JP2008047956A - Communication apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently distribute data to be transmitted to respective links in a communication device which communicates by a multilink transmission system. <P>SOLUTION: The multilink communication device 10 is equipped with a plurality of radio communication interfaces performing data transmission through different links, and distributes the data to be transmitted to one of radio communication interfaces by packets to transmit the data to be transmitted to an external device through a plurality of links L1 and L2. Specifically, the communication device measures carrier sense-off times as times wherein data transmission is not performed through links where link carrier sensing is not performed by the links. Then packets are distributed to a radio communication interface corresponding to a link whose carrier sense-off time is maximum, and the packets are transmitted to a radio communication interface as a distribution destination through the link whose carrier sense off time is maximum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication apparatus that includes a plurality of communication interfaces and performs communication using a multilink transmission method, and a program used for the communication apparatus.

  In recent years, with an increase in application software that handles large volumes of data, communication devices are required to have high data transmission capabilities. Adopting a multilink transmission method that simultaneously uses a plurality of physical interfaces (communication interfaces) is known as an effective method for realizing large-capacity transmission in a communication device (see Patent Document 1).

As a protocol corresponding to the multilink transmission system, the multilink protocol RFC1990 is known. RFC1990 is a protocol designed for the purpose of preventing a change in the arrival order of packets when transmitting and receiving packets.
JP 2000-216815 A

  By the way, in the multilink transmission method, it is necessary to distribute packets to each link (transmission path used by each communication interface). However, in an environment where the quality of the link varies greatly as in wireless communication, the packet is allocated to each link. If the distribution is evenly distributed, packet retransmission and packet loss are incurred on a link with poor quality, which adversely affects throughput and packet arrival order. For this reason, when a multilink transmission method is adopted for wireless communication, data distribution in consideration of the wireless communication environment is important for realizing efficient communication.

  Regarding the data distribution method, Patent Document 1 employs a technique of calculating an effective transmission rate based on the number of retransmissions for each link and distributing packets to a link that can be expected to have the highest transmission rate ( Method A).

  In addition, as a well-known technique related to the single link transmission method, in IEEE 802.11 widely used in a wireless LAN or the like, when data is transmitted from its own station, it is determined by carrier sense whether other communication stations are transmitting data. A technique is known that discriminates and prohibits data transmission from its own station when another communication station is transmitting data. When this concept is applied to the multilink transmission method, if it is determined by carrier sense that another communication station is transmitting data, data to be transmitted is transmitted to another link where data transmission by the other communication station is not performed. Can be considered to realize data transmission (method B).

  However, in the multilink transmission method, communication can be performed with both a multilink communication station capable of multilink transmission and a single link communication station having a single communication interface as an external device. In a wireless communication environment in which link communication stations are mixed, the number of communication stations staying on each link may be different.

  For example, there are two multilink communication stations that can use the links L1 and L2, and one single link communication station that can use only the link L1. When the number of communication stations staying on each link from one multilink communication station is seen, the number of other communication stations using link L1 is two, and the number of other communication stations using link L2 is one. There will be a stand. That is, the multilink communication station shares the link L1 with two other communication stations other than the own station, and shares the link L2 with one other communication station other than the own station.

  However, since the method A distributes packets to each link based on the number of retransmissions, the multilink communication station that distributes data by the method A distributes packets to links with a small number of retransmissions but a large number of staying communication stations. May end up. That is, in method A, packets are preferentially distributed to links with high traffic even if the number of retransmissions is small, and there is a possibility that the packet transmission waiting time and collision increase, resulting in a decrease in throughput. Also, in method A, since the link to be allocated is determined based on the number of retransmissions, method A is used to distribute packets for multicast communication that is generally not subjected to retransmission processing. There is a problem that can not be.

  In the method B, the link to which the packet is distributed is determined depending on the presence / absence of data transmission by another communication station. Therefore, the transmission target data is distributed to an appropriate link according to the link quality and traffic. There was a problem that I couldn't. For this reason, in method B, inefficient packet distribution is performed, packet transmission waiting time and collision increase, and throughput may be reduced.

  The present invention has been made in view of such a problem, and is a technology capable of distributing transmission target data more efficiently than before in a communication apparatus that includes a plurality of communication interfaces and performs communication by a multilink transmission method. The purpose is to provide.

  The communication device according to claim 1, which has been made to achieve the above object, includes a plurality of communication interfaces for transmitting data to an external device through different transmission paths, and a transmission used by the communication interface for each of these communication interfaces. A measurement unit that measures a non-transmission time during which no data is transmitted on the road is provided. Based on the measurement result of each measurement unit, the transmission control unit determines transmission target data for each unit data (for example, for each packet). The data is distributed to any one of a plurality of communication interfaces, and the corresponding data is transmitted to an external device via the communication interface of the distribution destination. Note that examples of the communication interface include a communication interface for wireless communication in addition to a communication interface for wired communication.

  According to this communication apparatus, since the communication interface for distributing data is determined based on the non-transmission time of the transmission path (link) used by each communication interface, the communication interface corresponding to the transmission path having a long non-transmission time is used. , Can preferentially sort data.

  In a transmission path (link) with a long non-transmission time, the allocated transmission target data is small and the data transmission capability is sufficient. For communication interfaces that use a transmission path with a long non-transmission time, If the data is preferentially distributed, the data can be efficiently transmitted to the external device by the multilink transmission method.

  For example, in a transmission line with poor quality, data retransmission frequently occurs and traffic on the transmission line increases, but according to the present invention, the magnitude of traffic can be evaluated based on the non-transmission time. Data can be preferentially distributed to good transmission paths. Even when the number of communication stations using each transmission path is different, the magnitude of traffic can be evaluated based on the non-transmission time, so that data can be appropriately distributed to an empty transmission path. In addition, according to the present invention, since the non-transmission time of each transmission path is measured, the free state of each transmission path can be evaluated more correctly than in the past, and data can be distributed more efficiently than method B. it can.

  Specifically, the transmission control means may be configured to distribute data to the communication interface corresponding to the transmission path with the longest non-transmission time based on the measurement result of each measurement means (claim 2). According to the communication apparatus configured as described above, data can be distributed to the transmission path with the most vacancy, and transmission target data can be efficiently transmitted to the external apparatus.

  In addition, the communication device may be configured to determine a communication interface for distributing data according to a ratio of non-transmission times of transmission paths corresponding to each communication interface based on a measurement result of each measurement unit ( Claim 3). Even if the communication apparatus is configured in this manner, data can be appropriately distributed according to the free state of each transmission path.

  In addition, the measuring means measures the time interval from the end of data transmission on the transmission path used by the communication interface until the start of the next data transmission as a non-transmission time, every time data transmission ends. However, it may be configured as follows.

  In other words, the measuring means may be configured to measure the total time during which data transmission is not performed on the transmission path used by the communication interface within the preset measurement time as the non-transmission time. ). According to the communication apparatus configured as described above, since the communication interface for distributing data is determined based on the total time during which data transmission is not performed in a certain period, the next data transmission is completed after the data transmission is completed. It is possible to realize an appropriate data distribution operation more stably than the case where the time interval until the start is calculated every time and the data is distributed based on this time interval. That is, if the sum is measured, it is difficult to be affected by the instantaneous change in the state of the transmission line, and data can be appropriately distributed to an empty transmission line.

  However, if the measurement time is shorter than the time interval from the end of data transmission in each transmission path to the start of the next data transmission, the non-transmission time calculated for each transmission path is It becomes difficult to determine which transmission path is a preferable transmission path as a data distribution destination. Therefore, the communication device may be configured to change the measurement time as follows.

  That is, the communication device includes an interval measuring unit that measures a transmission interval as a time interval from the end of data transmission on the transmission path used by the communication interface to the start of the next data transmission for each communication interface. The communication device may be configured to set the measurement time by the measurement time setting means so as not to be shorter than any of the transmission intervals in each transmission path based on the measurement result of each interval measurement means. 5).

  According to the communication apparatus configured in this way, the measurement time is set to a time (or the same time) longer than any of the transmission intervals of each transmission path, so which transmission path is preferable as a data distribution destination. It is possible to appropriately determine whether the road is a road and to appropriately distribute data.

  Also, a multilink communication station that performs multilink transmission using the same transmission line group as the transmission line group used by the communication apparatus, and each transmission line belonging to the transmission line group has a unit at a constant interval in order. When multiple external devices that distribute data and send each unit data to one of the transmission lines that form the transmission line group are connected, the transmission interval of the data that the external apparatus sends as the measurement time And a time multiplied by the number of communication interfaces included in the communication device (in other words, the number of transmission paths used by the communication device). In this way, if the measurement time is set, the quality of each transmission path can be appropriately evaluated in a short measurement time, and data can be appropriately distributed.

