An oscillator circuit that includes a voltage source, a resistor, a capacitor, and a nonlinear device. The capacitor and the nonlinear device may be coupled in parallel with one another. The resistor may be coupled in series with the capacitor and the nonlinear device. The voltage source may be coupled in series with the resistor. The voltage source may supply the oscillator circuit with a direct current input signal. The nonlinear device may include an active layer coupled to a first electrode and a second electrode. In response to the direct current input signal, the oscillator circuit may output a spike train including a spike bunch.

Demodulating a modulated signal. A method may include receiving a modulated signal, wherein the modulated signal is a signal modulated according to a modulation function varying faster than the signal. The modulation function is a function of the signal. The modulated signal received is demodulated with an artificial neural network system, or ANN system, which is trained to identify bit values from signal patterns as caused by the modulation function, by identifying bit values from patterns of the modulated signal received. Related modulation and demodulation systems are disclosed.

This application discloses a communications chip structure, including: a channel selection module, configured to receive an input signal, where the input signal is a signal of a preset narrow bandwidth span or a signal of a preset wide bandwidth span; and a digital baseband module, configured to control the channel selection module to select a first sampling and quantification channel when the input signal is a signal of the preset narrow bandwidth span, or control the channel selection module to select a second sampling and quantification channel when the input signal is a signal of the preset wide bandwidth span. The channel selection module is further configured to send the input signal to the first sampling and quantification channel or the second sampling and quantification channel for sampling and quantification.

Physical-layer security is provided by obfuscating or concealing the structure of the signal being transmitted, such that recovery of the underlying information is prohibitively expensive or even impossible. A digital filter implemented within a digital signal processor at the transmitter device introduces an obfuscation function. A digital filter implemented within a digital signal processor at the receiver device removes the obfuscation function. The obfuscation function conceals information bits to be conveyed by a modulated carrier signal. In some versions, the obfuscation function digitally modifies the phases of individual frequency components of the drive signals used to generate the modulated carrier signal. In other versions, the obfuscation function digitally modifies the phases and amplitudes of individual frequency components of the drive signals used to generate the modulated carrier signal.

A method for communicating magnetic resonance imaging (MRI) information wirelessly includes detecting an MRI system emission sequence, and identifying at least one parameter of the sequence. The at least one parameter identified is cross-correlated. A first initial condition for a first chaotic coded sequence and a second initial condition for a second chaotic coded sequence are determined based on the at least one parameter. The method further includes obtaining, from a modulation symbol mapped to MRI information generated at a local coil responsive to the sequence, a real component of the symbol and an imaginary component of the symbol. The real component of the symbol is encrypted based on the first initial condition, and the imaginary component of the symbol is encrypted based on the second initial condition. The encrypted real component and imaginary component of the symbol are wirelessly transmitted.

The present invention teaches a system and method for improved signal recovery for range and coverage extension in a heterogeneous cooperative network of digital chaos transmissions with OFDM component signal transmission. The invention improves upon the state of art in side channel information from the transmit side containing information on the clipped amplitude. In-band transmission of the side information is achieved by exploiting the sparsity of the resulting clip amplitude position with improved levels of compression over the prior art using Gabor Transform Multiple Symbol Encoding transmitter. The information rate of the clipped amplitude is sub-Nyquist relative to the original OFDM component signal transmission, which allows very low power spreading by a cooperative digital chaos sequences at a transmit side and recovery of the clipped amplitude at a receive side. Further, an improved noise resistance side channel performance is achieved by decoding Gabor Transform symbols for symbol recovery.

A reconstruction method for DCSK signals is provided. An information bit sequence to be transmitted is acquired, which is processed by serial-to-parallel conversion. A processed information bit sequence is input into a modulator for modulation to obtain a modulated signal matrix. Cross multiplication is performed between the modulated signal matrix and a chaotic signal to obtain an original information-bearing matrix, which is reconstructed according to a predetermined reconstruction matrix to obtain an information-bearing reconstruction matrix. A transmission symbol is generated according to the information-bearing reconstruction matrix and a reference signal matrix in combination with frame structure information of the transmission symbol, and is sent to a receiving end via a wireless network to demodulate a received signal according to a reconstruction matrix. A reconstruction device for DCSK signals is also provided.

A criterion method of GCCS (Globally Complete Chaos Synchronization) for three-node VCSEL (Vertical Cavity Surface Emitting Laser) networks with delay coupling is provided, including steps of: providing a delay-coupled VCSEL network consisting of three identical units and dynamic equations of the VCSEL network; providing assumptions of an outer-coupling matrix and a unitary matrix under the dynamic equations of the VCSEL network; in the three-node VCSEL network, determining rate equations of i-VCSEL, determining dynamic equations of a synchronization manifold, and determining a master-stability equation; calculating three maximum Lyapunov exponents; determining a stability of a synchronization state of the three-node VCSEL network, and determining whether the synchronization manifold of the VCSEL network is a chaotic waveform. Through a master-stability function, the method for determining whether the GCCS is achieved among all node lasers is provided, which solves a difficult problem of GCCS criterion for the VCSEL networks.

Aspects described herein relate to generating, using an initial seed and a pseudo-random shift value, a scrambling sequence, scrambling, using the scrambling sequence, one or more codewords as part of generating a baseband signal for a wireless communication channel, and transmitting the baseband signal to a network node.

Example communication systems and methods are described. In one implementation, a method receives a first chaotic sequence of a first temporal length, and a second chaotic sequence of a second temporal length. The method also receives a data symbol for communication to a destination. Based on the data symbol, the second chaotic sequence is temporally shifted and combined with the first chaotic sequence to generate a composite chaotic sequence. The first chaotic sequence functions as a reference chaotic sequence while the second chaotic sequence functions as a data-carrying auxiliary chaotic sequence.