JP2009105662A - Multi-hop communication system, multi-hop communication method, terminal device and repeating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately decide the size of a buffer holding received data in a terminal for receiving data, when there is a repeating device that performs aggregation. <P>SOLUTION: A transmitting side terminal 201 periodically transmits data, and the repeater 202 relays the data. When the data transmitted from the transmission-side terminal 201 are received, a receiving terminal 203 temporarily stores the data into a buffer. A buffer determining means 204 provided in the receiving terminal 203 determines the size of the buffer, on the basis of a receiving interval of sets of data aggregated into one piece of aggregated data by the repeater. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multihop communication system, a multihop communication method, a terminal device, a relay device, a program for a terminal device, and a program for a relay device, and in particular, can manage the size of a buffer that temporarily stores received data in the terminal device The present invention relates to a multihop communication system, a multihop communication method, a terminal device, a relay device, a terminal device program, and a relay device program applied to the multihop communication system.

  In real-time communication such as VoIP (Voice over Internet Protocol), a technique for maintaining the reproduction quality of audio and the like by absorbing a variation in the arrival interval of data generated in a network with a buffer is known. Hereinafter, a case where VoIP communication is performed will be described as an example.

  The reproduction quality is affected by how the size of the buffer is estimated. For example, when the size of the buffer is simply increased, the playback delay increases and the playback quality deteriorates. Conversely, if the buffer is estimated to be small, the buffer becomes empty or full due to fluctuations in the data arrival interval, and the reproduction quality deteriorates.

  Therefore, various buffer management methods for dynamically estimating the size of the buffer according to the arrival interval of data have been proposed. For example, Patent Documents 1 and 2 describe a method for determining the size of a buffer based on average delay jitter. If the size of the buffer is determined in this way, even if the arrival interval of VoIP data varies, the difference in arrival interval can be absorbed by the buffer so that the reproduction quality is not adversely affected. it can. Patent Documents 3 and 4 describe an adjustment method for detecting the silent data in the buffer and thinning or inserting them to keep the number of data in the buffer constant.

  Further, in a wireless communication system such as IEEE 802.11, a technique called aggregation is known in which a plurality of data is transmitted as a single data. In aggregation, a plurality of pieces of data are collectively transmitted and transmitted, thereby improving the throughput in wireless communication. An example of a wireless communication apparatus that employs aggregation is described in Patent Document 5. The wireless communication device described in Patent Document 5 forms a long data part in which MPDUs (MAC Protocol Data Units) are aggregated, and forms an aggregation frame with one header part added to the data part.

Japanese Patent Laid-Open No. 2004-72242 JP 2006-50488 A JP 2006-238445 A US Pat. No. 6,658,027 JP 2006-191279 A

  When aggregation is applied to VoIP communication in a wireless network, a large fluctuation occurs in data arrival intervals. The occurrence of this variation will be described. When aggregation is performed, a delay occurs because the relay apparatus waits for data for aggregation in a queue for a certain period of time for the purpose of aggregating a plurality of data. When the waiting time is equal to or longer than the data transmission interval at the data transmission source, a plurality of data transmitted from the same transmission source are collected into one data. Then, the relay device transmits the aggregated data to the destination receiving terminal. The arrival interval at which each data arrives at the receiving terminal may be almost zero or may be the waiting time for aggregation, and varies greatly. That is, the reception interval of each data collected into one data is almost zero. In addition, each piece of data collected into one piece of data and each piece of data collected into one piece of data after that are transmitted from the relay apparatus with an interval corresponding to the waiting time for aggregation. Therefore, the time interval at which both arrive at the receiving terminal is substantially the same as the waiting time for aggregation, and is significantly different from the above “0”.

  FIG. 12 is an explanatory diagram illustrating an example of a change in a time interval at which data arrives at a terminal that receives data when aggregation is applied. As shown in FIG. 12, when aggregation is applied, the data arrival interval at the destination terminal varies greatly.

  As described above, since the arrival interval when each data transmitted from the transmission source arrives at the receiving terminal greatly varies, the methods described in Patent Documents 1 and 2 (the size of the buffer is determined based on the average delay jitter). If aggregation is applied to the determining method), the buffer will become larger than necessary, or the buffer will be too small and overflow will occur. As a result, the reproduction quality is deteriorated.

  As a technique for keeping the buffer size constant, there is a technique (Patent Documents 3 and 4) for inserting or deleting silence data. Since this technology uses a silent state, it is required that the size of the buffer is appropriate to some extent. For this reason, it is impossible to solve the fluctuation of the arrival interval at the receiving terminal when the aggregation is applied.

  Therefore, in the present invention, when there is a relay device that performs aggregation, a multi-hop communication system that can appropriately determine the size of a buffer that holds received data in a terminal that receives data, and the multi-hop communication An object is to provide a multi-hop communication method, a terminal device, a relay device, a terminal device program, and a relay device program applied to the system.

  The multi-hop communication system of the present invention is a multi-hop communication system in which a relay device relays data transmitted and received between terminals, and a transmission source terminal that periodically transmits data and temporarily stores received data in a buffer Receiving terminal, and at least one relay device that relays data between the transmission source terminal and the receiving terminal, the receiving terminal receiving interval of a set of data aggregated into one aggregated data by the relay device And buffer determining means for determining the size of the buffer based on the above.

  The multi-hop communication method according to the present invention is applied to a multi-hop communication applied to a multi-hop communication system in which a relay device relays data transmitted and received between terminals, and a receiving terminal that receives data temporarily stores data received in a buffer. A method in which a source terminal periodically transmits data, and a receiving terminal determines a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device. Features.

  A receiving terminal of the present invention is a receiving terminal that receives data transmitted from a transmission source terminal that periodically transmits data via a relay device, and temporarily stores the received data in a buffer. Buffer determining means for determining the size of the buffer based on the reception interval of a set of data aggregated into one aggregated data is provided.

  The relay device of the present invention is a relay device that relays data by aggregating received data into one aggregated data and transmitting the aggregated data, and stores route information indicating a communication path of a multi-hop communication system A route storage unit that performs data storage, a destination included in the received data, and route information, an aggregation availability determination unit that determines whether to aggregate data, a data holding unit that holds data determined to be aggregated, and a fixed amount An aggregation unit that aggregates each data held in the data holding unit into one aggregated data every time, and identification information that identifies the operation when the aggregation unit performs an operation of aggregating each data into aggregated data. Identification information adding means for adding common identification information to each piece of data to be aggregated into one aggregated data, and generating aggregated data determined to aggregate the data If it is determined that the aggregated data is to be transmitted, and if it is determined not to aggregate the data, the transmission means for transmitting the individual data and the division for dividing the aggregated data into the individual data when the aggregated data is received Means for determining whether or not the aggregated data is divided by the dividing means, and determining whether or not to aggregate the divided individual data.

  The reception terminal program of the present invention is a computer used as a reception terminal that receives data transmitted from a transmission source terminal that periodically transmits data via a relay device and temporarily stores the received data in a buffer. A program for a receiving terminal, which causes a computer to execute buffer determination processing for determining a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device And

  The relay device program of the present invention is a relay device program installed in a computer that aggregates received data into one aggregated data and relays the data by transmitting the aggregated data. Aggregation determination processing for determining whether to aggregate data from the destination included in the data and route information indicating the communication path of the multi-hop communication system, data retention processing for retaining data determined to be aggregated, constant Aggregation processing that aggregates each stored data into one aggregated data every time, identification information that identifies the aggregation processing when executing the aggregation processing is defined, and each data aggregated into one aggregated data Identification information addition processing for adding common identification information to the aggregated data, if aggregated data is generated when it is determined that the data is aggregated When it is determined that the data is not aggregated, a transmission process for transmitting individual data and a division process for dividing the aggregated data into individual data when the aggregated data is received are executed. When the aggregated data is divided, the aggregation possibility determination process is executed for each divided data.

