Adaptive Channel Estimation Aided Log-Map Turbo Decoder Implementationfor DS-CDMA Based Mobile Systems

  • Authors:

  • Fan Mo;Junghwan Kim;Sameep Dave;Subhash C. Kwatra

  • Affiliations:

  • Electrical Engineering and Computer Science Department, The University of Toledo, 2801 W. Bancroft St, Toledo, Ohio 43606, U.S.A. E-mail: fan@eccincorp.com;Electrical Engineering and Computer Science Department, The University of Toledo, 2801 W. Bancroft St, Toledo, Ohio 43606, U.S.A.;Electrical Engineering and Computer Science Department, The University of Toledo, 2801 W. Bancroft St, Toledo, Ohio 43606, U.S.A.;Electrical Engineering and Computer Science Department, The University of Toledo, 2801 W. Bancroft St, Toledo, Ohio 43606, U.S.A.

  • Venue:
  • Wireless Personal Communications: An International Journal
  • Year:
  • 2004

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Abstract

Practical implementation of convolutional turbo codec is impeded by the difficulty of real-time execution in high transmission rate communication systems due to high computational complexity, iterative block decoding structure, as well as the requirement of accurate on-line channel reliability estimation for maximum-likelihood decoding. Relying on innovative channel estimation techniques involving DS-CDMA specificnoise/interference variance estimation and fading channel variation tracking,this paper provides a low-complexity all-digital design of an iterative SISOlog-MAP turbo decoder for DS-CDMA based mobile communication systems. The issues of quantization and data flow in both pre-decoder processing module and iterative trellis decoding module are prudently addressed to ensure highly efficient hardware implementation. The efficient design strategies applied confine the decoding complexity while leading to an excellent performance within 0.2 dB of the software decoder.