Method and apparatus for establishing and terminating a wireless link

Abstract

The invention relates to a method and apparatus for establishing and terminating a wireless link. The apparatus initiates a connection procedure to establish a wireless connection between the wireless communication apparatus and the access point, and the connection procedure includes (i) selecting a set of degraded uplink transmission quality parameters corresponding to a higher signal-to-noise ratio (SNR) as compared to a set of baseline uplink transmission quality parameters, and (ii) sending messages from the wireless communication apparatus to the access point during the connection procedure in accordance with the set of degraded uplink transmission quality parameters. Despite the wireless communication apparatus sending messages to the access point during the connection procedure in accordance with the set of degraded uplink transmission quality parameters, the wireless network connection can be established between the wireless communication apparatus and the access point as a result of the connection procedure being completed.

Description

[0001] Case Analysis

[0002] This application is a divisional application of Chinese Invention Patent Application No. 201880036692.1, filed on December 14, 2018. Technical Field

[0003] This invention relates to methods and apparatus for establishing and terminating wireless links. Background Technology

[0004] Wireless communication devices connect to wireless networks by broadcasting access points within their range. While access points are often fixed in location, end-user wireless devices such as smartphones, tablets, and laptops are often mobile and frequently move in and out of the coverage areas of different access points and wireless networks. Additionally, even when mobile devices maintain their location for an extended period while connected to a particular wireless network, external events and environmental changes can cause fluctuations in connection quality.

[0005] To manage these changing conditions, wireless communication devices may include a connection manager that detects wireless networks or access points near the device and determines when to connect to a network or access point based on indications of network or access point quality. For example, some wireless communication devices are configured to connect to an access point if the received signal strength from the transmission meets a predefined static threshold. If several access points are detected within range of the device, the connection manager may also select a specific network to connect to. Summary of the Invention

[0006] This specification describes systems, methods, apparatuses, and other techniques for managing connections between wireless communication devices and access points. The quality of a wireless connection involving bidirectional communication between a wireless communication device and an access point depends on both the wireless communication device's ability to successfully receive downlink transmissions from the access point and the access point's ability to successfully receive uplink transmissions from the wireless communication device. However, when a wireless communication device evaluates whether to connect to an access point it has detected, information regarding the quality or range of the uplink is often unavailable to the wireless communication device. For example, if the downlink transmission power level from the access point significantly exceeds the uplink transmission power level from the wireless communication device, the wireless communication device can initiate a connection to the access point based on the relatively high received signal strength detected by the wireless communication device, even if the uplink transmission quality is low. Therefore, even if a connection is established between the wireless communication device and the access point, there may be relatively little margin for fading, and the connection performance may be compromised.

[0007] This specification describes techniques for wireless communication devices to manage connections with access points (and the corresponding wireless networks) in a manner that takes into account both uplink and downlink transmission quality. These techniques may be applied when determining whether to initiate a connection with the access point, or, if a connection has already been established, when determining whether to maintain the connection.

[0008] In some implementations, the wireless communication device is configured to increase the SNR required for uplink transmission during the connection phase, thereby providing a margin in SNR that allows for the mitigation of potential fading during the wireless connection process by degrading the quality of the transmission from the wireless communication device to the access point as the wireless communication device attempts to establish a connection. The wireless communication device may, for example, reduce its transmission power, use a more complex modulation scheme, or both, during the connection process to establish a link with the access point. If a reduced uplink transmission quality is available to establish the link, the wireless communication device can then increase its transmission power and / or use a more robust modulation scheme for transmission once the link is established, thus providing a margin for uplink transmission. In this way, the device can reduce the uplink transmission quality during the connection phase (e.g., by reducing uplink transmission power and / or using a more complex modulation scheme) so that the access point can successfully receive transmissions requiring a higher level of SNR.

[0009] In some implementations, the wireless communication device is configured to determine specific entry criteria for connecting to different wireless networks, access points, and / or frequency channels. The device may also determine exit criteria for disconnecting, as further described below. Entry criteria may be based on indications of relative success in the history of successful connections to a particular network, access point, and / or channel by the wireless communication device (or other wireless communication devices). For example, the wireless communication device may maintain a database storing the ratios at which the wireless communication device (or other wireless communication devices) previously connected to different networks, access points, and / or channels at each of a plurality of different downlink transmission quality levels. Additionally or alternatively, the database may be maintained on one or more servers remote from the wireless device. When the wireless communication device later detects an available network, access point, and / or channel, it may compare the downlink transmission quality level of the transmissions from the detected network, access point, and / or channel with a threshold quality level for the detected network, access point, and / or channel, where the threshold quality level is based on the historical ability to connect to that network, access point, and / or channel with a minimum specified success rate. For example, if the historical success rate of connecting to a first access point with an RSSI of -70 dBm is high enough, the wireless communication device may choose to connect to the first access point where the detected transmission has an RSSI (Received Signal Strength Index) of -70 dBm. However, if the historical success rate of connecting to a second access point with an RSSI of -70 dBm does not meet the minimum specified level, the device may choose not to connect to the second access point where the detected transmission has an RSSI of -70 dBm. In some examples, the wireless communication device may be configured to initiate a connection to an access point if the downlink transmission has an RSSI that meets a predefined default RSSI. However, it may also be configured to lower the default RSSI threshold if the connection history indicates a sufficiently high success rate of connecting to that access point (e.g., on a specific wireless network and / or channel) at low RSSI levels (e.g., at the default RSSI threshold). If the lowered threshold continues to allow for a high success rate when connecting to the access point, the wireless communication device may maintain or further lower the threshold; otherwise, if a specified minimum connection success rate is required, the threshold may be restored to the default RSSI threshold or even increased above the initial default threshold. In some implementations, the database can be indexed by user and network location and / or by other contexts indicating preferred network and network performance on different days of the week, at different times of the day, and whether the user / device is indoors or outdoors.

[0010] Due to the potential for fading in the wireless connection between the wireless communication device and the access point, the wireless communication device can also be configured to monitor the health of the connection and terminate it if the connection performance degrades sufficiently over time (e.g., subsequently connecting to a different access point or network that can provide better service). One factor that the wireless communication device can consider when determining whether to maintain or terminate the connection is the downlink transmission power level of the transmission from the access point. If the downlink transmission power level (e.g., as measured by the wireless communication device as the downlink RSSI) drops below a power level threshold over a period of time, the wireless communication device can initiate a process to terminate the connection with the access point. However, when the downlink power is strong enough but the uplink power is not strong enough (e.g., due to the difference in transmission power between the access point and the wireless communication device), evaluating only the downlink transmission power level may allow the wireless communication device to maintain the connection.

[0011] Therefore, in some implementations, the wireless communication device can determine the termination criteria for the wireless link based on both the downlink transmission quality (e.g., power level and / or modulation scheme) from the perspective of the wireless communication device and the uplink transmission quality from the perspective of the access point. The wireless communication device can set the termination criteria for terminating the wireless communication device based on a comparison of the downlink and uplink transmission quality. Thus, if there is a significant difference between the uplink and downlink transmission quality (e.g., if the RSSI of the uplink transmission measured by the access point is lower than the RSSI of the downlink transmission measured by the wireless communication device), the wireless communication device can adjust the baseline termination criteria (e.g., increase the downlink termination RSSI threshold) such that if a valid communication channel can no longer be provided for either the wireless communication device or the access point in either communication direction, the wireless communication device terminates the connection.

[0012] In some implementations, the wireless communication device may not have direct access to information about the received signal strength of the uplink transmission at the access point or about other transmission quality parameters. In these cases, the wireless communication device can infer the quality of the uplink transmission received by the access point based on the characteristics of the downlink transmission corresponding to the successful uplink transmission received from the access point. For example, if the wireless communication device sends a packet to the access point and receives an acknowledgment indicating that the packet was successfully transmitted, the wireless communication device can measure one or more quality parameters of the transmission containing the acknowledgment to estimate the access point's perception of the health of the wireless link. If the access point transmits with a lower modulation and coding scheme (e.g., MCS0), the wireless communication device can infer that the received signal strength of the uplink transmission at the access point is relatively low. Therefore, the wireless communication device can adjust the exit criteria for terminating the wireless connection, for example, by increasing the exit RSSI threshold. In some implementations, the device can send multiple packets to the access point, each packet having a different MCS. The device can then track which of those packets (and their corresponding MCSs) are acknowledged, thereby providing the device with an indication of the current uplink signal quality (e.g., the received signal strength of the uplink transmission at the access point).

