About RRC Deep Sleep Optimization timers

Question :- What are RRC Deep sleep optimization timers available in the AMSS code and their use?



Answer :- UE uses Deep Sleep optimization timers RRCTMR_FREQ_SCAN_TIMER and RRCTMR_DEEP_SLEEP_NO_SVC_TIMER, when it enters deep sleep as part of OOS(Out of Service).



Detail:- RRCTMR_FREQ_SCAN_TIMER : If UE is in deep sleep and performed RRC_MAX_FULL_SCANS_IN_DEEP_SLEEP (i.e 3 as per the current code) number of full frequency scans on all supported bands and it didn't find any cell, it starts full scan timer ( For 30sec as per the current code) during which it only performs ACQ-DB scan and full scan only on bands which are not present in the ACQ-DB. This optimization is not followed if ACQ-DB is empty.


RRC_MAX_FULL_SCANS_IN_DEEP_SLEEP (3 as per the current code) :- This counter defines the max number of attempts for which full frequency scan should be done after UE enters deep sleep. Full Scan timer is started after these number of full scan attempts are completed.



RRCTMR_DEEP_SLEEP_NO_SVC_TIMER (10s as per the current code) :- If UE is in deep sleep and available plmn list is empty during service search, then UE starts a timer RRCTMR_DEEP_SLEEP_NO_SVC_TIMER (i.e no_svc_timer, 10sec), so that if RRC receives a RRC_SERVICE_REQ from NAS before this timer expires then return immediately RRC_SERVICE_CNF with no service.