Wireless local area network (LAN) carrier frequency correction for uplink transmission

Abstract

To provide wireless local area network (LAN) carrier frequency correction for uplink transmission.SOLUTION: A method includes receiving a plurality of frames from an access point. The method further includes determining a carrier frequency offset (CFO) estimate for each of the frames received from the access point. The method further includes computing a final CFO estimate based on the CFO estimates. The method further includes changing, based on the final CFO estimate, a first phase of a radio frequency phase-locked loop (RF PLL) to a second phase.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to wireless devices, and more particularly, to wireless local area network (LAN) carrier frequency correction for uplink transmissions. [Background technology]

[0002] Wireless local area network (LAN) technologies have evolved to a point where wireless devices can communicate with extremely high throughput, high efficiency, and support both multi-user (MU) orthogonal frequency division multiple access (OFDMA) and multi-user multiple input multiple output (MU-MIMO) in both downlink and uplink directions. The support of MU OFDMA and MU-MIMO in the uplink direction also imposes stringent requirements on the transmitting devices (compared to legacy methods), since the access point (AP) or base station (BS) in uplink transmission under these Wi-Fi 6 technologies requires stringent levels of timing synchronization, power control for target received power, and high signal quality from multiple transmitting devices. These stringent Wi-Fi 6 requirements include those related to in-band distortion, e.g., error vector magnitude (EVM), as well as out-of-band distortion, e.g., unused tone error (UTE) and carrier frequency offset (CFO) relative to the AP / BS. This places stringent requirements on transmitter CFO and carrier leakage in the AP / BS from trigger-based physical layer protocol data unit (TB-PPDU) frames received from a transmitting device. Although the standards related to Wi-Fi6 state that transmitting devices must pre-compensate for in-band and out-of-band distortion to meet these stringent standard levels for EVM, UTE and CFO, the standards do not actually teach how this should be done by such transmitting devices. [Brief description of the drawings]

[0003] [Figure 1]1 is a block diagram of an exemplary wireless communication system according to some embodiments. [Diagram 2] FIG. 2 is a simplified timing diagram illustrating a wireless device (station) using WLAN carrier frequency correction for uplink transmissions in accordance with some embodiments. [Diagram 3] 1 is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments. [Figure 4] FIG. 2 is a timing diagram illustrating a radio frequency (RF) phase-locked loop (PLL) retuning trigger for wireless LAN carrier frequency correction for uplink transmissions according to some embodiments. [Diagram 5] FIG. 5A is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments, and FIG. 5B is a flow diagram of a method for performing RF PLL retuning for WLAN carrier frequency correction for uplink transmissions according to some embodiments. [Figure 6] FIG. 2 is a block diagram of a wireless device for performing frequency estimation and triggering LO trim (RF PLL retuning) for WLAN carrier frequency correction for uplink transmissions according to some embodiments. [Figure 7] FIG. 1 is a block diagram of a wireless device that employs hardware to perform frequency estimation and trigger LO trim (RF PLL retuning) for WLAN carrier frequency correction for uplink transmissions, according to some embodiments. [Figure 8] FIG. 1 is a block diagram of a wireless device that employs hardware to perform both LO trim pre-correction RF PLL retuning and analog front-end (AFE) PLL trimming for WLAN carrier frequency correction for uplink transmissions in accordance with some embodiments. [Figure 9]FIG. 9 is a block diagram of a wireless device 900 that performs LO trim (RF PLL retuning) for coarse carrier frequency correction and digital pre-correction for fine carrier frequency for WLAN carrier frequency correction for uplink transmission in accordance with various embodiments. [Figure 10] FIG. 10 is a flow diagram of a method 1000 for performing LO trim (RF PLL retuning) pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction for WLAN carrier frequency correction for uplink transmission in accordance with various embodiments. [Figure 11] 1 is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments. [Figure 12] FIG. 2 is a simplified timing diagram illustrating LO trim triggers for WLAN carrier frequency correction for uplink transmissions in accordance with some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] The following description sets forth many specific details, such as examples of specific systems, devices, components, methods, etc., to provide a good understanding of various embodiments of wireless local area network (LAN) carrier frequency correction for uplink transmission. Wireless LAN devices have evolved with generations. For example, the first two generations of the Wi-Fi standard were based on single-carrier spread spectrum techniques, but subsequent generations adopted the more efficient orthogonal frequency division multiplexing (OFDM) as the basic modulation technique. Furthermore, later generations added support for multiple antenna techniques, such as multiple-input multiple-output (MIMO), to improve reliability and throughput using spatial dimensions such as redundancy and multiplexing. However, the access mechanism has used carrier sense multiple access with collision avoidance (CSMA / CA) and random backoff as an access mechanism to share the medium or channel among users. This meant that only a single user (SU) could use the medium or channel at any time instance.

[0005] The more recent Institute of Electrical and Electronics Engineers (IEEE) 802.11ac standard, also called Very High Throughput (VHT) or Wi-Fi® 5, added support for multi-user (MU) capability in the downlink direction using MU-MIMO techniques. This allows multiple users to share the medium at one time instance, for example, by being multiplexed together. More recently, the IEEE 802.11ax standard, also called High Efficiency (HE) or Wi-Fi® 6, added multi-user (MU) support in both the uplink and downlink directions using Orthogonal Frequency Division Multiple Access (OFDMA) and MU-MIMO techniques. For these more recent standards, on the downlink side, access point (AP) or base station (BS) frame synchronization is the default point-to-multipoint transmission, since, for example, the AP / BS is simply sending content to individual wireless devices as the content is received, typically by multiplexing the various content to the correct wireless devices. In contrast, on the uplink side, the AP / BS is configured to receive transmissions from multiple wireless devices (multipoint-to-point) so that the AP / BS correctly receives the content when it simultaneously receives multiple streams from multiple devices that are then transmitted, which requires synchronization between the multiple wireless devices.

[0006] As mentioned, stringent Wi-Fi 6 requirements for uplink transmissions include those related to in-band distortion, e.g., Error Vector Magnitude (EVM), and out-of-band distortion, e.g., Unused Tone Error (UTE) and Carrier Frequency Offset (CFO) to the AP / BS. This places stringent requirements on timing and carrier leakage in the access point from trigger-based physical layer protocol data unit (TB-PPDU) frames received from the transmitting device. Although standards related to Wi-Fi 6 state that transmitting devices must pre-correct in-band and out-of-band distortion to meet these stringent standard levels for EVM, UTE and CFO, the Wi-Fi 6 standards do not actually teach how this should be done by the transmitting device. As described in more detail below, current digital pre-correction techniques improve (e.g., reduce) carrier leakage, but they do not improve carrier leakage to the levels currently required under the most recent Wi-Fi standards.

