Optical communication system

Abstract

This optical communication system includes a first communication device and a second communication device. The first communication device is provided with a first communication unit, a communication control unit, a photoelectric converter, and a power source control unit. The first communication unit transmits / receives an optical signal to / from the second communication device. The communication control unit controls communication of the second communication device. The photoelectric converter converts the optical signal received from the second communication device into electricity. When power supply is not performed in the first communication unit, the power source control unit performs control so as to start power supply in the first communication unit by using the electricity converted by the photoelectric converter.

Description

Optical Communication Systems

[0001] The present invention relates to optical communication systems.

[0002] Fig. 10 is a diagram showing an example of the configuration of a conventional optical communication system. The optical communication system shown in Fig. 10 has one upper device and multiple lower devices. The upper device has the function of controlling the transmission timing of upstream frames in each of the multiple connected lower devices. The lower devices have the function of temporarily holding upstream frames and transmitting them at the timing instructed by the upper device. Fig. 11 is a sequence diagram of upstream frame transmission timing control in the optical communication system.

[0003] Each device is also equipped with a sleep function to reduce power consumption and has the function of supplying the minimum amount of power necessary. Note that while Figure 10 shows a one-to-many connection configuration, the same applies to a one-to-one connection configuration.

[0004] On the other hand, there is a technology in which the lower device converts the power supply light transmitted from the upper device into current using a photodetector, and uses the converted current to perform upstream communication (see, for example, non-patent document 1).

[0005] "ANSL R&D Times, 2. Wired Power Supply Access System Configuration", Nippon Telegraph and Telephone Corporation, No. 105, [online], 2018, Internet<https: / / www.rd.ntt / as / times / 105 / 02 / 02.html>

[0006] With conventional technology, it is difficult for a host device installed far from the user to remotely grasp the timing of new connections of a lower-level device or the timing of user use. Therefore, it is necessary to constantly check for the presence or absence of upstream frames for the lower-level device and instruct the transmission timing. Therefore, even if the lower-level device is not connected, is powered off, or is in a sleep state, or is otherwise in a state where communication is not required, it is not possible to completely power off the host device. Even with the conventional sleep function, it is not possible to reduce the standby power consumption of the upper device to zero.

[0007] In view of the above circumstances, an object of the present invention is to provide an optical communication system capable of reducing power consumption.

[0008] One aspect of the present invention is an optical communication system having a first communication device and a second communication device, wherein the first communication device comprises a first communication unit that transmits and receives optical signals to and from the second communication device, a communication control unit that controls communication of the second communication device, a photoelectric conversion unit that converts optical signals received from the second communication device into electricity, and a power control unit that controls the first communication unit to start supplying power using the electricity converted by the photoelectric conversion unit when power is not being supplied to the first communication unit.

[0009] The present invention makes it possible to provide a communication system that can reduce power consumption.

[0010] FIG. 1 is a diagram for explaining an overview of an optical communication system according to an embodiment of the present invention. FIG. 2 is a diagram for explaining an example of the configuration of an optical communication system according to an embodiment of the present invention. FIG. 3 is a diagram for explaining an overview of the operation of an optical communication system according to a first embodiment. FIG. 4 is a flow diagram showing the processing of an optical communication system according to the first embodiment. FIG. 5 is a diagram for explaining the configuration of an optical communication system according to the first embodiment. FIG. 6 is a diagram for explaining the configuration of an optical communication system according to the first embodiment. FIG. 7 is a diagram for explaining the configuration of an optical communication system according to the first embodiment. FIG. 8 is a diagram for explaining the configuration of an optical communication system according to a second embodiment. FIG. 9 is a diagram for explaining an example of the configuration of a conventional optical communication system. FIG. 10 is a sequence diagram in a conventional optical communication system.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] FIG. 1 is a diagram illustrating an overview of an optical communication system 1 according to an embodiment of the present invention. The optical communication system 1 shown in FIG. 1 includes a higher-level device 2 and n lower-level devices 3 (n is an integer equal to or greater than 1). The higher-level device 2 and the lower-level device 3 are examples of a first communication device and a second communication device, respectively. The higher-level device 2 and the n lower-level devices 3 are connected by splitting a communication signal transmitted through a single optical cable 4 into multiple signals using an optical splitter 5. The optical cable 4 is an optical transmission path. The direction from the higher-level device 2 to the lower-level device 3 is called downlink, and the direction from the lower-level device 3 to the higher-level device 2 is called uplink.

[0013] The upper device 2 multiplexes and transmits downstream frames of the optical signal to be transmitted to each of the n lower devices 3. The optical splitter 5 simply branches the multiplexed downstream frames and forwards them to each of the n lower devices 3. The lower device 3 extracts the downstream frames addressed to itself from the received downstream frames. Meanwhile, the upstream frames of the optical signal transmitted from each of the n lower devices 3 to the upper device 2 are multiplexed by the optical splitter 5 and transmitted to the upper device 2. The timing at which each lower device 3 transmits its upstream frame is instructed by a transmission permission signal from the upper device 2 before transmitting the upstream frame.

