OFDM_GeneratePreamble

 Generates an OFDM preamble.

 function [ d_preamble ] = OFDM_GeneratePreamble(d_TR, Para,
 preamble_type)

 The function works for SISO and some MIMO systems.

 Input arguments:

   d_TR: vector [Para.nSubcarriers, 1] of pilot symbols.

   Para: structure containing the modulation parameters.

   preamble_type: optional, type of preamble, 'synchro' (only for Para.N_T
   == 1) or 'channel_estimation' (by default).

 Outputs arguments:

   d_preamble: preamble symbols. Size: matrix [Para.nSubcarriers,
   Para.PreambleLength] if Para.N_T == 1 and multidimensional array
   [Para.N_T, Para.nSubcarriers, Para.PreambleLength] otherwise

0001 function [ d_preamble ] = OFDM_GeneratePreamble(d_TR, Para, preamble_type)
0002 % Generates an OFDM preamble.
0003 %
0004 % function [ d_preamble ] = OFDM_GeneratePreamble(d_TR, Para,
0005 % preamble_type)
0006 %
0007 % The function works for SISO and some MIMO systems.
0008 %
0009 % Input arguments:
0010 %
0011 %   d_TR: vector [Para.nSubcarriers, 1] of pilot symbols.
0012 %
0013 %   Para: structure containing the modulation parameters.
0014 %
0015 %   preamble_type: optional, type of preamble, 'synchro' (only for Para.N_T
0016 %   == 1) or 'channel_estimation' (by default).
0017 %
0018 % Outputs arguments:
0019 %
0020 %   d_preamble: preamble symbols. Size: matrix [Para.nSubcarriers,
0021 %   Para.PreambleLength] if Para.N_T == 1 and multidimensional array
0022 %   [Para.N_T, Para.nSubcarriers, Para.PreambleLength] otherwise
0023 %
0024 
0025 
0026 % This file is part of WaveComBox: www.wavecombox.com and is distributed under the terms of the MIT license. See accompanying LICENSE file.
0027 % Original author: François Rottenberg, May 3, 2018.
0028 % Contributors:
0029 % Change log:
0030 
0031 d_preamble=zeros(Para.N_T,Para.nSubcarriers,Para.PreambleLength);
0032 F_pilot=1/sqrt(Para.N_T)*exp(-1j*2*pi/Para.N_T*(0:Para.N_T-1)'*(0:Para.N_T-1)  );
0033 
0034 if exist('preamble_type','var')==0
0035     preamble_type='channel_estimation';
0036 end
0037 
0038 switch preamble_type
0039     case 'synchro'
0040         if Para.N_T>1
0041             error('Preamble type "synchro" not yet implemented for N_T>1')
0042         end
0043         for m=Para.PreamblePilotSubcarriers
0044             d_preamble(:,m,1)=d_TR(m);
0045             d_preamble(:,m,2)=d_TR(m);
0046         end
0047     case 'channel_estimation'
0048         for m=Para.PreamblePilotSubcarriers
0049             d_preamble(:,m,1:Para.N_T)=d_TR(m)*F_pilot;
0050         end
0051     otherwise
0052         error('Preamble type not defined')
0053 end
0054 
0055 
0056 if Para.N_T==1
0057     d_preamble=squeeze(d_preamble).';
0058     if length(d_preamble(:,1))~=Para.nSubcarriers
0059        d_preamble=d_preamble.';
0060     end
0061 end
0062 
0063 end
0064