this patch refactors the SDU queuing and dropping policy of the RLC and PDCP layer.
the previous design had issues when packets have been generated at a higher
rate above the PDCP than they could be consumed below the RLC.
When the RLC SDU queues were full, we allowed two policies, one to block on the write
and the other to drop the SDU. Both options are not ideal because they either
lead to a blocking stack thread or to lost PDCP PDUs.
To avoid this, this patch makes the following changes:
* PDCP monitors RLC's SDU queue and drops packets on its north-bound SAP if queues are full
* a new method sdu_queue_is_full() has been added to the RLC interface for PDCP
* remove blocking write from pdcp and rlc write_sdu() interface
* all writes into queues need to be non-blocking
* if Tx queues are overflowing, SDUs are dropped above PDCP, not RLC
* log warning if RLC still needs to drop SDUs
* this case should be avoided with the monitoring mechanism
Avoid double buffering of SIBs in MAC as this would require one buffer for each CC.
Instead, use byte_buffer managed by RRC that contains packed SIBs to avoid
double memcpy for each SIB tx. Only use MAC provided buffer in error case.
Also avoid MAC calling RLC for each SIB and call RRC directly.
- move cell specific eNB params to cell list in rr.conf
- make sure DL EARFCN and DL freq can be used to manually overwrite a single cell config
- fix SIB packing and transmission for multi cell configs
- introduce cell list to MAC
- adapt default enb.conf.example and rr.conf.example
* first step towards moving MAC timers to stack. Mac is still using its own timers. srslte::timers class can be restructured.
* moved timers out of the UE MAC