JPH11252035A - Band allocation method and transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission technique capable of preventing cell abandonment by the buffer overflow of a subscriber's device. SOLUTION: In this transmission system, the subscriber's devices 2a-2n are star-connected to a station side device 1 and the communication of the time division multiple access system of a cell base for setting and managing the band of the subscriber's devices 2a-2n from the station side device 1 is performed. Buffer storage information is reported from the subscriber's devices 2a-2n to the station side device 1, and in the station side device 1. Based on the reported buffer storage information and a free band at present, the band of the subscriber's devices 2a-2n in allocated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission system, and more particularly, to a station apparatus in which a plurality of subscriber units are star-coupled,
The present invention relates to a transmission technology for performing cell-based time division multiple access communication for setting and managing bands of the plurality of subscriber devices from the station side device.

[0002]

2. Description of the Related Art Conventionally, in a transmission system for performing cell-based TDMA communication in which a plurality of subscriber units are star-coupled to a station side device and a band of the subscriber unit is set and managed from the station side device, the station side device has The bandwidth of the subscriber device was specified.

[0003]

However, in this case, even when the buffer storage capacity of the subscriber unit is increased, the subscriber unit cannot request a change of the band. Therefore, there is a problem that cell discard occurs due to buffer overflow. Therefore, an object of the present invention is to declare the buffer storage capacity of the subscriber unit to the optical line terminal and allocate an extra band according to the available band, thereby preventing cell discard due to buffer overflow of the subscriber unit. To provide a transmission technology.

[0004]

According to the present invention, a plurality of subscriber units are star-coupled to an optical line terminal, and a cell-based time division multiple unit for setting and managing bands of the plurality of subscriber units from the optical line unit. A bandwidth allocation method in a transmission system that performs communication of a connection method, comprising: a step of causing a subscriber device to declare buffer storage information to an optical line terminal; and a step of: Allocating a bandwidth of the subscriber device based on the bandwidth.

[0005] In the step of allocating the band, the vacant band is larger than the buffer storage amount indicated by the buffer storage information declared by the subscriber unit, and the subscriber unit is provided with the buffer storage amount corresponding to the buffer storage amount. In addition, when the free bandwidth is smaller than the buffer storage amount indicated by the buffer storage information declared by the subscriber device, the free bandwidth is assigned to the current bandwidth. It is preferable to assign it in addition to the band.

In the step of declaring buffer storage information, a predetermined threshold value is compared with the buffer storage amount, and if the buffer storage amount is larger than the threshold value, the buffer storage amount is declared, and the buffer storage amount is declared. If the buffer storage amount is declared to be zero when the buffer storage amount is smaller than the threshold value and the bandwidth of the subscriber device is assigned in the step of allocating the bandwidth of the subscriber device, if the buffer storage amount is declared as zero by the subscriber device, the subscriber device is newly notified. The added band may be released.

According to the present invention, a plurality of subscriber units are star-coupled to an optical line terminal, and communication of a cell-based time division multiple access system for setting and managing bands of the plurality of subscriber units from the optical line unit is performed. A transmission system, wherein each subscriber device comprises:
The station-side device includes a reporting unit that monitors the buffer accumulation amount and declares the buffer accumulation amount to the optical line terminal, and a cell transmitting unit that transmits cells in a band specified by the optical line-side device. Bandwidth allocation control means for determining a bandwidth to be newly added to the subscriber device based on the buffer storage amount declared by the subscriber device and the current available bandwidth; and And notification means for notifying the user.

[0008] The bandwidth allocation control means compares the buffer storage amount declared by the subscriber unit with the free band, and if the buffer storage amount is larger than the free band, the bandwidth allocation control means sends a signal to the subscriber unit. A bandwidth corresponding to the buffer storage amount is additionally allocated to the current bandwidth, and when the free bandwidth is smaller than the buffer storage amount, a free bandwidth is additionally allocated to the subscriber device to the current bandwidth. It is preferably a means.

[0009] Further, the subscriber unit includes a storage unit in which a predetermined threshold value is stored, a comparison unit that compares the buffer storage amount with the threshold value, and receives the result of the comparison unit and sets the buffer storage amount to the threshold value. Means for notifying the station side device when the buffer accumulation amount is larger than the threshold, and notifying the station side device of the buffer accumulation amount as zero when the buffer accumulation amount is smaller than the threshold value. The side device may be configured by adding means for releasing the bandwidth added to the subscriber device when the buffer storage amount is notified from the subscriber device as zero.

