JP2009224881A - Wireless terminal device, access point search method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a scanning time and a time for wireless communication by scanning by providing excellent passive scanning. <P>SOLUTION: A wireless terminal device stores beacon interval information at an access point. Also, a state of "belonging" to a management part inside its own device is managed. When the wireless terminal device moves, a radio condition with the access point worsens and scanning is executed so as to try to belong to another access point. In so doing, according to the beacon interval information stored in the storage part and the belonging state managed by the management part, the wireless terminal device performs passive scanning only for a time of the beacon interval information stored in the storage part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless terminal device, an access point search method, and a program.

  Generally, in a wireless LAN (Local Area Network) environment, a wireless terminal device performs a scan to search for an access point to which it belongs. This scan can be classified into an active scan and a passive scan.

  In the active scan, a probe request frame is transmitted, and the access point returns a probe response frame, thereby actively searching for an access point to which it can belong. On the other hand, the passive scan searches passively by receiving a beacon frame periodically transmitted from the access point.

  The passive scan is inferior to the active scan because the scan time is long and the power consumption is large. However, it is not necessary to perform only active scanning. For example, in a domain such as a nation, the frequency band and the maximum transmission power permitted by a wireless LAN are uniquely determined. Even within the same domain, the usage may differ depending on the frequency band, such as being only usable indoors. Since the wireless terminal device moves between domains and indoors and outdoors, even if a probe request or other frame is transmitted in an environment where the wireless terminal device is currently located, it is not known whether it violates the domain regulations.

  For this reason, information can be collected without violating regulations by performing a passive scan that performs a search using only the reception capability.

  If a frame such as a beacon can be received by passive scan, information such as a frequency band that can be used in the domain can be obtained by receiving an information element defined by IEEE 802.11d. In addition, even when there is no information element defined in IEEE 802.11d, it can be seen that at least a channel that can receive a frame such as a beacon can be used.

  In order to shorten the scan time, for example, in Patent Document 1, if it is determined that the access point to which the original attribute belongs and the access point to which the attribute belongs next belong to the same domain, it is assumed that there is no violation of the regulations, and the passive scan The active scan is performed without performing the above. Further, in Patent Document 2, a passive scan is efficiently performed by scheduling a passive scan by generating a site timing table.

JP 2004-229278 A Special table 2007-507982

  The first problem is that the method disclosed in Japanese Patent Application Laid-Open No. 2004-229278 cannot reduce the scan time when there is no domain information in the frame transmitted from the access point. The reason is that a normal passive scan is necessary to perform a safe scan in a state where domain information is not held.

  The second problem is that in the method disclosed in Japanese Patent Application Laid-Open No. 2004-229278, for example, when transmission in the 802.11a frequency band is prohibited outdoors, it is necessary to determine whether the transmission is outdoors or not. The time cannot be shortened. The reason is that even if domain information is obtained, it cannot be used for judgments such as indoors and outdoors, and a normal passive scan is required.

  A third problem is that the method of Japanese Patent Publication No. 2007-507982 may not reduce the total scan time when the wireless terminal device moves. The reason is that the schedule of the neighboring access point cannot be executed until the information of the site timing table of the new neighboring access point is obtained, and a normal passive scan is necessary.

  The present invention has been made under such a background, and is a wireless terminal device and access point search that realizes a suitable passive scan capable of shortening the scan time and shortening the no-communication time by the scan. An object is to provide a method and a program.

  The present invention is a wireless terminal device that receives a beacon transmitted from an access point, searches for a nearby access point, and connects to the searched access point using a wireless line.

  Here, the feature of the present invention is that a beacon interval information storage unit that stores beacon interval information received from an access point, and an belonging state management unit that manages an belonging state to the access point of the own wireless terminal device, When the radio wave condition deteriorates, beacon interval information at the access point to which the own wireless terminal device belongs is acquired based on the information obtained by referring to the belonging state management means and the beacon interval information storing means. And a scan time determining means for determining a scan time corresponding to the interval information of the beacon at the access point to which the own wireless terminal device acquired by the acquiring means belongs as a scan time for performing the passive scan. It is in place.

  When the present invention is viewed from the viewpoint of an access point search method, the present invention receives a beacon transmitted from an access point, searches for a nearby access point, and connects to the searched access point using a wireless line. This is an access point search method applied to a wireless terminal device.

