IJSRP, Volume 3, Issue 12, December 2013 Edition [ISSN 2250-3153]
Pallavi Suryawanshi, Vaishali Sonone, Ashish Jadhav
OFDM has several distinct challenges in the underwater channel environment. The underwater channel is known to be highly frequency selective with large delay and Doppler spreading as well as fast time variance. To overcome the poor communication environment between the underwater acoustic signal transmitter and receiver, previous research applied underwater acoustic OFDM communication system which had efficient bandwidth capacity and could mitigate multi-path delay spread effect via guard interval. Concurrently with this OFDM signal, additional data could be transmitted through spread spreading technique, which was called water-line technique. However, this decreased the performance of the OFDM modulation because the water-line signal degraded OFDM signal. An essential feature of this system is that it offers greater power and schemes with significant error protection for the transmission of sensor data information requiring a higher quality of service (QoS). The proposed underwater acoustic multimedia system employs high power, low speed modulation, and schemes providing significant error protection for the transmission of sensor data messages requiring a stringent bit-error rate (BER). In contrast, low power, high speed modulation, and less capable error protection schemes are provided for messages that can tolerate a high BER.