cellular-infrastructure
/
osmo-trx
mirror of https://gerrit.osmocom.org/osmo-trx
9
0
Fork 0
Code Issues Projects Releases Wiki Activity
osmo-trx/Transceiver52M/sigProcLib.cpp

1629 lines
38 KiB
C++
Raw Blame History

/*
* Copyright 2008, 2011 Free Software Foundation, Inc.
*
* This software is distributed under the terms of the GNU Affero Public License.
* See the COPYING file in the main directory for details.
*
* This use of this software may be subject to additional restrictions.
* See the LEGAL file in the main directory for details.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "sigProcLib.h"
#include "GSMCommon.h"
extern "C" {
#include "convolve.h"
#include "scale.h"
}
using namespace GSM;
#define TABLESIZE 1024
/** Lookup tables for trigonometric approximation */
float cosTable[TABLESIZE+1]; // add 1 element for wrap around
float sinTable[TABLESIZE+1];
/** Constants */
static const float M_PI_F = (float)M_PI;
static const float M_2PI_F = (float)(2.0*M_PI);
static const float M_1_2PI_F = 1/M_2PI_F;
/* Precomputed rotation vectors */
static signalVector *GMSKRotationN = NULL;
static signalVector *GMSKReverseRotationN = NULL;
static signalVector *GMSKRotation1 = NULL;
static signalVector *GMSKReverseRotation1 = NULL;
/*
* RACH and midamble correlation waveforms. Store the buffer separately
* because we need to allocate it explicitly outside of the signal vector
* constructor. This is because C++ (prior to C++11) is unable to natively
* perform 16-byte memory alignment required by many SSE instructions.
*/
struct CorrelationSequence {
CorrelationSequence() : sequence(NULL), buffer(NULL)
{
}
~CorrelationSequence()
{
delete sequence;
free(buffer);
}
signalVector *sequence;
void *buffer;
float toa;
complex gain;
};
/*
* Gaussian and empty modulation pulses. Like the correlation sequences,
* store the runtime (Gaussian) buffer separately because of needed alignment
* for SSE instructions.
*/
struct PulseSequence {
PulseSequence() : c0(NULL), c1(NULL), empty(NULL),
c0_buffer(NULL), c1_buffer(NULL)
{
}
~PulseSequence()
{
delete c0;
delete c1;
delete empty;
free(c0_buffer);
free(c1_buffer);
}
signalVector *c0;
signalVector *c1;
signalVector *empty;
void *c0_buffer;
void *c1_buffer;
};
CorrelationSequence *gMidambles[] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL};
CorrelationSequence *gRACHSequence = NULL;
PulseSequence *GSMPulse = NULL;
PulseSequence *GSMPulse1 = NULL;
void sigProcLibDestroy()
{
for (int i = 0; i < 8; i++) {
delete gMidambles[i];
gMidambles[i] = NULL;
}
delete GMSKRotationN;
delete GMSKReverseRotationN;
delete GMSKRotation1;
delete GMSKReverseRotation1;
delete gRACHSequence;
delete GSMPulse;
delete GSMPulse1;
GMSKRotationN = NULL;
GMSKRotation1 = NULL;
GMSKReverseRotationN = NULL;
GMSKReverseRotation1 = NULL;
gRACHSequence = NULL;
GSMPulse = NULL;
GSMPulse1 = NULL;
}
// dB relative to 1.0.
// if > 1.0, then return 0 dB
float dB(float x) {
float arg = 1.0F;
float dB = 0.0F;
if (x >= 1.0F) return 0.0F;
if (x <= 0.0F) return -200.0F;
float prevArg = arg;
float prevdB = dB;
float stepSize = 16.0F;
float dBstepSize = 12.0F;
while (stepSize > 1.0F) {
do {
prevArg = arg;
prevdB = dB;
arg /= stepSize;
dB -= dBstepSize;
} while (arg > x);
arg = prevArg;
dB = prevdB;
stepSize *= 0.5F;
dBstepSize -= 3.0F;
}
return ((arg-x)*(dB-3.0F) + (x-arg*0.5F)*dB)/(arg - arg*0.5F);
}
// 10^(-dB/10), inverse of dB func.