  According to the present invention, the buffer size is determined based on the reception interval of the set of data aggregated into one aggregated data by the relay device, so that the buffer size can be appropriately determined.

Hereinafter, embodiments of the present invention will be described.
The multi-hop communication system of the present invention includes a transmission source terminal that periodically transmits data, a reception terminal that receives data, and at least one relay device that relays data between the transmission source terminal and the reception terminal. Prepare. However, in the first embodiment described below, two or more relay devices are provided.

Embodiment 1. FIG.
FIG. 1 is an explanatory view showing a first embodiment of the present invention. The multi-hop communication system includes a transmission source terminal 101, a reception terminal 104, and two or more relay devices. A range indicated by a dotted line in FIG. 1 indicates a communication range of each terminal or relay device. Although FIG. 1 shows the relay apparatuses 102 and 103, the number of relay apparatuses may be two or more. In the following description, the terminal 101 is described as a transmission source terminal that transmits data, and the terminal 104 is a reception terminal that receives data. However, the terminal 104 is a transmission source terminal, the terminal 101 is a reception terminal, 104 may send and receive data to and from each other.

  The transmission source terminal 101 periodically transmits data. The data transmitted from the transmission source terminal 101 may be a packet or a frame.

  The receiving terminal 104 temporarily stores data received from the transmission source terminal 101 via the relay apparatuses 102 and 103 in a buffer and processes the data. As an example of this process, there is an audio reproduction process in VoIP. That is, terminals 101 and 104 perform VoIP communication, and receiving terminal 104 temporarily stores received data in a buffer and reproduces the data as audio.

  Further, a relay device other than the relay device 103 that directly transmits data to the receiving terminal 104 performs aggregation on the data and transmits the data to the next relay device. In the example illustrated in FIG. 1, the relay apparatuses 102 other than the relay apparatus 103 that transmits data directly to the receiving terminal 104 hold the data received from the transmission source terminal 101, and hold the held data 1 every fixed time. The data is aggregated into one aggregated data and transmitted to the next relay apparatus 103. Hereinafter, data obtained by consolidating a plurality of data into one is referred to as aggregated data. For example, when the relay apparatus 102 performs aggregation on packets received from the transmission source terminal 101 and aggregates a plurality of packets into one packet, the aggregated one packet is referred to as aggregated data.

  In the present embodiment, it is assumed that the terminals 101 and 104 do not have a function of dividing the aggregated data into individual data.

  The relay apparatus 102 that directly receives data from the transmission source terminal 101 receives individual data from the transmission source terminal 101, and transmits aggregated data obtained by aggregating the data to the next relay apparatus.

  The relay device 103 that transmits data directly to the receiving terminal 104 divides the aggregated data received from other relay devices into individual data, and transmits the divided individual data to the receiving terminal 104.

  In FIG. 1, only two relay apparatuses are illustrated, but there may be a relay apparatus that relays data between the relay apparatus 102 and the relay apparatus 103. The relay device receives the aggregated data from another relay device and relays the data to the next relay device. When such a relay device receives the aggregated data, it divides the aggregated data into individual data, retains the individual data after the division, aggregates the retained data at regular intervals, and repeats the next relay Send to device. This division is called deaggregation. In addition, the time interval which performs aggregation and transmits aggregated data may differ for every relay apparatus.

  In the present embodiment, relay apparatuses other than the relay apparatus 103 that directly transmit data to the receiving terminal 104 perform aggregation and transmit aggregated data. Each relay device that performs aggregation adds identification information (hereinafter referred to as an aggregation ID) for identifying an aggregation operation performed at regular intervals to individual data to be aggregated, and the data is converted into one aggregated data. Summarize. The relay device adds a common aggregation ID to each piece of data aggregated into one aggregated data.

  The individual data to which the common aggregation ID is added is aggregated together at the relay node.

  In addition, as described above, a relay device that relays data between relay devices receives aggregated data from other relay devices, divides the aggregated data into individual data, and then again converts the individual data into aggregated data. To aggregate. Also in this case, the relay device determines an aggregation ID and adds it to individual data. In this case, the relay device replaces the aggregation ID added by the previous relay device with a new aggregation ID.

  Since the relay apparatus 102 that performs aggregation transmits aggregated data at regular intervals, the aggregated data arrives at the relay apparatus 103 with a time interval. Then, when the relay apparatus 103 that directly transmits data to the receiving terminal 104 receives one piece of aggregated data, the relay apparatus 103 divides the aggregated data into individual data and transmits the data to the receiving terminal 104. Accordingly, when receiving a plurality of data to which the same aggregation ID is added, the receiving terminal 104 receives a plurality of data to which another aggregation ID is added after a lapse of time. The receiving terminal 104 determines the size of the buffer based on the reception interval of a set of data with different aggregation IDs. For example, the receiving terminal 104 receives a plurality of data to which another aggregation ID of “2” is added after a lapse of time after receiving a plurality of data to which an aggregation ID of “1” is added. The receiving terminal 104 determines the size of the buffer based on the time interval from receiving a plurality of pieces of data with a certain aggregation ID until receiving a plurality of pieces of data with another aggregation ID.

  If the buffer size is determined in this way, the buffer size is determined based on the interval at which the receiving terminal 104 receives a set of data aggregated into one aggregated data by the relay device 102. Become.

  FIG. 2 is a block diagram illustrating a configuration example of the relay apparatus. A relay apparatus 300 shown in FIG. 2 is used as each of the relay apparatuses 102 and 103 shown in FIG. The relay device includes a wireless communication unit 301, a data processing unit 302, and an aggregation processing unit 303.

  The wireless communication unit 301 has one or a plurality of wireless communication interfaces, and transmits / receives data to / from other nodes.

  The data processing unit 302 performs transfer processing of received data. Hereinafter, the processing performed by the data processing unit 302 will be specifically described.

  The data processing unit 302 stores route information indicating a communication route of the multihop communication system in advance. The route information is information that allows the relay device to derive the next node to which the data should be transferred from the destination address included in the received data (eg, packet, frame, etc.). For example, the route information may be information indicating a correspondence relationship between the destination address and a node to which the relay device should transfer data.

  The data processing unit 302 determines whether to aggregate data from the destination address included in the received data and the route information. For example, the next node to which the data is to be transferred is specified from the destination address and the route information, and if the node is a relay device, it is determined that the data is aggregated. If the next node to which data is to be transferred is the receiving terminal 104, it is determined that the data is not aggregated.

  In addition, when the data processing unit 302 receives aggregated data from another relay apparatus, the data processing unit 302 divides the aggregated data into individual data (individual data transmitted by the transmission source terminal).

  When the data processing unit 302 determines whether or not to aggregate data, if individual data is received from the transmission source terminal 101, whether or not the data is aggregated for each individual data. Determine. When the aggregated data is received and the aggregated data is divided into individual data, it is determined whether or not the data is aggregated with respect to the divided data.

  The data processing unit 302 causes the aggregation processing unit 303 to hold the data determined to be aggregated.

