siso_sc_fde.m

B3g_phase2_C语言_Matlab程序及说明

function SoftDetOut = SISO_SC_FDE(R, h, sigma2, softfb, var, LLR, N, ModType)
% Soft input without the aprior ordered succesive interference cancelation for V-BLAST initial detection.
%
%	function SoftDetOut = SISO_SC_FDE(R, h, sigma2, softfb, var, LLR, N, ModType)
%
%	Parameters:
%
%	Input:
%			R: 			The origenal received signal vector, column vector.
%			h:			Channel impulse response
%			sigma2:		Noise variance of the channel. if using ZF detection, just discarding this parameter.
%			softfb:		The apriori information
%			var:		variance of the apriori information.
%			LLR:		LLR of the a priori
%			N:			Block length
%
%	Output:
%			SoftDetOut:	Soft detection output.
%
% See also:
%
% (C) Wang Dongming, NCRL, SEU, April. 2003

load QAM.mat

h0 = zeros(N,1);
h0(1:length(h)) = h;

f = fft(h0);
g0 = f./(sigma2 + var*(abs(f).^2));
phi0 = ifft(g0);

% reconstruct the received signal using FFT/IFFT
rr = ifft(f.*fft(softfb));
SoftDetOut = [];

for kk = 1:N
	
	hk = h0;
	wk = phi0;
	rou = abs(wk'*hk);
	si = wk'*(R-rr+hk*softfb(kk));
	
	sigma2i = rou*(1-var*rou);
	mui = rou;

	% only for 16QAM
	Xi = real(si);
	Yi = imag(si);
	
	% first bit
	LLR1 = (-abs(Xi - 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(2,kk);
	LLR2 = (-abs(Xi - 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(2,kk);
	LLR3 = (-abs(Xi + 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(2,kk);
	LLR4 = (-abs(Xi + 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(2,kk);
	
	SoftDetOut = [ SoftDetOut (max(LLR1,LLR2) - max(LLR3,LLR4)) ];
	
	% second bit
	LLR1 = (-abs(Xi - 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(1,kk);
	LLR2 = (-abs(Xi + 3/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(1,kk);
	LLR3 = (-abs(Xi - 1/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(1,kk);
	LLR4 = (-abs(Xi + 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(1,kk);
	
	SoftDetOut = [ SoftDetOut (max(LLR1,LLR2) - max(LLR3,LLR4)) ];
	
	% third bit
	LLR1 = (-abs(Yi - 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(4,kk);
	LLR2 = (-abs(Yi - 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(4,kk);
	LLR3 = (-abs(Yi + 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(4,kk);
	LLR4 = (-abs(Yi + 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(4,kk);
	
	SoftDetOut = [ SoftDetOut (max(LLR1,LLR2) - max(LLR3,LLR4)) ];
	
	% forth bit
	LLR1 = (-abs(Yi - 3/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(3,kk);
	LLR2 = (-abs(Yi + 3/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(3,kk);
	LLR3 = (-abs(Yi - 1/sqrt(10)*mui)^2)/sigma2i + 0.5*LLR(3,kk);
	LLR4 = (-abs(Yi + 1/sqrt(10)*mui)^2)/sigma2i - 0.5*LLR(3,kk);
	
	SoftDetOut = [ SoftDetOut (max(LLR1,LLR2) - max(LLR3,LLR4)) ];
	
	% circulant of the vector
	h0 = [h0(end);h0(1:end-1)];
	phi0 = [phi0(end);phi0(1:end-1)];
	
end %for kk = 1:TxAntNum