JP2000216815A - Multilink communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilink communication equipment improving the effective band using efficiency of the whole system by matching the sorting quantity of communication with the effective transmitting rate of each line at the time of simultaneously using plural lines. SOLUTION: A multilink processing part 14 is provided with the function of monitoring a line and provided with a function executing sorting of communication according to the effective transmitting rate of each line based on the result of monitoring. Thus, it is always avoided to generate excessive delay and to apply an excessive load with respect to each line and realizes low-delay and efficient communication through the multilink as a whole. In addition, a function capable of estimating the effective transmitting rate of the line by simple processing by monitoring resending generated at the line is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus having a multilink function for providing a plurality of lines as one virtual line.

[0002]

2. Description of the Related Art A surge in demand for data communication requires a large-capacity communication line. However, simply increasing the speed is often limited by the investment and time required for technology and system construction. In such a case, by simultaneously using a plurality of existing communication lines and providing an interface that can be virtually treated as one communication line to the upper layer, the communication capacity can be expanded without changing the upper layer. it can. This method is called "multi-link" or "multi-connection". Multilink is generally provided as a link layer function, and an upper network layer function can transmit communication information to the multilink without distinguishing individual communication lines. Also, even when the network layer function supports a plurality of communications with different service qualities, the network layer function only needs to present the quality of each communication to the multilink function to transfer the communication information. The use of individual lines according to the communication quality is performed by the multilink function. Therefore, also in this case, the network layer function does not need to distinguish individual lines in the multilink. A multilink can be configured using a plurality of virtual / logical lines set up on a network. In this mode, the multilink function operates as an upper layer of the network layer function, but the processing inside is the same as the processing in the link layer, and a function similar to the network layer function is added on the multilink function. Therefore, the multi-link function is essentially the same as the case where it is provided as a link layer function. Therefore, the following description in this specification includes such a form.

[0003] As an example of a technique for realizing a multilink function, in an IP (Internet Protocol) communication, a multilink protocol (MP: Multi) is used.
ilink Protocol, RFC 1990)
It has been known. In this MP, a protocol is designed with emphasis on using a plurality of lines and preventing the transmission order of IP packets handled in the process from being changed. This is because some applications operate on the assumption that packets arrive in the order of transmission to applications using IP communication. By using the MP, a large-capacity communication path can be easily set.

[0004]

By the way, the conventional multilink is considered mainly for use on a line having a low error rate, and the transmission speed of each line has been regarded as being constant. Therefore, the distribution of communication to each line has been fixed once set. However, if this is used in a system where the error rate is higher than that of a wired line such as a wireless line, or the quality of the line fluctuates with time, the amount of communication is reduced to the effective transmission speed of each line. There are lines that do not match and communication is not easily completed. As a result, there is a problem that the effective band use efficiency is lowered as a whole. In particular, when control having a function of preventing order inversion is performed like MP, the average transmission delay also increases, and this tendency becomes remarkable.

Therefore, in the present invention, multi-link processing
By providing a line monitoring function and a function to sort communications according to the effective transmission speed of each line based on the monitoring result, overall low-latency, efficient multilink communication is provided. Realize.

[0006]

In order to solve the above-mentioned problems, the present invention provides a plurality of logical communication lines including a communication line whose effective transmission speed fluctuates between opposing devices. A communication device having a multi-link communication function capable of exchanging various data with a higher-level function without distinguishing each of the plurality of lines by showing them as one virtual communication line at the same time. Provided is a multilink communication device having a function of monitoring an effective transmission speed of a line and a function of distributing data according to the effective transmission speed of each line.

In particular, when the communication line includes a wireless communication line, a function of monitoring the effective transmission speed of the wireless communication line is also provided.

[0008] Even if the communication device includes a line whose communication quality fluctuates, data of a capacity corresponding to the effective communication speed of each line forming the multilink is always transferred, so that excessive delay in communication is caused. Optimum communication state can be maintained without giving an excessive load to the line or applying an excessive load to the line. In particular, even when the line condition fluctuates, such as when using a wireless line involving movement, stable data communication can be ensured by performing dynamic data transfer distribution according to the present invention.

