JP2003158773A - Message transfer method, message relay device, relay wireless base station and system using these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communications system using a line provided with a plurality of different communication schemes, which realizes error correction capable of immediate judgement without suppressing the limited transmission performance of a wireless line. SOLUTION: If a communication line between a wireless terminal and a relay node has an error correction function specific to itself, the communication through this line uses transfer procedures having no re-transmission function, and procedures in which error correction is performed by re-transmission is used for the communication between a relay node using a router network having no error correction function in a communication line itself and a main wireless base station. By this method, the re-transmission of discarded data to be transmitted from a wireless terminal can be suppressed to the minimum, and unnecessary overhead on communication can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a wireless communication system, particularly in a dual link communication system for transmitting and receiving control information, user information and the like between a wireless terminal and a wireless base station using a plurality of wireless lines. The present invention relates to a communication method, a communication device, and a communication system.

[0002]

2. Description of the Related Art Portable communication devices have come into widespread use due to advances in communication technologies including wireless technologies and wireless devices. Mainly used for mobile phones and PHS (Personal Handyphon)
e System) is widely used. Both have their own strengths and weaknesses. In order to utilize these effectively, the user should select the most suitable method depending on the situation in which the device is used. These advantages and disadvantages are created by the wireless communication system because the concept of using the system is originally different.

Due to recent advances in information systems, the amount of information exchanged via networks has also increased rapidly. In particular, distribution of contents such as music and video has been desired, and a higher speed communication system has been required. As a market need, there is an increasing demand to use these contents on the above-mentioned wireless device. For high-speed wireless communication, for example ARIB-T70 Hi
The SWANa (High Speed Wireless Access Network type a) method has been established as a standard.

However, the wireless device based on the HiSWANa system requires a large amount of power because of its characteristics. The characteristics mentioned here mean that the frequency band used is a frequency with large attenuation of 5 GHz, and that power must be transmitted in a wide band. This is a big obstacle when mounted on a small wireless device such as a mobile phone.

For this reason, a hybrid MMAC (Multi-media Mobile Access Communicatio
n) The system was developed. In the hybrid MMAC, multiple wireless lines are used properly in consideration of the concept of each system usage. In the hybrid MMAC, only the HiSWANa receiver is installed in the wireless terminal, and the HiSWANa wireless transmission is performed from the wireless base station that has relatively available power to the wireless terminal. On the other hand, the PHS wireless equipment is used for the transmission from the wireless terminal that has no available power to the wireless base station. In other words, as viewed from the wireless terminal, different communication methods are used for the uplink and the downlink. Normally, the uplink data exchanged by the PHS is used to control the radio base station of HiSWANa system.

FIG. 8 shows a hybrid MMAC system constructed according to the prior art. In the HiSWANa system standard, the association between the wireless base station and the wireless terminal that is the communication partner needs to be completed. After that, each time there is a communication request from the wireless terminal, a control message is exchanged between the wireless terminal and the HiSWANa wireless base station to establish a connection.

In the hybrid MMAC, the wireless terminal 801 is Hi
Since there is no SWANa transmission function, there is no means to establish the above connection. The control message for doing this is the wireless link 80 established with the PHS base station 802.
3 is transmitted. PH that received the control message
The S base station 802 sends the information to the communication network 805.
To the access router 804 connected to. The access router 804 sends the passed control message to
Hi connected by the same communication network 805
It is transmitted to the SWANa wireless base station 806. Through this series of operations, a control message is transmitted from the wireless terminal 801 to the HiSWANa wireless base station 806, and the HiSWANa wireless line 8 is transmitted.
07 is established.

The format of the control message transmitted at this time is shown in FIG. As shown in FIG. 9, the control message is stored as user data in the IP datagram. The wireless terminal 801 to the HiSWANa wireless base station 80
For transmission to 6, UDP (Us
er Datagram Protocol) is used.

