Orthogonal Chirp Division Multiplexing Based on Dictionary Theory for Integrated Sonar and Communication System

The complexity of the underwater acoustic (UWA) channel, such as severe Doppler expansion, is a major challenge when designing waveform and signal processing methods for the integrated sonar and communication (ISC) system. In this letter, dictionary theory is applied to signal design and a dictionary-theory-based orthogonal chirp division multiplexing (Dic-OCDM) signal is proposed. The geometric transformations for constructing the structured dictionary are used to construct the modulation matrix of the Dic-OCDM. The generated Dic-OCDM signal has a larger subcarrier spacing and thus is more tolerant to Doppler expansion. Simulation results show that the proposed Dic-OCDM signal can effectively improve the communication performance with similar detection performance compared to the OCDM signal.