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The modified Max-Log-MAP turbo decoding algorithm by extrinsic information scaling for wireless applications

Taskaldiran, Mustafa and Morling, Richard C.S. and Kale, Izzet (2009) The modified Max-Log-MAP turbo decoding algorithm by extrinsic information scaling for wireless applications. In: Powell, Steven and Shim, J.P., (eds.) Wireless technology: applications, management, and security. Lecture notes in electrical engineering (44). Springer. ISBN 9780387717869



The iterative nature of turbo-decoding algorithms increases their complexity compare to conventional FEC decoding algorithms. Two iterative decoding algorithms, Soft-Output-Viterbi Algorithm (SOVA) and Maximum A posteriori Probability (MAP) Algorithm require complex decoding operations over several iteration cycles. So, for real-time implementation of turbo codes, reducing the decoder complexity while preserving bit-error-rate (BER) performance is an important design consideration. In this chapter, a modification to the Max-Log-MAP algorithm is presented. This modification is to scale the extrinsic information exchange between the constituent decoders. The remainder of this chapter is organized as follows: An overview of the turbo encoding and decoding processes, the MAP algorithm and its simplified versions the Log-MAP and Max-Log-MAP algorithms are presented in section 1. The extrinsic information scaling is introduced, simulation results are presented, and the performance of different methods to choose the best scaling factor is discussed in Section 2. Section 3 discusses trends and applications of turbo coding from the perspective of wireless applications.

Item Type:Book Section
Research Community:University of Westminster > Electronics and Computer Science, School of
ID Code:6178
Deposited On:23 Mar 2009 15:23
Last Modified:11 Aug 2010 15:35

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