In UDP, even if excessive traffic is input to a router on the path and a buffer flow occurs and the data is discarded, the discarded data is not transmitted again. Still, using UDP is
This is because communication processing can be simplified. Regarding the error correction of the transmission data, if there is another method of compensating for the flowing data, overlapping use of the protocol having the error correction function may rather complicate the process.

In this system using UDP, the HiSWANa base station 806 cannot receive the data that it should originally receive, for example, when the transmitted data is discarded somewhere along the route. Therefore, the HiSWANa base station 806
It cannot respond to the wireless terminal 801 that sent it. The wireless terminal 801 again transmits the same control message because there is no response. By performing the processing as described above, the wireless terminal 801 and the HiSWANa base station 8
Communication performed between 06 is guaranteed.

This state is shown in FIG. First, the control message transmitted by the wireless terminal 801 is the access router 80.
It reaches 4 (1001). The access router 804 sends the control message to the HiSWANa wireless base station 806.
At this time, it is delivered via some routers (not shown) existing in the communication network 805 (1
002, 1003). If the control message is discarded by any of the routers (not shown) in the communication network 805 (1004), the HiSWANa wireless base station 806 should not respond to the discarded control message. When the response is not obtained within the predetermined time, the wireless terminal 801 determines that the control message has not been normally delivered, and tries to retransmit the message (1005, 1006, 1007).

However, the above-described series of error correction processing has some problems to be improved.

One is that if the control message is discarded for some reason, the communication data for performing this error correction flows through all the existing lines. This puts a considerable pressure on the band of the wireless line which originally has a limited transfer capability, which is interposed on the way. Further, since the conventional method is premised on the correction processing by retransmitting the data itself, the error correction function provided in the communication method of the communication line on the way is out of consideration. If it is originally left to the error correction of the communication line, there may be a situation where the obvious retransmission process is not necessary. Looking at how to perform error correction in the entire configured communication system, it is often the case that unnecessary communication processing is performed.

Further, in order for the wireless terminal to judge whether or not the control message has arrived at the HiSWANa wireless base station, it has to wait a predetermined time for a response from the other party. The response time must also take into consideration the internal processing time spent for radio control of the HiSWANa radio base station, which requires a relatively long time. In order to obtain a prompt arrival response, there is a demand for a method capable of detecting that a vehicle has not yet arrived without waiting the waiting time.

[0015]

In communication using a transport protocol without guaranteed arrival, even if a part of a communication line passing through has an error correction function, the function is positively used. By doing so, the error correction is not optimal as a whole. As mentioned above, this causes an adverse effect such as unnecessary data communication and the inability to promptly confirm arrival. INDUSTRIAL APPLICABILITY The present invention relates to a communication method using a line having a plurality of different communication methods, which does not put pressure on the limited transmission capacity of a wireless line and realizes error correction that can be quickly determined, a communication system, and a use thereof An object of the present invention is to provide a communication device.

[0016]

According to the present invention, a router network for transferring an IP datagram, first and second radio base stations connected to the router network, and the first and second radio base stations are connected. In a message transfer method by a wireless terminal that transmits and receives an IP datagram using a wireless channel generated between the wireless base station and the wireless base station, the control of the wireless channel between the first wireless base station and the wireless terminal The IP datagram transmitted by the wireless terminal including the message is
A message relay unit connected to the router network for relaying from the second wireless base station to the first wireless base station, and for transmitting a message from the wireless terminal to the message relay unit, communication data is transmitted. A transport layer transfer procedure having no arrival guarantee function is used, while a message is transmitted from the message relay means to the first radio base station using a transport layer transfer procedure having a reach guarantee function. A message transfer method is provided that is characterized by performing.

