Joint estimation of the framer index and the frequency offset in an optical communication system are described among various other features. A transmitter can transmit data frames using pilot and framer symbols. A receiver can estimate the framer index and frequency offset using the pilot and framer symbols, and identify the beginning of a header portion of a data frame. By identifying the beginning of the header portion of a data frame, the receiver can then process data received from the transmitter in a manner synchronous to the manner in which the data was transmitted by the transmitter.

Disclosed are a frequency offset estimation method and apparatus in an optical transmission network and a storage medium. The method comprises: acquiring a data symbol to be frequency offset estimated, and eliminating a noise phase, a phase generated by a light source and an information phase in the data symbol to be frequency offset estimated; and performing a correlation operation on a data symbol with a set interval in the data symbol after the elimination processing and using a correlation operation result to determine a frequency offset estimation value.

A method and apparatus for generating a sampling frequency are provided. A signal is generated, of which frequency is a predetermined multiple of a reference clock, and a frequency offset in a channel is extracted from the entire frequency offset. The amount of shift is calculated by dividing the extracted frequency offset by a predetermined value, and a final sampling frequency is obtained by shifting the frequency of the generated signal by the amount of shift.

A carrier-phase recovery method includes: (i) applying a first carrier-phase recovery algorithm to complex-valued symbols of a signal received by a product detector, yielding coarse phase-estimates, the signal being modulated per an M-QAM scheme; (ii) modelling the coarse phase-estimates as a weighted sum of M probability-density functions of an M-component mixture model; (iii) optimizing the M probability-density functions with an expectation-maximization algorithm to yield M optimized probability-density functions; (iv) mapping, based on the M optimized probability-density functions, the coarse phase-estimates to one of M symbols corresponding to the QAM scheme, each coarse phase-estimate mapped to a same symbol belonging to a same one of M clusters; (v) applying a second carrier-phase recovery algorithm to each of the M clusters to generate refined phase-estimates each corresponding to a respective coarse phase-estimate; and (vi) mapping, based on the M optimized probability-density functions, each refined phase-estimate to one of the M symbols.

A method for antenna calibration is disclosed, the method including driving calibration signals for antenna array beam calibration to an antenna array feeder line in a transceiver front end unit by using one or more directional couplers and/or radio frequency probes, wherein calibration signal paths are integrated inside the transceiver front end unit. Measurements are carried out on the calibration signals, between different antenna combinations inside the antenna array. Based on collected measurement data, calibration information is calculated for each measurement branch of the antenna array by using a mathematical formula. Active antenna array beam calibration is then performed based on the calculated calibration information.

A method to compensate a carrier frequency offset (CFO) in a receiver is disclosed. The method includes receiving discrete time samples, obtaining a sample vector from the received discrete time samples, obtaining tentative CFO estimates based on the sample vector, selecting a CFO having a greatest compensation coefficient from the tentative CFO estimates, and compensating the CFO in the received discrete time samples.

Methods, systems, and devices for wireless communication are described. A base station may broadcast a synchronization signal using a narrowband portion of a bandwidth of a cell. The synchronization signal may include a sequence repeated over several symbol periods using a cover code to support power-efficient cell acquisition. A user equipment (UE) receiving the synchronization signal may determine frequency and timing information for a cell by performing a weighted combination and accumulation of low complexity autocorrelation and cross-correlation procedures on the synchronization signal. The reduced complexity correlation procedures may be enabled based on the use of the cover code and a base sequence. In some cases, the cross-correlation may be performed at multiple sampling rates. The use of the cover code within the synchronization signal may also support correlation procedures that use recursive or repeated updates, which may allow for further reduced computational complexity relative to other cell search procedures.

Upon receipt of a coherent optical signal that includes a training signal generated using a code sequence constituted by multi-value phase modulation symbols, in which a deviation angle of a vector average of a one-symbol delay differential component of a signal generated on the basis of the code sequence has a prescribed angle and a modulation phase difference between adjacent symbols has a fixed, repeated pattern, a reception training signal corresponding to a training code sequence for frequency offset estimation is detected within a reception signal acquired by converting the received coherent optical signal into an electric signal, a plurality of delay differential components are calculated on the basis of the detected reception training signal and at least two delay signals of the reception training signal, each delay signal having a different number of delay symbols, and an averaged frequency offset amount is calculated using the calculated plurality of delay differential components.

Joint estimation of the framer index and the frequency offset in an optical communication system are described among various other features. A transmitter can transmit data frames using pilot and framer symbols. A receiver can estimate the framer index and frequency offset using the pilot and framer symbols, and identify the beginning of a header portion of a data frame. By identifying the beginning of the header portion of a data frame, the receiver can synchronize, with less error, the data transmitted by the transmitter and the data it received. To further improve the framer index estimation, a lock indicator signal can be generated to signal to other receiver components that the estimated framer indices are reliable. The receiver can determine frequency offset and additional framer index estimations with increased reliability when performed after the lock indicator signal is generated.

A method of performing carrier frequency offset (CFO) estimation and/or time offset (TO) estimation at a radio equipment in a mobile communications system. The method allows, for each of a plurality of synchronization signal (SS) blocks (SSBs) in a SS Burst detected at said radio equipment, determining a CFO estimation and/or a TO estimation based on network information signal prediction. The method includes selecting at least some of said detected SSBs in said SSB Burst and combining the CFO estimations and/or the TO estimations to obtain improved CFO compensation and/or TO compensation for signal processing at said radio equipment.