Coded under Water Acoustic Communication (UWA) with Cryptography

Cheap, robust, low power, error free and secure communication underwater is one of the challenges facing ocean-observing and communication systems. An underwater acoustic communication (UWA) system satisfying the above needs. Any such communication system must work around the errors introduced by multipath reflections, Doppler shifts in frequency, acoustic noise in the channel and insecurity. Errors can be reduced by using error-resistant modulation schemes such as DSSS, building better receiver structures or by implementing error control coding (ECC) schemes. The cheapest of these, in terms of cost and power, is ECC and in terms of security, is cryptography. The research on UWA communication has a few descriptions of error correction coding. However they are focused on high-end acoustic modems that transmit over long distances or large amounts of data and at a high cost and power. Most of them describe Turbo codes or Low Density Parity Check codes (LDPC), which give top performance but have complex encoders and decoders. Thus they are unsuitable for minimalist system and we would anyway not require that level of performance since our data rates are low. One good choice of code that gives excellent performance at relatively low complexities is the Reed Solomon code. Another main problem of our under water acoustic communication is security of information or data. Solution of this problem is that we use encrypted data communication. In our paper we are giving main attention on use of encryption method (RSA Algorithm for encryption and decryption) before encoding (RS code for low power & complexity of system) the data to improve security of ocean-observing and communication systems.