JP5487139B2 - Bandwidth allocation method and passive optical communication network system - Google Patents

Description

  The present invention relates to a bandwidth allocation method for dynamically allocating communication time (bandwidth) for uplink communication in a passive optical communication network and a passive optical communication network system implementing the same.

  A PON (Passive Optical Network) is an OLT (Optical Line Terminal) installed in a communication carrier station, and an ONU (Optical Network Unit) installed in a user's home. FTTH (Fiber To The Home). The PON is an optical network in which an OLT and a plurality of ONUs are connected via an optical transmission line such as an optical fiber or a passive optical splitter, and is widely used due to its economic superiority.

  Among EPON (Ethernet (registered trademark) PON) in which OLT and ONU communicate using Ethernet (registered trademark) frames, GE-PON (Gigabit Ethernet (registered trademark) PON) having a transmission rate of 1 Gbps is high-speed, Since an inexpensive FTTH service can be provided, it is widely used especially in Japan. Recently, a standard specification of 10G-EPON having a transmission rate increased to 10 Gbps has been studied. In the standard specification of 10G-EPON, as shown in FIG. 1, it is considered that ONUs having different transmission rates of 10 Gbps and 1 Gbps are mixedly connected to the OLT.

  In general, in PON, the direction of communication from the OLT to the ONU is referred to as the downstream direction, and the opposite direction is referred to as the upstream direction. In many PONs including GE-PON, uplink communication is performed by time division multiple access. By controlling the transmission timing of each ONU by the OLT, a plurality of ONUs can perform time division communication with the OLT.

  Similarly, 10G-EPON uplink communication is performed by time division multiple access. In 10G-EPON, a method in which a plurality of ONUs having different uplink transmission rates can be connected to one OLT is being studied. At this time, uplink communication is realized by time division multiple access even between ONUs of different speeds.

  In many PONs in which upstream communication is performed by time division multiple access, in order to use the upstream bandwidth efficiently, the length of time for which upstream communication is permitted for each ONU depends on the communication status. Dynamic bandwidth allocation by changing dynamically is important. Here, the bandwidth is allocated by calculating a transmission permission amount for each ONU and exclusively securing the transmission time zone.

  EPON defines a protocol called MPCP (Multi Point-Control Protocol) for controlling the transmission timing of a plurality of ONUs. The OLT performs dynamic bandwidth allocation using MPCP.

  The ONU transmits a transmission request signal (REPORT) for notifying the OLT of the uplink transmission request amount to the OLT. FIG. 2 (REPORT format) shows the format of REPORT defined in IEEE802.3ah and IEEE802.3av. REPORT has a plurality of Queue Sets (hereinafter referred to as QS) in one frame, and can notify a plurality of transmission request amounts to the OLT. In one Queue Set, an accumulation amount (Queue Report: hereinafter referred to as QR) for each of a plurality of priority queues can be further described. The ONU calculates a transmission request amount (QS and QR) based on the uplink buffer accumulation amount.

  The OLT receives the REPORT, refers to the transmission request amount described therein, calculates the amount of transmission permitted for each ONU and the transmission start time, and describes these in the transmission permission signal (GATE). Send to ONU. At that time, control is performed so that the transmission signals of the respective ONUs do not overlap in time. The ONU starts transmission from the designated transmission start time according to the received GATE, and transmits the signal accumulated in the uplink buffer for the designated transmission permission amount.

  The method of dynamic bandwidth allocation is important in determining the performance of the PON system. The performance of the PON system can be evaluated using bandwidth utilization efficiency, delay time, and the like as indexes. In dynamic bandwidth allocation, it is important to transmit data with low delay while maintaining high bandwidth utilization efficiency.

  In the PON system, it can be said that the higher the upstream bandwidth utilization efficiency, the higher the performance.

  In order to realize high bandwidth utilization efficiency, it is assumed that the ONU transmits the uplink data frame stored in the uplink buffer according to the uplink transmission priority in the transmission permission amount allocated from the OLT. , ONU and OLT must be matched.

  Here, a plurality of methods will be described for the uplink transmission priority when the ONU transmits an uplink data frame. First, there are two types of methods in which the ONU preferentially transmits a frame for which the buffer accumulation amount has been notified by REPORT in the previous cycle, or transmits it with full priority at a specified transmission timing. The former is given priority for the REPORTed frame, and the latter is given no priority for the REPORTed frame. The priority of the REPORTed frame will be described with reference to FIG. As an example, here, the ONU has four priority queues Q3 to Q0 (31 to 34) indicate upstream buffers for each priority of the ONU. Q3 (31), Q2 (32), Q1 (33), and Q0 (34) are set in descending order of priority. Assume that the ONU notifies the OLT of the accumulated amount (314) of each queue by REPORT at time T1 (35). In response to this, the OLT permits transmission by GATE. The ONU receives GATE at time T2 (36). The transmission start time specified by the OLT is T4 (38), but it is assumed that the frame (315) with the highest priority is received in the ONU upstream buffer at T3 (37) before time T4 (38). Then, at time T4 (38), if the priority is given to the REPORTed frame, the priority is given to the REPORTed frame regardless of the state in the buffer at the time of transmission, as in 311. In this case, as shown in 312, complete priority is given within the given transmission permission time.

  In addition, when there is a priority for a REPORTed frame, there are two types of upstream transmission priorities as the upstream transmission priority of the buffer accumulation amount requested by the QR included in the PORT that has been REPORTed. Within the QS, it is transmitted in the order of high priority to low priority and proceeds to the next QS, or is transmitted in order of two types of uplink transmission priorities, ie, the QS is transmitted across the QS in order from the high priority QR to the low priority QR. is there. This is the priority for each QS. The former is prioritized for each QS, and the latter is not prioritized for each QS. These will be described using an example in which two QSs and two QRs are provided. QS1 and QS2 include QR0 and QR1, respectively. It is assumed that QR1 has a higher priority. At this time, the transmission priority in the case of priority for each QS is the order of QR1 in QS1, QR0 in QS1, QR1 in QS2, QR0 in QS2, whereas the transmission priority in the case of no priority for each QS is The order is QR1 of QS1, QR1 of QS2, QR0 of QS1, and QR0 of QS2.

