Channel training adaptation

Abstract

The present disclosure relates to channel training adaptation. A method is disclosed that may include detecting parameters of a communication between an AP and a STA. The method may include determining a training configuration for channel estimation for the communication based on the parameters. The method may include transmitting a DL transmission or a trigger frame to the STA. The DL transmission may include a training block configured according to the training configuration. The trigger frame may include the training configuration and an instruction to the STA to include the training block configured according to the training configuration in an UL transmission to the AP. The STA may be configured to use the training block of the DL transmission received at the STA to determine the channel estimate of the channel of the communication. Alternatively, the method may also include using the training block of the UL transmission received at the AP to determine the channel estimate of the channel of the communication.

Description

Technical Field

[0001] The embodiments discussed in this disclosure relate to channel training adaptation. Background Art

[0002] Unless otherwise indicated in this disclosure, materials described in this disclosure are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

[0003] A wireless network (e.g., a wireless local area network (WLAN)) may include an access point (AP) and at least one wireless station (STA) communicating with each other via one or more channels. Communications between the AP and the STA may include training blocks for performing channel estimation. In some embodiments, channel estimation may be performed on the current channel. For example, a transmission from the AP to the STA on a particular channel may include training blocks used by the STA to perform channel estimation on the particular channel. The AP or STA may use the channel estimate to decode data also included in the transmission.

[0004] The subject matter claimed in this disclosure is not limited to implementations that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is merely provided to illustrate one example technology area in which some implementations described in this disclosure may be practiced. Summary of the Invention

[0005] In one embodiment, a method may include detecting one or more parameters of a communication between an AP and a STA. The method may include determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication. The method may include transmitting a downlink (DL) transmission to the STA. The DL transmission may include training blocks configured according to the training configuration. The STA may be configured to determine a channel estimate for the communication channel using the training blocks of the DL transmission received at the STA.

[0006] In another embodiment, a system may include an AP. The AP may be configured to detect one or more parameters of communication between the AP and a STA. The AP may be configured to determine a training configuration for channel estimation for the communication based on the one or more parameters of the communication. The AP may be configured to transmit a downlink transmission to the STA. The downlink transmission may include training blocks configured according to the training configuration. The STA may be configured to determine a channel estimate for the communication channel using the training blocks of the downlink transmission received at the STA.

[0007] In another embodiment, a method may include detecting one or more parameters of a communication between an AP and a STA. The method may include determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication. The method may include transmitting a trigger frame to the STA. The trigger frame may include a training configuration and instructions for the STA to include training blocks configured according to the training configuration in an uplink (UL) transmission to the AP. The method may include determining a channel estimate for a channel of the communication using the training blocks of the UL transmission received at the AP.

[0008] In another embodiment, a system may include an AP. The AP may be configured to detect one or more parameters of communication between the AP and a STA. The AP may be configured to determine a training configuration for channel estimation for the communication based on the one or more parameters of the communication. The AP may be configured to transmit a trigger frame to the STA. The trigger frame may include a training configuration and instructions for the STA to include a training block configured according to the training configuration in a UL transmission to the AP. The AP may be configured to determine a channel estimate for the communication channel using the training block of the UL transmission received at the AP. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Example implementations will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0010] Figure 1 shows an exemplary environment in which an AP may be implemented;

[0011] Figure 2 A flow chart illustrating an exemplary method for performing channel training adaptation is shown;

[0012] Figure 3 shows a graphical representation of a simulation of SNR versus packet error rate for a DL between an AP and two STAs with two communication streams or four communication streams using various numbers of training symbols and modulation schemes;

[0013] Figure 4A A flowchart illustrating an exemplary method for performing channel estimation is shown; and

[0014] Figure 4B A flow chart of another exemplary method for performing channel estimation is shown. DETAILED DESCRIPTION

[0015] A wireless network (e.g., a WLAN) may include an AP and at least one STA communicating with each other via one or more channels. In some embodiments, the AP and STA may communicate according to a high-efficiency (HE) long training field (LTF) format. For example, the AP and STA may communicate according to a HE single-user (SU) format, a HE extended-range SU format, a HE trigger-based (TB) format (e.g., STA-to-AP transmission), or a HE multi-user (MU) format (e.g., AP-to-STA transmission). In some embodiments, these transmissions may be transmitted via an uplink (UL) or DL within the wireless network. The UL may include a link from a STA to an AP, and the DL may include a link from an AP to a STA. In some embodiments, the UL may occur on a reverse channel, and the DL may occur on a forward channel within the wireless network. In some embodiments, each transmission in a communication between an AP and a STA may include a preamble (e.g., a legacy preamble), an HE preamble, and a data portion.

[0016] In some embodiments, the HE preamble may include a training block including training symbols. The AP or STA may use the training symbols as a receiver to determine a channel estimate for the current channel (e.g., forward channel or reverse channel) of the communication. In some embodiments, the AP or STA may use the training symbols to determine the characteristics of the channel. In addition, the AP or STA may use the channel estimate to decode the data portion of the transmission. In some embodiments, the accuracy of the channel estimate may affect the signal-to-noise ratio (SNR) or bit error rate (BER) of the communication. For example, if the accuracy of the channel estimate is low, the SNR may be low or the BER may be high, and some of the data portions may be incorrectly decoded. In some embodiments, the accuracy of the channel estimate may affect the link throughput of the communication on the channel.

[0017] In some channel training techniques, the number or length of training symbols in a training block may be constant. Additionally, in some channel training techniques, the AP or STA may inform the receiver whether precoding is being applied to the transmission. Furthermore, in some channel training techniques, one or more of the training symbols may be transmitted in unallocated resource blocks in the data portion of the transmission. These channel training techniques may not allow for adjustment (e.g., adaptation) of the number or length of training symbols to improve the performance of communications between the AP and STA.

[0018] Furthermore, these channel training techniques can make the overhead of a training block constant, even when a training block with less overhead could be used to determine the channel estimate. Furthermore, these channel training techniques can make the SNR low or the BER of a transmission high, even when the channel estimate could be improved by adjusting the number or length of training symbols in the training block. Furthermore, these channel training techniques can reduce the throughput of communications between the AP and STAs or increase the processing required to perform communications between the AP and STAs.

[0019] Some embodiments described in this disclosure may allow for adjusting the training block based on parameters of the communication between the AP and STA. According to embodiments described in this disclosure, the training block may be adjusted by adjusting the number or length of training symbols in the training block.

[0020] In at least one embodiment described in this disclosure, an AP may detect parameters of communications between the AP and a STA. In these and other embodiments, the AP may determine a training configuration for channel estimation for the communications based on the parameters of the communications. In some embodiments, the training configuration may indicate that the number or length of training symbols will be adjusted relative to previous transmissions between the AP and the STA.

