Wireless communication device and wireless communication method

Abstract

The invention relates to a wireless communication apparatus and a wireless communication method. [Problem] A WLAN system in which a more suitable BSS transfer threshold can be set. [Solution] Provided is a wireless communication device that functions as a WLAN access point, the wireless communication device comprising a control unit that dynamically sets, on the basis of information contained in a wireless signal from an external device, a threshold value to be used when a station belonging to a BSS of the wireless communication device attempts to shift to another BSS belonging to the same ESS as the aforementioned BSS.

Description

[0001] This application is a divisional application of the invention patent application with the application date of January 29, 2019, application number 201980017725.2, and invention name “Wireless Communication Device and Wireless Communication Method”. Technical Field

[0002] The present disclosure relates to a wireless communication device and a wireless communication method. Background Art

[0003] Wireless communication systems that perform communication between access points (hereinafter referred to as "APs" for convenience) and stations (hereinafter referred to as "STAs" for convenience) are known. For example, wireless local area networks (LANs) that employ carrier sense multiple access with collision avoidance (CSMA / CA) are widely known.

[0004] An AP in a wireless LAN defined in the IEEE 802.11 standard forms a cell (hereinafter referred to as a "basic service set (BSS)"), and STAs belong to the cell to receive services. An STA can transfer to another BSS belonging to the same network as the BSS to which the STA belongs (hereinafter referred to as an "extended service set (ESS)" for convenience).

[0005] Here, the AP controls the BSS transition of the STA by setting a threshold for determining transition to another BSS (hereinafter, may be referred to as a "BSS transition threshold" for convenience).

[0006] Reference List

[0007] Patent Literature

[0008] Patent Document 1: JP 2016-039445 A

[0009] Patent Document 2: JP 2011-160484 A Summary of the Invention

[0010] Technical issues

[0011] In this case, it may be difficult to set an appropriate BSS transfer threshold. For example, when multiple APs belonging to the same ESS are installed in a home environment or the like that cannot be supported by a service operator managing wireless LAN services, it is difficult to set an appropriate BSS transfer threshold for each AP.

[0012] Therefore, the present disclosure has been made in view of the above circumstances, and provides a new and improved wireless communication apparatus and wireless communication method capable of setting a more appropriate BSS transfer threshold in a wireless LAN system.

[0013] Solution to the problem

[0014] According to the present disclosure, there is provided a wireless communication device serving as an access point of a wireless LAN, the wireless communication device including:

[0015] a control unit configured to dynamically set a threshold used when a station belonging to a BSS of the present device transfers to another BSS belonging to the same ESS as the BSS based on information included in a wireless signal from an external device.

[0016] Furthermore, according to the present disclosure, there is provided a wireless communication method for implementing an access point function of a wireless LAN, the wireless communication method including:

[0017] dynamically setting a threshold used when a station belonging to a BSS of the present device attempts to transfer to another BSS belonging to the same ESS as the BSS based on information included in a wireless signal from an external device.

[0018] Furthermore, according to the present disclosure, there is provided a wireless communication device serving as a wireless LAN station, the wireless communication device including:

[0019] a control unit configured to control a transfer to another BSS belonging to the same ESS as the BSS to which the ESS belongs using a threshold dynamically set based on information included in a wireless signal from an external device and reception information on a wireless signal from an access point.

[0020] Furthermore, according to the present disclosure, there is provided a wireless communication method for implementing a station function of a wireless LAN station, the wireless communication method including:

[0021] controlling a transfer to another BSS belonging to the same ESS as the BSS to which the ESS belongs using a threshold dynamically set based on information included in a wireless signal from an external device and reception information on a wireless signal from an access point.

[0022] Advantageous Effects of the Invention

[0023] According to the present disclosure as described above, a more appropriate BSS transfer threshold can be set in a wireless LAN system.

[0024] It should be noted that the above effects are not necessarily limited, and together with or instead of the above effects, any effects described in this specification or other effects that can be understood from this specification may be exhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a system configuration diagram for describing the conventional technology.

[0026] Figure 2 is a sequence diagram showing an example of a process of processing of an AP and an STA at the time of conventional BSS transfer.

[0027] Figure 3 It is a diagram showing an example of the structure of an ESS report element defined in the IEEE 802.11ax standard.

[0028] Figure 4 It is a diagram showing an example of the structure of a reconnection request signal defined in the IEEE 802.11 standard.

[0029] Figure 5 It is a system structure diagram for describing the conventional technology.

[0030] Figure 6 It is a diagram showing an example of the structure of an ESS report element in a beacon signal transmitted from the AP 100 to each STA 200.

[0031] Figure 7 It is a diagram showing an example of the structure of a reconnection request signal transmitted from the STA 200 to the AP 100.

[0032] Figure 8 It is a block diagram showing an example of the device structure of the AP 100 and the STA 200.

[0033] Figure 9 It is a flowchart showing an example of the process of the STA 200.

[0034] Figure 10 It is a flowchart showing an example of the process of the STA 200 scanning the surrounding APs 100 as candidate connection destinations.

[0035] Figure 11 It is a flowchart showing an example of the process of the AP 100.

[0036] Figure 12 It is a sequence diagram showing an example of the process of the AP 100 and the STA 200.

[0037] Figure 13 It is a diagram showing a specific example of the process of the AP 100 and the STA 200.

[0038] Figure 14 It is a sequence diagram showing an example of the process of the AP 100 and the STA 200.

[0039] Figure 15 It is a diagram showing a specific example of the process of the AP 100 and the STA 200.

[0040] Figure 16It is a diagram showing an example of the structure of an ESS report element in a beacon signal transmitted from the AP 100 to each STA 200.

[0041] Figure 17 It is a flowchart showing an example of the process of the STA 200.

[0042] Figure 18 It is a flowchart showing an example of the process of the STA 200 scanning the surrounding APs 100 as candidate connection destinations.

[0043] Figure 19 It is a diagram showing a specific example of the processes of the AP 100 and the STA 200.

[0044] Figure 20 It is a sequence diagram showing an example of the process of communication processing between APs 100.

[0045] Figure 21 It is a flowchart showing an example of the process of adjusting the second threshold.

[0046] Figure 22 It is a diagram showing a specific example of the processes of the AP 100 and the STA 200.

[0047] Figure 23 It is a diagram showing an example of the structure of an ESS report element in a beacon signal transmitted from the AP 100 to each STA 200.

[0048] Figure 24 It is a block diagram showing an example of the schematic structure of a smart phone.

[0049] Figure 25 It is a block diagram showing an example of the schematic structure of a car navigation device.

[0050] Figure 26 It is a block diagram showing an example of the schematic structure of a radio access point. Detailed Description of the Embodiment

[0051] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the drawings, components having substantially the same functional structure will be denoted by the same reference numerals, and redundant descriptions thereof will be omitted.

[0052] It should be noted that the description will be made in the following order.

[0053] 1. Background

[0054] 1.1. Overview of the Background

[0055] 1.2. Prior Art

[0056] 2. First Embodiment

[0057] 2.1. Overview

[0058] 2.2. Example of Device Structure

[0059] 2.3. Processing Flow

[0060] 3. Second Embodiment

[0061] 4. Third Embodiment

[0062] 5. Fourth Embodiment

[0063] 6. Application Examples

[0064] 6.1. First Application Example

[0065] 6.2. Second Application Example

[0066] 6.3. Third Application Example

[0067] 7. Summary

[0068] <1. Background>

[0069] (1.1. Overview of the Background)

[0070] First, an overview of the background for the technology used to create the present disclosure will be described.

[0071] As described above, in a wireless LAN standardized by the IEEE 802.11 standard, a STA can transfer to another BSS belonging to the same ESS as the BSS to which the STA belongs. In standards prior to the IEEE 802.11ax standard, only the method of the AP commanding the STA was allowed for transfer between BSSs belonging to the same ESS. On the other hand, in the currently standardized IEEE 802.11ax standard, a mechanism is adopted in which ESS information, a BSS transfer threshold for determining transfer to another BSS, etc. are included in a wireless signal to allow the AP to notify the STA of this information. Therefore, the STA is expected to be able to determine by itself whether to transfer to another BSS by using this information.

[0072] Here, although adjustment of the BSS transfer threshold based on the surrounding environment is allowed in this standard, the specific adjustment method is not defined in this standard. Therefore, it is considered that a service operator managing a wireless LAN service adjusts the BSS transfer threshold for each AP based on the installation location of each AP or the coverage range of the BSS to be ensured.

