KR100483009B1 - Medium access control method of passive optical network and system thereof - Google Patents

Abstract

The present invention relates to a polling-based media access control system and method for a passive optical subscriber network. a) receiving an advertisement frame, which is a registration request frame from the OLT, transmitting a polling group registration frame to the OLT, and registering the polling frame in a polling table to wait for a frame reception; b) receiving a frame from the OLT and determining the frame type; c) if the determined frame type is a data frame, transmitting a frame to a higher layer and returning to step a) to wait for frame reception; d) if the determined frame type is a control frame, checking whether it is a polling frame; e) if the control frame is a polling frame, checking whether there is a polling group leave request from a higher layer; And f) if there is no request to leave the polling group, transmitting a data frame below a predetermined threshold that can be transmitted during one polling period to the OLT and notifying the end of transmission. According to the present invention, by setting a threshold value of a data frame that can be transmitted in ONT, it is possible to prevent a deterioration in the quality of service due to bandwidth monopoly of a small number of subscribers, and to prevent a channel monopoly by a small number of subscribers in advance. This prevents the long wait time of new polling registrants.

Description

METHOD ACCESS CONTROL METHOD OF PASSIVE OPTICAL NETWORK AND SYSTEM THEREOF

The present invention relates to a method of medium access control (hereinafter referred to as MAC) of a passive optical network (hereinafter referred to as PON), and more particularly to a polling-based MAC method. will be.

Today's Internet traffic continues to grow in proportion to the growing demand for multiple applications that are based on real-time transmission of data. In order to accommodate such increasing traffic, the available capacity of the entire network is continuously increasing in the backbone network area, and the problem of insufficient transmission bandwidth is already being properly resolved. On the other hand, in the subscriber network area, adequate services cannot be provided due to the increase in bandwidth required from the user terminal and the inconsistency of a plurality of technologies and the inconsistency of protocols between the backbone networks capable of providing broadband transmission bandwidth.

Accordingly, the optical subscriber network aims to provide a bandwidth suitable for the characteristics of current subscriber traffic in real time based on a high transmission bandwidth and a low bit error rate (BER), which are characteristics of optical transmission.

Recently, the most actively discussed Ethernet Passive Optical Network (E-PON) technology is based on the Fiber To The Home (FTTH) subscriber network and the Fiber To The Curb (FTTC) subscriber network depending on the location of the network and the type of concentrator equipment. Are distinguished. In these two subscriber networks, since the optical wavelengths of the downlink data transmission and the uplink data transmission are different from each other, a full-duplex type point-to-multipoint structure is used.

Among them, the FTTC type E-PON technology shares the link from the optical line terminator (OLT) to the optical splitter, which is a passive signal splitter, and the subscriber traffic access equipment (Optical) in the optical splitter. Network Units (hereinafter referred to as ONUs) are typical point-to-multipoint structures with individual links.

That is, since all the downlink signals transmitted from the OLT to the ONU are branched from the optical splitter and transmitted to the entire ONU, it has a network structure suitable for broadcast traffic service, and the network can be configured in various forms from the ONU to each subscriber terminal.

However, in the uplink traffic service, since contention occurs in the shared link between the OLT and the optical splitter region, a multiplexing scheme based on a time division multiple access scheme is used to solve this problem. This multiplexing scheme is applied between the ONU and the OLT where a large number of subscriber traffics are primarily focused, thus ensuring an appropriate level of efficiency.

On the other hand, the FTTH type E-PON technology allocates enough bandwidth to provide services by connecting the optical link to the end terminal, and the downlink transmission in the FTTH network is the same as the FTTC network. It consists of (Optical Network Termination) and is processed based on the destination address.

However, the FTTH network has limitations in uplink transmission control because the installation location and traffic capacity are different from those of the FTTC network. That is, since the distance between ONT and OLT is relatively shorter and higher speed than FTTC network, propagation delay time has little effect. In addition, unlike the ONU of the FTTC network, the ONT of the FTTH network is a user terminal that does not aggregate subscriber traffic, so the generation of Internet traffic in the ONT is not a continuous form based on the user's use of the Internet. Seems.

