JP4489663B2 - COMMUNICATION CONTROL DEVICE, COMMUNICATION CONTROL METHOD, COMMUNICATION CONTROL PROGRAM, AND ITS RECORDING MEDIUM - Google Patents

Description

  The present invention is a network for transmitting data using a communication medium in which a transmission band (transmission time band) is ensured by time division, and a device on the transmission side confirms the response of the transmitted data on the device on the reception side. The present invention relates to a communication control apparatus, a communication control method, a communication control program, and a recording medium for controlling a transmission band in a communication medium in a network that transmits next data after receiving from the network.

  2. Description of the Related Art In recent years, techniques related to home networks that connect home devices to each other using IP (Internet Protocol) have been actively developed.

  In the home network, it is assumed that various types of data are exchanged in the same manner as in the Internet, but in particular, a technique related to real-time transmission of moving images, audio data, and the like has attracted attention.

  In transmission using IP (Internet Protocol), transmission using TCP (Transport Control Protocol) or transmission using UDP (User Datagram Protocol) is generally used. On the Internet, TCP is used for a wide range of applications because of the advantage of ensuring reliability. Against this background, development related to transmission using TCP is also actively performed in real-time transmission in the home.

  In TCP, the reliability of communication is ensured by using a positive acknowledgment (acknowledgment) called ACK (Acknowledgment), but the next data cannot be transmitted until the ACK of the previous data is received. Then, transmission efficiency deteriorates. Therefore, for example, as described in Non-Patent Document 1, transmission efficiency is increased by using a method called a sliding window.

  On the other hand, methods such as PLC (Power Line Communication) and IEEE 802.11e, which are transmission methods using a power line, have been proposed as communication media constituting a home network. In these systems, QoS (Quality of Service) technology is incorporated on the assumption that real-time data is transmitted in the home.

  Since real-time data is processed sequentially, it is required to transmit while maintaining a certain transmission rate. Therefore, QoS technology solves the problem of lowering the transmission rate due to competition with other streams during real-time data transmission by securing the necessary transmission bandwidth on each communication medium and performing transmission. is doing.

In the QoS technique, TDMA (Time Division Multiple Access) is generally used as a method for securing a transmission band (see Non-Patent Document 2). This is a method of securing a transmission band by dividing a transmission path according to time and transmitting only predetermined data in each section. FIG. 25 is a diagram illustrating a state of a transmission line that is time-division controlled by TDMA control. In FIG. 25, one transmission path is divided into three sections, and each divided section is assigned as the transmission time of each stream (Stream A, B, C), thereby ensuring the necessary transmission time for each stream. is doing.
Philip Miller, translated by Yukio Hamada, “Mastering TCP / IP Application”, Ohm, 1st Edition, p.124-131 “IT Glossary of Terms e-words”, [online], Incept, Inc. [searched on July 20, 2005], Internet <URL: http://e-words.jp/w/IEEE20802.11e.html>

  However, when a sliding window is used as in Patent Document 1, if RTT (Round Trip Time) is larger than Window Size, a problem called Long Fat Pipe occurs, and throughput is inevitably increased. descend.

  This problem will be described in more detail. FIG. 26 is an explanatory diagram showing the relationship between window size and RTT and throughput. As shown in this figure, there is no particular problem when the RTT is small, or when the RTT is large and the window size is as large as that, but when the RTT is large relative to the window size, the so-called Long Fat Pipe This causes a problem called “transmission rate” and the transmission rate decreases.

When the window size is W (bits), the round trip transmission delay is RTT (seconds), and the transmission capability of the transmission path is r (bits / second), the transmission rate R (bits / second) obtained is
R = min (r, W / RTT)
It can be expressed as. Note that min (x, y) represents the smaller value of x and y.

  Therefore, when r> (W / RTT), the transmission capability of the transmission path cannot be fully utilized, and the transmission rate is lowered.

  In addition, in the configuration in which data is transmitted in real time by TCP using TDMA, there is a problem that the transmission rate is lowered when the period of the transmission period is too long. FIG. 27 is an explanatory diagram showing an example of a transmission state when data is transmitted in real time by TCP using TDMA.

  In the example shown in this figure, one system is time-divided into a downlink section and an uplink section, and data transmission of one stream is transmitted in the downlink section, and TCP ACK for stream data is transmitted in the uplink section.

  If the amount of data that can be transmitted in each downlink section is larger than the TCP window size, the transmission is interrupted when transmission for the window size is performed without using all the capacity of the transmission path. The ACK for the transmitted data cannot be returned immediately, but is waited until the next uplink transmission time allocation. Eventually, the amount of data that can be transmitted during the period T is the data for the Window Size. If the size of the Window Size is W, the transmission rate R is R = W / T. Therefore, if the period T is too large, the transmission rate required for real-time transmission cannot be secured.

  In addition, when QoS control by TDMA is performed on a network composed of a plurality of systems (communication media) and real-time transmission is performed by TCP on the path, transmission delay further occurs at the connection between the systems. There is. An example of such a case will be described with reference to FIGS.

  FIG. 28 is an explanatory diagram illustrating an example of a network including a plurality of systems. The network shown in this figure includes a transmitter 101, a relay device 102, a relay device 103, and a receiver 104. The transmitter 101 and the relay apparatus 102 are connected by a communication medium A (for example, wireless LAN (802.11e)), and the relay apparatus 102 and the relay apparatus 103 are connected by a communication medium C (for example, PLC). The relay apparatus 103 and the receiver 104 are connected by a communication medium B (for example, a wireless LAN (802.11e)). In this network, QoS control by TDMA is performed on each of the communication media A to C, and real-time transmission by TCP is performed on the route.

FIG. 29 is an explanatory diagram showing a state of data transmission in this network. In the example shown in this figure, for the sake of simplicity, it is assumed that no transmission delay occurs in the communication medium C (between the relay device 102 and the relay device 103).

  In the example shown in this figure, when data is transmitted from the transmitter 101 to the relay apparatus 102 via the communication medium A, and the data is transmitted from the relay apparatus 102 to the relay apparatus 103, the communication medium B is in the upstream section. ing. For this reason, the relay apparatus 103 transmits the data to the receiver 104 after waiting until the communication medium B enters the downstream section.

  The receiver 104 that has received this data needs to return an ACK, but when the data is received, the communication medium B is in the downstream section, so the ACK is transmitted after waiting for the upstream section.

  Furthermore, when the ACK is transmitted from the receiver 104 to the relay apparatus 103 via the communication medium B and the ACK is transmitted from the relay apparatus 103 to the relay apparatus 102, the communication medium A is in the downstream section. For this reason, the relay apparatus 102 transmits the above ACK to the transmitter 101 after waiting until the communication medium A enters the upstream section.

  For this reason, even when a communication medium that can obtain a necessary transmission rate by appropriately setting T when used alone is used as the communication medium A to C, there is a delay between the transmitter 101 and the receiver 104. Will increase, causing the problem of Long Fat Pipe, resulting in a problem that the required transmission rate cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object of the present invention is a network that transmits data using a communication medium in which a transmission band is secured by time division, and a transmission-side apparatus includes: In the network in which the next data is transmitted after the response confirmation of the transmitted data is received from the receiving device, the transmission rate is prevented from decreasing.

  In order to solve the above problems, the communication control apparatus of the present invention is a network that transmits data between a transmission apparatus and a reception apparatus via a plurality of communication media whose transmission time zones are controlled by time division. The transmission device is provided in a network capable of transmitting next data after receiving a response confirmation for the data after transmitting data to the reception device, and time-sharing each of the communication media. A communication control device that causes a control device that performs control to perform time-sharing control based on a schedule specified by the control device, wherein the transmission device transmits data to the reception device and receives a response confirmation for the data The transmission time zones in each of the communication media are allocated to each other so that the round-trip delay time, which is the time until the time, becomes a predetermined time at which a necessary transmission rate can be obtained. Association with the is characterized in that it comprises a control means for setting the schedule.

  According to the above configuration, the control means sets the schedule by associating the allocation of the transmission time zones in each communication medium with each other so that the round-trip delay time is set to a time at which a necessary transmission rate can be obtained. Therefore, by causing the control device to perform time-sharing control of each communication medium based on the schedule set in this way, even in a network that performs communication via a plurality of communication media, a response that occurs on the communication path It is possible to prevent the transmission rate from being lowered due to the arrival delay of the confirmation.

  In addition, the communication control apparatus of this invention may be provided integrally with the said control apparatus. In this case, the control device may be a relay device that relays at least two of the communication media. According to any of the above configurations, the configuration of the network can be simplified.

  In addition, the control unit transmits, in each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device, and a response confirmation for the data transmitted from the reception device. A second time allocation that can be transmitted in the direction of at least once every predetermined time, and the end time of the first time allocation in each communication medium matches, It is good also as a structure which sets the said schedule so that the start time of 2nd time allocation may correspond.

  According to the above configuration, the data transmitted from the transmission device passes through each communication medium without waiting time and is received by the reception device. Similarly, the response confirmation for the data transmitted from the receiving apparatus is received by the transmitting apparatus after passing through each communication medium without waiting time. Therefore, a response confirmation for the data arrives at the transmitting device within a predetermined time after the data is transmitted from the transmitting device. Thereby, since the round trip delay time for the response confirmation becomes equal to or shorter than the predetermined time, it is possible to prevent the transmission rate from being lowered as the response confirmation delay increases.

  Further, in this case, the control means matches the start time of the first time allocation in each communication medium and matches the end time of the second time allocation in each communication medium. It is good also as a structure which sets the said schedule.

  According to said structure, the length of the 1st time allocation in each communication medium becomes the same, and the length of the 2nd time allocation in each communication medium becomes the same. For this reason, particularly efficient time allocation can be performed when the communication capability (data amount that can be transmitted per unit time) of each communication medium is equal.

  In addition, the control unit sequentially delays the start time of the first time allocation in each communication medium from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, The schedule is set so that the end time of the second time allocation in each communication medium is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. Also good.

  According to said structure, since the round trip delay time of a response confirmation can be made into predetermined time or less, it can prevent that a transmission rate falls with the increase in the delay of a response confirmation. In this case, the lengths of the first time allocation and the second time allocation in each communication medium are sequentially shortened from the transmitting apparatus side to the receiving apparatus side. Therefore, particularly efficient time allocation can be performed when the communication capability (the amount of data that can be transmitted per unit time) of each communication medium gradually increases from the transmitting apparatus side to the receiving apparatus side.

  In addition, the control unit transmits, in each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device, and a response confirmation for the data transmitted from the reception device. A second time allocation that can be transmitted in the direction of at least once every predetermined time, and a start time of the first time allocation in each communication medium matches, It is good also as a structure which sets the said schedule so that the end time of 2nd time allocation may correspond.

  According to said structure, the response confirmation about the data arrives at a transmission device within predetermined time after sending data from a transmission device. Thereby, it is possible to prevent a decrease in transmission rate due to a delay in response confirmation.

  For example, the control unit sequentially delays the end time of the first time allocation in each communication medium from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side. The schedule is set so that the start time of the second time allocation in each communication medium is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. Also good. In this case, the lengths of the first time allocation and the second time allocation in each communication medium are sequentially increased from the transmitting apparatus side to the receiving apparatus side. Therefore, particularly efficient time allocation can be performed when the communication capability (the amount of data that can be transmitted per unit time) of each communication medium decreases sequentially from the transmitting device side toward the receiving device side.

  Further, the control means transmits a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device in the direction of the transmission device. A second time allocation that can be performed at least once every predetermined time, and in each communication medium, the start time of the first time allocation is arranged on the transmission device side From the communication medium arranged on the transmission apparatus side to the communication medium arranged on the reception apparatus side from the communication medium arranged on the transmission apparatus side. The start time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side, and the end time of the second time assignment is received. apparatus So successively slower toward the communication medium disposed on the transmitting apparatus side from the communication medium disposed on, may be configured to set the schedule.

  According to said structure, the response confirmation about the data arrives at a transmission device within predetermined time after sending data from a transmission device. Thereby, since the round trip delay time for the response confirmation becomes equal to or shorter than the predetermined time, it is possible to prevent the transmission rate from being lowered as the response confirmation delay increases.

  Further, the control means varies a period of transmission time zone allocation in each communication medium for each communication medium, and transmits the data in the direction from the transmitting apparatus to the receiving apparatus in each communication medium. And a second time allocation capable of transmitting a response confirmation for the data from the receiving device to the transmitting device at least once every predetermined time, and in each of the communication media Set the schedule so that the end time of the first time allocation matches at least once every predetermined time, and the start time of the second time allocation matches at least once every predetermined time It is good also as composition to do.

  According to said structure, even if it is a case where the period of transmission time slot | zone allocation in each communication medium differs for every communication medium, the end time of 1st time allocation and 2nd at least once for every predetermined time. The time allocation start time is synchronized in each communication medium. Therefore, a response confirmation for the data arrives at the transmitting device within a predetermined time after the data is transmitted from the transmitting device. Thereby, since the round trip delay time for the response confirmation becomes equal to or shorter than the predetermined time, it is possible to prevent the transmission rate from being lowered as the response confirmation delay increases.