[0007] To address these and other shortcomings of known approaches to carrier leakage reduction, the present disclosure describes configuring and / or operating a wireless device to instead (or in addition to performing digital pre-correction) perform carrier frequency correction for uplink transmissions. By determining a carrier frequency offset (CFO) estimate for frames received by the wireless device, the CFO estimate can be used to calculate a statistical measure (e.g., average, weighted average, moving average, mean, etc.) and the RF PLL of the device can be retuned according to the calculated statistical measure, which allows its carrier frequency to undergo larger frequency adjustments and better meet stringent standard levels for EVM, UTE and CFO.

[0008] Thus, in at least some embodiments, a method includes receiving frames from an access point. The method further includes determining a CFO estimate for each of the frames received from the access point. The method further includes calculating a final CFO estimate based on the CFO estimate. The method further includes changing a first phase of an RF PLL to a second phase based on the final CFO estimate.

[0009] In some embodiments, an apparatus is disclosed that employs an RF PLL to receive frames from an access point while the RF PLL operates in a first phase. A processing device (e.g., a state machine, firmware, etc.) is coupled to the RF PLL and determines a CFO estimate for each frame received from the access point. The processing device calculates a final CFO estimate (e.g., an average, weighted average, moving average, or mean of the received CFO estimates) and changes the RF PLL from the first phase to a second phase based on the final CFO estimate.

[0010] In some embodiments, a system is disclosed that employs a first circuit to receive frames from an access point. The first circuit includes an RF PLL. The system further employs a second circuit (e.g., a state machine, firmware, etc.) to determine a CFO estimate for each frame received from the access point. The second circuit calculates a final CFO estimate (e.g., an average, weighted average, moving average, or mean of the received CFO estimates) and changes the RF PLL from a first phase to a second phase based on the final CFO estimate. Additional embodiments and implementation variations are described in detail with reference to FIGS. 2-14.

[0011] The present disclosure includes several advantages, including the ability to address carrier frequency offset (CFO) by changing the frequency at which the radio circuitry (e.g., RF PLL) operates (e.g., RF PLL retuning) based on a final CFO estimate determined by calculating a statistical measure (e.g., average, weighted average, moving average, or mean) of received CFO estimates. In this way, stringent carrier leakage issues can be minimized. This approach also relaxes the requirements for residual carrier leakage to meet UTE requirements. This approach also avoids correcting CFO in a time-critical manner and does not require stringent timing. WLAN carrier frequency correction for uplink transmissions using RF PLL retuning allows a wider range of potential frequency changes to at least meet stringent standard levels for EVM, UTE, and CFO. This approach can relax the transmit carrier leakage specification by more than 20 dB. In other words, under similar transmit carrier leakage, the proposed approach provides an additional margin of more than 20 dB for UTE compared to conventional solutions. Further advantages will be apparent to those skilled in the art of modern wireless technology and recent IEEE standards.

[0012] Although the present disclosure describes some embodiments for WLAN carrier frequency correction for multi-user uplink transmissions, in some embodiments, the WLAN carrier frequency correction for uplink transmissions can be for single-user (SU) uplink transmissions. Such use in SU transmissions helps the corresponding receiver improve sensitivity because the residual frequency offset that the receiver needs to estimate and compensate at the receiver side is smaller. Furthermore, although the present disclosure describes WLAN carrier frequency correction for uplink transmissions, in some embodiments, the carrier frequency correction for uplink transmissions can be performed for any type of personal area network (e.g., Bluetooth, Zigbee, short range wireless communication, etc.).

[0013] 1 is a block diagram of an exemplary wireless communication system 100, according to some embodiments. In these embodiments, the wireless communication system 100 includes base stations and / or access points 112-116 (which may be referred to interchangeably herein), wireless devices 118-132 (e.g., wireless stations (STAs) and other such wireless communication devices), and network hardware components 134. The wireless devices 118-132 may include laptop computers 118 or tablets 126, personal digital assistants 120 and 130, personal computers 124 and 132, and / or mobile phones 122 and 128. Details of one embodiment of such wireless devices when functioning as transmitting devices are described in more detail below.

[0014] In an embodiment, base stations (BS) or access points (AP) 112-116 are operatively coupled to a network hardware component 134 via local area network connections 136, 138 and 140. The network hardware component 134, which may be a router, switch, bridge, modem, system controller, etc., provides a wide area network connection 142 to the communication system 100. Each of the base stations or access points 112-116 has an associated antenna or antenna array for communicating with wireless communication devices within an area reachable by each respective base station or access point. Typically, wireless devices register with a particular base station or access point 112-116 to receive services from the communication system 100. In the case of a direct connection (i.e., point-to-point communication), the wireless communication devices communicate directly over an allocated channel.

[0015] Any of the various wireless devices 118-132 and BSs or APs 112-116 may include a processor and communications interface to support communication with any other of the wireless devices 118-132 and BSs or APs 112-116. In one example of operation, a processor and communications interface implemented within one of the devices (e.g., any one of the wireless devices 118-132 and BSs or APs 112-116) is configured to process at least one signal received from another one of the devices (e.g., any other one of the wireless devices 118-132 and BSs or APs 112-116) and / or generate at least one signal to be transmitted to another one of the devices.

[0016] It should be noted that general references to communication devices, such as the wireless devices (e.g., wireless devices) 118-132 and BSs or APs 112-116 of FIG. 1, or any other communication and / or wireless communication devices, may alternatively be made herein generally using the term "device" for brevity. The processors and communication interfaces of any one of the various devices, wireless devices 118-132 and BSs or APs 112-116, may be configured to support communication with any other of the various devices, wireless devices 118-132 and BSs or APs 112-116. Such communication may be unidirectional or bidirectional between the devices. Also, such communication may be unidirectional between the devices at some times and bidirectional between those devices at other times, although embodiments herein generally focus on wireless devices transmitting to BSs or APs 112-116 operating in a multi-user transmission mode, such as MU OFDMA or MU-MIMO.

[0017] In one example of operation, AP / BS device 116 (representing either BS or AP 112-116) includes a communications interface and a processor configured to receive one or more signals (e.g., OFDMA symbols 181) from devices 130 and 132. Considering the OFDMA example, device 130 uses a first at least one subcarrier and device 132 uses a second at least one subcarrier. In general, different subsets of subcarriers are assigned for use by different devices. Such assignments may be dynamic, adaptive, etc., for different devices, for different symbols, and / or at different times.

[0018] In these embodiments, the AP / BS device 116 receives a first OFDMA symbol including a first data from the device 130 modulated onto a first set of at least one subcarrier and a second data from the device 132 modulated onto a second set of at least one subcarrier. The AP / BS device 116 processes the first data to decode (or demodulate) the data from the first device 130. The AP / BS device 116 also processes the second data to decode (or demodulate) the data from the second device 132. In other examples / embodiments, the AP / BS device 116 receives a first MU-MIMO symbol including the first data from the device 130 modulated onto the first set of at least one subcarrier and the second data from the device 132 modulated onto the first set of at least one subcarrier. The AP / BS device 116 spatially processes the first data to decode (or demodulate) the data from the first device 130. The AP / BS device 116 also spatially processes the second data to decode (or demodulate) the data from the second device 132. In both examples, the first device 130 and the second device 132 transmit data with a pre-corrected CFO that the first device 130 and the second device 132 estimate based on a trigger frame preceding the data frame. Such a capability in the first device 130 and the second device 132 may generally be referred to as a CFO pre-correction capability. With respect to this embodiment and other embodiments or examples provided herein, there may be instances where the pre-corrected CFO provides a zero offset between the AP / BS device 116 and another device similar to the devices 130 and 132 (e.g., device 126 or 128).

