Synchronize multiple gNBs by aligning the slot boundaries
Currently, we derive frame and slot number based on proc->timestamp_rx
using
proc->frame_rx = (proc->timestamp_rx / (fp->samples_per_subframe*10))&1023;
proc->tti_rx = get_slot_from_timestamp(proc->timestamp_rx, fp);
This ignores the samples
proc->timestamp_rx % fp->samples_per_frame
while computing the frame and slot number creating a mis-alignment with
the slot boundaries. A detailed description of the slot misalignment
in a pictorial representation can be seen in an attachment in the MR [1].
We fix this alignment issue by compensating these samples during the
first reception.
We can test the synchronization of the multiple gNBs from the estimated
ToAs from the PRS in the Downlink and the estimated ToAs from the SRS in
the Uplink using rfsim.
In order to test this, make sure you build gNB and nrUE along with the
telnetsrv flag using the option --build-lib telnetsrv.
Also, enable the following log in the function
nr_est_srs_timing_advance_offset() in
openair1/PHY/NR_ESTIMATION/nr_measurements_gNB.c to observe SRS ToAs
LOG_I(NR_PHY, "SRS estimatd ToA %d [RX ant %d]: TA offset %d, TA offset ns %d (max_val %ld, mean_val %ld, max_idx %d)\n", srs_toa, ant, *ta_offset, *ta_offset_nsec, max_val, mean_val, max_idx);
Furthermore, update the option Active_gNBs = 2; in
targets/PROJECTS/GENERIC-NR-5GC/CONF/ue.nr.prs.fr1.106prb.conf to enable
decoding PRS transmitted from two gNBs
To run:
nrUE:
sudo ./nr-uesoftmodem -r 106 --numerology 1 --band 78 -C 3619200000 --uicc0.imsi 001010000000001 --rfsim --phy-test -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/ue.nr.prs.fr1.106prb.conf --rfsimulator.serveraddr server
gNB 0:
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb0.prs.band78.fr1.106PRB.usrpx310.conf --gNBs.[0].min_rxtxtime 6 --rfsim --phy-test --rfsimulator.[0].serveraddr 127.0.0.1 --rfsimulator.[0].options chanmod --rfsimulator.[0].modelname AWGN --telnetsrv
gNB 1:
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb1.prs.band78.fr1.106PRB.usrpx310.conf --gNBs.[0].min_rxtxtime 6 --rfsim --phy-test --rfsimulator.[0].serveraddr 127.0.0.1 --rfsimulator.[0].options chanmod --rfsimulator.[0].modelname AWGN --telnetsrv
When we run the nrUE, gNB0 and gNB1, we can see the following logs
nrUE:
[PHY] [gNB 0][rsc 0][Rx 0][sfn 976][slot 2] DL PRS ToA ==> 0.0 / 2048 samples, peak channel power -16.4 dBm, SNR +4.0 dB, rsrp -42.2 dBm
[PHY] [gNB 1][rsc 0][Rx 0][sfn 976][slot 3] DL PRS ToA ==> 0.0 / 2048 samples, peak channel power -16.4 dBm, SNR +4.0 dB, rsrp -42.2 dBm
gNB 0:
[NR_PHY] SRS estimatd ToA 0 [RX ant 0]: TA offset 31, TA offset ns 0 (max_val 99820162, mean_val 80176, max_idx 0)
gNB 1:
[NR_PHY] SRS estimatd ToA 0 [RX ant 0]: TA offset 31, TA offset ns 0 (max_val 98784562, mean_val 79369, max_idx 0)
From the above logs, when we run the rfsim and when no delays introduced, we can observe the following results
In the Downlink at the UE, the estimated ToAs using PRS from both gNB0
and gNB1 are 0 and in the uplink, the ToA estimated from the SRS
transmitted by the UE at both the gNBs are also 0. This indicates that
both the gNBs are synchronized along with their slot boundaries. We also
highlight that this is not the case in the current develop branch since
the slot boundaries are not aligned.
We also can test the multi gNB synchronization by introducing delays
using telnet as follows,
Introduce new_offset (delay) of 4 samples to the gNB 0 from UE in the
uplink as follows,
openairinterface5g$ echo rfsimu setdistance rfsimu_channel_enB0 20 | ncat --idle 1 127.0.0.80 9080
softmodem_gnb> rfsimu_setdistance_cmd: new_offset 4, new (exact) distance 19.518 m, new delay 0.000065 ms
Ncat: Idle timeout expired (1000 ms).
We can oberve this delay of 4 samples being reflected in the estimated
SRS ToAs at gNB 0 while not changing the ToA in gNB 1
[NR_PHY] SRS estimatd ToA 4 [RX ant 0]: TA offset 31, TA offset ns 65 (max_val 98803636, mean_val 79430, max_idx 8)
similarly, Introduce new_offset (delay) of 2 samples to the gNB 1 from
UE in the uplink as follows,
openairinterface5g$ echo rfsimu setdistance rfsimu_channel_enB0 10 | ncat --idle 1 127.0.0.81 9081
softmodem_gnb> rfsimu_setdistance_cmd: new_offset 2, new (exact) distance 9.759 m, new delay 0.000033 ms
Ncat: Idle timeout expired (1000 ms).
