Direct Mapping OFDM-Based Transmission Scheme for Underwater Acoustic Multimedia

In this paper, we propose a direct mapping (DM) orthogonal frequency division multiplexing (OFDM) based transmission scheme for underwater acoustic multimedia (UAM). We adopt DM multi-input multi-output (MIMO), power assignment mechanism, OFDM, adaptive modulation, and unequal error protection in the UAM system. 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. Simulation results show that the proposed scheme can not only fulfill the quality of services (QoS) required by a UAM system, but also achieve the mission of maximum transmission bit rates or minimum transmission power.