[0019] In general, the AP / BS device 116 operates by processing data from other devices contained within the same set of at least one subcarrier. Several different combinations of such data and copies and / or repetitions of that data may be used in various embodiments. When the other device pre-corrects for a CFO, the other device, similar to devices 130 and 132 described above, modifies or adapts its communications with the device to compensate for the CFO that may exist between the AP / BS device 116 and the other device to ensure effective communication, synchronization, and improved performance of communications between the devices.

[0020] FIG. 2 is a simplified timing diagram 200 illustrating a wireless device (station) using WLAN carrier frequency correction for uplink transmissions, according to some embodiments.

[0021] In some embodiments, the station device 204 transmits an authentication request frame 206 to the AP / BS device 202. In some embodiments, the authentication request frame (e.g., the authentication request frame 206) is a type of management frame used in Wi-Fi networks. The authentication request frame may be transmitted by a station device (e.g., the station device 204) to initiate the process of authentication with an access point.

[0022] The AP / BS 202 transmits an authentication response frame 208 to the station device 204 following a short interframe space (SIFS) 220. In some embodiments, the authentication response frame (e.g., authentication response frame 208) may be a type of management frame used in Wi-Fi networks. The authentication response frame may be transmitted by an access point (e.g., AP / BS 202) in response to an authentication request frame transmitted by a station (e.g., station device 204). The authentication response frame is transmitted in response to the authentication request frame and may include information regarding the authentication method used by the network (e.g., Wi-Fi Protected Access Pre-Shared Key (WPA2-PSK), WPA2 Enterprise, etc.).

[0023] In some embodiments, a SIFS (e.g., SIFS 220) is 16 microseconds (μs) + / - 400 ns after the end of the previous frame, as specified by the IEEE 802.11ax standard. This SIFS time period may change in the future, so the exact amount of time is not important, but it is beneficial to ensure that it is a very short interval of time that is not expected to change.

[0024] The station device 204 then transmits an association request frame 212 to the AP / BS device 202. In some embodiments, the association request frame may be a type of management frame used in Wi-Fi networks. The association request frame (e.g., the association request frame 212) may be transmitted by a station (e.g., the station device 204) to request association with an access point (e.g., the AP 202) and begin the process of connecting to the network.

[0025] The AP / BS 202 transmits an association response frame 214 to the station device 204 following a short interframe space (SIFS) 220. In some embodiments, the association response frame (e.g., association response frame 214) may be a type of management frame used in Wi-Fi networks. The association response frame may be transmitted by an access point (e.g., AP / BS 202) in response to an association request frame (e.g., association request frame 212) transmitted by a station (e.g., station device 204) and includes information regarding whether the association was successful, as well as additional information about the network.

[0026] In some embodiments, frames transmitted and received between the station device 204 and the AP / BS 202 may be management frames (e.g., beacon frames, probe request frames, probe response frames, association request frames, association response frames, authentication frames, deauthentication frames, etc.). In some embodiments, frames transmitted and received between the station device 204 and the AP / BS 202 may be control frames (e.g., request to send (RTS) frames, clear to send (CTS) frames, acknowledgement (ACK) frames, etc.). In some embodiments, frames transmitted and received between the station device 204 and the AP / BS 202 may be data frames (e.g., data frames, null function frames, etc.). In some embodiments, each frame transmitted by an AP / BS (e.g., AP / BS 202) has a CFO, and a station (e.g., station device 204) receiving such frames determines a CFO estimate for each frame received from the AP / BS.

[0027] In some embodiments, the station device 204 and the AP / BS 202 continue to transmit and receive frames (e.g., up to N frames). Each frame transmitted by an AP / BS (e.g., AP / BS 202) has a CFO, and a station (e.g., station device 204) receiving such frames determines a CFO estimate (e.g., CFO estimates 230A-N) for each frame received from the AP / BS. In some embodiments, the magnitude of the CFO estimate may be small. In some embodiments, the magnitude of the CFO estimate may be large.

[0028] In some embodiments, RF PLL tuning 222 (e.g., retuning) may be triggered. In some embodiments, a function (e.g., g(.)) receives an input (e.g., CFO estimates 230A-N) and outputs a final CFO estimate based on the input (e.g., the CFO estimate used as an input). In some embodiments, calculating the final CFO estimate may include calculating a statistical metric (e.g., average, weighted average, moving average, mean, etc.) of the CFO estimate. In some embodiments, function g(.) receives the CFO estimate as an input and outputs a final CFO estimate. In some embodiments, function g(.) may employ any number of statistical or mathematical techniques to generate an output (e.g., the final CFO estimate).

[0029] In some embodiments, the phase of the RF PLL is changed based on the final CFO estimate. In some embodiments, the final CFO estimate is a frequency and the phase of the RF PLL can be changed by trimming the LO that is part of the RF PLL. For example, for a final CFO estimate of 1 MHz, the LO is adjusted by 1 MHz in the LO trim to retune the RF PLL.

[0030] In some embodiments, the RF PLL retuning operation includes changing the RF PLL from a first phase to a second phase based on the final CFO estimate. In some embodiments, the RF PLL retuning operation does not require strict timing because a medium may be reserved to perform the RF PLL retuning operation and the RF PLL retuning operation does not need to be completed within a short period of time (e.g., a few microseconds). In some embodiments, once the RF PLL retuning settles, communication (e.g., between the station device 204 and the AP / BS 202) may resume.

[0031] In some embodiments, the station device 204 determines whether the final CFO estimates meet a criterion before changing the RF PLL from a first phase to a second phase (i.e., tuning / retuning the RF PLL). In some embodiments, the criterion may be a determination that the number of CFO estimates is equal to a threshold number of CFO estimates. For example, in some embodiments, the RF PLL retuning operation may not be triggered until the number of CFO estimates is greater than a threshold. In some embodiments, the threshold number of CFO estimates is based on the magnitude of the CFO estimates. For example, in some embodiments, the RF PLL retuning operation may not be triggered until the magnitude of the CFO estimate is greater than 1 MHz. In some embodiments, the station device 204 may determine a magnitude of at least one of the CFO estimates and, in response to the magnitude of at least one of the CFO estimates meeting the threshold magnitude, change the threshold number of CFO estimates from a first number to a second number. For example, in some embodiments, if the magnitudes of the first three CFO estimates are greater than a threshold magnitude (e.g., a particular number of Hz), the threshold number of CFO estimates required to calculate a final CFO estimate may be changed from a first number to a second number (e.g., from 16 to 2). In some embodiments, because the magnitudes of the CFO estimates are relatively large, the final CFO estimate may need to be calculated sooner to facilitate correction of the relatively large CFO that may cause transmission impairments (e.g., carrier leakage, etc.).

