JP6845747B2 - Subscriber line end station equipment - Google Patents

Description

The present invention relates to a subscriber line end station device.

Communication systems having various configurations are being studied regardless of whether the communication form is fixed or mobile. A communication system having an optical fiber as a medium is called an optical access network. There are two types of optical access network methods: SS (Single Star) method and PON (Passive Optical Network) method.

FIG. 4 is a diagram showing an example of the configuration of the optical access network. In the SS method, one subscriber line terminal unit (ONU: Optical Network Unit) is connected to one subscriber line terminal device (OLT: Optical Line Terminal) via an optical fiber. In the PON method, a plurality of subscriber line termination devices are connected to one subscriber line end station device via an optical fiber and an optical splitter.

Hereinafter, the direction from the subscriber line termination device to the subscriber line end station device is referred to as an "upward direction". Hereinafter, the direction from the subscriber line end station device to the subscriber line end device is referred to as "downward direction". Hereinafter, the signal in the upward direction is referred to as an "up signal". Hereinafter, the signal in the downward direction is referred to as a "down signal".

In the PON system, a plurality of subscriber line termination devices share an optical fiber. In order to prevent collisions between uplink signals, the subscriber line end station device controls the timing at which the subscriber line end station device transmits the uplink signal. The subscriber line end station device controls the transmission timing of the uplink signal by using the MPCP (Multi-Point Control Protocol) message.

The subscriber line terminating device requests the subscriber line end station device for permission to transmit an uplink signal by transmitting a transmission request signal (REPORT message) to the subscriber line end station device. The subscriber line end station device gives permission to transmit an uplink signal to the subscriber line termination device by transmitting a transmission permission signal (GATE message) to the subscriber line termination device (see Non-Patent Document 1). In the PON method, the subscriber line end station device dynamically allocates a band according to the transmission timing to the uplink signal of a plurality of subscriber line end station devices by dynamic band allocation (DBA) in MPCP. assign.

The conventional subscriber line end station device is implemented by dedicated hardware. In recent years, it has been studied to implement some of the functions of the subscriber line end station device in the server device of the data center by software (see Non-Patent Document 2). In Non-Patent Document 2, a part of the management function and the control function of the subscriber line end station device and the subscriber line termination device is executed on the server of the data center. In Non-Patent Document 2, since the functions related to the above-mentioned management and control can be added only by changing the software, speeding up of service introduction can be expected.

IEEE802.3.ah, “IEEE Std 802.3-2012 SECTION FIVE 64.Multipoint MAC Control” L. Peterson et.al., “Central Office Re-architected as a Datacenter”, IEEE Communications Magazine, Vol.54 (10), pp.96-101, 2016.

However, Non-Patent Document 2 is premised on implementing the dynamic bandwidth allocation function by hardware. In order to calculate the dynamic bandwidth allocation at high speed, it is necessary to prepare many calculation resources for each hardware, and there is a problem that the total cost becomes high. Therefore, by converting the dynamic bandwidth allocation function into software and consolidating it in the data center, it is expected that the calculation resources will be reduced due to the aggregation effect.

FIG. 5 is a diagram showing an example of the configuration of the station building of the optical access network. In FIG. 5, the transfer system function of the subscriber line end station device and the control / management system function including the dynamic band allocation function are separated, and then the subscriber line end station is installed in the server device of the data center by software. The device executes high-speed calculation processing such as dynamic bandwidth allocation. On the other hand, the transfer function is implemented by a general-purpose L2 switch or the like. In the configuration, the dynamic allocation function in a plurality of PONs is integrated in the data center, so that the reduction of calculation resources can be expected. The transfer device of the subscriber line end station device transmits the transmission permission signal transmitted from the band allocation device (MPCP function unit) of the subscriber line end station device to the subscriber line end station device.

FIG. 6 is a diagram showing an example of a state in which transmission of a transmission permission signal is in a waiting state. The control signal queue is a queue for transmitting a control signal. The data signal queue is a queue for transmitting a data signal. The transfer device transmits both a data signal including user data and a control signal such as a transmission permission signal to the subscriber line termination device via the PON. The transfer device gives priority to the control signal over the data signal and transmits the control signal from the control signal queue.

