Method and apparatus for two-step random access procedure

Abstract

It is possible to determine (1110) the first transmission power for the first PRACH preamble in a two-step random access procedure based on the first set of power control parameters. It is possible to transmit (1120) the first PRACH preamble in the two-step random access procedure based on the first transmission power. It is possible to make a determination (1130) to switch from the two-step random access procedure to a four-step random access procedure. It is possible to determine (1140) the second transmission power based on the first set of power control parameters and a second set of power control parameters for the subsequent second PRACH preamble transmission in the four-step random access procedure. It is possible to transmit (1150) the subsequent second PRACH preamble in the four-step random access procedure based on the second transmission power.

Description

Technical Field

[0001] 1. Field

[0002] The present disclosure relates to methods and apparatuses for a two-step random access procedure. Background Art

[0003] 2. Introduction

[0004] Currently, wireless communication devices such as user equipment (UE) communicate with other communication devices using wireless signals. The UE uses a random access procedure to synchronize with a wireless network so that the UE can transmit and receive data on the wireless network.

[0005] The two-step random access procedure includes a MsgA transmission from the UE and a MsgB reception by the UE. The two-step random access procedure can reduce the latency associated with connection establishment, serving cell change (e.g., handover), and / or uplink synchronization, and potentially has benefits for channel access in unlicensed spectrum when compared to a four-step random access procedure. MsgA includes a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH) with data that can also be included in Msg3 of the four-step random access procedure. MsgB includes at least one random access response (RAR) message.

[0006] The four-step random access procedure includes transmitting a random access preamble (Msg1) in the PRACH, receiving an RAR message (Msg2) with a physical downlink control channel (PDCCH) / physical downlink shared channel (PDSCH), and transmitting a PUSCH scheduled by the RAR uplink (UL) grant and receiving a PDSCH for contention resolution when applicable. Brief Description of the Drawings

[0007] To describe the manner in which the advantages and features of the present disclosure can be obtained, a description of the present disclosure is presented by reference to specific embodiments of the present disclosure illustrated in the drawings. These drawings only depict example embodiments of the present disclosure and should not be considered as limiting its scope. For clarity, the drawings may have been simplified and are not necessarily drawn to scale.

[0008] Figure 1 is an example block diagram of a system according to a possible embodiment;

[0009] Figure 2 is an example illustration of a MAC sub-header with a backoff indicator (BI) of an example media access control (MAC) sub-protocol data unit (PDU) for MsgB according to a possible embodiment;

[0010] Figure 3An example illustration of a MAC sub - header of an example MAC sub - PDU for MsgB with a Random Access Preamble Identifier (RAPID) for fallback RAR;

[0011] Figure 4 An example illustration of a MAC sub - header of an example MAC sub - PDU for MsgB, the MAC sub - header having a PDSCH - to - Hybrid Automatic Repeat reQuest (HARQ) - Positive Acknowledgment (ACK) Feedback Timing Offset (PHFTO) / Physical Uplink Control Channel (PUCCH) Resource Indicator (PRI) for successful RAR;

[0012] Figure 5 An example illustration of a MAC successful RAR of an example MAC sub - PDU for MsgB;

[0013] Figure 6 An example illustration of a MAC sub - header of an example MAC sub - PDU for MsgB having a BI;

[0014] Figure 7 An example illustration of a MAC sub - header of an example MAC sub - PDU for MsgB having a RAPID for both fallback RAR and successful RAR;

[0015] Figure 8 An example illustration of a MAC successful RAR of an example MAC sub - PDU for MsgB;

[0016] Figure 9 An example flowchart illustrating the operation of a device according to a possible embodiment;

[0017] Figure 10 An example flowchart illustrating the operation of a device according to a possible embodiment;

[0018] Figure 11 An example flowchart illustrating the operation of a device according to a possible embodiment;

[0019] Figure 12 An example flowchart illustrating the operation of a device according to a possible embodiment;

[0020] Figure 13 An example flowchart illustrating the operation of a device according to a possible embodiment;

[0021] Figure 14 An example flowchart illustrating the operation of a device according to a possible embodiment; and

[0022] Figure 15It is an example block diagram of a device according to a possible embodiment. Detailed Description

[0023] Embodiments provide a method and apparatus for a two-step random access procedure.

