TWI418180B - Wireless broadband transmission apparatuses and flow control method for the apparatuses - Google Patents

Description

Wireless broadband transmission device and flow control method suitable for the same

The present invention relates to a wireless transmission device, and more particularly to a wireless broadband transmission device.

With the evolution of the digital age, the number of Internet users has increased, and services on various application networks have mushroomed. As a result, the amount of traffic required for the overall network system has increased dramatically. For network operators, a large amount of network construction needs to be built to meet the needs of network users.

Among them, the line connecting the network operator's main network to the client is called the Last Mile. At present, the most commonly used network connection method is Digital Subscriber Line (DSL), coaxial cable (Cable) or fiber optic (Fiber Optics). These wired network connections provide high speed and stable network connectivity. However, in some cases, such as geographical restrictions or deployment time and funding considerations, it is not suitable to use the above network connection. In these examples, using a wireless network as the last or a backbone network connection has become a viable option. Methods. The microwave communication system is currently one of the most commonly used wireless communication technologies for the last connection.

In order to increase the transmission speed of this microwave communication system as a last-minute or wireless connection to the backbone network, the microwave communication system needs to use a channel with a large bandwidth and use a very high frequency (10 GHz or higher frequency). Carrier signal to transmit data. Both the transmit and receive ends require a high speed digital signal processor to process the signal and use complex channel coding to overcome various non-ideal effects in wireless transmission. High-speed microwave communication systems requiring specific application hardware components are therefore quite costly, so high-speed microwave communication systems requiring specific application hardware components are not widely used in practical use.

In view of the above problems, the present invention provides a wireless broadband transmission apparatus and a flow control method applicable to the apparatus for use as a broadband wireless communication network to solve the problems and disadvantages of the prior art.

The wireless broadband transmission device provided by the invention comprises a Combine and Spilt Module, at least one wireless network group, a connection control module and at least one Ethernet Module. . The packet cutting and reassembling module comprises a transmitting packet buffer and a receiving packet register. Each wireless network group includes a plurality of wireless network modules, the plurality of wireless network modules being coupled to the packet cutting and recombining module, wherein each wireless network group is used with a remote wireless network Road group establishment A chain. The connection control module is coupled to the packet cutting and recombining module, the connection control module is coupled to the packet cutting and recombining module, and the connection control module and the at least one remote connection control module perform a handshake process to detect the transmission. a link between the device and the at least one remote transmission device, the connection control module respectively sending a control packet to the at least one remote connection control module according to the condition of each link, the control packet is used to establish a chain Junction and flow control for each link. The Ethernet module is coupled to the packet cutting reassembly module.

In an embodiment of the present invention, the method for establishing a link by the connection control module includes connecting a control module, continuously transmitting a link connection (Link Connect) packet, until the connection control module receives a link preparation (Link Ready) After the packet is received, the connection control module receives a Link Ready packet and sets the state of the link to Ready for Transmission; the data packet is transmitted via the established link.

According to an embodiment of the present invention, the connection control module performs flow control by the following steps: first, the connection control module transmits a Link Halt packet or receives a link suspension packet; and the connection control module sets the link. Connected State; the link remains connected, but the link pauses to transmit data packets. If the link for the connection state is to retransmit the data packet, repeat the steps described in the previous paragraph.

According to an embodiment of the present invention, if the link in the connected state receives a Link Disconnect packet or transmits a Link Disconnect packet, the link is interrupted, and the link is set to be unconnected. status (Disconnected State). If the link that is not connected is to retransmit the data packet, repeat the steps described in the previous paragraph.

According to an embodiment of the present invention, the connection control module periodically transmits a Link Status packet and counts it. If the Link Status packet is not received within the time, the link is set to be lost ( Connection Lost) status. To link the lost state to this link, if you want to retransmit the data packet, repeat the steps described in the previous paragraph.

According to an embodiment of the invention, when a plurality of wireless network modules receive a plurality of data packets, a plurality of data packets are stored in the receiving packet buffer. The packet cutting and reworking module determines whether the data packet is missing or incorrect according to the number on the received data packet and the error verification code on the data packet. If the data packet is missing or incorrect, the connection control module sends a status chain packet to remotely resend the lost or incorrect data packet. Until the data packet is confirmed to be correct, the data packet is sent to the Ethernet module output.

