blast_qr.m

在MIMO系统中

%for test
clc;
clear all;
Tx_n=4;
Rx_n=4;
%SNR_dB = 10;
SNR_dB = -5;
%SNR_dB=[0:2:20]
SNR_step = 5;
ff_num = 0;% frame num in every run
index = 1;%for modu index:1/2/4/6 bits per symbol
frame_length = 48;
point = 0;
BER = 1;
while ( BER > 1.0e-003 )
	error_temp = 0;
	point = point + 1;
	SNR_dB = SNR_dB + SNR_step;
	while ( error_temp < 1000)
		ff_num = ff_num + 1;
		source = rand(1,Tx_n*frame_length*index)>.5;
		%encoder_input = modulation(source, index);
		%encoder_input = 2*source - 1;
		[encoder_output,Padding_Bit_Length] = vblast_encoder(Tx_n, source);
		for t=1:Tx_n
			encoder_output_modu(t,:) = modulation(encoder_output(t,:), index);
		end
		[channel_output,H] = flat_channel(Rx_n, encoder_output_modu);
		%keep the signal level at 0 dB
		module_signal = [];
		for t=1:Tx_n
			module_signal =[ module_signal abs(channel_output(t,:))];			
		end
		signal_level = mean(module_signal);
	    %signal_level_dB = 10 * log10(signal_level);
		%amplifier_for_SNR_dB =  0 - signal_level_dB;
    	%amplifier_for_SNR_linear = power(10,amplifier_for_SNR_dB/20);
		amplifier_for_SNR_linear = 1/signal_level;
    	channel_output = channel_output * amplifier_for_SNR_linear;
		decoder_input = awgn(channel_output,SNR_dB);
		decoder_output_demodu = vblast_decoder_QR(H,decoder_input, index);%demodulate already
		sink = zeros(1,Tx_n*frame_length*index);
		%demultiplex
		for i = 1:Tx_n
			sink(i:Tx_n:end)=decoder_output_demodu(i,:);
		end
		
		error_temp = sum(sink ~= source)+error_temp;
	end
	BER(point) = error_temp/(Tx_n*frame_length*index*ff_num);
	ff_num = 0;
end
S = 0:SNR_step:(point-1)*SNR_step;
semilogy(S,BER,'r-*');
grid on;