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srsLTE
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remove SL specific CFO correction method

This commit is contained in:
Andre Puschmann 2020-02-23 14:56:56 +01:00
parent 09f7355870
commit 151ce10a96
3 changed files with 1 additions and 50 deletions
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2
lib/include/srslte/phy/sync/cfo.h
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@ -62,6 +62,4 @@ srslte_cfo_correct_offset(srslte_cfo_t* h, const cf_t* input, cf_t* output, floa
SRSLTE_API float srslte_cfo_est_corr_cp(cf_t* input_buffer, uint32_t nof_prb);
SRSLTE_API float srslte_sl_cfo_est_corr_cp(cf_t* input_buffer, uint32_t nof_prb, srslte_cp_t cp);
#endif // SRSLTE_CFO_H

3
lib/src/phy/phch/test/pscch_file_test.c
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@ -238,8 +238,7 @@ int main(int argc, char** argv)
nread = -1;
}
// CFO estimation and correction
srslte_sl_cfo_est_corr_cp(input_buffer, cell.nof_prb, cell.cp);
// Convert to frequency domain
srslte_ofdm_rx_sf(&fft);
if (cell.tm == SRSLTE_SIDELINK_TM1 || cell.tm == SRSLTE_SIDELINK_TM2) {

46
lib/src/phy/sync/cfo.c
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@ -146,50 +146,4 @@ float srslte_cfo_est_corr_cp(cf_t* input_buffer, uint32_t nof_prb)
float cfo = (float)(-1 * carg(cfo_estimated) / (float)(2 * M_PI * tFFT));
srslte_vec_apply_cfo(input_buffer, (float)(1 / (nFFT * 15e3)) * ((-15e3 / 2.0) - cfo), input_buffer, sf_n_samples);
return cfo;
}
/*
* Sidelink CFO estimation and correction based on cp
*/
float srslte_sl_cfo_est_corr_cp(cf_t* input_buffer, uint32_t nof_prb, srslte_cp_t cp)
{
int symbol_sz = srslte_symbol_sz(nof_prb);
int sf_n_samples = SRSLTE_SF_LEN_PRB(nof_prb);
float tFFT = (float)(1 / 15000.0);
int cp_size = SRSLTE_CP_SZ(symbol_sz, cp);
int cp_size_0 = (cp == SRSLTE_CP_NORM) ? SRSLTE_CP_LEN_NORM(0, symbol_sz) : cp_size;
// Compensate for initial SC-FDMA half subcarrier shift, cfo = 7500 / (15000 * symbol_sz) <=> 1 / (symbol_sz * 2.0)
srslte_vec_apply_cfo(input_buffer, (1 / (float)(symbol_sz * 2.0)), input_buffer, sf_n_samples);
uint32_t p1 = 0;
uint32_t p2 = symbol_sz;
uint32_t cp_len = 0;
uint32_t sf_n_symbols = (cp == SRSLTE_CP_NORM)
? (14 - 1)
: (12 - 1); // // TS 36.211 Section 9.3.2: The last SC-FDMA symbol in a sidelink subframe,
// serves as a guard period and shall not be used for sidelink transmission.
cf_t average_cfo = 0.0f;
for (int i = 0; i < sf_n_symbols; i++) {
// Calculate CP length
cp_len = (i == 0 || i == SRSLTE_CP_NSYMB(cp)) ? cp_size_0 : cp_size;
// Correlate CP with tail
average_cfo += srslte_vec_dot_prod_conj_ccc(&input_buffer[p2], &input_buffer[p1], cp_len);
// Increment pointers for next symbol
p1 += cp_len + symbol_sz;
p2 += cp_len + symbol_sz;
}
float cfo = (float)(carg(average_cfo) / (float)(2 * M_PI * tFFT));
// Compensate for initial SC-FDMA half subcarrier shift, cfo = - 7500 / (15000 * symbol_sz) <=> 1 / (symbol_sz * 2.0)
srslte_vec_apply_cfo(
input_buffer, (-1 / (float)(symbol_sz * 2.0)) + (-cfo / (float)(15e3 * symbol_sz)), input_buffer, sf_n_samples);
return cfo;
}