JP5807450B2 - Master station apparatus, communication system, and downlink data transfer control method - Google Patents

Description

  The present invention relates to a master station device, a communication system, and a downlink data transfer control method. For example, the present invention relates to a passive optical network (PON) system that controls uplink transmission timing by dynamic bandwidth allocation (DBA). It can be applied.

  The PON system generally has a layer configuration as shown in FIG. OLT (Optical Line Terminal) is a maintenance / operation / monitoring (OAM) layer protocol, which is used to maintain and maintain ONU (Optical Network Unit). An operation / monitoring function is provided (see Non-Patent Document 1). The OAM layer provides a service using an OAM PDU (PDU is Protocol Data Unit) to the upper layer. The upper layer uses the OAM layer service to transmit and receive OAM PDUs between opposing nodes to realize a maintenance / operation / monitoring function. For transmission of OAMPDU, an upper limit of the number of transmissions of 10 frames per second is defined, and occupation of the line bandwidth due to continuous transmission of OAMPDU is suppressed.

  In the upstream time division PON system, upstream bandwidth allocation is realized by the DBA function (see Non-Patent Document 2). The uplink frame transmission timing for each ONU is controlled by the DBA function implemented in the OLT. The DBA function of the OLT instructs upstream frame transmission timing for all ONUs for each DBA cycle. As a result, collision of upstream transmission frames from each ONU can be avoided, and bandwidth allocation (frame transmission time allocation) for each ONU according to the upstream bandwidth control policy can be realized.

IEEE 802.3ah Clause. 57 IEEE 802.3av

  By the way, a group of data related to a large amount of OAM must be transmitted from the OLT to the ONU. For example, in the process of updating ONU software, it may be desired to transfer the updated software from the OLT to the ONU using an OAM layer (OAMPDU) function. Although the transmission restriction of OAMPDU transmission within 10 frames per second is effective in guarding the occupation of the downlink bandwidth, it takes time for a large amount of data transfer such as update software transfer to the ONU. Also, every time the update software is divided and the downlink frame in which the divided data part is inserted is transferred from the OLT to the ONU, an ACK must be transmitted from the ONU to the OLT, and the uplink allocated by the DBA cycle is also considerable. It will be affected. On the other hand, if the transmission restriction is canceled in order to shorten the data transfer time, there is a possibility of occupying the downlink band by the update software transfer to the ONU, and the user band is reduced.

  Therefore, there is a demand for a master station device, a communication system, and a downlink data transfer control method that can reduce the transfer time of a group of data to be transferred to a slave station device and reduce the downlink occupied bandwidth of the transfer data.

  In the first aspect of the present invention, the master station device transmits data in units of frames to any one of the plurality of slave station devices via the relay device, and the predetermined number of frames are continuously transmitted. The slave station apparatus received by the master station apparatus returns a reception response frame to the master station apparatus via the relay apparatus according to the dynamic band allocation period determined by the master station apparatus dynamically allocating the band. In the master station device to which the master station device corresponds, the total size of data transferred from the master station device to the slave station device, the dynamic bandwidth allocation period, and the amount of data included in one frame At least a fixed value, and while changing the upper limit number of frames per predetermined time allowed to be transferred from the master station device to the slave station device, all the data to be transferred for each value of the upper limit frame number The transfer time that can be transferred is calculated, and when the upper limit frame number is changed from a small value to a large value, the upper limit frame number per predetermined time at the change point at which the calculated transfer time is considered to have converged is obtained. The parent station device has a restriction setting unit that sets the upper limit number of frames per predetermined time of change points as a restriction when transferring data from the own device to the child station device.

  According to the second aspect of the present invention, the master station device transmits data in units of frames to any one of the plurality of slave station devices via the relay device, and the predetermined number of frames are continuously transmitted. The slave station apparatus received by the master station apparatus returns a reception response frame to the master station apparatus via the relay apparatus according to the dynamic band allocation period determined by the master station apparatus dynamically allocating the band. In the above, the master station device is the master station device according to the first aspect of the present invention.

