A synchronizer can include a symbol estimator, an inner-pattern de-mapper, a timing tracker, and a correlator. The symbol estimator can be configured to estimate one or more symbols of a received signal based on a phase signal. The inner-pattern de-mapper can be configured to de-map the one or more symbols to generate an inner-pattern de-mapped symbol estimation. The timing tracker can be configured to accumulate the inner-pattern de-mapped symbol estimation and to determine a peak position based on the accumulated inner-pattern de-mapped symbol estimation. The correlator can be configured to correlate the accumulated inner-pattern de-mapped symbol estimation based on a reference signal. The correlation of the accumulated inner-pattern de-mapped symbol estimation can be independent of a signal over sampling rate (OSR). The synchronizer can be adapted in a long range Bluetooth low energy (BLE) receiver.

A digital television (DTV) receiving system includes an information detector, a resampler, a timing recovery unit, and a carrier recovery unit. The information detector detects a known data sequence which is periodically inserted in a digital television (DTV) signal received from a DTV transmitting system. The resampler resamples the DTV signal at a predetermined resampling rate. The timing recovery unit performs timing recovery on the DTV signal by detecting a timing error from the resampled DTV signal using the detected known data sequence. The carrier recovery unit performs carrier recovery on the resampled DTV signal by estimating a frequency offset value of the resampled DTV signal using the detected known data sequence.

Adaptive payload extraction in wireless communications involving multi-access address packets are described herein. A device can be configured to detect a synchronization sequence of a nested data packet, the nested data packet having synchronization sequences placed in series ahead of a payload, the synchronization sequences including the synchronization sequence; evaluate blocks after the synchronization sequence in the nested data packet to identify the blocks as either additional ones of the synchronization sequences or the payload in the nested data packet; and extract the payload.

Synchronizing a pulse position modulation (PPM) signal. A method includes performing a first synchronization operation by receiving a first series of symbols. The symbols in the first series are transmitted with a pulse in a known slot, such that the symbols comprise pulses that are substantially equally spaced in time from adjacent symbols. The first synchronization operation includes identifying when each pulse is received for each of the symbols and using information identifying when each pulse is received for each of the symbols in the first series of symbols to identify symbol and slot boundaries for the pulse position modulation signal. The method further includes performing a second synchronization operation by receiving a second series of symbols transmitted in a known pattern, and identifying the known pattern in the received second series of symbols to identify a frame boundary.

Methods, systems, and devices for wireless communications are described. A base station may transmit an indication of a demodulator configuration to a user equipment (UE) for the UE to use that demodulator configuration for demodulating a multi-layer transmission from the base station. The base station may determine the demodulator configuration for the UE to use based on one or more uplink signals transmitted from the UE. Additionally, the UE may transmit an indication of demodulator capabilities that the UE supports to the base station, where the base station determines the demodulator configuration based on the indication of the demodulator capabilities. In some examples, the demodulator configuration may indicate a demodulation search space corresponding to a number of layers included per layer group of the multi-layer transmission, may correspond to an amount of cross correlation determined between respective layers of the multi-layer transmission, or a combination thereof.

Examples described herein include systems and methods which include wireless devices and systems with examples of cross correlation including symbols indicative of radio frequency (RF) energy. An electronic device including a statistic calculator may be configured to calculate a statistic including the cross-correlation of the symbols. The electronic device may include a comparator configured to provide a signal indicative of a presence or absence of a wireless communication signal in the particular portion of the wireless spectrum based on a comparison of the statistic with a threshold. A decoder/precoder may be configured to receive the signal indicative of the presence or absence of the wireless communication signal and to decode the symbols responsive to a signal indicative of the presence of the wireless communication signal. Examples of systems and methods described herein may facilitate the processing of data for wireless communications in a power-efficient and time-efficient manner.

The present disclosure provides a signal sampling method and apparatus, and an optical receiver. The method includes sampling a burst signal that is received according to a first sampling frequency to obtain a first sampling signal; sampling a preamble signal in the first sampling signal according to a second sampling frequency to obtain a second sampling signal; determining a phase difference between the burst signal and a local sampling clock corresponding to the first sampling frequency according to the second sampling signal; and interpolating the first sampling signal according to the phase difference to obtain a target sampling signal.

In one implementation, a receiver has a module to calculate the cross-correlation between a portion of a digital representation of a received signal and a reference signal. The receiver also has a module to generate an estimate of a portion of a message potentially included in the digital representation of the received signal and a screening module to determine the likelihood that the received signal includes a message. For a received signal that is determined likely to include a message, the receiver includes a carrier refinement module to shift the frequency of carrier pulses in the digital representation of the received signal toward a desired frequency and to align the phase of carrier pulses in the digital representation of the received signal with a desired phase and a coherent matched filter to recover the message from the digital representation of the received signal.

A radio apparatus is configured to correlate signal data with stored synchronization data to generate synchronization correlation data. The signal data represents a received radio-frequency signal that encodes a data frame having a synchronization preamble comprising a plurality of instances of a predetermined synchronization sequence. The stored synchronization data represents the predetermined synchronization sequence. The synchronization correlation data is generated by correlating signal data representing the synchronization preamble with the stored synchronization data. While generating the synchronization correlation data, the radio apparatus identifies a first set of one or more peaks in the synchronization correlation data, and determines first synchronization information from the first set of one or more peaks. After generating more of the synchronization correlation data, the radio apparatus identifies a second set of one or more peaks in the synchronization correlation data, and determines second synchronization information from the second set of one or more peaks.

A radio apparatus correlates signal data with stored synchronization data to determine correlation data. The signal data represents a received radio-frequency signal that encodes a data frame, which has a synchronization preamble with a plurality of instances of a predetermined synchronization sequence. The stored synchronization data represents the predetermined synchronization sequence. The radio apparatus identifies a set of peaks in the correlation data, and uses a timing criterion to identify a plurality of subsets of the set of peaks, such that time values of the peaks of each identified subset satisfy the timing criterion. The radio apparatus calculates a correlation score C.sub.j for each of the identified subsets from correlation values of the subset's peaks, and uses the correlation scores C.sub.j to select a subset from the plurality of subsets. Timing or frequency synchronization information for the radio apparatus is determined from the peaks of the selected subset.