Method used by a wireless communication device to connect to an access point, and a wireless communication device using the same

Abstract

To provide a wireless communication device and method that are able to shorten the time to connect to a new access point in the event that the wireless communication device has met roaming criteria, for connecting to access points in a wireless communication system.SOLUTION: A wireless communication device includes: a wireless transceiver; and a processor coupled to the wireless transceiver. The processor is configured to: establish a first wireless connection to a first access point via the wireless transceiver; determine whether the first wireless connection of the wireless communication device has met a roaming criteria; having met the roaming criteria, obtain a subset of historical record stored in the wireless communication device according to the first access point; rank access points in the subset of historical record; select a second access point according to a list of the ranked access points; and establish a second wireless connection to the second access point via the wireless transceiver.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention is directed to a method used by a wireless communication device to connect to an access point and a wireless communication device using the method.

Background Art

[0002] Wireless communication devices such as mobile phones, laptops, tablets, or similar devices have the advantage of portability, and the portability of wireless communication devices requires that the network connection be wireless so that the wireless communication device can move long distances while maintaining the network connection. When the wireless communication device is already connected to an access point (AP) such as a WiFi access point, router, converter, repeater, or similar device, and the signal strength of the wireless connection to the AP drops below a certain threshold, the wireless communication device can switch to roaming mode and start scanning for an alternative channel belonging to another AP.

[0003] However, if a scan is performed while the wireless communication device is in roaming mode, the signal strength of the wireless connection to the original AP may continue to decrease. When the signal strength of the wireless connection to the original AP decreases, the data rate of the wireless connection also correspondingly decreases. For example, if the signal strength of the wireless connection decreases by 7.5 decibels (dB), the transmission rate can decrease from 270 megabits per second (Mbps) to 108 Mbps. If an alternative AP is not quickly found, or if the scan takes too long, the likelihood of improving signal quality is low. However, depending on the situation, even if the wireless communication device can quickly switch to another AP after transitioning to roaming mode, the scan results may be old, resulting in suboptimal AP selection and poor transmission quality. If the wireless communication device is located inside a high-speed moving vehicle, or if the moving distance of the wireless communication device is very long, or if the scan time is too long, the scan results may quickly become outdated. Techniques to solve such problems include reducing the number of channels for scanning in addition to reducing the moving speed of the wireless communication device. The advantage of such a technique is that the scan time is shortened instead of reducing the system bandwidth.

[0004] Also, the task of scanning channels can take a long time. Currently, each dynamic frequency selection (DFS) channel may require at least 300 milliseconds (ms) to complete a scan, and each non-DFS channel may require 100 ms to complete a scan. If the wireless communication device has to scan 15 non-DFS channels and 16 DFS channels, it takes about 100 ms × 15 + 300 × 16 = 6300 ms to complete a series of scans. A long scan time is likely to cause problems when the wireless communication device is moving at high speed. Assume that the wireless communication device is moving at a train speed of 22 m / s. After 3.6 seconds, it may have moved 79.2 meters. Since the wireless communication device may already be far from the AP it last connected to, such a long distance may reduce the signal strength and degrade the transmission quality.

[0005] Also, a high moving speed may lead to a requirement for a high sampling speed, and thus it is necessary to reduce the number of channels to be scanned in order to shorten the scan time. However, a decrease in the number of channels to be scanned reduces the overall system bandwidth available to the user. Assuming that the user can originally use 20 channels, restricting the number of channels to be scanned to 3 channels reduces the system bandwidth to 3 / 20 = 15%, leading to a decrease in network capacity. This forces the user to compromise between the moving speed and the available network capacity.

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a wireless communication device is in the roaming mode, the signal strength of the wireless connection to the original AP may continue to decrease, and correspondingly, the data speed of the wireless connection may decrease. If it takes too much time to scan for alternative channels, there may be a gap in which the wireless communication device is not connected to any AP in its wireless connection. Therefore, it is beneficial to shorten the time required for the wireless communication device to connect to the next AP.

Means for Solving the Problems

[0007] Accordingly, the present invention is directed to a method used by a wireless communication device to connect to an access point and a wireless communication device using the same.