float dBinv(float x) {
float arg = 1.0F;
float dB = 0.0F;
if (x >= 0.0F) return 1.0F;
if (x <= -200.0F) return 0.0F;
float prevArg = arg;
float prevdB = dB;
float stepSize = 16.0F;
float dBstepSize = 12.0F;
while (stepSize > 1.0F) {
do {
prevArg = arg;
prevdB = dB;
arg /= stepSize;
dB -= dBstepSize;
} while (dB > x);
arg = prevArg;
dB = prevdB;
stepSize *= 0.5F;
dBstepSize -= 3.0F;
}
return ((dB-x)*(arg*0.5F)+(x-(dB-3.0F))*(arg))/3.0F;
}
float vectorNorm2(const signalVector &x)
{
signalVector::const_iterator xPtr = x.begin();
float Energy = 0.0;
for (;xPtr != x.end();xPtr++) {
Energy += xPtr->norm2();
}
return Energy;
}
float vectorPower(const signalVector &x)
{
return vectorNorm2(x)/x.size();
}
/** compute cosine via lookup table */
float cosLookup(const float x)
{
float arg = x*M_1_2PI_F;
while (arg > 1.0F) arg -= 1.0F;
while (arg < 0.0F) arg += 1.0F;
const float argT = arg*((float)TABLESIZE);
const int argI = (int)argT;
const float delta = argT-argI;
const float iDelta = 1.0F-delta;
return iDelta*cosTable[argI] + delta*cosTable[argI+1];
}
/** compute sine via lookup table */
float sinLookup(const float x)
{
float arg = x*M_1_2PI_F;
while (arg > 1.0F) arg -= 1.0F;
while (arg < 0.0F) arg += 1.0F;
const float argT = arg*((float)TABLESIZE);
const int argI = (int)argT;
const float delta = argT-argI;
const float iDelta = 1.0F-delta;
return iDelta*sinTable[argI] + delta*sinTable[argI+1];
}
/** compute e^(-jx) via lookup table. */
complex expjLookup(float x)
{
float arg = x*M_1_2PI_F;
while (arg > 1.0F) arg -= 1.0F;
while (arg < 0.0F) arg += 1.0F;
const float argT = arg*((float)TABLESIZE);
const int argI = (int)argT;
const float delta = argT-argI;
const float iDelta = 1.0F-delta;
return complex(iDelta*cosTable[argI] + delta*cosTable[argI+1],
iDelta*sinTable[argI] + delta*sinTable[argI+1]);
}
/** Library setup functions */
void initTrigTables() {
for (int i = 0; i < TABLESIZE+1; i++) {
cosTable[i] = cos(2.0*M_PI*i/TABLESIZE);
sinTable[i] = sin(2.0*M_PI*i/TABLESIZE);
}
}
void initGMSKRotationTables(int sps)
{
GMSKRotationN = new signalVector(157 * sps);
GMSKReverseRotationN = new signalVector(157 * sps);
signalVector::iterator rotPtr = GMSKRotationN->begin();
signalVector::iterator revPtr = GMSKReverseRotationN->begin();
float phase = 0.0;
while (rotPtr != GMSKRotationN->end()) {
*rotPtr++ = expjLookup(phase);
*revPtr++ = expjLookup(-phase);
phase += M_PI_F / 2.0F / (float) sps;
}
GMSKRotation1 = new signalVector(157);
GMSKReverseRotation1 = new signalVector(157);
rotPtr = GMSKRotation1->begin();
revPtr = GMSKReverseRotation1->begin();
phase = 0.0;
while (rotPtr != GMSKRotation1->end()) {
*rotPtr++ = expjLookup(phase);
*revPtr++ = expjLookup(-phase);
phase += M_PI_F / 2.0F;
}
}
static void GMSKRotate(signalVector &x, int sps)
{
signalVector::iterator rotPtr, xPtr = x.begin();
if (sps == 1)
rotPtr = GMSKRotation1->begin();
else
rotPtr = GMSKRotationN->begin();
if (x.isRealOnly()) {
while (xPtr < x.end()) {
*xPtr = *rotPtr++ * (xPtr->real());
xPtr++;
}
}
else {
while (xPtr < x.end()) {
*xPtr = *rotPtr++ * (*xPtr);
xPtr++;
}
}
}
static void GMSKReverseRotate(signalVector &x, int sps)
{
signalVector::iterator rotPtr, xPtr= x.begin();
if (sps == 1)
rotPtr = GMSKReverseRotation1->begin();
else
rotPtr = GMSKReverseRotationN->begin();
if (x.isRealOnly()) {
while (xPtr < x.end()) {
*xPtr = *rotPtr++ * (xPtr->real());
xPtr++;
}
}
else {
while (xPtr < x.end()) {
*xPtr = *rotPtr++ * (*xPtr);
xPtr++;
}
}
}
signalVector *convolve(const signalVector *x,
const signalVector *h,
signalVector *y,
ConvType spanType, int start,
unsigned len, unsigned step, int offset)
{
int rc, head = 0, tail = 0;
bool alloc = false, append = false;
const signalVector *_x = NULL;
if (!x || !h)
return NULL;
switch (spanType) {
case START_ONLY:
start = 0;
head = h->size();
len = x->size();
append = true;
break;
case NO_DELAY:
start = h->size() / 2;
head = start;
tail = start;
len = x->size();
append = true;
break;
case CUSTOM:
if (start < h->size() - 1) {
head = h->size() - start;
append = true;
}
if (start + len > x->size()) {
tail = start + len - x->size();
append = true;
}
break;
default:
return NULL;
}
/*
* Error if the output vector is too small. Create the output vector
* if the pointer is NULL.