  Here, the feature of the present invention is that the beacon interval information storage means stores the beacon interval information received from the access point, and the belonging state management means indicates the belonging state to the access point of the own wireless terminal device. When the radio wave condition deteriorates, the managing and acquiring means is based on the information obtained by referring to the belonging state managing means and the beacon interval information storing means at the access point to which the own wireless terminal device belongs. The interval information of the beacon is acquired, and the scan time determination means performs the passive scan with the scan time according to the interval information of the beacon at the access point to which the own wireless terminal device acquired by the acquisition means belongs. This is where the scan time is determined.

  When the present invention is viewed from the viewpoint of a program, the present invention installs the information processing apparatus to receive the beacon transmitted from the access point and searches for the nearby access point. It is a program for realizing an access point search function applied to a wireless terminal device connected to the access point using a wireless line.

  Here, the features of the present invention are a beacon interval information storage function for storing beacon interval information received from an access point, and an belonging state management function for managing an belonging state to the access point of the own wireless terminal device; When the radio wave condition deteriorates, beacon interval information at the access point to which the own wireless terminal device belongs is acquired based on the information obtained by referring to the belonging state management function and the beacon interval information storage function. A scan time determination function for determining a scan time corresponding to the interval information of the beacon at the access point to which the own wireless terminal device acquired by this function belongs and the scan time for performing the passive scan. It is where it will be realized.

  According to the present invention, it is possible to shorten the scan time and the no-communication time due to the scan.

(First embodiment)
A first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a block configuration diagram of a wireless terminal device 1 according to the first embodiment. FIG. 2 is a diagram showing a movement path, access points 10 to 12, communication ranges 21 to 23, and backbone networks 24 and 25 of the wireless terminal device 1 for explaining the operation of the wireless terminal device 1 of the first embodiment. is there. Here, description will be made with reference to the situation of FIG. Referring to FIG. 2, the wireless terminal device 1 receives a beacon transmitted from the access points 10, 11, and 12, searches for a nearby access point 10, 11, or 12, and searches for the searched access point 10, 11, or 12. Connect using a wireless line.

  As illustrated in FIG. 1, the wireless terminal device 1 includes a storage unit 3 that is a beacon interval information storage unit that stores interval information of beacons received from the access point 10, and attribution of the own wireless terminal device 1 to the access point 10. And a management unit 4 which is an belonging state management means for managing the state, and when the radio wave state deteriorates, the own wireless terminal device 1 belongs based on information obtained by referring to the management unit 4 and the storage unit 3. Means for acquiring the beacon interval information at the access point that has been acquired, and the scan time corresponding to the beacon interval information at the access point 10 to which the own wireless terminal device 1 acquired by the acquiring means belongs, And a determination unit 5 including a scan time determination unit that determines a scan time to be performed. .

  That is, the wireless terminal device 1 includes a wireless input / output processing unit 2 that performs wireless communication, a storage unit 3 that stores information on the beacon interval of the access point received by the wireless input / output processing unit 2, and a management that manages the belonging state. Part 4. Moreover, the determination part 5 which judges whether the information of the beacon interval memorize | stored in the memory | storage part 3 is used according to the attribution state managed by the management part 4, and determines scanning time is provided. Further, a control unit 6 that controls the wireless input / output processing unit 2, the storage unit 3, the management unit 4, and the determination unit 5 is provided.

  Next, the operation of the wireless terminal device 1 of the first embodiment will be described with reference to FIGS. Referring to FIG. 2, access points 10, 11, and 12 are installed, and a communication range 21 indicates a range in which the access point 10 can communicate. Similarly, the communication range 22 indicates the range in which the access point 11 can communicate, and the communication range 23 indicates the range in which the access point 12 can communicate.

  It is assumed that the access point 10 and the access point 11 are connected to the same backbone network 24 and installed so as to be able to perform handover while maintaining the belonging state. Further, it is assumed that the access point 12 is connected to the backbone network 25 and cannot be handed over with the access points 10 and 11 while maintaining the belonging state.

  Now, it is assumed that the wireless terminal device 1 belongs to the access point 10. At this time, the wireless terminal device 1 stores the beacon interval information of the access point 10 in the storage unit 3. Further, the state of “being attributed” is managed by the management unit 4. Thereafter, it is assumed that the wireless terminal device 1 moves in the direction of the access point 11. When the wireless terminal device 1 moves to the point a, the radio wave condition with the access point 10 deteriorates, and the wireless terminal device 1 executes a scan to try to belong to another access point 11.

