JP2009130859A - Wireless lan system, radio terminal, and communication method in wireless lan system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless LAN system and a radio terminal in which lowering of transmission efficiency can be suppressed, when transmitting data requiring a wide transmission band within the wireless LAN system, and to provide a communication method in the wireless LAN system. <P>SOLUTION: In a wireless LAN system which directly transmits data while establishing a connection on the same channel mutually between a plurality of radio terminals, a threshold is set to each radio terminal as the upper limit of a data transmission band that is occupied for connection in data transmission. When transmitting data, such as video data, having such a data transmission band as exceeding the threshold, data transmission is performed by establishing preferential connection that can occupy the data transmission band over the threshold, between corresponding radio terminals only for one connection simultaneously within the wireless LAN system and as long as the preferential connection is established, data transmission due to the other connection is temporarily interrupted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a wireless LAN system suitable for transmitting data requiring a wide transmission band, such as video data, in a wireless LAN system in which a plurality of wireless terminals directly transmit data while establishing connections with each other on the same channel. The present invention relates to a LAN system, a wireless terminal, and a communication method in the wireless LAN system.

  An example of a conventional wireless LAN system is illustrated in FIG. The conventional wireless LAN system shown in FIG. 4 includes four wireless terminals: a wireless terminal a41, a wireless terminal b42, a wireless terminal c43, and a wireless terminal d44. These four wireless terminals establish connections with each other on the same channel. In FIG. 4, for example, five connections indicated by arrows are established in the wireless LAN system, and data is directly transmitted between the wireless terminals. In this type of wireless LAN system, the data transmission band specific to the wireless LAN system is determined by various conditions such as the frequency and modulation format of the wireless signal used. In general, an intended wireless LAN system is constructed by selecting various conditions so that this unique data transmission band can secure a sufficient value for the transmission band of transmission data to be handled.

  Conventionally, such wireless LAN systems mainly handle so-called data traffic such as messages and files. However, with the recent progress and spread of multimedia technology, multimedia data traffic is As with the system, it has become desirable to handle it uniformly in the conventional wireless LAN system. Examples of multimedia data include streaming data such as audio data, moving image data, and video data. These streaming data require a wider transmission band than those of conventional data systems, and in connection with the connection between wireless terminals for transmission, data of good quality especially in terms of few delays and omissions during transmission. Although transmission is required, a sufficient connection is not always ensured. For this reason, a technique capable of coping with the problem of securing such a connection has been disclosed (for example, see Patent Document 1).

In the case disclosed in this patent document, a large-capacity video or audio using a network system such as an ad hoc network where each wireless terminal is multi-hop connected and can be any of transmission, reception and relay terminals. When data is transmitted while being relayed, control is performed so as to limit the amount of data to be relayed according to the resource state of the relay terminal in the middle of the route.
JP 2006-50371 A (page 11, FIG. 6)

  By the way, when video data to be monitored acquired in, for example, monitoring work is continuously transmitted as streaming data using a wireless LAN system as described above, real-time performance is ensured due to the nature of the data and the data A connection with a wide data transmission band without omission is set between predetermined wireless terminals. In addition, such a wide data transmission band connection may be set simultaneously between one wireless terminal and a plurality of wireless terminals. Furthermore, in addition to connections for handling multimedia data, connections for handling data traffic may be set in the wireless LAN at the same time.

  On the other hand, in a wireless LAN system, it is known that traffic is congested, for example, transmission data from a plurality of wireless terminals collide. Usually, for example, a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method is employed, but it is difficult to eliminate traffic congestion due to a so-called hidden terminal problem.

  However, in the situation where a large number of connections including large-capacity data transmission are set up in the wireless LAN system as described above, such traffic congestion is likely to occur, and once congestion occurs, each data The retransmission will be repeated, and the transmission efficiency will be significantly reduced. In particular, when traffic congestion occurs during transmission of streaming data such as video data that requires a wide data transmission band, the real-time property is lost and data loss frequently occurs. As a result, there is a risk of affecting the performance of the monitoring work while acquiring the video data.