[0032] In some embodiments, the final CFO estimate may not meet the criteria, and the station device 204 does not change the first phase of the RF PLL to the second phase (i.e., performs an RF PLL retuning operation based on the final CFO estimate). In some embodiments, the station device 204 may receive additional frames from the AP / BS 202 and determine a CFO estimate for the additional frames received from the AP / BS 202. The station device 204 may then calculate an updated final CFO estimate based on the CFO estimate. In some embodiments, calculating an updated final CFO estimate based on the CFO estimate may include recalculating the final CFO estimate using the CFO estimate and the CFO estimate. In some embodiments, calculating an updated final CFO estimate based on the CFO estimate may include recalculating the final CFO estimate using a subset of the CFO estimate and the CFO estimate. In some embodiments, calculating an updated final CFO estimate based on the CFO estimate may include recalculating the final CFO estimate using only the CFO estimate.

[0033] In some embodiments, the station device 204 may determine whether the updated final CFO estimate meets the criterion and change the first phase of the RF PLL to the second phase based on the final CFO estimate meeting the criterion. In some embodiments, the station device 204 may continue to receive additional frames from the access point based on the final CFO estimate not meeting the criterion.

[0034] In some embodiments, the AP / BS 202 may transmit a trigger frame to the station device 204. The station device 204 transmits a TB-PPDU frame 218 to the AP / BS 202 following the SIFS 220.

[0035] FIG. 3 is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments.

[0036] The method 300 may be performed by processing logic including hardware (e.g., circuits, dedicated logic, programmable logic, microcode, etc.), software (e.g., instructions executed on a processing device), or a combination thereof. The method 300 may be performed, in whole or in part, by the wireless devices 118-132 or the station device 204, or any of their components. Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be changed. Thus, the illustrated embodiment should be understood as merely an example, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Furthermore, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in every embodiment. Other process flows are possible.

[0037] The method 300 begins at block 302 where processing logic performing the method receives a plurality of frames from an access point. In some embodiments, the plurality of frames may be at least one of management frames, control frames, or data frames.

[0038] At block 304, processing logic determines a CFO estimate for each of a plurality of frames received from the access point. In some embodiments, the CFO estimate is the difference between the carrier frequency at the transmitter and the carrier frequency at the receiver.

[0039] In some embodiments, processing logic further determines whether the final CFO estimate meets a criterion, in some embodiments, the criterion may be that the final CFO estimate must meet or exceed a threshold magnitude (e.g., the final CFO estimate must be greater than 5 MHz).

[0040] In some embodiments, changing the first phase of the RF PLL to the second phase may be based on the final CFO estimate satisfying a criterion.

[0041] In some embodiments, satisfying the criterion may include determining that the number of CFO estimates is equal to a threshold number of CFO estimates. In some embodiments, the criterion may be a threshold number of CFO estimates that corresponds to a number of frames received. For example, a final CFO estimate does not satisfy the criterion if it is calculated using less than two CFO estimates.

[0042] In some embodiments, the processing logic further determines a magnitude of at least one of the CFO estimates. In some embodiments, the processing logic changes the threshold number of CFO estimates from a first number to a second number in response to the magnitude of at least one of the CFO estimates meeting a threshold magnitude. In some embodiments, the threshold number of CFO estimates is based on the magnitude of the CFO estimates. For example, a final CFO estimate may not be calculated under normal conditions until eight CFO estimates are received. However, if the magnitude of one or more of the several received estimates meets a threshold magnitude value (e.g., two of three received estimates are greater than the threshold magnitude value), the final CFO estimate is calculated using only the three CFO estimates.

[0043] At block 306, processing logic calculates a final CFO estimate based on the multiple CFO estimates.

[0044] In some embodiments, calculating the final CFO estimate based on the CFO estimates includes calculating at least one of an average, a weighted average, a moving average, or a mean. In some embodiments, a function, such as (g(.)), is used to calculate the final CFO estimate. In some embodiments, the function (g(.)) may process the previous N CFO estimates to calculate the final CFO estimate used for LO trim. In some embodiments, the output of (g(.)) may be an average of the last N estimates to help improve the accuracy of the CFO estimate.

[0045] In some embodiments, such an average may be represented by Δ=(Δf(0)+Δf(1)+...Δf(N)) / N. In some embodiments, the output of (g(.)) may be a weighted average of the last N CFO estimates. In some embodiments, such a weighted average may be represented by Δ=(w0*Δf(0)+w1*Δf(1)+...+wN*Δf(N)) / N. Using such a weighted average calculation, the weights w0, w1,..., wN may be selected based on a fixed value that places more weight on a current estimate than on past estimates (e.g., wk=e(-at(k)) / Σe(-at(k))). In some embodiments, the weights w0, w1,..., wN may be selected based on an estimated signal-to-noise ratio (SNR) of the frame corresponding to the frequency estimate (e.g., wk=e(-SNRk) / Σe(-SNRk)).

[0046] In some embodiments, the averaging window size (N CFO estimates) is determined by the moving average estimate of the frequency offset (e.g., (MA(Δf(i))>THRESH)→N=N small , otherwise N large ) In some embodiments, the averaging window size may also be selected at a more granular level, N, based on an array of thresholds.

[0047] At block 308, the processing logic changes the first phase of the RF PLL to a second phase based on the final CFO estimate. In some embodiments, changing the first phase of the RF PLL to the second phase is known as an RF PLL retuning operation. In some embodiments, the RF PLL retuning operation is performed by trimming (i.e., adjusting) a local oscillator (LO) frequency. In some embodiments, trimming the LO frequency is known as an LO trim. For example, the LO trim may be performed by adjusting a voltage controlled oscillator (VCO) tuning voltage or changing a bias current of the VCO.

[0048] In some embodiments, the processing logic further receives additional frames from the access point.

[0049] In some embodiments, processing logic determines a CFO estimate for the additional frames received from the access point.

[0050] In some embodiments, processing logic calculates an updated final CFO estimate based on the CFO estimate, for example, processing logic may recalculate an average CFO estimate that now includes the newly received CFO estimate.

[0051] In some embodiments, processing logic determines whether the updated final CFO estimate meets a criterion.

[0052] In some embodiments, the processing logic changes the first phase of the RF PLL to the second phase based on the final CFO estimate meeting the criterion or continues to receive additional frames from the access point based on the final CFO estimate not meeting the criterion.

[0053] FIG. 4 is a timing diagram illustrating a radio frequency (RF) phase-locked loop (PLL) retuning trigger for WLAN carrier frequency correction for uplink transmission, according to some embodiments.

