Turbo Decoder

Description

This project features a double binary, DVB-RCS turbo decoder using the SOVA algorithm.
Two models are included:
- a MyHDL model, along with a complete testbench,
- a synthesizable VHDL model.

Features

Double binary, DVB-RCS code
Soft Output Viterbi Algorithm
MyHDL cycle/bit accurate model and testbench
Synthesizable VHDL model

Status

Release 0.3:
- Synthesizable VHDL model
- Fixed ponderation filtering

Release 0.2:
- DVB-RCS interleaver
- DVB-RCS puncturing (decoder only)
- Controllable SNR for the noiser

Release 0.1: MyHDL model posted
- Simulation system consists of a random data pattern generator, turbo coder, transmission channel (gaussian noiser with controlable standard deviation), turbo decoder and Bit Error Rate monitors
- Turbo decoder generic parameters are: number of iterations, number of bits for the coding of the systematic and redundant data in the decoder, number of bits for the coding of the extrinsic information, first and second trellis' length, number of bits for the coding of the accumulated distances, length of the interleaver matrix side
- No puncturing
- No coder/decoder synchronization
- No wishbone I/F
- No in-operation BER monitoring
- Simple line-write/column-read interleaver
- Basic documentation (block diagrams)

Results

Decoder input signal width: 4 bits
Extrinsic information signal width: 5 bits
First trellis' length: 24
Second trellis' length: 12
Accumulated distances signal width: 9 bits
Interleaver frame size: 64 bit couples
Signal-to-noise ratio: 5.1 dB
Code rate: 1 / 2

Bit Error Rate:
0.0368951613 @ iteration 0 (no decoding)
0.0027355688 @ iteration 1
0.0001380629 @ iteration 2
0.0000722789 @ iteration 3
0.0000255319 @ iteration 4
0.0000212947 @ iteration 5