PATENT DOCUMENT

Publication Number: US-9549337-B2
Application Number: US-201414501870-A
Country: US
Kind Code: B2

Title: Dynamic backoff in Wi-Fi calling

Abstract:
In order to improve the quality of a telephone call communicated over a wireless local area network (WLAN), an electronic device (such as a cellular telephone) may obtain one or more performance metrics based on communication with another electronic device (such as an access point) via a connection in the WLAN. For example, the electronic device may receive the one or more performance metrics from the other electronic device and/or may determine the one or more performance metrics based on the performance of the communication. Then, the electronic device may compare the one or more performance metrics with an interference criterion. If the interference criterion is met, the electronic device may perform a remedial action, such as selectively discontinuing use of the WLAN to communicate the telephone call for a time interval. Otherwise, the electronic device may continue using the WLAN to communicate the telephone call.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an interface circuit configured to communicate a Wi-Fi call with another electronic device using a connection in a wireless local area network (WLAN); 
 a processor; and 
 a memory, wherein the memory stores a program module, and wherein the program module is configured to be executed by the processor, the program module including:
 instructions for obtaining one or more performance metrics based on at least the performance of the communication with the other electronic device; 
 instructions for comparing the one or more performance metrics with an interference criterion; 
 instructions for performing a remedial action when the interference criterion is met; 
 instructions for discontinuing the remedial action after a time interval, wherein the length of the time interval depends on at least a number of times that the remedial action has been taken; and 
 instructions for using the connection in the WLAN to communicate the Wi-Fi call. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the one or more performance metrics include at least one of: a received signal strength indicator from the other electronic device, a signal-to-noise ratio, a transmit packet error rate, a beacon error rate, a successful transmit data rate, a request-to-send failure rate, a successful receive data rate and a successful Transmission Control Protocol connection rate. 
     
     
       3. The electronic device of  claim 1 , wherein the one or more performance metrics include at least one of: an instantaneous value of a first performance metric, and an average value of a second performance metric. 
     
     
       4. The electronic device of  claim 1 , wherein the interference criterion includes at least one of:
 a received signal strength indicator exceeding a first threshold and a transmit packet error rate exceeding a second threshold; 
 a difference between a transmit packet error rate with and without request-to-send at a common data rate exceeding a third threshold; 
 an increase in the transmit packet error rate during communication as a data rate is decreased; 
 a number of request-to-send requests exceeding a fourth threshold; a decreasing data rate while the received signal strength indicator is approximately constant; 
 a number of co-channel transmissions exceeding a fifth threshold; and 
 a medium busy time exceeding a sixth threshold. 
 
     
     
       5. The electronic device of  claim 1 , wherein the remedial action includes at least one or more of:
 avoiding using the WLAN for Voice-over-Internet-Protocol (VoIP) communication for a time interval, 
 avoiding using an access point associated with the WLAN for VoIP communication for the time interval, and 
 transitioning the communication of the Wi-Fi call to a cellular-telephone network. 
 
     
     
       6. The electronic device of  claim 1 , wherein the time interval is increased after each instance of the remedial action. 
     
     
       7. The electronic device of  claim 1 , wherein the Wi-Fi call uses VoIP. 
     
     
       8. The electronic device of  claim 1 , wherein the program module further includes, after the instructions for performing the remedial action, instructions for selectively discontinuing the remedial action. 
     
     
       9. The electronic device of  claim 8 , wherein the remedial action is selectively discontinued when at least one of the following occurs: the interference criterion is no longer met, the connection is re-associated with another WLAN, the Wi-Fi call is communicated via a cellular-telephone network, the cellular-telephone network is unavailable, and a performance metric of the cellular-telephone network is less than a threshold. 
     
     
       10. The electronic device of  claim 1 , wherein the program module further includes:
 instructions for dynamically updating the interference criterion based at least on a coverage of the WLAN. 
 
     
     
       11. The electronic device of  claim 1 , wherein the program module further includes:
 instructions for dynamically updating the interference criterion based at least on a determination of whether the WLAN is capable of supporting Wi-Fi calling. 
 
     
     
       12. An electronic device, comprising:
 an interface circuit, coupled to an antenna, configured to communicate a Wi-Fi call with another electronic device using a connection in a wireless local area network (WLAN), wherein the interface circuit is further configured to: 
 obtain one or more performance metrics based on the performance of the communication with the other electronic device; 
 compare the one or more performance metrics with an interference criterion; 
 determine interference criterion is met; 
 perform a remedial action; 
 discontinue the remedial action after a time interval, wherein the length of the time interval depends on a number of times that the remedial action has been taken; and 
 use the connection in the WLAN to communicate the Wi-Fi call. 
 
     
     
       13. The electronic device of  claim 12 , wherein obtaining the one or more performance metrics involves calculating a performance metric. 
     
     
       14. The electronic device of  claim 12 , wherein the one or more performance metrics include at least one of: a received signal strength indicator from the other electronic device, a signal-to-noise ratio, a transmit packet error rate, a beacon error rate, a successful transmit data rate, a request-to-send failure rate, a successful receive data rate and a successful Transmission Control Protocol connection rate. 
     