[0013] The techniques described herein can achieve one or more advantages in some implementations and in certain situations. First, by degrading the uplink transmission quality relative to the baseline quality during the connection process, the wireless communication device can ensure that any resulting connection will have an additional margin to offset transmission fading that may occur during the wireless connection process. Second, by adjusting the entry criteria for connecting to the access point based on historical information about the downlink transmission quality level that led to a successful connection, the wireless communication device can increase the likelihood of successfully connecting to the access point at a later time (e.g., for a specific wireless network and / or on a specific frequency channel) and reduce the likelihood of establishing a poor-quality connection. Third, by adjusting the exit criteria for initiating the termination of an existing / ongoing wireless connection based on a comparison of uplink quality parameters and downlink transmission quality parameters, the wireless communication device can more effectively determine when to maintain or terminate the wireless connection. For example, instead of simply measuring the received signal strength of the downlink transmission, which risks maintaining a poor connection where the wireless communication device is within the downlink range of the access point but the access point is not within the uplink range of the wireless communication device, an exit threshold for the received signal strength of the downlink transmission can be increased if there is a gap between the received signal strength of the uplink and downlink transmissions. Fourth, wireless communication devices can select better-performing access points for connection by applying different access criteria specific to individual access points.

[0014] In a first aspect, some embodiments of the subject matter disclosed herein include a computer-implemented method relating to actions for performing the following steps: identifying an access point for a wireless network via a wireless communication device; initiating a connection process via the wireless communication device to establish a wireless connection between the wireless communication device and the access point, including: (i) selecting a set of degraded uplink transmission quality parameters corresponding to a higher signal-to-noise ratio (SNR) compared to a set of baseline uplink transmission quality parameters; and (ii) sending a message from the wireless communication device to the access point according to the set of degraded uplink transmission quality parameters during the connection process; and establishing the wireless connection between the wireless communication device and the access point as a result of the completion of the connection process, although the wireless communication device sends a message to the access point according to the set of degraded uplink transmission quality parameters during the connection process. The set of degraded uplink transmission quality parameters can be described as corresponding to a higher signal-to-noise ratio (SNR) because messages sent according to those parameters may require a higher SNR for successful reception.

[0015] These and other implementations may optionally include one or more of the following features.

[0016] The set of degraded uplink transmission quality parameters may include a reduced uplink power transmission level, which is lower than the baseline uplink power transmission level. Sending the message from the wireless communication device to the access point during the connection process may include sending the message at the reduced uplink power transmission level.

[0017] The set of degraded uplink transmission quality parameters may include a specific modulation scheme that is rated as more complex than the baseline modulation scheme, and sending the message from the wireless communication device to the access point during the connection process may include using the specific modulation scheme to send the message.

[0018] The set of degraded uplink transmission quality parameters can be assigned to a first modulation and coding scheme (MCS) index value, and the set of baseline uplink transmission quality parameters can be assigned to a second MCS index value. The first MCS index value assigned to the set of degraded uplink transmission quality parameters corresponds to a more complex modulation scheme compared to the second MCS index value assigned to the set of baseline uplink transmission quality parameters.

[0019] The method may further include actions for performing the following steps: identifying a second access point for a second wireless network via the wireless communication device; initiating a second connection process via the wireless communication device to establish a second wireless connection between the wireless communication device and the second access point, including: (i) selecting the set of degraded uplink transmission quality parameters that correspond to a higher signal-to-noise ratio (SNR) compared to the set of baseline uplink transmission quality parameters; and (ii) sending a message from the wireless communication device to the second access point during the second connection process according to the set of degraded uplink transmission quality parameters, wherein, as a result of the second connection process, the wireless communication device fails to establish the second wireless connection between the wireless communication device and the second access point.

[0020] The method may further include actions for determining the downlink transmission power level of the access point, wherein the set of baseline uplink transmission quality parameters is a set of default uplink transmission quality parameters mapped to the downlink transmission power level of the access point.

[0021] The method may further include actions for performing the following steps: after establishing the wireless connection between the wireless communication device and the access point, reconfiguring the wireless communication device to send messages to the access point via the wireless connection according to the set of baseline uplink transmission quality parameters.

[0022] The wireless communication device can identify the access point by actively scanning the access point, including (i) sending a probe message from the wireless communication device and (ii) receiving a response to the probe message from the access point at the wireless communication device. Sending a message from the wireless communication device to the access point during the connection process according to the set of degraded uplink transmission quality parameters may include sending the probe message from the wireless communication device according to the set of degraded uplink transmission quality parameters.

[0023] The wireless communication device can identify the access point through passive scanning. Sending messages from the wireless communication device to the access point during the connection process according to the set of degraded uplink transmission quality parameters may include sending messages according to the set of degraded uplink transmission quality parameters during at least one of the authentication phase or the association phase of the connection process.

[0024] The wireless communication device may be a mobile phone, a tablet computer, a laptop computer, or a smartwatch.

[0025] The method may further include actions for performing the following steps: determining, based on a comparison of the downlink transmission power level of the access point with a threshold power level, whether to initiate a connection process to establish the wireless connection between the wireless communication device and the access point.

[0026] The wireless communication device can identify the access point for the wireless network through the connection process by sending multiple probe messages, and can send at least some of the probe messages according to different sets of degraded uplink transmission quality parameters. The wireless communication device can track responses received from the access point to assess the adequacy of the set of degraded uplink transmission quality parameters for communicating with the access point.

[0027] In a second aspect, some embodiments of the subject matter disclosed herein include a computer-implemented method relating to actions for performing the following steps: identifying an access point for a wireless network via a wireless communication device; determining, via the wireless communication device, a downlink transmission power level of a transmission from the access point; identifying a threshold power level for initiating a connection to the access point, the threshold power level being based on the lowest downlink transmission power level previously attempted by the wireless communication device or another wireless communication device to connect to the access point with at least a threshold success rate; determining whether the downlink transmission power level of the transmission from the access point satisfies the threshold power level; and initiating a connection process for establishing a wireless connection between the wireless communication device and the access point via the wireless device and in response to determining that the downlink transmission power level of the transmission from the access point satisfies the threshold power level.

[0028] In a third aspect, some embodiments of the subject matter disclosed herein include a computer-implemented method for performing the following steps: establishing a wireless connection between a wireless communication device and an access point for a wireless network; identifying, via the wireless communication device, one or more downlink transmission quality parameters of a first set of transmissions from the access point to the wireless communication device via the wireless connection; identifying, via the wireless communication device, one or more uplink transmission quality parameters of a second set of transmissions via the wireless connection to the access point; determining a difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters; determining a criterion for initiating termination of the wireless connection based on the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters; determining whether the characteristics of the wireless connection between the wireless communication device and the access point satisfy the criterion for initiating termination of the wireless connection; and initiating termination of the wireless connection in response to determining that the characteristics of the wireless connection between the wireless communication device and the access point satisfy the criterion.

[0029] These and other implementations may optionally include one or more of the following features.

[0030] The one or more downlink transmission quality parameters may include the downlink transmission power level of the first set of transmissions from the access point to the wireless communication device, and the one or more uplink transmission quality parameters may include the uplink transmission power level of the second set of transmissions from the wireless communication device to the access point.

[0031] The downlink transmission power level of the first group of transmissions can be measured by the wireless communication device as the received signal strength of the first group of transmissions; and the uplink transmission power level of the second group of transmissions can be measured by the access point as the received signal strength of the second group of transmissions.

[0032] Identifying one or more uplink transmission quality parameters of the second group of transmissions may include requesting the access point to provide the wireless communication device with data indicating the one or more uplink transmission quality parameters.

[0033] Criteria for initiating termination of the wireless connection may include downlink transmission power levels from the access point to the wireless communication device not meeting threshold power levels.

[0034] The threshold power level may be an adjusted threshold power level, and the criteria for determining the termination of the wireless connection may include generating the adjusted threshold power level by applying an offset to a baseline threshold power level based on the difference between the downlink transmission power level of the first set of transmissions and the uplink transmission power level of the second set of transmissions.

[0035] The one or more downlink transmission quality parameters may include a first modulation scheme for the first set of transmissions from the access point to the wireless communication device, and the one or more uplink transmission quality parameters may include a second modulation scheme for the second set of transmissions from the wireless communication device to the access point.

[0036] Identifying one or more downlink transmission quality parameters of the first group of transmissions may include identifying the modulation and coding scheme (MCS) index value of the first group of transmissions, wherein the first modulation scheme is assigned to the MCS index value of the first group of transmissions; and identifying one or more uplink transmission quality parameters of the second group of transmissions may include identifying the MCS index value of the second group of transmissions, wherein the second modulation scheme is assigned to the MCS index value of the second group of transmissions.

[0037] Criteria for initiating termination of the wireless connection may include a downlink transmission power level from the access point to the wireless communication device that does not meet a threshold power level, and the method may further include determining the threshold power level based on an estimated difference in received signal strength between the first set of transmissions at the wireless communication device and the second set of transmissions at the access point, the estimated difference being determined using at least the MCS index value of the second set of transmissions.

[0038] In response to determining that the characteristics of the wireless connection between the wireless communication device and the access point do not meet the criteria, the wireless communication device may be configured to maintain the wireless connection for a period of time, rather than initiating the termination of the wireless connection.