  According to a third aspect of the present invention, the master station device transmits data in units of frames to any one of the plurality of slave station devices via the relay device, and the predetermined number of frames are continuously transmitted. The slave station apparatus received by the master station apparatus returns a reception response frame to the master station apparatus via the relay apparatus according to the dynamic band allocation period determined by the master station apparatus dynamically allocating the band. In the downlink data transfer control method, the master station device has at least a total size of data transferred from the device itself to the slave station device, the dynamic bandwidth allocation period, and a data amount included in one frame. While changing the upper limit number of frames per predetermined time that is allowed to be transferred from the own device to the slave station device, the entire data to be transferred is changed for each value of the upper limit frame number. When the transfer time that can be sent is calculated, and the upper limit frame number is changed from a small value to a large value, the upper limit frame number per predetermined time at the change point at which the calculated transfer time is considered to have converged is obtained. The upper limit number of frames per predetermined time of points is set as a limit at the time of data transfer from the own apparatus to the slave station apparatus.

  According to the master station apparatus, the communication system, and the downlink data transfer control method of the present invention, it is possible to reduce the transfer time of a group of data to be transferred to the slave station apparatus and to reduce the downlink occupied band of the transfer data.

It is a block diagram which shows the functional structure of OLT in 1st Embodiment. 5 is a flowchart illustrating processing of an OAM layer processing unit that is executed when ONU software transfer processing is activated in the first embodiment. It is a sequence diagram which shows the data transfer model on the OAM layer which 1st Embodiment presupposes. 4 is a graph (part 1) showing a relationship between the number of downlink transmission frames per second, the transfer time obtained by calculation, and the transfer bandwidth obtained by calculation, applying the model of FIG. 4 is a graph (part 2) showing the relationship between the number of downlink transmission frames per second, the transfer time obtained by calculation, and the transfer bandwidth obtained by calculation, applying the model of FIG. 4 is a graph (part 3) showing the relationship between the number of downlink transmission frames per second, the transfer time obtained by calculation, and the transfer bandwidth obtained by calculation, applying the model of FIG. 6 is a flowchart illustrating a first specific method for determining the number of downlink transmission frames per second in the first embodiment. In 1st Embodiment, it is explanatory drawing of the 2nd specific method of determining the downlink transmission frame restriction | limiting number per second. It is a block diagram which shows the functional structure of OLT in 2nd Embodiment. It is a sequence diagram which shows the generalized traffic model which 2nd Embodiment presupposes. It is explanatory drawing which shows the general layer structure in a PON system.

(A) First Embodiment Hereinafter, a first embodiment of a master station apparatus, a communication system, and a downlink data transfer control method according to the present invention will be described with reference to the drawings. The communication system of the first embodiment is a PON system, and the master station device of the first embodiment is an OLT.

(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing a functional configuration of the OLT 10 in the first embodiment. In FIG. 1, an OLT 10 includes an OAM layer processing unit 11, an OAM frame generation unit 12, a main signal frame generation unit 13, a transmission frame multiplexing unit 14, a reception frame demultiplexing unit 15, an OAM frame termination unit 16, and a main signal frame termination unit. 17.

  The OAM layer processing unit 11 executes OAM layer processing related to the maintenance / operation / monitoring function. The OAM layer processing unit 11 is mainly configured by, for example, a CPU and software executed by the CPU. The OAM layer processing unit 11 gives the OAM frame generation unit 12 when data (OAMPDU) related to OAM to be given to any or all ONUs (not shown) is generated. Here, the data frequency given to the OAM frame generation unit 12 by the OAM layer processing unit 11 is set to be within the OAM transmission frame limit number determined as described later based on the data size of a group of data. Yes.

  The OAM frame generation unit 12 generates an OAM frame by adding overhead or the like to the OAM PDU and gives it to the transmission frame multiplexing unit 14.

  The main signal frame generation unit 13 generates a main signal frame by adding overhead to user data (main signal) to be given to any or all ONUs (not shown) given from the host device of the OLT 10 and transmits the main signal frame. This is given to the frame multiplexing unit 14.

