prbs_generator.m

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%  Property of Freescale
%  Freescale Confidential Proprietary
%  Freescale Copyright (C) 2005 All rights reserved
%  ----------------------------------------------------------------------------
%  $RCSfile: PRBS_generator.m.rca $
%  $Revision: 1.4 $
%  $Date: Mon Oct 30 18:36:32 2006 $
%  Target: Matlab
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%***************************************************************************
%  802.16-2004 OFDMA PHY - PRBS_generator  uplink function
%
%    Description: This function generates the PRBS sequence for the
%                 data modulation. The data modulator takes care of the
%                 symbol offset.
%
%    Input:
%           UL_IDCell: Data Structure that contains zone configuration
%           seg_num:   Segment Number
%           symb_offset:  Symbol offset from frame start
%
%           Nused_PRBS: number of subcarriers used (including DC)
%
%     Output:
%           PRBS_seq:         PRBS sequence ( +/- 1 )
%
%    Functions:         N/A
%
%    Data Files:        N/A
%
%***************************************************************************

%-- Matlab files used by this file
%-- End of list

function PRBS_seq = PRBS_generator(UL_IDCell,seg_num,symb_offset,Nused_PRBS)

if seg_num<0 | seg_num>2
    error('Error: Segment number must be 0, 1 or 2.');
end

%IDCell evaluation
IDCellB = bitand(UL_IDCell,[1 2 4 8 16])~=0; %filter and flip five LSBs

%segment number evaluation
SegmentNrInc  = seg_num + 1;
SegmentNrIncB = bitand(SegmentNrInc,[1 2])~=0; %filter and flip two LSBs

%symbol offset evaluation
Symb_offsetB = bitand(symb_offset,[1 2 4 8])~=0; %filter and flip four LSBs

%PRBS initial vector
PRBS = [Symb_offsetB , SegmentNrIncB , IDCellB];

% Generate PRBS sequence for the usefull carriers within symbol and for 32
% additional carriers (to consider the symbol offset)
for (k=1:Nused_PRBS+32)
    PRBS_seq(k,1) = 1 - PRBS(11)*2;
    PRBS  = [bitxor(PRBS(9),PRBS(11)) PRBS(1:10)];
end