Further, in the present invention, the line includes a line having a function of retransmitting a communication error, and the monitoring function includes, for the line to be retransmitted, the number of retransmissions occurring on the line. The multi-link communication device is characterized in that the effective speed is calculated based on

Thus, the effective transmission speed of the line is easily estimated by a simple process.

Alternatively, a system for providing one of the wireless communication lines is developed along a route on which a mobile unit using the communication device moves, and a function of monitoring an effective transmission speed of each line; A multi-link communication apparatus is provided, which has a function of sorting data according to a cycle of a communication state change occurring in a wireless communication line developed along the route and an effective transmission speed of each line.

[0012] By using such a device, the ITS
(Intelligent Transport Sy
In the case of a multi-link including a wireless channel in which handovers such as a “stem”) and a valley of fading occur periodically,
The present invention provides multilink communication that keeps the line use efficiency high because data distribution can be realized in consideration of the quality change.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a first embodiment showing a multilink communication apparatus according to the present invention. The communication device 10 includes a communication control unit 13, a multilink processing unit 14, a transmission / reception unit 15-1.
~ 3. The communication device 10 includes three transmission / reception units, each of which faces the communication device 1 via a line.
1 connected. The configuration of the communication device 11 is the same as that of the communication device 11, and includes a communication control unit 21, a multilink processing unit 14, transmission / reception units 19-1 to 19-3, a handset 2
2 and a data signal terminal 17. With such a configuration, communication is performed between the communication devices 10 and 11. The communication control unit performs general processing necessary for the communication device. For example, the voice input from the handset 16 is converted into a signal in a format used for communication and delivered to the multilink processing unit 14.
Alternatively, when the received signal is input through the transmission / reception unit and the multilink processing unit 14, the signal is returned to the original signal format. For example, if the signal is a data signal, the signal is output to the data signal terminal 17. I do. The multilink processing unit 14 has a function of allocating a signal from the communication control unit to a plurality of lines 18-1 to 3 connected to each other, collecting signals received by each line, and restoring a signal before division. . The transmission / reception units 15-1 to 15-3 transmit and receive signals via the lines 18-1 to 18-1.

The format of the signal exchanged between the multilink processing unit 14 and the communication control unit is a format having a finite length such as a packet. The multilink processing unit 14 shown in FIG. 2 divides a packet to be transmitted into short packets of a length corresponding to the bandwidth of each output line by a packet dividing unit 33,
Each short packet is sent to the corresponding transmitting / receiving section 15-1 to 15-3. FIG. 3 shows a configuration example of the short packet 41. At the head is a sequence section 42. The multilink processing unit 14 has a counter 31 to which an initial value is given when the processing is started.
, And the short packets are numbered sequentially in the division process. The sequence number is inserted into the part. If the short packet consists of the beginning or end of the original packet, a flag bit 4 indicating this is used.
There are 3,44. Each transmission / reception unit sends the short packet to the line. Each of the opposing transmission / reception units 19-1 to 19-3 passes the short packet to the multilink processing unit 20 when receiving the short packet. The multilink processing unit 20 includes
Based on the sequence number assigned to the short packet passed from -1 to -3, the original packet is synthesized and restored. The restored packet is passed to the communication control unit 21, where necessary processing is performed and output. Communication in the direction from the communication device 11 to the communication device 10 is performed in the same manner. The counter of each multilink processing unit has
A 16-bit or 32-bit counter is used so that the period becomes sufficiently long. For this reason, even if the counter repeatedly uses the number, it is almost impossible that the same number is given to the short packets transmitted at the same time. Then, the received multilink processing unit can correctly reproduce the packet.

As described above, when restoring a packet in the multilink processing unit, restoration is performed based on the sequence number of the received short packet. Also, short packets have flags indicating the beginning and end of the restored packet, so that no matter which short packet is transmitted to which line,
The original packet can be restored.

