factorgraph.h

根据LDPC码中码子的构造方法中的PEG算法

/**************************************
 *
 * factorgraph
 *
 **************************************/

#ifndef FACTORGRAPH
#define FACTORGRAPH
#undef FACTORGRAPH_DEBUG

#include "BlockCodeGenerator.h"
//#include "TrellisFunctionNode.h"
#include "VariableNode.h"
#include "ChannelTransition.h"
//#include "ISI.h"
#include "ParityCheckNode.h"

class FactorGraph {

private:
  
  // LDPC code parameter
  int N, K, M;

  // maximum number of ones per row in H
  int m;

  // generator matrix
  /* extended factor graph
     int *(*G);
  */

  // compressed parity check matrix
  int *(*T);

  // info bits location within a codeword
  int *infoBitsLocation;

  // arrays of pointers to variable and function nodes
  ChannelTransition *(*channelTransitions);
  //VariableNode *(*channelSymbols);
  //VariableNode *(*trellisStates);
  //TrellisFunctionNode *(*trellisTransitions);
  VariableNode *(*codeBits);
  ParityCheckNode *(*parityChecks);

  /* extended factor graph
     VariableNode *(*infoBits);
     ParityCheckNode *(*codeEquations);
   */

  // local functions
  /* extended factor graph
     LocalFunction *codeEquationsLF;
     LocalFunction *parityChecksLF;
  */
  //LocalFunction *trellisSectionLF;

  // auxiliary methods (uses to build the connections in the factor graph)
  // (returns an array containing the number of 1s in each row/column of G and H, respectively)
  /* extended factor graph
     void getOnesInRowsOfG(int *ones);
     void getOnesInColsOfG(int *ones);
  */
  void getOnesInRowsOfH(int *ones);
  void getOnesInColsOfH(int *ones);

public:
  
  // constructor
  FactorGraph(const BlockCodeGenerator *blockCodeGenerator);

  // destructor
  ~FactorGraph();

  // probabilities that are used to decide which information word was sent
  double *(*probabilities);

  // initialization for a new received block
  void initialize(double *(*prob));

  // perform an update
  void update(void);

  // perform a BCJR update on the trellis part of the factor graph
  //void BCJRupdate(void);

  // perform an distributed update on the parity-check part of the factor graph
  void LDPCupdate(void);
  void FactorGraph::LDPCupdateExBitK(int k); // BitNode k not updated.
  void FactorGraph::LDPCupdateExBitK(int k, int j); 
  //void LDPCupdatePartial(void);
  // get a code word
  void getCodeWord(int *codeWord, double *codeWordLLR);

  void getCodeWord(int *codeWord, double *codeWordLLR, int pos);
  // get the absolute value of the syndrome
  int getAbsSyndrome(int *codeWord);

  // Gausselimination of G*infobits = codeword;
  void decodeCodeWord(int *codeWord, int *decidedBits);

  // reset the whole graph
  void reset(void);
  
  // get the probabilities of the last trellis state
  //void getEndStateProbabilities(double *(*startStateProbabilities));

  // issues a list of all nodes belonging to this graph and 
  // writes the output to a file
  //void draw(char *filename, int iteration);

  // starts matlab to draw the factor graph
  //void writeMatlabFile(char *filename, int iteration);
  //void writeDatFile(char *filename, int iteration);

  // test method
  //static void test(void);  

};

#endif