JP6923787B2 - Home equipment and optical communication method - Google Patents

Description

The present invention relates to a home device and an optical communication method.

In recent years, with the rapid spread of the Internet, there is a demand for an increase in the capacity of optical access systems and economic improvement through sophistication that contributes to OPEX (Operating Expense) and CAPEX (Capital Expenditure). Research on PON (Passive Optical Network) is underway as a method for realizing such a system. PON is to share a transmission line between a center device and an optical passive element among a plurality of users by concentrating a plurality of transmission lines from a plurality of users into a single transmission line by an optical passive element such as an optical power splitter. It is an optical access communication system that is advantageous for economicization.

FIG. 5 shows the configuration of a TDMA (Time Division Multiple Access) -PON system. In the PON system, in order to realize high economic efficiency, the upward direction from the in-house device (ONU: Optical Network Unit) installed in the user's house to the in-station device (OLT: Optical Line Terminal) installed in the telecommunications carrier building. The TDMA technology is applied to the communication of the above, and a communication method in which the bandwidth of the uplink signal is shared by a plurality of users is adopted. Therefore, the transceiver mounted on the ONU uses a burst optical transmitter that transmits an optical signal at a time specified by the OLT, and the transceiver mounted on the OLT uses the optical power level transmitted from the ONU under the OLT. A burst optical receiver is used that can correctly receive different burst optical signals.

Currently in Japan, an economical optical access communication system GE-PON (Gigabit Ethernet®-PON) that shares a 1 Gbps (Gigabit per second) class line capacity with up to 32 users by time division multiplexing (TDM). ) Has been introduced. As a result, FTTH (Fiber to the home) services have become available at realistic rates for users, and have rapidly become widespread.

On the other hand, research on 10 Gbps class 10G-EPON is underway as a next-generation optical access system that can meet the needs for even larger capacities, and standardization was completed at IEEE in 2009. In this method, by increasing the bit rate of the optical transmitter / receiver, it is possible to realize a large capacity while using the same transmission line portion as the existing GE-PON.

K. Hara, S. Kimura, H. Nakamura, N. Yoshimoto, and H. Hadama, "Ultra Fast Response AC-coupled Burst-mode Receiver with High Sensitivity and Wide Dynamic Range for 10G-EPON Systems", OECC2010, 8A4- 2, 2010, p.434-435

The area of the user that can be accommodated by the PON system, that is, the distance from the OLT to the ONU, is defined by the loss budget. The loss budget is a value of allowable transmission loss expressed as a difference between the transmission power of the ONU transmitter and the minimum reception sensitivity of the OLT receiver. Further, in general GE-PON and 10G-EPON, the optical fiber transmission loss of the uplink signal wavelength is larger than that of the downlink signal wavelength, so that the loss budget is dominated by the transmission characteristics of the uplink signal. Expanding these loss budgets and increasing the number of ONUs that can be accommodated by one OLT means increasing the number of users who share the cost, so it is very important from the viewpoint of system economics. On the other hand, in order to expand these loss budgets, additional devices such as optical amplifiers that compensate for optical loss are required in the previous studies, and there are operational issues such as power supply and remote maintenance management. , There was a problem with the cost increase due to the addition of devices.

In view of the above circumstances, an object of the present invention is to provide a home device and an optical communication method capable of improving the loss budget while suppressing the cost.

One aspect of the present invention is the in-house device in an optical access system in which a plurality of in-house devices transmit optical signals to the in-station device by time-division multiple access, and receives an optical signal received from the in-station device. The processing unit, the determination unit that determines the received light power level of the optical signal received and processed by the reception processing unit, and the condition that the received light power level determined by the determination unit is determined to be a low level are satisfied. In this case, the present invention includes a transmission processing unit that transmits an optical signal having an extended preamble length to the in-station device as compared with the case where the above conditions are not satisfied.