[0021] In these and other embodiments, the AP may transmit a DL transmission or a trigger frame to the STA. When transmitted, the DL transmission may include training blocks configured according to the training configuration. When transmitted, the trigger frame may include the training configuration and instructions for the STA to include the training blocks configured according to the training configuration in its UL transmission to the AP. A training block for a DL transmission or UL transmission may include adjusted symbols according to the training configuration (e.g., a training block with a different number of symbols and / or a different length than previously). Thus, the AP may determine the DL or UL training configuration. In some embodiments, the AP may determine a channel estimate based on the training blocks in the UL transmission. In other embodiments, the STA may determine a channel estimate based on the training blocks in the DL transmission.

[0022] Therefore, at least one embodiment described in this disclosure can improve the throughput of communications between an AP and a STA. For example, a training configuration can indicate that the length of training symbols will be reduced, which can result in reduced training block overhead. Furthermore, at least one embodiment described in this disclosure can improve the data rate of communications between an AP and a STA by increasing the signal-to-noise ratio (SNR) or reducing the frame-to-noise ratio (BER). For example, a training configuration can indicate that the number of training symbols will be increased to improve noise averaging across the training symbols, thereby reducing transmitted noise and, therefore, increasing the signal-to-noise ratio (SNR).

[0023] These and other embodiments of the present disclosure will be explained with reference to the accompanying drawings. It will be understood that the drawings are diagrammatic and schematic representations of these exemplary embodiments and are not limiting, nor are they necessarily drawn to scale. In the drawings, features with the same number indicate the same structure and function, unless otherwise described.

[0024] Figure 1 An exemplary environment 100 is shown in which an AP 102 may be implemented. The environment 100 may also include a STA 104. The AP 102 and the STA 104 may form a wireless network 101. Figure 1 The circle of wireless network 101 is shown for reference only and may, but does not necessarily, represent the actual coverage area of wireless network 101 .

[0025] In some embodiments, the AP 102 may provide the STA 104 with access to the Internet. Examples of the STA 104 may include a personal computer, a printer, a television, a digital video disc (DVD) player, a security camera, a smartphone, a tablet, a smart device, or any other suitable computing device configured for wireless communication. In these and other embodiments, the AP 102 may implement the IEEE 802.11 standard, which is a contention-based standard for handling communications between multiple competing devices sharing a wireless communication medium on a selected one of a plurality of communication channels. The frequency range of each communication channel is specified in the corresponding protocol of the implemented IEEE 802.11 protocol, such as "a", "b", "g", "n", "ac", "ad", "ax".

[0026] In some embodiments, the AP 102 may detect parameters of the communication between the AP 102 and the STA 104. In these and other embodiments, the parameters of the communication may include the channel frequency selectivity of the channel, the length of the packet in the transmission or the air time of the transmission, the precoding or beamforming of the transmission, the SNR of the transmission, or the success rate of previous transmissions between the AP 102 and the STA 104. In addition, the AP 102 may determine a training configuration based on the parameters of the communication. The training configuration may be determined as a channel estimate for the communication between the AP 102 and the STA 104.

[0027] In some embodiments, the training configuration may indicate the length of the training symbols in the training block. For example, the training configuration may indicate that the length of the training symbols is 3.2 microseconds (μs) (e.g., 1x length or regular length), 6.4 μs (e.g., 2x length), or 12.8 μs (e.g., 4x length). In these and other embodiments, the training configuration may indicate that the length of the training symbols is to be adjusted relative to previous transmissions between the AP 102 and the STA 104. In some embodiments, setting or adjusting the length of the training symbols to 3.2 μs may reduce the air time overhead of the training block. In other embodiments, setting or adjusting the length of the training symbols to 12.8 μs may improve channel estimation performance for frequency selective channels.

[0028] In some embodiments, the training configuration may indicate the number of training symbols to be included in a training block. For example, the training configuration may indicate that the number of training symbols to be included in a training block is two, four, six, or eight, which may be more, less, or the same number of training symbols included in a previous transmission. In these and other embodiments, each training symbol may contribute to the overall length (e.g., air time) of the training block, where the overall length may be equal to the number of training symbols multiplied by the length per symbol. The overall length may be greater, less, or the same as in the previous transmission. For example, if the number of training symbols is increased from two to four, and the length of the training symbols remains at 6.4 μs, the overall length of the training block may increase from 12.8 μs to 25.6 μs.

[0029] In some embodiments, the AP 102 may generate a training block to include a determined number and length of training symbols according to a training configuration (e.g., as specified by the training configuration) in a DL transmission from the AP 102 to the STA 104. In other embodiments, the AP 102 may generate a trigger frame that includes an instruction to the STA 104 to include a training block having a determined number and length of training symbols (e.g., the training configuration) in a UL transmission from the STA 104 to the AP 102.

[0030] In some embodiments, AP 102 may transmit a DL transmission to STA 104. In these and other embodiments, the DL transmission may include training blocks configured according to a training configuration. For example, the number and / or length of training symbols in a training block may be specified in the training configuration. Thus, the training blocks in the DL transmission may be generated according to the training configuration.

[0031] In other embodiments, the training configuration may be included in the trigger frame along with the instructions provided to the STA 104. In this and other embodiments, the STA 104 may generate training blocks for UL transmissions according to the training configuration received in the trigger frame.

[0032] In some embodiments where the DL transmission includes the generated training blocks, the AP 102 may transmit the DL transmission having the training blocks and a data portion (e.g., payload) to the STA 104. The STA 104 may perform channel estimation of the communication channel based on the training blocks in the DL transmission. Additionally, the STA 104 may decode the data portion of the DL transmission based on the channel estimate.

[0033] In some embodiments, AP 102 may instead send a TB transmission (e.g., a transmission for triggering a response transmission from STA 104) or other trigger frame to STA 104. In these and other embodiments, the trigger frame may include a training configuration and instructions to STA 104 to include a training block configured according to the training configuration in one or more UL transmissions to the AP. In addition, STA 104 may generate a training block for the UL transmission according to the training configuration in the trigger frame received from AP 102. STA 104 may transmit the UL transmission having the training block and a data portion to AP 102. AP 102 may perform channel estimation of the communication channel based on the training block in the UL transmission. In addition, AP 102 may decode the data portion of the UL transmission based on the channel estimate.

[0034] Communication parameters, including the frequency selectivity of a channel, will now be discussed. In some embodiments, AP 102 may determine that a communication channel with STA 104 is a flat fading channel. In these and other embodiments, AP 102 may determine that a channel is a flat fading channel by determining whether the coherence bandwidth of the channel is greater than the bandwidth of the corresponding transmission. In some embodiments, a flat fading channel may make AP 102 or STA 104 more susceptible to interference caused by transmissions on adjacent channels.

