Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) may receive, from a second UE and using a first fast Fourier transform (FFT) window configuration, a physical sidelink control channel (PSCCH) signal associated with a physical sidelink shared channel (PSSCH) signal. The UE may identify, based at least in part on the reception of the PSCCH signal, one or more values of one or more parameters estimated from the PSCCH signal. The UE may select, based at least in part on the one or more values of the one or more parameters, a second FFT window configuration to be used to receive the PSSCH signal. The UE may receive, from the second UE, the PSSCH signal using the second FFT window configuration, Numerous other aspects are described.

This application provides a synchronization signal sending method and receiving method, and an apparatus. In the method, a base station determines a frequency domain position of a target frequency resource based on a frequency interval of synchronization channels, wherein the frequency interval of synchronization channels is 2.sup.m times a predefined frequency resource of a physical resource block, and m is a preset nonnegative integer. The base station sends a synchronization signal by using the target frequency resource.

Methods, systems, and devices for tampering detection in phase based ranging are described.

A device may engage in two-tone phase based ranging. For example, the device may transmit a composite signal that includes a first carrier at a first frequency and a second carrier at a second frequency. The device may receive a third carrier at the first frequency and measure its phase. The device may determine a phase sum associated with the first frequency based on the measured phase of the third carrier and a measured phase of the first carrier. The device may compare the phase sum with a reference value and determine whether tampering with the phase based ranging has occurred based on the comparison.

Systems and methods are described, and one method includes acquiring a frequency offset for a demodulator receiving one symbol rate in combination with acquiring another frequency offset for another demodulator, based on sweeping the other frequency offset until detecting a qualifying symbol pattern or acquiring the frequency offset for the demodulator receiving one symbol rate, whichever occurs first. Associated with acquiring the other frequency offset based on acquiring the frequency offset for the demodulator receiving one symbol rate, setting the other frequency offset includes adjusting the frequency offset for the demodulator receiving one symbol rate.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate with a base station by initiating a random access procedure with a two-root preamble. The UE may receive, from the base station, control signaling that indicates a set of root preamble sequences. The UE may transmit, to the base station, a preamble signal that is generated based on a first root preamble sequence and a second root preamble sequence of the set of root preamble sequences. The UE may then monitor for a preamble response based on the preamble signal. In some cases, the base station may be a base station in a terrestrial network. In other cases, the base station may be a satellite in a non-terrestrial network (NTN).

The present invention provides a preamble that is inserted into an OFDMA frame and has a common sequence for all the base stations participating in a transmission. The subscriber station performs fine synchronization using the common sequence on the common preamble, and the resulting peaks will provide the locations of candidate base stations. The base station specific search is then performed in the vicinities of those peaks by using base station specific pseudo-noise sequences. With this two stage cell search, the searching window is drastically reduced. The preamble is matched to known values by a respective receiver to decode the signals and permit multiple signals to be transferred from the transmitter to the receiver. The preamble may comprise two parts, Preamble-1 and Preamble-2, which may be used in different systems, including multioutput, multi-input (MIMO) systems.

This application provides a synchronization signal sending method and receiving method, and an apparatus. In the method, a base station determines a frequency domain position of a target frequency resource based on a frequency interval of synchronization channels, wherein the frequency interval of synchronization channels is 2.sup.m times a predefined frequency resource of a physical resource block, and m is a preset nonnegative integer. The base station sends a synchronization signal by using the target frequency resource.

This application provides a synchronization signal sending method and receiving method, and an apparatus. In the method, a base station determines a frequency domain position of a target frequency resource based on a frequency interval of synchronization channels, wherein the frequency interval of synchronization channels is 2.sup.m times a predefined frequency resource of a physical resource block, and m is a preset nonnegative integer. The base station sends a synchronization signal by using the target frequency resource.

Methods, systems, and devices for wireless communication are described. A transmitting device may transmit a wakeup message to another device. The wakeup message may be transmitted using a transmit diversity scheme in accordance with aspects of the present disclosure. The transmit diversity may, for example, include a cyclic shift diversity scheme, a phase rotation scheme, a symbol generation scheme, or combinations thereof. The transmit diversity may in some cases improve a communication range of the wakeup message or otherwise benefit the wireless communications system.

A method and apparatus estimating carrier frequency offset (CFO) with timing synchronization are provided. The apparatus includes processor that receives analog-to-digital converter (ADC) samples, determines a coarse angle from the received ADC samples, obtains an improved coarse angle by altering the coarse angle based on a preamble duration, determines a base CFO estimate from the improved coarse angle and determines a plurality of candidate CFOs based on the base CFO estimate and a difference frequency.