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Common Phase error estimation and compensation in uplink.

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FEATURE STATEMENT:
- Introduce linear phase error noise model in Uplink at UE
- Perform common phase error (CPE) estimation and compensation at gNB

SOLUTION:
- A linear phase shift model is introduced in simulation.
- PTRS symbols are used to perform estimation of CPE from DMRS compensated signal
- The estimated values are interpolated in time domain and signal is compensated for the CPE.
- PTRS processing is done in Frequency Domain for each symbol in a slot and
  LLR's are calculated for each symbol accordingly.

IMPLEMENTATION:
* sim.h/channle_sim.c
- Linear Phase Noise Generation model definition.
* nr_ul_channel_estimation.c/nr_ul_estimation.h
- CPE estimation from PTRS and DMRS compensated signal.
* nr_dmrs_rx.c/nr_refsig.h
- Regenerate PTRS symbols at gNB.
* nr_ulsch_demodulation.c
- Removed old PTRS processing code and move to a common PTRS processing function
* defs_gNB.h/init.c
- New PTRS variables definition and initialization
* nr_ulsch_ue.c
- Corrected PTRS parameter to get new PTRS symbols for each OFDM symbol

TESTING
* ulsim.c
- Added Phase noise, Enable PTRS signal and verified the output.

VERIFICATION
- The LLR are rotated back with estimated CPE and no error is observed in scrambling/decoding
This commit is contained in:
Parminder Singh
2020-08-27 11:55:06 +02:00
parent f4631f2186
commit b288eafd1e
14 changed files with 666 additions and 106 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair1/SIMULATION/NR_PHY/ulsim.c
+28 -18
View File
@@ -447,7 +447,7 @@ int main(int argc, char **argv)
0);
fix_scc(scc,ssb_bitmap);
xer_fprint(stdout, &asn_DEF_NR_CellGroupConfig, (const void*)secondaryCellGroup);
// xer_fprint(stdout, &asn_DEF_NR_CellGroupConfig, (const void*)secondaryCellGroup);
AssertFatal((gNB->if_inst = NR_IF_Module_init(0))!=NULL,"Cannot register interface");
@@ -562,14 +562,13 @@ int main(int argc, char **argv)
uint8_t ptrs_time_density = get_L_ptrs(ptrs_mcs1, ptrs_mcs2, ptrs_mcs3, Imcs, mcs_table);
uint8_t ptrs_freq_density = get_K_ptrs(n_rb0, n_rb1, nb_rb);
int ptrs_symbols = 0; // to calculate total PTRS RE's in a slot
double ts = 1.0/(frame_parms->subcarrier_spacing * frame_parms->ofdm_symbol_size);
number_dmrs_symbols = get_dmrs_symbols_in_slot(l_prime_mask, nb_symb_sch);
if(1<<ptrs_time_density >= nb_symb_sch)
pdu_bit_map &= ~PUSCH_PDU_BITMAP_PUSCH_PTRS; // disable PUSCH PTRS
for (i = 0; i < nb_symb_sch; i++) {
number_dmrs_symbols += (l_prime_mask >> i) & 0x01;
}
mod_order = nr_get_Qm_ul(Imcs, 0);
code_rate = nr_get_code_rate_ul(Imcs, 0);
@@ -586,6 +585,7 @@ int main(int argc, char **argv)
reset_meas(&gNB->ulsch_ldpc_decoding_stats);
reset_meas(&gNB->ulsch_unscrambling_stats);
reset_meas(&gNB->ulsch_channel_estimation_stats);
reset_meas(&gNB->ulsch_ptrs_processing_stats);
reset_meas(&gNB->ulsch_llr_stats);
reset_meas(&gNB->ulsch_channel_compensation_stats);
reset_meas(&gNB->ulsch_rbs_extraction_stats);
@@ -765,19 +765,24 @@ int main(int argc, char **argv)
int error_flag;
for (trial = 0; trial < n_trials; trial++) {
error_flag = 0;
//----------------------------------------------------------
//------------------------ add noise -----------------------
//----------------------------------------------------------
if (input_fd == NULL ) {
for (i=0; i<slot_length; i++) {
for (ap=0; ap<frame_parms->nb_antennas_rx; ap++) {
((int16_t*) &gNB->common_vars.rxdata[ap][slot_offset])[(2*i) + (delay*2)] = (int16_t)((double)(((int16_t *)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)])/sqrt(scale) + (sqrt(sigma/2)*gaussdouble(0.0,1.0))); // convert to fixed point
