EqualizerTimeDomainOverlapandsave

 Time domain equalization of the received signal efficiently performed using the
 overlap-and-save algorithm.

 function [ r_eq ] = EqualizerTimeDomainOverlapandsave( r, C, N, K_ov, criterion, Para )
 function [ r_eq ] = EqualizerTimeDomainOverlapandsave( r, C, N, K_ov, criterion, Para, B )

 The function works for SISO systems and is not dependent on a specific
 modulation format.

 Input arguments:

   r: received signal. Size: vector [1, nFrameSamples].

   C: channel impulse response. Multidimensional array [1, 1, ~].

   N: block size of the overlap-and-save algorithm.

   K_ov: discarded samples from each block of N samples, needs to be even.

   criterion: determines the criterion to use. Several 
 options are possible: 

       'ZF': zero forcing.

       'MMSE': minimum mean squared error.

       'Specific': the specific equalizing matrices given in the function
       argument B should be provided and will be used for equalization.
       Argument C is not regarded.

   B: the equalizing matrices at each subcarrier should be provided if
   'Specific' equalizer type is chosen.%
   Para: structure containing the modulation parameters.

 Ouput arguments:

   r_eq: equalized signal. Size: vector [1, nFrameSamples].

0001 function [ r_eq ] = EqualizerTimeDomainOverlapandsave( r, C, N, K_ov, criterion, Para, B )
0002 % Time domain equalization of the received signal efficiently performed using the
0003 % overlap-and-save algorithm.
0004 %
0005 % function [ r_eq ] = EqualizerTimeDomainOverlapandsave( r, C, N, K_ov, criterion, Para )
0006 % function [ r_eq ] = EqualizerTimeDomainOverlapandsave( r, C, N, K_ov, criterion, Para, B )
0007 %
0008 % The function works for SISO systems and is not dependent on a specific
0009 % modulation format.
0010 %
0011 % Input arguments:
0012 %
0013 %   r: received signal. Size: vector [1, nFrameSamples].
0014 %
0015 %   C: channel impulse response. Multidimensional array [1, 1, ~].
0016 %
0017 %   N: block size of the overlap-and-save algorithm.
0018 %
0019 %   K_ov: discarded samples from each block of N samples, needs to be even.
0020 %
0021 %   criterion: determines the criterion to use. Several
0022 % options are possible:
0023 %
0024 %       'ZF': zero forcing.
0025 %
0026 %       'MMSE': minimum mean squared error.
0027 %
0028 %       'Specific': the specific equalizing matrices given in the function
0029 %       argument B should be provided and will be used for equalization.
0030 %       Argument C is not regarded.
0031 %
0032 %   B: the equalizing matrices at each subcarrier should be provided if
0033 %   'Specific' equalizer type is chosen.%
0034 %   Para: structure containing the modulation parameters.
0035 %
0036 % Ouput arguments:
0037 %
0038 %   r_eq: equalized signal. Size: vector [1, nFrameSamples].
0039 %
0040 
0041 
0042 
0043 % This file is part of WaveComBox: www.wavecombox.com and is distributed under the terms of the MIT license. See accompanying LICENSE file.
0044 % Original author: François Rottenberg, May 4, 2018.
0045 % Contributors:
0046 % Change log:
0047 
0048 if Para.N_R==1 && Para.N_T==1
0049     nFrameSamples=length(r);
0050     H=squeeze(fft(C,N)).';
0051     switch criterion
0052         case 'ZF'
0053             B=1./H;
0054         case 'MMSE'
0055             % Noise power
0056             Es_N0=10.^(Para.Es_N0_dB/10);
0057             B=conj(H)./(abs(H).^2+1/Es_N0);
0058         case 'Specific'
0059             if exist('B','var')==0
0060                error('Argument B missing for criterion "Specific"') 
0061             end
0062         otherwise
0063             error('Equalizer type not existing')
0064     end
0065     iter=ceil((nFrameSamples)/(N-K_ov));
0066     for index_iter=1:iter
0067         if(index_iter==1)
0068             block=[zeros(1,K_ov/2), r((index_iter-1)*(N-K_ov)+1:(index_iter)*(N-K_ov)+K_ov/2)];
0069         elseif(index_iter==iter)
0070             block=[r((index_iter-1)*(N-K_ov)-K_ov/2+1:nFrameSamples) zeros(1,(index_iter)*(N-K_ov)+K_ov/2-nFrameSamples)];
0071         elseif (index_iter)*(N-K_ov)+K_ov/2 > nFrameSamples
0072             block=[r((index_iter-1)*(N-K_ov)-K_ov/2+1:end) zeros(1,(index_iter)*(N-K_ov)+K_ov/2-nFrameSamples)];
0073         else
0074             block=r((index_iter-1)*(N-K_ov)-K_ov/2+1:(index_iter)*(N-K_ov)+K_ov/2);
0075         end
0076         temp=fft(block);
0077         for m=1:N
0078             temp(m)=B(m)*temp(m);
0079         end
0080         temp= ifft(temp);
0081         r_eq((index_iter-1)*(N-K_ov)+1:(index_iter)*(N-K_ov))=temp(K_ov/2+1:end-K_ov/2);
0082     end
0083     r_eq=r_eq(1:nFrameSamples);   
0084 
0085 else
0086     if Para.N_T>Para.N_R
0087         error('Error: N_T>N_R')
0088     else
0089         error('Error: MIMO setting not yet available')
0090 
0091     end
0092     
0093 end
0094 
0095 
0096       
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0109 end
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