PATENT DOCUMENT

Publication Number: US-9491607-B2
Application Number: US-201213398545-A
Country: US
Kind Code: B2

Title: Wireless scan and advertisement in electronic devices

Abstract:
An electronic device performs a scan of each wireless channel in a sequence of wireless channels to detect advertising frames transmitted from other electronic devices. When performing the scan, the electronic device waits for a next transmit time. After the next transmit time, the electronic device configures the electronic device to monitor a next wireless channel from the sequence of wireless channels. The electronic device then monitors the next wireless channel for the advertising frames for a scanning time interval, wherein a duration of the scanning time interval is set in accordance with one or more transmit times used for transmitting advertising frames on the wireless channels in the sequence of wireless channels. When wireless channels from the sequence of wireless channels remain to be scanned, the electronic device returns to wait for a next transmit time.

Claims:
What is claimed is: 
     
       1. A method for wirelessly communicating between electronic devices, comprising:
 configuring a first electronic device to transmit advertising frames on a home wireless channel, wherein the home wireless channel is one wireless channel in a sequence of wireless channels associated with a plurality of electronic devices; 
 identifying, with the first electronic device, the sequence of wireless channels; 
 scanning, with the first electronic device, the sequence of wireless channels by:
 configuring, after a first transmit time, the first electronic device to monitor a first wireless channel in the sequence of wireless channels; 
 monitoring, during a first scanning time interval, the first wireless channel for an advertising frame sent from an electronic device associated with the first wireless channel; and 
 configuring, after the first scanning time interval, the first electronic device to transmit an advertising frame on the home wireless channel during a second transmit time following the first scanning time interval, wherein the duration of time between the first transmit time and the second transmit time is a transmit interval, and wherein each wireless channel in the sequence of wireless channels has a unique transmit interval duration. 
 
 
     
     
       2. The method of  claim 1 , wherein scanning with the first electronic device further comprises:
 transmitting, on the first electronic device&#39;s home wireless channel, an advertising frame during the first transmit time. 
 
     
     
       3. The method of  claim 2 , wherein the sequence of wireless channels comprise wireless channels from a predetermined group of social wireless channels, and wherein the first electronic device&#39;s home wireless channel is a channel from the group of social wireless channels. 
     
     
       4. The method of  claim 2 , wherein configuring the first electronic device to monitor the first wireless channel in the sequence of wireless channels further comprises:
 waiting a predetermined time after the first transmit time before configuring the electronic device to monitor the first wireless channel. 
 
     
     
       5. The method of  claim 2 , wherein the duration of the first scanning time interval is equal to the transmit interval minus an overhead value, wherein the overhead value comprises a sum of:
 a time for configuring the first electronic device to transmit on the first electronic device&#39;s home wireless channel; 
 a time for transmitting an advertising frame on the first electronic device&#39;s home wireless channel; and 
 a time for configuring the first electronic device to monitor the first wireless channel in the sequence of wireless channels. 
 
     
     
       6. The method of  claim 5 , wherein the first scanning time interval is a predetermined multiple of the overhead value. 
     
     
       7. The method of  claim 1 , wherein the advertising frame sent by the electronic device associated with the first wireless channel comprises information for communicating with the electronic device associated with the first wireless channel. 
     
     
       8. The method of  claim 1 , wherein the method further comprises:
 generating, by the first electronic device, the sequence of wireless channels, wherein the sequence of wireless channels comprises a plurality of subsequences, each subsequence comprising a group of social wireless channels arranged in a predetermined order. 
 
     
     
       9. An electronic device that wirelessly communicates with other electronic devices, comprising:
 a first electronic device comprising a processing subsystem configured to:
 configure a first electronic device to transmit advertising frames on a home wireless channel, wherein the home wireless channel is one wireless channel in a sequence of wireless channels associated with a plurality of electronic devices; 
 identify, with the first electronic device, the sequence of wireless channels; 
 scan, with the first electronic device, the sequence of wireless channels by:
 configuring, after a first transmit time, the first electronic device to monitor a first wireless channel in the sequence of wireless channels; 
 monitoring, during a first scanning time interval, the first wireless channel for an advertising frame sent from an electronic device associated with the first wireless channel; and 
 configuring, after the first scanning time interval, the first electronic device to transmit an advertising frame on the home wireless channel during a second transmit time following the first scanning time interval, wherein the duration of time between the first transmit time and the second transmit time is a transmit interval, and wherein each wireless channel in the sequence of wireless channels has a unique transmit interval duration. 
 
 
 
     
     
       10. The electronic device of  claim 9 , wherein the processing subsystem is further configured to:
 transmit, on the first electronic device&#39;s home wireless channel, an advertising frame during the first transmit time. 
 
     
     
       11. The electronic device of  claim 10 , wherein the sequence of wireless channels comprise wireless channels from a predetermined group of social wireless channels, and wherein the first electronic device&#39;s home wireless channel is a channel from the group of social wireless channels. 
     
     
       12. The electronic device of  claim 10 , wherein, when configuring the first electronic device to monitor the first wireless channel in the sequence of wireless channels, the processing subsystem is further configured to:
 wait a predetermined time after the first transmit time before configuring the electronic device to monitor the first wireless channel. 
 
     
     
       13. The electronic device of  claim 10 , wherein the duration of the first scanning time interval is equal to the transmit interval minus an overhead value, wherein the overhead value comprises a sum of:
 a time for configuring the first electronic device to transmit on the first electronic device&#39;s home wireless channel; 
 a time for transmitting an advertising frame on the first electronic device&#39;s home wireless channel; and 
 a time for configuring the first electronic device to monitor the first wireless channel in the sequence of wireless channels. 
 
     
     
       14. The electronic device of  claim 13 , wherein the first scanning time interval is a predetermined multiple of the overhead value. 
     
     
       15. The electronic device of  claim 9 , wherein the advertising frame sent by the electronic device associated with the first wireless channel comprises information for communicating with the electronic device associated with the first wireless channel. 
     
     
       16. The electronic device of  claim 9 , wherein the processing subsystem is further configured to generate, by the first electronic device, the sequence of wireless channels, wherein the sequence of wireless channels comprises a plurality of subsequences, each subsequence comprising a group of social wireless channels arranged in a predetermined order. 
     
