4 results about "Doppler rate" patented technology

Embodiments of this application provide a wireless communication method and an apparatus. The method includes: A first communication apparatus receives first information, where the first information indicates a determining threshold of a parameter in a first parameter set, and the first parameter set includes at least one of the following parameters: location information, delay information, a timing advance rate, a rate of the timing advance rate, a Doppler value, a Doppler rate, and remaining coverage time. The first communication apparatus determines, based on the first information, whether an access condition is met, and performs random access when the access condition is met. This avoids a random access failure in a current cell and re-access in a next cell due to random access performed when the condition is not met.

This invention discloses a secure transmission method for satellite constellation communication based on post-quantum cryptography, relating to the fields of satellite communication and information security technology. The method includes: analyzing the satellite constellation topology to determine the latency sensitivity level of the secure handshake; pre-screening a set of candidate PQC algorithms based on the sensitivity level; sensing the channel and extracting non-stationary features such as fading depth, duration, and Doppler rate of change; constructing a multi-dimensional joint optimization model with algorithm identifier, fragmentation granularity, redundancy, and modulation and coding scheme as joint decision variables, aiming to maximize the handshake probability within the expected duration; solving the model to generate an adaptive transmission strategy, and performing adaptive non-uniform fragmentation and fountain code encoding on PQC protocol data units; predicting link trends based on Doppler rate of change and dynamically scheduling symbol transmission. This invention achieves deep coupling optimization of network topology, cryptographic algorithms, and channel characteristics, improving the transmission reliability of PQC in dynamic satellite networks.

The invention belongs to the field of satellite navigation, and particularly relates to a space-frequency anti-interference method based on self-adaptive null broadening, which comprises the following steps: converting a digital intermediate frequency signal into a frequency domain signal through windowing and discrete Fourier transform, and calculating a covariance matrix in a conventional operation scene; the Doppler change rate is adopted to identify a current motion scene, so that whether matrix reconstruction is carried out or not is judged, and an adaptive null broadening function is realized; and performing spatial filtering on each narrow sub-band, and transforming a frequency domain signal back to a time domain signal by using inverse discrete Fourier transform and inverse window to obtain anti-interference data. According to the method, the Doppler change rate is innovatively introduced into null broadening for self-adaptive judgment, the problem of mismatching of the null depth and the interference coming direction in special motion scenes such as a large off-axis attitude is solved, meanwhile, the anti-interference limit performance in a conventional operation scene is not affected, and the self-adaptive capacity of the anti-interference navigation terminal is effectively improved.

The application relates to a method of estimating a location of a source of an electromagnetic signal. Also disclosed is a system comprising apparatus for carrying out the method, and a computer-readable medium storing a computer program for carrying out the method. The method includes: obtaining a first set of equations that, for each of a plurality of receivers of the electromagnetic signal, relate time of arrival (TOA), frequency of arrival (FOA), and Doppler rate of arrival (DROA), to a range between the source and the particular one of the plurality of receivers; selecting a candidate source location in three-dimensional space; obtaining a second set of equations by transforming each of the first set of equations based on a displacement vector; based on the second set of equations, obtaining a set of difference equations comprising, for each of a number of pairs of the receivers, respective equations representing a time difference of arrival (TDOA) between the pair, a frequency difference of arrival (FDOA) between the pair, and a Doppler rate difference of arrival (DRDOA) between the pair; obtaining a plurality of datasets, each dataset comprising successive data samples representative of the electromagnetic signal as received at a respective one of the receivers; comparing pairs of the datasets to determine respective measured TDOA, FDOA and DRDOA values; solving the set of difference equations by searching for a displacement vector that minimises a cost function; and iteratively arriving at an estimate of the location of the signal source.