[0035] If the channel is flat fading, the training configuration may be determined to, for example, reduce the length of the training symbols in the training block compared to the length of the training symbols in the training block sent in the previous transmission. In many of the examples that follow, only one exemplary pairing of input parameters (e.g., communication parameters) and output parameters (e.g., training configuration adjustments) is discussed. Where the AP 102 determines opposing input parameters, the training configuration may be determined to have output parameters that move in opposite directions. For example, if the channel is determined to be frequency selective rather than flat fading, the training configuration may be determined to increase rather than decrease the length of the training symbols in the training block.

[0036] In some embodiments, reducing the length of the training symbols compared to the length in the previous transmission can improve the performance of channel estimation for flat fading channels. For example, the training configuration can be determined to reduce the length of the training symbols to 3.2 μs or 6.4 μs. In some embodiments, the AP 102 can generate a DL transmission to include training blocks according to the training configuration, and specifically include training blocks with reduced length training symbols. Alternatively, in some embodiments, the AP 102 can generate a trigger frame that includes the training configuration with instructions to the STA 104 to include training blocks according to the training configuration (e.g., with reduced length training symbols) in the UL transmission.

[0037] Communication parameters, including the length of packets in the data portion of transmissions between AP 102 and STA 104, will now be discussed. In some embodiments, AP 102 may detect the length of packets in the data portion of transmissions between AP 102 and STA 104. In these and other embodiments, the length of packets in the data portion may be determined for packets previously transmitted between AP 102 and STA 104 (e.g., in a previous DL transmission or UL transmission). For example, AP 102 may detect the length of packets in the data portion previously received in one or more previous UL transmissions from STA 104 or previously sent in one or more previous DL transmissions. In other embodiments, the length of packets in the data portion may be determined for packets to be transmitted in the data portion of a DL transmission of a training block configured according to a training configuration or in the UL transmission of a training block configured according to a training configuration. For example, AP 102 may detect the length of packets in the data portion of a DL transmission.

[0038] In some embodiments, if the length of the data portion of a packet is less than a packet length threshold, the training configuration may be determined to reduce the length of the training symbols in the training block. Additionally or alternatively, if the length of the data portion of a packet is less than the packet length threshold, the training configuration may be determined to reduce the number of training symbols in the training block. In one exemplary embodiment, the packet length threshold may be 90% of the total packet length. For example, assuming a packet length of 300 microseconds, in this case, in this example, the packet length threshold may be 270 microseconds. If a training block includes a total length of 102.4 microseconds (e.g., 8 training symbols multiplied by 12.8 microseconds per symbol), the length of the data portion of the packet may be 197.6 microseconds, which is less than the 270 microsecond packet length threshold. Therefore, in this example, the training configuration may be determined to reduce the length of the training block, for example, by reducing the length of each training symbol and / or by reducing the total number of training symbols in the training block. On the other hand, if the training block includes a total length of 12.8 microseconds (e.g., 4 training symbols multiplied by 3.2 microseconds / symbol), the length of the data portion of the packet may be 287.2 microseconds, which is greater than the 270 microsecond packet length threshold. Therefore, the training configuration may be determined to maintain the length of the training block as shown in this example or even increase the length of the training block, for example, by increasing the length of each training symbol and / or by increasing the total number of training symbols in the training block.

[0039] In some embodiments, the training configuration may be determined to reduce the number or length of training symbols in a training block. Reducing the number or length of training symbols may reduce the air time of the training block or the total air time of a DL transmission or UL transmission. In these and other embodiments, the AP 102 may generate a DL transmission to include training blocks according to the training configuration, e.g., where the training blocks have a reduced number of training symbols and / or reduced length training symbols. Alternatively, in some embodiments, the AP 102 may generate a trigger frame to include the training configuration with instructions to the STA 104 to include the training blocks according to the training configuration in the UL transmission.

[0040] The parameters of communication will now be discussed, including the air time of transmissions between AP 102 and STA 104. In some embodiments, AP 102 may detect the air time of a previous transmission or a current transmission between AP 102 and STA 104. In some embodiments, the air time may correspond to the amount of time that elapsed during a single transmission between AP 102 and STA 104. For example, AP 102 may use a timestamp to determine the amount of time between the initiation and receipt of a transmission. In other embodiments, the air time may correspond to the TB transmission plus the response transmission between AP 102 and STA 104. For example, the air time may be equal to the amount of time that elapsed between AP 102 transmitting a TB transmission or other triggering frame and AP 102 receiving a response transmission from STA 104.

[0041] In some embodiments, AP 102 may determine the distance between AP 102 and STA 104 based on air time. In these and other embodiments, if the distance is greater than a distance threshold, the training configuration may be determined to increase the number of training symbols in the training block. The distance threshold may be near the end of the range of AP 102, where the link with STA 104 is very weak, such that increasing the number of training symbols may provide a gain in channel estimation and further aid decoding. For example, the distance threshold may be approximately 80%, 85%, 90%, or 95% of the end of the range of AP 102. The end of the range of AP 102 may be inferred based on the received signal strength indicator (RSSI), the MCS determined by the rate control, or other historical information about the link. In cases where RSSI is used as a range indicator (e.g., end of range), the distance threshold may be 6 decibels (dB) higher than the minimum supported RSSI. If MCS is used as a range indicator, a lower MCS of 1 or 2 may be used as the distance threshold as the number of training samples increases.

[0042] In these and other embodiments, the AP 102 may generate a DL transmission to include training blocks according to a training configuration (e.g., with an increased number of training symbols). Alternatively, in some embodiments, the AP 102 may provide a training configuration for UL transmissions from a STA or other STAs by including the training configuration in a trigger frame sent on the downlink by the AP 102. The STA 104 may use these parameters (e.g., the training configuration) to generate training blocks in an uplink response packet (generally referred to herein as an UL transmission).

[0043] The parameters of the communication will now be discussed, including precoding for transmissions between the AP 102 and the STA 104. In some embodiments, the AP 102 may detect the precoding or beamforming selection for transmissions between the AP 102 and the STA 104. For example, the AP 102 may determine DL-MU precoding for DL transmissions, in which case the STA 104 may or may not use various receiver techniques to improve channel estimation for the DL transmissions received from the AP 102.

[0044] In some embodiments, the training configuration may be determined to increase the number of training symbols in a training block based on the precoding of the transmission. In these and other embodiments, increasing the number of training symbols in a training block may reduce noise in a DL transmission or an UL transmission by averaging the noise for each training symbol over the increased number of training symbols rather than over fewer training symbols included in a previous transmission. Additionally, in some embodiments, the AP 102 may generate a DL transmission to include training blocks according to the training configuration (e.g., with an increased number of training symbols). Alternatively, in some embodiments, the AP 102 may generate a trigger frame to include a training configuration with instructions to the STA 104 to include the increased number of training symbols in a training block of an UL transmission.