[0054] In some embodiments, the AP device 402 transmits on a medium (e.g., a channel). The station device 404 determines that the N available CFO estimates 470 meet a criterion (e.g., N is greater than a threshold number 480). In response to determining that the criterion is met, the station device 404 waits for the channel on which the AP 402 is transmitting to become available. The AP device 402 ends transmission, and the station device 404 decrements a random backoff counter every slot 432 during a contention window 434 following an interframe space (IFS) 430. Upon gaining channel access (random backoff decrement to zero), the station device 404 transmits a CTS frame 463 to itself, blocks the medium (e.g., channel) to perform LO trim, and triggers the LO trim.

[0055] FIG. 5A is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments.

[0056] Method 500A may be performed by processing logic, which may include hardware (e.g., a processing device, circuitry, dedicated logic, programmable logic, microcode, device hardware, integrated circuits, etc.), a microcontroller (e.g., digital logic, programmed logic, firmware), or a combination thereof. In some embodiments, method 500A is performed by control logic and / or hardware of one of wireless devices 600, 700 and / or 800, 900 (FIGS. 6-9). Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be changed. Thus, the illustrated embodiment should be understood as merely an example, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in every embodiment. Other process flows are possible.

[0057] At operation 502, processing logic initializes the number of CFO offset values ​​to 0 and / or initiates a refresh state, which causes the number of CFO offset values ​​to be reset to 0 and all values ​​for CFO estimates 0 through N to be equal to 0.

[0058] At operation 504, processing logic determines whether a frame has been received from the AP device. If yes, flow proceeds to operation 506. If no, flow returns to operation 504.

[0059] At operation 506, processing logic stores the CFO estimates from the frames received from the AP. In some embodiments, processing logic stores the CFO estimates from the frames received from the AP in an array corresponding to index "n" and increments index "n".

[0060] At operation 508, processing logic processes the stored CFO estimate using function g(.) In some embodiments, processing logic checks whether an RF PLL retuning operation can be triggered based on the final CFO estimate based on some criteria.

[0061] At operation 510, processing logic determines whether to apply RF PLL tuning. If yes, flow continues to operation 512. If no, flow returns to operation 504.

[0062] At operation 512, processing logic triggers an RF PLL retuning operation based on the final CFO estimate. Flow returns to operation 502 where the processing device refreshes its state (i.e., sets N CFO estimate values ​​to 0 and sets all CFO estimate values ​​to 0).

[0063] 5B is a flow diagram of a method for determining whether to trigger RF PLL retuning for WLAN carrier frequency correction for uplink transmissions according to some embodiments. In some embodiments, FIG. 5B is a detailed flow of operation 510 of FIG. 5A.

[0064] Method 500B may be performed by processing logic, which may include hardware (e.g., a processing device, circuitry, dedicated logic, programmable logic, microcode, device hardware, integrated circuits, etc.), a microcontroller (e.g., digital logic, programmed logic, firmware), or a combination thereof. In some embodiments, method 500B is performed by control logic and / or hardware of one of wireless devices 600, 700 and / or 800, 900 (FIGS. 6-9). Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be changed. Thus, the illustrated embodiment should be understood as merely an example, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in every embodiment. Other process flows are possible.

[0065] At operation 522, processing logic determines whether a criterion is met (eg, the magnitude of the final CFO estimate greater than a threshold).

[0066] At operation 524, processing logic determines whether the medium (e.g., channel) is busy. If yes, flow ends (i.e., flow moves from operation 510 in FIG. 5A to operation 504). If no, flow continues to operation 526.

[0067] The processing logic contends for the medium (e.g., the channel) at operation 526. In some embodiments, the processing logic decrements a random backoff counter every slot time while contending for the medium.

[0068] At operation 528, processing logic causes a CTS-2-self frame to be transmitted (eg, by the station device).

[0069] At operation 530, processing logic sets LO TRIM to YES, which means that performing an LO TRIM will result in an RF PLL retuning operation being performed (i.e., flow moves from operation 510 to operation 512 in FIG. 5A).

[0070] FIG. 6 is a block diagram of a wireless device for performing frequency estimation and triggering LO trim (RF PLL retuning) for WLAN carrier frequency correction for uplink transmission, according to some embodiments.

[0071] In some embodiments, the wireless device 600 is any of the wireless devices 118-132. In some embodiments, the wireless device 600 includes a programmable processor 602, a memory 606 (e.g., non-volatile and / or volatile memory), an antenna 608, hardware 614 including Rx processing hardware 614A and Tx processing hardware 614B, a radio 620 including RF circuitry, and an external oscillator 650 (e.g., an external crystal, or XTAL). In various embodiments, the radio 620 includes a demodulator 624A, a modulator 624B, an LO 630 (also referred to herein as a Tx LO), and a front-end module (hereinafter FEM 640) having one or more front-end modules operably coupled to the antenna 608. In various embodiments, the radio 620 includes an analog-to-digital converter (ADC) 626 coupled to a demodulator 624A driven by the LO 630, and a digital-to-analog converter (DAC) 622 coupled to a modulator 624B driven by the LO 630.

[0072] In some embodiments, the programmable processor 602 executes instructions (e.g., computer code and / or firmware) to drive and provide parameters for the functionality of the hardware 614. In an embodiment, the hardware 614 is coupled to the radio 620. In some embodiments, the LO 630 is implemented, for example, in an RF PLL of the RF circuitry. In some embodiments, the LO 630 is integrated with the RF circuitry of the radio 620 and is either a resistive-capacitive (or RC) oscillator or a real-time clock (RTC) oscillator. In some embodiments, the LO trim triggers the selection or deselection of a capacitor in a capacitor bank and / or a resistor in a resistor bank to tune the Tx LO carrier frequency.

[0073] In some embodiments, one or more input signals (e.g., including management frames, control frames, data frames, etc.) are captured by antenna 608 and FEM 640 and passed to demodulator 624A (e.g., demodulator) to demodulate the received signal. In some embodiments, this demodulation extracts the original information-bearing signal, including management frames, control frames, data frames, etc. The Rx processing hardware 614A may then process the demodulated signal to obtain an estimate of the CFO (e.g., CFO estimate) from the management frames, control frames, data frames, etc., among other information. In some embodiments, the Rx processing hardware 614A provides the CFO information to the programmable processor 602. In some embodiments, the programmable processor 602 is programmed to process the estimated CFO (e.g., CFO estimate) to calculate a final CFO estimate and generate an LO trim value to shift the LO 630 (or an RF PLL including LO 630) in carrier frequency that compensates for the final estimated CFO (e.g., final CFO estimate).

[0074] Thus, in some embodiments, the transmitting side of the wireless device 600 generates a transmission at the trimmed LO carrier frequency. For example, the Tx processing hardware 614B processes the information of the next transmission signal, which the modulator 624B then modulates and passes to the FEM 640. The modulator 624B uses the trimmed LO 630, and thus the TB-PDDU frame transmitted from the FEM 640 and the antenna 608 is based on the shifted carrier frequency of the trimmed LO 630 (e.g., the trimmed Tx LO). In this way, carrier leakage (which causes in-band and out-of-band distortion) is better addressed by correcting the Tx LO (LO 630) of the wireless device 600 using the final CFO estimate to compensate for the CFO between the Rx LO and Tx LO (of the AP / BS device 116).