  The present invention has been made in consideration of the above-described circumstances, and when transmitting data that requires a wide transmission band in a wireless LAN system, a wireless LAN system, a wireless terminal, and the like that suppress a decrease in transmission efficiency. It is another object of the present invention to provide a communication method in a wireless LAN system.

  To achieve the above object, the wireless LAN system of the present invention is a wireless LAN system in which a plurality of wireless terminals directly transmit data while establishing a connection with each other on the same channel. Data having a threshold as an upper limit of a data transmission band that can be occupied in each connection, which is preset to a value less than the data transmission band unique to the wireless LAN system, and having a data transmission band exceeding the threshold When transmitting, a priority connection that can occupy the data transmission band exceeding this threshold is established between the wireless terminals that perform this data transmission at the same time in the wireless LAN system, and this priority connection is established. Data transmission through the other connection during Wherein the interruption time.

  In addition, the wireless terminal of the present invention is a bandwidth calculator that calculates a data transmission bandwidth required for transmitting target data in a wireless terminal used in a wireless LAN system that directly transmits data while establishing a connection with each other on the same channel. Means and whether or not the calculated data transmission band exceeds a threshold value as an upper limit of the data transmission band that can be occupied in the connection, which is preset to a value less than the data transmission band specific to the wireless LAN system. If the calculated data transmission band exceeds the threshold value as a result of the determination by the determination means and the determination means, only one connection exceeds the threshold value simultaneously in the wireless LAN system. The destination is a priority connection that can occupy the data transmission band necessary for transmitting the target data. Establishing a priority request in the wireless LAN to temporarily suspend all data transmissions other than the priority connection in the wireless LAN during the establishment of the priority connection. Then, the target data is transmitted to the wireless terminal that is the destination, and after the transmission is completed, a priority release request for releasing the priority request and releasing the priority request is issued in the wireless LAN. A priority connection setting control means; and a data waiting means for temporarily waiting for data to be transmitted other than the priority connection when the priority request is received, and restarting the transmission after receiving the priority release request. Features.

  Further, the communication method in the wireless LAN system of the present invention is a communication method in a wireless LAN system in which a plurality of wireless terminals perform direct data transmission while establishing a connection with each other on the same channel. Data is transmitted from the first wireless terminal to the second wireless terminal having a threshold value as an upper limit of the data transmission band that can be occupied in the connection, which is preset to a value less than the data transmission band unique to the LAN system In this case, the first terminal calculates a data transmission band necessary for transmitting the data, determines whether the calculated data transmission band exceeds the threshold, and determines the determination. As a result, when the threshold value is exceeded, only this connection exceeds this threshold value simultaneously in the wireless LAN system. A priority connection capable of occupying a data transmission band necessary for transmitting the data is established with the second wireless terminal, and during the period of establishment of the priority connection, the priority connection other than the priority connection in the wireless LAN is established. A priority request for temporarily suspending data transmission by connection is issued in the wireless LAN, and then the data is transmitted to the second wireless terminal. After the data transmission is completed, the priority is transmitted. A priority release request for releasing the connection and releasing the priority request is issued in the wireless LAN, and the other wireless terminal receiving the priority request temporarily waits for data to be transmitted other than the priority connection, and The transmission is resumed after receiving the release request.

  According to the present invention, there is provided a wireless LAN system, a wireless terminal, and a communication method in a wireless LAN system that can suppress a decrease in transmission efficiency when transmitting data that requires a wide transmission band in the wireless LAN system. Obtainable.