Therefore, the FTTH network is suitable for traffic patterns where there is always a certain amount of traffic through traffic aggregation, and the network synchronization is basically required to prevent transmission collisions. Therefore, the time division multiplexing method that requires congestion and high system cost is required. The application of is not suitable. In addition, since there is a long distance common line between a plurality of transmission start points and common destinations, transmission control must be performed through an appropriate media access control function to reduce the probability of collision and reception collision of traffic.

In addition, the current subscriber network is significantly short of the subscriber network bandwidth considering various application services such as remote video conferencing, HDTV-class video providing service, remote education and remote computing, which are proposed based on future high-speed Internet service. Since quality is limited over distance, it is difficult to provide high-bandwidth, high-quality services sufficient for such service needs.

Therefore, the present invention is to solve the problems of the prior art, and to apply the conventional polling-based access control scheme to the FTTH network in the uplink traffic transmission of passive optical subscriber network, the threshold for fairness and performance stabilization of bandwidth allocation It is an object of the present invention to provide a method and a system for controlling a medium access that limits a transmittable area during one polling period.

In addition, by constructing and maintaining a polling table based on the total number of terminals requiring actual transmission bandwidth, the uplink transmission efficiency is increased through band allocation based on the actual subscriber, and the polling table of new terminals is performed every polling period. It is an object of the present invention to provide a method and system for controlling access to a medium that enables dynamic subscriber management by providing an initial registration procedure for allowing registration.

In accordance with an aspect of the present invention, a media access control method for a passive optical subscriber network according to a feature of the present invention applies a polling scheme in a passive optical subscriber network to transmit data from an end subscriber (ONT) to an optical termination device (OLT). As a medium access control method for transmitting a message,

a) receiving an Advertisement Frame, which is a registration request frame from the OLT, transmitting a Polling Group Registration Frame to the OLT and registering the Polling Group in a polling table to wait for a frame reception; b) receiving a frame from the OLT and determining the frame type; c) if the determined frame type is a data frame, transmitting a frame to a higher layer and returning to step a) to wait for frame reception; d) if the determined frame type is a control frame, checking whether it is a polling frame; e) if the control frame is a polling frame, checking whether there is a polling group leave request from a higher layer; And f) if there is no request to leave the polling group, transmitting a data frame below a predetermined threshold that can be transmitted during one polling period to the OLT and notifying the end of transmission.

In this case, step b) compares the destination address of the frame received from the OLT with the destination address of the ONT, and discards the frame if the destination address is different as a result of the comparison.

As a result of the checking in step e), if there is a request to leave the polling group, the polling group leaving frame is transmitted and all processes are terminated.

In addition, a frame generated in the upper layer and Ethernet framed and received for transmission to the OLT is stored in a transmission buffer in case of receiving a poll later.

In addition, the threshold is set by the OLT monitors the channel occupancy period and the entire polling period of each ONT during each polling period to determine the input traffic situation to set a new value for polling of the next period, and the threshold is set to the advertisement frame information field Writes to notify the entire ONT, and receives the advertisement frame at each ONT to reset the threshold.

In addition, the polling process in the OLT,

i) checking whether there is a withdrawal and newly subscribed ONT in the polling table, and applying the withdrawal and newly subscribed ONT to configure a new polling table and start a polling cycle; ii) checking the frame type if a frame is received; iii) processing the data frame through a bridge operation if the received frame is a data frame; iv) confirming a type of the control frame if the received frame is a control frame; v) changing the table information of the ONT requesting the withdrawal to the end if the polling group withdrawal frame is determined as a result of step iv); vi) checking whether the entire polling period of the corresponding ONT is completed if the transmission end frame (EOT Frame) is confirmed as the result of step iv); vii) if the entire polling period is completed as a result of the check, transmitting an advertisement frame advertising an initial access frame for a newly connected ONT, registering in the polling table, and returning to step a); And viii) if the check has not completed the entire polling period, polling the next sequence of ONTs and returning to step ii).