[0014] In this embodiment, when the upper device 2 is in a power-off state, the lower device 3 activates the upper device 2. Here, the power-off state refers to a state in which power supply to the functional units of the upper device 2 related to the transmission and reception of optical signals with the lower device 3 is stopped. Regardless of whether the connection configuration is one-to-many or one-to-one communication, if the upper device 2 is in a power-off state, it can be determined that the upper device 2 is in a non-communicating state. When the upper device 2 is in a non-communicating state, there is no need to consider upstream frame collisions between the lower devices 3. Therefore, the lower device 3 can issue upstream frames at any timing. The upper device 2 is activated upon receiving the upstream frame signal. That is, the upper device 2 converts the upstream frame signal received from the lower device 3 from an optical signal to electricity and activates itself using the converted electricity. The lower device 3 determines whether the upper device 2 is in a power-off state based on whether a link-up is possible within a certain period of time.

[0015] According to this embodiment, even in a higher-level device installed in a location far from the user, the functional parts related to sending and receiving optical signals with the lower-level device can be completely powered off until the time of use by the user, thereby reducing standby power consumption.

[0016] 2 is a diagram showing an example of the configuration of an optical communication system 1 according to this embodiment, in which only functional units related to this embodiment are extracted and shown.

[0017] The higher-level device 2 has a communication package 21 and a package control unit 23. The communication package 21 has a signal transmission / reception unit 22, and the package control unit 23 has a communication necessity determination unit 24. The higher-level device 2 may have any number of communication packages 21, but only one communication package 21 is shown in FIG.

[0018] The communication package 21 transmits and receives optical signals to and from the lower-level device 3 via the optical cable 4. The signal transmitter / receiver 22 receives optical signals output from the lower-level device 3 and transmitted through the optical cable 4, and converts the received optical signals into electrical signals. The signal transmitter / receiver 22 also converts downstream electrical signals into optical signals and outputs the converted optical signals to the optical cable 4. When the communication package 21 is in a power-off state where no power is supplied to the communication package 21, the signal transmitter / receiver 22 converts the optical signals received from the lower-level device 3 into electricity, and starts up the communication package 21 using the converted electricity.

[0019] The package control unit 23 starts up or powers off the communications package 21 based on the determination result of the communication necessity determination unit 24. The communication necessity determination unit 24 holds registration information for the lower devices 3 and constantly monitors the status of the lower devices 3. The communication necessity determination unit 24 also controls communication between itself and the lower devices 3 based on the status of the lower devices 3. That is, the communication necessity determination unit 24 determines whether communication with the lower devices 3 is necessary based on the status of the lower devices 3. The communication necessity determination unit 24 determines the timing for permitting upstream communication for the lower devices 3 for which communication is determined to be necessary, and notifies the determined timing via an optical signal from the signal transmission / reception unit 22. If the communication necessity determination unit 24 determines that communication with any of the lower devices 3 subordinate to the communications package 21 is unnecessary, it powers off the communications package 21.

[0020] The lower-level device 3 includes a signal transmitting / receiving unit 31 , a control unit 32 , and a UNI (User Network Interface) 33 .

[0021] The signal transmitter / receiver 31 receives downstream optical signals output from the higher-level device 2 and transmitted through the optical cable 4, and converts the received optical signals into electrical signals. The signal transmitter / receiver 31 outputs the converted electrical signals to an external device from the UNI 33. The signal transmitter / receiver 31 also converts electrical signals received by the UNI 33 from an external device into upstream optical signals, and outputs the converted optical signals to the optical cable 4 at the timing notified by the higher-level device 2.

[0022] The control unit 32 recognizes whether a signal has been received from the higher-level device 2. If the control unit 32 has not received a signal from the higher-level device 2 for a certain period of time, it determines that the higher-level device 2 is in a sleep state and causes the signal transmission / reception unit 31 to transmit an optical signal to start up the higher-level device 2. The control unit 32 also determines and executes startup and sleep of its own device based on a signal from the UNI 33. The UNI 33 is an interface with the user-side network. The UNI 33 sends and receives signals to and from the user-side network.

[0023] With the above configuration, the signal transmitter / receiver 22 of the higher-level device 2 can activate the communication package 21 in response to an optical signal output from the signal transmitter / receiver 31 of the lower-level device 3, even if the communication package 21 is powered off. Therefore, even when the higher-level device 2 controls communication for the lower-level device 3, it is possible to completely power off the communication package 21 of the higher-level device 2. Conventionally, the higher-level device controlled communication, so powering off the higher-level device was not possible. In this embodiment, the control unit 32 of the lower-level device 3 determines whether communication is necessary, and if communication is necessary, the signal transmitter / receiver 31 sends an optical signal to instruct the higher-level device 2 to start up. This allows the higher-level device 2 to completely power off the communication package 21 without affecting the user, thereby achieving maximum power savings. Detailed embodiments are described below.

