JP4880546B2 - HANDOVER METHOD AND RADIO TERMINAL DEVICE - Google Patents

Description

The present invention, in a mobile communication system such as a wireless LAN system, relates to a handover method and a radio terminal equipment to realize fast handover.

  Hereinafter, the wireless base station device is referred to as AP (Access Point), and the wireless terminal device is referred to as STA (Station). Further, an AP that is a handover source is referred to as a current AP, and a plurality of APs that are adjacent to the current AP and are candidates for a handover destination are referred to as target APs.

  In the wireless LAN system, in order to realize high-speed handover, the IEEE802.11k standard for acquiring connection information necessary for connection to the target AP in advance and the IEEE802.11r standard for smooth handover are specified. ing. The STA collects the connection information of the target AP using the IEEE802.11k standard, prepares for the handover using the IEEE802.11r standard while belonging to the current AP, and when the handover becomes necessary, the STA quickly collects the current AP. The handover from the target AP to the target AP is completed. In general, in handover in a wireless LAN system, the most time loss factor is to search for a target AP. For this reason, the IEEE802.11r standard for obtaining connection information of the target AP before the handover is defined.

However, when there are a plurality of target APs for which the STA is preparing for handover, it is necessary to attempt to belong to all the target APs when actually performing handover, which hinders high-speed handover. Therefore, conventionally, there has been a method of limiting the number of target AP candidates in order to realize high-speed handover. In other words, this is a method in which a target AP is limited to a server on the network and the connection information is inquired (Patent Document 1). This method assumes that the STA moves one-dimensionally by a train, etc., limits the target AP corresponding to the destination of the STA, and enables high-speed handover by acquiring the connection information of the target AP To do.
JP 2005-31646 A

  However, in the prior art that inquires the connection information of the target AP to the server on the network, it is assumed that the STA moves two-dimensionally or three-dimensionally in a place where the AP is expanded two-dimensionally or three-dimensionally. Not. Further, when trying to cope with such an assumption, there are still a plurality of target APs with a possibility of handover, which hinders high-speed handover.

The present invention provides a handover method capable of realizing high-speed handover by narrowing down target APs even in a situation where there are a plurality of target APs in a place where APs are expanded two-dimensionally or three-dimensionally. Another object of the invention is to provide a radio terminal equipment.

  According to a first aspect of the present invention, a wireless terminal device wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally switches a wireless base station device to be wirelessly connected with movement In the handover method for performing a handover, when a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs, the radio base station apparatus The wireless terminal device holds connection information necessary for establishing a wireless connection with the target AP, and notifies the wireless terminal device of the connection information. The wireless terminal device receives the connection information of the target AP broadcast from the current AP, holds the connection history information of the wireless base station device that was wirelessly connected before the handover to the current AP, and based on this connection history information When the priority is set to the target AP and the handover is performed, the wireless AP is sequentially tried to establish the wireless connection using the connection information of the target AP according to the priority, and the handover is first performed to the target AP that can establish the wireless connection. The information on the current AP is added to the connection history information.

  According to a second aspect of the present invention, a wireless terminal device wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally switches a wireless base station device wirelessly connected with movement In the handover method for performing a handover, when a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs, the radio base station apparatus The wireless terminal device holds connection information necessary for establishing a wireless connection with the target AP, and transmits the connection information of the target AP in response to a request from the wireless terminal device. The wireless terminal device requests the connection information of the target AP from the current AP, receives the connection information of the target AP transmitted from the current AP in response to the request, and wirelessly connected before the handover to the current AP. The connection history information of the base station apparatus is held, the priority order is set to the target AP based on the connection history information, and when performing the handover, the wireless AP is sequentially established using the connection information of the target AP according to the priority order. Attempt to hand over to the target AP that was able to establish a wireless connection first, and add the information of the current AP handed over to the connection history information.

In the first to second aspects of the invention, the time for attempting to establish a wireless connection using the connection information for the target AP having a high priority may be set longer than that of the target AP having a low priority. Good.

