FWGN_tf.m

function [FadMtx,tf]=FWGN_tf(Np,fm_Hz,N,M,Nfosf,type,varargin)
% fading generation using FWGN with fitering in the time domain
% Inputs:
%   Np       : # of multipath
%   fm_Hz   : A vector of maximum Doppler frequency of each path[Hz]
%   N        : # of independent random realization
%   M        : Length of Doppler filter, i.e, size of IFFT
%   Nfosf   : Fading oversampling factor 
%   type    : Doppler spectrum type
%            'flat'=flat, 'class'=calssical, 'sui'=spectrum of SUI channel
%            '3gpprice'=rice spectrum of 3GPP 
%   Outputs:
%     FadMtx  : Np x N fading matrix 

%MIMO-OFDM Wireless Communications with MATLAB¢ç   Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang
%2010 John Wiley & Sons (Asia) Pte Ltd

% generates scatter components having CN(0,1)
if isscalar(fm_Hz), fm_Hz= fm_Hz*ones(1,Np);  end
fmax= max(fm_Hz);
path_wgn= sqrt(1/2)*complex(randn(Np,N),randn(Np,N));
for p=1:Np
   filt=gen_filter(fm_Hz(p),fmax,M,Nfosf,type,varargin{:});
   path(p,:)=fftfilt(filt,[path_wgn(p,:) zeros(1,M)]); %filtering WGN
end
FadMtx= path(:,M/2+1:end-M/2);
tf=1/(2*fmax*Nfosf); %fading sample time=1/(Max. Doppler BW*Nfosf)
% Normalization to 1
FadMtx= FadMtx./sqrt(mean(abs(FadMtx).^2,2)*ones(1,size(FadMtx,2)));