JP2005080163A - Radio communication link method and wireless module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the continuation of communication even if a communication status is not excellent in radio communication. <P>SOLUTION: A radio terminal STA1 utilizes two channels of a band that does not interfere with a radio terminal STA2, to establish two wireless links. The radio terminal STA1 first utilizes an ordinary channel Ach of the two channels to transmit data. When the wireless link is cut for the ordinary channel, the radio terminal STA1 switches to a reserve channel Rch and utilizes the reserve channel Rch to transmit data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a link method when performing wireless communication.

  There are wireless communication using IEEE802.11 method, Bluetooth, and the like. In order to transmit and receive data using these wireless communications, it is first necessary to establish a wireless link between wireless terminals. In order to establish a wireless link, it is necessary to negotiate while exchanging various packet data according to a procedure defined by the protocol.

  On the other hand, in network communication as well as wireless communication, a link once established may be disconnected due to a change in communication state. In particular, in the case of wireless communication, compared to wired communication in which an electrical signal is transmitted over a wired cable, the wireless link is more likely to be subject to environmental fluctuations and is more likely to be disconnected. Possible causes of disconnection of the wireless link include, for example, temporary interference of radio waves in addition to the ISM (Industry Science Medical) band and movement of the terminal itself. When the process of establishing the radio link is performed while exchanging the packet data every time the radio link is disconnected, there is a problem that it takes a long time for reconnection. The application cannot continue communication during the reconnection process. Also, the wireless module consumes extra power to reconnect the wireless link.

  As one measure for solving such a problem, in Patent Document 1 below, a logical link is maintained even when a physical link is disconnected. Even in a state where the communication level is lowered, the disconnection of the logical link is delayed so that the link is not easily disconnected.

JP 2002-152309 A

  According to Patent Document 1, for example, when a physical link is recovered, there is no need to establish a new logical link, so that there is an advantage that the communication state can be recovered early. However, as long as the physical link does not recover, there is a problem that the communication state cannot be recovered. Further, when a specific band is disturbed, it is difficult to recover the communication state.

  In addition, a method of preparing a plurality of wireless communication modules and duplexing the wireless communication path can be considered, but there is a problem that the cost is increased. In addition, there is a problem that the terminal size increases in a wireless terminal that is required to be downsized.

  In view of the above problems, an object of the present invention is to improve the continuity of a communication state in wireless communication.

  In order to solve the above problem, the invention according to claim 1 establishes a plurality of radio links with a communication partner terminal using channels of a plurality of bands that do not interfere with each other, and establishes the radio links. A step of transmitting / receiving data to / from a communication partner terminal using one channel among a plurality of channels, and, when the radio link is disconnected for the one channel, another channel establishing a radio link And a step of transmitting / receiving data to / from a communication partner terminal using

  The invention according to claim 2 is a step of establishing a plurality of radio links with a communication partner terminal using channels of a plurality of bands that do not interfere with each other, and one of the plurality of channels establishing the radio links. A step of transmitting / receiving data to / from a communication partner terminal using a channel, and when a communication level of the one channel falls below a predetermined threshold, another channel that establishes a wireless link is used. And a step of transmitting / receiving data to / from a communication partner terminal.

  According to a third aspect of the present invention, in the link method in the wireless communication according to the first or second aspect, the data transmission / reception is performed with the communication partner terminal using the other channel, The step of monitoring the communication state of one channel and, when the one channel becomes communicable, establishes a wireless link again for the one channel and switches to the one channel to transmit / receive data And a process.

  According to a fourth aspect of the present invention, in the link method in the wireless communication according to the first or second aspect, the data transmission / reception is performed with the communication partner terminal using the other channel, A step of monitoring a communication state of one channel, and a step of establishing a radio link for the one channel again and preparing the one channel as a standby channel when the one channel becomes communicable And.

