UNDERWATER COMMUNICATION WITH THE HELP OF FREQUENCY MULTIPLE ACCESSES TECHNIQUE

The usage of TDMA and CSMA techniques for underwater communications is strictly limited in efficiency and scalability, the mostly due to the very large propagation delays. Frequency Hopping Multiple Accesses (FHMA) seems a feasible alternative in that the propagation delay does not impact significantly its efficiency. However, in underwater communications, the capacity achievable on a particular channel depends strongly both on its frequency and on the communication distance. Unlike in traditional radio transmissions system where FHMA channels usually has comparable performance. Therefore, fixed channel allocation schemes traditionally used for radio FHMA do not perform well in underwater communications. In this paper, we explore the application of the principles of frequency multiple access to underwater communications. In particular, we proposed a data transmission scheme which exploits user location knowledge in order to maximize the throughput capacity among those achieved by the users. This provides maximum fairness and makes a more efficient use of the available frequency accesses resources. Performance evaluation of proposed work is carried out by means of simulation shows that our approach can achieve a great improvement in fairness among users, with respect to other schemes, while at the same time throughput of system is much better and thus allowing effective communications over larger distances within the water with less energy consumption rate.