Make sure to apply Doppler and TA not directly when receiving the target cell ntn_config,
but apply Doppler just before the initial sync, and the TA after the initial sync when
we have tha actuel cell frame and slot numbers.
We need the ntn_config when reconfiguring the PHY layer for a new initial sync,
e.g. for calculating the DL Doppler frequency.
As a dedicated scheduled_response dl_config PDU it reaches the PHY layer too late,
as part of the phy_config.config_req it reaches the PHY layer in time with the
other configuration values.
Instead of trying to estimate N_UE_TA_adj with a second degree polynomial,
we introduce orbit propagation to calculate N_UE_TA_adj with higher accuracy.
When we receive the satellite ephemeris data consisting of the satellite position vector
and the satellite velocity vector, we calculate parameters for orbit propagation, assuming
a circular orbit in the plane created by the satellite position vector and the satellite
velocity vector. This is done in the function prepare_ue_sat_ta().
Every millisecond, we use these parameters together with the time since epoch to calculate
the satellite position on that orbit and from this the reound-trip-time between UE and the
satellite, what corresponds to N_UE_TA_adj. This is done in the function apply_ntn_timing_advance().
The acceleration magnitude on the orbital path can be calculated as:
t = 2 * pi * r / v
omega = 2 * pi / t = v / r
acceleration = omega² * r = v² / r
Where t is the orbital period, r is the orbital radius, v is the orbital velocity, omega is the angular velocity.
The acceleration direction is from the SAT position towards the earth center.
To calculate the acceleration towards the UE, this is projected on the direction from the SAT to the UE.
simplify and make more local variables in nr_rx_pdcch() and fix small bugs...
simplify and make more local variables in nr_rx_pdcch() and fix small bugs
(size 9 RE instaed of 12 RE)
TS 38.213 4.1 says coreset 0 is present only if kssb < 24 for FR1 and <
12 for FR2. This commit sets get_sib1 flag based on kssb.
Also, setting of mac state is taken out of function nr_ue_decode_mib().
continuously update SIB19 information for rfsim NTN LEO scenarios
Contains mainly these changes:
- gNB: add function nr_update_sib19() allowing to update SIB19
information
- rfsimulator: update SIB19 contents every frame for LEO channel
simulations
- NR UE: improve initial timing advance calculation from SIB19
Before, we only considered ta_Common_r17 and the SAT position from SIB19
to compute the initial timing advance value. This is good enough if the
satellite does not move too fast (e.g. GEO satellite).
Now we also consider ta_CommonDrift_r17, ta_CommonDriftVariant_r17 and
the SAT velocity together with the epoch time from SIB19. This improves
the accuracy of the initial TA computation, esp. for LEO satellite
scenarios.
Before, we only considered ta_Common_r17 and the SAT position from SIB19 to compute the initial timing advance value.
This is good enough if the satellite does not move too fast (e.g. GEO satellite).
Now we also consider ta_CommonDrift_r17 and the SAT velocity together with the epoch time from SIB19.
This improves the accuracy of the initial TA computation, esp. for LEO satellite scenarios.
Enabling usage of ulsyncvalidityDuration timer in SIB19
ntn-UlSyncValidityDuration in SIB19 from Spec 38.331 v17.12 A validity
duration configured by the network for assistance information which
indicates the maximum time duration (from epochTime) during which the UE
can apply assistance information without having acquired new assistance
information. The unit of ntn-UlSyncValidityDuration is second. Value s5
corresponds to 5 s, value s10 indicate 10 s and so on.
ntn-UlSyncValidityDuration-r17 ENUMERATED{ s5, s10, s15, s20, s25, s30, s35,s40, s45, s50, s55, s60, s120, s180, s240, s900}
Implementation of epochtime is under discussion.
It can be configured in configuration file according to the above
enumeration. For GEO - 240s, MEO - 20s, LEO-5s can be used.
Suspend RBs at UE
In case of suspended radio bearer (by RRC), the MAC needs to discarded received
PDUs and avoid to transmit using LCID related to that RB
SPEC 38.331 section 5.2.2.6
Inform MAC that UL SYNC got lost because of T430 expiry
- Send message NR_MAC_RRC_CONFIG_RESET with cause UL_SYNC_LOST_T430_EXPIRY to MAC
Reacquire SIB19 after T430 expiry
This is not checked in this commit
- RACH needs to be performed through probably PDCCH order to reobtain UL-SYNC
- system usecase involving Recovery from T430 expiry not tested yet as that requires changes on gNB side.
The UE stores PDCCH search spaces from the network in NR_BWP_PDCCH_t
struct within NR_UE_MAC_INST_t. After storing, the pointers otherSI_SS,
ra_SS and paging_SS are updated to point to the stored SS. Multiple
pointers could point to the same stored SS struct depending on
configuration. Then when the UE wants to release the SS, the pointers
are used to free the stored SS using ASN_STRUCT_RESET(). If multiple
pointers point to the same SS, calling ASN_STRUCT_RESET() on all
pointers would lead to double free. So one needs to check for dangling
pointer before freeing.
Instead of using pointers and assigning them during configuration, we
use SS id for otherSI_SS, ra_SS and paging_SS to retrieve the pointers
whenever needed. When the UE wants to release the SS, we make them -1
indicating an invalid SS id.
K-offset updated with configured sub carrier spacing
According to 38.331 , cell specific K-OFFSET provided in SIB19 is provided in
number of slots as per 15Khz SCS Koffset before being applied, needs to be
updated to the slots according to the configured subcarrier spacing.
According to 38.331 , cell specific K-OFFSET provided in SIB19 is provided in number of slots as per 15Khz SCS
Koffset before being applied, needs to be updated to the slots according to the configured subcarrier spacing.
fix NTN LEO scenarios
- gNB: add support for NTN parameter ta-CommonDrift-r17
- NR UE: fix application of NTN TA information
- NR UE: add command line parameter ntn-initial-time-drift to compensate
time drift during initial sync
- NR UE: fix writeTimestamp inconsistencies
- NR UE: add MAC state UE_RECEIVING_SIB ensuring to start RA only after
successfully receiving SIBs
- rfsimulator: update earth radius for LEO simulation to match UE
position in ue.conf file
- update conf files for NTN LEO scenario
- update description how to run NTN scenarios in RUNMODEM.md
- fix: ta-Common is a round-trip-time, not a one-way delay
- NR UE: simplify calculation of next_tx_slot_and_frame by moving up
assignment of duration_rx_to_tx
- cellbarredNTN indicates notbarred in SIB1 if NTN access is available
- Removed b66 NTN and enabled B254 NTN conf file in CI
- NR UE: RRC layer now explicitly tells MAC layer when the RA procedure
can be started
- move NTN LEO config to band 254 and update doc/RUNMODEM.md
Closes#901
Thomas Schlichter