPON MAC layer, including being capable of receiving and processing EPON operation, administration, and maintenance (OAM) messages that may be sent by the OLT and forwarded to CNUs 122 by CMC 112. Furthermore, EPON MAC332 interfaces with PHY module 334, which PHY module 334 can implement an ethernet PHY layer. The PHY module 334 enables physical transport over the User Network Interface (UNI) 306 (e.g., ethernet cable) to connected user devices.

Fig. 4 illustrates an EPOC power save mode according to one embodiment of the present disclosure. Within a hybrid EPON-EPOC network including OLT400, EPOCCMC112, and three EPOC CNUs 122 a-122 c, an EPOC power save mode is shown with respect to exemplary scenario 400. OLT400 and CMC112 are connected via fiber optic cable 302, which may be part of an EPON network. CMC112 is connected to EPOC CNUs 122a through 122c via coaxial cables 304a through 304c, respectively. For example, EPOC CMC112 as described above in fig. 3 may be implemented. EPOC CNUs 122 a-122 c as described above in fig. 3 are implemented.

OLT400 includes a plurality of unicast queues (including queues 402, 404, and 406), a plurality of multicast queues (including queue 408), and a broadcast queue 410. The unicast queue specifies unicast traffic destined for a particular ONU/CNU. For example, queues 402, 404, and 406 store unicast traffic destined for CNUs 122a, 122b, and 122c, respectively. The multicast queue is designated for multicast traffic that is transmitted to the selected multicast group. The multicast group includes a plurality of ONUs and/or CNUs whose users have agreed to receive multicast traffic. Broadcast queue 410 is designated for broadcast traffic that is typically sent to each ONU/CNU in the network. In addition, OLT400 includes a scheduler/shaper that receives traffic from the different queues and schedules the transmission of traffic over fiber optic line 302.

For purposes of illustration, it is assumed that CNU122a is active, sending upstream traffic to OLT400 via CMC112 and receiving downstream traffic from OLT 400. Unicast traffic destined for CNU122a is stored in unicast queue 402 of OLT 400. Assume that CNU122b only receives downstream multicast traffic from OLT 400. Downstream multicast traffic being received by CNU122b is stored in multicast queue 408 of OLT 400. Assume that CNU122c operates at a lower bandwidth usage. For example, the traffic of CNU122c may include routing or network management traffic, and no or less user traffic.

As shown in fig. 4, the EPOC power save mode includes a wake-up time and a power-down time. In an embodiment, the wake-up time and power-down time are programmable and may be repeated periodically for a particular CNU as long as the traffic conditions remain the same for that particular CNU. During the wake-up time, all three CNUs 122 a-122 c are fully powered up, including all of their transmit and receive circuitry (e.g., DAC320, ADC322, RF TX circuitry 336, and RF RX circuitry 338). Within OLT400, all unicast queues 402, 404, and 406 continue to forward their unicast traffic to the scheduler/shaper for transmission to the various CNUs.

At power down time, one or more CNUs 122 a-122 c may enter a sleep mode. The sleep mode may vary from CNU to CNU and may be triggered by OLT400 and/or by the CNUs themselves. In one embodiment, OLT400 determines which CNUs 122 a-122 c should enter sleep mode. For example, OLT400 may analyze one or more upstream and downstream traffic from each CNU to determine whether the CNU's upstream traffic satisfies a sleep mode condition (e.g., no upstream user traffic, low upstream bandwidth usage, etc.).

If a CNU satisfies the sleep mode condition, OLT400 determines an appropriate sleep mode for the CNU and instructs the CNU to enter the sleep mode via a control message. The control message may be an EPONOAM message instructing the CNU to enter the sleep mode for a predetermined duration. In another embodiment, the same sleep pattern is used for all CNUs suitable for sleep. In another embodiment, CMC112 may adjust the downstream data rate and/or frequency spectrum based on traffic from CNUs observed at CMC112 and/or OLT 400. For example, CMC112 may reduce the data rate (sub-rating) of the downlink channel in view of the lower downstream traffic load (which it observes or which OLT400 observes). Alternatively or additionally, the CMC112 may reduce the modulation order, transmit power, or reduce the amount of downlink spectrum in order to conserve power. Likewise, if the CMC112 determines that the upstream traffic is low, the upstream data rate may be decreased (e.g., from 10G to 1G). The lower slew rate and the ability to reduce the transmission power of the upstream laser also saves power.