  The transmission frame multiplexing unit 14 time-division-multiplexes the OAM frame given from the OAM frame generation unit 12 and the main signal frame given from the main signal frame generation unit 13 and outputs the result as a downlink transmission frame. is there. Such a time-division multiplexed frame is converted into an optical signal in the OLT 10 and transmitted to the common optical fiber in the downstream direction.

  A frame composed of an optical signal transmitted from each ONU and introduced into the common optical fiber in the upstream direction via an optical splitter (not shown) is converted into an electrical signal in the OLT 10 and received frame demultiplexing unit 15 Given to. The received frame demultiplexing unit 15 determines whether the received frame that has been time-division multiplexed is an OAM frame or a main signal frame based on the overhead, gives the received OAM frame to the OAM frame termination unit 16, and receives the received main frame. The signal frame is given to the main signal frame termination unit 17.

  The OAM frame termination unit 16 performs termination processing such as removing overhead from the received OAM frame, and provides the obtained OAM data to the OAM layer processing unit 11. Note that some OAM frames to be received do not include a payload such as an ACK frame. In such a case, the fact that the ACK frame has been received is transmitted from the OAM frame termination unit 16 to the OAM layer processing unit 11. Be notified.

  The main signal frame termination unit 17 performs termination processing such as removing overhead from the received main signal frame, and sends the obtained user data (main signal) to the host device of the OLT 10.

(A-2) Operation of First Embodiment As an OAM layer process executed by the OAM layer processing unit 11 of the OLT 10, there is a process of sending a group of large amounts of data to an ONU. For example, when the software executed by the CPU in the ONU is updated, when transferring the entire updated software instead of the difference before and after the update, the OAM layer processing unit 11 sends a group of large amounts of data to the ONU. (Note that the amount of data may increase even when transferring the difference in the update). Such software transfer processing to the ONU (hereinafter referred to as ONU software) should be transferred to the OAM layer processing unit 11 (or a memory connected to the OAM layer processing unit 11) by a host device or a maintenance terminal (not shown). It is started after the ONU software is prepared.

  FIG. 2 is a flowchart showing the processing of the OAM layer processing unit 11 executed when the ONU software transfer processing is activated.

  When the transfer process is activated, the OAM layer processing unit 11 first confirms the data size of the ONU software (step 100), and then divides the ONU software into data amounts to be included in the payload of each OAM frame (convert to OAMPDU). ) To grasp the total number of frames to be transferred (step 101). Also, the DBA cycle for the upstream transfer at that time is taken in (step 102). Using the total number of frames, the DBA period, etc., the OAM transmission frame limit number is determined and set (step 103), and transfer is started (step 104). Then, the completion of the transfer of the total number of frames to be transferred is confirmed, and the series of processing shown in FIG. 2 is terminated (step 105).

  As described above, conventionally, the OAM transmission frame limit number M is a fixed value such as 10 frames / second. The first embodiment is characterized in that the OAM transmission frame limit number M is dynamically determined in accordance with the data size of the ONU software (thus, the total number of frames to be transferred), the DBA cycle, and the like.

  Hereinafter, a method of determining the OAM transmission frame limit number M in step 103 will be described. The OAM transmission frame limit number M is naturally determined from the relationship between the transfer time of the ONU software in the downstream direction and the transfer band.

  The transfer time and transfer band of ONU software in the OAM layer generally follow the following theoretical value calculation model. First, various parameters will be described.

  The total number of frames to be transmitted (unit: frames) T can be defined by rounding up the data size of ONU software, which is downlink transfer data, divided by the data length per OAM frame to an integer value.

  The OAM transmission frame limit number (unit: frames / second) M is the upper limit transmission permission number of downlink OAM frames per second. In the first embodiment, this transmission frame limit number M is determined. Here, the parameter M1 is a limit number of downlink OAM transmission frames for one second, and is different from the parameter M in that the unit is a frame.