     
       17. A networking subsystem in an electronic device, comprising:
 a first radio; and 
 a configuration mechanism coupled to the first radio configured to:
 cause, after a first transmit time, the first radio to monitor a first wireless channel in a sequence of wireless channels; 
 cause, during a first scanning time interval, the first radio to monitor the first wireless channel for an advertising frame sent from a second radio associated with the first wireless channel; and 
 cause, after the first scanning time interval, the first radio to transmit an advertising frame during a second transmit time on a home wireless channel following the first scanning time interval, wherein the home wireless channel is one wireless channel in the sequence of wireless channels, wherein the duration of time between the first transmit time and the second transmit time is a transmit interval, and wherein the each wireless channel in the sequence of wireless channels has a unique transmit interval duration. 
 
 
     
     
       18. The networking subsystem of  claim 17 , wherein the configuration mechanism is further configured to transmit, on the first radio&#39;s home wireless channel, an advertising frame during the first transmit time. 
     
     
       19. The networking subsystem of  claim 18 , wherein the sequence of wireless channels comprises wireless channels from a predetermined group of social wireless channels, and wherein the radio&#39;s home wireless channel is a channel from the group of social wireless channels. 
     
     
       20. The networking subsystem of  claim 18 , wherein the configuration mechanism is further configured to:
 wait a predetermined time after the first transmit time before configuring the first radio to monitor the first wireless channel. 
 
     
     
       21. The networking subsystem of  claim 18 , wherein the duration of the first scanning time interval is equal to the transmit interval minus an overhead value, wherein the overhead value comprises a sum of:
 a time for configuring the radio to transmit on the radio&#39;s home wireless channel; 
 a time for transmitting an advertising frame on the radio&#39;s home wireless channel; and 
 a time for configuring the radio to monitor the first wireless channel in the sequence of wireless channels. 
 
     
     
       22. The networking subsystem of  claim 21 , wherein the first scanning time interval is a predetermined multiple of the overhead value. 
     
     
       23. The networking subsystem of  claim 17 , wherein the advertising frame sent by the second radio comprises information for communicating with the first radio. 
     
     
       24. The networking subsystem of  claim 17 , wherein the sequence of wireless channels comprises a plurality of subsequences, each subsequence comprising a group of social wireless channels arranged in a predetermined order.

Description:
BACKGROUND 
     1. Field 
     The described embodiments relate to electronic devices. More specifically, the described embodiments relate to wireless communication between electronic devices. 
     2. 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) standards 802.11), and/or another type of wireless interface. In some of these electronic devices, the network interfaces can be used to detect other electronic devices as part of a process for enabling communication between the electronic devices. For example, one electronic device can broadcast an advertising frame, and another electronic device can monitor for the advertising frame to detect the electronic device. 
     Many of these electronic devices, particularly battery-powered electronic devices, have low power-consumption targets, and so the power that can be allocated for detecting other devices can be minimal. For example, for some devices, a power consumption target for detecting other devices can be in the range of 10 mW/hour. Because the electronic devices require minimal power consumption while detecting other devices, the use of the radios (which typically consumes the largest portion of the allocated power) to detect other devices can be very limited. For example, given the 10 mW/hour target, as little as a few percent of possible radio time (e.g., around 3% of radio time) can be available for detecting other electronic devices. 
     In order to discover other electronic devices that are infrequently monitoring for advertising frames (e.g., when another electronic device is switching in and out of a reduced-power “sleep” state and hence may be monitoring for advertising frames infrequently), a passive scan procedure can be used. Differently than an active transmit procedure that consists of transmitting advertising frames with broadcast probe request frames at arbitrary times from an electronic device, and thus requesting an answer from the other electronic devices and requiring the other electronic device to be monitoring for advertising frames, the passive scan procedure consists in listening on a given wireless channel with a listening time, i.e., a “dwell time,” that is long enough to catch a advertising frame from the other electronic device. Existing implementations of passive scanning use a 110-120 ms dwell time in order to detect periodic advertising frames spaced at a constant 100-104 ms. 
     However, there are two problems with existing implementations that use the constant periods for passive scans that become particularly apparent when multiple devices are attempting to discover one another. A larger number of devices means that many devices in range of each other may be advertising, leading to relatively long discovery times due to contention for channels and the need for individual discovery of multiple other devices. This can lead to a power-consumption problem because, even using the radios as sparingly as possible, the power consumption required for broadcasting advertising frames to be detected using passive scans and performing passive scans is high in comparison with power targets for many battery-powered electronic devices. 
     SUMMARY 
     The described embodiments include an electronic device that wirelessly communicates with other electronic devices. In the described embodiments, the electronic device first determines that a sequence of wireless channels is to be scanned to detect advertising frames transmitted from other electronic devices. The electronic device then performs a scan of each wireless channel in the sequence of wireless channels to detect advertising frames transmitted from other electronic devices. When performing the scan, the electronic device waits for a next transmit time. After the next transmit time, the electronic device configures the electronic device (e.g., a processing subsystem, a networking subsystem, and/or another subsystem in the electronic device) to monitor a next wireless channel from the sequence of wireless channels. The electronic device then monitors the next wireless channel for the advertising frames for a scanning time interval, wherein a duration of the scanning time interval is set in accordance with one or more transmit times used for transmitting advertising frames on the wireless channels in the sequence of wireless channels. When wireless channels from the sequence of wireless channels remain to be scanned, the electronic device returns to wait for a next transmit time. 
     In some embodiments, the electronic device is configured to determine that advertising frames are to be transmitted from the electronic device on a home wireless channel to enable other electronic devices to detect the electronic device. The electronic device then transmits advertising frames by, before each next transmit time, configuring the electronic device to transmit on the home wireless channel, and, at each next transmit time, transmitting an advertising frame from the electronic device on the home wireless channel. 
     In some embodiments, the wireless channels comprise wireless channels from a predetermined group of social wireless channels, and the home wireless channel is a channel from the group of social wireless channels. 
     In some embodiments, each transmit time is separated by a transmit interval from a preceding transmit time and a subsequent transmit time, wherein a duration of the transmit interval is set according to the home wireless channel used in the electronic device. 
     In some embodiments, when configuring the electronic device to monitor the next wireless channel from the sequence of wireless channels after the next transmit time, the electronic device is configured so that, when advertising frames are not being transmitted from the electronic device, the electronic device waits a predetermined time after the next transmit time before configuring the electronic device to monitor the next wireless channel, and, when advertising frames are being transmitted from the electronic device, the electronic device waits until the advertising frame has been transmitted from the electronic device at the next transmit time before configuring the electronic device to monitor the next wireless channel. 
     In some embodiments, the scanning time interval is proportional to the transmit interval minus an overhead value, wherein the overhead value comprises a sum of: (1) a time for configuring the electronic device to transmit on the home wireless channel for the electronic device; (2) a time for transmitting an advertising frame on the home wireless channel from the electronic device; and (3) a time for configuring the electronic device to monitor a next wireless channel from the sequence of wireless channels. 
     In some embodiments, the scanning time interval is at least a predetermined multiple of the overhead value. 
     In some embodiments, each advertising frame comprises information for communicating with another electronic device that transmitted the advertising frame. 
     In some embodiments, the electronic device generates the sequence of wireless channels, wherein the sequence of wireless channels comprises a plurality of subsequences, each subsequence comprising a group of social wireless channels arranged in a predetermined order. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  presents a timeline diagram illustrating the scanning of wireless channels in accordance with the described embodiments. 
         FIG. 2  presents a block diagram illustrating an electronic device in accordance with the described embodiments. 
         FIG. 3  presents a block diagram illustrating an expanded view of a networking subsystem in accordance with the described embodiments. 
         FIG. 4  presents a block diagram illustrating a group of electronic devices wirelessly communicating in accordance with the described embodiments. 
         FIG. 5  presents a block diagram illustrating an advertising frame. 
         FIG. 6  presents a figure illustrating an exemplary sequence of wireless channels in accordance with the described embodiments. 
         FIG. 7  presents a timeline diagram of a scan sequence for a first and second electronic devices in accordance with the described embodiments. 
         FIG. 8  presents a table that shows scan periods for a set of wireless channels in accordance with the described embodiments. 
         FIG. 9  presents a flowchart illustrating a process for scanning a set of wireless channels in accordance with the described embodiments. 
         FIG. 10  presents a flowchart illustrating a process for scanning a set of wireless channels in accordance with the described embodiments. 
         FIG. 11  presents a flowchart illustrating a process for transmitting advertising frames in accordance with the described embodiments. 
     