*/
if (y && (len > y->size()))
return NULL;
if (!y) {
y = new signalVector(len);
alloc = true;
}
/* Prepend or post-pend the input vector if the parameters require it */
if (append)
_x = new signalVector(*x, head, tail);
else
_x = x;
/*
* Four convovle types:
* 1. Complex-Real (aligned)
* 2. Complex-Complex (aligned)
* 3. Complex-Real (!aligned)
* 4. Complex-Complex (!aligned)
*/
if (h->isRealOnly() && h->isAligned()) {
rc = convolve_real((float *) _x->begin(), _x->size(),
(float *) h->begin(), h->size(),
(float *) y->begin(), y->size(),
start, len, step, offset);
} else if (!h->isRealOnly() && h->isAligned()) {
rc = convolve_complex((float *) _x->begin(), _x->size(),
(float *) h->begin(), h->size(),
(float *) y->begin(), y->size(),
start, len, step, offset);
} else if (h->isRealOnly() && !h->isAligned()) {
rc = base_convolve_real((float *) _x->begin(), _x->size(),
(float *) h->begin(), h->size(),
(float *) y->begin(), y->size(),
start, len, step, offset);
} else if (!h->isRealOnly() && !h->isAligned()) {
rc = base_convolve_complex((float *) _x->begin(), _x->size(),
(float *) h->begin(), h->size(),
(float *) y->begin(), y->size(),
start, len, step, offset);
} else {
rc = -1;
}
if (append)
delete _x;
if (rc < 0) {
if (alloc)
delete y;
return NULL;
}
return y;
}
static bool generateC1Pulse(int sps, PulseSequence *pulse)
{
int len;
if (!pulse)
return false;
switch (sps) {
case 4:
len = 8;
break;
default:
return false;
}
pulse->c1_buffer = convolve_h_alloc(len);
pulse->c1 = new signalVector((complex *)
pulse->c1_buffer, 0, len);
pulse->c1->isRealOnly(true);
/* Enable alignment for SSE usage */
pulse->c1->setAligned(true);
signalVector::iterator xP = pulse->c1->begin();
switch (sps) {
case 4:
/* BT = 0.30 */
*xP++ = 0.0;
*xP++ = 8.16373112e-03;
*xP++ = 2.84385729e-02;
*xP++ = 5.64158904e-02;
*xP++ = 7.05463553e-02;
*xP++ = 5.64158904e-02;
*xP++ = 2.84385729e-02;
*xP++ = 8.16373112e-03;
}
return true;
}
static PulseSequence *generateGSMPulse(int sps, int symbolLength)
{
int len;
float arg, avg, center;
PulseSequence *pulse;
/* Store a single tap filter used for correlation sequence generation */
pulse = new PulseSequence();
pulse->empty = new signalVector(1);
pulse->empty->isRealOnly(true);
*(pulse->empty->begin()) = 1.0f;
/*
* For 4 samples-per-symbol use a precomputed single pulse Laurent
* approximation. This should yields below 2 degrees of phase error at
* the modulator output. Use the existing pulse approximation for all
* other oversampling factors.
*/
switch (sps) {
case 4:
len = 16;
break;
default:
len = sps * symbolLength;
if (len < 4)
len = 4;
}
pulse->c0_buffer = convolve_h_alloc(len);
pulse->c0 = new signalVector((complex *) pulse->c0_buffer, 0, len);
pulse->c0->isRealOnly(true);
/* Enable alingnment for SSE usage */
pulse->c0->setAligned(true);
signalVector::iterator xP = pulse->c0->begin();
if (sps == 4) {
*xP++ = 0.0;
*xP++ = 4.46348606e-03;
*xP++ = 2.84385729e-02;
*xP++ = 1.03184855e-01;
*xP++ = 2.56065552e-01;
*xP++ = 4.76375085e-01;
*xP++ = 7.05961177e-01;
*xP++ = 8.71291644e-01;
*xP++ = 9.29453645e-01;
*xP++ = 8.71291644e-01;
*xP++ = 7.05961177e-01;
*xP++ = 4.76375085e-01;
*xP++ = 2.56065552e-01;
*xP++ = 1.03184855e-01;
*xP++ = 2.84385729e-02;
*xP++ = 4.46348606e-03;
generateC1Pulse(sps, pulse);
} else {
center = (float) (len - 1.0) / 2.0;
/* GSM pulse approximation */
for (int i = 0; i < len; i++) {
arg = ((float) i - center) / (float) sps;
*xP++ = 0.96 * exp(-1.1380 * arg * arg -
0.527 * arg * arg * arg * arg);
}
avg = sqrtf(vectorNorm2(*pulse->c0) / sps);
xP = pulse->c0->begin();
for (int i = 0; i < len; i++)
*xP++ /= avg;
}
return pulse;
}
signalVector* frequencyShift(signalVector *y,
signalVector *x,
float freq,
float startPhase,
float *finalPhase)
{
if (!x) return NULL;
if (y==NULL) {
y = new signalVector(x->size());
y->isRealOnly(x->isRealOnly());
if (y==NULL) return NULL;
}
if (y->size() < x->size()) return NULL;
float phase = startPhase;
signalVector::iterator yP = y->begin();
signalVector::iterator xPEnd = x->end();
signalVector::iterator xP = x->begin();
if (x->isRealOnly()) {
while (xP < xPEnd) {
(*yP++) = expjLookup(phase)*( (xP++)->real() );
phase += freq;
}
}
else {
while (xP < xPEnd) {
(*yP++) = (*xP++)*expjLookup(phase);
phase += freq;
}
}
if (finalPhase) *finalPhase = phase;
return y;
}
signalVector* reverseConjugate(signalVector *b)
{
signalVector *tmp = new signalVector(b->size());
tmp->isRealOnly(b->isRealOnly());
signalVector::iterator bP = b->begin();
signalVector::iterator bPEnd = b->end();
signalVector::iterator tmpP = tmp->end()-1;
if (!b->isRealOnly()) {
while (bP < bPEnd) {
*tmpP-- = bP->conj();
bP++;
}
}
else {
while (bP < bPEnd) {
*tmpP-- = bP->real();
bP++;
}
}
return tmp;
}
/* soft output slicer */
bool vectorSlicer(signalVector *x)
{
signalVector::iterator xP = x->begin();
signalVector::iterator xPEnd = x->end();
while (xP < xPEnd) {
*xP = (complex) (0.5*(xP->real()+1.0F));
if (xP->real() > 1.0) *xP = 1.0;
if (xP->real() < 0.0) *xP = 0.0;
xP++;
}
return true;
}
static signalVector *rotateBurst(const BitVector &wBurst,
int guardPeriodLength, int sps)
{
int burst_len;
signalVector *pulse, rotated, *shaped;
signalVector::iterator itr;
pulse = GSMPulse1->empty;
burst_len = sps * (wBurst.size() + guardPeriodLength);
rotated = signalVector(burst_len);
itr = rotated.begin();
for (unsigned i = 0; i < wBurst.size(); i++) {
*itr = 2.0 * (wBurst[i] & 0x01) - 1.0;
itr += sps;
}
GMSKRotate(rotated, sps);
rotated.isRealOnly(false);
/* Dummy filter operation */
shaped = convolve(&rotated, pulse, NULL, START_ONLY);
if (!shaped)
return NULL;
return shaped;
}
static signalVector *modulateBurstLaurent(const BitVector &bits,
int guard_len, int sps)
{
int burst_len;
float phase;
signalVector *c0_pulse, *c1_pulse, c0_burst, c1_burst, *c0_shaped, *c1_shaped;
signalVector::iterator c0_itr, c1_itr;
/*
* Apply before and after bits to reduce phase error at burst edges.
