chcompstc.cpp

在vc上做的802.16d ofdm phy的仿真

//chcomp for stc code
//input length 256
//output length 201 

#include "typedef.h"
#include "chCompStc.h"

void chCompStc (Uint8 stcFlag,
				Int16 *pChCompIn,
				Uint16 chCompLength, //2*ffisize
				PhaseParam *pPhaseShift,
				Int16 *pChCompOut)
//只去处信道的固定频偏和角偏移,不去处信道响应
{
	Int16 i;
	Int16 freqOffsetCoarse;
	double freqOffsetFine;
	Int16 symbolCompIn[804]; 
	Int16 symbolCompFirst[804];
	Int16 sinValue;
	Int16 cosValue;
	Uint16 chCompOutLength;
	Int16 shiftFixPhrase = 14;
	Int16 shiftFreOffset = 15; // (16-1) mod of sine;
	chCompOutLength = chCompLength - 110; //402

	for (i = 0; i < chCompOutLength / 2; i++)
	{
		symbolCompIn[2*i] = pChCompIn[2*i+56];
		symbolCompIn[2*i+1] = pChCompIn[2*i+57];
		symbolCompIn[2*i+402] = pChCompIn[2*i+512+56];
		symbolCompIn[2*i+403] = pChCompIn[2*i+512+57];
		
	}
	
	for (i = 0; i < chCompOutLength / 2; i++)
	{

		symbolCompFirst[2*i] = (Int16)(((Int32)symbolCompIn[2*i] * pPhaseShift[0].fixedPhase[0] 
							  	+ (Int32)symbolCompIn[2*i+1] * pPhaseShift[0].fixedPhase[1])
								>> shiftFixPhrase);
		symbolCompFirst[2*i+1] = (Int16)(((Int32)symbolCompIn[2*i+1] * pPhaseShift[0].fixedPhase[0] 
								- (Int32)symbolCompIn[2*i] * pPhaseShift[0].fixedPhase[1])
								>> shiftFixPhrase);
								
		symbolCompFirst[2*i+402] = (Int16)(((Int32)symbolCompIn[2*i+402] * pPhaseShift[0].fixedPhase[0] 
							  	+ (Int32)symbolCompIn[2*i+403] * pPhaseShift[0].fixedPhase[1])
								>> shiftFixPhrase);
		symbolCompFirst[2*i+403] = (Int16)(((Int32)symbolCompIn[2*i+403] * pPhaseShift[0].fixedPhase[0] 
								- (Int32)symbolCompIn[2*i+402] * pPhaseShift[0].fixedPhase[1])
								>> shiftFixPhrase);
	}
	
	for (i = 0; i < chCompOutLength / 4; i++)
	{
		freqOffsetCoarse =  pPhaseShift[0].freqIq * (100 - i) * 256 / (32767 * PI);
		freqOffsetFine = pPhaseShift[0].freqIq * (100-i) * 256 / (32767 * PI);
		if (freqOffsetCoarse == 0)
		{
			sinValue = freqOffsetFine * 32767 * PI / 256;
			cosValue = 32767 - ((sinValue * sinValue) >> 16);//cosx=1-0.5*x^2
		}
		else
		{
			sinValue = (Int16)(g_sineTable[freqOffsetCoarse] 
					+ (freqOffsetFine - freqOffsetCoarse) * g_sineTable[128-freqOffsetCoarse]);
			cosValue = (Int16)(g_sineTable[128-freqOffsetCoarse] 
					- (freqOffsetFine - freqOffsetCoarse) * g_sineTable[freqOffsetCoarse]);
		}
		
		pChCompOut[2*i] = (Int16)(((Int32)symbolCompFirst[2*i] * cosValue 
							- (Int32)symbolCompFirst[2*i+1] * sinValue)
							>> shiftFreOffset);
		pChCompOut[2*i+1] = (Int16)(((Int32)symbolCompFirst[2*i+1] * cosValue 
							+ (Int32)symbolCompFirst[2*i] * sinValue)
							>> shiftFreOffset);
		pChCompOut[2*(200-i)] = (Int16)(((Int32)symbolCompFirst[2*(200-i)] * cosValue 
								+ (Int32)symbolCompFirst[2*(200-i)+1] * sinValue)
								>> shiftFreOffset);
		pChCompOut[2*(200-i)+1] = (Int16)(((Int32)symbolCompFirst[2*(200-i)+1] * cosValue 
								- (Int32)symbolCompFirst[2*(200-i)] * sinValue)
								>> shiftFreOffset);
								
		pChCompOut[2*i+402] = (Int16)(((Int32)symbolCompFirst[2*i+402] * cosValue 
							- (Int32)symbolCompFirst[2*i+403] * sinValue)
							>> shiftFreOffset);
		pChCompOut[2*i+403] = (Int16)(((Int32)symbolCompFirst[2*i+403] * cosValue 
							+ (Int32)symbolCompFirst[2*i+402] * sinValue)
							>> shiftFreOffset);
		pChCompOut[2*(200-i)+402] = (Int16)(((Int32)symbolCompFirst[2*(200-i)+402] * cosValue 
								+ (Int32)symbolCompFirst[2*(200-i)+403] * sinValue)
								>> shiftFreOffset);
		pChCompOut[2*(200-i)+403] = (Int16)(((Int32)symbolCompFirst[2*(200-i)+403] * cosValue 
								- (Int32)symbolCompFirst[2*(200-i)+402] * sinValue)
								>> shiftFreOffset);
	
	}
	//去处信道的角偏移.
	pChCompOut[200] = symbolCompFirst[200];
	pChCompOut[201] = symbolCompFirst[201];
	pChCompOut[602] = symbolCompFirst[602];
	pChCompOut[603] = symbolCompFirst[603];
	//subcarrier 为0,不用去除freqoffset
	
}