JP4768668B2 - Communication system, subscriber terminal, station side device, communication method and program - Google Patents

Description

  The present invention relates to a communication system, and in particular, when a dicing gasp and a transmission band allocation request are sent from a subscriber terminal to a station side apparatus, the station side apparatus assigns the highest priority band to the subscriber terminal. The allocation and subscriber terminal relates to a communication system for transmitting high priority data using the allocated bandwidth.

  Conventionally, in a network in which one station-side device and a plurality of in-house transmission devices (subscriber terminals) are connected, the in-home transmission device is in a dicing gap when the in-home transmission device is almost inoperable due to a power failure or the like. (DyingGasp) is sent to the station side device. The station side device that has received the diing gasp has taken down the link of the port to which the in-home transmission device that has sent the diing gasp is connected. Such a conventional technique is described in Patent Document 1.

  The above contents will be described with reference to a time chart FIG.

  Conventionally, when a dieing gasp factor is generated in the ONU and the dieing gasp is transmitted from the ONU to the OLT, the OLT disconnects the connection with the ONU even if the ONU is still communicable. Then, after sending the diving gasp, even if the ONU has high priority data with high urgency, the data cannot be transmitted to the OLT. As a result, data that should be sent before the ONU becomes inoperable, such as an emergency call, has also been discarded.

  Here, the station side device in Patent Document 1 corresponds to the Optical Line Terminal (OLT) of the present invention, and the in-home transmission device in Patent Document 1 corresponds to the Optical Network Unit (ONU) of the present invention.

JP 2004-015645 A

In the station side device that has received the above-described conventional diing gasp, since the link with the in-home transmission device that sent the diing gasp after receiving the diing gasp is down (disconnecting the network), the in-home transmission device is Even after the sending, even if the operation is possible using the built-in battery or the like, no data can be sent to the station side device after sending the dieing gasp. For this reason, there is a problem that even when high-priority data with high urgency is present in the in-home transmission device at the time of sending the diving gasp, the data cannot be transmitted.
[Object of invention]
An object of the present invention is to provide a communication system, a subscriber terminal, a station-side device, a communication method, and a program that solve the above-described conventional problems.

The communication system according to the present invention includes a diing gasp factor detection circuit that detects that the inoperable state is close, and transmission that classifies input data into high priority data and low priority data according to a predetermined condition. When it is detected that the priority classification unit and the diing gasp factor detection circuit are in an inoperable state, a first signal is transmitted to notify the fact that the high level is classified by the transmission priority classification unit. When there is priority data, an uplink transmission bandwidth request is further transmitted when transmitting the first signal, and when the requested transmission bandwidth is allocated , the transmission priority classification unit classifies a subscriber terminal and a transmission unit that transmits using this band high priority data, when receiving only said first signal to disconnect the link with the subscriber terminal Having a central terminal having OLT control unit for allocating a transmission band of the highest priority to the subscriber terminal that has sent the first signal when receiving a transmission bandwidth request of the first signal and the uplink It is characterized by that.

The subscriber terminal according to the present invention classifies the diving gasp factor detection circuit for detecting that the inoperable state is close and the data to be input into high priority data and low priority data according to a predetermined condition. When it is detected that the transmission priority classifying unit and the diing gasp factor detection circuit are in an inoperable state, a first signal is transmitted to indicate that the classification is performed by the transmission priority classifying unit. When there is high-priority data, an uplink transmission band request is further transmitted when transmitting the first signal, and the highest priority band is transmitted from the station side apparatus connected to the transmission band request. A transmission unit that transmits the high-priority data classified by the transmission priority classification unit using the bandwidth when allocated.