A router network for transferring the IP datagram and a first network connected to the router network.
And an IP datagram including a message for controlling a communication line between a second wireless base station, a wireless terminal that communicates with the first wireless base station, and the first wireless base station. Relaying from a radio base station to the first radio base station,
A message relay unit connected to the router network, the message relay unit guaranteeing arrival of an IP datagram including a message for controlling a communication line between the wireless terminal and the first wireless base station. There is provided a communication system characterized by converting a transport layer transfer procedure having no function into a transport layer transfer procedure having an arrival guarantee function.

For example, when passing through a communication line having an error correction function from the wireless terminal to the message relay device, a transfer procedure without an error correction function by retransmission is used,
The communication line between the message relay device and the wireless base station has a transfer procedure for error correction by re-sending.

In addition, by providing a communication device used in the above communication method, it is possible to minimize the retransmission of the data transmitted from the wireless terminal which is not normally delivered for some reason by this method. , It is possible to reduce unnecessary overhead in communication.

[0020]

FIG. 1 shows an embodiment of a communication system of the present invention. The communication system includes a wireless terminal 101 including a plurality of wireless communication means, and a first terminal having a communication line with the wireless terminal 101.
Wireless base station 106 and second wireless base station 102. The control message of the wireless line generated between the wireless terminal 101 and the first wireless base station 106 is the relay node 1
It is sent from the second radio base station 102 to the first radio base station 106 via 04. The server device 108 is a server-side application with which the above-described wireless terminal 101 exchanges when executing an application on the network, or an application server that provides a database system.

In this system example, the first radio base station 10
6 is equipped with a HiSWANa type wireless device, and the second wireless base station 102 is, for example, a PHS wireless base station. The HiSWANa method is a communication method standardized as ARIB-T70. Hereinafter, the first wireless base station adopting the HiSWANa system and the second wireless base station adopting the PHS system will be described as an example. When implementing the present invention, the wireless communication system adopted by the second wireless base station may be a system using an existing mobile phone, or a third generation mobile communication system such as W-CDMA or cdma2000. Even if it is such, the same effect can be obtained.

Further, in the present embodiment, one first radio base station and one second radio base station are shown, respectively, but these should be understood as showing transmission and reception of one control message. For example, consider a case where the wireless terminal 101 is moving and has deviated from the service area of the first wireless base station or the second wireless base station currently communicating. At this time, it is usual to continue communication with the first or second wireless base station in charge of the service area to which the wireless terminal 101 newly belongs, which is different from the one that has been communicating until now. is there. In addition to the case described above, the wireless terminal 101 may communicate with a plurality of first wireless base stations while each having a communication line. Even if the partner radio base station is changed as described above, or even if it is a communication using multiple lines, in the relationship between each radio base station and the radio terminal, it is simply regarded as one control message transmission. Because you can.

The relay node 104 relays the control message transmitted from the wireless terminal 101 to the first wireless base station, and at that time, converts the IP datagram included in the control message. In this embodiment, a TCP segment having an error correction function is mainly used from a UDP segment having no error correction function.
Convert to segment.

In the HiSWANa type wireless line, whenever there is a communication request from a wireless terminal that has completed association with the wireless base station, a control message is exchanged between these wireless terminals to set up the wireless line connection.

However, in the hybrid MMAC system described above, the wireless terminal 101 does not have a HiSWANa type wireless transmitter. Therefore, a control message for establishing a HiSWANa wireless link, which is a downlink from the first wireless base station 106 to the wireless terminal 101, is performed via the second wireless base station 102.

The second radio base station 102 is the radio terminal 10
The control message is acquired via the wireless line 103 established between the first wireless base station 102 and the second wireless base station 102. The second radio base station 102 that has acquired the control message notifies the relay node 104 of this via an ISDN line, for example.
The relay node 104 receives the control message, for example, the destination IP of the IP datagram including the control message.
By checking the address, it is determined whether the address is sent to the own node.

When it is determined that this is a control message addressed to the own node and is a control message for controlling the first radio base station in accordance with a rule negotiated in advance, the first radio base station transmitted in the control message is transmitted. From the identifier showing the station,
Determine the destination IP address. The IP datagram converted from the UDP segment of the control message to the TCP segment has the first IP address obtained earlier
To the wireless base station 106.