[0039] In a fourth aspect, some embodiments of the subject matter disclosed herein include a computer-implemented method relating to actions for performing the following steps: establishing a wireless connection between a wireless communication device and an access point for a wireless network; identifying an uplink transmission successfully transmitted from the wireless communication device to the access point; determining a downlink transmission power level for a downlink transmission corresponding to the uplink transmission successfully transmitted from the wireless communication device to the access point; identifying a minimum acceptable uplink transmission quality level; determining a threshold downlink receive power level for initiating termination of the wireless connection between the wireless communication device and the access point, the threshold downlink receive power level being based on a downlink transmission power level at the receiver for one or more downlink transmissions corresponding to one or more of the uplink transmissions successfully transmitted from the wireless communication device to the access point at the minimum acceptable transmission quality level; and using the threshold downlink receive power level to determine whether to initiate termination of the wireless connection between the wireless communication device and the access point.

[0040] Each of the computer-implemented methods described herein can be additionally implemented as a computer program, which includes program instructions executable by a data processing apparatus in one or more wireless devices or other types of computers. The computer program can be stored on one or more computer-readable media. For example, one or more computer-readable media may be encoded with instructions that, when executed by a data processing apparatus (e.g., one or more processors), cause the data processing apparatus to perform any of the computer-implemented methods described herein. In some embodiments, the computer-readable media and the data processing apparatus are part of a computing system.

[0041] Details of specific embodiments are set forth in the following figures and detailed description. Additional features and advantages will be apparent to those skilled in the art to which this subject pertains. Attached Figure Description

[0042] Figure 1 This is a conceptual diagram illustrating the gap between the transmission range of a wireless communication device and a pair of access points.

[0043] Figure 2 This is a flowchart of an example process for establishing a wireless link between a wireless communication device and an access point using degraded uplink transmission during the connection process.

[0044] Figure 3 This is a flowchart of an example process for generating and applying access point, network, and / or channel-specific access criteria so that a wireless communication device can connect to that access point, network, and / or channel.

[0045] Figure 4 It is a table showing the history of successful and failed attempts by a wireless communication device to connect to various wireless networks at certain access points and on certain channels.

[0046] Figure 5 This is a flowchart illustrating an example process by which a wireless communication device adjusts exit criteria for terminating wireless transmission based on uplink quality and downlink transmission quality.

[0047] Figure 6 This is a flowchart of an example process for dynamically setting exit criteria for terminating a wireless connection.

[0048] Figure 7 Examples of computing devices and mobile computing devices that can be used to implement the techniques described herein are shown. Detailed Implementation

[0049] This specification generally describes systems, methods, apparatus, and other techniques for establishing and monitoring wireless connections (also referred to as “wireless links”) between wireless communication devices and access points that provide access to wireless networks. Wireless communication devices can apply these techniques to selectively establish wireless connections with access points that are more likely to provide reliable, high-quality performance. In some embodiments, wireless communication devices can further apply these techniques to determine the appropriate time to terminate an existing wireless connection, for example, by supporting connection to an alternative access point that can provide a higher-quality connection.

[0050] refer to Figure 1The diagram illustrates a conceptual design of a wireless environment 100 having a wireless communication device 102 and a pair of access points 104, 106 located near the wireless communication device 102. The wireless communication device 102 can be any suitable wireless-enabled device capable of wirelessly connecting to the access points to access a network. The wireless communication device 102 can be, for example, a smartphone, tablet computer, laptop computer, desktop computer, wireless network interface card, smartwatch, wireless-enabled television or set-top box, automotive wireless system, or other suitable device. Access points 104, 106 can each be any suitable wireless networking device that allows the wireless communication device (e.g., wireless communication device 102) to connect to a network via a wireless connection to access points 104 or 106. In some embodiments, access points 104, 106 are integrated into a wireless router. In other embodiments, access points 104, 106 differ from a wireless router. Access points 104, 106 can each provide access to a wired network (such as the Internet or an organization's intranet). Typically, each access point 104, 106 implements a wireless network independently or in cooperation with one or more additional access points. For example, access points 104, 106 may be configured to implement an IEEE 802.11 (Wi-Fi) wireless LAN, or may be part of a 2G, 3G, 4G (e.g., LTE), or 5G broadband wireless LAN, as well as additional access points. Wireless communication device 102 may be configured to communicate with access points 104, 106 via a corresponding wireless network (e.g., an IEEE 802.11 Wi-Fi network or a 2G, 3G, 4G, or 5G network). Although in Figure 1 The diagram shows only two access points 104 and 106, but any number of access points (e.g., 3, 4, 5, 6 or more) can be located in the wireless environment 100 with such proximity that device 102 can detect their presence. Two or more of the access points (e.g., access points 104 and 106) can be part of the same wireless network or different wireless networks.

[0051] Wireless communication device 102 and access points 104 and 106 each have a receiver section and a transmitter section for receiving and transmitting radio frequency (RF) transmissions, respectively. Regarding the transmitter section, wireless communication device 102 is configured to broadcast uplink RF transmissions and detect / receive downlink RF transmissions. In contrast, access points 104 and 106 are each configured to broadcast downlink RF transmissions and detect / receive uplink RF transmissions. However, wireless communication device 102 and access points 104 and 106 may each have different transmission power levels providing different transmission ranges from each other. For example, Figure 1The diagram shows that access point 104 has a moderately sized coverage area 108 with radius r1, access point 106 has a relatively large coverage area 112 with radius r2 reflecting a higher transmission power level, and wireless communication device 102 has a relatively small coverage area with radius r3 reflecting a lower transmission power level (this representation assumes equivalent receiver sensitivity among devices 102, 104, and 106). Due to these differences in transmission power levels and the location of wireless communication device 102 relative to access points 104 and 106, wireless communication device 102 is within the corresponding downlink coverage areas 108 and 112 of access points 104 and 106, but only the first access point 104 is within the uplink coverage area 110 of wireless communication device 102. The second access point 104 is located at a greater distance from wireless communication device 102, beyond the effective uplink transmission range r3 of wireless communication device 102. As a result, wireless communication device 102 may be able to receive transmissions of sufficient quality to allow reliable downlink communication from both access points 104 and 106, but only the first access point 104 within range allows reliable uplink communication from wireless communication device 102. However, the downlink power transmission levels measured by wireless communication device 102 from both access points 104 and 106 may be the same (or the transmission from the second access point 106 may even have a greater received signal strength at wireless communication device 102). For example, due to the variation in access point transmission power levels, the change in access point beacon RSSI can exceed 10 dB at the edge of the uplink range. (See also: Regarding...) Figure 2-4 As described, wireless communication device 102 can take action to selectively connect to access points that are more likely to provide reliable connectivity and margin for fading in downlink and uplink communications, rather than relying on a static threshold of downlink transmission power when determining whether to attempt to connect to an access point.

[0052] Figure 2 This is a flowchart of an example process 200 for establishing a wireless connection between a wireless communication device and an access point. Typically, the wireless communication device can be configured to connect to the access point while attempting to establish a connection, in a manner that provides a margin for signal quality fading in uplink transmission by degrading the quality of the transmission from the wireless communication device to the access point. The wireless communication device may, for example, use a lower-than-baseline transmission power level, use a more complex modulation scheme, or both during the connection process to establish a link with the access point. If a reduced uplink transmission quality can be used to establish the link, then once the link is established, the wireless communication device can then increase the transmission power and / or use a more robust modulation scheme for transmission, thereby providing a margin for uplink transmission.

[0053] More specifically, at stage 202, the wireless communication device (e.g., wireless communication device 102) detects available access points (e.g., access point 104 or 106) for the wireless network. The wireless communication device can detect access points by passively or actively scanning its environment. For active scanning, the wireless communication device can first announce its presence by broadcasting a message and monitoring responses from any access point within its uplink range. For passive scanning, the access point can periodically send beacons that allow any wireless communication device within its downlink range to discover the access point by listening for such beacons on a predefined frequency channel.

[0054] At stage 204, the wireless communication device determines one or more quality parameters for downlink transmissions from the detected access point. Downlink transmissions may be beacons detected from the access point during passive scanning, transmissions received during active scanning in response to probe messages from the wireless communication device, or any other transmissions detected by the wireless communication device from the access point before establishing a link with it. Transmission quality parameters include any characteristics of the transmission relevant to the wireless communication device's ability to successfully receive and interpret the transmission, such as the transmission's signal-to-noise ratio (SNR), power level, modulation scheme, number of spatial streams provided in the transmission, coding rate, and guard interval. In some implementations, the transmitting device is configured to broadcast transmissions according to a defined set of transmission quality parameters and adjust the parameters as needed to ensure reliable throughput of data to the receiving device. When significant interference or noise is present, the transmitting device may select higher quality transmission parameters to make its transmission more robust against the adverse effects of interference or noise. In other words, the quality of the transmission is generally inversely proportional to the destructiveness caused by interference or noise. For example, Binary Phase Shift Keying (BPSK) can be considered a higher quality modulation scheme than Quadrature Phase Shift Keying (QPSK) because BPSK transmission is less affected by noise than QPSK, despite BPSK's lower throughput. As another example, 16-QAM offers lower data throughput, but for the purposes of this specification, it is considered to have higher quality than 64-QAM because 16-QAM is less affected by noise.