[0045] The parameters of communications, including parameters of previous transmissions between the AP 102 and the STA 104, will now be discussed. In some embodiments, the AP 102 may detect parameters of previous transmissions between the AP 102 and the STA 104. The parameters may include the number or length of training symbols in a previously transmitted training block. In these and other embodiments, the AP 102 may use different parameters to determine the success rate of the previous transmission. For example, the AP 102 may determine the success rate of transmissions between the AP 102 and the STA 104 that included two training symbols in a training block.

[0046] In some embodiments, if the success rate of a previous transmission is below a success threshold, the training configuration may be determined to indicate that the number or length of training symbols in a training block will be adjusted. For example, if the success rate is below the success threshold and the number of training symbols in the previous transmission was six and the length was 6.4 μs, the training configuration may be determined to indicate that the length of the training symbols will be increased to 12.8 μs, and the number of training symbols will remain at six. For another example, if the success rate is below the success threshold and the number of training symbols in the previous transmission was two and the length was 3.2 μs, the training configuration may be determined to indicate that the length of the training symbols will be increased to 6.4 μs, and the number of training symbols will be increased to four. The success rate may include a ratio of the number of correctly decoded packets to the total number of packets transmitted, and the success threshold may include a 90% success rate or some other value.

[0047] Alternatively, embodiments described herein may consider a failure rate (rather than a success rate) such as a packet error rate (PER), and a failure threshold (e.g., a PER of 10% or some other value). In this example, the length of the training symbols or the number of training symbols may be determined to increase in response to the failure rate being greater than the failure threshold in the training configuration.

[0048] In some embodiments, the AP 102 may generate a DL transmission to include training blocks according to a training configuration with an increased number of training symbols or with increased lengths. Alternatively, in some embodiments, the AP 102 may generate a trigger frame to include a training configuration with instructions to the STA 104 to include an increased number of training symbols or with increased lengths in the training blocks of the UL transmission.

[0049] The parameters of the communication will now be discussed, including the SNR of previous transmissions between the AP 102 and the STA 104. In some embodiments, the AP 102 may detect the UL or DL SNR between the AP 102 and the STA 104. In these and other embodiments, if the UL or DL SNR is less than an SNR threshold, the training configuration may be configured to increase the number of training symbols in the training block of the corresponding UL transmission or DL transmission. The SNR threshold may be 3 dB or some other value. In these and other embodiments, the AP 102 may generate a DL transmission to include a training block with an increased number of training symbols according to the training configuration. Alternatively, in some embodiments, the AP 102 may generate a trigger frame to include a training configuration with an instruction to the STA 104 to include an increased number of training symbols in the training block of the UL transmission.

[0050] In some embodiments, the number of training symbols in a training block of a DL transmission or an UL transmission may always be equal to or greater than the number of flows (e.g., connections between the AP 102 and STAs within the wireless network 101). For example, the wireless network 101 may include a second STA and a third STA ( Figure 1 (not shown), and the number of training symbols may always be equal to or greater than three. Furthermore, the embodiments described in the present disclosure may be implemented in the media access control (MAC) layer or the physical (PHY) layer of the AP 102. Furthermore, the number or length of training symbols in a training block may be determined based on a combination of two or more of the above examples. For example, the number or length of training symbols may be determined based on any combination of channel frequency selectivity of the channel, the length of packets in the data portion of the transmission, the air time of the transmission, the precoding of the transmission, and parameters of previous transmissions between the AP 102 and the STA 104.

[0051] Figure 21 is a flow chart illustrating an exemplary method 200 for performing channel training adaptation. In some embodiments, the method 200 may be performed by any suitable system, apparatus, or device for channel training adaptation. For example, Figure 1 The AP 102 or STA 104 may perform or direct the performance of one or more of the operations associated with the method 200. The method 200 may include one or more blocks 202, 204, 206, 208, 210, 212, 214, 216, 218, or 220.

[0052] Generally speaking, method 200 may include determining one or more parameters of communication between an AP and a STA, including one or more of blocks 202, 204, 206, 208, 210, 212, and 214. Each of blocks 202, 204, 206, 208, 210, 212, and 214 is discussed in greater detail below.

[0053] At block 202, a determination may be made as to whether communication is occurring on a forward channel or a reverse channel. In some embodiments, if the AP 102 is transmitting data to the STA 104, the communication may occur on the forward channel. In these and other embodiments, if the STA 104 is transmitting data to the AP 102, the communication may occur on the reverse channel. Additionally or alternatively, the channel of communication may be determined based on information included in the transmission.

[0054] At block 204, a channel frequency selectivity estimate may be determined. In some implementations, the channel frequency selectivity estimate may be determined by the AP 102 as the channel frequency selectivity of the communication channel, as described above with respect to Figure 1 For example, a channel frequency selectivity estimate may be determined to indicate whether the channel is a flat fading channel or a channel with high frequency selective fading.

[0055] At block 206, the packet length of the communication (eg, the length of the packet) may be determined. In some embodiments, the AP 102 may determine the packet length of the communication, as described above with respect to Figure 1 For example, the packet length may be determined based on packets included in a DL transmission, a UL transmission, or a data portion of a previous transmission.

[0056] At block 208, the air time of the communication may be determined. In some embodiments, the AP 102 may determine the air time of the communication, as described above with respect to Figure 1 For example, the air time can be determined based on the amount of time that elapses between the initiation and completion of a transmission. As another example, the air time can be determined using the packet length of a packet in a DL transmission or an UL transmission.

[0057] At block 210, a precoding or beamforming selection may be determined for communication. In some embodiments, the AP 102 may determine the precoding or beamforming selection as described above with respect to Figure 1 The precoding or beamforming choices used for transmission may limit the techniques that can be used to perform channel estimation at the receiver.

[0058] At block 212, a success rate for previous communications may be determined. In some embodiments, the success rate may be determined based on previous transmissions between the AP 102 and the STA 104. In these and other embodiments, the AP 102 may determine the success rate, as described above with respect to Figure 1 discussed.

[0059] At block 214, a per-link channel configuration may be determined. In some embodiments, the per-link channel configuration may include the number or length of training symbols in a previously communicated training block. In these and other embodiments, the AP 102 may determine the per-link configuration as described above with respect to Figure 1 discussed.

[0060] At block 216, a training configuration may be determined. In some embodiments, the training configuration may be determined based on channel frequency selectivity estimates, air time of the communication, precoding or beamforming selections, or any combination of per-link channel configurations and success rates of previous communications. In these and other embodiments, the AP 102 may determine the training configuration as described above with respect to Figure 1 As discussed. In some embodiments, the training configuration may be determined to indicate that the number of training symbols to be included in a training block is one, two, four, six, or eight. In these and other embodiments, the training configuration may be determined to indicate that the length of the training symbols is equal to 1X, 2X, or 4X. The training configuration may be determined with or without reference to a previous transmission as a reference. For example, the training configuration may be determined to indicate that the number, length, or both of the number and length of the training symbols will be increased, decreased, or maintained relative to a previous training configuration. Alternatively, the determined training configuration may set the number, length, or both of the number and length of the training symbols without reference to a previous training configuration.

