[Discuss-gnuradio] GSOC 2016 :Implement optimized, standardized channel codes

[Влад Василенко]

Hi Jan,

I would suggest the implementation of a pseudo-random interleavers, namely randon and s-random. It is more difficult to implement, but have a better performance. Used in turbo codes, they interleaver purpose is to offer each uncorrelated or random encoder version information, whereby each encoder parity bits are independent. The degree of independence of the parity bits is essentially a function of the type of length / depth of the interleaver.

The attached files contain BER graphics, depending on various parameters.

Figure 1 shows the effect of N input block size N on BER to Log Map decoding algorithm, 8 decoding iterations polynomial generators g0 = 7, g1 = 5, data rate in the Turbo code R = 1/2. At 1000 and 10000 symbols used in the transmitted pseudo-random interleaver block, and at 169 - the block.

Figure 2 shows the effect inte interleaving on BER to Log Map decoding algorithm, 8 decoding iterations polynomial generators g0 = 7, g1 = 5, data rate in the Turbo code R = 1/3. At 1000 and 10000 symbols used in the transmitted pseudo-random interleaver block, and at 169 - the block.

Figure 3 shows the effect of limiting the length of the encoder and polynomial generator on the characteristics of Turbo code.

These graphs were obtained by me in the course of the simulation.

I have implemented a system for simulating the operation of the turbo code. I implements the encoder, the decoder decoding with different algorithms(MAP-algorithm, LOG-MAP algorithm, MAX-LOG-MAP algorithm). It is also sold various types of interleavers (block, diagonal, random, s-random).

Best Regards,

Vlad Vasylenko

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