MethodA common method used in chaos engineering is direct-sequence spread-spectrum (DSSS)technique which require good periodicvariation properties ,good correlation,a wideband spectrum, initial condition must be sensitive to improve thesecurity at physical layer. Studies show that if an intruder may possibly recover a chaotic sequences by a method called blind estimation which will use thedata given from the different sequences to identify the symbols period givenfrom the this information from your original data. We can enhance this security issue by creating using avaried period according to the behavior of the chaotic spread in thecommunication system. How this works exactly is the information given from thesystem is given in a variable symbol period and is multiplied with a chaotic sequence to performthe spread-spectrum process. Below are different examples of different discrete-timemodels that show the synchronization, and analyzation for a spreading scheme with variable symbolperiods as well as a despreading schemewith sequence. We cover a series of Multi-access performance of white Gaussiannoise (AWGN) which is calculated byboth numerical computation andtheoretical derivation .

After this we compare and contrast the computer andactual simulations to verify that received data is correct our obtained resultspoint out that our proposed technique can protect the DSSS systems against thedetection of symbol period from the intruder, even if he has full informationon the used chaotic sequence Spreading scheme with variable bit periodBlock diagram demonstrates a spreading scheme with a pulsechain that has a variable inter-pulse intervals. We used {pl}, as the variable interval pulsegenerator (VIPG) The input we used is the {xk} to stand for the chaotic sequence. Which is sampled at eachtriggered input pulse. (1)pl=P(t?tl),with (2)P(t)={10?t??,0 Then the tl is the when you generate the lth pulseand the output sample xl is then converted into a positive integer ?l.

Thishappens by using a transformationfunction example (?l=f(xl)).Once f( · )is determined the sequence {xl} varies range is discovered and the xmin& xmax, {?l} is then in direct correlation to the range ?min=f(xmin)=0,?max=f(xmax)=?m.So in order to determine the functionf( · ), we had to usea fixed value for ?m. After we choose the value the xmin, xmax of the function is then dividedinto (?m+1) value intervals, xmin+j?,xmin+(j+1)?,with j varying from 0 to ?mand ? being a constant defined by(3)?=(xmax?xmin)/(?m+1).

Once the input numberxl falls in the range of xmin+j?,xmin+(j+1)?, the value for the othersource value ?l can finally be determined for example:(4)?l=f(xl)=?xl?xmin??,Depending on the value of ?l, will determine (l+1)after that the pulse is created at theoutput of the VIPG at the tl+1 given by (5)tl+1=tl+(?+?l)?,? is the chip periodof the chaotic sequence {xk} and ? is a fixed integer and the value is fixed.