| /* |
| * 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/>. |
| |
| */ |
| |
| #include "sigProcLib.h" |
| #include "GSMCommon.h" |
| #include "sendLPF_961.h" |
| #include "rcvLPF_651.h" |
| |
| extern "C" { |
| #include "convolve.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; |
| |
| /** Static vectors that contain a precomputed +/- f_b/4 sinusoid */ |
| signalVector *GMSKRotation = NULL; |
| signalVector *GMSKReverseRotation = 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; |
| |
| void sigProcLibDestroy() |
| { |
| for (int i = 0; i < 8; i++) { |
| delete gMidambles[i]; |
| gMidambles[i] = NULL; |
| } |
| |
| delete GMSKRotation; |
| delete GMSKReverseRotation; |
| delete gRACHSequence; |
| delete GSMPulse; |
| |
| GMSKRotation = NULL; |
| GMSKReverseRotation = NULL; |
| gRACHSequence = NULL; |
| GSMPulse = 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) |
| { |
| GMSKRotation = new signalVector(157 * sps); |
| GMSKReverseRotation = new signalVector(157 * sps); |
| signalVector::iterator rotPtr = GMSKRotation->begin(); |
| signalVector::iterator revPtr = GMSKReverseRotation->begin(); |
| float phase = 0.0; |
| while (rotPtr != GMSKRotation->end()) { |
| *rotPtr++ = expjLookup(phase); |
| *revPtr++ = expjLookup(-phase); |
| phase += M_PI_F / 2.0F / (float) sps; |
| } |
| } |
| |
| bool sigProcLibSetup(int sps) |
| { |
| if (sps != 4) |
| return false; |
| |
| initTrigTables(); |
| initGMSKRotationTables(sps); |
| generateGSMPulse(sps, 2); |
| |
| if (!generateRACHSequence(sps)) { |
| sigProcLibDestroy(); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void GMSKRotate(signalVector &x) { |
| signalVector::iterator xPtr = x.begin(); |
| signalVector::iterator rotPtr = GMSKRotation->begin(); |
| if (x.isRealOnly()) { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (xPtr->real()); |
| xPtr++; |
| } |
| } |
| else { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (*xPtr); |
| xPtr++; |
| } |
| } |
| } |
| |
| void GMSKReverseRotate(signalVector &x) { |
| signalVector::iterator xPtr= x.begin(); |
| signalVector::iterator rotPtr = GMSKReverseRotation->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; |
| } |
| |
| bool generateC1Pulse(int sps) |
| { |
| int len; |
| |
| switch (sps) { |
| case 4: |
| len = 8; |
| break; |
| default: |
| return false; |
| } |
| |
| GSMPulse->c1_buffer = convolve_h_alloc(len); |
| GSMPulse->c1 = new signalVector((complex *) |
| GSMPulse->c1_buffer, 0, len); |
| GSMPulse->c1->isRealOnly(true); |
| |
| /* Enable alignment for SSE usage */ |
| GSMPulse->c1->setAligned(true); |
| |
| signalVector::iterator xP = GSMPulse->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; |
| } |
| |
| void generateGSMPulse(int sps, int symbolLength) |
| { |
| int len; |
| float arg, avg, center; |
| |
| delete GSMPulse; |
| |
| /* Store a single tap filter used for correlation sequence generation */ |
| GSMPulse = new PulseSequence(); |
| GSMPulse->empty = new signalVector(1); |
| GSMPulse->empty->isRealOnly(true); |
| *(GSMPulse->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; |
| } |
| |
| GSMPulse->c0_buffer = convolve_h_alloc(len); |
| GSMPulse->c0 = new signalVector((complex *) |
| GSMPulse->c0_buffer, 0, len); |
| GSMPulse->c0->isRealOnly(true); |
| |
| /* Enable alingnment for SSE usage */ |
| GSMPulse->c0->setAligned(true); |
| |
| signalVector::iterator xP = GSMPulse->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); |
| } 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(*GSMPulse->c0) / sps); |
| xP = GSMPulse->c0->begin(); |
| for (int i = 0; i < len; i++) |
| *xP++ /= avg; |
| } |