  The invention according to claim 5 is the step of establishing a radio link with a communication partner terminal using one channel and transmitting / receiving data, and the communication level for the one channel is below a predetermined threshold. A new wireless link is established with a communication partner terminal using another channel in a band that does not interfere with the one channel, and the other channel is prepared as a standby channel. It is characterized by providing.

  A sixth aspect of the present invention relates to a wireless module, and executes the link method in the wireless communication according to any one of the first to fifth aspects.

  According to the first to sixth aspects of the invention, since wireless communication is performed using a plurality of wireless links, the continuity of communication can be improved.

  According to the second aspect of the present invention, since the channel is switched when the communication level falls below a predetermined threshold, it is possible to continue communication prior to the disconnection of the link.

  According to the fifth aspect of the present invention, the standby channel is prepared when the communication level is lower than the predetermined threshold value. Therefore, when the communication state is good, it is not necessary to secure an unnecessary channel and the efficiency is improved. Good.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a connection state of a radio link that is a feature of the present invention. The wireless terminal STA1 and the wireless terminal STA2 have established two wireless links using two channels. Of the two channels, the service channel Ach is used for data transmission and reception in the initial state, and the other standby channel Rch is used when the service channel Ach is disconnected. The regular channel Ach and the standby channel Rch are channels set in bands that do not interfere with each other.

  FIG. 2 is a functional block diagram of the wireless terminal STA1 or the wireless terminal STA2. In the following description, when a feature common to the wireless terminal STA1 and the wireless terminal STA2 is described, it will be abbreviated as the wireless terminal STAn. In the present embodiment, the wireless terminal STAn performs wireless communication based on the IEEE 802.11 scheme. The form of the wireless LAN may be an ad hoc mode in which each wireless terminal STAn directly transmits and receives data, or an infrastructure mode in which data is transmitted and received via a base station.

  The wireless terminal STAn includes a CPU 1, a memory 2, a wireless module 4, and an antenna 8. The CPU 1 is an arithmetic processing unit that performs overall control of the wireless terminal STAn, and the memory 2 stores an application program 3 that is a program for controlling the operation of the wireless terminal STAn.

  The wireless module 4 includes a host interface (I / F) unit 5, a MAC control unit 6, and a wireless communication unit 7. The host I / F unit 5 is an interface unit that transmits and receives data between the wireless module 4 and the CPU 1. The MAC control unit 6 has a function of executing a specific processing procedure of the present invention in addition to a function of executing an access control procedure in the MAC layer based on the IEEE 802.11 standard. The wireless communication unit 7 receives a baseband signal from the BBP module that executes baseband processing and the BBP module, outputs the data to a predetermined band of radio waves, and outputs the data from the radio waves received by the antenna 8. An RF module having a function of extracting and supplying a baseband signal to the BBP module is provided. The MAC control unit 6 includes a channel registration unit 61, a link monitoring unit 62, a channel control unit 63, a communication control unit 64, and a channel registration table 65. Each functional unit of the MAC control unit 6 will be described later.

{First embodiment}
Next, the radio link method according to the first embodiment will be described with reference to the flowchart of FIG. First, the MAC control unit 6 establishes a radio link for two channels in a band that does not interfere with each other (step S11). Specifically, the channel registration unit 61 registers frequency information of two channels selected as channels for establishing a radio link in the channel registration table 65. Then, the communication control unit 64 establishes a wireless link with the counterpart wireless terminal STAn for the two channels registered in the channel registration table 65.

  Next, data transmission / reception is performed using one of the two channels with which the radio link has been established as the regular channel Ach (step S12). Specifically, transmission data is generated when the application program 3 is executed on the CPU 1, and the transmission data is input to the wireless module 4 via the host I / F unit 5. At this time, channel control is performed. The unit 63 controls to transmit the transmission data using the regular channel Ach. Thereby, the radio terminal STAn can perform data communication with the counterpart radio terminal STAn using the regular channel Ach.