    
    
     In the figures, like reference numerals refer to the same figure elements. 
     DETAILED DESCRIPTION 
     The following description is presented to enable any person skilled in the art to make and use the described embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those 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 described embodiments. Thus, the described embodiments are not limited to the embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. 
     The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by an electronic device with computing capabilities. For example, the computer-readable storage medium can include volatile memory or non-volatile memory, including flash memory, random access memory (RAM, SRAM, DRAM, RDRAM, DDR/DDR2/DDR3 SDRAM, etc.), magnetic or optical storage mediums (e.g., disk drives, magnetic tape, CDs, DVDs), or other mediums capable of storing data structures or code. Note that in the described embodiments, the computer-readable storage medium does not include non-statutory computer-readable storage mediums such as transmission signals. 
     The methods and processes described in this detailed description can be included in hardware modules. For example, the hardware modules can include, but are not limited to, processors, application-specific integrated circuit (ASIC) chips, field-programmable gate arrays (FPGAs), and other programmable-logic devices. When the hardware modules are activated, the hardware modules perform the methods and processes included within the hardware modules. In some embodiments, the hardware modules include one or more general-purpose circuits that are configured by executing instructions (program code, firmware, etc.) to perform the methods and processes. 
     The methods and processes described in the detailed description section can be embodied as code and/or data that can be stored in a computer-readable storage medium as described above. When an electronic device with computing capabilities reads and executes the code and/or data stored on the computer-readable storage medium, the electronic device performs the methods and processes embodied as data structures and code and stored within the computer-readable storage medium. For example, in some embodiments, a processing subsystem can read the code and/or data from a memory subsystem that comprises the computer-readable storage medium and can execute code and/or use the data to perform the methods and processes. 
     In the following 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 the embodiments. 
     Overview 
     In the described embodiments, an electronic device (e.g., electronic device  200  in  FIG. 2 ) can perform operations to help discover other nearby electronic devices that are available for wirelessly communicating with the electronic device. In these embodiments, the electronic device can both passively scan a set of wireless channels for advertising frames transmitted from other electronic devices, and actively transmit advertising frames on a “home” wireless channel (which is, in some embodiments, one of the social wireless channels) to enable other electronic devices to discover the electronic device. The advertising frames generally contain information that enables electronic devices to determine information about the transmitting electronic device that can be used to enable subsequent communication with the transmitting electronic device. For example, the advertising frames can include information about an availability period during which the transmitting device will be monitoring a given channel for a given period of time to enable the transmitting device to receive frames transmitted from other electronic devices. In the described embodiments, the advertising frames can be management frames or data frames, in accordance with the underlying wireless standard. 
     In the described embodiments, when scanning the wireless channels for advertising frames and/or transmitting the advertising frames, an electronic device can scan and/or transmit using a predetermined set of “social” wireless channels (interchangeably “social channels”). The social wireless channels comprise any group of wireless channels agreed upon in advance that electronic devices can generally expect to be monitored by other electronic devices, thereby enabling simplified communication between electronic devices. For example, in some embodiments, the social channels include channels such as  1 ,  6 ,  11  in the 2.4 GHz band or channels  40 ,  104 , and  153  in the 5 GHz band of the IEEE 802.11 specification. In alternative embodiments, any number of the available channels in the 2.4 GHz and 5 GHz bands can be included in the social channels. Note additionally that the described embodiments are not intended to be limited to the current IEEE 802.11 wireless channels or to the network scheme described in IEEE 802.11. For example, some embodiments can use social channels in the newly-proposed 60 GHz band of the 802.11 specification (i.e., using the 802.11ad standard). Generally, any electronic devices that use an advertising frame scanning and/or transmission scheme similar to the described embodiments can comprise transmission times and scanning intervals as herein described. 
     In the described embodiments, the electronic device comprises a mechanism (e.g., a count-down/count-up timer, or another mechanism) for keeping track of reoccurring/periodic “transmit times,” each of which is separated by a transmit time interval from a preceding transmit time and a subsequent transmit time. At the transmit time, the electronic device may, but is not required to, transmit an advertising frame on the home wireless channel, which can be one of the social channels. In the described embodiments, the duration of the transmit time interval (and hence the time between transmit times) is set according to the social channel that is being used by the electronic device as the home wireless channel. More specifically, each social channel can have a different transmit time interval associated with it. For example, given that an electronic device is using an exemplary social channel  1  as the home wireless channel, a transmit time interval could be 110 ms, whereas for an exemplary social channel  2 , the transmit time interval could be 120 ms, etc. Thus, using exemplary channel  1  as the home wireless channel, a transmit time could occur every 110 ms for the electronic device, and hence the electronic device might, but does not have to, transmit an advertising frame on home channel  1  every 110 ms. 
     As previously described, in the described embodiments, an electronic device can use wireless channel scanning to enable discovery of other nearby electronic devices. In these embodiments, an electronic device uses the above-described transmit times and transmit intervals to determine when and for how long to perform scans of the social channels to detect advertising frames transmitted from other electronic devices on the social channels. More specifically, between transmit times (and assuming that the radio in the electronic device is not being used for another purpose), the electronic device can reconfigure the radio to monitor one of the social channels. Then, as a subsequent transmit time approaches, the electronic device can again reconfigure the radio to enable the optional transmission of the advertising frame on the home channel for the electronic device. In this way, the electronic device can alternate between using the radio to transmit the advertising frames on the home channel, and scanning social channels for advertising frames from other electronic devices. 
       FIG. 1  presents a timeline diagram illustrating the scanning of wireless channels in accordance with the described embodiments. As can be seen in  FIG. 1 , a transmit interval  100  (e.g., 100 ms, 150 ms, 500 ms, or another time) separates a first transmit time  104  and a second transmit time  106 . Between transmit times  104  and  106 , a scan of exemplary social channel  0  is performed by the electronic device for a scanning interval  102 . After transmit time  106 , a scan of exemplary social channel  1  is performed by the electronic device (again for the scanning interval  102 ). This pattern can repeat indefinitely, with corresponding transmit times indicating the start of a next transmit interval  100 , during which a social channel can be scanned for a scanning interval  102 . 
     As can be seen in  FIG. 1 , scanning interval  102  is shorter than the transmit interval  100 . Generally, scanning interval  102  is proportional to transmit interval  100  minus an overhead value. The overhead value includes an amount of time used for configuring the radio for monitoring a social channel for advertising frames, along with restoring the radio at the next transmit time. For example, the overhead value can include a sum of the amount of time that is used to (a) configure the radio to transmit an advertising frame on the home channel; (b) transmit the advertising frame on the home channel; and (c) configure the radio to monitor (scan) the given social channel. Although we describe this overhead value, in alternative embodiments, the overhead value includes additional or fewer times, including time for performing other operations for the radios, etc. 