  The best mode for carrying out a wireless LAN system, a wireless terminal, and a communication method in the wireless LAN system according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a conceptual diagram showing an embodiment of a wireless LAN system according to the present invention, particularly focusing on connection transition. In FIG. 1, this wireless LAN system is illustrated as having four wireless terminals, that is, a wireless terminal A11, a wireless terminal B12, a wireless terminal C13, and a wireless terminal D14. These four wireless terminals are configured identically, and as illustrated in FIG. 1A, each wireless terminal directly transmits data while establishing a connection with each other on the same channel. Yes. The wireless LAN system has a unique data transmission band determined by various conditions such as the frequency, modulation format, or encoding method of the wireless signal employed, and each connection has data exceeding this unique data transmission band. Data transmission having a transmission band cannot be performed. In the wireless LAN system according to the present invention, the upper limit of the data transmission band that can be occupied by one connection is set based on the data transmission band specific to this wireless LAN system so that a plurality of connections can be stably secured simultaneously in the system. A threshold value that is less than the inherent data transmission band is provided and set in each wireless terminal (not shown). In FIG. 1A, a case where five connections having a data transmission band not exceeding the preset threshold value are established between the wireless terminals as indicated by arrows. Illustrated.

  Here, when transmitting multimedia streaming data such as video data acquired in a monitoring operation, for example, exceeding this threshold, as shown in FIG. 1B, the corresponding wireless terminal In the meantime, a priority connection that can occupy a wider data transmission band that exceeds the threshold is established, and data transmission by other connections is temporarily suspended. In FIG. 1B, a priority connection is established between the wireless terminal B12 and the wireless terminal D14 among the five connections shown in FIG. 1A, and the other four connections are data. This is an example of the case where the transmission is temporarily suspended. During this interruption, transmission / reception of wireless signals is temporarily suspended and transmission data is also temporarily suspended, thereby eliminating traffic congestion and suppressing a decrease in transmission efficiency. With this priority connection, a wider data transmission bandwidth is provided. Data transmission is executed efficiently.

  After that, when the data transmission by the priority connection is completed, as illustrated in FIG. 1C, the established priority connection is released and the temporary interruption of other connections is also released and temporarily suspended. Data transmission through other connections is resumed and necessary connections are continuously established between the terminals.

  FIG. 2 is a block diagram illustrating an example of the configuration of the wireless terminals A11 to D14 of FIG. These four wireless terminals are all configured identically, and as illustrated in FIG. 2, a transmission data processing unit 21, a transmission band calculation unit 22, a transmission band comparison / determination unit 23, a priority connection setting control unit 24, transmission data It comprises a standby unit 25 and a transmission / reception unit 26. Further, based on the data transmission band unique to the wireless LAN system, a threshold value 231 is set in advance as an upper limit of the data transmission band that can be occupied by one connection. This threshold value 231 is set to an appropriate value less than the data transmission band specific to the wireless LAN system in consideration of, for example, an operation request for the wireless LAN system and its operating environment.

  The transmission data processing unit 21 forms various types of transmission data to be transmitted and performs predetermined data processing on the received transmission data. The transmission band calculation unit 22 calculates a data transmission band necessary for transmission data to be transmitted. The required data transmission bandwidth is basically determined from the amount of data generated per unit time, etc.For example, a table in which the required data transmission bandwidth is set in advance for each type of transmission data is provided. A method for calculating a data transmission band by referring to the data can also be used. The transmission band comparison / determination unit 23 determines whether the data transmission band of transmission data to be transmitted calculated by the transmission band calculation unit 22 exceeds a threshold value 231.

  The priority connection setting control unit 24 issues a priority connection establishment and release control, a priority request and a priority release request in the wireless LAN based on the determination result, and receives a priority request from another terminal. Until the priority release request is received, the transmission data waiting unit 25 (to be described later) temporarily waits for transmission data transmitted from the own wireless terminal. However, in this embodiment, the data for which the emergency flag is set is transmitted without temporarily waiting. In addition, the priority request is issued at a fixed period during the establishment of the priority connection, and when the priority request of the fixed period is not received, the priority release request can be configured to be received, According to such a configuration, priority connection setting control can be flexibly performed even with respect to a change in the propagation state of a radio signal. The transmission data standby unit 25 temporarily stores the transmission data during the standby period, and sends the transmission data that has been waiting after the priority connection is released. The transmission / reception unit 26 converts transmission data to be transmitted from the priority connection setting control unit 24 into a radio signal and transmits it, and also converts the received radio signal into transmission data to convert the transmission data processing unit 21 and the priority connection setting. The data is sent to the control unit 24.