  While transmitting / receiving data using the regular channel Ach, the link monitoring unit 62 monitors the link state of the regular channel Ach (step S13). When the link of the regular channel Ach is disconnected (Yes in Step S13), the channel control unit 63 controls to transmit the transmission data using the standby channel Rch (Step S14).

  In this way, since wireless links are established for multiple channels and one wireless link is disconnected, data communication is performed using the other wireless link, so data communication processing can be continued. It is. That is, the standby channel Rch also has already negotiated with the counterpart wireless terminal STAn in step S11 to establish the wireless link, so the time for performing the link connection process when the link of the regular channel Ach is disconnected. Can be omitted. In particular, since multiple channels are set from a band that does not interfere with each other, even if communication is unstable for some bands, communication can be continued, improving reliability. To do.

  In practice, such switching from the regular channel Ach to the standby channel Rch is realized by the radio terminals STAn at both ends performing communication switching channels. Therefore, the interval from when communication on the regular channel Ach becomes impossible until the communication on the standby channel Rch is started is the same as the interval between one radio terminal STAn and the other radio terminal STAn after detecting the disconnection of the radio link. Is a time difference until the disconnection of the wireless link is detected. This time difference is a short time compared to the processing time for reconnecting the wireless link. Therefore, the communication interruption time by the application can be shortened compared to the case of reconnecting the wireless link.

  While performing transmission / reception of data using the standby channel Rch, the link monitoring unit 62 periodically transmits a beacon in the frequency band of the regular channel Ach, thereby monitoring the communication state of the regular channel Ach (step S15). . If the wireless link cannot be established for the regular channel Ach (No in step S15), data communication using the standby channel Rch is continued. On the other hand, when the radio link can be established for the service channel Ach (Yes in step S15), the radio link is established again for the service channel Ach. Then, the channel controller 63 controls to transmit / receive data using the regular channel Ach (step S16). Thus, when communication using the regular channel Ach becomes possible, switching from the standby channel Rch to the regular channel Ach is performed again to avoid interference with other communications in the standby channel Rch. it can.

  Note that when reestablishing a radio link for the regular channel Ach, it is possible to use the information of the radio link that has been established before, so that it is not necessary to perform the connection procedure specified in the protocol again. For example, it is not necessary to execute again the communication start procedure defined by IEEE802.11. Specifically, the wireless link re-establishment process referred to here is simply a process of rewriting the state of the regular channel Ach registered in the channel registration table to the connected state.

  A modification of the first embodiment will be described. As described above, the same is true until the link monitoring unit 62 monitors the communication state of the regular channel Ach while performing data communication using the standby channel Rch. Next, when the link monitoring unit 62 determines that a radio link using the regular channel Ach is possible, the communication control unit 64 establishes a radio link for the regular channel Ach again. Switching control to is not performed. That is, data communication using the standby channel Rch is continued even after the radio link of the regular channel Ach is restored. This is a state where the regular channel Ach is prepared as a standby channel. By adopting such a method, the switching process from the standby channel Rch to the regular channel Ach can be made unnecessary. After the regular channel Ach is prepared for standby, the same processing as in FIG. 3 may be performed in a state where the positions of the regular channel Ach and the standby channel Rch are reversed.

{Second Embodiment}
Next, a radio link method according to the second embodiment will be described with reference to the flowchart of FIG. Steps S21 and S22 in FIG. 4 are the same as Steps S11 and 12 in FIG. 3 (first embodiment), and thus description thereof is omitted.

  While transmitting and receiving data using the regular channel Ach, the link monitoring unit 62 measures the communication level of the regular channel Ach and monitors the communication state (step S23). The link monitoring unit 62 measures, for example, RSSI (Received Signal Strength Indicator) and RSQ (Received Signal Quality) as the communication level. Further, the link monitoring unit 62 sets a predetermined threshold for the communication level to be measured. The predetermined threshold is a value that defines a level serving as a reference for a communicable state.

