In TDD mode, CQI requests are not possible in special subframes (at
least for some TDD configurations, see 36.213 7.2.3 that says "a
DL subframe is valid if it does not contain a DwPTS field if the
length is less than 7680 Ts").
In the code, we simply disable CQI requests in special subframes,
no matter what the length of DwPTS.
A problem can arise if the DCI0 for a given UE are sent only in
those special subframes. In this case the UE will never report
CQI and the eNB will use low MCS for this UE, impacting performances.
Another, related, problem is when there are several UEs. There again
one UE might always get its DCI0 in special subframes and thus never
report CQI. There again, performance issues.
This commit is an attempt to improve the situation.
It does two things.
1 - tag the UE as schedulable in the function UE_is_to_be_scheduled
if the cqi_req_timer is expired
2 - use cqi_req_timer as a criterium when ordering UEs for UL scheduling
The value chosen for the expiration of the cqi_req_timer in
UE_is_to_be_scheduled is quite high (300) because as the code is
today we may overschedule the UE for short bursts until we receive
a CQI from the UE. [TODO: fix the code properly to avoid this behavior.]
Note: the fairRR scheduler has not been analyzed and this commit may
not fix anything in case the fairRR scheduler is used.
- size of PUCCH has been fixed to:
- 2 RBs for N_RB_UL = 25 (1 RB at top of resource grid, 1 RB at bottom)
- 4 RBs for N_RB_UL = 50
- 6 RBs for N_RB_UL = 100
this is arbitrary and will need some rework at some point.
This may be also wrong. PUCCH size actually depends on DL traffic
(if the ack/nack is not done in PUSCH) and scheduling request
configurations.
- add sched_frame %= 1024 at one needed place
- reserve RBs for retransmission
this was not done so new transmissions were scheduled in the same
RBs. Since the code works with the notion of 'first_rb' only, it
was decided to skip all RBs lower than those retransmitted. This
works but is not correct (imagine we have to retransmit RB 23, then
all RBs < 23 will not be used for new transmission). The work to
fix this properly is complex, a lot has to change, so let's do it
this simple way for now.
- sort_ue_ul was not correct
- add the function maxround_ul to use the correct 'round' (the one
from DL was used, which is totally wrong)
- be sure to use the correct frame/subframe to get the correct HARQ pid
- uncomment "Couldn't find RNTI for UE X" in UE_RNTI() and rb_alloc in
pre_processor_reset() as they only inflate the debug output with little
benefited
- "doing ue_schedule_spec" is now displayed for individual UEs (and individual
CCs)
- show messages when not scheduling UE in ue_schedule_spec() due to invalid
slice or if not in RRC_CONNECTED
- introduce structure in RC for slicing conf (UL/DL)
- move global variables regarding slice configuration into RC
- change ue_slice_membership(): consider UL/DL
- remove the unnecessary header files
- set default parameters: one slice
Raphael Defosseux