However, the conventional subscriber line end station device has a problem that the control signal may not be transmitted in preference to the data signal. That is, when the control signal queue acquires the control signal during the transmission of the data signal which is the downlink signal, the transfer device needs to wait for the transmission of the control signal until the transmission of the data signal is completed. The fact that the transfer device waits for the transmission of the control signal may affect the time when the subscriber line termination device transmits the uplink signal. If the time at which the subscriber line termination device transmits the uplink signal is affected, the uplink signals may collide with each other in the PON.

In view of the above circumstances, an object of the present invention is to provide a subscriber line end station device capable of transmitting a control signal in preference to a data signal.

One aspect of the present invention is a subscriber line end station device including a band allocation device and a transfer device, and the band allocation device is a control signal for transmitting a control signal which is a signal related to control of the subscriber line termination device. The transfer device has a transmission unit, and the transfer device includes a control signal queue for acquiring the control signal, a data signal queue for acquiring a data signal transmitted to the subscriber line termination device, and a transmission time of the control signal. At the transmission time, the control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue, and the acquired control signal is transmitted to the subscriber line termination device. It is a subscriber line end station device having a control unit.

One aspect of the present invention is the subscriber line end station device, wherein the control signal transmission unit transmits a pilot signal in which the transmission time and transfer amount of the control signal are described, and transmits the pilot signal. The transmission of the control signal is started at a time when a predetermined standby time elapses from the time, the control signal queue acquires the control signal and the pilot signal, and the control unit uses the control signal queue to obtain the control signal. Acquiring the data signal from the data signal queue during the period from the time when the pilot signal is acquired until the transmission time elapses, or the period until the transmission of the control signal of the transfer amount is completed at the transmission time. The control signal of the transfer amount is acquired from the control signal queue, and the acquired control signal is transmitted to the subscriber line termination device.

One aspect of the present invention is the subscriber line end station device, further including a timer for transmitting an interrupt signal at a predetermined time, and the control unit starts from the time when the interrupt signal is transmitted. During the period until the transmission time of the control signal elapses, the control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue, and the acquired control signal is obtained from the subscriber line. Send to the termination device.

According to the present invention, the control signal can be transmitted with priority over the data signal.

It is a figure which shows the example of the structure of the optical access network in 1st Embodiment. It is a figure which shows the example of the transmission time secured by using the pilot signal in 1st Embodiment. It is a figure which shows the example of the structure of the optical access network in 2nd Embodiment. It is a figure which shows the example of the configuration of an optical access network. It is a figure which shows the example of the configuration of the station building of an optical access network. It is a figure which shows the example of the state which the transmission of the transmission permission signal is waiting state.

Embodiments of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
FIG. 1 is a diagram showing an example of the configuration of the optical access network 1a. The optical access network 1a is a communication system having an optical fiber as a medium. The optical access network 1a includes a PON 2 and a subscriber line end station device 3a.

The PON 2 includes a plurality of subscriber line termination devices 20. The subscriber line termination device 20 is a device that terminates the downlink signal transmitted by the subscriber line end station device 3a. The format of the downlink signal is the packet format. The PON 2 is a network in which a plurality of subscriber line termination devices 20 are connected to one subscriber line end station device 3a via an optical fiber and an optical splitter. The subscriber line terminating device 20 requests the subscriber line end station device 3a for permission to transmit an uplink signal by transmitting a transmission request signal (REPORT message) to the subscriber line end station device 3a.

The subscriber line end station device 3a is a device for terminating the uplink signal. The subscriber line end station device 3a transmits a transmission permission signal (GATE message) to the subscriber line termination device 20 to give permission to transmit an uplink signal to the subscriber line termination device 20 that has transmitted the transmission request signal. ..

The subscriber line end station device 3a includes a band allocation device 30a and a transfer device 31a. The band allocation device 30a includes an allocation unit 300a. The allocation unit 300a is a functional unit (control signal transmission unit) for transmitting a control signal which is a signal related to the control of the subscriber line termination device 20. The allocation unit 300a dynamically allocates a band according to the transmission timing (transmission time) to the uplink signals of the plurality of subscriber line end station devices by the dynamic band allocation in the MPCP. The allocation unit 300a transmits a control signal such as a transmission permission signal to the transfer device 31a. As a result, the allocation unit 300a can transmit the transmission permission signal to the subscriber line termination device 20 via the transfer device 31a.