[0061] At block 217, a determination may be made as to whether the training configuration is for subsequent DL or UL transmissions. If the communication parameters determined at one or more of blocks 202, 204, 206, 208, 210, 212, 214 are for a forward channel, then the training configuration may be determined at block 217 to be for DL transmissions, in which case block 217 may be followed by one or more of blocks 218 and 220. If the communication parameters determined at one or more of blocks 202, 204, 206, 208, 210, 212, 214 are for a reverse channel, then the training configuration may be determined at block 217 to be for UL transmissions, in which case block 217 may be followed by one or more of blocks 222 and 224.

[0062] At block 218, and in response to determining the training configuration for subsequent DL transmission at block 217, a DL transmission may be generated. In some implementations, the DL transmission may be generated to include a training block according to the training configuration having the determined number or length of training symbols.

[0063] At block 220, a DL transmission may be transmitted. In some embodiments, a DL transmission may be transmitted from the AP 102 to the STA 104, and the STA 104 may use the above with respect to Figure 1 The training block in question is used to perform channel estimation.

[0064] At block 222, and in response to determining at block 217 that the training configuration is for subsequent UL transmissions, a trigger frame may be generated to include the training configuration with instructions to the STA 104 to include the determined number or length of training symbols in a training block of the UL transmission.

[0065] At block 224, a trigger frame may be transmitted to the STA 104. In response to receiving the trigger frame, the STA 104 may generate an UL transmission to include training blocks according to the training configuration. The STA 104 may then transmit the UL transmission with the training blocks configured according to the training configuration to the AP 102. The AP 102 may receive the UL transmission and may use the information described above with respect to Figure 1 The training block in question is used to perform channel estimation.

[0066] Those skilled in the art will understand that for this and other processes, operations, and methods described in this disclosure, the functions and / or operations performed may be implemented in a different order. Furthermore, the functions and operations outlined are provided as examples only, and some functions and operations may be optional, combined into fewer functions and operations, or expanded into additional functions and operations without detracting from the essence of the disclosed embodiments.

[0067] Figure 3A graphical representation 300 shows simulations of SNR versus packet error rate (PER) for a DL between an AP and two STAs with two or four communication streams using various numbers of training symbols and modulation schemes. In graphical representation 300, the Y-axis indicates PER on a logarithmic scale, and the X-axis indicates SNR. The simulations were performed using modulation and coding schemes (MCS) 2 (MCS2) and MCS11. Furthermore, the DL used for the simulations was channel D.

[0068] Curve 302 shows the use of MCS2 and eight training symbols (in Figure 3 Curve 304 shows the simulated SNR and PER of two communication flows in a wireless network using MCS2 and two training symbols (in Figure 3 Curve 306 shows the simulated SNR and PER of four communication flows in a wireless network using MCS2 and eight training symbols. Curve 308 shows the simulated SNR and PER of four communication flows in a wireless network using MCS2 and four training symbols (in Figure 3 4) shows the simulated SNR and PER of four communication flows within a wireless network for NLTF 4).

[0069] Curve 310 shows the simulated SNR and PER for two communication flows within a wireless network using MCS11 and eight training symbols. Curve 312 shows the simulated SNR and PER for two communication flows within a wireless network using MCS11 and two training symbols. Curve 314 shows the simulated SNR and PER for four communication flows within a wireless network using MCS11 and eight training symbols. Curve 316 shows the simulated SNR and PER for four communication flows within a wireless network using MCS11 and four training symbols.

[0070] like Figure 3As shown, for most SNR values, using more training symbols reduces the corresponding PER, regardless of the modulation scheme used. For example, as shown by curves 306 and 308, at an SNR of approximately 7.5, for MCS2, the PER decreases from approximately 30% to approximately 5% when eight training symbols (curve 308) are used, relative to when four training symbols (curve 306) are used. For another example, as shown by curves 310 and 312, at an SNR of 25, for MCS11, the PER decreases from approximately 62% to approximately 5.5% when eight training symbols (curve 310) are used, relative to when two training symbols (curve 312) are used. For another example, as shown by curves 314 and 316, at an SNR of 30, for MCS11, the PER decreases from approximately 95% to approximately 60% when eight training symbols (curve 314) are used, relative to when four training symbols (curve 316) are used. Therefore, in some embodiments, increasing the number of training symbols in a training block can improve channel estimation performance. Additionally, increasing the number of training symbols in a training block and causing the PER to decrease may improve decoding (eg, decoding rate) of the data portion of a transmission.

[0071] According to at least one embodiment described in this disclosure, a 2.5 dB improvement in transmission using MCS11 and a 1.2 dB improvement using MCS2 may be experienced.

[0072] Figure 4A 4 is a flow chart illustrating an exemplary method 400 for performing channel estimation. In some embodiments, the method 400 may be performed by any suitable system, apparatus, or device for determining a channel estimate. For example, Figure 1 The AP 102 or STA 104 may perform or direct the performance of one or more of the operations associated with the method 400. The method 400 may include one or more blocks 402, 404, 406, or 408.

[0073] At block 402, one or more parameters of a communication may be detected. In some embodiments, the parameters of a communication between an AP and a STA may be detected. In one example, the parameters may be detected specifically for a reverse channel between the AP and the STA. For example, the AP 102 may detect the parameters for Figure 1 Communication parameters for reverse channel communication between AP 102 and STA 104. Block 402 may include, be included in, or correspond to Figure 2 One or more of blocks 202, 204, 206, 208, 210, 212, 214.

[0074] At block 404, a training configuration for channel estimation for communication may be determined. In some implementations, the training configuration may be determined based on one or more parameters of the communication. For example, Figure 1 The AP 102 may determine the training configuration based on the parameters of the communication between the AP 102 and the STA 104. Block 404 may include, be included in, or correspond to Figure 2 The training configuration may be determined specifically for subsequent UL transmissions from the STA 104 to the AP 102.

[0075] At block 406, a trigger frame may be transmitted from the AP to the STA, for example, from AP 102 to STA 104. The trigger frame may include a training configuration and instructions to STA 104 to Figure 1 The next UL transmission of the AP 102 includes a training block configured according to the training configuration (e.g., with adjusted training symbols). Block 406 may include, be included in, or correspond to Figure 2 Box 224.

[0076] At block 408, a channel estimate for the communication channel may be determined. In some embodiments, the channel estimate may be determined using training blocks included in the UL transmission. In these and other embodiments, Figure 1 The AP 102 may use the training blocks to determine the channel estimate.