In the first and second aspects of the invention, the movement direction of the wireless terminal device is estimated from the connection history information to determine the movement direction of the wireless terminal device, and the target AP viewed from the current AP according to the connection information May be determined, and priority may be set for the target APs in each direction according to the estimation result of the moving direction of the wireless terminal device.

According to a third aspect of the present invention, a wireless terminal device wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally switches a wireless base station device wirelessly connected with movement In a radio terminal apparatus that performs handover, when a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs, Connection information acquisition means for acquiring connection information necessary for establishing a wireless connection with the AP, and connection history information of the wireless base station apparatus that has been wirelessly connected before the handover to the current AP is held, and the current AP that has been handed over Connection history information holding means for adding information to the connection history information, and connection information acquisition means based on the connection history information. Target AP priority order setting means for setting the priority order for the target AP corresponding to the connection information, and when performing handover, the wireless AP first attempts to establish a wireless connection using the connection information of the target AP according to the priority order. This is a configuration for handing over to a target AP that has established a wireless connection.

  Here, the connection information acquisition means receives the connection information of the target AP notified by the current AP or requests the connection information of the target AP from the current AP, and in response to the request, the connection information of the target AP transmitted from the current AP. The connection information is received.

In the first, second and third inventions, the STA estimates the moving direction from the current AP using the connection history information of the AP connected in the past, and sets the priority to the target AP acquired from the current AP. As a result, wireless connection with the target AP can be established efficiently according to the priority order, and handover can be realized at high speed.

  Also, the connection information of the target AP is added in a control signal (for example, beacon) broadcast by the AP, and all STAs belonging to the current AP periodically receive the control signal, thereby preparing for handover at any time. Can do. Further, the STA requests the connection information of the target AP from the current AP and transmits it from the current AP, so that it can reliably acquire the connection information of the target AP and prepare for handover when necessary.

  Further, in the above invention, since the target AP with higher priority is highly likely to be the STA destination, it is more efficient and efficient by trying to establish the wireless connection with respect to the AP. Handover can be realized at high speed.

(First embodiment)
FIG. 1 shows a first embodiment of a wireless LAN system to which the present invention is applied.
In the figure, the wireless LAN system of the present embodiment includes APs 11, 12, and 13 connected to a network 1, and STAs 101 that can be wirelessly connected to each AP. The APs 11, 12, and 13 hold connection information (Neighbor Reports) 21, 22, and 23 of adjacent target APs, and notify the connection information 21, 22, and 23 using the beacons 31, 32, and 33.

  Here, the connection information 21, 22, and 23 are information necessary for the STA to connect to the target AP, and include, for example, information on BSSID (Basic Service Set Identifier), SSID (Service Set Identifier), and channel number. . Although the connection information 21, 22, and 23 held by the APs 11, 12, and 13 can be set from the network 1, each AP may autonomously communicate with an adjacent AP to acquire connection information, or AP maintenance. The person in charge may write the data individually. Further, identification information unique to the AP included in the connection information 21, 22, 23 such as BSSID is referred to as “AP information” in the following description.

  When the STA 101 receives the beacon 31 transmitted by the current AP with which wireless connection has been established (here, the current AP 11), the STA 101 acquires the connection information 21 of the target AP included in the beacon 31, and the candidate of the target AP in the current AP 11 Can know. In FIG. 1, the APs 11, 12, and 13 use the beacons 31, 32, and 33 to notify the respective connection information 21, 22, and 23, and the STA 101 receives the beacons and acquires the connection information. Is omitted.

  The STA 101 refers to a connection history information holding unit 201 that holds AP information of an AP wirelessly connected before handover to the current AP 11 as connection history information, and a position information table in which AP information of the current AP 11 and position information are associated with each other. The STA 101 travel direction history is determined from the connection history information to estimate the STA 101 travel direction, each direction of the target AP as viewed from the current AP is determined according to the connection information, and the travel direction of the wireless terminal device is determined. A target AP priority setting unit 202 is provided for setting a priority for the target AP in each direction according to the estimation result. The detailed processing procedure of the target AP priority order setting unit 202 will be described later.