[0008] In one aspect, the present invention is directed to a method used by a wireless communication device to connect to an access point. The method includes, but is not limited to, establishing a first wireless connection to a first access point, determining whether the first wireless connection of the wireless communication device meets roaming criteria, obtaining a subset of a history record stored in the wireless communication device based on the first access point, ranking access points in the subset of the history record to generate a list of ranked access points for obtaining a score of an access point based on the history record, selecting a second access point based on the list of ranked access points, and establishing a second wireless connection to the second access point.

[0009] In one aspect, the present invention is directed to a wireless communication device including, but not limited to, at least a wireless transceiver electrically connected to a processor. The processor is configured to at least establish a first wireless connection via the wireless transceiver, determine whether the first wireless connection of the wireless communication device meets roaming criteria, obtain a subset of a history record stored in the wireless communication device based on the first access point if the roaming criteria are met, rank access points in the subset of the history record to generate a list of ranked access points for obtaining a score of an access point based on the history record, select a second access point based on the list of ranked access points, and establish a second wireless connection to the second access point via the wireless transceiver.

Advantages of the Invention

[0010] The present invention is suitable for use in a wireless communication system and can shorten the time for a wireless communication device to connect to a new access point when the roaming criteria are met.

Brief Description of the Drawings

[0011] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated herein and form a part thereof. The drawings represent embodiments of the present invention and serve to explain the principles of the present invention together with the specification.

[0012]

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DETAILED DESCRIPTION OF THE INVENTION

[0013] Refer to the exemplary embodiments of the present invention in detail, and the examples thereof are shown in the accompanying drawings. The same reference numerals are used throughout the drawings and the specification to refer to the same or similar parts as much as possible.

[0014] In the following description, measurement data for an AP or a channel is measured and recorded by a wireless communication device. For each AP, the measurement data may include one or more elements such as signal strength typically measured in decibels (dB), received signal strength indicator (RSSI), signal-to-noise ratio (SNR), channel state information (CSI), 802.11mc fine timing measurement (FTM) / timestamp (TM), distance information obtained via CSI, SNR, RSSI, etc. For each channel, the measurement data may include one or more elements such as spectrum analysis results, noise floor, channel utilization, and the number of APs operating on the channel. The spectrum analysis results are for providing information regarding channel interference. Each entry in the history record may be associated with the media access control (MAC) address of an AP, and the measurement data for a channel may be recorded for each AP operating on that channel. For example, assuming that both AP1 and AP2 are operating on channel 6 with 50% channel utilization, the history record is a log as shown in the following record: AP1 MAC, Channel 6, Channel Utilization 50% AP2 MAC, Channel 6, Channel Utilization 50% The elements of the measurement data may vary according to the design and are not limited herein.

[0015] A metric may be obtained based on one of the elements of the measurement data for an AP or a channel. For example, but not limited to, one of the elements is selected as the metric, or multiple elements are summed by simple additive weighting to obtain the metric.

[0016] The historical records stored in the wireless communication device are a set of past measurement data. The historical records may include measurement data of channels associated with each AP in the list of APs. When the wireless communication device is connected to one AP (for example, the first AP), the past measurement data of other APs is also recorded in the wireless communication device, and the past measurement data of other APs recorded in the wireless communication device is called a "subset of the historical record". That is, each subset of the historical record corresponds to a different connected AP.

[0017] As described above, a wireless communication device moving at a certain speed may need to switch from a first (wireless) AP to a second (wireless) AP in order for the wireless communication device to continue to connect to the network when, for example, the wireless communication device moves away from the first AP or the channel state between the wireless communication device and the AP deteriorates. When the wireless communication device meets the roaming criteria, the wireless communication device may need to switch to the second AP. Assume that after the wireless communication device connects to the first AP, the wireless communication device detects the first measurement data of the first AP. The roaming criteria may include, for example, one or more of a signal strength threshold, an RSSI threshold, an SNR threshold, a CSI threshold, etc. When the first wireless connection between the wireless communication device and the first AP meets the roaming criteria (for example, the RSSI of the first wireless connection is lower than the RSSI threshold, or other first metrics already do not meet the threshold), the wireless communication device may need to search for a candidate AP as the second AP in order to continue to connect to the network. In order to effectively maintain the connection to the network, the present invention provides a method used by the wireless communication device to connect to an access point and a wireless communication device using the same.