  In wireless communication, it is common to perform carrier sense and output the result depending on whether the strength of a signal received through a transmission path (link) exceeds a certain threshold (carrier sense level). Therefore, using this function, each measuring means may be configured to measure a time during which the intensity of the signal received by the communication interface is equal to or less than a threshold value as a non-transmission time (Claim 7). If the communication device is configured in this way, the non-transmission time can be easily measured. Further, if the above transmission interval is measured by the same method, the transmission interval can be easily known.

Further, when the transmission target data is distributed when all of the transmission paths used by each communication interface are transmitting data, the following method may be employed.
That is, the communication device includes an elapsed time measuring means for measuring an elapsed time from the start of data transmission every time data transmission is performed on the transmission path used by the communication interface, and data on the transmission path used by the communication interface. Each time a transmission is made, a transmission time measuring means for measuring a transmission time as a time from the start of the data transmission to the completion of the data transmission is provided for each communication interface. In the case of transmission, a configuration may be adopted in which a communication interface for distributing data is determined based on a measurement result of each elapsed time measurement unit and a measurement history of each transmission time measurement unit.

  If the communication device is configured in this way, data can be preferentially assigned to a communication interface where data transmission ends early, and transmission target data can be efficiently transmitted to an external device.

  More specifically, the transmission control means derives the transmission time having the highest frequency in the past from the measurement history of the corresponding transmission time measurement means for each transmission line when all transmission lines are transmitting data. Estimate the remaining time until data transmission is completed on the corresponding transmission line from the time and the measurement result of the corresponding elapsed time measuring means, and use the transmission line with the minimum remaining time based on these estimation results The communication interface may be configured to distribute the data (claim 9). If the communication device is configured as described above, the transmission target data can be efficiently transmitted to the external device.

In addition, when data is distributed when all of the transmission paths used by each communication interface are in non-data transmission, the following method may be employed.
That is, the communication device includes an elapsed time measuring means for measuring an elapsed time from the end of data transmission every time data transmission is completed on the transmission path used by the communication interface, and data on the transmission path used by the communication interface. An idle time measuring means for measuring an idle time as a time from the end of data transmission to the start of the next data transmission is provided for each communication interface every time transmission is completed. When the transmission line is in non-data transmission, the communication interface for distributing data may be determined based on the measurement result of each elapsed time measurement unit and the measurement history of each idle time measurement unit. 10).

  According to the communication apparatus configured as described above, data can be distributed to a communication interface corresponding to a transmission path having a long time until data transmission by another communication station is performed, and data transmission operation by another communication station can be performed. The transmission target data can be transmitted from the own apparatus to the external apparatus during a period when the other communication station is not transmitting data without much influence. In other words, the data transmission operation can be realized without colliding with other communication stations so much, and a decrease in throughput due to the collision can be suppressed.

  More specifically, the transmission control means derives the idle time having the maximum frequency in the past from the measurement history of the corresponding idle time measurement means for each transmission line when all transmission lines are in non-data transmission. Based on the idle time and the measurement result of the corresponding elapsed time measuring means, the remaining time until data transmission is started in the corresponding transmission line is estimated, and based on these estimation results, the transmission line with the maximum remaining time is estimated. The data may be distributed to the communication interface that uses. By configuring the communication device in this way, an appropriate data distribution operation can be realized.

  Also, when an external device that uses the same transmission path as the communication device is configured to periodically transmit data, the next data transmission timing is estimated by detecting the data transmission timing by the external device. can do. Therefore, in order to realize multilink transmission in such an environment, the communication device may be configured as follows.

  That is, the communication device includes an estimation means for estimating, for each external device, an external device that uses the same transmission line as the transmission line used by the communication interface to perform data transmission using the transmission line. The communication device is provided for each interface, and the communication device distributes the transmission target data to one of a plurality of communication interfaces for each unit data based on the estimation result of each estimation unit, and externally transmits the data corresponding to the communication interface of the distribution destination. It is good to make it the structure which transmits to an apparatus (Claim 12).

  According to the communication apparatus having such a configuration, the own apparatus does not interfere with the data transmission operation of another communication station that performs data transmission using the same transmission path, and the other apparatus does not perform data transmission. The data transmission operation can be executed at. Therefore, according to this communication apparatus, collision with other communication stations hardly occurs, and a reduction in throughput can be suppressed. In other words, according to this communication apparatus, it is possible to efficiently distribute the transmission target data to the communication interface corresponding to the vacant transmission path.

  Moreover, the function as each means which comprises the above-mentioned communication apparatus can be implement | achieved by the computer of a communication apparatus with a program (Claims 13 and 14). Also, these programs can be provided to the user through a recording medium such as an optical disk such as a CD-ROM or DVD, a magnetic disk, or a memory device.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of a network system 1 having a multilink communication apparatus 10 to which the present invention is applied.
The multilink communication device 10 according to the present embodiment belongs to the network system 1 in which the same type of multilink communication device 10 and the single link communication device 50 participate, and includes the multilink communication device 10 and the single link communication device 50 other than the self device. A link (transmission path) is shared, and bidirectional communication is performed in a wireless form with other communication devices.

  In this network system 1, two links L1 and L2 (so-called channels) are prepared, and the multilink communication device 10 communicates with other communication devices using both the links L1 and L2. The single link communication device 50 communicates with other communication devices using only one of the predetermined link L1 or link L2.

  That is, the single link communication device 50 includes only one wireless communication interface and performs communication using a single link used by the wireless communication interface. On the other hand, the multilink communication device 10 includes a plurality (specifically, two) of wireless communication interfaces 20 that perform wireless communication using different links, and uses these wireless communication interfaces 20a and 20b at the same time. Communicate with an external device through the links L1 and L2.

  Specifically, the multilink communication apparatus 10 of the present embodiment is configured as shown in FIG. FIG. 2 is a block diagram illustrating the configuration of the multilink communication device 10 according to the present embodiment. In this embodiment, it is assumed that the multilink communication device 10 is used by being mounted on a vehicle such as an automobile, and transmits / receives data handled by the in-vehicle device 5 such as a navigation device.

  As shown in FIG. 2, the multilink communication device 10 of the present embodiment incorporates a microcomputer, a ROM, a RAM, and the like (not shown), and implements various functions by executing programs recorded in the ROM. A control circuit 30 that performs overall control, a first wireless communication interface 20a that performs wireless communication using the link L1, and a second wireless communication interface 20b that performs wireless communication using the link L2.

  The first and second wireless communication interfaces 20a and 20b have the same configuration except that different links are used. The first and second wireless communication interfaces 20a and 20b have a transmission / reception antenna 21, a communication control unit 23, a reception intensity detection unit 25, and carrier sense. The communication control unit 23 superimposes a transmission target packet distributed by the control circuit 30 on a carrier wave (carrier) and outputs the packet in a wireless form through the transmission / reception antenna 21. The communication control unit 23 includes a transmission buffer (not shown) for temporarily accumulating packets to be transmitted, and the packets accumulated in the transmission buffer are transmitted through the transmission / reception antenna 21 in the order of accumulation. Output in wireless form.

  In addition, the communication control unit 23 is configured to extract the received packet from the signal received by the transmission / reception antenna 21, input this to the control circuit 30, and transmit the received packet to the in-vehicle device 5 through the control circuit 30. Yes.

  In addition, the reception intensity detection unit 25 included in the multilink communication device 10 is configured to detect the intensity of the signal received by the transmission / reception antenna 21 and output an RSSI signal representing the reception intensity to the carrier sense unit 27. Based on the RSSI signal output from the reception strength detection unit 25, the carrier sense unit 27 uses a link (link L1 in the case of the first wireless communication interface 20a, the second wireless communication interface 20b) used in the corresponding wireless communication interface. In this case, it is determined whether or not data transmission is performed in the link L2).

  When the reception strength is equal to or less than a predetermined threshold, the carrier sense unit 27 outputs a carrier sense off signal indicating that data transmission is not performed on the corresponding link to the control circuit 30, and the reception strength is If it is greater than the threshold, a carrier sense ON signal indicating that data transmission is being performed on the corresponding link is output to the control circuit 30.

  Further, the control circuit 30 executes various programs by executing a program recorded in the ROM by a microcomputer, and packetized transmission target data sent from the in-vehicle device 5 such as a navigation device, Each packet is distributed to either the first or second wireless communication interface 20a or 20b, and the packet is transmitted to the distribution-destination wireless communication interface. In addition, the control circuit 30 is configured to transfer a packet addressed to itself received by each of the wireless communication interfaces 20a and 20b to the in-vehicle device 5 by executing a program.