The transfer device 31a is a device that transfers a downlink signal to the PON 2. The transfer device 31a transfers both a data signal and a control signal, which are signals including user data, to the PON 2. The control signal is, for example, an MPCP message such as a transmission permission signal (GATE message) or an OAM (Operation, Administration, and Maintenance) message. The transfer device 31a may transfer the uplink signal to the band allocation device 30a or an external device.

The transfer device 31a includes a control signal cue 310a, a data signal cue 320, a control unit 330a, and a transmission unit 340. A part or all of the functional parts of the transfer device 31a are hardware functional parts such as LSI (Large Scale Integration) and ASIC (Application Specific Integrated Circuit), for example. A part or all of these functional units implemented by dedicated hardware such as an L2 switch may be realized by a processor such as a CPU executing a program stored in the storage unit.

The control signal queue 310a acquires a control signal such as a transmission permission signal or an OAM message from the allocation unit 300a. The control signal queue 310a holds the acquired control signal. The control signal queue 310a acquires a pilot signal, which is one of the control signals, from the allocation unit 300a. The control signal queue 310a holds the acquired pilot signal. The data signal queue 320 acquires a data signal, which is a downlink signal, from an external device.

The control unit 330a acquires the pilot signal from the control signal queue 310a. The control unit 330a acquires the control signal from the control signal queue 310a. The control unit 330a acquires the data signal from the data signal queue 320. The control unit 330a gives priority to the control signal over the data signal based on the pilot signal, and transmits the control signal to the transmission unit 340. That is, the control unit 330a secures a transmission time for transmitting the control signal to the transmission unit 340 without transmitting the data signal to the transmission unit 340, based on the pilot signal. The control unit 330a transmits the control signal to the transmission unit 340 without transmitting the data signal to the transmission unit 340 at the time included in the secured transmission time. The control unit 330a transmits the data signal to the transmission unit 340 at a time not included in the reserved transmission time.

The transmission unit 340 acquires a control signal, which is a downlink signal, from the control unit 330a. The transmission unit 340 transfers the control signal to the PON2. The transmission unit 340 acquires a data signal, which is a downlink signal, from the control unit 330a. The transmission unit 340 transfers the acquired data signal to the PON 2. The transmission unit 340 may be integrated with the control unit 330a.

Next, the transmission time secured by using the pilot signal will be described.
FIG. 2 is a diagram showing an example of a transmission time secured by using the pilot signal 100. The allocation unit 300a transmits the pilot signal 100 to the control signal queue 310a before transmitting the control signal 101-1 to the control signal queue 310a. Information indicating the transmission time is described in the pilot signal 100. The transmission time is longer than the time required for the transmission of the control signal 101 scheduled to be transmitted by the allocation unit 300a to the transfer device 31a. In FIG. 2, the transmission time is defined as the time obtained by adding the time during which the allocation unit 300a can transmit the three control signals 101 scheduled to be transmitted to the transfer device 31a and the predetermined standby time. The predetermined waiting time is set to a time equal to or longer than the time required for the data signal queue 320 to transfer the data signal composed of the maximum length packets to the control unit 330a.

The reason why the standby time is set to a time longer than the time required to transfer the data signal composed of the maximum length packet is that the control unit 330a data at the time when the control signal queue 310a acquires the pilot signal. This is because when the signal is acquired, the control unit 330a cannot acquire the control signal 101-1 until the transmission of the data signal composed of the maximum length packet is completed. If the allocation unit 300a transmits the control signal 101-1 to the control signal queue 310a immediately after the pilot signal 100 is transmitted to the transfer device 31a, the control signal queue 310a controls the pilot signal 100. At the time of transmission to 330a, another waiting time is further generated.

The pilot signal 100 includes information representing the number of control signals 101 transmitted by the allocation unit 300a to the transfer device 31a. In FIG. 2, the pilot signal 100 contains information representing 3, which is the number of control signals 101 transmitted by the allocation unit 300a to the transfer device 31a. The allocation unit 300a starts transmitting the control signal 101-1 at a time when the waiting time elapses from the time when the pilot signal 100 is transmitted to the transfer device 31a.

The control unit 330a acquires the pilot signal 100 from the control signal queue 310a. When the control unit 330a acquires the pilot signal 100, the control unit 330a reads out information representing the transmission time from the pilot signal. When the control unit 330a acquires the pilot signal 100, the control unit 330a reads out information representing the number of control signals (transfer amount) from the pilot signal.