[0024] According to a possible embodiment, a command can be received from a network entity. The command can initiate a random access procedure and can include information on the type of random access procedure. The type of random access procedure can be selected from a two-step random access procedure and a four-step random access procedure. When the type of random access procedure is a two-step random access procedure, a MsgA transmission can be transmitted in response to receiving the command.

[0025] According to a possible embodiment, a first transmission power for a first PRACH preamble can be determined in a two-step random access procedure based on a first set of power control parameters. The first PRACH preamble can be transmitted in the two-step random access procedure based on the first transmission power. A determination can be made to switch from the two-step random access procedure to a four-step random access procedure. A second transmission power can be determined based on the first set of power control parameters and a second set of power control parameters for a subsequent second PRACH preamble transmission in the four-step random access procedure. The subsequent second PRACH preamble can be transmitted in the four-step random access procedure based on the second transmission power.

[0026] According to a possible embodiment, at least one common PUCCH resource set configuration for a two-step random access procedure can be received. At least one common PUCCH resource set can be determined based on the at least one common PUCCH resource set configuration. A PRACH and a corresponding MsgA PUSCH can be transmitted. A MsgB PDSCH can be received in response to the transmitted PRACH and MsgA PUSCH. The received MsgB PDSCH can be decoded. A successful RAR destined for the UE can be identified from the decoded MsgB PDSCH. A common PUCCH resource set in the at least one common PUCCH resource set and a PUCCH resource in the common PUCCH resource set can be determined based on the successful RAR. At least HARQ-ACK feedback information for the MsgB PDSCH can be transmitted on the PUCCH resource.

[0027] Embodiments can provide a method for: MsgB structure and transmission / reception of MsgB, HARQ-ACK feedback for MsgB successful RAR, two-step random access procedure initiated by a network command, search space configuration of MsgB, and / or power control when the UE falls back from a two-step random access procedure to a four-step random access operation.

[0028] Embodiments can provide details regarding PUCCH resources / HARQ-ACK feedback timing indication for MsgB HARQ-ACK feedback. Multiple common PUCCH resource set configurations for 2-step RACH can be received. A common PUCCH resource set can be selected depending on whether CSI reporting is included and depending on which type of CSI reporting is included in the PUCCH resources for MsgB HARQ-ACK feedback. A UE-specific PDSCH to HARQ-ACK feedback timing offset can be applied to determine the HARQ-ACK feedback timing.

[0029] Embodiments can provide enabling / disabling of support for HARQ combining for UEs for MsgB.

[0030] Embodiments can provide a RACH initiated by a network command (e.g., handover command or PDCCH instruction). An indication of the type of random access procedure (i.e., 2-step RACH vs. 4-step RACH) can be received. A CSI request can be received in the network command along with the indication of the 2-step random access procedure. If the UE is instructed to perform a 2-step random access procedure during a SpCell change, the UE can use the indicated new UE identity (“newUE-Identity”) to transmit the UE identity in the MsgA PUSCH (e.g., for contention-based 2-step RACH) and monitor the PDCCH for receiving MsgB in response to the MsgA PUSCH transmission (e.g., monitor DCI format with CRC scrambled with the new UE identity).

[0031] Embodiments can provide details regarding PDCCH monitoring for MsgB. If the UE has a C-RNTI, the UE can be configured with two PDCCH search space sets (MsgB-SearchSpaceCommon, MsgB-SearchSpace) for MsgB PDCCH. The UE can be configured with two different MsgB windows. The first MsgB window can be associated with the first PDCCH search space set (e.g., CSS). The second MsgB window can be associated with the second PDCCH search space set (e.g., USS). For example, the first MsgB window can be configured with a longer duration than the second MsgB window to accommodate multiple MsgB PDSCHs with different MAC PDUs within the first MsgB window. In the case of successful completion of a 2-step RACH, if no other UE-specific search space set is provided to the UE, the UE can monitor PDCCH candidates in the second PDCCH search space set provided by MsgB-SearchSpace for a fallback / compact DCI format with CRC scrambled by the C-RNTI.

