Method and system for improving channel estimation in receiver

Abstract

The invention discloses a method and a system for improving channel estimation in a receiver. In one aspect, a receiver includes a digital processor having a digital signal processing path comprising: a packet detector for detecting packets; a channel profile circuit coupled to the packet detector to determine a channel profile of a channel via which the packet is received; a fast Fourier transform (FFT) engine to transform the grouped time domain samples to frequency domain samples; and a plurality of smoothing filters. The receiver also includes a controller coupled to the channel profile circuitry to select one of the plurality of smoothing filters to couple into the digital signal processing path based at least in part on the channel profile.

Description

Background Art

[0001] In a wireless local area network (WLAN) - orthogonal frequency division multiplexing (OFDM) system, the frequency domain impulse response of a channel (H) is obtained using training field information present in a packet (usually one or more long training fields (LTFs)). The channel response is obtained and correlated over the subcarriers of one or more symbols in the frequency domain. A receiver often includes a channel filter to perform channel smoothing to reduce the impact of noise on the estimation and improve performance. However, it is difficult to configure or select a suitable filter to adapt to all channel conditions. Summary of the Invention

[0002] In one aspect, a receiver includes: an analog front end (AFE) circuit for receiving and processing an incoming radio frequency (RF) signal, which includes a packet; an analog-to-digital converter (ADC) coupled to the AFE circuit for receiving the processed incoming RF signal and digitizing the processed incoming RF signal into a digital signal; and a digital processor coupled to the ADC. The digital processor has a digital signal processing path that includes: a packet detector for detecting the packet; a channel profile circuit coupled to the packet detector, the channel profile circuit for determining a channel profile of the channel via which the packet is received; a fast Fourier transform (FFT) engine for converting time domain samples of the packet to frequency domain samples; and a plurality of smoothing filters. The receiver further includes a controller coupled to the channel profile circuit, the controller for selecting one of the plurality of smoothing filters to couple into the digital signal processing path at least partially based on the channel profile.

[0003] In one implementation, the controller is to: calculate metric information based on the channel profile; and select one of the plurality of smoothing filters at least partially based on the metric information. The channel profile circuit may include at least one correlator to determine cross-correlation information at least partially based on the time domain samples. The controller is to calculate metric information that includes a plurality of metric values, each of the plurality of metric values corresponding to a ratio between a peak cross-correlation value and another cross-correlation value. The controller is to: select a first one of the plurality of smoothing filters when a first quantity of the plurality of metric values is less than a first threshold, and select a second one of the plurality of smoothing filters when a second quantity of the plurality of metric values exceeds the first threshold.

[0004] In one implementation, the controller is to calculate metric information, which includes a metric value corresponding to a ratio between a first set of cross-correlation values and a second set of cross-correlation values, and the first set of cross-correlation values includes peak cross-correlation values. The controller may be configured to calculate a metric value corresponding to a ratio between a first set of cross-correlation values including a first sum of cross-correlation values and a second set of cross-correlation values including a second sum of cross-correlation values. The controller may: select a first smoothing filter among the plurality of smoothing filters when the metric value exceeds a threshold; and select a second smoothing filter among the plurality of smoothing filters when the metric value is less than the threshold.

[0005] In one implementation, the first smoothing filter includes a narrowband finite impulse response filter, and the second smoothing filter includes a wideband finite impulse response filter.

[0006] In one implementation, the controller is to: select a first smoothing filter among the plurality of smoothing filters when the channel profile indicates an additive white Gaussian noise channel; and select a second smoothing filter among the plurality of smoothing filters when the channel profile indicates a multipath channel. The digital signal processing path may further include a channel estimator coupled to an input of the selected smoothing filter to receive unsmoothed frequency domain samples, and the channel estimator is configured to determine smoothed frequency domain samples.

[0007] In another aspect, a method includes: obtaining digital samples from an incoming radio frequency signal in a receiver; calculating cross-correlation information for at least a portion of the digital samples; determining a channel profile based at least in part on the cross-correlation information; selecting a smoothing filter among a plurality of smoothing filters of the receiver based at least in part on the channel profile; and coupling the selected smoothing filter into the digital signal processing path of the receiver.