[0024] First Embodiment The first embodiment is an optical communication system having a PON (Passive Optical Network) configuration.

[0025] FIG. 3 is a diagram for explaining an outline of the operation of the optical communication system 10 according to the first embodiment. The optical communication system 10 includes one OLT (Optical Line Terminal) 200 and one or more ONUs (Optical Network Units) 300. The OLT 200 and the ONUs 300 are connected by an optical cable 4. The OLT 200 corresponds to the higher-level device 2 in FIGS. 1 and 2, and the ONUs 300 correspond to the lower-level device 3 in FIGS. 1 and 2. Only one ONU 300 is shown in FIG. 3. Also, the optical splitter 5 is not shown in FIG. 3.

[0026] The OLT 200 has a communication package 201 and a package control unit 203. The OLT 200 may have any number of communication packages 201, but only one communication package 201 is shown in FIG. 3. The communication package 201 has an optical communication unit 202. The package control unit 203 has a communication necessity determination unit 204. The communication package 201, the optical communication unit 202, the package control unit 203, and the communication necessity determination unit 204 correspond to the communication package 21, the signal transmission / reception unit 22, the package control unit 23, and the communication necessity determination unit 24 in FIG. 2, respectively. The ONU 300 has an optical communication unit 301 and a control unit 302. The optical communication unit 301 and the control unit 302 correspond to the signal transmission / reception unit 31 and the control unit 32 in FIG. 2, respectively.

[0027] In the case of a PON, the communication necessity determination unit 204 of the OLT 200 grasps the connection status with each ONU 300 using an authentication DB (database) and determines whether to power off the communication package 201. That is, according to conventional technology, the control unit 302 of the ONU 300 transmits a state transition notification signal from the optical communication unit 301 to the OLT 200 to notify the OLT 200 of its own state before powering off or entering a sleep state. The communication necessity determination unit 204 of the OLT 200 obtains information on the state of each ONU 300 from the state notification signal received by the communication package 201. The communication necessity determination unit 204 determines whether communication is necessary based on the acquired information on the state of the ONU 300. For example, if no communication occurs for a predetermined period of time because all ONUs 300 subordinate to the communication package 201 are powered off or in a sleep state, the communication necessity determination unit 204 places the communication package 201 in a power-off state.

[0028] When the communication package 201 of the OLT 200 is in a power-off state, the control unit 302 of the ONU 300 that is to be started first among the ONUs 300 connected under that communication package 201 detects that no downstream optical signal has been received for a certain period of time while the optical communication unit 301 is connected to the optical line, and sends an upstream optical signal from the optical communication unit 301 to forcibly instruct the OLT 200 to start up. The communication package 201 that was in a power-off state of the OLT 200 starts up when it receives an optical signal instructing it to start up. The communication package 201 is started up by optical power feeding. Unlike conventional systems, the optical communication unit 301 of the ONU 300 emits light without an instruction from the OLT 200, and the OLT 200 in a power-off state can be started up from the ONU 300 by optical power feeding. This achieves power saving.

[0029] 4 is a flow diagram showing the processing of the optical communication system 10. First, an ONU 300 is newly installed, or an ONU 300 is started up from a sleep state (step S1). The control unit 302 of the ONU 300 determines whether the optical communication unit 301 of the ONU 300 is connected to the optical cable 4 (step S2). If the control unit 302 determines that the optical communication unit 301 of the ONU 300 is not connected to the optical cable 4 (step S2: NO), the control unit 302 connects the optical communication unit 301 of the ONU 300 to the optical cable 4 (step S3), and then performs the processing of step S4.

[0030] When the control unit 302 of the ONU 300 determines that the optical communication unit 301 is connected to the optical cable 4 (step S2: YES), or after the optical communication unit 301 is connected to the optical cable 4 (step S3), the control unit 302 determines whether an LLID has been assigned to the ONU 300 from the OLT 200 and a link has been established (step S4). The procedure for assigning an LLID and establishing a link between the OLT 200 and the ONU 300 is performed in the same manner as in the prior art. When the control unit 302 of the ONU 300 determines that an LLID has been assigned and a link has been established (step S4: YES), the control unit 302 starts communication with the OLT 200 (step S5).