[0032] Figure 1 FIG. 1 is an example block diagram of a system 100 according to a possible embodiment. The system 100 can include a UE 110, at least one network entity 120 and 125, and a network 130. The UE 110 can be a wireless wide area network device, a user equipment, a wireless terminal, a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a personal digital assistant, a smart watch, a personal computer, a tablet computer, a laptop computer, a selective call receiver, an Internet of Things (IoT) device, or any other user equipment capable of transmitting and receiving communication signals over a wireless network. The at least one network entity 120 and 125 can be a wireless wide area network base station, can be a Node B, can be an enhanced Node B (eNB), can be a New Radio (NR) Node B (gNB) (such as a fifth generation (5G) Node B), can be an unlicensed network base station, can be an access point, can be a base station controller, can be a network controller, can be a Transmission and Reception Point (TRP), can be a network entity of a different type from other network entities, and / or can be any other network entity capable of providing wireless access between the UE and the network.

[0033] The network 130 can include any type of network capable of transmitting and receiving wireless communication signals. For example, the network 130 can include a wireless communication network, a cellular phone network, a Time Division Multiple Access (TDMA)-based network, a Code Division Multiple Access (CDMA)-based network, an Orthogonal Frequency Division Multiple Access (OFDMA)-based network, a Long Term Evolution (LTE) network, an NR network, a 3rd Generation Partnership Project (3GPP)-based network, a 5G network, a satellite communication network, a high altitude platform network, the Internet, and / or other communication networks.

[0034] In operation, the UE 110 can communicate with the network 130 via at least one network entity 120. For example, the UE 110 can transmit and receive control signals on a control channel and transmit and receive user data signals on a data channel.

[0035] The following provides the RAN2 agreement related to the two-step random access procedure:

[0036] Agreement based on 3GPP document R2-1908481:

[0037] From the perspective of RAN2, the two-step Random Access Channel (RACH) selection can be based on an indication to all UEs via a System Information Block (SIB), or a dedicated configuration in the RRC_CONNECTED / INACTIVE / IDLE state. If radio quality is used for two-step RACH selection, it is for Further Study (FFS).

[0038] From the perspective of RAN2, for MsgA retransmission (i.e., preamble and PUSCH), we assume that the UE retries the two-step RACH.

[0039] Whether the UE can fallback to the four-step RACH after a certain time is FFS. Ask RAN1 whether the preamble transmission performance for the two-step RACH and the four-step RACH is the same.

[0040] For MsgA with a cell-radio network temporary identifier (C-RNTI), the UE shall monitor the PDCCH addressed to the C-RNTI for a successful response and the MsgB-RNTI (e.g., random access-radio network temporary identifier (RA-RNTI) or new RNTI).

[0041] Contention resolution:

[0042] If a PDU PDCCH addressed to the C-RNTI containing a 12-bit timing advance (TA) command (i.e., the C-RNTI included in MsgA) is received, the UE shall consider the contention resolution to be successful, and if the UE is already synchronized, the UE shall stop receiving MsgB or use the UL grant to stop receiving MsgB.

[0043] If the corresponding fallback RAR is detected, the UE shall stop monitoring the PDCCH addressed to the corresponding C-RNTI for a successful response and handle the fallback operation accordingly.

[0044] If neither the corresponding fallback RAR nor the PDCCH addressed to the C-RNTI is detected within the response window, the UE shall consider the MsgA attempt to have failed, and if a fallback indicator is received in MsgB, the UE shall perform the fallback operation based on the fallback indicator.

[0045] If a new media access control (MAC) control element (CE) with a 12-bit timing advance command should be introduced, it is FFS.