[0008] In one implementation, the method further includes: calculating cross-correlation information using time domain samples of a training field portion of the digital samples; and smoothing frequency domain channel estimation samples obtained from a channel estimator using the selected smoothing filter. The method may further include: receiving smoothed frequency channel estimation samples from an output of the selected smoothing filter; determining a channel estimation for the smoothed frequency domain samples; providing the smoothed channel estimation to a decoder of the receiver; and using the smoothed channel estimation in the decoder to decode a plurality of data symbols for an equalization process to obtain message content of the digital samples.

[0009] In one implementation, the method includes using cross-correlation information to calculate metric information. Using cross-correlation information to calculate metric information may include: calculating a plurality of metric values, each of the plurality of metric values corresponding to a ratio between a peak cross-correlation value and another cross-correlation value. The method may further include: determining a channel profile based at least in part on the metric information; selecting a first smoothing filter from the plurality of smoothing filters when the channel profile indicates an additive white Gaussian noise channel; and selecting a second smoothing filter from the plurality of smoothing filters when the channel profile indicates a multipath channel.

[0010] In yet another aspect, a wireless device includes: an antenna; an AFE circuit coupled to the antenna for receiving and processing incoming RF signals, the incoming RF signals including packets; a digitizer coupled to the AFE circuit for receiving the processed incoming RF signals and digitizing the processed incoming RF signals into digital signals; and a baseband processor coupled to the digitizer. The baseband processor may have a digital signal processing path including: a packet detector for detecting packets; at least one correlator for generating cross-correlation information for at least a portion of a training field of a packet; a plurality of smoothing filters. The wireless device further includes a controller for receiving the cross-correlation information and calculating one or more metric values based at least in part thereon, the controller for selecting one of the plurality of smoothing filters to couple into the digital signal processing path based at least in part on the one or more metric values.

[0011] In one implementation, the controller is to calculate the one or more metric values including a plurality of metric values, each of the plurality of metric values corresponding to a ratio between a peak cross-correlation value and another cross-correlation value, and the controller is to select a narrowband smoothing filter from the plurality of smoothing filters when a first metric value among the plurality of metric values indicates an additive white Gaussian noise channel profile.

[0012] In one implementation, the controller is to calculate the one or more metric values that is a single metric value, the single metric value corresponding to a ratio between a first set of cross-correlation values and a second set of cross-correlation values, the first set of cross-correlation values including a peak cross-correlation value, and the controller is to select a wideband smoothing filter from the plurality of smoothing filters when the single metric value indicates a multipath channel profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a block diagram of a receiver according to an embodiment.

[0014] Figure 2 is a flowchart of a method according to an embodiment.

[0015] Figure 3is a graphical illustration of the cross - correlation output graph for AWGN channels and multipath channels.

[0016] Figure 4 is a block diagram of a typical integrated circuit incorporating an embodiment.

[0017] Figure 5 is a high - level diagram of a network according to an embodiment. Detailed Description

[0018] In various embodiments, a receiver includes a plurality of filters that can be used to filter incoming frequency - domain channel information obtained using a channel estimation process to perform channel smoothing, where the receiver uses the information from channel smoothing for performing equalization on data symbols. One of the plurality of channel filters can be selected based at least in part on the profile of the channel for use in performing channel smoothing.

[0019] In one embodiment, a finite impulse response (FIR) filter is used to perform channel smoothing. In this filtering operation, the frequency - domain channel is convolved with the filter, which can be implemented as a time - domain FIR filter to perform the smoothing operation. The characteristics of the FIR filter can be a significant factor affecting receiver performance. Thus, performance is improved by selecting an appropriate one of the plurality of filters present in the receiver.

[0020] Delay spread is one of the parameters by which a multipath channel can be characterized. Delay spread is the time difference between the first and the last significant reflection / path, and the RMS delay spread can also be calculated based on the channel profile, which is a measure of the multipath richness of the channel. The cyclic prefix (CP) present between OFDM symbols helps in handling the multipath effect. Generally, the CP must be greater than the delay spread of the channel to handle multipath scenarios.

