softdemod.m

B3g_phase2_C语言_Matlab程序及说明

function [DemodData] = SoftDeMod(Recv, ModScheme)
% This function completes soft demodulation of Gray mapping 16QAM and QPSK signal.
%
% function [DemodData] = SoftDeMod(Recv, ModScheme)
%
% Input:
%			Recv:		Receive symbols
%			ModScheme:	Modulation type
% Output:
%			DemodData:	Modulated symbols
% Note:
%			Unit energy symbol constellation
% See also:
%			Refer to: Berrou's paper, ICC'1993
% Description:
%			Author(s): Wang Dongming, SEU, NCRL


switch ModScheme
	
	case 2		% QPSK
		
		EstData = Recv;
		% Soft demodulation
		DemodData = zeros(1,length(EstData)*ModScheme);
		DemodData(1:2:end) = real(EstData);
		DemodData(2:2:end) = imag(EstData);
	
	case 4		% 16QAM
		
		EstData = Recv;
		% Soft demodulation
		DemodData = zeros(1,length(EstData)*ModScheme);
		DemodData(1:4:end) = real(EstData);
		DemodData(2:4:end) = abs(real(EstData))-2/sqrt(10);
		DemodData(3:4:end) = imag(EstData);
		DemodData(4:4:end) = abs(imag(EstData))-2/sqrt(10);
		
	otherwise
		disp('Modulation options out of range');
end