  In general, the beacon intervals of the access points 10 and 11 installed in the same system that can be handed over are often the same. Therefore, from the beacon interval information stored in the storage unit 3 and the belonging state managed by the management unit 4, the wireless terminal device 1 sets each channel to the beacon interval information stored in the storage unit 3. It is determined that it is sufficient to perform a passive scan only for the time. As a result, the passive scan time can be shortened.

  In the present embodiment, passive scanning is performed only for the time of beacon interval information. However, in consideration of beacon jitter, the scanning time may be increased or decreased by a fixed time in addition to the time of beacon interval information.

  Next, since the wireless terminal device 1 belongs to the access point 11, the beacon interval information of the access point 11 is stored in the storage unit 3. Further, the state of “being attributed” is managed by the management unit 4. Thereafter, it is assumed that the wireless terminal device 1 moves in the direction of the access point 12. When the wireless terminal device 1 moves to the point b, the radio wave condition with the access point 11 deteriorates, and the wireless terminal device 1 executes a scan to try to belong to another access point 12. However, since a new access point cannot be found at the point b, the wireless terminal device 1 is not affiliated and the “out of service” state is managed by the management unit.

  The wireless terminal device 1 executes a scan periodically or at a certain timing in order to search for a new access point 12. At this time, the beacon interval information of the access point 11 is stored in the storage unit 3, but since the state of “out of service” is managed by the management unit 4, it does not always belong to the access point of the same system. The beacon interval information stored in the storage unit 3 is not used, and the access point search is performed using the default scan time of the wireless terminal device 1. This makes it possible to search for a suitable access point even in another system where the beacon interval is unknown.

  The operation described above is shown in the flowchart of FIG. FIG. 3 is a flowchart showing the operation of the control unit 6. FIG. 4 shows a scan time obtained by adding an additional scan time to the beacon interval. As shown in FIG. 3, when the control unit 6 recognizes the deterioration of the radio wave state in the wireless input / output processing unit 2 (step S1), the storage unit 3 stores the beacon interval information (Yes in step S2). Whether or not the wireless terminal device 1 belongs to the access point (AP and illustration) of the stored beacon interval information is checked with reference to the management unit 4, and if it belongs (Yes in step S3) Then, a passive scan is performed based on the beacon interval information stored in the storage unit 3 (step S4).

  In addition, when an access point is not found even if passive scanning is performed based on the beacon interval information stored in the storage unit 3 (No in step S5), passive scanning is performed with a default scanning time ( Step S6).

  Further, when there is no storage of beacon interval information in the storage unit 3 (No in step S2), or when the wireless terminal device 1 does not belong to the access point of the beacon interval information stored in the storage unit 3 (No in step S3), the passive scan is performed from the beginning with the default scan time (step S6).

Further, as shown in FIG. 4, the determination unit 5 determines the scan time in which the additional time is added to the actual beacon interval, so that the beacon can be received even if there is a beacon delay due to jitter. Become.
(Second embodiment)

  A wireless terminal device 30 according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block configuration diagram of the wireless terminal device 30 of the second embodiment. Referring to FIG. 3, the wireless terminal device 30 includes a wireless input / output processing unit 31 that performs wireless communication, a storage unit 32 that stores information on a beacon interval of an access point received by the wireless input / output processing unit 31, and an belonging state The management part 33 which manages this. In addition, it is determined whether to use the information of the beacon interval stored in the storage unit 32 according to the belonging state managed by the management unit 33, and the determination unit 34 that determines the scan time, and the determined scan time And a dividing unit 35 for dividing. Furthermore, a control unit 36 that controls the wireless input / output processing unit 31, the storage unit 32, the management unit 33, the determination unit 34, and the division unit 35 is provided.

  Next, the operation of the second embodiment will be described with reference to FIGS. FIG. 6 is a diagram illustrating a movement path, access points 40 and 41, communication ranges 51 and 52, and a backbone network 53 of the wireless terminal device 30 for explaining the operation of the wireless terminal device 30 according to the second embodiment.

  Access points 40 and 41 are installed, and a communication range 51 indicates a range in which the access point 40 can communicate. Similarly, the communication range 52 indicates a range in which the access point 41 can communicate. It is assumed that the access points 40 and 41 are connected to the same backbone network 53 and installed so as to be able to perform handover while maintaining the belonging state.