     
       15. The electronic device of  claim 12 , wherein the interference criterion includes at least one of:
 a received signal strength indicator exceeding a first threshold and a transmit packet error rate exceeding a second threshold; 
 a difference between a transmit packet error rate with and without request-to-send at a common data rate exceeding a third threshold; 
 an increase in the transmit packet error rate during communication as a data rate is decreased; 
 a number of request-to-send requests exceeding a fourth threshold; 
 a decreasing data rate while the received signal strength indicator is approximately constant; 
 a number of co-channel transmissions exceeding a fifth threshold; and 
 a medium busy time exceeding a sixth threshold. 
 
     
     
       16. The electronic device of  claim 12 , wherein the remedial action includes at least one or more of: avoiding using the WLAN for VoIP communication for a time interval, avoiding using an access point associated with the WLAN for VoIP communication for the time interval, and transitioning the communication of the Wi-Fi call to a cellular-telephone network. 
     
     
       17. The electronic device of  claim 16 , wherein the time interval is increased after each instance of the remedial action. 
     
     
       18. The electronic device of  claim 12 , wherein the Wi-Fi call uses VoIP. 
     
     
       19. The electronic device of  claim 12 , wherein the program module further includes, after the instructions for performing the remedial action, instructions for selectively discontinuing the remedial action. 
     
     
       20. A processor-based method for communicating a Wi-Fi call with another electronic device using a connection in a wireless local area network (WLAN), wherein the method comprises:
 obtaining one or more performance metrics based on the performance of the communication with the other electronic device; 
 comparing the one or more performance metrics with an interference criterion; 
 using the processor, determining the interference criterion is met and performing a remedial action; 
 discontinuing the remedial action after a time interval, wherein the length of the time interval depends on a number of times that the remedial action has been taken; and 
 using the connection in the WLAN to communicate the Wi-Fi call. 
 
     
     
       21. An electronic device,
 an antenna; 
 an interface circuit, coupled to the antenna, configured to communicate with another electronic device using a connection in a wireless local area network (WLAN); 
 a processor; and 
 a memory, wherein the memory stores a program module, and wherein the program module is configured to be executed by the processor, the program module including: 
 instructions for obtaining one or more performance metrics based on the performance of the communication with the other electronic device; 
 instructions for comparing the one or more performance metrics with a communication criterion, wherein the communication criterion is based on a beacon data rate during the communication; 
 instructions for performing a remedial action when the communication criterion is met; 
 instructions for discontinuing the remedial action after a time interval, wherein the length of the time interval depends on a number of times that the remedial action has been taken; and 
 instructions for using the connection in the WLAN to communicate additional information. 
 
     
     
       22. The electronic device of  claim 21 , wherein the remedial action includes transitioning to at least one of: another WLAN, and a cellular-telephone network. 
     
     
       23. An electronic device, comprising:
 an interface circuit, coupled to an antenna, configured to communicate with another electronic device using a connection in a wireless local area network (WLAN), wherein the interface circuit is further configured to: 
 obtain one or more performance metrics based on the performance of the communication with the other electronic device; 
 compare the one or more performance metrics with a communication criterion, wherein the communication criterion is based on a beacon data rate during the communication; 
 determine that the communication criterion is met; 
 perform a remedial action based on at least the determination; 
 discontinue the remedial action after a time interval, wherein the length of the time interval depends on a number of times that the remedial action has been taken; and 
 use the connection in the WLAN to communicate additional information. 
 
     
     
       24. The electronic device of  claim 23 , wherein the remedial action includes transitioning to at least one of: another WLAN, and a cellular-telephone network. 
     
     
       25. A processor-based method for communicating information with another electronic device using a connection in a wireless local area network (WLAN), wherein the method comprises:
 obtaining one or more performance metrics based on the performance of the communication with the other electronic device; 
 comparing the one or more performance metrics with a communication criterion, wherein the communication criterion is based on a beacon data rate during the communication; 
 performing a remedial action when the communication criterion is met; 
 discontinue a remedial action after a time interval, wherein the length of the time interval depends on a number of times that the remedial action has been taken; and 
 use the connection in the WLAN to communicate additional information. 
 
     
     