[0073] For example, when multiple APs belonging to the same ESS are installed in a home environment or the like that cannot be supported by a service provider, it is considered difficult to set an appropriate BSS transition threshold for each AP. As a result, for example, the BSS transition threshold is set too low, and thus it becomes difficult for the STA to appropriately perform a transition to another BSS, or the BSS transition threshold is set too high, and thus there is a risk that the STA attempts to transition to another BSS and the scanning of the surrounding environment or the transmission of a reconnection request signal is repeated. Therefore, the AP needs to set a more appropriate BSS transition threshold without going through the service provider. In addition, when the position and on / off of the AP are frequently changed like a mobile router or the number of APs is changed, it is preferable to reset a more appropriate BSS transition threshold.

[0074] The above-mentioned Patent Document 1 discloses a technique for optimizing communication parameters by scanning the surrounding environment. However, when the communication environment may be changed, the time required to scan the surrounding environment becomes longer or the scanning frequency becomes higher, and thus the communication efficiency deteriorates. Therefore, preferably, the BSS transition threshold is set without scanning the surrounding environment as much as possible (or while reducing the time required for scanning).

[0075] In addition, Patent Document 2 discloses a technique for determining a transition to another BSS using multiple BSS transition thresholds. However, the method for setting the BSS transition threshold is not defined, and this technique cannot set a more appropriate BSS transition threshold according to the surrounding environment.

[0076] (1.2. Prior Art)

[0077] Next, the prior art related to the present disclosure will be described with reference to Figures 1 to 5 the following.

[0078] When describing the prior art, the system configuration as shown in Figure 1 is considered. More specifically, a wireless LAN system having two APs (AP1 and AP2 in the drawing) and four STAs (STA1 to STA4 in the drawing) in a home is considered.

[0079] An AP is such a wireless communication device that is connected to an external network and provides communication with the external network for the STA. For example, the AP is connected to the Internet and enables the STA to communicate with a device on the Internet or a device connected via the Internet.

[0080] The STA is a wireless communication device that communicates with the AP. The type of the STA is not particularly limited. For example, the STA can be a display with a display function, a memory with a storage function, a keyboard and a mouse with an input function, a speaker with a sound output function, and a smart phone with a function of performing advanced computational processing. Each STA can select the AP with the best communication quality, and as Figure 1 shown, STA2 and STA4 are connected to AP1, and STA1 and STA3 are connected to AP2.

[0081] Here, the processing procedures of the AP and the STA during the conventional BSS transition will be described with reference to Figure 2 . As a premise, it is assumed that: in step S100 in Figure 2 , STA1 belongs to the BSS formed by AP1 (different from the situation in Figure 1 ).

[0082] In Figure 2 , in step S100, STA1 receives a beacon signal from AP1 and acquires the ESS information and the BSS transition threshold in the ESS report element included in the beacon signal. Then, in step S104, STA1 determines whether to transfer to another BSS based on the information. More specifically, STA1 compares the received power of the beacon signal with the BSS transition threshold, and determines to transfer to another BSS when the received power of the beacon signal is equal to or lower than the BSS transition threshold.

[0083] In step S108, STA1 scans for another AP that belongs to the same ESS as AP1. In step S112, when one or two or more other APs that belong to the same ESS as AP1 are detected among the APs, STA1 determines the AP (AP2 in this example) with the highest received power of the beacon signal as the target of the reconnection request. In step S116, STA1 sends a reconnection request signal to AP2 determined as the target of the reconnection request. Different from the normal connection request signal, the reconnection request signal includes the address information (or identification information) of the AP (AP1 in this example) to which STA1 is currently connected.

[0084] As a result, the AP2 that has received the reconnection request signal identifies the AP1 to which STA1 is connected, and in step S120, obtains information about STA1 (e.g., authentication information, etc.) by communicating with AP1. Thereafter, in step S124, AP2 determines whether the reconnection of STA1 is possible based on the information about STA1, and in step S128, by sending a reconnection response signal including the determination result to STA1, a series of processes ends. In step S120, AP2 communicates with AP1 and obtains information about STA1, so that the BSS transition of STA1 can be achieved while greatly omitting the authentication process.

[0085] Here, a structural example of the ESS report element defined in the IEEE 802.11ax standard will be described with reference to Figure 3 As described above, it is assumed that: the ESS report element as shown in Figure 3 is included in the beacon signal sent from the AP, and thus, is notified to the STA connected to the AP.

[0086] As Figure 3 shown, the ESS report element includes an element ID, a length, an element ID extension, and ESS information, and the ESS information includes a planned ESS, the edge of the ESS, and a BSS transition threshold.

[0087] The "planned ESS" in the ESS report element is information indicating whether the AP configures the same ESS as another AP. More specifically, when the "planned ESS" is "1", the AP configures the same ESS as other APs. In the Figure 1 example of

[0088] , since AP1 and AP2 belong to the same ESS, the planned ESS is "1".

[0089] In addition, the "edge of the ESS" is information indicating that the AP is located at the far end of the ESS compared to another AP belonging to the same ESS. Since the "edge of the ESS" can be used to determine whether to transfer to another BSS but is not currently specified in the IEEE 802.11ax standard, the "edge of the ESS" will not be described in detail in this document.

[0089] In addition, as described above, the BSS transition threshold is a threshold used when the STA connected to the AP determines whether to transfer to another BSS. More specifically, when the received power of the beacon signal from the AP is equal to or lower than the BSS transition threshold, the STA determines to transfer to another BSS. The structure of the ESS report element is not limited to the Figure 3 example of

[0090] Next, a description will be given with reference to Figure 4Describe an example of the structure of a reconnection request signal defined in the IEEE 802.11 standard. As described above, different from a normal connection request signal, this signal includes address information about the AP to which the STA is currently connected (in the drawing, represented by "current connection destination AP address"). As a result, the AP that receives the reconnection request signal can obtain information about the STA from the AP to which the STA is currently connected (e.g., authentication information, etc.), so the authentication process can be greatly omitted.

[0091] Next, the problems in the prior art will be specifically described.

[0092] Various settings in the ESS are mainly made by service operators who manage the wireless LAN service. Therefore, it is assumed that the service operator (or predetermined control software, etc.) sets the BSS transition threshold included in the ESS report element for each AP based on the results of measuring radio waves, etc. As a result, as described above, when multiple APs belonging to the same ESS are installed in a home environment, etc. that the service operator cannot support, it is considered difficult to set a more appropriate BSS transition threshold for each AP. In addition, when the position, number, or on / off of the AP is frequently changed like a mobile router, it is preferable to reset a more appropriate BSS transition threshold, but in a home environment that the service operator cannot support, it is actually impossible to reset a more appropriate BSS transition threshold. Figure 3 For example, in

[0093] For example, in Figure 5 consider the situation where only AP1 initially covers all rooms, but at a certain time, AP2 is newly installed and the position of AP1 is moved. In Figure 5 the BSS formed by AP1 is "BSS1", and the range within which each STA attempts to maintain a connection in BSS1 is described as the "BSS1 connection maintenance range" (in other words, outside the BSS1 connection maintenance range, the received power of the beacon signal is equal to or lower than the first threshold, and the STA attempts to transfer to another BSS). In addition, the BSS formed by AP2 is called "BSS2", and the range within which each STA attempts to maintain a connection in BSS2 is represented by the "BSS2 connection maintenance range". At this time, preferably, STA1 present in Room 1 (represented by "Room 1" in the drawing) is connected to AP2 with a shorter distance and better communication quality. However, when the BSS transition threshold is set low enough to allow AP1 to cover all rooms, STA1 cannot determine the BSS transition by itself and will continue to be connected to AP1, and thus the communication quality is not improved.

[0094] In addition, STA3 present in Room 2 (represented by "Room 2" in the attached drawing) also attempts to connect to AP2 with a shorter distance and good communication quality. Here, if AP2 sets the BSS transition threshold relatively high, even if STA3 is connected to AP2, STA3 attempts to execute a reconnection request or the like for another AP because the received power of the beacon signal from AP2 is equal to or lower than the BSS transition threshold, and thus there is a possibility that wasted operations will be repeatedly generated.

[0095] In view of the above situation, the applicant of this case has created the technology according to the present disclosure. Hereinafter, each embodiment according to the present disclosure will be sequentially described.

[0096] <2. First Embodiment>

[0097] As described above, the background of the technology of the present disclosure has been described. Next, the first embodiment of the present disclosure will be described.

[0098] (2.1. Overview)

[0099] First, the overview of this embodiment will be described.