  The aggregation processing unit 303 holds the data determined to be aggregated until the data is aggregated and transmitted. Then, the aggregation processing unit 303 aggregates the stored data into one aggregated data at regular time intervals. The aggregation processing unit 303 performs an operation of aggregating each data at fixed time intervals, but determines one aggregation ID for identifying each aggregation operation performed periodically when one aggregation operation is executed. . Then, the aggregation processing unit 303 adds the determined aggregation ID to each piece of data aggregated into one aggregated data. Therefore, at this time, the aggregation processing unit 303 adds a common aggregation ID to each data.

  When the aggregation processing unit 303 generates the aggregated data, the aggregation processing unit 303 transmits the aggregated data to the next node to be transferred via the wireless communication unit 301. Note that, since the aggregated data is transmitted when the data is aggregated, the transmission interval of the aggregated data by the relay device is the same as the interval for performing the aggregation operation. Further, the data processing unit 302 transmits the data determined not to be aggregated to the next node to which the data is to be transferred via the wireless communication unit 301.

  The wireless communication unit 301 transmits aggregated data generated as a result of determining that data is aggregated or individual data that is not aggregated as a result of being determined not to aggregate to the next node to be transferred.

  The data processing unit 302 and the aggregation processing unit 303 are realized by a CPU that operates according to a program (relay device program), for example. In this case, the relay device may store the relay device program in a storage device (not shown), and the CPU may read the relay device program and operate according to the relay device program.

  FIG. 3 is a block diagram illustrating a configuration example of the receiving terminal. The reception terminal 104 includes a transmission interval holding unit 351, a reception interval measurement unit 352, an aggregation interval estimation unit 353, a buffer determination unit 354, a reception interval variation determination unit 355, and a data storage device 356.

  The transmission interval holding unit 351 holds information on the data transmission interval of the transmission source terminal 101 (see FIG. 1) that periodically transmits data and information on the size of data transmitted by the transmission source terminal 101. The receiving terminal 104 includes negotiation means (not shown) that negotiates with the transmission source terminal 101 before the start of data transmission / reception, and the negotiation means determines whether the data transmission interval of the transmission source terminal 101 or the transmission source terminal is negotiated. The size of individual data to be transmitted is determined, and the information is stored in the transmission interval holding unit 351.

  The reception interval measurement unit 352 measures the reception interval of a set of data with different added aggregation IDs, and obtains the average time of the reception intervals. For example, the time interval from when a plurality of data with an aggregation ID “1” is received to when a plurality of data with an aggregation ID “2” is received is measured. Similarly, the reception interval measurement unit 352 continues to measure the reception interval and obtains the average of the reception intervals.

  Note that the reception interval measurement unit 352 measures the reception interval of each data set, using, for example, the reception time of the plurality of data as the average time of the reception times of the plurality of data to which the common aggregation ID is added. That's fine.

  The data storage device 356 is a storage device used as a buffer for temporarily storing received data. The capacity used as the buffer is determined by the buffer determination unit 354.

  The buffer determination unit 354 is a size of a buffer for temporarily storing received data based on an average of reception intervals obtained by the reception interval measurement unit 352 (an average of reception intervals of a set of data having different aggregation IDs). To decide. That is, the capacity used as a buffer in the data storage device 356 is determined.

  When the size of the buffer to be prepared is V, the number of data to be kept in the buffer is N, and the size of each data transmitted from the transmission source terminal is L, the size of the buffer to be prepared V is as follows: It is expressed by a formula.

  V = N × L

  Further, the number N of data retained in the buffer is expressed by the following equation, where I is the average of the reception intervals obtained by the reception interval measuring unit 352 and P is the data transmission interval of the transmission source terminal 101.

  N = I / P

  Therefore, the size V of the buffer to be prepared is represented by (I / P) × L. The buffer determination unit 354 reads the data transmission interval P of the transmission source terminal 101 and the size L of each data transmitted from the transmission source terminal from the transmission interval holding unit 351, and receives the reception interval obtained by the reception interval measurement unit 352. The size of the buffer may be determined by calculating (I / P) × L using the average I. That is, the result of dividing the average I of the reception intervals obtained by the reception interval measurement unit 352 by the data transmission interval P of the transmission source terminal 101 may be multiplied by the size L of each data.

  For example, assume that the packet size transmitted from the transmission source terminal 101 is 200 bytes, and the data transmission interval of the transmission source terminal 101 is 10 msec. Then, it is assumed that the average I of the reception intervals obtained by the reception interval measurement unit 352 is 30 msec. In this case, the buffer determination unit 354 determines the size of the buffer as (30/10) × 200 = 600 bytes.

  However, the buffer determination unit 354 may determine the size of the buffer by other methods.

  The aggregation interval estimation unit 353 calculates the time interval of the aggregation operation by the relay device based on the number of data to which the common aggregation ID is added and the data transmission interval of the transmission source terminal 101. Specifically, the aggregation interval estimation unit 353 counts the number of data to which a common aggregation ID is added from the received data, and calculates the product of the value and the data transmission interval of the transmission source terminal 101 as an aggregation operation. What is necessary is just to obtain | require as a time interval. The time interval of this aggregation operation is the time interval in the relay device 102 immediately before the relay device 103 that directly transmits data to the receiving terminal 104.

  For example, it is assumed that the number of data to which the same aggregation ID is added is 3, and the data transmission interval of the transmission source terminal 101 is 10 msec. At this time, the aggregation interval estimation unit 353 estimates the time interval of the aggregation operation by the relay device as 3 × 10 = 30 msec.

  The reception interval variation determination unit 355 determines whether or not the variation in the reception interval at which the receiving terminal 104 receives data is caused by the communication network. Specifically, the reception interval variation determination unit 355 is estimated by the average of the reception intervals obtained by the reception interval measurement unit 352 (the average of the reception intervals of a set of data having different aggregation IDs) and the aggregation interval estimation unit 353. If the difference with the aggregation operation interval is greater than or equal to a predetermined threshold value, it is determined that the reception interval has changed due to the communication network. If the calculated difference is less than a predetermined threshold, it is determined that there is no change in the reception interval due to the communication network. Even when there is no change in the reception interval due to the communication network, a plurality of data with a common aggregation ID is received, and then a plurality of data is similarly received after a lapse of time. Thus, the reception interval of each piece of data fluctuates, but this fluctuation is caused by aggregation by the relay device. Therefore, if the calculated difference is less than the threshold value, the reception interval fluctuation determination unit 355 determines that a fluctuation caused by aggregation occurs, not a fluctuation caused by the communication network.

  If there is no fluctuation in the reception interval due to the communication network, and the fluctuation in the data reception interval is mainly due to aggregation, and the fluctuation is larger than the predetermined fluctuation amount, the transmission source terminal 101 and the reception The terminal 104 may change the codec and change the data size to be transmitted / received so that the data transmission interval at the transmission source terminal is increased. Note that there is a correlation between the data transmission interval and the size of data to be transmitted / received. For example, G. In 711, as shown in FIG. 4, the packet size increases as the data transmission interval increases. In this case, if the packet size is greatly changed, the data transmission / reception interval also increases.

  In addition, when there is a change in the reception interval due to the communication network, the receiving terminal 104 requests data path switching, secures bandwidth by bandwidth reservation, or requests priority control for the communication network. You may do.

  The reception interval measurement unit 352, the aggregation interval estimation unit 353, the buffer determination unit 354, and the reception interval variation determination unit 355 are realized by a CPU that operates according to a program (reception terminal program), for example. In this case, the receiving terminal 104 may store the receiving terminal program in the storage device, and the CPU may read the receiving terminal program and operate according to the receiving terminal program.