[0046] For the common control channel (CCCH), MsgB can include a signaling radio bearer (SRB) radio resource control (RRC) message. The format should be designed for both with and without an RRC message.

[0047] For the CCCH, for a successful or fallback RAR, MsgB can multiplex messages for multiple UEs. If we can multiplex SRB RRC messages for multiple UEs, it is FFS.

[0048] The network response to MsgA (i.e., MsgB / Msg2) can include the following:

[0049] Successful RAR

[0050] Back-off RAR

[0051] Back-off indication.

[0052] FFS: the format of the successful RAR and whether the successful RAR is split into more than one message, and the back-off RAR format and whether the traditional msg2 can be reused for the back-off RAR.

[0053] When the CCCH message is included in msgA, the following fields can be included in the successful RAR.

[0054] a. Contention resolution identifier (ID)

[0055] b. C-RNTI

[0056] c. TA command.

[0057] When receiving the back-off RAR, the UE shall advance to the Msg3 step of the 4-step RACH procedure.

[0058] The back-off RAR shall contain the following fields

[0059] a. RAPID

[0060] b. UL grant (to retransmit the MsgA payload). If different grants and reconstructions, FFS regarding the constraints on the grant and UE behavior

[0061] c. Temporary cell RNTI (TC-RNTI)

[0062] d. TA command.

[0063] From the perspective of RAN2, the start of the MsgB monitoring window does not require further offset (i.e., no offset is required to cover the RRC processing delay and / or F1 delay).

[0064] The UE will use a single msgB agreement window to monitor the response message.

[0065] The MsgB containing the successful RAR shall not be multiplexed in the same MAC PDU as the traditional 4-step RACH RAR.

[0066] Agreement based on 3GPP document R2-1911776:

[0067] Working assumption: SRB RRC messages of multiple UEs cannot be multiplexed in the same MsgB (i.e., the same MAC PDU).

[0068] The successful RAR cannot be split into more than one message (i.e., the contention resolution ID will also be included in the successful RAR).

[0069] Able to reuse successful RAR and fallback RAR

[0070] and

[0071] => From the perspective of RAN2, the HARQ feedback required for msgB

[0072] and

[0073] The TB size provided in the UL grant in the fallback RAR shall be the same as the TB size provided for payload transmission in MsgA; otherwise, UE behavior is undefined (i.e., depends on UE implementation).

[0074] In the 4-step random access procedure, all or most UEs transmitting a PRACH preamble at a given PRACH occasion are unlikely to transmit HARQ-ACK feedback on the same time slot in response to receiving their own Msg4 PDSCH, because each UE can experience a different number of retransmissions for Msg3 PUSCH and / or the network entity can adjust the transmission timing of the Msg4 PDSCH (addressed to the UE's TC-RNTI) based on its scheduling decision. Therefore, 16 PUCCH resources in a common (e.g., cell-specific configured) PUCCH resource set may be sufficient to accommodate the HARQ-ACK feedback from UEs performing the 4-step random access procedure. However, in the 2-step random access procedure, a group of UEs transmitting a PRACH preamble and the corresponding MsgA PUSCH at a given PRACH occasion and MsgA PUSCH occasion may receive a successful RAR in the same MsgB PDSCH and may have to provide HARQ-ACK feedback. Therefore, it may be necessary to allow the network entity to indicate different values of the PDSCH-to-HARQ feedback timing indicator for different expected UEs for the MsgB PDSCH. In addition, if the network entity has downlink (DL) data for the UE and anticipates subsequent DL transmissions to the UE, the DL channel state information (CSI) acquisition and reporting of the UE during the 2-step random access procedure can be used.

