With the help of binary message signal and PN sequence
, a SS signal is generated which is modulated using BPSK modulation technique at the transmitter side.
The digitization of chaotic system can generate PN sequence
, which can be used in secure communications.
Comparison between chaos based and PN sequence
based CDMA system is shown in [2, 3].
In , block and symbol scrambling were proposed based on PN sequence
that was generated by Pseudo Random Generator.
For embedding process the watermark signal W are generated by using watermarking information bits b, chip rate r and PN sequence
In Section III, a proposed authentication scheme is presented depending on the dynamic change of S-box in AES, the new secret key for every authentication process and the new PN sequence
On the other hand, we can merely assign one PN sequence
for each user in the multiuser code-time diversity system and by exploiting the autocorrelation property of the PN sequence
, and the rest (N-1) spreading codes required for the proposed diversity scheme can be generated from the same generator polynomial by cyclically shifting the generated sequence different (N - 1) times.
We adopt different lengths of cyclic prefix in OFDM and different lengths of PN sequence
in SSOFDM to analyze the system performance.
And compared to other PN sequences
like m sequences, and so forth, the PN sequence
generated by chaotic system has advantages like larger key space, longer cycle, and so forth.
The maximum length PN sequence
that can be obtained from these polynomials is [2.sup.15]-1.
As a PN signal has a very sharp autocorrelation at zero delay, it can be detected by correlation of the returned measurement signal with the known PN sequence
. The detection is done with a delay locked loop (DLL) that accurately determines amplitude and group delay of the channel.