PROCESSING REQUESTS FOR PRECISION TIME MEASUREMENTS

Abstract

A procedure that includes: Receiving, by a first network device (105; 205; 505; 605), a plurality of fine timing measurement (FTM) requests from a second network device (110; 210; 510; 610) over a first channel (120; 571; 670A); Determining, by the first network device (105; 205; 505; 605), channel traffic along the first channel (120; 571; 670A); Accessing a lookup table comprising the channel traffic and an FTM response frequency based on the channel traffic; Selecting the FTM response frequency from the lookup table; Setting the FTM response frequency by the first network device (105; 205; 505; 605) based on the selection; and Responding, by the first network device (105; 205; 505; 605) and based on the FTM response frequency, only to a first number of FTM requests from the plurality of FTM requests and determining not to acknowledge a second number of FTM requests from the plurality of FTM requests.

Description

BACKGROUND

[0001] In general, a wireless local area network (WLAN) can contain one or more access points (APs). Communication devices such as laptops, PCs, smartphones, etc., can connect to the WLAN to exchange data within the network. The communication devices can submit range requests to one or more APs.

[0002] Ranging techniques such as the Fine Timing Measurement (FTM) protocol have gained popularity due to the broad compatibility between APs and communication devices. The FTM protocol typically involves the exchange of messages between APs and communication devices. From the messages, a time of flight, round-trip time, etc., is derived, which is used to determine a position of the communication device relative to the AP. For example, the time of flight can be defined as the total time it takes for signals to travel from the AP to a client device (e.g., the communication device) and from the client device back to the AP. Using the time of flight information, the distance between the AP and the client device can be determined.

[0003] US 2019 / 0 246 349 A1 describes a method for selecting a wireless access point (AP) that relates to the field of communication technologies and a Fine Time Measurement (FTM) technology in a wireless network, wherein a server, upon receiving a query request with a query condition, determines a target AP according to stored service capability information of each of a plurality of APs that support an FTM mechanism and the query condition, and sends a Media Access Control (MAC) address of the target AP and information about a frequency band and a channel used by the target AP to a terminal.

[0004] WO 2021 / 258 100 A1 relates to a method comprising receiving a first Fine Timing Measurement (FTM) request from an initiating station (ISTA), determining a priority classification of the ISTA relative to other ISTAs, and deciding, based at least in part on the priority classification, whether to accept the first FTM request.

[0005] WO 2017 / 026 976 A1 relates to devices, systems, and / or methods for cellular-based fine timing measurement (FTM). For example, a user equipment (UE) may comprise a wireless local area network (WLAN) transceiver; a cellular transceiver for receiving a cellular message from a cellular network containing fine timing measurement (FTM) capability information indicating the capability of one or more WLAN stations (STAs) to support FTM; and a fine timing measurement (FTM) component configured to, based on the FTM capability information, cause the WLAN transceiver to communicate FTM messages with the one or more WLAN STAs.

[0006] US 2016 / 0 353 306 A1 relates to techniques for efficient ranging. According to certain aspects of US 2016 / 0 353 306 A1, techniques are provided for signaling the use of different time unit resolutions for parameters to be used in a ranging method, such as a fine-time measurement (FTM) method.

[0007] US 2019 / 0 349 280 A1 describes a device comprising an interface configured to receive at least one ranging frame from a wireless node. The device further comprises a processing system configured to determine at least one round-trip time (RTT) between the device and the wireless node based on the received at least one ranging frame, determine the quality of the at least one RTT based on the received at least one ranging frame, and generate a feedback frame comprising the at least one RTT and the quality of the at least one RTT. The interface is further configured to output a feedback frame for transmission to the wireless node. SHORT DESCRIPTION

[0008] A method according to claims 1 to 8, a first network device according to claims 9 to 17 and a non-transitory computer-readable storage medium according to claims 18 to 21 are disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present subject matter can best be understood from the following description and the accompanying drawings, which serve to illustrate examples of the present subject matter. Fig. shows a schematic representation of a network according to an example of the present subject matter; Fig. shows a schematic representation of an FTM transaction between a first network device and a second network device, according to an example; Fig. shows a block diagram of a computing device for processing FTM requests according to an example of the present subject matter; The Fig. show a flowchart illustrating a method of operating a first network device according to an example of the present subject matter; Fig. shows a schematic view of a network representing an FTM transaction according to an example of the present subject matter; and Fig. shows a schematic view of a network illustrating the selection of a subset of channels for an FTM transaction according to an example of the present subject matter. DETAILED DESCRIPTION

[0010] The FTM protocol is increasingly used by various client devices and APs. The FTM protocol is used to establish a range between a responding device (e.g., an AP) and the client device. An initiator sends multiple sets of ranging requests / range measurements to various APs. The initiator of the ranging requests can estimate its relative position with respect to the APs. A common implementation is for the client device to act as the initiator of ranging requests and the AP to act as the responder. With many communication devices that support the FTM protocol, each AP in a network can receive multiple ranging requests. Under certain circumstances, the access point can become overloaded with these multiple ranging requests, which consume a lot of airtime. Other client devices, on the other hand, can send multiple ranging requests within short time intervals, which can also overload the AP.With this type of administrative traffic, the access control points are busy responding to these range requests, which overloads the channel on which these devices communicate.

