fix for #1934
This fixes a race condition between Stack thread and DL
PDU processing that lead to updates of the RLC buffer that
are undetected by the BSR routine.
What happens is that in a UL SCH PDU all outstanding data is transmitted
and and a LBSR with all zero buffers is sent.
14:39:47.327301 [MAC ] [D] [ 3793] BSR: LCID=3 old_buffer=59
14:39:47.330600 [MAC ] [I] [ 3793] UL LCID=3 len=58 LBSR: b=0 0 0 0
Note that "old_buffer" isn't set to zero here.
At the same time (same TTI), the MAC PDU processing thread handles DL-SCH PDUs
that may generate new UL PDUs:
14:39:47.330749 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=1)
14:39:47.330762 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=2)
14:39:47.330775 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=3)
..
Those PDUs are "new data" since the previous buffer state was zero.
Here is the race now between the threads, at the end of the bsr::step() function
old_buffer of each LCG is updated with the previous new_buffer, so
the buffer state of LCG=2 is now 59.
Now MAC starts the next TTI:
14:39:47.331910 [MAC ] [D] [ 3794] Running MAC tti=3794
14:39:47.331928 [MAC ] [D] [ 3794] Update Bj: lcid=0, Bj=0
14:39:47.331934 [MAC ] [D] [ 3794] Update Bj: lcid=1, Bj=0
14:39:47.331938 [MAC ] [D] [ 3794] Update Bj: lcid=2, Bj=0
14:39:47.331941 [MAC ] [D] [ 3794] Update Bj: lcid=3, Bj=-1752
14:39:47.331951 [MAC ] [D] [ 3794] BSR: LCID=0 update new buffer=0
14:39:47.331960 [MAC ] [D] [ 3794] BSR: LCID=1 update new buffer=0
14:39:47.331964 [MAC ] [D] [ 3794] BSR: LCID=2 update new buffer=0
14:39:47.331971 [MAC ] [D] [ 3794] BSR: LCID=3 update new buffer=335
14:39:47.331976 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(0)=0
14:39:47.331980 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(1)=0
14:39:47.331984 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(2)=59
14:39:47.331988 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(3)=0
14:39:47.331993 [MAC ] [D] [ 3794] BSR: LCID=0 old_buffer=0
14:39:47.332000 [MAC ] [D] [ 3794] BSR: LCID=1 old_buffer=0
14:39:47.332003 [MAC ] [D] [ 3794] BSR: LCID=2 old_buffer=0
14:39:47.332007 [MAC ] [D] [ 3794] BSR: LCID=3 old_buffer=335
And since the buffer state of LCG=2 isn't zero, the new data for LCID=3 of that LCG is considered.
So effectivly, the BSR missed the "empty" buffer state for a fraction of time and doesn't
consider the outgoing data generated in the same TTI as new. It therefore
doesn't transmit a BSR.
in which a BSR wasn't
when releasing PUCCH/SRS (see 5.3.13 in 36.331) we need to reset the SR config as well.
In our case, SR is handled by MAC so we need to (re-)configure MAC, not all of
MAC though, just SR.
* Make PHY non-blocking and fefactor HO procedure
* makes entire PHY non-blocking through command interface
* adds dedicated queue for cell_search/cell_select commands
* refactor HO procedure to run faster, in one stack cycle. Looks closer to the specs
* force ue to always apply SIB2 configuration during reestablishment
* Run update_measurements in all workers
Co-authored-by: Ismael Gomez <ismagom@gmail.com>
we fix a number of very related issues for HO/reestablishment
in the success/error case:
* this patch removes the hard-coded check that intra-cell HO aren't
allowed. There are cases where eNBs use this method to update
the security context.
* the patch also fixes an issue after failed HO where the security context
of the source eNB should be used for the reestablishment.
* update security keys according to specs when mobilitycontrol
indicated change of key
the filter alpha was initialized to zero by default which causes an
issue because the first measurement for a cell can't be updated,
because the filtering function will always return the current value.
According to 36.331 Sec 5.5.3.2 Note 2, a k-value of 0 should turn
off filtering, which should be used as the default value until
an update is received from the network.
this patch fixes the UL BSR as per TS 36.321, it includes following
main changes:
* report UL buffer state to reflect the UEs transmit buffer after
the MAC UL PDU containing the BSR has been built.
In other words, if the UE, for example, can transmit all outstanding
data in an UL grant, it will not report any pending data to transmit.
* refactor MUX routines and subheader space calculation
Andre Puschmann
Francisco Paisana
Pedro Alvarez
Xavier Arteaga
Sylvain Munaut
Ismael Gomez