  For example, in the control unit, the transmission time zone allocation period in each communication medium is sequentially 1 / m times (m from the communication medium arranged on the transmitting apparatus side to the communication medium arranged on the receiving apparatus side. The above schedule may be set so that is a natural number. In this case, for example, in a network in which the transmission capability of each communication medium is gradually increased from the transmission apparatus side to the reception apparatus side, the transmission time slot allocation period is decreased in order from the communication medium on the transmission apparatus side. Thus, each communication medium can be used effectively.

  Alternatively, the control means sequentially assigns the transmission time zone allocation period in each communication medium to n times (n is a natural number) from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side. ) So that the schedule is set. In this case, for example, in a network in which the transmission capability of each communication medium is gradually decreasing from the transmitting apparatus side to the receiving apparatus side, the transmission time slot allocation period increases in order from the communication medium on the transmitting apparatus side. Thus, each communication medium can be used effectively.

  Further, the control means varies a transmission time slot allocation period in each communication medium for each communication medium, and transmits data transmitted from the transmission device in the direction of the reception device in each communication medium. And a second time allocation capable of transmitting a response confirmation for the data transmitted from the receiving device in the direction of the transmitting device at least once for each predetermined time, and In each of the communication media, the start time of the first time allocation is sequentially delayed from the communication medium arranged on the transmitting device side toward the communication medium arranged on the receiving device side. The end time is sequentially delayed from the communication medium arranged on the transmission device side to the communication medium arranged on the reception device side, and the start time of the second time allocation is from the communication medium arranged on the reception device side. The end time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving apparatus side toward the communication medium arranged on the transmitting apparatus side. It is good also as a structure which sets the said schedule so that it may become.

  According to said structure, the response confirmation about the data arrives at a transmission device within predetermined time after sending data from a transmission device. Thereby, since the round trip delay time for the response confirmation becomes equal to or shorter than the predetermined time, it is possible to prevent the transmission rate from being lowered as the response confirmation delay increases.

  Further, the control means may be configured to set the schedule so that the first time allocation and the second time allocation are provided once for each predetermined time in each communication medium. .

  According to the above configuration, it is possible to perform efficient allocation without performing extra allocation in a communication medium in which the transmission time period allocation cycle is shorter than other communication media.

  In addition, the control unit transmits, in each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device, and a response confirmation for the data transmitted from the reception device. The schedule may be set so that the second time allocation that can be transmitted in the direction is provided a plurality of times for each predetermined time.

  Thereby, the amount of data that can be transmitted within the predetermined time can be increased, and the transmission rate can be improved.

  The control means may be configured to set the schedule so that the second time allocation in each communication medium is a transmission time zone in which only information transmitted from the receiving device can be transmitted. .

  According to said structure, in each communication medium, the transmission time slot | zone which transmits the response confirmation from a receiver to a transmitter can be ensured reliably.

  In addition, the control means allocates the second time allocation in each communication medium, not only the information transmitted from the receiving apparatus, but also information transmitted from another apparatus that performs communication via the communication medium. Alternatively, the schedule may be set so that the transmission time zone can be transmitted.

  In general, the data amount of response confirmation is very small with respect to the data amount of data (stream) transmitted from the transmission device to the reception device. Therefore, in the above configuration, the second time allocation for transmitting the response confirmation is a shared section (transmission time shared with other devices) in which information (such as other streams) transmitted from other devices can also be transmitted. Obi). Thereby, a communication medium can be used more effectively.

  In addition, it includes availability determination means for determining whether or not the schedule can be set so that the round-trip delay time is a time at which a necessary transmission rate can be obtained, and the control means includes the round-trip delay time. For the schedule that can be executed in the network, and the time division control period in each communication medium, and the first The round trip time is calculated based on the start time and end time of the second time assignment and the start time and end time of the second time assignment, and based on the calculated round trip time and the necessary transmission rate. In order to realize the transmission rate, the transmission device calculates the amount of data to be transmitted at one time and transmits the transmission The amount of data location can send at once, it may be configured to be set on the basis of the data amount calculated above. Here, the data amount that can be transmitted by the transmitting device at a time is the amount of data that the transmitting device can transmit without waiting for response confirmation.

  According to the above configuration, even if the schedule cannot be set so that the round-trip delay time is a time at which a necessary transmission rate can be obtained, the transmission is performed in order to realize the necessary transmission rate. By calculating the amount of data that the device should transmit at one time and setting the amount of data that the transmitting device can transmit at one time based on the calculated amount of data, the transmission amount per unit time is increased and the required transmission bandwidth Can be secured.

  Moreover, the communication control apparatus of this invention is good also as a structure provided with the synchronization means which synchronizes the time of the said several control apparatus with which the said network is equipped.

  According to said structure, the time of each control apparatus can be synchronized and time division control of each communication medium can be performed appropriately.

  The communication control device of the present invention may be configured to cause the control device provided in a network that performs communication using TCP (Transport Control Protocol) to perform time-sharing control based on a schedule designated by the communication control device. . In this case, communication can be performed using an existing transport protocol.

  In order to solve the above problems, the communication control device of the present invention is a network for transmitting data between a transmission device and a reception device via a communication medium whose transmission time zone is controlled by time division. The transmission device is provided in a network capable of transmitting next data after receiving a response confirmation for the data after transmitting data to the reception device, and performing time-sharing control of each communication medium. A communication control device that causes a control device to perform time-division control based on a schedule designated by itself, from the time when the transmission device transmits data to the reception device until a response confirmation for the data is received Control means for setting the schedule such that the round-trip delay time, which is the time, becomes a predetermined time at which a necessary transmission rate can be obtained, The means transmits, in each communication medium, a first time allocation for transmitting data transmitted from the transmitting device in the direction of the receiving device and a response confirmation for the data transmitted from the receiving device in the direction of the transmitting device. The schedule is set so that the second time allocation that can be performed is provided a plurality of times for each predetermined time.

  According to said structure, the data amount which can be transmitted within the said predetermined time can be increased, and a transmission rate can be improved.

  In order to solve the above problems, the communication control method of the present invention is a network that transmits data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division. The transmission device is provided in a network capable of transmitting next data after receiving a response confirmation for the data after transmitting data to the reception device, and time-sharing each of the communication media. A communication control method for causing a control device that performs control to perform time-division control, wherein the round-trip delay time is a time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data Is based on a schedule that correlates the allocation of transmission time zones in each of the communication media so that a predetermined time can be obtained. It is characterized by controlling the serial controller.

  According to the above method, even in a network that performs communication via a plurality of communication media, it is possible to prevent a decrease in transmission rate due to a delay in arrival of a response confirmation that occurs on a communication path.

  The communication control device may be realized by a computer. In this case, a communication control program for causing the communication control device to be realized by a computer by operating the computer as the control means, and recording the program. Such computer-readable recording media are also included in the scope of the present invention.

  As described above, the communication control device of the present invention has a transmission rate that requires a round trip delay time, which is a time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data. Control means for setting the schedule by associating the transmission time zone assignments in the communication media with each other so as to obtain a predetermined time that can be obtained.

  Therefore, by causing the control device to perform time-sharing control of each communication medium based on the schedule set as described above, even if the network communicates via multiple communication media, it occurs on the communication path. It is possible to prevent the transmission rate from being lowered due to the arrival delay of the response confirmation.

  Further, the communication control method of the present invention can obtain a transmission rate that requires a round trip delay time, which is a time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data. The control device is controlled based on a schedule in which transmission time zone assignments in the communication media are associated with each other so that a predetermined time can be reached.

  Therefore, even in a network that performs communication via a plurality of communication media, it is possible to prevent a decrease in transmission rate due to the arrival delay of the response confirmation that occurs on the communication path.

[Embodiment 1]
A network according to an embodiment of the present invention will be described. The network according to the present embodiment is a transmission rate required for real-time transmission when transmission is performed using TCP in a network that performs communication via a plurality of systems (communication media) whose transmission band is secured by TDMA. Is secured between the transmitter and the receiver. Further, in the network according to the present embodiment, the transmitter cannot transmit the next data until it transmits ACK (response confirmation) about the data after transmitting the data. In the present embodiment, an example of transmission using TCP over IP (Internet Protocol) will be described, but the present invention is not limited to this.

  FIG. 1 is a block diagram showing a configuration of a network (present network) according to the present embodiment. As shown in this figure, this network is composed of a transmitter 1, a receiver 2, and a relay device 3.

  The transmitter 1 and the relay device 3 are communicably connected via a system A (for example, a wireless LAN (802.11e or the like)). Further, the relay device 3 and the receiver 2 are communicably connected via a system B (for example, PLC).

  As the transmitter 1 and the receiver 2, various devices having a communication function can be used. For example, a video, hard disk recorder, DVD recorder, digital tuner, or the like can be used as the transmitter 1, and a television (television receiver) can be used as the receiver 2.

  The relay device (control device, control command device) 3 is a device for connecting the system A and the system B to each other and transmitting / receiving data to / from devices connected to each system. (802.11e) and a bridge device provided with a PLC interface. In this network, such a configuration enables real-time data transmission between the transmitter 1 and the receiver 2.

  Both the system A and the system B can secure a transmission band by TDMA, and the relay device 3 performs time division control by TDMA for each of the system A and system B. In this embodiment, different communication media (wireless LAN and PLC) are used for the system A and the system B. However, the present invention is not limited to this, and the same communication medium may be used.

  FIG. 30 is a block diagram illustrating an internal configuration of the relay device 3. The relay device 3 includes a processing unit 3101, a communication unit A 3105, a communication unit B 3106, and a protocol conversion unit 3107.

  The processing unit 3101 includes a communication control unit A 3103, a communication control unit B 3104, and a control unit 3102. The communication control unit A3103 controls the operation of the communication unit A3105, and the communication control unit B3104 controls the operation of the communication unit B3106. Communication control unit A 3103 and communication control unit B 3104 perform time-sharing control of system A and system B, respectively.

  The control unit 3102 includes an initialization determination unit 3111, an initialization request unit 3112, a usage status acquisition unit 3113, a scheduling availability determination unit 3114, and a control request unit 3115.

  The initialization determination unit 3111 determines whether each system has been initialized. The initialization request unit 3112 makes an initialization request for the system A and the system B to the communication control unit A and the communication control unit B when each system is not initialized.

  The usage status acquisition unit 3113 acquires information on the usage status of each system from the communication control unit A 3103 and the communication control unit B 3104. Here, the usage status includes, for example, TDMA period (service interval) of each system, start time of the next period (start time of the next service), information on a period that can be allocated within each period, and the like. The period here is, for example, a transmission interval of a signal called a beacon transmitted from a control device in order to synchronize each device on the system in time division control by TDMA (however, it is limited thereto) is not).

  The scheduling availability determination unit 3114 determines whether scheduling for making the round-trip delay time within a predetermined time during which a necessary transmission rate can be obtained is possible based on the usage status of each system. Details of the scheduling method will be described later.

  When the scheduling availability determination unit 3114 determines that the predetermined scheduling is possible, the control request unit 3115 requests the communication control unit A and the communication control unit B to secure the bandwidth of each system based on the predetermined scheduling. I do. The communication control unit A controls the communication unit A and notifies the transmitter 1 of the schedule so as to perform the time division control of the system A based on the control request from the control request unit 3115. Similarly, the communication control unit B controls the communication unit B and notifies the receiver 2 of the schedule so that the time division control of the system B is performed based on the control request from the control request unit 3115. The transmitter 1 and the receiver 2 communicate with each other at a timing based on the schedule received from the communication control units A and B.

  The processing unit 3101 includes, for example, a processor such as a CPU, and the functions of each member provided in the processing unit 3101 are realized by reading and executing software stored in a ROM (not shown). That is, the processing unit 3101 is a processor that is operated by software (driver software or the like) that performs various control processes. On the processing unit 3101, software (driver software) that performs various controls of the communication unit A 3105 is executed to realize the functions of the communication control unit A 3103, and software that performs various controls of the communication unit B 3106 is executed. Thus, the function of the communication control unit B3104 is realized. Further, information on the usage status is acquired from the communication control unit A 3103 and the communication control unit B 3104, it is determined whether or not a necessary transmission band can be secured, and based on a predetermined scheduling method for securing the transmission band. The function of the control unit 3102 is realized by executing software for making a control request.

  The communication unit A3105 is a communication interface for performing communication in the system A, and is, for example, a wireless LAN card having a wireless LAN (802.11e) function.

  The communication unit B 3106 is a communication interface for performing communication in the system B, and is, for example, an interface card having a PLC function.

  The protocol conversion unit 3107 converts the communication protocol of the system A and the communication protocol of the system B. For example, data transmitted by a wireless LAN (802.11e) protocol is converted into a PLC protocol, and vice versa.

  Next, processing in which the control unit 3102 of the relay apparatus 3 performs time division control using the TDMAs of the system A and the system B will be described. FIG. 31 is a flowchart showing the flow of this process.

