Method and device for random access in small data transmissions
The present disclosure provides a method and device used in a communication node for wireless communications. A communication node determines that first data is transmitted in a first state, selects a first step-size, and transmits a first signal according to first target power; updates a first counter; when the first counter is not greater than a first threshold, and determines that a second counter is updated, transmits a third signal according to second target power; monitors a second signal in a first time window; the first state comprises RRC_INACTIVE State; the first data comprises a small data packet; the first signal, the second signal and the third signal are used for random access procedure; the first counter is used to count a number of transmission(s) of a preamble sequence; the second counter is used to count a number of time(s) the first step-size is increased.
1 . A user equipment (UE), comprising:
a transceiver; and
a processor, wherein the transceiver and the processor are configured to:
perform a small data transmission (SDT) in a radio resource control (RRC) inactive (RRC_INACTIVE) state,
receive control information,
select a first step-size based on a sum of a first offset and a second step-size indicated by the control information,
on a condition that a first random access signal including a preamble is transmitted according to a first power, update a first counter of a number of transmissions of the preamble,
on a condition that the first counter is not greater than a first threshold and a second counter is updated, transmit a third random access signal including a preamble according to a second power, wherein the second counter is counter of a number of times the first step-size is increased,
on a condition that the first counter is greater than the first threshold, enter an RRC idle (RRC_IDLE) state, and
monitor a second random access signal in a first time window of slots, wherein a difference between the second power and the first power is associated with the first step-size.
2 . The UE according to claim 1 , wherein whether the SDT is transmitted in the RRC_INACTIVE state is a determined according to a first reference signal receive quality (RSRP) and a size of the SDT.
3 . The UE according to claim 2 , wherein the transceiver and the processor are further configured to:
on a condition that the first RSRP is not less than a first RSRP threshold and a size of the SDT is not greater than a first size threshold, perform the SDT in the RRC_INACTIVE state.
4 . The UE according to claim 1 , wherein the first counter is a PREAMBLE_TRANSMISSION_COUNTER, and wherein updating the first counter includes increasing the first counter by 1, and wherein the first threshold is preambleTransMax and is configured via an RRC message.
5 . The UE according to claim 1 , wherein the second counter is a PREAMBLE_POWER_RAMPING_COUNTER, and wherein updating the second counter includes increasing the second counter by 1, and wherein determining whether to update the second counter includes: determine whether a condition for updating the second counter is satisfied, and wherein the condition of updating the second counter including at least one of a value of the first counter being greater than 1, or not receiving a notification of suspending the first counter, or, not receiving a listen-before-talk (LBT) failure indication for a first signal, or a synchronization signal block (SSB) or a channel-state information reference signal (CSI-RS) not being changed.
6 . The UE according to claim 1 , wherein the first power is associated with a first initial power and first power difference value, and wherein the second power is associated with the first initial power, the first power difference value and a first power increment, and wherein a first difference value includes a DELTA PREAMBLE, and the first power difference value is associated with a format of a preamble, and wherein the first power increment is (the second counter-1)×the first step-size, and wherein the first initial power includes msgA-PreambleReceivedTargetPower or preambleReceivedTargetPower.
7 . The UE according to claim 1 , wherein the transceiver and the processor are further configured to;
receive control information indicating the first step-size.
8 . The UE according to claim 1 , wherein the transceiver and the processor are further configured to:
transmit first data and second data, and
determine that a transmission of the first data is successful and a transmission of the second data failed, wherein the SDT includes the first data and the second data, and wherein a transmission of the first data being successful and a transmission of the second data having failed are used to determine that the difference between the second power and the first power is associated related to the first step-size.
9 . The UE according to claim 1 , wherein a size of the first step-size is unrelated to the SDT in the RRC_INACTIVE state and is associated with a 2-step random access procedure or a 4-step random access procedure.
10 . The UE according to claim 9 , wherein the first signal, second signal and third random access signals are used for the 2-step random access procedure.
11 . The UE according to claim 9 , wherein the first, second signal and third random access signals are used for the 4-step random access procedure.
12 . The UE according to claim 9 , wherein when the first random access signal is used for the 2-step random access procedure, and the third random access signal is used for the 4-step random access procedure, the difference between the second power and the first power is associated with a second offset, a difference between a first sub-step-size and a second sub-step-size and the first counter are used to determine the second offset, and the first sub-step-size and the second sub-step-size are respectively used to determine a power of the 2-step random access procedure and the 4-step random access procedure.
13 . The UE according to claim 9 , wherein the control information is used to determine a first candidate preamble sub-group, the first candidate preamble sub-group is used to indicate the SDT in the RRC_INACTIVE state, the first candidate preamble sub-group is one of a plurality of first-type preamble sub-groups, and a number of the plurality of first-type preamble sub-groups is associated with a characteristic of a preamble used for random access, and wherein the first random access signal includes a preamble in the first candidate preamble sub-group, and wherein the control information include a RACH-ConfigCommon IE or a RACH-ConfigCommonTwoStepRA IE.
14 . The UE according to claim 13 , wherein:
on a condition that the SDT is made in the RRC_INACTIVE state and the random access type is 2-step random access, a preamble used for a random access procedure is in a first one of first-type preamble sub-groups,
on a condition that the SDT is made in the RRC_INACTIVE state and the random access type is 4-step random access, a preamble used for a random access procedure is a preamble in a second one of first-type preamble sub-groups,
on a condition that the SDT is not made in the RRC_INACTIVE state and the random access type is 2-step random access, a preamble used for a random access procedure is a preamble in a third one of first-type preamble sub-groups,
on a condition that the SDT is not made in the RRC_INACTIVE state and the random access type is 4-step random access, a preamble used for a random access procedure is a preamble in a fourth one of first-type preamble sequence sub-groups, and
the first candidate preamble sub-group includes the first one of first-type preamble sequence sub-groups, or the first candidate preamble sub-group includes the second one of first-type preamble sub-groups.
15 . The UE according to claim 1 , wherein the control information is used to determine a first candidate preamble sub-group, the first candidate preamble sub-group is used to indicate the SDT in the RRC_INACTIVE state, the first candidate preamble sub-group is one of a plurality of first-type preamble sub-groups, and a number of the plurality of first-type preamble sub-groups is associated with a characteristic of a preamble used for random access, and wherein the first random access signal includes a preamble in the first candidate preamble sub-group, and wherein the control information include a RACH-ConfigCommon information element (IE) or a RACH-ConfigCommonTwoStepRA IE.
16 . The UE according to claim 15 , wherein the number of the plurality of first-type preamble sub-groups is four, and four first-type preamble sequence sub-groups are based on whether the SDT is in the RRC_INACTIVE and a random access type used for the SDT.
17 . The UE according to claim 1 , wherein the first step-size is used to determine a power-ramping factor, and wherein the SDT is generated by a higher layer, and wherein the first random access signal is used to trigger the second random access signal.
18 . A method, comprising:
performing a small data transmission (SDT) in a radio resource control (RRC) inactive (RRC_INACTIVE) state;
receiving control information;
selecting a first step-size based on a sum of a first offset and a second step-size indicated by the control information;
on a condition that a first random access signal including a preamble is transmitted according to a first power, updating a first counter of a number of transmissions of the preamble;
on a condition that the first counter is not greater than a first threshold and a second counter is updated, transmitting a third random access signal including a preamble according to a second power, wherein the second counter is counter of a number of times the first step-size is increased;
on a condition that the first counter is greater than the first threshold, entering an RRC idle (RRC_IDLE) state; and
monitoring a second random access signal in a first time window of slots, wherein a difference between the second power and the first power is associated with the first step-size.