[0010]

Embodiments of the present invention will be described.
The present invention relates to a transmission system for performing cell-based TDMA communication in which a plurality of subscriber units are star-coupled to an optical line unit and a bandwidth of the subscriber unit is set and managed from the optical line unit. To provide a configuration that can automatically change the band in accordance with.

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical line terminal, 2a to 2n denote subscriber devices, 3 denotes an optical fiber transmission line, and 4 denotes a star coupler.
A plurality of subscriber units 2a to 2n are connected to the optical line terminal 1 via an optical fiber transmission line 3 and a star coupler 4. In the above configuration, the subscriber units 2a to 2n
Reports the information stored in the buffer to the optical line terminal 1. In the optical line terminal 1, the vacant band and the subscriber units 2a to 2n
, To determine whether to newly allocate a band, and determine a band for the subscriber units 2a to 2n. That is, if there is a free band according to the buffer accumulation information of the subscriber units 2a to 2n, an extra band is allocated to the corresponding subscriber unit, so that the cell due to the buffer overflow in the subscriber units 2a to 2n. Prevent disposal.

Next, the optical line terminal 1 and the subscriber units 2a to 2n
Will be described in detail. First, the optical line terminal 1 will be described. FIG. 2 is a block diagram of the optical line terminal 1. In FIG. 2, reference numeral 21 denotes a DMUX unit. This DMUX unit 21
Is for separating OAM information from cells transmitted from the subscriber units 2a to 2n.

Reference numeral 22 denotes a buffer storage capacity receiving unit. The buffer storage capacity receiving unit 22 receives the OAM information output from the DMUX unit 21 and receives the storage capacity of the buffer of the subscriber device 2 from the OAM information. 23 is a band allocation control unit. This band allocation control unit 23
Controls the bandwidth allocation of the subscriber unit 2 based on the output signal output from the buffer storage capacity receiving unit 22. The bandwidth allocation control unit 23 has a control signal input port, compares the remaining bandwidth with the buffer storage capacity declared from the subscriber units 2a to 2n, and determines whether to allocate a bandwidth. And the subscriber units 2a to 2n
And a band allocation change unit 233 for changing the band for the subscriber unit 2 based on the output signal of the band allocation determination unit 231.

Reference numeral 24 denotes an OAM information generation unit. This OA
The M information generation unit 24 reads the band information of the subscriber units 2a to 2n from the band allocation memory 232 and generates OAM information. 25 is a MUX unit. This MUX unit 25
OAM information from the OAM information generation unit 24 is cell-multiplexed,
It is sent to the subscriber units 2a to 2n.

Next, the subscriber units 2a to 2n will be described. Note that the subscriber units 2a to 2n have the same configuration for all the subscriber units, and therefore only the subscriber unit 2a will be described. FIG. 3 is a block diagram of the subscriber device 2a. In FIG. 3, reference numeral 31 denotes a buffer. This buffer 31 stores cells to be transmitted to the optical line terminal 1.

Reference numeral 32 denotes a buffer monitoring unit. The buffer monitoring unit 32 monitors the storage capacity of the buffer 31 and outputs the storage capacity as buffer storage information. 33 is OA
An M information generation unit. The OAM information generation unit 33 converts the buffer accumulation information output from the buffer monitoring unit 32
Generate AM information. 34 is a DMUX unit. This D
The MUX unit 34 separates the cell transmitted from the optical line terminal 1 into main signal information and OAM information for the local subscriber unit 2a, and separates the main signal information into a subsequent main signal processing unit (shown in FIG. 3). Not). On the other hand, the OAM information is transmitted to a transmission control unit 35 described later.

Reference numeral 35 denotes a transmission control unit. The transmission control unit 35, based on the input OAM information,
The cell transmission is controlled in the band specified by. 36 is M
UX section. The MUX unit 36 cell-multiplexes the main signal information sent from the buffer 31 and the OAM information (including the buffer accumulation information) sent from the OAM information generation unit 33, and according to the control of the transmission control unit 35. The cell is transmitted in the band specified by the optical line terminal 1.

