WIRELESS PRO-FRAME-BASED LOCAL OSCILLATOR TRIM FOR UPLINK MULTI-USER TRANSMISSION

Abstract

A wireless device comprises a radio unit, which includes a front end and a first local oscillator (LO), and control logic coupled to the radio unit. The control logic determines, from a received trigger frame, a carrier frequency offset (CFO) between the first carrier frequency of the first LO and the second carrier frequency of a second LO of an access point operating in a multi-user transmission mode. Based on the CFO, the control logic triggers LO trimming of the first LO to adjust the first carrier frequency so that it matches the second carrier frequency within a threshold tolerance. The radio unit can then transmit a protocol data unit frame to the access point using the trimmed first LO, with the protocol data unit frame associated with the multi-user transmission mode.

Description

TECHNICAL FIELD

[0001] This disclosure relates to wireless per-frame-based local oscillator trimming for uplink multi-user transmission. STATE OF THE ART

[0002] Wireless local area network (LAN) technology has evolved to the point where wireless devices can communicate with very high throughput and high efficiency, supporting both multi-user (MU) orthogonal frequency division multiple access (OFDMA) and multi-user multiple-input and multiple output (MU-MIMO) in both the downlink and uplink directions.Because an access point (AP) or base station (BS) in uplink transmissions with these WiFi™ 6 technologies requires a strict level of timing synchronization, power control for target reception power, and high signal quality from multiple transmission devices, support for MU-OFDMA and MU-MIMO in the uplink direction has led to stricter requirements (compared to legacy methods) regarding transmission devices. These strict WiFi™ 6 requirements include those related to in-band distortions, such as error vector magnitude (EVM), and out-band distortions, such as unused tone error (UTE) and carrier frequency offset (CFO), with respect to the AP / BS. This in turn leads to strict requirements regarding carrier penetration of trigger-based physical layer protocol data unit (TB-PPDU) frames received by the transmitting devices.While the standard associated with WiFi™ 6 specifies 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 standard does not teach how this should be practically implemented by such transmitting devices. BRIEF DESCRIPTION OF THE CHARACTERS Fig. 1 is a block diagram of an example wireless communication system according to some embodiments. Fig. 2 is a simplified graph illustrating multiple wireless devices (stations) in an uplink MU transmission (MU-MIMO or OFDMA) according to one embodiment. Fig. 3 is a set of carrier frequency diagrams illustrating the operation of digital pre-correction according to at least one embodiment. Fig. 4 is a set of carrier frequency diagrams illustrating transmit (Tx) local oscillator trim pre-correction according to at least one embodiment. Fig. 5 is a timing diagram illustrating how trigger-based LO trim pre-correction may be implemented within a short interface space (SIFS) time period, according to at least some embodiments. Fig. 6 is a block diagram of a wireless device having a microcontroller to perform calculations using frequency estimation from physical layer (PHY) hardware and trigger LO trim pre-correction according to some embodiments. Fig. 7 is a block diagram of a wireless device employing hardware to perform frequency estimation and trigger LO trim pre-correction according to some embodiments. Fig. 8 is a block diagram of a wireless device employing hardware to perform both LO trim pre-correction and analog front-end (AFE) phase-locked loop (PLL) trimming, according to some embodiments. Fig. 9 is a flow diagram of a method for performing LO trim pre-correction in a transmission device according to various embodiments. Fig. 10 is a flow diagram of a method for performing either LO trim pre-correction or digital pre-correction based on a frequency estimate from a trigger frame, according to some embodiments. Fig. 11 is a block diagram of a wireless device performing LO trim pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction according to various embodiments. Fig. 12 is a block diagram of a method for performing LO trim pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction according to various embodiments. Fig. 13 is a timing diagram illustrating how, according to at least some embodiments, trigger-based LO trim pre-correction may be implemented within the SIFS time period, but wherein the LO trim based frequency calculation is performed after preamble processing. Fig. 14 is a flow diagram of an example method for performing LO trim pre-correction within the SIFS time period, according to at least some embodiments, wherein the LO trim based frequency calculation is performed after preamble processing. DETAILED DESCRIPTION

[0003] The following description sets forth numerous specific details, such as examples of specific systems, devices, components, methods, and so on, to provide a good understanding of various embodiments for wireless per-frame-based local oscillator trimming for uplink multi-user transmission. Wireless LAN devices have evolved over several generations. For example, the first two generations of the WiFi™ standard were based on the single-carrier spread spectrum technique, while later generations adopted a more efficient ODFM as the basic modulation technique. Even later generations added support for multiple antenna technology, e.g., MIMO, to enhance reliability and throughput performance, for example, using spatial dimension for redundancy and multiplexing.However, the access mechanism used Carrier Sense Multiple Access with Collision Avoidance (CDMA-CA) and random back-off as the access mechanism to share a medium or channel among users. This meant that only a single user (SU) could use the medium or channel at a time.

[0004] Even more recently, the Institute of Electrical and Electronics Engineers' IEEE 802.11ac standard, also known as Very-High-Throughput (VHT) or Wi-Fi™ 5, added support for multi-user (MU) capability in the downlink direction using MU-MIMO technology. This allowed multiple users to share the medium at a time, e.g., by multiplexing together. More recently, the IEEE 802.11ax standard, also known as High-Efficiency (HE) or WiFi 6, added multi-user (MU) support in both the uplink and downlink directions using OFDMA and MU-MIMO techniques. These latest standards consider, on the downlink side, access point (AP) or base station (BS) frame synchronization as a standard point-to-multipoint transmission, e.g.,Because AP / BS only send content to individual wireless devices, the content is generally received by multiplexing different content to the correct wireless device. In contrast, on the uplink side, AP / BS are configured to receive transmissions from multiple wireless devices (multipoint-to-point), so that AP / BS correctly receives the content when multiple streams are simultaneously received from multiple devices to be subsequently transmitted. This requires synchronization of the multiple wireless devices.

[0005] As mentioned, stringent WiFi™ 6 requirements for uplink transmission include those related to in-band distortions, such as error vector magnitude (EVM), and out-of-band distortions, such as unused tone error (UTE) and carrier frequency offset (CFO) with respect to the AP / BS. This, in turn, leads to stringent requirements regarding carrier breakdown within the access point from the TB-PPDU frames received by the transmitting devices. While the standard associated with WiFi™ 6 specifies that transmitting devices must pre-correct in-band and out-of-band distortions to meet these stringent standard levels for EVM, UTE, and CFO, the WiFi™ 6 standard does not teach how this should be practically implemented by such transmitting devices. As will be discussed in more detail, current digital pre-correction techniques, although they improve carrier breakdown (e.g.reduce), do not do so at the level now required under the latest WiFi™ standards.

[0006] To address these and other deficiencies with known carrier breakdown reduction approaches, the present disclosure sets forth configuring and / or operating wireless devices instead of performing local oscillator (LO) trimming at a carrier frequency of transmitting devices (or in addition to performing digital pre-correction). By directly adjusting the LO within the radio unit circuitry of these wireless transmitting devices, their carrier frequencies can be subjected to greater adjustments and better meet stringent standard levels for EVM, UTE, and CFO.