[0100] AP 100 according to this embodiment sets two types of BSS transition thresholds, such as a "first threshold" and a "second threshold". Here, the first threshold is similar to the above-mentioned conventional BSS transition threshold. More specifically, the first threshold is a threshold for comparison with the received power of the beacon signal from this device (or propagation loss information, etc.). The second threshold is a threshold for comparison with the difference between the received power of the beacon signal from this device and the received power of the beacon signal from another AP (or the difference in propagation loss information, etc.). By setting not only the first threshold but also the second threshold, STA 200 is facilitated to transfer to a BSS with higher communication quality. Details of the method of using these thresholds will be described below.

[0101] Here, reference will be made to Figure 6 to describe an example of the structure of the ESS report element in the beacon signal sent from AP 100 to each STA 200 in this embodiment. As Figure 6 shown, in the ESS information of the ESS report element, AP 100 notifies each STA 200 of these thresholds by setting the first threshold and the second threshold at a later stage of "the edge of the ESS". It should be noted that the structure of the ESS report element according to this embodiment is not limited to the Figure 6 example. For example, the data positions for providing the first threshold and the second threshold can be changed as needed.

[0102] Next, reference will be made to Figure 7Describe an example of the structure of a reconnection request signal sent from the STA 200 to the AP 100 according to this embodiment. As Figure 7 shown, different from the conventional reconnection request signal (see Figure 4 ), the STA 200 includes, in the reconnection request signal, information on the reception power information of the beacon signal received from the AP 100 to which the STA 200 is currently connected (hereinafter, may be referred to as "current AP reception power information" for convenience). As a result, the AP 100 currently connected to the STA 200 receives the reconnection request signal sent from the affiliated STA 200 to another AP 100, and thus, the first threshold can be dynamically adjusted based on the current AP reception power information included in the reconnection request signal. Details of the process of adjusting the first threshold will be described below. Note that the structure of the reconnection request signal according to this embodiment is not limited to Figure 7 the example. For example, the data position providing the current AP reception power information may be changed as needed.

[0103] (2.2. Example of device structure)

[0104] The overview of this embodiment has been described above. Next, an example of the structure of each device according to this embodiment will be described with reference to Figure 8 . Hereinafter, an example of the device structure of the AP 100 will be mainly described, but since the AP 100 and the STA 200 can basically have similar functions, each of the structural examples described below can be regarded as the STA 200.

[0105] As Figure 8 shown, the AP 100 according to this embodiment includes a data processing unit 110, a control unit 120, a storage unit 130, a transmission unit 140, an antenna sharing unit 150, an antenna 160, and a reception unit 170.

[0106] (Data processing unit 110)

[0107] During transmission, the data processing unit 110 generates a packet for transmission by using the transmission target data input from the upper layer, generates transmission data by performing processes (such as adding a MAC header for media access control (MAC) and adding an error detection code to the packet), and provides the transmission data to the analog signal conversion unit 141. In addition, during reception, the reception target data is extracted by performing processes (such as analyzing the MAC header and detecting errors in the frame) on the reception data provided from the digital signal conversion unit 172.

[0108] (Control unit 120)

[0109] The control unit 120 controls each component in the AP 100 as a whole. More specifically, the control unit 120 performs settings of parameters (such as coding schemes, modulation schemes, transmission powers, etc.) for the processing of each component in the AP 100, scheduling of the processing, and the like. In addition, in the present embodiment, the control unit 120 sets a first threshold and a second threshold, and controls the generation process and transmission process of beacon signals including these thresholds in the ESS report element as a whole. In addition, the control unit 120 dynamically sets the first threshold based on the current AP reception power information included in the reconnection request signal from the affiliated STA 200. In addition, the control unit 120 also determines whether the reconnection of the STA 200 that is the transmission source of the reconnection request signal is possible.

[0110] In addition, the control unit 220 of the STA 200 controls the connection process to the AP 100 based on the reception information (such as reception power information, propagation loss information, etc.) of the beacon signal from the AP 100, the first threshold, and the second threshold. It should be noted that the processing of the control unit 120 of the AP 100 and the control unit 220 of the STA 200 is not limited to this.

[0111] (Storage unit 130)

[0112] The storage unit 130 is configured to store various types of information. For example, the storage unit 130 stores programs, parameters, etc. for the processing of each component. In addition, in the present embodiment, the storage unit 130 can store the first threshold and the second threshold set by the control unit 120. In addition, the storage unit 230 of the STA 200 can store the information (such as BSSID, etc.) included in the beacon signal from the AP 100 and the reception information of the beacon signal (such as reception power information, propagation loss information, etc.). It should be noted that the information stored in the storage unit 130 of the AP 100 and the storage unit 230 of the STA 200 is not limited to this.

[0113] (Transmission unit 140)

[0114] The transmission unit 140 is configured to generate a transmission signal transmitted from the antenna 160 by using the transmission data generated by the data processing unit 110. As Figure 8 shown, the transmission unit 140 includes an analog signal conversion unit 141 and an RF transmission unit 142.

[0115] (Analog signal conversion unit 141)

[0116] The analog signal conversion unit 141 is configured to convert the transmission data generated by the data processing unit 110 into an analog signal. More specifically, the analog signal conversion unit 141 generates an analog signal by performing encoding, interleaving, modulation, etc. on the transmission data generated by the data processing unit 110 based on the encoding scheme and modulation scheme set by the control unit 120, and provides the analog signal to the RF transmission unit 142.

[0117] (RF transmission unit 142)

[0118] The RF transmission unit 142 is configured to perform frequency conversion and power amplification of the analog signal generated by the analog signal conversion unit 141. More specifically, the RF transmission unit 142 generates a transmission signal to be transmitted from the antenna 160 by performing filtering processing, up-conversion processing to the carrier frequency band, amplification processing to a predetermined power, etc. on the analog signal generated by the analog signal conversion unit 141.

[0119] (Antenna sharing unit 150, antenna 160)

[0120] During transmission, the antenna sharing unit 150 is configured to transmit the transmission signal generated by the transmission unit 140 as an electromagnetic wave via the antenna 160. Additionally, during reception, the antenna sharing unit 150 provides the electromagnetic wave received via the antenna 160 to the reception unit 170 as a reception signal. The antenna 160 may be a chip antenna (an antenna formed by wiring on a printed circuit board) or an antenna formed by using a linear conductor element.

[0121] (Reception unit 170)

[0122] The reception unit 170 is configured to obtain reception data from the reception signal provided by the antenna sharing unit 150. As Figure 8 shown, the reception unit 170 includes an RF reception unit 171 and a digital signal conversion unit 172.

[0123] (RF reception unit 171)

[0124] The RF reception unit 171 is configured to perform frequency conversion and power amplification on the reception signal input from the antenna sharing unit 150. More specifically, the RF reception unit 171 outputs an analog signal by performing amplification processing to a predetermined power, down-conversion processing, filtering processing, etc. on the reception signal input from the antenna sharing unit 150. The RF reception unit 171 may use a low-noise amplifier (LNA) or an automatic gain control (AGC) circuit to perform the processing.

[0125] (Digital signal conversion unit 172)

[0126] The digital signal conversion unit 172 is configured to convert the analog signal output by the RF receiving unit 171 into a digital signal. More specifically, the digital signal conversion unit 172 demodulates, deinterleaves, and decodes the analog signal output by the RF receiving unit 171 based on the decoding scheme and demodulation scheme set by the control unit 120 to obtain received data, and provides the received data to the data processing unit 110.

[0127] The structural examples of each device according to the present embodiment have been described above. It should be noted that the structures described above with reference to Figure 8 are merely examples, and the structures of the AP 100 and the STA 200 are not limited to this example. In addition, the structures of the AP 100 and the STA 200 can be flexibly modified according to specifications and operations.

[0128] (2.3. Process flow)

[0129] The structural examples of each device according to the present embodiment have been described above. Next, examples of the process flows of the AP 100 and the STA 200 according to the present embodiment will be described.

[0130] (Process flow of the STA 200)

[0131] First, an example of the process flow of the STA 200 will be described with reference to Figure 9 the description.

[0132] In step S1000, the STA 200 receives a beacon signal from any AP 100. Then, the STA 200 confirms the transmission source by analyzing the beacon signal. When the beacon signal is sent from the AP 100 to which the STA 200 is connected (hereinafter, referred to as the "current connection destination AP 100" for convenience) (step S1004 / "Yes"), in step S1008, the STA 200 compares the first threshold included in the ESS report element of the beacon signal with the received power of the beacon signal. When the received power of the beacon signal is greater than the first threshold (step S1008 / "Yes"), the STA 200 maintains the connection to the AP 100 without transferring to another BSS. At this time, the STA 200 stores the received power information of the beacon signal in the storage unit 230 in step S1012 (updates the received power information when the received power information is pre-stored), and as a result, can perform various processes during the period when a beacon signal is received from another AP 100, which will be described later.

