A number of warnings appear when compiling flexric with gcc-12, which we
use in the next commit. Those have been fixed upstream. Switch to the
updated version to avoid warnings.
- 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
Neighbor configuration can be given by gNB.conf
get_MeasConfig function is extended as it will prepare A2 / A3 Report
Configs. Single Meas Obj is used for all.
rrc_gNB_process_MeasurementReport function is extended to process A2 /
A3 measurement events. helper functions are written to fetch neighbour
cell informations from sequence containers.
(get_neighbour_cell_information, get_neighbour_config)
- neighbour_config.conf file includes neighbour and measurement related parameters
Neighbour List:
- nr_cellid: the identity of existing cell who has neighbour
- neighbour_cell_configuration(list): includes the identity parameters
of the neighbour cell such:
- gNBID (incase of N2 Handover / to be identified from AMF)
- nr_cell_id (target gNB needs to consider)
- physical_cellId (needed for measurement reporting)
- absoluteFrequencySSB (needed for measurement reporting)
- subcarrierSpacing (needed for measurement reporting)
- plmn / tracking area code (incase of N2 Handover / needed for AMF
to identify / allow HO)
NR Measurement Configuration
- Periodical
- enable (default is 0, 1 enables the reporting)
- includeBeamMeasurements, maxNrOfRS_IndexesToReport (configurable
reporting parameters)
- A2
- enable (default is 0, 1 enables the reporting)
- threshold , timeToTrigger (configurable reporting parameters)
- A3
- cell_id (the nr_cellid of neighbour cell. So this A3 parameters
will be used for the neighbour
- [-1] means default. so it can be applied to any neighbour if
there is no specific config
- Neighbour specific A3 Threshold can be used or default can be
selected depending to the neighbour planning
- The neighbour-config.conf specifies, apply default A3 for
neighbours 3 and 4 | apply specific one for neighbour 2
- offset, hysteresis, timeToTrigger (configurable reporting parameters)
the neighbour_config.conf can be included in the gNB.conf file. Example
is given: gnb.sa.band78.106prb.rfsim.neighbour.conf
A sequence array container is used for neighbour cell configuration. RRC
structure has this container. A Measurement configuration structure is
defined. This structure has Periodical / A2 Event structures and also a
sequence container for A3 Event List.
These structures are filled during the initialization. While F1 Setup
Response is coming from DU to CU, the intra frequency / inter frequency
neighbour decision is given for the existing cell. Also new neighbours
could be added here if needed.
It might be desirable to run the UE without superuser rights. More
concretely, it might run without NET_ADMIN. In this case, various
corresponding operations on the TUN socket fd might fail. In this
commit,
- improve error reports to make them more clear
- do not automatically exit(1), but return from the function to ensure
continuity of the softmodem
The RTT for GEO satellites is more than 500 ms.
And as the TA update interval must be greater than the RTT, we increase it to 1 second instead of 100 ms.
Should also do no harm for terrestrial networks.
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 in the gNB conf file, in the section `servingCellConfigCommon`
There is already a command line option called 'ue-scan-carrier' which
seemed to blindly look for SSB by changing the center frequency by
+/-100Hz if the previous attempt failed. This is probably copied from
LTE and is not suitable for NR. This commit uses this option to either
1. Perform initial sync on one GSCN if the SSB position if known
2. Or scan the all GSCN (if the SSB postion is unknown)
Also, the following is done for re-synchronization
1. Scan all GSCN when UE comes back from IDLE state
2. Scan one GSCN when UE does re-estabishment
Removed dependency of lte-softmodem.h in nr-softmodem.c.
CONFIG_HLP_UESCAN is declared also in lte-softmodem.h.
Till this commit, the UE gets the position of SSB in frequency from
command line and does the syncronization by locating the SSB in time. It
does this by generating a PSS time signal during initialization with the
SSB offset given via command line. Then PSS detection is done by
correlation.
In this commit, the UE computes a list of GSCN in the current NR band
that falls within the current bandwidth for the set center frequency.
For each GSCN in the list, the UE starts a thread and performs the
following:
1. Generate PSS time signal with SSB offset for current GSCN.
2. Detect PSS, SSS and decode PBCH (this step remains the same).
After all threads finishes, the results are collected.
For now, only the first detected PBCH is used to proceed further. So
this PBCH is indicated to MAC and UE exits initial sync.
Future work: The cell search can be standalone feature where the UE
could scan for SSB in the entire NR band. This would require changing
radio's frequency on the fly as the UE's bandwidth would not cover an
entire NR band. The cell detection can futher be imporved by looking
for SIB1 for each decoded PBCH.
38.321 6.1.3.1 says: "The size of the RLC headers and MAC subheaders are
not considered in the buffer size computation" [for BSR]. However, prior
to this commit, we take the size signaled of the BSR and schedule the UE
with that amount of data, making it impossible for the UE to transmit
all its data at once (because it is the size signaled + headers).
In this commit, over-estimate the buffer status size. As we cannot know
the exact number and size of headers, we simply use "BSR size + n", as
done in function overestim_bsr_index().
Robert Schmidt