47 lines
1.0 KiB
Matlab
47 lines
1.0 KiB
Matlab
% gp_interleaver.m
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%
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% David Rowe May 2017
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%
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% Golden Prime Interleaver. My interprestation of "On the Analysis and
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% Design of Good Algebraic Interleavers", Xie et al,eq (5).
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1;
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% Choose b for Golden Prime Interleaver. b is chosen to be the
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% closest integer, which is relatively prime to N, to the Golden
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% section of N.
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function b = choose_interleaver_b(Nbits)
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p = primes(Nbits);
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i = 1;
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while(p(i) < Nbits/1.62)
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i++;
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end
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b = p(i);
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assert(gcd(b,Nbits) == 1, "b and Nbits must be co-prime");
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end
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function interleaved_frame = gp_interleave(frame)
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Nbits = length(frame);
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b = choose_interleaver_b(Nbits);
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interleaved_frame = zeros(1,Nbits);
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for i=1:Nbits
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j = mod((b*(i-1)), Nbits);
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interleaved_frame(j+1) = frame(i);
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end
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endfunction
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function frame = gp_deinterleave(interleaved_frame)
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Nbits = length(interleaved_frame);
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b = choose_interleaver_b(Nbits);
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frame = zeros(1,Nbits);
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for i=1:Nbits
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j = mod((b*(i-1)), Nbits);
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frame(i) = interleaved_frame(j+1);
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end
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endfunction
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