[0007] Thus, in at least some embodiments, a wireless device is disclosed that employs a radio unit with a first LO, e.g., as may be employed in or by a radio frequency (RF) phase-locked loop (PLL). The RF PLL may, for example, comprise a type of voltage-controlled oscillator (VCO) operating at a frequency adjustable by changing an input voltage of the VCO according to reference input and feedback voltages of the PLL. In these embodiments, the wireless device further employs control logic to determine, from a trigger frame received from the AP / BS, a carrier frequency offset (CFO) between a first carrier frequency of the first LO and a second carrier frequency of a second LO of an access point or base station (AP or BS) operating in a multi-user transmission mode.In embodiments, the control logic, based on the CFO, triggers an LO trim of the first LO to adjust the first carrier frequency to match the second carrier frequency within a threshold tolerance. In these embodiments, the radio unit transmits a protocol data unit frame (e.g., TB-PPDU) to the AP / BS using the trimmed first LO, wherein the protocol data unit frame is associated with the multi-user transmission mode.

[0008] In various embodiments, the control logic is implemented in at least one of a microcontroller or hardware, as will be discussed in more detail. In at least some embodiments, the control logic continuously triggers the LO trim of the first LO on a per-frame basis in response to detecting changes in the CFO during the transmission of multiple protocol data unit frames to one or more access points (APs or BSs). Additional embodiments and variations of the implementation are described with reference to Fig. 2-14 discussed in more detail.

[0009] The present disclosure includes several advantages, including the ability to provide for the carrier frequency offset (CFO) by directly updating the LO frequency at which the radio unit circuitry operates based on an estimated CFO determined from a previous trigger frame on a per-packet basis. This approach also relaxes the residual carrier breakdown requirements to be able to meet UTE requirements. Together with digital pre-correction implemented for fine carrier frequency adjustments, direct LO trims in wireless radio units can implement coarse carrier frequency adjustments, enabling a wider range of potential frequency modifications to meet at least the stringent standard levels for EVM, UTE, and CFO.Additional benefits will be apparent to those familiar with modern wireless technologies and recent IEEE standards.

[0010] Fig. 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 a network hardware component 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 cellular phones 122 and 128. The details of one embodiment of such wireless devices when functioning as transmitting devices are described in more detail below.

[0011] In embodiments, the base stations (BSs) or access points (APs) 112-116 are operably connected to the network hardware component 134 via local area network connections 136, 138, and 140. The network hardware component 134, which may be a router, a switch, a bridge, a modem, a system controller, etc., provides a local area network connection 142 for the communication system 100. The base stations or access points 112-116 each have 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, the wireless devices register with a respective base station or access point 112-116 to receive services from the communication system 100. For direct connections (i.e.In point-to-point communications, wireless communication devices communicate directly over a dedicated channel.

[0012] The various wireless devices 118-132 and BSs or APs 112-116 may each include a processor and a communication interface to support communications with any other of the wireless devices 118-132 and BSs or APs 112-116. In one operational example, a processor and the communication interface implemented in one of the devices (e.g., any one of the wireless devices 118-132 and BSs or APs 112-116) are configured to process at least one signal received from another of the devices (e.g., any 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 of the devices.

[0013] It is noted that a general reference to a communication device, such as a wireless device (e.g., wireless devices) 118-132 and BSs or APs 112-116 in Fig. 1) or any other communication devices and / or wireless communication devices may alternatively be referred to herein generally using the term "device" for brevity. The processor and communication interface of any of the various devices, wireless devices 118-132, and BSs or APs 112-116 may be configured to support communications with any other of the various devices, wireless devices 118-132, and BSs or APs 112-116. Such communications may be unidirectional or bidirectional between devices.Such communications may also be unidirectional between devices at one time and bidirectional between those devices at another time, although the embodiments herein generally focus on wireless devices transmitting to a BS or AP 112-116 operating in a multi-user transmission mode, such as MU OFDMA or MU-MIMO.

[0014] In one operational example, AP / BS device 116 (representative of any one of BSs or APs 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 an OFDMA example, device 130 uses a first at least one subcarrier and device 132 uses a second at least one subcarrier. Generally, different subsets of subcarriers are allocated for use by different devices. Such allocation may be dynamic, adaptive, etc., for different devices, for different symbols and / or at different times.

[0015] In these embodiments, the AP / BS device 116 receives a first OFDMA symbol comprising first data from the device 130 modulated on a first set of at least one sub-carrier and second data from the device 132 modulated on a second set of at least one sub-carrier. 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 another case / other embodiments, the AP / BS device 116 receives a first MU-MIMO symbol comprising first data from the device 130 modulated on a first set of at least one sub-carrier and second data from the device 132 modulated on a first set of at least one sub-carrier.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 cases, the first device 130 and second device 132 transmit data with the pre-corrected CFO, which the first and second devices 130 and 132 estimate based on the trigger frame preceding the data frame. Such capability in the first and second devices 130 and 132 may generally be referred to as a CFO pre-correction capability. With respect to these embodiments and other embodiments or examples provided herein, there may be cases where the pre-corrected CFO is at 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).

[0016] Generally, the AP / BS device 116 operates by processing data from another device that is included in the same set of at least one subcarrier. A number of 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 the CFO, the other device, similar to devices 130 and 132 above, modifies or adapts communications to and / or from that device to compensate for any CFO that may exist between the AP / BS device 116 and the other device to ensure effective communications, synchronization, and improved performance of communications between the devices.

[0017] Fig. Figure 2 is a simplified graph illustrating multiple wireless devices (stations) in an uplink MU transmission (MU-MIMO or OFDMA) according to one embodiment. For example, the stations are labeled STA1 through STA4, which can generally represent any of the wireless devices 118-132 operating in a frequency domain and spatial domain. With OFDMA, for example, the channel bandwidth is divided into resource units (RUs) of various sizes. The size of an RU can vary from the smallest 26 subcarriers (or 2 megahertz (MHz)) to 996 tones (or 77.8 MHz). The size and location of the RUs is defined for 20 MHz, 40 MHz, 80 MHz channels, and 80+80 or 160 MHz channels.

[0018] In various embodiments, these RUs are used for data subcarriers, which are used to carry data information and make up the bulk of the subcarrier allocation, pilot subcarriers used for phase tracking for channel estimation, direct current (DC) subcarriers at the center frequency of the channel, and guard band / zero subcarriers used at the band edges to protect against interference from neighboring RUs. A different number and size of RUs can be allocated for transmissions to different users based on how much data each station requires. In embodiments, the AP / BS device 116 is responsible for RU allocation and coordination. For example, applications that require a lot of data, such as streaming video, can be allocated a large RU, while applications that require very little data can be allocated a small RU.Each RU may use a different modulation scheme, coding rate, and coding level, and RU assignments may vary on a frame-by-frame basis.

