RSA/Shift Secured IFFT/FFT Based OFDM Wireless System

The research on wireless system is to improve the reliability and performance of wireless radio links. The effects of (multi-path) radio propagation, modulation, and coding and signal processing techniques on the spectrum efficiency and performance of wireless radio networks are studied, in particular orthogonal frequency division multiplexing (OFDM) and related transmission methods. But the multimedia information is not secured in the wireless environment compared to that of wired environment. In this paper, we have carried out a new method of cryptographic algorithm over a future generation (4G and above) wireless system called the OFDM (FFT (fast Fourier transform) / IFFT (inverse FFT)) technique using Walsh Hadamard spreading codes. We have done the simulation in MATLAB programming and the BER (bit error rate) vs. SNR (signal-to-noise ratio) performance is studied for multimedia signals (such as text, audio and image) in an AWGN wireless channel. We have also developed an algorithm for generating the Walsh codes and the RSA secret keys. We found the results of our simulation are very much satisfactory for practical implementation in wireless systems.