An IP datagram that does not meet the above conditions is determined to be communication data with an application such as the Web or telnet, and is transferred to the destination IP address of the IP datagram or is discarded. .

At this time, it is usual that a plurality of devices such as a switching router having a function of relaying communication exist between the relay node 104 and the first radio base station 106. Of course, the configuration example that can be the embodiment of the present invention is not limited to the hybrid MMAC, and one wireless base station to another wireless base station by using a wireless network and a router network of a wireless terminal and a plurality of wireless base stations. A system for sending a control message for setting and releasing a wireless line to the like can similarly enjoy the effects of the present invention.

First, let us consider a case where the control message addressed to the first radio base station 106 is delivered from the radio terminal 101 to the relay node 104. During this time, PHS wireless line and ISD
Using PHS data communication line consisting of N lines, PIAFS (PH
The data link layer protocol frame specified by S Internet Access Forum Standard) is sent.

On the other hand, the relay node 104 and the first radio base station 106 are connected by a reliable network such as Ethernet (registered trademark). Ethernet is usually a LAN (Local Area N) connected by routers that control communication paths and relay packets that pass through them.
etwork).

The LAN is rarely constructed for only one system, and in reality, packets used in various other applications flow at the same time. Depending on the conditions, packet collision (collision) may frequently occur on the Ethernet, or the intervening router may not be able to process the packets flowing there, and may discard some packets. Loss of such a packet means loss of the IP datagram containing the packet.

In the present invention, the wireless terminal 101 and the relay node 1
04, and the other relay node 104 and the first radio base station 1
It is possible to effectively utilize the difference in the characteristics regarding the error correction of the IP datagram due to the difference in the characteristics of the respective transmission paths and the protocol between the No. 06. UDP (User Datagram Protocol) is used between the wireless terminal 101 and the first relay node 104, and TCP (Transmission Control Protocol) is used between the relay node 104 and the first wireless base station 106.

FIG. 2 shows packet formats before and after the relay node 104. In FIG. 2A, the control message is stored in the UDP payload part, and the UDP / IP packet is included in the PPP frame and transferred. In Fig. 2 (b), the control message is stored in the TCP payload part, and the TCP / I
It indicates that the P packet is included in the Ethernet frame and transferred.

Next, the state of the control message flowing through the communication path will be described. 3 shows the wireless terminal 101 to the relay node 1
The transfer sequence of the control message up to 04 is shown. The control message divided into PPP frames is
The second radio base station 1 divided into a plurality of PIAFS frames
It is delivered to 02 (301).

When all the PIAFS frames divided from one PPP frame arrive at the relay node 104, the IP datagram in the PIAFS frame is extracted and the first wireless base station 10
It is sent to 6 (302). When an error occurs in these PIAFS frames due to deterioration of the quality of the PHS wireless line (303), a PIAFS prescribed retransmission request (304) is issued, and retransmission is performed based on this (30).
5). As a result, all PPP frames including the control message transmitted from the wireless terminal 101 are transferred to the relay node 104 without error according to the PIAFS agreement.

FIG. 4 shows a control message transfer sequence from the relay node 104 to the first radio base station 106. The relay node 104 receives the UDP /
Extract control message from IP packet TCP / IP
The extracted control message is put in a packet and transmitted (402). In the router on the path leading to the first wireless base station, the received Ethernet frame (402)
Is routed to the appropriate network (403). When the TCP / IP packet reaches the first wireless base station, which is the destination, the confirmation ACK packet is sent to the relay node 10.
4 (404, 405).

