Method of selecting an access point and associated communication device

Abstract

A communication device and a method for selecting an access point, the method is applied to a communication device and includes the following steps: (a) listening to a channel of at least one frequency band; (b) calculating a first number of times that the channel is detected to be in use; (c) calculating a second number of times that the channel is detected to have ambient noise; (d) repeating steps (a) to (c) to obtain a first number and a second number of each of a plurality of channels used by a plurality of access points; (e) obtaining a plurality of received signal strength indicators (RSSIs) of the plurality of access points respectively; and (f) selecting a target channel from the plurality of channels and a target access point from the plurality of access points according to the plurality of RSSIs and the first number and the second number of each of the plurality of channels.

Description

Technical Field

[0001] This disclosure relates to communication technologies for wireless local area networks, and in particular to a method and communication apparatus for selecting access points. Background Technology

[0002] Modern daily life is inseparable from mobile devices and the internet, with Wi-Fi access points ubiquitous in public facilities and homes. Traditional mobile devices prioritize access points in a wireless network environment based on their Received Signal Strength Index (RSSI) and automatically connect to the one with the highest RSSI. Access points in the 2.4GHz band have significantly lower transmission speeds than those in the 5GHz band, and the 2.4GHz band is also more susceptible to interference from household appliances. Furthermore, RSSI alone cannot determine whether the current transmission load at an access point is high enough to cause latency. In short, traditional mobile devices do not consider noise levels and latency when selecting access points, often resulting in perceived network delays and a degraded user experience. Summary of the Invention

[0003] This disclosure provides a method for selecting an access point, applicable to a communication device, and includes the following steps: (a) monitoring channels in at least one frequency band; (b) calculating a first number of times a channel is detected to be in use; (c) calculating a second number of times a channel is detected to have ambient noise; (d) repeating steps (a) to (c) to obtain a first number and a second number for each of the multiple channels used by the multiple access points; (e) obtaining multiple received signal strength indices (RSSIs) for the multiple access points respectively; and (f) selecting a target channel among the multiple channels and a target access point among the multiple access points based on the multiple RSSIs and the first and second numbers for each of the multiple channels.

[0004] This disclosure provides a communication apparatus comprising an antenna and a baseband circuit. The antenna is used to transmit or receive radio frequency signals in at least one frequency band. The baseband circuit is coupled to the antenna and is used to: (a) monitor channels in at least one frequency band; (b) count a first number of times a channel is detected to be in use; (c) count a second number of times a channel is detected to have ambient noise; (d) repeat steps (a) to (c) to obtain a first number and a second number of times each of a plurality of channels used by a plurality of access points; (e) obtain a plurality of RSSIs of the plurality of access points respectively; and (f) select a target channel among the plurality of channels and a target access point among the plurality of access points for connection based on the plurality of RSSIs and the first and second numbers of each of the plurality of channels.

[0005] One of the advantages of the above-mentioned method and communication device is that it can comprehensively consider the RSSI of the access point, the latency of the channel, and the noise intensity of the channel to automatically connect to the most efficient channel and access point for data transmission. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating a wireless network environment according to an embodiment of this disclosure.

[0007] Figure 2 This is a flowchart of a method for selecting an access point according to an embodiment of this disclosure.

[0008] Figure 3 This is a schematic diagram of a communication device performing channel scanning in one embodiment of this disclosure.

[0009] Figure 4 This is a schematic diagram of a communication device detecting whether a channel is in use, according to one embodiment of this disclosure.

[0010] Figure 5 This is a schematic diagram of a communication device detecting the presence of environmental noise in a channel, according to one embodiment of this disclosure.

[0011] Figure 6 This is a partial flowchart of a method for selecting an access point according to an embodiment of this disclosure.

[0012] Figure 7 This is a simplified functional block diagram of a communication device according to an embodiment of this disclosure.