According to another embodiment of the present invention, the present invention provides a data transmission method for a wireless broadband transmission apparatus, the steps comprising: (a) continuously transmitting a link connection packet until receiving a link connection packet; (b) After receiving a link ready packet, the set state is ready for transmission; (c) transmitting or receiving a plurality of data packets when the state is ready for transmission; (d) receiving a link when transmitting or receiving a plurality of data packets Suspend the packet or transmit a link to suspend the packet, temporarily stop transmitting the data packet, and set the state to the connected state. among them, In step (d), if the data packet is to be retransmitted, repeat the steps (a), (b) and (c) described in this paragraph.

In summary, the present invention provides a wireless broadband transmission apparatus using a plurality of wireless network modules and a flow control method applicable to the same. These multiple wireless network modules can efficiently transfer data through this flow control method. This wireless broadband transmission device can replace the microwave communication system as the last wireless broadband connection method of the backbone or backbone network.

The above description of the present invention and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention.

10‧‧‧Wireless Broadband Transmission

11‧‧‧Package cutting and reorganization module

112‧‧‧Transport packet register

114‧‧‧Receive packet register

12‧‧‧Wireless network group

122‧‧‧First wireless network module

124‧‧‧Second wireless network module

126‧‧‧ Third wireless network module

128‧‧‧fourth wireless network module

12a‧‧‧First wireless network group

12b‧‧‧Second wireless network group

13‧‧‧ links

13a‧‧‧First Link

13b‧‧‧Second link

14‧‧‧Connected control module

18‧‧‧Ethernet Module

182‧‧‧First Ethernet Module

184‧‧‧Second Ethernet Module

22‧‧‧Remote wireless network group

22a‧‧‧Remote first wireless network group

22b‧‧‧Remote second wireless network group

222‧‧‧First remote wireless network module

224‧‧‧Second remote wireless network module

226‧‧‧ Third Remote Wireless Network Module

228‧‧‧4th remote wireless network module

24‧‧‧Remote connection control module

282‧‧‧Remote First Ethernet Module

284‧‧‧Remote second Ethernet module

20‧‧‧Remote wireless broadband transmission device

20a‧‧‧First remote wireless broadband transmission device

20b‧‧‧Second remote wireless broadband transmission device

100‧‧‧Unconnected state

200‧‧‧Prepared for delivery status

300‧‧‧Connected status

400‧‧‧Connection lost status

1 is a block diagram showing a wireless broadband transmission device according to an embodiment of the present invention.

2 is a block diagram showing a wireless broadband transmission device and a remote wireless broadband transmission device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a wireless broadband transmission device and a remote wireless broadband transmission device according to another embodiment of the present invention.

4 is a block diagram showing a wireless broadband transmission device and a second remote wireless broadband transmission device according to another embodiment of the present invention.

Figure 5 is a state transition diagram of an embodiment of the present invention.

Figure 6 is a flow chart of an embodiment of the present invention.

The detailed features and advantages of the present invention are set forth in the Detailed Description of the Detailed Description of the <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> </ RTI> <RTIgt; The objects and advantages associated with the present invention can be readily understood by those skilled in the art. The following examples are intended to describe the present invention in further detail, but are not intended to limit the scope of the invention.

As shown in FIG. 1 , it is an embodiment of the wireless broadband transmission device proposed by the present invention. The wireless broadband transmission device 10 includes a packet cutting and recombining module 11 , a wireless network group 12 , and a connection control. Module 14 and at least one Ethernet module 18. The packet cutting and reassembling module 11 includes a transport packet buffer 112 and a receiving packet register 114. The buffers are used for temporarily storing data packets, and the storage capacity of the register can be set according to usage requirements. The connection control module 14 is coupled to the packet cutting reassembly module 11.

The wireless network group 12 includes a first wireless network module 122, a second wireless network module 124, a third wireless network module 126, and a fourth wireless network module 128. The first wireless network module 122. The second wireless network module 124, the third wireless network module 126, and the fourth wireless network module 128 use a communication protocol of IEEE802.11a/b/g/n or use IEEE802.16d communication. Agreement, or other communication protocol that is not mentioned but has similar or identical communication. The communication protocol mentioned here is only the description of the embodiment, and is generally known in the art. It will be appreciated by those skilled in the art that other similar or identical transmission protocols can be applied to the apparatus or method of the present invention via routine operation. These multiple wireless network modules can support a Wireless Distribution System (WDS) or a protocol that establishes a wireless connection between two wireless network modules.

