66 lines
2.1 KiB
Matlab
66 lines
2.1 KiB
Matlab
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function mod_symbols = tx_modulate(bits_in, modulation)
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full_len = length(bits_in);
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% BPSK modulation
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if ~isempty(findstr(modulation, 'BPSK'))
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% Angle [pi/4 -3*pi/4] corresponds to
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% Gray code vector [0 1], respectively.
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table=exp(j*[0 -pi]); % generates BPSK symbols
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table=table([1 0]+1); % Gray code mapping pattern for BPSK symbols
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inp=bits_in;
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mod_symbols=table(inp+1); % maps transmitted bits into BPSK symbols
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% QPSK modulation
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elseif ~isempty(findstr(modulation, 'QPSK'))
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% Angle [pi/4 3*pi/4 -3*pi/4 -pi/4] corresponds to
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% Gray code vector [00 10 11 01], respectively.
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table=exp(j*[-3/4*pi 3/4*pi 1/4*pi -1/4*pi]); % generates QPSK symbols
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table=table([0 1 3 2]+1); % Gray code mapping pattern for QPSK symbols
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inp=reshape(bits_in,2,full_len/2);
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mod_symbols=table([2 1]*inp+1); % maps transmitted bits into QPSK symbols
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% 16-QAM modulation
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elseif ~isempty(findstr(modulation, '16QAM'))
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% generates 16QAM symbols
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m=1;
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for k=-3:2:3
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for l=-3:2:3
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table(m) = (k+j*l)/sqrt(10); % power normalization
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m=m+1;
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end;
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end;
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table=table([0 1 3 2 4 5 7 6 12 13 15 14 8 9 11 10]+1); % Gray code mapping pattern for 8-PSK symbols
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inp=reshape(bits_in,4,full_len/4);
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mod_symbols=table([8 4 2 1]*inp+1); % maps transmitted bits into 16QAM symbols
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% 64-QAM modulation
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elseif ~isempty(findstr(modulation, '64QAM'))
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% generates 64QAM symbols
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m=1;
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for k=-7:2:7
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for l=-7:2:7
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table(m) = (k+j*l)/sqrt(42); % power normalization
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m=m+1;
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end;
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end;
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table=table([[ 0 1 3 2 7 6 4 5]...
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8+[ 0 1 3 2 7 6 4 5]...
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24+[ 0 1 3 2 7 6 4 5]...
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16+[ 0 1 3 2 7 6 4 5]...
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56+[ 0 1 3 2 7 6 4 5]...
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48+[ 0 1 3 2 7 6 4 5]...
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32+[ 0 1 3 2 7 6 4 5]...
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40+[ 0 1 3 2 7 6 4 5]]+1);
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inp=reshape(bits_in,6,full_len/6);
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mod_symbols=table([32 16 8 4 2 1]*inp+1); % maps transmitted bits into 64QAM symbol
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else
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error('Unimplemented modulation');
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end
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