[0013] Symbol Explanation

[0014] 100: Wireless Network Environment

[0015] 101: Home Appliances

[0016] AP1, AP2, AP3: Access Points

[0017] STA1, STA2, STA3: communication device

[0018] 200: Methods for selecting access points

[0019] S210~S280: Steps

[0020] 310–370: Beacon Frames

[0021] LT: During listening

[0022] T1: First preset time interval

[0023] G1: First logical value

[0024] G2: Second logical value

[0025] S610~S660: Steps

[0026] 700: Communication device

[0027] 710: Antenna

[0028] 720: Transmitter Circuit

[0029] 730: Receiver Circuit

[0030] 740: Switching Circuit

[0031] 750: Local Oscillator

[0032] 760: Baseband Circuit

[0033] 770: Memory Detailed Implementation

[0034] The embodiments of this disclosure will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar elements or method steps.

[0035] Figure 1 This is a schematic diagram of a wireless network environment 100 according to an embodiment of this disclosure. The wireless network environment 100 includes multiple access points AP1-AP3, multiple communication devices STA1-STA3, and a home appliance 101 (e.g., a microwave oven). Access points AP1-AP3 can be electronic devices supporting the IEEE 802.11 WiFi communication protocol. For example, access points AP1-AP3 can be wireless routers. As another example, communication devices STA1-STA3 can be smartphones, laptops, or other portable electronic devices with wireless communication capabilities. Communication device STA1 is within the communication range of access points AP1-AP3; that is, communication device STA1 can discover the existence of access points AP1-AP3 through active or passive scanning and connect to one of access points AP1-AP3. For example, communication device STA1 can access the Internet through one of access points AP1-AP3. Communication devices STA2-STA3 also have similar functions to communication device STA1, which will not be repeated here. The boundary of the communication range is... Figure 1 The dashed lines indicate that access points AP1 to AP3 are each located at the center of their respective communication range. However, Figure 1 The configuration and arrangement of various devices are for ease of understanding only, and this document is not intended to limit us to them.

[0036] Figure 2This is a flowchart of a method 200 for selecting an access point according to an embodiment of this disclosure. Any method described herein may include more or fewer steps than shown in the flowchart, and the steps in the method may be performed in any suitable order. Communication device STA1 can perform method 200 to connect to the access point, frequency band, and channel that is most efficient and least interfered with for data transmission.

[0037] In the following embodiments of this disclosure, the frequency bands supported by access points AP1 to AP3 and the channels used are shown in Table 1 below. However, the frequency band and channel configuration shown in Table 1 is for illustrative purposes only and is not intended to limit this disclosure. Those skilled in the art will understand the channel numbers and center frequencies of the 2.4 GHz and 5 GHz bands, which will not be repeated here.

[0038] Table 1

[0039] frequency band aisle Access point AP1 2.4GHz 1,6 Access point AP2 5GHz 149,153,161 Access point AP3 5GHz 153,161

[0040] In some embodiments, the interference source in the wireless network environment 100 may be Figure 1 A household appliance 101 is located near access point AP1. The electromagnetic waves generated by the household appliance 101 may interfere with the communication between communication device STA1 and access point AP1. In some embodiments, the interference source may also be communication devices STA2-STA3 located within the communication range of access points AP2 and AP3. If communication devices STA2-STA3 densely use the 5GHz band to transmit packets, the chance of signal collisions occurring in the air on the 5GHz band will increase, thereby interfering with the communication between communication device STA1 and access points AP2 or AP3. The operation of communication device STA1 when performing each step of method 200 will be further described below.

[0041] Please also refer to Figure 2 and Figure 3 , Figure 3 This is a schematic diagram of a communication device STA1 performing a channel scan in one embodiment of this disclosure. The communication device STA1 can execute steps S210 to S250 multiple times to scan multiple channels in the frequency band (e.g., 2.4 GHz and 5 GHz) supported by the communication device STA1. First, in step S210, the communication device STA1 can select "Channel 1" in the 2.4 GHz frequency band and continuously listen to the signal in "Channel 1" during the listening period LT.