Referring to FIG. 2, the wireless network group 12 establishes a link 13 with a remote wireless network group 22. The first wireless network module 122, the second wireless network module 124, the third wireless network module 126, and the fourth wireless network module 128 and the remote wireless network group in the wireless network group 12 The first remote wireless network module 222, the second remote wireless network module 224, the third remote wireless network module 226, and the fourth remote wireless network module 228 in the group 22 use the same. Communication agreement. Different wireless network modules can use different channels or use directional antennas to establish sub-links in different directions. The link 13 is a collection of these sub-links. Those skilled in the art will recognize that the number of wireless networks referred to herein is for illustrative purposes only. Therefore, an appropriate number of wireless network modules can be selected depending on the actual network deployment situation.

In this embodiment, a plurality of data packets are transmitted to the packet cutting and reassembling module 11 via the Ethernet module 18. The plurality of data packets are stored in the transport packet register 112, and the packet cut reassembly module 11 sequentially numbers the plurality of data packets.

The connection control module 14 continuously transmits a link connection (Link Connect) packet, and the link connection packet is transmitted to the remote connection control module 24 via the link 13. The remote connection control module 24 receives the link connection packet After that, a Link Ready packet is sent back to the connection control module 14. The connection control module 14 receives a link preparation packet and sets the state of the link to Ready for Transmission, representing the link 13 to be established. The data packet is transmitted via this link 13. In order to reduce the cost of building a wireless network, the link 13 can operate in an Unlicensed Band. However, in order to obtain better communication quality, the link 13 can also operate in the licensed band (Licensed Band).

Because the link 13 uses wireless communication technology as the connection mode of its physical layer, the communication quality of wireless communication is often subject to environmental interference and changes. Therefore, the transmission rate of each sub-link on the link 13 is not a fixed rate. When the connection control module 14 detects that a sub-link transmission rate is lower than a reference value, the connection control module 14 sends a Link Halt packet to the remote connection control module 24 to suspend the connection. The data packet on the sub-link is transmitted. The connection control module 14 and the remote connection control module 24 set the sub-link to a connected state (Connected State), and the sub-link is continuously connected, but the packet is not transmitted. Therefore, a sub-link with a faster transfer rate can transmit more data packets, and a link with a slower transfer rate will transmit fewer data packets. The connection control module 14 can effectively utilize each of the sub-links so that the links 13 of the sub-links can achieve an optimized transmission rate. The connection control module 14 continuously detects the sub-link. When the transmission speed of the sub-link is higher than a reference value, the connection control module 14 can repeat the steps described in the above paragraph to re-use the sub-link to transmit data. Packet.

If there is no data packet in the transport packet buffer 112 that needs to be transmitted, the connection control module 14 transmits a Link Disconnect packet to the remote connection control module 24. At this time, the link 13 is interrupted, and the connection control module 14 and the remote connection control module 24 set the link 13 to a Disconnected State. If there is a data packet in the transport packet buffer 112 that needs to be transmitted again, the connection control module 14 can repeat the steps described in the previous paragraph, and the link 13 can continue to be used to transmit data.

In addition, if the link 13 suspends transmitting the data packet, the link 13 needs to be interrupted, and the connection control module 14 transmits a Link Disconnect packet to the remote connection control module 24. At this point the link 13 will be interrupted. The connection control module 14 can repeat the steps described in the previous paragraph to re-establish the link 13.

In the Ready for Transmission or Connected State, the connection control module 14 and the end connection control module 24 periodically transmit Link Status packets to each other. If the connection control module 14 does not receive the Link Status packet for a certain period of time, the link is set to the Connection Lost state, indicating that the link 13 is interrupted for unknown reasons. The information in the Link Status packet includes information such as the transmission speed of the link 13 and the number of the last successfully transmitted data packet.

Since the wireless broadband transmission device 10 is a two-way transmission device, the wireless broadband transmission device 10 also has the function of receiving. First wireless network After the circuit module 122, the second wireless network module 124, the third wireless network module 126, and the fourth wireless network module 128 receive the plurality of data packets, the plurality of data packets are stored in the receiving packet buffer. 114. The packet cutting and reassembling module 11 determines whether the data packet is missing or incorrect according to the number on the received data packet and the error verification code on the data packet. If the data packet is missing or incorrect, the connection control module 14 sends a control packet to the remote connection control module 24 to resend the lost or erroneous data packet until the data packet is confirmed to be correct. In this embodiment, this confirms that the correct data packet is sent via the Ethernet module 18.