Next, the operation will be described.
FIG. 5 is an explanatory diagram illustrating an operation in which the terminals 101 and 104 and the relay apparatuses 102 and 103 illustrated in FIG. 1 transmit and receive data. The transmission source terminal 101 periodically transmits data including the address of the reception terminal 104 as a destination address (step S1).

  The relay device 102 aggregates and transmits the individual data periodically transmitted from the transmission source terminal 101 to the relay device 103 (step S2). In step S2, the relay apparatus 102 specifically operates as follows. The data processing unit 302 of the relay device 102 determines that the data is to be transferred to the relay device 103 from the destination address of each received data and the stored route information, and the next node to be transferred is not the receiving terminal. Therefore, it is determined that the data is aggregated, and the received individual data is held in the aggregation processing unit 303. The aggregation processing unit 303 aggregates (aggregates) each stored data into one aggregated data at regular time intervals. During this fixed time, in order to collect the data to be aggregated, it waits without performing the aggregation operation. When this aggregation operation is performed, the aggregation processing unit 303 determines an aggregation ID and adds the aggregation ID to individual data aggregated into one aggregated data. Then, the individual data is aggregated into one aggregated data. The aggregation processing unit 303 transmits the aggregated data to the relay device 103 via the wireless communication unit 301. The relay apparatus 102 performs this operation at regular intervals.

  When the relay device 103 receives the aggregated data from the relay device 102, the relay device 103 performs division (deaggregation) on the aggregated data, and transmits the divided individual data to the reception terminal 104 (step S3). In step S3, the relay apparatus 103 specifically operates as follows. The data processing unit 302 of the relay device 103 divides the aggregated data received from the relay device 102 into individual data. Then, based on the destination address included in the data and the stored route information, it is determined that the data is to be transmitted to the receiving terminal 104, and the next node to be transferred is the receiving terminal. judge. The data processing unit 302 transmits the data to the receiving terminal 104 via the wireless communication unit 301.

  The receiving terminal 104 determines in advance the size L of individual data transmitted by the transmission source terminal 101 and the data transmission interval P of the transmission source terminal 101 by negotiation with the transmission source terminal 101, and transmits a transmission interval holding unit 351 (FIG. 3). The reception interval measurement unit 352 of the reception terminal 104 measures the reception interval of a set of data with different added aggregation IDs, and calculates the average time I of the reception intervals. Next, the buffer determination unit 354 calculates (I / P) × L using the above L, P, and I, and determines the calculation result as the size of the buffer.

  Also, the receiving terminal 104 holds the received data in a buffer.

  Further, the aggregation interval estimation unit 353 of the receiving terminal 353 counts the number of data to which a common aggregation ID is added, calculates the product of the value and P (data transmission interval), and the calculation result is the relay device. Estimated as the time interval of the aggregation operation at. The reception interval variation determination unit 355 obtains a difference between the time interval of the aggregation operation and I (average of reception intervals of a set of data having different aggregation IDs). If the difference is equal to or greater than the threshold, reception interval variation determination section 355 determines that reception interval variation due to the communication network has occurred. In this case, the receiving terminal 104 may perform an operation such as a request for switching the data path described above. If the calculated difference is less than the threshold value, the reception interval variation determination unit 355 determines that the reception interval variation due to the communication network has not occurred, and the reception interval variation is mainly due to aggregation. In this case, if the variation in the reception interval of individual data is large, each terminal 101, 104 may change the data size to be transmitted / received as described above.

  A specific example of the operation of the present invention will be shown. In the specific example shown below, it is assumed that a relay device (referred to as relay device 150) that relays data between the relay device 102 and the relay device 103 shown in FIG. 1 is provided. FIG. 6 is an explanatory diagram illustrating an operation in which the transmission source terminal, each relay device, and the reception terminal perform real-time communication such as VoIP.

  The transmission source terminal 101 periodically transmits a frame whose destination address is the address of the reception terminal 104 (step S11).

  The relay apparatus 102 performs frame aggregation to improve the utilization rate of the radio link, and transmits the aggregated data aggregated into one frame to the relay apparatus 150 (step S12). In step S12, the relay apparatus 102 specifically operates as follows. The data processing unit 302 of the relay apparatus 102 determines that the frame is to be transferred to the relay apparatus 150 from the received destination address of each received frame and the stored route information, and the next node to be transferred is not the receiving terminal. The data is determined to be aggregated, and the received individual data is held in the aggregation processing unit 303. The aggregation processing unit 303 aggregates frames every Xmsec. During Xmsec from the aggregation operation to the next aggregation operation, the aggregation processing unit 303 stands by without performing the aggregation operation. Meanwhile, the number of individual frames to be aggregated increases.

  The aggregation processing unit 303 determines an aggregation ID when performing aggregation. For example, the initial value of the aggregation ID is set to “0”, the aggregation ID is incremented for each aggregation operation, and when the maximum value that can be expressed as the aggregation ID is exceeded, the value of the aggregation ID is returned to the initial value “0”. Increment again. However, another method of determining the aggregation ID may be used.

  The aggregation processing unit 303 adds the determined aggregation ID to each frame to be aggregated. In this example, since terminals communicate with each other using RTP (Real-time Transport Protocol), any field of RTP Header Extension, CSRC, or CCRC may be added with an aggregation ID.

  When the aggregation processing unit 303 aggregates the frames to which the aggregation ID is added into one frame, the aggregation processing unit 303 transmits the aggregated frame to the relay device 150 via the wireless communication unit 301.

  The relay device 150 divides the aggregated data (frame) received from the relay device 120 into individual frames, performs aggregation again, and transfers the aggregated data (frame) to the relay device 103 according to the destination address (step S13). In step S13, the relay device 150 specifically operates as follows. When the data processing unit 302 of the relay device 150 receives from the relay device 102 a frame in which a plurality of frames are aggregated into one, the data processing unit 302 divides the frame into individual frames. Then, the data processing unit 302 determines that the frame is to be transferred to the relay device 103 from the destination address of the frame and the stored route information, and the next node to be transferred is not the receiving terminal. Determination is made, and the individual data after the division is held in the aggregation processing unit 303. Assume that the aggregation processing unit 303 of the relay device 150 aggregates frames every Ymsec. During Ymsec from the aggregation operation to the next aggregation operation, the aggregation processing unit 303 waits without performing the aggregation operation, and the number of individual frames to be aggregated increases during that time.

  The aggregation processing unit 303 of the relay device 150 determines the aggregation ID, adds it to each frame, and aggregates the frames into one frame. Since the aggregation ID is determined independently by each relay device, the relay device 150 may increment the initial value of the aggregation ID from “0” as “0”. In addition, an aggregation ID has already been added by the relay apparatus 102 to each divided frame. The aggregation processing unit 303 of the relay device 150 rewrites the aggregation ID added to the frame to a newly determined aggregation ID.

  The aggregation processing unit 303 of the relay device 150 transmits the aggregated frame to the relay device 103 via the wireless communication unit 301.

  When the relay device 103 receives the aggregated data (frame) from the relay device 150, the relay device 103 divides the frame into individual frames, and transmits the divided individual data to the receiving terminal 104 (step S14). In step S14, the relay apparatus 103 specifically operates as follows. The data processing unit 302 of the relay device 103 divides the frame received from the relay device 150 into individual frames. Then, the data processing unit 302 determines that the data is to be transmitted to the receiving terminal 104 from the destination address of the frame and the stored route information, and does not aggregate the data because the next node to be transferred is the receiving terminal. Is determined. The data processing unit 302 transmits the data to the receiving terminal 104 via the wireless communication unit 301.

