Title :
Spatial Focusing and Intersymbol Interference in Multiple-Input–Single-Output Time Reversal Communication Systems
Author :
Blomgren, Peter ; Kyritsi, Persefoni ; Kim, Arnold D. ; Papanicolaou, George
Author_Institution :
Dept. of Math. & Stat., San Diego State Univ., San Diego, CA
fDate :
7/1/2008 12:00:00 AM
Abstract :
In this paper, we study a multiple-input-single-output (MISO) underwater communication system that applies time reversal (TR) to transmit signals so that they focus spatially and compress temporally on the intended receiver. Our simulations model an underwater acoustic channel as a waveguide, and we investigate the cases of a waveguide both with and without random inhomogeneities. We investigate physical TR metrics and communications related performance indicators. The results of our simulations show that spatial focusing depends strongly on the delay spread ( DS ) , as has been seen in experiments. This physical property of TR could be exploited in communication systems where signal coherence is desired only at the receiver location. However, in the simulations, we find that while spatial compression increases with DS in a robust way (i.e., even when inhomogeneities exist), time compression does not increase with DS. Moreover, physical measures of the temporal compression (temporal peak-to-sidelobe ratio) do not improve with waveguide inhomogeneities. Nevertheless, TR reduces intersymbol interference (ISI) at the receiver as DS increases for both types of waveguides, which is an important effect for efficient, high-speed communication. In addition to TR, preequalization at the transmitter can ideally eliminate ISI without significantly affecting spatial compression. However, this preequalization causes a reduction of received power, which may be acceptable when the signal-to-noise ratio (SNR) at the receiver is high.
Keywords :
MIMO communication; intersymbol interference; underwater acoustic communication; intersymbol interference; multiple-input-single-output time reversal communication systems; signal-to-noise ratio; spatial focusing; temporal peak-to-sidelobe ratio; underwater acoustic channel; underwater communication system; Intersymbol interference (ISI); low probability of intercept (LPI); time reversal (TR); underwater acoustic communications; waveguides;
Journal_Title :
Oceanic Engineering, IEEE Journal of
Conference_Location :
10/21/2008 12:00:00 AM
DOI :
10.1109/JOE.2008.925083