[0018] One of the inventive concepts is shown in the flowchart of FIG. 1. Referring to FIG. 1, assume that the wireless communication device has established a wireless connection to the first access point.

[0019] In step S102, the wireless communication device determines whether the first wireless connection of the wireless communication device meets the roaming criteria based on the real-time measurement data. For example, the wireless communication device may continuously or periodically detect the SNR or RSSI of the first wireless connection to determine whether the SNR has dropped below the SNR threshold or whether the RSSI has dropped below the RSSI threshold. In another example, a metric may be further obtained based on the measurement data of the first wireless connection, and the wireless communication device determines whether the metric of the wireless communication device meets the roaming criteria.

[0020] In step S103, if the roaming criteria are met, the wireless communication device may obtain a subset of the history records based on the first access point. In other words, after the roaming criteria are met, this situation triggers the wireless communication device to search for candidate APs in the list of APs based on a subset of the history records. In this example, the wireless communication device is connected to the first AP in step S101, and therefore, the subset of the history records is the past measurement data of each AP recorded by the wireless communication device when connected to the first AP.

[0021] In step S104, in order to generate a list of ranked access points by obtaining the score of an AP based on the history record, the wireless communication device may perform ranking of the access points in a subset of the history record. The ranking of the access points may be performed on some APs, for example, by filtering the list of APs under a predetermined condition, rather than on the entire list of APs. For example, APs with channel utilization higher than 90% in the list of APs are excluded by filtering. For the APs not excluded by filtering, respective metrics of the APs are obtained based on past measurement data. The ranking of these APs may be performed based on the ranking of their respective metrics. Since there may be multiple metrics for one AP, the ranking of the APs may be performed based on the metrics via a simple additive weighting method or a multi-level sort. The additive weighting method may be implemented by the sum of the weighted multiple metrics, and each metric is multiplied by a predetermined weight (for example, weight 1 × the first metric + weight 2 × the second metric +... = score). After a score is calculated for each AP not excluded by filtering, the APs are ranked based on their respective scores.

[0022] In step S105, the wireless communication device may select a second AP based on the list of ranked access points. Step S105 may be performed based on the first exemplary embodiment or the second exemplary embodiment described later. In step S106, after the second AP is selected, the wireless communication device may establish a second wireless connection with the second AP and subsequently disconnect the first wireless connection.

[0023] For the first exemplary embodiment, the wireless communication device may select a second AP by obtaining (i.e., performing a scan) real-time measurement data of the APs based on a list of ordered channels. In step S201, the wireless communication device may obtain a list of channels based on the ranked list of access points. In other words, each AP in the ranked list of APs has one channel pre-assigned that constitutes the list of channels to be ordered. In step S202, the wireless communication device may generate a list of channels to be ordered from the list of channels. The channels may be ordered based on an order that matches the ranked list of APs. In step S203, the wireless communication device may collect real-time measurement data and corresponding metrics of at least some of the channels and corresponding APs in the ordered list of channels in an order that matches the list order of the ordered list of channel lists. Note that the channel list is based on the order specified in the ranked list of APs, and APs with more favorable history scores are scanned before APs with less favorable history scores. In step S204, the wireless communication device obtains an AP score based on the real-time measurement data and the history record.

[0024] Specifically, to obtain real-time measurement data of the APs, the wireless communication device may perform operations (e.g., scans, FTM, etc.) to obtain real-time measurement data of some or all of the channels in the ordered list of channels based on the order specified in the ordered list of channels.

[0025] Specifically, the wireless communication device may hop to the first channel of the ordered channels and then perform scanning, FTM, etc. Spectrum scanning and channel analysis may also be performed sequentially or simultaneously. Next, the wireless communication device may hop to the second channel of the ordered channels and perform a scan. Similarly, the wireless communication device may hop to the remaining channels and perform scans respectively. The real-time measurement data is applied to the AP associated with the channel. For example, if AP1 and AP2 are on channel 1, the real-time record of the channel is recorded for both AP1 and AP2.