  Through the operations of the transmission source terminal and each relay device as described above, the reception terminal 104 receives a plurality of frames to which a common aggregation ID is added, and receives a plurality of similar frames again after a lapse of time. Repeat to do. As described above, the receiving terminal 104 uses L (frame length in this example), P (data transmission interval), and I (in this example, the average reception interval of a set of frames having different aggregation IDs). To determine the size of the buffer.

  Also, the receiving terminal 104 performs processing after temporarily storing the received frame in a buffer. For example, in the case of VoIP, audio reproduction processing is performed.

  Further, as described above, the receiving terminal 104 estimates the time interval of the aggregation operation in the relay device 150, and the difference between the time interval and I (the average of the reception intervals of a set of frames with different aggregation IDs). Then, it is determined whether or not the reception interval varies due to the communication network. Depending on the determination result, a data path switching request or the like may be made, or a frame size to be transmitted / received may be changed.

  Even if the interval of the aggregation operation in each relay device that aggregates data is different, the receiving terminal 104 can obtain the reception interval of the set of frames from the aggregation ID added by the relay device 150. FIG. 7 is an explanatory diagram schematically illustrating a reception interval of a data set at a receiving terminal when aggregation is performed by a plurality of relay apparatuses. FIG. 7A shows a case where X is 20 msec, Y is 40 msec, and X <Y. FIG. 7B shows a case where X is 40 msec, Y is 20 msec, and X> Y. In any case, the receiving terminal 104 can obtain the reception interval of the data set.

  Further, in the specific example described with reference to FIG. 6, the case where the transmission source terminal 101 transmits a frame as data is taken as an example, but the same applies to the case where the packet is not a frame but a communication data unit. is there.

  In the above example, the aggregation ID is added to the RTP header. However, the relay apparatus (aggregation processing unit 303) may add the DSCP (TOS Field) of the IP header. A unique header may be used.

  In the above example, the aggregation ID is incremented, and when the maximum value that can be expressed as the aggregation ID is exceeded (when the maximum value that can be expressed by the bit length expressing the aggregation ID is exceeded), the aggregation ID is set to “0”. The case where it returns to "is shown. An ID for identifying a relay apparatus that performs aggregation may be represented by a predetermined number of bits higher in bit length that represents the aggregation ID. Then, the aggregation ID may be incremented from “0” with the lower bits, and returned to “0” when the aggregation ID cannot be expressed with the lower bits. By including the relay device ID in the aggregation ID in this way, the receiving terminal 104 can finally determine which relay device has performed the aggregation.

  Further, when the aggregation ID is added to the DSCP (TOS Field) of the IP header, the number of bits for expressing the aggregation ID is limited. In this case, the aggregation processing unit 303 may store the destination IP address and the destination MAC address of each data to be aggregated, and manage the aggregation ID for each destination address. That is, the aggregation ID may be incremented from the initial value for each destination address. Even if the number of bits that can represent the aggregation ID is limited, the aggregation ID is managed for each destination address, and the receiving terminal can obtain the reception interval of the data set.

  According to this embodiment, when the relay device aggregates individual data, the aggregation ID for identifying the aggregation operation is added to the data and aggregated. As a result, the receiving terminal receives the data to which the aggregation ID is added, so that the data can be distinguished based on the aggregation ID. Then, it is possible to measure the reception interval of a set of data with different added aggregation IDs and determine the size of the buffer based on the reception interval. FIG. 8 is an explanatory diagram showing a reception interval of a set of data having different aggregation IDs. If there is no data delay due to the communication network, the reception interval of a set of data with different aggregation IDs is constant as shown in FIG. In the present invention, a set of data to which a common aggregation ID is added is regarded as one large piece of data, and the size of the buffer is determined based on the reception interval of sets with different aggregation IDs. As shown in FIG. 8, the reception intervals of sets with different aggregation IDs are constant if there is no data delay due to the communication network, so that the size of the buffer can be determined appropriately.

Embodiment 2. FIG.
The multihop communication system according to the second embodiment includes a transmission source terminal, a relay device, and a reception terminal, as in the first embodiment. However, in this embodiment, there may be one relay device or two or more relay devices. The point provided with a transmission source terminal, a relay device, and a reception terminal is the same as that of the first embodiment, and this embodiment will be described below with reference to FIG.

  The transmission source terminal 101 periodically transmits data as in the first embodiment.

  Each relay apparatus 102 and 103 performs aggregation on the data, and transmits the aggregated data to the next node. In the present embodiment, the relay apparatus 103 that transmits data directly to the receiving terminal 104 transmits aggregated data to the receiving terminal 104.

  Also, unlike the first embodiment, each relay device does not have to add an aggregation ID to each piece of data when the pieces of data are aggregated into one piece of data. Therefore, each relay device does not have to define an aggregation ID. Hereinafter, a case where the relay apparatuses 102 and 103 do not define an aggregation ID will be described.

  A relay device that receives aggregated data from a relay device that is different from itself (for example, the relay device 103 that receives aggregated data from the relay device 102) divides and holds the received aggregated data, and holds it at regular intervals. Aggregated data into aggregated data and send it.

  Also, the relay device 102 that directly receives data from the transmission source terminal 101 receives individual data from the transmission source terminal 101, and transmits aggregated data obtained by aggregating the data to the next relay device.

  In the present embodiment, the receiving terminal 104 receives aggregated data from the relay device 103. The receiving terminal 103 divides the received aggregated data into individual data, temporarily stores the divided data in a buffer, and performs processing (for example, voice reproduction processing in VoIP communication).

  The relay device aggregates the held data and transmits the aggregated data at regular time intervals. Accordingly, the receiving terminal 104 receives the next aggregated data after a lapse of time after receiving certain aggregated data. The receiving terminal 104 determines the size of the buffer based on the reception interval of the aggregated data. When the size of the buffer is determined in this way, the buffer is determined based on the interval at which the receiving terminal 104 receives a set of data aggregated into one aggregated data by the relay device 103.

  The configuration of the relay apparatus in this embodiment is as shown in FIG. 2 as in the first embodiment, but the operations of the data processing unit 302 and the aggregation processing unit 303 are partially different. Hereinafter, the data processing unit 302 and the aggregation processing unit 303 in the present embodiment will be described. The wireless communication unit 301 is the same as that in the first embodiment.

  The data processing unit 302 causes the aggregation processing unit 303 to hold data to be transmitted / received between terminals as a target of aggregation regardless of whether the next node to which data is transferred is a relay device or a receiving terminal.

  In addition, when the data processing unit 302 receives aggregated data from another relay apparatus, the data processing unit 302 divides the aggregated data into individual data (individual data transmitted by the transmission source terminal).

  When the data processing unit 302 receives individual data addressed to the receiving terminal from the transmission source terminal 101, the data processing unit 302 causes the aggregation processing unit 303 to hold the data as an aggregation target. In addition, when aggregated data obtained by aggregating data transmitted and received between terminals is received and the aggregated data is divided, the data after division is held in the aggregation processing unit 303 as an aggregation target. The aggregation processing unit 303 holds the data until the data is aggregated and transmitted.

  The aggregation processing unit 303 aggregates each stored data into one aggregated data at regular time intervals. Then, the aggregated data is transmitted to the next node to be transferred via the wireless communication unit 301. Similar to the first embodiment, the transmission interval of the aggregated data by the relay device is the same as the interval for performing the aggregation operation.