One aspect of the present invention is the above-mentioned in-house device, wherein the reception processing unit is an optical receiving unit that converts the optical signal received from the in-station device into an electric signal, and the optical receiving unit that is converted by the optical receiving unit. A current-voltage conversion unit that converts an electric signal current into a voltage and an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit are provided, and the determination unit is converted by the optical reception unit. The received optical power level is determined based on at least one of the generated current of the electric signal and the voltage converted by the current-voltage conversion unit.

One aspect of the present invention is the above-mentioned in-house device, wherein the reception processing unit is an optical receiving unit that converts the optical signal received from the in-station device into an electric signal, and the optical receiving unit that is converted by the optical receiving unit. A current-voltage conversion unit that converts an electric signal current into a voltage and amplifies it, and an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit. The received optical power level is determined based on the electric signal amplification factor in at least one of the conversion unit and the equalization amplification unit.

One aspect of the present invention is the above-mentioned in-house device, wherein the reception processing unit is an optical receiving unit that converts the optical signal received from the in-station device into an electric signal, and the optical receiving unit that is converted by the optical receiving unit. A current-voltage conversion unit that converts an electric signal current into a voltage and amplifies it, and an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit, and the determination unit receives the light. In combination with at least one of the current of the electric signal converted by the unit and the voltage converted by the current-voltage conversion unit, and the electric signal amplification factor in at least one of the current-voltage conversion unit and the equalization amplification unit. Based on this, the received light power level is determined.

One aspect of the present invention is an optical communication method executed by the home device in an optical access system in which a plurality of home devices transmit optical signals to the station device by time division multiplexing access, and an optical signal received from the station device. A reception processing step for performing the reception processing of the above, a determination step for determining the received optical power level of the optical signal received and processed in the reception processing step, and a low level of the received optical power level determined in the determination step. When the condition to be determined is satisfied, it has a transmission processing step of transmitting an optical signal having an extended preamble length to the in-station device as compared with the case where the condition is not satisfied.

According to the present invention, it is possible to improve the loss budget while suppressing the cost.

It is a figure which shows the upstream burst frame composition by embodiment of this invention. It is a figure which shows the structure of the transmission / reception device by 1st Embodiment. It is a figure which shows the structure of the transmission / reception device by 2nd Embodiment. It is a figure which shows the structure of the transmission / reception device by 3rd Embodiment. The configuration of the prior art TDMA-PON system is shown. It is a figure which shows the frame structure of the upstream burst signal of the prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. An embodiment of the present invention relates to an in-home device of an optical access system using TDMA technology applied to TDM-PON or the like.

FIG. 6 is a diagram showing a frame configuration of an uplink burst signal in a conventional PON system. The figure shows the frame configuration of an uplink burst frame used in a PON system in which TDMA technology is applied to uplink signal transmission represented by GE-PON and 10G-EPON. The upstream burst frame shown in the figure is mainly composed of a preamble, a payload, and an end-of-burst frame from the beginning. The preamble is a frame required for synchronization so that the burst optical receiver of the OLT can correctly receive the data in the burst frame. The payload is the frame into which the data to be transmitted is inserted. The end of burst is a frame that marks the end of the burst signal.

In the TDMA-PON system represented by the conventional GE-PON system and the 10GE-PON system, the payload portion of these uplink burst frames is serviced as a variable frame according to the transmission request band of the ONU. On the other hand, fixed frame lengths are assigned to frames such as other preambles. For example, the standardized specifications of a 10G-EPON system define arbitrary fixed values from 800 ns to 1312 ns.

On the other hand, considering the expansion of the loss budget in uplink signal transmission, that is, the improvement of the reception sensitivity characteristics of the burst optical receiver used for OLT, the longer the preamble length of the uplink burst frame, the more relaxed the requirement for the time constant of the receiving circuit. Improvement of the minimum reception sensitivity characteristic of dB can be expected. That is, by extending the length of the preamble frame of the upstream burst frame, improvement of the loss budget can be expected without major modification to the existing system or the like.

