Iterative Doppler Tracking based on Kalman Filter for Underwater Acoustic FH-FSK Communication in High Mobility

Due to its relatively lower propagation loss, acoustic wave is until now the only option for medium and long range underwater wireless communication. However, the low velocity of acoustic wave in water can easily lead to significant Doppler effect. Especially in the case of communication between underwater platforms with high mobility, the Doppler effect could even be time varying during signal transmission. In this paper, an iterative Doppler tracking algorithm based on Kalman filter is proposed for non-coherent frequency hopping frequency shift keying underwater acoustic communication (UWA) systems suffered from varying Doppler effect. Since the duration of a UWA communication signal is usually short, the change in relative motion between transmitter and receiver is not too drastic.Therefore the motion during this period is modeled by constant acceleration model or constant jerk model. Then, a receiver algorithm iteratively estimates and refines the time-varying Doppler is proposed, in which the refinement is carried out based on Kalman filter. Utilizing the filtered Doppler scale factors, this algorithm adaptively performs symbol synchronization and Doppler frequency shift correction in a symbol-by-symbol fashion, which effectively compensates the signal distortion induced by varying Doppler effect. Simulation results demonstrate the effectiveness of the proposed algorithm in different maneuvering scenes.