[0055] Similarly, a higher transmission power level generally corresponds to higher transmission quality because it improves the signal-to-noise ratio (SNR) of the transmission at the receiver. In this specification, the transmission power level generally refers to the strength of the transmission at the receiving device. The transmission power level is typically measured at the receiving device, for example, in terms of Received Signal Strength Index (RSSI). The transmission power level attenuates as it propagates through the medium and is inversely proportional to the distance from the transmitter. Therefore, the transmission power level measured at the receiver will generally be less than the transmission power level measured at the transmitter. However, the transmitting device can be configured to select different transmission power levels, so in some contexts as described herein, the transmission power level may refer to the transmission power level from the transmitter's perspective.

[0056] In some implementations, the wireless communication device may determine the Modulation and Coding Scheme (MCS) index value of the transmission from the access point as an indicator of transmission quality. The IEEE 802.11 protocol defines a series of MCS index values, each representing a different combination of transmission quality parameters. Generally, a higher MCS index value indicates a lower quality transmission, i.e., providing higher data throughput but requiring a higher SNR for successful reception. For example, MCS0 indicates a transmission with a spatial stream, using BPSK modulation, and a 1 / 2 coding rate. MCS1 is a slightly lower quality, higher throughput transmission with a spatial stream, using QPSK modulation, and a 1 / 2 coding rate. In some implementations, the wireless communication device may use the MCS index value, RSSI, or both of the received transmission as an indicator of transmission quality.

[0057] At stage 206, the wireless communication device compares the observed downlink transmission quality from the access point with one or more entry criteria used to initiate a connection with the access point. Entry criteria may include thresholds for one or more transmission quality parameters, such as a minimum acceptable downlink transmission power level (e.g., a threshold RSSI value). If the observed transmission quality from the access point meets the entry criteria, the wireless communication device may initiate a connection process to establish a wireless link with the access point (stage 208). If the observed transmission quality from the access point does not meet the entry criteria, the wireless communication device may choose not to attempt to connect to the access point.

[0058] As mentioned, at stage 208, the wireless communication device may initiate a connection procedure to establish a wireless link with the access point. The wireless communication device selects a set of degraded uplink transmission quality parameters (210) to be applied during the connection procedure, and then configures the transmitter portion of the wireless communication device to use the degraded parameters in uplink transmission during the connection procedure (212). The degraded uplink parameters have lower quality than the baseline parameter set because the transmission generated using the degraded parameters requires a higher SNR for successful reception by the access point. For example, the wireless communication device may throttle the transmission power level of the uplink transmission during the connection procedure based on the baseline (e.g., maximum) power level that the wireless communication device is configured to use after the connection procedure is completed and the wireless link is successfully established (and in this case) in the case of the connection procedure. Additionally or alternatively, the wireless communication device may use a more complex modulation scheme (e.g., QPSK instead of BPSK) that requires a higher SNR for successful reception by the access point during the connection procedure. If the connection is established later, the wireless communication device may revert to higher quality parameters, such as broadcasting at a higher transmission power level and / or applying a less complex modulation scheme. In this way, by providing lower quality transmissions while the wireless communication device is attempting to connect to the access point, the wireless communication device can proactively take measures to provide SNR margins in uplink transmissions from the wireless communication device after the link is established.

[0059] At stage 214, if the access point is able to successfully receive the degraded uplink transmission during the connection process and the process is successfully completed, the wireless link is established and the wireless communication device is connected to the access point (216). However, if the access point is of degraded quality and cannot successfully receive uplink transmission from the wireless communication device, the link will not be established and the wireless communication device will not be connected to the access point (218).

[0060] In some implementations, after a connection to the access point is established, the wireless communication device is configured to initially broadcast an uplink transmission using at least one improved transmission quality parameter compared to the transmission quality parameters used during the connection process when the communication device uses at least one degraded transmission quality parameter. The first uplink transmission occurring after the link is established may have a lower MCS index value and / or a higher power level compared to those applied during the connection process, such that the quality of the initial uplink transmission in the link is higher than the quality of the degraded uplink transmission occurring during the connection process. In some implementations, the wireless communication device is configured to initially generate the uplink transmission when establishing a link with the access point using at least one improved transmission quality parameter, regardless of the downlink transmission power level, other downlink transmission quality parameters, or other information about the link quality. For example, the wireless communication device may broadcast the uplink transmission at less than full power during the connection process and then be configured to send the first uplink transmission at full power after the link is established. The device may subsequently adjust the transmission quality parameters of the uplink transmission based on information about the link quality, including the quality parameters of the uplink and / or downlink transmissions.

[0061] Degraded uplink transmissions can be applied throughout the entire connection process or only for certain messages sent during the connection process. In some implementations, the wireless communication device degrades probe messages during active scanning. If a given degraded probe message does not receive a response from the access point, the wireless communication device will not detect the access point or attempt to connect further. In some implementations, the wireless communication device degrades additional messages after detecting an access point, regardless of whether it is as a result of active or passive scanning.

[0062] Turning Figure 3 A flowchart of an example process 300 for determining access point-specific entry criteria so that a wireless communication device can connect to a specific access point is shown. Typically, access point-specific criteria can be generated based on indications of historical success rates of one or more wireless communication devices connecting to different access points with different downlink transmission qualities. The entry criteria for a specific access point can then be set to, or based on, the quality of downlink transmissions from the access point that have historically provided connections with at least a threshold success rate. In some implementations, if the wireless communication device achieves a sufficiently high success rate in establishing a reliable connection with the access point at the current entry threshold, the entry criteria can be relaxed for a specific access point (e.g., lowering the RSSI threshold). It should be noted that, although... Figure 3The examples discussed herein relate to access point-specific access criteria, but some implementations relate to determining individualized access criteria for a particular wireless network that includes one or more access points, and some implementations relate to determining specific access criteria for different frequency channels of individual access points and / or wireless networks.

[0063] More specifically, at stage 302, the wireless communication device (e.g., wireless communication device 102) detects available access points (e.g., access points 104 or 106) for the wireless network. The wireless communication device can detect access points by passively or actively scanning its environment. For active scanning, the wireless communication device can first announce its presence by broadcasting a message and monitoring responses from any access point within its uplink range. In some active scanning implementations, the device can announce its presence by sending probe request frames. Probe request frames can be sent multiple times, with each instance of the probe request being sent at a different power level and / or a different MCS. Each probe request can have a unique identifier (e.g., a sequence number) and can also be sent with a different (randomized) MAC address, such that access points receiving multiple probe requests do not recognize that the probe requests originate from the same physical device. The access points can then respond to each of the probe requests separately. Based on these responses (or expected responses if no response is received), the wireless device can determine which specific probe response messages the access point responded to, and can identify the corresponding transmit power and / or MCS level of the probe requests that led to these responses from the access point. The wireless device can then estimate the uplink signal quality based on the responses from the access point. For passive scanning, the access point can periodically transmit beacons that allow any wireless communication device within the access point's downlink range to discover the access point by listening for such beacons on a predefined frequency channel.

[0064] At stage 304, the wireless communication device determines that it should attempt to connect to the detected access point and initiates a connection process to establish a wireless link with the access point. The determination to initiate a connection process can be generated by identifying that the quality of beacons or other downlink transmissions from the access point meets predefined entry criteria for connecting to the access point. Initially, the wireless communication device can use default entry criteria until prior experience and a history of successes in connecting to various access points become available. As the wireless communication device collects more observations of successful and failed attempts to connect to the wireless communication device under different conditions and different downlink transmission qualities, the default criteria can later be replaced or adjusted with access point-specific criteria.

[0065] At stage 306, the wireless communication device stores the result of the connection process and an indication of the downlink transmission quality of one or more transmissions from the access point. The downlink transmission whose quality is measured and recorded may be a transmission corresponding to the time when the wireless communication device detects the access point and / or a transmission that occurs during the connection process. In some embodiments, the result of the connection process is binary-classified, e.g., a successful connection (established link) or a failed connection (unestablished link). For example, the wireless communication device may generate database entries for connection attempts, indicating the result of the attempt (e.g., success or failure) and the downlink transmission power level (e.g., RSSI level) of one or more downlink transmissions sent during the connection process. In some embodiments, a cumulative success and / or failure rate may be maintained in the database, indicating the percentage of connection attempts that the wireless communication device and / or other wireless communication devices have consistently succeeded or failed over a past period when attempting to connect to a particular access point (or a particular wireless network and / or a particular channel on a particular access point). The cumulative success or failure rate may be updated based on the result of the most recent attempt to initiate a connection with the access point performed at stage 304.

