Abstract: The ocean display episode of changing acoustic signal transmission due to its non-stationary nature. To set up wireless communication system of communication purpose is challenging in underwater application because transmitter sector section and receiver section are not fixed. Sound causes large delay in acoustic signal because of multipath phenomena and speed of sound is 1500 m/s. inter-symbol interference (ISI) occur due to large time delay and ISI decrease the performance of many system or receivers. However orthogonal frequency division multiplexing (OFDM) is a multi-tone modulation scheme which is used to reduce the long-time delay spreads of acoustic channels. OFDM-IDMA system is designed to mitigate the error burst in multi-access underwater application. An efficient random base interleaver is present which is simple and could produce orthogonal interleavers for generating user specific chip level interleaver for different user. Performance of OFDM-IDMA system was observed through analysis of BER with respect to SNR.

Keywords: IDMA, FDMA, BER, ISI, MAI and underwater communication.