For example, in scene 400, OLT400 may determine that CNUs 122b that receive multicast traffic only and CNUs 122c that have lower bandwidth usage are eligible to enter sleep mode. Accordingly, OLT400 may instruct CNUs 122b and 122c to enter a sleep mode. In one embodiment, the sleep mode of CNU122b includes powering down DAC320 and RF TX circuitry 336 for a predetermined duration. The sleep mode of CNU122c includes powering down DAC320 and RF TX circuitry 336 and ADC322 and RF RX circuitry 338 for a predetermined power down time.

During the power down time, OLT400 assumes that CNUs 112b and 112c have entered sleep mode, thus stopping forwarding unicast traffic destined for CNUs 122b and 122c to the scheduler/shaper for transmission to CNUs 112b and 112 c. Instead, OLT400 buffers unicast traffic in unicast queues 404 and 406 until the next wake-up time period. Likewise, broadcast traffic sent to all ONU/CNUs served by OLT400 is queued in broadcast queue 410 until the next wake-up time period. During this power down time, however, multicast traffic continues to be transmitted. In another embodiment, the CMC112 also stops forwarding unicast traffic destined for CNUs 122b and 122c that have entered sleep mode.

In another embodiment, OLT400 determines which CNUs 122 a-122 c should enter sleep mode and indicates that a CNU suitable for sleep enters sleep mode simply by specifying the power down time and the wake up time. The CNUs adapted for sleep receive sleep mode instructions from OLT400 and therefore make autonomous decisions as to whether to enter a prescribed sleep mode and which elements to power down during the power down time of the sleep mode. For example, upon receiving a sleep mode command, the CNU122b may determine whether it can power down its RF RX circuitry. In the example scenario 400, since the CNU122b is receiving multicast traffic, the CNU122b decides to power down only its DAC320 and RF TX circuitry 336 and keep its ADC322 and RF RX circuitry 338 powered up. Any SERDES channels between DAC320 and EPOC PHY328 may also be powered down. In addition, any modulation logic outside of RF TX circuitry 336 may also be powered down.

Alternatively or additionally, the appropriateness of the sleep mode may be performed individually per each CNU by analyzing the upstream and downstream traffic of each CNU itself and determining the traffic characteristics. According to the traffic characteristics, if the sleep mode condition is satisfied, each CNU selects an appropriate sleep mode and enters the selected sleep mode. In one embodiment, the CNU notifies the CMC112 that it intends to enter the selected sleep mode. The CMC112 may then buffer downstream traffic destined for the CNU for the power-down time duration. Alternatively, the CNUs notify OLT400, which buffers unicast traffic destined for the CNUs. On the user side, PHY module 334, EPON MAC332, and EPOC PHY328 remain powered up to receive any upstream user traffic from UNI 306. Upstream user traffic is buffered within EPON MAC332 or EPOC PHY328, e.g., until the next wakeup time.

Fig. 5 illustrates an exemplary EPOC CNU500 having sleep mode features according to one embodiment of the present disclosure. Exemplary CNU500 is for illustration and not limitation. As shown in fig. 5, exemplary CNU500 includes similar elements to EPOC CNU122 described above in fig. 3. Further, CNU500 includes a power manager module 502 and a traffic detection module 504.

In one embodiment, the EPON MAC module 332 is configured to receive a control message containing an instruction to enter sleep mode. The control message may comprise an EPONOAM message from the OLT. The sleep mode may specify a power down time and a wake up time period. In addition, the sleep mode may specify a particular CNU element to be powered down at power down times. In response to the control message, EPONMAC332 may transmit a sleep mode instruction to power manager module 502 via control signal 510. Alternatively, or in addition, EPON MAC332 communicates sleep mode instructions to traffic detection module 504.

In one embodiment, upon receiving the control signal 510, the power manager module 502 communicates with the traffic detection module 504 and instructs the traffic detection module 504 to analyze the traffic at the CNU500 and determine predetermined traffic characteristics. In one embodiment, the power manager module 502 and the traffic detection module 504 are configured to communicate via a bi-directional interface 508. In another embodiment, the power manager module 502 is configured to act on the sleep mode instructions contained within the control signal 510 without relying on the traffic detection module 504.