[0021] Considering the scenario of a pure additive white Gaussian noise (AWGN) channel without multipath components, the significant energy in the time - domain channel impulse response is confined to a few (e.g., 1 to 2) samples around the central sample. In a multipath scenario, based on the delay spread of the multipath channel, energy in the time - domain impulse response is observed over multiple samples around the center. For example, if the delay spread of the channel is 0.4 microseconds (μsec), then the time - domain impulse response has significant components over approximately a total of 8 samples (where the sampling rate is 20 megahertz (MHz)). Thus, for an AWGN scenario, a smoothing filter with a narrow passband (which spans the number of samples where there is energy) is suitable for giving the best performance scenario.

[0022] However, for a multipath scenario, compared to the AWGN scenario described above, the smoothing filter may have a wider passband. For a multipath scenario, the smoothing filter can be configured with a passband that covers samples in the time-domain channel impulse response where significant energy exists.

[0023] In various embodiments, the receiver can include N filters, and a given one of the filters can be suitably selected based on the channel profile. In one embodiment, the system can have only two filters (N = 2), such that one filter is for the AWGN scenario and the other filter is for the multipath case.

[0024] Generally speaking, compared to using a narrower filter, using a wider filter for the AWGN scenario results in performance degradation (because it allows more noise components / samples to enter the passband). Conversely, using a narrower filter for the multipath scenario causes problems because channel information may be filtered out / lost. Therefore, embodiments provide techniques for selecting a given smoothing filter based on the channel profile.

[0025] Now referring to Figure 1 , shown is a block diagram of a receiver according to an embodiment. As Figure 1 shown therein, the receiver 100 can be part of any type of wireless device, ranging from a small portable Internet of Things (IoT) device to a smartphone, smartwatch, tablet, or other wireless device.

[0026] As illustrated, the device 100 receives an incoming radio frequency (RF) signal via the antenna 105, and the antenna 105 provides the RF signal to the RF analog front-end (AFE) circuit 110. In various implementations, the AFE circuit 110 can include various filtering circuits, including analog filters, gain circuits including programmable gain amplifiers (PGAs), mixers that down-convert the RF signal to a lower frequency signal, such as an intermediate frequency (IF) signal, such as a low IF, zero IF, or other lower frequency signal. The AFE circuit 110 can include additional circuits. The resulting processed lower frequency signal is then provided to an analog-to-digital converter (ADC) 115, which converts the signal to a digital stream that is provided to the baseband processor 120. The baseband processor 120 is shown at a high level in Figure 1 to include various circuits related to performing the smoothing filter control operations described herein.

[0027] As shown, the incoming baseband digital baseband signal is provided to a packet detector 125 that detects the start of a packet. In one embodiment, cyclic prefix removal is done after fine symbol timing obtained by processing the conventional long training field (L-LTF) field of the packet. The resultant packet information is then provided to a carrier frequency offset (CFO) detector / compensator 130 that can detect the CFO present between the receiver and the transmitter. The CFO detector / compensator 130 also compensates for the carrier frequency offset of the device. The resultant compensated time domain samples are provided to a channel profile circuit 140 and a cyclic prefix removal circuit 134 that further removes the cyclic prefix. The time domain OFDM samples with the cyclic prefix removed are given as input to a fast Fourier transform (FFT) engine 135 that transforms the incoming time domain samples into the frequency domain, i.e., as a plurality of subcarriers. For the discussion herein, these subcarriers include data subcarriers and additional so-called pilot subcarriers that are known subcarriers distributed throughout the frequency domain to enable channel estimation and other processing to be performed.

[0028] The resultant frequency domain signal is provided to a channel estimation circuit 160. In one embodiment, the FFT input is circularly shifted by a few samples to simplify the smoothing operation such that frequency domain channel smoothing can be done by a real coefficient low-pass filter instead of a complex coefficient band-pass filter.

[0029] In an embodiment herein, the channel profile circuit 140 can be configured to determine a channel profile from the time domain samples. To this end, these samples are provided to a set of correlators 142 that can perform a cross-correlation between the time domain samples and a known sequence stored in a storage device 144. In one embodiment, the known sequence can correspond to a given portion of a packet preamble such as the LTF. Further, the channel profile circuit 140 can determine the channel profile based at least in part on the cross-correlation information.

