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A Novel Multi-Exponential Function-based Companding Technique for Uniform Signal Compression over Channels with Limited Dynamic Range

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EN
Companding, as a variant of audio level compression, can help reduce the dynamic range of an audio signal. In analog (digital) systems, this can increase the signal-to-noise ratio (signal to quantization noise ratio) achieved during transmission. The µ-law algorithm that is primarily used in the digital telecommunication systems of North America and Japan, adapts a companding scheme that can expand small signals and compress large signals especially at the presence of high peak signals. In this paper, we present a novel multi-exponential companding function that can achieve more uniform compression on both large and small signals so that the relative signal strength over the time is preserved. That is, although larger signals may get considerably compressed, unlike µ-law algorithm, it is guaranteed that these signals after companding will definitely not be smaller than expanded signals that were originally small. Performance of the proposed algorithm is compared with µ-law using real audio signal, and results show that the proposed companding algorithm can achieve much smaller quantization errors with a modest increase in computation time.
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  • Dept. of Electrical and Computer Engineering, University of Nevada Las Vegas, NV 89154, USA
Bibliografia
  • [1] T. Jiang and G. Zhu, “Nonlinear companding transform for reducing peak-to-average power ratio of ofdm signals,” IEEE Trans. Broadcast., vol. 50, pp. 342–346, Sep. 2004.
  • [2] T. Jiang, Y. Yang, and Y.H. Song, “Exponential companding technique for PAPR reduction in OFDM systems,” IEEE Trans. Broadcasting, vol. 51, no. 2, pp. 244–248, June 2005.
  • [3] C. Kikkert, “Digital Companding Techniques,” IEEE Trans. Communications, vol. 22, no. 1, pp. 75-78, Jan. 1974.
  • [4] J. Kim and Y. Shin, “A robust companding scheme against nonlinear distortion of high power amplifiers in OFDM systems,” IEEE Vehicular Technology Conference, pp. 1697–1701, May 2008.
  • [5] J. Kim and Y. Shin, “An effective clipped companding scheme for PAPR reduction of OFDM signals,” IEEE Int’l Conference on Communications, pp. 668–672, May 2008.
  • [6] N.S.L. Phani Kumar, A. Banerjee, and P. Sircar, “Modified exponential companding for PAPR reduction of OFDM signals”, IEEE Wireless Communications and etworking Conference, pp. 1344–1349, March 2007.
  • [7] K. Sayood, Introduction to Data Compression, Third Edition, Morgan Kaufmann Publisher, 2006.
  • [8] D. A. Stojanovic and D. R. Aleksic, “Analysis of Uniform Polar Quantization over Bennett’s Integral,” ISSN 1392-1215 “Elektronika Ir Elektrotechnika,” vol. 64, no. 8, 2005.
  • [9] Y. P. Tsividis, V. Gopinathan, and L. Toth, “Companding in signal processing,” Electronics Letters, vol. 26, no. 17, pp. 1331–1332, Aug. 1990.
  • [10] X. Wang, T. T. Tjhung, and C. S. Ng, “Reduction of peak-to-average power ratio of ofdm system using a companding technique,” IEEE Trans. Broadcasting, vol. 45, no. 3, pp. 303–307, Sept. 1999.
  • [11] www.cisco.com/en/US/tech/
  • [12] www.iua.upf.edu/~xserra/cursos/TDP/7-Speech Coding.pdf
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bwmeta1.element.baztech-article-BWA0-0045-0020
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