In a system in which the order of short packets is not reversed due to retransmission or the like in the line portion, if a short packet is lost in the middle due to an error due to noise or the like, the next packet is restored by the subsequent short packet. Is detected. In this case, short packets related to packets that could not be restored are discarded. Further, in the case of a packet having a short packet length, if the packet is divided by the number of lines, each short packet becomes too small and the transfer efficiency is reduced, so that the packet may be divided into a number smaller than the number of lines. If there is such a packet, there is a possibility that the above-described packet loss detection method may be erroneous and that the order of the packets may be changed so as to confuse the application. For example, there are three lines a, b, and c, and packet A is divided into three short packets Aa, Ab, and Ac and sent to each line, and the next short packet B Short packet B
-A, B-b, and are assigned to lines a and b. At this time, if a large delay occurs due to retransmission or the like on the line c to which Ba and Bb were not transferred, the short packets Ba and Bb that passed through the normal lines a and b would be A.
The packet arrives at the receiving side earlier than -c and is reproduced in the original packet B. Then, the previously received A-a, A-
b is discarded, and the reproduced packet B is passed to the communication control unit. Alternatively, even if Aa and Ab are not discarded, a short packet B reproduced before receiving Ac is passed to the communication control unit, and thereafter, Aa and A-
Since the original packet A is reproduced from b and Ac and passed to the communication control unit, the order of the packets received on the application side is changed. This may degrade the operation of the application. In order to prevent such a situation, a timer is provided on the receiving side, and even if a packet that comes later is played back first, it waits for the time set by the timer, and only when the first short packet is not played back during that time. The first short packet is discarded, and the reproduced packet is output. However, when this configuration is used, there is a problem in that an optimum timer is set and a delay is increased as a whole due to the above-described standby.

[0018] On the other hand, the multilink processing unit grasps the status of error detection and retransmission request occurring in the transmission / reception unit, so that it is possible to solve the problem by determining whether to wait for an unarrived short packet. . This is because it is possible to determine whether to wait for the arrival of the remaining short packets by checking for the presence or absence of the retransmitted short packets on the line through which the unarrived short packets are supposed to be transmitted. This configuration requires cooperation between the multilink processing unit and the transmission / reception unit for the reception operation, but is optimal in terms of the delay that occurs when unarrived short packets occur, packet loss, and prevention of packet rearrangement. Can be done.

In a system in which the order of short packets is reversed when retransmission is performed in the line section, even if an individual packet is divided so as to be always distributed to all lines, the reordering of the packets is performed by retransmission as described above. Occurs. In this case, the same measures as above are required.

The multilink processors 14 and 20 have a function of constantly monitoring the effective transmission speed of the line to which the transceivers 15-1 to 15-1 and 19-1 to 3 are connected.
Normally, each line has a rated transmission rate defined by the average or the maximum value, but its quality according to the mobile situation and other communication situations caused by using a wireless line or xDSL wired line. The effective transmission speed dynamically changes due to the temporal fluctuation of the transmission speed, the fluctuation of the available transmission speed given by the system caused by the ABR service of the ATM line, and the like. Even in such an environment, the effective transmission speed of each line is obtained using the monitoring function, and the packet division unit 33 of the multilink processing units 14 and 20 divides the input packet into short packets of a size corresponding thereto. I do. As a result, the maximum transmission rate can be obtained for the entire line with the optimal delay under the circumstances at that time. The monitoring function obtains the status of each line from each transmitting / receiving unit.
In the case of xDSL or ATM ABR service, the effective transmission rate itself is managed by the transmission / reception unit, and the information can be obtained. In the case of a wireless line, the monitoring unit can estimate the effective transmission rate by obtaining information such as the number of retransmissions. If this function is not provided, it will be effective to transmit data of the rated capacity even on the line where the transmission speed has deteriorated, so that the data will accumulate delays and the number of short packets stored in the queue will increase. Or overflow from the buffer. This affects not only the loss on the line but also the original packet itself including the affected short packet by the same delay and discard. In the multilink processing according to the present invention, by providing a monitoring function and a packet distribution control function based on the monitoring function, such a deterioration in overall communication efficiency does not occur, and as described above, the delay in the packet restoration is suppressed. There are also effects and the like, and these functions are important to always optimize the efficiency of the system.

FIG. 4 shows a flow of processing related to packet division performed in the multilink processing units 14 and 20 described above. It is determined whether there is a packet input (S5).
1) If there is a packet input, the input packet is divided into the number of lines at a division ratio calculated in advance (S52). Next, a short packet is formed by adding a header including an s-detection number to the divided packets (S5).
3). Then, the short packet is sent to the corresponding transmitting / receiving section (S54).