  The number of transmission frames (unit: frames / second) S is the number of transmittable downlink OAM frames per second. In the case of the first embodiment, every time the OLT 10 sends one OAM frame to the ONU, the ONU returns an ACK to the OLT 10, and the OLT 10 transmits the next OAM frame in response to this reply. (See FIG. 3 to be described later). Therefore, the number S of transmission frames takes a value corresponding to the number of ACKs that can be transmitted (= 1 second ÷ DBA cycle). That is, since uplink frame transmission is possible at every DBA cycle, downlink frame transmission timing synchronized with uplink ACK reception also depends on the DBA cycle. Therefore, the number S of downlink OAM frames that can be transmitted per second depends on the number of uplink ACK that can be transmitted per second. Here, the parameter S1 is the number of downlink OAM frames transmitted per second, and is different from the parameter S in that the unit is a frame.

  Note that the number of transmission frames S is the number of downlink OAM frames that can be transmitted, which is determined by the DBA cycle, and therefore may be larger than the transmission frame limit number M.

  The transfer time of ONU software can be expressed by equation (1) or equation (2). The transfer band of the ONU software can be expressed by equations (3) to (6). Since the number of bits of one frame in equations (3) to (6) is the number of bits of one OAM frame, it is the sum of the number of bits of payload (data portion) and the number of bits of overhead. Also, in equation (1), T is divided by M because the number of transmission frames S, which is the number of transmittable downlink OAM frames per second, exceeds the OAM transmission frame limit number M. This is because the frame limit number M is limited.

When S> M Transfer time (seconds) = integer part of (T / M) + (remainder of (T / M1)) / S (1)
When S ≦ M Transfer time (seconds) = T / S (2)
When S> M and T> M1, transfer band (bps) = M × (number of bits in one frame) (3)
When S> M and T ≦ M1, transfer bandwidth (bps) = (T × (number of bits in one frame)) / 1 second (4)
When S ≦ M and T> S1, transfer band (bps) = S × (number of bits in one frame) (5)
When S ≦ M and T ≦ S1, transfer band (bps) = (T × (number of bits in one frame)) / 1 second (6)
Now, data transfer on the OAM layer is modeled as shown in FIG. That is, the ONU software is divided into 512-byte lengths, an overhead is added to generate a 550-byte-long OAM frame and transferred from the OLT 10 to the ONU 20, and the ONU 20 receives 64 bytes each time it receives a downstream OAM frame. It is assumed that a long ACK frame is returned to the OLT 10.

  In this case, the total number of frames T is a value obtained by rounding up the ONU software data size divided by 512 bytes to an integer value. The number S of transmission frames is 1 frame × (1 / DBA cycle). The number of bits in one frame is 550 bytes × 8 bits = 4400 bits.

  The model of FIG. 3 is applied, and the number M of downlink transmission frames per second, the transfer time applying Formula (1) or (2), and any one of Formulas (3) to (6) are applied. When the relationship with the transfer band is calculated and graphed, it is as shown in FIGS. Here, since the transmission timing of the uplink frame is determined by the DBA cycle, the DBA cycle is used as a parameter, and the DBA cycle is 700 μsec (FIG. 4), the DBA cycle is 1400 μsec (FIG. 5), and the DBA cycle is The case of 2100 μsec (FIG. 6) is calculated. The ONU software data size is calculated for four patterns of 200 kilobytes, 500 kilobytes, 700 kilobytes, and 1000 kilobytes.

  4 to 6, it can be seen that the transfer time and the transfer band converge at a certain level or more even if the transmission frame limit number M per second is increased. This seems to be because, as the transmission frame limit number M per second increases, the number of uplink ACK transmissions is limited depending on the DBA cycle above a certain level. In this state, the downlink occupied band (transfer band) at the time of data transfer for the corresponding DBA cycle takes the maximum value.

  Focusing on the above characteristics, it is possible to determine the OAM transmission frame limit number M that efficiently uses the downlink transfer band with respect to the downlink transfer time. That is, paying attention to the point (value of the transmission frame limit number M) at which the transfer time converges at a predetermined time (for example, about several seconds), the transmission frame limit number M is set at this point and the use of the forward transfer band By suppressing this, it is possible to efficiently use the downstream transfer band with respect to the transfer time, rather than realizing the minimum transfer time without limiting the number of OAM frames.

  For example, when the DBA cycle is 700 μs and the data size is 700 kilobytes, the transmission frame limit number M is set around 300 frames per second. Comparing the case of such setting with the case where the transmission frame limit number M is not set, in both cases, the data transfer time is almost the same level of time sense, whereas the downlink transfer band (occupation) In the case where the transmission frame limit number M is set around 300 frames per second, the case where the transmission frame limit number is not set is about ¼.