[0026] Accordingly, the real-time score of each AP may be obtained based on the real-time measurement data of the channel and the corresponding metrics via scanning, and the real-time ranking may be performed by the wireless communication device based on the real-time scores of each AP and the ranking of the history records. As another example, the real-time score of each AP may be obtained based on both the real-time measurement data and its corresponding metrics via scanning and the past measurement data and its corresponding metrics, but is not limited thereto.

[0027] According to step S204, the wireless communication device may calculate the scores of the APs associated with some or all of the channels in the ordered list of channels by applying the weighted sum of the collected real-time metrics and the metrics stored in the respective history records of some or all of the channels, based on the metrics obtained from the scanned APs and the scanned channels. Also, the wireless communication device does not have to obtain the real-time metrics of all the channels in the ordered list of channels, and it may only be necessary to obtain the real-time metrics of a predetermined number of channels and a predetermined number of associated APs. Specific examples will be provided later in the present invention. Since the wireless communication device does not have to obtain the real-time measurement data of all the channels in the ordered list of channels and it may only be necessary to obtain the real-time metrics of a predetermined number of channels and a predetermined number of associated APs, time for switching to another AP is saved. Specific examples will be provided later in the present invention.

[0028] The second exemplary embodiment is applicable to emergency situations such as when wireless communication is lost or just before the network connection is lost, and it is necessary to urgently connect to an alternative AP. Referring to FIG. 3, at step S301, the wireless communication device detects an emergency situation (for example, the connection is lost, or the RSSI / SNR is much lower than the RSSI threshold / SNR threshold). At step S302, the wireless communication device may select one AP based only on the list of ranked access points generated from step S104 without requiring real-time measurement data (i.e., without performing a scan or measurement). For example, the wireless communication device may select and connect to the AP with the best historical score based on the list of ranked access points without obtaining real-time measurement data. At step S303, if the connection to the AP with the best historical score fails, the wireless communication device may select and connect to the AP with the next-best score based on the list of ranked access points. Essentially, according to the second exemplary embodiment, the wireless communication device may refer to past measurement data stored in the storage device to generate a ranked AP list in response to the roaming criteria being met (for example, steps S103, S104 in FIG. 2). Next, the wireless communication device may select candidate APs from the historical record based on the AP with the best score from the ranked AP list. The decision may be made without performing real-time metric measurements, or may be made by performing a small number of measurements as long as the results of the measurements are acceptable.

[0029] FIG. 4 represents a hardware block diagram of a wireless communication device 400 according to one exemplary embodiment of the present invention. The wireless communication device may include, but is not limited to, a processor 401 connected to a transceiver 402 and a storage device 403. The processor 401 may be a central processing unit (CPU), a microprocessor, a microcontroller, a field programmable gate array (FPGA), a graphics processing unit (GPU), a customized integrated circuit, or a device with similar functions.

[0030] The transceiver 402 may include one or more wired or wireless transceiver modules. For example, the transceiver 402 may include a wireless transceiver that enables the wireless communication device 400 to receive data at RF or millimeter wave frequencies. For example, the transceiver 402 may include a WiFi or Bluetooth transceiver compliant with the 802.XX standard. For example, the transceiver 402 may include a USB port or interface for facilitating cable connection. For example, the transceiver 402 may include a short-range wireless transceiver such as a Near Field Communication (NFC) transceiver.

[0031] The storage device 403 may be a non-volatile storage medium for storing non-volatile information such as flash memory, a hard disk drive (HDD), a read-only memory (ROM), etc. The information to be stored may include information such as the above-described history record and program code that is loaded into the processor 401 to execute the functions described in the specific examples of FIGS. 1 to 3 and FIGS. 5 and 6.

[0032] FIG. 5 is a specific example related to the first exemplary embodiment. Assume that the wireless communication device (e.g., 400) is located in a mobile or stationary environment and is connected to a first AP via a first wireless connection. In the first graph 501 of FIG. 5, assume that it takes time S1 to scan all channels in one cycle and time S2 to scan the channels in another cycle. The periods of S1 and S2 are currently about 6250 ms. Assume that there are 15 non-DFS channels and 16 DFS channels respectively, and the scan for each of S1 and S2 is, for example, (15×150 ms + 16×250 ms) = 6250 ms. If the scan time is too long, the metric 511 of the first AP will significantly decrease due to the moving speed of the wireless communication device until the wireless communication device detects that the metric 512 of the second access point at the second time point T2 is close to the roaming criterion. Therefore, the wireless communication device may lose its network connection.