  FIG. 9 is a block diagram illustrating a configuration example of a receiving terminal according to the second embodiment. The receiving terminal 104 of the present embodiment includes a terminal-side dividing unit 361, a transmission interval holding unit 351, a reception interval measuring unit 352, an aggregation interval estimating unit 353, a buffer determining unit 354, and a reception interval variation determining unit 355. And a data storage device 356.

  The terminal side dividing unit 361 divides the aggregated data received from the relay device into individual data (individual data transmitted by the transmission source terminal).

  The divided individual data is temporarily held in a buffer (data storage device 356). The data storage device 356 is a storage device used as a buffer for temporarily storing received data.

  Similarly to the first embodiment, the transmission interval holding unit 351 holds the data transmission interval P of the transmission source terminal 101 (see FIG. 1) and the size L of data transmitted by the transmission source terminal 101. As in the first embodiment, a negotiation unit (not shown) stores these pieces of information in the transmission interval holding unit 351.

  In the second embodiment, the reception interval measurement unit 352 measures the reception interval for receiving the aggregated data from the relay device, and obtains the average time of the reception intervals. In the second embodiment, I is the average time of this reception interval. This I is the same as that of the first embodiment in that it is the average of the reception intervals of a set of data aggregated into one aggregated data by the relay device.

  The buffer determination unit 354 determines the size of the buffer based on the average I of the reception intervals obtained by the reception interval measurement unit 352. The buffer determination unit 354 may determine the size of the buffer by calculating (I / P) × L, as in the first embodiment. That is, the result of dividing the average I of the reception intervals obtained by the reception interval measurement unit 352 by the data transmission interval P of the transmission source terminal 101 may be multiplied by the size L of each data. However, the buffer determination unit 354 may determine the size of the buffer by other methods.

  The aggregation interval estimation unit 353 calculates the time interval of the aggregation operation by the relay apparatus based on the number of data divided from one aggregated data and the data transmission interval of the transmission source terminal 101. The aggregation interval estimation unit 353 counts the number of data divided from one aggregated data by the terminal side dividing unit 361, and uses the product of the value and the data transmission interval of the transmission source terminal 101 as the time interval of the aggregation operation. Find it.

  The reception interval variation determination unit 355 determines whether or not the variation in the reception interval of the aggregated data occurs due to the communication network. The reception interval variation determination unit 355 calculates the difference between the average of the reception intervals obtained by the reception interval measurement unit 352 (the average of the reception intervals of the aggregated data) and the interval of the aggregation operation estimated by the aggregation interval estimation unit 353. If the difference is equal to or greater than a predetermined threshold value, it is determined that the reception interval has changed due to the communication network.

  When it is determined that a change in the reception interval due to the communication network has occurred, the receiving terminal 104 may make a request for switching the data path, as in the first embodiment.

  Even if there is no change in the reception interval due to the communication network, if the reception interval of the aggregated data at the reception terminal 104 is large, the transmission source terminal 101 and the reception terminal 104 change the codec respectively. Then, the data size to be transmitted / received may be changed so that the data transmission interval at the transmission source terminal is increased.

  The terminal-side dividing unit 361, the reception interval measurement unit 352, the aggregation interval estimation unit 353, the buffer determination unit 354, and the reception interval variation determination unit 355 are realized by, for example, a CPU that operates according to a program (reception terminal program). This point is the same as in the first embodiment.

Next, the operation of this embodiment will be described.
FIG. 10 is an explanatory diagram illustrating an operation in which each terminal and the relay device transmit and receive data in the second embodiment. The transmission source terminal 101 periodically transmits data including the address of the reception terminal 104 as a destination address (step S21).

  The relay device 102 aggregates and transmits the individual data periodically transmitted from the transmission source terminal 101 to the relay device 103 (step S22). At this time, the relay apparatus 102 specifically operates as follows. The data processing unit 302 of the relay apparatus 102 causes the aggregation processing unit 303 to hold individual data received from the transmission source terminal 101. The aggregation processing unit 303 aggregates each piece of held data into one aggregated data at regular time intervals, and transmits the aggregated data to the relay device 103 via the wireless communication unit 301.

  When the relay apparatus 103 receives the aggregated data from the relay apparatus 102, the relay apparatus 103 divides the aggregated data, aggregates the aggregated data again, and transmits the aggregated data to the receiving terminal 104 (step S23). At this time, the relay apparatus 103 specifically operates as follows. The data processing unit 302 of the relay device 103 divides the aggregated data received from the relay device 102 into individual data, and causes the aggregation processing unit 303 to hold the divided individual data. The aggregation processing unit 303 aggregates each piece of held data into one aggregated data at regular time intervals, and transmits the aggregated data to the receiving terminal 104 via the wireless communication unit 301. Note that the time interval of the aggregation operation may be different for each relay device.

  When the aggregated data transmitted in step S23 is received, the terminal side dividing unit 361 (see FIG. 9) of the receiving terminal 104 divides the aggregated data into individual data. Also, the reception interval measurement unit 352 calculates an average I of the reception intervals of the aggregate data. Next, the buffer determination unit 354 determines the size of the buffer by calculating (I / P) × L. Further, the receiving terminal holds the divided individual data in the buffer.

  Further, the aggregation interval estimation unit 353 of the receiving terminal 353 counts the number of data divided from one aggregated data by the terminal side dividing unit 361 and calculates the product of the value and P (data transmission interval). Thus, the time interval of the aggregation operation in the relay device is obtained. The reception interval variation determination unit 355 determines whether or not there is a variation in the reception interval caused by the communication network, using the time interval of the aggregation operation and I (average of the reception intervals of the aggregated data).

  Also in this embodiment, if there is no data delay due to the communication network, the reception interval of the aggregated data received by the receiving terminal from the relay device is constant. In the present embodiment, since the buffer size is determined using the reception interval, the buffer size can be appropriately determined.

  Next, the outline of the present invention will be described. FIG. 11 is an explanatory diagram showing an outline of the present invention. In the multi-hop communication system of the present invention shown in FIG. 11, the relay device 202 relays data transmitted and received between the terminals 201 and 203. The number of relay devices is not limited to one.

  The transmission side terminal 201 periodically transmits data, and the relay device 202 relays the data.

  Data transmitted from the transmission side terminal 201 is collected by the relay device. The first embodiment shows a case where data aggregated by the relay device is divided by the relay device immediately before the receiving terminal and sent to the receiving terminal. In the second embodiment, a case where individual data is aggregated into one data and sent to the receiving terminal is shown.

  When receiving the data transmitted from the transmitting terminal 201, the receiving terminal 203 temporarily stores the data in a buffer. And the buffer determination means 204 with which the receiving terminal 203 is provided determines the size of the buffer based on the reception interval of the set of data aggregated into one aggregated data by the relay device.

  In the present invention, the buffer size is determined based on the reception interval of a set of data aggregated into one aggregated data, not the reception interval of each piece of data transmitted from the transmission side terminal 201. Can be determined appropriately.