[0031] If the control unit 302 of the ONU 300 determines that a link has not been established (step S4: NO), it determines whether a Gate signal has been received from the OLT 200 within a predetermined time period prior to the present (step S6). For example, the predetermined time period may be, but is not limited to, one second. The Gate signal is a transmission permission signal from the OLT 200 to the ONU 300. The Gate signal includes information such as the timing at which the ONU 300 is permitted to transmit an upstream signal and the amount of transmission permission. If the control unit 302 of the ONU 300 determines that a Gate signal has been received within the predetermined time period prior to the present (step S6: YES), it starts communication with the OLT 200 (step S5).

[0032] On the other hand, if the control unit 302 of the ONU 300 determines that it has not received a Gate signal within a predetermined time period going back from the present (step S6: NO), it determines that the OLT 200 is in a sleep state (step S7). The control unit 302 of the ONU 300 transmits an optical signal startup instruction from the optical communication unit 301 (step S8). When the optical communication unit 202 of the OLT 200 receives the startup instruction from the ONU 300, it starts up the communication package 201 by optical power feeding. Specifically, the optical communication unit 202 converts the startup instruction received from the ONU 300 from an optical signal to electricity, and starts up the communication package 201 using this converted electricity.

[0033] The control unit 302 of the ONU 300 determines whether or not it is possible to receive a gate signal from the OLT 200 (step S9). For example, the control unit 302 determines that it is possible to receive a gate signal when processing related to the MPCP (Multi-Point Control Protocol) function required for receiving a gate signal has been performed between the ONU 300 and the OLT 200. If the control unit 302 determines that it is not possible to receive a gate signal (step S9: NO), it repeats the processing of step S8. If the control unit 302 determines that it is possible to receive a gate signal (step S9: YS), it starts communication with the OLT 200 (step S10).

[0034] As described above, unlike the conventional technology, the optical communication unit 301 of the ONU 300 emits light without an instruction from the OLT 200, and the OLT 200 in a power-off state can be started up by optical power supply from the ONU 300 side, thereby realizing power saving.

[0035] Next, a configuration for starting the OLT by optical power feeding will be described.

[0036] Fig. 5 is a diagram showing the configuration of an optical communication system 11. The optical communication system 11 includes one OLT 210 and one or more ONUs 310. The OLT 210 and the ONUs 310 are connected by an optical cable 4. The OLT 210 is used as the OLT 200 shown in Fig. 3, and the ONU 310 is used as the ONU 300 shown in Fig. 3. Fig. 5 shows only one ONU 310. Furthermore, Fig. 5 omits the illustration of the optical splitter 5.

[0037] The OLT 210 includes a communication package 211, an OLT package control unit 218, and an OLT power supply unit 219. The OLT 210 may include any number of communication packages 211, but Fig. 5 shows only one communication package 211. The communication package 211 and the OLT package control unit 218 correspond to the communication package 21 and the package control unit 23 of the higher-level device 2 in Fig. 2, respectively.

[0038] The communication package 211 includes a signal transmitting / receiving unit 212, a communication package control unit 215, and a power supply circuit unit 216. The signal transmitting / receiving unit 212 includes an opto-electrical conversion unit 213 and a transceiver 214. The opto-electrical conversion unit 213 is, for example, an opto-electrical conversion element. The opto-electrical conversion unit 213 receives an upstream optical signal transmitted through the optical cable 4, converts the received optical signal into an electrical signal, and supplies the electrical signal to the power supply circuit unit 216. The transceiver 214 receives the upstream optical signal transmitted through the optical cable 4 and converts the received upstream optical signal into an electrical signal. The transceiver 214 transmits the converted upstream electrical signal to the host device 600. Alternatively, a conversion unit (not shown) may convert the upstream signal converted into an electrical signal by the transceiver 214 into a predetermined type of signal and transmit it to the host device 600. The transceiver 214 also converts the electrical signal received from the host device 600 into a downstream optical signal and inputs it to the optical cable 4. Alternatively, a conversion unit (not shown) may convert a predetermined type of downstream signal received from the higher-level device 600 into an electrical signal, and the transceiver 214 may convert the converted electrical signal into a downstream optical signal and input it to the optical cable 4. The predetermined type of signal transmitted and received by the higher-level device 600 may be, for example, an optical signal, an electrical signal, or the like, but is not limited to these.

[0039] The communication package control unit 215 controls the signal transmitting / receiving unit 212 and the power supply circuit unit 216. For example, the communication package control unit 215 controls the light source used by the transceiver 214 to transmit and receive optical signals. In addition, in accordance with instructions from the OLT package control unit 218, the communication package control unit 215 transmits a signal notifying the LLID and control signals such as a Gate signal to the ONU 310 via a downstream optical signal from the transceiver 214 of the signal transmitting / receiving unit 212.