  When the communication level for the regular channel Ach is below a predetermined threshold (Yes in step S23), the channel control unit 63 controls to transmit the transmission data using the standby channel Rch. Yes (step S24). As described above, since the radio link is established for a plurality of channels, and the communication level for one radio link falls below a predetermined threshold, data communication is performed using the other radio link. It is possible to continue processing. In particular, since multiple channels are set from a band that does not interfere with each other, even if communication is unstable for some bands, communication can be continued, improving reliability. To do. In addition, since the channel is switched when the communication level falls below a predetermined threshold before the radio link is completely disconnected, the continuity of communication can be further improved.

  In practice, such switching from the regular channel Ach to the standby channel Rch is realized by the radio terminals STAn at both ends performing communication switching channels. Therefore, the interval from when communication on the regular channel Ach becomes impossible until communication by the standby channel Rch starts, the channel from one radio terminal STAn to channel switch from the other radio terminal STAn is switched. It becomes time difference until. Therefore, it is preferable to preliminarily define a predetermined threshold value for determining that communication is impossible between wireless terminals that perform wireless communication.

  While transmitting and receiving data using the standby channel Rch, the link monitoring unit 62 monitors the communication state of the regular channel Ach (step S25). If the communication level for the regular channel Ach is still below the predetermined threshold and the wireless link cannot be established (No in step S25), data communication using the standby channel Rch is continued. On the other hand, when the communication level for the service channel Ach exceeds a predetermined threshold and the radio link can be established (Yes in step S25), the radio link is established again for the service channel Ach. Then, the channel controller 63 controls to transmit / receive data using the regular channel Ach (step S26). Thus, when communication using the regular channel Ach becomes possible, switching from the standby channel Rch to the regular channel Ach is performed again to avoid interference with other communications in the standby channel Rch. it can.

  Note that when reestablishing a radio link for the regular channel Ach, it is possible to use the information of the radio link that has been established before, so that it is not necessary to perform the connection procedure specified in the protocol again. For example, it is not necessary to execute again the communication start procedure defined by IEEE802.11. Specifically, the wireless link re-establishment process referred to here is simply a process of rewriting the state of the regular channel Ach registered in the channel registration table to the connected state.

  A modification of the second embodiment will be described. As described above, the same is true until the link monitoring unit 62 monitors the communication state of the regular channel Ach while performing data communication using the standby channel Rch. Next, when the link monitoring unit 62 determines that a radio link using the regular channel Ach is possible, the communication control unit 64 establishes a radio link for the regular channel Ach again. Switching control to is not performed. That is, data communication using the standby channel Rch is continued even after the radio link of the regular channel Ach is restored. This is a state where the regular channel Ach is prepared as a standby channel. By adopting such a method, the switching process from the standby channel Rch to the regular channel Ach can be made unnecessary. After the regular channel Ach is prepared for standby, the same processing as in FIG. 4 may be performed in a state where the positions of the regular channel Ach and the standby channel Rch are reversed.

{Third embodiment}
Next, a radio link method according to the third embodiment will be described with reference to the flowchart of FIG. First, the MAC control unit 6 establishes a radio link using a specific channel as the regular channel Ach (step S31). Specifically, the channel registration unit 61 registers the frequency information of the channel selected as the regular channel Ach in the channel registration table 65. Then, the communication control unit 64 establishes a wireless link with the counterpart wireless terminal STAn for the regular channel Ach registered in the channel registration table 65.

  Next, data is transmitted and received using the regular channel Ach with which the wireless link is established (step S32). Specifically, transmission data is generated by executing the application program 3 on the CPU 1, and the transmission data is input to the wireless module 4 via the host I / F unit 5. Then, the channel control unit 63 controls to transmit the transmission data using the regular channel Ach. Thereby, the radio terminal STAn can perform data communication with the counterpart radio terminal STAn using the regular channel Ach.