Next, the operation of this embodiment will be described. FIG. 4 is a diagram for explaining this operation, FIG. 5 is a flowchart of the operation of the subscriber unit 2a, and FIG.
It is a flowchart of FIG. In this operation, as shown in FIG. 4, all the bands for the subscriber units 2a to 2n are Q,
When the bandwidth allocated to the subscriber units 2a to 2n is Q1, the vacant bandwidth is Q2, and the bandwidth initially allocated to the subscriber unit 2a is Q3, and an extra band is allocated to the subscriber unit 2a. Will be described.

First, the buffer monitoring unit 32
Is monitored, and the buffer storage capacity of the buffer 31 is calculated from the difference between the read address and the write address of the buffer 31 (Step 500). At this time, it is assumed that the buffer accumulation amount of the buffer 31 corresponds to the band Q4.
Then, the buffer monitoring unit 32 outputs the band Q4 to the OAM information generation unit 33 as buffer accumulation information (Step
501).

The OAM information generating unit 33 generates OAM information from the buffer accumulation information sent from the buffer monitoring unit 32 and other control information (Step 502). Subsequently, in the MUX unit 36, the main signal information sent from the buffer 31 and the OAM information (including the buffer accumulation information) sent from the OAM information generation unit 33 are cell-multiplexed. Band to be controlled (band Q3)
Is transmitted (Step 503).

Next, the optical line terminal 1 starts the operation shown in FIG. First, the DMUX unit 21 separates the received cell into main signal information and OAM information, sends the main signal information to the subsequent main signal processing unit, and sends the OAM information to the buffer storage capacity receiving unit 22 (Step 600). . next,
The buffer storage capacity receiving unit 22 separates the buffer storage information from the OAM information and outputs it to the band allocation control unit 23 (Step 601). The buffer storage information separated at this time is the band Q4.

In the band allocation control unit 23 to which the buffer storage information is input, first, in the band allocation determination unit 231, the free band (band Q2) sent from the band allocation memory 232 and the buffer storage information (band Q4). They are compared (Steps 602 and 603). If the free band (band Q2) is larger than the buffer accumulation information (band Q4), it is determined that the band Q4 is additionally allocated to the band Q3 of the subscriber device 2a (Step 60).
4). If the vacant band (band Q2) is smaller than the buffer accumulation information (band Q4), it is determined that the band Q2 is additionally allocated to the band Q3 of the subscriber device 2a (Step 605).

Then, based on the determination by the bandwidth allocation determining unit 231, the bandwidth allocation changing unit 233
Then, the band Q3 of the subscriber device 2a stored in 2 is changed to (band Q3 + band Q4) or (band Q3 + band Q2) (Step 606). Subsequently, the OAM information generation unit 2
4 reads out the band information of the subscriber unit 2a from the band allocation memory 232 and generates OAM information (Step 60).
7) OUX information is cell-multiplexed and transmitted by the MUX unit 25 (Step 608).

Returning to FIG. 5, the cell transmitted from the optical line terminal 1 is separated into main signal information and OAM information for the local subscriber unit 2a by the DMUX unit 34, and the OAM information is transmitted to the transmission control unit 35. (Step 504). And
The transmission control unit 35 controls cell transmission in the newly set band, that is, (band Q3 + band Q4) or (band Q3 + band Q2) (Step 505).

As described above, the buffer storage capacity of the subscriber unit 2a is reported to the optical line terminal 1, and an extra band is allocated in accordance with an available band, whereby the subscriber unit 2a
Can be prevented from being discarded due to the buffer overflow. Next, another embodiment of the present invention will be described. FIG. 7 is a block diagram of another embodiment.

In this embodiment, as shown in FIG. 7, a threshold setting unit 70 and a comparison unit 71 are provided between the buffer monitoring unit 32 and the OAM information generation unit 33. In the embodiment configured as described above, the buffer accumulation amount output by the buffer monitoring unit 32 is output to the comparison unit 71. The threshold setting unit 70 holds a predetermined threshold of the buffer.

The comparison unit 71 compares the buffer accumulation amount output from the buffer monitoring unit 32 with the threshold value of the threshold value setting unit 70, and only when the buffer accumulation amount exceeds the threshold value, the station unit 1 Notifies the buffer accumulation amount and requests a change of the band. Thereafter, if the buffer storage amount does not exceed the threshold, the buffer storage amount is notified to the optical line terminal 1 as 0, and a request is made to release the newly added bandwidth. . In response to this request, the optical line terminal 1 releases the added bandwidth to make the bandwidth free.

