Provided are a data transmission method and apparatus, a sending end sends data to a receiving end on one or more orthogonal frequency division multiplexing (OFDM) symbols in a scheduling unit, and the receiving end receives data sent by the sending end on one or more OFDM symbols in the scheduling unit. A time length of the scheduling unit is a length of two long term evolution (LTE) OFDM symbols having normal cycle prefixes and a subcarrier spacing of 15 kHz, the scheduling unit is formed by seven or eight OFDM symbols having a subcarrier spacing of 60 kHz, the scheduling unit is maintained to be the seven OFDM symbols having a subcarrier spacing of 60 kHz and having new extended cycle prefixes.

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.

A method and apparatus for generating a preamble symbol in an Orthogonal Frequency Division Multiplexing (OFDM) system by generating a first main body sequence in a time domain by performing an inverse fast Fourier transform (IFFT) on a preset sequence in a frequency domain, generating a first postfix by copying samples in a preset section in the first main body sequence, generating a first prefix by copying samples in at least a portion of a section remaining by excluding the preset section from the first main body sequence, and generating a plurality of symbols, based on a combination of the first main body sequence, the first prefix, and the first postfix.

Devices and methods of transmit opportunity (TXOP) with continued listen-before-talk (LBT) are generally described. A user equipment (UE) can be configured to perform a single LBT during an LBT scanning instance, to detect availability of an unlicensed wireless channel. Upon detecting availability of the channel, data is encoded for transmission during a TXOP with a TXOP duration. A pause in the transmission of the data is initiated upon expiration of a first time interval of the TXOP. A continuous LBT procedure is performed upon expiration of the pause, to determine a plurality of sensing metrics indicating occupancy of the unlicensed wireless channel. The transmission of the data is resumed during the TXOP for a second time interval, when at least one sensing metric of the plurality of sensing metrics is below a threshold.

A modem circuit associated with a communication system is disclosed. The modem circuit comprises a symbol tracking circuit configured to track a symbol timing associated with a downstream (DS) channel associated with the modem circuit, in accordance with a timing offset estimate. In some embodiments, the timing offset estimate comprises a unified timing offset derived based on one or more external channels associated with the modem circuit that is different from the DS channel. The symbol tracking circuit is further configured to apply a sample rate correction to a DS signal associated with the DS channel, based on the timing offset estimate comprising the unified timing offset, and apply a frequency correction to the DS signal, based on a frequency offset estimate comprising a unified frequency offset derived based on the one or more external channels.

Methods, systems, and devices for wireless communications are described to enable base station and a user equipment (UE) to mitigate interference when using full-duplex communications. For example, a base station communicating with a UE via full-duplex communications may indicate for the UE to align the time of its uplink transmissions with the time the UE receives downlink transmissions. Additionally or alternatively, the base station may indicate a timing alignment window for the UE, where the window may consist of an allowed time period the UE may use to select a time to begin uplink transmissions. In some examples, the base station may select a cyclic prefix for full-duplex communications, where the cyclic prefix may be longer than a cyclic prefix used for other communications. Further, the base station may select uplink frequency and downlink frequency bands separated by a defined guard band for full-duplex communications.

A method for transmitting a random access preamble in a narrowband-IoT system supporting time division duplexing and an apparatus therefor. In some implementations, a method for transmitting a narrowband physical random access channel (NPRACH) preamble by a user equipment in a narrowband-Internet of things (NB-IoT) system supporting time division duplexing may include: receiving, from a base station, configuration information related to an uplink-downlink configuration; and transmitting, to the base station, the NPRACH preamble configured by considering the uplink-downlink configuration.

A backhaul radio is disclosed that operates in multipath propagation environments such as obstructed LOS conditions with uncoordinated interference sources in the same operating band. Such a backhaul radio may use adaptive beamforming and sample alignment at the transmitter to enhance the link performance. Such backhaul radios may communicate with each other to compute and apply optimal beamforming parameters for a particular propagation environment through a closed-loop feedback mechanism.

A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols. The transmitter comprises a frame builder configured to receive the payload data to be transmitted and to receive first signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data and the first signalling data into frames for transmission, the first signalling data forming a part of the frames with the payload data. A modulator is configured to modulate a first OFDM symbol with the first signalling data and to modulate one or more second OFDM symbols with the payload data. A signature sequence processor provides a signature sequence, a combiner combines the signature sequence with the first OFDM symbol, and a transmission unit transmits the first and second OFDM symbols. The signature sequence provided by the signature sequence processor comprises at least one of a first synchronisation sequence or a second message sequence, the first synchronisation sequence and or the second message sequence being combined by the combiner with the first OFDM symbol. The first synchronisation sequence is provided for a receiver to detect and to recover the first signalling data from the first OFDM symbol and the second message sequence provides message information to the receiver. The message information may be used to convey a specific message to a user such as an emergency warning relating to a natural disaster such as an earthquake or a tsunami warning.

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.