  In the above embodiment, two or more relay devices are provided, and each relay device stores route information indicating route information indicating a communication route of the multi-hop communication system, and a destination included in the received data. , An aggregation availability determination unit that determines whether or not to aggregate data from the path information, a data holding unit that holds data determined to be aggregated, and each data held in the data holding unit at regular intervals A means for aggregating the data into one aggregated data, and identification information for identifying the operation when the aggregate means performs an operation for aggregating each data into the aggregated data, and for each data aggregated into one aggregated data Identification information adding means for adding common identification information, and when it is determined that the data is aggregated and aggregated data is generated, the aggregated data is transmitted and it is determined not to aggregate the data In this case, it has a transmitting means for transmitting individual data and a dividing means for dividing the aggregated data into individual data when the aggregated data is received. The aggregation availability determining means divides the aggregated data by the dividing means. When it is determined, whether or not the divided individual data is aggregated is determined, and the buffer deciding means determines the identification information as the reception interval of the set of data aggregated into one aggregated data by the relay device. A configuration is described in which the reception size of a set of different data is used and the size of the buffer is determined based on the reception interval of a set of data having different identification information.

  In the above embodiment, the receiving terminal aggregates each data into one aggregated data based on the number of data to which common identification information is added and the data transmission interval of the transmission source terminal. Aggregation interval estimation means for estimating the aggregation operation time interval, and fluctuations in the reception interval of data due to the communication network due to the difference between the reception interval of a set of data with different identification information and the estimated aggregation operation time interval A configuration having reception interval variation determination means for determining whether or not has occurred is described.

  In the above embodiment, a configuration is described in which the aggregation interval estimation unit estimates the product of the number of data to which common identification information is added and the data transmission interval of the transmission source terminal as the time interval of the aggregation operation. ing.

  Further, in the above embodiment, the buffer determination unit uses the reception interval of the set of data with different identification information, the data transmission interval of the transmission source terminal, and the size of the data transmitted by the transmission source terminal to A configuration for determining the size of the is described.

  Further, in the above embodiment, each relay device has a data holding unit that holds data, and an aggregation unit that aggregates each data held in the data holding unit at a certain time into one aggregated data, When the aggregated data is transmitted by the dividing unit when the aggregated data is divided by the dividing unit, the aggregated data transmitting unit that transmits the aggregated data and the dividing unit that divides the aggregated data into individual data when the aggregated data is received. The divided data is held, and the buffer deciding means uses the aggregated data reception interval as the reception interval of the set of data aggregated into one aggregated data by the relay device, and based on the aggregated data reception interval A configuration for determining the size of the buffer is described.

  Further, in the above embodiment, the receiving terminal divides the received aggregated data into individual data, the number of pieces of data divided from one aggregated data, and the data transmission interval of the transmission source terminal The aggregation means estimates the time interval of the aggregation operation in which the aggregation means aggregates each data into one aggregated data, and the difference between the aggregate data reception interval and the estimated aggregation operation time interval And a reception interval variation determining means for determining whether or not a variation in the data reception interval due to the communication network has occurred.

  Further, the above embodiment describes a configuration in which the aggregation interval estimation means estimates the product of the number of data divided from one aggregated data and the data transmission interval of the transmission source terminal as the aggregation operation time interval. ing.

  In the above embodiment, the buffer determining means determines the buffer size using the aggregated data reception interval, the data transmission interval of the transmission source terminal, and the size of the data transmitted by the transmission source terminal. The configuration to be described is described.

  The present invention is suitably applied to a multi-hop communication system in which a relay device relays data transmitted and received between terminals and temporarily stores data received by a receiving terminal in a buffer, such as a communication system performing VoIP communication. The

It is explanatory drawing which shows the 1st Embodiment of this invention. It is a block diagram which shows the structural example of a relay apparatus. It is a block diagram which shows the structural example of a receiving terminal. It is explanatory drawing which shows the example of a data transmission interval and a packet size. It is explanatory drawing which shows the operation | movement which each terminal and a relay apparatus transmit / receive data. It is explanatory drawing which shows the operation | movement which a sender terminal, each relay apparatus, and a receiving terminal perform real-time communications, such as VoIP. It is explanatory drawing which shows typically the reception interval of the collection of data in a receiving terminal when aggregation is performed with a some relay apparatus. It is explanatory drawing which shows the reception interval of the collection of data from which aggregation ID differs. It is a block diagram which shows the structural example of the receiving terminal in 2nd Embodiment. It is explanatory drawing which shows the operation | movement which each terminal and a relay apparatus transmit / receive data in 2nd Embodiment. It is explanatory drawing which shows the outline | summary of this invention. It is explanatory drawing which shows the example of the fluctuation | variation of the time interval when data arrives at the terminal which receives data, when aggregation is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Transmission source terminal 102,103 Relay device 104 Reception terminal 301 Wireless communication part 302 Data processing part 303 Aggregation processing part 351 Transmission interval holding part 352 Reception interval measurement part 353 Aggregation interval estimation part 354 Buffer determination part 355 Reception interval fluctuation determination part 356 Data storage device

Claims (20)

