Design of Low-Power Turbo Encoder and Decoder for NB-IoT

Abstract

Turbo code is an error correction coding scheme close to the Shannon limit, usually used in wireless data transmission. Based on the parallel Turbo code algorithm, a parallel Turbo code circuit design scheme is proposed. In the encoder, the recursive systematic convolutional encoder is multiplexed. The decoder is divided into branch metric, recursive, maximum likelihood ratio, and external information calculation modules. The decoding algorithm is based on Max-Log-MAP, controlling the component decoder in parallel. And the state metric calculation in the decoding circuit is combined to reduce the overall power consumption effectively, enabling the encoder and decoder to be used in narrowband Internet of things (NB-IoT). Finally, the hardware scheme of the main functional modules of Turbo code encoding and decoding is designed and implemented. The results show that the dynamic power consumption is less than 50 mW. The overall on-chip power consumption is reduced by 40% at the frequency of 125 MHz compared with previous jobs.