[0075] Additionally, in some embodiments, the radio 620 includes a radio frequency (RF) phase-locked loop (PLL) that includes the first LO. In these embodiments, the control logic (e.g., the programmable processor 602 in this embodiment) is configured to calculate an updated RF PLL frequency based on the CFO (e.g., the final CFO estimate), trigger the RF PLL to operate at the updated RF PLL frequency in response to the LO trim, and cause the RF PLL to operate at a default RF PLL frequency after transmission of the protocol data unit frame.

[0076] FIG. 7 is a block diagram of a wireless device employing hardware to perform frequency estimation and trigger LO trim (RF PLL retuning) for WLAN carrier frequency correction for uplink transmissions, according to some embodiments.

[0077] In some embodiments, the wireless device 600 of FIG. 6 is modified such that, instead of the programmable processor 602 performing the LO trim, LO trim calculation hardware 710 (which may be a separate hardware component, a programmed hardware component, or a combination thereof) is included within the hardware 614 provided on the wireless device 700. In this embodiment, the LO trim calculation hardware 710 calculates the LO trim value based on the final CFO estimate value received from the Rx processing hardware 614A. Thus, in this embodiment, the LO trim calculation hardware 710 provides the LO trim value to the LO 630 (or an RF PLL that includes the LO 630) to provide a shift in the Rx LO carrier frequency to compensate for the estimated CFO (e.g., as represented in the final CFO estimate value).

[0078] FIG. 8 is a block diagram of a wireless device employing hardware to perform both LO trim (RF PLL retuning) pre-correction and analog front-end (AFE) PLL trimming for WLAN carrier frequency correction for uplink transmission in accordance with some embodiments.

[0079] In an embodiment, the wireless device 800 of FIG. 8 extends on the wireless device 700 of FIG. 7 in an implementation in which the device includes different PLLs for separately generating both a clock for the AFE and a clock for the RF. For example, in the embodiment of FIG. 8, the radio 820 of the wireless device 800 includes a radio frequency (RF) phase-locked loop (PLL) or RF PLL 830 (which may include, for example, an LO such as the LO 630 from FIG. 6-7), an analog-to-digital converter (ADC) 826 coupled to a demodulator 624A driven by the RF PLL 830, a digital-to-analog converter (DAC) 822 coupled to a modulator 624B driven by the RF PLL 830, and an analog front-end PLL 835 (or RF PLL) configured to generate clocks for driving the ADC 826 and the DAC 822. In some embodiments, the receive (Rx) processing hardware 614A is coupled to the ADC 826 and the trim logic 810. In an embodiment, the transmit (Tx) processing hardware 614B is coupled to the DAC 822.

[0080] In some embodiments, the hardware 814 of the wireless device 800 includes LO trim logic 810 coupled to an RF PLL 830 and an analog front-end PLL 835, and the clock mechanism in the radio 820 has a PLL for the AFE clock that is separate from the RF PLL 830, which clocks the demodulator 624A and the modulator 624B. Thus, in these embodiments, the LO trim logic 810 is configured to separately trim both the analog front-end PLL 835 and the RF PLL 830 to provide capability for both carrier clock frequency tuning capability and sampling clock frequency tuning capability of the RF circuitry in the radio 820.

[0081] Thus, in some embodiments, the LO trim logic 810 is configured to determine a CFO estimate between the first carrier frequency of the RF PLL and the second carrier frequency of the LO of the access point (e.g., AP / BS device 116) operating in a transmit mode from each received frame of the at least one received frame. In some embodiments, the CFO estimate corresponding to each received frame is processed by the LO trim logic 810 to determine a final CFO estimate. In some embodiments, the trim logic 810 further triggers a first trim of the RF PLL 830 based on the final CFO estimate to adjust the first carrier frequency to match the second carrier frequency within a threshold tolerance. In these embodiments, the LO trim logic 810 further triggers a second trim of the analog front-end PLL 835 based on the final CFO estimate to ensure that both the carrier clock and the sampling clock are aligned and to support meeting the threshold tolerance. Thus, the radio 820 may be configured to transmit protocol data unit frames to an access point (e.g., AP / BS device 116) using the trimmed RF PLL. In some embodiments, the LO trim logic 810 may successively trigger a first trim of the RF PLL 830 and a second trim of the analog front-end PLL 835 in response to detecting a change in the CFO estimate during transmission of multiple protocol data unit frames to the access point.

[0082] FIG. 9 is a block diagram of a wireless device 900 that performs LO trim (RF PLL retuning) pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction for WLAN carrier frequency correction for uplink transmission in accordance with various embodiments.

[0083] In an extension to the embodiment of Figure 8, the wireless device 900 employs pre-correction to the final CFO estimate, performed via LO trim for coarse correction and digitally for fine correction, allowing a wide range of potential frequency changes to at least meet stringent standard levels for EVM, UTE and CFO. For example, this coarse / fine pre-correction approach may be implemented when the RF PLL accuracy is not sufficient to meet the specifications of the standard requirements.

[0084] 9, the wireless device 900 includes hardware 914 having pre-correction logic 910 coupled between the Rx processing hardware 614A, the LO 630 (or RF PLL), and digital pre-correction components also included in the hardware 914. In at least some embodiments, the pre-correction logic 910 is configured to determine that the LO trim (e.g., calculated according to FIG. 3) is insufficient to meet the target residual CFO value when transmitting to the AP / BS device 116. In some embodiments, the pre-correction logic 910 calculates the digital pre-correction offset required to meet the target residual CFO value and uses the digital pre-correction offset to cause digital up-conversion of the waveform that drives the digital processing of the protocol data unit frame.

[0085] More specifically, in at least some embodiments, the digital pre-correction components include a waveform generator 915 for generating a digital frame (e.g., TB-PPDU), a digital up-converter 916, and a digital resampler 917 coupled together in a string, the digital resampler being coupled to the DAC 822. In these embodiments, the pre-correction logic 910 determines a coarse LO trim value (f ) that the pre-correction logic 910 uses to adjust (trim) the LO 630 or the RF PLL based on the CFO estimate (e.g., the CFO estimate and / or the final CFO estimate). coarse) that coarse trim may not be sufficient to meet the stringent requirements for CFO of the IEEE standard, the pre-correction logic 910 may be configured to determine a set of digital parameters for updating the digital up-conversion of the digital up-converter 916 and / or the resampling of the digital resampler 917. In this manner, the pre-correction logic 910 may trigger digital pre-correction components in further fine digital pre-correction that affects the signal transmitted via the DAC 822 for incorporation into the protocol data unit frames transmitted by the radio 920.

[0086] 10 is a flow diagram of a method 1000 for performing LO trim (RF PLL retuning) pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction for WLAN carrier frequency correction for uplink transmission, according to various embodiments. In some embodiments, method 1000 ensures that the LOs of the devices are synchronized by performing LO trim on untriggered frames and digital pre-correction on triggered frames to correct for residual offsets remaining after LO trim.