[0066] In some implementations, a connection attempt is classified as successful if the connection process completes and results in the establishment of a link between the wireless communication device and the access point. If the link cannot be established, the connection attempt is considered to have failed. In some implementations, a connection attempt is classified as successful only if the link is established and maintained for at least a threshold amount of time (e.g., ensuring that the link does not immediately fail despite being established for a short period of time). If the link fails before the threshold amount of time has elapsed, the connection is considered to have failed. In some implementations, a connection attempt is classified as successful only if the link is established and the quality of uplink and / or downlink transmissions meets a threshold quality requirement for at least the threshold amount of time.

[0067] At stage 308, the wireless communication device or another system determines access point-specific entry criteria for connecting to an access point (or for connecting to a specific wireless network to which the access point belongs and / or for connecting to the access point on a specific frequency channel). Specifically, the system determines, for each of a plurality of downlink transmission quality levels, the cumulative success rate (or failure rate) (310) of connecting the wireless communication device and / or other wireless communication devices to a specific access point when a specific downlink transmission quality level is observed. The success rate may be determined based on the aforementioned database entries mapping the results of connection attempts to downlink transmission quality levels. In some embodiments, the success rate is determined for a specific downlink transmission quality (e.g., -60 dB, -55 dB power level). In other embodiments, the success rate is determined for a range of transmission quality (e.g., -70 to -61 dB, -60 to -51 dB power level). The system then uses selection criteria to select one or more downlink transmission quality levels to set the entry criteria for the access point (312). In some implementations, the system selects the lowest downlink transmission quality level mapped to a sufficiently high historical connection success rate (e.g., as indicated by a threshold success rate). The selected downlink transmission quality level can then be used to establish access point-specific entry criteria (314) for the access point. In some implementations, the entry criteria are or include a threshold downlink transmission power level (e.g., RSSI level), and this threshold is set or based on the selected downlink transmission power level, such as the lowest transmission power level mapped to a threshold connection success rate for the access point.

[0068] For illustration purposes, Figure 4 Example database tables are shown, storing information about past attempts by wireless communication devices to connect to various access points on different networks and channels. Each row presents connection success information for a specific combination of SSID, BSSID, frequency channel, and RSSI range. For a given entry, the SSID (“Service Set Identifier”) column indicates the wireless network the wireless communication device attempted to connect to; the BSSID column indicates the MAC address of the specific access point the wireless communication device attempted to connect to; the channel column indicates the frequency channel on which the connection attempt was made; and the RSSI column indicates the range of RSSI levels containing the corresponding downlink transmissions from the access point used for the connection attempt. Based on... Figure 3The described techniques allow wireless communication devices or other systems to determine a threshold entry RSSI level for a specific SSID / BSSID / channel combination by selecting a minimum RSSI range corresponding to a minimum acceptable (e.g., a threshold) connection success rate. For example, if the threshold connection success rate is 75%, then for “WirelessNet_1”, access point “7f:a4:3d:be:df:8c”, and channel 1, the system can select an RSSI level from the range -50 to -41 dB as the entry RSSI threshold. In some implementations, the selected RSSI threshold is the lowest signal strength (e.g., -50 dB), the highest signal strength (e.g., -41 dB), or an intermediate value within that range. In some implementations, the system sets the RSSI threshold based on the range providing the highest success rate, regardless of whether the success rate meets the threshold. Different RSSI thresholds can be maintained for different SSID / BSSID / channel combinations. In some implementations, the system periodically (or otherwise from time to time) updates the RSSI threshold and / or other entry criteria based on the most recent indications of successful and failed connection attempts.

[0069] In some implementations, wireless communication devices or other systems can be configured to dynamically adjust the entry criteria used by the wireless communication device to initiate connections with a specific access point. For example, the wireless communication device may employ an initial (e.g., default) set of entry criteria. If, over time, the wireless communication device demonstrates a sufficiently high connection success rate with the access point using the initial set of entry criteria, the entry criteria can be relaxed (e.g., the minimum downlink RSSI threshold can be lowered). If the relaxed entry criteria continue to produce a sufficiently high connection success rate with the access point, the wireless communication device may further relax the entry criteria. On the other hand, if the relaxed entry criteria result in too many failed connections (e.g., the connection success rate fails to meet a specified threshold), the entry criteria can be restored upwards again.

[0070] Refer again Figure 3After the access point-specific entry criteria have been determined, at a later time when the wireless communication device has the opportunity to connect to the access point, the wireless communication device can measure one or more downlink transmission quality parameters and compare them with the parameters required by the entry criteria (stage 318). At stage 320, the wireless communication device then determines whether the quality of the downlink transmission from the access point meets the entry criteria. In some embodiments, determining whether the downlink transmission quality meets the entry criteria includes comparing the downlink transmission power level (e.g., RSSI of a beacon or probe response) of the transmission from the access point with a threshold power level (e.g., a threshold RSSI level). At stage 322, if the entry criteria are met, the wireless communication device establishes a connection with the access point. Alternatively, if the entry criteria are not met, the wireless communication device may not establish a connection with the access point (stage 324).

[0071] Figure 5 This is a flowchart of an example process 500 for a wireless communication device to set exit criteria for terminating wireless transmission based on information about the relative quality of uplink and downlink transmissions. Typically, after a link has been established between the wireless communication device and an access point, the wireless communication device can monitor the health or quality of the link. If the link quality degrades to the point where the wireless communication device struggles to successfully receive downlink transmissions or successfully transmit uplink transmissions, the wireless communication device can initiate a termination process. Initiating a termination process may involve searching for other access points to connect to instead of maintaining the link with the current access point, and can sometimes result in the immediate termination of the link. Link quality can fluctuate as the wireless communication device moves relative to the access point and will often degrade depending on the distance from the wireless communication device to the access point. Other obstacles and interference from external conditions may also occur. However, to reduce the likelihood that the wireless communication device will maintain a poor-quality link when downlink transmission quality is acceptable but uplink transmission quality is unacceptable, the wireless communication device can perform process 500 to further consider uplink transmission quality when determining the exit criteria for the link.

[0072] At stage 502, the wireless communication device establishes a wireless link (connection) with the access point. Once the link is established, the wireless communication device monitors the health or quality of the link. On a constant or frequent basis, for example, the wireless communication device may measure the quality of downlink transmissions from the access point (stage 504) and identify the quality of uplink transmissions received by the access point (stage 506). In some implementations, the wireless communication device determines, for example, quality parameters of uplink and downlink transmissions during the connection process, such as the signal-to-noise ratio (SNR) of the transmission, the power level of the transmission, the modulation scheme of the transmission, the number of spatial streams provided in the transmission, the coding rate of the transmission, the guard interval of the transmission, or a combination thereof. Since downlink transmissions are received by the wireless communication device, the wireless communication device can usually directly determine their quality. For example, the wireless communication device can determine the RSSI level and / or the MCS index value of the downlink transmission. However, the wireless communication device may not be able to directly measure certain uplink quality parameters, such as the received signal strength of the uplink transmission at the access point. Therefore, the access point can measure the received signal strength of the uplink transmission independently or upon request from the wireless communication device, and send an indication of the measured signal strength of the uplink transmission to the wireless communication device. In some implementations of the wireless link based on the IEEE 802.11 protocol, the wireless communication device can utilize messages originally proposed for beamforming techniques to enable the access point to provide an indication of the received signal strength of the uplink transmission to the wireless communication device. Other uplink quality parameters, such as modulation scheme, coding rate, and guard interval, are set by the transmitter of the wireless communication device and are therefore known to the wireless communication device.

[0073] In some implementations, the wireless communication device sets a termination criterion for the link by adjusting the baseline link termination criterion using information about uplink and downlink transmission quality. At stage 508, the wireless communication device identifies the baseline termination criterion. As an example, the baseline termination criterion may include a predefined static downlink transmission power threshold (e.g., RSSI level). In the absence of measurements, if the measured downlink transmission power level of downlink transmissions from the access point does not meet this static threshold for a period of time, the wireless link may be terminated. The baseline termination criterion may additionally or alternatively include other quality factors, such as modulation criteria, coding rate criteria, SNR thresholds, or combinations of these and other criteria.

[0074] At stage 510, the wireless communication device compares the quality of the monitored downlink and uplink transmissions. If a gap exists between the uplink and downlink quality, the wireless communication device can adjust the termination criteria based on this gap. In some implementations, the wireless communication device determines the difference between the transmission power levels of the uplink and downlink transmissions (e.g., the difference in RSSI levels between the downlink and uplink transmissions) and then applies this difference as an offset to a predefined static downlink transmission power threshold. For example, the adjusted downlink transmission power threshold can be determined by adding the offset to a baseline threshold, where the offset is equal to the downlink transmission power level minus the uplink transmission power level. Therefore, if the received signal strength of the uplink transmission is less than the received signal strength of the downlink transmission, this difference can be added to the downlink transmission power threshold, making the wireless communication device more sensitive to terminating existing links.

