Methods, systems, devices, and apparatuses are described for phase noise estimation. A transmitting device identifies a phase noise metric associated with a receiving device. The phase noise metric provides an indication of the expected phase noise for the receiving device. The transmitting device selects a plurality of pilot tones adjacent to each other and a plurality of null tones for a transmission to the receiving device based on the phase noise metric. The plurality of null tones may be adjacent to and on both sides of the pilot tones in the frequency domain. The transmitting device identifies its own phase noise metric and select the pilot tones adjacent to each other and plurality of null tones in further consideration of its own phase noise metric. The receiving device may use the pilot tones and plurality of adjacent null tones to determine a phase noise estimation for the transmission.

Embodiments of the present invention provide a signal transmission method and apparatus, which can implement fast initial time synchronization. The method includes: generating, by a transmit-end device, an initial short training sequence, where the initial short training sequence includes M sub-sequences b, and the sub-sequence b includes N transmission sampling points; determining a quantity of reception sampling points used by a receive-end device when the receive-end device performs autocorrelation processing; generating a symbol sequence according to the quantity of the reception sampling points, and generating a target short training sequence according to the symbol sequence and the initial short training sequence; and sending a target signal to the receive-end device, where a short training sequence field of the target signal carries a short training sequence symbol, and the short training sequence symbol is used to indicate the target short training sequence.

A device for synchronizing a symbol clock during data transmission and to a transmission system. The device has: an estimation component and a symbol synchronizer, the estimation component being configured to receive a first signal generated by the transmitter and, based on the first signal, to estimate a phase offset and/or a frequency offset between a symbol clock of the transmitter, based on which the first signal is generated, and a symbol clock of the receiver based on which the first signal is evaluated in the receiver. The device initializes the symbol synchronizer, which is a feedback symbol synchronizer, based on the estimated phase offset and/or the estimated frequency offset. The symbol synchronizer receives a second signal generated by the transmitter, and generates an output signal based on the second signal, which represents symbols synchronized with the symbol clock of the receiver that are transmitted within the second signal.