  In the present embodiment, functions as the measurement unit 31, the measurement time setting unit 33, and the data distribution unit 35 are realized in the control circuit 30 by executing the program by the microcomputer. That is, the control circuit 30 functions as the measurement unit 31, the measurement time setting unit 33, and the data distribution unit 35 by executing the program.

  Then, the process which the measurement part 31 performs is demonstrated. FIG. 3 is a flowchart showing a measurement process repeatedly executed by the measurement unit 31. In the present embodiment, a measurement unit 31 is provided for each of the first and second wireless communication interfaces 20a and 20b (in other words, for each of the link L1 and the link L2), and the first wireless communication interface is provided. The measurement unit 31 corresponding to 20a performs measurement processing described below based on the signal output from the carrier sense unit 27 of the first wireless communication interface 20a, and the measurement unit corresponding to the second wireless communication interface 20b. 31 starts measurement processing described below based on a signal output from the carrier sense unit 27 of the second wireless communication interface 20b.

  The measurement part 31 will clear the counter for time measurement first, if a measurement process is started (S110). Thereafter, based on the signal from the corresponding carrier sense unit 27, it is determined whether or not the output signal from the carrier sense unit 27 is a carrier sense off signal (S120), and the output signal from the carrier sense unit 27 is the carrier signal. If it is determined that the signal is a sense-off signal (Yes in S120), the process proceeds to S130. On the other hand, if it is determined that the output signal from the carrier sense unit 27 is a carrier sense ON signal (No in S120), the process proceeds to S140.

  After shifting to S130, the measuring unit 31 determines whether or not the counter has already been operated and time measurement has been performed. If the counter has not been operated (No in S130), the counter is operated to measure time. (S135), the process proceeds to S150. On the other hand, if it is determined in S130 that the counter is already operating (Yes in S130), the measurement unit 31 skips S135 and proceeds to S150.

  In S150, it is determined whether or not the elapsed time since the counter is cleared exceeds the measurement time Tm set in advance for the measurement unit 31, and if it does not exceed the measurement time Tm. (No in S150), the process proceeds to S120, and the processes of S120 to S150 are repeated until the elapsed time after the counter is cleared exceeds the measurement time Tm.

  That is, when the output signal from the carrier sense unit 27 is a carrier sense off signal, the measurement unit 31 determines Yes in S120, performs time measurement using a counter, and the output signal from the carrier sense unit 27 is carrier sense. When the signal is an on signal (when the output signal is switched from the carrier sense off signal to the carrier sense on signal), it is determined No in S120, the counter is suspended, and the time measurement is suspended (S140). , The process proceeds to S150.

  In this way, in the measurement process, the total time during which the output signal from the carrier sense unit 27 was the carrier sense off signal within the measurement time Tm is measured by the counter. With this operation, the measuring unit 31 corresponding to the first wireless communication interface 20a obtains the total time during which data transmission is not performed in the link L1 within the measurement time Tm, and the measuring unit corresponding to the second wireless communication interface 20b. In 31, the sum total of the time during which data transmission is not performed in the link L <b> 2 within the measurement time Tm is obtained.

  When it is determined that the elapsed time since the counter is cleared has passed the preset measurement time Tm (Yes in S150), the measurement unit 31 stops the counter (S160), The counter value is output to the data distribution unit 35 as the carrier sense off time T_CS [i] (S170). The parameter i is an index number corresponding to the links L1 and L2, and the carrier sense off time corresponding to the link L1 is represented as T_CS [1] below, and the carrier sense off time corresponding to the link L2 is This is expressed as T_CS [2].

Moreover, when the process in S170 is completed, the measurement unit 31 once ends the measurement process, and executes the measurement process from S110 again.
Then, the content of the process which the measurement time setting part 33 which sets the measurement time Tm to the measurement part 31 performs is demonstrated. FIG. 4 is a flowchart showing a measurement time setting process repeatedly executed by the measurement time setting unit 33.

  When the measurement time setting process is started, the measurement time setting unit 33 first sets the link L1 as an inspection target in order to inspect the traffic of the links L1 and L2 (S210), and the first wireless communication interface using the link L1. It is determined whether the output signal from the carrier sense unit 20a is a carrier sense on signal (S220). If it is determined that the output signal is not a carrier sense on signal (No in S220), the process waits until the output signal becomes a carrier sense on signal. If the output signal is a carrier sense on signal (Yes in S220). Then, the process proceeds to S225, and then waits until the output signal from the carrier sense unit 27 of the first wireless communication interface 20a is switched to the carrier sense off signal. When the output signal is switched to the carrier sense off signal (Yes in S225), a time T1 from this point in time until the output signal is switched to the carrier sense on signal is measured (S230).

  When the output signal is switched to the carrier sense ON signal and the measurement of the time T1 is completed, the measured time T1 is longer than the measurement time Tm set in advance in each measurement unit 31 corresponding to both the links L1 and L2. It is determined whether or not it is large (S240), and if it is determined that Tm <T1 (Yes in S240), a value obtained by adding a constant α to time T1 as a measurement time Tm (T1 + α) for all measurement units 31. Is set (S245).

  Note that the multilink communication apparatus of the present embodiment is configured to set the same measurement time Tm for all the measurement units 31 for each link (in other words, for each wireless communication interface), and the constant α is It is assumed that the multilink communication apparatus 10 is set in advance to an arbitrary value of zero or more at the design stage.

  Further, when the setting operation of the measurement time Tm in S245 is completed, the measurement time setting unit 33 proceeds to S250, and sets the link L2 as an inspection target instead of the link L1 (S250). On the other hand, when the time T1 is equal to or shorter than the measurement time Tm (No in S240), the process of S245 is skipped and the process proceeds to S250, and the link L2 is set as an inspection target.

  When the process in S250 is completed, the measurement time setting unit 33 determines whether the output signal from the carrier sense unit 27 of the second wireless communication interface 20b using the link L2 is a carrier sense on signal. (S260) If the output signal is a carrier sense on signal (Yes in S260), the process proceeds to S265, and if the output signal is not a carrier sense on signal (No in S260), the output signal is a carrier signal. The process waits until the sense-on signal is reached, and when the output signal is switched to the carrier sense-on signal, the process proceeds to S265.

  On the other hand, if it transfers to S265, the measurement time setting part 33 will wait until the output signal from the carrier sense part 27 of the 2nd radio | wireless communication interface 20b switches to a carrier sense off signal. When the output signal is switched to the carrier sense off signal (Yes in S265), a time T2 from this point in time until the output signal is switched to the carrier sense on signal is measured (S270).

  Further, when the output signal from the carrier sense unit 27 of the second wireless communication interface 20b is switched to the carrier sense ON signal and the measurement of the time T2 is completed, the measurement units 31 corresponding to both the links L1 and L2 are set in advance. It is determined whether or not the time T2 is greater than the measured time Tm (S280). If Tm <T2 (Yes in S280), the time T2 is set as the measured time Tm for all the measuring units 31. A value obtained by adding a constant α to (T2 + α) is set (S285).

  When the process in S285 is completed, the measurement time setting unit 33 once ends the measurement time setting process, and then executes the subsequent processes from S210 again. On the other hand, if it is determined that the time T2 is equal to or shorter than the measurement time Tm (No in S280), the measurement time setting unit 33 skips the process of S285 and temporarily ends the measurement time setting process. Thereafter, subsequent processing is executed again from S210.

  In this way, the measurement time setting unit 33 sequentially sets the measurement time Tm so as not to be shorter than the idle time of each of the links L1 and L2 (the time during which the carrier sense off signal continues).

  Next, processing executed by the data distribution unit 35 will be described. FIG. 5 is a flowchart showing data distribution processing that is repeatedly executed by the data distribution unit 35. Based on the carrier sense off times T_CS [1] and T_CS [2] obtained by the measurement unit 31, the data allocating unit 35 receives each packet to be transmitted input from the in-vehicle device 5 as the first packet. The packet is distributed to one of the first and second wireless communication interfaces 20a and 20b, and the corresponding packet is transmitted to the distribution-destination wireless communication interface in a wireless form.

  When the data distribution process is started, the data distribution unit 35 waits until a transmission target packet is input from the in-vehicle device 5 (S300). When a transmission target packet is input (Yes in S300), S310 The subsequent processing is executed.

  When a packet to be transmitted is input and the process proceeds to S310, the data distribution unit 35 corresponds to the latest carrier sense off time T_CS [1] obtained from the measurement unit 31 corresponding to the link L1 and the link L2. Based on the latest carrier sense off time T_CS [2] obtained from the measurement unit 31, it is determined whether or not the time T_CS [1] is larger than the time T_CS [2] (S310), and T_CS [1]> T_CS. If it is determined that [2] (Yes in S310), the transmission buffer amount (that is, the total amount of packets accumulated in the transmission buffer) Buf1 of the first wireless communication interface 20a is checked (S320).