  In accordance with the above concept, the transmission frame limit number M may be determined in step 103 of FIG. 2 described above. The specific determination method is not limited as long as the above concept is followed, but two specific determination methods are given below.

  FIG. 7 is a flowchart illustrating an example of a method of determining the transmission frame limit number M. When the processing shown in FIG. 7 is started, the OAM layer processing unit 11 first sets the transmission frame limit number M to 1500 frames, and applies the total number of frames grasped in step 101, the DBA period captured in step 102, and the like. The transfer time when the transmission frame limit number M is 1500 frames is calculated and held as the reference transfer time TREF (step 150). Here, the transfer time when the transmission frame limit number M is not set is approximated by the transfer time when the transmission frame limit number M is 1500 frames.

  Next, the OAM layer processing unit 11 sets the parameter m to an initial value (for example, 10) (step 151).

  Then, assuming that the number of m frames per second is set to the transmission frame limit number M, the transfer time Tm at that time is calculated (step 152), and the obtained transfer time Tm is set to the upper limit value TUP (for example, 10 UP) of the allowable transfer time. Seconds) (step 153).

  If the obtained transfer time Tm exceeds the upper limit value TUP of the allowable transfer time, the OAM layer processing unit 11 increments the parameter m by 1 (step 154), and returns to step 152 described above. Here, the case where the parameter m is increased by 1 has been shown. However, the transmission frame limit number M may be increased by 2 so that the transmission frame limit number M can be determined quickly. You may make it a value.

  If the obtained transfer time Tm is equal to or less than the upper limit value TUP of the allowable transfer time, the OAM layer processing unit 11 obtains the ratio of the obtained transfer time Tm to the reference transfer time TREF (step 155), and the obtained ratio Is less than or equal to a threshold value (for example, 1.2) (step 156). This determination means determination of whether or not the convergence state has been reached. For this determination, a difference may be used instead of a ratio.

  If the obtained ratio exceeds the threshold value, the OAM layer processing unit 11 proceeds to Step 154 and switches the candidate value m for the transmission frame limit number M. On the other hand, if the obtained ratio is less than or equal to the threshold value, the OAM layer processing unit 11 determines the number of m frames per second as the transmission frame limit number M (step 157) and returns to the main routine (FIG. 2). .

  FIG. 8 is an explanatory diagram of a second example of a specific determination method for determining the transmission frame limit number M. In this second example, the range that the total number of frames (or data size) can take is divided into a plurality of partial ranges, and the range that the DBA cycle can take is divided into a plurality of partial ranges, for each combination of both partial ranges. The value of the transmission frame limit number M is determined in advance. FIG. 8 shows the value of the transmission frame limit number M determined in advance for each combination of both partial ranges.

  Recognize the partial range to which the total number of frames related to the ONU software to be transferred belongs and the partial range to which the DBA period determined to be applied at present belongs, and the transmission frame limit determined by the combination of the two recognized partial ranges The value of the number M is taken out and set as the transmission frame limit number M.

(A-3) Effect of First Embodiment According to the first embodiment, the OAM transmission frame limit number that converges the data transfer time within a predetermined time (about several seconds) is applied to the OAM layer of the OLT 10. Therefore, at the time of transferring a group of OAM layer data, it is possible to effectively balance the reduction of the transfer time and the suppression of the downlink line bandwidth (transfer bandwidth).

(B) Second Embodiment Next, a second embodiment of the master station apparatus, the communication system and the downlink data transfer control method according to the present invention will be described with reference to the drawings. The communication system of the second embodiment is also a PON system, and the master station device of the second embodiment is also an OLT.

  The OLT of the second embodiment applies the downlink transmission frame limit number in the downlink transfer of user data (main signal) as in the first embodiment, and uses both the transfer time and transfer band instead of a fixed value. It was decided to take into account.