The packet division unit converts packets into short packets based on this flow, so that short packets can be distributed according to the effective transmission speed of each line. In this figure, it is assumed that the division ratio for each line has been calculated in advance. Since the division ratio is determined based on information appropriately obtained by the line monitoring unit as described above, the division ratio is separately calculated by the multilink processing unit periodically or whenever information from the line monitoring unit changes.

FIG. 5 shows another example of processing relating to packet division. First, it is determined whether a packet is input (S5).
5) If there is a packet input, the input packet is divided into predetermined fixed lengths (S56), and a header including a sequence number is added to the divided packets to form a short packet (S57). Then, short packets are allocated to each line at a distribution ratio calculated in advance (S58). Subsequently, the short packet is sent to the corresponding transmitting / receiving unit (S59).

For example, in many cases, communication is performed using a fixed-length frame unique to a wireless line. In such a line, a short packet generated by the multilink processing unit is inserted as data into a line-specific frame. However, depending on the length of the short packet, only a small part of the data space prepared in the frame is used. There is a case where communication is performed without satisfying the above conditions. This wastes the transmission capacity of the line unit. In order to reduce this waste, the multilink processing unit divides the packet into fixed lengths in which the length of the short packet obtained by dividing the packet matches the length of the data area of the frame used on the line. . Then, the short packets are distributed to the transceivers so that the ratio of the number of distributions of the generated short packets to each line is a distribution ratio according to the effective transmission speed information of each line obtained from the line monitoring unit. . As a result, waste of transmission capacity in the line section is reduced, and data transfer suitable for the effective transmission speed can be maintained. In addition, there is an advantage in that the size of the short packet is fixed and the packet is easily divided, and since all the short packets have the same length, the short packet distribution processing is simplified. In this method, if the number of short packets generated from one packet is small, the difference between the calculated target distribution ratio and the ratio of the number of short packets actually distributed to the calculated target distribution ratio may increase in each packet processing. is there. To avoid this, by controlling the distribution so that the distribution ratio of short packets approaches the target band distribution ratio over a plurality of packets, the effect of using the present invention can be enhanced.

Up to this point, an example has been described in which division control is performed on a packet basis. However, when a fixed-length short packet is used as shown in FIG. The invention is effective. For example, as described above, the distribution ratio is adjusted based on the number of fixed-length short packets allocated per unit time, and a packet obtained by dividing a packet into a fixed length is mechanically inserted into each short packet. If the last part of the packet remains short, the packet is divided by the corresponding length from the beginning of the next packet, and is also inserted into the data area of the fixed-length short packet. This allows
Since the data area of short packets is always filled, the efficiency of data transfer is further improved, and the control of the distribution ratio of short packets to each line and the division of packets and generation of short packets can be configured independently. Is further simplified. This example is shown in FIG. In the figure, packets 1 to 3 (81-1 to 3) are divided into short packets 1
To (86-1-5). In the header of the short packet, a length area 85 indicating the boundary of the packet is provided. If both the flag, the first bit and the last bit in the short packet are 1, and the length area is 100, the first 100 bytes of the data area are the last part of the previous packet and the remaining bytes are the next byte. This is the first part of the packet. If either or both of the first bit and the last bit are 0, the length area is ignored.

FIG. 6 shows another example of the dividing process. First, it is determined whether or not there is an input packet (S60), and if there is an input, the number M of links for which new retransmission has occurred among N links is checked (S61). In response, the packet is divided into NM (S62). Then, a short packet is configured by adding a header including a sequence number to the divided packets (S63). N- for short packets
The data is sent to the M transmitting / receiving units (S64).

In this process, the line monitor monitors the occurrence of retransmission on the line. Then, when retransmission occurs once on a certain line, the packet division unit divides the packet and distributes the packet to the line so that the assignment of short packets to the line is stopped once. Therefore, when dividing a packet, the packet dividing unit first obtains information from the line monitoring unit as to whether a new retransmission has occurred on each line after the previous division / distribution. Then, the packet is divided into the number of lines on which no retransmission has occurred. Now, assuming that the number of lines is N and the number of lines in which retransmission occurs is M, the number of lines is divided into NM. The generated short packet is distributed to a line on which no retransmission has occurred. This method has an advantage that line monitoring is very easy because the effective transmission speed of each line is determined based on the number of retransmissions. Also, in combination with the method of dividing the packet into fixed-length short packets as in the previous example, the deviation of the distribution ratio from the target caused by the mismatch between the length of the retransmitted short packet and the length of the short packet that has not been allocated is determined. Can be kept low, and the overall packet transfer rate can be kept close to the overall effective transmission rate.