     Because each of the social channels has a corresponding transmit interval and the scanning interval is configured using the duration of the transmit interval, the described embodiments can be configured so that two electronic devices on different home wireless channels from among the social channels can find each other in a limited number of scans of the social channels (note that the home wireless channels in this example are social channels). For example, in the described embodiments, a first electronic device that is using a first social channel as its home wireless channel can almost always find a second electronic device that is using a second social channel as its home wireless channel in two passes/scans of the set of social channels (during a “pass,” each of the social channels is separately scanned for a scanning interval as shown in  FIG. 1 ). More specifically, assuming that the first electronic device scans the second social channel, but does not encounter an advertising frame transmitted by the second electronic device during a first pass, in the described embodiments, because of the relative timing of the scanning intervals for the first electronic device (which are based on the first social channel) and the transmit times for the second electronic device (which are based on the second social channel), the first device almost always encounters an advertising frame transmitted by the second electronic device during a second pass. Note that this example assumes that the second device is transmits an advertising frame during at least the second pass. Specifically, the second device transmits an advertising frame at the transmit time for the second device that aligns with the second pass/scan by the first device. Generally, the second device should be transmitting advertising frames (and not optionally not transmitting advertising frames as described herein) in order to ensure that a first device discovers a second device within two passes/scans of the set of social channels. 
     Electronic Device 
       FIG. 1  presents a block diagram illustrating electronic device  200  in accordance with the described embodiments. Electronic device  200  includes processing subsystem  202 , memory subsystem  204 , and networking subsystem  206 . 
     Processing subsystem  202  includes one or more devices configured to perform computational operations. For example, processing subsystem  202  can include one or more microprocessors, application-specific integrated circuits (ASICs), microcontrollers, and/or programmable-logic devices. 
     Memory subsystem  204  includes one or more devices for storing data and/or instructions for processing subsystem  202  and networking subsystem  206 . For example, memory subsystem  204  can include dynamic random access memory (DRAM), static random access memory (SRAM), and/or other types of memory. In addition, memory subsystem  204  can include mechanisms for controlling access to the memory. In some embodiments, memory subsystem  204  includes a memory hierarchy that comprises one or more caches coupled to a memory in electronic device  200 . In some of these embodiments, one or more of the caches is located in processing subsystem  202 . 
     In some embodiments, memory subsystem  204  is coupled to one or more high-capacity mass-storage devices (not shown). For example, memory subsystem  204  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  204  can be used by electronic device  200  as fast-access storage for often-used data, while the mass-storage device is used to store less frequently used data. 
     Networking subsystem  206  includes one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations). For example, networking subsystem  206  can include a Bluetooth™ networking system, a cellular networking system (e.g., a 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  206  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. In the following description, we refer to the mechanisms used for coupling to, communicating on, and handling data and events on the network for each network system collectively as the “interface” or “network interface” for the network system. Note that in some embodiments, a “network” between the devices does not yet exist, and hence electronic device  200  uses the mechanisms in networking subsystem  206  for performing simple wireless communication between the devices, e.g., transmitting advertising frames and/or scanning the social channels for advertising frames transmitted by other electronic devices as herein described. 
     Within electronic device  200 , processing subsystem  202 , memory subsystem  204 , and networking subsystem  206  are coupled together using bus  210 . Bus  210  is an electrical, optical, or electro-optical connection that the subsystems can use to communicate commands and data among one another. Although only one bus  210  is shown for clarity, different embodiments can include a different number or configuration of electrical, optical, or electro-optical connections between the subsystems. 
     Electronic device  200  can be (or can be included in) any device with at least one network interface. For example, electronic device  200  can be (or can be included in) a desktop computer, a laptop computer, a server, a media player, an appliance, a subnotebook/netbook, a tablet computer, a smart phone, a piece of testing equipment, a network appliance, a set-top box, a personal digital assistant (PDA), a toy, a controller, or another device. 
     Although we use specific components to describe electronic device  200 , in alternative embodiments, different components and/or subsystems may be present in electronic device  200 . For example, electronic device  200  may include one or more additional processing subsystems  202 , memory subsystems  204 , and/or networking subsystems  206 . Additionally, one or more of the subsystems may not be present in electronic device  200 . Moreover, in some embodiments, electronic device  200  may include one or more additional subsystems that are not shown in  FIG. 1 . For example, electronic device  200  can include, but is not limited to, a display subsystem for displaying information on a display, 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. 1 , in some embodiments, some or all of a given subsystem can be integrated into one or more of the other subsystems in electronic device  200 . 
       FIG. 3  presents a block diagram illustrating an expanded view of networking subsystem  206  in accordance with the described embodiments. As can be seen in  FIG. 3 , networking subsystem  206  comprises radio  300  and configuration mechanism  302 . Radio  300  includes hardware and/or software mechanisms that are used for transmitting wireless signals from electronic device  200  and receiving signals at electronic device  200  from other electronic devices. Aside from the mechanisms herein described, radios such as radio  300  are generally known in the art and hence are not described in detail. 
     Although networking subsystem  206  can include any number of radios  300 , embodiments with one radio  300  are herein described. Note, however, that the radios  300  in multiple-radio embodiments function in a similar way to the described single-radio embodiments. 
     Configuration mechanism  302  in radio  300  comprises one or more hardware and/or software mechanisms used to configure the radio to transmit and/or receive on a given channel (i.e., frequency). For example, in some embodiments, the configuration mechanism  302  can be used to switch radio  300  from monitoring and/or transmitting on a given channel in the 2.4 GHz and 5 GHz band of channels described in the IEEE 802.11 specification to monitoring and/or transmitting on a different channel. (Note that “monitoring” as used herein comprises receiving signals from other electronic devices and possibly performing one or more processing steps on the received signals, e.g., determining if the received signal comprises an advertising frame, etc.) 
     In the described embodiments, it takes time for configuration mechanism  302  to switch radio  300  from transmitting or receiving on a given channel to transmitting or receiving on a different channel. For example, in some embodiments, switching from transmitting or monitoring on a first channel to transmitting or monitoring on a second channel takes approximately 3 ms. Additionally, it takes time for radio  300  to transmit an advertising frame. For example, in some embodiments, transmitting an advertising frame takes approximately 3 ms. Hence, in some embodiments, an approximate total time for switching radio  300  to transmit on a first channel, transmitting a advertising frame on the first channel, and switching the radio to monitor on a different channel is approximately 9 ms. In the described embodiments, this “overhead” value is used to determine scanning interval  102  (as is described in more detail below). 
     Wirelessly Communicating Between Electronic Devices 
       FIG. 4  presents a block diagram illustrating electronic devices  402 - 406  wirelessly communicating in accordance with the described embodiments. More specifically, electronic devices  402 - 406  are wirelessly communicating while discovering one another by scanning wireless channels and/or transmitting advertising frames on wireless channels using the techniques herein described. 
     In some embodiments, electronic devices  402 - 406  comprise subsystems similar to subsystems  202 - 206  shown in  FIG. 2 , although alternative embodiments may include different types or arrangements of subsystems. In addition, radios  408 - 412  in electronic devices  402 - 406  can include mechanisms similar to those shown in radio  300  in  FIG. 3 . Generally, electronic devices  402 - 406  can include (or can be included within) any devices with a networking subsystem  206  that enables the electronic device to wirelessly communicate with another electronic device. This can comprise transmitting (e.g., multicasting) advertising frames on wireless channels to enable devices to make initial contact, followed by exchanging subsequent data/management frames (perhaps based on the information in the initially-multicast advertising frames) to establish and/or join an existing wireless network, establish a communication session (e.g., a TCP/IP session, etc.), configure security options (e.g., IPSEC), and/or exchange data/management frames for other reasons. 