  The ONU upstream transmission priority order can be classified into three types according to the combination of the above-mentioned priority of the REPORTed frame and the priority for each QS.

  As a method of dynamic bandwidth allocation, the ONU notifies the OLT of the buffer accumulation amount or the frame accumulation amount equal to or less than the threshold by the REPORT as the transmission request amount, and the OLT matches the transmission request amount notified by the ONU by the REPORT. There is a method for notifying the permitted transmission amount by GATE.

  In Non-Patent Document 1, each ONU notifies a transmission request amount to the OLT, and the OLT permits transmission of an amount that matches the notified transmission request amount, thereby eliminating the excess bandwidth and improving the bandwidth utilization efficiency. Is disclosed.

Interleaved polling with adaptive cycle time (IPACT): A dynamic bandwidth distribution in an optical access network, N. p.

However, the conventional method described above has the following two problems.

  Non-Patent Document 1 does not have a step of determining or notifying ONU uplink transmission priority, and the OLT performs dynamic bandwidth allocation after determining it in advance, so that the OLT and ONU However, if the ONU upstream transmission priority is interpreted differently, the bandwidth utilization efficiency may decrease. That is, as the problem 1, when the ONU uplink transmission priority is different between the ONU and the OLT, the correspondence relationship between the transmission request composed of a plurality of request amounts and the transmission permission amount necessary for transmission without waste is as follows: Since there is a difference between the OLT and the ONU, the transmission permission amount permitted by the OLT and the transmission amount of the ONU cannot be made to coincide with each other, and the band use efficiency is lowered.

  Further, in the cited document 1, when the upstream transmission priority of the ONU is no priority for the REPORTed frame, the OLT correctly interprets the upstream transmission priority of the ONU and sets the transmission permission amount so that there is no waste. Even if notified, the delay time of low-priority traffic increases depending on the traffic conditions. The traffic condition here indicates a condition in which high priority traffic always flows. In other words, as an issue 2, when the ONU has an upstream transmission priority of no priority for a REPORTed frame, the transmission permission amount is notified to the ONU so that the OLT accurately interprets the upstream transmission priority of the ONU so that there is no waste. Even so, the delay time of low-priority traffic increases depending on the traffic conditions.

  Therefore, in order to solve the above-described problems, the present invention provides a bandwidth allocation method that maintains high bandwidth utilization efficiency and realizes low delay when dynamically assigning an upstream bandwidth of a PON, and a passive light that implements the bandwidth allocation method. An object is to provide a communication network system.

  In order to achieve the above object, according to the bandwidth allocation method of the present invention, when the priority order for transmitting data stored in the upstream buffer of the ONU is different between the OLT and the ONU, The priority order to be interpreted by the ONU is determined, and the bandwidth is allocated based on the result.

Specifically, the bandwidth allocation method according to the present invention includes a passive optical communication network in which an optical terminal device and a plurality of optical subscriber devices are connected via an optical transmission line, from each of the optical subscriber devices. A bandwidth allocation method for dynamically allocating a communication band to the optical terminal device, wherein uplink data information relating to transmission priority of uplink data for each optical subscriber device is held and received from the optical subscriber device When calculating the transmission permission amount permitted to the optical subscriber unit based on the transmission request amount indicated by the transmission request message and the uplink data information, the transmission request amount for each optical subscriber unit, and the optical subscriber unit An identification procedure for identifying whether the uplink data information is confirmed or unconfirmed based on the past permitted transmission amount and the communication data amount transmitted by the optical subscriber unit and received by the optical terminal device and features to make a That.

  In this bandwidth allocation method, the OLT holds uplink data information, and calculates a transmission permission amount allowed for each ONU from the transmission request amount from the ONU and the uplink data information. The ONU transmits uplink data based on this transmission permission amount. Therefore, the present invention provides a bandwidth allocation method that maintains high bandwidth utilization efficiency and realizes low delay when dynamically assigning an upstream bandwidth of a PON, and a passive optical communication network system that implements the bandwidth allocation method. it can.

  Here, the bandwidth allocation method according to the present invention is characterized in that the communication data amount is for each priority.

  The transmission request message of the bandwidth allocation method according to the present invention includes M (M is a natural number of 1 or more) queue sets, and each of the queue sets has m (m is a natural number of 2 or more) queue reports. The transmission request amount is a value of any one of the queue reports, or a sum of two or more queue report values, and the transmission request message includes M transmission request amounts, and the uplink data information Is characterized in that it includes first information indicating that it is Method A or Method B, and second information indicating that it is Method A or Method D.

However,
Method A is a method in which the optical subscriber unit preferentially transmits a frame included in the transmission request amount of each transmission request message,
Method O is a method in which the optical subscriber unit does not give priority to the frame included in the transmission request amount of each of the transmission request messages, and transmits with complete priority at the start of transmission,
Method IV is a method in which the optical subscriber unit transmits the frames according to the transmission priority for each queue set out of the frames included in the transmission request amount of each transmission request message. It is a method of transmitting the corresponding frame with priority according to the priority,
The method is a method in which the optical subscriber unit preferentially transmits the frame corresponding to the queue report among the frames included in the transmission request amount of each transmission request message according to the priority.

  In the present invention, the ONU notifies the OLT of whether the priority of the REPORTed frame and the priority of the REPORTed frame are prior to each QS, or for each ONU monitored by the OLT. By determining based on the REPORT amount, the allocated amount, and the received traffic amount, and allocating the band based on the result, it is possible to allocate the band with high band utilization efficiency and low delay.

  The identification procedure of the bandwidth allocation method according to the present invention includes a first determination step for definitively identifying whether the first information is the method A or the method B, and the first information is the method A A first inference step for inferring whether there is a method B or a first update step for updating the first information in the upstream data information based on the identification in the first determination step or the inference in the first inference step And a second confirmation step for definitively identifying whether the second information is the method fence or the method book, and a second guessing whether the second information is the method fence or the method book. A second estimation step, and a second update step for updating the second information of the uplink data information based on the identification in the second determination step or the estimation in the second estimation step.