[0030] In one embodiment, a channel profile is obtained using an L-LTF based cross-correlation method. In this method, the received L-LTF portion / samples of the packet are correlated with the expected / stored L-LTF samples. During the cross-correlation operation, the fine symbol timing may not yet be determined. However, based on the conventional short training field (L-STF), a coarse timing is available. Ensure that the CFO between the two devices is as low as possible. In one embodiment, the cross-correlation operation is performed after compensating for the coarse CFO obtained from the L-STF. In another embodiment, the cross-correlation operation is performed after compensating for the coarse CFO estimate and the fine CFO estimate (after it is determined). In one embodiment, the L-LTF field is used to obtain the fine CFO estimate. In a particular embodiment for communication using the IEEE802.11ax framework, channel estimation can be obtained from the L-LTF (pre-high efficiency (HE)) and / or the HE-LTF fields.

[0031] The cross-correlation output is used to determine the type of channel and the selection of the smoothing filter. The channel profile information is then provided to the controller 150. Herein, the controller 150 is configured to determine an appropriate smoothing filter to be used at least in part based on the channel profile information. More specifically, depending on the channel profile, the controller 150 may select a given smoothing filter. Although the discussion herein refers to the channel profile that identifies the channel as an AWGN channel profile or a multipath channel profile, other channel profiles may be identified in other embodiments. For example, there are different types of multipath channels, and they are grouped or characterized based on the delay profile and spread of the channel. The channel is also characterized based on Doppler measurements.

[0032] As can be seen, the controller 150 provides filter control signaling to the channel estimation circuit 160. In response to this signaling, the channel estimation circuit 160 (which includes a channel estimator 162 and a plurality of smoothing filters 165 0-n ) configures the receiver signal processing path to include a selected smoothing filter from among the smoothing filters 165. That is, at least in part based on the channel profile information, a given smoothing filter 165 is selected for use in processing the frequency domain information coming into the channel estimator 162 (such as that received from the FFT engine 135). This channel smoothing filter selection may include configuring a particular channel smoothing filter into the receiver signal processing path by way of one or more switches or the like. Additionally, the controller 150 may set the parameters of the selected channel smoothing filter, including bandwidth, filter taps, and the like. Although the controller 150 is shown as being included in the baseband processor 120, in other embodiments the controller 150 may be separate from the baseband processor 120. The selection of the channel smoothing filter or the parameters of the channel smoothing filter are determined based on a metric calculated on the determined channel profile and are explained by way of examples in the following sections.

[0033] Still referring to Figure 1 , the channel estimation along with the frequency domain data subcarriers is provided to the decoder 170, which decodes the data subcarriers into a set of bits, which are then provided to additional receiver blocks for further processing or are provided to the Medium Access Control (MAC) layer. Although shown at this high level in the Figure 1 embodiment, many variations and alternatives are possible.

[0034] Now referring to Figure 2 , shown is a flowchart of a method according to an embodiment. In Figure 2In [the figure], method 200 is a method for selecting an appropriate smoothing filter according to an embodiment. Method 200 can be executed by a hardware circuit, such as a controller of a receiver alone, and / or in combination with firmware and / or software, which can be implemented as instructions stored in a non-transitory storage medium.

[0035] As illustrated, method 200 begins by receiving and processing an incoming RF signal to obtain packet content (block 210). Such processing can be performed within the receiver signal processing path. Next, at block 220, cross-correlation information can be calculated on the training field of the packet content. For example, a channel profile circuit can perform the cross-correlation between the LTF present in the header of the packet and a known LTF time-domain sequence / sample.

[0036] Still referring to Figure 2 , the resulting cross-correlation information can be provided to the channel profile circuit, which determines the channel profile (block 230) at least in part based on the cross-correlation information. Next, at block 240, the controller can be configured to select a given smoothing filter from a plurality of smoothing filters at least in part based on the channel profile for use in performing channel estimation.