[0033] The second graph 502 in FIG. 5 presents a solution to the above-described problem by shortening the scan time from SI and S2 to S3 and S4. In this method, while the metric 513 of the first AP decreases as the wireless communication device moves away from the first AP, when the metric 514 of the first AP drops below the roaming criterion at the third time point T3, the wireless communication device may start searching for an alternative AP's channel in the time of S3 in one cycle, and then search for another AP's channel in the time of S4 in another cycle. Since the times of S3 and S4 are short, the wireless communication device at the fourth time point can find a suitable AP by detecting the acceptable real-time metric 514 of the second AP while the real-time metric 513 of the first AP has not dropped too low. Therefore, one of the objectives of the present invention is to shorten the time for the wireless communication device to connect to an alternative AP.

[0034] When a user activates the wireless function (e.g., WiFi) of a wireless communication device such as a laptop or a mobile phone, numerous WiFi APs can be detected by the wireless communication device when it is located in a densely populated urban area. However, some channels or WiFi APs have low metrics and low connection priorities for the wireless communication device. The present invention discloses the use of historical records and real-time data not only to filter out unwanted channels and APs but also to re-prioritize the order of channels to be scanned by the access point. By filtering out unwanted channels of the access point and re-ordering the scan order, the scan time per scan cycle can be shortened. In this way, the detection time can be reduced, and the full network capacity can be available when operating at high speed.

[0035] As an example, assume that a wireless communication device (e.g., 400) is connected to a first AP via a first wireless connection that meets roaming criteria (e.g., 521, 522) (e.g., S101). For example, the SNR or RSSI of the first wireless connection may be lower than a predetermined SNR threshold or a predetermined RSSI threshold. The wireless communication device continues to determine whether the measurement data of the first wireless connection meets the roaming criteria (S102). Next, the wireless communication device may refer to a storage device (e.g., 403) to obtain a subset of the history record that includes the AP and the history of the measurement data of the channel corresponding to the AP (S103). For example, the history record may record AP1, AP2, AP3, AP4, AP5, AP6, and the channels corresponding to them, and the subset of the history record may be the record of the AP while the communication device is connected to the first AP. Further, since the channel utilization rate of AP1 and AP2 is higher than a predetermined channel utilization threshold, e.g., 90%, they are excluded by filtering. Next, ranking of the APs in the subset of the history record is performed based on those history metrics recorded when measurements were made in the past, thereby generating a ranking list of access points (S104). Specifically, the ranking list of APs includes AP3, AP4, AP5, AP6, and is in the order where AP3 has the best score. Next, assume that AP3 corresponds to channel 36, AP4 corresponds to channel 11, AP5 corresponds to channel 36, and AP6 corresponds to channel 1 (S201). The ordered list of channels (S202) is in the order including channel 36, channel 11, channel 1 based on the ranked APs. Since there are no duplicate channels in the ordered list of channels, the second instance of channel 36 (i.e., AP5 corresponding to channel 36) is not included in the ordered list of channels.

[0036] Next, assuming that the wireless communication device encounters a non-emergency situation, the wireless communication device acquires real-time measurement data by performing, for example, scans, FTM, and spectrum scans on channels 36, 11, 1, and the corresponding APs (S203). According to one exemplary embodiment, the wireless communication device may perform scans in the same order as the list of ordered channels. This means that the order of channel scans is in the order of channel 36, channel 11, and channel 1. More specifically, the communication device first hops to channel 36 and performs interactions (such as scans, FTM, etc.) with channel 36 and the APs in channel 36 (for example, AP3 and AP5). Next, the communication device hops to channel 11 and performs interactions with channel 11 and the AP in channel 11 (for example, AP4). Next, the communication device hops to channel 1 and performs interactions with channel 1 and the AP in channel 1 (for example, AP6). According to one exemplary embodiment, the wireless communication device may perform scans only on a part of the listed or ordered channel list and the corresponding APs. Thus, the wireless communication device may only need to perform scans on channels 36 and 11 and APs 3 and 4, excluding channel 1 and AP6.