  The transmission permission amount exceeding a maximum transmission request amount is allocated to the optical subscriber unit identified as the first information is the method B in the identification procedure of the bandwidth allocation method according to the present invention, To do. It is possible to prevent a delay in uplink data from an ONU having a low priority.

  The optical subscriber among the upstream traffic from the optical subscriber unit to the optical subscriber unit identified by the identification procedure of the bandwidth allocation method according to the present invention as the first information is the method B. The upstream traffic in which the value of the queue report in the transmission request message from a device is greater than zero and the amount of transmission data from the optical subscriber unit is zero with respect to the transmission permission amount based on the transmission request message When the presence / absence of the transmission request is detected, the transmission permission amount exceeding the sum of the transmission request amounts included in the transmission request message is allocated to the optical subscriber device based on the transmission request amount of all the optical subscriber devices. It is characterized by. It is possible to prevent a delay in uplink data from an ONU having a low priority.

  In the bandwidth allocation method according to the present invention, when the transmission permission amount exceeding the total transmission request amount included in the transmission request message is allocated to the optical subscriber device, the uplink traffic is transmitted from the optical subscriber device. The duration of the state in which the transmission data amount is zero is also considered.

  In the bandwidth allocation method according to the present invention, when allocating the transmission permission amount exceeding the sum of the transmission request amounts included in the transmission request message to the optical subscriber unit, an uplink high priority with higher priority than the uplink traffic is provided. The average transmission rate of the priority traffic is also taken into consideration.

  The passive optical communication network system according to the present invention includes a passive optical communication network in which an optical terminal device and a plurality of optical subscriber devices are connected via an optical transmission line, and each optical subscriber in the band allocation method. And a control device that dynamically allocates a communication band from the device to the optical terminal device.

  The present invention can provide a bandwidth allocation method that maintains high bandwidth utilization efficiency and realizes a low delay when dynamically assigning an upstream bandwidth of a PON, and a passive optical communication network system that implements the bandwidth allocation method.

It is a figure explaining a passive communication network system. It is a figure explaining a REPORT format. It is a figure explaining the ONU upstream priority policy of 1st embodiment. This is a case where priority is given to a REPORTed frame. It is a figure explaining the REPORT format of 1st embodiment. It is a figure explaining the state of the upstream transmission buffer of ONU of 1st embodiment. It is a figure explaining QS which ONU of 1st embodiment notified by REPORT, and the value of QR contained in it. It is a figure explaining the structure of OLT of 1st embodiment. It is a figure explaining the identification table which OLT of a first embodiment has. It is a figure explaining the procedure which identifies the uplink transmission priority of 1st embodiment. It is a figure explaining the procedure which identifies the uplink transmission priority of 1st embodiment. It is a figure explaining the procedure of the 1st identification of 1st embodiment. It is a figure explaining the uplink transmission control sequence of 1st embodiment. It is a figure explaining the procedure of the 2nd identification of 1st embodiment. It is a figure explaining the procedure of the 3rd identification of 1st embodiment. It is a figure explaining the procedure of the 4th identification of 1st embodiment. It is a figure explaining the procedure of the 5th identification of 1st embodiment. It is a figure explaining the calculation procedure of the transmission permission of 1st embodiment. It is a figure explaining the procedure of the 1st identification of 2nd embodiment. It is a figure explaining the procedure of the 3rd identification of 2nd embodiment. It is a figure explaining the procedure of the 4th identification of 2nd embodiment. It is a figure explaining ONU upstream priority policy. This is a case where priority is given to a REPORTed frame. It is a figure explaining the procedure of the 5th identification of 2nd embodiment.

  The target PON system in the present invention is a system in which upstream communication is realized by TDM (time division multiple access), and a plurality of ONUs are connected to the OLT. The ONU transmits uplink data only in accordance with transmission permission (transmission permission amount and transmission timing) from the OLT.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, what is given the same number in a figure shall have the same characteristic.

(First embodiment)
A first embodiment of the present invention will be described. A configuration of a passive optical communication network in the present embodiment is shown in FIG. A plurality of ONUs (3-1 to 3-4) are connected to the OLT 1 via the optical communication path 2. Although only four ONUs are connected to the OLT 1 here, the number of ONUs is not limited in the present invention. The same applies to the other embodiments.

  The lower networks (4-1 to 4-4) are connected to the corresponding ONUs (3-1 to 3-4), respectively, and the OLT 1 is connected to the upper network 5. The lower network 4 and the upper network 5 exchange information via the OLT 1, the optical communication path 2, and the ONU 3.

  Since a plurality of ONUs 3 are connected to the OLT 1, transmission of data signals from the ONU 3 to the OLT 1 (upward direction) is controlled by the OLT 1. Specifically, the OLT 1 gives an upstream signal transmission permission for each ONU 3, and the ONU 3 transmits an upstream data signal according to the given transmission permission. The upstream data signal is transmitted as a variable-length Ethernet (registered trademark) frame. Hereinafter, it is described as an uplink data frame.

  The OLT 1 includes a protocol defined as MPCP by IEEE 802.3ah, and the transmission permission to be given includes an uplink transmission time at which the ONU 3 starts uplink transmission and a transmission permission amount permitted to be transmitted. Information regarding these transmission permissions is mounted on a signal in a frame format called GATE, and is transmitted from the OLT 1 to each ONU 3.

  On the other hand, the upstream data frame is accumulated in upstream buffers provided in each of the ONUs 3 until transmission permission is given from the OLT 1. If the transmission permission is given, the stored uplink data frame is transmitted to the OLT 1 within the range of the transmission permission amount.

  The ONU 3 notifies the OLT 1 of the amount of uplink data frames accumulated in the uplink buffer by a transmission request signal. The transmission request signal is configured by a frame format signal called REPORT, which is defined as the MPCP.