[0133] In step S1008, when the received power of the beacon signal is equal to or lower than the first threshold (step S1008 / "No"), in step S1016, STA 200 attempts to transfer to another BSS and scans the surrounding APs 100 that are candidate connection destinations (hereinafter, referred to as "candidate connection destination APs 100" for convenience). The details of the scanning process of the candidate connection destination APs 100 will be described later. When STA 200 successfully detects a candidate connection destination AP 100 (step S1020 / "Yes"), in step S1024, STA 200 ends this process by sending a reconnection request signal to the best candidate connection destination AP 100.

[0134] In step S1020, when STA 200 fails to detect a candidate connection destination AP 100 (step S1020 / "No"), in step S1028, STA 200 ends this process by sending a reconnection request signal to the current connection destination AP 100.

[0135] In step S1004, when the beacon signal received by STA 200 is sent from an AP 100 other than the current connection destination AP 100 (step S1004 / "No"), STA 200 confirms whether the beacon signal is sent from an AP 100 belonging to the same ESS. When the beacon signal is sent from an AP 100 belonging to the same ESS (step S1032 / "Yes"), in step S1036, STA 200 calculates the difference between the received power of this beacon signal and the received power of the beacon signal from the current connection destination AP 100 stored in the storage unit 230 (in the drawings, represented by "current AP beacon received power" for convenience).

[0136] In step S1040, STA 200 compares the second threshold included in the ESS report element of the beacon signal from the current connection destination AP 100 with the difference as the calculation result. When the difference as the calculation result is greater than the second threshold (step S1040 / "Yes"), in step S1044, STA 200 ends this process by sending a reconnection request signal to the AP 100 that is the source of the beacon signal (in the drawings, represented by "beacon source AP" for convenience) in order to attempt to execute another BSS.

[0137] When the beacon signal received by the STA 200 in step S1032 is not transmitted by the AP 100 belonging to the same ESS (step S1032 / "No"), the process ends without BSS transition. Further, in step S1040, even when the calculated difference is equal to or lower than the second threshold (step S1040 / "No"), the process similarly ends without performing BSS transition.

[0138] Here, details of the process of scanning the surrounding APs 100 as candidate connection destinations in step S1016 in Figure 10 will be described for the STA 200 to attempt to transfer to another BSS. Figure 9

[0139] In Figure 10 step S1100, the STA 200 starts scanning the surrounding APs 100 as candidate connection destinations. When the STA 200 receives a beacon signal from any AP 100 before the predetermined scan time has elapsed (step S1104 / "No") (step S1108 / "Yes"), the STA 200 confirms the transmission source of the beacon signal. When the transmission source of the beacon signal is an AP 100 other than the current connection destination AP 100 belonging to the same ESS (step S1112 / "Yes"), the STA 200 compares the received power of the beacon signal with the received power of the beacon signal from the current connection destination AP 100 stored in the storage unit 230. When the received power of the beacon signal is greater than the received power of the beacon signal from the current connection destination AP 100 (step S1116 / "Yes"), in step S1120, the STA 200 sets the transmission source of the beacon signal as the connection destination candidate AP 100, and stores the information included in the beacon signal (e.g., BSSID, etc.) and the reception information (e.g., received power information, propagation loss information, etc.) in the storage unit 230. The STA 200 continues to execute the processes of steps S1104 to S1120 above until the predetermined scan time has elapsed.

[0140] When the predetermined scan time has passed (step S1104 / "Yes"), the STA 200 ends the scan of the surrounding APs 100 in step S1124. When one or more candidate APs 100 for the connection destination are detected (step S1128 / "Yes"), in step S1132, the STA 200 successfully detects the candidate AP 100 for the connection destination, and determines the best connection destination by using the information stored in the storage unit 230 (for example, the information included in the beacon signal, the reception information of the beacon signal, etc.) to end the process. On the other hand, when the candidate AP 100 for the connection destination is not detected (step S1128 / "No"), in step S1136, the STA 200 ends the process by determining that the detection of the candidate AP 100 for the connection destination has failed. It should be noted that the processes after steps S1132 and S1136 are as described with reference to Figure 9 as described above. Additionally, in the example of Figure 10 , the scan of the surrounding APs 100 is continuously performed until the predetermined scan time has passed, but when an AP 100 is successfully detected, the STA 200 may end the scan of the surrounding APs 100.

[0141] (Flow of the process of the AP 100)

[0142] Next, an example of the flow of the process of the AP 100 will be described with reference to Figure 11 as follows.

[0143] In step S1200, the AP 100 receives a reconnection request signal from any STA 200. Then, the AP 100 confirms the destination of the signal by analyzing the reconnection request signal. When the destination of the reconnection request signal is this device (step S1204 / "Yes"), in step S1208, the AP 100 determines whether reconnection of the STA 200 is possible, and sends a reconnection response signal including the determination result to the STA 200. On the other hand, when the destination of the reconnection request signal is not this device (step S1204 / "No"), the AP 100 does not send a reconnection response signal.

[0144] Next, the AP 100 confirms the source of the signal by analyzing the reconnection request signal. When the source of the signal is the STA 200 attached to this device (step S1212 / "Yes"), in step S1216, the AP 100 ends the process by adjusting the first threshold based on the current AP reception power information included in the reconnection request signal (see Figure 7 ). On the other hand, when the source of the signal is not the STA 200 attached to this device (step S1212 / "No"), the AP 100 ends the process without adjusting the first threshold.

[0145] (Specific example of the process of processing of AP 100 and STA 200)

[0146] Next, with reference to Figures 12 to 15 a specific example of the process of processing of AP 100 and STA 200 will be described.

[0147] First, with reference to Figure 12 and 13 a situation will be described where STA 200a transfers the connection destination from AP 100a to AP 100b. Figure 12 is a sequence diagram showing a series of processes for BSS transfer for STA 200a. It should be noted that in Figure 13 , the BSS formed by AP 100a is represented by "BSS10a", and the range where each STA 200 attempts to maintain a connection in BSS10a is represented by "BSS10a connection maintenance range". In addition, the BSS formed by AP 100b is represented by "BSS10b", and the range where each STA 200 attempts to maintain a connection in BSS10b is represented by "BSS10b connection maintenance range".

[0148] When STA 200a receives a beacon signal from AP 100b belonging to the same ESS in step S1300 in Figure 12 , in step S1304, STA 200a determines whether to perform BSS transfer. For example, as shown in Figure 13 , it is assumed that: the received power of the beacon signal from AP 100a to which STA200a is connected is -70 [dBm], and the received power of the beacon signal from AP 100b is -50 [dBm]. In addition, it is assumed that: the first and second thresholds of AP 100a are -80 [dBm] and 10 [dBm] respectively, and the first and second thresholds of AP 100b are -50 [dBm] and 10 [dBm].

[0149] In this case, since the received power of the beacon signal from the connected AP 100a (-70 [dBm]) is greater than the first threshold of AP 100a (-80 [dBm]), according to the prior art, STA 200a cannot perform BSS transfer by its own determination and maintain the connection to AP 100a. On the other hand, in this embodiment, since the difference between the received power of the beacon signal from AP 100a and the received power of the beacon signal from AP 100b is 20 [dBm] and is greater than the second threshold (10 [dBm]) set by AP 100a, STA 200a can determine to perform BSS transfer.

[0150] Then, in Figure 12 step S1308 in , STA 200a sends a reconnection request signal to AP 100b. Here, it is assumed that the reconnection request signal sent by STA 200a is also received by AP 100a. As a result, AP 100b that has received the reconnection request signal identifies AP 100a to which STA 200a is connected, and in step S1312, obtains information about STA 200a (e.g., authentication information, etc.) by communicating with AP100a.

[0151] Then, AP 100a obtains the current AP received power information included in the reconnection request signal in step S1316 by receiving the reconnection request signal addressed to AP 100b sent from the affiliated STA 200a in the above processing, and can use this information to determine whether to adjust the first threshold. For example, as Figure 13 shown in , since the current AP received power information is greater than the first threshold set by AP 100a, AP 100a determines that the set first threshold is too low and adjusts the first threshold to the same value as the current AP received power information (-70 [dBm]). As a result, as Figure 13 shown in , the BSS10a connection holding range is reduced.