When the control unit 330a acquires the pilot signal 100, the control unit 330a acquires the number (transfer amount) of control signals described in the pilot signal 100 from the control signal queue 310a. That is, the control unit 330a acquires the number of control signals 101 described in the pilot signal 100 from the control signal queue 310a before the transmission time elapses from the time when the acquisition of the pilot signal 100 is completed.

The control unit 330a does not acquire the data signal 102 from the data signal queue 320 until the number of control signals 101 described in the pilot signal 100 is acquired from the control signal queue 310a. That is, the control unit 330a acquires the number of control signals 101 described in the pilot signal 100 from the control signal queue 310a, and then acquires the data signal 102 from the data signal queue 320.

As described above, the subscriber line end station device 3a of the first embodiment includes a band allocation device 30a and a transfer device 31a. The band allocation device 30a has an allocation unit 300a as a control signal transmission unit. The transfer device 31a includes a control signal cue 310a, a data signal cue 320, and a control unit 330a. The allocation unit 300a transmits a pilot signal 100 in which the transmission time and the transfer amount of the control signal 101, which is a signal related to the control of the subscriber line termination device 20, are described. The allocation unit 300a starts transmitting the control signal 101 at a time when a predetermined waiting time has elapsed from the transmission time of the pilot signal 100. The control signal queue 310a acquires the control signal 101 and the pilot signal 100. The data signal queue 320 acquires the data signal 102 transmitted to the subscriber line termination device 20. The control unit 330a secures a control signal transmission time. The control unit 330a acquires the control signal from the control signal queue 310a without acquiring the data signal from the data signal queue 320 at the secured transmission time, and transmits the acquired control signal to the subscriber line termination device 20. To do. That is, the control unit 330a is the data signal during the period from the time when the control signal queue 310a acquires the pilot signal 100 until the transmission time elapses, or the period until the transmission of the control signal of the transfer amount is completed in the transmission time. The control signal 101 of the transfer amount is acquired from the control signal queue 310a without acquiring 102 from the data signal queue 320. The control unit 330a transmits the acquired control signal 101 to the subscriber line termination device 20 during the period from the time when the control signal queue 310a acquires the pilot signal 100 until the transmission time elapses. Thereby, the subscriber line end station device 3a of the first embodiment can transmit the control signal with priority over the data signal.

In the subscriber line end station device 3a of the first embodiment, even when the transfer device 31a has a shared bus for the uplink signal and the downlink signal, the transfer of the uplink signal does not affect the transmission time of the control signal 101. It is possible to do so. When the transfer device 31a has a shared bus for the uplink signal and the downlink signal, the control unit 330a uses the uplink signal for the same period as when the control unit 330a stops acquiring the downlink data signal. The transfer of a certain data signal may be temporarily stopped.

(Second Embodiment)
The second embodiment is different from the first embodiment in that the control unit acquires the control signal based on the interrupt signal. In the second embodiment, only the differences from the first embodiment will be described.

FIG. 3 is a diagram showing an example of the configuration of the optical access network 1b. The optical access network 1b is a communication system having an optical fiber as a medium. The optical access network 1b includes a PON 2 and a subscriber line end station device 3b. The subscriber line end station device 3b includes a band allocation device 30b and a transfer device 31b.

The transfer device 31b is a device that transfers a downlink signal to the PON 2. The transfer device 31b transfers both a data signal including user data and a control signal such as a transmission permission signal to PON2. The transfer device 31b includes a control signal cue 310b, a data signal cue 320, a control unit 330b, a transmission unit 340, and a timer 350.

The allocation unit 300b is a control signal transmission unit that transmits a control signal. The allocation unit 300b transmits a control signal 101 such as a transmission permission signal to the transfer device 31b. The timing (transmission time) at which the allocation unit 300b transmits the control signal 101 to the control signal queue 310b is predetermined. For example, the timing at which the allocation unit 300b transmits the control signal 101 to the control signal queue 310b may be a fixed cycle. The allocation unit 300b does not have to transmit the pilot signal 100 to the control signal queue 310b.

