NDLI: Adaptive OFDM for underwater acoustic channels with limited feedback

Content Provider	IEEE Xplore Digital Library
Author	Radosevic, A. Duman, T.M. Proakis, J.G. Stojanovic, M.
Copyright Year	2011
Description	Author affiliation: Dept. of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA (Stojanovic, M.) \|\| School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, 85287-5706, USA (Duman, T.M.) \|\| Dept. of Electrical and Computer Engineering, Univ. of California, San Diego, La Jolla, 92093, USA (Radosevic, A.; Proakis, J.G.)
Abstract	In this paper we analyze the performance of adaptive orthogonal frequency division multiplexing (OFDM) for underwater acoustic (UWA) communications. Our goal is to maximize the system throughput under a target average bit error rate (BER). We consider two different schemes based on the level of adaptivity: in the first scheme only the modulation levels are adjusted while the power is allocated uniformly across the sub-carriers, whereas in the second scheme, both the modulation levels and the power are adjusted adaptively. We exploit a feedback from the receiver in two forms: one that conveys the modulation alphabet and quantized power levels to be used for each sub-carrier, and another that conveys a quantized estimate of the sparse channel impulse response. We compare these two strategies based on the average number of bits per OFDM block needed to achieve a pre-specified target average BER. In both cases we predict the channel one travel time ahead so as to improve the performance in the presence of a long propagation delay. The second approach is shown to be advantageous, as it requires significantly fewer feedback bits for the same system throughput. The effectiveness of the proposed schemes is demonstrated using real channel measurements recorded in shallow water off the western coast of Kauai, Hawaii, in June 2008.
Starting Page	975
Ending Page	980
File Size	175774
Page Count	6
File Format	PDF
ISBN	9781467303217
ISSN	10586393
e-ISBN	9781467303231
DOI	10.1109/ACSSC.2011.6190156
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-11-06
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Modulation OFDM Throughput Channel estimation Bit error rate Transmitters Resource management
Content Type	Text
Resource Type	Article
Subject	Signal Processing Computer Networks and Communications

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