[0040] The power supply circuit unit 216 includes a power supply IC (integrated circuit) 217. The power supply circuit unit 216 supplies power supplied from an OLT power supply unit 219 to the signal transmission / reception unit 212 and the communication package control unit 215. When the OLT package control unit 218 or the communication package control unit 215 determines that the communication package 211 does not require communication, the power supply circuit unit 216 enters a power-off state and stops (cuts off) the power supply to each functional unit in the communication package 211. When the communication package 211 is in a power-off state, the power supply circuit unit 216 activates the power supply IC 217 using current from the photoelectric conversion unit 213 and starts supplying power to each functional unit in the communication package 211. The power supply IC 217 switches the power supply from the power supply circuit unit 216.

[0041] The OLT package control unit 218 grasps the connection status notified from the ONU 310 and determines whether or not to cut off power to the communication package 211 based on the grasped connection status. If power cutting is possible, the OLT package control unit 218 puts the communication package 211 in a power-off (communication cut-off) state. The OLT package control unit 218 also performs processes such as assigning an LLID to the ONU 310 and determining the transmission timing and permitted transmission amount of upstream signals to be permitted to each ONU 310 based on the upstream data amount notified from the ONU 310, etc.

[0042] The OLT power supply unit 219 supplies power from an external power supply 500 to each unit such as the communication package 211 and the OLT package control unit 218. The OLT power supply unit 219 supplies power to the power supply circuit unit 216 even when the communication package 211 is in a power-off state.

[0043] The ONU 310 includes a signal transmitting / receiving unit 311, a control unit 312, a UNI 313, and a connector unit 314. The signal transmitting / receiving unit 311, the control unit 312, and the UNI 313 correspond to the signal transmitting / receiving unit 31, the control unit 32, and the UNI 33 of the lower-level device 3 shown in FIG. 2, respectively.

[0044] The signal transmitter / receiver 311 receives downstream optical signals output from the OLT 210 and transmitted through the optical cable 4, and converts the received optical signals into electrical signals. The signal transmitter / receiver 311 outputs the converted electrical signals from the UNI 313 to external devices on the user-side network. The signal transmitter / receiver 311 also converts electrical signals received by the UNI 313 from external devices on the user-side network and addressed to the higher-level device 600 into upstream optical signals, and outputs the converted optical signals to the optical cable 4.

[0045] The control unit 312 recognizes whether a signal is received from the OLT 210. The control unit 312 also determines and executes startup and sleep of the device itself based on signals transmitted and received by the UNI 33. The UNI 33 is an interface with the user-side network. The UNI 33 transmits and receives signals to and from the user-side network. The connector unit 314 is a connector that connects the signal transmission / reception unit 311 to the optical cable 4.

[0046] When the control unit 312 of the ONU 310 detects that the connector unit 314 is connected to the optical cable 4 and further detects that the UNI 313 has received an upstream frame, the control unit 312 checks for a certain period of time (for example, one second) whether it is possible to receive a transmission permission signal (gate signal) from the OLT 210. When the control unit 312 does not receive a transmission permission signal (gate signal) from the OLT 210 for a certain period of time, it determines that the OLT 210 is in a sleep state and forcibly transmits an upstream optical signal from the signal transmitting / receiving unit 311.

[0047] When the communication package 211 is in a power-off state, the photoelectric conversion unit 213 of the OLT 210 receives an optical signal from the ONU 310 and converts the received optical signal into electricity. The photoelectric conversion unit 213 supplies the converted electricity to the power supply circuit unit 216. When the power supply circuit unit 216 starts up the power supply IC 217 using the electricity supplied from the photoelectric conversion unit 213 and switches from the power-off state to the activated state, the power supply circuit unit 216 supplies power supplied from the OLT power supply unit 219 to the signal transmission / reception unit 212 and the communication package control unit 215.

[0048] The OLT package control unit 218 grasps the connection status of each ONU 310 based on notifications from those ONUs 310, and determines whether to power off the communication package 211 based on the grasped connection status of each ONU 310. If the OLT package control unit 218 determines that power cannot be powered off, it continues to supply power to each unit from the OLT power supply unit 219. The OLT package control unit 218 determines the transmission timing of the upstream signal permitted to the ONU 310, and instructs the communication package 211 to transmit a Gate signal with the determined transmission timing set. The communication package control unit 215 of the communication package 211 transmits the Gate signal from the transceiver 214 of the signal transmission / reception unit 212 to the ONU 310. The control unit 312 of the ONU 310 controls the signal transmission / reception unit 311 to output the upstream signal at the transmission timing notified by the Gate signal.

[0049] On the other hand, when the OLT package control unit 218 determines that it is possible to power off the communication package 211 based on the connection state of each ONU 310, it instructs the communication package control unit 215 of that communication package 211 to power off. The communication package control unit 215 instructs the communication package 211 to stop the power supply in accordance with the instruction from the OLT package control unit 218, and the communication package 211 enters a power-off state.