       26. The method of  claim 25 , wherein the remedial action includes transitioning to at least one of: another WLAN, and a cellular-telephone network.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 62/046,743, entitled “Dynamic Backoff in Wi-Fi Calling,” by Xiaowen Wang, Ajoy K. Singh, Wen Zhao, Shu Du, Kapil Chhabra, and Rudy E. Rawlins, filed on Sep. 5, 2014, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     Field 
     The described embodiments relate to techniques for improving communication performance in a wireless network. More specifically, the described embodiments relate to techniques for determining whether a wireless network can support Wi-Fi calling. 
     Related Art 
     Many modern electronic devices include a networking subsystem that is used to wirelessly communicate with other electronic devices. For example, these electronic devices can include a networking subsystem with a cellular network interface (UMTS, LTE, etc.), a wireless local area network interface (e.g., a wireless network such as described in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard (which is sometimes referred to as ‘Wi-Fi®’) or Bluetooth® from the Bluetooth Special Interest Group of Kirkland, Wash.), and/or another type of wireless interface. 
     Because of the wireless-communication capability and the widespread availability of Wi-Fi access points, electronic devices are now being used to communicate telephone calls (which is sometimes referred to as ‘Wi-Fi calling’). However, the ad-hoc deployment of the Wi-Fi access points, as well as the radio characteristics of the license-free spectrum using in Wi-Fi, can degrade the quality of Wi-Fi networks. This variable performance can result in dropped calls and poor call quality. 
     SUMMARY 
     The described embodiments relates to an electronic device that facilitates Wi-Fi calling. This electronic device includes: an antenna; and an interface circuit, coupled to the antenna, which communicates a Wi-Fi call with another electronic device using a connection in a wireless local area network (WLAN). The electronic device also include: a processor and memory. The memory stores a program module that is executed by the processor. This program module includes instructions for: obtaining one or more performance metrics based on the performance of the communication with the other electronic device; comparing the one or more performance metrics with an interference criterion; performing a remedial action when the interference criterion is met; and, otherwise, using the connection in the WLAN to communicate the Wi-Fi call. 
     Note that the WLAN may include a Wi-Fi network. 
     Moreover, obtaining the one or more performance metrics may involve calculating a performance metric. Furthermore, the one or more performance metrics may include: a received signal strength indicator from the other electronic device, a signal-to-noise ratio, a transmit packet error rate, a beacon error rate, a successful transmit data rate, a request-to-send failure rate, a successful receive data rate and/or a successful Transmission Control Protocol connection rate. In some embodiments, the one or more performance metrics include: an instantaneous value of a first performance metric, and/or an average value of a second performance metric. 
     Additionally, the interference criterion may include: a received signal strength indicator exceeding a first threshold and a transmit packet error rate exceeding a second threshold; a difference between a transmit packet error rate with and without request-to-send at a common data rate exceeding a third threshold; an increase in the transmit packet error rate during communication as a data rate is decreased; a number of request-to-send requests exceeding a fourth threshold; a decreasing data rate while the received signal strength indicator is approximately constant; a number of co-channel transmissions exceeding a fifth threshold; and/or a medium busy time exceeding a sixth threshold. 
     Moreover, the remedial action may include: avoiding using the WLAN for Voice-over-Internet-Protocol (VoIP) communication for a time interval, avoiding using an access point associated with the WLAN for VoIP communication for the time interval, and/or transitioning the communication of the Wi-Fi call to a cellular-telephone network. Note that the time interval may be increased after each instance of the remedial action. 
     Furthermore, the Wi-Fi call may be communicated using VoIP. 
     After the instructions for performing the remedial action, the program module may include instructions for selectively discontinuing the remedial action. For example, the remedial action may be selectively discontinued when: the interference criterion is no longer met, the connection is re-associated with another WLAN, the Wi-Fi call is communicated via a cellular-telephone network, the cellular-telephone network is unavailable, and/or a performance metric of the cellular-telephone network is less than a threshold. 
     Another embodiment provides a computer-program product for use with the electronic device. This computer-program product includes instructions for at least some of the operations performed by the electronic device. 
     Another embodiment provides an electronic device with an antenna and an interface circuit that is configured to perform at least some of the aforementioned operations of the program module. 
     Another embodiment provides a method for communicating the Wi-Fi call with the other electronic device using the connection in the WLAN, which may be performed by an embodiment of the electronic device. During operation, the electronic device obtains the one or more performance metrics based on the performance of the communication with the other electronic device. Then, the electronic device compares the one or more performance metrics with the interference criterion. Moreover, the electronic device performs the remedial action when the interference criterion is met. Otherwise, the electronic device uses the connection in the WLAN to communicate the Wi-Fi call. 
     Another embodiment provides a second electronic device. This second electronic device includes: an antenna; and an interface circuit, coupled to the antenna, which communicates with another electronic device using a connection in a WLAN. This second electronic device includes: a processor and memory. The memory stores a program module that is executed by the processor, and includes instructions for: obtaining one or more performance metrics based on the performance of the communication with the other electronic device; comparing the one or more performance metrics with a communication criterion, where the communication criterion is based on a beacon data rate during the communication; performing a remedial action when the communication criterion is met; and, otherwise, using the connection in the WLAN to communicate additional information. 
     Note that the remedial action may include transitioning to: another WLAN, and/or a cellular-telephone network. 
     Another embodiment provides a computer-program product for use with the second electronic device. This computer-program product includes instructions for at least some of the operations performed by the second electronic device. 
     Another embodiment provides a second electronic device with an antenna and an interface circuit that is configured to perform at least some of the aforementioned operations of the program module. 
     Another embodiment provides a method for communicating information with the other electronic device using the connection in the WLAN, which may be performed by an embodiment of the second electronic device. During operation, the second electronic device obtains the one or more performance metrics based on the performance of the communication with the other electronic device. Then, the second electronic device compares the one or more performance metrics with the communication criterion, where the communication criterion is based on a beacon data rate during the communication. Moreover, the second electronic device performs the remedial action when the communication criterion is met. Otherwise, the second electronic device uses the connection in the WLAN to communicate additional information. 
     This Summary is provided merely for purposes of illustrating some exemplary embodiments, so as to provide a basic understanding of some aspects of the subject matter described herein. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a block diagram illustrating electronic devices wirelessly communicating in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a flow diagram illustrating a method for communicating between the electronic devices in  FIG. 1  in accordance with an embodiment of the present disclosure. 
         FIG. 3  is a drawing illustrating communication between the electronic devices of  FIG. 1  in accordance with an embodiment of the present disclosure. 
         FIG. 4  is a flow diagram illustrating a method for communicating between the electronic devices of  FIG. 1  in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a drawing illustrating communication between the electronic devices of  FIG. 1  in accordance with an embodiment of the present disclosure. 
         FIG. 6  is a block diagram illustrating one of the electronic devices of  FIG. 1  in accordance with an embodiment of the present disclosure. 
     
