theperfectrake.m

用matlab程序实现WCDMA系统的仿真

function [y,z]=ThePerfectRake(insig,delays,sigLength,PShape,ChipSamples,chan_code,N,DPCCH_code,N_pilot,scramble_code)
%*******************************************************************************
%function [y,z]=ThePerfectRake(insig,delays,sigLength)
%
%Copyright 2002 The Mobile and Portable Radio Research Group
%
%This function emulates the operation of a "Perfect" rake receiver.  This 
%receiver is "Perfect" in the sense that has perfect knowledge of the 
%multipath delays (but not necessarily the amplitudes.  
%
%This receier tunes one tap to each delay and extracts the signal energy at 
%that delay.  Soft decisions are made at each delay component and then combind in 
%and equal gain fashion.  Then a hard decision is made.  The pilot symbols are 
%used to estimate the phase rotation due to the channel.  These esitmates are 
%updated every slot.
%
%Parameters
%   Input
%      insig       Vector   Incoming Signal
%      delays      Vector   Contains the discrete time delays of the multipath
%                           components
%      sigLength   Scalar   Contains the length of the transmitted signal
%      PShape      Vector   Reciever Filter Impuse response
%      ChipSamples Scalar   Number of Samples per Chip
%   Output
%      y           Vector   Contains the extracted data symbols
%                  or Matrix
%      z           Vector   Contains the extracted control symbols
%
%*******************************************************************************
NumDelays=length(delays);
ChipsPerSlot=2560;
SF_Control=256;
SF_Data=length(chan_code(1,:));
ControlBitsPerSlot=ChipsPerSlot/SF_Control;
DataBitsPerSlot=ChipsPerSlot/SF_Data;

for k=1:NumDelays
   %Receiver Matched Filter
   tap_sig=insig(1+delays(k):sigLength+delays(k));
   received_signal=WCDMAReceiveFilter(tap_sig.',PShape,ChipSamples);
   
   %Descramble the signal
   unscrambled_signal = received_signal.*conj(double(scramble_code));
   
   %Despread the signal
   [Rcvd_Control_Sig,Rcvd_Data_Sig]=WCDMADespread(unscrambled_signal,chan_code,N);
   
   %Estimate Phase Offset
   PhaseOffset = EstPhaseOffset(Rcvd_Control_Sig,DPCCH_code,N_pilot);
   %Note that PhaseOffset will be a vector of length 15, one estimate per slot
   
   %Apply Phase Offset to Received Control Signal and Received Data Signal 
   
   for m=1:15
      Controlindex=(ControlBitsPerSlot*(m-1)+1):ControlBitsPerSlot*m;
      Dataindex=(DataBitsPerSlot*(m-1)+1):DataBitsPerSlot*m;
      RotatedRcvdControlSig(k,Controlindex)=PhaseOffset(m)*Rcvd_Control_Sig(Controlindex);
      RotatedRcvdDataSig(:,Dataindex,k)=PhaseOffset(m)*Rcvd_Data_Sig(:,Dataindex);
   end
   
end

%Implement Equal Gain Combiner
CombinedControlSig=sum(RotatedRcvdControlSig,1);
CombinedDataSig=sum(RotatedRcvdDataSig,3);

% perform hard decisoins
RcvdCntlBits=sign(real(CombinedControlSig));

switch N
case 1
   RcvdDataBits=sign(real(CombinedDataSig));
case 2
   RcvdDataBits(1,:)=sign(real(CombinedDataSig));
   RcvdDataBits(2,:)=sign(imag(CombinedDataSig));
case 3
   RcvdDataBits(1,:)=sign(real(CombinedDataSig(1,:)));
   RcvdDataBits(2,:)=sign(imag(CombinedDataSig(1,:)));
   RcvdDataBits(3,:)=sign(real(CombinedDataSig(2,:)));   
case 4
   RcvdDataBits(1,:)=sign(real(CombinedDataSig(1,:)));
   RcvdDataBits(2,:)=sign(imag(CombinedDataSig(1,:)));
   RcvdDataBits(3,:)=sign(real(CombinedDataSig(2,:)));   
   RcvdDataBits(4,:)=sign(imag(CombinedDataSig(2,:)));   
case 5
   RcvdDataBits(1,:)=sign(real(CombinedDataSig(1,:)));
   RcvdDataBits(2,:)=sign(imag(CombinedDataSig(1,:)));
   RcvdDataBits(3,:)=sign(real(CombinedDataSig(2,:)));   
   RcvdDataBits(4,:)=sign(imag(CombinedDataSig(2,:)));   
   RcvdDataBits(5,:)=sign(real(CombinedDataSig(3,:)));   
case 6
   RcvdDataBits(1,:)=sign(real(CombinedDataSig(1,:)));
   RcvdDataBits(2,:)=sign(imag(CombinedDataSig(1,:)));
   RcvdDataBits(3,:)=sign(real(CombinedDataSig(2,:)));   
   RcvdDataBits(4,:)=sign(imag(CombinedDataSig(2,:)));   
   RcvdDataBits(5,:)=sign(real(CombinedDataSig(3,:)));   
   RcvdDataBits(6,:)=sign(imag(CombinedDataSig(3,:)));   
otherwise
   error('N cannot exceed 6 or be less than 1')
end
y=RcvdDataBits;
z=RcvdCntlBits;