channelestimation.h

数字音频广播中的信道估计算法在计算机上的算法实现

/******************************************************************************\
 * Technische Universitaet Darmstadt, Institut fuer Nachrichtentechnik
 * Copyright (c) 2001
 *
 * Author(s):
 *	Volker Fischer
 *
 * Description:
 *	See ChannelEstimation.cpp
 *
 ******************************************************************************
 *
 * This program 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 2 of the License, or (at your option) any later 
 * version.
 *
 * This program 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, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
\******************************************************************************/

#if !defined(CHANEST_H__3B0BA660_CA63_4344_BB2B_23E7A0D31912__INCLUDED_)
#define CHANEST_H__3B0BA660_CA63_4344_BB2B_23E7A0D31912__INCLUDED_

#include "../Parameter.h"
#include "../util/Modul.h"
#include "../ofdmcellmapping/OFDMCellMapping.h"
#include "../ofdmcellmapping/CellMappingTable.h"
#include "../tables/TableQAMMapping.h"
#include "../matlib/Matlib.h"
#include "TimeLinear.h"
#include "TimeWiener.h"

#ifdef HAVE_DFFTW_H
# include <dfftw.h>
#else
# include <fftw.h>
#endif

#include "../sync/TimeSyncTrack.h"


/* Definitions ****************************************************************/
#define LEN_WIENER_FILT_FREQ_RMA		6
#define LEN_WIENER_FILT_FREQ_RMB		11
#define LEN_WIENER_FILT_FREQ_RMC		11
#define LEN_WIENER_FILT_FREQ_RMD		13

/* Time constant for IIR averaging of fast signal power estimation */
#define TICONST_SNREST_FAST				((CReal) 30.0) /* sec */

/* Time constant for IIR averaging of slow signal power estimation */
#define TICONST_SNREST_SLOW				((CReal) 100.0) /* sec */

/* Time constant for IIR averaging of MSC signal / noise power estimation */
#define TICONST_SNREST_MSC				((CReal) 1.0) /* sec */

/* Initial value for SNR */
#define INIT_VALUE_SNR_WIEN_FREQ_DB		((_REAL) 30.0) /* dB */

/* SNR estimation initial SNR value */
#define INIT_VALUE_SNR_ESTIM_DB			((_REAL) 20.0) /* dB */

/* Wrap around bound for calculation of group delay. It is wraped by the 2 pi
   periodicity of the angle() function */
#define WRAP_AROUND_BOUND_GRP_DLY		((_REAL) 4.0)

/* Set length of history for delay values for minimum search. Since the
   delay estimation is optimized for channel estimation performance and
   therefore the delay is usually estimated as too long, it is better for the
   log file to use the minimum value in a certain time period for a good
   estimate of the true delay */
#define LEN_HIST_DELAY_LOG_FILE_S		((CReal) 1.0) /* sec */


/* Classes ********************************************************************/
class CChannelEstimation : public CReceiverModul<_COMPLEX, CEquSig>
{
public:
	CChannelEstimation() : iLenHistBuff(0), TypeIntFreq(FWIENER), 
		TypeIntTime(TWIENER), eDFTWindowingMethod(DFT_WIN_HAMM),
		TypeSNREst(SNR_FAC), bInterfConsid(FALSE) {}
	virtual ~CChannelEstimation() {}

	enum ETypeIntFreq {FLINEAR, FDFTFILTER, FWIENER};
	enum ETypeIntTime {TLINEAR, TWIENER};
	enum ETypeSNREst {SNR_FAC, SNR_PIL};

	void GetTransferFunction(CVector<_REAL>& vecrData,
		CVector<_REAL>& vecrGrpDly,	CVector<_REAL>& vecrScale);
	void GetAvPoDeSp(CVector<_REAL>& vecrData, CVector<_REAL>& vecrScale, 
					 _REAL& rLowerBound, _REAL& rHigherBound,
					 _REAL& rStartGuard, _REAL& rEndGuard, _REAL& rPDSBegin,
					 _REAL& rPDSEnd);
	void GetSNRProfile(CVector<_REAL>& vecrData, CVector<_REAL>& vecrScale);

	CTimeLinear* GetTimeLinear() {return &TimeLinear;}
	CTimeWiener* GetTimeWiener() {return &TimeWiener;}
	CTimeSyncTrack* GetTimeSyncTrack() {return &TimeSyncTrack;}