| } |
| |
| 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 = GSMPulse->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); |
| rotated.isRealOnly(false); |
| |
| /* Dummy filter operation */ |
| shaped = convolve(&rotated, pulse, NULL, START_ONLY); |
| if (!shaped) |
| return NULL; |
| |
| return shaped; |
| } |
| |
| /* Assume input bits are not differentially encoded */ |
| signalVector *modulateBurst(const BitVector &wBurst, int guardPeriodLength, |
| int sps, bool emptyPulse) |
| { |
| int burst_len; |
| float phase; |
| signalVector *c0_pulse, *c1_pulse, c0_burst, c1_burst, *c0_shaped, *c1_shaped; |
| signalVector::iterator c0_itr, c1_itr; |
| |
| if (emptyPulse) |
| return rotateBurst(wBurst, guardPeriodLength, sps); |
| |
| /* |
| * Apply before and after bits to reduce phase error at burst edges. |
| * Make sure there is enough room in the burst to accodmodate the bits. |
| */ |
| if (guardPeriodLength < 4) |
| guardPeriodLength = 4; |
| |
| c0_pulse = GSMPulse->c0; |
| c1_pulse = GSMPulse->c1; |
| |
| burst_len = sps * (wBurst.size() + guardPeriodLength); |
| |
| 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 < wBurst.size(); i++) { |
| *c0_itr = 2.0 * (wBurst[i] & 0x01) - 1.0; |
| c0_itr += sps; |
| } |
| |
| /* Padded differential end bits */ |
| *c0_itr = 2.0 * (0x01 & 0x01) - 1.0; |
| |
| GMSKRotate(c0_burst); |
| 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 < wBurst.size(); i++) { |
| phase = 2.0 * ((wBurst[i - 1] & 0x01) ^ (wBurst[i - 2] & 0x01)) - 1.0; |
| *c1_itr = *c0_itr * Complex<float>(0, phase); |
| |
| c0_itr += sps; |
| c1_itr += sps; |
| } |
| |
| /* End magic */ |
| int i = wBurst.size(); |
| phase = 2.0 * ((wBurst[i-1] & 0x01) ^ (wBurst[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 pulse shaped outputs */ |
| 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; |
| } |
| |
| 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 intOffset = (int) floor(delay); |
| float fracOffset = delay - intOffset; |
| |
| // do fractional shift first, only do it for reasonable offsets |
| if (fabs(fracOffset) > 1e-2) { |
| // create sinc function |
| signalVector sincVector(21); |
| sincVector.isRealOnly(true); |
| signalVector::iterator sincBurstItr = sincVector.end(); |
| for (int i = 0; i < 21; i++) |
| *--sincBurstItr = (complex) sinc(M_PI_F*(i-10-fracOffset)); |
| |
| signalVector shiftedBurst(wBurst.size()); |
| if (!convolve(&wBurst, &sincVector, &shiftedBurst, NO_DELAY)) |
| return false; |
| wBurst.clone(shiftedBurst); |
| } |
| |
| if (intOffset < 0) { |
| intOffset = -intOffset; |
| signalVector::iterator wBurstItr = wBurst.begin(); |
| signalVector::iterator shiftedItr = wBurst.begin()+intOffset; |
| 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-intOffset; |
| while (shiftedItr >= wBurst.begin()) |
| *wBurstItr-- = *shiftedItr--; |
| while (wBurstItr >= wBurst.begin()) |
| *wBurstItr-- = 0.0; |
| } |
| } |
| |
| 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) |
| { |
| 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++; |
| } |
| } |
| } |
| |
| /** 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; |
| 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,&gMidambles[tsc]->TOA, NULL); |
| |
| 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; |
| 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,&gRACHSequence->TOA, NULL); |
| |
| 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. Perform |
| * fast peak detection (no interpolation) for initial gating. Interpolate |
| * the sub-sample peak after we have detected the burst. |
| */ |
| 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)) { |