[0042] In step S220, the communication device STA1 determines whether a beacon frame has been received in the currently monitored channel. If the communication device STA1 receives a beacon frame during the monitoring period LT, it determines that this channel corresponds to an available wireless network and then executes steps S220-S250 to obtain relevant information about this channel, such as noise intensity or latency. For example, ... Figure 3 As shown, since the communication device STA1 receives the beacon frame 310 from the access point AP1 during the listening period of "Channel 1", the communication device STA1 will then record the information of "Channel 1". On the other hand, if the communication device STA1 does not receive the beacon frame during the listening period of LT, the communication device STA1 will determine that this channel does not correspond to an available wireless network, and the communication device STA1 can switch to another channel and / or another frequency band after the listening period of LT ends, and execute step S210 again.

[0043] Please continue to refer to this. Figure 2 and Figure 4 , Figure 4 This is a schematic diagram of a communication device STA1 detecting whether a channel is in use in one embodiment of this disclosure. In step S230, the communication device STA1 can detect whether the currently monitored channel is in use every first preset time interval T1 (e.g., 4 microseconds (μs)) during the listening period LT. If so, the count of the channel being in use is incremented by 1 to obtain the first number of times the channel has been detected as being in use at the end of the listening period LT. For example, in Figure 4 In the embodiment, during the listening period, the communication device STA1 performed a total of 6x10 on "Channel 1". 4 The tests were conducted, and a total of 10 of them were performed. 4 When a detection point detects that "Channel 1" is in use, the communication device STA1 will set the first count for "Channel 1" to 10. 4 .

[0044] In one embodiment, if the communication device STA1 detects that the channel is being used to transmit packets of a predetermined format (e.g., WiFi packets), the communication device STA1 determines that the channel is in use. Conversely, the communication device STA1 determines that the channel is idle.

[0045] In some embodiments, the communication device STA1 can determine whether a channel is being used to transmit packets of a predetermined format through a Clear Channel Assessment (CCA) operation. For example, the Clear Channel Assessment operation includes a Carrier Sense step, which identifies a preamble of a specific format, which may contain the packet's data length, thereby determining whether a packet of the predetermined format exists on the channel and the duration the channel will be occupied. For example, as... Figure 4 As shown, when the idle channel evaluation result indicates that "Channel 1" is being used to transmit packets of a predetermined format, the idle channel evaluation index in communication device STA1 can be switched to the first logic value G1, so that communication device STA1 can determine that "Channel 1" is in use when performing the aforementioned detection. Conversely, the idle channel evaluation index in communication device STA1 can be set to the second logic value G2, so that communication device STA1 determines that "Channel 1" is in an idle state.

[0046] Please continue to refer to this. Figure 2 and Figure 5 , Figure 5 This is a schematic diagram of a communication device STA1 detecting the presence of ambient noise in a channel according to one embodiment of this disclosure. In step S240, the communication device STA1 can detect whether the currently monitored channel has ambient noise every second preset time interval (e.g., 4 microseconds (μs)) during the monitoring period LT. If the communication device STA1 determines that the channel has ambient noise, it increments the count of the channel having ambient noise by 1 to obtain a second count of detecting ambient noise in the channel at the end of the monitoring period LT. In some embodiments, the second preset time interval may be the same as or different from the first preset time interval T1 in step S230. In other embodiments, the order of steps S230 and S240 may be interchanged, or steps S230 and S240 may be executed simultaneously.

[0047] Specifically, the communication device STA1 can record the received energy level as a numerical data point each time it detects energy, and classify all numerical data obtained during the listening period LT into different levels according to their magnitude, so as to obtain, for example... Figure 5The statistical charts shown are illustrated. In some embodiments, the communication device STA1 may pre-store multiple classification thresholds as the basis for classification numerical data, such as -92dBm, -89dBm, -86dBm, -83dBm, -80dBm, -75dBm, -70dBm, -65dBm, -60dBm, and -55dBm. However, this disclosure is not limited to this, and the number and size of the classification thresholds can be adjusted according to actual design requirements. The communication device STA1 may also store interference thresholds. When the numerical data is greater than or equal to the interference threshold, it indicates that the channel may have environmental noise during the detection.