FIG. 1 is a diagram showing an uplink burst frame configuration according to the present embodiment. The burst frame configuration shown in FIG. 6 differs from the conventional burst frame configuration shown in FIG. 6 in that the preamble has a variable length.

In the establishment of communication between the OLT and the ONU in the PON system, the ONU receives the control signal transmitted by the OLT and returns a response signal to the control signal from the ONU to the OLT before the control starts. Further, for control such as variable control of the preamble length, the OLT issues an instruction to the ONU. Here, in the conventional preamble frame length (preamble length), when a new ONU is set at a position where an uplink signal cannot be received in the OLT, how can the ONU determine to extend the preamble frame length transmitted by the ONU? The issue is how to do it.

Therefore, in the present embodiment, in order to realize the loss budget expansion effect without adding a device to the existing PON system by extending the length of the preamble frame in the uplink burst frame, the ONU receives from the OLT by its own device. The necessity of frame length expansion is determined by referring to the optical power of the downlink light signal. A detailed embodiment will be described below.

[First Embodiment]
FIG. 2 is a diagram showing a configuration example of the transmission / reception device 2 included in the ONU 1 according to the first embodiment. The transmission / reception device 2 shown in the figure determines the necessity of preamble frame expansion of the uplink burst signal with reference to the downlink signal power level received by the ONU 1 from the OLT. The transmission / reception device 2 includes an optical transmission unit drive unit 21, an optical transmission unit 22, an optical junction demultiplexing unit 23, an optical reception unit 24, a current / voltage conversion unit 25, an equalization amplification unit 26, and a current / voltage level determination unit 27. It is composed of.

The optical transmission unit drive unit 21 drives the optical transmission unit 22. The optical transmission unit 22 converts the uplink signal from an electric signal to an optical signal and outputs the signal to the optical demultiplexing unit 23. The optical combined demultiplexing unit 23 combines and demultiplexes the upstream optical signal and the downstream optical signal. The optical combined demultiplexing unit 23 transmits the uplink optical signal output by the optical transmission unit 22 to the OLT via the optical transmission line. The optical demultiplexing unit 23 outputs an optical signal received from the OLT via the optical transmission line to the optical receiving unit 24. The optical receiving unit 24 receives the downlink optical signal and converts it into an electric signal. The current / voltage conversion unit 25 converts the current photoelectrically converted by the optical reception unit 24 into a voltage and amplifies it. The equalization amplification unit 26 equalizes and amplifies the voltage converted by the current / voltage conversion unit 25. The current / voltage level determination unit 27 determines the downlink signal level based on the current level or voltage level of the stage before input to the equalization amplification unit 26, and is required to expand the preamble of the uplink burst signal based on the determination result of the downlink signal level. Judge whether or not.

According to the configuration shown in FIG. 2, the current / voltage level determination unit 27 estimates the downlink light signal power level by referring to the current component and the voltage component of the downlink light signal received by the optical reception unit 24. The current / voltage level determination unit 27 determines the downlink signal level based on the estimated optical signal power level, and determines the necessity of preamble frame expansion of the uplink burst signal based on the determination result of the downlink signal level.

Specifically, the current / voltage level determination unit 27 sets in advance a threshold value having a margin of several dB from the minimum reception sensitivity for each of the current component and the voltage component. The current / voltage level determination unit 27 determines whether the current component and the voltage component are equal to or higher than the respective threshold values at the time of determining the necessity. The current / voltage level determination unit 27 does not perform preamble expansion when both the current component and the voltage component are equal to or more than the threshold value, and determines to apply the preamble expansion when at least one of them is equal to or less than the threshold value. Alternatively, the current / voltage level determination unit 27 does not perform preamble expansion when at least one of the current component and the voltage component is equal to or more than the threshold value, and applies preamble expansion when both the current component and the voltage component are equal to or less than the threshold value. You may make a judgment to do. These determination results are transmitted from the current / voltage level determination unit 27 to the electronic control circuit unit 3 that controls the ONU 1 as a control signal, and are reflected in the uplink signal frame.