[0037] After performing the collection of the above-described real-time measurement data and its corresponding metrics, the wireless communication device may obtain an AP score based on the real-time measurement data and past measurement data (S204). The score may be based on multi-criteria decision-making (MCDM) such as a simple additive weighting method or machine learning, or other methods that can solve MCDM. After applying one or more of these methods, each AP is assigned a score. The wireless communication device selects the AP with the highest score to establish a new wireless connection.

[0038] FIG. 6 shows an example of applying a simple additive weighting method to determine an AP having the highest score. Similar to the above example, the candidate APs to be considered include AP3, AP4, and AP6, and four criteria are used to rank the APs, but it should be noted that the present invention does not limit the ranking of APs to these criteria. In this example, the first criterion is the roaming record from the history record, the second criterion is the RSSI of each of AP3, AP4, and AP6, the third criterion is the noise floor of channels 36, 11, and 1 corresponding to AP3, AP4, and AP6, and the fourth criterion is the channel utilization of channels 36, 11, and 1. The second, third, and fourth criteria may be either the history record or the measured real-time metric. For each AP, a cumulative score is obtained by multiplying each criterion by its weighting factor. For example, the cumulative score of AP3 is determined by the sum of the multiplication of the first roaming record by the first weighting factor (W1), the multiplication of the first RSSI by the second weighting factor (W2), the multiplication of the first noise floor by the third weighting factor (W3), and the multiplication of the first channel utilization by the fourth weighting factor (W4). Also, the sum of the weighting factors W1, W2, W3, and W4 is 1. As an example, W1 = 0.2, W2 = 0.15, W3 = 0.4, W4 = 0.25, but the present invention does not limit the values of these weighting factors.

[0039] As another example, assume that a wireless communication device detects an emergency situation such as the disconnection of a first wireless connection with a first AP (S301). In this example, assume that the wireless communication device executes steps S101 to S103, obtains APs AP3, AP4, and AP6 in the ranked list of APs, and obtains channels 36, 11, and 1 in the ordered list of channels. Next, since AP3 has the best score based on the ranked access points generated in step S104, the wireless communication device may select AP3. Therefore, the wireless communication device may directly connect to AP3 without performing any measurements (S302). If the connection to AP3 fails, since AP4 has the second-best score in the ranked list of access points, the wireless communication device may attempt to connect to AP4 (S303).

[0040] Also, the history record may be updated periodically, and old channels or access points in the history record may be deleted. For example, when the wireless communication device has a wireless connection with a sufficiently high metric such as an SNR higher than a threshold, the wireless communication device may perform a complete channel scan on detectable channels every predetermined period (e.g., 5 or 10 minutes), and subsequently update the history record accordingly. After performing a complete scan, APs with low scores may be removed from the history record. Also, undetectable or non-updatable APs may be removed from the history record. There is a predetermined aging time associated with the history record. Data obtained before the predetermined aging time may be removed from the history record.

[0041] Elements, acts, or instructions used in the detailed description of the disclosed embodiments of the present application should not be construed as absolutely important or essential to the present invention unless explicitly stated.

[0042] It will be apparent to those skilled in the art that various modifications or variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the present invention. In view of the above, the present invention is intended to embrace modifications and variations of the present invention as long as they are within the scope of the claims and the equivalents thereof.

Industrial Applicability

[0043] The present invention is suitable for use in a wireless communication system and can shorten the time for a wireless communication device to connect to a new access point when the roaming criteria are met.

Explanation of Signs

[0044] S101 to S106: Method steps S201 to S204: Method steps S301 to S303: Method steps 401: Processor 402: Transceiver 403: Storage device 404: Antenna 501: First graph 502: Second graph 511: Metric of the first AP of the first graph 512: Metric of the second AP of the first graph 513: Metric of the first AP of the second graph 514: Metric of the second AP of the second graph 521: Roaming criteria of the first graph 522: Roaming criteria of the second graph T1: First time point T2: Second time point T3: Third time point T4: Fourth time point S1: Time S2: Time S3: Time S4: Time

Claims

1. A method used by a wireless communication device to connect to an access point, comprising: establishing a first wireless connection to a first access point; determining whether the first wireless connection of the wireless communication device meets roaming criteria; if the roaming criteria are met, obtaining a subset of a history record stored in the wireless communication device, the history record including a record of past measurement data of access points when the wireless communication device was connected to the first access point; ranking the access points in the subset of the history record to generate a list of ranked access points for obtaining the score of the access point based on the history record; selecting a second access point based on the list of ranked access points; establishing a second wireless connection to the second access point including a method.