  Then, the STA 101 tries to establish a wireless connection for the target AP candidate using the connection information 21 according to the priority order set when the handover is necessary, and the target AP that has established the wireless connection earliest. Hand over. At this time, the target AP having a high priority may be controlled so as to establish a wireless connection more reliably over time. Finally, the AP information of the current AP that has been handed over is added to the connection history information holding unit 201 and held.

  FIG. 2 shows the frame format of the beacons 31, 32, and 33. Here, a beacon defined by IEEE802.11 is taken as an example of a control signal notified by the AP, and a frame format of a management frame used for transmission of this beacon is shown.

  The frame format includes a MAC header 901 including information necessary for communication such as a destination address and a transmission source address, a frame body 902 including transmission data, and an FCS 903 which is an error detection code of the frame body. In IEEE802.11, an area that can be uniquely set by a manufacturer called Vendor Specific 904 is secured at the end of the frame body 902 of the beacon. By using this Vendor Specific 904, connection information 21, 22, and 23 of adjacent APs is transmitted. To do.

FIG. 3 shows a setting example of the priority order of the target AP.
In the figure, ● is an AP, AP with ☆ is the current AP, the arrow is the STA movement path based on the connection history information, APs adjacent to the current AP (four in this case) are the target APs, and the priority is a number. 1-4. When APs are developed three-dimensionally, six-direction target APs are assumed, and the priority order of the six target APs is indicated by numerals 1-6.

  FIG. 3 (1) is an example in which the priority order is set based only on the previous connection history information. The STA proceeds in the upward direction in the figure and is at the position of the current AP, and determines that the probability of returning from the current AP to the downward direction in the figure is low. The downward direction (return direction) is given priority 4. Since there are three equal rankings, the priority rankings 2 and 3 are omitted.

  FIGS. 3 (2) and 3 (3) are examples of setting priorities based on the connection history information up to the previous two. The STA in FIG. 3 (2) advances to the left and upward in the figure and is at the current AP position, and it is determined that the probability of returning to the direction that has advanced with respect to the current AP is low. Priority 1 is assigned to the same row, priority 3 is assigned to the right direction, and priority 4 is assigned to the downward direction (return direction).

  In addition, the STA of FIG. 3 (3) is in the position of the current AP, moving in the upward and upward directions in the figure, the probability of returning to the direction that has advanced with respect to the current AP is low, and the probability of progressing in a continuous direction The upper direction is set as priority 1, the left direction and the right direction are set as priority 2 in the same row, and the lower direction (return direction) is set as priority 4.

  FIG. 3 (4) is an example in which priorities are set based on connection history information up to the previous three. The STA advances in the left direction, upward direction, and upward direction in the figure and is at the position of the current AP, and has a low probability of returning to the direction that has been advanced with respect to the current AP, and also proceeds in the continuous direction and the moving direction so far. It is determined that the probability is high, the upper direction is set as priority 1, the left direction is set as priority 2, the right direction is set as priority 3, and the down direction is set as priority 4.

  In this way, by increasing the history information information to be referred to, the priority order can be set finely. Here, for example, when setting the priority order based on the connection history information up to the previous three, the movement direction obtained from the positional relationship of the AP corresponding to the connection history information is counted, and based on the count value, the current FIG. 4 shows an example of a processing procedure for setting the priority order of the target AP corresponding to the estimation result of estimating the moving direction of the STA relative to the AP. Further, FIG. 5 shows an example of processing for setting the priority order of the target AP. When the STA accesses the AP of the wireless LAN system for the first time and there is no connection history information, the processing of FIG. 4 is not started, and the priorities of the target APs adjacent to the current AP are all set to be the same. The

  As shown in FIG. 5, the target AP priority setting unit 202 holds AP information and position information of APs installed in an area (for example, a shopping mall) where the STA moves as an AP position information table. Here, for example, the position information of AP (a) corresponding to AP information BSSID (a) is a. The position information a, b, c,... Only needs to be information that allows the relative positional relationship of each AP to be understood. For example, an X coordinate and a Y coordinate (in some cases, a Z coordinate) represented by integers are used. Expressed. At least accurate positional information such as latitude and longitude is not required. The AP location information table may be downloaded from the current AP when the STA first accesses in the area, or may be set in advance by acquiring the AP location information table of the area to which the user is going. Good. With such an AP position information table, the connection information and connection history information of the target AP acquired from the current AP can be replaced with the position information (movement direction) for processing.