[0075] In some implementations, the wireless communication device determines the difference between the modulation and coding scheme (MCS) index values ​​of the monitored uplink and downlink transmissions, and adjusts the downlink transmission power threshold, which forms or is part of the termination criterion, based on this difference. Each MCS index value can be mapped to a corresponding SNR value. The wireless communication device can then adjust the downlink transmission power threshold by an amount equal to the difference between the uplink and downlink transmission SNR values. For example, if during connection establishment, the wireless communication device uses MCS1 to broadcast uplink transmissions but the access point uses MCS0 to broadcast downlink transmissions, the wireless communication device increases the downlink transmission power level threshold to account for the fact that the access point is using a higher-quality modulation and coding scheme. This technique can be beneficial for adjusting the threshold used to terminate the link when the wireless communication device cannot access the received signal strength data of the vehicle's uplink transmission from the access point.

[0076] At stage 512, the wireless communication device determines whether the quality of the downlink transmission meets the adjusted exit criteria, for example, by comparing the RSSI levels of one or more downlink transmissions with an adjusted RSSI threshold. If the quality of the downlink transmission meets (e.g., equals or exceeds) the adjusted exit criteria, such as the measured RSSI level of the downlink transmission meeting the adjusted RSSI threshold, the wireless communication device chooses to maintain the wireless link 514. However, if the quality of the downlink transmission does not meet the adjusted exit criteria, the wireless communication device may choose to initiate termination of the wireless link (stage 516). In some embodiments, the wireless communication device terminates the wireless link only if an alternative access point or network that would provide better performance than the current access point is available. In other embodiments, the wireless communication device terminates the wireless link immediately regardless of whether an improved link can be established.

[0077] Figure 6 This is a flowchart of an example process 600 for dynamically setting exit criteria for terminating a wireless connection. In some implementations, process 600 is performed using a wireless communication device (e.g., wireless communication device 102) and an access point (e.g., access point 104 or 106).

[0078] At stage 602, the wireless communication device establishes a wireless link (connection) with the access point. For example, the wireless communication device can discover the access point through active or passive scanning, determine that detected pre-connection downlink transmissions from the access point meet one or more entry criteria, and initiate a connection process to establish a wireless link.

[0079] At stage 604, during a period of time in the link process, the wireless communication device may change the quality of its uplink transmission to the access point. This change may be explicitly performed for the purposes of this process 600 to derive exit criteria, or it may change incidentally as a result of typical adjustments to transmission quality parameters by the wireless communication device in response to conditions such as requiring the wireless communication device to compensate for changes in fading or other phenomena over time. The quality of the uplink transmission can be changed by adjusting the transmission power level, modulation scheme, coding rate, guard interval, or combinations of these and / or other quality parameters for different transmissions. In some embodiments, the wireless communication device adjusts the quality of its uplink transmission by transmitting according to quality parameters defined by different MCS index values.

[0080] At stage 606, the wireless communication device identifies uplink transmissions successfully sent to the access point at different quality levels. In some embodiments, these transmissions can be identified by monitoring acknowledgment transmissions from the access point. If no acknowledgment is received, the uplink transmission may not have been successfully sent to and received by the access point. In some embodiments, successfully sent uplink transmissions can be identified as those for which the access point has not sent back an indication that the transmission should be retransmitted.

[0081] At stage 608, the wireless communication device identifies a downlink transmission sent from the access point that corresponds to a successfully transmitted uplink transmission. These corresponding downlink transmissions are typically transmissions received by the wireless communication device that are very close in time to the successfully transmitted uplink transmission. A logical connection may also exist between the successfully transmitted uplink transmission and its corresponding downlink transmission. For example, the wireless communication device may identify an acknowledgment from the access point as a downlink transmission corresponding to a successfully transmitted uplink transmission. The wireless communication device also determines the downlink transmission power level used for the identified downlink transmission corresponding to the successfully transmitted uplink transmission. For example, the wireless communication device may determine the RSSI level of an acknowledgment received in response to a successfully transmitted uplink transmission.

[0082] At stage 610, the wireless communication device stores data that maps (i) the downlink transmission power level for the identified downlink transmission corresponding to a successfully transmitted uplink transmission to (ii) the transmission quality level of the successfully transmitted uplink transmission. For example, the data may indicate that an uplink transmission under MCS1 was successfully transmitted and resulted in a corresponding downlink transmission received with an RSSI of -83 dB, and in another case, that an uplink transmission under MCS0 was successfully transmitted and resulted in a corresponding downlink transmission received with an RSSI of -70 dB. In some embodiments, the data includes samples only from the current connection between the wireless communication device and the access point. In other embodiments, the data additionally includes samples from previous connections between the wireless communication device and the access point.

[0083] At stage 612, the system uses historical data indicating uplink transmission quality levels (e.g., MCS level or a separate quality parameter) and corresponding downlink transmission power levels to determine a threshold downlink transmission power level for terminating the link between the wireless communication device and the access point. In some embodiments, the threshold is set to or based on a downlink transmission power level mapped to the minimum acceptable uplink transmission quality level. For example, MCS1 can be designated as the minimum acceptable uplink transmission quality level. In some embodiments, modulation and coding schemes are indexed such that a lower index value indicates a scheme requiring a smaller SNR for successful reception compared to a scheme with a higher index value. For example, an MCS1 transmission typically requires a smaller SNR for successful reception compared to an MCS2 transmission, an MCS2 transmission typically requires a smaller SNR for successful reception compared to an MCS3 transmission, and so on. The wireless communication device or a remote system communicating with it can analyze the history of successful uplinks to determine the downlink transmission power level (e.g., RSSI level) corresponding to the MCS1 uplink transmission. If the data indicates that there are multiple MCS1 uplink transmissions, the system can calculate the average of the corresponding downlink transmission power levels used for these MCS1 uplink transmissions to generate an exit threshold, or use other criteria to select a representative downlink power level as the exit threshold (e.g., the mean, median, or pattern of power levels, or the highest or lowest power level).

[0084] After a threshold downlink transmission power level for link termination has been set, at stage 614 the wireless communication device continues to monitor the strength of downlink transmissions from the access point during the connection with the access point. The measured power level of the downlink transmissions (e.g., RSSI level) is compared to the threshold level (stage 616), and if the measured power level is determined to meet the threshold power level, the wireless communication device maintains its current connection with the access point (stage 618). However, if the measured power level is determined to not meet the threshold power level for a period of time, the wireless communication device may initiate termination of its current connection with the access point (stage 620). In some embodiments, the wireless communication device terminates the connection only if another access point or network that is likely to provide better performance than the currently connected access point is available. In some embodiments, the wireless communication device may terminate the connection immediately upon recognizing that the measured downlink transmission power level does not meet the threshold power level.

[0085] Figure 7Examples of computing devices 700 and mobile computing devices that can be used to implement the techniques described herein are shown. Computing device 700 is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other suitable computers. Mobile computing devices are intended to represent various forms of mobile devices, such as personal digital assistants, cellular phones, smartphones, and other similar computing devices. The components, their connections and relationships, and their functions shown herein are intended to be exemplary only and are not intended to limit the implementation of the inventions described and / or claimed in this document.

[0086] Computing device 700 includes a processor 702, a memory 704, a storage device 706, a high-speed interface 708 connected to the memory 704 and multiple high-speed expansion ports 710, and a low-speed interface 712 connected to a low-speed expansion port 714 and the storage device 706. Each of the processor 702, memory 704, storage device 706, high-speed interface 708, high-speed expansion port 710, and low-speed interface 712 is interconnected using various buses and may be mounted on a common motherboard or otherwise, as appropriate. The processor 702 can process instructions for execution within computing device 700, including instructions stored in memory 704 or on storage device 706 for displaying graphical information for a GUI on an external input / output device, such as a display 716 coupled to high-speed interface 708. In other embodiments, multiple processors and / or multiple buses, as well as multiple memories and various types of memory, may be used as appropriate. Additionally, multiple computing devices may be connected, with each device providing a portion of the necessary operation (e.g., as a server group, a set of blade servers, or a multiprocessor system).

[0087] Memory 704 stores information within computing device 700. In some embodiments, memory 704 is one or more volatile memory cells. In some embodiments, memory 704 is one or more non-volatile memory cells. Memory 704 may also be another form of computer-readable medium, such as a magnetic disk or optical disk.

[0088] Storage device 706 provides mass storage for computing device 700. In some embodiments, storage device 706 may be or include computer-readable media such as floppy disk devices, hard disk devices, optical disk devices, magnetic tape devices, flash memory, or other similar solid-state storage devices or arrays of devices, including devices in storage area networks or other configurations. The computer program product may also include instructions that, when executed, perform one or more methods, such as those described above. The computer program product may also be tangibly embodied in a computer or machine-readable medium such as memory 704, storage device 706, or memory on processor 702.

[0089] High-speed interface 708 manages bandwidth-intensive operations of computing device 700, while low-speed interface 712 manages less bandwidth-intensive operations. This allocation of functions is merely exemplary. In some embodiments, high-speed interface 708 is coupled to memory 704, display 716 (e.g., via a graphics processor or accelerator), and high-speed expansion port 710, which can accept various expansion cards (not shown). In this embodiment, low-speed interface 712 is coupled to storage device 706 and low-speed expansion port 714. Low-speed expansion port 714, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, Wireless Ethernet), can be coupled to one or more input / output devices, such as keyboards, pointing devices, scanners, or networking devices such as switches or routers, for example, via a network adapter.