[0048] In some embodiments, the interference threshold is between -75 and -92 dBm. In this case, as... Figure 5 As shown, there are approximately 3.6 x 10. 4 The test results indicated that "Channel 1" may have ambient noise. In one embodiment, the interference threshold is -80 dBm.

[0049] It is worth mentioning that, in addition to environmental noise, the following factors may also cause the communication device STA1 to record numerical data exceeding the interference threshold: (1) radio frequency signals with specific format packets (e.g., WiFi packets) generated by access points AP1-AP3 and communication devices STA2-STA3; and (2) radio frequency signals generated by the communication device STA1 itself when transmitting packets. Therefore, in some embodiments, in the numerical data exceeding the interference threshold, the communication device STA1 may not need to consider the portion caused by the above factors, and count the number of data values ​​actually caused by environmental noise as a second count.

[0050] For example, such as Figure 5 As shown, communication device STA1 does not need to consider the 1.2x10 dBm range. 4 These numerical data points correspond to radio frequency signals (Rx signals) generated by other devices and containing WiFi packets. Communication device STA1 also does not need to consider the 6x10 data points located in the -65 to -60 dBm range. 3 These numerical data are sampled during the period when the communication device STA1 transmits radio frequency signals (Tx signals). Therefore, the communication device STA1 can only consider approximately 1.8 x 10^6 data points greater than -55 dBm. 4 The numerical data was recorded, and the second iteration of "Channel 1" was set to approximately 1.8 x 10^6. 4 .

[0051] In some embodiments, the listening periods LT of the multiple channels may be different. In order to accommodate the possible different listening periods LT of the multiple channels, or to save memory space, the communication device STA1 may standardize the first number and the second number obtained in steps S230 and S240.

[0052] For example, in step S230, the communication device STA1 can obtain the first total number of detections during the listening period LT to determine whether the channel is in use, and divide the first number by the first total number of detections to obtain the first percentage of the channel. Figure 4 In one embodiment, by using 10 4 Divide by 6 x 10 4 We can see that the first percentage of "Channel 1" is approximately 16.67%.

[0053] For example, in step S240, the communication device STA1 can obtain a second total number of detections during the listening period LT to determine whether the channel has ambient noise, and divide the second number by the second total number of detections to obtain a second percentage of the channel. Figure 5 In this embodiment, assuming the first preset time interval is the same as the second preset time interval, the second total number of detections is 6 x 10. 4 By using 1.8x10 4 Divide by 6 x 10 4 We can see that the second percentage of "Channel 1" is 30%.

[0054] Please refer to this again. Figure 2 In step S250, the communication device STA1 determines whether the scanning of all channels and / or frequency bands supported by the communication device STA1 has been completed. If so, the communication device STA1 then executes steps S260-S270 to analyze the first and second counts (or the first and second percentages) for each channel to select the most efficient access point, frequency band, and channel for data transmission. If the scanning of all channels and / or frequency bands has not been completed, the communication device STA1 can switch to another channel and / or another frequency band and execute step S210 again.

[0055] In step S260, the communication device STA1 can acquire multiple Received Signal Strength Indices (RSSIs) for access points AP1 to AP3 respectively. RSSI represents the relative strength of the signal received in the wireless network environment 100. In some embodiments, step S260 can be performed before step S210, or simultaneously with any of steps S210 to S250.

[0056] Through steps S210 to S260, such as Figure 3As shown, communication device STA1 receives beacon frames 310 and 320 from access point AP1 in "Channel 1" and "Channel 6"; receives beacon frames 330, 340, and 350 from access point AP2 in "Channel 149", "Channel 153", and "Channel 161"; and receives beacon frames 360 and 370 from access point AP3 in "Channel 153" and "Channel 161". Therefore, communication device STA1 can obtain the number of access points AP1 to AP3 in the wireless network environment 100, as well as the frequency bands supported by each access point AP1 to AP3 and the channels used.