At this time, the polling table includes a withdrawal / new field indicating the withdrawal and newly subscribed ONT information, and in step vii), the newly connected ONT information is registered in the withdrawal / new filter.

The transmission end frame, the polling group leaving frame, the polling group joining frame, the polling frame, and the advertisement frame may include a destination address field indicating a destination and source information, a source address field, a type field indicating information distinguishing a control frame and a data frame. And an action code field indicating information for identifying an action of each frame.

The destination address field and the source address field of the transmission end frame, the polling group leaving frame, and the polling group joining frame include OLT address and ONT address information, respectively, and the destination address field and the source address field of the polling frame and the advertisement frame, respectively. Each contains ONT address and OLT address information.

Also, in the operation code field, transmission termination information when the operation code value is OP_code = 0x0001, polling group withdrawal information when OP_code = 0x0002, polling group subscription information when OP_code = 0x0003, polling information when OP_code = 0x0004, and OP_code = 0x0005 indicates advertisement information for requesting to join a polling group.

In addition, the media access control system of a passive optical subscriber network according to a feature of the present invention applies a polling scheme in a passive optical subscriber network to process data transmitted between an end subscriber (ONT) and the optical terminator (OLT) As a media access control system,

When the ONT transmits a data frame to the OLT, the ONT transmits a data frame having a length smaller than a predetermined threshold that the ONT can transmit during one polling period, and the polling group join / leave request from the OLT and higher layers is A polling group join and leave request frame is sent to the OLT, and the OLT applies a polling group join and leave request frame received from the ONT to start a new poll to the actual service requesting subscriber at the beginning of every polling cycle. Configure the table.

At this time, the OLT monitors the channel occupancy period and the entire polling period of each ONT during every polling period to grasp the input traffic, sets a threshold of a new data frame required for polling of the next period, and sets the threshold in the advertisement frame information field. Fill in to notify the entire ONT, and each ONT receives the advertisement frame to reset the threshold.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings the most preferred embodiment that can be easily carried out by those of ordinary skill in the art as follows.

In general, an important factor in determining performance in the uplink traffic transmission of an optical subscriber network is that each subscriber terminal should be able to actually start upstream after a periodic buffer wait time and each end point in a situation where sharing efficiency of the uplink channel is maximized. The allocation band and frequency between terminals must be fair. This is similar to the conventional CSMA / CD (Carrier Sence Multiple Access with Collision Detection) Ethernet media access control technology that seeks fairness of transmission opportunities while preventing collisions through repeated retransmission latency.

Accordingly, the media access control method according to the present invention attempts to control access through polling between terminals. In other words, the OLT module, which is a central control node, asks each terminal whether it needs to transmit sequentially, and only the terminal that has been granted dual transmission transmits the bandwidth to the node without any possibility of data collision that may occur during transmission. The polling interval determines the efficiency of the channel.

This results in a very high communication integrity between the ONT and the OLT as the optical link enters the end subscriber station, and greatly reduces the propagation delay due to the reduction in the physical transmission distance, which inevitably reduces the channel efficiency caused by transmission interruption during the polling period. It is due to the lowering effect.

However, subscriber Ethernet traffic has different service requirements and frame sizes in proportion to the various types of higher application. Therefore, continuous transmission over the average in the event that one terminal gains a transmission opportunity as a result of polling results in an increase in the total length of the waiting frames of the other terminals, and it is unclear whether real-time traffic processing is guaranteed or not. It is a degrading factor.

Therefore, the FTTH network, which is the first subscriber access network, should seek the fairness of bandwidth allocation while stabilizing the real-time traffic service by limiting the transmission capacity by setting an appropriate transmission maximum for fair bandwidth allocation.

The FTTH network is composed of a plurality of subscriber terminals and OLT modules for controlling their uplink transmission. In the downlink traffic transmission, all traffic transmitted from the OLT is transmitted to all subscribers through the optical splitter. At this time, the distance from the optical splitter to the terminal is estimated to be around 500M.

In addition, in the uplink traffic processing, a subscriber terminal means a subscriber station generating a plurality of Ethernet traffics, and a plurality of OLT modules form one OLT system. Therefore, in the FTTH network, the OLT module exists in proportion to the total number of subscriber terminals, and the number and network structure of the OLT system are determined in proportion to the total traffic capacity.