The station side device of the present invention detects that the inoperable state is near, classifies the data to be input into high priority data and low priority data according to a predetermined condition, and the inoperable state When a close signal is detected, a first signal is transmitted to notify that, and when there is data with a high priority, an uplink transmission bandwidth request is further transmitted when transmitting the first signal. a central terminal for allocating a transmission band to the subscriber terminal, is the only pre-Symbol subscriber terminal or found the first signal when receiving disconnects the link with the subscriber terminal, the subscriber who when receiving a previous SL first signal and the transmission bandwidth request from the terminal and having an OLT control unit for allocating a transmission band of the highest priority to the subscriber terminal which transmitted said first signal.

The communication method of the present invention is a communication method for communicating data between a subscriber terminal and a station side device, and detecting a diing gasp factor detecting that the subscriber terminal is nearly inoperable. A step of classifying the input data into high priority data and low priority data according to a predetermined condition, and the subscriber terminal in the dicing gasp factor detection step. When there is a high-priority data classified by the classification step and a step of transmitting a first signal to that effect to the station-side device when it is detected that the inoperable state is near , said subscriber terminal, a step of further transmitting a transmission bandwidth request uplink to the station side device when transmitting the first signal, the station-side apparatus, only the first signal Upon signal disconnects the link with the subscriber terminal, when receiving a transmission bandwidth request of the first signal and the uplink is the highest-priority subscriber terminal transmitting said first signal A step of allocating a transmission band; and when the requested transmission band is allocated by the subscriber terminal, the high-priority data classified in the classification step is transmitted to the station side device using the band. And a step of performing.

The program of the subscriber terminal according to the present invention is a dicing gasp factor detection process for detecting that the inoperable state is close, and the input data is classified into high priority data and low priority data according to predetermined conditions. When the transmission priority classification process for classification and the diing gasp factor detection process detect that the inoperable state is close, a first signal is transmitted to that effect, and classification is performed by the transmission priority classification process. When there is high priority data transmitted, an uplink transmission band request is further transmitted when transmitting the first signal, and the station side apparatus connected to the transmission band request has the highest priority. using this band when the band is allocated, this to execute a transmission process, to a computer to transmit data of high priority that has been classified by the transmission priority classification process The features.

The station device program of the present invention detects that the inoperable state is near, classifies the data to be input into high priority data and low priority data according to a predetermined condition, When it is detected that the state is close, a first signal is transmitted to that effect, and when there is data with high priority, a further transmission bandwidth request is made when transmitting the first signal. a subscriber program is causing station side apparatus executes the process to the computer to assign a transmission band to the terminal that transmits the subscriber only pre Symbol subscriber terminal or found the first signal when receiving cutting the link with the terminal, when receiving a previous SL first signal and the transmission bandwidth request from the subscriber terminal assigns a transmission band of the highest priority to the subscriber terminal that has sent the first signal processing The Program the station side device, characterized in that to execute the Yuta.

In the present invention, the subscriber terminal classifies the input data into data having high priority and data having low priority, and when detecting that the subscriber terminal is almost inoperable, On the other hand, a first signal that informs that is transmitted, and when there is data with high priority, an uplink transmission band request is further transmitted when the first signal is further transmitted . In line terminal is for the subscriber terminal that received only the first signal to disconnect the link, you assign a transmission band of the highest priority for the subscriber terminal which has transmitted the transmission bandwidth request. The subscriber terminal assigned the highest priority transmission band uses this band to transmit the classified high priority data to the station side device. Therefore, in the present invention, even when the first signal indicating that the subscriber terminal is almost inoperable is transmitted to the station side device, the subscriber terminal transmits the high priority data to the station side. This has the effect that it can be transmitted to the device.

  The present invention relates to a subscriber terminal Optical Network Unit (ONU) and a station side apparatus Optical Line Terminal after sending a diving gasp in a passive optical network (PON), particularly a Gigabit Ethernet (registered trademark) -passive optical network (GE-PON). The invention relates to transmission and reception of signals between (OLT).

  Prior to the description of the embodiment of the present invention, first, a diing gasp related to the present invention defined in IEEE 802.3ah will be briefly described.

