On The Sliding-Window Decoding Algorithm Of Turbo Code And FPGA Implementation

Turbo code is one of the most significant achievements in wireless communication systems coding theory during the last decade. Reference to the large number of domestic and international literature in recent years, combined with the practical engineering applications, this paper studies deeply the Turbo encoding in LTE standard. Then focus on used the sliding window algorithm in Turbo Decoding, to achieve LTE uplink speed50Mbps, downlink throughput rates of100M bps.Firstly, the principle of encoding and decoding of Turbo codes are introduced. By writing a C++program we investigated the existing three different turbo decoding algorithm. Comparisons of both their performances and implementation complexities were performed. Log-MAP was found to offer the best performance-complexity compromise. The parameters were determined use in the FPGA implementation.Secondly, the sliding window algorithm described in detail and given the reason for it to achieve high-speed decoding. When several Log-MAP processors are used in parallel decoder, memory access contentions occur when more than one extrinsic value is to be written to or read from the same memory block at the same time. These contentions may be avoided by designing contention-free interleaver.Finally, created two projects one for turbo encoder another for turbo decoder in the Quartus II software. In the decoder project, the critical calculation module was introduced by given theoretical analysis, top-level diagram and pin definitions. All projects were simulated by the ModelSim software.