FIG. 1 shows the overall configuration of a general passive optical subscriber network. FIGS. 1A and 1B show an FTTC network and an FTTH network, respectively.

As shown in FIGS. 1A and 1B, an optical splitter 200 exists between an OLT 100 that is an upper node, an ONU 300 that is a lower node, and an ONT 400 for both the FTTC network and the FTTH network. The light splitter 200 is commonly transmitted to the lower nodes 300 and 400.

Meanwhile, in the case of the FTTC network, as shown in FIG. 1A, the common link part is about 15 to 20 km long, whereas the common link part of the FTTH network is composed of short distances of less than 1 km as shown in FIG. 1B. The propagation delay is relatively very low. In addition, there is a transmission / reception module for a corresponding wavelength for full-duplex communication in the ONU 300 and the ONT 400, which are lower nodes of each network, and the up / down transmission is logically independent.

On the other hand, Figure 2 shows the structure of the ONT node of the FTTH network to which the present invention is applied.

As shown in FIG. 2, each ONT 400 has a variable length polling period, during which time it receives a plurality of Ethernet data frames 410 from a higher application and stores them in its transmit buffer 420. If a polling frame is received after one period, the uplink data frame is transmitted to the OLT 100 according to its buffer 420. At this time, the length of the uplink data frame does not exceed a predetermined threshold T _h , which is caused by an increase in the waiting time of another ONT 400 due to a channel monopoly of some ONT 400 and a change in polling period accordingly. This is to prevent the deterioration of service quality.

On the other hand, Figures 3a to 3c shows the structure of a frame according to an embodiment of the present invention.

As shown in FIG. 3A, a data frame is configured in the same manner as a general Ethernet frame. The destination address 411 and the source address 412 are the addresses of the ONT 400 and the OLT 100, respectively, according to the upstream and downstream traffic. The type field 413 is a field for distinguishing a control frame from a data frame in the MAC layer of each device. In the case of an Ethernet frame, the type field 413 has a value of Ox0800. In addition, the data packet 414 has a variable length as information transmitted from a higher layer.

On the other hand, the control frame is divided into two types: a frame generated in the ONT 400 and transmitted to the OLT 100 and a frame transmitted in the OLT 100 and received by the ONT 400. Among these, the frame generated by the ONT 400 and delivered to the OLT 100 may include a transmission end frame (EOT frame), a polling group withdrawal frame, and a polling group subscription frame as shown in FIG. 3B. ).

A transmission end frame (EOT Frame) that functions as transmission termination and simple channel release indicates that the type field value is a control frame with TYPE = Ox8808, and indicates that the transmission end frame is OP_code = EOT. The polling group leaving frame (Succession Frame) frame informs the OLT node 100 of the end of its communication with OP_code = Succession. In addition, a subscriber who wishes to start a new communication and register in the polling table receives an Advertisement Frame at an initial registration time performed after every polling period, and then registers an initial polling group registration frame in which OP_code = Registration. Frame) to register in the polling table. At this time, OP_code of the initial polling group join frame is defined as a binary number as below.

OP_code = Ox0001 = EOT

OP_code = Ox0002 = Succession

OP_code = Ox0003 = Registration

OP_code = Ox0004 = Polling

OP_code = Ox0005 = Registration Request

Meanwhile, as illustrated in FIG. 3C, frames transmitted from the OLT and received from each ONT include a polling frame and an initial registration request frame. Among these, the polling frame is a medium control acceptance frame transmitted using ONT 400 registered as a destination address sequentially based on the information in the polling table. OP_code of the polling frame is Polling, and ONT 400 of the same destination address only receives the polling frame and starts transmission. In addition, the initial subscription request frame is an advertisement frame that is sent to all ONT 400 for new polling subscriber registration after the end of every polling cycle, and the destination address is all set to 1, and OP_code is set to Registration Request to Induce appropriate response actions of the ONT 400 to meet the purpose.