At this time, consider a case where the data is discarded by the router between the relay node 104 and the first radio base station 106. When some data is discarded due to buffer overflow due to excessive traffic input to the router (406), the relay node 104 that processes TCP that is the transport layer protocol and the first node A TCP / IP packet including a control message is retransmitted with the wireless base station (407). Therefore, error correction between the relay node 104 and the first radio base station 106 is performed between them, and as a result, a correct control message can be delivered with a minimum communication process.

In the conventional control protocol for connecting and disconnecting the wireless link of the HiSWANa system using UDP, the other party that sends the control message, that is, HiSW
The ANa radio base station must wait for the time it thinks necessary to respond to the processing of the control message before it can be determined that there is no response from the other party, that is, the control message has not arrived.

On the other hand, in TCP, which is a transport layer protocol, whether or not the control message has reached the other party simply waits for the estimated delay time for the control message and its acknowledgment to be transferred through the network. You can judge.

Comparing the former processing waiting time with the latter estimated delay time, the latter can overwhelmingly set a shorter time. In addition, the relay node 104 and the first radio base station 106
As long as the error correction of the TCP / IP packet including the control message is performed only during the period, it is not necessary to retransmit the same control message from the wireless terminal 101. Therefore, it is not necessary to use the band of the wireless line 103 for error correction, and the limited wireless line capacity can be used exclusively for data communication.

The communication efficiency can be improved by applying the error correction method suitable for the communication system of the line used in this way.

FIG. 5 shows an internal configuration example of the relay node 104 in the embodiment using the hybrid MMAC as an example. The relay node 104 accommodates the ISDN line 501 and processes the PIAFS protocol TAP (Terminal Adapter for PIAFS) 5
02, and process PPP frames carried by PIAFS
It has a PPP processing unit 503 at the input stage. A TCP / IP protocol processing unit 504 that controls IP routing, UDP packet processing, TCP retransmission, and the like, and an Ethernet processing unit 505 that is connected to the Ethernet 506 and that transmits and receives Ethernet frames.

As described above, the control message transmitted from the wireless terminal 101 is error-corrected by PIAFS,
An error-free control message is delivered to the TAP 502. T
AP502 constructs a PPP frame from PIAFS frame
It is sent to the P processing unit 503. PPP processing unit 503 that received it
Passes the IP datagram obtained by removing the PPP header from the received PPP frame to the next TCP / IP protocol processing unit 504.

The TCP / IP protocol processing unit 504 receives the received IP
The datagram addressed to the first wireless base station 106 is selected, and the selected data is subjected to the following processing.

If the selected one includes the control message as shown in FIG. 2A, it is guided to the TCP / IP protocol processing unit 504 via the route 508 shown in FIG. The selected IP datagram is stripped of the UDP header and only the control message is extracted. After that, the TCP / IP protocol processing unit 504 stores the retrieved control message in a TCP frame. At this time, a TCP header including a sequence number is added to the control message. Further, the TCP / IP protocol processing unit 504 is provided with a buffer for accumulating TCP segments in order to be able to perform retransmission processing. When a data error is detected between the relay node 104 and the second radio base station 106, retransmission is performed based on the information accumulated here, and error correction is performed between the two.

The TCP / IP datagram generated through the above processing is then delivered to the Ethernet processing unit 505 and output as an Ethernet frame from the Ethernet 506 onto the router network 105.

On the other hand, the TCP / IP protocol processing unit 504
The second wireless base station 1 for the received IP datagram
The control message of No. 06 is bypassed to the Ethernet processing unit 505 via the route 507 without performing the above processing. Then, an Ethernet header is added and the data is sent from the Ethernet 506 to the router network 105.

In this way, the relay node 104 performs the protocol conversion from UDP to TCP for the IP datagram including the control message for the first radio base station 106,
It has the function of simply routing other IP datagrams.