Please refer to FIG. 3, which is another embodiment of the present invention. The wireless broadband transmission device 10 further includes a first wireless network group 12a and a second wireless network group 12b. The remote wireless broadband transmission device 20 also includes a remote first wireless network group 22a and a remote second wireless network group 22b. The first wireless network group 12a of the wireless broadband transmission device 10 includes a first wireless network module 122 and a second wireless network module 124, and the second wireless network group 12b includes a third wireless network module 126. And a fourth wireless network module 128. The remote first wireless network group 22a of the remote wireless broadband transmission device 20 includes a first remote wireless network module 222 and a second remote wireless network module 224, and a remote second wireless network group 22b includes a third remote wireless network module 226 and a fourth remote wireless network module 228. A first link 13a can be established between the first wireless network group 12a of the wireless broadband transmission device 10 and the remote first wireless network group 22a of the remote wireless broadband transmission device 20, and the wireless broadband transmission device 10 A second link 13b can be established between the second wireless network group 12b and the remote second wireless network group 22b of the remote wireless broadband transmission device 20. The wireless broadband transmission device 10 also includes a first Ethernet module 182 and a second Ethernet module 184. The data packet transmitted by the first Ethernet module 182 to the wireless broadband transmission device 10 is transmitted to the remote wireless broadband transmission device 20 via the first link 13a, and is configured by the remote first Ethernet module 282. Send it out. The data packet transmitted by the second Ethernet module 184 to the wireless broadband transmission device 10 is transmitted to the wireless broadband transmission device 20 via the second link 13b, and is sent by the remote second Ethernet module 284.

Please refer to FIG. 4, which is another embodiment of the present invention. The wireless broadband transmission device 10 further includes a first wireless network group 12a and a second wireless network group 12b. The first wireless network group 12a includes a first wireless network module 122 and a second wireless network module 124. The second wireless network group 12b includes a third wireless network module 126 and a fourth wireless network. Module 128. The first wireless network group 12a is used to establish the first link 13a, and the second wireless network group 12b is used to establish the second link 13b. The first link 13a and the second link 13b can independently transmit or receive data packets, respectively. In this embodiment, the plurality of data packets can be transmitted by the first remote wireless broadband transmission device 20a to the wireless broadband transmission device 10 via the first link 13a, and the wireless broadband transmission device 10 further encapsulates the plurality of data packets. The two links 13b are transmitted to the second remote wireless broadband transmission device 20b. At this time, the wireless broadband transmission device 10 can be regarded as a relay transmission device. The wireless broadband transmission device 10 can also be partially The data packet is sent via the Ethernet module 18. Another embodiment of the present embodiment is the input of the data packet Ethernet module 18, and confirms that the correct data packet is sent to the first wireless network module 122 and the second wireless network in the first wireless network group 12a. The road module 124 is transmitted to the first remote wireless broadband transmission device 20a via the first link 13a. Confirming that the correct data packet can also be sent to the third wireless network module 126 and the fourth wireless network module 128 in the second wireless network group 12b to the second remote wireless broadband via the second link 13b. Transmission device 20b. At this time, the wireless broadband transmission device 10 can be regarded as a point-to-multipoint transmission device. In order to use the plurality of wireless broadband transmission devices 10, a broadband network system architecture can be constructed.

In an embodiment of the invention, the error verification code uses a Cycle Redundancy Check (CRC). The transport packet buffer 112 and the receive packet register 114 are first in first out (FIFO) registers. The connection control module 14 can encrypt or decrypt each data packet, and the encryption and decryption methods can be Wireless Encryption Protocol (WEP), Advanced Encryption Standard (AES), temporary key. Temporal Key Integrity Protocol (TKIP) or other methods.

The invention further proposes a flow control method suitable for a wireless broadband transmission device. The method defines four states, an unconnected state 100, a ready to transmit state 200, a connected state 300, and a connected lost state 400. Please refer to "figure 5", which is a state transition diagram for this embodiment. Unconnected state 100 can be switched to the ready to transfer state 200. The ready transfer state 200 can be converted to the unconnected state 100, the connected state 300, or the connected lost state 400. The connection state 300 can be converted to an unconnected state 100, a ready to transmit state 200, or a connected lost state 400. The connection lost state 400 can be converted to the ready to transmit state 200.

