As we don't have SIB19 with continuously updated ta-Common and ta-CommonDrift values yet, the UE can only adapt it's UL timing according to it's DL drift.
This is required for the UE to keep UL sync with fast time drift and relatively long RTT (e.g. LEO satellite).
We should replace this with the standard compliant way as soon as we have SIB19 with continuously updated contents.
While we don't have SIB19 support yet, UE gets this parameter from command line, just like --ntn-koffset and --ntn-ta-common.
We use this value to initialize the UE's time-tracking PI controller accumulator.
This allows to correctly track the time even if the delay is changing significantly (e.g. due to LEO satellite movement).
We also use it to compensate for the time drift that happenes while performing the initial sync.
- if search fails, keeps increasing the rx gain (set by --ue-rxgain) by
3 db until USRP max rx gain
- if initial sync is success, sets the rxgain to the value of
(TARGET_RX_POWER (50) - pbch digital power in dB/RE)
According to the RRC specification, cellSpecificKoffset is:
Scheduling offset used for the timing relationships that are modified for NTN (see TS 38.213 [13]).
The unit of the field K_offset is number of slots for a given subcarrier spacing of 15 kHz.
If the field is absent UE assumes value 0
This parameter `cellSpecificKoffset_r17` can be set via UE command line parameter `--ntn-koffset`.
- Reworked nrLDPC_decoder_offload.c to process all segments in a TB with a single call to LDPCdecoder() or LDPCencoder().
- Perform CRC checks on the T2.
- Modified nr_ulsch_decoding (gNB decoder) to:
- Count processed segments.
- Properly perform CRC checks.
- Created a constant NR_LDPC_MAX_NUM_CB to define the maximum number of codeblocks.
- Conditional library loading:
- On gNB: Load ldpc_t2 library if offload is enabled using the --ldpc-offload-enable flag.
- On UE: Load both ldpc_t2 and ldpc libraries since only encoder offload is supported.
- General cleanup of nrLDPC_decoder_offload.c for improved readability and maintainability.
- Modified the structure of LDPC encoder/decoder/offload parameters:
- Introduced a structure for code block (CB) related parameters.
- Removed parameter E from the encoder and offload parameter structures for clarity.
- Replaced E with perCB->E_cb in the UE encoder code.
- Phy config update and Sidelink frame parameters initialisation
- PSBCH scheduler to trigger TX PSBCH/RX PSBCH actions
- Sidelink indication with rx ind to trigger send SL-MIB to MAC
- Enable Scope for PSBCH use -d or --dqt
- Enable system testing of PSBCH for example using RFSIMULATOR:
- UE1 is a SYNCRONISATION SOURCE UE which transmits PSBCH
started using command -
sudo ./nr-uesoftmodem --sl-mode 2 --sync-ref 4 --rfsim --rfsimulator.serveraddr server
- UE2 syncs onto UE1 during sidelink search, gets the timing and continues to receive PSBCH
started using command -
sudo ./nr-uesoftmodem --sl-mode 2 --rfsim --rfsimulator.serveraddr 127.0.0.1
- In the default use case 2 Sidelink SSBs sent over 16 frames.
- In case SL-SSB configuration needs to be changed use -O option in the above command like
-O ../../../targets/PROJECTS/NR-SIDELINK/CONF/sidelink_preconfig_1txpool.conf
Doing only 5 LDPC iterations by default leads to a poor reception
performance, and correspondingly many retransmissions. Increase to 8 as
the new default to improve user experience.
Config options --reconfig_file and --rbconfig-file have been introduced
to modify the filenames of reconfig.raw and rbconfig.raw (e.g., in the
case of multiple UEs). These filen*ames* were to be prepended with
--rrc_config_path to set the path. In summary, three options were
necessary, when two are sufficient.
In this commit, change to the options --reconfig-file and
--rbconfig-file (slight change for harmonization with other options,
which mostly use dashes) to give the full path to the corresponding
files, and avoid to surprise users who would not expect to have three
options.
--rrc_config_path has been deprecated and an error will be printed if a
user attempts to use it.
1. Adding a "SL" frequency for Sidelink mode. The
importance of this variable is to ensure that
when we are in mode 1 (UE+UE+gNB), that the slot
configuration and frequencies do not overlap. This
SL frequency is important for rotation and allows
us to utilize the OFDM modulation and demodulation
functions that already exist in OAI.
2. Adding sl_mode to the command line for proper UE
deployment when in SL mode. sl_mode can be set to 0,
1, or 2. sl_mode 0 indicates no-Sidelink at all,
mode 1 is gNB, UE, and UE (3GPP defines mode numbers).
sl_mode 2 indicated UE to UE communications with no
gNB at all.
3. New functions for calculating the carrier frequency
for SL mode.
Thomas Schlichter