  FIG. 9 is a block diagram illustrating a functional configuration of the OLT 10A according to the second embodiment. In FIG. 9, the OLT 10 </ b> A of the second embodiment includes an identification information extraction unit 21, a traffic identification unit 22, a corresponding data transfer model search unit 23, and a downlink transmission frame limit number database 24.

  The identification information extraction unit 21 extracts information for identifying a traffic pattern from the conduction data of traffic from the host device of the OLT 10A to the ONU (may be main signal traffic), and the traffic identification unit 22 It is something to give to. The traffic identification unit 22 identifies a traffic pattern based on information from the identification information extraction unit 21. Examples of the traffic pattern identification method include a method of identifying a traffic pattern by applying a service class distribution logic and a method of identifying and identifying traffic information based on a TCP port number.

  The corresponding data transfer model search unit 23 specifies a data transfer model (see FIG. 10 to be described later) corresponding to (corresponding to) the traffic pattern identified by the traffic identification unit 22, and uses the identified data transfer model as a key to transmit a downlink transmission frame. The limit number database 24 is searched.

  The downlink transmission frame limit number database 24 stores information on the transmission frame limit number for each data transfer model. Here, the transmission frame limit number does not correspond to the data transfer model on a one-to-one basis. For example, a plurality of transmission frame limit numbers are stored for one data transfer model, A transmission frame limit number corresponding to parameters (for example, data size and DBA cycle) related to communication can be extracted (see FIG. 8).

  In the first embodiment described above, the traffic model shown in FIG. 3 in which the transfer of ONU software on the OAM layer is modeled is applied. In the second embodiment, a generalized traffic model as shown in FIG. 10 is applied. The traffic model shown in FIG. 10 is a model in which an ACK frame having a Fa byte is returned from the ONU after N frames are continuously transmitted to the ONU with a payload of Fs bytes and an overhead added to the Fos. is there. A data transfer model is obtained by applying specific values to the various parameters N, Fs, Fos, and Fa in FIG.

  When the traffic model of FIG. 10 is applied, the parameters of this model are expressed as follows.

  The total number of frames to be transmitted (unit: frame) T can be defined by rounding up the total size (data size) of downlink transfer data by the data length Fs bytes per frame to an integer value. The number of transmission frames (unit: frames / second) S, which is the number of downlink frames that can be transmitted per second, is defined by N frames × (1 / DBA period). Furthermore, the number of bits in one frame is Fos bytes × 8 bits.

  In the case of the second embodiment, the value of the parameter to be applied is different compared to the first embodiment, but in the case where the value of the transmission frame limit number M is increased as in the first embodiment. The point at which the transfer time converges at a predetermined time (for example, about several seconds) is grasped, and the value of the transmission frame limit number M at this point is determined for each combination of data size and DBA cycle, and the downlink transmission frame limit number database 24. (See FIG. 8). Instead of extracting from the downlink transmission frame limit number database 24, the value of the convergence frame transmission frame limit number M may be searched as described with reference to FIG. In this case, the increment unit of the candidate value is preferably a multiple of N frames, for example. In addition, when there is traffic with the same data size and DBA cycle at any transfer time, the transmission frame limit number may be associated with the data transfer model on a one-to-one basis.

  When traffic from the host device of the OLT 10A to the ONU is newly generated, information for identifying the traffic pattern is extracted from the new traffic continuity data by the identification information extracting unit 21 of the OLT 10A, and the traffic identifying unit 22 A traffic pattern is identified. In the corresponding data transfer model search unit 23, a data transfer model corresponding to (corresponding to) the traffic pattern identified by the traffic identifying unit 22 is specified, and the downlink transmission frame limit number database 24 is stored using the specified data transfer model as a key. Accessed and the number of downlink transmission frames limited according to the data size and DBA period related to the new traffic is extracted. Then, the transfer of new traffic from the OLT 10A to the ONU is executed under the limit of the extracted transmission frame limit number.

  According to the second embodiment, the data transfer model of the traffic to be controlled is defined and the upper limit of the number of downlink frames transmitted per second is determined. Therefore, the efficient downlink for the downlink data transfer rate for each traffic is determined. A transfer band (allocated band) can be determined.