[0050] In order to prevent erroneous detection of light in the photoelectric conversion unit or unintended light entering the photoelectric conversion unit, light of a specific wavelength may be used to activate the OLT communication package. In this case, a wavelength filter is installed in the photoelectric conversion unit to convert the light of the specific wavelength into electricity for activation.

[0051] Fig. 6 is a diagram showing the configuration of an optical communication system 12. In Fig. 6, the same components as those in the optical communication system 11 shown in Fig. 5 are assigned the same reference numerals, and their description will be omitted. The optical communication system 12 shown in Fig. 6 differs from the optical communication system 11 shown in Fig. 5 in that it includes an OLT 220 instead of the OLT 210. The configuration of the ONU 310 is the same as the configuration of the ONU 310 shown in Fig. 5. However, a control unit 312 transmits a start instruction for an optical signal of a predetermined wavelength from a signal transmission / reception unit 311.

[0052] 6 differs from the OLT 210 shown in Fig. 5 in that it includes a communication package 221 instead of the communication package 211. The communication package 221 differs from the communication package 211 in that it includes a signal transmitter / receiver 222 instead of the signal transmitter / receiver 212. The signal transmitter / receiver 222 includes an opto-electrical converter 213, a transceiver 214, and a wavelength filter 224. When the wavelength filter 224 receives an upstream optical signal transmitted from the ONU 310 and transmitted through the optical cable 4, it extracts an optical signal of a predetermined wavelength used for opto-electrical conversion and outputs the extracted optical signal to the opto-electrical converter 213. The opto-electrical converter 213 converts the optical signal extracted by the wavelength filter 224 into electricity.

[0053] In addition, in order to prevent the communication package from being activated due to erroneous detection of light in the photoelectric conversion unit or unintended light entering the photoelectric conversion unit, the power supply circuit unit may be provided with an activation determination unit that determines an optical signal with a specific light emission pattern as an activation signal.

[0054] FIG. 7 is a diagram showing the configuration of an optical communication system 13. In FIG. 7, the same components as those in the optical communication system 11 shown in FIG. 5 are designated by the same reference numerals, and their description will be omitted. The optical communication system 13 shown in FIG. 7 differs from the optical communication system 11 shown in FIG. 5 in that it includes an OLT 230 instead of the OLT 210. The configuration of the ONU 310 is the same as that of the ONU 310 shown in FIG. 5. However, the control unit 312 transmits an optical signal of a certain duration or longer, or an activation instruction for an optical signal of a predetermined signal pattern, from the signal transmission / reception unit 311. The signal pattern is represented by a combination of on / off timing. In other words, the signal pattern is the light emission pattern of the activation signal transmitted from the signal transmission / reception unit 311.

[0055] The OLT 230 shown in Fig. 7 differs from the OLT 210 shown in Fig. 5 in that it includes a communication package 231 instead of the communication package 211. The communication package 231 differs from the communication package 211 in that it includes a power supply circuit unit 232 instead of the power supply circuit unit 216. The power supply circuit unit 232 includes a power supply IC 217 and an activation determination unit 233. The activation determination unit 233 supplies electricity supplied from the photoelectric conversion unit 213 to the power supply circuit unit 232 when the signal transmission / reception unit 212 confirms reception of an optical signal for a certain period of time or more or when it receives an optical signal with a predetermined signal pattern. When the power supply is cut off, the power supply circuit unit 232 activates the power supply IC 217 with electricity supplied from the activation determination unit 233 and supplies power to each unit in the communication package 231. The activation determination unit 233 of the OLT 230 activates the communication package 231 when it receives continuous light or an intended signal pattern for a predetermined period of time or more, thereby preventing activation due to erroneous detection of an optical signal.

[0056] The OLT 230 may include a signal transmitting / receiving unit 222 shown in FIG. 6 instead of the signal transmitting / receiving unit 212 .

[0057] Furthermore, the photoelectric conversion unit of the OLT may not be included in the signal transmission / reception unit, and the photoelectric conversion unit and the signal transmission / reception unit may be separate units.

[0058] FIG. 8 is a diagram showing the configuration of an optical communication system 14. In FIG. 8, the same components as those in the optical communication system 11 shown in FIG. 5 are denoted by the same reference numerals, and their description will be omitted. The optical communication system 14 shown in FIG. 8 differs from the optical communication system 11 shown in FIG. 5 in that it includes an OLT 240 instead of the OLT 210. The OLT 240 differs from the OLT 210 in that it includes an opto-electrical converter 213 and a signal transceiver 242 instead of the signal transceiver 212. An upstream optical signal transmitted from an ONU 310 and transmitted through the optical cable 4 is branched, and one branched optical signal is output to the opto-electrical converter 213, and the other branched optical signal is input to the signal transceiver 242. The signal transceiver 242 operates in the same manner as the signal transceiver 212 shown in FIG. 5, except that it does not include the opto-electrical converter 213.