Next, a second embodiment showing the effect of the present invention will be described.

FIG. 8 shows a system for performing data communication via a plurality of wireless lines. User communication device 10
Reference numeral 0 denotes a communication device having a multilink processing unit 103 according to the present invention, which is used by connecting a terminal device to the data signal terminal 101, for example. Alternatively, the communication module may take the form of a communication module incorporated in a small portable computer. The communication control unit 102 controls the overall communication by a control signal transmitted / received via a data signal terminal, notifies the status thereof, and performs processing such as format conversion on the transmitted / received data signal. The communication device has three wireless communication units 104-1 to 104-3, each of which is connected to a multilink processing unit. The wireless communication unit includes antennas 107-1 to 107-3, parts 106-1 to 3-3 for transmitting and receiving wireless signals, and protocol units 105-1 to 3-5 for controlling communication in a wireless communication section. The protocol section converts and reverse-converts the data to be transmitted into a packet format suitable for the wireless line, detects errors or loss of the transmitted packet, and performs retransmission reliably. Performs recovery and stop control processing.
For example, if the wireless system is a PHS (Personal H
PIAF in the case of an and-phoneSystem)
S (PHS Internet Access For
um Standard) protocol plays this role. Then, the data is transmitted to the relay communication device 120 via the plurality of wireless lines 108-1 to 108-3. The three wireless lines, line a, line b, and line c, may be provided by different wireless systems, or the same system may have different frequencies and different connection base stations. Lines a and b in FIG. 8 are wireless communication devices 109- on the network side.
1 and 2 have the aforementioned protocol unit. Data input / output to / from the protocol unit is transmitted / received to / from a relay communication device via a backbone network using a communication device not shown. Since the line c is provided by the system to which the relay communication device belongs, the line c is directly connected to the relay communication device via a communication unit (not shown) from the base station 110 that transmits and receives wireless signals. For this reason, the relay communication device has a protocol unit for processing a signal with the line c in the relay communication device. For signals on lines a and b,
For this purpose, transmission / reception units 125 and 126 are provided. And
A multilink processing unit 123 for managing communication via the lines a to c and a communication relay unit 122 for connecting to a server or another network via the data signal terminal 121
Having. Thereby, when the user accesses various communication services via the user communication device-relay communication device,
Between the user communication device and the relay communication device, a transmission capacity obtained by integrating the transmission speeds of the lines a to c can be used, and comfortable communication can be secured.

Now, it is assumed that communication to be performed is communication based on IP packets, and the basic protocol used in the multilink processing unit is a Point-to-Point Protocol having a multilink protocol function.
(PPP). PPP and its Multilink Protocol (MP) mechanism are InternetEn
Gineering Task Force (IET
F) issued in RFC1661 and RFC1990.

