The invention provides a frequency offset estimation method for an OFDM-IM system. The method includes: S1. performing preliminary frequency offset compensation on a received signal subjected to non-uniform frequency offset by using a two-step method of: (1) resampling and down conversion; and (2) unified compensation for residual frequency offset , wherein in the step (2), a sum of energy of null sub-carriers is used as a cost function, an initial estimation value of is obtained by one-dimensional search, and the preliminary compensation is performed; S2. estimating positions of non-activated sub-carriers in the OFDM-IM system by using the signal subjected to the preliminary compensation; and S3. assigning certain weights to the estimated sub-carriers, adding energy of the estimated sub-carriers into the cost function according to different weights, obtaining a final estimation value of by the one-dimensional search performed on , and performing secondary compensation.

Provided are a method and an apparatus for performing physical resource block (PRB) indexing in a wireless communication system. A user equipment (UE) receives information on an offset between a synchronization signal (SS) block and a system bandwidth from a network through the SS block and performs the PRB indexing on the system bandwidth on the basis of the information on the offset.

Methods, systems, and devices for wireless communications are described. In some wireless systems, different wireless devices may communicate using different radio access technologies (RATs) in a shared radio frequency spectrum. Prior to communicating on a channel in the shared radio frequency spectrum, a wireless device may transmit a training field as part of a preamble in a transmission on the channel to reserve the channel for the transmission. As described herein, a training field transmitted by a wireless device using one RAT may be transmitted with an autocorrelation property associated with training fields of another RAT. As such, a wireless device configured to communicate using the other RAT may be able to receive and identify the training field (e.g., based on the autocorrelation property), and the wireless device may use the additional techniques described herein to determine an availability of the channel based on the training field.

The present invention provides a method for estimating a sampling frequency offset of a receiver supporting ATSC 3.0 standard is disclosed. The method includes the steps of: receiving a bootstrap signal comprising a plurality of symbols; performing an autocorrelation operation on a first symbol of the plurality of symbols to generate a first correlation result; performing the autocorrelation operation on a second symbol of the plurality of symbols to generate a second correlation result; and determining the sampling frequency offset according to the first correlation result and the second correlation result.

Various embodiments relate to a method for processing received distributed multiple-input and multiple-output (DMIMO) OFDM signals from a plurality of transmitters, including: performing an initial carrier frequency offset (CFO) correction; receiving a plurality of OFDM symbols; re-constructing the channel every N symbols based upon a channel estimate for each transmitter and an estimate of residual CFO for each of the transmitters based upon the long term fields (LTF), wherein N is an integer; and equalizing the received OFDM symbols using the re-constructed channel.

The present invention relates to a method for transmitting and receiving a Physical Protocol Data Unit (PPDU) and an apparatus for supporting the same. Particularly, a method for transmitting a Physical Protocol Data Unit (PPDU) performed by an apparatus in a wireless communication system may include generating a High Efficiency-Short Training Field (HE-STF) sequence in a frequency domain throughout a transmission bandwidth of the PPDU and transmitting the PPDU that includes an HE-STF field which is constructed based on the HE-STF sequence, wherein the HE-STF sequence may be mapped to a data tone except a direct current tone and a guard tone, and wherein a non-zero value may be mapped to all data tones that include a tone index which is a multiple of a predetermined value in the data tone.

Disclosed herein are a synchronization apparatus and method for a upstream system. The synchronization apparatus for a upstream system includes one or more processors, and execution memory for storing at least one program that is executed by the one or more processors, wherein the at least one program is configured to receive a signal and calculate a first channel estimation value for the received signal using a predefined pilot, and calculate a second channel estimation value using a predefined complementary pilot and the first channel estimation value.

A receiver-implemented method is for measuring a periodically modulated signal. The method includes applying a received periodically modulated signal to a mixer of a receiver, the periodically modulated signal not synchronized with the receiver, and tuning a local oscillator (LO) of the mixer using an estimate of actual carrier frequency and an estimate of an arbitrary waveform generator (AWG) sampling rate to obtain a digitized intermediate frequency (IF) signal. The method further includes applying a short time Fourier transform (STFT) to the digitized IF signal, extracting a carrier frequency offset and a AWG sampling rate offset based on the applied STFT, compensating for the carrier frequency offset, and applying a digital correction to the STFT to compensate for the AWG sampling rate offset. Compensating for the carrier frequency offset may include retuning the LO to obtain a new digitized IF signal to which the digital correction is applied.

Provided are a method and an apparatus for performing physical resource block (PRB) indexing in a wireless communication system. A user equipment (UE) receives information on an offset between a synchronization signal (SS) block and a system bandwidth from a network through the SS block and performs the PRB indexing on the system bandwidth on the basis of the information on the offset.

Aspects of the present disclosure provide techniques for design of synchronization signals for narrowband operation and other clean-slate, OFDM based systems such as enhanced component carrier (eCC) systems. An example method is provided for operations which may be performed by a BS to generate and transmit a dual-layer PSS, and correspondingly, techniques for a UE to detect the dual-layer PSS. The PSS may be generated utilizing a binary code cover and at least one sequence applied to a number of symbols within one or more subframes of a frame.