Methods, systems, and devices for wireless communications are described that provide time synchronization via wireless communications for devices that use strict timing synchronization. A user equipment (UE) may obtain time synchronization via a wireless connection between the UE and a timing source that may be associated with a base station (or another wireless device). In some cases, the timing source may be synchronized at the UE by determining, using periodic synchronization resources, a propagation delay between the UE and the base station that is based on a timing of a line-of-sight instance of a transmission between the base station and the UE. The propagation delay may be used to determine a timing advance value for use in timing synchronization. One or more devices may be coupled with the UE and the UE may provide commands to the one or more devices that are synchronized according to the synchronized timing source.

Embodiments are disclosed for timing recovery used in conjunction with a phase detector embedded in a receiver of a communication system. An example method includes receiving, via a receiver of a communication system, an input signal. The input signal encodes a plurality of bits in a number of amplitude levels. The method further includes using an analog to digital converter to generate a sampled signal based on the input signal. The method further includes using a first interpolation filter to filter the sampled signal. The method further includes using a second interpolation filter to filter the sampled signal. The method further includes using a first non-linear device to process an output of the first interpolation filter. The method further includes using a second non-linear device to process an output of the second interpolation filter. The method further includes performing a mathematical operation on an output of the first non-linear device with an output of the second non-linear device to generate phase information.

A method of evaluating OFDM synchronization between a transmitter and a receiver, the method carried out at the receiver and comprising, obtaining a non-coherent channel power estimate, obtaining a coherent channel power estimate, comparing the two estimates, and determining whether the receiver and the transmitter are synchronized based on the comparison.

Embodiments are disclosed for timing recovery used in conjunction with a phase detector embedded in a receiver of a communication system. An example method includes receiving, via a receiver of a communication system, an input signal. The input signal encodes a plurality of bits in a number of amplitude levels. The method further includes using an analog to digital converter to generate a sampled signal based on the input signal. The method further includes using a first interpolation filter to filter the sampled signal. The method further includes using a second interpolation filter to filter the sampled signal. The method further includes using a first non-linear device to process an output of the first interpolation filter. The method further includes using a second non-linear device to process an output of the second interpolation filter. The method further includes performing a mathematical operation on an output of the first non-linear device with an output of the second non-linear device to generate phase information.

Embodiments of the present application provide a method for acquiring information of access resources, a terminal device, and a base station. A terminal device detects a synchronization signal of a cell to be accessed by the terminal device. The terminal device further receives a broadcast channel of the cell on a broadcast channel resource. The terminal device then determines a resource on which the cell is located according to resource indication information carried in the broadcast channel. The broadcast channel resource corresponds to an actual access resource, and the synchronization signal is detected on the actual access resource. The actual access resource is one of a plurality of candidate access resources of the cell. The resource indication information indicates a location relationship between the actual access resource and the resource on which the cell is located.

The present disclosure relates to an adaptive mode switching method for simultaneous wireless power/information transmission operating in a dual mode and an apparatus for performing the same. The adaptive mode switching apparatus for simultaneous wireless power/information transmission operating in a dual mode includes: an energy harvesting unit; a single tone information receiving unit; a multi-tone information receiving unit; a time-division switch; and an adaptive mode switching control unit which determines a communication mode and a modulation index based on a battery status, the magnitude of the received signal, and a data transmission rate and controls the time-division switch in accordance with the selected communication mode and modulation index. It is possible to overcome a limited energy transmission area of simultaneous wireless power/information transmission (SWIPT) using a single tone in a low power IoT environment and a low transmission rate of a peak-to-average power ratio (PAPR)-based SWIPT using a multi-tone.

A method is provided to generate and control transmission of reference symbols in a synchronization subframe, wherein a reference symbol includes reference values mapped to a block of K subcarriers. The method includes generating data corresponding to a basic subsequence of KR1R2 reference values, where R1 and R2 are integers such that 1R1+R2<K, and mapping the data corresponding to the basic subsequence to an original range of KR1R2 contiguous subcarriers in the block such that there is a first set of R1 unmapped subcarriers above the original range of subcarriers and a second set of R2 unmapped subcarriers below the original range of subcarriers. Data corresponding to last R1 values in the basic subsequence is mapped to the first set of unmapped subcarriers. Data corresponding to first R2 values in the basic subsequence is mapped to the second set of unmapped subcarriers.

A method of evaluating OFDM synchronization between a transmitter and a receiver, the method carried out at the receiver and comprising, obtaining a non-coherent channel power estimate, obtaining a coherent channel power estimate, comparing the two estimates; and determining whether the receiver and the transmitter are synchronized based on the comparison.

A method for detecting times-of-arrival of signals comprising, at a receiving node: during a time slot, receiving a signal comprising a carrier signal characterized by a carrier frequency and modulated by a template signal defining a code sequence characterized by a transmitter chip period; demodulating the signal according to a local oscillator frequency to generate a received baseband signal, the local oscillator frequency and the carrier frequency defining a desynchronization ratio characterized by a denominator greater than a threshold denominator; sampling the received baseband signal at the transmitter chip period to generate a set of digital samples; generating a reconstructed baseband signal based on the set of digital samples; calculating a cross-correlation function comprising a cross-correlation of the reconstructed baseband signal and the template signal; and calculating, on the fine time grid, a time-of-arrival of the signal based on the cross-correlation function.

Prior art includes complex clock synchronization in 5G and 6G based on precision time measurements and multiple message exchanges. Disclosed is a simpler synchronization procedure suitable for reduced-capability receivers as well as high-performance users. The base station can transmit a brief signal on a specific subcarrier, surrounded fore and aft by silent periods, and the receiver can measure the signals in the silent periods to detect intrusion of the signal into one or the other silent periods, thereby indicating a timing offset. Alternatively, the base station can transmit a brief signal spanning an interface between subsequent symbol-times, and the receiver can measure the energy received in the two symbol-times, thereby detecting an offset. In either case, and other versions disclosed, the receiver can calculate the size and direction of the clock offset by amplitude measurements, and apply a correction without further communications between the user device and the base station.