The difference between the polling-based FTTH network and the FTTC network is that the maximum efficiency is achieved by attempting bandwidth allocation to the next ONT 400 before the actual transmission cycle of one ONT 400 is terminated through ranging or the like. The complex algorithm for does not apply. Because the lowest subscriber terminal has a relatively low traffic generation frequency and a variable transmission capacity below the threshold compared to the polling period, using the variable bandwidth can cause confusion of the receiving OLT side and reduce the congestion of the system operation. It can be weighted.

On the other hand, Figure 4 shows a flow diagram of the transmission, resubscription and withdrawal process of the ONT node according to an embodiment of the present invention.

As shown in FIG. 4, when it is necessary to start uplink transmission, each ONT 400 waits for reception of a registration request frame (S401), and when receiving the frame, transmits a polling group subscription frame to the OLT 100. Register itself to the polling table (S402). After that, the frame is received from the OLT 100 in the same manner as in the general MAC, and the destination address is compared and discarded if it is not the same (S403 to 405). This occurs because the E-PON structurally sends every frame to every ONT 400.

On the other hand, if their MAC address and the destination address is the same, this means that the frame is transmitted to it, so the type of the frame is examined for proper frame processing (S406). As a result of the investigation, if the received frame is an Ethernet data frame, the packet is transmitted to a higher layer (S407), and the state is switched to the frame reception standby state (S403).

On the other hand, in the same manner as the general protocol, the frame generated in the upper layer is Ethernet framed and received for transmission to the OLT 100 is stored in the transmission buffer in preparation for transmission in the case of receiving a later poll (S412 ~ 413). At this time, since the E-PON node uses a full-duplex communication method, this process is performed independently of the frame receiving process.

On the other hand, if the received frame is a control frame, it is checked whether the corresponding frame is a polling frame (S408). As a result of the check, if the polling frame is not, the frame is transmitted by packetization for processing in the upper layer (S407). If the polling frame indicates that the upper transmission access is accepted, the frame is transmitted.

At this time, in order to comply with the general ONT function, it is first checked whether a polling group withdrawal request is requested from an upper layer before transmitting a frame (S409). This is done by general monitoring functions. As a result of the check, if there is no withdrawal request, the maximum data frame is transmitted to the OLT 100 from its own transmission buffer below the threshold (S410), and when the transmission is completed, the OLT 100 transfers the channel access right to the next ONT 400. Informs the end of transmission (EOT) at step S411. At this time, if there is no frame accumulated up to the time of receiving the polling frame, the access right is released by transmitting the EOT immediately, thereby increasing the efficiency of the uplink channel. In addition, when the subscriber requests to leave the polling group, the subscriber transmits the polling group leave frame and terminates all processes.

Meanwhile, FIG. 5 illustrates a structure of a FTTH network including a plurality of ONTs 400 and OLTs 100 and a polling table configuration method according to an embodiment of the present invention. The transmission process is described through three cycles up to the +1) th cycle.

As mentioned above, the polling period is configured based on information on the ONT 400 that has requested a registration, and polling is sequentially performed. First, the OLT 100 polls all registered ONTs and then performs an advertisement broadcasting a registration request frame for the new subscriber ONT 3. The OLT 100 configures a polling table of the next period based on the polling group subscription frame information received after elapse of time considering the transmission delay and processing time and resumes polling.

Meanwhile, as shown in the polling table configuration of the (M + 1) th period, when the polling group leave request frame is received in the subsequent polling process, the corresponding ONT (ONT 2, ONT N-1) is deleted from the polling table configuration of the next period. do.

Through this process, the OLT 100 configures a dynamic polling table and allocates bandwidth only to ONT that actually requires an uplink bandwidth in every polling cycle, thereby increasing efficiency of an uplink channel. In addition, it is possible to reduce the waste of the bandwidth and actively respond to the dynamic change of the number of ONT requesting the actual service, and the function of the OLT module can be simplified by setting a threshold in the transmission bandwidth of the ONT.

6 is a flowchart illustrating a polling process and a frame processing procedure of an OLT according to an embodiment of the present invention.

