Research On Generation And Performance Of Spread Random Sequence Based On Physical Entropy Source

Spread spectrum communication has anti-jamming,anti-fading and confidentiality,and is widely used in military and aerospace communications.The performance of a spread spectrum communication system largely depends on the performance of spreading sequence.The traditional spread spectrum sequences generally have periodicity and weak orthogonality,such as pseudo-random sequences,which not only reduces the link performance of the spread spectrum communication,but also limits its application in the field of secure communication and digital scrambling.The physical random sequence not only has the statistical characteristics of white noise,but also satisfies the true randomness.A scheme that treats physical random sequences generated by physical entropy sources as spread-spectrum random sequences is proposed in this thesis.The application of truncated and optimized physical random sequence in DS-SS system is studied.First,the chaotic signal output by the semiconductor laser is treated as a physical entropy source.After photoelectric conversion and digital operation processing,a high-speed physical random sequence with a rate of 4Gbit/s is obtained with Matlab/Simulink auxiliary operation.Then,the statistical properties of the physical random sequence and the original chaotic sequence,such as balance and correlation,are compared and analyzed.The true random performance of the physical random sequence is tested using test standard software published by the National Institute of Standards and Technology(NIST).Finally,the truncated and optimized physical random sequence is treated as the spreading code in DS-SS simulation model,and the spread spectrum communication system link error performance and multi-user interference performance are studied.The simulation results show that compared with the original chaotic sequence,the truncated and optimized physical random sequence has better balance,auto-correlation and orthogonality.The DS-SS has better anti-noise and anti-multi-address interference performance,which used physical random sequence as spreading sequence.