The present embodiment has a new effect of reducing the occupation time of the newly allocated band so that the vacant band can be used effectively by the subscriber unit.

[0029]

According to the present invention, by disclosing the buffer storage capacity of the subscriber unit to the optical line terminal and allocating an extra band according to the available band, it is possible to prevent cell loss due to buffer overflow of the subscriber unit.

[Brief description of the drawings]

FIG. 1 is a block diagram of the present embodiment.

FIG. 2 is a block diagram of an optical line terminal.

FIG. 3 is a block diagram of a subscriber device.

FIG. 4 is a diagram for explaining an operation;

FIG. 5 is an operation flowchart of the subscriber device.

FIG. 6 is an operation flowchart of the optical line terminal.

FIG. 7 is a block diagram of another embodiment.

[Explanation of symbols]

 Reference Signs List 1 station apparatus 2a to 2n subscriber apparatus 3 optical fiber transmission line 4 star coupler 21 DMUX section 22 buffer storage capacity receiving section 23 band allocation control section 24 OAM information generation section 25 MUX section 31 buffer 32 buffer monitoring section 33 OAM information generation Unit 34 DMUX unit 35 transmission control unit 36 MUX unit 70 threshold setting unit 71 comparison unit 231 band allocation determination unit 232 band allocation memory 233 band allocation change unit

Claims (6)

[Claims] 1. A transmission system in which a plurality of subscriber units are star-coupled to an optical line terminal and a communication based on a cell-based time division multiple access system for setting and managing bands of the plurality of subscriber units from the optical line unit is performed. A bandwidth allocation method according to claim 1, wherein the subscriber device declares buffer storage information to the optical line terminal; and wherein the station side device performs the subscription based on the declared buffer storage information and a current free bandwidth. Allocating the bandwidth of the user device. 2. The method of allocating a bandwidth, comprising: when the free bandwidth is larger than the buffer storage amount indicated by the buffer storage information declared by the subscriber device,
When a bandwidth corresponding to the buffer storage amount is added to the current bandwidth and assigned to the subscriber unit, and the available bandwidth is smaller than the buffer storage amount indicated by the buffer storage information declared by the subscriber unit, ,
2. The bandwidth allocation method according to claim 1, wherein a free bandwidth is added to the subscriber device and added to a current bandwidth. 3. A step of declaring buffer storage information, comparing a predetermined threshold value with a buffer storage amount, and declaring the buffer storage amount when the buffer storage amount is larger than the threshold value. If the buffer storage amount is declared to be zero when the buffer storage amount is smaller than the threshold, and in the step of allocating the bandwidth of the subscriber unit, if the buffer storage amount is declared to be zero by the subscriber unit,
The bandwidth allocation method according to claim 1, wherein a bandwidth newly added to the subscriber device is released. 4. A transmission system in which a plurality of subscriber units are star-coupled to an optical line terminal and communication of a cell-based time division multiple access system for setting and managing bands of the plurality of subscriber units from the optical line unit is performed. Wherein each of the subscriber units monitors a buffer storage amount and reports the buffer storage amount to the optical line terminal; and a cell transmitting unit for transmitting cells in a band designated by the optical line unit. The station-side device has a band allocation control unit that determines a band to be newly added to the subscriber device based on the buffer storage amount declared by the subscriber device and the current free band, Notifying means for notifying the subscriber device of the newly allocated bandwidth. 5. The bandwidth allocation control means compares the buffer storage amount declared by the subscriber device with a vacant band, and when the buffer storage amount is larger than the vacant band, the band allocation control means controls the subscriber device. A bandwidth corresponding to the buffer storage amount is additionally allocated to the current bandwidth, and when the free bandwidth is smaller than the buffer storage amount, a free bandwidth is additionally allocated to the subscriber device to the current bandwidth. 5. The transmission system according to claim 4, wherein the transmission system is a means. 6. A subscriber device comprising: a storage unit in which a predetermined threshold value is stored; a comparison unit that compares a buffer storage amount with the threshold value; Means for notifying the station side device of the buffer accumulation amount when the buffer accumulation amount is larger than the threshold, and notifying the station side device of the buffer accumulation amount as zero when the buffer accumulation amount is smaller than the threshold value, 6. The side device according to claim 4, wherein the side device has means for releasing a bandwidth added to the subscriber device when the buffer storage amount is notified from the subscriber device as zero. Transmission system.