* Make sure there is enough room in the burst to accomodate all bits.
*/
if (guard_len < 4)
guard_len = 4;
c0_pulse = GSMPulse->c0;
c1_pulse = GSMPulse->c1;
burst_len = sps * (bits.size() + guard_len);
c0_burst = signalVector(burst_len);
c0_burst.isRealOnly(true);
c0_itr = c0_burst.begin();
c1_burst = signalVector(burst_len);
c1_burst.isRealOnly(true);
c1_itr = c1_burst.begin();
/* Padded differential start bits */
*c0_itr = 2.0 * (0x00 & 0x01) - 1.0;
c0_itr += sps;
/* Main burst bits */
for (unsigned i = 0; i < bits.size(); i++) {
*c0_itr = 2.0 * (bits[i] & 0x01) - 1.0;
c0_itr += sps;
}
/* Padded differential end bits */
*c0_itr = 2.0 * (0x01 & 0x01) - 1.0;
/* Generate C0 phase coefficients */
GMSKRotate(c0_burst, sps);
c0_burst.isRealOnly(false);
c0_itr = c0_burst.begin();
c0_itr += sps * 2;
c1_itr += sps * 2;
/* Start magic */
phase = 2.0 * ((0x01 & 0x01) ^ (0x01 & 0x01)) - 1.0;
*c1_itr = *c0_itr * Complex<float>(0, phase);
c0_itr += sps;
c1_itr += sps;
/* Generate C1 phase coefficients */
for (unsigned i = 2; i < bits.size(); i++) {
phase = 2.0 * ((bits[i - 1] & 0x01) ^ (bits[i - 2] & 0x01)) - 1.0;
*c1_itr = *c0_itr * Complex<float>(0, phase);
c0_itr += sps;
c1_itr += sps;
}
/* End magic */
int i = bits.size();
phase = 2.0 * ((bits[i-1] & 0x01) ^ (bits[i-2] & 0x01)) - 1.0;
*c1_itr = *c0_itr * Complex<float>(0, phase);
/* Primary (C0) and secondary (C1) pulse shaping */
c0_shaped = convolve(&c0_burst, c0_pulse, NULL, START_ONLY);
c1_shaped = convolve(&c1_burst, c1_pulse, NULL, START_ONLY);
/* Sum shaped outputs into C0 */
c0_itr = c0_shaped->begin();
c1_itr = c1_shaped->begin();
for (unsigned i = 0; i < c0_shaped->size(); i++ )
*c0_itr++ += *c1_itr++;
delete c1_shaped;
return c0_shaped;
}
static signalVector *modulateBurstBasic(const BitVector &bits,
int guard_len, int sps)
{
int burst_len;
signalVector *pulse, burst, *shaped;
signalVector::iterator burst_itr;
if (sps == 1)
pulse = GSMPulse1->c0;
else
pulse = GSMPulse->c0;
burst_len = sps * (bits.size() + guard_len);
burst = signalVector(burst_len);
burst.isRealOnly(true);
burst_itr = burst.begin();
/* Raw bits are not differentially encoded */
for (unsigned i = 0; i < bits.size(); i++) {
*burst_itr = 2.0 * (bits[i] & 0x01) - 1.0;
burst_itr += sps;
}
GMSKRotate(burst, sps);
burst.isRealOnly(false);
/* Single Gaussian pulse approximation shaping */
shaped = convolve(&burst, pulse, NULL, START_ONLY);
return shaped;
}
/* Assume input bits are not differentially encoded */
signalVector *modulateBurst(const BitVector &wBurst, int guardPeriodLength,
int sps, bool emptyPulse)
{
if (emptyPulse)
return rotateBurst(wBurst, guardPeriodLength, sps);
else if (sps == 4)
return modulateBurstLaurent(wBurst, guardPeriodLength, sps);
else
return modulateBurstBasic(wBurst, guardPeriodLength, sps);
}
float sinc(float x)
{
if ((x >= 0.01F) || (x <= -0.01F)) return (sinLookup(x)/x);
return 1.0F;
}
bool delayVector(signalVector &wBurst, float delay)
{
int whole, h_len = 20;
float frac;
complex *data;
signalVector *h, *shift;
signalVector::iterator itr;
whole = floor(delay);
frac = delay - whole;
/* Sinc interpolated fractional shift (if allowable) */
if (fabs(frac) > 1e-2) {
data = (complex *) convolve_h_alloc(h_len);
h = new signalVector(data, 0, h_len);
h->setAligned(true);
h->isRealOnly(true);
itr = h->end();
for (int i = 0; i < h_len; i++)
*--itr = (complex) sinc(M_PI_F * (i - h_len / 2 - frac));
shift = convolve(&wBurst, h, NULL, NO_DELAY);
delete h;
free(data);
if (!shift)
return false;
wBurst.clone(*shift);
delete shift;
}
/* Integer sample shift */
if (whole < 0) {
whole = -whole;
signalVector::iterator wBurstItr = wBurst.begin();
