KR100903111B1 - Apparatus for bandwidth assignment in TDMA PON OLT systems and method thereof - Google Patents

Abstract

The present invention relates to a band allocation apparatus and method for a Time Division Multiple Access (TDMA) based passive optical network (PON) optical line terminal (OLT) system. OLT) is a device and method for compensating the uplink traffic loss of the ONU in operation during the time to process the registration of the new optical network unit (ONU) by placing a traffic compensation unit in the band allocation device of the system.

Passive Optical Subscriber Network (PON), Gigabit Passive Optical Subscriber Network (GPON), TDMA-PON, Dynamic Bandwidth Allocation (DBA), Class of Service Agreement (SLA), Traffic Compensation

Description

Apparatus for bandwidth assignment in TDMA PON OLT systems and method according to time division multiple access based passive optical subscriber network system

1 is a general schematic diagram of a TDMA based PON network to which the present invention is applied.

2 illustrates a configuration of a band allocation and frame generation apparatus of an OLT system.

3 illustrates an operation example of a band allocation method of an OLT before and after a new ONU registration section.

4 illustrates a configuration of a band allocation and frame generation apparatus of an OLT system including a traffic compensation unit according to the present invention.

5 is a flowchart illustrating an operation of a traffic compensation unit according to the present invention.

The present invention relates to a band allocation apparatus and method of a TDMA PON OLT system, and more particularly, band allocation including a function for selectively compensating some of upstream traffic of ONUs in operation not transmitted by a new ONU registration interval. An apparatus and method are provided.

Passive Optical Network (PON) technology is one of the FTTH (Fiber To The Home) technologies proposed to effectively provide the bandwidth required for the subscriber end, and many ONUs (Optical Network Units) are passive devices (optical It is a point-to-multipoint network structure that shares one optical line terminal (OLT) through a distributor.

ODN (Optical Distribution Network) network is a transport network between OLT and ONU and consists of a tree structure. The FTTH network with PON structure has been standardized by ITU-T and IEEE which are standardization organizations such as ATM-PON (Asynchronous Transfer Mode PON), E-PON (Ethernet PON) and G-PON (Gigabit PON). .

1 shows a general configuration of a TDMA based PON network to which the present invention is applied.

As shown in FIG. 1, a TDMA-based PON has a tree structure in which one OLT 101 corresponds to 1: N through a plurality of ONUs 102, 103, and 104 and passive elements 105.

In the downlink transmission from the OLT 101 to the ONUs 102, 103, and 104, data transmitted from the OLT 101 are broadcasted to all ONUs 102, 103, and 104, thereby causing problems due to media sharing. I never do that.

On the other hand, in the uplink transmission from the ONUs 102, 103, and 104 to the OLT 101, the ONUs are connected from the passive element 105 to the OLT 101 through one optical fiber. In order to perform uplink transmission without collision between (102, 103, 104), a TDMA-based medium access control (MAC) protocol is used that accesses a medium while avoiding duplication in time.

In the TLT-based PON OLT system, when a new ONU is registered in the network during operation, the new ONU is automatically recognized and the new ONU is allocated to handle the registration of the new ONU in order to allocate a band for uplink traffic transmission. Implement the method.

The OLT initiates a new ONU registration process by stopping band allocation to temporarily suspend transmission of upstream traffic from existing ONUs, and allows only new ONUs to transmit registration-related messages to measure the presence of a new ONU and its distance from the OLT. It has a mechanism.

These mechanisms may differ in their processing procedures, message formats, and specific implementation methods for each standardization organization, such as ITU-T or IEEE. However, the existing ONUs may be suspended and only new ONUs may be upgraded. The basic mechanism for sending a registration message is the same.

In the process of registering new ONUs, ONUs that have been operating in the middle of the new ONU registration period stop the uplink transmission and store the data in the queue. Resume.

Accordingly, traffics that must guarantee a constant transmission bandwidth and transmission time interval, such as constant bit rate (CBR) traffic, among upstream data of the ONU, are subject to service class agreement (SLA: The service quality agreed by the Service Level Agreement will not be achieved.

Accordingly, a band allocation device of an OLT system in a TDMA-based PON network requires an apparatus and method for compensating for transmission bandwidth and transmission delay for uplink traffic of an existing ONU occurring during a new ONU registration interval.