  The REPORT frame has a plurality of queue sets (hereinafter, QS) in one frame, and can notify the OLT of a plurality of transmission request amounts. In one QS, an accumulation amount for each of a plurality of priority queues can be described. FIG. 4 shows a format example of the REPORT frame. In this example, two QSs of QS (1) and QS (2) are stored in one REPORT frame, and the number of QS is two.

  In the present embodiment, each ONU 3 has two priority queues.

  A plurality of uplink transmission priorities when the ONU 3 transmits uplink frames will be described with reference to FIG. Organize multiple methods. First, a REPORTed frame is prioritized or not. Assume that a buffer accumulation amount corresponding to frames [1] (33) in the high priority queue and frames [2] (34) in the low priority queue is notified by the REPORT, and at the transmission start time corresponding to the REPORT, the ONU upstream buffer Assume that high-priority frames [3] (315) that have not been REPORTed have been accumulated. At this time, when the priority is given to the REPORTed frame, the frame shown at 314 has been prioritized, and when the priority is not given to the REPORTed frame, the frame accumulated at the data transmission time T4 (38) is given full priority. .

  In the case where there is a priority of the REPORTed frame, there are a plurality of uplink transmission priorities such as priority for each QS or none. The priority for each QS will be described with reference to FIGS. FIG. 5 shows an example of the state of the ONU upstream transmission buffer. Assume that 3211 and 3212 frames are stored in Q1 of the high priority queue, and 3213 and 3214 frames are stored in Q0 of the low priority queue. FIG. 6 shows the QS notified by the ONU by REPORT and the QR value included therein. In this example, the number of queues, QS, and QR are two each. This ONU sets the transmission request amount corresponding to the data amount up to the maximum frame end below the threshold in the upstream buffer to QS1 in TQ units, and the transmission request amount obtained by subtracting QS1 from all the buffer accumulation amounts to QS2 in TQ units. Describe. When the target system is GE-PON, 1TQ = 2 bytes are converted. Here, the threshold value is set to 60 TQ, and the contents described in the REPORT of each ONU 3 calculated thereby are QS1 (1) = 50 TQ, QS1 (0) = 55 TQ, QS2 (1) = 51 TQ, QS2 (0) = 100 TQ It becomes. Here, QSm (k) represents the QRk of the m-th QS, and it is assumed that the higher the k, the higher the priority. Note that there is an ONU that uses QS2 as the total buffer storage amount itself as a QS QR calculation method. In this case, if a value converted as QS2 ′ (k) = QS2 (k) −QS1 (k) is used for all k, equivalent processing can be performed. The OLT needs to perform conversion after grasping or determining the QS calculation method of the ONU by any method, but this method is not limited in this embodiment.

  At this time, the transmission priority in the case of priority for each QS is QS1 (1) (3221 in the figure), QS1 (0) (3222 in the figure), QS2 (1) (3223 in the figure), QS2 ( 0) (3224 in the figure), whereas the transmission priority in the case of no priority for each QS is QS1 (1) (3221 in the figure), QS2 (1) (3223 in the figure), The order is QS1 (0) (3222 in the figure) and QS2 (0) (3224 in the figure).

  The ONU 3-1 has priority for the REPORTed frame and priority for each QS. When the OLT permits transmission of 50 TQ, 105 TQ, 156 TQ, or 256 TQ to this REPORT, the ONU 3-1 can match the transmission permission amount with the transmission amount in all cases. However, when the transmission permission amount is 101 TQ, only transmission for 50 TQ can be performed, so the transmission permission amount does not match the transmission amount.

  The ONU 3-2 is assumed to have priority for the REPORTed frame and no priority for each QS. When the OLT 1 permits transmission of 50TQ, 101TQ, 156TQ, or 256TQ to this REPORT, the ONU 3-2 can match the transmission permission amount and the transmission amount in all cases. However, when the transmission permission amount is set to 105 TQ, only the transmission for 101 TQ can be performed, so the transmission permission amount and the transmission amount do not match.

  The ONU 3-3 has no priority for the REPORTed frame. It is assumed that high priority frames arrive at the ONU 3-3 at regular intervals. When the OLT 1 permits transmission of 256 TQ to this REPORT, the ONU 3-3 may be able to match the transmission permission amount with the transmission amount, but may not be able to match.

  In the present embodiment, it is assumed that the OLT 1 can collect the REPORT content for each ONU 3, the transmission permission amount G, and the reception amount Rx that is not distinguished for each priority. The OLT 1 determines the upstream transmission priority of the ONU 3 based on these pieces of information.

  A configuration of the OLT 1 in this embodiment is shown in FIG. The upstream frame transmitted by each ONU 3 and reaching the OLT 1 via the communication path 2 is received by the transmission / reception unit 11. Thereafter, the reception amount is measured by the reception amount measurement unit 12. The reception amount measurement unit 12 measures the reception amount of only the upstream data frame for each ONU 3 and after distinguishing the upstream data frame and the REPORT frame. Further, the received amount is obtained by adding overhead (preamble: 8 bytes, minimum interframe gap: 12 bytes, etc.) necessary for frame transmission in the Ethernet (registered trademark) format to the received upstream data frame. . This is for the purpose of matching the transmission permission amount, and when using an error correction code, the parity length to be given is also taken into consideration. The reception amount measuring unit 12 records the measured reception amount in the storage unit 17.

  Thereafter, the upstream data frame is transferred to the upper network 5 via the IF unit 15. On the other hand, the REPORT frame is transferred to the identification unit 13. Based on the received REPORT frame, the identification unit 13 identifies a method for calculating the transmission request amount of each ONU 3. The calculation method is QS calculation and QS order. The identified result is recorded in the identification table 14 and referred to at the time of identification. The result recorded in the storage unit 17 is also referred to.

