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.

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.

Systems and methods for transmitting data using various Modulation on Zeros schemes are described. In many embodiments, a communication system is utilized that includes a transmitter having a modulator that modulates a plurality of information bits to encode the bits in the zeros of the z-transform of a discrete-time baseband signal. In addition, the communication system includes a receiver having a decoder configured to decode a plurality of bits of information from the samples of a received signal by: determining a plurality of zeros of a z-transform of a received discrete-time baseband signal based upon samples from a received continuous-time signal, identifying zeros that encode the plurality of information bits, and outputting a plurality of decoded information bits based upon the identified zeros.

Disclosed is a low-complexity linear equalization method for an Orthogonal Time Frequency Space (OTFS) system. The method may include: receiving a time domain signal passing through a linear time-varying (LTV) channel; sampling the time domain signal to obtain a sampled signal; demodulating the sampled signal to obtain a demodulated signal; performing a Symplectic Finite Fourier Transform (SFFT) on the demodulated signal to obtain a sampled delay-Doppler domain signal; determining an effective channel matrix in a delay-Doppler domain under a restriction of a rectangular window according to a time domain channel matrix; determining a linear equalization matrix according to the effective channel matrix; and equalizing the sampled delay-Doppler domain signal in a low-complexity way according to the linear equalization matrix. The disclosure also discloses a linear equalization device of an OTFS system for realizing the linear equalization method and a computer-readable storage medium.

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.

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 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.

Methods and systems for modulating and demodulating data in systems is described. An Inverse Fast Fourier Transform (FFT) can be applied to complex-valued symbols that represent bit groups. The FFT can be replaced with a Fast Accurate Fourier Transform (FAFT) that can comprise variable size signal windows.

Numerous Clos Star Networks (CSNs), each constructed as a set of connectors providing single-hop paths for each pair of access nodes of a respective access group, are fused to form a large-scale global network providing at least one single-hop path for each pair of access nodes of the formed global network. The access groups are arranged into access bands of multiple access groups each. Connectors of CSNs are paired to form distributors so that each access node has multiple parallel single-hop paths to each other access node of the same access band and one single-hop path to each access node of each other access band. The distributors are clustered into a set of geographically-spread constellations and each access node of the global network has a direct multichannel link to each of a respective subset of constellations thus entirely eliminating use of cross connectors and significantly simplifying the network structure.

An electronic device and communication method are disclosed. The electronic device comprises a processing circuit configured to perform a pre-processing operation on a first one-dimensional sequence of modulation symbols, the pre-processing operation including: performing a dimension-increasing conversion to convert the first one-dimensional sequence of modulation symbols into a first multi-dimensional modulation symbol block; transforming the first multi-dimensional modulation symbol block into a second multi-dimensional modulation symbol block with a first transformation, wherein the first transformation couples each symbol in the first multi-dimensional modulation symbol block with each other; and performing a dimension-decreasing conversion to convert the second multi-dimensional modulation symbol block into a second one-dimensional sequence of modulation symbols, wherein the dimension-decreasing conversion is an inverse process of the dimension-increasing conversion. The processing circuit is also configured to transmit the second one-dimensional sequence of modulation symbols.