[0057] In step S270, the communication device STA1 calculates multiple communication quality parameters for each access point. Each communication quality parameter represents the communication quality of the access point when it communicates through a corresponding channel it uses.

[0058] For example, referring to Table 1 above, communication device STA1 will calculate two communication quality parameters for access point AP1 corresponding to "channel 1" and "channel 6" respectively; it will calculate three communication quality parameters for access point AP2 corresponding to "channel 149", "channel 153" and "channel 161" respectively; and it will calculate two communication quality parameters for access point AP3 corresponding to "channel 153" and "channel 161" respectively.

[0059] Each communication quality parameter can be calculated using the following Formula 1. In Formula 1, "Q" represents the communication quality parameter; "CLM" represents the first count or first percentage; "NHM" represents the second count or second percentage; "M" represents the access point number; "N" represents the channel number; "α" and "β" are preset parameters, or in some embodiments, "α" and "β" can be adaptively adjusted by the user according to various factors in the environment (such as interference intensity), where "α" is greater than "β".

[0060]

[0061] In an exemplary embodiment, "α" is 1 and "β" is 0.5. The RSSI of access points AP1 to AP3 are assumed to be -60dBm, -63dBm and -64dBm, respectively. The communication quality parameters of access points AP1 to AP3 are shown in Tables 2 to 4 below.

[0062] Table 2. Communication quality parameters of access point AP1

[0063]

[0064] Table 3. Communication quality parameters of access point AP2

[0065]

[0066] Table 4. Communication quality parameters of access point AP3

[0067]

[0068]

[0069] In the above embodiments, the first count and the first percentage can be used to represent the channel latency. The higher the first count or the first percentage, the greater the channel latency. The second count and the second percentage can be used to represent the channel noise intensity. The higher the second count or the second percentage, the greater the channel noise intensity. Therefore, a larger communication quality parameter represents preferred communication quality. In step S280, the communication device STA1 can select the access point and channel corresponding to the largest of all communication quality parameters obtained in step S270, as the target access point and target channel for connection, respectively, thereby obtaining the best data transmission efficiency.

[0070] For example, in the embodiments shown in Tables 2 to 4 above, "Channel 1" and "Channel 6" are severely interfered with by household appliance 101. Communication device STA2 is communicating with access point AP2 through "Channel 153", and communication device STA3 is communicating with access point AP3 through "Channel 161", resulting in considerable delays in "Channel 153" and "Channel 161". Therefore, the maximum communication quality parameter "-58.1" reflects that access point AP2 and "Channel 149" have relatively good connection quality. Communication device STA1 will select "Channel 149" and access point AP2 as the target channel and target access point, and connect to access point AP2 through "Channel 149".

[0071] As described above, compared to the traditional method of selecting access points solely based on RSSI, the method 200 provided in this disclosure comprehensively considers RSSI, channel latency, and channel noise intensity. Communication device STA1 can automatically avoid using the 2.4GHz band, which typically has higher noise levels, even though access points in the 2.4GHz band usually have better RSSI. Furthermore, when different access points supporting the 5GHz band have similar RSSI values ​​(e.g., access points AP2 and AP3), communication device STA1 can prioritize using channels and access points with lower latency and avoid using channels and access points with higher latency.

[0072] Please refer to Figure 2 and Figure 6 , Figure 6This is a partial flowchart of a method 200 for selecting an access point according to an embodiment of this disclosure. In some embodiments, the communication device STA1 may be configured to preferentially select one of a plurality of frequency bands (hereinafter referred to as the "preferred band") for communication. In this case, Figure 2 Steps S270 to S280 can be replaced with Figure 6 Steps S610 to S660. For ease of explanation, in the following embodiments, the communication device STA1 is set to preferentially select the 5GHz frequency band, but this disclosure is not limited thereto.

