Reduced complexity in generating chaotic sequences for communication systems using sub-sampling techniques

A sub-sampling system that is part of a modulator in a transmitter employing an M-ary chaotic shift keying (M-CSK) architecture and including a symbol mapper and a single chaos generator, said system comprising:

• M-number of channels each receiving a sequence of chaos samples from the chaos generator;
• a delay device in all of the channels except one that each delay the chaos samples at different delay times;
• a sub-sampler in each channel of the M-number of channels receiving the sequence of delayed chaos samples, each sub-sampler outputting every predetermined number of the chaos samples so that each sub-sampler outputs a sequence of sub-sampled chaos samples that each have a different chaos sample at a certain sample time;
• a register in each channel each storing a predetermined number of the sequence of sub-sampled chaos samples;
• and
• a selection switch responsive to the stored sub-sampled chaos samples from the registers, said selection switch also being responsive to a selection signal from the symbol mapper that selects one of the registers to output the sequences of stored sub-sampled chaos samples from the sub-sampling system.

A communications system comprising:

• a transmitter including a modulator that modulates a signal to be transmitted, said modulator including a transmitter chaos generator and a transmitter sub-sampling sub-system, said transmitter sub-sampling sub-system including a plurality of channels each receiving a sequence of chaos samples from the transmitter chaos generator, a delay device in each of the plurality of channels that each delay the sequence of chaos samples at different delay times, a sub-sampler in each channel of the plurality of channels receiving the delayed chaos samples, each sub-sampler outputting every predetermined number of the chaos samples so that each sub-sampler outputs a sequence of sub-sampled chaos samples that each have a different chaos sample at a certain sample time, and a selection switch responsive to all of the sequences of sub-sampled chaos samples from the sub-samplers in the channels, said selection switch also being responsive to a selection signal that selects one of the sequences of sub-sampled chaos samples to be transmitted by the transmitter;
• and
• a receiver receiving the transmitted signal and including a demodulator that demodulates the transmitted signal, said demodulator including a receiver chaos generator and a receiver sub-sampling sub-system, said receiver sub-sampling sub-system including a plurality of channels each receiving a sequence of chaos samples from the receiver chaos generator, a delay device in each of the plurality of channels that each delay the sequence of chaos samples at different delay times, a sub-sampler in each channel of the plurality of channels receiving the delayed chaos samples, each sub-sampler outputting every predetermined number of the chaos samples so that each sub-sampler outputs a sequence of sub-sampled chaos samples that each have a different chaos sample at a certain sample time, said demodulator further including a multiplier in each channel that multiplies the chaos samples by the transmitted signal, and an adder that adds the multiplied signal.