     As can be seen in  FIG. 4 , wireless signals  414  (represented by jagged lines) are transmitted from a radio  412  in electronic device  406 . In the described embodiments, radio  412  (as well as radios  408 - 410 ) comprises mechanisms similar to configuration mechanism  302  that can be used to configure the radio  412  to transmit signals using certain designated channels. For example, in the described embodiments, electronic device  406  can dynamically configure (or re-configure) radio  412  so that wireless signals  414  are transmitted on a “home” wireless channel for electronic device  406 . 
     Wireless signals  414  comprise data/management frames that are encoded/included in wireless signals  414  using techniques known in the art. The frames comprise at least an advertising frame  500  (see  FIG. 5 ) that contains information that enables other electronic devices to determine one or more properties of electronic device  406 , e.g., an availability window during which electronic device  406  will be monitoring a home channel for data/management frames in signals transmitted from other electronic devices. (Note that, although we describe the embodiments using advertising frame  500 , the data/management frames in wireless signals  414  can comprise any type of data/management frames.) In some embodiments, the frames are multicast frames, which comprise information that indicates that any receiving electronic device should process the frames. 
     Wireless signals  414  are received by radios  408  and  410  in electronic devices  402  and  404 , respectively. For the sake of example, it is assumed that electronic device  402  is monitoring the wireless channel upon which wireless signals  414  are transmitted, but electronic device  404  is not. Thus, although wireless signals  414  are “received” by both devices (e.g., both devices are in range of wireless signals  414 ), only electronic device  402  processes the advertising frame  500  in wireless signals  414 . In the described embodiments, both of electronic devices  402  and  404  can be performing a scan of the social wireless channels such as herein described, although electronic device  402  is the only one of the two devices that is monitoring the wireless channel upon which electronic device  406  transmits the advertising frame  500  at the time of the example. Note that, using the scanning technique herein described, electronic device  404 , which misses a current advertising frame  500  from electronic device  406 , will almost always receive the advertising frame  500  from electronic device  406  within two scans of the set of social channels (i.e., within two passes through the set of social channels, scanning each channel), as described below. 
     In the described embodiments, processing the advertising frame  500  in electronic device  402  comprises: receiving wireless signals  414  with the encoded/included advertising frame  500 : decoding/extracting the advertising frame  500  from received wireless signals  414  to acquire the advertising frame  500 ; and processing the advertising frame  500  to determine information contained in the advertising frame  500 . As indicated above, the advertising frame  500  comprises information that enables electronic device  402  to determine one or more properties of electronic device  406 . Using the information, electronic device  402  can determine at least how/when to communicate with electronic device  406 . 
     Although we describe the network environment shown in  FIG. 4  as an example, in alternative embodiments, different numbers or types of devices may be present. For example, some embodiments comprise more or fewer electronic devices. As another example, in another embodiment, different devices are transmitting and/or receiving frames. 
     Advertising Frame 
       FIG. 5  presents a block diagram illustrating an advertising frame  500 . As shown in  FIG. 5 , advertising frame  500  comprises header  502  and payload  504 . Header  502  comprises information about an electronic device that transmitted the advertising frame  500 , and payload  504  comprises information that can enable another device to determine one or more properties of the electronic device that transmitted the advertising frame  500 . For example, in some embodiments, from the information in payload  504 , a receiving electronic device can determine addressing information for the transmitting electronic device (although addressing information and other information may also be able to be determined from the header of advertising frame  500 ), one or more channels upon which the transmitting electronic device will be monitoring for and/or transmitting data/management frames (e.g., multicasting data/management frames) during an “availability period,” and/or a schedule of when the transmitting electronic device will be monitoring for and/or transmitting data/management frames. 
     Note that advertising frame  500  is simply one example of an advertising frame, in some embodiments, advertising frame  500  comprises more, fewer, or different types of information. Generally, any information that can help in transmitting the advertising frame to a recipient, determining information about a transmitter (including an availability window for the transmitter), and/or determining other information that enables a receiving device to wirelessly communicate with another electronic device (e.g., a third electronic device) can be contained within advertising frame  500 . 
     Channel Sequence 
     In order to discover other electronic devices using the passive scanning technique, an electronic device can first determine a sequence of channels to be scanned (or can acquire a predetermined sequence, e.g., from a memory subsystem  204  in the electronic device). The sequence of channels can comprise repeated instances of the set of social channels arranged in a predetermined order (e.g., sequential, random, increasing/decreasing, alternating even/odd, etc.). For example,  FIG. 6  presents a figure illustrating a possible sequence  600  of wireless channels in accordance with the described embodiments. As can be seen in  FIG. 6 , the social channels in the sequence  600  of channels comprise exemplary channels  1 ,  2 ,  4 ,  5 , and  6 . In subsequence  602  the social channels are arranged in a first random order, and in second subsequence  604  the social channels are arranged in a second random order. When scanning the social channels, an electronic device can proceed through the sequence of channels in order, one channel at a time, monitoring each of the channels for advertising frames transmitted by other devices during a scanning interval  102 . 
     Although we present the arrangement in  FIG. 6 , any arrangement of wireless channels can be used, including shorter, longer (as indicated by the ellipses in  FIG. 6 ), or different sequences  600 . Generally, any arrangement or sequence of a set of wireless channels that is to be scanned for advertising frames or wireless signals from another device can be used. 
     Advertising Frame Scanning and Transmission Process 
     As previously indicated, the described embodiments can perform a scanning process during which an electronic device  200  configures a radio  300  in a networking subsystem  206  to monitor for advertising frames  500  transmitted from another electronic device  200 . In these embodiments, the electronic device can determine that a transmit time  104  has occurred and optionally transmit an advertising frame  500  on a home wireless channel. After transmitting the advertising frame  500 , or, when no advertising frame  500  is transmitted at the transmit time, when a predetermined time (e.g., 5 ms) has passed since the transmit time  104 , the electronic device  200  can configure radio  300  to monitor a next social channel from a sequence  600  of social channels in an attempt to detect advertising frames  500  transmitted by other electronic devices  200 . The channel can be monitored for a scanning interval  102 , and then the electronic device  200  can reconfigure the radio  300  to transmit an advertising frame  500  on the home channel (or to prepare for a scan of a next social channel in the sequence  600 ). This process can continue until a predetermined condition is met. For example, the process can continue until the electronic device  200  has scanned each social channel in the sequence  600  of social channels a given number of times, until the electronic device  200  has encountered one or more other electronic devices, until a predetermined time has passed, and/or until another condition is met. 
     In the described embodiments, the transmit interval  100  that is used to determine when to (optionally) transmit advertising frames  500  and when to scan the social channels is set in accordance with the social channel that is being used as the home wireless channel in an electronic device  200 . In these embodiments, if the transmit intervals  100  were equal (or one was a multiple of the other) for two or more of the social channels, it is possible that a first electronic device that was scanning the social channels would be unable to find a second electronic device on a different home channel because the second electronic device could be transmitting advertising frames  500  at the same times as the first electronic device, and hence channel scans performed by the first electronic device could fall between the transmissions of advertising frames  500  by the second device. For this reason, the described embodiments use a different transmit interval for each of the social channels. For example, some embodiments could use the following transmit intervals for exemplary social channels  1 ,  6 , and  11  in the 2.4 GHz band and  40 ,  104 , and  153  in the 5 GHz band as described in the IEEE 802.11 specification: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Exemplary Per-Channel Transmit Interval 
               