  The REPORT frame is then transferred to the transmission permission calculation unit 16. Based on the received REPORT frame and the identification table 14, the transmission permission calculation unit 16 calculates a transmission permission amount and a transmission permission time for each ONU 3, and generates and transmits a GATE frame describing these. Thereafter, the GATE frame is multiplexed with the downlink data frame transferred from the upper network 5 via the IF unit 15, and transmitted to the optical communication path 2 via the transmission / reception unit 11.

  In addition, the transmission permission calculation unit 16 records the QR value of each QS included in the received REPORT frame and the calculated transmission permission amount in the storage unit 17.

  Details of the identification table 14 are shown in FIG. The identification table 14 has an upstream transmission priority identification result for each ONU 3. Specifically, each of the priority of the REPORTed frame and the priority for each QS has a value and a state. The value can be “Yes” or “No” for each of the priority of the REPORTed frame and the priority for each QS. Further, the state can be “confirmed” or “unconfirmed”. The state means certainty with respect to the identified result. For example, if the priority of the REPORTed frame is “Yes”, the priority state of the REPORTed frame is set to “Confirmed”. If the probability is high but not certain, it is determined as “indeterminate”. The values and states described in FIG. 8 are examples, and these are updated according to the identification result of the identification unit 13.

  When the ONU 3 connects to the OLT 1 for the first time, the priority status of the REPORTed frame and the priority status for each QS are set to “indeterminate” for the corresponding ONU 3 in the identification table 14. There are no particular restrictions on the initial values, but here, “Yes” and “Yes” respectively. However, for an ONU for which the uplink transmission priority is specified, for example, information on the transmission request calculation method is given in advance, the state of the identification table 14 is set to “determined” and the value is set to the specified value. Keep it.

Next, a procedure for identifying the uplink transmission priority by the identification unit 13 will be described with reference to FIGS. 9 and 10. The general flow of the identification procedure is as follows.
(First identification: S602)
Whether the priority of the REPORTed frame can be definitely determined is identified.
(Second identification: S606)
The priority of the REPORTed frame is used to identify which value can be determined as having a high probability.
(Third and fifth identification: S611, S619)
If the priority of the REPORTed frame is “present”, it is identified whether the priority for each QS can be definitely determined.
(Fourth and sixth identification: S617, S620)
If the priority of the REPORTed frame is “present”, the priority for each QS identifies which value can be determined to be more likely.

  This identification is performed for each ONU 3. However, the trigger for starting identification is not particularly limited. Each time a REPORT frame is received, it may be performed on the ONU 3 that transmitted the REPORT frame, or the received REPORT frame may be stored and received together from a plurality of ONUs 3 (execution for each ONU 3 is performed). (Repeat) may be carried out. In any case, as long as there is a REPORT frame to be referred to for identification, it can be implemented at any opportunity.

  Details of the identification procedure will be described below. First, with reference to the identification table 14, the priority state of the REPORTed frame of the ONU 3 to be identified is confirmed (S601). In steps S602 to S607, in order to identify the priority of the REPORTed frame, if it is confirmed that the determination has already been made in S601, these steps are skipped and the process proceeds to S608. On the other hand, if “indeterminate”, the first identification is performed (S602). In the first identification, it is identified whether the priority of the REPORTed frame can be definitely determined. If the priority of the REPORTed frame is not determined by the first identification, the second identification is performed (S606). In the second identification, it is identified whether there is any of the priority values of the REPORTed frame that can be determined to be more likely.

  Next, priority is identified for each QS in steps S608 to S624. First, the priority value of the REPORTed frame in the identification table 14 is confirmed (S608). If the priority of the REPORTed frame is “none”, the priority identification for each QS is not performed. The identification is terminated by skipping S609 to S624. If the priority of the REPORTed frame is “Yes”, the priority state for each QS in the identification table 14 is referred to (S609), and if it is already “confirmed”, the identification is terminated. On the other hand, if it is “indeterminate”, the priority state of the REPORTed frame is confirmed (S610). If the priority state of the REPORTed frame is “confirmed”, the third identification is performed (S611). In the third identification, it is identified whether the priority value for each QS can be definitely determined. If the priority value for each QS can be determined as a result of the third identification (S612), the state is determined, the value is updated, and the process ends. If the priority value for each QS cannot be determined as a result of the third identification (S612), the process ends. If the priority state of the REPORTed frame is “indeterminate” in S610, the fourth identification is performed (S617). In the fourth identification, it is identified whether the priority value for each QS can be definitely determined. If the priority value for each QS can be determined as a result of the fourth identification (S618), the priority of the REPORTed frame and the priority state for each QS are set to “confirmed” (S621, S623), and the priority value of the REPORTed frame “Yes”, the priority value for each QS is updated to the value of the fifth identification result, and the process ends (S622, S624). If the priority value for each QS cannot be determined as a result of the fifth identification (S618), the fifth identification is performed (S619). The fifth identification identifies a highly probable value among the priority values for each QS. Next, the value is updated (S620) and the process ends.

  With the above procedure, the priority of the REPORTed frame and the priority for each QS are identified. If deterministic identification is possible, each value is confirmed, and if it is not a condition where definitive identification is possible, the value is updated to a higher probability.

  Next, each identification procedure will be described in detail.

  FIG. 11 shows the procedure of the first identification (S602). In the first identification, priority identification of the REPORTed frame is performed. First, as an initialization process, the first identification result (state) is unconfirmed (S701). Next, it is determined whether the priority of the REPORTed frame can be definitely identified as “none”. Specifically, it is determined whether or not the condition 1-1 is satisfied (S702). Condition 1-1 is that the expression 1-1 is satisfied. When this equation is satisfied, it can be definitely identified that the priority of the REPORTed frame is “none”. Here, G represents a transmission permission amount corresponding to the corresponding REPORT, Rx represents an OLT reception amount corresponding to the corresponding transmission permission amount, and mFLTQ (minFrameLengthTQ) represents a TQ converted value of the minimum frame length.

  FIG. 12 shows an uplink transmission control sequence. In response to the transmission request amount (each QS and the QR value included therein) notified by the ONU by the REPORT (1511), the OLT sends the transmission permission amount G calculated based on the contents of the REPORT and the transmission start time to the transmission permission signal (1512). ) The ONU transmits a data signal (1523) in accordance with each uplink transmission priority within the range of the transmission permission amount G from the transmission start time notified from the OLT.