As shown in FIG. 6, after the polling of each cycle is finished, the OLT first checks the information change of the polling table, configures a new polling table with the withdrawal and newly subscribed ONT, and starts a new polling (S601 ˜ 603). In practice, there is little time lag in this step because it constantly monitors changes to table information during polling of the previous cycle.

After receiving the frame to check the frame type, when receiving the data frame is processed through the bridge operation (S604 ~ 605). After the reception of the data frame or when there is no frame to be transmitted by the ONT, if the control frame is transmitted immediately after polling, the type of the control frame is checked (S606). As a result of the check, when the polling group withdrawal frame (Succession) is received, the information of the corresponding ONT table is changed to the end so that the OLT can delete the corresponding ONT in the next polling period, and then the polling procedure is continued (S607).

On the other hand, when the transmission end frame (EOT) is received, this means that the end of the uplink transmission of the ONT that is currently polled, so ONT checks whether the entire polling period has been completed (S608), and the polling procedure of the current period is completed. If not, the next sequence of ONT is polled to give media access control (S609). If the polling period is completed, the mobile station moves to an advertisement step of broadcasting an initial access frame for newly connected ONTs (S610). The information received in the advertising step is recorded in the polling table in real time, and when the advertising step ends, it returns to the table checking step (S601). The subsequent procedure is the same as the polling cycle procedure mentioned above.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the appended claims or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the threshold-based polling medium access control method of the present invention sets a threshold to prevent deterioration of service quality due to bandwidth monopoly of a small number of subscribers, and prevents channel monopoly by a small number of subscribers in advance to maximize polling of existing subscribers. The period is predictable and prevents long polling of new polling registrants.

In addition, the media access control method of the present invention can solve the problems of congestion and network synchronization requirements that may occur when the time-channel multiplexing method is applied by simplifying the uplink access method. It is possible.

In addition, since the polling procedure is started by re-confirming the actual service requesting subscriber at the end of every polling cycle, it is possible to prevent bandwidth waste through unnecessary polling and to actively respond to changes in end subscribers. This is appropriate when considering the fact that the upstream traffic pattern of the ONT, which is the final subscriber, changes in real time according to the type of the upper application and the user in the FTTH network, whereas a certain amount of subscriber traffic is concentrated in the ONU of the FTTC network. That's the way.

In addition, the flexibility of the network configuration is ensured according to the present invention. This is necessary when considering that the FTTH network is the first network access network of service subscribers, and in the present invention, ONT can be newly registered as a response procedure by the initial registration request of the OLT, and the congestion of the protocol is increased by such a procedure. none.

In addition, the present invention can simplify the function of the subscriber modem by concentrating control functions on the OLT. All control functions such as overall uplink bandwidth allocation procedure and registration procedure are performed by OLT, and by performing control function corresponding to frame in ONT by control frame, there is less burden on hardware side of ONT and interworking with existing commercial protocol. This is relatively easy.

1A to 1B are types and configuration diagrams of a passive optical subscriber network.

2 is a block diagram of a buffer of an optical subscriber terminal to be applied to the present invention.

3A to 3C are configuration diagrams of a transmission frame according to an embodiment of the present invention.

4 is a flow diagram of a band allocation procedure between an optical terminator (OLT) and an end subscriber terminal (ONT) in accordance with an embodiment of the present invention.

5 is a configuration diagram of a polling table according to an embodiment of the present invention.

6 is a flowchart illustrating a polling process and a frame processing procedure of an OLT according to an embodiment of the present invention.

