Asian Science
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Abstract: We live in an era where hacking and unauthorized access attempts
to data are so common. There is a need to secure data before it is transmitted.
Addition of overhead bits and modulation techniques decrease the capacity and
increase the cost. Both the channel capacity and the cost to set up the communication
system have to be optimal. So intimidating is a feature called multiple access
used for this purpose. Multiple access also improves capacity by simultaneously
transmitting large number of messages. There is very less or no interference
between the signals since each of them is polarized orthogonally or encoded
using different coding sequences or sent as bursts in different time slots.
Particularly Code Division Multiple Access (CDMA) makes it more difficult for
the hacker to access the transmitted data. If the message is thrown to all the
users only the intended receiver has the same coding sequence to decode it.
So, others cant access the message. Even if the message is detected, use
of steganography makes it all the more difficult for the hacker to decode the
message. This increases the security multifold. The aesthetic appeal of CDMA
and steganography together has revolutionized the present world communication
systems. In this study, the performance of CDMA is analysed by embedding confidential
information at three levels namely after interleaving, spreading and modulator.
The Bit Error Rate (BER) performance comparison graphs with and without information
hiding at three levels are analysed using BPSK, QPSK and QAM schemes.