  If it is determined that the transmission buffer amount Buf1 is smaller than the maximum accumulation amount (maximum amount of packets that can be stored in the transmission buffer) in the first wireless communication interface 20a (Yes in S330), the input transmission target The packet is distributed to the first wireless communication interface 20a, and the first wireless communication interface 20a is caused to transmit the packet to the external device in a wireless form (S340). When the process in S340 is completed, the data distribution unit 35 temporarily ends the data distribution process, and then proceeds to S300 again and waits until the next transmission target packet is input.

  If the transmission buffer amount Buf1 checked in S320 is the maximum accumulation amount of the transmission buffer (No in S330), the data distribution unit 35 proceeds to S333 and transmits the transmission buffer amount Buf2 of the second wireless communication interface 20b. Check.

  When it is determined that the transmission buffer amount Buf2 is smaller than the maximum accumulation amount of the transmission buffer in the second wireless communication interface 20b (Yes in S337), the process proceeds to S380. On the other hand, when the transmission buffer amount Buf2 is the maximum accumulation amount of the transmission buffer in the second wireless communication interface 20b (No in S337), the process proceeds to S390, and the transmission target packet input this time is discarded. The data distribution process is temporarily terminated. Thereafter, the process proceeds to S300 again.

  In addition, if it is determined in S310 that T_CS [1]> T_CS [2] is not satisfied (No in S310), the data distribution unit 35 checks the transmission buffer amount Buf2 of the second wireless communication interface 20b (S360). When it is determined that the transmission buffer amount Buf2 is smaller than the maximum accumulation amount of the transmission buffer in the second wireless communication interface 20b (Yes in S370), the input transmission target packet is distributed to the second wireless communication interface 20b. The second wireless communication interface 20b transmits the packet to the external device in a wireless form (S380). When the process in S380 is completed, the data distribution process is temporarily terminated, and then the process proceeds to S300 again.

  In addition, when the transmission buffer amount Buf2 checked in S360 is the maximum accumulation amount of the transmission buffer (No in S370), the data distribution unit 35 proceeds to S373 and transmits the transmission buffer amount of the first wireless communication interface 20a. Check Buf1.

  When it is determined that the transmission buffer amount Buf1 is smaller than the maximum accumulation amount of the transmission buffer in the first wireless communication interface 20a (Yes in S377), the process proceeds to S340. On the other hand, when the transmission buffer amount Buf1 is the maximum accumulation amount of the transmission buffer in the first wireless communication interface 20a (No in S377), the process proceeds to S390, and the transmission target packet input this time is discarded. The data distribution process is temporarily terminated. Thereafter, the process proceeds to S300 again, and the data distribution process is repeatedly executed.

  In this way, the data distribution unit 35 is connected to a wireless communication interface corresponding to a link having a long carrier sense off time every time a packet to be transmitted is input from the in-vehicle device 5 unless the transmission buffer is full. Then, the input packet is distributed, and the packet is transmitted in a wireless form to the wireless communication interface of the distribution destination.

  In this embodiment, since the transmission target packet is distributed in this way, for example, when the quality of the link L1 is poor, the transmission target packet can be appropriately distributed preferentially to the link L2. In the link transmission method, the throughput can be improved as compared with the conventional case.

  As shown in FIG. 6A, since a packet transmission error occurs in the poor quality link L1, the number of retries regarding the packet transmission operation increases, and the carrier sense off time in the link L1 decreases. Therefore, according to the present embodiment, it is not necessary to distribute the packet to the link L1 with poor quality, and the packet can be efficiently transmitted to the external device by the multilink transmission method.

  In particular, in the multilink communication device 10 of the present embodiment, the presence or absence of data transmission through the links L1 and L2 by other communication devices is determined by carrier sense without measuring the number of retransmissions of packets transmitted by the device itself. Since the wireless communication interface to which packets are distributed is determined based on the carrier sense off time, not only the quality of the links L1 and L2, but also the degree of congestion of the links L1 and L2 can be evaluated. By contrast, even when the single link communication device 50 using this link is participating in the network system 1, it is possible to avoid a congested link and efficiently use a free link.

  For example, when M1 multilink communication devices 10 using links L1 and L2 and M2 single link communication devices 50 using only link L1 are participating in network system 1, the number M2 is sufficiently larger than M1. Since there are M1 + M2 devices using the link L1 and M1 devices using the link L2, the number of devices staying at each link is unbalanced. Therefore, in such an environment, the link L2 may be free even when the quality of the link L2 is poor and the packet is being retransmitted to some extent (see FIG. 6B).

  Under such circumstances, since only the number of retransmissions was conventionally evaluated, there was a possibility that packets would be distributed to the congested link L1, but in the multilink communication device 10 of this embodiment, carrier sense Since packets are preferentially distributed to free links based on the off time, unlike the conventional apparatus, the link L2 can be efficiently used to transmit packets to an external apparatus at high speed. That is, according to the present embodiment, the link quality and the degree of congestion can be comprehensively evaluated and packets can be appropriately distributed, and a high-performance multilink communication device 10 can be provided.

  The measuring unit 31 of this embodiment corresponds to the measuring unit of the present invention, the data allocating unit 35 corresponds to the transmission control unit of the present invention, and the measurement time setting unit 33 is the interval measuring unit of the present invention. And measurement time setting means. In addition, the carrier sense off time corresponds to the non-transmission time of the present invention.

  In this embodiment, packets are distributed to links having a long carrier sense off time. However, the multilink communication apparatus 10 distributes packets based on the ratio of the carrier sense off times of the links L1 and L2. May be configured to perform.

  FIG. 7 is a flowchart showing data distribution processing repeatedly executed by the data distribution unit 35 in the multilink communication device 10 of the second embodiment. Since the multilink communication device 10 of the second embodiment described below is different from the multilink communication device 10 of the first embodiment in part of the data distribution process, FIG. 7 is used in the following. Only the data distribution process executed by the data distribution unit 35 in the multilink communication apparatus 10 according to the second embodiment will be described. In addition, here, the same step number is assigned to the step that executes the process having the same content as in the first embodiment, and the description of the process content related to that step is omitted as appropriate.

  When the data distribution process is started, the data distribution unit 35 waits until the transmission target packet is input from the in-vehicle device 5 (S300). When the transmission target packet is input (Yes in S300), S3100 The latest carrier sense off time T_CS [1] obtained from the measuring unit 31 corresponding to the link L1 and the latest carrier sense off time T_CS [obtained from the measuring unit 31 corresponding to the link L2 2], the value R is calculated according to the following equation.

R = T_CS [1] / (T_CS [1] + T_CS [2])
When this process is finished, the data distribution unit 35 proceeds to S3103, generates a random number α satisfying 0 ≦ α ≦ 1, and sets the random number α to the threshold Th0 (Th0 = α). When the processing in S3103 is completed, the data distribution unit 35 proceeds to S3105 and determines whether or not the calculated value R is greater than the set threshold Th0 (S3105).

  If it is determined that the value R is greater than the threshold value Th0 (Yes in S3105), the process proceeds to S320, where the transmission buffer amount Buf1 of the first wireless communication interface 20a is checked, and in the same manner as in the first embodiment. Execute subsequent processing. That is, when the transmission buffer amount Buf1 of the first wireless communication interface 20a is smaller than the maximum accumulation amount of the transmission buffer in the first wireless communication interface 20a (Yes in S330), the input transmission target packet is changed to the first packet. The packet is distributed to one wireless communication interface 20a, and the first wireless communication interface 20a transmits the packet to the external apparatus in a wireless form (S340). Thereafter, the data distribution process ends.

  On the other hand, when determining that the value R is equal to or less than the threshold Th0 (No in S3105), the data distribution unit 35 proceeds to S360, checks the transmission buffer amount Buf2 of the second wireless communication interface 20b, and further, Subsequent processing is executed in the same manner as in the first embodiment. That is, it is determined whether or not the transmission buffer amount Buf2 of the second wireless communication interface 20b is smaller than the maximum accumulation amount of the transmission buffer in the second wireless communication interface 20b (S370), and if smaller (Yes in S370). The input packet to be transmitted is distributed to the second wireless communication interface 20b, and the second wireless communication interface 20b transmits the packet to the external device in a wireless form (S380). Thereafter, the data distribution process is temporarily terminated.

  In this way, the data distribution unit 35 of the multilink communication device 10 in the second embodiment performs carrier sense off every time a transmission target packet is input from the in-vehicle device 5 unless the transmission buffer is full. Based on the time ratio, the packet input from the in-vehicle device 5 is distributed, and the packet is transmitted to the distribution destination wireless communication interface in a wireless form.