Although FIG. 2 shows a configuration in which both the current component in the subsequent stage of the optical receiving unit 24 and the voltage component in the subsequent stage of the current / voltage conversion unit 25 are referred to, only one of them may be referred to. ..

[Second Embodiment]
The transmission / reception device of the first embodiment determines the downlink power level received by the ONU based on the current level or voltage level of the stage before input to the equalization amplification unit, and determines the necessity of preamble frame expansion of the uplink burst signal. I was judging. The transmission / reception device of the present embodiment determines the downlink power level received by the ONU based on the electrical signal amplification factor, and determines the necessity of preamble frame expansion of the uplink burst signal.

FIG. 3 is a diagram showing a configuration example of a transmission / reception device 2a included in the ONU 1a according to the second embodiment. In the figure, the same parts as ONU1 according to the first embodiment shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. The transmission / reception device 2a shown in the figure includes an optical transmission unit drive unit 21, an optical transmission unit 22, an optical combined demultiplexing unit 23, an optical reception unit 24, a current / voltage conversion unit 25, an equalization amplification unit 26, and a circuit state determination unit 28. Is configured with.

The operations of the optical transmission unit drive unit 21, the optical transmission unit 22, the optical combined demultiplexing unit 23, the optical reception unit 24, the current / voltage conversion unit 25, and the equalization amplification unit 26 are the same as those in the first embodiment. The circuit state determination unit 28 determines the downlink signal level based on the circuit state in the current / voltage conversion unit 25 and the equalization amplification unit 26.

According to the configuration shown in FIG. 3, the circuit state determination unit 28 is the current / voltage conversion unit 25 and the equalization amplification unit 26 that convert and amplify the electrical component of the downlink reception signal photoelectrically converted by the optical reception unit 24. , The downlink power signal power level is estimated by referring to the circuit state such as the amplification factor. The circuit state determination unit 28 determines whether or not the preamble frame expansion of the uplink burst signal is necessary based on the estimated downlink power signal power level.

Specifically, the circuit state determination unit 28 sets in advance a threshold value having a margin of several dB from the minimum reception sensitivity for each of the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26. back. The circuit state is represented by the electrical signal amplification factor. The circuit state determination unit 28 does not perform preamble expansion when both the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26 are equal to or more than the threshold value, and the preamble when at least one of them is equal to or less than the threshold value. Make a decision to apply the extension. Alternatively, the circuit state determination unit 28 does not perform preamble expansion when at least one of the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26 is equal to or more than the threshold value, and both are equal to or less than the threshold value. May make a determination to apply the preamble extension. These determination results are transmitted from the circuit state determination unit 28 to the electronic control circuit unit 3 that controls ONU1a as a control signal, and are reflected in the uplink signal frame.

Although FIG. 3 shows a configuration in which both the circuit state of the current / voltage conversion unit 25 and the circuit state of the equalization amplification unit 26 are referred to, only one of them may be referred to.

[Third Embodiment]
The transmission / reception device of the first embodiment determines the downlink power level received by the ONU based on the current level or voltage level of the stage before input to the equalization amplification unit, and in the second embodiment, the ONU receives the signal. The downlink power level was determined based on the electrical signal amplification factor. In the present embodiment, the downlink power level received by the ONU is determined based on the current level and voltage level of the stage before the input of the equalization amplification unit and the electric signal amplification factor, and whether or not the preamble frame of the uplink burst signal needs to be expanded. To judge.

