The present invention teaches method and apparatus to transform a featureless, unpredictable, and non-repeatable chaos waveform into digital chaos waveforms that maintain featureless characteristics to serve as a for wireless communications protocol, whereby unintended observers cannot detect or disrupt yet imprint a small measure of predictability and repeatability to aid intend observers in recovering embedded information.

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.

Various embodiments are described that relate to a switched-capacitor in a chaotically modulated communication device. For one chaotically modulated communication device to communicate with another chaotically modulated communication device, the devices should be finely tuned with one another. To achieve this fine tuning, the devices can employ a switched-capacitor set that can function as a variable resistor set. Employing the switched-capacitor set can cause achievement of precise resistances that allow the devices to successfully communicate with one another.

Methods, systems, and storage media for providing and/or obtaining feedback for data transmissions in an unlicensed shared medium are described. In embodiments, an apparatus may include radio control circuitry to demodulate and decode a data transmission from an evolved node B (eNB). The apparatus may include and processing circuitry, coupled with the radio control circuitry, and the processing circuitry is to receive the data transmission from the radio control circuitry and generate feedback based on the data transmission. The radio control circuitry may also control radio-frequency circuitry to determine whether a physical channel in an unlicensed shared medium is unoccupied, and transmit the feedback to the eNB over the physical channel when the physical channel is unoccupied according to the determination. Other embodiments may be described and/or claimed.

A coherent detection-based high-speed chaotic secure transmission method includes: at a transmit terminal in a chaotic secure transmission system, optically coupling an optical chaotic carrier and transmission information by using an orthogonal basis to mask the transmission information by using a noise-like feature of the chaotic carrier, so as to obtain a chaotic masked signal; adding a fast phase disturbance and a fast polarization disturbance to the chaotic masked signal and transmitting the chaotic masked signal over an optical fiber transmission link; and at a receive terminal, obtaining the chaotic masked signal through coherent detection, compensating the chaotic masked signal for linear and nonlinear effects through digital signal processing, and using a polarization orthogonal basis- or phase orthogonal basis-based chaotic decryption algorithm to separate the chaotic carrier from the signal so as to complete decryption.

A differential chaos shift keying (DCSK) communication method based on three-dimensional constellation is provided. Target information bit is mapped to a three-dimensional constellation symbol. An initial chaotic signal generated by a chaotic generator is processed by cyclic shift to generate a chaotic signal group including the initial chaotic signal, a first shifted chaotic signal and a second shifted chaotic signal. Information modulation is performed based on the three-dimensional constellation symbol and the chaotic signal group to obtain an information-bearing signal. A transmission signal is generated based on the information-bearing signal and the initial chaotic signal, and sent to a receiver to generate a received signal, which is subjected to information recovery analysis in the receiver to obtain an estimated information bit. A DCSK communication device based on three-dimensional constellation is also provided.

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.

The present invention teaches a system and method for secure network access and group membership in a cooperative network of digital chaos transmissions. The invention involves sensing generated digital chaos sequences as spreading sequences at a transmit side and determining the availability of open channels at a receive side. Further, a broadcast request to join frame from a node on an open channel is transmitted to network manager or coordinator. A network manager or coordinator sends an association/authentication packet, comprised of the reserved digital chaos associated to the unique device id, in response to the request to join frame from a node with a valid identification.

The present invention teaches a system and method for dynamic channel access in a cooperative network of digital chaos transmissions. The invention involves sensing generated digital chaos sequences as spreading sequences at a transmit side and determining the availability of open channels at a receive side. Further, a broadcast request to change channel at the receive side is cooperatively forwarded to group members based on their group member and pool of channel assignments. Each group member sends an acknowledgement packet, comprised of its reserved digital chaos acknowledgement sequences, upon changing to the new channel.

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.