[0037] As an example, assume the receiver has 8 filters (e.g., implemented as low-pass filters (LPF)) with different passband bandwidths. Consider the peak of the cross-correlation as the first sample and its energy as E 1 , and the energy of sample k after this peak as E k . In one embodiment, E k is the energy of the Kth peak in the cross-correlation output. With this nomenclature, the controller can calculate a metric according to the following equation:

[0038] Iteratively determine the value of the metric for k. From the determined metric, the controller identifies a given metric that has a value below a threshold (e.g., metric 1 is less than 0.01 (threshold 1)). Based on the determined value of k, the corresponding filter is coupled into the receiver signal processing path and used for smoothing purposes. There can be multiple values of k at which metric 1 is greater than threshold 1. The highest value of k for which metric 1 is not less than threshold 1 is used for smoothing filter selection.

[0039] In another example, assume the receiver has 2 filters available (e.g., LPF) with different passband bandwidths. For example, the first filter can be configured as a narrowband filter (with a passband between -0.625 MHz and +0.625 MHz), and the second filter can be configured as a broadband filter (with a passband between -1.56 MHz and +1.56 MHz).

[0040] In this example, the controller can calculate a metric according to the following equation:

[0041] The controller can select an appropriate filter based on the value of the metric. For example, if the metric has a value below a given threshold (e.g., metric 2 is less than 0.35 (threshold 2)), the controller selects a wider bandwidth filter; otherwise, a narrow bandwidth filter is used.

[0042] As Figure 2 further shown in, at block 250, the receiver is configured with the selected smoothing filter in the receiver signal processing path. To this end, various switches can be performed to route the incoming frequency-domain subcarriers through the selected smoothing filter. Additionally, appropriate configuration of the smoothing filter can be performed, including setting a given bandwidth and a given number of filter taps. Finally, at block 260, the frequency-domain samples can be smoothed by the selected smoothing filter. Thus, a more accurate channel estimate is determined and provided for use in the decoding operation. Although shown at this high level in the Figure 2 embodiment, many variations and alternatives are possible. For example, other smoothing techniques can be used, such as by vacating several samples in the time-domain impulse response of the channel (by performing an inverse FFT (IFFT) on H) and converting it back to the frequency domain (using an FFT engine).

[0043] Now referring to Figure 3 , a graphical illustration of the cross-correlation output plots for an AWGN channel (illustration 310) and a multipath channel (whose RMS delay spread is 50 nanoseconds) (illustration 320) is shown. As shown, compared to the multipath case, for the AWGN case, most of the energy is in a smaller bandwidth, and thus filter selection can be performed accordingly.

[0044] Now referring to Figure 4 , a block diagram of a typical integrated circuit 400 is shown, which includes a channel smoothing filter selection circuit as described herein. In the Figure 4 embodiment shown, the integrated circuit 400 can be, for example, a dual-mode wireless transceiver that can operate according to one or more wireless protocols (e.g., WLAN and Bluetooth, etc.), or other devices that can be used in a variety of use cases. In one or more embodiments, Figure 4 the circuitry of the integrated circuit 400 shown in can be implemented on a single semiconductor chip.

[0045] The integrated circuit 400 can be included in a series of devices, including various stations, including smartphones, wearable devices, smart home devices, other consumer devices, or industrial, scientific, and medical (ISM) devices, etc.

[0046] In the illustrated embodiment, integrated circuit 400 includes a memory system 410 which, in one embodiment, may include volatile storage devices (such as RAM) and non-volatile memory (such as flash memory). As further shown, optionally, integrated circuit 400 may also include a separate flash memory 490 (or other non-volatile memory). The flash memory 490 may be implemented as a non-transitory storage medium which may store instructions and data. Such non-volatile memory may store instructions, including instructions for performing channel smoothing filter selection (as described herein).

[0047] The memory system 410 is coupled to a digital core 420 via a bus 450. The digital core 420 may include one or more cores and / or microcontrollers which act as the main processing unit of the integrated circuit. Further, the digital core 420 may be coupled to a clock generator 430 which may provide one or more phase-locked loops or other clock generator circuits to generate various clocks for use by the circuits of the IC.