  In the GE-PON standard IEEE 802.3ah, the following contents are defined. The dicing gasp that is sent from the ONU to the OLT when it is almost impossible to operate the terminal due to a power failure or the like is notified in the Flags field of Operations, Administration, and Maintenance Protocol Data Units (OAMPDU). It is sent with the highest priority among the data to be sent. When the ONU deviates from the GE-PON network managed by the OLT, the ONU must continue to operate until the sending of the dieing gasp is completed.

  Further, in the transmission of diing gasp caused by a decrease in the power supply voltage on the ONU side, it is common to guarantee continuous operation for a certain time with a capacitor or a battery.

  Next, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing the configuration of the first exemplary embodiment of the present invention. As shown in FIG. 1, in the GE-PON in which one optical line 52 is shared by a plurality of subscriber terminals, the first embodiment includes an OLT 30 installed in a center station, an ONU 20 installed in a subscriber's house, 21, 22, optical lines 50, 52, and the like capable of optical communication defined by IEEE 802.3ah, and a coupler 41 that branches the lines for a plurality of subscriber terminals in GE-PON. . The ONU 21 and the ONU 22 are subscriber terminals different from the ONU 20 branched and connected by the coupler 41.

  Communication transmitted from the OLT 30 via the coupler 41 to the ONUs 20, 21, 22 using the optical lines 52, 50, etc. is referred to as downlink communication. Further, the OLT 30 allocates an upstream transmission band to each ONU, and communication transmitted from the ONUs 20, 21, and 22 to the OLT 30 using the allocated band is defined as upstream communication.

  The ONU 20 can be connected to an optical line 50, a communication terminal 40 such as a personal computer, and an emergency notification device 45 such as a fire alarm, and has the following functional blocks.

  The ONU 20 includes a control unit 1 that controls the operation of the ONU 20, an optical connection unit 2 that can connect the optical line 50, a LAN connection unit 3 that can connect the communication terminal 40 and the emergency call device 45, and a LAN connection unit 3. A transmission priority classifying unit 4 that classifies data frames input via the high priority data frame and the low priority data frame according to a predetermined rule, and the high priority data frame and the low data frame. A priority condition setting unit 5 for setting a condition for classification, a low priority queue 6 for storing data frames classified by the transmission priority classification unit 4 until they are transmitted, and a transmission priority classification It is dynamically allocated by the high priority queue 7 that stores data frames classified by the unit 4 until high priority is transmitted, and GE-PON Dynamic Bandwidth Allocation (DBA). A transmission allocation control unit 8 that stores in the transmission buffer 9 data frames that are actually transmitted according to the allocated upstream band, and stores data frames that are determined to be transmitted using the dynamically allocated upstream band. The transmission buffer 9, the transmission unit 10 that transmits the data frame stored in the transmission buffer 9 to the OLT 30 through the optical connection unit 2, and a diing gasp (Dying Gasp) such as a power supply voltage drop of the ONU 20 need to be transmitted A dicing gasp factor detection circuit 11 for detecting a factor, a receiving unit 12 for receiving a downlink data frame from the optical line 50 via the optical connection unit 2, and a data frame received by the receiving unit 12 are assigned to the ONU 20. And a reception analysis unit 13 for extracting the upstream band.

  The OLT 30 can connect an optical line 52 and a network 51 such as the Internet, and has the following functional blocks.

  An OLT control unit 31 that controls the operation of the OLT 30, an OLT optical connection unit 32 that can connect the optical line 52, an OLT network connection unit 33 that can connect the network 51, and the optical line 52 via the OLT optical connection unit 32. An OLT reception unit 34 that receives an upstream data frame, an OLT reception analysis unit 35 that extracts control information such as information on a bandwidth allocation request from the ONU and dicing gasp from the data frame received by the OLT reception unit 34, OLT transmission band allocation table 36 for storing the status of the uplink transmission band allocated to each ONU 20, 21, 22; OLT transmission control unit 37 for allocating the uplink transmission band for each ONU 20, 21, 22; and transmission control OL for sending control information such as band allocation information from the unit 37 to the optical line 52 And a transmission unit 38.