[0090] As shown in the figure, the computing device 700 can be implemented in many different forms. For example, it can be implemented as a standard server 720, or multiple times in a group of such servers. Furthermore, it can be implemented in a personal computer such as a laptop computer 722. It can also be implemented as part of a rack server system 724. Alternatively, components from the computing device 700 can be combined with other components in a mobile device (not shown) (such as a mobile computing device 750). Each of such devices can contain one or more of the computing device 700 and the mobile computing device 750, and the entire system can consist of multiple computing devices communicating with each other.

[0091] Mobile computing device 750 includes a processor 752, memory 764, input / output devices such as a display 754, a communication interface 766, a transceiver 768, and other components. Mobile computing device 750 may also be provided with storage devices, such as microdrives or other devices, to provide additional storage. Each of the processor 752, memory 764, display 754, communication interface 766, and transceiver 768 is interconnected using various buses, and several components may be suitably mounted on a common motherboard or otherwise installed.

[0092] The processor 752 can execute instructions within the mobile computing device 750, including instructions stored in the memory 764. The processor 752 can be implemented as a chipset including separate and multiple analog and digital processors. The processor 752 can provide, for example, coordination for other components of the mobile computing device 750, such as control of the user interface, applications running by the mobile computing device 750, and wireless communications performed by the mobile computing device 750.

[0093] The processor 752 can communicate with the user via a control interface 758 and a display interface 756 coupled to the display 754. The display 754 can be, for example, a TFT (Thin Film Transistor Liquid Crystal Display) or OLED (Organic Light Emitting Diode) display or other suitable display technology. The display interface 756 can include suitable circuitry for driving the display 754 to present graphics and other information to the user. The control interface 758 can receive commands from the user and translate them for submission to the processor 752. Furthermore, an external interface 762 can provide communication with the processor 752 to enable near-field communication between the mobile computing device 750 and other devices. The external interface 762 can be provided, for example, for wired communication in some embodiments, or for wireless communication in others, and multiple interfaces can be used.

[0094] Memory 764 stores information within the mobile computing device 750. Memory 764 may be implemented as one or more computer-readable media, one or more volatile storage units, or one or more non-volatile storage units. Extended memory 774 may also be provided and connected to the mobile computing device 750 via an extended interface 772, which may include, for example, a SIMM (Single In-line Memory Module) card interface. Extended memory 774 may provide additional storage space for the mobile computing device 750, or it may store applications or other information for the mobile computing device 750. Specifically, extended memory 774 may include instructions for performing or supplementing the above processes, and may also include security information. Therefore, for example, extended memory 774 may be provided as a security module for the mobile computing device 750, and may be programmed with instructions that allow secure use of the mobile computing device 750. Furthermore, secure applications may be provided via a SIMM card along with additional information, such as placing identification information on the SIMM card in an unbreakable manner.

[0095] As discussed below, the memory may include, for example, flash memory and / or NVRAM (non-volatile random access memory). The computer program product contains instructions that, when executed, perform one or more methods, such as those described above. The computer program product may be a computer or machine-readable medium, such as memory 764, extended memory 774, or memory on processor 752. In some embodiments, the computer program product may be received in the course of propagation (e.g., via transceiver 768 or external interface 762).

[0096] Mobile computing device 750 can communicate wirelessly via communication interface 766, which may include digital signal processing circuitry if necessary. Communication interface 766 can provide communication under various modes or protocols, such as GSM voice calls (Global System for Mobile Communications), SMS (Short Message Service), EMS (Enhanced Messaging Service) or MMS messaging (Multimedia Messaging Service), CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), PDC (Personal Digital Cellular), WCDMA (Wideband Code Division Multiple Access), CDMA2000, or GPRS (General Packet Radio Service). Such communication can occur, for example, using radio frequency via transceiver 768. Furthermore, short-range communication can occur, such as using Bluetooth, WiFi, or other such transceivers (not shown). Additionally, GPS (Global Positioning System) receiver module 770 can provide additional navigation and location-related wireless data to mobile computing device 750, which can be used as appropriate by applications running on mobile computing device 750.

[0097] The mobile computing device 750 can also use an audio codec 760 for audible communication, which can receive spoken information from a user and convert it into usable digital information. The audio codec 760 can also generate audible sound for the user, for example, through a speaker (e.g., in the handset of the mobile computing device 750). This sound can include sounds from voice telephone calls, recorded sounds (e.g., voice messages, music files, etc.), and sounds generated by applications operating on the mobile computing device 750.

[0098] As shown in the figure, the mobile computing device 750 can be implemented in many different forms. For example, it can be implemented as a cellular phone 780. It can also be implemented as part of a smartphone 782, a personal digital assistant, or other similar mobile devices.

[0099] The various implementations of the computer-based systems and techniques described herein can be implemented using digital electronic circuits, integrated circuits, specially designed ASICs (Application-Specific Integrated Circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations may include implementations in one or more computer programs executable and / or interpretable on a programmable system comprising at least one programmable processor, which may be dedicated or general-purpose, coupled to receive data and instructions from a storage system, at least one input device, and at least one output device, and to transmit data and instructions to the storage system, at least one input device, and at least one output device.

[0100] These computer programs (also referred to as programs, software, software applications, or code) include machine instructions for a programmable processor and can be implemented using high-level procedural and / or object-oriented programming languages ​​and / or assembly / machine languages. As used herein, the terms machine-readable medium and computer-readable medium refer to any computer program product, apparatus, and / or device (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term machine-readable signal refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0101] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and pointing device (e.g., a mouse or trackball) that the user can use to provide input to the computer. Other types of devices may also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including sound, speech, or tactile input.

[0102] The systems and technologies described herein can be implemented in computing systems that include back-end components (e.g., as data servers), middleware components (e.g., application servers), front-end components (e.g., client computers having a graphical user interface or web browser that a user can use to interact with implementations of the systems and technologies described herein), or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected via digital data communication (e.g., communication networks) of any form or medium. Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0103] A computing system may include clients and servers. Clients and servers are generally geographically separated and typically interact via a communication network. The client-server relationship is established by means of computer programs running on the respective computers and having a client-server relationship with each other.

[0104] The logs described herein (e.g., activity logs) can be implemented as digital data stored in a computer-readable physical memory structure. Where the systems, methods, devices, and other technologies described herein collect personal information about a user (e.g., contextual data) or where such personal information can be used, users can be provided with the opportunity to control whether a program or feature collects user information (e.g., information about the user's social networks, social actions or activities, occupation, user preferences, or the user's current location) or to control whether and / or how content potentially more relevant to the user is received from a content server. Furthermore, certain data can be processed in one or more ways before it is stored or used, such that personally identifiable information is removed. For example, a user's identity can be processed so that personally identifiable information cannot be determined for that user, or, where location information is available, the user's geographic location can be generalized (e.g., to a city, zip code, or state level), making it impossible to determine the user's specific location. Therefore, users can control how information about themselves is collected and used by content servers.

[0105] Although various embodiments have been described in detail above, other modifications are possible. Furthermore, the logical flow depicted in the figures does not require a specific order or sequence to achieve the desired result. Additionally, other steps may be provided, or steps may be eliminated from the described flow, or other components may be added to or removed from the described flow. Therefore, other embodiments are within the scope of the following claims.

Claims

1. A computer-implemented method, comprising: Establishing a wireless connection between a wireless communication device and an access point used for a wireless network: The wireless communication device identifies one or more downlink transmission quality parameters for a first set of transmissions from the access point to the wireless communication device via the wireless connection, wherein the one or more downlink transmission quality parameters indicate the downlink transmission power level of the first set of transmissions from the access point to the wireless communication device. The wireless communication device identifies one or more uplink transmission quality parameters for a second set of transmissions from the wireless communication device to the access point via the wireless connection, wherein the one or more uplink transmission quality parameters indicate the uplink transmission power level of the second set of transmissions from the wireless communication device to the access point. Determine the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters, wherein the difference indicates the relative quality between the second group of transmissions and the first group of transmissions; A criterion for initiating termination of the wireless connection is determined based on the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters, wherein the criterion for initiating termination of the wireless connection includes a downlink transmission power level from the access point to the wireless communication device that does not meet a threshold power level. Determine whether the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria used to initiate the termination of the wireless connection. as well as In response to determining that the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria, termination of the wireless connection is initiated.

2. The computer-implemented method according to claim 1, wherein: The downlink transmission power level of the first group of transmissions is measured by the wireless communication device as the received signal strength of the first group of transmissions; as well as The uplink transmission power level of the second group of transmissions is measured by the access point as the received signal strength of the second group of transmissions.