| #ifndef TRX_LOAD_TESTING |
| return -1; |
| #endif |
| } |
| |
| /* Peak detection - place restrictions at correlation edges */ |
| *amp = fastPeakDetect(corr, toa); |
| |
| #ifndef TRX_LOAD_TESTING |
| if ((*toa < 3 * sps) || (*toa > len - 3 * sps)) |
| return 0; |
| #endif |
| |
| /* Peak -to-average ratio */ |
| if (computePeakRatio(&corr, sps, *toa, *amp) < thresh) { |
| #ifndef TRX_LOAD_TESTING |
| return 0; |
| #endif |
| } |
| |
| /* Run the full peak detection when we have a burst */ |
| *amp = peakDetect(corr, toa, NULL); |
| |
| /* Normalize our channel gain */ |
| *amp = *amp / sync->gain; |
| |
| 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 8 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 != 2) && (sps != 4)) |
| return -1; |
| |
| target = 8 + 40; |
| head = 4; |
| tail = 8; |
| |
| 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; |
| |
| /* Compensate for unknown rotation */ |
| if (amp) |
| *amp = _amp * complex(0.0, 1.0); |
| |
| 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 6 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, *_chan; |
| CorrelationSequence *sync; |
| |
| if ((tsc < 0) || (tsc > 7) || ((sps != 1) && (sps != 2) && (sps != 4))) |
| return -1; |
| |
| target = 3 + 58 + 16 + 5; |
| head = 4; |
| tail = 6 + 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; |
| |
| /* Compensate for unknown rotation */ |
| if (amp) |
| *amp = _amp * complex(0, 1.0); |
| |
| /* 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); |
| |
| // 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; |
| |
| } |
| |
| |
| // 1.0 is sampling frequency |
| // must satisfy cutoffFreq > 1/filterLen |
| signalVector *createLPF(float cutoffFreq, |
| int filterLen, |
| float gainDC) |
| { |
| #if 0 |
| signalVector *LPF = new signalVector(filterLen-1); |
| LPF->isRealOnly(true); |
| LPF->setSymmetry(ABSSYM); |
| signalVector::iterator itr = LPF->begin(); |
| double sum = 0.0; |
| for (int i = 1; i < filterLen; i++) { |
| float ys = sinc(M_2PI_F*cutoffFreq*((float)i-(float)(filterLen)/2.0F)); |
| float yg = 4.0F * cutoffFreq; |
| // Blackman -- less brickwall (sloping transition) but larger stopband attenuation |
| float yw = 0.42 - 0.5*cos(((float)i)*M_2PI_F/(float)(filterLen)) + 0.08*cos(((float)i)*2*M_2PI_F/(float)(filterLen)); |
| // Hamming -- more brickwall with smaller stopband attenuation |
| //float yw = 0.53836F - 0.46164F * cos(((float)i)*M_2PI_F/(float)(filterLen+1)); |
| *itr++ = (complex) ys*yg*yw; |
| sum += ys*yg*yw; |
| } |
| #else |
| double sum = 0.0; |
| signalVector *LPF; |
| signalVector::iterator itr; |
| if (filterLen == 651) { // receive LPF |
| LPF = new signalVector(651); |
| LPF->isRealOnly(true); |
| itr = LPF->begin(); |
| for (int i = 0; i < filterLen; i++) { |
| *itr++ = complex(rcvLPF_651[i],0.0); |
| sum += rcvLPF_651[i]; |
| } |
| } |
| else { |
| LPF = new signalVector(961); |
| LPF->isRealOnly(true); |
| itr = LPF->begin(); |
| for (int i = 0; i < filterLen; i++) { |
| *itr++ = complex(sendLPF_961[i],0.0); |
| sum += sendLPF_961[i]; |
| } |
| } |
| #endif |
| |
| float normFactor = gainDC/sum; //sqrtf(gainDC/vectorNorm2(*LPF)); |
| // normalize power |
| itr = LPF->begin(); |
| for (int i = 0; i < filterLen; i++) { |
| *itr = *itr*normFactor; |
| itr++; |
| } |
| return LPF; |
| |
| } |
| |
| |
| |
| #define POLYPHASESPAN 10 |
| |
| // assumes filter group delay is 0.5*(length of filter) |
| signalVector *polyphaseResampleVector(signalVector &wVector, |
| int P, int Q, |
| signalVector *LPF) |
| |
| { |
| |
| bool deleteLPF = false; |
| |
| if (LPF==NULL) { |