  Although the configuration of the first embodiment has been described in detail above, the GE-PON defined in IEEE 802.3ah and the DBA that dynamically allocates the upstream bandwidth are well known to those skilled in the art, and the present invention Since the relationship with is thin, detailed description thereof is omitted.

  Next, the operation of the first embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 2 is a flowchart showing an outline of the operation.

  Hereinafter, an operation in which data from the emergency notification device 45 with high urgency is preferentially transmitted to the OLT 30 when the ONU 20 transmits the diving gasp will be described.

  As a premise, in the priority classification condition of the priority condition setting unit 5, it is assumed that the data from the communication terminal 40 is set to a low priority and the data from the emergency call device 45 is set to a high priority. In addition, it is assumed that the cause of occurrence of the dieing gasp is a decrease in the power supply voltage of the ONU 20.

  The operation example of the first embodiment is shown below.

  When the dieing gasp factor detection circuit 11 detects a power supply voltage drop of the ONU 20 due to a power failure or the like (step 101), the control unit 1 transmits the dieing gasp to the OLT 30 via the transmission allocation control unit 8 (step 102).

  After the diving gasp transmission, the control unit 1 of the ONU 20 confirms whether data from the emergency call device 45 exists in the high priority queue 7 (step 103).

  If there is no data in the high priority queue 7 (No in Step 103), the ONU 20 stops its operation as it is (Step 108).

  When data from the emergency call device 45 exists in the high priority queue 7 (Yes in Step 103), the control unit 1 requests the OLT 30 to allocate an upstream band for data transmission (Step 104).

  Further, the control unit 1 discards the data in the transmission buffer 9 in order to preferentially send the data in the high priority queue 7 and stores the data in the high priority queue 7 in the transmission buffer 9 (step 105). ).

  The OLT reception analysis unit 35 of the OLT 30 analyzes data from the ONU 20 received by the reception unit 34. When the OLT reception analysis unit 35 detects the dicing gasp from the ONU 20 (Yes in Step 109), the OLT control unit 31 confirms whether bandwidth allocation is requested from the ONU 20 while maintaining the connection with the ONU 20 ( Step 110).

  When there is no bandwidth allocation request from the ONU 20 (No in Step 110), the OLT control unit 31 disconnects the ONU 20 from the link (Step 114).

  When there is a bandwidth allocation request from the ONU 20 (Yes in Step 110), the OLT control unit 31 receives the request from the ONU 20 at the earliest time among the bandwidths allocated in the uplink direction stored in the OLT transmission bandwidth allocation table 36. Reallocate bandwidth (time) so that data can be transmitted.

  The rearranged bandwidth allocation information is notified to the ONU 20 via the OLT transmission control unit 37 (step 111).

  Here, a recombination example of bandwidth allocation in the transmission bandwidth allocation table 36 will be described with reference to FIG.

  The upper diagram of FIG. 3 shows an example of normal bandwidth allocation in the OLT transmission bandwidth allocation table 36. In this state (the upper diagram in FIG. 3), the ONU 20 can transmit data only after data transmission between the ONU 22 and the ONU 21. For this reason, since it takes a long time until the transmission allocation band (time) of the ONU 20 as it is, there is a possibility that the ONU 20 falls into an inoperable state before sending data.

  In order to avoid this, the OLT control unit 1 of the OLT 30 rearranges the OLT transmission band allocation table 36 so that the ONU 20 can transmit the earliest (the lower diagram in FIG. 3). The state of the OLT transmission band allocation table 36 after this recombination is performed is shown in the lower diagram of FIG.

  Here, the description returns to the flowchart of FIG.

  When the transmission band is allocated from the OLT 30 (Yes in Step 106), the control unit 1 of the ONU 20 transmits the data from the emergency call device 45 stored in the transmission buffer 9 in the designated band (time) (Step S1). 107).