[0019] In embodiments, OFDMA uplink transmissions are more complex than downlink operations because, in uplink transmission, traffic is transmitted simultaneously from multiple stations to AP / BS device 116. In uplink transmission, AP / BS device 116 acts as the operation and transmission coordinator. First, AP / BS device 116 sends a trigger frame 210 to other stations (e.g., STA1, STA2, STA3, STA4) that will participate in the upcoming transmission. In these embodiments, these stations transmit simultaneously on their respective RUs in response to the trigger frame, e.g., transmitting an uplink (UP) MU-PDDU frame 220. In response to receiving the UP MU-PDDU frames 220, AP / BS device 116 transmits an acknowledgment frame 230 back to the respective stations.

[0020] In various embodiments, the client station adjusts its timing, frequency, and power levels based on the trigger frame 210 to participate in this transmission. Carrier frequency adjustment is considered a particular focus for adjustment in this disclosure. Current IEEE standards require client stations participating in an OFDMA transmission to transmit 400 nanoseconds (ns) apart. To synchronize the clients, the AP / BS device 116 transmits the trigger frame 210. This frame contains information about the RU of the OFDMA subcarrier assigned to each station. In response, the participating clients must initiate a transmission of the uplink signal after a predetermined short interframe space (SIFS) time interval of 16 microseconds (µs) + / - 400 ns after the end of the trigger frame, as defined by the IEEE 802.11ax standard.This SIFS time period could change in the future, so the exact time duration is not critical, but it is instructive to see that it is a very short time interval that is not expected to vary.

[0021] In these embodiments, to prevent inter-carrier interference (ICI) between clients transmitting simultaneously, such as the aforementioned in-band and out-of-band distortions, the stations participating in the transmission will also pre-compensate for the carrier frequency offset (CFO). The client stations adjust their carrier frequency based on the trigger frame 210 received from the AP / BS device 116. The IEEE 802.11ax standard requires that the residual CFO error after compensation be less than 350 Hz. Again, the exact residual CFO error level required by the standard could change (it could likely become even more stringent), and it is included here only as an example of how stringent the requirement currently is in the IEEE 802.11ax standard.

[0022] Fig. 3 is a set of carrier frequency diagrams illustrating the function of digital pre-correction according to at least one embodiment. As wireless technology evolves toward higher frequencies, shorter antennas are being used in addition to the upconversion architecture to enable transmission at these higher frequencies. To achieve this, radio units in wireless devices modulate a baseband frequency to a carrier frequency, e.g., via a circuit in which the baseband signal is multiplied by the local oscillator (LO) frequency. If the LO is not ideal, carrier breakdown may occur as a modulated signal is demodulated at the Rx LO of an AP / BS device 116.

[0023] Certain modern wireless devices correct carrier frequency offset and carrier breakdown using digital correction techniques. The use of digital techniques for carrier frequency correction causes carrier breakdown at the transmitter to be offset from the AP (or BS) carrier frequency, which will be referred to as the receiver (Rx) LO center frequency. To illustrate this, the figure below (A) illustrates Fig. 3, that the Tx baseband spectrum of the DC-RU is aligned to the Tx-LO before digital pre-correction. In embodiments, the Tx-LO is located within the radio unit of the wireless device 120, which is exemplary for any of the wireless devices 118-132, but has been selected below as the focus of description for clarity and ease of explanation. The lower image (B) illustrates that the DC-RU is aligned to the Rx-LO after baseband correction. Finally, the upper image (C) illustrates the Tx radio unit output, showing that the Tx-LO breakdown is not aligned to the Rx-LO center frequency.

[0024] In embodiments, this misalignment between the Tx-LO and the Rx-LO within the DC-RU (e.g., a delta of f Rx -f Tx) a carrier breakdown of the Tx LO frequency within the AP / BS device 116 with the Tx LO frequency. This carrier breakdown results in degraded EVM (in-band distortion) for the RU, above the DC carrier, and degraded UTE (out-of-band distortion) for the RU near the DC. Digital pre-correction therefore results in a strict requirement regarding the amount of residual carrier breakdown in order to be able to meet EVM and UTE requirements.

[0025] Fig. Figure 4 is a set of carrier frequency diagrams illustrating transmit (Tx) local oscillator trim precorrection according to at least one embodiment. To address the deficiencies in the digital precorrection approach, Fig. 4 shows the results instead of performing a trim of the Tx LO frequency (e.g., the transmit carrier frequency) to compensate for the CFO. In embodiments, this is performed by directly updating the LO frequency of the radio frequency (RF) circuitry of wireless device 120 (e.g., any of wireless devices 118-132) based on an estimated offset from a previous trigger frame. This relaxes the residual carrier leakage requirements to be able to meet standards-based UTE (among others) requirements.

[0026] For example, in disclosed embodiments, control logic of wireless device 120 determines, from a received trigger frame 210, a carrier frequency offset (CFO) between a first carrier frequency of the Tx LO and a second carrier frequency of the Rx LO of AP / BS device 116 operating in a multi-user transmission mode. In these embodiments, the control logic further triggers, based on the CFO, an LO trim of the Tx LO to adjust the first carrier frequency to match the second carrier frequency within a threshold tolerance. This threshold tolerance may correspond to a low frequency stipulated by the IEEE standard, which, for example, is within 350 Hz, as mentioned in one example, although a CFO of less than or greater than 350 Hz is conceivable, such as 450 Hz, 400 Hz, 300 Hz, 350 Hz, 250 Hz, or the like.In various embodiments, this direct LO trimming technique may depend on the wireless device radio's RF switching technology exercising control of the LO frequency with a granularity of a few Hz, a radio's PLL having a lock range of up to a few hundred kilohertz (kHz) (e.g., the RF PLL is automatically fixed to a target frequency), and the LO lock-in time to the trimmed frequency being within the SIFS time period. Therefore, in some embodiments, the control logic of the wireless device 120 is configured to adjust the carrier frequency of the Tx LO to within a few hertz of a target frequency associated with the Rx carrier frequency (e.g., the AP / BS device 116).

[0027] Fig. 5 is a timing diagram 500 illustrating how trigger-based LO trim pre-correction may be implemented within a short interface space (SIFS) time period 515, according to at least some embodiments. Assuming that time moves from left to right in the timing diagram 500, a radio unit (Rx) for the wireless device 120 receives a trigger frame 510, from which the control logic of the wireless device 120 may determine the CFO, e.g., the carrier frequency offset between the Tx LO of the wireless device 120 and the Rx LO of the AP / BS device 116 (e.g., f Tx - f Rx). In various embodiments, after the radio unit receives the trigger frame 510, it experiences a physical layer (PHY) Rx latency 520 for processing the trigger frame 510 through the physical layer, followed by a medium access control (MAC) processing delay 530 before performing the LO trimming calculation 540. At the end of the PHY Rx latency 520, the CFO estimates become available to the control logic of the wireless device 120. Therefore, in these embodiments, trigger frame reception and MAC-level content validation are performed during the PHY Rx latency 520 and MAC processing delay 530 periods.