FIG. 4 is a diagram showing a configuration example of a transmission / reception device 2b included in the ONU 1b according to the third embodiment. In the figure, the same parts as ONU1 according to the first embodiment shown in FIG. 2 and ONU1a according to the second embodiment shown in FIG. 3 are designated by the same reference numerals. The transmission / reception device 2b shown in the figure includes an optical transmission unit drive unit 21, an optical transmission unit 22, an optical combined demultiplexing unit 23, an optical reception unit 24, a current / voltage conversion unit 25, an equalization amplification unit 26, and a current / voltage level determination. It is configured to include a unit 27 and a circuit state determination unit 28.

The operation of the optical transmitter drive unit 21, the optical transmitter unit 22, the optical junction demultiplexer unit 23, the optical receiver unit 24, the current / voltage conversion unit 25, the equalization amplification unit 26, and the current / voltage level determination unit 27 is the first operation. It is the same as the embodiment. The operation of the circuit state determination unit 28 is the same as that of the second embodiment.

According to the configuration shown in FIG. 4, the transmission / reception device 2b improves the downlink light signal power level estimation accuracy by referring to both the circuit state and the current / voltage level, and whether or not the preamble frame expansion of the uplink burst signal is necessary. To judge. Specifically, a threshold value having a margin of several dB from the minimum reception sensitivity is set in advance in the current / voltage level determination unit 27 for each of the current component and the voltage component, and the circuit state determination unit 28 receives the minimum reception in advance. From the sensitivity, a threshold value having a margin of several dB is set for each of the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26.

The current / voltage level determination unit 27 determines whether the current component and the voltage component are equal to or higher than the respective threshold values at the time of determining the necessity. The current / voltage level determination unit 27 does not perform preamble expansion when both the current component and the voltage component are equal to or more than the threshold value, and determines to apply the preamble expansion when at least one of them is equal to or less than the threshold value. Alternatively, the current / voltage level determination unit 27 does not perform preamble expansion when at least one of the current component and the voltage component is equal to or more than the threshold value, and applies preamble expansion when both the current component and the voltage component are equal to or less than the threshold value. You may make a judgment to do. Further, the circuit state determination unit 28 does not perform preamble expansion when both the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26 are equal to or more than the threshold value, and when at least one of them is equal to or less than the threshold value. Makes a decision to apply the preamble extension. Alternatively, the circuit state determination unit 28 does not perform preamble expansion when at least one of the circuit state in the current / voltage conversion unit 25 and the circuit state in the equalization amplification unit 26 is equal to or more than the threshold value, and both are equal to or less than the threshold value. May make a determination to apply the preamble extension.

These determination results are transmitted as control signals from the current / voltage level determination unit 27 and the circuit state determination unit 28 to the electronic control circuit unit 3 that controls ONU1b, and are reflected in the uplink signal frame. For example, when the electronic control circuit unit 3 is determined to apply the preamble extension to at least one of the current / voltage level determination unit 27 and the circuit state determination unit 28, or when it is determined to apply the preamble extension to both of them. , Perform preamble expansion. FIG. 4 shows a configuration in which all the information of the current level or the electric level in the stage before the input of the equalization amplification unit, the circuit state of the current / voltage conversion unit 25, and the circuit state of the equalization amplification unit 26 is referred to. , Any plurality of information among these four pieces of information may be combined and referred to.

According to the embodiment described above, the home device of the optical access system that transmits the time-intermittent optical signal to the station device to which the time division multiplexing access technology is applied includes a reception processing unit, a determination unit, and a transmission processing. It has a part. The reception processing unit is, for example, an optical reception unit 24, a current / voltage conversion unit 25, and an equalization amplification unit 26, and performs reception processing of an optical signal received from an in-station device. The determination unit is, for example, a current / voltage level determination unit 27 and a circuit state determination unit 28, and determines the received optical power level of the optical signal received and processed by the reception processing unit. The transmission processing unit is, for example, the optical transmission unit drive unit 21 and the optical transmission unit 22, and when the reception optical power level determined by the determination unit satisfies the condition determined to be a low level, the condition is not satisfied. An optical signal with an extended preamble length is transmitted to the in-station device.