[0075] According to Subclause 9.2.1 of 3GPP TS 38.213 V15.6.0 (2019-06), if the UE does not have a dedicated PUCCH resource configuration provided by the PUCCH-ResourceSet in the PUCCH-Config, the PUCCH resource set is provided by pucch-ResourceCommon through an index to the rows of Table 9.2.1-1 for use in The HARQ-ACK information is transmitted on the PUCCH in the initial UL bandwidth part (BWP) of a physical resource block (PRB). The PUCCH resource set includes sixteen resources, each corresponding to a PUCCH format, first symbol, duration, PRB offset, and cyclic shift index set for PUCCH transmission. The UE uses frequency hopping to transmit the PUCCH. The orthogonal cover code with index 0 is used for the PUCCH resource with PUCCH format 1 in Table 9.2.1-1. The UE uses the same spatial domain transmission filter as that for the PUSCH transmission scheduled by the RAR UL grant as described in Subclause 8.3 to transmit the PUCCH.

[0076] If no pdsch-HARQ-ACK-Codebook is provided to the UE, the UE generates at most one HARQ-ACK information bit.

[0077] If the UE provides HARQ-ACK information in the PUCCH transmission in response to detecting downlink control information (DCI) format 1_0 or DCI format 1_1, the UE determines the PUCCH resource with index r PUCCH where 0 ≤ r PUCCH ≤ 15, as where, N CCE is the number of control channel elements (CCEs) in the control resource set (CORESET) for the PDCCH reception with DCI format 1_0 or DCI format 1_1, as described in Subclause 10.1, n CCE，0 is the index of the first CCE for the PDCCH reception, and Δ PRI is the value of the PRI field in DCI format 1_0 or DCI format 1_1.

[0078] If then the UE determines the PRB index for the PUCCH transmission in the first hop as and determines the PRB index for the PUCCH transmission in the second hop as where, N CS is the total number of initial cyclic shift indices in the initial cyclic shift index set; and the UE determines the initial cyclic shift index in the initial cyclic shift index set as r PUCCH mod N CS .

[0079] If then the UE determines the PRB index for the PUCCH transmission in the first hop as and determines the PRB index for the PUCCH transmission in the second hop as and the UE determines the initial cyclic shift index in the initial cyclic shift index set as (rPUCCH (−8) mod N CS 。

[0080] Table 9.2.1-1: PUCCH resource sets before dedicated PUCCH resource configuration

[0081]

[0082] When several UEs have data for the multicast MsgB, 3GPP Tdoc R1-1908342 provides various ways to uniquely determine the PUCCH resources:

[0083] The DCI field is extended to include multiple PUCCH resource indicators and / or PDSCH-to-HARQ feedback timing indicators, one indicator for each UE that has its contention resolution identity in MsgB. Although this scheme may seem simple to design, it increases the size of the DCI, and based on the DCI size constraint, there is an upper limit on the number of UEs that can place their contention resolution identity in MsgB.

[0084] The DCI field provides the contention resolution identity to the PUCCH resource indicator and PDSCH-to-HARQ feedback timing indicator of the first UE in MsgB. If there are other UEs with contention resolution identities in MsgB, PUCCH resource indicators and PDSCH-to-HARQ feedback timing indicators are provided inside MsgB. This scheme does not increase the size of the DCI but increases the size of MsgB.

[0085] The PUCCH resources are implicitly derived depending on the contention resolution identity position of the UE within MsgB and parameters related to the DCI that schedules MsgB (e.g., the starting CCE index of the DCI of MsgB, PUCCH resource indicator and / or PDSCH-to-HARQ feedback timing, and higher layer parameters). This scheme does not increase the size of the DCI that schedules MsgB or the size of MsgB.

[0086] According to Subclause 8.1 of 3GPP TS 38.213, the higher layer configuration for PRACH transmission includes the following: a configuration for PRACH transmission as described in TS 38.211; and the preamble index, preamble subcarrier spacing (SCS), P PRACH,目标 , the corresponding RA-RNTI, and the PRACH resources.

[0087] As described in Subclause 7.4, transmit the PRACH with transmit power P PRACH，b，f，c (i) using the selected PRACH format to transmit the PRACH.