((int16_t*) &gNB->common_vars.rxdata[ap][slot_offset])[(2*i)+1 + (delay*2)] = (int16_t)((double)(((int16_t *)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)+1])/sqrt(scale) + (sqrt(sigma/2)*gaussdouble(0.0,1.0)));
}
}
}
error_flag = 0;
//----------------------------------------------------------
//------------------------ add noise -----------------------
//----------------------------------------------------------
if (input_fd == NULL ) {
for (i=0; i<slot_length; i++) {
for (ap=0; ap<frame_parms->nb_antennas_rx; ap++) {
/* Add phase noise if enabled */
if (pdu_bit_map & PUSCH_PDU_BITMAP_PUSCH_PTRS) {
phase_noise(ts, &((int16_t*)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)],
&((int16_t*)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)+1]);
}
((int16_t*) &gNB->common_vars.rxdata[ap][slot_offset])[(2*i) + (delay*2)] = (int16_t)((double)(((int16_t *)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)])/sqrt(scale) + (sqrt(sigma/2)*gaussdouble(0.0,1.0))); // convert to fixed point
((int16_t*) &gNB->common_vars.rxdata[ap][slot_offset])[(2*i)+1 + (delay*2)] = (int16_t)((double)(((int16_t *)&UE->common_vars.txdata[ap][slot_offset])[(i<<1)+1])/sqrt(scale) + (sqrt(sigma/2)*gaussdouble(0.0,1.0)));
}
}
}
else {
AssertFatal(frame_parms->nb_antennas_rx == 1, "nb_ant != 1\n");
// 800 samples is N_TA_OFFSET for FR1 @ 30.72 Ms/s,
@@ -825,6 +830,10 @@ int main(int argc, char **argv)
&gNB->pusch_vars[0]->ul_ch_estimates_ext[0][(start_symbol+1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size],(nb_symb_sch-1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size,1,1);
LOG_M("rxsigF0_comp.m","rxsF0_comp",
&gNB->pusch_vars[0]->rxdataF_comp[0][(start_symbol+1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size],(nb_symb_sch-1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size,1,1);
#ifdef DEBUG_UL_PTRS
LOG_M("rxdataF_ptrs_comp.m","ptrs_comp",
&gNB->pusch_vars[0]->rxdataF_ptrs_comp[0][(start_symbol+1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size],(nb_symb_sch-1)*NR_NB_SC_PER_RB * pusch_pdu->rb_size,1,1);
#endif
}
start_meas(&gNB->phy_proc_rx);
////////////////////////////////////////////////////////////
@@ -902,6 +911,7 @@ int main(int argc, char **argv)
if (print_perf==1) {
printDistribution(&gNB->phy_proc_rx,table_rx,"Total PHY proc rx");
printStatIndent(&gNB->ulsch_channel_estimation_stats,"ULSCH channel estimation time");
printStatIndent(&gNB->ulsch_ptrs_processing_stats,"ULSCH PTRS Processing time");
printStatIndent(&gNB->ulsch_rbs_extraction_stats,"ULSCH rbs extraction time");
printStatIndent(&gNB->ulsch_channel_compensation_stats,"ULSCH channel compensation time");
printStatIndent(&gNB->ulsch_llr_stats,"ULSCH llr computation");
openair1/SIMULATION/TOOLS/phase_noise.c
+42
View File
@@ -0,0 +1,42 @@
/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.1 (the "License"); you may not use this file
* except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.openairinterface.org/?page_id=698
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include "sim.h"
/* linear phase noise model */
void phase_noise(double ts, int16_t * InRe, int16_t * InIm)
{
double fd = 300;//0.01*30000
static double i=0;
double real, imag,x ,y;
i++;
real = cos(fd * 2 * M_PI * i * ts);
imag = sin (fd * 2 * M_PI * i * ts);
x = ((real * (double)InRe[0]) - (imag * (double)InIm[0])) ;
y= ((real * (double)InIm[0]) + (imag * (double)InRe[0])) ;
InRe[0]= (int16_t)(x);
InIm[0]= (int16_t)(y);
}
openair1/SIMULATION/TOOLS/sim.h
+8
View File
@@ -440,6 +440,14 @@ void init_channelmod(void) ;
double N_RB2sampling_rate(uint16_t N_RB);
double N_RB2channel_bandwidth(uint16_t N_RB);
/* Linear phase noise model */
/*!
\brief This function produce phase noise and add to input signal
\param ts Sampling time
\param *Re *Im Real and Imag part of the signal
*/
void phase_noise(double ts, int16_t * InRe, int16_t * InIm);
#include "targets/RT/USER/rfsim.h"
void do_DL_sig(sim_t *sim,