  While transmitting and receiving data using the regular channel Ach, the link monitoring unit 62 measures the communication level of the regular channel Ach and monitors the communication state (step S33). The link monitoring unit 62 measures, for example, RSSI (signal strength) and RSQ (signal quality) as the communication level. Further, the link monitoring unit 62 sets a predetermined threshold for the communication level to be measured. The predetermined threshold is a value that defines the standby preparation level. When the communication level reaches the standby preparation level, it is predicted that there is a possibility that the wireless link will be disconnected, and a standby channel is prepared.

  When the communication level for the service channel Ach is below a predetermined threshold (standby preparation level) (Yes in step S33), the channel registration unit 61 uses the standby channel Rch in a band that does not interfere with the service channel Ach. Make a reservation. Specifically, the channel registration unit 61 registers the frequency information of the channel selected as the standby channel Rch in the channel registration table 65. Then, the communication control unit 64 establishes a wireless link with the counterpart wireless terminal STAn for the standby channel Rch registered in the channel registration table 65 (step S34).

  In this way, the standby channel Rch is prepared while performing data communication using the regular channel Ach. This state is the same as step S12 in FIG. 3 (first embodiment) or the same state as step S22 in FIG. 4 (second embodiment). Therefore, after this, by performing the same processing as step S13 and subsequent steps in FIG. 3 or the processing similar to step S23 and subsequent steps in FIG. 4, communication can be continued while switching between the regular channel Ach and the standby channel Rch. It becomes possible.

  As described above, by preparing a standby channel before the radio link is disconnected, it is possible to improve the continuity of communication. Further, when the communication state of the regular channel Ach is good, it is efficient because it is not necessary to prepare the standby channel Rch.

It is a figure which shows the state which has established the radio link using a some channel. It is a functional block diagram of the radio | wireless terminal concerning this Embodiment. It is a flowchart which shows the link method concerning 1st Embodiment. It is a flowchart which shows the link method concerning 2nd Embodiment. It is a flowchart which shows the link method concerning 3rd Embodiment.

Explanation of symbols

6 MAC control unit 7 Wireless communication unit Ach Service channel Rch Standby channel STAn (STA1, STA2) Wireless terminal

Claims (6)

Establishing a plurality of radio links with a communication partner terminal using channels of a plurality of bands that do not interfere with each other;
A step of transmitting and receiving data to and from a communication partner terminal using one of a plurality of channels that have established a wireless link;
When a radio link is disconnected for the one channel, a step of transmitting / receiving data to / from a communication partner terminal using another channel that has established a radio link;
A link method in wireless communication, comprising: Establishing a plurality of radio links with a communication partner terminal using channels of a plurality of bands that do not interfere with each other;
A step of transmitting and receiving data to and from a communication partner terminal using one of a plurality of channels that have established a wireless link;
When the communication level for the one channel falls below a predetermined threshold, transmitting and receiving data to and from a communication partner terminal using another channel that establishes a radio link;
A link method in wireless communication, comprising: The link method in wireless communication according to claim 1 or 2, further comprising:
Monitoring the communication state of the one channel while transmitting / receiving data to / from a communication partner terminal using the other channel;
A step of establishing a radio link for the one channel again when the one channel becomes communicable and switching to the one channel to transmit and receive data;
A link method in wireless communication, comprising: The link method in wireless communication according to claim 1 or 2, further comprising:
Monitoring the communication state of the one channel while transmitting / receiving data to / from a communication partner terminal using the other channel;
Establishing a radio link for the one channel again when the one channel becomes communicable, and preparing the one channel as a standby channel; and
A link method in wireless communication, comprising: Establishing a wireless link with a communication partner terminal using one channel and transmitting / receiving data;
When the communication level for the one channel falls below a predetermined threshold, a new radio link is established with a communication partner terminal using another channel in a band that does not interfere with the one channel; Preparing the other channel as a standby channel;
A link method in wireless communication, comprising: A wireless module that executes the link method in wireless communication according to claim 1.

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