The IP packet generated on the user side is passed to the multilink processing unit 103 via the communication control unit 102. In the multilink processing unit 103, a connection based on PPP is established on each line in advance with the multilink processing unit of the relay communication device that is opposed to the multilink processing unit, and settings are collectively handled as a multilink. . Therefore, the multilink processing unit divides the IP packet and generates a short packet to which a necessary header and footer are added. FIG. 9 shows a frame of this short packet. This frame transferred from the upper left to the lower right has first and last one-byte length flag regions 131 and 136 for detecting a frame break. In addition, there are a header 132 defined by the PPP and a frame check sequence (FCS) 135 for error detection, and a header 133 defined by the MP. In the above division, the method described in the above embodiment is used so that short packets are distributed to each line according to the effective transmission speed of each line obtained from the information of the line monitoring unit. Multilink processing unit 10
The short packets generated in step 3 are passed to the wireless communication units 104-1 to 104-3 of the corresponding lines. Wireless communication unit 104
In -1 to -3, short packets are further subjected to processing relating to a protocol for a wireless communication section, and transmitted from the transmission / reception units 106-1 to 3-6 in a frame configuration unique to the wireless section. The received wireless section frame is subjected to protocol processing, and the included short packet is taken out.
The data is passed to the 20 multilink processing units 123. If a data error or data loss occurs in the wireless section, retransmission processing is automatically performed between the wireless section protocols, and the reliability of the wireless link is independently assured by the wireless section protocol. Is done. Further, after the radio section frame is received by a base station near the user as shown by the line c in the figure, the relay communication device 12
0, and is terminated by the opposite protocol unit in the relay communication device, or a wireless section protocol is provided in a remote device or system as shown by lines a and b in the figure. Then, only the obtained short packet is further transferred to the relay communication device 1 via various backbone networks.
20. When the short packet arrives at the multilink processing unit 123 of the relay communication device 120 through these steps, the multilink processing unit 123 restores the original IP packet based on the sequence number in the short packet by the packet restoration unit. The IP packet is further sent to the outside via the communication relay unit. In this case, the same procedure as in the above embodiment is applied to the restoration procedure and the processing of the delayed / lost short packets. Therefore, even in the embodiment of this configuration, by using the multilink processing unit having the line monitoring unit to perform packet distribution according to the effective transmission speed of each line, communication using multiple lines with low delay and efficiency is efficiently performed. Can be realized.

From the relay communication device 120 to the user communication device 1
Communication in the 00 direction is performed in the same manner. However, when the device of the wireless line portion is remote such as the lines a and b, information on the status of the line portion is directly obtained from the wireless communication units 104-1 to 104-3 as in the case of the user communication device 100. May not be possible. At this time, the line monitoring unit can perform a desired operation by separately communicating information about the line status between the remote wireless communication device and the relay communication device 120. Alternatively, if flow control is performed by transferring short packets between a remote wireless communication device and a relay communication device, if the transfer of short packets is delayed on the wireless communication device side and the buffer becomes full, short packets are transferred. Since the transfer stop request of the packet is notified to the relay communication device, the line monitoring unit monitors the line based on this information and can estimate the effective transmission speed. Furthermore, when there is no such mechanism and it is difficult to obtain information from a system that manages a wireless line, line monitoring can be performed by exchanging information between the opposing multilink processing units. For example, there is a method of periodically acquiring information on the user communication device side, and in this example, a method of using an Echo-Request function of PPP. In the latter case, when an Echo-Request packet is sent out from the multilink processing unit of the relay communication device side 120 onto the line to be monitored, the Echo-R packet is immediately sent to the multilink processing unit 123 of the opposite user communication device.
Send back an eply packet. The multilink processing unit on the side of the relay communication device measures the time required for the round trip of the packet. By performing this operation periodically and monitoring the communication time of the target line for packet round trip, the status of the line can be known, and the effective transmission speed can be estimated. By using the above method, a line monitoring method for obtaining the effect of the present invention can be realized even when the multilink processing unit is not closely connected to the line communication device. Communication can be realized.

Furthermore, when the user communication device 100 is a mobile device and connects to a fixed network from the device to enjoy services, the functions of the relay communication device 120 can be placed in various places on the network. When the function of the relay communication device 120 is provided in a mobility assistance server of a wireless network supporting mobile terminals, communication from the moving user to the server using the multilink according to the present invention realizes highly efficient communication. at the same time,
Further, data can be directly exchanged between the server and a service server that actually provides a service requested by the user. As such a server function for mobility assistance, there is a foreign agent (FA) in a system called Mobile IP by IETF in which a mobile communication device is dynamically accommodated in a network. Referring to the example of FIG. 8, the moving user communication device 100 is connected to the line c.
The FA performs a user authentication and a gateway function for connecting the user to the Internet when connected to the wireless network having the FA. And this F
A is provided with the multi-link communication function of the present invention, so that the user can also set the connection from the user communication device to the FA via another wireless line a or b according to the required transmission speed, and Efficient large-capacity communication can be realized between FAs. Then, it can be connected to various service servers via the FA. In this case, since data flows through the most efficient route from the FA to the service server, comprehensively comfortable communication is realized from the service server to the user.