[0011] Furthermore, many wireless networking standards, such as IEEE 802.11 mc, allow both associated and non-associated client devices to make ranging requests. This further increases channel traffic with multiple FTM requests from both associated and non-associated devices. APs would serve associated clients for both FTM and non-FTM-related traffic. Furthermore, APs would respond to the numerous FTM requests from non-associated clients. This introduces additional delays on the channel. For example, if the AP is serving high-priority traffic, such as voice / video or Voice Over Internet Protocol (VOIP) traffic, and receives multiple ranging requests in parallel, it may not be able to respond to the ranging requests while serving the traffic. This could lead to a denial of service for certain client devices.In addition, a client device connected to a particular AP on one channel can still send ranging requests to another AP on a different channel, keeping the APs busy.

[0012] Even with certain wireless network standards that support more than one frequency band, such as a tri-band, there are still issues. For example, certain client devices performing FTM post-association must complete an FTM transaction on one channel. When an AP decides to announce a channel change, all client devices must switch to the new channel. With both associated and non-associated client devices, there is high airtime utilization due to ranging requirements. Therefore, there is a need to address the aforementioned technical deficiencies.

[0013] The present subject matter therefore discloses various examples for handling FTM requests. A first network device receives a plurality of FTM requests from a second network device over a first channel. For brevity, reference is made to the second network device in the singular. However, the plurality of FTM requests may originate from more than one second network device. In one example, the first network device is an access point, and the second network device may be a client device or another access point. The first network device determines channel traffic along the first channel. Based on the channel traffic, the first network device may set an FTM response frequency.

[0014] For example, if channel traffic is high, the FTM response frequency may be adjusted, which involves reducing the FTM response frequency. The FTM response frequency may be a rate at which the first network device responds to FTM requests / marshalling requests. By adjusting the FTM response frequency, the first network device can only respond to a first number of FTM requests from the plurality of FTM requests. Thus, if the first network device determines that the first channel is busy, it adjusts the FTM response frequency and only responds to a certain number of requests, i.e., the first number of FTM requests. In one example, adjusting the FTM response frequency increases the time interval between consecutive FTM exchanges. In the present case, the access party, e.g.the first network device, thus reducing delays in contention when critical requests need to be served or requests from connected devices need to be responded to. It also avoids a potential denial-of-service (DoS) attack due to an increased number of FTM requests on the network. Under certain conditions, a particular network device can send an unlimited number of FTM requests, thereby disrupting the services of the first network device. Such an unlimited sending of FTM requests can be referred to as a DoS attack. In one example, the first network device adjusts the frequency of FTM responses, thereby reducing the likelihood of a denial-of-service attack on other network devices on the network. The features and advantages of the present subject matter can be better understood by considering the following description of specific examples.

[0015] In the drawings, certain features and components may be shown to scale or schematically exaggerated, and certain details of some elements may be omitted for the sake of brevity and without limitation.

[0016] The following description refers to the examples illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used to indicate the same or similar features. Although several examples are described in the description, modifications, adaptations, and other implementations are possible. The following examples do not limit the scope of the present subject matter.

[0017] Fig. shows a schematic view of a network according to an example of the present subject matter. The network 100 includes a first network device 105 (for brevity, reference is made to a single device here, which is not limiting). The network 100 further includes a second network device 110. In the example shown, only one second network device 110 is illustrated. However, there may be more than one second network device 110. The first network device 105 may be an AP, and the second network device may be a client device. The first network device 105 is capable of operating in one or more of the frequency bands including, but not limited to, 2.4 gigahertz (GHz), 5 GHz, and / or 6 GHz.

[0018] The second network device 110 may be a mobile network device, a stationary network device, or another access point. If more than one second network device is present, they may communicate directly with each other via one or more communication networks. Alternatively, they may communicate with each other via the first network device 105 using a suitable wireless communication network.

[0019] The wireless communication network includes an IEEE 802.11 standard. The first network device 105 and the second network device 110 are each equipped with one or more antennas suitable for communication via the IEEE 802.11 standards. In the current example, the first network device 105 and the second network device 110 are compatible with IEEE 802.11ax, IEEE 802.1lac, and other earlier standards.

