[srslte-users] SRS support
ALEJANDRO BLANCO PIZARRO
100283180 at alumnos.uc3m.es
Fri May 24 14:18:32 UTC 2019
Hi Naveen,
I do not remember such error when I did it. BTW, the version that I used of
srsLTE was 17.10 I think.
Best,
Alejandro
El vie., 24 may. 2019 16:11, Naveen Rawat <
naveen.rawat at cohere-technologies.com> escribió:
> Hi Alejandro,
>
>
>
> After enabling SIB, I see that ping is not going through over LTE link
> between UE and eNB. Did you face this issue as well?
>
>
>
> Thanks and Regards
>
> Naveen Rawat
>
>
>
> *From: *ALEJANDRO BLANCO PIZARRO <100283180 at alumnos.uc3m.es>
> *Date: *Thursday, May 23, 2019 at 2:51 AM
> *To: *Naveen Rawat <naveen.rawat at cohere-technologies.com>
> *Subject: *Re: [srslte-users] SRS support
>
>
>
> Hi Naveen,
>
>
>
> Thanks for response and this is good to know. Can you tell me to what
> extent were you able to make it work. I am worried that after SRS is sent
> by UE, since eNB cannot understand it, this could make the connection
> un-stable.
>
>
>
> Thanks for response and this is good to know. Can you tell me to what
> extent were you able to make it work. I am worried that after SRS is sent
> by UE, since eNB cannot understand it, this could make the connection
> un-stable.
>
>
>
> I do not completely understand it. Basically, the srsenb cannot handle the
> SRS, but this does not mean that the communication becomes unstable. What
> is going to happen, depending in your SRS configuration, you will have in a
> specific subframe and position the SRS and the srsenb is not going to
> anything with that information. In my case, I saved the SRS in a file to
> later process it offline. I was interesting in estimating the distance
> between the UE and eNB but not in real time, so it is does not mind.
>
>
>
> Please help me with following questions:
>
> 1. Location of your modifications.
>
> What I am going to show you was personal decisions of the code, probably
> there is a better way to do it.
>
>
>
> 1º Add to the sib.conf (attached) the configuration regarding the SRS
> configuration:
>
>
>
> srs_ul_cnfg =
> {
> bw_cnfg = 0; // LIBLTE_RRC_SRS_BW_CONFIG_ENUM
> subfr_cnfg = 1; // LIBLTE_RRC_SRS_SUBFR_CONFIG_ENUM
> ack_nack_simul_tx = false; // bool
> max_up_pts = true; // bool
> max_up_pts_present = true; // bool
> present = true; // bool
> };
>
>
>
> 2º Add the lines to take the information from sib.conf in the parser:
> enb_cfg_parser (attached)
>
>
>
> // SRS_UL_CNFG configuration
> parser::section srs_ul_cnfg("srs_ul_cnfg");
> rr_config.add_subsection(&srs_ul_cnfg);
>
> srs_ul_cnfg.add_field(
> new parser::field_enum_num<LIBLTE_RRC_SRS_BW_CONFIG_ENUM,uint8>
> ("bw_cnfg", &data->rr_config_common_sib.srs_ul_cnfg.bw_cnfg,
> liblte_rrc_srs_bw_config_num,LIBLTE_RRC_SRS_BW_CONFIG_N_ITEMS)
> );
> srs_ul_cnfg.add_field(
> new parser::field_enum_num<LIBLTE_RRC_SRS_SUBFR_CONFIG_ENUM,uint8>
> ("subfr_cnfg", &data->rr_config_common_sib.srs_ul_cnfg.subfr_cnfg,
> liblte_rrc_srs_subfr_config_num,LIBLTE_RRC_SRS_SUBFR_CONFIG_N_ITEMS)
> );
>
> srs_ul_cnfg.add_field(
> new parser::field<bool>
> ("ack_nack_simul_tx",
> &data->rr_config_common_sib.srs_ul_cnfg.ack_nack_simul_tx)
> );
> srs_ul_cnfg.add_field(
> new parser::field<bool>
> ("max_up_pts", &data->rr_config_common_sib.srs_ul_cnfg.max_up_pts)
> );
> srs_ul_cnfg.add_field(
> new parser::field<bool>
> ("max_up_pts_present",
> &data->rr_config_common_sib.srs_ul_cnfg.max_up_pts_present)
> );
> srs_ul_cnfg.add_field(
> new parser::field<bool>
> ("present", &data->rr_config_common_sib.srs_ul_cnfg.present)
> );
>
>
>
> And change from false to true this line:
> sib2->rr_config_common_sib.srs_ul_cnfg.present = true;
>
>
>
> 3º Add to srsenb/src/upper/rrc.cc these lines of code:
>
>
>
> // Configure Sounging Reference Signal
> if (parent->sib2.rr_config_common_sib.srs_ul_cnfg.present){
> fprintf(stderr, "Estamos configurnado srs\n");
> phy_cfg->srs_ul_cnfg_ded_present = 1;
> phy_cfg->srs_ul_cnfg_ded.srs_bandwidth = LIBLTE_RRC_SRS_BANDWIDTH_BW0;
> phy_cfg->srs_ul_cnfg_ded.srs_hopping_bandwidth =
> LIBLTE_RRC_SRS_HOPPING_BANDWIDTH_HBW0 ;
> phy_cfg->srs_ul_cnfg_ded.cyclic_shift = LIBLTE_RRC_CYCLIC_SHIFT_CS0 ;
> phy_cfg->srs_ul_cnfg_ded.freq_domain_pos = 0;
> phy_cfg->srs_ul_cnfg_ded.srs_cnfg_idx = 0;
> phy_cfg->srs_ul_cnfg_ded.tx_comb = 0;
> phy_cfg->srs_ul_cnfg_ded.setup_present = 1;
> phy_cfg->srs_ul_cnfg_ded.duration = 1;
> }
>
>
>
> Now, the configuration from SIB2 and rrc messages supports SRS. As the UE
> decodes this informatio, it will send the SRS to the eNB without any
> configuration from the UE side.