[0059] 6 may be provided in the communication package 241 of the OLT 240, and the photoelectric conversion unit 213 may receive the light extracted by the wavelength filter 224. Moreover, the OLT 240 may be provided with a power supply circuit unit 232 shown in FIG. 7 instead of the power supply circuit unit 216.

[0060] According to this embodiment, the optical communication system includes one upper device (OLT) with a sleep function and one or more lower devices (ONUs). If the lower device fails to receive a downstream optical signal from the upper device for a predetermined period of time, it determines that the upper device is in a sleep state and transmits an upstream optical signal to the upper device. The upper device converts the upstream optical signal received from the lower device into electricity and uses that electricity to start up its power circuit, thereby waking up from the sleep state. This allows the communication package of the upper device to be completely powered off until the user begins using it, thereby reducing standby power consumption.

[0061] Second Embodiment In the first embodiment, the application to a PON system has been described. In the second embodiment, a media converter (MC) is used instead of the OLT and ONU of the PON system.

[0062] Fig. 9 is a diagram showing an example of the configuration of an optical communication system 15. The optical communication system 15 has a plurality of media converters 250 connected by optical cables 4. In Fig. 9, two media converters 250 are shown.

[0063] The media converter 250 has a signal transmitting / receiving unit 251, an E / O (electrical-optical) conversion unit 254, a copper port 255, a control unit 256, and a power supply circuit unit 257. The signal transmitting / receiving unit 251 and the E / O conversion unit 254 correspond to the signal transmitting / receiving unit 22 in Fig. 2, the copper port 255 corresponds to the UNI 33 in Fig. 2, and the control unit 256 corresponds to the package control unit 23 in Fig. 2.

[0064] The signal transmitting / receiving unit 251 has an opto-electrical conversion unit 252 and a transceiver 253. The opto-electrical conversion unit 252 receives an optical signal transmitted by the opposing media converter 250 and transmitted through the optical cable 4. The opto-electrical conversion unit 252 converts the received optical signal into electricity and supplies it to a power supply IC 258 of the power supply circuit unit 257. The transceiver 253 receives the optical signal transmitted from the opposing media converter 250 and transmitted through the optical cable 4, and outputs the received optical signal to the E / O conversion unit 254. In addition, the transceiver 214 inputs the optical signal received from the E / O conversion unit 254 to the optical cable 4.

[0065] The E / O conversion unit 254 converts the optical signal received from the transceiver 253 into an electrical signal and outputs it from the copper port 255 to the terminal device 700. The E / O conversion unit 254 also receives, from the transceiver 253, an electrical signal transmitted by the terminal device 700, converts the received electrical signal into an optical signal and outputs it to the transceiver 253. The copper port 255 inputs and outputs electrical signals to and from the terminal device 700.

[0066] The control unit 256 turns off the power supply circuit unit 257 or puts it into a sleep state when the E / O conversion unit 254 has not transmitted or received a signal for a predetermined period of time. The power supply circuit unit 257 includes a power supply IC 258. The power supply circuit unit 257 supplies power to the signal transmission / reception unit 251, the E / O conversion unit 254, and the control unit 256. When the power supply circuit unit 257 is in a power-off state, it stops supplying power to each unit, and when in a sleep state, it stops supplying power to some functional units including the signal transmission / reception unit 251. The power supply IC 258 switches the power supply from the power supply circuit unit 257.

[0067] The media converter 250 converts signals received from a terminal device 700 connected to the media converter 250 into optical signals and transmits them to the opposing media converter 250, or converts optical signals received from the opposing media converter 250 into electrical signals and transmits them to the terminal device 700 connected to the media converter 250. Therefore, the media converter 250 transmits optical signals without knowing the state of the opposing media converter 250. Even if the receiving media converter 250 is in a power-off state or sleep state, the photoelectric conversion unit 252 converts the received optical signals into electricity and supplies the converted electricity to the power supply circuit unit 257, thereby activating the power supply circuit unit 257. The activated power supply circuit unit 257 activates the power supply IC 258 and supplies power to the signal transmission / reception unit 251, the E / O conversion unit 254, and the control unit 256. This allows power to be supplied to the entire media converter 250, enabling communication.

[0068] The communication package control unit 215, OLT package control unit 218, control unit 256, and control unit 312 provided in each device of this embodiment may include a processor, memory, auxiliary storage device, etc. connected via a bus, and the processor may execute a program to realize the above functions. The processor may be, for example, a central processing unit (CPU) or a graphics processing unit (GPU). Note that all or part of the functions of the communication package control unit 215, OLT package control unit 218, control unit 256, and control unit 312 may be realized using hardware such as an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA). The programs for the communication package control unit 215, OLT package control unit 218, control unit 256, and control unit 312 may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as a magneto-optical disk, ROM, and CD-ROM, and storage devices such as a hard disk built into a computer system. In this way, the communication package control unit 215, the OLT package control unit 218, the control unit 256, and the control unit 312 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0069] According to the above-described embodiment, the optical communication system includes a first communication device and a second communication device. For example, the first communication device corresponds to the higher-level device 2, the OLTs 200, 210, 220, 230, and 240, and the media converter 250 in the embodiment, and the second communication device corresponds to the lower-level device 3, the ONUs 300 and 310, and the media converter 250 in the embodiment.