    
    
     Note that like reference numerals refer to corresponding parts throughout the drawings. Moreover, multiple instances of the same part are designated by a common prefix separated from an instance number by a dash. 
     DETAILED DESCRIPTION 
     In order to improve the quality of a telephone call communicated over a wireless local area network (WLAN), an electronic device (such as a cellular telephone) may obtain one or more performance metrics based on communication with another electronic device (such as an access point) via a connection in the WLAN. For example, the electronic device may receive the one or more performance metrics from the other electronic device and/or may determine the one or more performance metrics based on the performance of the communication. Then, the electronic device may compare the one or more performance metrics with an interference criterion. If the interference criterion is met, the electronic device may perform a remedial action, such as selectively discontinuing use of the WLAN to communicate the telephone call for a time interval. Otherwise, the electronic device may continue using the WLAN to communicate the telephone call. 
     In this way, this communication technique may improve the quality of the telephone call and, more generally, the communication between the electronic device and the other electronic device. For example, the communication technique may allow an interference condition to be reliably identified and avoided. Consequently, the communication technique may reduce user frustration and, thus, may improve the user experience when using the electronic device. 
     In general, the information communicated between the electronic device and the other electronic device in the communication technique may be conveyed in packets that are transmitted and received by radios in the electronic device and the other electronic device in accordance with a communication protocol, such as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, Bluetooth® (from the Bluetooth Special Interest Group of Kirkland, Wash.), a cellular-telephone communication protocol and/or another type of wireless interface. In the discussion that follows, Wi-Fi® is used as an illustrative example. 
     The communication between the electronic devices is shown in  FIG. 1 , which presents a block diagram illustrating electronic devices  110  and  112  wirelessly communicating. In particular, these electronic devices may wirelessly communicate while: detecting one another by scanning wireless channels, transmitting and receiving beacons or beacon frames on wireless channels, establishing connections (for example, by transmitting connect requests), and/or transmitting and receiving packets (which may include the request and/or additional information as payloads). 
     As described further below with reference to  FIG. 6 , electronic devices  110  and  112  may include subsystems, such as a networking subsystem, a memory subsystem and a processor subsystem. In addition, electronic devices  110  and  112  may include radios  114  in the networking subsystems. More generally, electronic devices  110  and  112  can include (or can be included within) any electronic devices with networking subsystems that enable electronic devices  110  and  112  to wirelessly communicate with another electronic device. This can comprise transmitting beacons on wireless channels to enable electronic devices to make initial contact with or detect each other, followed by exchanging subsequent data/management frames (such as connect requests) to establish a connection (which is sometimes referred to as a ‘Wi-Fi connection’), configure security options (e.g., IPSec), transmit and receive packets or frames via the connection, etc. 
     As can be seen in  FIG. 1 , wireless signals  116  (represented by a jagged line) are transmitted by a radio  114 - 1  in electronic device  110 . These wireless signals  116  are received by radio  114 - 2  in electronic device  112 . In particular, electronic device  110  (such as a cellular telephone) may transmit packets with information to electronic device  112  (such as an access point in a WLAN or a Wi-Fi network). Alternatively or additionally, electronic device  112  may transmit packets with information to electronic device  110 . For example, a user of electronic device  110  may conduct a telephone call with another user using a Voice-over-Internet Protocol (VoIP) on the WLAN (which is sometimes referred to as ‘Wi-Fi calling’ or a ‘VoIP call over Wi-Fi’). More generally, the user may communicate data using Voice-over-Internet Protocol. This capability may be useful, such as when a cellular-telephone data communication protocol (e.g., LTE) is unavailable or has poor performance. In addition, this capability may allow the user to avoid roaming charges. 
     However, as noted previously, because many access points are deployed in an ad-hoc manner, and because of the radio characteristics of the license-free spectrum used in Wi-Fi, the quality of Wi-Fi networks is often more variable than cellular-telephone networks. Consequently, a Wi-Fi network may not always be usable for Wi-Fi calling. In order to prevent dropped calls and/or dropped packets, the communication technique implemented by electronic device  110  distinguishes between a ‘good’ Wi-Fi connection or Wi-Fi network from a ‘bad’ one. In particular, as described further below with reference to  FIGS. 2 and 3 , electronic device  110  may determine if the WLAN has an acceptable amount of interference. (In the present discussion, interference may be associated with neighboring Wi-Fi networks or stations, communication using other communication protocols, emissions from electronic devices such as a microwave oven, etc.) If yes, electronic device  110  may continue to use the WLAN for Wi-Fi calling and, more generally, communicating information using VoIP. However, if the WLAN has an unacceptable amount of interference, electronic device  110  may perform a remedial action, such as discontinuing using the WLAN for Wi-Fi calling and/or communicating information using VoIP. 
