Energy saving techniques for a UE in 5G to conserve ue's battery power

  I will give you a brief introduction upon rrc State's DRX and cdrx when there is a data transfer between base station and UE then both SRB and drb are active and this state is called rrc connected state similarly if there is no data transfer between UE and base station for a long duration then base station can release both drb and SRB connections and this state is called rrc idle state in rrc idle State UE can sleep and doesn't listen to any signal from base station when the UE wants to transmit or receive data the base station has to First change UE State back to a RC connected to reduce the latency 5G introduced an intermediate State called rrc inactive in rrc in active State ue's SRB is connected but drb is released Rand can manage the switching between the RC and active and rrc connected State much faster without involving cornet work [Music] assume a scenario where yui is in RC idle or rrc in active State and the base station wants to transmit a downlink data before transmitting downlink data base station has to change UE state to rrc Connected state by sending a special signal called paging signal but UE is unreachable during sleep time so you we cannot listen to paging signal therefore UE has to wake up periodically and monitor the paging signal to be more precise UE has to wake up periodically and stay awake for a small duration and go back to sleep again and then repeat this cycle again this periodic wake-up and sleep cycle is called discontinuous reception or DRX these wake up and sleep states are also called DRX active and DRX in active States respectively base station and UE must be synchronized to ensure that the base station sends paging signal only when you ease awake different ue's will have different offsets for the wake up and sleep cycles so that base station gets enough resources to allocate paging signal for all ue's these offsets and DRX cycle durations are determined by core Network and conveyed to you using a special parameter inside the RC configuration next assume a second scenario where yui is in RC idle or rrc in active State and UE wants to transmit and a plank data before transmitting a plinkdator UE has to change its state back to our RC connected state for this purpose UE sends a scheduling request to base station and base station invokes the procedure to change UE state to our RC connected state note that UE has to send scheduling requests only during the time slots configured for it by base station thy similar sleep wake up cycle is also applied in rrc Connected State as well which is called connected mode discontinuous reception or cdrx if cdrx cycle periodicity is high then we can conserve more of ue's battery but the latency would also become High because base station has to wait longer for UE to wake up before it can transmit downlink data on the other hand if cdrx cycle periodicity is low then the latency is low but the ue's energy consumption would be high therefore cdrx periodicity has to be set properly to improve latency without compromising the Energy Efficiency DRX short Cycles are introduced just after UE enters into sleep this is because there is high probability for data transfer just after the UE goes into the sleep so UE wakes up and sleeps in a short cycle for some duration then switches to Long cycle if there is still no data transfer the corresponding wake up time duration is called DRX underation timer and the periodicity is called DRX short cycle the number of short Cycles is called DRX short cycle timer which is two in this example correspondingly the long cycle has a DRX cycle periodicity of DRX long cycle note that all these parameters are rrc parameters sent from base station to UE [Music] to reduce latency again without compromising Energy Efficiency A New Concept called event-based wake-up period extension is introduced the idea is that if a specific event happens when the UE is awake then the UE extends its wake-up period for an additional time duration for example if UE receives a pdcch with a downlink data scheduling then the UE extends its wake up period for a duration of DRX and activity timer during this period if UE receives anadditional pdcch with another downlink scheduling then you restarts the timer and stays awake until the timer expires another event is when UE receives an errored packet in downlink in that case UE sends a knack and waits for re-transmission from base station for a duration of DRX har car DD timer DL then wakes up for a Time duration of DRX re-transmission timer DL the buffer time period DRX har car DT timer DL is for base station to process Knack and schedule a re-transmission in downlink another event is when a UE completes anda plank transmission after transmitting a plinkdator UE waits for a duration of DRX har car DT timer ul and then stays awake for a duration of DRX re-transmission timer UL this is because in case base station receives the Uplink packet in error then UE has to be awake to listen to the re-transmission request by base station these events can be co-occurring also for example while waiting for the request for re-transmission UE may receive a downlink data in that case UE starts DRX in activity timer and extends its wake up duration until all

timers expire in summary UE stays awake until all its timers expire I hope this video helps you to get a basic understanding of rrc States DRX and cdrx I've left out a lot of details here to keep things simple you can read more about it in the references in the description below thank you for watching foreign