The present invention provides an apparatus and method for compensating for transmission bandwidth and transmission delay for uplink traffic of an ONU that is in operation during a new ONU registration interval in a TDMA based PON network.

In particular, by providing an apparatus and a method for selectively compensating traffic transmission for transmission bandwidth and transmission delay sensitive traffic among upstream traffics of the ONU in operation, each ONU has a service class agreement (SLA) regardless of the new ONU registration interval. The aim is to ensure that the quality of service agreed upon is achieved.

One embodiment of a bandwidth allocation device of a TDMA PON OLT system according to the present invention for solving the above technical problem, transmits a bandwidth allocation signal to a plurality of first optical network termination device (ONU), by the bandwidth allocation signal In a TDMA PON OLT system that receives data from the first optical termination device (ONU) by the allocated bandwidth, each of the first optical termination device (ONU) according to the service priority determined by a service class agreement (SLA). An allocation band calculator for calculating a required bandwidth and generating a bandwidth allocation signal including the calculated bandwidth information; An allocation band list for storing the bandwidth allocation signal; An optical network termination device (ONU) registration processing unit configured to generate a registration message bandwidth allocation signal for receiving registration information from at least one second optical network termination device (ONU); A traffic compensator for determining a service priority of the bandwidth allocation signal lost or delayed by the registration message bandwidth allocation signal and replacing it with a bandwidth allocation signal having a low service priority; And a frame generator for generating a frame including a pre-bandwidth allocation signal or the registration message bandwidth allocation signal and downlink data to be transmitted to the first optical network termination device (ONU).

One embodiment of the bandwidth allocation method of the TDMA PON OLT system according to the present invention for solving the above technical problem is, by transmitting a bandwidth allocation signal to a plurality of first optical network termination device (ONU), by the bandwidth allocation signal In a TDMA PON OLT system that receives data from the first optical termination device (ONU) by the allocated bandwidth, (a) the first optical termination device (ONU) according to the service priority determined by a service class agreement (SLA). Calculating bandwidths required for each, and generating a bandwidth allocation signal including the calculated bandwidth information; (b) storing the bandwidth allocation signal; (c) generating a registration message bandwidth allocation signal for receiving registration information from at least one second optical termination device (ONU); (d) determining a service priority of the bandwidth allocation signal lost or delayed by the registration message bandwidth allocation signal, and replacing the bandwidth allocation signal with a low service priority signal; And (e) generating a frame including the bandwidth allocation signal or the registration message bandwidth allocation signal and downlink data to be transmitted to the first optical network termination device (ONU).

 Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 illustrates a configuration of a band allocation and frame generation apparatus of an OLT system.

In FIG. 2, the allocation band calculator 210 calculates an amount of bandwidth to be allocated to the traffic queue of each ONU through a band allocation algorithm for each frame and transmits the amount of the bandwidth to the allocation band list 220.

The allocation band list 220 is implemented as a memory or a buffer and stores allocation amount information received from the allocation band calculator 210.

The allocation information transmitting unit 230 transmits content to be transmitted to the corresponding frame among the allocation amount information to the frame generating unit 240 every frame so that the bandwidth allocation information is displayed on the frame.

The ONU registration processing unit 250 is driven by the CPU of the OLT and stops the upstream traffic of the ONUs that are in operation for the new ONU registration and allocates a band for the new ONU to transmit the new ONU registration message.

Therefore, in the new ONU registration section, the allocation information transmitting unit 230 receives band allocation information from the ONU registration processing unit, not the allocation band list, and transmits the bandwidth allocation information to the frame generation unit.

3 illustrates an operation example of a band allocation method of an OLT before and after a new ONU registration section.

For convenience of explanation, it is assumed that there is only one ONU in operation, the new ONU registration interval is two frames, and half of the frame bandwidth is allocated to CBR (Constant Bit Rate) traffic and the other half is allocated to Best Effort traffic. .

3 (a) shows band allocation per frame according to the above assumption and shows band allocation without a new ONU registration section.