     For example, based on the performance of the communication using the connection, electronic device  110  may obtain one or more performance metrics. This may involve receiving the one or more performance metrics from electronic device  112  and/or calculating the one or more performance metrics. In general, a wide variety of performance metrics may be used, including: a received signal strength indicator (RSSI) from electronic device  112 , a signal-to-noise ratio (SNR), a transmit packet error rate, a beacon error rate, a successful transmit data rate, a request-to-send (RTS) failure rate, a successful receive data rate, a successful Transmission Control Protocol (TCP) connection rate and/or a performance metric that (directly or indirectly) characterizes a quality of the communication between electronic devices  110  and  112 . Note that the one or more performance metrics may include: an instantaneous value of a first performance metric, and/or an average value of a second performance metric. In particular, the average value may be determined using a low-pass filter, averaging of multiple measurements and/or systematic under-relaxation (e.g., y(i)=α×Δy+(1−α)·y(i−1), where α is a convergence factor such as 0.1 or 0.16). 
     Then, electronic device  110  may compare the one or more performance metrics with an interference criterion. While RSSI can be used to assess the performance or the quality of the communication, RSSI alone is often insufficient for determining whether or not there is interference, and packets can get dropped even when the RSSI is good. Consequently, the interference criterion may include: an RSSI exceeding a first threshold (such as −65 dB) and a transmit packet error rate exceeding a second threshold (such as 10%); a difference between a transmit packet error rate with and without RTS at a common data rate exceeding a third threshold (e.g., when the transmit packet error rate is higher with RTS than without RTS); an increase in the transmit packet error rate during communication with electronic device  112  as the data rate is decreased (so that the transmit packet error rate at a lower data rate such as 6 Mbps exceeds the transmit packet error rate at a higher data rate such as 78 Mbps); a number of RTS requests received from electronic device  112  exceeding a fourth threshold (such as 1, 2, 5 or 10); a decreasing data rate received from electronic device  112  while the RSSI is approximately constant; a number of co-channel transmissions from other stations or WLAN networks exceeding a fifth threshold (such as 1, 2, 5 or 10); and/or a medium busy time exceeding a sixth threshold (such as 70-80% of the communication time). In an exemplary embodiment, the presence of interference is determined based on the average RSSI, a transmit packet error rate and an RTS metric. More generally, the interference criterion may indicate that the performance of the Wi-Fi connection and/or the Wi-Fi network is degraded or unacceptable (e.g., there is an increased risk of a dropped call and/or dropped packets) because of interference (or probable interference) associated with communication with or among other electronic devices (not shown). 
     If the interference criterion is met or achieved, electronic device  110  may perform a remedial action (which is sometimes referred to as ‘dynamic backoff’). Otherwise, electronic device  110  may continue using the connection in the WLAN to communicate a Wi-Fi call and/or information using VoIP (i.e., electronic device  110  may continue normal processing of a Wi-Fi call, which may include checking additional conditions to determine if a Wi-Fi call can occur). Note that the remedial action may include: avoiding using the WLAN for VoIP communication for a time interval (such as 1, 5, 10, 30, 60 or 7200 min.), avoiding using an access point associated with the WLAN (such as electronic device  112 ) for VoIP communication for the time interval (such as blacklisting the associated basic service set identification or the service set identification), and/or transitioning the communication of the information to a cellular-telephone network. More generally, the remedial action may include one or more actions that reduce the likelihood of a dropped call and/or dropped packets on the Wi-Fi connection. Thus, the remedial action may include changing a Wi-Fi calling policy to try to use the cellular-telephone network whenever possible. 
     After performing the remedial action, electronic device  110  may perform one or more additional operations. For example, electronic device  110  may repeat the communication technique. If the remedial action is repeated, the time interval may be increased (such as by using an exponential backoff timer that doubles after each instance of the remedial action). In particular, the time interval may be increased after each instance of the remedial action. Alternatively or additionally, electronic device  110  may selectively discontinue the remedial action (such as by cancelling the backoff timer). For example, the remedial action may be discontinued when: the interference criterion is no longer met (i.e., the interference is improved or eliminated), the Wi-Fi connection is re-associated with another WLAN (such as a WLAN associated with another access point) or has switched to another channel, the information is communicated via a cellular-telephone network (i.e., electronic device  110  may transition the communication to a cellular-telephone network), the cellular-telephone network is unavailable or no longer available (so that in order to continue the communication the Wi-Fi network needs to be used), and/or a performance metric of the cellular-telephone network is less than a threshold (e.g., the communication performance on the Wi-Fi network may be better than the cellular-telephone network). 
     In an alternative embodiment of the communication technique (which is described further below with reference to  FIGS. 4 and 5 ), electronic device  110  dynamically determines a roaming criterion (and, more generally, a communication criterion) for transitioning from the WLAN to another WLAN based on a data rate used in the communication. For example, the data rate may be associated with beacons transmitted by electronic device  112  (which is sometimes referred to as a ‘beacon data rate’). Because the data rate associated with the beacons is known, electronic device  110  can use the beacons to obtain and/or to determine the one or more performance metrics. 
     For example, after obtaining the one or more performance metrics based on the performance of the communication with electronic device  112 , electronic device  110  may compare the one or more performance metrics with a communication criterion, where the communication criterion is based on a beacon data rate during the communication. If the communication criterion is met, electronic device  110  may perform a remedial action (such as transitioning the communication to another WLAN and/or a cellular-telephone network). Otherwise, electronic device  110  may use the connection in the WLAN to communicate information. 
