Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Methods, systems, and devices for wireless communication are described that support communication of information buts based on reference signal index modulation (RS-IM). A base station and a UE may transmit a number of downlink and uplink information bits (e.g., downlink control bits, uplink control bits) using index modulation schemes applied on references signals. A base station and a UE may transmit reference signal transmissions using reference signal index modulation, in which a set of information bits may be encoded using one or more coding techniques, in conjunction with RS-IM techniques, to enhance reliability of some or all of the information bits. Error detection bits may be added to the information bits, and included when coding is performed. Coding may include channel coding, repetition of reference signals for combining at a receiving device, or any combinations thereof.

Provided are a data sending method and apparatus, a data receiving method and apparatus, a data transmission system, and a storage medium. The data sending method includes: a first data stream is acquired, where the first data stream includes multiple coded data symbols; an N-dimensional orthogonal transformation is performed on the first data stream to obtain an orthogonally transformed first data stream, where N≥2; a modulation processing is performed on the orthogonally transformed first data stream to obtain a first radio frequency signal; and the first radio frequency signal is sent.

A broadcast signal receiver includes a tuner for tuning a broadcast signal, a reference signal detector for detecting pilots from the tuned broadcast signal, a de-framer for de-framing a signal frame of the broadcast signal and deriving service data based on a number of carriers of the signal frame, and a decoder for performing error correction process on the derived service data.

The present disclosure discloses a method and a system for transmitting DFT-s-OFDM symbols. A data sequence for transmitting as an OFDM symbol is received as input from a data source. A reference sequence for transmitting along with the data sequence as the OFDM symbol is generated and time-multiplexed with the data sequence, to generate a multiplexed sequence. Thereafter, a Discrete Fourier Transform (DFT) operation is performed on the multiplexed sequence to generate a DFT-spread-Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) symbol that is further processed for transmitting over a channel. The transmission of the reference sequence and the data sequence in a single OFDM symbol provides better bandwidth utilization and flexibility in modulation of the reference sequence and the data sequence.

A radio communication apparatus (100) according to the present disclosure includes a first frequency domain conversion unit (1) configured to convert a reception signal into a first frequency domain signal, a bandwidth restriction unit (2) configured to restrict a bandwidth by extracting a first number of points corresponding to a frequency bandwidth of a desired signal from the first frequency domain signal, a time domain conversion unit (3) configured to convert the signal with the restricted bandwidth into a time domain signal with the first number of points, a symbol reconstruction unit (4) configured to reconstruct symbols from the time domain signal, and a second frequency domain conversion unit (5) configured to convert each of the reconstructed symbols into a second frequency domain signal with the first number of points. Thus, a radio communication apparatus that can efficiently perform signal processing is provided.

Data acquisition in a chirp spread spectrum (CSS) signal may use a data alignment indicator of a single down chirp signal or single upchirp signal. A receiver may receive part or all of a preamble comprising a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT), and the values from the FFT may be accumulated. The accumulated values may exceed a threshold for detection. The receiver may align, based on the received chirps of the preamble and exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment. Upon receipt of the opposite chirp, the receiver may start data acquisition based on chirps following the single opposite chirp.

A receiver for detecting and recovering payload data from a received signal comprises a radio frequency demodulation circuit, a detector circuit and a demodulator circuit. The radio frequency demodulation circuit detects the received signal. The received signal carries the payload data as OFDM symbols in one or more of a plurality of time divided frames, each frame including a bootstrap signal, a preamble signal and a plurality of sub-frames. The demodulator circuit detects bootstrap OFDM symbols to identify communications parameters for detecting the fixed length signalling data, detects the fixed length signalling data to identify the communications parameters for detecting the variable length signalling data, detects the variable length signalling data, and uses the fixed and variable length signalling data to detect the payload data.

A chirp spread spectrum (CSS) receiver may reject, based on a data alignment chirp that includes an identifier that is a mismatch to a preconfigured identifier, a message early and before fully receiving/decoding the message. A receiver may receive a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT) and the resulting values accumulated. The receiver may align, based on the received chirps of the preamble and the accumulated values exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment and comprise an encoded identifier. The receiver may reject the message and terminate further message processing based on the encoded identifier being a mismatch to a preconfigured identifier.

A system includes a hardware accelerator configured to perform a two-dimensional (2D) fast Fourier transform (FFT) on an M×N element array. The hardware accelerator has log.sub.2 M×N pipeline stages including an initial group of log.sub.2 M stages and a final group of log.sub.2 N stages. Each stage includes a butterfly unit, a FIFO buffer coupled to the butterfly unit, and a multiplier coupled to the butterfly unit and to an associated twiddle factor table. The hardware accelerator also includes butterfly control logic to provide elements of the M×N element array to the initial group of stages in an N direction of the array, and twiddle factor addressing logic to, for the twiddle factor tables of the initial group of stages, apply an indexed entry of the twiddle factor table to the associated multiplier. The indexed entry begins as a first entry and advances by N entries after every N cycles.