  First, the control unit 3102 (initialization determination unit 3111) inquires of the communication control unit A 3103 and the communication control unit B 3104 whether or not the system A and the system B are initialized, and based on the response to the inquiry, It is determined whether A and the system B are initialized (S3201).

If it is determined that the system A and the system B are not initialized, the control unit 3102 (initialization request unit 3112) initializes the systems A and B with respect to the communication control unit A and the communication control unit B. A request is made (S3102, S3103). The initialization request here sets the TDMA cycle, the start time of the first cycle, and the like. For example, it is set so that the cycle Ta of the system A = the cycle Tb of the system B, or Ta = n × Tb or Ta = Tb / n (n is a natural number). In addition, the start time of the first cycle is set to start at the same time, for example. Further, the numerical value of the period is a period necessary when, for example, high-definition content of a maximum of 24 Mbps is transmitted with a normal window size of 64 Kbytes of TCP.
T = 64 × 8 × 10 ^ 3 / (24 × 10 ^ 6) ≈21 × 10 ^ −3 (seconds)
In contrast, each period is set to be smaller than this. However, it is not limited to this.

  When it is determined in S3201 that the system A and the system B have been initialized, or after making an initialization request to the communication control unit A and the communication control unit B in S3202 and S3203, the control unit 3102 (usage status acquisition unit 3113). ) Makes an inquiry about the usage status of each system to the communication control unit A3103 and the communication control unit B3104 (S3204, S3205). Here, the usage status includes, for example, TDMA period (service interval) of each system, start time of the next period (start time of the next service), information on a period that can be allocated within each period, and the like.

  Then, control unit 3102 (scheduling availability determination unit 3114) determines whether or not predetermined scheduling is possible based on the usage situation obtained from the responses from communication control unit A 3103 and communication control unit B 3104 (S3206). . That is, the control unit 3102 (schedulability determination unit 3114) obtains information on the TDMA period of each system, the start time of the next period, and the period that can be allocated within each period, acquired from the communication control unit A 3103 and the communication control unit B 3104. Based on the above, it is determined whether or not a predetermined scheduling for making the round-trip delay time within a predetermined time during which a necessary transmission rate can be obtained is possible. Here, the necessary transmission rate is, for example, a transmission rate that is at least required for reliably performing real-time transmission. The necessary transmission rate may be notified to the control command device 25 by, for example, a device (for example, the transmitter 1 or the receiver 2) requesting to secure a transmission band, or controlled according to the type of data to be transmitted. It may be set by the command device 25. Details of the predetermined scheduling will be described later.

  If it is determined that the predetermined scheduling is possible, the control unit 3102 (control request unit 3115) makes a bandwidth reservation request to the communication control unit A and the communication control unit B (S3207, S3208). The division control process ends.

  On the other hand, if it is determined in S3206 that the predetermined scheduling cannot be performed, the control unit 3102 (schedule availability determination unit 3114) determines that a transmission band necessary for communication cannot be secured, and a bandwidth securing request destination (for example, a user) In response to this, a notification that the band cannot be secured is sent (S3209), and the time-sharing control process is terminated.

  Next, a scheduling method (the predetermined scheduling) will be described. In each schedule example shown below, the time required for a packet to pass through each system and the time required for transmission on the relay device 3 are ignored. When it is necessary to consider these times, the time is not particularly limited. For example, these times may be added to the time allocated to each system.

  Of the scheduling examples shown below, only one preset may be used. In this case, the scheduling availability determination unit 3114 provided in the control unit 3102 determines whether or not the round-trip delay time can be made within a predetermined time during which a necessary transmission rate can be obtained, using a preset scheduling method. Then, if it can be done within a predetermined time, the control request unit 3115 requests the control devices (communication control unit A 3103 and communication control unit B 3104) to time-divide each system based on the scheduling method.

  In addition, the scheduling example that can minimize the round-trip delay time may be selected from the following scheduling examples. In this case, the scheduling availability determination unit 3114 included in the control unit 3102 may perform round-trip processing for each scheduling method. Calculate the delay time. Then, the control request unit 3115 can make the round trip delay time within a predetermined time, and the control device (the communication control unit A 3103 and the communication control) so as to time-divide each system based on a scheduling method that can make the round trip delay time the shortest. Part B3104).

  In addition, priorities are assigned to the following scheduling examples, and a round-trip delay time that is within a predetermined time during which a necessary transmission rate can be obtained is used, and the one with the highest priority is used. Also good. In this case, the scheduling availability determination unit 3114 provided in the control unit 3102 calculates the round trip delay time in order from the highest priority for each scheduling method, and finds a scheduling method that can make the round trip delay time within a predetermined time. Then, the control request unit 3115 requests the control devices (communication control unit A 3103 and communication control unit B 3104) to time-divide each system based on the scheduling method.

(Scheduling example 1)
FIG. 8 is an explanatory diagram showing an example of a scheduling method in the present embodiment. The example shown in this figure is an example in which the TDMA periods T of the system A and the system B match.

  In this schedule example, as shown in FIG. 8, the start time and end time of time allocation in the downlink direction (transmitter 1 → relay device 3 → receiver 2 direction) in system A within each period, and in system B The start time and the end time of the time allocation in the downlink direction are set to coincide with each other (so as to be the same time). In addition, the time allocation start time and end time in the uplink direction (receiver 2 → relay device 3 → transmitter 1 direction) in the system A within each period, and the time allocation start time and end time in the system B in the uplink direction Set to match the time.

  At this time, the downlink allocation time td and the uplink allocation time tu are determined as follows.

If the required transmission rate is R (bits / second), the communication capability of system A is ra (bits / second), and the communication capability of system B is rb (bits / second),
T × R ≦ min (ra × td, rb × td)
Td satisfying the above condition is set as the allocation time in the downlink direction. Thus, for example, when ra = rb,
td ≧ T × R / ra
It becomes.

Also, if one TCP packet size is S and one ACK packet size is s,
T × R / S × s ≦ min (ra × tu, rb × tu)
The tu that satisfies the above condition is set as the uplink allocation time.

Therefore, when ra = rb,
tu ≧ (T × R / ra) × s / S
It becomes.

  According to this example schedule, the data passing through the system A passes through the system B without any waiting time at the relay device 3. Similarly, the ACK for the data passes through the system A without any waiting time at the relay device 3 after passing through the system B. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  Further, in the present schedule example, the allocation time to the system B and the allocation time to the system A are the same. Therefore, it can be said that the time allocation is particularly efficient when the communication capability rb of the system B and the communication capability ra of the system A are rb = ra.

When the receiver 2 performs a so-called block ACK in which one ACK is returned for a plurality of TCP packets (when one ACK is returned for m TCP packets),
tu ≧ (T × R / ra) × (s / S / m)
And it is sufficient.

  As a result, the round-trip delay time of ACK is set to T or less, and it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases. That is, when block ACK is used, even if the downlink transmission allocation is set to be small, an increase in the round-trip transmission delay of ACK can be prevented, so that more efficient time allocation is possible.

(Scheduling example 2)
FIG. 9 is an explanatory diagram illustrating another example of the scheduling method according to the present embodiment. The example shown in this figure is an example in which the TDMA periods T of the system A and the system B match.

  In this schedule example, as shown in FIG. 9, the end time of the downlink time allocation in the system A within each period is set to coincide with the end time of the downlink time allocation in the system B. In addition, the start time of uplink time allocation in the system A and the start time of uplink time allocation in the system B are set to coincide with each other in each cycle. Further, the start time of the time allocation in the downlink direction of the system B is set later than the start time of the time allocation in the downlink direction of the system A, and the end time of the time allocation in the uplink direction of the system A is set as the time in the uplink direction of the system B. Set later than the end time of allocation.

  At this time, downlink allocation time td (a) in system A, downlink allocation time td (b) in system B, uplink allocation time tu (a) in system A, uplink allocation time in system B About tu (b), it determines as follows.

When the required transmission rate is R (bit / second), the communication capacity of system A is ra (bit / second), and the communication capacity of system B is rb (bit / second),
T × R ≦ ra × td (a),
T × R ≦ rb × td (b)
Td (a), td (b) satisfying
When the packet size of one TCP is S, the packet size of one ACK is s, and the time required for the ACK packet to pass through the system B is db,
T × R / S × s ≦ ra × tu (a),
T × R / S × s ≦ rb × tu (b)
The following conditions tu (a)> tu (b),
td (a)> td (b),
tu (a) + td (a) ≦ T
Add and decide.

  According to this example schedule, the data transmitted from the transmitter 1 and passing through the system A passes through the system B with the allocated time in the downlink direction of the system B having the same period. Similarly, the ACK for the data is transmitted from the receiver 2 and passed through the system B. The ACK passes through the system A with the allocated time in the uplink direction of the system A having the same period. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, the allocation time to the system B is shorter than the allocation time to the system A. Therefore, when the communication capability rb of the system B and the communication capability ra of the system A satisfy rb> ra. , Particularly efficient time allocation.

(Scheduling example 3)
FIG. 10 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. The example shown in this figure is an example in which the TDMA periods T of the system A and the system B match.

  In this schedule example, as shown in FIG. 10, the start time of the downlink time allocation and the end time of the uplink time allocation in the system A and the system B are set to be the same in each cycle. In addition, the end time of the time allocation in the downlink direction of the system B is later than the end time of the time allocation in the downlink direction of the system A, and the start time of the time allocation in the uplink direction of the system A is the start of the uplink direction of the system B. Set to be late with respect to the time.

At this time, for the downlink allocation times td (a) and td (b) and the uplink allocation times tu (a) and tu (b), the following condition tu (a) <tu (b),
td (a) <td (b),
tu (a) + td (a) ≦ T
To determine.

  According to this example schedule, the data transmitted from the transmitter 1 and passing through the system A passes through the system B with the allocated time in the downlink direction of the system B having the same period. Similarly, an ACK for the data is transmitted from the receiver 2 and passed through the system B. The ACK passes through the system A with the allocated time in the uplink direction of the system A having the same period. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, since the allocation time to the system A is shorter than the allocation time to the system B, when the communication capability rb of the system B and the communication capability ra of the system A satisfy rb <ra. , Particularly efficient time allocation.

(Scheduling example 4)
FIG. 11 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. The example shown in this figure is an example in which the TDMA periods T of the system A and the system B match.

  In this schedule example, as shown in FIG. 11, the start time of the time allocation in the downlink direction of the system B is delayed with respect to the start time of the time allocation in the downlink direction of the system A. The end time is set so as to be later than the time allocation in the downward direction of the system A. Further, the start time of the time allocation in the uplink direction of the system A is later than the start time of the time allocation in the uplink direction of the system B, and the end time of the time allocation in the uplink direction of the system A is the time in the uplink direction of the system B. Set to be late with respect to the allocation start time.

At this time, with respect to the downlink allocation times td (a) and td (b) and the uplink allocation times tu (a) and tu (b), the difference between the downlink start times of the system A and the system B is expressed as follows. Δtd, where Δtu is the difference in upstream start time between system A and system B, and x is the difference between the downstream time allocation end time of system B and the upstream time allocation start time of system B In addition, the following condition Δtd + tb (b) + x + Δtu + tu (a) ≦ T
To determine. That is, the time from the start time of downlink time allocation to the end time of uplink time allocation in system A is set to be equal to or less than time T.

  According to this example schedule, the data transmitted from the transmitter 1 and passing through the system A passes through the system B with the allocated time in the downlink direction of the system B having the same period. Similarly, an ACK for the data is transmitted from the receiver 2 and passed through the system B. The ACK passes through the system A with the allocated time in the uplink direction of the system A having the same period. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

(Scheduling example 5)
FIG. 12 is an explanatory diagram showing still another example of the scheduling method in the present embodiment.

  In the schedule examples 1 to 4 described above, the TDMA periods T of the system A and the system B coincide. On the other hand, in this schedule example, the TDMA period Ta of the system A is different from the TDMA period Tb of the system B. For example, Ta = n × Tb (n is a natural number) or Ta = Tb / n is considered. Or each period may be set so that it may become mxTa = nxTb (m and n are natural numbers).

  As shown in FIG. 12, in this schedule example, the cycle Tb of the system B is set at a cycle that is 1/2 the cycle Ta of the system A (Ta = T, Tb = T / 2). In addition, the end time of the time allocation in the down direction of the system A and the end time of the time allocation in the down direction of the system B coincide with each time T, and the start time of the time allocation in the up direction of the system A and the up time of the system B The start time of the time allocation in the direction is set to match every time T.

At this time, for the uplink allocation times td (a) and td (b) and the downlink allocation times tu (a) and tu (b), the following condition tu (a)> tu (b),
td (a)> td (b),
tu (a) + td (a) ≦ T,
tu (b) + td (b) ≦ T / 2
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passed through the system A is the time allocation in the downlink direction of the system B that ends at the same time as the end time of the time allocation in the downlink direction of the system A at that time. Pass through system B. Further, the ACK for the above data transmitted from the receiver 2 and passing through the system B is the time in the upstream direction of the system A that starts at the same time as the start time of the time allocation in the upstream direction of the system B at that time. It passes through the system A by allocation and arrives at the transmitter 1. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, the time allocation in the downlink direction and the time allocation in the uplink direction in the system B are set for each period Tb (Tb = T / 2), but the present invention is not limited to this. For example, the uplink and downlink allocations may be performed only once every two cycles Tb (that is, time T). Thus, efficient allocation can be performed for the system B without performing excessive allocation.