The control signal queue 310b acquires the control signal 101, which is a transmission permission signal, an OAM message, or the like, from the allocation unit 300b. The control signal queue 310b holds the acquired control signal 101. The timer 350 outputs an interrupt signal to the control unit 330b immediately before the time when the allocation unit 300b transmits the control signal 101 to the control signal queue 310b. That is, the timer 350 outputs an interrupt signal to the control unit 330b immediately before the time when the control signal queue 310b acquires the control signal 101.

The control unit 330b acquires an interrupt signal from the timer 350 instead of acquiring the pilot signal 100. The control unit 330b acquires the control signal 101 from the control signal queue 310b without acquiring the data signal from the data signal queue 320 until the transmission time elapses from the time when the interrupt signal is acquired from the timer 350. The control unit 330b does not transmit the data signal to the transmission unit 340 until the transmission time elapses from the time when the interrupt signal is acquired from the timer 350, and the control signal 101 for a predetermined time or a predetermined number (transfer amount). Is transmitted to the transmission unit 340.

As described above, the subscriber line end station device 3b of the second embodiment includes the band allocation device 30b and the transfer device 31b. The band allocation device 30b has an allocation unit 300b as a control signal transmission unit. The transfer device 31b includes a control signal cue 310b, a data signal cue 320, a timer 350, and a control unit 330b. The allocation unit 300b transmits a control signal 101, which is a signal related to the control of the subscriber line termination device 20. The control signal queue 310b acquires the control signal 101. The data signal queue 320 acquires the data signal 102 transmitted to the subscriber line termination device 20. The timer 350 transmits an interrupt signal at a predetermined time. The control unit 330b secures a control signal transmission time. The control unit 330b acquires the control signal from the control signal queue 310b without acquiring the data signal from the data signal queue 320 at the secured transmission time, and transmits the acquired control signal to the subscriber line termination device 20. To do. That is, the control unit 330b obtains the control signal 101 from the data signal queue 320 during the period from the time when the interrupt signal is transmitted until the transmission time of the control signal 101 elapses, without acquiring the data signal 102 from the data signal queue 320. Obtained from 310b. The control unit 330b transmits the acquired control signal 101 to the subscriber line termination device 20 during the period from the time when the interrupt signal is transmitted until the transmission time of the control signal 101 elapses. Thereby, the subscriber line end station device 3b of the second embodiment can transmit the control signal with priority over the data signal.

In the subscriber line end station device 3b of the second embodiment, since the control unit 330b does not acquire the pilot signal 100, the configuration of the control unit 330b of the second embodiment is compared with the configuration of the control unit 330a of the first embodiment. Can be simplified. The subscriber line end station device 3b of the second embodiment is particularly effective when the allocation unit 300a transmits a control signal to the transfer device 31b at regular intervals.

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.

The present invention is applicable to a subscriber line end station device of an optical access network.

1a, 1b ... Optical access network, 2 ... PON, 3a, 3b ... Subscriber line end station device, 20 ... Subscriber line termination device, 30a, 30b ... Band allocation device, 31a, 31b ... Transfer device, 100 ... Pilot signal , 101 ... control signal, 102 ... data signal, 300a, 300b ... allocation unit, 310a, 310b ... control signal queue, 320 ... data signal queue, 330a, 330b ... control unit, 340 ... transmission unit, 350 ... timer

Claims (1)

A subscriber line end station device including a band allocation device and a transfer device.
The band allocation device is
It has a control signal transmitter that transmits a control signal that is a signal related to the control of the subscriber line termination device.
The transfer device is
A control signal queue for acquiring the control signal and
A data signal queue for acquiring a data signal transmitted to the subscriber line termination device, and
The transmission time of the control signal is secured, and at the transmission time, the control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue, and the acquired control signal is subscribed to the control signal. have a control unit that transmits to the finisher line termination device,
The control signal transmission unit transmits a pilot signal in which the transmission time and transfer amount of the control signal are described, and starts transmission of the control signal at a time when a predetermined standby time elapses from the transmission time of the pilot signal. ,
The control signal queue acquires the control signal and the pilot signal, and obtains the control signal.
The control unit is the period from the time when the control signal queue acquires the pilot signal until the transmission time elapses, or the period until the transmission of the control signal of the transfer amount is completed in the transmission time. The control signal of the transfer amount is acquired from the control signal queue without acquiring the data signal from the data signal queue, and the acquired control signal is transmitted to the subscriber line termination device.
Subscriber line end station equipment.

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