  In FIG. 5, d (1), d (2), d (3), d (4) are the right, top, left, and bottom directions of the page, and the direction d () is based on the current AP (f). A procedure for setting priorities of the target AP (g), AP (b), AP (e), and AP (j) of 1), d (2), d (3), and d (4) will be described. Here, g = 1, b = 2, e = 3, and j = 4.

  In FIG. 4, first, the number of movement directions d (x) is counted from the connection history information (S1). For example, in the example of FIG. 5, the current AP moves from m → n → j → f, and the moving direction d (1) counted when x = 1 is m → n once.

  Next, it is determined whether or not the direction d (x) of the target AP (x) is opposite to the previous movement direction (S2), and if they match, the target AP (x) is set to priority 4 (S3). . Since the reverse direction of the immediately preceding movement direction is d (4), when x = 1, since d (1) ≠ d (4), the process proceeds from S2 to the next S4.

  Next, it is determined whether or not the number of movement directions d (x) that coincide with the direction d (x) of the target AP (x) is two or more (S4). If there are two or more times, the target AP (x) is determined. The priority is set to 1 (S5). When x = 1, since d (1) = 1 is counted, the process proceeds from S4 to the next S6.

  Next, it is determined whether or not the number of movement directions d (x) matching the direction d (x) of the target AP (x) is one (S6), and if it is one, the target AP (x) is determined. The priority is set to 2 (S7). When x = 1, since d (1) = 1 is counted, the process proceeds from S6 to S7, and the target AP (1) (= AP (g)) is set to the priority order 2.

  If d (x) is not 1, it is determined whether or not the number of movement directions d (x) matching the direction d (x) of the target AP (x) is 0 (S8). If so, the target AP (x) is set to priority 3 (S9).

  Similarly, when x = 2, 3, and 4 are repeated, the movement direction d (2) is twice, the movement direction d (3) is zero, and the movement direction d (4) is the reverse direction. As shown in FIG. 4, the priorities of the target AP (b), AP (e), and AP (j) are set to 1, 3, and 4, respectively. Further, as shown in FIGS. 3 (4) to (7), the priority order of each target AP is set similarly. Note that even if the processing method of FIG. 4 is applied to the cases of FIGS. 3 (1) to 3 (3), although the priority values are different, almost the same priority is set.

  In addition, when the current AP is an AP that has been connected in the past, the connection history information holding unit 201 holds the connection information of the AP connected next to the AP so that the AP can be obtained according to the above procedure. Apart from the order, it can also be set as a high priority target AP. An example is shown in Fig. 3 (8).

(Second Embodiment)
FIG. 6 shows a second embodiment of a wireless LAN system to which the present invention is applied.
The wireless LAN system shown in FIG. 1 has a configuration in which APs 11, 12, and 13 report adjacent AP connection information 21, 22, and 23 using beacons 31, 32, and 33, respectively. The wireless LAN system of this embodiment exchanges the connection information 21, 22, and 23 by other methods described below. Others are the same as in the first embodiment, and a description thereof will be omitted.

  The STA 101 transmits a request signal (Probe.Req) 40 that requests the connection information 21 of the current AP 11. The current AP 11 that has received the request signal (Probe.Req) 40 transmits a response signal (Probe.Rsp) 41 including the connection information 21. The STA 101 that has received the response signal (Probe.Rsp) 41 acquires the connection information 21 included therein, and sets the priority order of the target AP as in the first embodiment.

  This embodiment shows an example in which Probe.Req and Probe.Rsp defined in IEEE802.11 are used as a request signal from the STA 101 and a response signal of the current AP 11 corresponding thereto. IEEE802.11 stipulates that connection information (Neighbor Report) can be exchanged between Probe.Req and Probe.Rsp. Further, as a method for exchanging connection information (Neighbor Report), frames called Neighbor Report Req and Neighbor Report Rsp are also defined in IEEE802.11 and may be used.