[0073] In step S610, the communication device STA1 determines whether there are one or more access points (hereinafter referred to as "preferred access points") in the wireless network environment 100 that support a preferred frequency band (e.g., the 5GHz band), and whether the RSSI of these preferred access points is greater than or equal to a strength threshold (e.g., -80dBm). If so, the communication device STA1 proceeds to steps S620-S640 to connect to one of the preferred access points. If there is no preferred access point or the RSSI of all preferred access points is less than the strength threshold, the communication device STA1 proceeds to steps S650-S660 to comprehensively evaluate the connection quality of all access points in the wireless network environment 100. The following will first be in conjunction with... Figure 1 Tables 3 and 4 illustrate the detailed operation of the communication device STA1 in determining that a preferred access point exists in the wireless network environment 100 (i.e., the determination in step S610 is "yes").

[0074] Since access points AP2 and AP3, which support the 5GHz band, exist in the wireless network environment 100, and the RSSI of access points AP2 and AP3 is greater than the strength threshold, communication device STA1 will proceed to step S620 after step S610. In step S620, communication device STA1 will determine the channel used by the preferred access point (hereinafter referred to as the "preferred channel"). For example, communication device STA1 will determine that the preferred channel includes "channel 149", "channel 153" and "channel 161" used by access points AP2 and AP3.

[0075] Next, in step S630, the communication device STA1 calculates the communication quality parameters for each preferred access point according to the aforementioned Formula 1. For example, the communication device STA1 calculates three communication quality parameters for access point AP2 corresponding to "channel 149", "channel 153" and "channel 161", and calculates two communication quality parameters for access point AP3 corresponding to "channel 153" and "channel 161". The calculation results are shown in Tables 3 and 4 above, and will not be repeated here.

[0076] In step S640, the communication device STA1 selects the preferred access point and preferred channel corresponding to the largest of all communication quality parameters obtained in step S630, and uses them as the target access point and target channel for connection. For example, the communication device STA1 selects "channel 149" and access point AP2 as the target channel and target access point, and connects to access point AP2 through "channel 149".

[0077] The following will describe in detail how the communication device STA1 determines that there is no preferred access point or that the RSSI of all preferred access points is less than the strength threshold in the wireless network environment 100 (i.e., the determination in step S610 is "No"). In the following embodiments, the RSSI of access points AP1 to AP3 are assumed to be -80dBm, -83dBm, and -87dBm, respectively.

[0078] Since the determination in step S610 is "No", the communication device STA1 will then execute process S650 to calculate multiple communication quality parameters for each access point. The communication quality parameter of the preferred access point will be increased by a value "γ×PFB" (e.g., 0.5) to increase the chance of the communication device STA1 connecting to the preferred access point. In some embodiments, "γ" is an adjustable parameter and "PFB" is a preset parameter; the user can adjust "γ" according to their preference for a specific frequency band. In one embodiment, "γ" is approximately equal to "β" and "γ" is less than "α". Specifically, the communication quality parameter of a general access point (e.g., access point AP1) can be calculated using the aforementioned Formula 1, while the communication quality parameter of preferred access points (e.g., access points AP2-AP3) can be calculated using the following Formula 2.

[0079]

[0080] In an exemplary embodiment, the communication quality parameters of access points AP1 to AP3 obtained in process S650 are shown in Tables 5 to 7 below, where “α” and “PFB” are 1, and “β” and “γ” are 0.5.

[0081] Table 5. Communication quality parameters of access point AP1

[0082]

[0083] Table 6. Communication quality parameters of access point AP2

[0084]

[0085] Table 7. Communication quality parameters of access point AP3

[0086]

[0087]

[0088] In step S660, communication device STA1 can select the access point and channel corresponding to the largest of the multiple communication quality parameters obtained in step S650, and use them as the target access point and target channel for connection. For example, communication device STA1 will select "channel 149" and access point AP2 as the target channel and target access point, and connect to access point AP2 through "channel 149".

[0089] By using Figure 6 In the process, the communication device STA1 can prioritize connecting to an access point that supports the user's preferred frequency band, and can select a low-noise and low-latency channel for communication within the user's preferred frequency band, thereby helping to improve the user experience.