[0020] The first network device 105 includes hardware and / or a plurality of machine-executable instructions for communicating over a wireless communication network, such as Wireless Fidelity (Wi-Fi). As shown in the figure, the first network device 105 includes, for example, a network unit 106, a processing unit 107, and a non-transitory (computer-readable) storage medium 108. The communication network includes two or more bands, and each band is equipped with a plurality of communication channels.

[0021] The second network device 110 has FTM capabilities and is capable of sending ranging requests to the first network device 105. The ranging requests enable the determination of the distance of the second network device 110 relative to the first network device 105. A first channel 120, over which the first network device 105 and the second network device 110 communicate, may be heavily loaded due to FTM transactions from various associated and non-associated client devices. The associated client devices are devices that have completed an association process and are capable of exchanging real data or application data. The non-associated client devices, on the other hand, can execute / raise certain requests, such as FTM requests, even without completing the association process.The first network device 105 of the present subject is capable of processing management traffic such as FTM requests from these associated or non-associated client devices.

[0022] In one example, the first network device 105 is capable of multi-link operation (MLO). The first network device 105 is capable of operating on one or more of the frequency bands, including, but not limited to, 2.4 GHz, 5 GHz, and / or 6 GHz, and each frequency band may include a plurality of channels 120-122. Accordingly, the second network device 110 (e.g., the client device) is capable of multi-link operation. With the multi-link operation capability, the first network device 105 is capable of conducting FTM transactions across multiple links / channels. The first network device 105 is capable of detecting the channels supported by the second network device 110 and establishing connections to the available channels.

[0023] Fig. shows a schematic view 200 of an FTM transaction 215 between a first network device 205 and a second network device 210, which enables an understanding of the present subject matter. The FTM transaction 215 may consist of one or more FTM bursts. In the illustrated example, the FTM transaction 215 consists of an FTM burst 216. The second network device 210 initiates a ranging request by sending an FTM request 221 to the first network device 205. The first network device 205 responds with an acknowledgment 222. The second network device 210 acts as the initiating device and the first network device 205 as the responding device. The FTM request 221 and the corresponding acknowledgment 222 can be viewed as a handshake process in which the goal of performing the ranging operation is determined.

[0024] Furthermore, the first network device 205 and the second network device 210 may exchange multiple frames corresponding to FTM requests and corresponding acknowledgments. Each FTM request 221, 223, 225 and a corresponding acknowledgment 222, 224, 226 together constitute an "FTM exchange." Thus, each FTM burst may comprise one or more FTM exchanges. In the illustrated example, the FTM transaction 215 comprises only one FTM burst 216. The FTM burst 216 comprises three FTM exchanges 231, 232, 233.

[0025] In the example shown, at time t1_1, the first network device 205 sends a first frame related to an FTM request 223 to the second network device 210. The first network device 205 may record a departure time of the first FTM request 223. At t2_1, the second network device 210 receives the first FTM request 223 and records the arrival time, i.e., t2_1. At t3_1, the second network device 210 responds to the first network device 205 by sending an acknowledgment frame 224 to the first network device 205. At t4_1, the first network device 205 receives the acknowledgment frame 224 and records the time, i.e., t4_1. The departure and arrival times / time stamps t1_1, t2_1, t3_1, t4_1 can be used to determine the round trip time (RTT). Similarly, the time stamps tl_2 to t4_2 correspond to another FTM exchange, i.e., 233. The round trip time is used to determine the parameters for ranging, such as distance.For accuracy, more than one FTM exchange may be negotiated between the first network device 205 and the second network device 210. For example, the FTM burst 216 may include multiple FTM exchanges 231, 232, 233, etc. In one example, the second network device 210 may initiate many such FTM requests, which may be followed by a series of FTM exchanges between the first network device 205 and the second network device 210, resulting in multiple FTM bursts. One or more client devices, such as the second network device, make multiple FTM requests within a short period of time, which may result in contention delays.

[0026] Fig. is a block diagram of a computing device 300 for processing multiple FTM requests according to an example of the present subject matter. Computing device 300 may include an AP. In another example, computing device 300 may function as a client device, such as a computer, a smartphone, etc. In one example, computing device 300 may function as the first network device. In another example, computing device 300 may be part of the first network device.

[0027] Computing device 300 includes a processing unit 302 and a non-transitory (machine-readable) storage medium 304. Processing unit 302 may include one or more central processing units (CPUs), semiconductor-based microprocessors, and / or other hardware devices capable of retrieving and executing instructions stored in non-transitory storage medium 304. Processing unit 302 may retrieve, decode, and execute instructions, such as instructions 306-312, to control processes or operations for handling multiple FTM requests. Non-transitory storage medium 304 may be any electronic, magnetic, optical, or other physical storage device that contains or stores executable instructions. For example, non-transitory storage medium 304 may be encoded with executable instructions, for example, instructions 306-312.In addition, instructions 306-312 may be executed repeatedly and / or they may be executed by any suitable device or devices.