| float cutoffFreq = (P < Q) ? (1.0/(float) Q) : (1.0/(float) P); |
| LPF = createLPF(cutoffFreq/3.0,100*POLYPHASESPAN+1,Q); |
| deleteLPF = true; |
| } |
| |
| signalVector *resampledVector = new signalVector((int) ceil(wVector.size()*(float) P / (float) Q)); |
| resampledVector->fill(0); |
| resampledVector->isRealOnly(wVector.isRealOnly()); |
| signalVector::iterator newItr = resampledVector->begin(); |
| |
| //FIXME: need to update for real-only vectors |
| int outputIx = (LPF->size()+1)/2/Q; //((P > Q) ? P : Q); |
| while (newItr < resampledVector->end()) { |
| int outputBranch = (outputIx*Q) % P; |
| int inputOffset = (outputIx*Q - outputBranch)/P; |
| signalVector::const_iterator inputItr = wVector.begin() + inputOffset; |
| signalVector::const_iterator filtItr = LPF->begin() + outputBranch; |
| while (inputItr >= wVector.end()) { |
| inputItr--; |
| filtItr+=P; |
| } |
| complex sum = 0.0; |
| if ((LPF->getSymmetry()!=ABSSYM) || (P>1)) { |
| if (!LPF->isRealOnly()) { |
| while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| sum += (*inputItr)*(*filtItr); |
| inputItr--; |
| filtItr += P; |
| } |
| } |
| else { |
| while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| sum += (*inputItr)*(filtItr->real()); |
| inputItr--; |
| filtItr += P; |
| } |
| } |
| } |
| else { |
| signalVector::const_iterator revInputItr = inputItr- LPF->size() + 1; |
| signalVector::const_iterator filtMidpoint = LPF->begin()+(LPF->size()-1)/2; |
| if (!LPF->isRealOnly()) { |
| while (filtItr <= filtMidpoint) { |
| if (inputItr < revInputItr) break; |
| if (inputItr == revInputItr) |
| sum += (*inputItr)*(*filtItr); |
| else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| sum += (*inputItr + *revInputItr)*(*filtItr); |
| else if ( inputItr < wVector.end() ) |
| sum += (*inputItr)*(*filtItr); |
| else if ( revInputItr >= wVector.begin() ) |
| sum += (*revInputItr)*(*filtItr); |
| inputItr--; |
| revInputItr++; |
| filtItr++; |
| } |
| } |
| else { |
| while (filtItr <= filtMidpoint) { |
| if (inputItr < revInputItr) break; |
| if (inputItr == revInputItr) |
| sum += (*inputItr)*(filtItr->real()); |
| else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| sum += (*inputItr + *revInputItr)*(filtItr->real()); |
| else if ( inputItr < wVector.end() ) |
| sum += (*inputItr)*(filtItr->real()); |
| else if ( revInputItr >= wVector.begin() ) |
| sum += (*revInputItr)*(filtItr->real()); |
| inputItr--; |
| revInputItr++; |
| filtItr++; |
| } |
| } |
| } |
| *newItr = sum; |
| newItr++; |
| outputIx++; |
| } |
| |
| if (deleteLPF) delete LPF; |
| |
| return resampledVector; |
| } |
| |
| |
| signalVector *resampleVector(signalVector &wVector, |
| float expFactor, |
| complex endPoint) |
| |
| { |
| |
| if (expFactor < 1.0) return NULL; |
| |
| signalVector *retVec = new signalVector((int) ceil(wVector.size()*expFactor)); |
| |
| float t = 0.0; |
| |
| signalVector::iterator retItr = retVec->begin(); |
| while (retItr < retVec->end()) { |
| unsigned tLow = (unsigned int) floor(t); |
| unsigned tHigh = tLow + 1; |
| if (tLow > wVector.size()-1) break; |
| if (tHigh > wVector.size()) break; |
| complex lowPoint = wVector[tLow]; |
| complex highPoint = (tHigh == wVector.size()) ? endPoint : wVector[tHigh]; |
| complex a = (tHigh-t); |
| complex b = (t-tLow); |
| *retItr = (a*lowPoint + b*highPoint); |
| t += 1.0/expFactor; |
| } |
| |
| return retVec; |
| |
| } |
| |
| |
| // 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 = GMSKRotation->begin(); |
| signalVector::iterator revRotPtr = GMSKReverseRotation->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; |
| } |