signalVector::iterator shiftedItr = wBurst.begin() + whole;
while (shiftedItr < wBurst.end())
*wBurstItr++ = *shiftedItr++;
while (wBurstItr < wBurst.end())
*wBurstItr++ = 0.0;
} else {
signalVector::iterator wBurstItr = wBurst.end() - 1;
signalVector::iterator shiftedItr = wBurst.end() - 1 - whole;
while (shiftedItr >= wBurst.begin())
*wBurstItr-- = *shiftedItr--;
while (wBurstItr >= wBurst.begin())
*wBurstItr-- = 0.0;
}
return true;
}
signalVector *gaussianNoise(int length,
float variance,
complex mean)
{
signalVector *noise = new signalVector(length);
signalVector::iterator nPtr = noise->begin();
float stddev = sqrtf(variance);
while (nPtr < noise->end()) {
float u1 = (float) rand()/ (float) RAND_MAX;
while (u1==0.0)
u1 = (float) rand()/ (float) RAND_MAX;
float u2 = (float) rand()/ (float) RAND_MAX;
float arg = 2.0*M_PI*u2;
*nPtr = mean + stddev*complex(cos(arg),sin(arg))*sqrtf(-2.0*log(u1));
nPtr++;
}
return noise;
}
complex interpolatePoint(const signalVector &inSig,
float ix)
{
int start = (int) (floor(ix) - 10);
if (start < 0) start = 0;
int end = (int) (floor(ix) + 11);
if ((unsigned) end > inSig.size()-1) end = inSig.size()-1;
complex pVal = 0.0;
if (!inSig.isRealOnly()) {
for (int i = start; i < end; i++)
pVal += inSig[i] * sinc(M_PI_F*(i-ix));
}
else {
for (int i = start; i < end; i++)
pVal += inSig[i].real() * sinc(M_PI_F*(i-ix));
}
return pVal;
}
static complex fastPeakDetect(const signalVector &rxBurst, float *index)
{
float val, max = 0.0f;
complex amp;
int _index = -1;
for (int i = 0; i < rxBurst.size(); i++) {
val = rxBurst[i].norm2();
if (val > max) {
max = val;
_index = i;
amp = rxBurst[i];
}
}
if (index)
*index = (float) _index;
return amp;
}
complex peakDetect(const signalVector &rxBurst,
float *peakIndex,
float *avgPwr)
{
complex maxVal = 0.0;
float maxIndex = -1;
float sumPower = 0.0;
for (unsigned int i = 0; i < rxBurst.size(); i++) {
float samplePower = rxBurst[i].norm2();
if (samplePower > maxVal.real()) {
maxVal = samplePower;
maxIndex = i;
}
sumPower += samplePower;
}
// interpolate around the peak
// to save computation, we'll use early-late balancing
float earlyIndex = maxIndex-1;
float lateIndex = maxIndex+1;
float incr = 0.5;
while (incr > 1.0/1024.0) {
complex earlyP = interpolatePoint(rxBurst,earlyIndex);
complex lateP = interpolatePoint(rxBurst,lateIndex);
if (earlyP < lateP)
earlyIndex += incr;
else if (earlyP > lateP)
earlyIndex -= incr;
else break;
incr /= 2.0;
lateIndex = earlyIndex + 2.0;
}
maxIndex = earlyIndex + 1.0;
maxVal = interpolatePoint(rxBurst,maxIndex);
if (peakIndex!=NULL)
*peakIndex = maxIndex;
if (avgPwr!=NULL)
*avgPwr = (sumPower-maxVal.norm2()) / (rxBurst.size()-1);
return maxVal;
}
void scaleVector(signalVector &x,
complex scale)
{
#ifdef HAVE_NEON
int len = x.size();
scale_complex((float *) x.begin(),
(float *) x.begin(),
(float *) &scale, len);
#else
signalVector::iterator xP = x.begin();
signalVector::iterator xPEnd = x.end();
if (!x.isRealOnly()) {
while (xP < xPEnd) {
*xP = *xP * scale;
xP++;
}
}
else {
while (xP < xPEnd) {
*xP = xP->real() * scale;
xP++;
}
}
#endif
}
/** in-place conjugation */
void conjugateVector(signalVector &x)
{
if (x.isRealOnly()) return;
signalVector::iterator xP = x.begin();
signalVector::iterator xPEnd = x.end();
while (xP < xPEnd) {
*xP = xP->conj();
xP++;
}
}
// in-place addition!!
bool addVector(signalVector &x,
signalVector &y)
{
signalVector::iterator xP = x.begin();
signalVector::iterator yP = y.begin();
signalVector::iterator xPEnd = x.end();
signalVector::iterator yPEnd = y.end();
while ((xP < xPEnd) && (yP < yPEnd)) {
*xP = *xP + *yP;
xP++; yP++;
}
return true;
}
// in-place multiplication!!
