According to an embodiment, a communication repeater device includes storage and a controller which detects, upon receiving a radio frame including pairs of orthogonal frequency division multiplexing symbols and cyclic prefixes from the radio base station, switching timing between uplink and downlink according to similarity between certain sections of an original radio frame and a time-shifted radio frame. The controller estimates the subsequent switching timing between the uplink and the downlink from the detected switching timing and frame information stored in the storage.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a first synchronization signal for synchronizing with a cell, the first synchronization signal transmitted at a first periodicity by a base station serving the cell. The UE may then receive, subsequent to the synchronizing, a second synchronization signal for resynchronizing with the cell. In some cases, the second synchronization signal may be transmitted by the base station according to a second periodicity that is different from the first periodicity. In some cases, the second synchronization signal may include a plurality of repetitions of a first sequence that is based at least in part on a cell identifier of the cell. The UE may communicate over the cell with the base station based at least in part on the resynchronizing.

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 specification relates to a method for transmitting and receiving data in a wireless communication system supporting device-to-device (D2D) communication, and the method performed by a first terminal comprises the steps of: acquiring a resource pool used for D2D communication, wherein the resource pool includes either a scheduling assignment (SA) resource pool indicating a resource region through which an SA is transmitted or a data resource pool indicating a resource region through which D2D data is transmitted; transmitting, to a second terminal through the SA resource pool, the SA including information related to D2D data transmission; and transmitting the D2D data to the second terminal.

Methods and apparatus for frequency offset estimation are disclosed. In an exemplary embodiment, a method includes determining a demodulation reference signal (DMRS) frequency offset estimate from DMRS symbols in a received signal, and determining a cyclic prefix (CP) frequency offset estimate from cyclic prefix values in the received signal. The method also includes combining the DMRS and CP frequency offset estimates to determine a final frequency offset estimate. In an exemplary embodiment, an apparatus includes a DMRS frequency offset estimator that determines a DMRS frequency offset estimate based on DMRS symbols received in an uplink transmission, and a cyclic prefix (CP) frequency offset estimator that determines a CP frequency offset estimate based on cyclic prefix values in the uplink transmission. The apparatus also includes an offset combiner that combines the DMRS frequency offset estimate with the CP frequency offset estimate to generate a final frequency offset estimate.

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.

Systems and methods for blind detection of a numerology of a received signal are described. In one aspect, a method is provided for a user equipment (UE) to blindly detect the numerology of a received signal. The method includes correlating cyclic prefix (CP) signals in the received signal in the time domain based on a plurality of hypotheses of subcarrier spacing (SCS) and determining a numerology of the received signal for a corresponding hypothesis of SCS of the plurality of hypotheses based on the correlated CP signals.

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.

A Long Term Evolution (LTE) receiver performing a half cyclic prefix (CP) shift on received subframes is disclosed, comprising: an analog to digital conversion (ADC) module; a cyclic prefix (CP) removal module coupled to the ADC module configured to retain a portion of cyclic prefix samples; a fast Fourier transform (FFT) module configured to receive samples from the cyclic prefix removal module, and to perform a FFT procedure on the received samples using a FFT window, the FFT window being shifted ahead based on the retained portion of cyclic prefix samples, to output an orthogonal frequency division multiplexed (OFDM) symbol; and a rotation compensation module coupled to the FFT module, the rotation compensation module configured to perform phase de-rotation of the OFDM symbol.

A wireless device, such as an wireless access point, receives signals detected by a plurality of antennas of a wireless device to produce a plurality of antenna-specific receive signals potentially representing a wireless transmission received from each of one or a plurality of devices. A signal processing component of the wireless device, such as a modem, performs several operations on the antenna-specific receive signals, including building a first space-time equalizer to be applied to the plurality of antenna-specific receive signals to recover a transmission from a first device by both equalizing channel effects and canceling out effects associated with transmissions from devices other than the first device, and building a second space-time equalizer to be applied to the plurality of antenna-specific receive signals to recover a transmission from a second device by both equalizing channel effects and canceling out effects associated with transmissions from devices other than the second device.