[0152] Thereafter, AP 100b determines in Figure 12 step S1320 in whether the reconnection of STA 200a is possible based on the information about STA 200a, and in step S1324, ends a series of processes by sending a reconnection response signal including the determination result to STA 200a. In this way, STA 200a can transfer to BSS10b with a better reception environment by allowing AP 100a to set the second threshold, and AP 100a can adjust the first threshold to a more appropriate value based on the current AP received power information included in the reconnection request signal.

[0153] It should be noted that the above processing is only an example, and the processing of each device can be changed as needed. For example, AP 100a may set the value obtained by performing a predetermined calculation using the current AP received power information as the first threshold, rather than setting the same value as the current AP received power information (-70 [dBm]) as the first threshold. Additionally, the second threshold may be a threshold for comparison with the ratio of these received powers rather than the difference in the received powers of beacon signals from different APs 100.

[0154] Next, reference will be made to Figure 14 and 15Describe the situation where AP 100b adjusts the first threshold. Here, assume that before the process of step S1400 in Figure 14 is executed, STA 200c is connected to AP 100b.

[0155] When STA 200c receives a beacon signal from the connected AP 100b in step S1400, STA 200c determines whether to transfer the BSS in step S1404. For example, as shown in Figure 15 , assume that the received power of the beacon signal from AP 100b to which STA 200c is connected is -60 [dBm], and the received power of the beacon signal from AP 100a is -90 [dBm]. Additionally, assume that the first threshold and the second threshold of AP 100b are -50 [dBm] and 10 [dBm] respectively.

[0156] In this case, the received power of the beacon signal from the connected AP 100b (-60 [dBm]) is less than the first threshold of AP100b (-50 [dBm]), so STA 200c determines to perform BSS transfer. Then, in step S1408 in Figure 14 , STA 200c scans the surrounding APs 100 as candidate connection destinations to attempt to transfer to another BSS, but cannot detect another AP 100 with a received power of the beacon signal higher than that of the beacon signal of AP 100b. Therefore, STA 200c determines AP 100b as the target for the reconnection request in step S1412, and sends a reconnection request signal to AP 100b in step S1416. Then, AP 100b determines that the reconnection of STA 200c is possible in step S1420, and sends a reconnection response signal including the determination result to STA 200c in step S1424. As a result, the connection between STA200c and AP 100b is maintained.

[0157] However, since the received power of the beacon signal from the connected AP 100b (-60 [dBm]) is still less than the first threshold of AP100b (-50 [dBm]), according to the prior art, STA 200c determines to perform BSS transfer again, and the processes of steps S1408 to S1424 are repeated.

[0158] On the other hand, in this embodiment, AP 100b obtains the current AP received power information included in the reconnection request signal in step S1428 based on the fact that the reconnection request signal is received from the affiliated STA 200c, and determines whether it is necessary to adjust its own first threshold. More specifically, as shown in Figure 15As shown in the figure, since the current AP reception power information (-60 [dBm]) included in the reconnection request signal from STA 200c is equal to or lower than the first threshold (-50 [dBm]) of AP 100b, AP 100b determines that the set first threshold is too high and adjusts the first threshold to a lower value using the current AP reception power information. For example, AP 100b sets a value (-65 [dBm]) that is a predetermined value lower than the current AP reception power information (-60 [dBm]) as the first threshold. As a result, as shown in Figure 15 the BSS10b connection holding range becomes large, and STA200c is located within the BSS10b connection holding range, so the BSS transfer process of STA 200c is not repeated. In this way, AP100b can adjust its own first threshold to a more appropriate value by receiving a reconnection request signal including the current AP reception power information from the affiliated STA 200c.

[0159] Note that the above processing is only an example, and the processing of each device can be changed as needed. For example, AP 100b can adjust the first threshold only when the number (or frequency, etc.) of reconnection request signals received from the affiliated STA 200c exceeds a predetermined value. As a result, AP 100b can stabilize the first threshold.

[0160] <3. Second Embodiment>

[0161] The first embodiment of the present disclosure has been described above. Next, the second embodiment of the present disclosure will be described.

[0162] Although the method of adjusting the first threshold has been described in the first embodiment, there are APs 100 that do not want to cover a wide range according to the product. For such APs 100, the first threshold cannot be easily decreased because the coverage area is restricted. Therefore, the AP 100 according to the second embodiment sets the minimum value of the first threshold, and STA 200 uses the minimum value to determine whether BSS transfer is possible.

[0163] First, a structural example of the ESS report element according to the present embodiment will be described with reference to Figure 16 As shown in <{ Figure 16 the AP 100 according to the present embodiment notifies the minimum value of the first threshold to STA 200 by setting the minimum value of the first threshold at a later stage of the second threshold in the ESS information on the ESS report element. Note that other elements are the same as the ESS report element according to the first embodiment (see Figure 6 ). In addition, the structure of the ESS report element according to the present embodiment is not limited to Figure 16Example. For example, the data position setting the minimum value of the first threshold can be changed as needed.

[0164] Next, a flow example of the processing of the STA 200 according to the present embodiment will be described with reference to Figure 17 The difference from the flow example of the processing of the STA 200 according to the first embodiment (see Figure 9 ) is that when the STA 200 receives a beacon signal from another AP 100 belonging to the same ESS (step S1532 / "Yes"), it is determined in step S1536 whether the received power of the beacon signal is greater than the minimum value of the first threshold included in the ESS report element of the beacon signal. When the received power of the beacon signal is greater than the minimum value of the first threshold (step S1536 / "Yes"), similar to the first embodiment, the STA 200 sends a reconnection request signal or the like to the AP 100 that is the transmission source of the beacon signal by performing the processing after step S1540.

[0165] Next, in Figure 17 step S1516, details of the processing of scanning surrounding APs 100 as candidate connection destinations so that the STA 200 attempts to transfer to another BSS will be described with reference to Figure 18 The difference from the first embodiment (see Figure 10 ) is that when the STA 200 receives a beacon signal from any AP 100 by scanning (step S1608 / "Yes"), it is determined in step S1620 whether the received power of the beacon signal is greater than the minimum value of the first threshold. When the received power of the beacon signal is greater than the minimum value of the first threshold (step S1620 / "Yes"), similar to the first embodiment, the STA 200 regards the transmission source of the beacon signal as a candidate connection destination AP 100 in step S1624. It should be noted that in step S1620, the minimum value of the first threshold is obtained from the ESS report element in the beacon signal received by the STA 200 as described above.

[0166] Next, a specific example of the processing in such a case will be described with reference to Figure 19 where the STA200d connected to the AP 100a receives a beacon signal from the AP 100b. As Figure 19As shown in the figure, assume that: the received power of the beacon signal from AP 100a to which STA 200d is connected is -80 [dBm], and the received power of the beacon signal from AP 100b is -65 [dBm]. Additionally, assume that: the first threshold, the second threshold, and the minimum value of the first threshold of AP 100a are -80 [dBm], 10 [dBm], and -90 [dBm] respectively, and the first threshold, the second threshold, and the minimum value of the first threshold of AP 100b are -60 [dBm], 10 [dBm], and -60 [dBm] respectively.

[0167] In this case, the difference between the received power of the beacon signal from AP 100a (-80 [dBm]) and the received power of the beacon signal from AP 100b (-65 [dBm]) is 15 [dBm], and it is greater than the second threshold (10 [dBm]) set by AP 100a. Therefore, in the first embodiment, STA 200d sends a reconnection request signal to AP 100b. On the other hand, in this embodiment, STA 200d compares the minimum value of the first threshold notified by AP 100b with the received power of the beacon signal before comparing the difference in received power with the second threshold (see Figure 17 step S1536 in the figure). In this case, since the received power of the beacon signal from AP 100b (-65 [dBm]) is equal to or lower than the minimum value of the first threshold (-60 [dBm]) notified by AP 100b, STA 200d determines that AP 100b cannot extend the BSS10b connection holding range to the location of this device. Therefore, STA 200d abandons the transfer to AP 100b and continues to be connected to AP 100a. As described above, according to the AP 100b of this embodiment, by setting the minimum value of the first threshold, it can prevent the BSS10b connection holding range from extending beyond its own capabilities.

[0168] It should be noted that the above processing is only an example, and the processing of each device can be changed as needed. For example, AP 100b can set the minimum value of the first threshold to a fixed value or a variable value that can be dynamically changed. More specifically, when AP 100b is a device capable of dynamically controlling the transmission power, AP 100b can change the minimum value of the first threshold according to the transmission power. Additionally, AP 100b can control the BSS transfer of STA 200d by providing the maximum value of the first threshold instead of the minimum value of the first threshold.