*** Description of the symbols for the main parts of the drawings ***

100: optical termination device (OLT)

200: light splitter

300: subscriber traffic access unit (ONU)

400: end subscriber terminal (ONT)

Claims (12)

A medium access control method for transmitting data from an end subscriber (ONT) to an optical end device (OLT) by applying a polling scheme in a passive optical subscriber network, a) receiving an Advertisement Frame, which is a registration request frame from the OLT, transmitting a Polling Group Registration Frame to the OLT and registering the Polling Group in a polling table to wait for a frame reception; b) receiving a frame from the OLT and determining the frame type; c) if the determined frame type is a data frame, transmitting a frame to a higher layer and returning to step a) to wait for frame reception; d) if the determined frame type is a control frame, checking whether it is a polling frame; e) if the control frame is a polling frame, checking whether there is a polling group leave request from a higher layer; And f) if there is no request to leave the polling group, transmitting a data frame below a predetermined threshold that can be transmitted during one polling period to the OLT and notifying the end of transmission; Medium access control method of a passive optical subscriber network comprising a. The method of claim 1, B), And comparing the destination address of the frame received from the OLT with the destination address of the ONT, and discarding the frame if the destination address is different as a result of the comparison. The method of claim 1, In step e), And transmitting a polling group exit frame and ending all processes when there is a polling group exit request. The method of claim 1, And a frame generated in the upper layer and Ethernet framed and received for transmission to the OLT is stored in a transmission buffer in case of receiving a later poll. The method of claim 1, The threshold is set by the OLT to monitor the channel occupancy period and the entire polling period of each ONT during each polling period to determine the input traffic situation to set a new value for polling the next period, The threshold value is entered in the advertisement frame information field to inform the entire ONT, And receiving the advertisement frame at each ONT and resetting the threshold. The method of claim 1, The polling process in the OLT, i) checking whether there is a withdrawal and newly subscribed ONT in the polling table, and applying the withdrawal and newly subscribed ONT to configure a new polling table and start a polling cycle; ii) checking the frame type if a frame is received; iii) processing the data frame through a bridge operation if the received frame is a data frame; iv) confirming a type of the control frame if the received frame is a control frame; v) changing the table information of the ONT requesting the withdrawal to the end if the polling group withdrawal frame is determined as a result of step iv); vi) checking whether the entire polling period of the corresponding ONT is completed if the transmission end frame (EOT Frame) is confirmed as the result of step iv); vii) if the entire polling period is completed as a result of the checking, transmitting an advertisement frame advertising an initial access frame for newly accessed ONT, registering in the polling table, and returning to step a); And viii) if the check has not completed the entire polling cycle, polling the next sequence of ONTs and returning to step ii) Medium access control method of a passive optical subscriber network comprising a. The method of claim 6, The polling table includes a withdrawal / new field indicating the withdrawal and newly subscribed ONT information, And in step vii), the newly accessed ONT information is registered in the withdrawal / new filter. The method of claim 6, The transmission end frame, the polling group leaving frame, the polling group joining frame, the polling frame, and the advertisement frame may include a destination address field indicating a destination and source information, a source address field, a type field indicating information distinguishing a control frame and a data frame, and each. A method for controlling access to a medium of a passive optical subscriber network including an action code field indicating information for identifying a motion of a frame. The method of claim 8, The destination address field and the source address field of the transmission end frame, polling group leaving frame, and polling group joining frame respectively include OLT address and ONT address information. And a destination address field and a source address field of the polling frame and the advertisement frame, respectively, and include ONT address and OLT address information. The method of claim 8, The action code field includes transmission termination information, polling group exit information, polling group subscription information, polling information, and advertisement information requesting to join a polling group, and the passive optical subscription for which the information is determined according to the value of the action code field. Method of controlling medium access of own network. A media access control system for processing data transmitted between an end subscriber (ONT) and an optical end device (OLT) by applying a polling scheme in a passive optical subscriber network, When the ONT transmits a data frame to the OLT, the ONT transmits a data frame having a length smaller than a predetermined threshold that the ONT can transmit during one polling period, and the polling group join / leave request from the OLT and higher layers is Send a polling group join and leave request frame to the OLT. The OLT applies a polling group join and leave request frame received from the ONT to configure a new polling table with actual service request subscribers at the beginning of every polling cycle. Medium Access Control System of Passive Optical Subscriber Network. The method of claim 11, The OLT monitors the channel occupancy period and the entire polling period of each ONT during each polling period to determine the input traffic situation and sets the threshold of new data frames needed for the next polling period. The threshold value is entered in the advertisement frame information field to inform the entire ONT, Wherein each ONT receives the advertisement frame and resets the threshold.