A 50Mbps double-binary turbo decoder for WiMAX based on bit-level extrinsic information exchange

Abstract

A 50 Mbps, 2.24 mm2 double-binary turbo double decoder is designed and implemented in 0.13 mum CMOS process for the WiMAX standard. To reduce the large extrinsic memory needed in double-binary turbo decoding, the proposed decoder exchanges the bit-level extrinsic information values rather than the traditional symbol-level extrinsic information values, which is achieved by deriving two simple conversions. The proposed turbo decoder, with a low-complexity hardware interleaver generating interleaved addresses for two data flows simultaneously, provides an efficient stopping criterion for double-binary turbo decoding using bit-level extrinsic information as well as huge memory size reduction of 20.6%.