[0169] <4. Third Embodiment>

[0170] The second embodiment of the present disclosure has been described above. Next, the third embodiment of the present disclosure will be described.

[0171] In the first and second embodiments, methods for adjusting the first threshold have been mainly described. On the other hand, the second threshold may be a fixed value defined for each product, or may be a variable value that can be dynamically changed according to the communication environment. Therefore, in the third embodiment, an example of such a case where the AP 100 adjusts the second threshold will be described. For example, the AP 100 may dynamically adjust the second threshold according to the communication state (e.g., channel utilization rate) of another AP 100 belonging to the same ESS. Here, the channel utilization rate is assumed to be the rate of the time actually performing communication during a predetermined measurement time, but is not limited thereto.

[0172] First, reference will be made to Figure 20 to describe an example of the communication process between the APs 100 of this embodiment. For example, the APs 100a and 100b transmit beacon signals including channel utilization rate information to each other in steps S1700 and S1708 to determine whether to adjust their second thresholds according to the channel utilization rate information included in the received beacon signals in steps S1704 and S1712. When the APs 100a and 100b are not within the range where the APs 100a and 100b can receive each other's beacon signals, the AP 100 can perform communication via an external device (such as the STA 200) that can receive both signals. The APs 100a and 100b can share channel utilization rate information, etc. with each other via wireless signals or wired communication other than beacon signals.

[0173] Next, reference will be made to Figure 21 to describe an example of the process of the AP 100 adjusting the second threshold. In step S1800 in Figure 21 , the AP 100 obtains the channel utilization rate information included in the beacon signal from another AP 100. Then, the AP 100 calculates the difference between the channel utilization rate of another AP 100 and its own channel utilization rate in step S1804, and adjusts its own second threshold based on the calculation result in step S1808. For example, when the channel utilization rate of another AP 100 is higher than that of the AP 100, the AP 100 may adjust its own second threshold to a higher value to suppress the STA 200 from transferring to the BSS formed by another AP 100. Additionally, conversely, when the channel utilization rate of another AP 100 is equal to or lower than the channel utilization rate of the AP 100, the AP 100 may adjust its own second threshold to a lower value to promote the STA 200 to transfer to the BSS formed by another AP 100.

[0174] Next, reference will be made to Figure 22 to describe a specific example of such a case where the APs 100a and 100b adjust the second threshold. AsFigure 22 As shown in the figure, assume that the second threshold and channel utilization rate of AP 100a are 5 [dBm] and 90 [%] respectively, and the second threshold and channel utilization rate of AP100b are 5 [dBm] and 40 [%] respectively. AP 100a and AP 100b identify the channel utilization rate of the other party by transmitting beacon signals including channel utilization rate information to each other. In this case, since AP 100b has a higher channel utilization rate than that of AP 100a, AP 100a adjusts the second threshold to a higher value (for example, 10 [dBm]) to prevent STA 200 from transferring to BSS10b formed by AP 100b. On the other hand, AP 100b adjusts the second threshold to a lower value (for example, 0 [dBm]) to promote the transfer of STA 200 to BSS10a formed by AP 100a. As a result, each STA 200 can transfer to a more suitable BSS according to the channel utilization rate of each AP 100.

[0175] It should be noted that the above processing is only an example, and the processing of each device can be changed as needed. For example, AP 100 can adjust the second threshold based on information other than the channel utilization rate (for example, the number of associated STAs 200), as long as the information indicates the degree of congestion of the communication of each BSS. In addition, the set value of the second threshold can be determined by any method. For example, AP 100 can set the value obtained by performing a predetermined calculation using the difference in channel utilization rate from another AP 100 as the second threshold.

[0176] <5. Fourth Embodiment>

[0177] The third embodiment of the present disclosure has been described above. Next, the fourth embodiment of the present disclosure will be described.

[0178] The AP 100 according to the fourth embodiment stores the second threshold corresponding to each BSSID in the ESS report element. More specifically, as Figure 23 shown, AP 100 provides an arbitrary pair of BSSIDs and the second threshold corresponding to the BSSID at a stage subsequent to the first threshold in the ESS report element.

[0179] Then, in Figure 9 step S1040 in or Figure 17 step S1544 in, when the difference in received power between the currently connected destination AP 100 and another AP 100 is compared with the second threshold, the STA 200 that receives the ESS report element can use the second threshold according to the BSS formed by the other AP 100 instead of using a unified second threshold. In addition, in FigureIn step S1808, when adjusting the second threshold based on the difference in channel utilization rate between this device and another AP 100, AP100 can adjust the second threshold corresponding to the BSS formed by another AP 100. In this way, AP 100 can more finely control the BSS transition of STA 200 by managing the second threshold for each BSSID (in other words, for each BSS). It should be noted that the processing and the structure of the ESS report element according to this embodiment are not limited to those described above.

[0180] <6. Application Example>

[0181] The technology according to the present disclosure can be applied to various products. For example, STA 200 can be implemented as a mobile terminal (such as a smart phone, a tablet personal computer (PC), a notebook PC, a portable game terminal, or a digital camera), a fixed terminal (such as a television receiver, a printer, a digital scanner, or a network storage device), or a vehicle-mounted terminal (such as a car navigation device). Additionally, STA 200 is implemented as a terminal that performs machine-to-machine (M2M) communication (also referred to as a machine type communication (MTC) terminal), such as a smart meter, a vending machine, a remote monitoring device, or a point of sale (POS) terminal. Additionally, STA 200 can be a wireless communication module (e.g., an integrated circuit module constructed from a single die) installed on these terminals.

[0182] On the other hand, for example, AP 100 can be implemented as a wireless LAN access point (also referred to as a wireless base station) with or without a router function. Additionally, AP 100 can be implemented as a mobile wireless LAN router. Additionally, AP100 can be a wireless communication module (e.g., an integrated circuit module constructed from a single die) installed on these devices.

[0183] (6.1. First Application Example)

[0184] ​ is a block diagram showing an example of the schematic structure of a smart phone 900 to which the technology according to the present disclosure can be applied. The smart phone 900 includes a processor 901, a memory 902, a storage device 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, a display device 910, a speaker 911, a wireless communication interface 913, an antenna switch 914, an antenna 915, a bus 917, a battery 918, and an auxiliary controller 919.

[0185] The processor 901 can be, for example, a central processing unit (CPU) or a system on a chip (SoC), and controls the functions of the application layer and other layers of the smart phone 900. The memory 902 includes a random access memory (RAM) and a read-only memory (ROM), and stores programs and data executed by the processor 901. The memory 903 may include a storage medium such as a semiconductor memory or a hard disk. The external connection interface 904 is an interface that connects an external device (such as a memory card or a universal serial bus (USB) device) to the smart phone 900.

[0186] The camera 906 has an imaging element (such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS)), and generates a captured image. The sensor 907 may include a set of sensors such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor. The microphone 908 converts the audio input to the smart phone 900 into an audio signal. The input device 909 includes, for example, a touch sensor that detects a touch on the screen of the display device 910, a keypad, a keyboard, buttons, switches, etc., and receives an operation or information input from the user. The display device 910 has a screen (such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display), and displays an output image of the smart phone 900. The speaker 911 converts the audio signal output from the smart phone 900 into audio.

[0187] The wireless communication interface 913 supports one or more wireless LAN standards (such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, and 11ax) and performs wireless communication. The wireless communication interface 913 can communicate with other devices via a wireless LAN access point in infrastructure mode. Additionally, the wireless communication interface 913 can directly communicate with another device in ad hoc mode or direct communication mode (such as Wi-Fi Direct (registered trademark)). It should be noted that in Wi-Fi Direct, different from ad hoc mode, one of the two terminals serves as an access point, but communication is directly performed between these terminals. The wireless communication interface 913 generally can include a baseband processor, radio frequency (RF) circuitry, a power amplifier, etc. The wireless communication interface 913 can be a single-chip module in which a memory storing a communication control program, a processor executing the program, and related circuitry are integrated. In addition to wireless LAN solutions, the wireless communication interface 913 can also support other types of wireless communication solutions, such as short-range wireless communication solutions, proximity wireless communication solutions, and cellular communication solutions. The antenna switch 914 switches the connection destination of the antenna 915 among a plurality of circuits included in the wireless communication interface 913 (for example, circuits for different wireless communication solutions). Each antenna 915 has a single or multiple antenna elements (for example, multiple antenna elements forming a MIMO antenna) and is used to transmit and receive wireless signals through the wireless communication interface 913.

