Abstract
Recently, Block turbo codes have been suggested to many applications, such as IEEE 802.16e, satellite communication systems, optical fiber transmission systems and memory storages. The core of the block turbo code is the soft-input-soft-output (SISO) decoder. For high error performance applications, due to its high complexity and long decoding latency, it is hard to design an efficient SISO decoder. In this thesis, we proposed a SISO Chase decoder for a distance-based (64, 51, 6)2 block turbo code. The proposed decoder uses a threshold-sorting algorithm for finding 4-least-reliable inputs, a barrel-shifter-based error locator to finding roots of error locator polynomial, and a piece-wise-linear function to simplify the calculations of the extrinsic values. The throughput of the decoder is about 700 Mbps, with lower than 30K gate counts. As a component code of block turbo codes, the proposed SISO decoder has good contributions in bit-error-rate (BER) over signal-noise ratio (SNR). Compare to existing block turbo decoders, the error performance has gain 0.4-0.9 dB in low SNR applications. In addition, the three concepts in this thesis can be designed individually. These designs give good solutions both in reducing complexity and increasing decoding speed.