  Condition 1-1 in FIG. 11 indicates that when the OLT allocates the transmission permission amount equal to the total REPORT amount, the ONU cannot transmit the same amount as the allocation amount. This can occur only when a high priority frame arrives in the ONU upstream buffer between the GATE reception and the transmission start time when the priority of the REPORTed frame is “none”.

  If the condition 1-1 is met in step S702, the first identification result (value) is set to “none”, the first identification result (state) is set to “confirmed” (S704), and the first identification is performed. Exit.

  On the other hand, if they do not match, it is determined whether the priority of the REPORTed frame can be identified as “present”. Specifically, it is determined whether or not the condition 1-2 is met (S703). Condition 1-2 is that the expression 1-2 is satisfied. This means that when these expressions are satisfied, the priority of the REPORTed frame can be definitely identified as “Yes”. This condition is that the ONU uplink transmission priority is complete because the low-priority traffic frame is received even though a part of the high-priority traffic frame stored in the buffer is not transmitted. It clearly indicates that it is not a priority.

  FIG. 13 shows a second identification procedure (S606). In the second identification, among the priority values of the REPORTed frame, a value having a high probability of being taken is identified. Specifically, whether the condition 2-1 is met is identified. If they match, the identification result is “Yes” and the status is “Undefined”. This formula is always satisfied when the priority of the REPORTed frame is “Yes”, but even when it is “No”, a high priority frame must arrive at the ONU upstream buffer between the GATE reception and the transmission start time. The condition cannot be determined.

  Next, a third identification procedure (S611) is shown in FIG. In the third identification, the priority for each QS is identified. First, as an initialization process, the second identification result (state) is set to “indeterminate” (S901). Next, it is identified whether the priority for each QS can be definitely determined as “Yes”. Specifically, it is determined whether or not the condition 3-1 is met (S802). Condition 3-1 is conditional on satisfy | filling Formula 3-1. If these formulas are satisfied, the priority for each QS can be definitely identified as “Yes”.

  If the condition 3-1 is met in step S902, the third identification result (value) is “present”, the third identification result (state) is “confirmed” (S904), and the second identification is performed. Exit.

  On the other hand, if they do not match, it is identified whether it is possible to definitely determine that the priority for each QS is “none”. Specifically, it is determined whether or not the condition 3-2 is met (S903). Condition 3-2 is that the expression 3-2 is satisfied. In this case, when these equations are satisfied, it can be definitely identified that the priority for each QS is “none”.

  If the condition 3-2 is met in step S903, the third identification result (value) is set to “none”, the third identification result (state) is set to “confirmed” (S905), and the third identification is performed. Exit.

  Next, a fourth identification procedure (S617) is shown in FIG. In the fourth identification, the priority for each QS is definitely identified. First, as an initialization process, the fourth identification result (state) is set to “indeterminate” (S1001). Next, it is identified whether the priority for each QS can be definitely determined as “Yes”. Specifically, it is determined whether or not the condition 4-1 is satisfied (S1002). Condition 4-1 is on condition that Expression 4-1 is satisfied. If these formulas are satisfied, the priority for each QS can be definitely identified as “Yes”.

  If the condition 4-1 is met in step S1002, the fourth identification result (value) is “present”, the fourth identification result (state) is “confirmed” (S1004), and the fourth identification is performed. Exit.

  Next, a fifth identification procedure (S619) is shown in FIG. In the fifth identification, it is identified whether there is a highly probable value among the priority values for each QS. First, as an initialization process, the fifth identification result (state) is set to “indeterminate” (S1101). Next, it is identified whether there is a high probability that the priority for each QS is “none”. Specifically, it is determined whether or not the condition 5-1 is satisfied (S1102). Condition 5-1 is that the expression 5-1 is satisfied. If these formulas are satisfied, it can be identified that there is a high probability that the priority for each QS is “none”.

  If the condition 5-1 is met in step S1102, the fifth identification result (value) is “present”, the fifth identification result (state) is “unconfirmed” (S1104), End identification.

  Through the above procedure, the identification unit 13 identifies the uplink transmission priority for each ONU 3 and updates the identification table 14.

  Next, calculation of transmission permission by the transmission permission calculation unit 16 will be described. The transmission permission calculation unit 16 refers to the identification table 14 and calculates the transmission permission to each ONU 3 according to the REPORT frame transferred from the identification unit 13. The calculation of the transmission permission by the transmission permission calculation unit 16 is performed after all the REPORTs transmitted by the respective ONUs 3 are received.

  FIG. 17 shows a procedure for calculating transmission permission by the transmission permission calculating unit 16. First, on the basis of the identification table 14 and the REPORT frame transferred from the identification unit 13, an amount that is an allocation candidate is calculated for each ONU (S1201). Next, a transmission permission amount is calculated for each ONU (S1202). Finally, a transmission permission time is calculated (S1203).

A procedure for calculating the amount to be an allocation candidate will be described below.
When the value of the uplink transmission priority of the corresponding ONU _i is the priority “Yes” of the REPORTed frame and the priority “Yes” for each QS, the uplink transmission priority is high in order to match the allocated amount and the transmission amount. The sum of QR is calculated in order and set as an allocation candidate. In the case of this embodiment,
1st candidate R _i (1) = QS1 (0)
Second candidate R _i (2) = QS1 (0) + QS1 (1)
Third candidate R _i (3) = QS1 (0) + QS1 (1) + QS2 (0)
Fourth candidate R _i (4) = QS1 (0) + QS1 (1) + QS2 (0) + QS2 (1)
And

When the value of the uplink transmission priority of the corresponding ONU _j is the priority “present” of the REPORTed frame and the priority “none” for each QS, the uplink transmission priority is high in order to match the allocated amount and the transmission amount. The sum of QR is calculated in order and set as an allocation candidate. In the case of this embodiment,
First candidate R _j (1) = QS1 (0)
Second candidate R _j (2) = QS1 (0) + QS2 (0)
Third candidate R _j (3) = QS1 (0) + QS2 (0) + QS1 (1)
Fourth candidate R _j (4) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1)
And

