This paper discusses an off-line underwater acoustic software modem for multiple differential detection employing per-survivor processing (PSP-MDD) with channel prediction. Underwater acoustic communications (UWACs) suffer from severe time and frequency selective channels, i.e., doubly-selective channels. For doubly-selective channels, the authors have evaluated multiple single carrier (MSC) modulation scheme and joint detection schemes employing channel prediction. This paper discusses MSC modulation schemes employing PSP-MDD with channel prediction. In addition, this paper proposes an off-line underwater acoustic software modem employing commercial acoustic electronic devices. Due to off-line operation, the proposed software modem has the following features: 1) it can evaluate actual acoustic environment using the same program of a performance simulator, 2) it can compare performances of several demodulation schemes using the same received signals recorded in actual acoustic environment. This paper evaluates that performance of MSC modulation schemes employing PSP-MDD with channel prediction by using the proposed software modem in an anechonic tank simulating doubly-selective channels.