  As described above, the multilink communication device 10 of the second embodiment has been described, but also in this communication device, data can be appropriately distributed according to the free state of each link as in the first embodiment. Therefore, according to the present embodiment, packets can be appropriately distributed according to the link quality and the degree of congestion, and the packets can be efficiently transmitted to the external device.

  In addition, when all the links are in an idle state where data transmission is not performed, the multilink communication device 10 described above estimates the remaining time until data transmission is resumed in each link, and based on the estimation result. The packet may be distributed.

  FIG. 8 is a flowchart showing the measurement editing process executed by each measurement unit 31 together with the measurement process shown in FIG. 3 in the multilink communication device 10 of the third embodiment. FIG. 9 is an explanatory diagram showing an example of a histogram edited in the measurement editing process. FIG. 10 shows a data distribution unit 35 in the multilink communication apparatus 10 according to the third embodiment. 8 is a flowchart showing a data distribution process to be executed instead of the process shown in FIG. 7.

  Since the multilink communication device 10 of the third embodiment is different in the processing operation of the measurement unit 31 and the processing operation of the data distribution unit 35 from the multilink communication device 10 of the first and second embodiments. Hereinafter, with reference to FIGS. 8 to 10, the measurement editing process executed by each measurement unit 31 for each link and the data distribution process executed by the data distribution unit 35 in the multilink communication device 10 of the third embodiment. Only explained.

  Each measuring unit 31 of the present embodiment repeatedly executes the measurement editing process shown in FIG. 8, so that the elapsed time after the output signal of the carrier sense unit 27 of the corresponding wireless communication interface is switched to the carrier sense off signal. And the idle time of the corresponding link are repeatedly measured.

  Specifically, when the measurement editing process is started, the measurement unit 31 clears the time measurement counter independent of the measurement process counter (S410), and based on the output signal from the corresponding carrier sense unit 27. Then, it is determined whether the output signal is a carrier sense on signal (S420). If the output signal from the carrier sense unit 27 is a carrier sense on signal (Yes in S420), the process proceeds to S425. When the output signal from the carrier sense unit 27 is a carrier sense off signal (No in S420), the process proceeds to S425 when the output signal is switched to the carrier sense on signal.

  After shifting to S425, the measurement unit 31 thereafter waits until the output signal is switched from the carrier sense ON signal to the carrier sense OFF signal. When the output signal is switched to the carrier sense OFF signal, the measurement unit 31 shifts to S430, and in S410. The counter that has been cleared is operated to start measuring the elapsed time after the output signal is switched to the carrier sense off signal.

  When the processing in S430 is completed, the measurement unit 31 determines whether or not an inquiry about the elapsed time has occurred from the data distribution unit 35 (S440), and when the inquiry has occurred (S440). Yes), the current value of the counter is output as the elapsed time T_PS [i] to the inquiry source data distribution unit 35 (S445), and the process proceeds to S450. On the other hand, when the measurement unit 31 determines that an inquiry about the elapsed time has not occurred from the data distribution unit 35 (No in S440), the measurement unit 31 proceeds to S450 without executing the processing of S445.

  After shifting to S450, the measurement unit 31 determines whether or not the output signal from the corresponding carrier sense unit 27 has been switched to the carrier sense on signal, and determines that the output signal has not been switched to the carrier sense on signal (S450). No), the process proceeds to S440. On the other hand, if it is determined that the output signal is switched to the carrier sense ON signal (Yes in S450), the counter is stopped (S460), and the histogram of the link corresponding to the measurement unit 31 is edited based on the counter value at that time. (S470).

  As shown in FIG. 9, in the histogram edited in the present embodiment, the idle time as the duration of the carrier sense off signal is classified for each predetermined section, and the idle time belonging to the section is detected for each class. The number of occurrences is expressed as a percentage of the entire interval as the appearance frequency. This histogram is generated for each link, recorded in the RAM, and edited by the measurement editing process. However, in FIG. 9, the histogram is visually represented by a bar graph. The histogram actually recorded in the RAM depends on a fraction such as the number of detections of idle time belonging to the class / the total number of samples in all classes for each class. It is assumed that data of an expression method is described.

  That is, when the process proceeds to S470, the measurement unit 31 increments the detection count of the class corresponding to the idle time indicated by the counter by 1 in the corresponding link histogram, and increments the total number of samples by 1. Update the appearance frequency of each class in the histogram.

In addition, when the process in S470 is completed in this way, the measurement unit 31 once ends the measurement editing process, and again proceeds to S410.
On the other hand, the data distribution unit 35 in the present embodiment executes the data distribution process shown in FIG. 10, and determines each packet to be transmitted input from the in-vehicle device 5 based on the histogram of each link as the first and It distributes to either of the second wireless communication interfaces 20a and 20b.

  Specifically, when the data distribution process shown in FIG. 10 is started, the data distribution unit 35 waits until the transmission target packet is input from the in-vehicle device 5 (S500), and the transmission target packet is input. (Yes in S500), the process proceeds to S510, and it is determined whether or not all links are idle. That is, it is determined whether data transmission is not performed on all the links and a carrier sense off signal is output from all the carrier sense units 27 (S510).

  If it is determined that all links are not idle (No in S510), the process proceeds to S520, and normal processing is executed. Note that the normal processing here is the same as the processing surrounded by a dotted line in FIG. 5 or FIG. In other words, when the process proceeds to S520, the data distribution unit 35 transmits the transmission target packet input from the in-vehicle device 5 based on the carrier sense off times T_CS [1] and T_CS [2] to the first and second radios. Assign to either of the communication interfaces 20a and 20b. After that, the data distribution process is temporarily terminated, the process proceeds to S500 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  On the other hand, if it is determined in S510 that all the links are idle (Yes in S510), the data distribution unit 35 proceeds to S530, and the elapsed time T_PS [1] of the link L1 is associated with the link L1. The elapsed time T_PS [2] of the link L2 is acquired from the measuring unit 31 corresponding to the link L2 by the above inquiry (S530).

  When this processing is completed, the data distribution unit 35 proceeds to S540, determines the class having the maximum value (appearance frequency) from the histogram of the link L1, and then calculates the median T_CT [1 of the determined class. ], The remaining time T_RS [1] from when the idle state is terminated on the link L1 until the next data transmission is started is estimated (S550).

T_RS [1] = T_CT [1] −T_PS [1]
For example, in the histogram of the link L1 shown in FIG. 9, since the appearance frequency of the class of 500 to 600 μs (microseconds) is the maximum, using the median T_CT [1] = 550 μs of this class, Time T_RS [1] is calculated (S550).

  In addition, when the processing in S550 is completed, the data distribution unit 35 proceeds to S560, determines the class having the maximum value (appearance frequency) from the histogram of the link L2, and then calculates the median value T_CT of the determined class. Based on [2], the remaining time T_RS [2] until the idle state is completed on the link L2 and the next data transmission is started is estimated by the following equation (S570).

T_RS [2] = T_CT [2] −T_PS [2]
When the processing of S570 is completed, the data distribution unit 35 determines whether or not the time T_RS [1] is larger than the time T_RS [2] (S580), and T_RS [1]> T_RS [2]. If it is determined that there is (Yes in S580), processing similar to the processing after S320 shown in FIG. 5 is executed. That is, as long as the transmission buffer of the first wireless communication interface 20a is not full, the transmission target packet input from the in-vehicle device 5 is distributed to the first wireless communication interface 20a, and the first wireless communication interface 20a The corresponding packet is transmitted to an external device in a wireless form. Thereafter, the data distribution process is temporarily terminated, and the process proceeds to S500 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  On the other hand, if it is determined in S580 that T_RS [1]> T_RS [2] is not satisfied (No in S580), the data distribution unit 35 performs the same processing as the processing after S360 shown in FIG. That is, unless the transmission buffer of the second wireless communication interface 20b is full, the packet to be transmitted input from the in-vehicle device 5 is distributed to the second wireless communication interface 20b, and the second wireless communication interface 20b The corresponding packet is transmitted to an external device in a wireless form. Thereafter, the data distribution process is temporarily terminated, and the process proceeds to S500 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  The multilink communication device 10 according to the third embodiment has been described above. In this multilink communication device 10, when all the links are in non-data transmission (idle), the idle time having the maximum appearance frequency for each link. The remaining time until the next data transmission is started on each link is estimated from the idle time and the duration of the idle state at the present time. Based on the estimation results, the remaining time The packet is distributed to the wireless communication interface that uses the larger link.

  Therefore, according to this embodiment, the transmission target packet of the own device is externally transmitted during the period when the other communication device is not transmitting data through the link having the longest time until data transmission by the other communication device is performed. Data can be transmitted toward the apparatus, and a data transmission operation can be realized without much collision with other communication apparatuses. Therefore, if the network system 1 is constructed using the multilink communication device 10 of the present embodiment, it is possible to suppress a decrease in throughput due to collisions between the communication devices.

