A free-space optical communication system includes a transmitter and a receiver, the transmitter being configured to transmit an encrypted message to the receiver at the mid-infrared domain, the transmitter comprising a master mid-infrared optical source configured to generate a mid-infrared signal and a chaos generator configured to generate a chaotic signal by applying external optical feedback to the master mid-infrared optical source, the transmitter being configured to determine an encrypted message from an original message by applying a message encryption technique to the original message and to send the encrypted message to the receiver through an optical isolator, the receiver comprising a slave mid-infrared optical source similar to the master mid-infrared optical source the slave mid-infrared optical source being configured to recover the chaotic signal from the encrypted message by applying chaos synchronization, the receiver further comprising a first detector configured to detect the encrypted message, a second detector configured to detect the chaotic signal, and a message recovery unit configured to recover the original message from the encrypted message detected by the first detector and the chaotic signal detected by the second detector.

The present disclosure discloses a signal sending method and device. The method includes: receiving, by a base station, an uplink pilot signal sent by authorized user equipment, and determining a direction vector parameter and a first channel fading parameter of a channel calculating, according to the direction vector parameter and the first channel fading parameter, a first signal beamformer parameter, determining a transmission area of an artificial noise signal according to the direction vector parameter, and calculating a second signal beamformer parameter; and processing a to-be-transmitted signal by using the first signal beamformer parameter and the second signal beamformer parameter, and transmitting the processed signal. In this way, in a non-target direction, energy leakage of the secrecy signal to the authorized user equipment is relatively small, and transmitted artificial noise signals are concentrated in an area with a relatively high secrecy signal leakage risk.

Disclosed is an electronic device. The electronic device includes a communicator comprising communication circuitry and a processor, the processor is configured to control the communicator to perform communication with an external device based on identifying that a strength of a signal received from an external device is equal to or greater than a predetermined threshold value, and after converting an electronic device to a low power mode, based on identifying that a strength of a signal received from an external device being within a first range, to control the electronic device to perform a secure pairing operation.

Techniques, methods and system, for synchronization of sparse data signals are disclosed, comprising mixing a serial stream of sparse data signals with a serial stream of synchronization signals, to thereby add redundancy to the serial stream of sparse data signals and enable clock regeneration from a serial stream of mixed signals produced by said mixing, emulating the serial stream of synchronization signals by applying the clock regeneration to the serial stream of mixed signals, and generating a stream of parallel synchronization signals having a frequency of the serial stream of synchronization signals, deserializing the serial stream of mixed signals into a stream of parallel mixed signals having a data rate lower than a data rate of the serial signal streams, and demixing the stream of parallel synchronization signals with the stream of parallel mixed signals and thereby removing the redundancy introduced by the mixing into the sparse data signals and generating a parallel stream of demixed signals substantially synchronized with said synchronization signals.

The present disclosure relates to a method, apparatus, and computer program for setting an encryption key in a wireless communication system; and a recording medium for same. According to one embodiment of the present disclosure, a method for setting an encryption key size in a wireless communication system may comprise: a step in which a first controller of a first device receives a first message containing information on a minimum value of a first encryption key size from a first host of the first device; and a step in which the first controller transmits, to the first host, a second message indicating an encryption change. The second message may contain information on the first encryption key size.

A method for generating digital quantum chaotic orthonormal wavepacket signals includes the following steps: construct a N-dimensional Hermitian matrix Ĥ; calculate N eigen-wavefunctions φ.sub.j of a quantum Hamiltonian system with the Hamiltonian Ĥ by some numerical calculation methods, wherein the Hamiltonian is the Hermitian matrix Ĥ; extract some or all of the eigen-functions φ.sub.j with obvious chaos features as quantum chaotic eigen-wavefunctions according to a chaos criterion; generate some semi-classical digital quantum chaotic wavepacket signals φ.sub.j(n) with the same mathematical form as the quantum chaotic eigen-wavefunctions and length N from the selected quantum chaotic eigen-wavefunctions according to the mathematical correspondence between the classical signal and the wavefunction in quantum mechanics. By combining the quantum state chaotic transition theory and the classical time-frequency analysis, some semi-classical quantum chaotic wavepacket digital signals are generated according to the mathematical correspondence between the classical time-frequency signal and the wavefunction in quantum mechanics.

Sequences to synchronize devices and related methods are disclosed herein including an access address generator to cryptographically generate a first bit sequence, an access address selector to read a first portion of the first bit sequence and read a second portion of the first bit sequence, the second portion different than the first portion, an access address analyzer to identify a first access address from a first section of the first portion based on a first criteria, the first criteria a function of a first autocorrelation function and identify a second access address from a second section of the second portion based on a second criteria, the second criteria a function of a second autocorrelation function.

A differential chaos shift keying communication method based on hybrid index, including: modulating a transmitted signal based on the hybrid index; and demodulating a received signal based on the hybrid index. The hybrid index is a hybrid index bit, which includes a carrier index bit and a carrier number index bit. This application also provides a system for implementing the differential chaos shift keying communication method, which includes a transmitter and a receiver.

The present invention relates to a generation of a signal by executing a waveform dataset comprising waveform descriptive parameters. The execution of the waveform description parameters is limited by target device information specifying one or more specific target devices and time information specifying an execution period of the waveform descriptive parameters. By providing a waveform dataset comprising not only the waveform descriptive parameters, but also further information, in particular time information for limiting the execution period of the waveform descriptive parameters, the generation of the respective waveform signal is controlled.

The invention is a scrambler apparatus for scrambling a character block, in particular for cryptographic applications, which apparatus comprises a scrambler module (210) adapted for transforming a first character block (220a) consisting of first character components (225a) to a scrambled second character block (220b) consisting of second character components (225b), configured with a scrambler automaton (250), and each second character component (225b) is determined based on a first character component (225a) of the first character block (220a) having the position corresponding to the position of the given second character component (225b), at least one character component (225a, 225b) from the available character components (225a, 225b) of the first character block (220a) and the second character block (220b), and a single input signal character component (225c) of the input signal character block (220c). The invention is, furthermore, a scrambling method, a descrambler apparatus and a descrambling method.