使用MATLAB仿真观察3种合并方式的误码率
使用MATLAB对最大比值合并、等增益合并、选择式合并方式的误码率进行分析。
clear all;
Numusers = 1;
Nc=16; %扩频因子
ISI_Length=1; %每径延时为ISI_Length/2
EbN0db=[0:1:30]; %信噪比，单位dB
Tlen=8000; %数据长度
%误比特率的初始值
Bit_Error_Number1=0;
Bit_Error_Number2=0;
Bit_Error_Number3=0;
%每径功率因子
power_unitary_factor1 = sqrt(6/9)
power_unitary_factor2 = sqrt(2/9)
power_unitary_factor3 = sqrt(1/9)
s_initial=randsrc(1,Tlen); %数据源
%产生walsh矩阵
wal2 = [1 1;1 -1];
wal4 = [wal2 wal2;wal2 wal2*(-1)]
wal8 = [wal4 wal4;wal4 wal4*(-1)]
wal16 = [wal8 wal8;wal8 wal8*(-1)]
%扩频
s_spread = zeros(Numusers,Tlen*Nc)
ray1 = zeros(Numusers,2*Tlen*Nc)
ray2 = zeros(Numusers,2*Tlen*Nc)
ray3 = zeros(Numusers,2*Tlen*Nc)
for i=1:Numusers
x0 = s_initial(i,:).'*wal16(8,:);
x1 = x0.';
s_spread(i,:)=(x1(:)).';
end
%将每个扩频后的输出重复为两次，有利于下面的延迟（延迟半个码元）
ray1(1:2:2*Tlen*Nc-1)=s_spread(1:Tlen*Nc);
ray1(2:2:2*Tlen*Nc)=ray1(1:2:2*Tlen*Nc-1);
%产生第二径和第三径信号
ray2(ISI_Length+1:2*Tlen*Nc)=ray1(1:2*Tlen*Nc-ISI_Length);
ray3(2*ISI_Length+1:2*Tlen*Nc)=ray1(1:2*Tlen*Nc-2*ISI_Length);
for nEN = 1:length(EbN0db)
en = 10^(EbN0db(nEN)/10);
sigma=sqrt(32/(2*en));
%接收到的信号demp
demp = power_unitary_factor1*ray1+...
power_unitary_factor2*ray2+...
power_unitary_factor3*ray3+...
(rand(1,2*Tlen*Nc)+randn(1,2*Tlen*Nc)*i)*sigma;
dt = reshape(demp,32,Tlen)';
%将walsh码重复为两次
wal16_d(1:2:31) = wal16(8,1:16);
wal16_d(2:2:32) = wal16(8,1:16);
%解扩后rdata1为第一径输出
rdata1 = dt*wal16_d(1,:).';
%将walsh码延迟半个码片
wal16_delay1(1,2:32)=wal16_d(1,1:31);
%解扩后rdata2为第二径输出
rdata2 = dt*wal16_delay1(1,:).';
%将walsh码延迟一个码片
wal16_delay2(1,3:32)=wal16_d(1,1:30);
wal16_delay2(1,1:2)=wal16_d(1,31:32);
%解扩后rdata3为第三径输出
rdata3=dt*wal16_delay2(1,:).';
p1 = rdata1'*rdata1;
p2 = rdata2'*rdata2;
p3 = rdata3'*rdata3;
p = p1+p2+p3;
u1=p1/p;
u2=p2/p;
u3=p3/p;
%最大比值合并
rd_m1=real(rdata1*u1+rdata2*u2+rdata3*u3);
%等增益合并
rd_m2 = (real(rdata1+rdata2+rdata3))/3;
%选择式合并
u=[u1,u2,u3]
maxu=max(u)
if(maxu==u1)
rd_m3=real(rdata1);
else
if(maxu==u2)
rd_m3=real(rdata2);
else rd_m3=real(rdata3);
end
end
%三种方法判决输出
r_Data1=sign(rd_m1)';
r_Data2=sign(rd_m2)';
r_Data3=sign(rd_m3)';
%计算误比特率
Bit_Error_Number1 = length(find(r_Data1(1:Tlen)~=s_initial(1:Tlen)));
Bit_Error_Rate1(nEN)=Bit_Error_Number1/Tlen;
Bit_Error_Number2 = length(find(r_Data2(1:Tlen)~=s_initial(1:Tlen)));
Bit_Error_Rate2(nEN)=Bit_Error_Number2/Tlen;
Bit_Error_Number3 = length(find(r_Data3(1:Tlen)~=s_initial(1:Tlen)));
Bit_Error_Rate3(nEN)=Bit_Error_Number3/Tlen;
end
semilogy(EbN0db,Bit_Error_Rate1,'r*-');hold on;
semilogy(EbN0db,Bit_Error_Rate2,'bo-');hold on;
semilogy(EbN0db,Bit_Error_Rate3,'g.-');hold on;
legend('最大比合并','等增益合并','选择式合并');
xlabel('信噪比')
ylabel('误比特率')
title('三种主要分集合并方式性能比较');