bool multVector(signalVector &x,
signalVector &y)
{
signalVector::iterator xP = x.begin();
signalVector::iterator yP = y.begin();
signalVector::iterator xPEnd = x.end();
signalVector::iterator yPEnd = y.end();
while ((xP < xPEnd) && (yP < yPEnd)) {
*xP = (*xP) * (*yP);
xP++; yP++;
}
return true;
}
void offsetVector(signalVector &x,
complex offset)
{
signalVector::iterator xP = x.begin();
signalVector::iterator xPEnd = x.end();
if (!x.isRealOnly()) {
while (xP < xPEnd) {
*xP += offset;
xP++;
}
}
else {
while (xP < xPEnd) {
*xP = xP->real() + offset;
xP++;
}
}
}
bool generateMidamble(int sps, int tsc)
{
bool status = true;
float toa;
complex *data = NULL;
signalVector *autocorr = NULL, *midamble = NULL;
signalVector *midMidamble = NULL, *_midMidamble = NULL;
if ((tsc < 0) || (tsc > 7))
return false;
delete gMidambles[tsc];
/* Use middle 16 bits of each TSC. Correlation sequence is not pulse shaped */
midMidamble = modulateBurst(gTrainingSequence[tsc].segment(5,16), 0, sps, true);
if (!midMidamble)
return false;
/* Simulated receive sequence is pulse shaped */
midamble = modulateBurst(gTrainingSequence[tsc], 0, sps, false);
if (!midamble) {
status = false;
goto release;
}
// NOTE: Because ideal TSC 16-bit midamble is 66 symbols into burst,
// the ideal TSC has an + 180 degree phase shift,
// due to the pi/2 frequency shift, that
// needs to be accounted for.
// 26-midamble is 61 symbols into burst, has +90 degree phase shift.
scaleVector(*midMidamble, complex(-1.0, 0.0));
scaleVector(*midamble, complex(0.0, 1.0));
conjugateVector(*midMidamble);
/* For SSE alignment, reallocate the midamble sequence on 16-byte boundary */
data = (complex *) convolve_h_alloc(midMidamble->size());
_midMidamble = new signalVector(data, 0, midMidamble->size());
_midMidamble->setAligned(true);
memcpy(_midMidamble->begin(), midMidamble->begin(),
midMidamble->size() * sizeof(complex));
autocorr = convolve(midamble, _midMidamble, NULL, NO_DELAY);
if (!autocorr) {
status = false;
goto release;
}
gMidambles[tsc] = new CorrelationSequence;
gMidambles[tsc]->buffer = data;
gMidambles[tsc]->sequence = _midMidamble;
gMidambles[tsc]->gain = peakDetect(*autocorr, &toa, NULL);
/* For 1 sps only
* (Half of correlation length - 1) + midpoint of pulse shape + remainder
* 13.5 = (16 / 2 - 1) + 1.5 + (26 - 10) / 2
*/
if (sps == 1)
gMidambles[tsc]->toa = toa - 13.5;
else
gMidambles[tsc]->toa = 0;
release:
delete autocorr;
delete midamble;
delete midMidamble;
if (!status) {
delete _midMidamble;
free(data);
gMidambles[tsc] = NULL;
}
return status;
}
bool generateRACHSequence(int sps)
{
bool status = true;
float toa;
complex *data = NULL;
signalVector *autocorr = NULL;
signalVector *seq0 = NULL, *seq1 = NULL, *_seq1 = NULL;
delete gRACHSequence;
seq0 = modulateBurst(gRACHSynchSequence, 0, sps, false);
if (!seq0)
return false;
seq1 = modulateBurst(gRACHSynchSequence.segment(0, 40), 0, sps, true);
if (!seq1) {
status = false;
goto release;
}
conjugateVector(*seq1);
/* For SSE alignment, reallocate the midamble sequence on 16-byte boundary */
data = (complex *) convolve_h_alloc(seq1->size());
_seq1 = new signalVector(data, 0, seq1->size());
_seq1->setAligned(true);
memcpy(_seq1->begin(), seq1->begin(), seq1->size() * sizeof(complex));
autocorr = convolve(seq0, _seq1, autocorr, NO_DELAY);
if (!autocorr) {
status = false;
goto release;
}
gRACHSequence = new CorrelationSequence;
gRACHSequence->sequence = _seq1;
gRACHSequence->buffer = data;
gRACHSequence->gain = peakDetect(*autocorr, &toa, NULL);
/* For 1 sps only
* (Half of correlation length - 1) + midpoint of pulse shaping filer
* 20.5 = (40 / 2 - 1) + 1.5
*/
if (sps == 1)
gRACHSequence->toa = toa - 20.5;
else
gRACHSequence->toa = 0.0;
release:
delete autocorr;
delete seq0;
delete seq1;
if (!status) {
delete _seq1;
free(data);
gRACHSequence = NULL;
}
return status;
}
static float computePeakRatio(signalVector *corr,
int sps, float toa, complex amp)
{
int num = 0;
complex *peak;
float rms, avg = 0.0;
peak = corr->begin() + (int) rint(toa);
/* Check for bogus results */
if ((toa < 0.0) || (toa > corr->size()))
return 0.0;
for (int i = 2 * sps; i <= 5 * sps; i++) {
if (peak - i >= corr->begin()) {
avg += (peak - i)->norm2();
num++;
}
if (peak + i < corr->end()) {
avg += (peak + i)->norm2();
num++;
}
}
if (num < 2)
return 0.0;
rms = sqrtf(avg / (float) num) + 0.00001;
return (amp.abs()) / rms;
}
bool energyDetect(signalVector &rxBurst,
unsigned windowLength,
float detectThreshold,
float *avgPwr)
{
signalVector::const_iterator windowItr = rxBurst.begin(); //+rxBurst.size()/2 - 5*windowLength/2;
float energy = 0.0;
if (windowLength < 0) windowLength = 20;
if (windowLength > rxBurst.size()) windowLength = rxBurst.size();
for (unsigned i = 0; i < windowLength; i++) {
energy += windowItr->norm2();
windowItr+=4;
}
if (avgPwr) *avgPwr = energy/windowLength;
return (energy/windowLength > detectThreshold*detectThreshold);
}
/*
* Detect a burst based on correlation and peak-to-average ratio
*
* For one sampler-per-symbol, perform fast peak detection (no interpolation)
* for initial gating. We do this because energy detection should be disabled.