  When receiving data from the ONU 20, the OLT 30 transmits this data to the network 51 through the OLT network connection unit 33 (step 113), and then disconnects the ONU 20 from the link (step 114).

  With the above operation, the data from the emergency call device 45 can be sent to the network 51 before the ONU 20 becomes inoperable due to the cause of the diing gasp.

  Next, the contents of the present embodiment will be described with reference to the time chart FIG.

  In the present embodiment, when a highly urgent data transmission request is generated after a cause of a diing gasp occurs in the ONU, a transmission bandwidth request is transmitted after the diing gasp is transmitted from the ONU to the OLT. The The OLT that has received the transmission bandwidth request assigns the earliest (highest priority) transmission bandwidth to the ONU. Then, the ONU transmits data with high urgency and high priority to the OLT using the earliest transmission band.

  In the present embodiment described above, when a transmission bandwidth request is transmitted after the diving gasp is transmitted from the ONU 20 to the OLT 30, the OLT 30 allocates the earliest transmission bandwidth to the ONU 20, and therefore the ONU 20 transmits the diing gasp. Data can be transmitted even later.

  In addition, since the data to be transmitted at this time is highly urgent and high priority data, the ONU 20 must transmit urgent and high priority data to the OLT 30 even after the diving gasp transmission. Is possible.

  Next, a second embodiment of the present invention will be described with reference to the drawings.

  Since the configuration of the second embodiment is the same as the configuration of the first embodiment (FIG. 1), description thereof is omitted.

  The operation of the second embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 5 is a flowchart showing an outline of the operation.

  Hereinafter, an operation in which high priority data with high urgency from the emergency call device 45 is preferentially transmitted to the OLT 30 when the ONU 20 transmits the diving gasp will be described.

  As a premise, in the priority classification condition of the priority condition setting unit 5, it is assumed that the data from the communication terminal 40 is set to a low priority and the data from the emergency call device 45 is set to a high priority. In addition, it is assumed that the cause of occurrence of the dieing gasp is a decrease in the power supply voltage of the ONU 20.

  The operation example of the second embodiment is shown below.

  When the diving gasp factor detection circuit 11 detects a power supply voltage drop of the ONU 20 due to a power failure or the like (step 201), the control unit 1 of the ONU 20 determines whether data from the emergency notification device 45 exists in the high priority queue 7 or not. Confirm (step 202).

  When there is no data in the high priority queue 7 (No in Step 202), the control unit 1 of the ONU 20 transmits the diing gasp to the OLT 30 (Step 204), and the ONU 20 stops its operation as it is (Step 208). .

  When data from the emergency call device 45 exists in the high priority queue 7 (Yes in Step 202), the control unit 1 transmits a dicing gasp and an upstream bandwidth allocation request for data transmission to the OLT 30. (Step 203).

  Further, the control unit 1 discards the data in the transmission buffer 9 in order to preferentially send the data in the high priority queue 7 and stores the data in the high priority queue 7 in the transmission buffer 9 (step 205). ).

  The OLT reception analysis unit 35 of the OLT 30 analyzes data from the ONU 20 received by the reception unit 34. When detecting the dicing gasp from the ONU 20 (Yes in Step 209), the OLT reception analysis unit 35 analyzes whether or not bandwidth allocation is requested from the ONU 20 while maintaining the connection with the ONU 20 (Step 210).

  When there is no bandwidth allocation request from the ONU 20 (No in Step 210), the OLT control unit 31 disconnects the ONU 20 from the link (Step 214).

  When there is a bandwidth allocation request from the ONU 20 (Yes in Step 210), the OLT control unit 31 receives the request from the ONU 20 at the earliest time among the bandwidths allocated in the uplink direction stored in the OLT transmission bandwidth allocation table 36. Reallocate bandwidth (time) so that data can be transmitted.

  The reconfigured band allocation information is notified to the ONU 20 via the OLT transmission control unit 37 (step 211).