[0028] In these embodiments, during the MAC processing delay 530, the control logic of the wireless device 120 calculates the LO trim value as a signal to the Tx LO (or RF PLL including the Tx LO) to compensate (e.g., substantially remove) the CFO, which will be discussed in more detail with reference to the subsequent figures. At a particular time 550, e.g., after determining the LO trim 540, after the period of the MAC processing delay 530, the control logic may trigger a trim of the Tx LO, e.g., after the period of the MAC processing delay 530. B. in sufficient time for the Tx LO to settle (e.g., during an LO settlement period 555) before an end of the SIFS time period 515. Therefore, a PHY Tx latency 560 before the TB PPDU frame 570 can be transmitted (Tx) can be used to calculate approximately the latest possible instant to determine the particular time 550 at which the LO trim of the Tx LO should be triggered.In this way, the trim of the Tx-LO will have time to settle and cause a shift in the Tx carrier frequency of the wireless device 120 before the radio unit transmits a protocol data unit frame (e.g., the TB-PDDU frame 570) using the trimmed Tx-LO.

[0029] Fig. 6 is a block diagram of a wireless device 600 including a microcontroller to perform calculations using frequency estimates from PHY hardware and trigger LO trim pre-correction, according to some embodiments. In embodiments, the wireless device 600 is one 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, a microcontroller 610 (e.g., control logic), hardware 614, including Rx processing hardware 614A and Tx processing hardware 614B, a radio unit 620 including RF circuitry, and an external oscillator 650 (e.g., an external crystal or XTAL).In various embodiments, the radio unit 620 includes a digital-to-analog converter (DAC) 622, a demodulator 624A, an analog-to-digital converter (ADC) 626, a modulator 624B, a local oscillator (LO) 630 (also referred to herein as Tx-LO), and a front-end (hereinafter FEM 640) having one or more front-end modules operatively coupled to the antenna 608. In embodiments, the microcontroller 610 is embodied in digital logic, or programmed hardware, and executes microcode, such as firmware.

[0030] In these embodiments, the programmable processor 602 executes instructions (e.g., computer code and / or firmware) to provide parameters for and drive the functionality of the hardware 614. In embodiments, the hardware 614 is coupled to the radio unit 620, and the microcontroller 610 is coupled between the Rx processing hardware 614A and the LO 630 of the radio unit 620. In some embodiments, the LO 630 is implemented, for example, within an RF PLL of the RF circuitry. In some embodiments, the LO 630 is integrated into the RF circuitry of the radio unit 620 and is either a resistive-capacitive (or RC) oscillator or a real-time clock (RTC) oscillator. In some embodiments, the LO trim triggers a selection or deselection of capacitors in a capacitor bank and / or resistors in a resistor bank to tune the Tx LO carrier frequency.

[0031] In disclosed embodiments, an incoming signal (e.g., containing the trigger frame 210) is detected by the antenna 608 and the FEM 640 and passed to the demodulator 624A (e.g., a demodulator) to demodulate the received signal, which is passed by the ADC 626 to the RX processing 614A. In embodiments, this demodulation extracts the original information-carrying signal, which includes the trigger frame 210. The Rx processing hardware 614A may then process the demodulated signal to obtain, among other information, an estimate of the CFO from the trigger frame 210. In embodiments, the Rx processing hardware 614A provides the CFO information to the microcontroller 610.In these embodiments, the microcontroller 610 is programmed to process the estimated CFO to generate an LO trim value to cause the LO 630 (or RF PLL including the LO 630) to make a carrier frequency shift that compensates for the estimated CFO.

[0032] Thus, in embodiments, the transmit side of wireless device 600 generates a transmission with a trimmed LO carrier frequency. For example, Tx processing hardware 614B processes information for the upcoming transmit signal, which is converted to an analog signal by the DAC. In these embodiments, modulator 624B modulates the analog signal and provides the modulated analog signal to FEM 640 for transmission. In some embodiments, modulator 624B uses a frequency trimmed by LO 630, and therefore, the TB-PDDU frame transmitted from FEM 640 and antenna 608 is based on the shifted carrier frequency of the trimmed LO 630 (e.g., trimmed Tx LO).In this way, carrier breakdown (which causes in-band and out-of-band distortion) is better managed by pre-correcting the Tx LO (the LO 620) of the wireless device 600 to compensate for the CFO between the Rx LO (the AP / BS device 116) and Tx LO.

[0033] Furthermore, in some embodiments, the radio unit 620 includes a radio frequency (RF) phase-locked loop (PLL) including the first LO. In these embodiments, the control logic (e.g., the microcontroller 610 in this embodiment) is configured to calculate an updated RF PLL frequency based on the CFO, trigger the RF PLL to operate at the updated RF PLL frequency in response to the LO trim, and, after transmission of the protocol data unit frame, cause the RF PLL to operate at a default RF PLL frequency.

[0034] Fig. Figure 7 is a block diagram of a wireless device 700 that uses hardware to perform frequency estimation and trigger LO trim pre-correction according to some embodiments. In some embodiments, the wireless device 600 is Fig. 6 is modified so that, instead of the microcontroller 610, LO trim calculation hardware 710 (which may be discrete hardware components, programmed hardware components, or a combination thereof) is included in the hardware 614 provided on the wireless device 700. In these embodiments, the LO trim calculation hardware 710 calculates the LO trim value based on the estimated CFO received from the Rx processing hardware 614A. Therefore, in this embodiment, the LO trim calculation hardware 710 provides the LO trim value to the LO 630 (or an RF PLL including the LO 630) to provide the Tx LO carrier frequency shift to compensate for the estimated CFO.

[0035] Fig. Figure 8 is a block diagram of a wireless device 800 that uses hardware to perform both LO trim pre-correction and analog front-end (AFE) phase-locked loop (PLL) trimming, according to some embodiments. In embodiments, the wireless device 800 of Fig. 8 to the wireless device 700 of Fig. 7 in implementations where the device includes different PLLs to generate clocks for AFE and RF separately. For example, in the embodiment of Fig. 8 a radio unit 820 of the wireless device 800 comprises a radio frequency (RF) phase-locked loop (PLL) or RF-PLL 830 (which may, for example, comprise an LO such as the LO 630 of Fig. 6-7), an ADC 826 coupled to demodulator 624A driven by RF PLL 830, a DAC 822 coupled to modulator 624B driven by RF PLL 830, and an analog front-end PLL 835 (or AFE PLL) configured to generate a clock to drive ADC 826 and DAC 822. In embodiments, receive (Rx) processing hardware 614A is coupled to ADC 826 and trim logic 810. In embodiments, the transmit (Tx) processing hardware 614B is coupled to the DAC 822 and the trimming logic 810 is coupled to both the AFE PLL 835 and the RF PLL 830.