(C) Other Embodiments In the second embodiment, the OLT 10A identifies the traffic pattern. However, in the grasping of traffic information (traffic identification) by the service class sorting logic and the TCP port number as described above, The identification result by a device other than the OLT may be notified to the OLT. For example, the ONU that actually terminates the negotiation protocol identifies the traffic, notifies the OLT of traffic information, and the OLT determines the applicable number of downlink transmission frames for the traffic class and applies it. You may make it do.

  In each of the above embodiments, the case where the present invention is applied to the PON system has been described. However, the present invention can be applied to any one-to-many communication system having the same configuration as the PON system. For example, the present invention can be applied to a communication system in which a communication signal passing through a transmission path is not an optical signal but an electrical signal, and the transmission path is not an optical fiber but a space through which light passes. The present invention can also be applied.

  10, 10A ... OLT, 11 ... OAM layer processing unit, 12 ... OAM frame generation unit, 13 ... main signal frame generation unit, 14 ... transmission frame multiplexing unit, 15 ... reception frame demultiplexing unit, 16 ... OAM frame termination unit, 17 ... main signal frame termination unit, 21 ... identification information extraction unit, 22 ... traffic identification unit, 23 ... corresponding data transfer model search unit, 24 ... downlink transmission frame limit number database.

Claims (5)

The slave station device that transmits data in units of frames to the slave station device of any of the plurality of slave station devices via the relay device and continuously receives a predetermined number of the frames. Corresponds to the master station device of the communication system that returns a reception response frame to the master station device via the relay device according to a dynamic bandwidth allocation period determined by a method in which the master station device dynamically allocates a bandwidth. In the master station device to
The total size of data transferred from the master station device to the slave station device, the dynamic bandwidth allocation period, and the amount of data included in one frame are set to at least fixed values, and the master station device to the slave station While changing the upper limit number of frames per unit time allowed to be transferred to the device, the transfer time for transferring the entire data to be transferred is calculated for each value of the upper limit frame number, and the upper limit frame number is increased from a smaller value to a larger value. When the value is changed to a value, the upper limit frame number per predetermined time of the change point at which the calculated transfer time is considered to have converged is obtained, and the upper limit frame number per predetermined time of the change point is determined by the master station device. A master station device comprising a limit setting unit that sets a limit when data is transferred from the own device to the slave station device. The restriction setting unit, according to the traffic coming forward, the size of the entire, the dynamic bandwidth assignment period and, based on the amount of data to include per one frame, the transfer start immediately before a predetermined time of change points The master station apparatus according to claim 1, wherein a search operation is performed for the upper limit number of frames per hit.   The limit setting unit has a built-in storage unit that stores the upper limit number of frames per predetermined time of change points calculated in advance for each type of traffic, detects the type of traffic to be transferred from now on, The master station apparatus according to claim 1, wherein an upper limit number of frames to be applied is grasped. The slave station device that transmits data in units of frames to the slave station device of any of the plurality of slave station devices via the relay device and continuously receives a predetermined number of the frames. However, in the communication system for returning the reception response frame to the master station device via the relay device according to the dynamic bandwidth allocation period determined by the master station device dynamically allocating the bandwidth,
A communication system, wherein the parent station device is the parent station device according to claim 1. The slave station device that transmits data in units of frames to the slave station device of any of the plurality of slave station devices via the relay device and continuously receives a predetermined number of the frames. In the downlink data transfer control method of the communication system, the reception response frame is returned to the master station device via the relay device according to the dynamic bandwidth allocation period determined by the master station device dynamically allocating the bandwidth. ,
The master station device sets at least a fixed value to the total size of data transferred from the own device to the slave station device, the dynamic band allocation period, and the amount of data included in one frame. While changing the upper limit number of frames per predetermined time allowed to be transferred to the slave station device, the transfer time for transferring the entire data to be transferred is calculated for each value of the upper limit frame number, and the upper limit frame number is set to a small value. When the value is changed from 1 to a large value, the upper limit frame number per predetermined time of the change point at which the calculated transfer time is considered to have converged is obtained, and the upper limit frame number per predetermined time of the change point is determined from the own device. A downlink data transfer control method, wherein a restriction is set when transferring data to the slave station device.

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