If the value of the uplink transmission priority of the corresponding ONU _k is the priority “None” of the REPORTed frame, the sum of QR is calculated with complete priority to prevent an increase in delay of the low priority frame, and is set as an allocation candidate. Big Grant (BG) larger than the fourth candidate is inserted as the final candidate. In the case of this embodiment,
First candidate R _j (1) = QS1 (0)
Second candidate R _j (2) = QS1 (0) + QS2 (0)
Third candidate R _j (3) = QS1 (0) + QS2 (0) + QS1 (1)
Fourth candidate R _j (4) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1)
Fifth candidate R _j ( 5 ) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1) + α
And Here, for example, α = maximum frame length.

  With the above procedure, it is possible to calculate the amount to be an allocation candidate for each ONU.

  Although the transmission permission amount calculation procedure (S1202) is not limited in detail in the present invention, the OLT uses the same amount of data as any of the allocation candidates for each ONU as the transmission permission amount. The OLT monitors the uplink request amount of the ONU, and assigns the bandwidth so as not to be wasted as much as possible by repeatedly assigning the next largest allocation candidate if a surplus bandwidth occurs.

  When a surplus bandwidth occurs, such as when the total amount of uplink requests for all ONUs does not reach the entire bandwidth, it may be distributed to ONUs that have transmission requests.

  Although the transmission permission time calculation procedure (S1203) is not specifically limited in the present invention, for example, the OLT calculates the transmission permission time in order from the beginning of the transmittable time of the allocation period to each ONU. . The transmission permission time is a time obtained by adding the transmission permission amount of the corresponding ONU and a certain burst gap to the transmission time of the allocation cycle or the transmission permission time of the previous ONU.

  Through the above-described series of procedures, the transmission request amount method for each ONU can be identified, and an appropriate transmission permission to each ONU can be calculated based on the result.

(Second embodiment)
Next, a second embodiment in the present invention will be described. In the second embodiment, the reception amount measuring unit 12 of the OLT 1 in FIG. 7 can measure the frame reception amount for each priority, and other preconditions are the same as those in the first embodiment. Since the OLT 1 can measure the amount of received frames for each priority, the conditions for determining the upstream transmission priority are increased, and the ease and certainty of determination are improved. In addition, the size of the BG as an allocation candidate for the ONU 3 with priority “NONE” of the REPORTed frame can be determined according to the amount of high-priority traffic, and the timing of inserting the BG into the allocation candidate Since it can be determined according to an increase in delay, the delay time of low priority traffic can be reduced more appropriately.

  The second embodiment is almost the same as the first embodiment except for the following three points. (1) The reception amount measurement unit 12 of the OLT 1 can measure the frame reception amount for each priority. (2) The number of conditional expressions used in the identification procedure increases. (3) The BG used as the allocation candidate for the ONU 3 with the priority “NONE” in the REPORTed frame is set as the first allocation candidate when the allocation period in which the low-priority QR is greater than zero and the reception amount is equal to or greater than a certain value. The size is calculated based on the reception rate obtained from the reception amount of the high priority frame. Details are described below.

  In the present embodiment, the OLT 1 uses the procedure shown in FIG. 18 as the first identification procedure instead of the procedure shown in FIG. The difference from the first embodiment is the conditions used in S7102 and S7103. In S7102, it is determined whether or not it is possible to definitely determine that the priority of the REPORTed frame is “none”. Specifically, it is determined whether or not the condition 1-3 is met (S7102). Condition 1-3 is conditional on satisfying Formula 1-1 or 1-3. Here, Rx (k) indicates the amount of traffic received with priority k. That is, Rx (1) represents the amount of received highest priority traffic with priority 1, and Rx (0) represents the amount of received traffic with priority 0. When these expressions are satisfied, the priority of the REPORTed frame can be definitely identified as “Yes”. Compared to the first embodiment, Formula 1-3 is added.

  In step S7103, it is determined whether the priority of the REPORTed frame can be definitely determined as “present”. Specifically, it is determined whether or not the condition 1-4 is met (S7103). Condition 1-4 is conditional on satisfying Formula 1-2 or 1-4. Compared to the first embodiment, Formulas 1-4 are added.

The OLT 1 uses the procedure shown in FIG. 19 as the third identification procedure instead of the procedure shown in FIG. The difference from the first embodiment is the conditions used in S9102 and S9103. In S9102, it is identified whether or not it is possible to definitely determine that the priority for each QS is “Yes”. Specifically, it is determined whether or not the condition 3-3 is met (S9102). Condition 3-3 is conditional on satisfying Formula 3-1 or 3-3. When these expressions are satisfied, the priority for each QS can be definitely identified as “Yes”. Compared to the first embodiment, Formula 3-3 is added.
In step S9103, it is determined whether or not the priority of the REPORTed frame can be definitely determined as “none”. Specifically, it is determined whether or not the condition 3-4 is met (S9103). Condition 3-4 is conditional on satisfying Formula 3-2 or 3-4. Compared to the first embodiment, Formula 3-4 is added.

  The OLT 1 uses the procedure shown in FIG. 20 for the fourth identification procedure instead of the procedure shown in FIG. The difference from the first embodiment is the conditions used in S10102 and S10104. In S10102, it is identified whether or not it is possible to definitely determine that the priority for each QS is “Yes”. Specifically, it is determined whether or not the condition 4-2 is met (S10102). Condition 4-2 is that Condition 4-1 or 4-2 is satisfied. When these expressions are satisfied, the priority for each QS can be definitely identified as “Yes”. Compared to the first embodiment, Formula 4-2 is added.

  As described above, in the second embodiment, the conditions that can be used for identification are broadened compared to the first embodiment, so that identification is easier.

