- Volume 10 Issue 12
Beamforming for underwater acoustic communication (UAC) is affected by the broadband feature of UAC signal, which has relatively low currier frequency as compared to the signal bandwidth. The narrow-band assumption does not hold good in UAC. In this paper, we discuss a broadband FIR beamformer for UAC using the baseband equivalent way signal model. We consider the broadband FIR beamformer for QPSK UAC with carrier frequency 25kHz and symbol rate 5kHz. Array geometry is a uniform linear way with 8 omni-directional elements and sensor spacing is the half of the carrier wavelength. The simulation results show that the broadband n beamformer achieves nearly optimum signal to interference and noise ratio (SINR) and outperforms the conventional narrowband beamformer by SINR 0.5dB when two-tap FIR filter is employed at each sensor and the inter-tap delay is a quarter of the symbol interval. The broadband FIR beamformer performance is more degraded as the FIR filter length is increased above a certain value. If the inter-tap delay is not greater than half of the symbol period, SINR performance does not depend on the inter-tap delay. More training period is required when the inter-tap delay is same as the symbol period.
- L. Brekhovskikh and Y. Lysanov, Fundamentals of Ocean Acoustics. New York: Springer Verlag, 2003
- D. Kilfoyle and A. Baggeroer. 'The state of the art in underwater acoustic telemetry,' IEEE J. of Oceanic Eng, Vol. 25, pp. 4-27, Jan. 2000 https://doi.org/10.1109/48.820733
- Y. Park and J. Yim, 'A study on the protocol design and implementation for an underwater acoustic multi-ehannel digital communication,' Journal of KIMICS, Vol. 4, No.1, pp. 179-189, 2000
- H. Van Trees, Optimum Array Processing, New York: John Wiley & Sons, 2002
- F. Vook and R. Compton, 'Bandwidth performance of linear adaptive arrays with tapped delay-line processing,' IEEE Trans. AES, Vol. 28, No.3, pp. 901-908, July 1992