The traffic detection module 504 is coupled to the PHY module 334 via a bi-directional interface 506. The PHY module 334 is configured to couple the CNU500 to the UNI 306. Likewise, the traffic detection module 504 may be configured to monitor the bit stream within the PHY module 334. By monitoring the bit stream within PHY module 334, traffic detection module 504 may determine the traffic characteristics of upstream and downstream user traffic through CNU 500. The traffic detection module 504 then communicates the determined traffic characteristics to the power manager module 502 via the interface 508. Flow characteristics may include, for example, but are not limited to: one or more of an upstream data traffic presence, an absence of upstream data traffic, a presence of downstream data traffic, an absence of downstream data traffic, a presence/absence of an active joint multicast group (active joint multicast group), and an upstream bandwidth capacity usage rate (e.g., a ratio of an average upstream data rate to an upstream bandwidth capacity). In one embodiment, the flow detection includes packet inspection to determine flow activity based on the selected packet type. For example, traffic activity may be determined from packets, rather than from management/control frames. According to an embodiment, the type of packet used to determine the liveness of the packet is configurable.

The power manager module 502 is configured to determine a power profile based on the traffic characteristics received from the traffic detection module 504. In addition to the wake-up time and power-down time specified in the control message, the power profile may also specify that one or more modules of CNU500 be powered down during the power-down time of the sleep mode. Power manager module 502 then controls CNU500 according to the determined power profile, which may include powering down one or more modules of CNU 500. According to various example scenarios, the power manager module 502 may determine a power profile based on traffic characteristics. For example, without limitation, power manager module 502 may perform the following exemplary example scenario.

When the traffic characteristics indicate that there is no upstream data traffic at the CNU500, the power manager module 502 may be configured to power down the RF TX circuitry 336 and DAC320 of the CNU500 for a duration defined by the sleep mode. In one embodiment, power manager module 502 controls RF TX circuitry 336 and DAC320 using control signals 514 and 516, respectively. Separate control for RF TX circuitry 336 and RF RX circuitry 338 may also be used to control RF TX circuitry 336 and RF RX circuitry 338 independently of one another.

When the traffic characteristics indicate that there is no downstream data traffic, the power manager module 502 may be configured to power down the RFRX circuit 338 and ADC322 for a duration defined by the sleep mode. In one embodiment, power manager module 502 controls RF RX circuitry 338 and ADC322 using control signals 514 and 518, respectively.

When the traffic characteristics indicate that the upstream bandwidth capacity usage is below a predetermined threshold, power manager module 502 may be configured to power down one or more of RF TX circuitry 336, DAC320, RF RX circuitry 338, and ADC322 for a duration defined by the sleep mode. In another embodiment, where the traffic characteristics indicate that the upstream bandwidth capacity usage is below a predetermined threshold, the power manager module 502 may be configured to control the EPOC PHY328 using the control signals 512 (e.g., via the SDM FPGA 316) to reduce one or more of: (a) the number of frequency subcarriers used for uplink transmission; (b) a frequency of a frequency subcarrier used for uplink transmission; (c) a modulation order for uplink transmission; and (d) the symbol rate of the transmitter. These steps, individually or collectively, reduce the transmission power used by CNU500 for uplink transmissions.

In another embodiment, CNU500 may independently determine whether to enter sleep mode without the OLT control message indicating so. In this embodiment, the traffic detection module 504 and the power manager module 502 may still operate as described above to select and enter sleep mode as appropriate based on the user traffic at the CNU 500.

It is noted that in each case, it is preferable to keep the CMC112 energized at all times. This is because the CMC112 serves several CNUs, some of which may continue to be active. In addition, the CMC112 needs to keep registering its served CNUs with the OLT. Also, in an embodiment, the CMC112 provides a hold mode (hold over mode) for CNUs entering the sleep mode. The hold mode allows a CNU entering the sleep mode to remain synchronized with the CMC112 even if its RF TX/RX circuitry is powered down. Also, when the CNU wakes up, it may start sending traffic to or receiving traffic from the CMC112 immediately without waiting for its timing recovery circuit (e.g., PLL) to lock the CMC clock, which typically takes a longer time.