If there is no mobility assistance server, or even if the multilink efficiency according to the present invention is not widespread, a relay gateway device that a user always accesses when moving is prepared inside a fixed network, In some cases, the gateway device has the function of the relay communication device. By incorporating the function of improving the efficiency of multilink according to the present invention into this gateway device, if the user moves to any of the various service servers via the gateway regardless of where he moves, those communications can enjoy the effects of the present invention. . In this case, the function of increasing the efficiency of multilink according to the present invention is incorporated in the home agent (HA) in the Mobile IP system.

Alternatively, when the service server or the router for relaying communication has a function that allows a user to specify / program a protocol to be used therein, the function for improving the efficiency of multilink of the present invention can be used by using the function. The effect of the present invention can be enjoyed by performing communication by incorporating it in a service server or a router.

When the moving user performs communication using the multilink according to the present invention, there is also an effect that the line can be efficiently switched. FIG. 10 shows an example. When accessing the service on the Internet 208 from the user device 201 provided in the moving car 200,
The communication device 204 for the mobile phone system and the communication device 203 for the intelligent transportation system (ITS) possessed by the user device can be utilized. Initially, communication was performed using only the ITS communication device. However, when the transmission capacity was expanded by using the communication device for the mobile phone system due to lack of bandwidth, the additional communication was performed from the user device via the ITS via the mobile phone system. It is set between the mobile assistant server 206 provided in the network. At this time, if there are other lines that can be used when deciding a new line to be set, the communication quality or effective line capacity of each line is detected, and based on that, the decision is made. Even in communication using multilink, which is often affected by a bad line, communication quality after setting a new line can be kept high. Since the mobile phone system and the ITS are connected by a public communication network, a dedicated line, the Internet, or the like, the mobile phone system control station 210 transmits the connection 211
Through this, the additional communication can be set.
Each of the user device and the movement assistance server has multilink processing units 202 and 207 having the functions of the present invention. Then, a multilink according to the present invention is set between the movement assistance server and the user device. As a result, the user device can increase the capacity between the car and the ITS movement assistance server, which had the most limited line capacity when accessing the service server via the Internet. Even while using the ITS, there is a handover when moving between cells or a temporary line disconnection behind a large truck, and the mobile phone system side also experiences a service interruption due to a tunnel. In response to these changes in the line quality, the multilink processing unit according to the present invention constantly monitors the line quality and dynamically responds to the changes in the situation and quality based on the obtained information.
Maintains optimal communication with low delay and high line utilization efficiency. In the above example, the multi-link using the ITS and the mobile phone system has been described. However, the direct access from the vehicle within the ITS by road-to-vehicle communication and the connection to the ITS backbone network via another vehicle using the vehicle-to-vehicle communication are provided. A similar effect can be obtained by any combination of mobile communication systems such as multilink with indirect access, a mobile phone system and a satellite communication system.

In the case of the IP communication, the routing function at the network layer level also has a function of dynamically selecting a link to be used for data transfer according to the state of the line. To make consistent routing decisions throughout the network, so that dynamic changes occur relatively slowly. For this reason, it is not possible to follow minute changes in line conditions. Therefore, the method of improving the line utilization efficiency with low delay by adjusting the distribution of data transfer between links using the multilink according to the present invention by end users includes mobile communication in which the line condition changes in units of tens of seconds. If it is more effective.

In the case of the ITS, since the communication cells are arranged along the road, a handover that periodically moves between cells occurs as the vehicle advances. That is, the effective transmission speed of the communication line changes periodically. By allocating the data transfer in consideration of this cycle in the multilink processing unit, it is possible to keep the effective line use efficiency higher. In particular, the line for accessing the mobility assist server via the preceding and following vehicles using the inter-vehicle communication is also incorporated into the multilink, so that the direct I
The line connected to the TS and the line via another vehicle are less likely to be affected by handover and obstruction at the same time. This is the case when the user moves on a route and uses a mobile communication system deployed along the route.

As described above, the present invention provides a means for setting a plurality of communication lines, bundling them and always using them effectively even in mobile communication where the line conditions are liable to change.