[0048] As further illustrated, IC 400 also includes a power circuit 440 which may include one or more voltage regulators. Depending on the particular implementation, additional circuits may optionally be present to provide various functionality and interaction with external devices. Such circuits may include an interface circuit 460 which may provide a LAN or other interface to various off-chip devices, and a security circuit 470 which may perform wireless security techniques.

[0049] In addition, as Figure 4 shown, a transceiver circuit 480 may be provided to enable reception and transmission of wireless signals, for example, according to one or more of local or wide area wireless communication schemes such as Zigbee, Bluetooth, IEEE 802.11, IEEE 802.15.4, cellular communication or the like. As shown, the transceiver circuit 480 includes a plurality of channel smoothing filters 485 1-n which may be dynamically selected based on channel profile information (as described herein). It is understood that while shown from this high-level perspective, many variations and alternatives are possible.

[0050] ICs such as those described herein may be implemented in a variety of different devices such as wireless stations, IoT devices or the like. Now referring Figure 5 to, shown is a high-level diagram of a network according to an embodiment. As Figure 5 shown, network 500 includes a variety of devices, including wireless stations (including smart devices such as IoT devices), access points and remote service providers which may utilize the embodiment for selecting a suitable channel smoothing filter.

[0051] In Figure 5 an embodiment of, there is a wireless network 505, for example, in a building having a plurality of wireless devices 510 0-n . As shown, the wireless devices 510 are coupled to an access point 530, which in turn communicates with a remote service provider 560 via a wide area network 550 (e.g., the Internet). It is understood that although shown at this high level in Figure 5 an embodiment of, many variations and alternatives are possible.

[0052] Although the present disclosure has been described with respect to a limited number of implementations, those of ordinary skill in the art who have benefited from the present disclosure will appreciate numerous modifications and variations therein. The appended claims are intended to cover all such modifications and variations.

Claims

1. A receiver, comprising: an analog front end (AFE) circuit for receiving and processing incoming radio frequency (RF) signals, the incoming RF signals comprising packets; an analog-to-digital converter (ADC) coupled to the AFE circuit to receive the processed incoming RF signal and digitize the processed incoming RF signal into a digital signal; a digital processor coupled to the ADC, the digital processor having a digital signal processing path, the digital signal processing path comprising: a packet detector for detecting said packets; a channel profile circuit coupled to the packet detector, the channel profile circuit for determining a channel profile of a channel via which the packet is received; a Fast Fourier Transform (FFT) engine for converting the packetized time domain samples into frequency domain samples; and a plurality of smoothing filters; and A controller is coupled to the channel profile circuit, the controller being configured to select a smoothing filter of the plurality of smoothing filters to couple into the digital signal processing path based at least in part on the channel profile.

2. The receiver of claim 1, wherein: The controller shall: calculating metric information based on the channel profile; and The one smoothing filter of the plurality of smoothing filters is selected based at least in part on the metric information.

3. The receiver of claim 1, wherein: The channel profile circuit includes at least one correlator to determine cross-correlation information based at least in part on the time domain samples.

4. The receiver of claim 1, wherein: The controller is to calculate the metric information, the metric information comprising a plurality of metric values, each metric value of the plurality of metric values ​​corresponding to a ratio between a peak cross-correlation value and another cross-correlation value.

5. The receiver of claim 4, wherein: The controller shall: selecting a first smoothing filter among the plurality of smoothing filters when a first number of metric values ​​among the plurality of metric values ​​is less than a first threshold, and A second smoothing filter among the plurality of smoothing filters is selected when a second number of metric values ​​among the plurality of metric values ​​exceeds the first threshold.

6. The receiver of claim 1, wherein: The controller is to calculate the metric information, the metric information comprising a metric value corresponding to a ratio between a first set of cross-correlation values ​​and a second set of cross-correlation values, the first set of cross-correlation values ​​comprising peak cross-correlation values.

7. The receiver of claim 6, wherein: The controller is to calculate the metric value corresponding to the ratio between the first set of cross-correlation values ​​including a first sum of cross-correlation values ​​and the second set of cross-correlation values ​​including a second sum of cross-correlation values.