[0088] The ssb-perRACH-OccasionAndCb-Preamble PerSSB provides the UE with N synchronization signal (SS) / physical broadcast channel (PBCH) blocks associated with one PRACH occasion and R contention-based preambles for each SS / PBCH block of each valid PRACH occasion. If N < 1, one SS / PBCH block is mapped to 1 / N consecutive valid PRACH occasions, and R contention-based preambles with consecutive indices associated with the SS / PBCH block of each valid PRACH occasion start from preamble index 0. If N ≥ 1, R contention-based preambles with consecutive indices associated with n (0 ≤ n ≤ N - 1) SS / PBCH blocks of each valid PRACH occasion start from preamble index which is provided by totalNumberOfRA-Preambles and is an integer multiple of N. N can be a fraction. The SS / PBCH block indices provided by ssb-PositionsInBurst in SIB1 or in ServingCellConfigCommon are mapped to valid PRACH occasions in the following order, where the parameters are described in Subclause 4 of TS 38.211: First, in ascending order of preamble indices within a single PRACH occasion; second, in ascending order of frequency resource indices of PRACH occasions for frequency reuse; third, in ascending order of time resource indices of PRACH occasions for time reuse within a PRACH slot; fourth, in ascending order of indices of PRACH slots.

[0089] The association period for mapping SS / PBCH blocks to PRACH occasions starting from frame 0 is the minimum value in the set determined by the PRACH configuration period according to Table 8.1-1, such that

[0090] at least one SS / PBCH block is mapped to a PRACH occasion within the association period, where the UE obtains the value of ssb-PositionsInBurst in SIB1 or in ServingCellConfigCommon. If, after an integer number of SS / PBCH block to PRACH occasion mapping cycles within the association period, there are SS / PBCH blocks that are not mapped to ​If there is no set of PRACH occasions for an SS / PBCH block, then no SS / PBCH block is mapped to the set of PRACH occasions. The associated pattern period includes one or more associated periods and is determined such that the pattern between the PRACH occasion and the SS / PBCH block repeats at most every 160 milliseconds. PRACH occasions that are not associated with an SS / PBCH block after an integer number of associated periods, if any, are not used for PRACH transmission.

[0091] For a PRACH transmission triggered by a PDCCH command, if the value of the random access preamble index field is non-zero, the PRACH mask index field described in Subclause 5 of TS 38.212 indicates the PRACH occasion used for the PRACH transmission, where the PRACH occasion is associated with the SS / PBCH block index indicated by the SS / PBCH block index field of the PDCCH command. The PRACH occasions are mapped continuously according to the corresponding SS / PBCH block index. The index of the PRACH occasion indicated by the mask index value is reset in each mapping cycle of the consecutive PRACH occasions for each SS / PBCH block index. The UE selects, for the PRACH transmission, the PRACH occasion indicated by the PRACH mask index value for the SS / PBCH block index indicated in the first available mapping cycle.

[0092] For the indicated preamble index, the PRACH occasions are sorted as follows: First, in ascending order of the frequency resource index of the PRACH occasions for frequency reuse; second, in ascending order of the time resource index of the PRACH occasions for time reuse within the PRACH slot; and third, in ascending order of the index of the PRACH slot.

[0093] For a PRACH transmission triggered upon a higher layer request, if the value of the random access preamble index field is non-zero, the value of ra-OccasionList described in Subclause 12 of TS 38.331 indicates a list of PRACH occasions used for the PRACH transmission, where the PRACH occasions are associated with the CSI-reference signal (RS) index indicated by the csi-RS. The index of the PRACH occasion indicated by ra-OccasionList is reset according to each associated pattern period.

[0094] Table 8.1-1: Mapping between PRACH configuration periods and the PRACH occasion association periods for SS / PBCH blocks

[0095] PRACH Configuration Period (milliseconds) Associated Period (Multiple PRACH Configuration Periods) 10 {1，2，4，8，16} 20 {1，2，4，8} 40 {1，2，4} 80 {1，2} 160 {1}

[0096] For paired spectrum, all PRACH occasions are valid. For unpaired spectrum, if TDD-UL-DL-ConfigurationCommon is not provided to the UE, then a PRACH occasion in a PRACH slot is valid if the PRACH occasion in the PRACH slot does not precede the SS / PBCH block in the PRACH slot and starts at least N gap symbols after the last SS / PBCH block reception symbol, where N gap is provided in Table 8.1-2.