  When the transmission band is allocated from the OLT 30 (Yes in Step 206), the control unit 1 of the ONU 20 transmits the data from the emergency call device 45 stored in the transmission buffer 9 in the designated band (time) (Step S1). 207).

  When the OLT 30 receives data from the ONU 20 (Yes in step 212), the OLT 30 transmits the data to the network 51 via the OLT network connection unit 33 (step 213).

  With the above operation, the data from the emergency call device 45 can be sent to the network 51 before the ONU 20 becomes inoperable due to the cause of the diving gasp.

  In the second embodiment, since the diving gasp and the transmission band request are transmitted simultaneously, when the transmission band request is sent from the ONU 20 to the OLT 30, the OLT 30 is almost the same as the reception of the diing gasp. At the same time, a transmission bandwidth request is received. For this reason, it is possible to determine whether there is a transmission bandwidth request almost simultaneously with the reception of the diving gasp, so that the processing of the OLT 30 at the time of receiving the diing gasp can be speeded up.

  In the first and second embodiments described above, high-priority data is stored in the high-priority queue. However, even if a dedicated queue such as the high-priority queue is not used, the transmission source and destination IP The priority of data may be determined by referring to identification information or the like included in data stored in an address or payload.

  In the first and second embodiments, after the data stored in the transmission buffer 9 scheduled to be transmitted is discarded, the data in the high priority queue 7 is stored in the transmission buffer 9. However, it is also possible to confirm the priority of the data in the transmission buffer 9 and to transmit without discarding if there is high priority data.

  In the above description, the present invention has been described on the assumption that the present invention is realized in hardware. However, each function of the present invention can be realized by a program read by the CPU.

Block diagram of a communication system in the first and second embodiments The flowchart which shows operation | movement of 1st Embodiment. The conceptual diagram which shows the change condition of the OLT transmission bandwidth allocation table of 1st Embodiment Time chart showing the operation of the first embodiment The flowchart which shows operation | movement of 2nd Embodiment. Time chart showing operation of background technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 Optical connection part 3 LAN connection part 4 Transmission priority classification | category part 5 Priority condition setting part 6 Low priority queue 7 High priority queue 8 Transmission allocation control part 9 Transmission buffer 10 Transmission part 11 Dying gasp factor detection circuit 12 receiving unit 13 receiving analyzing unit 20 ONU
21 ONU
22 ONU
30 OLT
31 OLT control unit 32 OLT optical connection unit 33 OLT network connection unit 34 OLT reception unit 35 OLT reception analysis unit 36 OLT transmission bandwidth allocation table 37 OLT transmission control unit 38 OLT transmission unit 40 communication terminal 41 coupler 45 emergency call device 50 optical line 51 Network 52 Optical line

Claims (14)