[0188] It should be noted that the smart phone 900 is not limited to ​ the examples, and may include multiple antennas (for example, an antenna for wireless LAN and an antenna for a proximity wireless transmission solution). In this case, the antenna switch 914 can be omitted from the structure of the smart phone 900.

[0189] The bus 917 connects the processor 901, the memory 902, the storage device 903, the external connection interface 904, the camera 906, the sensor 907, the microphone 908, the input device 909, the display device 910, the speaker 911, the wireless communication interface 913, and the auxiliary controller 919 to each other. The battery 918 supplies power to ​ each block of the smart phone 900 shown in

[0190] In ​In the smart phone 900 shown, the processor 901 can be used as the control unit 220 of the STA 200. For example, the processor 901 can control the connection process for the AP 100 based on the received information (such as received power information, propagation loss information, etc.) of the beacon signal from the AP 100, the first threshold, the second threshold, and so on.

[0191] It should be noted that by allowing the processor 901 to execute the access point function at the application level, the smart phone 900 can be used as a radio access point (software AP). In addition, the wireless communication interface 913 can have a radio access point function.

[0192] (6.2. Second Application Example)

[0193] ​ It is a block diagram showing an example of the schematic structure of an in-vehicle navigation device 920 to which the technology according to the present disclosure can be applied. The in-vehicle navigation device 920 includes a processor 921, a memory 922, a global positioning system (GPS) module 924, a sensor 925, a data interface 926, a content player 927, a storage medium interface 928, an input device 929, a display device 930, a speaker 931, a wireless communication interface 933, an antenna switch 934, an antenna 935, and a battery 938.

[0194] The processor 921 can be, for example, a CPU and an SoC, and controls the navigation function and other functions of the in-vehicle navigation device 920. The memory 922 includes a RAM and a ROM, and stores programs and data executed by the processor 921.

[0195] The GPS module 924 measures the position (such as latitude, longitude, and altitude) of the in-vehicle navigation device 920 using GPS signals received from GPS satellites. The sensor 925 can include a set of sensors, such as a gyro sensor, a geomagnetic sensor, and a barometric pressure sensor. The data interface 926 is connected to the in-vehicle network 941 via, for example, a terminal (not shown), and acquires data generated on the vehicle side (such as vehicle speed data).

[0196] The content player 927 plays content stored in a storage medium (such as a CD or a DVD) inserted into the storage medium interface 928. The input device 929 includes, for example, a touch sensor that detects touches on the screen of the display device 930, buttons, switches, etc., and receives operation or information input from the user. The display device 930 has a screen (such as an LCD or an OLED display), and displays images of the navigation function or the content to be played. The speaker 931 outputs the audio of the navigation function or the content to be played.

[0197] The wireless communication interface 933 supports one or more wireless LAN standards (such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, and 11ax) and performs wireless communication. The wireless communication interface 933 can communicate with other devices via a wireless LAN access point in infrastructure mode. Additionally, the wireless communication interface 933 can directly communicate with another device in ad hoc mode or direct communication mode (such as Wi-Fi Direct). The wireless communication interface 933 generally includes a baseband processor, radio frequency (RF) circuitry, a power amplifier, etc. The wireless communication interface 933 can be a single-chip module in which a memory storing a communication control program, a processor executing the program, and related circuitry are integrated. In addition to wireless LAN solutions, the wireless communication interface 933 can also support other types of wireless communication solutions, such as short-range wireless communication solutions, proximity wireless communication solutions, and cellular communication solutions. The antenna switch 934 switches the connection destination of the antenna 935 among a plurality of circuits included in the wireless communication interface 933. The antenna 935 has one or more antenna elements and is used to transmit and receive wireless signals via the wireless communication interface 933.

[0198] It should be noted that the vehicle navigation device 920 is not limited to ​ the examples and may include multiple antennas. In this case, the antenna switch 934 can be omitted from the structure of the vehicle navigation device 920.

[0199] The battery 938 supplies power to each block of the vehicle navigation device 920 shown in ​ through a power line partially shown by a dotted line in the drawings. Additionally, the battery 938 stores the power supplied from the vehicle side.

[0200] In ​ the vehicle navigation device 920 shown, the processor 921 can be used as the control unit 220 of the STA 200. The operation of the processor 921 acting as the control unit 220 is similar to the operation of the processor 901 of the smart phone 900 described with reference to ​ this specification.

[0201] In addition, the wireless communication interface 933 can be used as the above-described AP 100 and provide a wireless connection to a terminal owned by a user on the vehicle. At this time, for example, the wireless communication interface 933 can set a first threshold and a second threshold, and can overall control the generation process and transmission process of a beacon signal including these thresholds in the ESS report element. In addition, the wireless communication interface 933 can dynamically set the first threshold based on the current AP reception power information included in the reconnection request signal from the attached terminal. In addition, the wireless communication interface 933 can manage the minimum value of the first threshold. In addition, the wireless communication interface 933 can dynamically set the second threshold according to the communication state (e.g., channel utilization rate, etc.) of another AP 100 belonging to the same ESS. In addition, the wireless communication interface 933 can manage the second threshold for each BSSID.

[0202] In addition, the technology according to the present disclosure can be implemented as an in-vehicle system (or vehicle) 940 including one or more blocks of the above-described car navigation device 920, an in-vehicle network 941, and a vehicle-side module 942. The vehicle-side module 942 generates vehicle-side data (such as vehicle speed, engine speed, or fault information) and outputs the generated data to the in-vehicle network 941.

[0203] (6.3. Third Application Example)

[0204] ​ It is a block diagram showing an example of a schematic structure of a radio access point 950 to which the technology according to the present disclosure can be applied. The radio access point 950 includes a controller 951, a memory 952, an input device 954, a display device 955, a network interface 957, a wireless communication interface 963, an antenna switch 964, and an antenna 965.

[0205] The controller 951 can be, for example, a CPU or a digital signal processor (DSP), and operates various functions of the Internet protocol (IP) layer and higher layers of the wireless access point 950 (e.g., access restriction, routing, encryption, firewall, log management, etc.). The memory 952 includes a RAM and a ROM, and stores programs and various control data (e.g., a terminal list, a routing table, an encryption key, security settings, logs, etc.) executed by the controller 951.

[0206] The input device 954 includes, for example, buttons, switches, etc., and receives operations from a user. The display device 955 includes, for example, an LED lamp, etc., and displays the operating state of the radio access point 950.

[0207] The network interface 957 is a wired communication interface that connects the radio access point 950 to the wired communication network 958. The network interface 957 may have a plurality of connection terminals. The wired communication network 958 may be a LAN, such as Ethernet (registered trademark) or a wide area network (WAN).

[0208] The wireless communication interface 963 supports one or more wireless LAN standards (such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, and 11ax), and provides a wireless connection to nearby terminals as an access point. The wireless communication interface 963 generally can include a baseband processor, radio frequency (RF) circuits, power amplifiers, etc. The wireless communication interface 963 may be a single-chip module, in which a memory storing a communication control program, a processor executing the program, and related circuits are integrated. The antenna switch 964 switches the connection destination of the antenna 965 among a plurality of circuits included in the wireless communication interface 963. The antenna 965 has a single or multiple antenna elements and is used to transmit and receive wireless signals through the wireless communication interface 963.

[0209] In ​ the radio access point 950 shown, the controller 951 can be used as the control unit 120 of the AP 100. For example, the controller 951 can set a first threshold and a second threshold, and can overall control the generation process and transmission process of a beacon signal including these thresholds in the ESS report element. In addition, the controller 951 can dynamically set the first threshold based on the current AP reception power information included in the reconnection request signal from an affiliated terminal. In addition, the controller 951 can manage the minimum value of the first threshold. In addition, the controller 951 can dynamically set the second threshold according to the communication state (such as channel utilization rate, etc.) of another AP 100 belonging to the same ESS. In addition, the controller 951 can manage the second threshold for each BSSID.

[0210] <7. Summary>

[0211] As described above, the AP 100 according to the present disclosure can more appropriately control the BSS transition of the STA 200 by using not only the first threshold but also the second threshold. In addition, the AP 100 can dynamically set the first threshold without scanning the surrounding environment by receiving a reconnection request signal including the current AP reception power information from the affiliated STA 200. In addition, the AP 100 can prevent the BSS connection holding range from expanding beyond its own capabilities by setting the minimum value of the first threshold. In addition, the AP 100 can dynamically set the second threshold without scanning the surrounding environment by receiving information about the communication state (e.g., channel usage rate, etc.) of another AP 100 belonging to the same ESS. In addition, the AP 100 can more finely control the BSS transition of the STA 200 by managing the second threshold for each BSSID.

