2019_programme: EFFECTS OF MULTIPATH SIGNAL WITH THE NONUNIFORM DOPPLER SHIFT ON VERTICAL UNDERWATER ACOUSTIC COMMUNICATION

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  • Session: 05. Underwater Communications and Networking
    Organiser(s): Tsimenidis Charalampos, Mitchell Paul, Pelekanakis konstantinos
  • Lecture: EFFECTS OF MULTIPATH SIGNAL WITH THE NONUNIFORM DOPPLER SHIFT ON VERTICAL UNDERWATER ACOUSTIC COMMUNICATION [invited]
    Paper ID: 798
    Author(s): Deguchi Mitsuyasu, Kida Yukihiro, Shimura Takuya
    Presenter: Deguchi Mitsuyasu
    Presentation type: oral
    Abstract: For several decades, demands to survey mineral sources on seabed have increased, and many autonomous underwater vehicles (AUVs) have been developed and operated for the purpose. Although a large mothership has been utilized to monitor the status of the AUV with vertical underwater acoustic (UWA) communication during the operation, a survey system with multiple AUVs and an autonomous surface vehicle (ASV) which monitors statuses of the AUVs has been proposed in recent years. From an operational point of view, the ASV has to be as small as several meters; thereby, it rolls and pitches more largely than the mothership, and such motion causes the nonuniform Doppler shift.\nIn addition, multipath signals can be received in actual survey areas. Generally, the Doppler shift of a multipath signal is different from that of the direct signal due to the difference in direction of arrival. Therefore, to realize our proposal system, effects of the nonuniform Doppler shift of the multipath signal on the demodulation performance have to be investigated as well as that of the direct signal.\nIn this study, effects of a multipath signal with the nonuniform Doppler shift on vertical UWA communication between surface and underwater vehicles were investigated by simulation. Single-carrier modulation (SCM) and orthogonal frequency division multiplexing (OFDM) communications were utilized, and the roll motion of the surface vehicle caused the Doppler shift. Consequently, it was found that a decision feedback equalizer suppresses the effects in SCM communication. On the other hand, results in OFDM communication indicate that the Doppler shift of the multipath signal causes inter-carrier interferences even if effects of the nonuniform Doppler shift of the direct signal are removed by a resampling method.\nFurthermore, simulation results show that OFDM communication is more sensitive to the Doppler shift of the multipath signal than SCM communication.
  • Corresponding author: Mr Deguchi Mitsuyasu
    Affiliation: JAMSTEC
    Country: Japan
    e-mail:

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