The elapsed time measuring means and the idle time measuring means of the present invention are realized by a measurement editing process executed by the measuring unit 31 in this embodiment.
Further, the multilink communication device 10 of the first and second embodiments described above estimates the remaining time until data transmission is completed in each link during the period in which all links perform data transmission. Based on the above, the packet may be distributed.

  FIG. 11 is a flowchart showing a measurement editing process executed by each measurement unit 31 together with the measurement process shown in FIG. 3 in the multilink communication device 10 of the fourth embodiment. FIG. 12 is an explanatory diagram showing an example of a histogram edited in the measurement editing process of the fourth embodiment, and FIG. 13 shows a data distribution unit 35 in the multilink communication apparatus 10 of the fourth embodiment. FIG. 11 is a flowchart showing data distribution processing to be executed instead of the processing shown in FIGS. 5, 7, and 10.

  Since the multilink communication device 10 of the fourth embodiment is different in the processing operation of the measurement unit 31 and the processing operation of the data distribution unit 35 from the multilink communication device 10 of the first and second embodiments. Hereinafter, with reference to FIGS. 11 to 13, the measurement editing process executed by each measurement unit 31 for each link and the data distribution process executed by the data distribution unit 35 in the multilink communication device 10 of the fourth embodiment. Only explained.

  Each measurement unit 31 of the present embodiment repeatedly executes the measurement editing process shown in FIG. 11 so that the output signal is changed from the carrier sense off signal to the carrier sense based on the output signal of the carrier sense unit 27 of the corresponding wireless communication interface. The elapsed time after switching to the ON signal and the transmission time as the time that the output signal continues with the carrier sense ON signal are repeatedly measured.

  Specifically, when the measurement editing process is started, the measurement unit 31 clears the time measurement counter independent of the measurement process counter (S610), and based on the output signal from the corresponding carrier sense unit 27. Whether or not the output signal is a carrier sense off signal (S620). If the output signal from the carrier sense unit 27 is a carrier sense off signal (Yes in S620), the process proceeds to S625. When the output signal from the carrier sense unit 27 is a carrier sense on signal (No in S620), the process proceeds to S625 when the output signal is switched to the carrier sense off signal.

  After shifting to S625, the measurement unit 31 waits until the output signal is subsequently switched from the carrier sense off signal to the carrier sense on signal. When the output signal is switched to the carrier sense on signal, the measurement unit 31 proceeds to S630, and in S610. The counter that has been cleared is operated, and measurement of an elapsed time after the output signal is switched to the carrier sense on signal is started.

  When the process in S630 is completed, the measurement unit 31 determines whether or not an inquiry about elapsed time has occurred from the data distribution unit 35 (S640). If an inquiry has occurred (S640). Yes), the current value of the counter is output as the elapsed time T_PS [i] to the inquiry source data distribution unit 35 (S645), and the process proceeds to S650. On the other hand, when the measurement unit 31 determines that an inquiry about the elapsed time has not occurred from the data distribution unit 35 (No in S640), the measurement unit 31 proceeds to S650 without executing the processing of S645.

  After shifting to S650, the measurement unit 31 determines whether or not the output signal from the corresponding carrier sense unit 27 has been switched to the carrier sense off signal, and determines that the output signal has not been switched to the carrier sense off signal (S650). No), the process proceeds to S640. On the other hand, if it is determined that the output signal is switched to the carrier sense off signal (Yes in S650), the counter is stopped (S660), and the histogram of the link corresponding to the measurement unit 31 is edited based on the counter value at that time. (S670).

  As shown in FIG. 12, the histogram edited in the present embodiment classifies the transmission time as the duration of the carrier sense ON signal for each predetermined section, and the transmission time belonging to the section is detected for each class. The number of occurrences is expressed as a percentage of the entire interval as the appearance frequency. This histogram is generated for each link and recorded in the RAM, and each histogram describes, for each class, data of a representation method by a fraction such as the number of detections of transmission time belonging to that class / the total number of samples of all classes. .

  That is, when the process proceeds to S670, the measurement unit 31 increments the detection count of the class corresponding to the transmission time indicated by the counter by 1 in the corresponding link histogram, and increments the total number of samples by 1. Update the appearance frequency of each class in the histogram.

In addition, when the process in S670 is completed in this way, the measurement unit 31 once ends the measurement editing process, and again proceeds to S610.
On the other hand, the data distribution unit 35 in the present embodiment executes the data distribution process shown in FIG. 13, and determines each packet to be transmitted input from the in-vehicle device 5 based on the histogram of each link as the first and It distributes to either of the second wireless communication interfaces 20a and 20b.

  Specifically, when the data distribution process illustrated in FIG. 13 is started, the data distribution unit 35 waits until a transmission target packet is input from the in-vehicle device 5 (S700), and the transmission target packet is input. (Yes in S700), the process proceeds to S710 to determine whether or not all links are transmitting data. That is, it is determined whether data transmission is performed in all the links and a carrier sense ON signal is output from all the carrier sense units 27 (S710).

  If it is determined that all links are not transmitting data (No in S710), the data distribution unit 35 proceeds to S720 and executes normal processing. That is, when the process proceeds to S720, the data distribution unit 35 executes a process that matches the process surrounded by the dotted line in FIG. 5 or FIG. 7, and based on the carrier sense off times T_CS [1] and T_CS [2]. The transmission target packet input from the in-vehicle device 5 is distributed to one of the first and second wireless communication interfaces 20a and 20b. Thereafter, the data distribution process is temporarily ended, the process proceeds to S700 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  On the other hand, if it is determined in S710 that all links are transmitting data (Yes in S710), the data distribution unit 35 proceeds to S730 and sets the elapsed time T_PS [1] of the link L1 to the link L1. Obtained from the corresponding measurement unit 31 by the above inquiry, and the elapsed time T_PS [2] of the link L2 is obtained from the measurement unit 31 corresponding to the link L2 by the above inquiry.

  When this processing is completed, the data distribution unit 35 proceeds to S740 and, like the third embodiment, determines the class having the maximum value (appearance frequency) from the histogram of the link L1, and then calculates the class. Based on the median value T_CT [1] of the class, the remaining time T_RS [1] until the data transmission is completed on the link L1 is estimated by the following equation (S750).

T_RS [1] = T_CT [1] −T_PS [1]
In addition, when the processing in S750 is completed, the data distribution unit 35 proceeds to S760, determines the class having the maximum value (appearance frequency) from the histogram of the link L2, and then calculates the median value T_CT of the determined class. Based on [2], the remaining time T_RS [2] until the data transmission is completed in the link L2 is estimated by the following equation (S770).

T_RS [2] = T_CT [2] −T_PS [2]
When the process of S770 is completed, the data distribution unit 35 determines whether or not the time T_RS [1] is smaller than the time T_RS [2] (S780), and T_RS [1] <T_RS [2]. If it is determined that there is (Yes in S780), processing similar to the processing after S320 shown in FIG. 5 is executed. That is, unless the transmission buffer of the first wireless communication interface 20a is full, the packet to be transmitted input from the in-vehicle device 5 is distributed to the first wireless communication interface 20a, and the first wireless communication interface 20a The corresponding packet is transmitted to an external device in a wireless form. Thereafter, the data distribution process is temporarily terminated, the process proceeds to S700 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  On the other hand, if it is determined in S780 that T_RS [1] <T_RS [2] is not satisfied (No in S780), the data distribution unit 35 executes the same processing as S360 and subsequent steps shown in FIG. That is, unless the transmission buffer of the second wireless communication interface 20b is full, the packet to be transmitted input from the in-vehicle device 5 is distributed to the second wireless communication interface 20b, and the second wireless communication interface 20b The corresponding packet is transmitted to an external device in a wireless form. Thereafter, the data distribution process is temporarily terminated, the process proceeds to S700 again, and waits until the next transmission target packet is input from the in-vehicle device 5.

  As described above, the multilink communication device 10 according to the fourth embodiment has been described. In this multilink communication device 10, when all links are transmitting data, a transmission time with the maximum appearance frequency is derived for each link. The remaining time until data transmission is completed in each link is estimated from the transmission time and the elapsed time from the start of data transmission, and based on these estimation results, the radio using the link with the smaller remaining time The packet is distributed to the communication interface.

  Therefore, according to the present embodiment, it is possible to preferentially distribute packets to the wireless communication interface in which data transmission is completed early, and it is possible to efficiently transmit packets to an external device.

The elapsed time measuring means and the transmission time measuring means of the present invention are realized by a measurement editing process executed by the measurement unit 31 in this embodiment.
Further, when the other single link communication device 50 and the multilink communication device 10 participating in the network system 1 are configured to periodically transmit packets, the transmission of the packet that the other communication device transmits next time is performed. The multilink communication device 10 may be configured to predict the timing and transmit a packet to be transmitted in the own device from the own device.