  Further, in this schedule example, the example in which the period Tb of the system B is 1/2 times as long as the period Ta of the system A is described. However, the period Tb of the system B is 1 / n with respect to the period Ta of the system A. If n is a natural number, the same result is obtained.

  Further, m × Ta = n × Tb (m and n are natural numbers) may be set. In this case, the end time of the downlink time allocation and the start time of the uplink time allocation of each system may be matched every m periods for the system A and every n periods for the system B. Thereby, efficient transmission can be performed when the end time of the downlink time allocation and the start time of the uplink time allocation of each other match.

(Scheduling example 6)
FIG. 13 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. In the example shown in this figure, the TDMA period Ta of the system A is set (Ta = T / 2, Tb = T) at a period ½ times the TDMA period Tb of the system B.

  In this schedule example, as shown in FIG. 13, the start time of the time allocation in the downlink direction of the system A coincides with the start time of the time allocation in the downlink direction of the system B every time T. The time allocation end time and the time allocation end time in the upward direction of the system B are set to coincide with each other for each time T.

At this time, for the allocation times td (a) and td (b) in the downlink direction of the systems A and B and the allocation times tu (a) and tu (b) in the uplink direction, the following condition tu (a)> tu (B),
td (a)> td (b),
tu (a) + td (a) ≦ T / 2
tu (b) + td (b) ≦ T
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passed through the system A is the time in the downstream direction of the system B that starts at the same time as the start time of the time allocation in the downstream direction of the system A at that time. Pass system B by assignment. Further, the receiver 2 transmits an ACK for the above data with the time allocation in the uplink direction in the same period Tb as the time allocation in the downlink direction, and passes through the system B. The ACK that has passed through the system B passes through the system A and arrives at the transmitter 1 with the time allocation in the upward direction in the period Ta next to the period Ta in which the data is transmitted from the transmitter 1. Therefore, ACK of data transmitted from the transmitter 1 and passed through the system A is transmitted to the transmitter 1 by time allocation in the uplink direction of the next period Ta in the system A.

  Here, since the period Ta of the system A is T / 2, an ACK for the data arrives at the transmitter 1 within a time T after the data is transmitted from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, when the requested round-trip delay time is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, the time allocation in the downlink direction and the time allocation in the uplink direction in the system A are set for each period Ta (Ta = T / 2). You may make it perform allocation of an up direction and a down direction only once for every Ta (namely, time T). As a result, efficient allocation can be performed for the system A without performing excessive allocation.

  In this example of the schedule, the period Ta of the system A is ½ times as long as the period Tb of the system B. However, the period Ta of the system A is 1 / n with respect to the period Tb of the system B. If n is a natural number, the same result is obtained.

  Further, m × Ta = n × Tb (m and n are natural numbers) may be set. In this case, the start time of the time allocation in the downlink direction and the end time of the time allocation in the uplink direction of each other system may be matched every m cycles for the system A and every n cycles for the system B. Thus, efficient transmission can be performed when the start time of the downlink time allocation and the end time of the uplink time allocation of each system match.

(Scheduling example 7)
FIG. 14 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. In the example shown in this figure, the TDMA period Tb of the system B is set (Ta = T, Tb = T / 2) at a period ½ times the TDMA period Ta of the system A.

  In this schedule example, the start time of the time allocation in the downward direction of the 2 × k-th period Tb in the system B is more than the start time of the time allocation in the downward direction of the k-th period (k is a natural number) in the system A. It is later, and the end time of the downlink time allocation of the 2 × k-th cycle Tb in the system B is later than the end time of the downlink time allocation of the k-th cycle Ta in the system A. Is set. Furthermore, the start time of the uplink time allocation of the kth cycle Ta in the system A is later than the start time of the uplink time allocation of the 2nd k + 1 cycle Tb in the system B. The end time of the uplink time allocation of the kth cycle Ta in the system A is set to be later than the end time of the uplink time allocation of the (k + 1) th cycle Tb.

Further, the downlink allocation times td (a) and td (b) of the system A and the system B and the uplink allocation times tu (a) and tu (b) are the downlinks of the kth cycle Ta in the system A. The difference between the start time of the time allocation in the direction and the start time of the time allocation in the down direction of the 2 × k-th period Tb in the system B is Δtd, and the time allocation in the up direction of the 2 × k-th period Tb in the system B Δtu is the difference between the start time and the start time of uplink time allocation in the kth period Ta in the system A, and the difference between the end time of downlink time allocation and the start time of uplink time allocation in the system B is When x, the following condition Δtd + tb (b) + x + Δtu + tu (a) ≦ T
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passed through the system A in the time allocation in the downlink direction of the kth cycle Ta in the system A is the downlink direction of the 2 × kth cycle Tb in the system B. Is transmitted to the receiver 2 through the system B with the time allocation of. Then, the ACK for the data passes through the system B with the 2 × k + 1th uplink time allocation of the system B, and passes through the system A with the uplink time allocation of the kth period Ta in the system A. Is transmitted to the machine 1.

  Here, since the period Ta of the system A is T, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK becomes T or less, when the requested round-trip delay time is T or less, it is possible to prevent the transmission rate from being lowered with the increase of the round-trip transmission delay of ACK.

  In this schedule example, the time allocation in the downlink direction and the time allocation in the uplink direction in the system B are set for each period Tb (Tb = T / 2), but the present invention is not limited to this. For example, the uplink and downlink allocations may be performed only once every two cycles Tb (that is, time T). Thus, efficient allocation can be performed for the system B without performing excessive allocation.

  Further, in this schedule example, the example in which the period Tb of the system B is 1/2 times as long as the period Ta of the system A is described. However, the period Tb of the system B is 1 / n with respect to the period Ta of the system A. If n is a natural number, the same result is obtained.

  Further, m × Ta = n × Tb (m and n are natural numbers) may be set. In this case, the end time of the downlink time allocation and the start time of the uplink time allocation for each system are set as described above for every m cycles for the system A and every n cycles for the system B. That's fine.

  As described above, the relay device (control command device, control device) 3 in the present embodiment performs TDMA settings for two systems (system A and system B) connected by the relay device 3. When performing TCP communication on a transmission line using a system, the time from when data is transmitted from the transmitter 1 until the arrival of an ACK for the data at the transmitter 1 is less than or equal to a predetermined time (time T) The transmission time zone allocation in each system is controlled in association with each other.

  As a result, the round trip delay time of the TCP ACK can be made equal to or less than a predetermined value, and the problem of a decrease in transmission rate accompanying an increase in the round trip delay time can be solved.

  In each of the schedule examples described above, an example in which one time allocation in the uplink direction and one time allocation in the downlink direction are performed for one period of the TDMA has been described. You may use the allocation method from which the set result becomes time allocation like the schedule examples shown in FIGS.

  In this embodiment, the communication control unit A 3103 and the communication control unit B 3104 of the relay device 3 manage (control) the time allocation of the system A and the system B. However, the present invention is not limited to this. Different devices (for example, the transmitter 1 and / or the receiver 2) may be managed.

  However, when the management of the time allocation of the system A and the management of the time allocation of the system B are performed by different devices, the cycle of the system A and the system B is slightly different, and the operation between the devices when the time elapses. There may be a difference between the start times in the upstream and downstream directions due to the clock shift. Therefore, in consideration of such a situation, the schedule of each system may be reset when the shift of the allocated time of each system exceeds a predetermined value.

For example, in the above schedule example 1,
td = T × R / ra + α,
tu = T × R / ra × s / S + β
Given td and tu so that
Δt = (Starting time of descending system A) − (Starting time of descending system B)
For Δt of
Δt = β or Δt = −α
Then, rescheduling may be performed.

  As a result, even if the operation clocks of the devices managing the clocks of each system (communication system) are shifted, the time in each system can be reset to prevent an increase in transmission delay caused by a shift.

[Embodiment 2]
Another embodiment of the present invention will be described. For convenience of explanation, members having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

  FIG. 2 is a block diagram showing a schematic configuration of a network (network system) according to the present embodiment. As shown in this figure, the network according to the present embodiment is composed of a system A, a system B, and a system C. The system A and the system B can be time-division controlled by TDMA, and the system C is configured not to be able to perform time-division control by TDMA. For example, wireless LAN (802.11e) is used as the system A, PLC is used as the system B, and Ethernet (registered trademark) is used as the system C. However, the configuration of each system is not limited to this, and various communication media can be used. In the present embodiment, the communication media different from those of the system A and the system B are used. However, the present invention is not limited to this, and the same communication medium may be used.

  In the first embodiment, the relay device 3 connecting the two systems A and B schedules the time allocation of each system, and manages and controls the time allocation of each system based on the scheduling. On the other hand, in the network according to the present embodiment, the control device that manages and controls the time allocation of each system, and information on the usage status of each system is acquired from each control device, and the round trip delay time is based on the information. And a control command device for requesting each control device to manage and control time allocation based on the scheduling result.

  As shown in FIG. 2, the network according to the present embodiment includes a transmitter 1, a relay device A (control device) 22, a relay device B (control device) 23, a receiver 2, and a control command device 25. The transmitter 1 and the receiver 2 are the same as those described in the first embodiment.

  The relay device A22 is a device for connecting the systems A and C to each other and transmitting / receiving data using both systems. The relay device A22 performs time division control by TDMA of the system A based on the control request regarding the time division of the system A from the control command device 25.

  The relay device B23 is a device for connecting the systems B and C to each other and transmitting and receiving data using both systems. The relay device B23 performs time division control by TDMA of the system B based on the control request regarding the time division of the system B from the control command device 25.

  The relay device A22 and the relay device B23 have the same configuration as the relay device 3 described in the first embodiment except that the control unit 3102 is not provided. In the present embodiment, the control unit 3102 is provided in the control command device 25.

  Also, the relay device A22 and the relay device B23 according to the present embodiment need to perform time allocation of each system at a specified time or interval in response to a control request from the control command device 25. Therefore, the relay device A22 and the relay device B23 synchronize the internal time using a mechanism such as NTP (Network Time Protocol). Note that the means for synchronizing each relay apparatus is not limited to this. Further, the means for synchronizing each relay device may be provided anywhere on the network, for example, may be provided in the control command device 25.

  The control instruction device 25 acquires information on the usage status (communication state) of the system A and the system B from the relay device A22 and the relay device B23, and based on the acquired result, the relay command device A22 and the relay device B23 are subjected to TDMA. Request time-sharing control.

  FIG. 32 is a block diagram showing the internal configuration of the control command device 25. As shown in this figure, the control command device 25 includes a processing unit 3301 and a communication unit 3303.

  The processing unit 3301 includes a control unit 3102 and a communication control unit 3304. The control unit 3102 communicates with a device capable of TDMA control on the network via the communication unit 3303 to acquire information on the usage status of each system (here, system A and system B) and is necessary for each system It is determined whether a secure transmission band can be secured, and a series of processes for making a control request regarding time division control to each device on the network is performed. The configuration of the control unit 3102 is the same as that of the first embodiment. The communication control unit 3304 controls the operation of the communication unit 3303.

  The processing unit 3301 includes a processor such as a CPU, for example, and the functions of each member provided in the processing unit 3301 are realized by reading and executing software stored in a ROM or the like (not shown). That is, the processing unit 3301 is a processor that is operated by software (driver software or the like) that performs various control processes.

  The communication unit 3303 is an interface for communicating with other devices (network devices) on the network, and is, for example, an Ethernet, a wireless LAN LAN card, a PLC modem, or the like (but is not limited thereto). ).

  Next, a control flow in which the control unit 3102 of the control command device 25 makes a control request to each device (relay device A22 and relay device B23) on the network will be described with reference to FIG.

  The control unit 3102 (initialization determination unit 3111) first makes an inquiry to each device on the network as to whether or not initialization has been performed (S3401). This inquiry may be made, for example, only for devices registered in advance on the control command device 25, or may be made by broadcast to all devices (all network nodes) on the network. It should be noted that each device on the network may be initialized independently, and in this case, this inquiry and the determination in S3402 may be omitted.

  The control unit 3102 (initialization determination unit 3111) receives a response as to whether or not initialization has been performed from each device, and determines whether or not each device has been initialized (S3402). When the control unit 3102 (initialization request unit 3112) has not been initialized, the control unit 3102 (communication control unit A3103 and relay device provided in the relay device A) is provided in each control device via the communication unit 3303. An initialization request is sent to the communication control unit B3104) provided in B (S3406). In this initialization request, the TDMA cycle, the start time of the first cycle, and the like are set as in the first embodiment.

  On the other hand, if it is determined in S3402 that the initialization is performed, the control unit 3102 (usage status acquisition unit 3113) inquires the usage status (communication status) to the target device (control device) on the network (S3404). ). The usage status includes, for example, TDMA period (service interval) of each system, start time of the next period (start time of the next service), information on a period that can be allocated within each period, and the like.