[0077] Figure 4B Flowchart of another exemplary method 450 for performing channel estimation is shown. In some embodiments, method 450 may be performed by any suitable system, apparatus, or device for determining channel estimation. For example, Figure 1 The AP 102 or STA 104 may perform or direct the performance of one or more of the operations associated with the method 450. The method 450 may include one or more blocks 452, 454, or 456.

[0078] At block 452, one or more parameters of the communication may be detected. In some embodiments, the parameters of the communication between the AP and the STA may be detected. In one example, the parameters may be detected specifically for the forward channel between the AP and the STA. For example, the AP 102 may detect the parameters for Figure 1 Communication parameters for forward channel communications between AP 102 and STA 104. Block 452 may include, be included in, or correspond to Figure 2 One or more of blocks 202, 204, 206, 208, 210, 212, 214.

[0079] At block 454, a training configuration for channel estimation for the communication may be determined. In some embodiments, the training configuration may be determined based on one or more parameters of the communication. For example, Figure 1 The AP 102 may determine the training configuration based on the parameters of the communication between the AP 102 and the STA 104. Block 454 may include, be included in, or correspond to Figure 2 Block 216 of FIG. The training configuration may be determined specifically for subsequent DL transmissions from the AP 102 to the STA 104.

[0080] At block 456, a DL transmission may be transmitted from the AP to the STA, e.g., from AP 102 to STA 104. In these and other embodiments, the DL transmission may include training blocks configured according to the training configuration (e.g., with adjusted training symbols). Block 456 may include, be included in, or correspond to Figure 2 Frame 220.

[0081] A channel estimate for the communication channel may then be determined. Specifically, a DL transmission may be received at a STA, and the STA may determine a channel estimate for the communication channel. In some embodiments, the channel estimate may be determined using training blocks included in the DL transmission received at the STA. In these and other embodiments, Figure 1 STA 104 may use the training blocks to determine a channel estimate.

[0082] Some portions of the detailed description are presented in terms of algorithms and symbolic representations of operations within a computer. These algorithmic descriptions and symbolic representations are the means by which those skilled in the data processing arts convey the essence of their innovations to others skilled in the art. An algorithm is a sequence of operations configured to produce a desired end state or result. In exemplary implementations, the operations performed require a tangible number of physical manipulations to achieve a tangible result.

[0083] Unless otherwise specifically stated, it will be apparent from the discussion that throughout the description, discussions utilizing terms such as detecting, determining, analyzing, identifying, scanning, etc., may include the actions and processes of a computer system or other information processing device that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system's memories or registers or other information storage, transmission, or display devices.

[0084] Example implementations may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the desired purpose, or it may comprise one or more general-purpose computers selectively activated or reconfigured by one or more computer programs. Such computer programs may be stored in a computer-readable medium, such as a computer-readable storage medium or a computer-readable signal medium. Computer-executable instructions may include, for example, instructions and data that cause a general-purpose computer, a special-purpose computer, or a special-purpose processing device (e.g., one or more processors) to perform or control the performance of certain functions or groups of functions.

[0085] Although the subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter configured in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0086] An exemplary device may include a wireless access point (WAP) or station and incorporates a VLSI processor and program code for support. The example transceiver is coupled to one of a cable, fiber optic, or digital subscriber backbone connection to the Internet via an integrated modem to support wireless communications on a wireless local area network (WLAN), such as IEEE 802.11 compliant communications. The WiFi stage includes a baseband stage, as well as an analog front end (AFE) and a radio frequency (RF) stage. In the baseband portion, wireless communications transmitted to or received from each user / client / station are processed. The AFE and RF portions handle the up-conversion on each transmit path of the wireless transmission initiated in the baseband. The RF portion also handles the down-conversion of signals received on the receive path and passes them to the baseband for further processing.

[0087] An exemplary device may be a MIMO device that supports up to NxN discrete communication streams via N antennas. In one example, the MIMO device signal processing unit may be implemented as NxN. In various embodiments, N may be 4, 6, 8, 12, 16, etc. Extended MIMO operation enables the use of up to 2N antennas for communication with another similarly equipped wireless system. It should be noted that an extended MIMO system can communicate with another wireless system even if the systems do not have the same number of antennas, but some antennas of one of the stations may not be utilized, thereby reducing optimal performance.

[0088] Channel state information (CSI) from any device described herein can be extracted independently of changes related to channel state parameters and used for spatial diagnostic services of the network, such as motion detection, proximity detection, and positioning, which can be used for, for example, WLAN diagnostics, home security, healthcare monitoring, smart home facility control, elderly care, car tracking and monitoring, home or mobile entertainment, car infotainment, etc.

[0089] Unless the specific arrangements described herein are mutually exclusive, the various implementations described herein may be combined in whole or in part to enhance system functionality and / or produce complementary functionality. Similarly, various aspects of an implementation may be implemented using independent arrangements. Therefore, the above description has been given by way of example only and may be modified in detail within the scope of the present invention.

[0090] The subject technology of the present invention is illustrated, for example, according to various aspects described below. For convenience, the various examples of various aspects of this subject technology are described as numbered embodiments (1, 2, 3, etc.). These are provided as examples and do not limit the subject technology. Unless otherwise specified by the context, the various aspects of the various specific implementations described herein can be omitted, replaced by various aspects of other specific implementations, or combined with various aspects of other specific implementations. For example, one or more aspects of the following embodiment 1 can be omitted, replaced by one or more aspects of another embodiment (for example, embodiment 2) or multiple embodiments, or combined with various aspects of another embodiment. The following is a non-limiting overview of some exemplary specific implementations presented herein.

[0091] Embodiment 1 A method comprising:

[0092] detecting one or more parameters of communication between the AP and the STA;

[0093] determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication; and

[0094] transmitting a DL transmission to the STA, the DL transmission comprising a training block configured according to the training configuration,

[0095] The STA is configured to determine the channel estimate of the communication channel using the training block of the DL transmission received at the STA.

[0096] In the method according to embodiment 1, determining the training configuration may include determining at least one of a number of training symbols or a length of training symbols to be included in the training block of the DL transmission. The method according to embodiment 1 may also include generating the training block of the DL transmission according to the training configuration. At least one of the number or the length of the training symbols may be determined to reduce an air time overhead of the training block of the DL transmission compared to an air time overhead of training blocks of one or more previous DL transmissions.

[0097] Embodiment 2. A system comprising:

[0098] The AP is configured as:

[0099] detecting one or more parameters of communication between the AP and the STA;

[0100] determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication; and

[0101] transmitting a DL transmission to the STA, the DL transmission comprising a training block configured according to the training configuration,

[0102] The STA is configured to determine the channel estimate of the communication channel using the training block of the DL transmission received at the STA.