  In the present embodiment, the BG used as the allocation candidate for the ONU having the priority “NONE” in the REPORTed frame is assigned to the fifth allocation when the allocation period in which the low-priority QR is greater than zero and the reception amount is zero is equal to or greater than a certain value As a candidate, the size is calculated based on the reception rate obtained from the reception amount of the high priority frame.

From the above, the allocation candidate for the ONU with the priority “none” of the REPORTed frame is
First candidate R _j (1) = QS1 (0)
Second candidate R _j (2) = QS1 (0) + QS2 (0)
Third candidate R _j (3) = QS1 (0) + QS2 (0) + QS1 (1)
Fourth candidate R _j (4) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1)
When the allocation period in which the low-priority QR is greater than zero and the reception amount is zero is greater than or equal to a certain value,
First candidate R _j (1) = QS1 (0)
Second candidate R _j (2) = QS1 (0) + QS2 (0)
Third candidate R _j (3) = QS1 (0) + QS2 (0) + QS1 (1)
Fourth candidate R _j (4) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1)
Fifth candidate R _j ( 5 ) = QS1 (0) + QS2 (0) + QS1 (1) + QS2 (1) + α
And Here, as an example, α = A · Rx (0). A is a constant. In this way, the size of the BG is calculated based on the received amount of high priority traffic. As a result, the size of the BG can be determined according to the rate of high-priority traffic, and an increase in delay time of low-priority frames can be prevented more effectively.

  By the above procedure, it is possible to prevent an increase in delay of a low priority frame of an ONU that has no priority for a REPORTed frame.

1, ...: OLT
2, ...: Optical communication path 3-1, 3-2, 3-3, 3-4, ...: ONU
4-1, 4-2, 4-3, 4-4,...: Lower network 5,...: Upper network 12: received amount measuring unit 13: identifying unit 14: identifying table 15: IF unit 16: Transmission permission calculation unit 17: storage unit

Claims (9)

In a passive optical communication network in which an optical terminal device and a plurality of optical subscriber devices are connected via an optical transmission line, a communication band is dynamically allocated from each optical subscriber device to the optical terminal device. A bandwidth allocation method comprising:
Holds uplink data information related to transmission priority of uplink data for each optical subscriber unit,
Based on the transmission request amount indicated by the transmission request message received from the optical subscriber device and the uplink data information, when calculating the transmission permission amount allowed to the optical subscriber device ,
The transmission request amount for each optical subscriber unit, the past transmission permission amount for each optical subscriber unit, the communication data amount transmitted by the optical subscriber unit and received by the optical terminal unit, An identification procedure for identifying whether the uplink data information is confirmed or not confirmed based on the bandwidth allocation method. The bandwidth allocation method according to claim 1 , wherein the communication data amount is for each priority. The transmission request message includes M (M is a natural number of 1 or more) queue sets, each of the queue sets includes m (m is a natural number of 2 or more) queue reports,
The transmission request amount is any one of the queue report values or a sum of two or more queue report values, and the transmission request message includes M transmission request amounts,
The uplink data information, wherein a first information indicating that the method is Party or method Otsu, a second information indicating a process Hei or method Ding, to claim 1 or 2, characterized in that it comprises a Bandwidth allocation method.
However,
The method A is a method in which the optical subscriber unit preferentially transmits a frame included in a transmission request amount of each transmission request message,
The method B is a method in which the optical subscriber unit does not give priority to the frame included in the transmission request amount of each of the transmission request messages, and transmits with complete priority at the start of transmission,
The method IV includes a queue report included in each queue set in a method in which the optical subscriber unit transmits frames according to a transmission priority for each queue set among frames included in the transmission request amount of each transmission request message. Is a method for transmitting frames that correspond to the priority according to the priority,
The method is a method in which the optical subscriber unit preferentially transmits the frame corresponding to the queue report among the frames included in the transmission request amount of each transmission request message according to the priority. The identification procedure is:
A first determination step deterministically identifies whether the first information is the method wherein the method Party B or a shell,
A first guess step of the first information to guess whether the Otsu said method said method or an instep,
A first update step of updating the first information of the uplink data information based on the identification in the first determination step or the estimation in the first estimation step;
A second determination step deterministically identifies whether the second information is the method signature whether said method hei,
A second guess step of the second information to guess whether it is the method signature whether said method hei,
A second update step for updating the second information of the uplink data information based on the identification in the second determination step or the estimation in the second estimation step;
The band allocation method according to claim 3 , further comprising: To the identification procedure the first information in the identification and the process is Otsu the said optical subscriber unit,
4. The bandwidth allocation method according to claim 3, wherein a transmission permission amount exceeding a total sum of the transmission request amounts is allocated. To the identification procedure the first information in the identification and the process is Otsu the said optical subscriber unit,
Of the upstream traffic from the optical subscriber unit,
The value of the queue report in the transmission request message from the optical subscriber unit is greater than zero, and the transmission data amount from the optical subscriber unit is zero with respect to the transmission permission amount based on the transmission request message. When the presence / absence of the upstream traffic is detected,
Based on the transmission demand of all the optical subscriber units, according to claim 3, in the optical subscriber units, and allocates the transmission permission amount that exceeds the sum of the transmission request amount contained in the transmission request message Bandwidth allocation method described in 1. When allocating the transmission permission amount exceeding the sum of the transmission request amounts included in the transmission request message to the optical subscriber device,
7. The bandwidth allocation method according to claim 6 , wherein a continuation time in which the amount of transmission data from the optical subscriber unit is zero is also considered for the upstream traffic. When allocating the transmission permission amount exceeding the sum of the transmission request amounts included in the transmission request message to the optical subscriber device,
The band allocation method according to claim 6 or 7 , wherein an average transmission rate of upstream high priority traffic having a higher priority than the upstream traffic is also taken into consideration. A passive optical communication network in which an optical terminal device and a plurality of optical subscriber devices are connected via an optical transmission line;
And dynamically allocating the control device a communication band to said optical terminal equipment from each of the optical subscriber units in a band allocation method according to any one of claims 1 to 8,
A passive optical communication network system comprising:

Images