(Third embodiment)
FIG. 7 shows a third embodiment of a wireless LAN system to which the present invention is applied.
In the figure, the wireless LAN system of this embodiment is composed of APs 14, 15, and 16 connected to the network 1, and STAs 102 that can be wirelessly connected to each AP. The APs 14, 15, and 16 hold adjacent AP connection information (Neighbor Reports) 24, 25, and 26, respectively, and target AP priority order setting means 211, 212, and the like that give priority to target AP candidates included therein. 213. In the first embodiment and the second embodiment, the feature of this embodiment is that each AP includes the target AP priority setting means 202 held by the STA 101.

  The STA 102 includes a connection history information holding unit 201 that holds AP information of an AP wirelessly connected in the past as connection history information, and includes the connection history information in a request signal (Probe.Req) 42 to indicate a current AP (here, current To AP14). The current AP 14 that has received the request signal (Probe.Req) 42 provides the connection history information included in the request signal (Probe.Req) 42 to the target AP priority setting unit 211. The target AP priority setting method in the target AP priority setting means 211 is the same as that in the first embodiment, and a response signal (Probe.Rsp) 43 including the connection information 24 and the set priority is transmitted to the STA 102. To do.

  Then, when handover is necessary, the STA 102 attempts to establish a wireless connection using the connection information 24 for the target AP candidate according to the acquired priority order, and sets the target AP that has established the wireless connection earliest. Hand over. At this time, the target AP having a high priority may be controlled so as to establish a wireless connection more reliably over time. Finally, the AP information of the current AP 14 is added to the connection history information holding unit 201 and held.

  The present embodiment shows an example in which Probe.Req and Probe.Rsp defined in IEEE802.11 are used as a request signal from the STA 102 and a response signal of the current AP 14 corresponding thereto. In IEEE802.11, since Vendor Specific exchanges are defined by Probe.Req and Probe.Rsp, connection information with priority (Neighbor Report) may be acquired using Vendor Specific. .

(Fourth embodiment)
FIG. 8 shows a fourth embodiment of a wireless LAN system to which the present invention is applied.
In the figure, the wireless LAN system of the present embodiment includes APs 17, 18, and 19 connected to a network 1 and a handover information providing server 2, and an STA 103 that can be wirelessly connected to each AP. The handover information providing server 2 holds connection information (Neighbor Report) 27 of APs adjacent to the APs 17, 18, and 19 connected to the network 1, and assigns a priority to target AP candidates included therein. Priority order setting means 214 is provided. In the third embodiment, the handover information providing server 2 includes the connection information (Neighbor Report) 24, 25, and 26 and the target AP priority setting means 211, 212, and 213 held by each AP. This is a feature of the embodiment.

  The STA 103 includes a connection history information holding unit 201 that holds AP information of an AP that has been wirelessly connected in the past as connection history information, and includes the connection history information in the handover information request signal 44 as a current AP (here, referred to as current AP 17). Is transmitted to the handover information providing server 2 via. The handover information request signal 44 includes AP information of the current AP 17. The handover information providing server 2 that has received the handover information request signal 44 gives the AP information of the current AP 17 and the connection history information of the STA 103 to the target AP priority setting unit 214. The target AP priority setting method in the target AP priority setting means 214 is the same as that of the first embodiment, and the handover information providing server 2 stores the handover information 45 including the connection information of the target AP and the set priority. Transmit to the STA 103 via the current AP 17. The STA 103 that has received the handover information 45 can know the target AP candidates with priorities.

  Then, when the STA 103 needs to be handed over, the STA 103 attempts to establish a wireless connection using the connection information for the target AP candidate according to the obtained priority order, and performs the handover to the target AP that has established the wireless connection earliest. To do. At this time, the target AP having a high priority may be controlled so as to establish a wireless connection more reliably over time. Finally, the AP information of the current AP 17 is added to the connection history information holding unit 201 and held.

  In the first to third embodiments, an example in which a management frame defined in IEEE 802.11 is used for exchanging connection information. However, in this embodiment, a server on the network is used. An IP packet of an upper layer can be used instead of a specified frame.