  Next, the operation of the wireless LAN system of the present embodiment configured as described above will be described with reference to FIG. 1 and FIG. 2 and the sequence diagram of FIG. In the following description, as illustrated in FIG. 1, the description will focus on a situation where a priority connection is established between the wireless terminal B12 and the wireless terminal D14 and then released.

  FIG. 3 is a sequence diagram for explaining the operation of the wireless LAN system according to the present invention. First, the four wireless terminals 11 to 14 directly transmit data while establishing connections with each other through the same channel as shown in FIG. At this time, each connection handles, for example, data-related traffic or the like whose data transmission band does not exceed the threshold 231 (ST401). Here, for example, when a request to transmit video data having a data transmission band exceeding the threshold 231 is generated from the wireless terminal D14 to the wireless terminal B12, the video data is transmitted within the wireless terminal D14. A data transmission band necessary for transmission is calculated by being sent from the data processing unit 21 to the transmission band calculating unit 22. Further, the calculation result is sent to the transmission band comparison / determination unit 23 and compared with the threshold value 231, and the result is sent to the priority connection setting control unit 24 (ST402).

  As a result of the comparison, when it is determined that the data transmission band required for the video data exceeds the threshold value 231, it is necessary to establish a priority connection and data transmission is necessary, so that the priority connection setting control unit 24 Transmits a request for establishing a priority connection to the wireless terminal B12 through the transmitting / receiving unit 26 (ST403). Receiving this request, the wireless terminal B12 accepts the request based on the control of its own priority connection setting control unit 24, and a priority connection is established between the wireless terminal D14 and the wireless terminal B12 (ST404).

  Following this, the priority connection setting control unit 24 of the wireless terminal D14 sends a priority request for temporarily interrupting data transmission by a connection other than the priority connection to another wireless terminal in the wireless LAN (in this embodiment, the wireless terminal). Issued to A11 and wireless terminal C13). In this embodiment, the priority request is issued at regular intervals thereafter, and is also issued from the wireless terminal B12 on the destination side of the priority connection. On the other hand, when the priority request is received by the wireless terminal A11 and the wireless terminal C13, this priority request is sent from the transmission / reception unit 26 in each wireless terminal to the priority connection setting control unit 24, and the connection established in step ST401. The data transmission by is temporarily interrupted. Then, the transmission data generated from the transmission data processing unit 21 during the interruption period is temporarily stored in the transmission data standby unit 25 and stored (ST405).

  Thereafter, transmission of video data is started from the wireless terminal D14 on the transmission side to the wireless terminal B12 on the reception side using the established priority connection, and the transmission is continued while issuing a priority request at regular intervals. (ST406 and ST407). However, in the present embodiment, the data for which the emergency flag is set is transmitted without causing a temporary standby, and the destination is accepted even when the priority connection is being set as in the wireless terminal D14, for example ( ST408).

  When the transmission of the video data that has been continuously transmitted using the priority connection is completed, the priority connection setting control unit 24 of the wireless terminal D14 releases the priority connection to the wireless terminal B12 in order to release the priority connection. The request for transmitting is transmitted through the transmission / reception part 26 (ST409). Receiving this request, the wireless terminal B12 accepts this request, and the priority connection established between the wireless terminal D14 and the wireless terminal B12 is released (ST410).

