2023_programme: The experiment of the long-range MIMO underwater acoustic communication using adaptive passive time reversal in a continental shelf of Japan.

• Session: 19. Underwater Communications and Networking
  Organiser(s): Charalampos Tsimenidis, Paul Mitchell and Konstantinos Pelekanakis
• Lecture: The experiment of the long-range MIMO underwater acoustic communication using adaptive passive time reversal in a continental shelf of Japan. [invited]
  Paper ID: 2008
  Author(s): Kida Yukihiro, Deguchi Mitsuyasu, Watanabe Yoshitaka, Shimura Takuya
  Presenter: Deguchi Mitsuyasu
  Abstract: Underwater acoustic channel is one of the most difficult environments for achieving high data rate wireless communication due to the bandwidth limitation and the severe multipath interferences. To overcome these characteristics, we investigate the applicability of a rejection combining technique called adaptive passive time reversal (APTR) to the spatial division multiplexing (SDM) multiple-input/multiple-output (MIMO) underwater acoustic communication in real sea environments. \nThe APTR utilizes the pre-estimated channel information among the MIMO channels at the receiver side for a rejection combining processing derived from the minimum variance distortionless response criteria to decompose the transmission streams and suppress the co-channel interferences in simultaneous transmissions of the SDM MIMO channel. Signals after APTR processing in passband are converted to the baseband with a coarse Doppler shift compensation using the detection result of the compression/dilatation of signaling frame. Then the baseband signals are equalized by a single channel decision feedback equalizer with a digital phase locked loop. The communication channels are convolutionally coded and the soft decision Viterbi algorithm is applied for decoding.\nThe experiment was carried out at the continental shelf area near Japan coast in summer. The vertical transmitter array and receiver array which consists of 5 projectors and 24 hydrophones, respectively, were moored at the distance over 13.5 km. The projectors sent different information bearing signals modulated by the single carrier modulation scheme utilizing the signal bandwidth from 4 kHz to 8.5 kHz. \nIt is found that the APTR method could achieve SDM MIMO communication using up to 5 projectors even though the channel response contains long-strong multipath spreads over tens to several hundred milliseconds with moderate temporal variations. Specifically, the bit-error-free packet rate of 98 % were achieved for overnight recording in the effective data rate of 27 kbps using 5 projectors.
• Corresponding author: Dr Yukihiro Kida
  Affiliation: Japan Agency for Marine Earth Sciecne and Technology
  Country: Japan
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