A low complexity stopping criterion for reducing power consumption in turbo decoders

Turbo codes are proposed in most of the advanced digital communication standards, such as 3GPP-LTE. However, due to its computational complexity, the turbo decoder is one of the most power hungry blocks in digital baseband. To alleviate this issue, one way is to avoid surplus computing phases thanks to the early termination of the iterative decoding process. The use of stopping criteria is one of the most common algorithm level power reduction methods in literature. These methods always come with some hardware overhead. In this paper, a new trellis based stopping criterion is proposed. The novelty of this approach is the lower hardware overhead thanks to the use of trellis states as key parameter to stop the iterative process. Results are showing the importance of this added hardware in terms of method efficiency. Compared to state-of-the-art Log Likelihood Ratio (LLR) based techniques, proposed Low Complexity Trellis Based (LCTB) is demonstrating 23% less power consumption on average, for comparable performance level in terms of Bit Error Rate (BER) and Frame Error Rate (FER).