* For higher oversampling values, we assume the energy detector is in place
* and we run full interpolating peak detection.
*/
static int detectBurst(signalVector &burst,
signalVector &corr, CorrelationSequence *sync,
float thresh, int sps, complex *amp, float *toa,
int start, int len)
{
/* Correlate */
if (!convolve(&burst, sync->sequence, &corr,
CUSTOM, start, len, sps, 0)) {
return -1;
}
/* Peak detection - place restrictions at correlation edges */
*amp = fastPeakDetect(corr, toa);
if ((*toa < 3 * sps) || (*toa > len - 3 * sps))
return 0;
/* Peak -to-average ratio */
if (computePeakRatio(&corr, sps, *toa, *amp) < thresh)
return 0;
/* Compute peak-to-average ratio. Reject if we don't have enough values */
*amp = peakDetect(corr, toa, NULL);
/* Normalize our channel gain */
*amp = *amp / sync->gain;
/* Compenate for residual rotation with dual Laurent pulse */
if (sps == 4)
*amp = *amp * complex(0.0, 1.0);
/* Compensate for residuate time lag */
*toa = *toa - sync->toa;
return 1;
}
/*
* RACH burst detection
*
* Correlation window parameters:
* target: Tail bits + RACH length (reduced from 41 to a multiple of 4)
* head: Search 4 symbols before target
* tail: Search 10 symbols after target
*/
int detectRACHBurst(signalVector &rxBurst,
float thresh,
int sps,
complex *amp,
float *toa)
{
int rc, start, target, head, tail, len;
float _toa;
complex _amp;
signalVector corr;
CorrelationSequence *sync;
if ((sps != 1) && (sps != 4))
return -1;
target = 8 + 40;
head = 4;
tail = 10;
start = (target - head) * sps - 1;
len = (head + tail) * sps;
sync = gRACHSequence;
corr = signalVector(len);
rc = detectBurst(rxBurst, corr, sync,
thresh, sps, &_amp, &_toa, start, len);
if (rc < 0) {
return -1;
} else if (!rc) {
if (amp)
*amp = 0.0f;
if (toa)
*toa = 0.0f;
return 0;
}
/* Subtract forward search bits from delay */
if (toa)
*toa = _toa - head * sps;
if (amp)
*amp = _amp;
return 1;
}
/*
* Normal burst detection
*
* Correlation window parameters:
* target: Tail + data + mid-midamble + 1/2 remaining midamblebits
* head: Search 4 symbols before target
* tail: Search 4 symbols + maximum expected delay
*/
int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
int sps, complex *amp, float *toa, unsigned max_toa,
bool chan_req, signalVector **chan, float *chan_offset)
{
int rc, start, target, head, tail, len;
complex _amp;
float _toa;
signalVector corr;
CorrelationSequence *sync;
if ((tsc < 0) || (tsc > 7) || ((sps != 1) && (sps != 4)))
return -1;
target = 3 + 58 + 16 + 5;
head = 4;
tail = 4 + max_toa;
start = (target - head) * sps - 1;
len = (head + tail) * sps;
sync = gMidambles[tsc];
corr = signalVector(len);
rc = detectBurst(rxBurst, corr, sync,
thresh, sps, &_amp, &_toa, start, len);
if (rc < 0) {
return -1;
} else if (!rc) {
if (amp)
*amp = 0.0f;
if (toa)
*toa = 0.0f;
return 0;
}
/* Subtract forward search bits from delay */
_toa -= head * sps;
if (toa)
*toa = _toa;
if (amp)
*amp = _amp;
/* Equalization not currently supported */
if (chan_req) {
*chan = new signalVector(6 * sps);
if (chan_offset)
*chan_offset = 0.0;
}
return 1;
}
signalVector *decimateVector(signalVector &wVector,
int decimationFactor)
{
if (decimationFactor <= 1) return NULL;
signalVector *decVector = new signalVector(wVector.size()/decimationFactor);
decVector->isRealOnly(wVector.isRealOnly());
signalVector::iterator vecItr = decVector->begin();
for (unsigned int i = 0; i < wVector.size();i+=decimationFactor)
*vecItr++ = wVector[i];
return decVector;
}
SoftVector *demodulateBurst(signalVector &rxBurst, int sps,
complex channel, float TOA)
{
scaleVector(rxBurst,((complex) 1.0)/channel);
delayVector(rxBurst,-TOA);
signalVector *shapedBurst = &rxBurst;
// shift up by a quarter of a frequency
// ignore starting phase, since spec allows for discontinuous phase
GMSKReverseRotate(*shapedBurst, sps);
// run through slicer
if (sps > 1) {
signalVector *decShapedBurst = decimateVector(*shapedBurst, sps);
shapedBurst = decShapedBurst;
}
vectorSlicer(shapedBurst);
SoftVector *burstBits = new SoftVector(shapedBurst->size());
SoftVector::iterator burstItr = burstBits->begin();
signalVector::iterator shapedItr = shapedBurst->begin();
for (; shapedItr < shapedBurst->end(); shapedItr++)
*burstItr++ = shapedItr->real();
if (sps > 1)
delete shapedBurst;
return burstBits;
}
// Assumes symbol-spaced sampling!!!