  Then, the control unit 3102 (schedulability determination unit 3114) acquires information on the usage status from each target device, and determines whether or not predetermined scheduling is possible based on the acquired information (S3405). That is, the control unit 3102 (schedulability determination unit 3114) starts the TDMA period of each system and the next period acquired from the communication control unit A3103 provided in the relay device A22 and the communication control unit B3104 provided in the relay device B23. Based on the time and information on the period that can be allocated within each cycle, it is determined whether or not a predetermined scheduling for making the round trip delay time within a predetermined time during which a necessary transmission rate can be obtained is possible. This predetermined scheduling will be described later.

  If it is determined in S3405 that the predetermined scheduling is possible, the control unit 3102 (control request unit 3115) issues a request to secure a transmission band to the control device that manages and controls the time allocation of the target system. Transmission is performed via the communication unit 3303 (S3406). This request may include a request for changing the TDMA period, if necessary. For example, the TDMA cycle has already been determined by the target device performing the initialization autonomously, but the cycle is large, and it is not possible to secure the necessary transmission bandwidth with TCP no matter what allocation is performed. In such a case, the TDMA cycle change request may be included in the case where the target device is configured to accept a cycle change request (but not limited to this).

  On the other hand, if it is determined in S3405 that the predetermined scheduling cannot be performed, the control unit 3102 (scheduling availability determination unit 3114) determines that a transmission band necessary for communication cannot be secured, and a bandwidth securing request destination (for example, a user) On the other hand, a notification that the bandwidth cannot be secured is made, and the process is terminated.

  Next, a scheduling method (the predetermined scheduling) will be described. In the following schedule example, the time required for a packet to pass through each system and the time required for transmission on the relay device A22 and the relay device B23 are ignored. When it is necessary to consider these times, the time is not particularly limited. For example, these times may be added to the time allocated to each system.

(Scheduling example 8)
FIG. 15 is an explanatory diagram illustrating an example of a scheduling method according to the present embodiment. Note that the scheduling method for the system A and the system B in the scheduling example shown in this figure is substantially the same as the scheduling example 4 shown in the first embodiment. However, since the system C is sandwiched between the system A and the system B, for example, in consideration of the maximum time D for each packet to pass through the system C in a normal situation,
Δtd> D and Δtu> D
Δtd and Δtu are determined so that

  According to this schedule example, if the transmission time in the system C is equal to or shorter than D, the TCP ACK is within the time T after the data transmission from the transmitter 1 is performed, as in the scheduling example 4 in the first embodiment. Arrives at transmitter 1. Therefore, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In addition, although the case where the scheduling substantially the same as the scheduling example 4 in the first embodiment has been described here, the scheduling is not limited to this, and the same scheduling as the other scheduling examples shown in the first embodiment may be performed. Good. That is, each scheduling example shown in the first embodiment may be used in consideration of the transmission time in the system C.

  In this embodiment, the communication control unit A3103 provided in the relay device A22 performs time division control of the system A, and the communication control unit B3104 provided in the relay device B23 performs time division control of the system B. This is not a limitation. That is, the device that controls the communication state in each system is not necessarily a relay device. For example, as illustrated in FIG. 3, the transmitter 1 may perform time division control of the system A, and the receiver 2 may perform time division control of the system B. Further, either the relay device A22 or the relay device B23 may perform time division control of the system A and the system B.

  In the present embodiment, the control command device 25 is provided separately from the transmitter 1, the relay device A22, the relay device B23, and the receiver 2, but is not limited thereto. That is, the function of the control command device 25 (control unit 3102) may be provided in any one of the transmitter 1, the relay device A22, the relay device B23, and the receiver 2.

  For example, as illustrated in FIG. 4, in a configuration in which the transmitter 1 performs time division control of the system A and the receiver 2 performs time division control of the system B, the transmitter 1 executes the function of the control command device 25. You may do it. In other words, the control command device 25 may be configured to be integrated with a device that performs time-sharing control of a certain system. Note that when the device provided on the transmission path has the function of the control command device 25 (control unit 3102), the control request transmitted from the control command device 25 is different from the data transmitted through each system by TCP. It is preferable to use a signal not identified as.

  As described above, in the present embodiment, the control command device 25 acquires information on the usage status from each device (control device) that controls a TDMA-controllable system on the communication path, and based on the result, In each system, it is determined whether a necessary transmission band can be secured between the transmitter 1 and the receiver 2. If a transmission band can be secured, a control request is sent to each device.

  Thereby, time allocation can be performed in each system so that the round-trip delay time when transmitting using TCP between the transmitter 1 and the receiver 2 is set to a predetermined value or less. It becomes possible. Therefore, it is possible to prevent the transmission rate from being lowered due to the increase in the round trip delay time.

[Embodiment 3]
Still another embodiment of the present invention will be described. For convenience of explanation, members having the same functions as those in the first and second embodiments are denoted by the same reference numerals as those in the first and second embodiments, and description thereof is omitted.

  FIG. 5 is a block diagram showing a schematic configuration of a network (network system) according to the present embodiment. As shown in this figure, the network according to the present embodiment is composed of a system A, a system B, and a system C, and each of these systems is configured to be capable of time division control by TDMA. For example, the wireless LAN (802.11e) is used as the system A, the PLC is used as the system B, and the UWB (Ultra Wide Band) is used as the system C. However, the configuration of each system is not limited to this, and various communication media can be used. In the present embodiment, the systems A, B, and C use different communication media. However, the present invention is not limited to this, and the same communication media may be used.

  As shown in FIG. 5, the network according to the present embodiment includes a transmitter 1, a relay device A (control device) 22, a relay device B (control device) 23, a receiver 2, and a control command device 25.

  The relay device A22 is a device for connecting the systems A and B to each other and transmitting / receiving data using both systems. Both the system A and the system B can secure a transmission band in the time division control by TDMA, and the relay device A22 receives the system A based on the control request regarding the time division of the system A from the control command device 25. Time-division control by TDMA. The configuration of the relay device A22 is the same as that shown in the second embodiment.

  The relay device B23 is a device for connecting the systems B and C to each other and transmitting and receiving data using both systems. Both the system B and the system C can secure a transmission band in the time division control by TDMA, and the relay apparatus B23 is based on the control request regarding the time division of the system B and the system C from the control command apparatus 25. System B and system C are time-division controlled by TDMA. The relay device B23 is substantially the same as the relay device B23 shown in the second embodiment. However, in addition to the configuration shown in the second embodiment, the relay device B23 according to the present embodiment includes a communication control unit C for performing time division control of the system C (managing and controlling time allocation of the system C). I have. The function and configuration of the communication control unit C are the same as those of the communication control units A and B.

  Also, the relay device A22 and the relay device B23 according to the present embodiment need to perform time allocation of each system at a specified time or interval in response to a control request from the control command device 25. Therefore, the relay device A22 and the relay device B23 synchronize the internal time using a mechanism such as NTP (Network Time Protocol), for example.

  The control command device 25 acquires information on the usage status (communication state) of the systems A, B, and C from the relay device A22 and the relay device B23, and sends the information to the relay device A22 and the relay device B23 based on the acquired information. On the other hand, a time division control request by TDMA is made.

  The configuration and operation (processing contents) of the control instruction device 25 are substantially the same as those in the second embodiment. However, the scheduling method is slightly different from that of the second embodiment. Here, the scheduling method in the present embodiment will be described.

(Scheduling example 9)
FIG. 16 is an explanatory diagram illustrating an example of a scheduling method according to the present embodiment. The example shown in this figure is an example when the TDMA periods T of the systems A, B, and C match.

  In this schedule example, as shown in FIG. 16, the start time and end time of downlink time allocation in each system are matched, and the start time and end time of uplink time allocation in each system are set to match. To do.

  In this schedule example, as shown in this figure, the start and end times of time allocation in the upstream direction (in the direction of the receiver 2 → the relay device 3 → the transmitter 1) in the system A within each cycle, The start time and the end time of the time allocation in the uplink direction are set to coincide with each other.

  At this time, the uplink allocation time td and the downlink allocation time tu of each system are determined as follows based on the same concept as in scheduling example 1 shown in the first embodiment.

That is, the required transmission rate is R (bit / second), the communication capability of system A is ra (bit / second), the communication capability of system B is rb (bit / second), and the communication capability of system C is rc (bit / bit). Seconds), where T is the TDMA period of each system,
T × R ≦ min (ra × td, rb × td, rc × td)
Td that satisfies the above is defined as the allocation time in the downlink direction. Note that min (a, b, c) means the smallest value among a, b, and c.

Thus, for example, if ra = rb = rc,
td ≧ T × R / ra
It becomes.

If one TCP packet size is S and one ACK packet size is s,
T × R / S × s ≦ min (ra × tu, rb × tu, rc × tu)
The tu that satisfies the above condition is set as the uplink allocation time.

Thus, for example, if ra = rb = rc,
tu ≧ T × R / ra × s / S
It becomes.

  According to this example schedule, the data passing through the system A passes through the system B without waiting time at the relay device A22, and passes through the system C without waiting time at the relay device B23. Similarly, the ACK for the data passes through the system B without waiting time at the relay device B23 and passes through the system A without waiting time at the relay device A22. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  Further, in this schedule example, the allocation time in the uplink direction and the downlink direction to each system is the same. For this reason, when the communication capability of each system is equal, especially efficient time allocation can be performed.

  In the scheduling example shown in FIG. 16, unused time allocation or time allocation to other streams is provided within the period of each system. However, the present invention is not limited to this, and each period is assigned to the transmitter 1 and the receiver. 2 may be configured only by time allocation in the uplink and downlink directions between the two.

(Scheduling example 10)
FIG. 17 is an explanatory diagram illustrating an example of a scheduling method according to the present embodiment. The example shown in this figure is an example when the TDMA periods T of the systems A, B, and C match.

  In this schedule example, as shown in FIG. 17, setting is made so that the end time of the downlink time allocation in each system matches and the start time of the uplink time allocation in each system matches. Further, the start time of time allocation in the downlink direction is set so that the system B is later than the system A and the system C is later than the system B. Further, the end time of the time allocation in the upward direction is set so that the system B is later than the system A and the system C is later than the system B.

  At this time, the downlink allocation times td (a), td (b), td (c) and the uplink allocation times tu (a), tu (b), tu (c) are shown in the first embodiment. Based on the same idea as in scheduling example 2, the following determination is made.

The required transmission rate is R (bit / second), the communication capacity of system A is ra (bit / second), the communication capacity of system B is rb (bit / second), and the communication capacity of system C is rc (bit / second). When TDMA cycle of each system is T,
T × R ≦ ra × td (a),
T × R ≦ rb × td (b),
T × R ≦ rc × td (c)
Td (a), td (b), td (c) satisfying the above, one TCP packet size S, one ACK packet size s, and time required for the ACK packet to pass through the system B If db
T × R / S × s ≦ ra × tu (a),
T × R / S × s ≦ rb × tu (b),
T × R / S × s ≦ rc × tu (c)
And the following condition tu (a)> tu (b)> tu (c),
td (a)> td (b)> tu (c),
tu (a) + td (a) ≦ T
Add and decide.

  According to this example schedule, the data passing through the system A passes through the system B without waiting time at the relay device A22, and passes through the system C without waiting time at the relay device B23. Similarly, the ACK for the data passes through the system B without waiting time at the relay device B23, and the ACK passing through the system B passes through the system A without waiting time at the relay device A22. . Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  Further, in this schedule example, the length of the allocation time in the uplink direction and the downlink direction to each system is system A> system B> system C, so that the communication capability of each system is rc> rb> ra. In such cases, particularly efficient time allocation can be performed.

  In the scheduling example shown in FIG. 17, the time allocation in the direction from the transmitter 1 to the receiver 2 (downward direction) and the time allocation in the direction from the receiver 2 to the transmitter 1 (upstream direction) in each system are continuous. However, the present invention is not limited to this, and time allocation in the direction from the transmitter 1 to the receiver 2 (downward) and time allocation in the direction from the receiver 2 to the transmitter 1 (upstream) in each system. In between, an unused time allocation or a time allocation to another stream may be provided.

(Scheduling example 11)
FIG. 18 is an explanatory diagram showing another example of the scheduling method in the present embodiment. The example shown in this figure is an example when the TDMA periods T of the systems A, B, and C match.

  In this schedule example, as shown in FIG. 18, the start time of the downlink time allocation in each system is matched, and the end time of the uplink time allocation in each system is set to match. Further, the end time of the time allocation in the downlink direction is set so that the system B is later than the system A and the system C is later than the system B. Further, the start time of the time allocation in the upward direction is set so that the system B is later than the system C and the system A is later than the system B.

At this time, the downlink allocation times td (a), td (b), td (c) and the uplink allocation times tu (a), tu (b), tu (c) are shown in the first embodiment. Based on the same idea as in scheduling example 3, the following condition tu (a) <tu (b) <tu (c),
td (a) <td (b) <td (c),
tu (a) + td (a) ≦ T
To determine.