3. The computer-implemented method according to claim 1, wherein, Identifying the one or more uplink transmission quality parameters of the second group of transmissions includes the wireless communication device requesting the access point to provide data indicating the one or more uplink transmission quality parameters to the wireless communication device.

4. The computer-implemented method according to claim 1, wherein, The threshold power level is an adjusted threshold power level, and the criteria for determining the termination of the wireless connection include generating the adjusted threshold power level by applying an offset to a baseline threshold power level, the offset being based on the difference between the downlink transmission power level of the first set of transmissions and the uplink transmission power level of the second set of transmissions.

5. The computer-implemented method according to claim 1, wherein, The one or more downlink transmission quality parameters include a first modulation scheme for the first set of transmissions from the access point to the wireless communication device, and the one or more uplink transmission quality parameters include a second modulation scheme for the second set of transmissions from the wireless communication device to the access point.

6. The computer-implemented method according to claim 5, wherein: Identifying the one or more downlink transmission quality parameters of the first group of transmissions includes identifying the modulation and coding scheme (MCS) index value of the first group of transmissions, wherein the first modulation scheme is assigned to the MCS index value of the first group of transmissions. as well as Identifying the one or more uplink transmission quality parameters of the second group of transmissions includes identifying the MCS index value of the second group of transmissions, and the second modulation scheme is assigned to the MCS index value of the second group of transmissions.

7. The computer-implemented method of claim 6, further comprising determining the threshold power level based on an estimated difference in received signal strength between the first set of transmissions at the wireless communication device and the second set of transmissions at the access point, the estimated difference being determined using at least the MCS index value of the second set of transmissions.

8. The computer-implemented method according to claim 1, wherein, In response to determining that the characteristics of the wireless connection between the wireless communication device and the access point do not meet the criteria, the wireless communication device is configured to maintain the wireless connection for a period of time, rather than initiating termination of the wireless connection.

9. A wireless communication device, comprising: One or more processors; as well as One or more computer-readable media having instructions encoded thereon, which, when executed by the one or more processors, cause to perform operations including the following steps: Establish a wireless connection between the wireless communication device and the access point for the wireless network: The wireless communication device identifies one or more downlink transmission quality parameters for a first set of transmissions from the access point to the wireless communication device via the wireless connection, wherein the one or more downlink transmission quality parameters indicate the downlink transmission power level of the first set of transmissions from the access point to the wireless communication device. The wireless communication device identifies one or more uplink transmission quality parameters for a second set of transmissions from the wireless communication device to the access point via the wireless connection, wherein the one or more uplink transmission quality parameters indicate the uplink transmission power level of the second set of transmissions from the wireless communication device to the access point. Determine the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters, wherein the difference indicates the relative quality between the second group of transmissions and the first group of transmissions; A criterion for initiating termination of the wireless connection is determined based on the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters, wherein the criterion for initiating termination of the wireless connection includes a downlink transmission power level from the access point to the wireless communication device that does not meet a threshold power level. Determine whether the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria used to initiate the termination of the wireless connection. as well as In response to determining that the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria, termination of the wireless connection is initiated.

10. The wireless communication device according to claim 9, wherein: The downlink transmission power level of the first group of transmissions is measured by the wireless communication device as the received signal strength of the first group of transmissions; and The uplink transmission power level of the second group of transmissions is measured by the access point as the received signal strength of the second group of transmissions.

11. The wireless communication device according to claim 9, wherein, Identifying the one or more uplink transmission quality parameters of the second group of transmissions includes the wireless communication device requesting the access point to provide data indicating the one or more uplink transmission quality parameters to the wireless communication device.

12. The wireless communication device according to claim 9, wherein, The threshold power level is an adjusted threshold power level, and the criteria for determining the termination of the wireless connection include generating the adjusted threshold power level by applying an offset to a baseline threshold power level, the offset being based on the difference between the downlink transmission power level of the first set of transmissions and the uplink transmission power level of the second set of transmissions.

13. The wireless communication device according to claim 9, wherein, The one or more downlink transmission quality parameters include a first modulation scheme for the first set of transmissions from the access point to the wireless communication device, and the one or more uplink transmission quality parameters include a second modulation scheme for the second set of transmissions from the wireless communication device to the access point.

14. The wireless communication device according to claim 13, wherein: Identifying the one or more downlink transmission quality parameters of the first group of transmissions includes identifying the modulation and coding scheme (MCS) index value of the first group of transmissions, wherein the first modulation scheme is assigned to the MCS index value of the first group of transmissions. as well as Identifying the one or more uplink transmission quality parameters of the second group of transmissions includes identifying the MCS index value of the second group of transmissions, and the second modulation scheme is assigned to the MCS index value of the second group of transmissions.

15. The wireless communication device of claim 14, wherein the operation further comprises determining the threshold power level based on an estimated difference in received signal strength between the first set of transmissions at the wireless communication device and the second set of transmissions at the access point, the estimated difference being determined using at least the MCS index value of the second set of transmissions.

16. One or more non-transitory computer-readable media having instructions stored thereon, the instructions causing, when executed by one or more processors, to perform an operation comprising the following steps: Establishing a wireless connection between a wireless communication device and an access point used for a wireless network: The wireless communication device identifies one or more downlink transmission quality parameters of a first group of transmissions from the access point to the wireless communication device via the wireless connection, wherein the one or more downlink transmission quality parameters include a first modulation scheme of the first group of transmissions from the access point to the wireless communication device, and wherein identifying the one or more downlink transmission quality parameters includes identifying a modulation and coding scheme (MCS) index value of the first group of transmissions, the first modulation scheme being assigned to the MCS index value of the first group of transmissions. The wireless communication device identifies one or more uplink transmission quality parameters of a second set of transmissions from the wireless communication device to the access point via the wireless connection, wherein the one or more uplink transmission quality parameters include a second modulation scheme of the second set of transmissions from the wireless communication device to the access point, and wherein identifying the one or more uplink transmission quality parameters includes identifying an MCS index value of the second set of transmissions, the second modulation scheme being assigned to the MCS index value of the second set of transmissions. Determine the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters, wherein the difference indicates the relative quality between the second group of transmissions and the first group of transmissions; The criteria for terminating the wireless connection are determined based on the difference between the one or more downlink transmission quality parameters and the one or more uplink transmission quality parameters. Determine whether the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria used to initiate the termination of the wireless connection. as well as In response to determining that the characteristics of the wireless connection between the wireless communication device and the access point meet the criteria, termination of the wireless connection is initiated.

17. One or more non-transitory computer-readable media according to claim 16, wherein, The one or more downlink transmission quality parameters indicate the downlink transmission power level of the first set of transmissions from the access point to the wireless communication device, and wherein the one or more uplink transmission quality parameters indicate the uplink transmission power level of the second set of transmissions from the wireless communication device to the access point.

18. One or more non-transitory computer-readable media according to claim 16, wherein, The criteria for initiating termination of the wireless connection include a downlink transmission power level from the access point to the wireless communication device that does not meet a threshold power level.

19. One or more non-transitory computer-readable media according to claim 18, wherein, The threshold power level is an adjusted threshold power level, and the criteria for determining the termination of the wireless connection include generating the adjusted threshold power level by applying an offset to a baseline threshold power level, the offset being based on the difference between the downlink transmission power level of the first set of transmissions and the uplink transmission power level of the second set of transmissions.

20. One or more non-transitory computer-readable media according to claim 18, wherein, The operation further includes determining the threshold power level based on an estimated difference in the received signal strength between the first set of transmissions at the wireless communication device and the second set of transmissions at the access point, the estimated difference being determined using at least the MCS index value of the second set of transmissions.

21. A computer-implemented method, comprising: Identify the access point for the wireless network using wireless communication devices: The downlink transmission power level of the transmission from the access point is identified by the wireless communication device; Identify a threshold power level for initiating a connection to the access point, the threshold power level being based on the lowest downlink transmission power level at which the wireless communication device or another wireless communication device previously connected to the access point with at least a threshold success rate; Determine whether the downlink transmission power level of the transmission from the access point meets the threshold power level; as well as In response to determining that the downlink transmission power level of the transmission from the access point meets the threshold power level, the wireless communication device initiates a connection process to establish a wireless connection between the wireless communication device and the access point.

22. A computer-implemented method, comprising: Establish a wireless connection between the wireless communication device and the access point used for the wireless network; Identify uplink transmissions successfully transmitted from the wireless communication device to the access point; Determine the downlink transmission power level corresponding to the uplink transmission successfully transmitted from the wireless communication device to the access point; Identify the minimum acceptable uplink transmission quality level; A threshold downlink power level is determined for initiating termination of the wireless connection between the wireless communication device and the access point, the threshold downlink power level being based on the downlink transmission power level at the receiver for one or more downlink transmissions corresponding to one or more uplink transmissions successfully transmitted from the wireless communication device to the access point at the minimum acceptable uplink transmission quality level. as well as The threshold downlink power level is used to determine whether to initiate the termination of the wireless connection between the wireless communication device and the access point.

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