// Based upon paper by Al-Dhahir and Cioffi
bool designDFE(signalVector &channelResponse,
float SNRestimate,
int Nf,
signalVector **feedForwardFilter,
signalVector **feedbackFilter)
{
signalVector G0(Nf);
signalVector G1(Nf);
signalVector::iterator G0ptr = G0.begin();
signalVector::iterator G1ptr = G1.begin();
signalVector::iterator chanPtr = channelResponse.begin();
int nu = channelResponse.size()-1;
*G0ptr = 1.0/sqrtf(SNRestimate);
for(int j = 0; j <= nu; j++) {
*G1ptr = chanPtr->conj();
G1ptr++; chanPtr++;
}
signalVector *L[Nf];
signalVector::iterator Lptr;
float d;
for(int i = 0; i < Nf; i++) {
d = G0.begin()->norm2() + G1.begin()->norm2();
L[i] = new signalVector(Nf+nu);
Lptr = L[i]->begin()+i;
G0ptr = G0.begin(); G1ptr = G1.begin();
while ((G0ptr < G0.end()) && (Lptr < L[i]->end())) {
*Lptr = (*G0ptr*(G0.begin()->conj()) + *G1ptr*(G1.begin()->conj()) )/d;
Lptr++;
G0ptr++;
G1ptr++;
}
complex k = (*G1.begin())/(*G0.begin());
if (i != Nf-1) {
signalVector G0new = G1;
scaleVector(G0new,k.conj());
addVector(G0new,G0);
signalVector G1new = G0;
scaleVector(G1new,k*(-1.0));
addVector(G1new,G1);
delayVector(G1new,-1.0);
scaleVector(G0new,1.0/sqrtf(1.0+k.norm2()));
scaleVector(G1new,1.0/sqrtf(1.0+k.norm2()));
G0 = G0new;
G1 = G1new;
}
}
*feedbackFilter = new signalVector(nu);
L[Nf-1]->segmentCopyTo(**feedbackFilter,Nf,nu);
scaleVector(**feedbackFilter,(complex) -1.0);
conjugateVector(**feedbackFilter);
signalVector v(Nf);
signalVector::iterator vStart = v.begin();
signalVector::iterator vPtr;
*(vStart+Nf-1) = (complex) 1.0;
for(int k = Nf-2; k >= 0; k--) {
Lptr = L[k]->begin()+k+1;
vPtr = vStart + k+1;
complex v_k = 0.0;
for (int j = k+1; j < Nf; j++) {
v_k -= (*vPtr)*(*Lptr);
vPtr++; Lptr++;
}
*(vStart + k) = v_k;
}
*feedForwardFilter = new signalVector(Nf);
signalVector::iterator w = (*feedForwardFilter)->end();
for (int i = 0; i < Nf; i++) {
delete L[i];
complex w_i = 0.0;
int endPt = ( nu < (Nf-1-i) ) ? nu : (Nf-1-i);
vPtr = vStart+i;
chanPtr = channelResponse.begin();
for (int k = 0; k < endPt+1; k++) {
w_i += (*vPtr)*(chanPtr->conj());
vPtr++; chanPtr++;
}
*--w = w_i/d;
}
return true;
}
// Assumes symbol-rate sampling!!!!
SoftVector *equalizeBurst(signalVector &rxBurst,
float TOA,
int sps,
signalVector &w, // feedforward filter
signalVector &b) // feedback filter
{
signalVector *postForwardFull;
if (!delayVector(rxBurst, -TOA))
return NULL;
postForwardFull = convolve(&rxBurst, &w, NULL,
CUSTOM, 0, rxBurst.size() + w.size() - 1);
if (!postForwardFull)
return NULL;
signalVector* postForward = new signalVector(rxBurst.size());
postForwardFull->segmentCopyTo(*postForward,w.size()-1,rxBurst.size());
delete postForwardFull;
signalVector::iterator dPtr = postForward->begin();
signalVector::iterator dBackPtr;
signalVector::iterator rotPtr = GMSKRotationN->begin();
signalVector::iterator revRotPtr = GMSKReverseRotationN->begin();
signalVector *DFEoutput = new signalVector(postForward->size());
signalVector::iterator DFEItr = DFEoutput->begin();
// NOTE: can insert the midamble and/or use midamble to estimate BER
for (; dPtr < postForward->end(); dPtr++) {
dBackPtr = dPtr-1;
signalVector::iterator bPtr = b.begin();
while ( (bPtr < b.end()) && (dBackPtr >= postForward->begin()) ) {
*dPtr = *dPtr + (*bPtr)*(*dBackPtr);
bPtr++;
dBackPtr--;
}
*dPtr = *dPtr * (*revRotPtr);
*DFEItr = *dPtr;
// make decision on symbol
*dPtr = (dPtr->real() > 0.0) ? 1.0 : -1.0;
//*DFEItr = *dPtr;
*dPtr = *dPtr * (*rotPtr);
DFEItr++;
rotPtr++;
revRotPtr++;
}
vectorSlicer(DFEoutput);
SoftVector *burstBits = new SoftVector(postForward->size());
SoftVector::iterator burstItr = burstBits->begin();
DFEItr = DFEoutput->begin();
for (; DFEItr < DFEoutput->end(); DFEItr++)
*burstItr++ = DFEItr->real();
delete postForward;
delete DFEoutput;
return burstBits;
}
bool sigProcLibSetup(int sps)
{
if ((sps != 1) && (sps != 4))
return false;
initTrigTables();
initGMSKRotationTables(sps);
GSMPulse1 = generateGSMPulse(1, 2);
if (sps > 1)
GSMPulse = generateGSMPulse(sps, 2);
if (!generateRACHSequence(1)) {
sigProcLibDestroy();
return false;
}
return true;
}
Reference in New Issue View Git Blame Copy Permalink