[0090] Figure 7 This is a simplified functional block diagram of a communication device 700 according to an embodiment of this disclosure. The communication device 700 can be used to implement... Figure 1 The communication device STA1 is described above. The communication device 700 includes an antenna 710, a transmitter circuit 720, a receiver circuit 730, a switching circuit 740, a local oscillator 750, a baseband circuit 760, and a memory 770. The baseband circuit 760 is coupled to the transmitter circuit 720, the receiver circuit 730, and the memory 770. The transmitter circuit 720 and the receiver circuit 730 are coupled to the antenna 710 via the switching circuit 740. The local oscillator 750 is coupled to the transmitter circuit 720 and the receiver circuit 730.

[0091] The switching circuit 740 is used to switch the antenna 710 to the transmitter circuit 720 or the receiver circuit 730 according to different operating modes. The antenna 710 is used to receive or transmit radio frequency signals in the 2.4 GHz and / or 5 GHz frequency band. In some embodiments, the antenna 710 may be implemented as a plurality of antennas respectively coupled to the transmitter circuit 720 and the receiver circuit 730, and the switching circuit 740 may be omitted. In other embodiments, the communication device 700 may include a plurality of combinations of antenna 710, transmitter circuit 720 and receiver circuit 730 to enable the communication device 700 to have multiple-input multiple-output (MIMO) functionality.

[0092] In conjunction with the local oscillator 750, the transmitter circuit 720 modulates the baseband signal generated by the baseband circuit 760 into a radio frequency signal, while the receiver circuit 730 demodulates the radio frequency signal received by the antenna 710 into a baseband signal.

[0093] The baseband circuit 760 is used to execute the method 200 in the above embodiments based on the baseband signal from the receiver circuit 730. Method 200 may be implemented by a plurality of instructions stored in a non-transitory computer-readable medium (e.g., memory 770). When the baseband circuit 760 executes these instructions, these instructions cause some or all of method 200 to be executed. In some embodiments, the baseband circuit 760 may also be used to perform idle channel evaluation.

[0094] In some embodiments, the memory 770 is used to store the classification threshold and interference threshold discussed in step S240, and may also be used to store the intensity threshold discussed in step S610.

[0095] Certain terms are used in the specification and claims to refer to specific elements. However, those skilled in the art will understand that the same element may be referred to by different names. The specification and claims do not distinguish elements by differences in name, but by differences in function. The term "comprising" as used in the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to". Furthermore, "coupled" here includes any direct and indirect means of connection. Therefore, if the text describes a first element coupled to a second element, it means that the first element can be directly connected to the second element through electrical connection or signal connection methods such as wireless transmission or optical transmission, or indirectly electrically or signalally connected to the second element through other elements or connection means.

[0096] The use of "and / or" herein includes any combination of one or more of the listed items. Unless otherwise specified in the specification, any singular term also includes the plural meaning.

[0097] The above are merely preferred embodiments of this disclosure. Various modifications and equivalent changes can be made to the structure of this disclosure without departing from its scope or concept. In summary, all modifications and equivalent changes made to this disclosure within the scope of the following claims are within the scope of this disclosure.

Claims

1. A method for selecting an access point, applicable to a communication device, wherein the communication device supports at least one frequency band, the method comprising the steps of: (a) Listening to one channel of at least one frequency band; (b) Calculate the first count of the channel being detected as being in use; (c) Calculate a second number of ambient noise detected in the channel; (d) Repeat steps (a) to (c) to obtain the first number and the second number for each of the multiple channels used by the multiple access points; (e) Obtain the multiple received signal strength indices for the multiple access points respectively; and (f) Based on the multiple received signal strength indicators and the first number and the second number of each of the multiple channels, select a target channel among the multiple channels and connect it to a target access point among the multiple access points.

