1、%16QAM%等效基带调制clc;clear all;close all;%关闭所有窗口，比如之前画的图nsymbol = 10000;%每种信噪比下符号数的发送符号数，106 个数errornumber = zeros(1,10);errorratio = zeros(1,10);data = randi(0,1,1,4*nsymbol);%产生 1 行，4*nsymbol 列均匀分布的随机数data_mod1 = zeros(1,nsymbol);%各参量初始化data_mod2 = zeros(1,nsymbol);data_demod1 = zeros(1,nsymbol);data_
2、demod2 = zeros(1,nsymbol);data_demod3 = zeros(1,nsymbol);data_demod4 = zeros(1,nsymbol);s_receive1 = zeros(1,nsymbol);s_receive2 = zeros(1,nsymbol);for i = 1:nsymbol %格雷码调制到星座图的映射if data(4*i-3)=0 if data(4*i-1)=0 elseif data(4*i-1)=0 elseif data(4*i-1)=1 elseif data(4*i-1)=1 endelseif data(4*i-3)=0
3、if data(4*i-1)=0 elseif data(4*i-1)=0 elseif data(4*i-1)=1 elseif data(4*i-1)=1 endelseif data(4*i-3)=1 if data(4*i-1)=0 elseif data(4*i-1)=0 elseif data(4*i-1)=1 elseif data(4*i-1)=1 endelseif data(4*i-3)=1 if data(4*i-1)=0 elseif data(4*i-1)=0 elseif data(4*i-1)=1 elseif data(4*i-1)=1 endendendSNR
4、_dB = 1:10;%信噪比 dB 形式SNR = 10.(SNR_dB/10);%信噪比转化为线性值for loop= 1:10sigma = sqrt(5/SNR(loop);s_receive1 = data_mod1 + sigma * randn(1,length(data_mod1);s_receive2 = data_mod2 + sigma * randn(1,length(data_mod2);%?for k = 1:nsymbolif s_receive1(k)2 data_demod1(k) = 0;data_demod2(k) = 0;if s_receive2(k)
5、2data_demod3(k) = 0;data_demod4(k) = 0;elseif s_receive2(k)0 data_demod4(k) = 0;elseif s_receive2(k)0 data_demod2(k) = 1;if s_receive2(k)2data_demod3(k) = 0;data_demod4(k) = 0;elseif s_receive2(k)0 data_demod4(k) = 0;elseif s_receive2(k)0 data_demod4(k) = 1;elseif s_receive2(k)-2data_demod3(k) = 1;d
6、ata_demod4(k) = 0;endendif (data_demod1(k) = data(k*4-3) | (data_demod2(k) = data(k*4-2)|(data_demod3(k) = data(k*4-1) | (data_demod4(k) = data(k*4)errornumber(loop) = errornumber(loop) + 1;endenderrorratio(loop) = errornumber(loop)/nsymbol;endt = 0.75*erfc(sqrt(3*SNR/30);ser_theory = 1-(1-t).2;%理论误码率，注意 Q 函数和误差函数的对应关系semilogy(SNR_dB,errorratio,-k*,SNR_dB,ser_theory,-ro);title(16QAM 信号在 AWGN 信道下的性能（格雷码）);xlabel(信噪比/dB);ylabel( 误码率);legend(误码率,理论误码率);grid on;%坐标线