We can oberve this delay of 2 samples being reflected in the estimated
SRS ToAs at gNB 1 while not changing the ToA in gNB 0
[NR_PHY] SRS estimatd ToA 2 [RX ant 0]: TA offset 31, TA offset ns 32 (max_val 98962768, mean_val 79552, max_idx 4)
Closes#897
[1] https://gitlab.eurecom.fr/oai/openairinterface5g/-/merge_requests/3892
Remove L1 dependence from NR band number
L1 band information relied on get_band function that couldn't provide an
unambiguous result. Also there is no SCF compliant parameter for L1 and
generally we don't really need that information in L1.
The MR also remove a RU section that used nr_band but was never really
accessed in NR.
NR UE: correctly compute writeTimestamp for SCS > 30 kHz with rf-simulator
Contains also two minor cleanups for nr-ue.c:
- make fp point to constant NR_DL_FRAME_PARMS where possible
- use c16_t type for I/Q sample arrays
Currently, we derive frame and slot number based on `proc->timestamp_rx`
using
`proc->frame_rx = (proc->timestamp_rx / (fp->samples_per_subframe*10))&1023;` and
`proc->tti_rx = get_slot_from_timestamp(proc->timestamp_rx, fp);`
This ignores the samples `proc->timestamp_rx % fp->samples_per_frame`
while computing the frame and slot number creating a mis-alignment with the slot boundaries.
We fix this alignment by compensating these samples during the first reception.
In the case that the config module cannot load the driver for libconfig
or yaml, currently, there might be a cascade of errors that are
difficult for users to understand. For instance (partially redacted for
clarity):
[CONFIG] Error calling dlopen(libparams_libconfig.so): libparams_libconfig.so: cannot open shared object file: No such file or directory
[CONFIG] config module "libconfig" couldn't be loaded
[CONFIG] config_get, section log_config skipped, config module not properly initialized
[LOG] init aborted, configuration couldn't be performed
[CONFIG] config_get, section (null) skipped, config module not properly initialized
[CONFIG] /home/francesco/openairinterface5g/common/config/config_userapi.c 68 nfapi has no processed integer availablle
[CONFIG] config_get, section (null) skipped, config module not properly initialized
Assertion (get_softmodem_params()->default_pdu_session_id == -1) failed!
In get_common_options() /home/francesco/openairinterface5g/executables/softmodem-common.c:161
Use uicc0.pdu_sessions.[0].id to change the requested PDU session ID (is 0)
Here, the error is the missing shared object, but a user is more likely
to look at the last error instead of the first.
This commit addresses it by checking early for
CONFIG_ISFLAGSET(CONFIG_ABORT), and stopping if it is set. Additionally
changes include making functions static, removing late
CONFIG_ISFLAGSET() checks, and the CONFIG_ISFLAGSET() in
load_configmodule(), because at that time "uniqCfg" is not set yet and
thus does not do anything (this is likely a regression of an earlier
cleanup).
See-also: f50d5f5a9b ("make multiple config instead of one implicit
global")
Cleanup Cmake: remove some double compilation
Harmonize some cmake code to avoid double compilation, notably around
polar and smallblock. In develop, we just add their sources to other
targets, whereas now we define STATIC libraries (further changed to
shared library in !3856) to avoid double compilation.
With this command line:
cmake .. -GNinja -DENABLE_TESTS=ON && ninja
shows that before we compile 12631 files, where after it is 12583
there is additional supporting cleanup (move code, remove headers,
types, ...).
there is more harmonization to do, I limited myself to some easy wins.
For instance, we do the same with PDCP/SDAP, and this should be
refactored into STATIC libraries as well.
semi-manual remove of not used #define commands
As i was upset to see all these #define with no code under, i made a
global pass to remove the obvious cases semi-manual remove of not used
bodies
manual script, then a lot of manual review
grep -IRs "#define" ../openair* ../common/* ../executables/ ../nfapi/ ../radio/ | \
fgrep -v '(' | fgrep -v '//' |awk '{print $2}' | egrep -v "#define *$n"| \
while read n ; do
grep -IRs $n ../openair* ../common/* ../executables/ ../nfapi/ ../radio/ | grep -v "#define *$n" | grep -q $n || echo $n;
done
will give a decent list of #define never used. Then, I think we should
keep lists of # define when it comes from standards, even if the code
doesn't use it right now
Add Ethernet PDU session support and make PDU session request configurable
This MR adds support for Ethernet PDU sessions, and makes PDU sessions
configurable: per-PDU session ID, type (IPv4/IPv4v6/IPv6/Ethernet [1]),
DNN, NSSAI.
