Performance analysis of signal to noise ratio and bit error rate for multiuser using Passive Time Reversal Technique in underwater communication

Underwater channel characterized by multipath propagation requires focusing of acoustic signal to overcome delay spread. This is achieved by time reversal. This paper simulates underwater acoustic communication using passive time reversal technique with transmitter and receiver separated in range by 4 Km in 120m deep water. The Passive Time Reversal (PTR) system is simulated for both singleuser and multiuser transmissions. Using Quadrature Phase Shift Keying (QPSK) modulation, input bit sequence is transmitted through the underwater channel. A 32 element Vertical Receiver Array (VRA) focuses the signal enabling to reduce the bit errors. Successful implementation of passive time reversal is carried out and the performance of the system is analyzed. Simulation result show that better Bit Error Rate (BER) can be achieved with respect to number of receiver elements with the time reversal techniques and comparison of the same is carried without passive time reversal. Also BER is found to vary with the distance between the users as also with the number of users.