function BER = Center (SNR)global FLAG_AWGN;global FLAG_MULTIPATH;global Num_Channel;global Num_Bit;Num_Bit=2^9;% Num_Sym=Num_Bit/4; %%%%%%%%%%%%Num_ErrorBit_Sum=0;Num_Packet = 1000;i=1;while( i <= Num_Packet )        [ BitData, TransData ] = Transmit ( );    [ RecData, ChanData ]  = Channel( TransData, SNR );          [ DeMapBitData ]       = Receive( RecData, ChanData );        Num_ErrorBit = sum(xor(BitData,DeMapBitData));        Num_ErrorBit_Sum = Num_ErrorBit_Sum + Num_ErrorBit;    if( (i==Num_Packet) && (Num_Packet<100000) )        if( Num_ErrorBit_Sum < 100 )            Num_Packet = Num_Packet + 1000;        end    end    i=i+1;    endBER=Num_ErrorBit_Sum / (Num_Bit*Num_Packet);