The details of the TCP / IP protocol processing unit 504 will be described with reference to FIGS. 6 and 7. FIG. 6 shows a block diagram of the processing unit. The TCP / IP protocol processing unit 504 has an IP processing unit 601 for performing IP datagram routing processing, a UDP processing unit 602 for performing UDP segment protocol processing, and a TCP processing unit 604 for performing TCP segment protocol processing. There is.
In addition to the part that processes these segments, there is a wireless control message processing unit 603 that performs control message transfer processing. Further, the radio control message processing unit 60
3 there is a base station ID table 605 for determining to which radio base station the received control message should be transferred. The table describes the relationship between the base station ID (identifier) of the first wireless base station of the communication system corresponding to the embodiment of the present invention and the IP address of each of them on the router network. Is.

Next, the operation of each of the above blocks will be described with reference to FIG. The control message for controlling the radio base station is I in the PPP frame as shown in FIG.
It is stored with P header and UDP header. Wireless terminal 1
When 01 transmits the control message, the relay node 104 is designated as the IP address that is the destination of the IP datagram. The base station ID (identifier) of the first radio base station, which is the destination of the control message, is described in the UDP payload.

First, the TCP / IP protocol processing unit 504 sets the PPP
An IP datagram including the control message is received from the processing unit 503 (step 701). Next, the destination address of the received IP datagram is checked, and it is the relay node 1
It is determined whether the address is for 04 (step 702).
If it is not addressed to the relay node 104, step 713
It is bypassed by branching to. At this time, the IP processing unit 601 uses the routing function to transfer the IP datagram to the PPP processing unit 503 or the Ethernet processing unit 50.
5 and is transferred to the target IP address of the IP datagram.

On the other hand, if the IP datagram is addressed to the relay node 104, it is next determined whether the datagram in the payload is a UDP segment (step 70).
3). If this is not a UDP segment, that is, if it is other than a UDP segment such as a TCP segment or an ICMP packet, the subsequent processing changes depending on whether it is a TCP segment (step 708).

If it is a TCP segment, TCP processing unit 6
TCP processing is performed by 04 (step 709), and complete TCP payload data is processed by the application program 606 (step 711). Examples of applications here include Web servers and Telne.
Examples include t servers. Information from these applications is subjected to processing relating to TCP and UDP protocols in step 712, and the target IP is passed through the IP processing unit 601.
Forwarded to the address.

When the TCP segment other than ICMP is included,
Processing corresponding to each protocol (step 71
After performing 0), the IP processing unit 60 as well as the TCP segment.
It is transferred to the target IP address via 1.

The last remaining UDP addressed to the relay node 104
In the case of segment, it becomes as follows. UDP processing unit 60
The protocol processing corresponding to the UDP segment is performed by 2 (step 704), and the UDP payload is extracted. Next, in step 705, it is determined whether the UDP payload information is a control message addressed to the first radio base station (step 705).

As a method of this determination, for example, a method of allocating a specific UDP port number for the control message in the communication system of the embodiment and checking whether it is addressed to the UDP port number can be considered. Of course, it can also be judged by the method of inspecting a specific pattern string in the UDP payload. If it is determined that the message is not a control message by these methods, it is determined to be UDP segment data for an application, and is sent to the processing by the application 606 as in the case of the TCP segment (step 71).
1).

When the UDP payload of the received IP datagram is a control message, the base station ID (identifier) contained therein is first extracted. Then, the IP address corresponding to the base station ID (identifier) is searched based on the base station ID table 603 described above (step 706). Next, the control message sent as a UDP segment is reconstructed into a TCP segment by the TCP processing unit 604 (step 70).
7) Based on the IP address corresponding to the previously obtained base station ID, it is transferred to the first wireless base station 106 that is the destination via the IP processing unit 601.

Although omitted in the flow chart of FIG. 7, TC
The P processing unit 604 performs the segment configuration processing as described above and also performs error correction according to the TCP protocol when data disappears between the relay node 104 and the first wireless base station 106. It also has a function.
Further, when establishing the communication between the both, the TCP processing unit 604 also performs connection processing such as TCP connection setting.
Is in charge.

