function?[pb1ps1pe1]=cm_sm32（snr_in_dB）
%?[pbps]=cm_sm32（snr_in_dB）
%????????????????CM_SM3?finds?the?probability?of?bit?error?and?symbol?error?for?
%????????????????the?given?value?of?snr_in_dB?signal?to?noise?ratio?in?dB.
N=10000;
E=1;????????????????????????????????????????????%?energy?per?symbol
snr=10^（snr_in_dB/10）;??????????????????????????%?signal?to?noise?ratio
sgma=sqrt（E/snr）/2;?????????????????????????????%?noise?variance
s00=[1?0];?s01=[0?1];?s11=[-1?0];?s10=[0?-1];???%?signal?mapping
%?generation?of?the?data?source
numofsymbolerror=0;
numofbiterror=0;
counter=0;
while（numofbiterror<100）
for?i=1:N
????temp=rand;?????j=2*i;?????????????????????????????%?a?uniform?random?variable?between?0?and?1
????if?（temp<0.25）?????????????????????????????%?with?probability?1/4?source?output?is?“00“
????????dsource（1j-1）=0;?dsource（1j）=0;
????elseif?（temp<0.5）??????????????????????????%?with?probability?1/4?source?output?is?“01“
????????dsource（1j-1）=0;?dsource（1j）=1;
????elseif?（temp<0.75）?????????????????????????%?with?probability?1/4?source?output?is?“10“
????????dsource（1j-1）=1;?dsource（1j）=0;
????else????????????????????????????????????????%?with?probability?1/4?source?output?is?“11“
????????dsource（1j-1）=1;?dsource（1j）=1;
????end;
end;
%?detection?and?the?probability?of?error?calculation
encodesource=convolutionencode（dsource）;

for?i=1:N
????%?the?received?signal?at?the?detection?for?the?ith?symbolis:
????n=sgma*randn（12）;????j=2*i;??????????????????????%?2?normal?distributed?r.v?with?0?variance?sgma
????if?（（encodesource（1j-1）==0）?&?（encodesource（1j）==0））?
????????r=s00+n;
????elseif?（（encodesource（1j-1）==0）?&?（encodesource（1j）==1））?
????????r=s01+n;
????elseif?（（encodesource（1j-1）==1）?&?（encodesource（1j）==0））?
????????r=s10+n;
????else?
????????r=s11+n;
????end;
????%?The?correlation?metrics?are?computed?below
????c00=dot（rs00）;?c01=dot（rs01）;?c10=dot（rs10）;?c11=dot（rs11）;
????%?The?decision?on?the?ith?symbol?is?made?next
????c_max=max（[c00c01c10c11]）;
????if?（c00==c_max）?decis1=0;?decis2=0;
????elseif?（c01==c_max）?decis1=0;?decis2=1;
????elseif?（c10==c_max）?decis1=1;?decis2=0;
????else?decis1=1;?decis2=1;
????end;
????%?Increment?the?error?counter?if?the?decision?is?not?correct
????symbolerror=0;
????if?（decis1~=encodesource（1j-1））?numofbiterror=numofbiterror+1;?symbolerror=1;?
????end;
????if?（decis2~=encodesource（1j））?numofbiterror=numofbiterror+1;?symbolerror=1;?
????end;
????if?（symbolerror==1）?numofsymbolerror=numofsymbolerror+1;?
????end;
????decode（1j-1）=decis1;?decode（1j）=decis2;
end
counter=counter+1;
end
ps1=numofsymbolerror/（N*counter）;??????????????????????????%?since?there?are?totally?N?symbols
pb1=numofbiterror/（2*N*counter）;?????????????????????????%?since?2N?bits?are?transmitted?

count=0;
correctcode=viterbidecode（decode）
for?i=1:N-1
????if?correctcode（1i）~=dsource（1i）
????????count=count+1;
????end

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

?????文件?????151040??2009-11-25?00:14??圖.doc

?????文件???????3071??2009-11-25?00:08??cm_sm33.m

?????文件???????1561??2009-11-21?14:17??convolutionencode.m

?????文件????????137??2009-11-23?17:10??equal.m

?????文件????????191??2008-10-22?10:36??hamm_dist.m

?????文件???????1395??2009-11-25?00:12??QPSK_System_BER_Simulation.m

?????文件???????6441??2009-11-24?15:46??viterbidecode.m

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

???????????????163836????????????????????7