     In particular, in a typical consumer Wi-Fi network, the beacon data rate may be 1 Mbps, while in an enterprise environment the beacon data rate may be 12 or 24 Mbps. As the beacon data rate increases, the coverage of the Wi-Fi network decreases or shrinks. Consequently, there may be more roaming, so that the chance of a Wi-Fi call handing off to a cellular-telephone network occurs more frequently. 
     In this embodiment of the communication technique, the roaming threshold (or the communication criterion) for Wi-Fi to Wi-Fi network transitions or Wi-Fi to cellular-telephone network transitions is dynamically selected based on the beacon data rate (and, more generally, the communication data rate). For example, in a home environment with a beacon data rate of 1 Mbps, a VoIP call can stay on a Wi-Fi network longer without sacrificing audio quality. Thus, in this case, the communication criterion may be an RSSI less than −85 dB and an SNR less than 3 dB. Alternatively, with a beacon data rate of 12 Mbps, the communication criterion may be an RSSI less than −80 dB and an SNR less than 12 dB. 
     In the described embodiments, processing a packet or frame in either of electronic devices  110  and  112  includes: receiving wireless signals  116  with the packet or frame; decoding/extracting the packet or frame from received wireless signals  116  to acquire the packet or frame; and processing the packet or frame to determine information contained in the packet or frame (such as the request or additional information in the payload, e.g., a Wi-Fi call). 
     Although we describe the network environment shown in  FIG. 1  as an example, in alternative embodiments, different numbers or types of electronic devices may be present. For example, some embodiments comprise more or fewer electronic devices. As another example, in another embodiment, different electronic devices are transmitting and/or receiving packets or frames. 
     We now describe embodiments of a method.  FIG. 2  presents a flow diagram illustrating method  200  for communicating between the electronic devices in  FIG. 1 , which may be performed by an electronic device (such as electronic device  110  in  FIG. 1 ). During operation, the electronic device obtains the one or more performance metrics (operation  210 ) based on the performance of the communication with the other electronic device via the connection in the WLAN. Then, the electronic device compares the one or more performance metrics with the interference criterion. For example, the electronic device may determine whether the interference criterion is met or not (operation  212 ). In some embodiments, the interference criterion is met if the one or more performance metrics exceed and/or are less than one or more thresholds. 
     Moreover, the electronic device performs the remedial action (operation  214 ) when the interference criterion is met. Otherwise (operation  212 ), the electronic device uses the connection in the WLAN (operation  216 ) to communicate additional information (such as communicating information via VoIP). 
     In some embodiments, the electronic device optionally performs one or more operations (operation  218 ), such as discontinuing the remedial action. 
     In an exemplary embodiment, at least some of the operations in method  200  are performed by a program module that is executed in an environment (such as the operating system) of the electronic device. Alternatively, at least some of the operations in method  200  may be performed by an interface circuit in the electronic device. 
     The communication technique is further illustrated in  FIG. 3 , which presents a drawing illustrating communication between electronic devices  110  and  112  ( FIG. 1 ). In particular, interface circuit  310  in electronic device  110  may communicate information  312  with electronic device  112 . Based on this communication, a processor  314  in electronic device  110  may determine one or more performance metrics  316 . Then, processor  314  compares  318  the one or more performance metrics with the interference criterion. If the interference criterion is met, processor  314  provides an instruction  320  to interface circuit  310  to perform remedial action  322 . 
     In these ways, the electronic device may facilitate reliable and high-quality communication between the electronic devices. In particular, there may be fewer dropped calls and/or dropped packets because of interference during Wi-Fi calls and/or communication using VoIP. 
     As noted previously, another embodiment of the communication technique may be used to dynamically select a roaming criterion or threshold (i.e., the communication criterion). This is shown in  FIG. 4 , which presents a flow diagram illustrating method  400  for communicating between the electronic devices in  FIG. 1 , which may be performed by an electronic device (such as electronic device  110  in  FIG. 1 ). During operation, the electronic device obtains the one or more performance metrics (operation  410 ) based on the performance of the communication with the other electronic device via the connection in the WLAN. Then, the electronic device compares the one or more performance metrics with the communication criterion, where the communication criterion is based on a beacon data rate during the communication. For example, the electronic device may determine whether the communication criterion is met or not (operation  412 ). In some embodiments, the communication criterion is met if the one or more performance metrics exceed and/or are less than one or more thresholds. 
     Moreover, the electronic device performs the remedial action (operation  414 ) when the communication criterion is met. Otherwise (operation  412 ), the electronic device uses the connection in the WLAN (operation  416 ) to communicate additional information (such as communicating information via VoIP). 
     In some embodiments, the electronic device optionally performs one or more operations (operation  418 ), such as discontinuing the remedial action. 