            
           
           
               
               
               
            
               
                   
                   
                 TRANSMIT 
               
               
                   
                 CHANNEL 
                 INTERVAL 
               
               
                   
                   
               
               
                   
                 CH 1 
                 100 ms 
               
               
                   
                 CH 6 
                 110 ms 
               
               
                   
                 CH 11 
                 120 ms 
               
               
                   
                 CH 40 
                 130 ms 
               
               
                   
                 CH 104 
                 140 ms 
               
               
                   
                 CH 153 
                 150 ms 
               
               
                   
                   
               
            
           
         
       
     
     In alternative embodiments, other channels may be used, each with a different transmit interval. For example, in some embodiments, each of the channels in the 802.11g and 802.11a bands as described in the IEEE specification could be used as the social channels. As another example, any predetermined set of wireless channels in a given wireless communication scheme could be used as the social channels. 
     In some embodiments, the transmit interval could be set so that the transmit interval for each nth social channel in a sequence  600  of social channels is as follows:
 
transmit_interval( n )=transmit_interval(0)+ n *delta,
 
with the transmit interval of a first channel in the sequence of social channels (i.e., transmit_interval (0)) equal to, e.g., 100 ms, and the delta being greater than an overhead value that comprises (as described with respect to  FIG. 1 ) a sum of the amount of time that is used to (a) configure the radio to transmit an advertising frame  500  on the home channel; (b) transmit the advertising frame  500  on the home channel; and (c) configure the radio to monitor (scan) a given social channel. For example, if the overhead is 5 ms, the delta can be set to 8 ms, 10 ms, etc. In the described embodiments, transmit_interval (0), i.e., the shortest of the time intervals for the social channels, is configured to be larger than the overhead time by some multiple, e.g., 5, 10, or another multiple.
 