[0103] Example 3. A method comprising:

[0104] detecting one or more parameters of communication between the AP and the STA;

[0105] determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication;

[0106] transmitting a trigger frame to the STA, the trigger frame including the training configuration and an instruction for the STA to include a training block configured according to the training configuration in a UL transmission to the AP; and

[0107] The channel estimate of the channel of the communication is determined using the training block of the UL transmission received at the AP.

[0108] In the method according to embodiment 3, determining the training configuration may include determining at least one of a number of training symbols to be included in the training block of the UL transmission or a length of the training symbols. At least one of the number or the length of the training symbols may be determined to reduce an air time overhead of the training block of the UL transmission compared to an air time overhead of training blocks of one or more previous UL transmissions.

[0109] In the method according to embodiment 3, detecting the one or more parameters of the communication may include determining that the channel of the communication is a flat fading channel. Determining the training configuration may include determining to reduce a length of one or more training symbols to be included in the training block of the UL transmission compared to a length of one or more training symbols included in training blocks of one or more previous UL transmissions.

[0110] In the method according to embodiment 3, detecting the one or more parameters of the communication may include detecting a length of one or more packets transmitted between the AP and the STA in one or more previous UL transmissions. In response to the length of the one or more packets being less than a packet length threshold, determining the training configuration may include: determining to reduce a length of training symbols to be included in the training block of the UL transmission compared to a length of training symbols included in the training blocks of the one or more previous UL transmissions; or determining to reduce a number of training symbols to be included in the training block of the UL transmission compared to a number of training symbols included in the training blocks of the one or more previous UL transmissions.

[0111] In the method according to embodiment 3, detecting the one or more parameters of the communication may include: detecting an air time of the communication; and determining a distance between the AP and the STA based on the air time of the communication. In response to the distance between the AP and the STA being greater than a distance threshold, determining the training configuration may include determining to increase the number of training symbols to be included in the training block of the UL transmission compared to the number of training symbols included in training blocks of one or more previous UL transmissions.

[0112] In the method of embodiment 3, detecting the one or more parameters of the communication may include detecting a signal-to-noise ratio (SNR) of the communication. In response to the SNR being less than an SNR threshold, determining the training configuration may include determining to increase a number of training symbols to be included in the training block of the UL transmission as compared to a number of training symbols included in training blocks of one or more previous UL transmissions.

[0113] In the method according to embodiment 3, detecting the one or more parameters of the communication may include detecting a precoding or beamforming selection for the communication.

[0114] In the method according to embodiment 3, detecting the one or more parameters of the communication may include detecting a previous training configuration of a previous UL transmission and a success rate of the previous UL transmission having the previous training configuration, the previous training configuration specifying a previous training symbol length and a previous number of training symbols of a previous training block of the previous UL transmission. In response to the success rate being less than a success rate threshold, determining the training configuration may include determining to increase at least one of the number or length of training symbols to be included in the training block of the UL transmission compared to the previous number of training symbols or the previous training symbol length of the previous training block of the previous UL transmission.

[0115] Embodiment 4. A system comprising:

[0116] The AP is configured as:

[0117] detecting one or more parameters of communication between the AP and the STA;

[0118] determining a training configuration for channel estimation for the communication based on the one or more parameters of the communication;

[0119] transmitting a trigger frame to the STA, the trigger frame including the training configuration and an instruction for the STA to include a training block configured according to the training configuration in a UL transmission to the AP; and

[0120] The channel estimate of the channel of the communication is determined using the training block of the UL transmission received at the AP.

[0121] With respect to the use of substantially any plural or singular terminology herein, those skilled in the art can translate from the plural to the singular or from the singular to the plural as appropriate to the context or application. For clarity, various singular / plural permutations may be explicitly set forth herein. Unless otherwise specified, reference to an element in the singular is not intended to mean "one and only one," but rather "one or more." Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly recited in the foregoing description.

[0122] In general, the terms used herein, and particularly in the appended claims (e.g., the bodies of the appended claims), are generally intended to be “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “including but not limited to,” etc.). Furthermore, in those instances where a convention similar to “at least one of A, B, and C, etc.” is used, generally, the meaning of such construction is the convention that one skilled in the art would understand (e.g., “a system having at least one of A, B, and C” would include but not be limited to a system including A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together, etc.). Additionally, phrases presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to include one, any, or both of the terms. For example, the phrase “A or B” would be understood to include the possibility of “A” or “B” or “A and B.”

[0123] The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. The embodiments described are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is therefore indicated by the appended claims rather than by the foregoing description. All variations that come within the meaning and range of equivalents of the claims are intended to be encompassed within the scope of the claims.

Claims

1. A method for performing channel training adaptation, the method comprising: Detecting one or more parameters of a communication channel between an access point AP and a wireless station STA, wherein detecting the one or more parameters of the communication channel includes detecting a signal-to-noise ratio (SNR) of the communication channel; determining, based on the one or more parameters of the channel of the communication, a training configuration for channel estimation of the channel of the communication, the training configuration indicating at least one of a number of training symbols to be included in a training block of a downlink (DL) transmission or a length of a training symbol, wherein, in response to the SNR being less than an SNR threshold, determining the training configuration comprises determining to increase the number of training symbols to be included in a training block of the DL transmission compared to a number of training symbols included in training blocks of one or more previous DL transmissions; as well as transmitting the DL transmission to the STA via the channel, the DL transmission comprising the training block and a data portion, the training block being configured according to the training configuration; and wherein the STA is configured to determine the channel estimate of the channel of the communication using the training blocks of the DL transmission received at the STA.

2. The method according to claim 1, wherein: determining the training configuration comprises determining at least one of a number of training symbols or a length of training symbols to be included in the training block of the DL transmission; and The method further comprises generating the training blocks for the DL transmission according to the training configuration.

3. The method according to claim 2, wherein: At least one of the number or length of the training symbols is determined to reduce an air time overhead of a training block of the DL transmission compared to an air time overhead of training blocks of one or more previous DL transmissions.

4. The method according to claim 1, wherein: detecting the one or more parameters of the channel of the communication includes determining that the channel of the communication is a flat fading channel; and Determining the training configuration includes determining to reduce a length of training symbols to be included in a training block of the DL transmission as compared to a length of one or more training symbols included in training blocks of one or more previous DL transmissions.

5. The method according to claim 1, wherein: Detecting the one or more parameters of the channel of the communication includes detecting a length of one or more packets transmitted between the AP and the STA in one or more previous DL transmissions; and In response to a length of the one or more packets being less than a packet length threshold, determining that the training configuration includes at least one of: determining to reduce a length of training symbols to be included in a training block of the DL transmission as compared to a length of training symbols included in training blocks of the one or more previous DL transmissions; or A determination is made to reduce the number of training symbols to be included in a training block of the DL transmission as compared to the number of training symbols included in training blocks of the one or more previous DL transmissions.