[0036] In these embodiments, the hardware 814 of the wireless device 800 includes the LO trimming logic 810 coupled to the RF PLL 830 and the analog front-end PLL 835, where the LO trimming logic 810 provides a clocking mechanism in the radio unit 820 for a separate PLL for the AFE / DAC clocks from the RF PLL 830 that clocks the demodulator 624A and the modulator 624B. Therefore, in these embodiments, the LO trimming logic 810 is configured to trim both the analog front-end PLL 835 and the RF PLL 830 separately to provide the capability for both carrier and sampling clock frequency tuning of the RF circuitry in the radio unit 820.

[0037] In various embodiments, therefore, the LO trimming logic 810 is configured to determine, from a received trigger frame, a carrier frequency offset (CFO) between a first carrier frequency of the RF PLL and a second carrier frequency of a local oscillator (LO) of an access point (e.g., the AP / BS device 116) operating in a multi-user transmission mode. In these embodiments, the LO trimming logic 810 further triggers, based on the CFO, a first trim of the RF PLL 830 to adjust the first carrier frequency to match the second carrier frequency, within a threshold tolerance. In these embodiments, the LO trimming logic 810 further triggers, based on the CFO, a second trim of the analog front-end PLL 835 to ensure that both carrier and sampling clocks are aligned and to assist in meeting the threshold tolerance.Radio unit 820 may therefore be configured to transmit a protocol data unit frame to the access point (e.g., AP / BS device 116) using the trimmed RF PLL. In some embodiments, LO trim logic 810 will continuously trigger the first trim of RF PLL 830 and the second trim of analog front-end PLL 835 in response to detecting changes in the carrier frequency offset (CFO) during the transmission of multiple protocol data unit frames to the access point.

[0038] Fig. 9 is a flow diagram of a method 900 for performing LO trim pre-correction in a transmitting device according to various embodiments. The method 900 may be performed by processing logic that may include hardware (e.g., 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, the method 900 is performed by control logic and / or hardware of one of the wireless devices 600, 700, and / or 800 ( Fig. 6-8). In some embodiments, method 900 refers to Rx processing within this control logic and / or hardware performed prior to performing Tx processing of Tx frames. Although shown in a particular sequence or order, unless otherwise specified, the order of the processes may be modified. The illustrated embodiments should be understood as examples only, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, one or more processes may be omitted in various embodiments. Therefore, not all processes are required in every embodiment. Other process flows are possible.

[0039] At operation 905, the processing logic will determine whether receiving a frame in a modulated signal has ended and continue to wait until it is verified that a modulated signal has been completely received. The frame may or may not be a trigger frame.

[0040] At operation 910, the processing logic determines whether a frame sequence check (FCS) was passed on the received modulated signal. An FCS can be understood as an error detection code added to a frame in a communications protocol. Frames are used to send payload data from a source to a destination. If the FCS was not passed, the method 900 ends; otherwise, if the FCS was passed, the method 900 continues with operation 915.

[0041] At operation 915, the processing logic determines whether a trigger frame has been received from the access point, e.g., the AP / BS device 116. Whether the frame was received at operation 905 is detected, for example, as a trigger frame. If no trigger frame was received at operation 920, the processing logic processes an Rx frame, e.g., because the received frame is not the trigger frame. At operation 925, the processing logic optionally sends a response frame (e.g., an ACK frame) to the AP / BS device 116.

[0042] At operation 930, in response to determining that a trigger frame has been received, the processing logic calculates an RF PLL frequency using the CFO estimate after trigger frame reception and content validation at a medium access control level, the latter having been described with reference to Fig. 5 discussed in detail.

[0043] At operation 935, based on the CFO estimate, the processing logic triggers a trim of the RF PLL (or Tx LO) to adjust the first carrier frequency of the wireless transmission device to match the second carrier frequency of the AP / BS device 116, within a threshold tolerance. In some embodiments, the processing logic stores a default PLL (or LO) frequency for the Tx LO just before performing operation 935 so that the default PLL (or LO) frequency can be restored later at operation 945. Furthermore, triggering the trim of the RF PLL (or Tx LO) can be performed in sufficient time for the Tx LO to settle, before an end of the SIFS time period 555.

[0044] At operation 940, the processing logic transmits a protocol data unit frame (e.g., the TB-PPDU frame) to the access point (e.g., AP / BS device 116) using the trimmed first LO. In embodiments, the protocol data unit frame is associated with the multi-user transmission mode.

[0045] At operation 945, the processing logic restores the RF PLL frequency, e.g., a default frequency or the frequency used prior to the Tx LO trim, thereby enabling, e.g., operation in a default state of the RF circuitry before repeating the method 900, e.g., in response to receiving another trigger frame at operation 915.

[0046] Fig. 10 is a flow diagram of a method 1000 for performing either LO trim pre-correction or digital pre-correction based on a frequency estimate from a trigger frame, according to some embodiments. The method 1000 may be performed by processing logic that may include hardware (e.g., 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, the method 1000 is performed by control logic and / or hardware of one of the wireless devices 600, 700, and / or 800 ( Fig. 6-8). In some embodiments, method 1000 refers to Rx processing within this control logic and / or hardware performed prior to performing Tx processing of Tx frames. Although shown in a particular sequence or order, unless otherwise specified, the order of the processes may be modified. The illustrated embodiments should be understood as examples only, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, one or more processes may be omitted in various embodiments. Therefore, not all processes are required in every embodiment. Other process flows are possible.

[0047] At operation 1005, the processing logic will determine whether receiving a frame in a modulated signal has ended and continue waiting until it is verified that a modulated signal has been completely received. The frame may or may not be a trigger frame.

[0048] At operation 1010, the processing logic determines whether a frame sequence check (FCS) was passed on the received modulated signal. An FCS can be understood as an error detection code added to a frame in a communications protocol. Frames are used to send payload data from a source to a destination. If the FCS was not passed, the method 1000 ends; otherwise, if the FCS was passed, the method 1000 continues with operation 1015.

[0049] At operation 1015, the processing logic determines whether a trigger frame was received from the access point, e.g., AP / BS device 116. If no trigger frame was received at operation 1020, the processing logic processes an Rx frame, e.g., because the received frame is not the trigger frame. At operation 1025, the processing logic optionally sends a response frame (e.g., an ACK frame) to the AP / BS device 116.

[0050] At operation 1030, the processing logic determines whether the CFO estimate is greater than a threshold. In response to the CFO not being greater than the threshold, at operation 1035 the processing logic applies digital pre-correction to the generation of the protocol data unit frame (which occurs at operation 1050). In response to the trigger frame being received (operation 1015) and the CFO being greater than the threshold (operation 1030), the method 1000 continues with operation 1040.

[0051] At operation 1040, the processing logic calculates an RF PLL frequency using the CFO estimate after trigger frame reception and content validation at a medium access control level, the latter having been described with reference to Fig. 5 discussed in detail.

