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.

A method for operating a data processing system to determine the actual frequency of a transmitter LO in a transmitter that up converts a repetitive input time domain signal to a repetitive RF signal is disclosed. The method includes receiving a repetitive RF signal resulting from up converting the input time domain signal and assuming a value for the transmitter LO frequency. The received signal is down converted to an IF signal using the transmitter LO frequency, and digitizes to form a time domain record, The time domain record is converted to a sequence of frequency spectra, each frequency spectrum is characterized by a time index and a plurality of plurality of phasors. The frequency difference between the assumed LO transmitter and an actual LO transmitter frequency is determined by fitting the sequence of frequency spectra to a phase tracker function of the time index and the frequency difference.

A method for operating a communications system includes transmitting a preamble sequence including a plurality of tones. Each tone of the plurality of tones has a first characteristic and a second characteristic. The first characteristic of each of the tones of the plurality of tones has a predetermined relative relationship to the first characteristic of each of the other tones of the plurality of tones and the second characteristic of each of the tones of the plurality of tones has a predetermined relative relationship to the second characteristic of each of the other tones of the plurality of tones. The first and second characteristics may include relative power and relative phase.

The present invention relates to a method for transmitting and receiving, by a station, signals in a wireless WLAN system. More particularly, the present specification proposes a frame structure for transmitting signals by bonding a plurality of channels by the station, and a method for transmitting and receiving signals on the basis of the same frame structure, and an apparatus therefor.

A transmitter for transmitting data to communications devices via a wireless access. The transmitter including modulator circuitry configured to receive modulation symbols of a segment and to rotate each modulation symbol by an angle dependent on a choice of modulation scheme, and receive each of the segments of rotated modulation symbols and for each segment to separate real and imaginary components of the rotated modulation symbols for the segment and to interleave the real components of the rotated modulation symbols of the segment differently to the imaginary components of the rotated modulation symbols of the segment. The circuitry also is configured to recombine the real and imaginary interleaved components of the rotated modulation symbols of each segment and to form from the real and imaginary components modulation cells.

A device for estimating frequency offsets which is performed by periodically transmitting training signals from a wireless local area network system. The device includes a processor and computerized codes stored in a storage unit. The processor is configured to execute the computerized code to perform a method. The method includes receiving the plurality of training signals, selecting selected training signals by a predetermined interval from the received training signals, detecting and storing phases of the selected training signals, averaging phase differences of every pair of the detected phases of the selected training signals, calculating the frequency offsets according to an average of the phase differences for every pair of the detected phases of the selected training signals, and calculating a weighted average of the calculated frequency offsets using weighting values for each of the calculated frequency offsets.

Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter applies a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.

A method and an apparatus for secondary synchronization in the Internet of things. The receiving apparatus extracts a frequency domain sample by applying channel estimation to a time domain sample of the secondary synchronization signal. Further, the receiving apparatus estimates a physical cell ID (PCI) and 80 ms frame timing (FT) based on decorrelation between a frequency domain standard signal of the secondary synchronization signal and the frequency domain sample.

An HE-LTF transmission method is provided, including: determining, based on a total number N.sub.STS of space-time streams, a number N.sub.HELTF of OFDM symbols included in an HE-LTF field; determining a HE-LTF sequence in frequency domain according to a transmission bandwidth and a mode of the HE-LTF field, where the HE-LTF sequence in frequency domain includes but is not limited to a mode of the HE-LTF field sequence that is in a 1 mode and that is mentioned in implementations; and sending a time-domain signal according to the number N.sub.HELTF of OFDM symbols and the determined HE-LTF sequence in frequency domain. In the foregoing solution, a PAPR value is relatively low.

Disclosed in the present disclosure are an uplink synchronization timing deviation determination method and device, for solving the problem in the prior art that a base station in an NB-IoT system has low accuracy in determining an uplink synchronization timing deviation by performing FFT and IDFT processing on a preamble sequence. The method specifically comprises: a base station receiving a preamble signal transmitted by a terminal device; determining channel estimation values of a frequency domain channel occupied for transmitting each symbol group of the preamble signal; performing, on the basis of a frequency hopping pattern used for transmitting the preamble signal, a conjugate multiplication on the channel estimation values corresponding to each symbol group to obtain a first radian value, and determining, on the basis of the first radian value, an uplink synchronization timing deviation of the terminal device.