This application provides a signal transmission method and apparatus. The method includes: A collaboration device receives a synchronization trigger frame delivered by a central device; the collaboration device obtains information about a time domain offset and/or information about a frequency domain offset; and the collaboration device sends a signal based on the synchronization trigger frame and the information about the time domain offset and/or the information about the frequency domain offset by using a corresponding time domain resource and a corresponding frequency domain resource. In this way, a plurality of collaboration devices send different time domain resources and/or frequency domain resources to a same terminal, and an interfering signal in channel estimation can be removed. This improves precision of the channel estimation and noise estimation at a receiving end, and improves demodulation performance at the receiving end and entire-network throughput.

A method and system to determine an adjusted guard interval duration associated with a wireless signal transmitted via a wireless communication link between a first network device and a second network device in a wireless network. The second network device receives a first wireless signal including a first duration of a guard interval from the first network device at a first time. The second network device determines, in view of the set of pilot symbols, a channel impulse response. A channel parameter value is determined based on the channel impulse response. An adjusted guard interval duration corresponding to the channel parameter value is established and used to estimate a second physical rate of the link. The second network device provides a communication identifying the adjusted guard interval duration to the first network device in response to determining the second physical rate is greater than the first physical rate.

Methods, devices, and systems for communication techniques that use the quasi-static properties of wireless channels are described. One example method to improve communication performance includes receiving a set of pilots over a transmission channel between the wireless communication apparatus and a far-end communication apparatus, the transmission channel comprising a first portion that is time-invariant and a second portion that is time-variant, processing the received set of pilots to generate an estimate of the first portion, processing the received set of pilots to generate an estimate of the second portion, and performing a communication based on a channel state information that is a weighted combination of a first term based on the estimate of the first portion and a second term based on the estimate of the second portion.

A signal processing apparatus for deblurring a digital input signal (I(x.sub.i)) comprising one or more processors. The one or more processors are configured to: compute a plurality of local length scales (l.sub.k, l(x.sub.i), λ) from at least one of a local signal resolution (FRC.sub.k) and a local signal-to-noise ratio (SNR.sub.k), and to compute each of the local length scales at a different location (I.sub.k(x.sub.i)) of the digital input signal, each of the different locations comprising at least one sample point (x.sub.i) of the input signal; compute a baseline estimate (ƒ.sub.n(x.sub.i, l.sub.n), ƒ(x.sub.i, l(x.sub.i))) of the input signal based on the local length scales, the baseline estimate representing signal structures of the digital input signal that are larger than the local length scale; and compute a digital output signal (O(x.sub.i)) based on one of (a) the baseline estimate and (b) the digital input signal and the baseline estimate.

An image processing apparatus for determining a focused output image in a passive autofocus system is configured to retrieve a set of input images and compute a baseline estimate for at least one input image. The baseline estimate represents image structures in the input image. The image structures have a length scale larger than a predetermined image feature length scale. The image processing apparatus is further configured to compute a set of output images, wherein each output image of the set of output images is computed based on one of a different input image of the set of input images and the at least one baseline estimate for the different input image and the at least one baseline estimate for a respective different input image. The image processing apparatus is further configured to determine one output image of the set of output images as the focused output image.

Embodiments of this application disclose example phase detection methods, phase detection circuits, and clock recovery apparatuses. One example method includes receiving a first signal and deciding a (2M−1) level of the first signal to obtain a decision result, where the first signal is a (2M−1)-level signal, and M is a positive integer. A response amplitude parameter of a transmission channel can then be obtained. Clock phase information in the first signal can then be extracted based on the first signal, the decision result, and the response amplitude parameter. Output clock phase information can then be determined based on at least three decision results and at least three pieces of clock phase information in at least three symbol periods.

A signal processing apparatus for enhancing a digital input signal (I(x.sub.i)) recorded by a recording system having a system response (H(x.sub.i)), is configured to retrieve the digital input signal (I(x.sub.i)) and compute a baseline estimate (ƒ(x.sub.i)) of the digital input signal, the baseline estimate representing a baseline of the digital input signal and comprising features of the digital input signal that are larger than a feature length (fl). The apparatus is further configured to remove the baseline estimate from the digital input signal to obtain an output signal comprising spatial features that are smaller than the feature length, retrieve a characteristic length (cl) of the system response (H(x.sub.i)) and compute the baseline estimate (ƒ(x.sub.i)) using a feature length that is smaller than the characteristic length of the system response (H(x.sub.i)).

Among other things, aspects, features, and implementations of wireless mesh networks and wireless mesh network devices are described.

Disclosed are Methods and apparatuses for estimating one or more characteristics of the communications channel. The method comprises receiving a first wireless signal transmitted by a transmitter at a first set of frequencies in a first time slot; and receiving a second wireless signal transmitted by the transmitter at a second set of frequencies in a second time slot. The second set of frequencies partially overlaps with the first set of frequencies and the second time slot is different from the first time slot. The method further comprises jointly processing the first wireless signal and the second wireless signal to estimate the one or more characteristics of the communications channel. Corresponding apparatuses are configured to implement the methods.

In at least one embodiment, a system for providing locationing multipath mitigation for wireless communication is provided. The system includes a receiver having at least one controller. The at least one controller is programmed to; receive a first narrowband wireless signal including a predetermined symbol from a transmitter across a wideband transmission channel that exhibits a multipath condition and additive noise, the first narrowband wireless signal being convoluted with the wideband channel to form a first received signal and to perform autocorrelation on the first received signal to extract the predetermined symbol. The at least one controller is further configured to filter the extracted predetermined symbol to deconvolve the first received signal to minimize the effects of the multipath condition and the additive noise to provide a first deconvoluted signal.