       FIG. 7  presents a timeline diagram of a scan sequence for a first and second electronic devices in accordance with the described embodiments. More specifically,  FIG. 7  shows a “meetup” or discovery of one device by another device while scanning the social channels. Note that  FIG. 7  shows a two-way discovery process in which a first device and a second device are both transmitting advertising frames  500  at transmit intervals and performing scans of a set of social channels. In this arrangement, the first and second electronic devices both find the other device. In alternative embodiments, the discovery may only be one device finding another device, or may be multiple devices finding some number of the other devices. 
     During the exemplary scanning process shown in  FIG. 7 , each device makes two scanning cycles (or “passes”) through a set of social channels; the first electronic device, which uses channel  1  as its home channel, scans wireless channels  0 ,  2 , and  3  twice, and the second electronic device, which uses channel  0  as its home channel, scans wireless channels  1 ,  2 , and  3  twice. Note that the devices need not continue to scan after finding one another, however, in some embodiments, the electronic devices can be configured to scan the social channels a given number of times to enable the discovery of other available electronic devices (e.g., third, fourth, etc. electronic devices), including electronic devices that have not started transmitting advertising frames  500  until one or more scan passes have been made by the first and second electronic devices. 
     As can be seen in  FIG. 7 , the electronic devices discover each other in the second pass. Illustrating this, the transmit time when the advertising frame  500  that is detected by the other device is transmitted is shown in bold for both electronic devices in  FIG. 7 , as is the scan interval in which the advertising frame  500  is detected. However, during the first pass, the first device transmits advertising frames  500  on its home channel  1  at times when the second device is not scanning channel one. Additionally, during the first pass, the second device transmits advertising frames  500  on its home channel  0  at times when the first device is not scanning channel  0 . This is shown by the dashed lines drawn from the transmit times in each of the timelines in the first scan pass. 
     The devices discover each other in the second pass because the devices have “drifted” with respect to one another by at least one overhead value. In other words, because the closest transmit time intervals are separated by at least one overhead value for different social channels (see the exemplary per-channel transmit intervals in Table 1), when the second pass occurs, the transmit times (and hence channel scans) have drifted relative to one another by at least the amount of time for the overhead value. Note that, while this is true for neighboring channels (i.e., channels separated by one overhead value), the drift can be larger for social channels whose transmit times differ by more than one overhead value. This means that a given device should almost always be able to find a second device on a different home channel in a set of social channels within two passes through a sequence of social channels. 
       FIG. 8  presents a table that shows exemplary scan periods for an exemplary set of social channels (channels  1 - 6 ) in accordance with the described embodiments. As can be seen in  FIG. 8 , a scan pass through the social channels scans the 5 social channels aside from a home channel for a device. For example, a device that is using channel  3  as its home channel will scan channels  1 ,  2 ,  4 ,  5 , and  6 . Recall that the scans occur in a scanning interval that is defined using the transmit interval (as shown in  FIGS. 1 and 7 ) and hence a “scan period” in which each of the social channels is scanned is 5 times the duration of a transmit interval for the home channel for an electronic device. An electronic device scans each of the social channels once in a corresponding scan period. For example, as shown in  FIG. 8 , the scan period for an electronic device that is using channel  1  as its home channel is 500 ms, and so the electronic device will scan each of social channels  2 - 6  with a 500 ms period. 
     As shown in  FIG. 8 , one of the scan periods is incompatible with another of the scan periods (shown by the hash marks in channel  3 &#39;s scan of channel  6 ). This occurs because the transmit intervals are multiples of one another. Specifically, channel  3 &#39;s scan period of 600 ms is a multiple of channel  6 &#39;s transmit interval of 150 ms. Thus, in some cases, the transmit times for channels  3  and  6  could be aligned such that the electronic device using channel  3  as the home channel would not discover electronic devices using channel  6  as the home channel. Some embodiments avoid this case by using transmit intervals that are not multiples of one another. Alternative embodiments avoid this case by using different scanning intervals for a given channel and/or using different transmit intervals on a per channel or per-scan-pass basis. 
     Note also that some scan periods (and the underlying scan intervals) are long enough that a device using the scan interval should discover a device on a different channel in a single pass. This is shown with an “X” in a corresponding scan box in  FIG. 8 . For example, a device using channel  6  as its home channel scans with a scanning interval of e.g., 140 ms (within a transmit interval of 150 ms), so a device using channel  1  as its home channel should be discovered in a first pass because the transmit interval for channel  1  is 110 ms, which is short enough for two advertising frames  500  to be transmitted during channel  6 &#39;s scan interval of 140 ms. 
       FIG. 9  presents a flowchart illustrating a process for scanning a set of wireless channels for advertising frames  500  in accordance with the described embodiments. As shown in  FIG. 9 , the process starts when an electronic device  200  determines that a sequence  600  of wireless channels is to be scanned to detect advertising frames  500  transmitted from other electronic devices  200  (step  900 ). This can occur when networking subsystem  206  in electronic device  200  receives a signal (e.g., a scan request, etc.) from an operating system on the device (which can come from an application on the device that is attempting to form connections with other devices) or otherwise determines that a sequence  600  of wireless channels is to be scanned. 
     In some embodiments, networking subsystem  206  can be configured to periodically and automatically scan the wireless channels, which can occur separately from receiving a request from an application/the operating system to perform the scan. However, as described above, the power consumption targets for the electronic device  200  can be restrictive, so the automated scan of the wireless channels can occur infrequently. For example, the device can make a pass through the sequence  600  of channels every 10 s (versus multiple consecutive passes through the sequence  600  for a requested scan). In addition, the sequence  600  of channels for such automatic scans can be different and/or shorter than a sequence  600  for a requested scan. In these embodiments, determining that the sequence  600  of wireless channels is to be scanned such as in step  902  can mean determining that an automatic scan is to be performed. 
     After making the determination, electronic device  200  performs a scan of each wireless channel in the sequence  600  of wireless channels to detect advertising frames  500  transmitted by other electronic devices (step  902 ). The operations performed when scanning each of the wireless channels is described below with respect to  FIG. 10 . 
