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PHY: add parameter end_of_burst_delay for TDD

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end_of_burst_delay is used to stop TX only "after a while".
If we stop right after effective signal, with USRP B210 and
B200mini, we observe a high EVM on the S subframe (on the
PSS).
A value of 400 (for 30.72MHz) solves this issue. This is
the default.

This default value can be changed in the configuration file.
For example:

RUs = (
    {
       local_rf       = "yes"
         nb_tx          = 1
         nb_rx          = 1
         att_tx         = 20
         att_rx         = 0;
         bands          = [7];
         max_pdschReferenceSignalPower = -27;
         max_rxgain                    = 105;
         eNB_instances  = [0];
         sf_extension = 312;
         end_of_burst_delay = 200;
    }
);

Here we would set a value of 200.

The value to put in the configuration file is for
30.72MHz. The value is scaled accordingly at runtime
(thus only one value to set for every RB configuration,
25, 50 or 100, leading to less problems when adapting
configuration files).

This option is for experts and should not be changed
randomly.
This commit is contained in:
Cedric Roux
2019-03-19 09:25:43 +01:00
parent a05753dff3
commit 275e5b3a64
3 changed files with 26 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
targets/RT/USER/lte-ru.c
+21 -4
View File
@@ -825,8 +825,16 @@ void tx_rf(RU_t *ru) {
int siglen=fp->samples_per_tti,flags=1;
if (SF_type == SF_S) {
/* end_of_burst_delay is used to stop TX only "after a while".
* If we stop right after effective signal, with USRP B210 and
* B200mini, we observe a high EVM on the S subframe (on the
* PSS).
* A value of 400 (for 30.72MHz) solves this issue. This is
* the default.
*/
siglen = (fp->ofdm_symbol_size + fp->nb_prefix_samples0)
+ (fp->dl_symbols_in_S_subframe - 1) * (fp->ofdm_symbol_size + fp->nb_prefix_samples);
+ (fp->dl_symbols_in_S_subframe - 1) * (fp->ofdm_symbol_size + fp->nb_prefix_samples)
+ ru->end_of_burst_delay;
flags=3; // end of burst
}
@@ -1379,12 +1387,20 @@ int setup_RU_buffers(RU_t *ru) {
ru->N_TA_offset = 0;
if (frame_parms->N_RB_DL == 100) /* no scaling to do */;
else if (frame_parms->N_RB_DL == 50) ru->sf_extension /= 2;
else if (frame_parms->N_RB_DL == 25) ru->sf_extension /= 4;
else { printf("not handled, todo\n"); exit(1); }
else if (frame_parms->N_RB_DL == 50) {
ru->sf_extension /= 2;
ru->end_of_burst_delay /= 2;
} else if (frame_parms->N_RB_DL == 25) {
ru->sf_extension /= 4;
ru->end_of_burst_delay /= 4;
} else {
printf("not handled, todo\n");
exit(1);
}
} else {
ru->N_TA_offset = 0;
ru->sf_extension = 0;
ru->end_of_burst_delay = 0;
}
if (ru->openair0_cfg.mmapped_dma == 1) {
@@ -2884,6 +2900,7 @@ void RCconfig_RU(void) {
RC.ru[j]->num_bands = RUParamList.paramarray[j][RU_BAND_LIST_IDX].numelt;
/* sf_extension is in unit of samples for 30.72MHz here, has to be scaled later */
RC.ru[j]->sf_extension = *(RUParamList.paramarray[j][RU_SF_EXTENSION_IDX].uptr);
RC.ru[j]->end_of_burst_delay = *(RUParamList.paramarray[j][RU_END_OF_BURST_DELAY_IDX].uptr);
for (i=0; i<RC.ru[j]->num_bands; i++) RC.ru[j]->band[i] = RUParamList.paramarray[j][RU_BAND_LIST_IDX].iptr[i];
} //strcmp(local_rf, "yes") == 0