8. The receiver of claim 7, wherein: The controller shall: selecting a first smoothing filter among the plurality of smoothing filters when the metric value exceeds a threshold; and A second smoothing filter among the plurality of smoothing filters is selected when the metric value is less than the threshold value.

9. The receiver of claim 8, wherein: The first smoothing filter comprises a narrowband finite impulse response filter, and the second smoothing filter comprises a wideband finite impulse response filter.

10. The receiver of claim 1, wherein: The controller shall: selecting a first smoothing filter of the plurality of smoothing filters when the channel profile indicates an additive white Gaussian noise channel; and A second smoothing filter of the plurality of smoothing filters is selected when the channel profile indicates a multipath channel.

11. The receiver of claim 1, wherein: The digital signal processing path further includes a channel estimator coupled to an input of the selected smoothing filter to receive the unsmoothed frequency domain samples, the channel estimator being configured to determine smoothed frequency domain samples.

12. A method comprising: obtaining digital samples from the incoming RF signal in a receiver; calculating cross-correlation information for at least a portion of the digital samples; determining a channel profile based at least in part on the correlation information; selecting a smoothing filter from a plurality of smoothing filters of the receiver based at least in part on the channel profile; as well as The selected smoothing filter is coupled into a digital signal processing path of the receiver.

13. The method of claim 12, further comprising: Calculating the cross-correlation information using time domain samples of a training field portion of the digital samples; as well as The frequency domain channel estimation samples obtained from the channel estimator are smoothed using the selected smoothing filter.

14. The method of claim 13, further comprising: receiving smoothed frequency channel estimate samples from an output of the selected smoothing filter; determining a channel estimate for the smoothed frequency domain samples; providing the smoothed channel estimate to a decoder of the receiver; as well as A plurality of data symbols are decoded using the smoothed channel estimate in the decoder for use in an equalization process to obtain a message content of the digital samples.

15. The method of claim 12, further comprising using the cross-correlation information to calculate metric information.

16. The method of claim 15, wherein: Calculating the metric information using the correlation information includes: A plurality of metric values ​​are calculated, each metric value of the plurality of metric values ​​corresponding to a ratio between a peak cross-correlation value and another cross-correlation value.

17. The method of claim 15, further comprising: determining the channel profile based at least in part on the metric information; selecting a first smoothing filter of the plurality of smoothing filters when the channel profile indicates an additive white Gaussian noise channel; and A second smoothing filter of the plurality of smoothing filters is selected when the channel profile indicates a multipath channel.

18. A wireless device comprising: antenna; an analog front end (AFE) circuit coupled to the antenna, the AFE circuit configured to receive and process incoming radio frequency (RF) signals, the incoming RF signals comprising packets; a digitizer coupled to the AFE circuit, the digitizer for receiving the processed incoming RF signal and digitizing the processed incoming RF signal into a digital signal; a baseband processor coupled to the digitizer, the baseband processor having a digital signal processing path, the digital signal processing path comprising: a packet detector for detecting said packets; at least one correlator for generating cross-correlation information for at least a portion of a training field of the packet; a plurality of smoothing filters; and A controller is configured to receive the cross-correlation information and calculate one or more metric values ​​based at least in part thereon, the controller being configured to select one of the plurality of smoothing filters to couple into the digital signal processing path based at least in part on the one or more metric values.

19. The wireless device of claim 18, wherein: The controller is to calculate the one or more metric values ​​including a plurality of metric values, each metric value in the plurality of metric values ​​corresponding to a ratio between a peak mutual correlation value and another mutual correlation value, and the controller is to select a narrowband smoothing filter among the plurality of smoothing filters when a first metric value in the plurality of metric values ​​indicates an additive white Gaussian noise channel profile.

20. The wireless device of claim 18, wherein: The controller is to calculate the one or more metric values ​​into a single metric value corresponding to a ratio between a first set of cross-correlation values ​​and a second set of cross-correlation values, the first set of cross-correlation values ​​including peak cross-correlation values, and the controller is to select a wideband smoothing filter from the plurality of smoothing filters when the single metric value indicates a multipath channel profile.

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