A diving gasp factor detection circuit for detecting that the state of being inoperable is near,
A transmission priority classifying unit that classifies input data into high priority data and low priority data according to a predetermined condition;
When it is detected that the state in which the diving gasp factor detection circuit becomes inoperable is close, a first signal is transmitted to that effect, and there is high priority data classified by the transmission priority classification unit further transmits a transmission bandwidth request uplink when transmitting the first signal when, during the transmission band that the request is assigned, the high priority that is classified by the transmission priority classification unit A transmitter for transmitting data using this band;
A subscriber terminal having
When receiving only said first signal to disconnect the link with the subscriber terminal, when receiving a transmission bandwidth request of the first signal and the uplink transmits the first signal A station side device having an OLT control unit for allocating the highest priority transmission band to the subscriber terminal;
A communication system comprising:   The communication system according to claim 1, wherein the uplink transmission band request is transmitted after the transmission of the first signal.   The communication system according to claim 1, wherein the uplink transmission band request is transmitted simultaneously with the transmission of the first signal.   The communication system according to any one of claims 1 to 3, wherein the high priority data is stored in a high priority queue of a subscriber terminal.   The communication system according to any one of claims 1 to 4, wherein it is determined whether or not the data is high priority data based on the identification information of the data. A diving gasp factor detection circuit for detecting that the state of being inoperable is near,
A transmission priority classifying unit that classifies input data into high priority data and low priority data according to a predetermined condition;
When it is detected that the state in which the diving gasp factor detection circuit becomes inoperable is close, a first signal is transmitted to that effect, and there is high priority data classified by the transmission priority classification unit In this case, when transmitting the first signal, an uplink transmission band request is further transmitted, and when the highest priority band is allocated in the station side apparatus connected to the transmission band request, this band is transmitted. A transmission unit for transmitting high priority data classified by the transmission priority classification unit , and
A subscriber terminal. When it is detected that the inoperable state is close, and the input data is classified into high priority data and low priority data according to a predetermined condition, and when it is detected that the inoperable state is close Transmitting a first signal to that effect, and when there is data having a high priority, transmits the first signal to a subscriber terminal that further transmits an uplink transmission bandwidth request. A station-side device that allocates bandwidth,
Before SL subscriber only when the received terminal or al the first signal to disconnect the link with the subscriber terminal, when receiving a previous SL first signal and the transmission bandwidth request from the subscriber terminal station apparatus characterized by having an OLT control unit for allocating a transmission band of the highest priority to the subscriber terminal that has sent the first signal to. A communication method for communicating data between a subscriber terminal and a station side device,
Dying gasp factor detection step for detecting that the subscriber terminal is close to an inoperable state; and
The subscriber terminal classifies input data into data having high priority and data having low priority according to a predetermined condition;
A step of transmitting to the station side device a first signal indicating that when the subscriber terminal detects that the inoperable state is close in the dicing gasp factor detection step;
When there is high priority data classified by the classification step, the subscriber terminal further transmits an uplink transmission band request to the station side device when transmitting the first signal. When,
The station-side apparatus, wherein when the only receiving the first signal disconnects the link with the subscriber terminal, when receiving a transmission bandwidth request of the first signal and the uplink claim Assigning the highest priority transmission band to the subscriber terminal that has transmitted one signal;
The subscriber terminal, when the requested transmission band is allocated, has the step of transmitting the high priority data classified in the classification step to the station side device using the band. A characteristic communication method.   The communication method according to claim 8, wherein the uplink transmission band request is transmitted after the transmission of the first signal.   9. The communication method according to claim 8, wherein the uplink transmission band request is transmitted simultaneously with the transmission of the first signal.   The communication method according to any one of claims 8 to 10, wherein the high priority data is stored in a high priority queue of a subscriber terminal.   12. The communication method according to claim 8, wherein whether or not the data is high priority data is determined based on the data identification information. Dying gasp factor detection processing for detecting that the state where the operation becomes impossible is near,
A transmission priority classification process for classifying input data into high priority data and low priority data according to a predetermined condition;
When it is detected that the inoperable state is close in the diving gasp factor detection process, a first signal is transmitted to that effect, and high priority data classified by the transmission priority classification process exists. In this case, when transmitting the first signal, an uplink transmission band request is further transmitted, and when the highest priority band is allocated in the station side apparatus connected to the transmission band request, this band is transmitted. A transmission process for transmitting high priority data classified by the transmission priority classification process , and
A program for a subscriber terminal, which causes a computer to execute. When it is detected that the inoperable state is close, and the input data is classified into high priority data and low priority data according to a predetermined condition, and when it is detected that the inoperable state is close Transmitting a first signal to that effect, and when there is data having a high priority, transmits the first signal to a subscriber terminal that further transmits an uplink transmission bandwidth request. A program for a station-side device that causes a computer to execute processing for allocating a bandwidth,
Before SL subscriber only when the received terminal or al the first signal to disconnect the link with the subscriber terminal, when receiving a previous SL first signal and the transmission bandwidth request from the subscriber terminal central terminal program, characterized in that to execute a process of allocating a transmission band of the highest priority to the subscriber terminal that has sent the first signal to the computer to.

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