6. The method according to claim 1, wherein: Detecting the one or more parameters of the channel of the communication comprises: detecting an air time of the communication; and determining a distance between the AP and the STA based on the air time of the communication; and In response to the distance between the AP and the STA being greater than a distance threshold, determining the training configuration includes determining to increase a number of training symbols to be included in a training block of the DL transmission as compared to a number of training symbols included in training blocks of one or more previous DL transmissions.

7. The method according to claim 1, wherein Detecting the one or more parameters of the channel of the communication includes detecting a precoding or beamforming selection of the channel of the communication.

8. The method according to claim 1, wherein: detecting the one or more parameters of the channel of the communication comprises detecting a previous training configuration of a previous DL transmission and a success rate of the previous DL transmission having the previous training configuration, the previous training configuration specifying a previous training symbol length and a previous training symbol number of a previous training block of the previous DL transmission; and In response to the success rate being less than a success rate threshold, determining the training configuration includes determining to increase at least one of the number or length of training symbols to be included in the training block of the DL transmission compared to the number of previous training symbols or the length of previous training symbols of a previous training block of the previous DL transmission.

9. A system comprising: Access point AP, wherein the access point AP is configured as: detecting one or more parameters of a channel for communication between the AP and a wireless station (STA), wherein when detecting the one or more parameters of the channel for communication, the AP is configured to detect a length of one or more packets transmitted between the AP and the STA in one or more previous DL transmissions; determining a training configuration for channel estimation of the channel for the communication based on the one or more parameters of the channel for the communication, the training configuration indicating at least one of a number of training symbols to be included in a training block for a downlink (DL) transmission or a length of a training symbol, wherein in response to a length of the one or more packets being less than a packet length threshold, upon determining the training configuration, the AP is configured to perform at least one of the following: determining to reduce a length of training symbols to be included in a training block of the DL transmission as compared to a length of training symbols included in training blocks of the one or more previous DL transmissions; or determining to reduce a number of training symbols to be included in a training block of the DL transmission as compared to a number of training symbols included in training blocks of the one or more previous DL transmissions; as well as transmitting the DL transmission to the STA via the channel, the DL transmission comprising the training block and a data portion, the training block being configured according to the training configuration, Wherein the STA is configured to determine the channel estimate of the channel of the communication using the training blocks of the DL transmission received at the STA.

10. A method for performing channel training adaptation, the method comprising: Detecting, by an access point AP, one or more parameters of a communication channel between the AP and a wireless station STA, wherein detecting the one or more parameters of the communication channel includes: detecting an air time of the communication; as well as determining a distance between the AP and the STA based on the air time of the communication; determining, by the AP, a training configuration for channel estimation of the channel for the communication based on the one or more parameters of the channel for the communication, the training configuration indicating at least one of a number of training symbols to be included in a training block for a downlink (DL) transmission or a length of a training symbol, wherein, in response to a distance between the AP and the STA being greater than a distance threshold, determining the training configuration comprises determining to increase the number of training symbols to be included in a training block for an UL transmission as compared to a number of training symbols included in one or more previously transmitted UL training blocks; transmitting, from the AP to the STA, a trigger frame, the trigger frame including the training configuration and an instruction for the STA to include the training block configured according to the training configuration in an uplink (UL) transmission to the AP; receiving, at the AP, the UL transmission from the STA; and The channel estimate of the channel for the communication is determined using the training blocks of the UL transmission received at the AP.

11. The method according to claim 10, wherein: Determining the training configuration includes determining at least one of a number of training symbols or a length of training symbols to be included in the training block of the UL transmission.

12. The method according to claim 11, wherein At least one of the number or length of the training symbols is determined to reduce an air time overhead of a training block of the UL transmission compared to an air time overhead of training blocks of one or more previous UL transmissions.

13. The method according to claim 10, wherein: detecting the one or more parameters of the channel of the communication includes determining that the channel of the communication is a flat fading channel; and Determining the training configuration includes determining to reduce a length of training symbols to be included in a training block of the UL transmission as compared to a length of one or more training symbols included in training blocks of one or more previous UL transmissions.

14. The method of claim 10, wherein: Detecting the one or more parameters of the channel of the communication includes detecting a length of one or more packets transmitted between the AP and the STA in one or more previous UL transmissions; and In response to a length of the one or more packets being less than a packet length threshold, determining the training configuration includes: determining to reduce a length of training symbols to be included in a training block of the UL transmission as compared to a length of training symbols included in training blocks of the one or more previous UL transmissions; or A determination is made to reduce the number of training symbols to be included in a training block of the UL transmission as compared to the number of training symbols included in training blocks of the one or more previous UL transmissions.

15. The method of claim 10, wherein: Detecting the one or more parameters of the channel of the communication comprises detecting a signal-to-noise ratio (SNR) of the channel of the communication; and In response to the SNR being less than an SNR threshold, determining the training configuration includes determining to increase a number of training symbols to include in a training block of the UL transmission compared to a number of training symbols included in training blocks of one or more previous UL transmissions.

16. The method according to claim 10, wherein Detecting the one or more parameters of the channel of the communication includes detecting a precoding or beamforming selection of the channel of the communication.

17. The method of claim 10, wherein: detecting the one or more parameters of the channel of the communication includes detecting a previous training configuration of a previous UL transmission and a success rate of the previous UL transmission having the previous training configuration, the previous training configuration specifying a previous training symbol length and a previous training symbol number of a previous training block of the previous UL transmission; and In response to the success rate being less than a success rate threshold, determining the training configuration includes determining at least one of increasing the number or length of training symbols to be included in the training block of the UL transmission compared to the previous number of training symbols or the previous training symbol length of the previous training block of the previous UL transmission.

18. A system comprising: Access point AP, wherein the access point AP is configured as: detecting one or more parameters of a communication channel between the AP and a wireless station STA, wherein when detecting the one or more parameters of the communication channel, the AP is configured to: detecting an air time of the communication; and determining a distance between the AP and the STA based on the air time of the communication; determining, in response to a distance between the AP and the STA being greater than a distance threshold, a training configuration for channel estimation of the channel of the communication based on the one or more parameters of the channel of the communication by determining to increase a number of training symbols to be included in a training block of an UL transmission as compared to a number of training symbols included in training blocks of one or more previous UL transmissions, the training configuration indicating at least one of a number of training symbols to be included in a training block of a downlink (DL) transmission or a length of a training symbol; transmitting a trigger frame to the STA, the trigger frame including the training configuration and an instruction for the STA to include the training block configured according to the training configuration in an uplink (UL) transmission to the AP; and The channel estimate of the channel for the communication is determined using the training blocks of the UL transmission received at the AP.

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