[0028] At 306, computing device 300 receives a plurality of FTM requests from a second network device over a first channel. Instead of a second network device, multiple client devices may send FTM / Ranging requests over the first channel to determine a distance between each client device and the AP. In this way, multiple FTM requests may be received in parallel from the multiple client devices.

[0029] At 308, computing device 300 determines channel utilization along the first channel. Computing device 300 may be configured to determine the channel utilization based on a number of FTM requests received by computing device 300 during a selected period of time. In one example, processing unit 302 of computing device 300 itself determines the channel traffic. In another example, computing device 300 may receive the channel traffic-related information from a traffic indicator unit.

[0030] At 310, computing device 300 adjusts an FTM response frequency based on the channel traffic. The FTM response frequency may be a frequency / rate at which computing device 300 responds to FTM requests made by the client device(s). In one example, the FTM response frequency may be set to a high or optimal value when channel traffic along the first channel is light, thereby accepting the FTM requests and negotiating corresponding FTM bursts. Further, in one example, the FTM response frequency may be predefined for different channel traffic conditions. A lookup table with different FTM response frequencies corresponding to different traffic conditions may be available in computing device 300. Computing device 300 may access the lookup table and select an FTM response frequency based on the determined channel traffic.In another example, the lookup table may be retrieved from a storage device located external to the computing device 300.

[0031] At 312, based on the FTM response frequency setting, computing device 300 responds to a first number of FTM requests from the plurality of FTM requests made by the client device(s). The first number of FTM requests may originate from a single client device. In another example, the first number of FTM requests may originate from two or more client devices. In another example, the first number of FTM requests may originate from a number of client devices from the plurality of client devices. With the FTM response frequency setting, computing device 300 may deny service or not acknowledge certain FTM requests. Computing device 300 reserves airtime to respond to potentially critical service requests, such as service requests from associated devices or high-priority devices.

[0032] The Fig. show a flowchart illustrating a method 400 for operating a first network device at various levels of detail according to an example of the present subject matter. The method 400 may be executed by a processing unit of the first network device, such as an AP. The method includes blocks 405-475, which may be in the form of instructions on a non-transitory storage medium. The method 400 may include further additional intermediate blocks, and the blocks may also be executed in a different order than that shown.

[0033] In block 405, the first network device receives a plurality of FTM requests over a first channel. The plurality of FTM requests may originate from a single client device or from multiple client devices. Also, a few FTM requests from the plurality of FTM requests may be sent in parallel from different client devices or sequentially—each from different client devices.

[0034] In block 410, the first network device enumerates the plurality of FTM requests received from the first network device over a selected period of time. In one example, enumerating the FTM request may include counting a number of FTM requests sent by a particular client device during the selected period of time. Many such client devices may send such multiple FTM requests, and the enumeration may be performed for all network devices. In one example, FTM requests from non-associated devices may also be enumerated. Further, in one example, a counter may be established for each client device that sends multiple FTM requests. In another example, a counter may be triggered when the client device sends a certain number of FTM requests within a second selected period of time.Setting the second selected time period may enable the conservation of processing and memory resources. In one example, after a selected time period, the first network device may reset a counter and begin enumerating a plurality of FTM requests received in a subsequent selected time period.

[0035] In block 415, the first network device compares the plurality of enumerated FTM requests (alternatively referred to as "enumerated FTM requests") to a first request threshold. If the enumerated FTM requests exceed the first request threshold, the first network device may determine that channel traffic is high. If the channel traffic is determined to be high, the first network device may adjust the FTM response frequency, as illustrated in block 430.

[0036] Conversely, if the enumerated FTM requests do not exceed the first request threshold, the first network device checks in block 420 whether the channel traffic on the first channel has exceeded a channel traffic threshold. The channel traffic threshold may be a reference metric used to determine channel traffic. If the channel traffic on the first channel exceeds the channel traffic threshold, a high traffic condition is determined. The channel traffic may increase due to the large number of FTM requests from multiple client devices. In another example, the channel traffic may increase due to the exchange or negotiation of application data / frames, which may be in addition to the FTM-related exchange or negotiation on the first channel.If the channel traffic exceeds the channel traffic threshold, the first network device also determines that the channel traffic is high. The first network device may adjust the FTM response frequency, as shown in block 430.