  According to this schedule example, data transmitted from the transmitter 1 and passing through the system A passes through the system B at the downlink allocation time of the system B having the same period, and the downlink allocation of the system C having the same period. Pass through system C in time. Similarly, the ACK for the data is transmitted from the receiver 2 and passed through the system C. The ACK passes through the system B at the upstream allocation time of the system B having the same period, and is transmitted from the system A having the same period. The system A is passed through the allocation time in the uplink direction. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this example of schedule, the length of the allocation time in the uplink direction and the downlink direction to each system is system A <system B <system C, so that the communication capacity of each system is ra> rb> rc. In such cases, particularly efficient time allocation can be performed.

  In the scheduling example shown in FIG. 18, time allocation in the direction from the transmitter 1 to the receiver 2 (downward direction) and time allocation in the direction from the receiver 2 to the transmitter 1 (upstream direction) in the system C are continuous. However, not limited to this, time allocation in the direction from the transmitter 1 to the receiver 2 (downward direction) and time allocation in the direction from the receiver 2 to the transmitter 1 (upstream direction) in the system C In between, an unused time allocation or a time allocation to another stream may be provided.

(Scheduling example 12)
FIG. 19 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. The example shown in this figure is an example when the TDMA periods T of the systems A, B, and C match.

  In this schedule example, as shown in FIG. 19, the start time and the end time of the downlink time allocation to each system are set so as to be delayed in the order of system A, system B, and system C, respectively. In addition, the start time and end time of the time allocation in the upward direction to each system are set so as to be delayed in the order of system C, system B, and system.

At this time, the downlink allocation times td (a), td (b), td (c) and the uplink allocation times tu (a), tu (b), tu (c) are shown in the first embodiment. Based on the same concept as in scheduling example 4, the following determination is made. That is, the difference in the start time in the down direction between the system A and the system B is Δtd (1), the difference in the start time in the down direction between the system B and the system C is Δtd (2), and the difference between the system C and the system B Δtu (1) is the difference between the start times of the directions, Δtu (2) is the difference between the start times in the upstream direction of the system B and the system A, and the end time of the time allocation in the downstream direction of the system C and the upstream direction of the system C When the difference from the time allocation start time is x (not shown in FIG. 19 because x = 0), the following condition Δtd (1) + Δtd (2) + tb (c) + x + Δtu (1) + Δtu (2 ) + Tu (a) ≦ T
To determine. That is, the time from the start time of downlink time allocation to the end time of uplink time allocation in system A is set to be equal to or less than time T.

  According to this schedule example, data transmitted from the transmitter 1 and passing through the system A passes through the system B at the downlink allocation time of the system B having the same period, and the downlink allocation of the system C having the same period. Pass through system B in time. Similarly, the ACK for the data is transmitted from the receiver 2 and passed through the system C. The ACK passes through the system B at the upstream allocation time of the system B having the same period, and is transmitted from the system A having the same period. The system A is passed through the allocation time in the uplink direction. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In the scheduling example shown in FIG. 19, the time allocation in the direction from the transmitter 1 to the receiver 2 (downward direction) and the time allocation in the direction from the receiver 2 to the transmitter 1 (upstream direction) in the system C are continuous. However, not limited to this, time allocation in the direction from the transmitter 1 to the receiver 2 (downward direction) and time allocation in the direction from the receiver 2 to the transmitter 1 (upstream direction) in the system C In between, an unused time allocation or a time allocation to another stream may be provided.

(Scheduling example 13)
FIG. 20 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. As shown in this figure, in this schedule example, the cycle Tb of the system B is set at a cycle 1/2 times the cycle Ta of the system A, and the cycle of the system C is set at a cycle 1/4 of the cycle Ta of the system A. A cycle Tc is set (Ta = T, Tb = T / 2, Tc = T / 4).

  Further, the end time of the downlink time allocation of each system and the start time of the uplink time allocation of each subsequent system are set to coincide with each other at each time T.

At this time, uplink allocation times td (a) and td (b) and downlink allocation times tu (a) and tu (b) are based on the same concept as in scheduling example 5 shown in the first embodiment. The following conditions tu (a)> tu (b)> tu (c),
td (a)> td (b)> td (c),
tu (a) + td (a) ≦ T,
tu (b) + td (b) ≦ T / 2
tu (c) + td (c) ≦ T / 4
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passing through the system A is the time allocation in the downlink direction of the system B that ends at the same time as the end time of the time allocation in the downlink direction of the system A at that time. The system B and the system C are passed through the time allocation in the downstream direction of the system C. The ACK for the above data transmitted from the receiver 2 and passed through the system C is the time in the upstream direction of the system B that is started at the same time as the start time of the time allocation in the upstream direction of the system C at that time. With the allocation and the time allocation in the uplink direction of the system A, it passes through the systems B and A and arrives at the transmitter 1. Therefore, an ACK for the data arrives at the transmitter 1 within a time T after sending the data from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, downlink time allocation and uplink time allocation in system B are set for each period Tb (Tb = T / 2), and downlink time allocation and uplink time allocation in system C are set. Is set for each period Tc (Tc = T / 4), but is not limited thereto. For example, for system B, allocation in the upward and downward directions is performed only once every two cycles Tb (ie, time T), and for system C, only once every four cycles Tc (ie, time T). You may make it perform allocation of an up direction and a down direction. As a result, efficient allocation can be performed for the systems B and C without performing extra allocation.

  Further, in this example of the schedule, the period Tb of the system B is ½ times the period Ta of the system A, and the period Tc of the system C is ¼ times as long as the period Ta of the system A. If the cycle Tb of the system B is 1 / n (n is a natural number) with respect to the cycle Ta of the system A and the cycle Tc of the system C is 1 / (2 × n) with respect to the cycle Ta of the system A, the same Results are obtained.

  In the scheduling example shown in FIG. 20, the end time of the time allocation in the downlink direction (from the transmitter 1 to the receiver 2) of each system matches every time T. Although the time allocation start time in the next upstream direction of the system (from the receiver 2 to the transmitter 1) is provided, the present invention is not limited to this. For example, after the end time of time allocation in the downlink direction (the direction from the receiver 2 to the transmitter 1) of each system matches every time T, the next uplink direction (from the receiver 2 to the transmitter 1 of each system) Between the start times of the (direction) time assignments, unused time assignments or other stream time assignments may be provided.

(Scheduling example 14)
FIG. 21 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. As shown in this figure, in this schedule example, the cycle Tb of the system B is set at a cycle that is 1/2 times the cycle Tc of the system C, and the cycle of the system A is set at a cycle that is 1/4 of the cycle Tc of the system C. The period Ta is set (Ta = T / 4, Tb = T / 2, Tc = T).

  Further, the end time of the upstream time allocation of each system and the start time of the downstream time allocation of each subsequent system are set to coincide with each other at time T.

At this time, the downlink allocation times td (a), td (b), td (c) and the uplink allocation times tu (a), tu (b), tu (c) of each system are described in the embodiment. 1 based on the same concept as the scheduling example 6 shown in FIG. 1, and the following condition tu (a)> tu (b)> tu (c),
td (a)> td (b)> td (c),
tu (a) + td (a) + td (c) ≦ T / 2
tu (c) + td (c) ≦ T
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passed through the system A is the time in the downstream direction of the system B that starts at the same time as the start time of the time allocation in the downstream direction of the system A at that time. The system B and the system C are passed through the allocation and the time allocation in the downstream direction of the system C. Further, the receiver 2 transmits an ACK for the above data in the uplink time allocation in the same period Tb as the downlink time allocation, and passes through the system C. The ACK that has passed through the system C passes through the system A and arrives at the transmitter 1 with the time allocation in the uplink direction four periods after the period Ta in which the above data is transmitted from the transmitter 1. Therefore, the ACK of the data transmitted from the transmitter 1 and passing through the system A is transmitted to the transmitter 1 by time allocation in the uplink direction after four cycles in the system A.

  Here, since the period Ta of the system A is T / 4, an ACK for the data arrives at the transmitter 1 within a time T after the data is transmitted from the transmitter 1. Thereby, since the round-trip delay time of ACK is T or less, when the requested round-trip delay time is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  In this schedule example, downlink time allocation and uplink time allocation in system B are set for each period Tb (Tb = T / 2), and downlink time allocation and uplink time allocation in system A are set. Is set for each period Ta (Ta = T / 4), but is not limited thereto. For example, for system B, allocation in the upward and downward directions is performed only once every two periods Tb (ie, time T), and for system A, only once every four periods Ta (ie, time T). You may make it perform allocation of an up direction and a down direction. As a result, it is possible to perform efficient allocation to system A and system B without performing extra allocation.

  In this schedule example, the period Tb of the system B is ½ times the period Tc of the system C, and the period Ta of the system A is ¼ times longer than the period Tc of the system C. If the cycle Tb of the system B is 1 / n (n is a natural number) with respect to the cycle Tc of the system C and the cycle Ta of the system A is 1 / (2 × n) with respect to the cycle Tc of the system C, the same Results are obtained.

  In the scheduling example shown in FIG. 21, the end time of the time allocation in the upstream direction (the direction from the receiver 2 to the transmitter 1) of each system matches every time T. Although the time allocation start time in the next downstream direction (from the transmitter 1 to the receiver 2) of the system is provided, the present invention is not limited to this. For example, after the end time of time allocation in the upstream direction (from the transmitter 1 to the receiver 2) of each system matches every time T, the next downstream direction (from the transmitter 1 to the receiver 2) of each system Between the start times of the (direction) time assignments, unused time assignments or other stream time assignments may be provided.

(Scheduling example 15)
FIG. 22 is an explanatory diagram showing still another example of the scheduling method in the present embodiment. As shown in this figure, in this schedule example, the cycle Tb of the system B is set at a cycle that is 1/2 times the cycle Tc of the system C, and the cycle of the system A is set at a cycle that is 1/4 of the cycle Tc of the system C. The period Ta is set (Ta = T / 4, Tb = T / 2, Tc = T).

  In this schedule example, the start of the time allocation in the downlink of the 2 × k-th cycle Tb in the system B rather than the start time of the time allocation in the downlink of the 4 × k-th (k is a natural number) cycle Ta in the system A. The time is later and the start time of the downlink time allocation of the kth period Tc in the system C is later than the start time of the downlink time allocation of the 2 × kth period Tb in the system B. Is set to Further, the end time of the time allocation in the down direction of the 2 × k-th period Tb in the system B is more than the end time of the time allocation in the down direction of the 4 × k-th (k is a natural number) period Ta in the system A. Is set so that the end time of the downlink time allocation of the kth cycle Tc in the system C is later than the end time of the downlink time allocation of the 2 × kth cycle Tb in the system B. ing. That is, the length of the allocation time in the downlink direction of each system is set to satisfy td (a) <td (b) <td (c).

  Further, the start time of the downlink time allocation of the 2 × k + 1-th cycle Tb in the system B is later than the start time of the downlink time allocation of the k-th cycle Tc in the system C. The start time of the time allocation in the down direction of the 4 × k + 3rd period Ta in the system A is set later than the start time of the time allocation in the down direction of the × k + 1 period Tb. Further, the end time of the downlink time allocation of the 2 × k + 1-th cycle Tb in the system B is later than the end time of the downlink time allocation of the k-th cycle Tc in the system C. The end time of the downlink time allocation of the 4 × k + 3rd cycle Ta in the system A is set later than the end time of the downlink time allocation of the × k + 1th cycle Tb. That is, the length of the allocation time in the uplink direction of each system is set to satisfy tu (a) <tu (b) <tu (c).

Also, the downlink allocation times td (a), td (b), td (c) and the uplink allocation times tu (a), tu (b), tu (c) of each system are The difference between the start time of the time allocation in the down direction of the 4 × k-th cycle Ta and the start time of the time allocation in the down direction of the 2 × k-th cycle Tb in the system B is Δtd (1), and 2 × in the system B The difference between the start time of the downlink time allocation of the kth cycle Tb and the start time of the downlink time allocation of the kth cycle Tc in the system C is Δtd (2), and the difference of the kth cycle Tc in the system C The difference between the end time of the uplink time allocation and the end time of the uplink time allocation of the 2 × k + 1-th cycle Tb in the system B is Δtu (1), and the uplink direction of the 2 × k + 1-th cycle Tb in the system B Time allocation end time and 4 × k + 3rd period T in system A Δtu (2), and the difference between the end time of the downlink time allocation in the system C and the start time of the uplink time allocation is x. When the following condition is satisfied: Δtd (1) + Δtd (2) + td (c) + x + tu (c) + Δtu (1) + Δtu (2) ≦ T
To determine.