	/* Set (get) frequency and time interpolation algorithm */
	void SetFreqInt(ETypeIntFreq eNewTy) {TypeIntFreq = eNewTy;}
	ETypeIntFreq GetFreqInt() {return TypeIntFreq;}
	void SetTimeInt(ETypeIntTime eNewTy) {TypeIntTime = eNewTy;
		SetInitFlag();}
	ETypeIntTime GetTimeInt() const {return TypeIntTime;}

	void SetIntCons(const _BOOLEAN bNewIntCons) {bInterfConsid = bNewIntCons;}
	_BOOLEAN GetIntCons() {return bInterfConsid;}


	/* Which SNR estimation algorithm */
	void SetSNREst(ETypeSNREst eNewTy) {TypeSNREst = eNewTy; SetInitFlag();}
	ETypeSNREst GetSNREst() {return TypeSNREst;}

	_BOOLEAN GetSNREstdB(_REAL& rSNREstRes) const;
	_REAL GetMSCMEREstdB(); /* MER on MSC cells */
	_REAL GetMSCWMEREstdB(); /* Weighted MER on MSC cells */
	_BOOLEAN GetSigma(_REAL& rSigma);
	_REAL GetDelay() const;
	_REAL GetMinDelay();

	void StartSaRaOffAcq() {TimeSyncTrack.StartSaRaOffAcq(); SetInitFlag();}

protected:
	enum EDFTWinType {DFT_WIN_RECT, DFT_WIN_HAMM};
	EDFTWinType				eDFTWindowingMethod;

	int						iNumSymPerFrame;

	CChanEstTime*			pTimeInt;

	CTimeLinear				TimeLinear;
	CTimeWiener				TimeWiener;

	CTimeSyncTrack			TimeSyncTrack;

	ETypeIntFreq			TypeIntFreq;
	ETypeIntTime			TypeIntTime;
	ETypeSNREst				TypeSNREst;

	int						iNumCarrier;

	CMatrix<_COMPLEX>		matcHistory;

	int						iLenHistBuff;

	int						iScatPilFreqInt; /* Frequency interpolation */
	int						iScatPilTimeInt; /* Time interpolation */

	CComplexVector			veccChanEst;
	CRealVector				vecrSqMagChanEst;

	int						iFFTSizeN;

	CReal					rGuardSizeFFT;

	CRealVector				vecrDFTWindow;
	CRealVector				vecrDFTwindowInv;

	int						iLongLenFreq;
	CComplexVector			veccPilots;
	CComplexVector			veccIntPil;
	CFftPlans				FftPlanShort;
	CFftPlans				FftPlanLong;

	int						iNumIntpFreqPil;

	CReal					rLamSNREstFast;
	CReal					rLamSNREstSlow;
	CReal					rLamMSCSNREst;

	_REAL					rNoiseEst;
	_REAL					rNoiseEstMSCMER;
	_REAL					rSignalEst;
	CVector<_REAL>			vecrNoiseEstMSC;
	CVector<_REAL>			vecrSigEstMSC;
	_REAL					rSNREstimate;
	_REAL					rSNRChanEstCorrFact;
	_REAL					rSNRFACSigCorrFact;
	_REAL					rSNRTotToPilCorrFact;
	_REAL					rSNRSysToNomBWCorrFact;

	_BOOLEAN				bInterfConsid;


	/* Needed for GetDelay() */
	_REAL					rLenPDSEst;
	CShiftRegister<CReal>	vecrDelayHist;
	int						iLenDelayHist;

	int						iStartZeroPadding;

	int						iInitCnt;
	int						iSNREstIniSigAvCnt;
	int						iSNREstIniNoiseAvCnt;
	int						iSNREstInitCnt;
	_BOOLEAN				bSNRInitPhase;
	_REAL CalAndBoundSNR(const _REAL rSignalEst, const _REAL rNoiseEst);


	/* Wiener interpolation in frequency direction */
	void UpdateWienerFiltCoef(CReal rNewSNR, CReal rRatPDSLen,
							  CReal rRatPDSOffs);

	CComplexVector FreqOptimalFilter(int iFreqInt, int iDiff, CReal rSNR, 
									 CReal rRatPDSLen, CReal rRatPDSOffs,
									 int iLength);
	CMatrix<_COMPLEX>		matcFiltFreq;
	int						iLengthWiener;
	CVector<int>			veciPilOffTab;

	int						iDCPos;
	int						iPilOffset;
	int						iNumWienerFilt;
	CComplexMatrix			matcWienerFilter;


	virtual void InitInternal(CParameter& ReceiverParam);
	virtual void ProcessDataInternal(CParameter& ReceiverParam);
};


#endif // !defined(CHANEST_H__3B0BA660_CA63_4344_BB2B_23E7A0D31912__INCLUDED_)