As shown in fig. 4 above, during the power down time of the sleep mode, OLT400 stops sending unicast traffic to CNUs determined to be suitable for the sleep mode. As the broadcast traffic also stops, the CNUs entering sleep mode do not have traffic to it. In the hold mode, the CMC112 continues to transmit pilot tones at the prescribed spectral frequencies to CNUs entering sleep mode. The CNUs, which are described further below, may be configured to extract pilot tones independently of their RF TX/RX circuitry, thereby maintaining synchronization with the CMC112 during sleep mode.

Fig. 6 illustrates an exemplary CNU RF module 600 according to one embodiment of the present disclosure. The exemplary CNU RF module 600 is intended to be illustrative, not limiting. As shown in fig. 6, RF module 600 includes RF TX circuitry 336, RF RX circuitry 338, duplexer 602, and pilot recovery module 606. The RF TX circuitry 336 and the RF RX circuitry may be similar to that described above in fig. 3. During transmit and receive timeslots, the duplexer 602 is configured to couple the RF TX circuitry 336 and the RF RX circuitry 338, respectively, to the coaxial cable.

The pilot recovery module 606 is coupled to the input terminal 604 of the RF RX circuit 338. Likewise, the pilot recovery module 606 may be configured to receive the same downlink RF signals as the RF RX circuitry 338. Also, even if the RF RX circuitry 338 is powered down in the sleep mode, synchronization may be maintained between the CNUs and the CMC using the pilot recovery module 606.

In one embodiment, the pilot recovery module 606 is configured to extract only pilot tones 608 at known frequencies from the downlink spectrum. The pilot tone provides a reference clock signal from the CMC. In one embodiment, by filtering the downlink frequency at a known frequency, the pilot tone 608 can be extracted from the downlink spectrum without sampling the filtered signal. Thus, if necessary, the ADC322 may be powered down.

Pilot recovery module 606 provides pilot tone 608 to EPOC PHY328 of the CNU. EPOC PHY328 uses pilot tone 608 as a reference clock to which its timing recovery module (e.g., PLL) is to lock. Likewise, EPOC PHY328 remains synchronized with its corresponding EPOC PHY312 at the CMC, even though both power-down RF TX circuitry 336 and RFRX circuitry 338 and no data traffic reaches the CNU.

Fig. 7 is a process flow diagram 700 of a method of conserving power within an EPOC CNU in accordance with one embodiment of the present disclosure. As shown in fig. 7, process 700 begins at step 702, which includes receiving a control message containing an instruction to enter a sleep mode. In one embodiment, the control message comprises an EPON OAM message sent by the OLT. In one embodiment, the control message is received by an EPON MAC module of the CNU. In another embodiment, the control message is transmitted from the CMC through the RF PHY channel. Once received at the CNU, the CNU immediately begins to discard the downlink spectrum. Therefore, the downstream channel can be quickly opened/closed at the CNU. In one embodiment, the CMC may use this control message on a packet-by-packet basis, depending on the downstream LLID.

Process 700 then continues to step 704, which includes determining traffic characteristics of the user traffic at the EPOCCNU in response to the control message. In one embodiment, step 704 is performed by the traffic detection module of the CNU. Flow characteristics may include, for example, but are not limited to: one or more of an upstream data traffic presence, an absence of upstream data traffic, a presence of downstream data traffic, an absence of downstream data traffic, a presence/absence of an active connection multicast group, and an upstream bandwidth capacity usage.

Process 700 then continues to step 706, which includes determining a power profile based on the determined traffic characteristics. In one embodiment, step 706 is performed by the power manager module of the CNU. The power profile determines a power down time and a wake up time, and specifies one or more modules of the CNU to be powered down during the power down time.

Finally, process 700 terminates at step 708, which includes controlling one or more modules of the EPACCNU according to the power profile. In one embodiment, step 708 is performed by a power manager module of the CNU and includes powering down one or more modules according to the determined power profile. In one embodiment, the traffic characterization indicates that there is no upstream amount of traffic, and step 708 further includes powering down the radio frequency RF TX circuitry and DAC of the EPOC CNU for a power down time defined by the sleep mode. In another embodiment, the traffic characterization indicates that there is no downstream amount of traffic, and step 708 further includes powering down the RF RX circuitry and ADC of the EPOC CNU for a power down time defined by the sleep mode.