1 is a diagram showing a first embodiment of a wireless LAN system to which the present invention is applied. The figure which shows the frame format of beacon 31,32,33. The figure which shows the example of a setting of the priority of a target AP. The flowchart which shows the setting process procedure of the priority order of a target AP. The figure which shows the example of a setting process of the priority of a target AP. The figure which shows 2nd Embodiment of the wireless LAN system to which this invention is applied. The figure which shows 3rd Embodiment of the wireless LAN system to which this invention is applied. The figure which shows 4th Embodiment of the wireless LAN system to which this invention is applied.

Explanation of symbols

1 Network 11, 12, 13, 14, 15, 16, 17, 18, 19 Radio base station apparatus (AP)
21, 22, 23, 24, 25, 26, 27 Target AP connection information 101, 102, 103 Wireless terminal equipment (STA)
201 Connection history information holding means 202, 211, 212, 213, 214 Target AP priority setting means

Claims (6)

In a handover method in which a wireless terminal device wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally performs a handover for switching a wireless base station device wirelessly connected with movement ,
When a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs,
The wireless base station device holds connection information necessary for the wireless terminal device to establish a wireless connection with the target AP, and notifies the wireless terminal device of the connection information,
The wireless terminal device
Receiving the connection information of the target AP broadcast from the current AP;
Holding the connection history information of the wireless base station device that was wirelessly connected before handing over to the current AP, and setting the priority to the target AP based on the connection history information;
When performing a handover, the wireless communication device sequentially tries to establish a wireless connection using the connection information of the target AP according to the priority order, and first performs a handover to the target AP that can establish the wireless connection.
A handover method comprising: adding information of a current AP that has been handed over to the connection history information. In a handover method in which a wireless terminal device wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally performs a handover for switching a wireless base station device wirelessly connected with movement ,
When a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs,
The wireless base station device holds connection information necessary for the wireless terminal device to establish a wireless connection with the target AP, and transmits connection information of the target AP in response to a request from the wireless terminal device,
The wireless terminal device
Requesting connection information of the target AP from the current AP, and receiving connection information of the target AP transmitted from the current AP in response to the request;
Holding the connection history information of the wireless base station device that was wirelessly connected before handing over to the current AP, and setting the priority to the target AP based on the connection history information;
When performing a handover, the wireless communication device sequentially tries to establish a wireless connection using the connection information of the target AP according to the priority order, and first performs a handover to the target AP that can establish the wireless connection.
A handover method comprising: adding information of a current AP that has been handed over to the connection history information. In the handover method according to claim 1 or 2 ,
A handover method characterized in that a time for attempting to establish a wireless connection using the connection information is set longer for the target AP with a higher priority than that for the target AP with a lower priority. In the handover method according to claim 1 or 2 ,
From the connection history information, a history of the direction of the movement path of the wireless terminal device is determined to estimate the movement direction of the wireless terminal device, and each direction of the target AP as viewed from the current AP is determined according to the connection information. A priority method is set for the target AP in each direction according to the estimation result of the moving direction of the wireless terminal device. A wireless terminal device that is wirelessly connected to one of a plurality of wireless base station devices arranged two-dimensionally or three-dimensionally and performs handover for switching the wireless base station device wirelessly connected with movement In
When a handover source radio base station apparatus is a current AP and a plurality of radio base station apparatuses that are candidates for a handover destination adjacent to the current AP are target APs,
Connection information acquisition means for acquiring connection information necessary for establishing a wireless connection with the target AP from the current AP;
Connection history information holding means for holding connection history information of a radio base station apparatus that is wirelessly connected before handover to the current AP, and further adding information of the current AP that has been handed over to the connection history information;
Target AP priority order setting means for setting a priority order for the target AP corresponding to the connection information acquired by the connection information acquisition means based on the connection history information, and when performing a handover, according to the priority order, A wireless terminal device characterized in that it establishes a wireless connection sequentially using the connection information of the target AP and performs handover to the target AP that can establish the wireless connection first. The wireless terminal device according to claim 5 ,
The connection information acquisition means receives the connection information of the target AP notified by the current AP or requests the connection information of the target AP from the current AP, and the target transmitted from the current AP in response to the request A wireless terminal device configured to receive AP connection information.

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