[0052] At operation 1045, based on the CFO estimate, the processing logic triggers a trim of the RF PLL (or Tx LO) to adjust the first carrier frequency of the wireless transmission device to match the second carrier frequency of the AP / BS device 116 within a threshold tolerance. In some embodiments, just before performing operation 1045, the processing logic stores a default phase-locked loop (PLL) frequency (or default LO frequency) for the Tx LO so that the default PLL frequency (or default LO frequency) can be restored later at operation 1055. Furthermore, triggering the trim of the RF PLL (or Tx LO) can be performed in sufficient time for the Tx LO to settle, before an end of the SIFS time period 555.

[0053] At operation 1050, the processing logic transmits a protocol data unit frame (e.g., the TB-PPDU frame) to the access point (e.g., AP / BS device 116) using either the digital pre-correction or the trimmed first LO. In embodiments, the protocol data unit frame is associated with the multi-user transmission mode.

[0054] At operation 1055, the processing logic restores the RF PLL frequency, e.g., a default frequency or the frequency used prior to the Tx LO trim, thereby enabling, e.g., operation in a default state of the RF circuitry before repeating the method 1000, e.g., in response to receiving another trigger frame at operation 1015.

[0055] Fig. 11 is a block diagram of a wireless device 1100 that performs LO trim pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction according to various embodiments. In an extension of the embodiments of Fig. 8, the wireless device 1100 employs pre-correction at the CFO, performed both through LO trimming for coarse correction and digitally for fine correction, enabling a wider range of potential frequency modifications to meet the stringent standard levels for EVM, UTE, and CFO. For example, this coarse / fine pre-correction approach can be implemented when the radio unit's PLL accuracy is insufficient to meet the specification of the standard requirements.

[0056] With reference to Fig. 11, the wireless device 1100 includes hardware 1114 that includes precorrection logic 1110 coupled between the Rx processing hardware 614A, the LO 630 (or RF PLL), and digital precorrection components also included in the hardware 1114. In at least some embodiments, the precorrection logic 1110 is configured to determine that the LO trim (calculated according to Fig. 8-10) is insufficient to satisfy a target residual frequency offset value when transmitted to the AP / BS device 116. In embodiments, the pre-correction logic 1110 calculates a digital pre-correction offset required to calculate the target residual frequency offset value and digitally upconverts a waveform using the pre-correction offset, thus driving the digital processing of the protocol data unit frame.

[0057] In particular, in at least some embodiments, the digital precorrection components include a waveform generator 1115 to generate a digital frame (e.g., TB-PPDU), a digital upconverter 1116, and a digital resampler 1117 coupled together in a chain, the latter being coupled to the DAC 822. In these embodiments, the precorrection logic 1110 is configured to determine a coarse LO trim value (f coarse) that precorrect logic 1110 uses to adjust (trim) the LO 630 or RF PLL. Since this coarse trim may not be sufficient to meet the strict carrier breakdown requirement of the IEEE standard, precorrect logic 1110 may be configured to determine a set of digital parameters with which to update the digital upconversion of digital upconverter 1116 and / or the resampling of digital resampler 1117. In this manner, precorrect logic 1110 may trigger the digital precorrect components in further fine digital precorrection affecting the signal transmitted by DAC 822 for inclusion in the protocol data unit frame transmitted by radio unit 1120.

[0058] Fig. 12 is a block diagram of a method 1200 for performing LO trim pre-correction for coarse carrier frequency correction and digital pre-correction for fine carrier frequency correction according to various embodiments. The method 1200 may be performed by processing logic that may include hardware (e.g., 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, the method 1200 is performed by control logic and / or hardware, e.g., the pre-correction logic 1110 of Fig. 11. In some embodiments, method 1200 refers to Rx processing within this control logic and / or hardware performed prior to performing Tx processing of Tx frames. Although shown in a particular sequence or order, unless otherwise specified, the order of the processes may be modified. The illustrated embodiments should be understood as examples only, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, one or more processes may be omitted in various embodiments. Therefore, not all processes are required in every embodiment. Other process flows are possible.

[0059] At operation 1205, the processing logic will determine whether receiving a frame in a modulated signal has ended and continue waiting until it is verified that a modulated signal has been completely received. The frame may or may not be a trigger frame.

[0060] At operation 1210, the processing logic determines whether a frame sequence check (FCS) was passed on the received modulated signal. An FCS can be understood as an error detection code added to a frame in a communications protocol. Frames are used to send payload data from a source to a destination. If the FCS was not passed, the method 1200 ends; otherwise, if the FCS was passed, the method 1200 continues with operation 1215.

[0061] At operation 1215, the processing logic determines whether a trigger frame was received from the access point, e.g., AP / BS device 116. If no trigger frame was received at operation 1220, the processing logic processes an Rx frame, e.g., because the received frame is not the trigger frame. At operation 1225, the processing logic optionally sends a response frame (e.g., an ACK frame) to the AP / BS device 116.

[0062] At operation 1230, in response to determining that a trigger frame was received, the processing logic estimates a coarse frequency to compensate for the CFO estimate and estimates a fine frequency to further compensate for the CFO estimate.

[0063] At operation 1235, the processing logic calculates an RF PLL frequency using the coarse frequency estimate and digital pre-correction parameters using the fine frequency estimate after trigger frame reception and content validation at a medium access control level, the latter having been described with reference to Fig. 5 discussed in detail.

[0064] At operation 1240, based on the coarse frequency estimate, the processing logic triggers a trim of the RF PLL (or Tx LO) to adjust the first carrier frequency of the wireless transmission device to match the second carrier frequency of the AP / BS device 116 within a first threshold tolerance. Also at operation 1240, the processing logic programs the digital precorrection parameters into the digital precorrection components to digitally fine-tune the transmitted frame frequency associated with the fine frequency estimate. In some embodiments, just before performing operation 1240, the processing logic stores a default PLL frequency (or LO frequency) for the Tx LO so that the default PLL frequency (or LO frequency) can be restored later at operation 1250.Furthermore, the triggering of the trim of the RF-PLL (or Tx-LO) can be performed in sufficient time for the Tx-LO to settle, before the end of the SIFS time period 555.

[0065] At operation 1245, the processing logic transmits a protocol data unit frame (e.g., the TB-PPDU frame) to the access point (e.g., the AP / BS device 116) using the trimmed first LO using a coarse estimate and the digital pre-correction using a fine estimate. In embodiments, the protocol data unit frame is associated with the multi-user transmission mode.

[0066] At operation 1250, the processing logic restores the RF PLL frequency, e.g., a default frequency or the frequency used before Tx LO trimming and digital pre-correction, thereby enabling, e.g., operation in a default state of the RF circuitry before repeating the method 1200, e.g., in response to receiving another trigger frame at operation 1215.