     In an exemplary embodiment, at least some of the operations in method  400  are performed by a program module that is executed in an environment (such as the operating system) of the electronic device. Alternatively, at least some of the operations in method  400  may be performed by an interface circuit in the electronic device. 
     The communication technique is further illustrated in  FIG. 5 , which presents a drawing illustrating communication between electronic devices  110  and  112  ( FIG. 1 ). In particular, interface circuit  510  in electronic device  110  may communicate information  512  with electronic device  112 . Based on this communication, a processor  514  in electronic device  110  may determine one or more performance metrics  516 . Then, processor  514  compares  518  the one or more performance metrics with the communication criterion. If the communication criterion is met, processor  514  provides an instruction  520  to interface circuit  510  to perform remedial action  522 . 
     In these ways, the electronic device may facilitate reliable and high-quality communication between the electronic devices. In particular, if the WLAN coverage is sufficient (as determined based on the beacon data rate), the threshold for transitioning to another WLAN and/or a cellular-telephone network may be reduced. This dynamic roaming criterion may allow a user of the electronic device to use Wi-Fi calling advantageously, such as when the Wi-Fi network is capable of supporting Wi-Fi calling with good quality and with fewer transitions (and, thus, fewer dropped calls and/or dropped packets). 
     In some embodiments of methods  200  ( FIG. 2 ) and  400  ( FIG. 4 ), there may be additional or fewer operations. Moreover, the order of the operations may be changed, and/or two or more operations may be combined into a single operation. 
     We now describe embodiments of the electronic device.  FIG. 6  presents a block diagram illustrating an electronic device  600 , such as electronic device  110  in  FIG. 1 . This electronic device includes processing subsystem  610 , memory subsystem  612 , and networking subsystem  614 . Processing subsystem  610  includes one or more devices configured to perform computational operations. For example, processing subsystem  610  can include one or more microprocessors, application-specific integrated circuits (ASICs), microcontrollers, programmable-logic devices, and/or one or more digital signal processors (DSPs). 
     Memory subsystem  612  includes one or more devices for storing data and/or instructions for processing subsystem  610  and networking subsystem  614 . For example, memory subsystem  612  can include dynamic random access memory (DRAM), static random access memory (SRAM), and/or other types of memory. In some embodiments, instructions for processing subsystem  610  in memory subsystem  612  include: one or more program modules or sets of instructions (such as program module  622  or operating system  624 ), which may be executed by processing subsystem  610 . Note that the one or more computer programs may constitute a computer-program mechanism. Moreover, instructions in the various modules in memory subsystem  612  may be implemented in: a high-level procedural language, an object-oriented programming language, and/or in an assembly or machine language. Furthermore, the programming language may be compiled or interpreted, e.g., configurable or configured (which may be used interchangeably in this discussion), to be executed by processing subsystem  610 . 
     In addition, memory subsystem  612  can include mechanisms for controlling access to the memory. In some embodiments, memory subsystem  612  includes a memory hierarchy that comprises one or more caches coupled to a memory in electronic device  600 . In some of these embodiments, one or more of the caches is located in processing subsystem  610 . 
     In some embodiments, memory subsystem  612  is coupled to one or more high-capacity mass-storage devices (not shown). For example, memory subsystem  612  can be coupled to a magnetic or optical drive, a solid-state drive, or another type of mass-storage device. In these embodiments, memory subsystem  612  can be used by electronic device  600  as fast-access storage for often-used data, while the mass-storage device is used to store less frequently used data. 
     Networking subsystem  614  includes one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations), including: control logic  616 , an interface circuit  618  and one or more antennas  620 . For example, networking subsystem  614  can include a Bluetooth networking system, a cellular networking system (e.g., an 3G/4G network such as UMTS, LTE, etc.), a universal serial bus (USB) networking system, a networking system based on the standards described in IEEE 802.11 (e.g., a Wi-Fi networking system), an Ethernet networking system, and/or another networking system. 
     Networking subsystem  614  includes processors, controllers, radios/antennas, sockets/plugs, and/or other devices used for coupling to, communicating on, and handling data and events for each supported networking system. Note that mechanisms used for coupling to, communicating on, and handling data and events on the network for each network system are sometimes collectively referred to as a ‘network interface’ for the network system. Moreover, in some embodiments a ‘network’ between the electronic devices does not yet exist. Therefore, electronic device  600  may use the mechanisms in networking subsystem  614  for performing simple wireless communication between the electronic devices, e.g., transmitting advertising or beacon frames and/or scanning for advertising frames transmitted by other electronic devices. 
     Within electronic device  600 , processing subsystem  610 , memory subsystem  612 , and networking subsystem  614  are coupled together using bus  628 . Bus  628  may include an electrical, optical, and/or electro-optical connection that the subsystems can use to communicate commands and data among one another. Although only one bus  628  is shown for clarity, different embodiments can include a different number or configuration of electrical, optical, and/or electro-optical connections between the subsystems. 
     In some embodiments, electronic device  600  includes a display subsystem  626  for displaying information on a display, which may include a display driver and the display, such as a liquid-crystal display, a multi-touch touchscreen, etc. 