  FIG. 14 shows a measurement estimation process that each measurement unit 31 performs repeatedly in place of the measurement process and the measurement editing process shown in FIGS. 3, 8, and 11 in the multilink communication device 10 of the fifth embodiment. It is a flowchart. FIG. 15A is an explanatory diagram showing a mode of packets periodically transmitted to the links L1 and L2. FIG. 15B is a diagram showing schedule data edited in the measurement estimation process. It is explanatory drawing showing a structure. In addition, FIG. 16 shows that in the multilink communication device 10 of the fifth embodiment, the data distribution unit 35 performs the data distribution process to be executed instead of the processes shown in FIGS. 5, 7, 10, and 13. It is a flowchart to represent.

  In the multilink communication device 10 of the fifth embodiment, the processing operation of the measurement unit 31 and the processing operation of the data distribution unit 35 are different, and all or some of the other communication devices of the participating network system 1 are Since the configuration is basically the same as that of the multilink communication apparatus 10 of the first embodiment except that the configuration is such that the packets are periodically transmitted, the following description will be made with reference to FIGS. Measurement estimation processing executed by each measurement unit 31 for each link and data distribution processing executed by the data distribution unit 35 in the multilink communication device 10 of the fifth embodiment will be described selectively.

  In the control circuit 30 of the present embodiment, as in the first embodiment, a measurement unit 31 realized by a program is provided for each link, and each measurement unit 31 receives from the carrier sense unit 27 of the corresponding link. Based on the output signal, the measurement estimation process shown in FIG. 14 is executed, and the future data transmission timing by the other communication device in the corresponding link is recorded in the schedule data.

  Specifically, when the measurement estimation process is started, the measurement unit 31 determines whether the output signal is a carrier sense off signal based on the output signal from the corresponding carrier sense unit 27 (S810). If the output signal from the sense unit 27 is a carrier sense off signal (Yes in S810), the process proceeds to S820, and if the output signal from the carrier sense unit 27 is a carrier sense on signal (No in S810) ), When the output signal is switched to the carrier sense off signal, the process proceeds to S820.

  When the process proceeds to S820, the measurement unit 31 waits until the output signal is subsequently switched from the carrier sense off signal to the carrier sense on signal. When the output signal is switched to the carrier sense on signal, the measurement unit 31 proceeds to S830, and the communication apparatus The time corresponding to the cycle Ts for sending the packet to the link and the future time when the current time is advanced are additionally written in the schedule data of the link as the next transmission start time by the communication device on the link. Moreover, after finishing the process in S830, the measurement part 31 once complete | finishes the said measurement estimation process, Then, it transfers to S810 again, and the output signal from the carrier sense part 27 changes from a carrier sense off signal to a carrier sense on signal. At the time of switching (Yes in S820), the time after one cycle Ts from the current time is additionally written to the schedule data in the schedule data of the corresponding link.

  In this way, as shown in FIG. 15B, the measurement unit 31 corresponding to the link L1 starts the start time of each data transmission that occurs in the near future in the link L1 to the schedule data of the link L1 recorded in the RAM. The measurement unit 31 corresponding to the link L2 records the start time of each data transmission occurring in the near future in the link L2 in the schedule data of the link L2 recorded in the RAM.

  For example, at the time point P shown in FIG. 15A, since the data transmission by the other communication device D1 and the data transmission by the other communication device D2 are performed on the link L1, the schedule data of the link L1 is other The next transmission start time by the communication device D1 and the next transmission start time by the other communication device D2 are recorded. Similarly, in the link L2, since the data transmission by the other communication device D5, the data transmission by the other communication device D3, and the data transmission by the other communication device D4 are performed, the schedule data of the link L2 is the other communication device. Next transmission start time by D5, next transmission start time by other communication device D3, and next transmission start time by other communication device D4 are recorded.

  Next, the data distribution process shown in FIG. 16 that is repeatedly executed by the data distribution unit 35 of the present embodiment will be described. When the data distribution process shown in FIG. 16 is started, the data distribution unit 35 waits until a transmission target packet is input from the in-vehicle device 5 (S900), and when a transmission target packet is input (in S900) Yes), the process proceeds to S903, and the remaining time T_FR [1] until data transmission is performed in the link L1 is calculated from the schedule data of the link L1. Specifically, in S903, if the link L1 is already transmitting data, T_FR [1] = 0 is set, and if the link L1 is idle, the future future closest to the current time indicated by the schedule data is set. The time corresponding to the difference between the next transmission start time and the current time is calculated as T_FR [1].

  For example, in the environment shown in FIG. 15A, when a packet to be transmitted is input from the in-vehicle device 5 at the time point P, the time until data transmission by the other communication device D1 is performed on the link L1 is expressed as T_FR. Calculated as [1].

  In addition, when the processing in S903 is completed in this way, the data distribution unit 35 proceeds to S907 and performs the same processing as S903 for the link L2. That is, the remaining time T_FR [2] until data transmission is performed on the link L2 is calculated from the schedule data of the link L2.

  After completing the process in S907, the data distribution unit 35 proceeds to S910, determines whether or not the time T_FR [1] is larger than the time T_FR [2], and T_FR [1]> T_FR [ 2] (Yes in S910), the process proceeds to S920, and the processes after S920 are executed. The processing after S920 is the same as the processing after S320 in the first embodiment, as can be understood by comparing FIG. 16 and FIG. That is, each step S9 ** (** is an arbitrary number) of S920 to S990 is a step for performing the same processing as step S3 ** in which the last two digits are the same. Therefore, the description of the processing after S920 is omitted here.

  In addition, if it is determined in S910 that T_FR [1]> T_FR [2] is not satisfied (No in S910), the data distribution unit 35 proceeds to S960 and performs the same processing as S360 and subsequent steps in S960. Execute in subsequent processing.

  In this way, the data distribution unit 35 according to the present exemplary embodiment, when T_FR [1]> T_FR [2], unless the transmission buffer is full, the first wireless communication interface 20a includes the in-vehicle device. The packet input from the device 5 is distributed, and the first wireless communication interface 20a that is the distribution destination is caused to transmit the packet to the external device in a wireless form. Further, when T_FR [1]> T_FR [2] is not satisfied, the data distribution unit 35 distributes the packet input from the in-vehicle device 5 to the second wireless communication interface 20b, and distributes the second wireless communication interface as a distribution destination. In 20b, the corresponding packet is transmitted to the external apparatus in a wireless form.

  The multilink communication device 10 according to the fifth embodiment has been described above. In this multilink communication device 10, the communication device other than its own device that uses each link transmits data transmission using the link. Based on these estimation results, the packet to be transmitted is distributed to one of the first and second wireless communication interfaces 20b, and the packet is distributed to the wireless communication interface of the distribution destination to the external device. Send it.

  Therefore, according to the multilink communication device 10 of the present embodiment, during the period when the other communication device is not performing data transmission without much interference with the data transmission operation of the other communication device that performs data transmission using the same link. The data transmission operation can be executed by the own device. Therefore, according to the present embodiment, collision with other communication devices hardly occurs, a reduction in throughput can be suppressed, and transmission target packets are efficiently distributed to wireless communication interfaces corresponding to free links. be able to.

Note that the estimation means of the present invention is realized by measurement estimation processing executed by the measurement unit 31 in this embodiment.
Although the first to fifth embodiments have been described above, the present invention is not limited to the above-described embodiments, and can take various forms.

  For example, in the first embodiment, the multilink communication apparatus 10 is configured such that the measurement time Tm is not shorter than the idle time of each link, but the measurement time Tm may be a fixed value.

  Further, in the first embodiment, the network system 1 is composed of a group of multilink communication devices 10, and each multilink communication device 10 transmits a plurality of links at a certain time interval to each packet constituting transmission target data. If each packet is distributed in order and sent to an external device at a fixed interval, the number of links, that is, the radio included in the multilink communication device 10 is included in the packet transmission interval. The time multiplied by the number of communication interfaces may be set as the measurement time Tm. That is, when each multilink device is configured to sequentially distribute packets to n links and transmit packets at the transmission interval Td, the measurement time Tm is set to Tm = Td · n. Good.

If the measurement time Tm is set in this way, the degree of congestion of each link can be appropriately evaluated with a short measurement time Tm, and each packet can be appropriately distributed.
That is, in this case, the multilink communication device 10 distributes packets to each link in order at a constant time interval, so packets are sequentially transmitted in the order of L1, L2, L3,..., Ln to n links L1 to Ln. , Ln, Ln-1, Ln-2,..., L1 or the distribution order differs for each multilink communication device 10, but each multilink communication device 10 has a time Tm. In the meantime, a packet is sent once for each link.