2. Obtaining a list of channels from the list of ranked access points, wherein each channel in the list of channels corresponds to one of the access points in the list of ranked access points; generating an ordered list of channels from the channels in the list of channels based on an array that matches the order of the list of ranked access points further comprising the method according to claim 1.

3. collecting real-time measurement data of at least some of the access points and at least some of the channels in the ordered list of channels; obtaining the score of the access point based on the collected real-time measurement data and the history record; selecting a second access point having the highest score further comprising the method according to claim 2.

4. The real-time measurement data of each of the at least some access points includes one or more of channel state information (CSI), signal-to-noise ratio (SNR), and received signal strength indicator (RSSI). the method according to claim 3.

5. For each of at least some of the channels in the ordered list of channels, the respective real-time measurement data includes one or more of spectral analysis results, noise floor, channel utilization, and the number of access points per channel. The method according to claim 3.

6. Detect an emergency situation, where the emergency situation includes a situation where the wireless communication device is about to lose the first wireless connection with the first access point. Selecting the second access point based on the ranked list of access points, including selecting the second access point based on the ranked list of access points without real-time measurement data. Further comprising The method according to claim 1.

7. Detecting that the second wireless connection with the second access point has failed. Selecting a second-best access point based on the ranked list of access points to handle the failure of the second access point. Further comprising The method according to claim 6.

8. The roaming criteria includes at least one of a signal strength threshold, a signal-to-noise ratio (SNR) threshold, a received signal strength indicator (RSSI) threshold, a channel state information (CSI) threshold, and a distance information threshold. The method according to claim 1.

9. A wireless communication device, A wireless transceiver, Coupled to the wireless transceiver, at least Establish a first wireless connection to a first access point via the wireless transceiver. Determine whether the first wireless connection of the wireless communication device meets the roaming criteria. If the roaming criteria are met, obtain a subset of the history records stored in the wireless communication device, where the history records include a record of past measurement data of the access points when the wireless communication device was connected to the first access point. Rank the access points in the subset of the history records to generate a ranked list of access points by obtaining the scores of the access points based on the history records. Select a second access point based on the ranked list of access points. Establish a second wireless connection to the second access point via the wireless transceiver. A processor configured as such and including a wireless communication device.

10. In response to generating the ranked list of access points, the processor obtains a list of channels from the ranked list of access points, where each channel in the list of channels corresponds to one of the access points in the ranked list of access points; and generates a ranked list of channels from the channels in the list of channels based on an array that matches the order of the ranked list of access points and is further configured as such. The wireless communication device according to claim 9.

11. The processor collects real-time measurement data of at least some of the access points and at least some of the channels in the ranked list of channels, obtains a score of the access point based on the collected real-time measurement data and the history record, and selects a second access point having the highest score and is further configured as such. The wireless communication device according to claim 10.

12. The real-time measurement data of each of the at least some of the access points includes one or more of distance information, channel state information (CSI), signal-to-noise ratio (SNR), and received signal strength indicator (RSSI). The wireless communication device according to claim 11.

13. The real-time measurement data of each of the at least some of the channels in the ranked list of channels includes one or more of spectrum analysis results, noise floor, channel utilization, and the number of access points per channel. The wireless communication device according to claim 11.

14. The processor detects an emergency situation, which includes a situation where the wireless communication device is about to lose the first wireless connection with the first access point, and in response to detecting the emergency situation, selects the second access point based on the ranked list of access points without real-time measurement data and is further configured as such. The wireless communication device according to claim 9.

15. The processor In response to the failure of the second wireless connection with the second access point, select a second-best access point based on the ranked list of access points. It is further configured as follows. The wireless communication device according to claim 14.

16. The roaming criterion includes at least one of a signal strength threshold, a signal-to-noise ratio (SNR) threshold, a received signal strength indicator (RSSI) threshold, a channel state information (CSI) threshold, and a distance information threshold. The wireless communication device according to claim 11.

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