[0037] Conversely, if at block 420 the channel traffic does not exceed the channel traffic threshold, at block 425 the first network device responds to the multiple FTM requests made during the selected time period. For example, the first network device acknowledges each FTM request from the plurality of FTM requests and negotiates FTM bursts corresponding to each FTM request. In one example, based on the plurality of FTM requests received during the selected time period, the first network device may determine that there is sufficient airtime or bandwidth to satisfy all FTM requests or application data requests from high-priority devices or associated client devices.The first network device saves airtime and avoids a possible denial of service for client devices (which could otherwise have been denied due to the high number of FTM requests within the selected time period).

[0038] As previously mentioned, if the first network device determines in blocks 415 or 420 that channel traffic is high, the first network device adjusts the FTM response frequency in block 430. In one example, the FTM response frequency is set to be between a maximum threshold frequency and a minimum threshold frequency (both inclusive). Both the maximum threshold frequency and the minimum threshold frequency are individually adjustable for each AP. In one example, the minimum frequency threshold and the maximum frequency threshold are preset during setup. In another example, the minimum frequency and the maximum frequency are adjustable by the user / network administrator. In another example, the FTM response frequency adjustment is performed by decreasing the FTM response frequency.In another example, adjusting the FTM response frequency may consist of varying the FTM response frequency in inverse proportion to the channel traffic. Furthermore, the adjusted FTM response frequency may cause an increase in the time interval between consecutive FTM exchanges. In another example, a time interval between FTM exchanges corresponding to an FTM burst may not be varied, and a time interval between consecutive FTM bursts may be varied. In one example, the first channel maintains sufficient bandwidth to respond to all potential requests from an associated or other critical client device.

[0039] In block 435, the first network device checks the availability of a number of channels for connecting to the second network device. In one example, both the first network device and the second network device are multilink devices (MLDs) with MLO capability. In other words, the first network with MLO capability can check and determine whether the second network device is also MLO-capable. If either the first network device or the second network device is not MLO-capable, the first network device negotiates the FTM transaction entirely on the first channel.

[0040] In block 440, the first network device determines one or more channel parameters of each channel from the number of channels determined to be available (alternatively referred to as "available channels"). In one example, the one or more channel parameters may include, but are not limited to, available bandwidth, channel traffic, or the number of network devices / stations on the particular channel. In another example, the first network device may check the available channels and the one or more parameters of each channel from the available channels in parallel.

[0041] In block 445, the first network device checks, based on the one or more channel parameters, whether an FTM transaction corresponding to the first number of requests (from the plurality of requests) can be negotiated on the first channel itself. For example, if the first channel has one or more favorable channel parameters, such as low traffic volume, high bandwidth, etc., then the entire FTM transaction may be executed on the first channel at the set FTM response frequency. In another example, the FTM transaction may be executed on the first channel, and a second channel may be made available for any potential application / data transaction or for high-priority FTM requests from network devices. As illustrated in block 450, the FTM transaction is executed on the first channel.Based on one or more channel parameters, the first network device may decide to execute part of the FTM transaction on a first of the available channels.

[0042] In block 455, the first network device checks whether a subset of the FTM transaction should be executed on a second channel. The first network device checks whether the channel parameters of the second channel are such that the subset of the FTM transaction can be executed on the second channel. In one example, the FTM transaction may comprise two FTM bursts, corresponding to the first number of FTM requests. A first FTM burst may be negotiated on the first channel, and the negotiation of a second FTM burst on the second channel may be verified. In another example, the first network device may compare the one or more channel parameters of the second channel with corresponding reference values. The reference parameters may be preset for a particular AP, or the reference values ​​may be set independently for each AP. The reference value may correspond to a threshold.

[0043] Based on the check in block 455, the first network device may respond in block 460 to a first FTM burst set of the FTM transaction on the first channel and a second burst set of the FTM transaction on the second channel. For example, a "burst set" may include a plurality of FTM exchanges, and each FTM exchange consists of FTM frames and corresponding acknowledgment frames. The terms "first," "second," "another," "another," and "others" are used to refer to similar elements / features at different times, and not in terms of any spatial, physical, sequential, or other relationship. In the example shown, a subset of the FTM transaction may be executed on the second channel to efficiently utilize the channel, and the subset of the FTM transaction may be the second FTM burst set.In another example, the FTM transaction may comprise only one FTM burst, and the subset of the FTM burst may contain one or more FTM exchanges. These one or more FTM exchanges may be negotiated on the second channel at the adjusted FTM response frequency. Negotiation of FTM transactions on one or more channels is performed at the adjusted FTM response frequency.