[0212] As described above, the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, but the technical scope of the present disclosure is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical concept described in the claims, and of course, it should be understood that these changes and modifications fall within the technical scope of the present disclosure.

[0213] For example, each step in the above flowcharts and sequence diagrams does not have to be processed in chronological order as described. That is, each step in the flowcharts and sequence diagrams can be processed in an order different from the described order, or can be processed in parallel.

[0214] In addition, the effects described in this specification are merely illustrative or exemplary and are not limited to those described in this specification. That is, in addition to or instead of the above effects, the technology according to the present disclosure can exhibit other effects that are apparent to those skilled in the art from the description of this specification.

[0215] The following structures are also within the technical scope of the present disclosure.

[0216] (1) A wireless communication device serving as an access point for a wireless LAN, comprising:

[0217] A control unit that dynamically sets a threshold used when a station belonging to a BSS of this device transfers to another BSS belonging to the same ESS as the BSS based on information included in a wireless signal from an external device.

[0218] (2) The wireless communication device according to (1), wherein

[0219] The control unit dynamically sets two types of thresholds.

[0220] (3) The wireless communication device according to (2), wherein

[0221] One type of the two types of thresholds is a first threshold for comparison with reception information regarding a wireless signal from this device.

[0222] (4) The wireless communication device according to (3), wherein

[0223] The control unit dynamically sets the first threshold based on reception information regarding a wireless signal from this device included in a wireless signal from the station.

[0224] (5) The wireless communication device according to (3) or (4), wherein

[0225] The control unit manages the minimum value of the first threshold.

[0226] (6) The wireless communication device according to any one of (3) to (5), wherein

[0227] The other type of the two types of thresholds is a second threshold for comparison with the difference between reception information regarding a wireless signal from this device and reception information regarding a wireless signal from another access point.

[0228] (7) The wireless communication device according to (6), wherein

[0229] The control unit dynamically sets the second threshold based on information regarding the communication state of the other access point included in a wireless signal from the other access point.

[0230] (8) The wireless communication device according to (6) or (7), wherein

[0231] The control unit sets the second threshold for each BSS.

[0232] (9) The wireless communication device according to any one of (3) to (8), wherein

[0233] The reception information is information regarding received power or information regarding propagation loss.

[0234] (10) A wireless communication method for implementing an access point function of a wireless LAN, including:

[0235] Dynamically setting a threshold used when a station belonging to a BSS of this device attempts to transfer to another BSS belonging to the same ESS as the BSS based on information included in a wireless signal from an external device.

[0236] (11) A wireless communication device serving as a wireless LAN station, including:

[0237] A control unit controls the handover to another BSS belonging to the same ESS as the BSS to which it belongs, using a threshold dynamically set based on information included in a wireless signal from an external device and reception information on the wireless signal from an access point.

[0238] (12) The wireless communication device according to (11), wherein

[0239] The control unit controls the handover using two types of thresholds.

[0240] (13) The wireless communication device according to (12), wherein

[0241] The control unit controls the handover based on a comparison result between a first threshold, which is one type of the two types of thresholds, and reception information on the wireless signal from an access point.

[0242] (14) The wireless communication device according to (13), further comprising:

[0243] A transmission unit that transmits a wireless signal including reception information for dynamic setting of the first threshold to an access point.

[0244] (15) The wireless communication device according to (13) or (14), wherein

[0245] The control unit controls the handover based on a comparison result between the minimum value of the first threshold and reception information on the wireless signal from an access point.

[0246] (16) The wireless communication device according to any one of (13) to (15), wherein

[0247] The control unit controls the handover based on a comparison result between the difference between reception information on the wireless signal from an access point and reception information on the wireless signal from another access point and a second threshold, which is the other type of the two types of thresholds.

[0248] (17) The wireless communication device according to (16), wherein

[0249] The second threshold is dynamically set by the access point based on information on the communication state of the other access point included in the wireless signal from the other access point.

[0250] (18) The wireless communication device according to (16) or (17), wherein

[0251] The access point sets the second threshold for each BSS.

[0252] (19) The wireless communication device according to any one of (11) to (18), wherein

[0253] The received information is information about received power or information about propagation loss.

[0254] (20) A wireless communication method for implementing the station function of a wireless LAN station, comprising:

[0255] Using a threshold dynamically set based on information included in a wireless signal from an external device and received information about a wireless signal from an access point to control the transfer to another BSS belonging to the same ESS as the BSS to which it belongs.

[0256] List of reference numerals

[0257] 100 AP

[0258] 200 STA

[0259] 110, 210 Data processing unit

[0260] 120, 220 Control unit

[0261] 130, 230 Storage unit

[0262] 140, 240 Transmission unit

[0263] 141, 241 Analog signal conversion unit

[0264] 142, 242 RF transmission unit

[0265] 150, 250 Antenna sharing unit

[0266] 160, 260 Antenna

[0267] 170, 270 Reception unit

[0268] 171, 271 RF reception unit

[0269] 172, 272 Digital signal conversion unit

Claims

1. A wireless communication device serving as an access point for a wireless LAN, comprising: A control unit that dynamically sets a threshold value used when a station belonging to a BSS of this device attempts to transfer to another BSS belonging to the same ESS as the BSS, based on information included in a wireless signal from an external device.

2. The wireless communication device according to claim 1, wherein The control unit dynamically sets two types of threshold values.

3. The wireless communication device according to claim 2, wherein One type of the two types of threshold values is a first threshold value for comparison with reception information regarding a wireless signal from this device.

4. The wireless communication device according to claim 3, wherein The control unit dynamically sets the first threshold value based on reception information regarding a wireless signal from this device, included in a wireless signal from the station.

5. The wireless communication device according to claim 3, wherein The control unit manages the minimum value of the first threshold value.

6. The wireless communication device according to claim 3, wherein The other type of the two types of threshold values is a second threshold value for comparison with the difference between reception information regarding a wireless signal from this device and reception information regarding a wireless signal from another access point.

7. The wireless communication device according to claim 6, wherein The control unit dynamically sets the second threshold value based on information regarding the communication state of the other access point, included in a wireless signal from the other access point.

8. The wireless communication device according to claim 6, wherein The control unit sets the second threshold value for each BSS.

9. The wireless communication device according to claim 3, wherein The reception information is information regarding reception power or information regarding propagation loss.

10. A wireless communication method for implementing an access point function of a wireless LAN, comprising: Dynamically setting a threshold value used when a station belonging to a BSS of this device attempts to transfer to another BSS belonging to the same ESS as the BSS, based on information included in a wireless signal from an external device.

11. A wireless communication device serving as a wireless LAN station, comprising: A control unit that controls the transfer to another BSS belonging to the same ESS as the BSS to which it belongs, using a threshold value dynamically set based on information included in a wireless signal from an external device and reception information regarding a wireless signal from an access point.

12. The wireless communication device according to claim 11, wherein The control unit controls the transfer using two types of threshold values.

13. The wireless communication device according to claim 12, wherein The control unit controls the transfer based on the comparison result between a first threshold value, which is one type of the two types of threshold values, and reception information regarding a wireless signal from an access point.

14. The wireless communication device according to claim 13, further comprising: A transmission unit that transmits a wireless signal including reception information for dynamic setting of the first threshold value, to an access point.

15. The wireless communication device according to claim 13, wherein The control unit controls the handover based on a comparison result between the minimum value of the first threshold and reception information regarding a wireless signal from an access point.

16. The wireless communication device according to claim 13, wherein the control unit controls the handover based on a comparison result between a difference between reception information regarding a wireless signal from an access point and reception information regarding a wireless signal from another access point and a second threshold that is the other type of threshold among the two types of thresholds.

17. The wireless communication device according to claim 16, wherein the second threshold is dynamically set by the access point based on information on a communication state of the other access point included in the wireless signal from the other access point.

18. The wireless communication device according to claim 16, wherein the access point sets a second threshold for each BSS.

19. The wireless communication device according to claim 11, wherein the reception information is information on reception power or information on propagation loss.

20. A wireless communication method for implementing a station function of a wireless LAN, comprising: controlling a handover to another BSS belonging to the same ESS as the BSS to which the station belongs by using a threshold dynamically set based on information included in a wireless signal from an external device and reception information regarding a wireless signal from an access point.

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