[0040]

As described above, according to the present invention, a line monitoring function is provided, and based on the monitoring result,
By providing a multi-link communication device equipped with a function to distribute communication according to the effective transmission speed of each line, especially in an environment where the line conditions such as mobile use of wireless communication lines dynamically change drastically However, as a whole, there is an effect that communication with low delay and efficient multilink can be realized. Furthermore, there is also an effect of realizing line switching that effectively follows frequent changes in line quality when used in a mobile body.

Further, by estimating the effective transmission rate of the communication line based on the occurrence of retransmission on the communication line, the above effect can be realized with a simple calculation.

[Brief description of the drawings]

FIG. 1 is an example of a communication system using a multilink communication device.

FIG. 2 is a configuration example of a multilink processing unit according to the present invention.

FIG. 3 is an example of a frame configuration of a short packet.

FIG. 4 is a first example of a flow of a packet division process.

FIG. 5 is a second example of the flow of the packet division processing.

FIG. 6 is a third example of the flow of the packet division processing.

FIG. 7 is a configuration example of a fixed-length short packet.

FIG. 8 is a second example of a communication system using a multilink communication device.

FIG. 9 is a multilink packet frame.

FIG. 10 is an example of communication using an in-vehicle multilink communication device.

[Explanation of symbols]

 10, 11 user communication device 13, 21 communication control unit 14, 20 multilink processing unit 15-1 to 3, 19-1 to 3 transmission / reception unit 16, 22 handset 17, 23 data signal terminal 31 counter 32 line monitoring unit 33 Packet division unit 34 Packet restoration unit 35 Buffer 41 Short packet frame 42 Sequence unit 45 Data unit 81-1 to 3. . . Input packet frame 82 Sequence number area 85 Length area 86-1-5. . . Output short packet frame 104-1 to 3 wireless communication unit 105-1 to 3 wireless section protocol processing unit 106-1 to 3 wireless transmission and reception unit 110 base station 112 backbone network 120 relay communication device 122 communication relay unit 132 PPP header 133 MP Header 200 Car 201 User equipment 202, 207 Multilink processing unit 205 ITS base station and antenna 206 ITS mobility support server 208 Internet 209 Cellular phone system base station and antenna 210 Cellular phone system control station

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K030 GA02 GA03 JL01 JL07 LA01 LB06 LB13 LC09 LE06 LE14 MB02 MB05 MB09 5K034 AA01 CC01 EE07 FF04 HH04 HH06 HH63 JJ13 KK25 LL07 MM03 MM11 9A001 CC05 CC07 DD10 LL05

Claims (4)

[Claims] 1. A system in which a plurality of logical communication lines including a communication line whose effective transmission speed fluctuates is used at the same time to make one virtual communication line appear between the opposing devices, thereby displaying a higher virtual communication line. In a communication device having a multilink communication function capable of exchanging various data with the function without distinguishing each of the plurality of lines, a function of monitoring an effective transmission speed of each line and an effective function of each line A multi-link communication device having a function of sorting data according to a typical transmission speed. 2. A method in which a plurality of logical communication lines including a communication line whose effective transmission speed fluctuates between a pair of opposing devices to simultaneously appear as one virtual communication line, thereby forming a higher-ranking communication line. In a communication device having a function of multi-link communication capable of exchanging various data between functions without distinguishing each of the plurality of lines, the communication line includes a wireless communication line, and the monitoring function is The multilink communication device according to claim 1, further comprising a function of monitoring an effective transmission speed of a wireless communication line. 3. The line includes a line having a function of retransmitting a communication error, and the monitoring function is based on the number of retransmissions occurring in the line for the line to be retransmitted. 3. The multilink communication apparatus according to claim 1, wherein the effective transmission rate is calculated. 4. A higher-level function by simultaneously using a plurality of logical communication lines including a communication line whose effective transmission speed fluctuates between the opposing devices to appear as one virtual communication line. A communication device having a multilink communication function capable of exchanging various data between the plurality of lines without distinguishing each of the plurality of lines, wherein the communication lines include a wireless communication line, and one of the wireless communication lines A system to be provided is deployed along a route on which a moving object using the communication device moves, a function of monitoring an effective transmission speed of each line, and a wireless communication line deployed along the route. A multi-link communication apparatus having a function of distributing data in accordance with a cycle of a communication status change occurring in the above and an effective transmission speed of each line.