     Electronic device  600  can be (or can be included in) any electronic device with at least one network interface. For example, electronic device  600  can be (or can be included in): a desktop computer, a laptop computer, a server, a media player (such as an MP3 player), an appliance, a subnotebook/netbook, a tablet computer, a smartphone, a cellular telephone, a piece of testing equipment, a network appliance, a set-top box, a personal digital assistant (PDA), a toy, a controller, a digital signal processor, a game console, a computational engine within an appliance, a consumer-electronic device, a portable computing device, a personal organizer, a sensor, a user-interface device and/or another electronic device. 
     Although specific components are used to describe electronic device  600 , in alternative embodiments, different components and/or subsystems may be present in electronic device  600 . For example, electronic device  600  may include one or more additional processing subsystems  610 , memory subsystems  612 , networking subsystems  614 , and/or display subsystems  626 . Additionally, one or more of the subsystems may not be present in electronic device  600 . Moreover, in some embodiments, electronic device  600  may include one or more additional subsystems that are not shown in  FIG. 6 . For example, electronic device  600  can include, but is not limited to, a data collection subsystem, an audio and/or video subsystem, an alarm subsystem, a media processing subsystem, and/or an input/output (I/O) subsystem. Also, although separate subsystems are shown in  FIG. 6 , in some embodiments, some or all of a given subsystem or component can be integrated into one or more of the other subsystems or component(s) in electronic device  600 . For example, in some embodiments program module  622  is included in operating system  624 . 
     Moreover, the circuits and components in electronic device  600  may be implemented using any combination of analog and/or digital circuitry, including: bipolar, PMOS and/or NMOS gates or transistors. Furthermore, signals in these embodiments may include digital signals that have approximately discrete values and/or analog signals that have continuous values. Additionally, components and circuits may be single-ended or differential, and power supplies may be unipolar or bipolar. 
     An integrated circuit may implement some or all of the functionality of networking subsystem  614 , such as a radio. Moreover, the integrated circuit may include hardware and/or software mechanisms that are used for transmitting wireless signals from electronic device  600  and receiving signals at electronic device  600  from other electronic devices. Aside from the mechanisms herein described, radios are generally known in the art and hence are not described in detail. In general, networking subsystem  614  and/or the integrated circuit can include any number of radios. Note that the radios in multiple-radio embodiments function in a similar way to the described single-radio embodiments. 
     In some embodiments, networking subsystem  614  and/or the integrated circuit include a configuration mechanism (such as one or more hardware and/or software mechanisms) that configures the radio(s) to transmit and/or receive on a given communication channel (e.g., a given carrier frequency). For example, in some embodiments, the configuration mechanism can be used to switch the radio from monitoring and/or transmitting on a given communication channel to monitoring and/or transmitting on a different communication channel. (Note that ‘monitoring’ as used herein comprises receiving signals from other electronic devices and possibly performing one or more processing operations on the received signals, e.g., determining if the received signal comprises an advertising frame, etc.) 
     While a communication protocol compatible with Wi-Fi standards was used as an illustrative example, the described embodiments of the communication technique may be used in a variety of network interfaces. Furthermore, while some of the operations in the preceding embodiments were implemented in hardware or software, in general the operations in the preceding embodiments can be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations in the preceding embodiments may be performed in hardware, in software or both. For example, at least some of the operations in the communication technique may be implemented using program module  622 , operating system  624  (such as a driver for interface circuit  618 ) or in firmware in interface circuit  618 . Alternatively or additionally, at least some of the operations in the communication technique may be implemented in a physical layer, such as hardware in interface circuit  618 . 
     While the preceding embodiments used VoIP communication as an illustrative example, in other embodiments the communication technique may be applied to communication of arbitrary information or data via a connection in a WLAN. 
     In the preceding description, we refer to ‘some embodiments.’ Note that ‘some embodiments’ describes a subset of all of the possible embodiments, but does not always specify the same subset of embodiments. 
     The foregoing description is intended to enable any person skilled in the art to make and use the disclosure, and is provided in the context of a particular application and its requirements. Moreover, the foregoing descriptions of embodiments of the present disclosure have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the present disclosure to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Additionally, the discussion of the preceding embodiments is not intended to limit the present disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Metadata:
Filing Date: 20140930
Publication Date: 20170117
Grant Date: 20170117
Priority Date: 20140905
Inventors: WANG XIAOWEN
SINGH AJOY K.
ZHAO WEN
DU SHU
CHHABRA KAPIL
RAWLINS RUDY E.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W36/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W28/0236", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W40/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0022", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W76/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W76/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W28/0236", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W40/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W40/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W76/10", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 55438805