  Therefore, if the measurement time Tm is set to the measurement time Tm = Td · n, the deviation of the packet distribution timing to each link can be grasped efficiently in a short time by the carrier sense off time. In the link communication device 10, packets can be distributed to any of the links in an appropriate order while considering the packet distribution order in the other multilink communication devices 10. Therefore, if the measurement time Tm is set as described above, it is possible to efficiently evaluate the deviation of the packet distribution timing to each link, and the overall throughput of the network system 1 can be improved.

  In the above embodiment, the multilink communication device 10 is configured to discard the packet when the transmission buffer amount of the links L1 and L2 is greater than or equal to the limit value. However, the data distribution unit 35 is provided with a buffer. Thus, when the packet is not discarded and any of the transmission buffers of both the links L1 and L2 becomes empty, the packet stored in the buffer of the data distribution unit 35 is transferred to either of the links L1 and L2. You may comprise the multilink communication apparatus 10 so that it may distribute.

1 is an explanatory diagram illustrating a configuration of a network system 1 having a multilink communication device 10. FIG. 2 is a block diagram illustrating a configuration of a multilink communication device 10. FIG. It is a flowchart showing the measurement process which the measurement part 31 repeatedly performs. It is a flowchart showing the measurement time setting process which the measurement time setting part 33 performs repeatedly. It is a flowchart showing the data distribution process which the data distribution part 35 performs repeatedly. It is explanatory drawing regarding the data transmission aspect in link L1, L2. In a 2nd Example, it is a flowchart showing the data distribution process which the data distribution part 35 repeatedly performs. 12 is a flowchart showing a measurement editing process executed by a measurement unit 31 in the third embodiment. It is explanatory drawing showing an example of the histogram of 3rd Example. In a 3rd Example, it is a flowchart showing the data distribution process which the data distribution part 35 repeatedly performs. 14 is a flowchart illustrating a measurement editing process executed by a measurement unit 31 in the fourth embodiment. It is explanatory drawing showing an example of the histogram of 4th Example. In a 4th Example, it is a flowchart showing the data distribution process which the data distribution part 35 repeatedly performs. In a 5th Example, it is a flowchart showing the measurement estimation process which the measurement part 31 performs. It is explanatory drawing showing the aspect of the packet periodically transmitted to link L1, L2. In a 5th Example, it is a flowchart showing the data distribution process which the data distribution part 35 performs repeatedly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Network system, 5 ... In-vehicle apparatus, 10 ... Multilink communication apparatus, 20 ... Wireless communication interface, 20a ... 1st wireless communication interface, 20b ... 2nd wireless communication interface, 21 ... Transmission / reception antenna, 23 ... Communication control part, 25 ... Reception intensity detection unit, 27 ... Carrier sense unit, 30 ... Control circuit, 31 ... Measurement unit, 33 ... Measurement time setting unit, 35 ... Data distribution unit, 50 ... Single link communication device

Claims (14)

A plurality of communication interfaces for transmitting data to external devices through different transmission paths are provided. Data to be transmitted is distributed to one of the plurality of communication interfaces for each unit data, and the transmission is performed through the plurality of transmission paths. A communication device that transmits target data to an external device,
A measuring means for each communication interface for measuring a non-transmission time, which is a time during which data transmission is not performed in the transmission path used by the communication interface;
Based on the measurement result of each measurement means, the transmission target data is distributed to any of the plurality of communication interfaces for each unit data, and the data corresponding to the communication interface of the distribution destination is transmitted to the external device. Control means;
A communication apparatus comprising:   The transmission control unit is configured to distribute data to a communication interface corresponding to a transmission line having the longest non-transmission time based on a measurement result of each measurement unit at that time when distributing data. The communication apparatus according to claim 1, wherein:   The transmission control unit is configured to determine a communication interface for distributing data according to a ratio of non-transmission time in each transmission path based on a measurement result of each measurement unit at that time when distributing data. The communication device according to claim 1, wherein:   Each of the measuring means is configured to measure a total time during which data transmission is not performed in a transmission path used by a communication interface within a preset measurement time as the non-transmission time. The communication apparatus according to any one of claims 1 to 3. An interval measuring means for each communication interface for measuring a transmission interval as a time interval from the end of data transmission in the transmission path used by the communication interface to the start of the next data transmission;
Based on the measurement result of each interval measurement means, measurement time setting means for setting the measurement time so as not to be shorter than any of the transmission intervals of each transmission path,
The communication apparatus according to claim 4, further comprising: In the group of transmission lines used by the communication device, the unit data is distributed in order at regular intervals to the transmission lines belonging to the group of transmission lines, and the unit data is configured as a group of the transmission lines. Multiple external devices that send to either
5. The communication apparatus according to claim 4, wherein the measurement time is a time obtained by multiplying a transmission interval of data transmitted by the external apparatus by the number of communication interfaces provided in the communication apparatus.   7. The communication apparatus according to claim 1, wherein each of the measurement units measures, as the non-transmission time, a time when the intensity of a signal received by the communication interface is equal to or less than a threshold value. For each communication interface provided by the device,
An elapsed time measuring means for measuring an elapsed time from the start of data transmission every time data transmission is performed in a transmission path used by a communication interface;
A transmission time measuring means for measuring a transmission time as a time from the start of the data transmission to the completion of the data transmission each time data transmission is performed in the transmission path used by the communication interface;
With
The transmission control means, when allocating data, if all transmission paths are transmitting data, based on the measurement result of each elapsed time measurement means at this time and the measurement history of each transmission time measurement means 8. The communication apparatus according to claim 1, wherein a communication interface for distributing data is determined. The transmission control means, when all transmission paths are in data transmission,
For each transmission path, a transmission time having the highest frequency in the past is derived from the measurement history of the corresponding transmission time measuring means, and the transmission corresponding to this transmission time and the measurement result of the corresponding elapsed time measuring means Estimate the remaining time until data transmission is complete on the road,
9. The communication apparatus according to claim 8, wherein the communication device is configured to distribute data to a communication interface that uses a transmission path having the minimum remaining time based on the estimation results. For each communication interface provided by the device,
An elapsed time measuring means for measuring an elapsed time from the end of the data transmission every time data transmission is completed in the transmission path used by the communication interface;
An idle time measuring means for measuring an idle time as a time from the end of the data transmission to the start of the next data transmission every time data transmission is completed in the transmission path used by the communication interface;
With
When the transmission control unit distributes data, and all the transmission lines are not transmitting data, the measurement result of each elapsed time measurement unit and the measurement history of each idle time measurement unit at this point are used. 8. The communication apparatus according to claim 1, wherein a communication interface for allocating data is determined based on the communication interface. The transmission control means, when all transmission paths are in non-data transmission,
For each transmission path, the idle time having the highest frequency in the past is derived from the measurement history of the corresponding idle time measuring means, and the corresponding transmission is determined from the idle time and the measurement result of the corresponding elapsed time measuring means. Estimate the remaining time until data transmission starts on the road,
11. The communication apparatus according to claim 10, wherein the communication apparatus is configured to distribute data to a communication interface that uses the transmission path having the maximum remaining time based on these estimation results. A plurality of communication interfaces for transmitting data to external devices through different transmission paths are provided. Data to be transmitted is distributed to one of the plurality of communication interfaces for each unit data, and the transmission is performed through the plurality of transmission paths. A communication device that transmits target data to an external device,
For each communication interface provided by the device,
An external device that uses the same transmission path as the transmission path used by the communication interface includes an estimation unit that estimates the timing for performing data transmission using the transmission path for each external device, and
Based on the estimation results of the respective estimation means, transmission control means for assigning transmission target data to any one of the plurality of communication interfaces for each unit data and transmitting data corresponding to the communication interface of the distribution destination to an external device A communication apparatus comprising: In a computer of a communication device including a plurality of communication interfaces for transmitting data to an external device through different transmission paths,
A measuring means for each communication interface for measuring a non-transmission time, which is a time during which data transmission is not performed in the transmission path used by the communication interface;
Based on the measurement result of each measurement means, transmission control means for assigning transmission target data to any one of the plurality of communication interfaces for each unit data and transmitting data corresponding to the communication interface of the distribution destination to an external device A program to realize the functions as In a computer of a communication device including a plurality of communication interfaces for transmitting data to an external device through different transmission paths,
Estimating means for each communication interface for estimating, for each external device, the timing at which the external device using the same transmission path as the transmission path used by the communication interface performs data transmission using the transmission path;
Based on the estimation results of the respective estimation means, transmission control means for assigning transmission target data to any one of the plurality of communication interfaces for each unit data and transmitting data corresponding to the communication interface of the distribution destination to an external device A program to realize the functions as