A Novel Single-Carrier Frequency-Domain Equalization Technique without Prefix or Suffix for Underwater Acoustic Communications

Single-Carrier Frequency-Domain Equalization (SC-FDE) is one of the key techniques to achieve high data-rate transmissions in underwater acoustic communications. However, the periodically inserted prefixes or suffixes, in forms of cyclic-prefixes or guard intervals in transmission sequence, reduce the bandwidth efficiency and data rate. A SC-FDE technique without prefix or suffix is proposed based on the Time Reversal (TR) for underwater acoustic communications. At the transmitter side, the single-carrier signal without prefix or suffix is transmitted. At the receiver side, the suffix is reconstructed in each block before canceling the intersymbol interference with FDE. The suffix reconstruction, which is the core of receiver, contains three main procedures: the TR processing, interference cancelation, and suffix reconstruction. First, the TR processing converts receptions from an array of receiving elements into a single composite signal. The equivalent impulse response (namely the q-function) has a stable peak, which avoids the noise amplification. Next, the interference cancelation is conducted to remove the InterBlock Interference (IBI) from the previous block and the ACausal Interference (ACI) from the current block. Afterward, suffix reconstruction is achieved by calculating the multipath arrivals of each symbol, which are obtained from the causal part of the q-function. Experimental results validate the effectiveness of this technique and its superiority over the SC-FDE technique without prefix or suffix in the current literature.