  Furthermore, these two wireless terminals issue priority cancellation requests for canceling the priority requests issued in step ST405 to other wireless terminals in the wireless LAN. Thereafter, the data transmission traffic is continued between the wireless terminal D14 and the wireless terminal B12 by establishing a connection similar to ST401 or a priority connection again as required for data transmission. On the other hand, when the priority cancellation request is received, the wireless terminal A11 and the wireless terminal C13 resume the temporarily interrupted data transmission. If there is transmission data temporarily stored in each transmission data standby unit 25 during the interruption period, the data is transmitted through the initial connection, and traffic is continued (ST411).

  As described above, in this embodiment, in a wireless LAN system in which a plurality of wireless terminals directly transmit data while establishing connections with each other on the same channel, each wireless terminal is connected to each other during data transmission. A threshold is set in advance as the upper limit of the data transmission band that can be occupied by. This threshold value is set to a value less than the inherent data transmission band of this wireless LAN system. When data having a data transmission band exceeding the threshold is generated and transmitted, such as video data, the threshold is set between the corresponding wireless terminals for only one connection at the same time in the wireless LAN system. Data transmission is performed by establishing a priority connection that can occupy the data transmission band beyond this, and while the priority connection is established, data transmission by other connections in the wireless LAN is temporarily suspended. As a result, traffic congestion due to transmission data collisions in the wireless LAN can be greatly reduced, so when transmitting data that requires a wide transmission band, real-time performance can be ensured and data loss can be prevented. It is possible to reduce the reduction in transmission efficiency.

  In addition, transmission data generated in other wireless terminals during the temporary suspension, while temporarily waiting in its own wireless terminal, resume transmission after the priority connection is released, and for transmission data with an emergency flag set, Transmission is performed even during the establishment of a priority connection, and quality to be serviced as a wireless LAN system is ensured.

  In addition, each wireless terminal calculates the transmission band of data to be transmitted when transmitting data, and if the result exceeds the threshold, executes a procedure for establishing a priority connection with the destination wireless terminal At the same time, a priority request for temporarily suspending data transmission is issued to other terminals, and then data transmission is performed. At the end of transmission, the priority connection is released and a priority release request is issued. On the other hand, when a priority request is received, data transmission is temporarily suspended except for data for which an urgent flag is set, and subsequent transmission data is temporarily held in its own wireless terminal, and data transmission is performed after receiving a priority release request. Has resumed. Therefore, according to the wireless terminal of the present embodiment, traffic congestion in the wireless LAN can be greatly reduced, so that when transmitting data requiring a wide transmission band, the real-time property can be ensured and the data can be secured. Missing data can also be reduced, and a decrease in transmission efficiency can be suppressed. In addition, transmission data generated by the own wireless terminal during a temporary interruption due to a priority request and temporarily suspended will resume transmission after receiving a priority cancellation request, and will also interrupt transmission data for which an emergency flag is set Transmission is performed without any problem, and the quality to be serviced as a wireless LAN system is ensured.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a conceptual diagram showing an embodiment of a wireless LAN system according to the present invention. The block diagram which shows an example of a structure of the radio | wireless terminal which concerns on this invention. The sequence diagram for demonstrating operation | movement of the wireless LAN system which concerns on this invention. The figure which shows an example of the conventional wireless LAN system.

Explanation of symbols

11, 12, 13, 14 Wireless terminal 21 Transmission data processing unit 22 Transmission band calculation unit 23 Transmission band comparison determination unit 24 Priority connection setting control unit 25 Transmission data standby unit 26 Transmission / reception unit 231 Threshold value

Claims (8)