In yet another embodiment, the traffic characteristic indicates that the upstream bandwidth capacity usage is below a predetermined threshold, and step 708 further includes powering down one or more of the EPOC CNU electrical RF TX circuitry, DAC, RF rx circuitry, and ADC for a power down time defined by the sleep mode. Alternatively, when the uplink bandwidth capacity usage is below a predetermined threshold, step 708 further comprises performing one or more of: (a) reducing the number of frequency subcarriers used for uplink transmission; (b) reducing the frequency of frequency subcarriers used for uplink transmission; (c) reducing a modulation order for uplink transmission; and (d) reducing the symbol rate of the transmitter.

Fig. 8 is a process flow diagram 800 of another method of conserving power within an EPOC CNU in accordance with an embodiment of the present disclosure. Process 800 may be performed by an EPOC CNU independently of process 700 described above in fig. 7. Thus, processes 700 and 800 may be performed simultaneously or at different times.

As shown in fig. 8, process 800 begins at step 802, which includes monitoring EPOC CNUs for upstream data traffic. In one embodiment, step 802 is performed by the traffic detection module of the CNU. The traffic detection module may monitor the bit stream through the PHY module of the EPOC CNU that interfaces the CNU and UNI.

Process 800 then continues to step 804, which includes comparing the data rate of the upstream data traffic to the available upstream bandwidth capacity. In one embodiment, step 804 is also performed by the traffic detection module of the EPOC CNU. From this comparison, if a lower bandwidth usage condition is detected in step 806 (e.g., the data rate of the upstream data traffic is below a predetermined threshold of available upstream bandwidth capacity), then process 800 continues to step 808. Otherwise, process 800 returns to step 802.

Step 808 includes selecting a power profile for the EPOC CNU by comparing the data rate of the upstream data traffic to the available upstream bandwidth capacity. In one embodiment, step 808 is performed by a power manager module of the EPOC CNU. In one embodiment, different power profiles may be selected depending on the ratio of the data rate of the upstream data traffic and the available upstream bandwidth capacity. The power profile may include one or more transmission reconfigurations to reduce the amount of power used for upstream transmissions.

Finally, process 800 terminates at step 810, which includes controlling the EPOC CNU into the selected power profile. In one embodiment, step 810 is performed by a power manager module of the EPOC CNU. In one embodiment, step 810 may include one or more of the following: (a) controlling an EPOC PHY module of an EPOC CNU to reduce a number of frequency sub-carriers for upstream transmission by an EPOC CCNU; (b) controlling the EPOC PHY module to reduce the frequency of the frequency sub-carriers used for upstream transmission by the EPOC CNU (the power required to transmit at lower frequencies is typically lower than at higher frequencies, which may reduce power consumption, due to less attenuation at lower frequencies); (c) controlling an EPOC PHY module to reduce a modulation order used by the EPOC NU for upstream transmission; and (d) controlling the EPOC PHY so as to reduce a symbol rate (symbol rate) of the transmitter.

It is noted that in an embodiment, the EPOC CNU may perform process 800 and choose to enter sleep mode without notifying the OLT. For example, the EPOC CNU may choose to reduce its upstream data rate in order to conserve power without notifying the OLT. This flexibility is achieved by a system and method that sub-rates EPON MAC traffic for the EPOC portion of a hybrid EPON-EPOC network without the end-to-end EPON MAC link being aware of the sub-rating. A detailed description of these sub-rating systems and methods can be found in U.S. patent application No. 13/163,283, filed on 17.6.2011, which is incorporated herein by reference in its entirety.