[0067] Fig. 13 is a timing diagram 1300 illustrating how, according to at least some embodiments, a trigger-based LO trim pre-correction may be implemented within the SIFS time, but wherein the LO trim-based frequency calculation is performed after the preamble processing. As a modification of the diagram 500 of Fig. 5, calculating the LO trim value at a much earlier time, during reception (Rx) of the trigger frame 210, helps to improve the timing of the pre-correction for the CFO estimation, e.g., it allows a longer settling time for the LO after triggering the LO trim calculation 540. Thus, in the embodiment of Fig. 13, the control logic of a wireless device calculates the LO trim value at time 1340 based on a fine frequency estimate of the CFO available after preamble processing of the trigger frame. As illustrated, the LO trim calculation 540 is removed from the LO settling period 555 because the LO trim value is calculated much earlier, thereby allowing the LO trim 550 to be shifted to an earlier time during the SIFS time period 515.

[0068] Fig. 14 is a flow diagram of an example method 1400 for performing LO trim pre-correction within the SIFS time, according to at least some embodiments, wherein the LO trim-based frequency calculation is performed after preamble processing. The method 1400 may be performed by processing logic that may include hardware (e.g., 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, the method 1400 is performed by control logic and / or hardware of one of the wireless devices 600, 700, and / or 800 ( Fig.6-8). In some embodiments, method 1400 refers to Rx processing within this control logic and / or hardware performed prior to performing Tx processing of Tx frames. Although shown in a particular sequence or order, unless otherwise specified, the order of the processes may be modified. The illustrated embodiments should be understood as examples only, and the illustrated processes may be performed in a different order, and some processes may be performed in parallel. Additionally, one or more processes may be omitted in various embodiments. Therefore, not all processes are required in every embodiment. Other process flows are possible.

[0069] At operation 1405, the processing logic detects that a preamble of a frame received from an access point (e.g., AP / BS device 116) has been processed, where the access point is operating in a multi-user transmission mode. Operation 1405 may be performed for each frame received from the access point to detect CFO-related information as early as possible, but if, for example, it is later determined not to be a trigger frame, method 1400 may restart.

[0070] At operation 1410, based on information obtained from the trigger frame after preamble processing, the processing logic estimates a carrier frequency offset (CFO) between a first carrier frequency of the first LO and a second carrier frequency of a second LO of the access point. Also at operation 1410, the processing logic calculates (or otherwise determines) an LO trim value (or RF PLL trim value) using the CFO estimate. In some embodiments, determining the LO trim value includes estimating a shift in the first carrier frequency required so that the first carrier frequency matches the second carrier frequency within a threshold tolerance.

[0071] At operation 1415, the processing logic will determine whether receiving the trigger frame has ended in a modulated signal and continue to wait until verifying that a modulated signal has been fully received.

[0072] At operation 1420, the processing logic determines whether a frame sequence check (FCS) was passed on the received modulated signal. An FCS can be understood as an error detection code added to a frame in a communications protocol. Frames are used to send payload data from a source to a destination. If the FCS was not passed, the method 1400 ends; otherwise, if the FCS was passed, the method 1400 continues with operation 1425.

[0073] At operation 1425, the processing logic determines whether a trigger frame was received from the access point, e.g., the AP / BS device 116. For example, whether the frame processed with reference to operation 1405 was actually a trigger frame. If no trigger frame was received at operation 1430, the processing logic processes an Rx frame, e.g., because the received frame is not the trigger frame. At operation 1435, the processing logic optionally sends a response frame (e.g., an ACK frame) to the AP / BS device 116.

[0074] At operation 1440, the processing logic, using the LO trim value, triggers a trim of the RF PLL (or Tx LO) to adjust the first carrier frequency of the wireless transmission device to match the second carrier frequency of the AP / BS device 116 within a threshold tolerance.

[0075] At operation 1445, the processing logic transmits a protocol data unit frame (e.g., the TB-PPDU frame) to the access point (e.g., AP / BS device 116) using the trimmed first LO. In embodiments, the protocol data unit frame is associated with the multi-user transmission mode.

[0076] At operation 1450, the processing logic restores the RF PLL frequency, e.g., a default frequency or the frequency used prior to the Tx LO trim, thereby enabling, e.g., operation in a default state of the RF circuitry before repeating the method 1400, e.g., in response to receiving another trigger frame. For example, the method 1400 may further include continuously adjusting the LO trim value of the first LO on a per-frame basis in response to detecting changes in the CFO during transmission of multiple uplink protocol data unit frames to one or more access points.

[0077] It will be apparent to one 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 format so as not to unnecessarily obscure the subject matter described herein. The specific details set forth below are therefore merely exemplary. Specific implementations may vary from these exemplary details while still being within the spirit and scope of the present embodiments.

[0078] References in the specification to "one embodiment," "a single embodiment," "an exemplary embodiment," "some embodiments," and "various embodiments" mean that a particular function, structure, step, operation, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the invention. Furthermore, the appearances of the phrases "one embodiment," "a single embodiment," "an exemplary embodiment," "some embodiments," and "various embodiments" in various places throughout the specification are not necessarily all referring to the same embodiment(s).

[0079] The description includes references to the accompanying drawings, which form part of the detailed description. The drawings show illustrations in accordance with exemplary embodiments. These embodiments, which may also be referred to herein as "examples," are described in sufficient detail to enable those 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 is to be understood that the embodiments described herein are not intended to limit the scope of the claimed subject matter, but rather to enable one skilled in the art to practice, make, and / or use the claimed subject matter.

[0080] The description includes references to the accompanying drawings, which form part of the detailed description. The drawings show illustrations in accordance with exemplary embodiments. These embodiments, which may also be referred to herein as "examples," are described in sufficient detail to enable those 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 is to be understood that the embodiments described herein are not intended to limit the scope of the claimed subject matter, but rather to enable one skilled in the art to practice, make, and / or use the claimed subject matter.

[0081] Certain embodiments may be implemented as firmware instructions stored on a non-transitory computer-readable medium, such as, for example, volatile memory and / or non-volatile storage. These instructions may be used to program and / or configure one or more devices including one or more processors (e.g., CPUs) or equivalents thereof (such as, for example, processing cores, processing engines, microcontrollers, and the like) such that, when executed by the processor(s) or equivalents thereof, the instructions cause the device(s) to perform the operations described herein for USB-C / PD mode transition architecture. The non-transitory computer-readable storage medium may include, but is not limited to, an electromagnetic storage medium, read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g.,EPROM and EEPROM), flash memory or any other non-transitory type of medium now known or later developed which is suitable for storing information.

[0082] Although the operations of the circuit(s) and block(s) are shown and described herein in a particular order, in some embodiments, the order of operations of each circuit / block may be changed so that certain operations may be performed in a reverse order or certain operations may be performed, at least in part, concurrently and / or in parallel with other operations. In other embodiments, instructions or sub-operations of separate operations may be performed in an intermittent and / or alternating manner.

[0083] In the foregoing specification, the disclosure has been described with reference to specific 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 disclosure as described in the appended claims. Accordingly, the specification and drawings are to be considered as illustrative and not restrictive.