       FIG. 10  presents a flowchart illustrating a process the electronic device  200  uses to scan the set of wireless channels for advertising frames  500  transmitted by other electronic devices in accordance with the described embodiments. The process shown in  FIG. 10  is an expanded view of step  902  in  FIG. 9 , showing a set of operations performed during step  902  in some embodiments. 
     The process in  FIG. 10  starts when electronic device  200  waits for a next transmit time  104  (step  1000 ). As described above, transmit time  104  is a time at which the electronic device  200  can optionally transmit an advertising frame  500 . However, transmit time  104  is also a time used to indicate when a next wireless channel from a sequence  600  of wireless channels should be scanned. 
     After the next transmit time  104 , electronic device  200  configures itself to monitor a next wireless channel from the sequence  600  of wireless channels (step  1002 ). Configuring electronic device  200  to monitor the next wireless channel comprises performing operations to make it possible for electronic device  200  to receive wireless signals  414  from other electronic devices  200  and process the wireless signals  414  to determine if an advertising frame  500  has been received. This can mean configuring a radio  300  in networking subsystem  206  to receive wireless signals  414  at a corresponding frequency, configuring one or more circuits or processors within networking subsystem  206 /electronic device  200  to extract frames from the received wireless signals  414 , configuring one or more circuits and/or processors in networking subsystem  206 /electronic device  200  to interpret the frames, etc. 
     Note that reconfiguring electronic device  200  to monitor for advertising frames  500  on a next wireless channel “after” the transmit time  104  means one of two things. In the first case, the electronic device  200  is transmitting advertising frames  500  at the transmit time  104 , and hence the radio  300  needs to complete the transmission of the advertising frame  500  before the radio  300  can be reconfigured to monitor the next wireless channel. In the second case, electronic device  200  is not transmitting advertising frames  500  at the transmit time. In this case, the radio  300  can be reconfigured anytime after the transmit time, but before the scanning interval  102  is to begin. In some embodiments, the networking subsystem  206  can wait for a predetermined time after the transmit time  104  (e.g., 7 ms, 12 ms, etc.) before reconfiguring the radio  300 . 
     Electronic device  200  then monitors the wireless channel for the advertising frames  500  for a scanning interval  102  (step  1004 ). When monitoring the wireless channel, electronic device  200  receives wireless signals  414  from other electronic devices  200  on the channel and processes the wireless signals  414  to determine if an advertising frame  500  has been received. When an advertising frame  500  is received, electronic device  200  can use information from the advertising frame  500  in making subsequent communications to the other electronic device from which the advertising frame  500  is received and/or for performing one or more configuration operations in electronic device  200  (e.g., reconfiguring the home channel, etc.). 
     After the scanning interval  102 , electronic device  200  determines if any wireless channels remain to be scanned (step  1006 ). If so, electronic device  200  can return to step  1000  to wait for a next transmit time. Otherwise, if no channels remain to be scanned, the process ends. 
       FIG. 11  presents a flowchart illustrating a process for transmitting advertising frames  500  in accordance with the described embodiments. As described above, some embodiments may perform the scanning process without transmitting advertising frames  500  (e.g., to conserve power). Thus, the transmission of advertising frames is optional. In some embodiments, the electronic device  200  can be automatically and dynamically configured or reconfigured to perform (or not perform) the transmission of advertising frames  500 . For example, the electronic device  200  can transmit advertising frames  500  at N consecutive transmit times, but can then stop transmitting advertising frames  500 . For clarity, in this example it is assumed that the advertising frames are being transmitted at corresponding transmit time (and that electronic device  200  is not optionally not transmitting advertising frames  500 ). 
     The process shown in  FIG. 11  starts when electronic device  200  determines that advertising frames  500  are to be transmitted from an electronic device  200  on a home wireless channel (step  1100 ). This can occur when networking subsystem  206  in electronic device  200  receives a signal (e.g., a transmit request, etc.) from an operating system on the device (which can come from an application on the device that is attempting to form connections with other devices) or otherwise determines that advertising frames  500  are to be transmitted. 
     In some embodiments, networking subsystem  206  can be configured to periodically and automatically transmit advertising frames  500 . However, as described above, the power consumption targets for the electronic device  200  can be restrictive, so the automated transmission of advertising frames  500  can occur infrequently. For example, the device can transmit advertising frames  500  for N consecutive transmit times every 10 s (versus continuous transmissions of advertising frames  500 ). In these embodiments, determining that the advertising frames  500  are to be transmitted as in step  1100  can mean determining that an automatic scan is to be performed. 
     Before a next transmit time, electronic device  200  configures itself to transmit on the home wireless channel (step  1102 ). Configuring electronic device  200  to transmit on the home wireless channel comprises performing operations to make it possible for electronic device  200  to assemble advertising frames  500  and transmit the advertising frames  500  in wireless signals  414  that can be received by other electronic devices. This can mean configuring a radio  300  in networking subsystem  206  to transmit wireless signals  414  at a corresponding frequency and/or configuring one or more circuits or processors within networking subsystem  206 /electronic device  200  to assemble an advertising frame  500  (e.g., collect data for the frame, compute error-correcting values, create the frame itself, etc.). 
     Then, at the corresponding transmit time, the electronic device  200  transmits an advertising frame  500  on the home wireless channel (step  1104 ). This comprises transmitting a wireless signal  414  into which the advertising frame  500  has been embedded/encoded so that other electronic devices can receive the wireless signals and extract from the wireless signals the advertising frame  500 . 
     The foregoing descriptions of embodiments have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the embodiments. The scope of the embodiments is defined by the appended claims.

Metadata:
Filing Date: 20120216
Publication Date: 20161108
Grant Date: 20161108
Priority Date: 20120216
Inventors: VANDWALLE PIERRE B.
DOMINGUEZ CHARLES F.
THOMAS TITO
HARTMAN CHRISTIAAN A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W40/244", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W24/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/244", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47714582