[0044] In block 465, the first network device may check, based on the one or more channel parameters, whether the first FTM burst set can be fully executed on the first channel. The first FTM burst set may include a first FTM swap set and a second FTM swap set. A conducive aspect for executing the first FTM swap set and the second FTM swap set on the first channel and the second channel, respectively, is checked. Likewise, the first network device may check whether the second FTM burst set can be fully executed on the second channel.

[0045] At block 470, the first network device may execute the first FTM burst set entirely on the first channel based on one or more channel parameters and based on the check performed at block 465. For example, the first network device may send acknowledgement-related frames to the second network device over the first channel in response to the FTM request(s). The first FTM burst set also includes one or more FTM exchanges negotiated on the first channel. Similarly, the first network device may check and respond whether the second FTM burst set should be executed entirely on the second channel.

[0046] Based on the test in block 465, the first network may determine in 475 that a first FTM exchange set of the first FTM burst set should be executed on the first channel and a second FTM exchange set of the first FTM burst set should be executed on the second channel. In one example, the first network device may detect the occurrence of a contention delay on the first channel, causing the second FTM exchange set to be executed on the second channel.

[0047] If the first network device or the second network device is not MLO-compatible, block 450 may be executed after block 430. The remaining blocks (e.g., 435, 440, 445, 455-475) are then inapplicable. In some examples, the illustrated blocks 405-475 may have a different order, and the current illustrated order corresponds to an example. Many combinations and variations of the illustrated blocks and additional actions discussed here are possible.

[0048] Fig. shows a schematic view of a network 500 depicting an FTM transaction according to an example of the present subject matter. The current example shows the first network device 505, which may be an access point capable of multi-link operation. The second network device 510 may be a client device or another access point also capable of multi-link operation. Both the first network device 505 and the second network device 510 are MLDs due to their MLO capability, allowing data to be sent and received over the available channels.

[0049] In the illustrated diagram, the second network device 510 is connected to the first network device 505 via a first channel 571 and a second channel 572. The first channel 571 may be a channel from a first frequency band, and the second channel 572 may be a channel from a second frequency band. In one example, the first frequency band may be a 2.4 GHz frequency band and the second frequency band may be a 5 GHz band. However, the selected frequency bands are exemplary, as any other available frequency band may be used. In one example, the first channel and the second channel may be from the same frequency band. If the first channel and the second channel are selected from the same frequency band, sufficient spacing can be maintained between the channels to avoid interference.For example, the first channel may be located at the high end of a 5 GHz frequency band, and the second channel may be located at the low end of the 5 GHz frequency band. Furthermore, larger channel bandwidths available in certain frequency bands can be effectively used to negotiate an initial number of FTM requests from a plurality of FTM requests from one or more client devices.

[0050] An FTM transaction 515 responsive to a first number of FTM requests from the plurality of FTM requests of the second network device 510 is illustrated. The FTM transaction 515 consists of a first FTM burst set 5151 and a second FTM burst set 5152. Based on the channel traffic, the first network device 505 may negotiate all FTM exchanges on the first channel 571. However, in the illustrated example, the first network device 505 executes a first FTM burst set 5151 on the first channel 571 and the second FTM burst set 5152 on the second channel 572. In one example, the second FTM burst set 5152 transmitted on the second channel 572 may be due to reordering or retransmission due to the identification of non-conducive channel parameters on the first channel 571.

[0051] Furthermore, the first FTM burst set 5151 may include one or more FTM exchanges that may be performed on the first channel 571. Similarly, the second FTM burst set 5152 may include one or more FTM exchanges that may be performed on the second channel 572. Further, in one example, a first FTM exchange set of the first FTM burst set 5151 may be performed on the first channel 571 and a second FTM exchange set of the FTM burst set 5151 may be performed on the second channel 572. If two or more channels are available, the first network device 505 may utilize any subset of the channels consisting of two channels based on the channel parameters of each channel of the subset of channels. In the figure, only two channels are available. The channel parameters include, among others, the channel bandwidth, the channel traffic, and the number of network devices / stations available on the channel.

[0052] When frames corresponding to the FTM transaction are sent over the second channel 572, a sender address in the frame is set to S2 and a receiver address is set to R2. Similarly, when frames are sent on the first channel 571, the sender address in the frame is set to S1 and the receiver address is set to R1. In addition to the addresses R1, R2 corresponding to the channels / radios, the network devices have a third address R3 / S3 that identifies the network device. For example, the first network device 505 may be identified by an address S3 and the second network device 510 by R3 to complete the FTM transaction. In one example, the first channel is in the 2.4 GHz band and the second channel 572 is in the 5 GHz band. Furthermore, the first network device 505 may route at least part of the FTM transaction over the second channel, which may operate in the 6 GHz band.The selection of 6 GHz bands and associated channels may be based on the availability of that particular frequency band on one of the devices, allowing for the utilization of a larger channel bandwidth. In another example, if channel parameters on the first channel 571 or the second channel 572 are not conducive, part of the FTM request may be executed on a third channel, thereby changing a subset of channels. Furthermore, the first network device 505 includes a processing unit 507 that can retrieve and execute instructions corresponding to selecting the subset of channels and adjusting the FTM response frequency from a non-transitory storage medium 508. The first network device 505 may include a network unit 506 that can be used to connect to the second network device 510.