  According to this schedule example, the data transmitted from the transmitter 1 and passed through the system A in the time allocation in the downstream direction of the 4 × k-th cycle Ta in the system A is the 2 × k-th cycle Tb in the system B. The signal is transmitted to the receiver 2 through the system B with the time allocation in the downlink direction and through the system C with the time allocation in the downlink direction of the k-th period Tc in the system C. Then, the ACK for the data passes through the system C in the uplink time allocation of the kth period Tc in the system C, and passes through the system B in the uplink time allocation of the 2 × k + 1 period Tb in the system B. Then, the signal is transmitted to the transmitter 1 through the system A with the time allocation in the upward direction of the 4 × k + 3rd period Ta in the system A. Here, since the period Ta of the system A is T / 4, an ACK for the data arrives at the transmitter 1 within a time T after the data is transmitted from the transmitter 1. Thereby, since the round-trip delay time of ACK becomes T or less, when the requested round-trip delay time is T or less, it is possible to prevent the transmission rate from being lowered with the increase of the round-trip transmission delay of ACK.

  In this schedule example, downlink time allocation and uplink time allocation in system A are set for each period Ta (Ta = T / 4), and downlink time allocation and uplink time allocation in system B are set. Is set for each period Tb (Tb = T / 2), but is not limited thereto. For example, the allocation in the up and down directions is performed only once every four periods Ta (ie, time T), and the allocation in the up and down directions is performed only once every two periods Tb (ie, time T). You may make it perform. As a result, efficient allocation can be performed for the system A and the system B without performing extra allocation.

  Further, in this schedule example, the period Tb of the system B is ½ times as long as the period Tc of the system C, and the period Ta of the system A is ¼ times as long as the period Tc of the system C. The cycle Tb of the system B is 1 / n (n is a natural number) with respect to the cycle Tc of the system C, and the cycle Ta of the system A is 1 / (2 × n with respect to the cycle Tc of the system C. ), The same result is obtained.

  In the schedule example shown in FIG. 22, the length of the allocation time in the downlink direction of each system is td (a) <td (b) <td (c), and the length of the allocation time in the uplink direction of each system. Is set so that tu (a) <tu (b) <tu (c). However, the present invention is not limited to this. For example, the length of the allocation time in the downlink direction of each system is td (a)> td (b)> td (c), and the length of the allocation time in the uplink direction of each system is tu (a)> tu (b )> Tu (c). Further, for example, an ACK for data transmitted from the transmitter 1 in the downlink time allocation of the kth cycle in the system A arrives at the transmitter 2 by the k + 1th uplink time allocation in the system A. Scheduling may be performed as described above.

  As described above, in the present embodiment, the usage status acquisition unit 3113 of the control command device 25 uses the status from each device (control device) that performs time-sharing control of three or more TDMA-controllable systems on the communication path. The information regarding this is acquired, and based on the result, the scheduling availability determination unit 3114 determines whether it is possible to secure a necessary transmission band between the transmitter 1 and the receiver 2 in each system. If the transmission band can be secured, the control request unit 3115 sends a control request to each control device so as to perform time-sharing control based on the determined schedule.

  Thereby, time allocation can be performed in each system so that the round-trip delay time when transmitting using TCP between the transmitter 1 and the receiver 2 is set to a predetermined value or less. It becomes possible. Therefore, it is possible to prevent the transmission rate from being lowered due to the increase in the round trip delay time.

  In this embodiment, a network that performs communication across three systems has been described. However, the number of systems arranged on the communication system path is not limited to this, and a network that includes three or more systems. It may be.

  In this embodiment, the communication control unit A3103 provided in the relay device A22 performs time-sharing control of the system A based on a control request from the control command device 25 (control request unit 3115), and is provided in the relay device B23. The configuration in which the communication control unit B3104 and the communication control unit C that perform the time-sharing control of the system B and the system C has been described, but is not limited thereto. For example, as shown in FIG. 6, the transmitter 1 (Server) performs time division control of the system A, the relay device B23 (Bridge 2) performs time division control of the system B, and the receiver performs the time division control of the system C. 2 (client) may be used. That is, the communication control unit A3103 that performs time division control of the system A is provided in the transmitter 1, the communication control unit A3104 that performs time division control of the system B is provided in the relay device B23, and the communication control that performs time division control of the system C. Part C may be provided in the receiver 2.

[Embodiment 4]
Still another embodiment of the present invention will be described. For convenience of explanation, members having the same functions as those in the first to third embodiments are denoted by the same reference numerals as those in the first to third embodiments, and description thereof is omitted.

  FIG. 7 is a block diagram of a network (network system) according to the present embodiment. As shown in this figure, the network according to this embodiment includes a transmitter A71, a transmitter B76, a relay device A (control device) 72, a relay device B (control device) 73, a receiver A74, a receiver B77, a control. The command device 25 is configured. Between the transmitter A71 and the relay device A72, the system A, between the relay device A72 and the relay device B73, the system B, between the relay device B73 and the receiver A74, the system C, and between the transmitter B76 and the relay device A72, Is connected to the system D, and the relay device B73 and the receiver B77 are connected to each other via the system E. In other words, this network is composed of five systems: system A, system B, system C, system D, and system E.

  Note that communication media that can secure a transmission band by time division control using TDMA are used for the systems A, B, and E, and communication media that cannot secure a transmission band are used for the systems C and D. . For example, a wireless LAN (802.11e) is used for the system A, a PLC is used for the system B, and a wireless LAN (802.11e) is used for the system E (however, the system A is not limited to this). For the system C and the system D, for example, Ethernet is used.

Stream transmission (Stream A) between the transmitter A 71 and the receiver A 74 via the system A → the system B → the system C, and the transmitter B 76 and the receiver via the system D → the system B → the system E Stream transmission (stream B) to / from B77 is performed. That is, system B is shared by stream A and stream B.
In the present embodiment, it is assumed that the system B is used as a so-called backbone that is commonly used when each device transmits and receives data in the network. Therefore, the transmission capacity of the system B is made larger than that of the system A and the system E (however, the present invention is not limited to this).

  The configurations of the transmitter A71 and the transmitter B76 are the same as those of the transmitter 1 shown in the first embodiment. The configurations of the receiver A 74 and the receiver B 77 are the same as those of the receiver 2 shown in the first embodiment.

  The relay device A72 is a device for connecting the systems A, B, and D to each other, and is a bridge device having a communication interface corresponding to a communication medium used for each system. In the present embodiment, the relay device A72 includes three communication interfaces of a wireless LAN, Ethernet, and PLC. Further, the relay device A72 includes a communication control unit A3103 that performs time division control of the system A and a communication control unit B3104 that performs time division control of the system B.

  The relay device B73 is a device for connecting the systems B, C, and E to each other, and is a bridge device that includes a communication interface corresponding to a communication medium used for each system. In the present embodiment, the relay device B73 includes three communication interfaces: wireless LAN, Ethernet, and PLC. Further, the relay device B 73 includes a communication control unit A 3104 that performs time division control of the system B and a communication control unit E that performs time division control of the system E. The configuration of the communication control unit E is the same as that of the communication control units A3103 and B3104.

  The relay device A72 and the relay device B73 need to perform time allocation of the systems A, B, and E at designated times or intervals in response to a control request from the control command device 25. Therefore, the relay device A 72 and the relay device B 73 synchronize their internal times with each other using a mechanism such as NTP (Network Time Protocol).

  The configuration of the control command device 25 is substantially the same as the configuration of the control command device 25 shown in the second embodiment. The control command device 25 acquires information on the usage status (communication state) of the systems A, B, and E from the relay device A72 and the relay device B73, and sends the information to the relay device A72 and the relay device B73 based on the acquired result. Requesting time division control by TDMA of each system.

  Next, the control unit 3102 of the control command device 25 assigns the transmission band to the stream A transmitted between the transmitter A 71 → the relay device A 72 → the relay device B 73 → the receiver A 74 and transmits it to the network system. A description will be given of processing when the transmission band is sequentially assigned to the stream B transmitted between the machine B76, the relay apparatus A72, the relay apparatus B73, and the receiver B77.

  When receiving a request for securing the transmission band for the stream A, the control unit 3102 (control request unit 3115) transmits the transmission band to the relay device A72 via the communication unit 3303 according to the flowchart illustrated in FIG. Send a control request. At this time, the allocation in the system A and the system B is larger in the transmission capacity of the system B than the transmission capacity of the system A, and the communication is performed in the direction of the system A → the system B. Here, the scheduling shown in the first embodiment is performed. Scheduling is performed by the method of Example 2. FIG. 23 is an explanatory diagram showing a state of time allocation in the system A and the system B at the time when the securing of the transmission band for the stream A is completed.

  When receiving a request for securing the transmission band for the stream B, the control unit 3102 (control request unit 3115), like the stream A, follows the communication unit 3303 according to the flowchart shown in FIG. Then, a transmission band control request is transmitted to the relay apparatus B73. As the scheduling method, the transmission capability of the system B is larger than the transmission capability of the system E, and communication is performed in the direction of the system B → the system E. Therefore, here, the method of the scheduling example 3 shown in the first embodiment is used.

  At this time, the system B is in a state where a part of time is allocated by the stream A. Therefore, when performing scheduling, the control unit 3102 (schedulability determination unit 3114) can secure a transmission amount necessary for transmission of the stream B by the idle time of the system B when the system B is used alone. Determine whether or not.

  If the transmission amount can be secured, the allocation time for the system B is determined first, and the allocation for the system E is determined so as to match the allocation time. FIG. 24 is a diagram illustrating a state of allocation of the system B and the system E in a state where the transmission band for the stream B has been secured.

  On the other hand, when it is determined that the transmission amount necessary for transmission of the stream B cannot be secured due to the idle time of the system B when the system B is used alone, the control unit 3102 (scheduling availability determination unit 3114) If the time allocation in the system B of the streams A and B is changed (if rescheduling is performed), it is determined whether or not the transmission amount necessary for the transmission of the streams A and B can be secured. If the transmission amount necessary for the streams A and B cannot be secured even after rescheduling, the control unit 3102 (scheduling availability determination unit 3114) determines that the transmission band necessary for communication cannot be secured, and The request destination (for example, user) is notified that the band cannot be secured, and the process is terminated.

  As described above, in the network according to the present embodiment, one system (system B) is shared by a plurality of streams (streams A and B). Then, the usage status acquisition unit 3113 of the control command device 25 acquires information on the usage status from each device (control device) that controls the TDMA-controllable system on the communication path, and whether scheduling is possible based on the result. The determination unit 3114 determines whether it is possible to secure a transmission band necessary for each stream in each system. Then, a control request is sent to a control device that performs time division control of each system so that time division control of each system is performed based on scheduling that can secure a transmission band.

  Thereby, in each stream, the round trip delay time of TCP ACK can be made a predetermined value or less. Therefore, it is possible to prevent a decrease in transmission rate due to an increase in the round trip delay time.

  In the present embodiment, an example in which a communication medium that cannot secure a transmission band is used as the system C and the system D has been described. However, the present invention is not limited to this. For example, the system C and / or the system D may be a communication medium that can secure a transmission band.

  For example, the system C may be the same system (communication medium) as the system A, and the system D may be the same system (communication multiple) as the system E. In this case, for example, time allocation as shown in FIG. 34 may be performed in each system. The scheduling example shown in FIG. 34 is an example in which the TDMA periods of the system A, the system B, and the system C match.

  In this schedule example, as shown in FIG. 34, in the system A, the system B, and the system C, the start time and the end time of the time allocation in the downstream direction and the upstream direction of the stream A match. Also, the uplink and downlink allocation times are set within time T.

  Therefore, after transmitting data from the transmitter A71, an ACK for the data arrives at the transmitter A71 within the time T. Thereby, since the round-trip delay time of ACK is T or less, it is possible to prevent the transmission rate from being lowered as the round-trip transmission delay of ACK increases.

  Further, the communication medium used for each system is not limited to the above example. For example, all systems may be configured with the same communication medium, all systems may be configured with different communication media, or other combinations may be used.

  In each of the above embodiments, when the control command device determines that predetermined scheduling cannot be performed (transmission time cannot be allocated), transmission time is not allocated.

  However, it is possible to calculate the round trip delay time RTT for an executable schedule (a combination of executable time allocations). Therefore, the Window Size W for obtaining the necessary transmission rate R may be calculated based on the round trip delay time RTT, and transmission may be performed with the calculated Window Size W.

  Specifically, the control unit 3102 provided in the control command device 25 is configured to execute a time-division control period in each system, a start time and an end time of downlink time allocation, and an uplink time allocation for executable schedules. A round trip time calculation unit is provided for calculating the round trip time RTT based on the start time and the end time. Further, the control unit 3102 is provided with a window size calculation unit that calculates Window Size W based on R = W / RTT. Further, the control unit 3102 determines whether or not the calculated window size W is a window size that can be processed by each device on the transmission path, and if it is a window size that can be processed, the transmitter is used to use the window size. A window size setting unit for notifying is provided. Thereby, the transmitter can secure the necessary transmission band by setting the Window Size based on the information notified from the control command device 25 (window size setting unit).

  Therefore, even in a network (system combination) in which the response confirmation cannot be transmitted in the originally requested round trip time, the transmission amount per unit time can be increased, so that a necessary transmission band can be secured.

  In each scheduling example shown in each of the above embodiments, the downlink time allocation and the uplink time allocation are provided once in one TDMA period, but the present invention is not limited to this. For example, when the control cycle of the communication medium (system) is large, a plurality of uplink time allocations and downlink time allocations may be performed within one TDMA cycle as shown in FIG.

