clear?all;
SNR=0:2:30;
snr=10.^（SNR/10）;
sigma=sqrt（1./snr）;%噪聲與信號的幅度比值
K=200000;%未調制信號長度，信號越長，曲線越精確
data=randint（1K）;
%%%%%%%%%%%%%%%%%%%%設置參數%%%%%%%%%%%%%%%%%%%%%%%%
nt=2;%發射天線數
nr=2;%接收天線數
n=4;?%調制方式nPSK

%%%%%%%%%%%%%%%%%%%%NPSK信號調制%%%%%%%%%%%%%%%%%%%%
npskdata=npsk（ndata）;%調用調制方式子函數
x=npskdata;???????????%調制后信號

%%%%%%%%%%%%%%%%%%%Alamouti%%%%%%%%%%%%%%%%%%%%%%%%
for?k=1:length（SNR）
????error_symbol=0;%對每一個信噪比下的誤符號率清零
	for?i=1:length（npskdata）/2
????	x1=x（2*i-1）;
????????x2=x（2*i）;?????????%對信源進行空時操作，每兩個數據符號一起
????????X=[x1?-x2‘;x2?x1‘];%空時發射信號矩陣
		H=rey（ntnr）;??????%調用信道子函數
		noise=sigma（k）.*rey（ntnr）;
????????R=sqrt（1/2）.*H*X+noise;%接收信號矩陣
????????y1=0;y2=0;
		for?i=1:nr
		????y1=H（i1）‘*R（i1）+H（i2）*R（i2）‘+y1;
		????y2=H（i2）‘*R（i1）-H（i1）*R（i2）‘+y2;
		end??

	????%進行最大似然檢測
	????DEC_X=judge（ny1y2）;

????????%統計符號錯誤的總數
	????if?DEC_X（1）~=x1
	????error_symbol=error_symbol+1;
	????end
	????if?DEC_X（2）~=x2
	????error_symbol=error_symbol+1;
	????end
	end
?????SER（k）=error_symbol/length（npskdata）;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%畫圖%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
semilogy（SNRSER‘b*-‘）;
grid?on
legend（‘Alamouti?QPSK（2TX?2RX）‘）
title（‘QPSK調制下的Alamouti碼方案在慢瑞利衰減信道上的誤符號率性能‘）
xlabel（‘信噪比/dB‘）;
ylabel（‘誤符號率‘）;
hold?on

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件??????71168??2009-03-30?10:47??運行結果.doc

?????文件????????449??2009-03-29?21:07??judge.m

?????文件????????304??2009-03-29?21:02??npsk.m

?????文件????????241??2009-03-29?21:00??rey.m

?????文件???????1461??2009-03-29?21:34??alamouti.m

-----------?---------??----------?-----??----

????????????????73623????????????????????5