2. The method as described in claim 1, wherein, Step (b) includes: During a listening period, the channel is checked at each first preset time interval to determine whether it is in use. This checking includes: determining that the channel is in use when it is used to transmit packets of a predetermined format; and... The number of times the channel was determined to be in this usage state during the monitoring period is summed up as the first count.

3. The method as described in claim 1, wherein, Step (c) includes: During a listening period, the channel is checked for ambient noise at each second preset time interval. The check for ambient noise includes determining that the channel has ambient noise when the energy of a radio frequency signal of the channel is greater than or equal to an interference threshold, and the radio frequency signal is not generated by the communication device and does not contain a packet of a predetermined format. as well as The number of times the channel was determined to have ambient noise during the monitoring period is summed up as the second count.

4. The method as described in claim 2 or 3, wherein, The packet in this predefined format is a WiFi packet.

5. The method of claim 1, wherein, Step (f) includes: Based on the multiple received signal strength indicators and the first and second counts of each of the multiple channels, multiple communication quality parameters are calculated, wherein each communication quality parameter corresponds to a corresponding access point among the multiple access points and corresponds to a corresponding channel used by the corresponding access point among the multiple channels. as well as Based on these multiple communication quality parameters, the target channel and the target access point are selected for connection.

6. The method of claim 1, wherein, One or more of the multiple access points support a preferred frequency band in the at least one frequency band, and the one or more preferred access points use multiple preferred channels in the multiple channels, wherein step (f) includes: When one or more received signal strength indicators of the one or more preferred access points are greater than or equal to a strength threshold, the target channel is selected from the multiple preferred channels and the target access point is selected from the one or more preferred access points and connected based on the one or more received signal strength indicators, the first number and the second number of each preferred channel. as well as When the received signal strength index of one or more preferred access points is less than the strength threshold, the target channel is selected from the multiple channels and the target access point is selected from the multiple access points based on the multiple received signal strength index and the first number and the second number of each channel.

7. The method of claim 6, wherein, When the received signal strength indices of one or more preferred access points are less than the strength threshold, the selection of the target channel from the multiple channels and the selection of the target access point from the multiple access points, based on the multiple received signal strength indices and the first and second counts for each channel, includes: Based on the multiple received signal strength indicators and the first and second counts of each of the multiple channels, multiple communication quality parameters are calculated, wherein each communication quality parameter corresponds to a corresponding access point among the multiple access points and corresponds to a corresponding channel used by the corresponding access point among the multiple channels. Increase the value of the communication quality parameters corresponding to one or more preferred access points by a predetermined value; and Based on these multiple communication quality parameters, the target channel and the target access point are selected for connection.

8. A communication device, comprising: An antenna is used to transmit or receive radio frequency signals in at least one frequency band; and A baseband circuit, coupled to the antenna, is used for the following steps: (a) Listening to one channel of at least one frequency band; (b) Calculate the first count of the channel being detected as being in use; (c) Calculate a second number of ambient noise detected in the channel; (d) Repeat steps (a) to (c) to obtain the first number and the second number for each of the multiple channels used by the multiple access points; (e) Obtain the multiple received signal strength indices for the multiple access points respectively; and (f) Based on the multiple received signal strength indicators and the first number and the second number of each of the multiple channels, select a target channel among the multiple channels and connect it to a target access point among the multiple access points.

9. The communication device as claimed in claim 8, wherein, Step (b) includes: During a listening period, the channel is checked for being in use every first preset time interval. The check for being in use includes: when the channel is used to transmit a packet of a predetermined format, the channel is determined to be in use. as well as The number of times the channel was determined to be in this usage state during the monitoring period is summed up as the first count.

10. The communication device as claimed in claim 8, wherein, Step (c) includes: During a listening period, the channel is checked for ambient noise at each second preset time interval. The check for ambient noise includes determining that the channel has ambient noise when the energy of a radio frequency signal of the channel is greater than or equal to an interference threshold, and the radio frequency signal is not generated by the communication device and does not contain a packet of a predetermined format. as well as The number of times the channel was determined to have ambient noise during the monitoring period is summed up as the second count.

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