  As shown in FIG. 35, when 5 times of time allocation in the downlink direction are provided in one cycle, for example, if Window Size is W = 4, 4 × 5 = 20 data can be transmitted in one cycle. On the other hand, in a configuration in which downlink time allocation and uplink time allocation are provided once in one TDMA period, only W = 4 data can be transmitted in one period. Therefore, when the control cycle of the communication medium (system) is not large, it is possible to improve the transmission rate by providing a plurality of time allocations in the uplink and downlink directions within one cycle.

  Also, a scheduling method for setting a plurality of uplink time allocations and downlink time allocations within one period may be used in combination with any of the scheduling methods described above. For example, a scheduling method for setting a plurality of uplink time allocations and downlink time allocations within one period is the same as that in scheduling example 4 shown in the first embodiment or scheduling example 12 shown in the third embodiment. If this is used as a time allocation method, even in a system with a large control cycle, the round-trip delay time of TCP ACK can be reduced to a predetermined value or less, and a decrease in transmission rate due to an increase in round-trip delay time can be prevented. .

  In addition, the scheduling method for setting a plurality of uplink time allocations and downlink time allocations within one period as described above performs communication using a single system between the transmitter and the receiver. It can also be applied to networks. In this case, even in a system with a large control cycle, the TCP ACK round trip delay time can be set to a predetermined value or less, and a decrease in transmission rate due to an increase in round trip delay time can be prevented.

  Further, in each of the above embodiments, the time allocation in the receiver → transmitter direction (upstream direction) is allocated as a transmission band for ACK, but the present invention is not limited to this. For example, ACK transmission may be performed in a contention period (CP) that can be shared with other data transmissions.

  Here, the contention period is a period during which the control device does not manage the transmission right of each device on the system. During this period, for example, an access method called DCF (distributed coordination function) is used. In DCF, each device on a network monitors whether data is being transmitted to a communication medium. When it is detected that a state in which no data is transmitted from any device continues for a predetermined period (a period referred to as DIFS), timing of a down timer called a back-off timer is started. The back-off timer is a down timer that starts from a random value within a predetermined range in each device. If the communication medium is idle when the back-off timer reaches 0 (if the state in which no data is transmitted from any device continues), the device can start data transmission. That is, a person with a short waiting time randomly determined can obtain the right to transmit data.

  A device that has obtained the right to transmit data can transmit data. When the data transmission is finished, the apparatus returns to the phase for monitoring whether or not a frame is transmitted to the communication medium, and the same thing is repeated.

  In IEEE802.11e, an access method called EDCF (enhanced distributed channel access function) obtained by extending DCF is used. This is because the size of the back-off timer is changed according to the type of data to be transmitted to adjust the priority of transmission according to the type of data to be transmitted, and the device that has obtained the right to transmit data continuously This is a method that adds a mechanism to transmit multiple data. In the contention period, either DCF or EDCF may be used.

  In addition, each block of the control instruction device in each of the above embodiments, in particular, the control unit 3102 and each block included therein is realized by software using a processor such as a CPU as described above.

  That is, the control instruction device includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. An object of the present invention is a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of a control instruction device, which is software that realizes the above-described functions, is recorded in a computer-readable manner, The program is supplied to the control command device, and the computer (or CPU or MPU) reads and executes the program code recorded on the recording medium.

  Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The control command device may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  In addition, each block of the control instruction device in each of the above embodiments, in particular, the control unit 3102 and each block included in the block is not limited to being realized using software, and may be configured by hardware logic. Good.

  The embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention is a network for transmitting data using a communication medium in which a transmission band is secured by time division, and after the transmission side apparatus receives a response confirmation of the transmitted data from the reception side apparatus, It can be applied to the network that can transmit the data.

It is a block diagram which shows the structure of the network concerning one Embodiment of this invention. It is a block diagram which shows the structure of the network concerning other embodiment of this invention. It is a block diagram which shows the modification of the network shown in FIG. It is a block diagram which shows the modification of the network shown in FIG. It is a block diagram which shows the structure of the network concerning further another embodiment of this invention. It is a block diagram which shows the modification of the network shown in FIG. It is a block diagram which shows the structure of the network concerning further another embodiment of this invention. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. It is explanatory drawing which shows an example of the scheduling method of the time division in the network shown in FIG. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 6 is an explanatory diagram illustrating an example of a time-sharing scheduling method in the network illustrated in FIG. 5. FIG. 8 is an explanatory diagram showing time allocation in the system A and the system B at the time when the securing of the transmission band for the stream A is completed in the network shown in FIG. 7. FIG. 8 is an explanatory diagram showing time allocation in the systems B and E in a state where the transmission band for the stream B has been secured in the network shown in FIG. 7. It is a figure showing the mode of the conventional transmission line by which the time division control was carried out by TDMA control. It is explanatory drawing which shows the relationship between Window Size and RTT, and a throughput in the conventional transmission line time-controlled by TDMA control. It is explanatory drawing which shows an example of the transmission state in the conventional network which transmits data in real time by TCP using TDMA control. It is explanatory drawing which shows an example of the conventional network which consists of several systems. It is explanatory drawing which shows the mode of the data transmission in the network of FIG. It is a block diagram which shows the internal structure of the relay apparatus with which the network shown in FIG. 1 is equipped. FIG. 31 is a flowchart showing a processing flow when the relay apparatus shown in FIG. 30 performs time division control by TDMA of each system provided in the network shown in FIG. 1. It is a block diagram showing the internal structure of the control command apparatus with which the network shown in FIG. 2 is equipped. FIG. 33 is a flowchart showing a flow of processing when the control instruction device shown in FIG. 32 makes a control request to a control device that performs time division control by TDMA of each system provided in the network shown in FIG. 2. FIG. 8 is an explanatory diagram showing an example of scheduling when the system A and the system D are wireless LAN 1 (802.11e) and the system C and the system E are wireless LAN 2 (802.11e) in the network shown in FIG. It is explanatory drawing which shows an example of the time-sharing scheduling method in the network of this invention.

Explanation of symbols

1,71,76 Transmitter (Transmitter)
2 Receiver (Receiver)
3 Relay device 22, 23, 72, 73 Relay device 25 Control command device (communication control device)
3101 Processing unit 3102 Control unit 3103, 3104 Communication control unit 3107 Protocol conversion unit 3111 Initialization determination unit 3112 Initialization request unit 3113 Usage status acquisition unit 3114 Scheduling availability determination unit 3115 Control request unit 3301 Processing unit

Claims (18)

A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. A time division control based on a schedule designated by itself is provided to a control device that is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and that performs time division control of each communication medium. A communication control device for performing
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Comprising a control means for setting the schedule by associating transmission time zone assignments in each communication medium ;
The control means includes
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. Providing a possible second time allocation at least once every predetermined time; and
The communication control device , wherein the schedule is set so that end times of the first time allocation in the respective communication media match and start times of the second time allocation match . The control means includes
The start times of the first time allocations in the communication media match, and
The communication control apparatus according to claim 1 , wherein the schedule is set so that end times of the second time allocation in the communication media coincide with each other. The control means includes
The start time of the first time allocation in each communication medium is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side,
Setting the schedule such that the end time of the second time allocation in each communication medium is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. The communication control device according to claim 1 . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. A time division control based on a schedule designated by itself is provided to a control device that is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and that performs time division control of each communication medium. A communication control device for performing
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Comprising a control means for setting the schedule by associating transmission time zone assignments in each communication medium ;
The control means includes
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
The communication control apparatus , wherein the schedule is set so that the start times of the first time allocations in the communication media match and the end times of the second time allocations match . The control means includes
The end time of the first time allocation in each communication medium is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side,
Setting the schedule such that the start time of the second time allocation in each communication medium is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. The communication control device according to claim 4 . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. A time division control based on a schedule designated by itself is provided to a control device that is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and that performs time division control of each communication medium. A communication control device for performing
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Comprising a control means for setting the schedule by associating transmission time zone assignments in each communication medium ;
The control means includes
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
In each communication medium, the start time of the first time allocation is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the first time allocation ends. The time is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the start time of the second time allocation is changed from the communication medium arranged on the reception device side to the transmission device. So that the end time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. A communication control apparatus characterized by setting the schedule . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. A time division control based on a schedule designated by itself is provided to a control device that is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and that performs time division control of each communication medium. A communication control device for performing
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Comprising a control means for setting the schedule by associating transmission time zone assignments in each communication medium ;
The control means includes
The transmission time zone allocation cycle in each communication medium is different for each communication medium,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
The end time of the first time allocation in each communication medium matches at least once every predetermined time, and the start time of the second time allocation matches at least once every predetermined time A communication control device that sets the schedule . The control means includes
The transmission time slot allocation period in each communication medium is sequentially 1 / m times (m is a natural number) from the communication medium arranged on the transmission apparatus side toward the communication medium arranged on the reception apparatus side. The communication control apparatus according to claim 7 , wherein the schedule is set. The control means includes
The transmission time zone allocation period in each communication medium is sequentially increased by a factor of n (n is a natural number) from the communication medium arranged on the transmission apparatus side to the communication medium arranged on the reception apparatus side. The communication control device according to claim 7 , wherein a schedule is set. A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. A time division control based on a schedule designated by itself is provided to a control device that is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and that performs time division control of each communication medium. A communication control device for performing
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Comprising a control means for setting the schedule by associating transmission time zone assignments in each communication medium ;
The control means includes
The transmission time zone allocation cycle in each communication medium is different for each communication medium,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
In each communication medium, the start time of the first time allocation is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the first time allocation ends. The time is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the start time of the second time allocation is changed from the communication medium arranged on the reception device side to the transmission device. So that the end time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. A communication control apparatus characterized by setting the schedule . The control means includes
11. The schedule according to claim 7 , wherein in each of the communication media, the schedule is set so that the first time allocation and the second time allocation are provided once for each predetermined time. The communication control apparatus according to any one of claims. A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. The communication control method is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and causes the control device that performs time-sharing control of each communication medium to perform time-sharing control. And
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Including a control step of controlling the control device based on a schedule associated with allocation of transmission time zones in each communication medium ,
In the control process,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
A communication control method, wherein the schedule is set so that end times of the first time allocation in the respective communication media match and start times of the second time allocation match . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. The communication control method is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and causes the control device that performs time-sharing control of each communication medium to perform time-sharing control. And
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Including a control step of controlling the control device based on a schedule associated with allocation of transmission time zones in each communication medium,
In the control process,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
A communication control method, wherein the schedule is set so that the start times of the first time allocation in the communication media coincide and the end times of the second time allocation coincide . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. The communication control method is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and causes the control device that performs time-sharing control of each communication medium to perform time-sharing control. And
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Including a control step of controlling the control device based on a schedule associated with allocation of transmission time zones in each communication medium ,
In the control process,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
In each communication medium, the start time of the first time allocation is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the first time allocation ends. The time is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the start time of the second time allocation is changed from the communication medium arranged on the reception device side to the transmission device. So that the end time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. A communication control method characterized by setting the schedule . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. The communication control method is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and causes the control device that performs time-sharing control of each communication medium to perform time-sharing control. And
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Including a control step of controlling the control device based on a schedule associated with allocation of transmission time zones in each communication medium ,
In the control process,
The transmission time zone allocation cycle in each communication medium is different for each communication medium,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
The end time of the first time allocation in each communication medium matches at least once every predetermined time, and the start time of the second time allocation matches at least once every predetermined time A communication control method characterized by setting the schedule . A network for transmitting data between a transmission device and a reception device via a plurality of communication media whose transmission time zones are controlled by time division, wherein the transmission device transmits data to the reception device. The communication control method is provided in a network capable of transmitting next data after receiving a response confirmation for the data from the receiving device, and causes the control device that performs time-sharing control of each communication medium to perform time-sharing control. And
The round trip delay time, which is the time from when the transmitting device transmits data to the receiving device until receiving a response confirmation for the data, is a predetermined time at which a necessary transmission rate can be obtained. Including a control step of controlling the control device based on a schedule associated with allocation of transmission time zones in each communication medium ,
In the control process,
The transmission time zone allocation cycle in each communication medium is different for each communication medium,
In each communication medium, a first time allocation for transmitting data transmitted from the transmission device in the direction of the reception device and a response confirmation for the data transmitted from the reception device may be transmitted in the direction of the transmission device. A possible second time allocation is provided at least once every predetermined time period; and
In each communication medium, the start time of the first time allocation is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the first time allocation ends. The time is sequentially delayed from the communication medium arranged on the transmission device side toward the communication medium arranged on the reception device side, and the start time of the second time allocation is changed from the communication medium arranged on the reception device side to the transmission device. So that the end time of the second time allocation is sequentially delayed from the communication medium arranged on the receiving device side toward the communication medium arranged on the transmitting device side. A communication control method characterized by setting the schedule . A communication control program for operating the communication control device according to any one of claims 1 to 11 , wherein the communication control program causes a computer to function as the control means. A computer-readable recording medium on which the communication control program according to claim 17 is recorded.

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