A multi-hop communication system in which a relay device relays data transmitted and received between terminals,
A source terminal that periodically sends data,
A receiving terminal for temporarily storing received data in a buffer;
At least one relay device that relays data between the transmission source terminal and the reception terminal is provided,
The receiving terminal
A multi-hop communication system comprising buffer determining means for determining a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device. With two or more relay devices,
Each relay device
Route storage means for storing route information indicating a communication route of the multi-hop communication system;
Aggregation availability determination means for determining whether to aggregate data from a destination included in received data and route information;
Data holding means for holding data determined to be aggregated;
Aggregating means for aggregating each data held in the data holding means into one aggregated data at regular time intervals;
Identification information adding means for defining identification information for identifying the operation when the aggregation means performs an operation for aggregating each data into the aggregated data, and adding common identification information to each data aggregated into one aggregated data When,
When it is determined that the data is aggregated and aggregated data is generated, the aggregated data is transmitted, and when it is determined that the data is not aggregated, a transmission unit that transmits individual data;
Dividing means for dividing the aggregated data into individual data when the aggregated data is received,
The aggregation availability determination means determines whether or not to aggregate the divided individual data when the aggregated data is divided by the dividing means,
The buffer determining means uses the reception interval of the data set with different identification information as the reception interval of the data set aggregated into one aggregated data by the relay device, and based on the reception interval of the data set with different identification information. The multi-hop communication system according to claim 1, wherein a size of the buffer is determined. The receiving terminal
Aggregation interval estimation means for estimating the time interval of the aggregation operation in which the aggregation means aggregates each data into one aggregated data based on the number of data to which common identification information is added and the data transmission interval of the transmission source terminal; ,
Reception interval variation determination means for determining whether a variation in the reception interval of data due to the communication network has occurred based on the difference between the reception interval of a set of data with different identification information and the estimated time interval of the aggregation operation The multi-hop communication system according to claim 2. The multi-hop communication system according to claim 3, wherein the aggregation interval estimation means estimates a product of the number of data to which common identification information is added and the data transmission interval of the transmission source terminal as a time interval of the aggregation operation. The buffer determination means determines the size of the buffer using the reception interval of a set of data having different identification information, the data transmission interval of the transmission source terminal, and the size of data transmitted by the transmission source terminal. The multi-hop communication system according to any one of claims 1 to 4. Each relay device
Data holding means for holding data;
Aggregating means for aggregating each data held in the data holding means into one aggregated data at regular time intervals;
Aggregated data transmission means for transmitting aggregated data;
Dividing means for dividing the aggregated data into individual data when the aggregated data is received,
The data holding means holds the divided individual data when the aggregated data is divided by the dividing means,
The buffer determination means determines the size of the buffer based on the reception interval of the aggregated data using the reception interval of the aggregate data as the reception interval of the set of data aggregated into one aggregated data by the relay device. The multi-hop communication system described. The receiving terminal
A terminal-side dividing means for dividing the received aggregated data into individual data;
Aggregation interval estimation means for estimating the time interval of the aggregation operation in which the aggregation means aggregates each data into one aggregated data based on the number of data divided from one aggregated data and the data transmission interval of the transmission source terminal; ,
The reception interval variation determining means for determining whether or not the variation in the data reception interval caused by the communication network is caused by the difference between the reception interval of the aggregated data and the estimated time interval of the aggregation operation. 6. The multi-hop communication system according to 6. The multi-hop communication system according to claim 7, wherein the aggregation interval estimation means estimates a product of the number of data divided from one aggregated data and the data transmission interval of the transmission source terminal as a time interval of the aggregation operation. The buffer determination means determines the size of the buffer using the reception interval of the aggregated data, the data transmission interval of the transmission source terminal, and the size of the data transmitted by the transmission source terminal. The multi-hop communication system according to any one of the above. A multi-hop communication method applied to a multi-hop communication system in which data transmitted and received between terminals is relayed by a relay device and data received by a receiving terminal is temporarily stored in a buffer,
The sending device sends data periodically,
A multi-hop communication method, wherein a receiving terminal determines a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device. Using two or more relay devices
Each relay device
From the destination included in the received data and the path information indicating the communication path of the multi-hop communication system, determine whether to aggregate the data,
Holds data that is determined to be aggregated,
Aggregate each stored data into one aggregated data at regular intervals,
Defining identification information for identifying the operation during the aggregation operation, adding common identification information to each data aggregated into one aggregated data,
When the aggregated data is received, the aggregated data is divided into individual data, and it is determined whether to aggregate the divided data.
If it is determined that data is aggregated and aggregated data is generated, aggregated data is transmitted. If it is determined that data is not aggregated, individual data is transmitted.
The receiving terminal uses the reception interval of the data set with different identification information as the reception interval of the data set aggregated into one aggregated data by the relay device, and buffers based on the reception interval of the data set with different identification information The multi-hop communication method according to claim 10, wherein the size of the multi-hop communication method is determined. Each relay device
When data that has not been aggregated is received, the data is retained. When aggregated data in which a plurality of data is aggregated is received, individual data divided from the aggregated data is retained.
Aggregate each stored data into one aggregated data at regular intervals,
Send aggregate data,
The receiving terminal uses the aggregated data reception interval as a reception interval of a set of data aggregated into one aggregated data by the relay device, and determines the buffer size based on the aggregated data reception interval. Multi-hop communication method. A receiving terminal that receives data transmitted from a transmission source terminal that periodically transmits data via a relay device and temporarily stores the received data in a buffer,
A receiving terminal comprising buffer determining means for determining a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device. From the destination included in the received data and the route information indicating the communication route of the multi-hop communication system, it is determined whether or not the data is to be aggregated, and the data determined to be aggregated is retained and retained at regular intervals. Collecting each piece of data into one aggregated data, defining identification information for identifying the operation during the aggregation operation, adding common identification information to each data aggregated into one aggregated data, When the aggregated data is received, the aggregated data is divided into individual data, whether or not the divided data is aggregated is determined, and if aggregated data is generated when it is determined that the data is aggregated, the aggregated data is transmitted When it is determined that the data is not aggregated, it is a receiving terminal that receives data via a relay device that transmits individual data,
The buffer determination means uses the reception interval of the data set with different identification information as the reception interval of the data set aggregated into one aggregated data by the relay device, and based on the reception interval of the data set with different identification information. The receiving terminal according to claim 13, wherein the size of the buffer is determined. When data that has not been aggregated is received, the data is retained. When aggregated data in which a plurality of data is aggregated is received, individual data divided from the aggregated data is retained, and is retained at regular intervals. Each receiving data is aggregated into one aggregated data, and the data is received via a relay device that transmits the aggregated data.
The buffer determination means uses the aggregated data reception interval as the reception interval of a set of data aggregated into one aggregated data by the relay device, and determines the buffer size based on the aggregated data reception interval. The receiving terminal described. A relay device that relays data by aggregating received data into one aggregated data and transmitting the aggregated data,
Route storage means for storing route information indicating a communication route of the multi-hop communication system;
Aggregation availability determination means for determining whether to aggregate data from a destination included in received data and route information;
Data holding means for holding data determined to be aggregated;
Aggregating means for aggregating each data held in the data holding means into one aggregated data at regular time intervals;
Identification information adding means for defining identification information for identifying the operation when the aggregation means performs an operation for aggregating each data into the aggregated data, and adding common identification information to each data aggregated into one aggregated data When,
When it is determined that the data is aggregated and aggregated data is generated, the aggregated data is transmitted, and when it is determined that the data is not aggregated, a transmission unit that transmits individual data;
Dividing means for dividing the aggregated data into individual data when the aggregated data is received,
An aggregation availability determination unit determines whether or not to aggregate individual divided data when the aggregated data is divided by the dividing unit. A program for a receiving terminal installed in a computer used as a receiving terminal that receives data transmitted from a transmission source terminal that periodically transmits data via a relay device and temporarily stores the received data in a buffer. And
On the computer,
A program for a receiving terminal for executing a buffer determination process for determining a buffer size based on a reception interval of a set of data aggregated into one aggregated data by a relay device. From the destination included in the received data and the route information indicating the communication route of the multi-hop communication system, it is determined whether or not the data is to be aggregated, and the data determined to be aggregated is retained and retained at regular intervals. Collecting each piece of data into one aggregated data, defining identification information for identifying the operation during the aggregation operation, adding common identification information to each data aggregated into one aggregated data, When the aggregated data is received, the aggregated data is divided into individual data, whether or not the divided data is aggregated is determined, and if aggregated data is generated when it is determined that the data is aggregated, the aggregated data is transmitted When it is determined that the data is not aggregated, the computer that receives the data via the relay device that transmits the individual data
In the buffer determination process, as the reception interval of the data set aggregated into one aggregated data by the relay device, the reception interval of the data set with different identification information is used, and based on the reception interval of the data set with different identification information The receiving terminal program according to claim 17, wherein the size of the buffer is determined. When data that has not been aggregated is received, the data is retained. When aggregated data in which a plurality of data is aggregated is received, individual data divided from the aggregated data is retained, and is retained at regular intervals. To a computer that receives data via a relay device that aggregates each piece of data into one aggregated data and transmits the aggregated data,
18. The buffer determination process uses the aggregated data reception interval as the reception interval of a set of data aggregated into one aggregated data by the relay device, and determines the buffer size based on the aggregated data reception interval. The receiving terminal program. A relay device program installed in a computer that relays data by aggregating received data into one aggregated data and transmitting the aggregated data,
On the computer,
Aggregation availability determination process for determining whether to aggregate data from the destination included in the received data and the path information indicating the communication path of the multi-hop communication system,
Data retention processing that retains data determined to be aggregated,
Aggregation processing that aggregates each stored data into one aggregated data at regular intervals,
An identification information adding process for defining identification information for identifying the aggregation process when executing the aggregation process, and adding common identification information to each data aggregated into one aggregated data;
When it is determined that data is aggregated and aggregated data is generated, aggregated data is transmitted. When it is determined that data is not aggregated, individual data is transmitted, and when aggregated data is received, Execute a division process to divide the aggregated data into individual data,
A program for a relay device that, when the aggregated data is divided by the dividing process, causes the divided individual data to be subjected to the aggregation possibility determination process.

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