[0087] Method 1000 may be performed by processing logic, which may include hardware (e.g., a processing device, circuitry, dedicated logic, programmable logic, microcode, device hardware, integrated circuits, etc.), a microcontroller (e.g., digital logic, programmed logic, firmware), or a combination thereof. In some embodiments, method 1000 is performed by control logic and / or hardware, such as pre-correction logic 910 of FIG. 9. Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be changed. Thus, the illustrated embodiment should be understood as merely an example, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Furthermore, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in every embodiment. Other process flows are possible.

[0088] At operation 1002, processing logic initializes the number of CFO offset values ​​to 0 and / or initiates a refresh state, which causes the number of CFO offset values ​​to be reset to 0 and all values ​​for CFO estimates 0 through N to be equal to 0.

[0089] At operation 1004, processing logic determines whether a frame has been received from the AP device. If yes, flow proceeds to operation 1006. If no, flow returns to operation 1004.

[0090] In operation 1006, processing logic stores the CFO estimates from all frames received from the AP.

[0091] At operation 1008, processing logic processes the stored CFO estimate using function g(.) In some embodiments, processing logic checks whether an RF PLL retuning operation can be triggered based on the final CFO estimate based on some criteria.

[0092] At operation 1010, processing logic determines whether a trigger frame has been received (eg, by a station device). If no, flow continues to operation 1016. If yes, flow continues to operation 1012.

[0093] In operation 1012, processing logic performs digital pre-correction for the triggered frame to correct for residual offsets remaining after the last LO trim.

[0094] At operation 1014, processing logic transmits a TB-PPDU frame (eg, TB-PPDU 218 of FIG. 2).

[0095] At operation 1016, processing logic determines whether to apply RF PLL tuning. If yes, flow continues to operation 1018. If no, flow returns to operation 1004.

[0096] At operation 1018, processing logic triggers an RF PLL retuning operation based on the final CFO estimate. Flow returns to operation 1002 where the processing device refreshes the state (i.e., sets N CFO estimate values ​​to 0 and sets all CFO estimate values ​​to 0).

[0097] 11 is a flow diagram of a method for performing WLAN carrier frequency correction for uplink transmissions according to some embodiments. In some embodiments, the frequency estimate (CFO estimate) is split into a coarse offset and a fine offset. The coarse estimate may be used by the LO trim and the fine estimate may be used by the digital pre-correction logic.

[0098] Method 1100 may be performed by processing logic, which may include hardware (e.g., a processing device, circuitry, dedicated logic, programmable logic, microcode, device hardware, integrated circuit, etc.), a microcontroller (e.g., digital logic, programmed logic, firmware), or a combination thereof. In some embodiments, method 1100 is performed by control logic and / or hardware, such as pre-correction logic 910 of FIG. 9. Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be changed. Thus, the illustrated embodiment should be understood as merely an example, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Furthermore, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in every embodiment. Other process flows are possible.

[0099] At operation 1102, processing logic initializes the number of CFO offset values ​​to 0 and / or initiates a refresh state, which causes the number of CFO offset values ​​to be reset to 0 and all values ​​for CFO estimates 0 through N to be equal to 0.

[0100] At operation 1104, processing logic determines whether a frame has been received from the AP device. If yes, flow proceeds to operation 1106. If no, flow returns to operation 1104.

[0101] At operation 1106, processing logic stores the CFO estimates from all frames received from the AP.

[0102] At operation 1108, processing logic processes the stored CFO estimate using function g(.) In some embodiments, processing logic checks whether an RF PLL retuning operation can be triggered based on the final CFO estimate based on some criteria.

[0103] At operation 1110, processing logic determines whether to apply RF PLL tuning. If yes, flow continues to operation 1112. If no, flow returns to operation 1104.

[0104] At operation 1112, processing logic coarse CFO offset and f fine Calculate the CFO offset.

[0105] At operation 1114, processing logic coarse LO trim is triggered by CFO offset, f fine The digital pre-correction is programmed with the CFO offset. Flow then returns to operation 1102 where the processing device refreshes the state (i.e., sets the N CFO estimates to 0 and sets all CFO estimate values ​​to 0).

[0106] FIG. 12 is a simplified graph 1200 illustrating LO trim trigger for WLAN carrier frequency correction for uplink transmission, according to some embodiments.

[0107] In some embodiments, the y-axis may represent the magnitude of the CFO estimate. The x-axis may represent time. In some embodiments, there may be N CFO estimates. In a first example, the CFO estimates 1202 and 1204 may be greater than the LO trim trigger threshold 1220. Because the CFO estimates 1202 and 1204 meet the LO trim trigger criteria, the CFO estimates 1202 and 1204 are input into function g(.) 1230 and a final CFO estimate is calculated. The LO trim 1250A is triggered (e.g., an RF PLL retune operation is triggered) and the LO trim is triggered based on the final CFO estimate.

[0108] In a second example, CFO estimates 1206, 1208, and 1210 are each less than the LO trim trigger threshold 1220. However, the predicted CFO estimate 1212 is greater than the LO trim trigger threshold 1220. In some embodiments, a predicted CFO estimate may be created using a trend line 1240. The trend line 1240 may be the product of a regression analysis, a cluster analysis, a time series analysis, or the like. Because the predicted CFO estimate 1212 is greater than the LO trim trigger threshold 1220 (i.e., meets the LO trim trigger criteria), the CFO estimates 1206, 1208, 1210 and the predicted CFO estimate 1212 are input into function g(.) 1230 and a final CFO estimate is calculated. An LO trim trigger 1250B is received (e.g., triggering an RF PLL retune operation) and the LO trim is triggered based on the final CFO estimate.

[0109] It will be apparent to those skilled in the art that at least some embodiments may be practiced without these specific details. In other instances, well-known components, elements, or methods are not described in detail or are presented in simple block diagram form to avoid unnecessarily obscuring the subject matter described herein. Thus, the specific details described below are merely exemplary. It may be contemplated that certain implementations may differ from these exemplary details and still be within the spirit and scope of the present embodiments.

[0110] Some portions of the detailed descriptions are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is generally conceived herein to be a self-consistent sequence of steps leading to a desired result. These steps require physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, primarily for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0111] However, it should be borne in mind that all of these and similar terms should be associated with the appropriate physical quantities and are merely convenient labels applied to these physical quantities. As is clear from the above description, unless otherwise noted, throughout the description, descriptions utilizing terms such as "receive," "determine," "calculate," "change," "calculate," "continue," "adjust," and the like, are understood to refer to operations and processes of a computing system or similar electronic computing device that manipulates data represented as physical (e.g., electronic) quantities in the registers and memory of the computing system and converts it into other data similarly represented as physical quantities in the memory or registers of the computing system or other such information storage, transmission, or display devices. Additionally, terms such as "first," "second," "third," "fourth," and the like, as used herein, are intended to be labels for distinguishing different elements and cannot have any ordering meaning according to their numerical designations.