Concretely, it adds a new configuration file section pdu_sessions below
uicc0 that looks like this if everything is specified (default values
are shown):
uicc0:
[...]
pdu_sessions:
- id: 1
type: "IPv4"
nssai_sst: 1
nssai_sd: 0xffffff
dnn: "oai"
It is possible to list multiple PDU sessions (add new line - id: 2 to
request a second PDU session). It is backwards-compatible to the current
PDU session configuration (uicc0.dnn/nssai_sst/etc), the idea being that
either legacy or new configuration could be used, but (1) if
pdu_sessions exist, it will overwrite the legacy configuration, and (2)
multiple PDU sessions, and type, can only be configured using the new
config. The old parameters --extra-pdu-id and --default-pdu-id are not
accepted anymore. Documentation has been added to the UE tutorial.
It is possible to test an Ethernet PDU session [1]. It is possible to
test the PDU session inside the UE by verifying it has an TAP interface
oaitap_ue1, and ARPing the data network (arping has been added to
oai-nr-ue container for that purpose):
ip addr add 192.168.72.140/26 dev oaitap_ue1 # same subnet as data network!
ip link set dev oaitap_ue1 up
arping -c 20 -I oaitap_ue1 192.168.72.135 # will send ARP request in Ethernet frame to get IP address of data network
[1] See description MR !3769 for more information. On the UE side, only
the type has to be changed to "Ethernet".
NR UE: add support for multiple RF frontends
This MR adds basic support for multiple RF-frontends at the UE.
There are multiple reasons why we might want this:
1. There might be different antennas needed for different bands (e.g. NTN or
TN antennas). These antennas might be connected to different RF-frontends.
In case of Handover, the UE needs to dynamically switch between these
RF-frontends.
2. Each rf-simulator connection carries baseband I/Q samples. To be able to
perform a handover between two cells at different frequencies, there must
be two rf-simulator connections, as the baseband channels should not
interfere and thus cannot simply be added.
3. When we want to support multiple UE simulation within one instance of
nr-uesoftmodem, and allow multiple cells and probably even handover between
these cells, we need either:
1. dedicated RF-frontends for each simulated UE, or
2. dedicated RF-frontends for each connected cell and dynamically assign
simulated UEs accordingly.
This MR implements what is needed for 1., 2. and 3.1.
Use the new PDU session configuration functionality of the parent
commit. It is now possible to request multiple PDU sessions, and to
request specific PDU session types. While the new uicc0.pdu_sessions is
preferred, it is still possible to use the "legacy"
uicc0.dnn/nssai_sst/nssai_sd.
The old parameters --default-pdu-id and --extra-pdu-id are not allowed
anymore, as it is possible to manually define this in the UE
configuration. Correspondingly, fix the use of those options, where
applicable.
Note: since the default_pdu_id is changed to -1, all interface names
will have pX to interface names appended (oaitun_ue1pX). The next commit
will correct this.
When writing dummy data or reading to trash, we don't need to allocate data buffers for each antenna.
We can allocate just for one antenna and use this buffer for each antenna.
This feature shall allow in future to simulate an arbitratry number of UEs connected to an other arbitrary number of cells.
Therefore each RF-frontend (also called RU) needs to be configured for one specific cell.
In case of handover of a UE from one cell to another cell, it needs to switch RUs accordingly (TODO).
There has to be a 1-to-1 mapping between RUs and cells.
Each UE will be assigned to one of the defined cells.
Initially all UEs are assigned to cell 0.
The global variable rx_gain_off was always 0.0, as it was not even modified by the NR UE command line parameter --ue-rxgain-off.
That command line parameter modified only a parameter in the struct nrUE_params_t, which was not used at all and is removed in this commit, too.
Also, the global variable rx_gain_off was just added to rx_total_gain_dB and subtracted from it again in nr_rf_card_config_gain().
So we simplify that function slightly, too.
FHI 7.2 does not have a field for the number of RACH Occasions.
It seems this needs to be manually configured, and M plane has field
num-prach-re to set the number of frequency domain PRACH occasions.
PROBLEM: In PNF mode, L1 is started from nfapi_pnf.c without verifying RU
readiness. The only gate is config_sync_var, but nr_softmodem.c sets this before
the RU (e.g., FHI-72) is actually started. As a result, START_REQUEST can
trigger L1 init while the RU is not yet ready -- this is an issue when using
FHI72 with DPDK BBDEV, where a pre-mature L1 init will crash the entire program
as DPDK BBDEV depends on xRAN's DPDK EAL.
FIX: Perform RU readiness checks before setting config_sync_var in NFAPI PNF mode.
This aligns PNF behavior with other modes and prevents L1 from starting before the
RU is operational.
These logs are very helpful to identify cell configuration
changes in MAC/PHY, for monitoring purposes, and to rapidly
signal integrity failures during re-establishment.
Robert Schmidt