[0070] The first communication device includes a first communication unit, a communication control unit, a photoelectric conversion unit, and a power supply control unit. For example, the first communication unit corresponds to the communication packages 21, 201, 211, 221, and 231, the signal transmission / reception units 22, 212, 222, 242, and 251, the photoelectric conversion unit 213, and the optical communication unit 202 in the embodiment. The first communication unit transmits and receives optical signals to and from the second communication device. For example, the communication control unit corresponds to the communication necessity determination units 24 and 204 and the OLT package control unit 218. The communication control unit controls communication of the second communication device. The photoelectric conversion unit converts optical signals received from the second communication device into electricity. When power is not being supplied to the first communication device, the power supply control unit controls the first communication device to start supplying power using the electricity converted by the photoelectric conversion unit. For example, the power supply control unit may control the first communication device to start up from a power-off state in which power supply is stopped using the electricity converted by the photoelectric conversion unit and supply power from the power supply unit to the first communication device.

[0071] The photoelectric conversion unit may convert an optical signal having a predetermined wavelength from the second communication device into electricity when the photoelectric conversion unit receives the optical signal for a predetermined period of time or more from the second communication device, or when the photoelectric conversion unit receives an optical signal having a predetermined emission pattern from the second communication device, so as to start supplying power to the first communication unit.

[0072] The second communication device includes a second communication unit and a control unit. For example, the second communication unit corresponds to the signal transmitting / receiving unit 31, the optical communication unit 301, the signal transmitting / receiving units 311 and 251, and the E / O conversion unit 254 in the embodiments, and the control unit corresponds to the control units 32, 302, 312, and 256 in the embodiments. The second communication unit transmits and receives optical signals to and from the first communication device. The communication control unit may control the second communication unit to transmit an optical signal when the second communication unit has not received an optical signal from the first communication device for a predetermined period of time.

[0073] The first communication unit may notify the second communication device of information about the transmission timing assigned to the second communication device by an optical signal. The second communication unit transmits the optical signal to the first communication device at the transmission timing notified by the first communication unit.

[0074] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and include designs within the scope of the present invention that do not deviate from the gist of the present invention.

[0075] 1, 10, 11, 12, 13, 14, 15 Optical communication system 2 Upper-level device 3 Lower-level device 4 Optical cable 5 Optical splitter 21, 201, 211, 221, 231, 241 Communication package 22, 31, 212, 222, 242, 251, 311 Signal transmitting / receiving unit 23, 203 Package control unit 24, 204 Communication necessity determination unit 32, 256, 302, 312 Control unit 33, 313 UNI 200, 210, 220, 230, 240 OLT 202, 301 Optical communication unit 213, 252 Photoelectric conversion unit 214, 253 Transceiver 215 Communication package control unit 216, 232, 257 Power supply circuit unit 217, 258 Power supply IC 218 OLT package control unit 219 OLT power supply unit 224 Wavelength filter 233 Startup determination unit 250 Media converter 254 E / O conversion unit 255 Copper port 300, 310 ONU 314 Connector unit 500 External power supply 600 Upper level device 700 Terminal device

Claims

1. An optical communication system having a first communication device and a second communication device, wherein the first communication device includes: a first communication unit that transmits and receives an optical signal to and from the second communication device; a communication control unit that controls the communication of the second communication device; a photoelectric conversion unit that converts the optical signal received from the second communication device into electricity; and a power control unit that controls to start power supply in the first communication unit using the electricity converted by the photoelectric conversion unit when power supply is not performed in the first communication unit. Optical communication system.

2. The optical communication system according to claim 1, wherein the photoelectric conversion unit converts the received optical signal into electricity when receiving an optical signal having a predetermined wavelength from the second communication device.

3. The optical communication system according to claim 1, wherein the power control unit controls to start power supply in the first communication unit when the photoelectric conversion unit receives an optical signal from the second communication device for a predetermined time or more, or when receiving an optical signal having a predetermined emission pattern from the second communication device.

4. The second communication device includes: a second communication unit that transmits and receives an optical signal to and from the first communication device; and a control unit that controls to transmit an optical signal from the second communication unit when the second communication unit has not received an optical signal from the first communication device for a predetermined time. The optical communication system according to any one of claims 1 to 3.

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