"Picture 6" is a flow chart for establishing link and flow control. First, a link connection packet is sent (S110), and it is judged whether or not a link preparation packet is received. If the link preparation packet is received, the setting state is the ready transmission state 200 (S120). If the link preparation packet is not received, the transmission of a link connection packet is continued (S110). Next, the setting state is set to the ready transmission state 200 (S120). Transmitting or receiving a data packet (S130). The receiving link pauses the packet or transmits a link suspension packet, and the set state is the connected state 300 (S140).

In the step S140, if the data packet is to be retransmitted, the steps of S110 and S120 are repeated.

In the step S130, if the link interruption packet is received or transmitted, the set state is the unconnected state 100. At this time, if the data packet is to be retransmitted, the steps of S110 and S120 are repeated.

In the step S140, if the link interruption packet is received or transmitted, the set state is the unconnected state 100. At this time, if the data packet is to be retransmitted, the steps of S110 and S120 are repeated.

At step S130, the link status packet is transmitted at intervals and the calculation time is started, if it is not received within a certain period of time To the link status packet, the set state is the connection lost state 400. At this time, if the data packet is to be retransmitted, the steps of S110 and S120 are repeated.

At step S140, the link status packet is transmitted at intervals and the calculation time is started. If the link status packet is not received within a certain period of time, the set status is the connection lost status 400. At this time, if the data packet is to be retransmitted, the steps of S110 and S120 are repeated.

In summary, the present invention provides a wireless broadband transmission apparatus using a plurality of wireless network modules and a flow control method applicable to the same. These multiple wireless network modules can efficiently transfer data through this flow control method. In an embodiment of the invention, if the wireless network modules are IEEE 802.11n communication protocols. When these wireless network modules operate in a 20MHz bandwidth mode, the maximum transmission rate of a single network module can reach 300Mbps. Because the wireless broadband transmission device uses four wireless network modules, the wireless broadband transmission device has a high transmission rate of 1200 Mbps. At the same time, the cost of erecting this wireless broadband transmission device is much lower than the use of high-speed microwave communication systems that require hardware components for specific applications. Therefore, the wireless broadband transmission device can not only replace the high-speed microwave communication system as the last one or the wireless broadband connection mode of the backbone network, and the use of the wireless broadband transmission device can greatly reduce the cost of network system deployment.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. About the boundaries of the present invention Please refer to the attached patent application scope for the scope of protection.

10‧‧‧Wireless Broadband Transmission

11‧‧‧Package cutting and reorganization module

112‧‧‧Transport packet register

114‧‧‧Receive packet register

12‧‧‧Wireless network group

122‧‧‧First wireless network module

124‧‧‧Second wireless network module

126‧‧‧ Third wireless network module

128‧‧‧fourth wireless network module

14‧‧‧Connected control module

18‧‧‧Ethernet Module

Claims (32)