>
>
>
> 4º Now you have to take the SRS from the eNB. What I did was to configure
> the SRS to be sent every 10 TTI, so I save the SRS to a file. Assuming that
> it is sent the last symbol of the subframe you can extract it. To do it,
> you can take it from the file phch_worker.cc, the variable where you can
> take it is the buffer of the eNB.
>
> Here an example to do it:
>
>
>
> srslte_filesink_t sink;
>
> int start = X % where the signal start
>
> int size = 576*2; % the size of the SRS
> srslte_filesink_init(&sink, buf, SRSLTE_COMPLEX_FLOAT_BIN);
> cf_t * signal = enb_ul.fft.out_buffer;
> srslte_filesink_write(&sink, (void *) &signal[start] , tot);
>
>
>
> Sorry but this part is not programatical, it depends on your
> configuration. But was enough for my purpose.
>
>
>
>
>
> 1. With srsUE, you said SRS could be enabled, but srsEnb could not
> understand them. Did connection drop or did not even work?
>
>
> 1. If srsENB somehow worked, did you make changes to ignore SRS
> received ?
>
> The connection does not drop. And not
>
>
> 1.
>
>
> 1. Did you make progress with smartphone for SRS ?
>
>
>
> Unfortunately not. Sorry
>
>
>
> If you achieve to work with a smartphone tell me.
>
>
>
> I totally recommend you to read the standard and forums to understadn how
> to configure the SRS.
>
>
>
> Good luck. Best,
>
> Alejandro
>
>
>
> I am trying to achieve something similar to what you did, by using SRS at
> eNB for my experimentations.
>
>
>
> Thanks and Regards
>
> Naveen Rawat
>
>
>
>
>
> *From: *ALEJANDRO BLANCO PIZARRO <100283180 at alumnos.uc3m.es>
> *Date: *Wednesday, May 22, 2019 at 1:56 AM
> *To: *Naveen Rawat <naveen.rawat at cohere-technologies.com>
> *Cc: *"srslte-users at lists.softwareradiosystems.com" <
> srslte-users at lists.softwareradiosystems.com>
> *Subject: *Re: [srslte-users] SRS support
>
>
>
> Hi Naveen,
>
>
>
> From my experience, SRS is not fully handled by srsLTE. As far as I know,
> srsUE is able to send it but srsenb cannot use it.
>
>
>
> One year ago, I worked with SRS and basically what I did was to add some
> parameter to SIB2 and RRC messages to active them, thus the srsUE can send
> it. As the srsenb cannot handle it, I saved the SRS in a file and process
> it offline.
>
>
>
> In addition, I tried to configure the SRS and check if a smartphone can
> send it, but I couldn't do it. I used the srsUE for my application.
>
>
>
> Here you have the message that I posted in the mailing list of srsLTE:
> http://www.softwareradiosystems.com/pipermail/srslte-users/2018-May/001575.html.
> Thanks to Ismael I could use the SRS.
>
>
>
> If you need further information tell me. I can tell you what was my
> configuration and which files of the code I modified.
>
>
>
> Best,
>
> Alejandro
>
>
>
> El mar., 21 may. 2019 a las 9:10, Naveen Rawat (<
> naveen.rawat at cohere-technologies.com>) escribió:
>
> Hi srsLte Team,
>
>
>
> I am looking for setting for enabling SRS. I found a bug was opened for
> this but looks like bug was closed with a commit. However I am unable to
> find the related config. Can you please tell if this was implemented from
> eNB side and what is the config to trigger that.
>
>
>
> Thanks and Regards
>
> Naveen Rawat
>
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>
>
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