Balancing latency reduction and user equipment power saving
Balancing latency reduction and user equipment power saving is provided. A method for balancing latency reduction and user equipment power saving may include receiving, from a network entity, an indication of a number of repetitions of an uplink channel and determine at least one duration of at least one timer based on at least the number of repetitions. The method may further transmit the uplink channel with the number of repetitions and starts the timer and determine, based on an expiration status of the at least one timer, a discontinuous reception state of the apparatus comprising a plurality of active and inactive states.
1 . An apparatus configured as a user equipment, comprising:
at least one processor; and
at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to:
receive, from a base station via downlink control information, an explicit indication of a number of repetitions for a physical uplink shared channel transmission scheduled for a hybrid automatic repeat request (HARQ) process;
determine that a last-transmission indicator for uplink repetitions is configured for the user equipment;
based on the indicated number of repetitions and the last-transmission indicator being configured, determine a value of a drx-HARQ-RTT-TimerUL by:
selecting one of a plurality of timer values pre-configured by the base station, wherein each timer value is uniquely associated with a respective number of uplink repetitions, and wherein the selected timer value is shorter for a larger number of repetitions and longer for a smaller number of repetitions;
transmit the physical uplink shared channel using the indicated number of repetitions;
start the drx-HARQ-RTT-TimerUL from a first symbol following a last repetition of the physical uplink shared channel;
refrain from monitoring a physical downlink control channel while the drx-HARQ-RTT-TimerUL is running;
upon expiration of the drx-HARQ-RTT-TimerUL, transition the apparatus from a discontinuous reception inactive state to a discontinuous reception active state; and
monitor the physical downlink control channel during the discontinuous reception active state for a retransmission grant corresponding to the HARQ process.
2 . The apparatus of claim 1 , wherein the plurality of timer values pre-configured by the base station is provided to the apparatus via radio resource control (RRC) signaling as a table that maps each supported number of uplink repetitions to a corresponding drx-HARQ-RTT-TimerUL value.
3 . The apparatus of claim 2 , wherein the table includes entries for at least three different numbers of uplink repetitions, and wherein the drx-HARQ-RTT-TimerUL values decrease monotonically as the number of uplink repetitions increases.
4 . The apparatus of claim 3 , wherein the apparatus is further caused to determine the drx-HARQ-RTT-TimerUL by applying an offset to a default drx-HARQ-RTT-TimerUL value configured by the base station, the offset being selected based on the indicated number of uplink repetitions.
5 . The apparatus of claim 4 , wherein the offset is subtracted from the default drx-HARQ-RTT-TimerUL value when the indicated number of uplink repetitions exceeds a predefined repetition threshold.
6 . The apparatus of claim 5 , wherein the apparatus is further caused to determine the drx-HARQ-RTT-TimerUL by scaling a default drx-HARQ-RTT-TimerUL value using a scaling factor associated with the indicated number of uplink repetitions.
7 . The apparatus of claim 6 , wherein the scaling factor is inversely proportional to the indicated number of uplink repetitions.
8 . The apparatus of claim 7 , wherein the indicated number of uplink repetitions is counted based on available transmission slots, and wherein the determined drx-HARQ-RTT-TimerUL is selected based on the counting of available transmission slots.
9 . The apparatus of claim 8 , wherein the apparatus is further caused to:
determine a drx-RetransmissionTimerUL based on the indicated number of uplink repetitions; and
monitor the physical downlink control channel for the retransmission grant during a duration defined by the drx-RetransmissionTimerUL.
10 . The apparatus of claim 9 , wherein the drx-RetransmissionTimerUL is longer for a higher number of uplink repetitions than for a lower number of uplink repetitions.
11 . A method performed by an apparatus, the method comprising:
receiving, from a base station via downlink control information, an explicit indication of a number of repetitions for a physical uplink shared channel transmission scheduled for a hybrid automatic repeat request (HARQ) process;
determining that a last-transmission indicator for uplink repetitions is configured for the user equipment;
based on the indicated number of repetitions and the last-transmission indicator being configured, determining a value of a drx-HARQ-RTT-TimerUL by:
selecting one of a plurality of timer values pre-configured by the base station, wherein each timer value is uniquely associated with a respective number of uplink repetitions, and wherein the selected timer value is shorter for a larger number of repetitions and longer for a smaller number of repetitions;
transmitting the physical uplink shared channel using the indicated number of repetitions;
starting the drx-HARQ-RTT-TimerUL from a first symbol following a last repetition of the physical uplink shared channel;
refraining from monitoring a physical downlink control channel while the drx-HARQ-RTT-TimerUL is running;
upon expiration of the drx-HARQ-RTT-TimerUL, transitioning the apparatus from a discontinuous reception inactive state to a discontinuous reception active state; and
monitoring the physical downlink control channel during the discontinuous reception active state for a retransmission grant corresponding to the HARQ process.
12 . The apparatus of claim 11 , wherein the plurality of timer values pre-configured by the base station is provided to the apparatus via radio resource control (RRC) signaling as a table that maps each supported number of uplink repetitions to a corresponding drx-HARQ-RTT-TimerUL value.
13 . The method of claim 12 , wherein the table includes entries for at least three different numbers of uplink repetitions, and wherein the drx-HARQ-RTT-TimerUL values decrease monotonically as the number of uplink repetitions increases.
14 . The method of claim 13 , further comprising determining the drx-HARQ-RTT-TimerUL by applying an offset to a default drx-HARQ-RTT-TimerUL value configured by the base station, the offset being selected based on the indicated number of uplink repetitions.
15 . The method of claim 14 , wherein the offset is subtracted from the default drx-HARQ-RTT-TimerUL value when the indicated number of uplink repetitions exceeds a predefined repetition threshold.
16 . The method of claim 15 , further comprising determining the drx-HARQ-RTT-TimerUL by scaling a default drx-HARQ-RTT-TimerUL value using a scaling factor associated with the indicated number of uplink repetitions.
17 . The method of claim 16 , wherein the scaling factor is inversely proportional to the indicated number of uplink repetitions.
18 . The method of claim 17 , wherein the indicated number of uplink repetitions is counted based on available transmission slots, and wherein the determined drx-HARQ-RTT-TimerUL is selected based on the counting of available transmission slots.
19 . The method of claim 18 , further comprising:
determining a drx-RetransmissionTimerUL based on the indicated number of uplink repetitions; and
monitoring the physical downlink control channel for the retransmission grant during a duration defined by the drx-RetransmissionTimerUL.
20 . The method of claim 19 , wherein the drx-RetransmissionTimerUL is longer for a higher number of uplink repetitions than for a lower number of uplink repetitions.