A wireless broadband transmission device includes: a packet cutting and recombining module, including a transmission packet temporary register and a receiving packet temporary register; at least one wireless network group, each of the wireless network groups including a plurality of wireless groups The network module, the plurality of wireless network modules are coupled to the packet cutting and recombining module, wherein each wireless network group is used to establish a link with a remote wireless network group; a module, the connection control module is coupled to the packet cutting and recombining module, and the connection control module performs an information exchange process with the at least one remote connection control module to detect the transmission device and the at least one remote transmission device The connection control module sends a control packet to the at least one remote connection control module according to the status of each link, and the control packet is used to establish the link and Each of the links performs flow control; and at least one Ethernet module, the Ethernet module is coupled to the packet cutting and recombining module; wherein the plurality of wireless network modules receive the plurality of data After the packet, the plurality of data packets are stored in the receiving packet buffer, and the packet cutting and recombining module determines whether the data packet is based on the received number on the data packet and the error verification code on the data packet. Lost or wrong, if the data packet is missing or incorrect, the connection The control module sends the control packet to remotely resend the lost or erroneous data packet until the data packet is confirmed to be correct. The transmission device of claim 1, wherein the plurality of data packets are transmitted to the packet cutting and reassembling module and then stored in the transport packet temporary register, so that the packet cutting and recombining module is adapted to the plurality of data packets. The sequence is numbered. The transmission device of claim 2, wherein the method for establishing the link by the connection control module comprises the following steps: (a) the connection control module continuously sends a link connection packet until the connection control module receives (b) the connection control module receives the link preparation packet and sets the state of the link to be ready for transmission; and (c) the data packet is transmitted via the established link. The transmission device of claim 3, wherein the method for controlling the flow control of the connection control module is as follows: (d) the connection control module transmits a link suspension packet or receives the link suspension packet; (e) the connection The control module sets the link to a connected state; and (f) the link remains connected, but the link suspends transmitting the data packet. The transmission device of claim 4, wherein the link in the connected state repeats the steps (a), (b), and (c) if the data packet is to be retransmitted. The transmission device of claim 3, wherein if the link in preparation for the transmission state receives a link interruption packet or transmits the link interruption packet, the link is interrupted, and the link is set to an unconnected state. The transmission device of claim 6, wherein the link in the unconnected state repeats the steps (a), (b), and (c) if the data packet is to be retransmitted. The transmission device of claim 4, wherein the link in the connected state interrupts the link if the link is interrupted or the link is interrupted, and the link is set to an unconnected state. The transmission device of claim 8, wherein the link in the unconnected state repeats the steps (a), (b), and (c) if the data packet is to be retransmitted. The transmission device of claim 3, wherein the connection control module periodically transmits the status link packet and counts the time, and if the status link packet is not received within the time, the link is set to be a connection lost state. The transmission device of claim 10, wherein the step (a), (b), and (c) are repeated if the link to which the connection is lost is to retransmit the data packet. The transmission device of claim 4, wherein the connection control module periodically transmits the status link packet and timed, and if the status link packet is not received within the time, the link is set to be a connection lost state. The transmission device of claim 12, wherein the connection is in a lost state If the link is to retransmit the data packet, repeat the steps (a), (b), and (c). The transmission device of claim 1, wherein the correct data packet is sent to the Ethernet module output. The transmission device of claim 1, wherein the correct data packet is sent to the plurality of wireless network module outputs in the wireless network group. The transmission device of claim 1, wherein the error verification code uses a cyclic redundancy check. The transmission device of claim 1, wherein the transport packet buffer and the receive packet register are first in first out registers. The transmission device of claim 1, wherein the connection control module can encrypt or decrypt each of the data packets. The transmission device of claim 1, wherein the plurality of wireless network modules are network modules using an IEEE 802.11a/b/g/n communication protocol. The transmission device of claim 1, wherein the plurality of wireless network modules are network modules that use an IEEE 802.16d communication protocol. The transmission device of claim 1, wherein the plurality of wireless network modules are network modules using a wireless distributed system. The transmission device of claim 1, wherein the plurality of Ethernet modules are network modules that use the IEEE802.3 protocol. A flow control method for a wireless broadband device, the steps comprising: (a) continuously transmitting a link connection packet until receiving the link connection seal (b) after receiving a link preparation packet, setting the state to prepare for transmission; (c) transmitting or receiving a plurality of data packets when the state is ready for transmission, wherein when transmitting the data packets, Each data packet number in the data packet, when receiving the data packet, determines whether the data packet is lost or incorrect according to the number on the data packet and the error check code on the data packet; d) When transmitting or receiving a plurality of the data packets, if receiving a link suspension packet or transmitting the link suspension packet, temporarily stopping transmitting the data packet, and setting the state to a connection state. The method of claim 23, wherein in the step (d), the step (a) (b) (c) is repeated if the data packet is to be retransmitted. The method of claim 23, wherein, in the step (c), when a link interrupt packet is received or the link interrupt packet is transmitted, a link is interrupted, and the set state is an unconnected state. The method of claim 25, wherein the step (a) (b) (c) is repeated if the data packet is to be retransmitted after the data packet transmission is suspended. The method of claim 23, wherein, in the step (d), if a link interrupt packet is received or a link interrupt packet is transmitted, a link is interrupted, and the set state is an unconnected state. The method of claim 27, wherein the step (a) (b) (c) is repeated if the link is to be re-established after the link is interrupted. The method of claim 23, wherein at the step (c), the status chain packet is transmitted at intervals and the calculation time is started, and if the status chain packet is not received within a certain period of time, the setting is as follows. The status is the connection lost state. The method of claim 29, wherein the step (a) (b) (c) is repeated if the link is to be re-established after a link is broken. The method of claim 23, wherein at the step (d), the status chain packet is transmitted at intervals and the calculation time is started, and if the status chain packet is not received within a certain period of time, the setting is as follows. The status is the connection lost state. The method of claim 31, wherein the step (a) (b) (c) is repeated if the link is to be re-established after a link is broken.