A new speech scrambler based on ofdm technique

In this paper, we propose a new speech scrambler using the Orthogonal Frequency Division Multiplexing (OFDM) technique referred to as OFDM scrambler. The OFDM scrambler can provide secured speech privacy by permuting a large number of frequency components. Important items are discussed, such as the size of OFDM subcarriers, the permutation of frequency components, and the generation of permutation matrices. In system structure, the OFDM scrambler needs only two FFT operations instead of four for a conventional FFT-based scrambler. Although the proposed speech scrambler is simpler than the conventional FFT-based scrambler, it attains the same degree of security for the scrambled speech. Simulation results also indicate that the OFDM scrambler provides not only low residual intelligibility of the scrambled speech but also good quality of the de-scrambled speech.