When the OLT processes the new ONU registration for the third and fourth frames, the ONU registration processing unit allocates the bandwidth for transmitting the new ONU registration message during this interval, and the bandwidth allocation information for the ONU that was in operation is stored in memory. A new ONU registration section is written to the allocation band list 220 implemented by the UE, but the allocation information transfer unit 230 receives the bandwidth allocation information from the ONU registration processing unit 250 and does not read the bandwidth allocation information of the allocation band list. It is then overwritten by the newly allocated band allocation information.

In this case, the bandwidth allocation information carried on the frame is shown in FIG. 3 (b), and the bandwidth allocation information to be down during the new ONU registration section is lost, and the constant bit rate (CBR) traffic of the upstream traffic of the ONU in operation is Uplink transmission cannot be performed for 2 frames, which causes a transmission delay for the corresponding time. As this new ONU registration interval is repeated, the uplink transmission bandwidth itself decreases, so that the transmission bandwidth and transmission agreed by the service class agreement (SLA) are reduced. Quality of service such as delays cannot be achieved.

FIG. 3 (c) shows an operation example when the allocation band list is implemented as a buffer of a first-in, first-out (FIFO) type.

In this case, since the bandwidth allocation information for the new ONU registration section is stored in the buffer, after the new ONU registration section, the allocation information that should have been delivered to the corresponding frame is delayed by the new ONU registration section, and then forwarded to the upstream traffic of the ONU that was in operation. Similarly, the transmission delay is as much as the new ONU registration interval.

3 (d) shows an operation example to which the traffic compensation method according to the present invention is applied.

During the new ONU registration period, the ONU registration processor transfers the band allocation for the new ONU registration to the frame generation unit 240 through the allocation information transmission unit 230. During this time, the traffic compensation unit 460 of FIG. Among the band allocation information stored in the list, only the band allocation information for traffic sensitive to transmission band loss is selected and stored separately.

After that, when the band allocation information for subsequent frames is written in the allocation band list after the end of the new ONU registration interval, the band allocation information for the traffic which is not sensitive to the transmission band loss is deleted, and the new ONU registration interval for the corresponding band is deleted. It replaces the bandwidth allocation information for the loss-sensitive traffic that has been stored separately.

As shown in FIG. 3 (d), the band allocation information of the constant bit rate (CBR) 3 and the constant bit rate (CBR) 4 is stored during the new ONU registration period, and then the band allocation information for the subsequent frame after the new ONU registration period is finished. By replacing the bandwidth allocation information of Best Effort 5 and Best Effort 6, the amount of uplink transmission bandwidth of the CBR (Constant Bit Rate) traffic of the uplink traffic of the ONU that is being operated may be compensated.

4 illustrates a configuration of a band allocation and frame generation apparatus of an OLT system to which a traffic compensation unit is added according to the present invention.

In FIG. 4, as described above, the traffic compensator 460 separately stores band allocation information for traffic sensitive to transmission delay and transmission bandwidth loss among the band allocation information transmitted to the allocation band list 420 during the new ONU period. It performs the function of replacing the bandwidth allocation information for traffic that is not sensitive to transmission delay and transmission bandwidth loss among the newly allocated bandwidth allocation information after the new ONU registration interval.

5 shows an operation flow of the traffic compensation unit according to the present invention.

When a new ONU registration interval starts, the transmission bandwidth is sensitive to transmission bandwidth loss and transmission delay, such as constant bit rate (CBR) traffic, among the bandwidth allocation information calculated by the allocation band calculator 410 and transmitted to the allocation band list 420 in the corresponding frame. Band allocation information for traffic is collected and stored separately (S510).

In order to facilitate the traffic screening operation, in the process of transmitting the band allocation information from the allocation band calculation unit 410 to the allocation band list 420, a tag indicating that the traffic to be compensated is added to the band allocation information in advance so that it can be easily distinguished. can do.

The band allocation information of the stored compensation target traffic is converted into length information of a byte unit irrespective of a start position (S520). The band allocation information is composed of a pair of start byte position and allocation band length information indicating a band allocation position or a pair of band allocation start position information and end position information.

This information is converted into only the length information irrespective of the start position, so that the band allocation information for the non-compensated traffic and the replacement of the newly allocated band allocation information after the end of the new ONU registration section are easily facilitated.