[0112] References herein to "an embodiment," "one embodiment," "exemplary embodiments," "several embodiments," and "various embodiments" mean that a particular feature, structure, step, act, or characteristic described in connection with that embodiment is included in at least one embodiment. Moreover, appearances of the phrases "an embodiment," "one embodiment," "exemplary embodiments," "several embodiments," and "various embodiments" in various places in this specification do not necessarily all refer to the same embodiments.

[0113] This specification includes references to the accompanying drawings, which form a part of the detailed description. The drawings show diagrams according to exemplary embodiments. These embodiments, sometimes referred to herein as "examples," are described in sufficient detail to enable one skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable one skilled in the art to practice, make, and / or use the subject matter.

[0114] This specification includes references to the accompanying drawings, which form a part of the detailed description. The drawings show diagrams according to exemplary embodiments. These embodiments, sometimes referred to herein as "examples," are described in sufficient detail to enable one skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable one skilled in the art to practice, make, and / or use the subject matter.

[0115] Certain embodiments may be implemented by firmware instructions stored in a non-transitory computer-readable medium, such as, for example, a volatile memory and / or a non-volatile memory. These instructions may be used to program and / or configure one or more devices, including a processor (e.g., a CPU) or its equivalent (e.g., a processing core, a processing engine, a microcontroller, etc.). Non-transitory computer-readable storage media may include, but are not limited to, electromagnetic storage media, read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), flash memory, or other now known or later developed non-transitory types of media suitable for storing information.

[0116] Although the operations of the circuits and blocks herein are shown and described in a particular order, in some embodiments, the order of operations of each circuit / block may be changed such that certain operations may be performed in reverse order, or such that certain operations may be performed at least partially simultaneously and / or in parallel with other operations. In other embodiments, instructions or sub-operations of separate operations may be performed intermittently and / or alternatingly.

[0117] In the foregoing specification, the present disclosure has been described with reference to certain exemplary embodiments thereof. However, it will be apparent that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure as set forth in the appended claims. The specification and drawings are therefore to be regarded in an illustrative rather than a restrictive sense.

Claims

1. receiving a plurality of frames from an access point; determining a carrier frequency offset (CFO) estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing a first phase of a radio frequency phase-locked loop (RF PLL) to a second phase based on the final CFO estimate; The method includes:

2. The method further includes determining whether the final CFO estimate satisfies a criterion, and changing the first phase of the RF PLL to the second phase is based on the final CFO estimate satisfying the criterion. The method of claim 1.

3. Satisfying the criterion includes determining that the number of CFO estimates is equal to a threshold number of CFO estimates. The method of claim 2.

4. The method comprises: determining a magnitude of at least one of the CFO estimates; changing the threshold number of CFO estimates from a first number to a second number in response to a magnitude of the at least one of the CFO estimates meeting a threshold magnitude; Further comprising: The method according to claim 3.

5. Calculating the final CFO estimate based on the CFO estimate includes calculating at least one of an average, a weighted average, a moving average, or a mean. The method of claim 1.

6. The method comprises: receiving an additional frame from the access point; determining a CFO estimate for the additional frames received from the access point; calculating an updated final CFO estimate based on the CFO estimate; determining whether the updated final CFO estimate satisfies a criterion; changing the first phase of the RF PLL to the second phase based on the final CFO estimate satisfying the criterion, or continuing to receive additional frames from the access point based on the final CFO estimate not satisfying the criterion; Further comprising: The method of claim 1.

7. an RF circuit comprising a radio frequency (RF) phase-locked loop (PLL); a processing device coupled to the RF PLL; An apparatus comprising: the RF circuit receives a plurality of frames from an access point while the RF PLL operates in a first phase; The processing device comprises: determining a carrier frequency offset (CFO) estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from the first phase to a second phase based on the final CFO estimate; To carry out A processing device; An apparatus comprising:

8. the processing device further determines whether the final CFO estimate satisfies a criterion, and the changing of the first phase of the RF PLL to the second phase is based on the final CFO estimate satisfying the criterion.

8. The apparatus of claim 7.

9. satisfying the criterion includes determining that a number of CFO estimates is equal to a threshold number of CFO estimates, the threshold number of CFO estimates being based on a magnitude of the CFO estimates.

9. The apparatus of claim 8.

10. and calculating the final CFO estimate based on the CFO estimate includes calculating at least one of an average, a weighted average, a moving average, or a mean.

8. The apparatus of claim 7.

11. The processing device comprises: receiving an additional frame from the access point; determining a CFO estimate for the additional frames received from the access point; calculating an updated final CFO estimate based on the CFO estimate; and determining whether the updated final CFO estimate satisfies a criterion; and changing the first phase of the RF PLL to the second phase based on the final CFO estimate satisfying the criterion or continuing to receive additional frames from the access point based on the final CFO estimate not satisfying the criterion; Further, 8. The apparatus of claim 7.

12. The processing device includes a state machine, the state machine comprising: determining a CFO estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from the first phase to a second phase based on the final CFO estimate; To carry out 8. The apparatus of claim 7.

13. The processing device comprises firmware, the firmware comprising: determining a carrier frequency offset (CFO) estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from the first phase to a second phase based on the final CFO estimate; To carry out 8. The apparatus of claim 7.

14. 1. A system comprising a first circuit and a second circuit, The first circuit comprises a radio frequency (RF) phase-locked loop (PLL), the first circuit receiving a plurality of frames from an access point; The second circuit includes: determining a carrier frequency offset (CFO) estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from a first phase to a second phase based on the final CFO estimate; To carry out system.

15. the second circuit further determines whether the final CFO estimate satisfies a criterion, and the changing of the first phase of the RF PLL to the second phase is based on the final CFO estimate satisfying the criterion. The system of claim 14.

16. satisfying the criterion includes determining that a number of CFO estimates is equal to a threshold number of CFO estimates, the threshold number of CFO estimates being based on a magnitude of the CFO estimates. The system of claim 15.

17. The calculating the final CFO estimate includes calculating at least one of an average, a weighted average, a moving average, or a mean. The system of claim 14.

18. The second circuit includes: receiving an additional frame from the access point; determining a CFO estimate for the additional frames received from the access point; calculating an updated final CFO estimate based on the CFO estimate; and determining whether the updated final CFO estimate satisfies a criterion; and changing the first phase of the RF PLL to the second phase based on the final CFO estimate satisfying the criterion or continuing to receive additional frames from the access point based on the final CFO estimate not satisfying the criterion; Further, The system of claim 14.

19. The second circuit includes a state machine, the state machine comprising: determining a CFO estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from the first phase to a second phase based on the final CFO estimate; To carry out The system of claim 14.

20. The second circuit comprises firmware, the firmware comprising: determining a CFO estimate for each of the plurality of frames received from the access point; calculating a final CFO estimate based on the CFO estimate; changing the RF PLL from the first phase to a second phase based on the final CFO estimate; To carry out The system of claim 14.

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