[0060]

By using the error correction function of the communication line in the communication via the line having a plurality of different communication methods by using the transport protocol with no guarantee of arrival, the transmission data itself It realizes error correction that can quickly confirm the arrival without reducing the transmission capacity of the wireless line due to the retransmission processing.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a communication system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a format of a packet including a control message according to an embodiment of the present invention.

FIG. 3 is a diagram showing a transfer sequence of a packet including a control message on a PHS line according to an embodiment of the present invention.

FIG. 4 is a diagram showing a transfer sequence of a packet including a control message according to the embodiment of the present invention.

FIG. 5 is a diagram showing a block configuration of a relay node according to an embodiment of the present invention.

FIG. 6 is a diagram showing a block configuration of a TCP / IP protocol processing unit according to an embodiment of the present invention.

FIG. 7 is a processing flowchart of a TCP / IP protocol processing unit according to the embodiment of the present invention.

FIG. 8 is a diagram showing an overall configuration of a conventional hybrid MMAC system.

FIG. 9 is a diagram showing a format of a packet including a control message transferred in a conventional hybrid MMAC system.

FIG. 10 is a diagram showing a transfer sequence of a packet including a control message in the conventional hybrid MMAC system.

[Explanation of symbols]

101 wireless terminal 102 second radio base station 104 Relay node 105 router network 106 first radio base station 504 TCP / IP protocol processing unit

Claims (5)

[Claims] 1. A router network for transferring an IP datagram, first and second radio base stations connected to the router network, and the first and second radio base stations. In a message transfer method by a wireless terminal that transmits and receives IP datagrams using a wireless channel, the IP transmitted by the wireless terminal including a control message of the wireless channel between the first wireless base station and the wireless terminal A message relay means connected to the router network for relaying a datagram from the second radio base station to the first radio base station, and for transmitting a message from the radio terminal to the message relay means. Uses a transport layer transfer procedure without a communication data arrival guarantee function, while a message from the message relay means to the first wireless base station is transmitted. The di-transmitted using a transport layer transfer procedure with the arrival assurance function,
A message transfer method characterized by performing communication. 2. An IP including a control message for the wireless line
2. The message transfer according to claim 1, wherein the message relaying unit converts a datagram from a transport layer transfer procedure having no arrival guarantee function to a transport layer transfer procedure having the arrival guarantee function. Method. 3. A message relay device for transferring a message addressed to the first wireless base station received from the second wireless base station to a first wireless base station connected to a router network for transferring an IP datagram. In the received wireless terminal, the second wireless base station addressed to the first wireless base station, and the wireless terminal transmitted by the wireless terminal transmitting and receiving IP datagrams to and from the first and second wireless base stations, For an IP datagram including a message for controlling a communication line with the first wireless base station, a transport layer transfer procedure without a reach guarantee function is converted to a transport layer transfer procedure with a reach guarantee function. A message relay device comprising transfer procedure conversion means. 4. A relay connected to the router network, which transfers a message addressed to the wireless base station to a main wireless base station connected to the router network that transfers the IP datagram, via the router network. A radio base station, wherein the main radio base station, the relay radio base station and the IP
Receiving an IP datagram including a message transmitted by a wireless terminal transmitting and receiving a datagram and controlling a wireless line between the wireless terminal and the main wireless base station,
A relay radio base station, wherein the received IP datagram is converted from a transport layer transfer procedure having no reach guarantee function into a transport layer transfer procedure having a reach guarantee function. 5. A router network for transferring an IP datagram, the first and second wireless base stations connected to the router network, and the first and second wireless base stations received from the second wireless base station. The wireless terminal that transmits and receives the IP datagram to and from the wireless base station of
The IP datagram addressed to the first wireless base station including the message for controlling the communication line with the wireless base station of A communication system, comprising: a message relay means for converting into a layer transfer procedure and transferring an IP datagram including the converted message to the first radio base station.