??COFDM - v2.rar_COFDM_V2 _coherent_coherent ofdm

function varargout=pattern(ptype,nseed,options) %PATTERN Create the sequence pattern with rules. % PAT=PATTERN(PTYPE,NSEED,OPTIONS) returns in PAT a sequence of Nsymb % integers representing the symbol-pattern for a digital modulation. % Nsymb=GSTATE.NSYMB see RESET_ALL. In absence of OPTIONS the pattern is % a bit-pattern, i.e. a vector of 0 and 1. % % PTYPE is the type of the pattern and can be one of the following: % % 'debruijn': creates a De Bruijn sequence (DBS) (each subsequence of % length log2(Nsymb) appears exactly once in a DBS) [1-2]. In % the binary case, a DBS is a pseudo random binary sequence % (PRBS) with an additional zero added to to the longest % sequence of 0. % % NSEED is the DBS seed. 0 <= NSEED < Nsymb/4 yields a unique % DBS, i.e. it is not possible to obtain the same DBS with a % different NSEED, neither with a circular shift. % For NSEED >= Nsymb/4 the DBS is not unique, hence PATTERN % generates a circular random delayed version of a DBS % with NSEED < Nsymb/4. % NSEED must be < Nsymb/4*(Nsymb-1). % It is not possible to have the same sequence for different % NSEED. % % 'random': creates a uniform distributed random sequence. % % <sequence of numbers>: E.g. '20104101' creates a periodic % repetition of the sequence up to length Nsymb, and % truncates when necessary. % For instance, with Nsymb=16 returns 2010410120104101. % The sequence can be a string or a vector of double, e.g. % '20104101' or [2 0 1 0 4 1 0 1] % % <file>: reads the pattern from 'file' using LOAD. 'file' contains % the pattern for the channel. % E.g. Nsymb=8, with patterns '30101210', 'file' can have any % form, e.g.: % % 3 0 1 0 or 3 0 1 0 1 2 1 0 % 1 2 1 0 % % % OPTIONS is an optional parameter containing: % % OPTIONS.alphabet: is the alphabet of the pattern. % E.g. PAT=PATTERN('debruijn',0,OPTIONS) with OPTIONS.alphabet=4 % returns: % % PAT=[1 1 2 3 0 3 1 3 3 2 2 1 0 2 0 0] % % i.e. a DBS sequence with symbols (0,1,2,3) containing all % couples of symbols exactly once. % % E.g. PAT=PATTERN('random',OPTIONS) with OPTIONS.alphabet=8 % may return: % % PAT=[6 3 7 6 6 2 3 7 3 2 5 4 4 2 0 2] % % % [PAT,BMAT] = PATTERN(PTYPE,NSEED,OPTIONS) returns in BMAT the binary % representation of PAT. BMAT is a matrix of size % [Nsymb,ceil(log2(OPTIONS.alphabet))]. % % Example: For a QPSK modulation, the two columns of BMAT represent the % in-phase and quadrature component of a pseudo random quaternary % sequence (PRQS), [2]. % % Note: PAT and BMAT are of type double. % % See also ELECTRICSOURCE, PAT_DECODER % % % [1] F. S. Annexstein, "Generating De Bruijn Sequences: An Efficient % Implementation," IEEE Transaction on Computers, vol. 48, no. 2, % pp. 198-200, Feb. 1997. % % [2] D. v. d. Borne et al, "Bit pattern dependence in optical DQPSK % modulation," Electronic Letters, vol. 43, no. 22, Oct. 2007 % % Author: Paolo Serena, 2009 % University of Parma, Italy % This file is part of Optilux, the optical simulator toolbox. % Copyright (C) 2009 Paolo Serena, <serena@tlc.unipr.it> % % Optilux is free software; you can redistribute it and/or modify % it under the terms of the GNU General Public License as published by % the Free Software Foundation; either version 3 of the License, or % (at your option) any later version. % % Optilux is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the % GNU General Public License for more details. % % You should have received a copy of the GNU General Public License % along with this program. If not, see <http://www.gnu.org/licenses/>. global GSTATE % GSTATE is a structure whose fields are defined in reset_all.m fromfile = 0; if strcmp(ptype,'debruijn') % PSEUDO-RANDOM BINARY SEQUENCE if nargin == 1 error('Missing nseed'); else if nargin == 3 nfnames = fieldnames(options); if any(strcmp(nfnames,'alphabet')) q = log2(options.alphabet); if rem(q,1) error(['De Bruijn sequence can be implemented only for ',... ' power of 2 alphabets']); end else q = 1; end else q = 1; % default: binary end maxseed = GSTATE.NSYMB*(GSTATE.NSYMB-1)/4; % largest seed if nseed(1) > maxseed, error('nseed must be <= %d',maxseed); end lg2 = log2(GSTATE.NSYMB); if rem(lg2,q) error(['The De Bruijn sequence does not exist! log2(number ',... 'of symbols)=%d is not a multiple of log2(alphabet length)=%d.'],... lg2,q); end [pat,tmat] = debruijn_seq(log2(GSTATE.NSYMB)/q,nseed(1),q); varargout{2} = tmat'; end elseif strcmp(ptype,'random') % RANDOM PATTERN if nargin >= 2 if nargin == 2, options = nseed;end nfnames = fieldnames(options); if any(strcmp(nfnames,'alphabet')) qq = options.alphabet; else qq = 2; end else qq = 2; end pat = floor(qq.*rand(1,GSTATE.NSYMB)); varargout{2} = mydec2bin(pat,log2(qq)); elseif isnumeric(ptype) % VECTOR OF SYMBOLS if nargin >= 2 if nargin == 2, options = nseed;end nfnames = fieldnames(options); if any(strcmp(nfnames,'alphabet')) q = log2(options.alphabet); if rem(q,1) error(['Sequence can be implemented only for ',... ' power of 2 alphabets']); end else q = 1; end else q = 1; % default: binary end pat = myseq(ptype,GSTATE.NSYMB); % periodically repeat the pattern varargout{2} = mydec2bin(pat,q); elseif (min(double(ptype-48)) >= 0 && max(double(ptype-48)) <= 9) % STRING if nargin >= 2 if nargin == 2, options = nseed;end nfnames = fieldnames(options); if any(strcmp(nfnames,'alphabet')) q = log2(options.alphabet); if rem(q,1) error(['Sequence can be implemented only for ',... ' power of 2 alphabets']); end else q = 1; end else q = 1; % default: binary end ptype2 = double(ptype-48); pat = myseq(ptype2,GSTATE.NSYMB); % periodically repeat the pattern varargout{2} = mydec2bin(pat,q); elseif exist(ptype,'file') == 2 pat = loadpattern(ptype,GSTATE.NSYMB); fromfile = 1; varargout{2} = mydec2bin(pat); else error('String ptype unknown'); end varargout{1} = pat(:); if GSTATE.PRINT %%%%% PRINT outfile = [GSTATE.DIR,'/simul_out']; fid = fopen(outfile,'a'); fprintf(fid,'========================================\n'); fprintf(fid,'=== pattern ===\n'); fprintf(fid,'========================================\n\n'); if strcmp(ptype,'debruijn') fprintf(fid,'%s pattern with seed %d\n',ptype,nseed(1)); elseif strcmp(ptype,'random') fprintf(fid,'%s pattern\n',ptype); elseif fromfile == 1 fprintf(fid,'user-defined pattern from file %s\n',ptype); else fprintf(fid,'Periodic pattern:\n'); if isnumeric(ptype), ptype=char(ptype+48);end fprintf(fid,'...%s...',ptype); end if exist('options','