Implement the #define variables required for synchronization: These
variables include offset and payload size values that vary from the Uu
interface, in relation to the PSS, SSS and PBCH elements. We also
introduce the new sl_mode command line flag, which is used to switch
between the Uu interface and SL interface. This will allow us to modify
exisitng PSS and SSS functions, without copying complete 5G functions
and only changing a few lines to support sidelink mode.
Fixing formatting for softmodem-common.h
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.
Different threads (e.g., RRC, DU tasks) might access the scheduler at
the same time as the thread that drivers the scheduler itself
(ru_thread). To avoid data races, introduce this mutex.
Most functions of the scheduler are only used internally and have been
marked static in the previous commit. The remaining ones, in this
commit, either lock the scheduler mutex sched_lock, or a comment has
been added of the assumption of how such function is to be locked (e.g.,
if it might be called from different places, or if it is called by a
function that already locks the scheduler).
fill_default_secondaryCellGroup() is moved to nr_rrc_config.c.
Furthermore, the signature is changes to return the NR_CellGroupConfig
from the functions, instead of filling a pre-allocated structure (which
is, in all cases, allocated just before calling
fill_default_secondaryCellGroup().
There is a problem with this function: the function also fills the
ServingCellConfig (a parameter to this function). This behavior has not
been changed.
This commit fixes a bug caused by global variables in the gNB_MAC_INST
structure used to transfer MAC scheduler's results to the PHY layer.
When using several threads in the PHY layer, it may happen that the
MAC scheduler is called a second time by the second PHY thread for the
next slot before the content of the global variables in the gNB_MAC_INST
structure used to store the result of the MAC scheduler for the current
slot have been consumed by the first thread, leading to unpredictable
results (all of them certainly wrong).
The solution is to introduce a small memory management module for the
interface between the PHY threads and the MAC scheduler. The MAC
scheduler now fills the data structures passed to it, and not a
global variable anymore. The PHY layer manages the structures and
ensures that no data is overwritten before being fully consumed by
the various threads of the PHY layer.
Some care has to be taken because several PHY threads will access the
same structures at the same time for a given slot (in read mode, so
it's okay). A mechanism of reference counting has thus been introduced.
Only one CC is supported. This restriction should not be too hard
to remove if/when needed. (The code before this commit does not seem
to work for more than one CC anyway.)
Robert Schmidt