In a wireless LAN system in which a plurality of wireless terminals directly transmit data while establishing a connection with each other on the same channel,
The plurality of wireless terminals have a threshold as an upper limit of a data transmission band that can be occupied in each connection, which is preset to a value less than the data transmission band specific to the wireless LAN system,
When transmitting data having a data transmission band exceeding the threshold,
A priority connection that can occupy the data transmission band exceeding the threshold is established between the wireless terminals that perform data transmission for only one connection at the same time in the wireless LAN system, and during the period when the priority connection is established. A wireless LAN system characterized by temporarily interrupting data transmission through the other connection.   2. The data according to claim 1, wherein the data has an urgent data flag therein, and transmission of data in which the urgent flag is set is not temporarily interrupted even during a period in which the priority connection is established. The wireless LAN system described. In a wireless terminal used in a wireless LAN system that directly transmits data while establishing a connection with each other on the same channel,
Bandwidth calculation means for calculating the data transmission bandwidth required for transmission of the target data;
Judgment to determine whether or not the calculated data transmission band exceeds a threshold as an upper limit of the data transmission band that can be occupied in the connection, which is set in advance to a value less than the data transmission band unique to the wireless LAN system Means,
As a result of the determination by the determination means, if the calculated data transmission band exceeds the threshold value,
In the wireless LAN system, a priority connection that can occupy the data transmission band necessary for transmitting the target data by exceeding only one connection at the same time is established with the wireless terminal that is the destination, and this priority is set. During the connection establishment period, a priority request for temporarily suspending all data transmissions by connections other than the priority connection in the wireless LAN is issued to the wireless terminal as a destination after issuing a priority request to the wireless LAN. The target data is transmitted, and after the transmission is finished, a priority connection setting control means for releasing a priority release request in the wireless LAN for releasing the priority connection and releasing the priority request;
If the priority request is received,
A wireless terminal comprising: data waiting means for temporarily waiting for data to be transmitted other than the priority connection and restarting the transmission after receiving the priority release request. The priority request in the priority connection setting control means is repeatedly issued at a predetermined cycle during the period in which the priority connection is established,
4. The wireless terminal according to claim 3, wherein the data waiting unit considers that the priority cancellation request is received when the priority request is not received in the predetermined period after the priority request is first received. .   The data has an urgent data flag therein, and the data standby means transmits the data set with the urgent flag generated during the period in which the priority connection is established without temporarily waiting. The wireless terminal according to claim 3, wherein the wireless terminal is a wireless terminal. In a communication method in a wireless LAN system in which a plurality of wireless terminals perform direct data transmission while establishing a connection with each other on the same channel,
The plurality of wireless terminals have a threshold value as an upper limit of a data transmission band that can be occupied in the connection, set in advance to a value less than the data transmission band specific to the wireless LAN system,
When transmitting data from the first wireless terminal to the second wireless terminal,
The first terminal is
Calculate the data transmission bandwidth required to transmit the data,
Determine whether this calculated data transmission bandwidth exceeds the threshold,
As a result of the determination, when the threshold value is exceeded, priority that can occupy the data transmission band necessary to transmit the data exceeding the threshold value for only one connection at the same time in the wireless LAN system. Establishing a connection with the second wireless terminal;
During the establishment of the priority connection, a priority request for temporarily suspending all data transmissions by connections other than the priority connection in the wireless LAN is issued to the second wireless terminal. Transmit the data between them,
After completing the transmission of the data, issue a priority release request in the wireless LAN to release the priority connection and release the priority request,
Other wireless terminals that have received the priority request are:
Temporarily wait for data to be transmitted on other than the priority connection,
A communication method in a wireless LAN system, wherein the transmission is resumed after receiving the priority release request.   The priority request is repeatedly issued at a predetermined cycle during the period in which the priority connection is established, and other wireless terminals that have received the priority request receive the predetermined request after the priority request is first received. The communication method in the wireless LAN system according to claim 6, wherein, when not received in a cycle, it is considered that the priority cancellation request has been received.   The data has an urgent data flag therein, and the other wireless terminal receiving the priority request temporarily waits for the data in which the urgent flag is set during the period in which the priority connection is established. The communication method in the wireless LAN system according to claim 6 or 7, wherein transmission is performed without any transmission.

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