  Now, it is assumed that the wireless terminal device 30 belongs to the access point 40. At this time, the wireless terminal device 30 stores the beacon interval information of the access point 40 in the storage unit 32. Further, the status of “being attributed” is managed by the management unit 33. Thereafter, it is assumed that the wireless terminal device 30 moves in the direction of the access point 41. When the wireless terminal device 30 moves to the point c, the radio wave condition with the access point 40 deteriorates, and the wireless terminal device 30 performs a scan to try to belong to another access point 41.

  At this time, from the beacon interval information stored in the storage unit 32 and the belonging state managed in the management unit 33, the wireless terminal device 30 uses the beacon interval information stored in the storage unit 32 for each channel. It is determined that the passive scan is performed for the period of time. The description so far is the same as in the first embodiment.

  In the second embodiment, the dividing unit 35 divides the scan time determined by the determining unit 34. For example, FIG. 7 shows a diagram showing the relationship between the scan and the beacon interval of the access point when the scan time is divided into two equal parts. Scans 60 and 61 indicate divided passive scans. Beacons A-1, A-2, A-3, and A-4 indicate access point A beacons, and beacons B-1, B-2, B-3, and B-4 indicate access point B beacons. The beacons C-1, C-2, C-3, and C-4 indicate access point C beacons.

  First, the passive scan is performed for half the time (T / 2) of the beacon interval information, and then the passive scan is performed for the remaining time (T / 2) after the time (T) of the beacon interval information. By dividing in this way, an access point can be found no matter what timing other access points with the same beacon interval transmit beacons. As a result, it is possible to reduce the no-communication time by one scan.

In the example of FIG. 7, an example in which the scan time is divided into two parts is shown, but it may be divided into three equal parts or more. In addition, division with different scan times may be performed instead of equal division.
(Example of the program)

  An example of a program that, when installed in an information processing apparatus, causes the information processing apparatus to realize a function corresponding to the function of the wireless terminal device 1 or 30 of the present embodiment will be described. Here, the information processing apparatus is a general-purpose computer apparatus.

  By recording the program of this embodiment on a recording medium, the information processing apparatus can install the program of this embodiment using this recording medium. Alternatively, the program of the present embodiment can be directly installed on the information processing apparatus from the server holding the program of the present embodiment via the network.

  Thereby, using the information processing device, the communication control function in the wireless input / output processing unit 2 or 31 in the wireless terminal device 1 or 30 of the present embodiment, the function of the storage unit 3 or 32, the function of the management unit 4 or 33, The function of the determination unit 5 or 34, the function of the control unit 6 or 36, and the function of the dividing unit 35 can be realized.

The program of this embodiment includes not only a program that can be directly executed by the information processing apparatus but also a program that can be executed by being installed on a hard disk or the like. Also included are those that are compressed or encrypted.
(Explanation of effect)

  The first effect is that even when there is no domain information in the frame transmitted from the access point, the scan time can be shortened and the no-communication time by the scan can be shortened. The reason is that the scan time of the passive scan can be shortened using the information of the beacon interval received from the access point even when the domain information is not held.

  The second effect is that the scan time can be shortened and the non-communication time by the scan can be shortened also in the scan when determining whether or not it is outdoors. The reason is that the domain information that cannot be determined whether it is outdoors is not used, and the scan time of the passive scan can be shortened by using the information of the beacon interval received from the access point.

  The third effect is that even when the wireless terminal device moves, the total scan time can be shortened and the no-communication time by the scan can be shortened. The reason is that it is not necessary to obtain information on the site timing table of a new neighboring access point.

  According to the present invention, the scan time can be shortened and the no-communication time by the scan can be shortened. Therefore, the present invention can be used for improving the use efficiency of the network.

It is a block block diagram of the radio | wireless terminal apparatus in 1st embodiment of this invention. It is a figure which shows the movement path | route of a wireless terminal device, an access point, a communication range, and a backbone network for demonstrating operation | movement of the wireless terminal device of 1st embodiment of this invention. It is a flowchart which shows operation | movement of a control part. It is a figure which shows the scanning time which provided the additional scanning time to the beacon interval. It is a block block diagram of the radio | wireless terminal apparatus in 2nd embodiment of this invention. It is a figure which shows the movement path | route of a wireless terminal device, an access point, a communication range, and a backbone network for demonstrating operation | movement of the wireless terminal device of 2nd embodiment of this invention. It is the figure which showed the time relationship between the scan at the time of dividing a scan time into two, and the beacon interval of an access point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,30 Wireless terminal device 2, 31 Wireless input / output processing part 3, 32 Storage part 4, 33 Management part 5, 34 Determination part 35 Dividing part 6, 36 Control part 10-12, 40, 41 Access point 21-23, 51, 52 Communication range 24, 25, 53 Core network 60, 61 Scan A-1, A-2, A-3, A-4, B-1, B-2, B-3, B-4, C- 1, C-2, C-3, C-4 Beacon