The reception processing unit includes an optical receiver that converts an optical signal received from an in-station device into an electric signal, a current-voltage converter that converts the current of the electric signal converted by the optical receiver into a voltage and amplifies it, and a current voltage. The configuration may include an equalization amplification unit that equalizes and amplifies the voltage converted by the conversion unit. In this case, the determination unit determines the current of the electric signal converted by the optical receiver, the voltage converted by the current-voltage conversion unit, the electric signal amplification factor in the current-voltage conversion unit, and the electric signal amplification factor in the equalization amplification unit. The received optical power level of the optical signal is determined based on one or more of them.

As a result, when the reception power of the downlink light signal received from the in-station device is at a low level equal to or lower than the specified value, the in-home device extends the preamble length of the uplink burst signal and transmits the signal. Therefore, since it is not necessary to make major modifications to the existing system, etc., the loss budget is suppressed while suppressing the cost increase due to the cost related to the operation such as power supply and remote maintenance management and the cost for adding the cost due to the addition of the device. Can be expanded and improved.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs and the like within a range that does not deviate from the gist of the present invention.

It can be applied to home appliances of optical access systems to which TDMA technology is applied.

1, 1a, 1b ... ONU, 2, 2a, 2b ... Transmitter / receiver, 3 ... Electronic control circuit unit, 21 ... Optical transmitter drive unit, 22 ... Optical transmitter, 23 ... Optical demultiplexer, 24 ... Optical receiver , 25 ... Current / voltage conversion unit, 26 ... Equalization amplification unit, 27 ... Current / voltage level determination unit, 28 ... Circuit state determination unit

Claims (5)

The home device in an optical access system in which a plurality of home devices transmit optical signals to the station device by time division multiplexing access.
A reception processing unit that performs reception processing of the optical signal received from the in-station device, and
A determination unit that determines the received optical power level of the optical signal received and processed by the reception processing unit, and a determination unit.
When the received optical power level determined by the determination unit satisfies the condition determined to be a low level, the transmission processing unit transmits an optical signal having an extended preamble length to the in-station device as compared with the case where the condition is not satisfied. When,
Home device equipped with. The reception processing unit
An optical receiver that converts the optical signal received from the in-station device into an electric signal, and
A current-voltage converter that converts the current of the electric signal converted by the optical receiver into a voltage,
It is provided with an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit.
The determination unit determines the received optical power level based on at least one of the current of the electric signal converted by the optical reception unit and the voltage converted by the current-voltage conversion unit.
The in-home device according to claim 1. The reception processing unit
An optical receiver that converts the optical signal received from the in-station device into an electric signal, and
A current-voltage converter that converts the current of the electric signal converted by the optical receiver into a voltage and amplifies it.
It is provided with an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit.
The determination unit determines the received light power level based on the electric signal amplification factor in the equalization amplification unit.
The in-home device according to claim 1. The reception processing unit
An optical receiver that converts the optical signal received from the in-station device into an electric signal, and
A current-voltage converter that converts the current of the electric signal converted by the optical receiver into a voltage and amplifies it.
It is provided with an equalization amplification unit that equalizes and amplifies the voltage converted by the current-voltage conversion unit.
The determination unit is based on a combination of at least one of the current of the electric signal converted by the optical reception unit and the voltage converted by the current-voltage conversion unit, and the electric signal amplification factor in the equalization amplification unit. To determine the received light power level,
The in-home device according to claim 1. An optical communication method executed by the home device in an optical access system in which a plurality of home devices transmit optical signals to the station device by time division multiplexing access.
A reception processing step for receiving an optical signal received from the in-station device, and a reception processing step.
A determination step for determining the received optical power level of the optical signal received and processed in the reception processing step, and a determination step.
When the received optical power level determined in the determination step satisfies the condition determined to be a low level, a transmission processing step of transmitting an optical signal having an extended preamble length to the in-station device as compared with the case where the condition is not satisfied. When,
Optical communication method having.

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