Performance of Bit Level Decoding Algorithms for Binary LTE Turbo Codes with Early Stopping

Year 2017, Volume: 17 Issue: 2, 3399 - 3415, 27.07.2017

Yogesh Beeharry , Tulsi Pawan Fowdur Krishnaraj M. S Soyjaudah

Abstract

Turbo codes apply an
iterative message passing mechanism between two concatenated decoders. Their
astounding performance has led to their widespread adoption in several
communication standards such as Long Term Evolution (LTE), and Code Division
for Multiple Access (CDMA) 2000. This paper gives an overview of three bit-level
decoding Max-Log-MAP algorithms with Sign Difference Ratio (SDR)-based early
stopping that can be used in LTE Turbo Codes. A detailed computational
complexity analysis is given for the three methods. It is observed that the
complexity of the decoding methods decrease significantly as the E_b/N₀
increases when SDR is used. Moreover, the Bit Error Rate (BER) performance of
the methods was also assessed and compared for different modulation schemes.
Results show that the different methods perform differently in the waterfall
and error-floor regions with different modulation schemes. Moreover, the
computational complexity analysis show that Method 2 requires fewer overall
number of computations compared to Methods 1 and 3.

Keywords

LTE Turbo Codes, Max-Log-MAP Turbo Decoding, Computational Complexity Analysis.

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