[0053] Fig.shows a schematic view of a network 600 illustrating selection of a subset of channels according to an example of the present subject matter. The first network device 605 and the second network device 610 include two or more channels 670A-670N. The first network device 605 selects a subset of channels from the two or more channels 670A-670N. A first subset of channels 616 is formed, for example, by a first channel 670A and a second channel 670B. Similarly, a second subset of channels 617 is formed by the second channel 670B and a third channel 670C. Thus, in the current example, N such channels are available. A subset of channels (e.g., two channels) is selected by the first network device 605 based on one or more channel parameters of each channel. The first network device 605 selects the subset of channels to perform the FTM transactions.For example, a fourth subset of channels 619 may be formed by the first channel 670A and an Nth channel 670N.

[0054] In one example, a first portion of an FTM transaction may be executed on the subset of channels consisting of a first channel 670A and a second channel 670B. The selection of the subset of channels is not limited to sequential channels. For example, to execute a second portion of the FTM transaction, the first channel 670A and the third channel 670C form a third subset of channels 670B. The first network device responds with an adjusted FTM response frequency on the selected subset of channels, and the FTM response frequency may be adjusted based on channel traffic along the available channels.

[0055] In one example, an FTM transaction may be initiated on the first subset of channels 616. The first network device 605 may reorder frames related to a portion of the FTM transaction and transmit them on the first channel 670A or the second channel 670B because the channel parameters on one of the channels are not conducive to transmission. In another example, a portion of the FTM transaction may be retransmitted on the second portion of channels 617 because the channel parameters are not conducive to transmission or to negotiating FTM exchanges. The first network device 605 may select a different subset of channels based on required channel parameters and perform certain portions of the FTM transaction on that subset of channels.

[0056] In another example, the first network device 605 may execute a second FTM transaction 617 on the second subset of channels 670B, 670C from the number of channels. The first network device 605 may select any subset of channels. Furthermore, in one example, a first part of the FTM transaction may include a first FTM burst set and a second part of the FTM transaction may include a second FTM burst set. In another example, the FTM transaction may include only one FTM burst set, and the first part may include a first FTM exchange set and the second part may include a second FTM exchange set. At the adjusted FTM response frequency, the first network device negotiates the FTM transaction on one or more subsets of channels.

[0057] The present subject matter is described with reference to the foregoing examples. Although specific examples have been illustrated and described herein, the scope of the claimed subject matter is intended to cover all equivalents thereof. Other forms, details, and examples may be used without departing from the scope of the present subject matter.