When the new ONU registration interval ends (S530), the allocation information for the non-compensated target traffic is searched from the newly allocated allocation band list to the allocated band list 420 (S540), and the total length of the detected non-compensated target traffic is calculated (S540). S550).

The allocation information for the non-compensation target traffic is replaced with the allocation information for the compensation target traffic stored during the new ONU registration interval (S560).

The above operation is performed every frame until the band allocation information for all the collected compensation target traffic is compensated (S580).

So far, the present invention has been described with reference to the preferred embodiment. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, in the current TDMA-based PON system, the transmission bandwidth loss and the transmission delay are derived from the upstream traffic of the ONU which is being operated by the new ONU registration processing interval, and the transmission time interval and the transmission are constant, such as CBR (Constant Bit Rate) traffic. For traffic for which time interval deviations must be guaranteed, it becomes difficult to eventually achieve the quality of service promised by the service class agreement (SLA).

In the present invention, the traffic compensation unit is placed in the OLT so that ONUs that are in operation can select some of the traffic to be compensated among the traffics that have not been transmitted during the interval after the new ONU registration period, and then transmit the traffic compensation unit. Ensure a fixed quality of service.

Claims (11)

A time division multiple access-based passive optical subscriber network for transmitting a bandwidth allocation signal to a plurality of first optical termination devices (ONU) and receiving data from the first optical network termination device (ONU) as much as the bandwidth allocated by the bandwidth allocation signal. In the system, An allocation band calculator configured to calculate a bandwidth required for each of the first optical network termination equipment (ONU) according to a service priority determined by a service class agreement (SLA), and to generate a bandwidth allocation signal including the calculated bandwidth information ; An allocation band list for storing the bandwidth allocation signal; An optical network termination device (ONU) registration processing unit configured to generate a registration message bandwidth allocation signal for receiving registration information from at least one second optical network termination device (ONU); A traffic compensator for determining a service priority of the bandwidth allocation signal lost or delayed by the registration message bandwidth allocation signal and replacing it with a bandwidth allocation signal having a low service priority; And And a frame generator for generating a frame including the bandwidth allocation signal or the registration message bandwidth allocation signal and downlink data to be transmitted to the first optical network termination apparatus (ONU). Bandwidth Allocation Device for Subscriber Network System. The method of claim 1, The allocation band calculator of the time division multiple access based passive optical subscriber network system, characterized in that generated by including an indicator (Tag) indicating that the bandwidth allocation signal to be replaced by the traffic compensation unit based on the service priority Bandwidth Allocation Device. The method of claim 1, And bandwidth allocation signal for continuously transmitting the bandwidth allocation signal or the registration message bandwidth allocation signal to the frame generation unit. delete delete The method of claim 1, The traffic compensating unit stores bandwidth allocation information of the lost or delayed bandwidth allocation signal as band allocation start position information and allocation band length information in bytes. . A time division multiple access-based passive optical subscriber network for transmitting a bandwidth allocation signal to a plurality of first optical termination devices (ONU) and receiving data from the first optical network termination device (ONU) as much as the bandwidth allocated by the bandwidth allocation signal. In the system, (a) calculating a bandwidth required for each of the first optical fiber termination equipment (ONU) according to a service priority determined by a service class agreement (SLA), and generating a bandwidth allocation signal including the calculated bandwidth information; ; (b) storing the bandwidth allocation signal; (c) generating a registration message bandwidth allocation signal for receiving registration information from at least one second optical termination device (ONU); (d) determining a service priority of the bandwidth allocation signal lost or delayed by the registration message bandwidth allocation signal, and replacing the bandwidth allocation signal with a low service priority signal; And (e) generating a frame including the bandwidth allocation signal or the registration message bandwidth allocation signal and downlink data to be transmitted to the first optical network termination device (ONU); Bandwidth Allocation Method for Optical Subscriber Network System. The method of claim 7, wherein In step (a), the time division multiple access-based passive optical subscriber network is generated by including an indicator (Tag) indicating that the bandwidth allocation signal is required to be replaced in the step (d) based on the service priority. How the system allocates bandwidth. delete delete The method of claim 7, wherein In the step (d), the bandwidth allocation information of the lost or delayed bandwidth allocation signal is bandwidth allocation start position information and allocation band length information in units of bytes. .

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