The embodiments have been described above with the aid of functional building blocks illustrating the specific functions and relationships thereof. The boundaries of these functional elements have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

The foregoing description of the specific embodiments will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

The breadth and scope of an embodiment of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims (9)

1. A coaxial cable ethernet passive optical network, EPOC, coaxial network unit, CNU, comprising:

an EPON Media Access Control (MAC) module configured to receive a control message containing an instruction to enter a sleep mode;

a Radio Frequency (RF) module configured to couple the Ethernet over coax passive optical network coaxial network unit to a coaxial cable;

an EPON MAC module coupled to the RF module, the EPON MAC module configured to receive the RF signal from the RF module;

a traffic detection module configured to determine a traffic characteristic of user traffic at the EPOC PHY module in response to the control message; and

a power manager module configured to determine a power profile according to the determined traffic characteristics and to control one or more modules of the Ethernet over coax passive optical network coaxial network unit to enter the sleep mode according to the power profile,

wherein the traffic characteristics indicate that upstream bandwidth capacity usage is below a predetermined threshold, and wherein the power manager module is configured to control the EPOC PHY module to reduce at least one of: a frequency of a frequency subcarrier used for uplink transmission, a modulation order used for uplink transmission, or a symbol rate used for uplink transmission.

2. A coaxial cable ethernet passive optical network coaxial network unit according to claim 1, wherein said traffic characteristics are indicative of one or more of: there is uplink data traffic, no uplink data traffic, there is downlink data traffic, no downlink data traffic, there is an active connection multicast group, and uplink bandwidth capacity usage.

3. The coaxial cable ethernet passive optical network coaxial network unit according to claim 2, wherein said RF module further comprises:

RF Transmit (TX) circuitry configured to transmit a first RF signal on the coaxial cable; and

RF Receive (RX) circuitry configured to receive a second RF signal from the coaxial cable;

a digital-to-analog converter (DAC) coupled to the RF transmit circuit; and

an analog-to-digital converter (ADC) coupled to the RF receiving circuit.

4. A coaxial cable ethernet passive optical network coaxial network unit according to claim 3, wherein said traffic characteristics indicate an absence of downstream data traffic, and wherein said power manager module is configured to power down said RF receive circuitry and said analog-to-digital converter for a duration defined by said sleep mode.

5. A coaxial cable ethernet passive optical network coaxial network unit according to claim 3, wherein said traffic characteristics are indicative of upstream bandwidth capacity usage being below a predetermined threshold, and wherein said power manager module is configured to electrically power down said RF transmit circuitry, said digital-to-analog converter, said RF receive circuitry and said analog-to-digital converter for a duration defined by said sleep mode.

6. The coaxial cable ethernet passive optical network coaxial network unit according to claim 3,

wherein the radio frequency module further comprises a pilot recovery module configured to extract a pilot tone from the second RF signal and provide the pilot tone to the EPOC PHY module.

7. The coaxial cable ethernet passive optical network coaxial network unit according to claim 1, wherein:

the EPOC physical layer PHY module configured to couple a coax Ethernet passive optical network coax unit to a User Network Interface (UNI),

wherein the traffic detection module is configured to determine traffic characteristics of the user traffic by monitoring a bitstream within the physical layer module.

8. A method for saving power within a coaxial cable ethernet passive optical network, EPOC, coaxial network unit, CNU, comprising:

receiving a control message, wherein the control message comprises an instruction for entering a sleep mode;

determining a traffic characteristic of the user traffic at the physical layer PHY module in response to the control message;

determining a power distribution from the determined flow characteristics; and

controlling one or more modules of the Ethernet over coax passive optical network coaxial network unit to enter the sleep mode according to the power profile,

wherein the traffic characteristic is indicative of an upstream bandwidth capacity usage below a predetermined threshold, and wherein the controlling comprises reducing at least one of: a frequency of a frequency subcarrier used for uplink transmission, a modulation order used for uplink transmission, or a symbol rate used for uplink transmission.

9. A method for saving power in a coaxial cable ethernet passive optical network, EPOC, coaxial network unit, CNU, comprising:

monitoring uplink data flow in a physical layer (PHY) module of the coaxial cable Ethernet passive optical network coaxial network unit;

comparing the data rate of the uplink data traffic with the available uplink bandwidth capacity;

selecting a power distribution of the coax Ethernet passive optical network coax units based on the comparison of the data rate of the upstream data traffic and the available upstream bandwidth capacity; and

controlling the coax Ethernet passive optical network coax network unit to enter the power profile to enter a sleep mode,

wherein a data rate of the upstream data traffic is below a predetermined threshold of the available upstream broadband capacity, and wherein controlling the EPOC CNU comprises controlling the PHY module of the EPOC CNU to reduce a frequency of a frequency sub-carrier used by the EPOC CNU for upstream transmission.