Claims

[1] A process comprising: Receiving, by a first network device (105; 205; 505; 605), a plurality of fine timing measurement (FTM) requests from a second network device (110; 210; 510; 610) over a first channel (120; 571; 670A); Determining, by the first network device (105; 205; 505; 605), channel traffic along the first channel (120; 571; 670A); Accessing a lookup table comprising the channel traffic and an FTM response frequency based on the channel traffic; Selecting the FTM response frequency from the lookup table; Setting the FTM response frequency by the first network device (105; 205; 505; 605) based on the selection; and Responding, by the first network device (105; 205; 505; 605) and based on the FTM response frequency, only to a first number of FTM requests from the plurality of FTM requests and determining not to acknowledge a second number of FTM requests from the plurality of FTM requests. [2] The method of claim 1, wherein determining channel traffic along the first channel (120; 571; 670A) comprises: Enumerating, by the first network device (105; 205; 505; 605), the plurality of FTM requests made by the second network device (110; 210; 510; 610) during a selected period of time; and Comparing, by the first network device (105; 205; 505; 605), the enumerated FTM requests with a first request threshold. [3] The method of claim 2, wherein the first network device (105; 205; 505; 605) adjusts the FTM response frequency based on the enumerated FTM requests that exceed the first request threshold. [4] The method of claim 1, wherein the first network device (105; 205; 505; 605) sets the FTM response frequency to be between a minimum threshold frequency and a maximum threshold frequency, wherein both the minimum threshold frequency and the maximum threshold frequency are adjustable. [5] The method of claim 1, wherein adjusting the FTM response frequency comprises: Reducing, by the first network device (105; 205; 505; 605), the FTM response frequency when the channel traffic along the first channel (120; 571; 670A) exceeds a channel traffic threshold. [6] The method of claim 1, wherein adjusting the FTM response frequency comprises: Varying, by the first network device (105; 205; 505; 605), the FTM response frequency in inverse proportion to the determined channel traffic. [7] The method of claim 1, wherein the first network device (105; 205; 505; 605) responds over the first channel (120; 571; 670A) only to the first number of FTM requests during a selected period of time. [8] The method of claim 1, wherein the lookup table is accessed from a location external to the first network device (105; 205; 505; 605). [9] A first network device (105; 505) comprising: a processing unit (107; 507); and a non-transitory computer-readable storage medium (108; 508) storing a plurality of instructions, the plurality of instructions being executable by the processing unit (107; 507) to: receive a plurality of fine timing measurement (FTM) requests from a second network device (510) over a first channel (571); to determine channel traffic along the first channel (571); access a lookup table comprising the channel traffic and an FTM response frequency based on the channel traffic; select the FTM response frequency from the lookup table; to adjust the FTM response frequency depending on the selection; and respond only to a first number of FTM requests from the plurality of FTM requests based on the FTM response frequency, and determine not to acknowledge a second number of FTM requests from the plurality of FTM requests. [10] The first network device (505) according to claim 9, wherein the processing unit (107; 507) further serves to: adjust the FTM response frequency by reducing the FTM response frequency, wherein the first network device (505) maintains a channel bandwidth for one or more potential requests from one or more network devices, the one or more network devices comprising associated devices and high priority devices. [11] The first network device (505) of claim 9, wherein the processing unit (107; 507) further serves to: determine an availability of a number of channels for a wireless connection between the first network device (505) and the second network device (510), and wherein one or more channel parameters of each channel of the number of available channels are determined, the one or more channel parameters comprising a channel bandwidth, the channel traffic, and a number of network devices connected to the channel. [12] The first network device (505) of claim 11, wherein the processing unit (107; 507) further serves to: select a subset of channels from available channels to execute an FTM transaction according to the first number of FTM requests. [13] The first network device (505) of claim 12, wherein the processing unit (107; 507) further serves to: execute the FTM transaction along the subset of channels selected from the number of available channels based on the one or more channel parameters of each channel. [14] The first network device (505) of claim 13, wherein the processing unit (107; 507) further serves to: execute a first FTM burst set of the FTM transaction over a first channel (571) of the subset of channels and a second FTM burst set of the FTM transaction over a second channel (572) of the subset of channels based on the one or more channel parameters. [15] The first network device (505) of claim 14, wherein the processing unit (107; 507) further serves to: perform a first FTM exchange set of the first FTM burst set over the first channel (571) and a second FTM exchange set of the first FTM burst set over the second channel (572) based on the one or more channel parameters. [16] The first network device (505) of claim 12, wherein the processing unit (107; 507) further serves to: execute a first part of the FTM transaction on a first subset of channels from the available channels; and execute a second part of the FTM transaction on a second subset of channels from the available channels. [17] The first network device (505) of claim 12, wherein the first network device (505) and the second network device (510) include multi-link operability, wherein at least a portion of the FTM transaction is transmitted on a subset of channels from the number of available channels. [18] A non-transitory, computer-readable storage medium (304; 508) comprising a plurality of instructions, the plurality of instructions being executed by a processing unit (302; 507) to: receive (306) a plurality of fine timing measurement (FTM) requests from a second network device (110; 210; 510; 610) over a first channel (120; 571; 670A); to determine (308) channel traffic along the first channel (120; 571; 670A); access a lookup table comprising the channel traffic and an FTM response frequency based on the channel traffic; select the FTM response frequency from the lookup table; adjust the FTM response frequency in dependence on the selection (310); and respond (312) only to a first number of FTM requests from the plurality of FTM requests based on the FTM response frequency and determine not to acknowledge a second number of FTM requests from the plurality of FTM requests. [19] The non-transitory computer-readable storage medium (304; 508) of claim 18, wherein the plurality of instructions executable by the processing unit (302; 507) further serves to: to determine the channel traffic along the first channel (120; 571; 670A) by comparing with a channel traffic threshold. [20] The non-transitory computer-readable storage medium (304; 508) of claim 18, wherein the plurality of instructions executable by the processing unit (302; 507) further serves to: enumerate the plurality of FTM requests made by the second network device (110; 210; 510; 610) during a selected period of time; and to compare the listed FTM requirements with an initial requirement threshold. [21] The non-transitory computer-readable storage medium (304; 508) of claim 19, wherein adjusting the FTM response frequency is performed when the enumerated FTM requests exceed a first request threshold, even if the channel traffic along the first channel (120; 571; 670A) is less than the channel traffic threshold.

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