Claims

[1] A wireless device that includes: a radio unit including a front end and a first local oscillator (LO); and Control logic coupled to the radio unit, the control logic serving to: Determining, from a received trigger frame, a carrier frequency offset (CFO) between a first carrier frequency of the first LO and a second carrier frequency of a second LO of an access point operating in a multi-user transmission mode; and Trigger, based on the CFO, a LO trim of the first LO to adjust the first carrier frequency so that it, within a Threshold tolerance, matches the second carrier frequency; and wherein the radio unit transmits a protocol data unit frame to the access point using the trimmed first LO, the protocol data unit frame being associated with the multi-user transmission mode. [2] The wireless device of claim 1, wherein the control logic is implemented in at least one of a microcontroller or hardware, and wherein the control logic will continuously trigger the LO trim of the first LO on a per-frame basis in response to detecting changes in the CFO during transmission of a plurality of protocol data unit frames to one or more access points. [3] The wireless device of claim 1, wherein the control logic further serves to: Calculating an LO trim value based on the CFO after trigger frame reception and content validation at a medium access control level; Storing a default phase-locked loop (PLL) frequency for the first LO; and triggering the LO trim of the first LO in sufficient time for the first LO to settle before an end of a short interface space (SIFS) time period. [4] The wireless device of claim 1, wherein the radio unit further includes a radio frequency (RF) phase locked loop (PLL) comprising the first LO, and wherein the control logic is further to: Calculate an updated RF-PLL frequency based on the CFO; Triggering the RF-PLL to operate at the updated RF-PLL frequency in response to the LO trim; and after transmitting the protocol data unit frame, causing the RF-PLL to operate at a standard RF-PLL frequency. [5] The wireless device of claim 1, wherein the radio unit further includes a radio frequency (RF) phase locked loop (PLL) comprising the first LO, and wherein the control logic further serves to: Determine whether the CFO is greater than a threshold; in response to the CFO not being larger than the threshold, applying a digital pre-correction to the protocol data unit frame; and in response to the CFO being greater than the threshold: Calculating an updated RF PLL frequency based on the CFO; and triggering the RF PLL to operate at the updated RF PLL frequency in response to the LO trim. [6] The wireless device of claim 1, wherein the control logic further serves to: Determining that the LO trim is insufficient to satisfy a target residual frequency offset value when transmitted to the access point; Calculating a digital pre-correction offset required to meet the target residual frequency offset value; and Performing a digital upconversion, using the pre-correction offset, of a waveform, thereby driving the digital processing of the protocol data unit frame. [7] The wireless device of claim 1, wherein the control logic is configured to adjust the first carrier frequency of the first LO to within a few hertz of a target frequency associated with the second carrier frequency. [8] Wireless device that includes: a radio unit that includes: a radio frequency phase-locked loop (RF-PLL); an analog-to-digital converter (ADC) coupled to a demodulator driven by the RF PLL; a digital-to-analog converter (DAC) coupled to a modulator driven by the RF PLL; and an analog front-end PLL to generate a clock to drive the ADC and DAC; and Trim logic coupled to the RF PLL and the analog front-end PLL, where the trim logic serves the following: Determining, from a received trigger frame, a carrier frequency offset (CFO) between a first carrier frequency of the RF-PLL and a second carrier frequency of a local oscillator (LO) of an access point operating in a multi-user transmission mode; Triggering, based on the CFO, a first trim of the RF-PLL to adjust the first carrier frequency to match the second carrier frequency within a threshold tolerance; and Triggering, based on the CFO, a second trim of the analog Front-end PLL to assist in meeting the threshold tolerance; and wherein the radio unit transmits a protocol data unit frame to the access point using the trimmed RF PLL. [9] A wireless device according to claim 8, further comprising: Receive (Rx) processing hardware coupled to the ADC and trimming logic; and Transmit (Tx) processing hardware coupled to the DAC. [10] The wireless device of claim 8, wherein the trimming logic will continuously trigger the first trim of the RF PLL and the second trim of the analog front-end PLL in response to detecting changes in the carrier frequency offset during transmission of a plurality of protocol data unit frames to the access point. [11] The wireless device of claim 8, wherein the trimming logic further serves to: Calculating an LO trim value based on the CFO after trigger frame reception and content validation at a medium access control level; Storing a standard phase-locked loop (PLL) frequency for the RF-PLL; and Triggering the first trim of the RF-PLL in sufficient time for the RF-PLL to settle before the end of a short interface space (SIFS) time period. [12] The wireless device of claim 8, wherein the trimming logic further serves to: Calculate an updated RF-PLL frequency based on the CFO; Triggering the RF-PLL to operate at the updated RF-PLL frequency in response to the first RF-PLL trim; and after transmitting the protocol data unit frame, causing the RF-PLL to operate at a standard RF-PLL frequency. [13] The wireless device of claim 8, wherein the trimming logic further serves to: Determine whether the CFO is greater than a threshold; in response to the CFO not being larger than the threshold, Applying digital pre-correction to generate the protocol data unit frame; and in response to the CFO being greater than the threshold: Calculating an updated RF-PLL frequency based on the carrier frequency offset; and Triggering the RF-PLL to operate at the updated RF-PLL frequency in response to the first RF-PLL. [14] The wireless device of claim 8, wherein the trimming logic further serves to: Determine that the first trim and the second trim are insufficient, to meet a target residual frequency offset value when transmitted to the access point; Calculating a digital pre-correction offset required to meet the target residual frequency offset value; and Performing a digital upconversion, using the pre-correction offset, of a waveform, thereby driving the digital processing of the protocol data unit frame. [15] Procedure which includes: Detecting, by control logic coupled to a radio unit having a first local oscillator (LO), that a preamble of a trigger frame received from an access point has been processed, wherein the access point operates in a multi-user transmission mode; Estimating, based on information obtained from the trigger frame after preamble processing, a carrier frequency offset (CFO) between a first carrier frequency of the first LO and a second carrier frequency of a second LO of the access point; Determining an LO trim value based on the CFO; and Causing, by the control logic, an adjustment using the LO trim value at the first carrier frequency of the first LO before the radio unit transmits an uplink protocol data unit frame to the access point. [16] The method of claim 15, further comprising continuously adjusting the LO trim value of the first LO on a per-frame basis in response to detecting changes in the CFO during transmission of a plurality of uplink protocol data unit frames to one or more access points. [17] The method of claim 15, wherein determining the LO trim value includes estimating a shift in the first carrier frequency required so that the first carrier frequency matches the second carrier frequency within a threshold tolerance. [18] A method according to claim 15, further comprising, prior to initiating the adjustment: Determining that a frame sequence check has been passed; Receiving a trigger frame from the access point; and Perform content validation of the trigger frame. [19] A method according to claim 15, further comprising: Storing, before initiating the adjustment, a standard phase-locked loop (PLL) frequency for the first LO; and Triggering an LO trim of the first LO in sufficient time for the first LO to settle before the end of a short interface space (SIFS) time period. [20] A method according to claim 15, further comprising: after initiating the adjustment, causing the radio unit to transmit the uplink protocol data unit frame to the access point; and after transmitting the uplink protocol data unit frame, restoring a default phase-locked loop (PLL) frequency for the first LO.