Claims (12)

In a wireless terminal device that receives a beacon transmitted from an access point and searches for nearby access points, and connects to the searched access point using a wireless line,
Beacon interval information storage means for storing beacon interval information received from the access point;
Belonging state management means for managing the belonging state to the access point of the own wireless terminal device;
Means for acquiring beacon interval information at the access point to which the own wireless terminal device belongs, based on information obtained by referring to the belonging state management means and the beacon interval information storage means when the radio wave state deteriorates When,
Scan time determining means for determining, as a scan time for performing a passive scan, a scan time corresponding to the beacon interval information at the access point to which the own wireless terminal device acquired by the acquiring means belongs. A wireless terminal device.   2. The scanning time determining means according to claim 1, further comprising means for determining, as a scanning time, a time obtained by adding a predetermined time to a time corresponding to a beacon interval at an access point to which an own wireless terminal device belongs. Wireless terminal device.   3. The wireless terminal device according to claim 1, further comprising means for performing a passive scan with a default scan time when an access point cannot be searched for based on the scan time determined by the scan time determining means.   Claims comprising means for dividing the scan time determined by the scan time determining means into a plurality of times, and performing a plurality of times of passive scans according to the divided individual times with an interval of the scan time before the division. Item 4. The wireless terminal device according to any one of Items 1 to 3. In an access point search method applied to a wireless terminal device that receives a beacon transmitted from an access point and searches for a nearby access point and connects to the searched access point using a wireless line,
The beacon interval information storage means stores the beacon interval information received from the access point,
The belonging state management means manages the belonging state to the access point of the own wireless terminal device,
When the means for acquiring the radio wave condition deteriorates, the beacon interval at the access point to which the own wireless terminal device belongs is based on the information obtained by referring to the belonging state managing means and the beacon interval information storing means. Get information,
The scan time determining means determines the scan time corresponding to the interval information of the beacon at the access point to which the own wireless terminal device acquired by the acquiring means belongs as the scan time for performing the passive scan. Access point search method.   6. The access point search method according to claim 5, wherein the scan time determining means determines, as a scan time, a time obtained by adding a predetermined time to a time corresponding to a beacon interval at an access point to which the own wireless terminal device belongs. .   The access point search method according to claim 5 or 6, wherein when the access point cannot be searched for by the scan time determined by the scan time determining means, the passive scan is performed by the default scan time.   8. The scan time determined by the scan time determination means is divided into a plurality of times, and a plurality of passive scans according to the divided individual times are respectively performed with an interval of scan time before the division. The access point search method according to any one of the above. By installing on an information processing device,
In a program that realizes an access point search function applied to a wireless terminal device that receives a beacon transmitted from an access point and searches for a nearby access point and connects to the searched access point using a wireless line,
A beacon interval information storage function for storing beacon interval information received from an access point;
An belonging state management function for managing the belonging state to the access point of the own wireless terminal device;
A function of acquiring beacon interval information at the access point to which the own wireless terminal device belongs, based on information obtained by referring to the belonging state management function and the beacon interval information storage function when the radio wave state deteriorates When,
Realize a scan time determination function that determines the scan time corresponding to the beacon interval information at the access point to which the own wireless terminal device acquired by this function belongs as the scan time for performing passive scan A program characterized by   10. The function according to claim 9, wherein the scan time determination function implements a function of determining, as a scan time, a time obtained by adding a predetermined time to a time corresponding to a beacon interval at an access point to which the own wireless terminal device belongs. program.   The program according to claim 9 or 10, which realizes a function of performing a passive scan with a default scan time when an access point cannot be searched for based on the scan time determined by the scan time determination function.   The scan time determined by the scan time determination function is divided into a plurality of times, and a plurality of passive scans according to the divided individual times are respectively implemented by providing an interval of scan times before the division. Item 12. The program according to any one of Items 9 to 11.

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