[0097] If TDD-UL-DL-ConfigurationCommon is provided to the UE, then a PRACH occasion in a PRACH slot is valid if the PRACH occasion in the PRACH slot is within a UL symbol or does not precede the SS / PBCH block in the PRACH slot, and starts at least N gap symbols after the last downlink symbol and at least N gap symbols after the last SS / PBCH block transmission symbol, where N gap is provided in Table 8.1-2 for preamble format B4 described in subclause 4 of TS 38.211, and N gap = 0.

[0098] Table 8.1-2: Values of N for different preamble SCS μ gap Value

[0099]

[0100] At least some embodiments can provide a MsgB structure and HARQ-ACK feedback for MsgB. In one implementation, for the following cases, it can be expected that the UE provides HARQ-ACK feedback for MsgB during a two-step random access procedure. In the first case, if the UE includes a C-RNTI in MsgA and / or performs a contention-free two-step random access procedure, it can be expected that the UE provides HARQ-ACK feedback in response to detecting a DCI format addressing the C-RNTI of the scheduled unicast MsgB PDSCH. In the second case, if the UE includes a CCCH service data unit (SDU) in MsgA, it can be expected that the UE provides HARQ-ACK feedback in response to detecting a DCI format addressing the MsgB-RNTI and finding its contention resolution identity from one of the successful RARs in the MsgB PDSCH.

[0101] For the first case above, the UE can send an ACK or a negative ACK (NACK) depending on the decoding success or failure of the MsgB PDSCH. For the second case above, the UE can only send an ACK.

[0102] In one embodiment, the UE is capable of receiving one or more common PUCCH resource configurations for a two-step random access procedure and is capable of determining, based on the one or more common PUCCH resource configurations, one or more sets of common PUCCH resources configured for the two-step random access procedure. In one implementation, the one or more sets of common PUCCH resources configured for the two-step random access procedure can be different from the set of common PUCCH resources configured for the four-step random access procedure. In another implementation, a set of common PUCCH resources from the one or more sets of common PUCCH resources can be used for both the two-step random access procedure and the four-step random access procedure, where the UE can transmit a HARQ-ACK bit in a PUCCH resource in the set of common PUCCH resources. Different sets of common PUCCH resources can have different PUCCH formats to accommodate different amounts of uplink control information (UCI) bits generated by different types of UCI. For example, different types of UCI can include only 1-bit HARQ-ACK information, HARQ-ACK information and CSI report 1 (e.g., the report quantity indicator set to "ssb-Index-RSRP" includes the SS / PBCH block index and the corresponding RSRP value), and HARQ-ACK and CSI report 2 (e.g., the report quantity indicator set to "deltaCQI" includes differential channel quality indicator (CQI) information regarding the CQI / modulation and coding scheme (MCS) for the MsgB PDSCH).

[0103] In one example of PUCCH formats 1 and 2, the common PUCCH resource configuration can include the following information: PUCCH format (e.g., specified in 3GPP TS 38.213), the first symbol of PUCCH transmission (i.e., the starting symbol), the number of symbols of PUCCH transmission, PRB offset, and the initial cyclic shift index set. In another example of PUCCH formats 2 and 3, the common PUCCH resource configuration can include the starting PRB (or PRB offset), the number of PRBs, the number of symbols of PUCCH transmission, and the first symbol of PUCCH transmission. In yet another example of PUCCH format 4, the common PUCCH resource configuration can include the PRB offset, the number of symbols of PUCCH transmission, the length of the orthogonal cover code, and the first symbol of PUCCH transmission.

[0104] According to one embodiment, a UE is capable of receiving one or more cell-specific CSI report configurations and one or more associated common PUCCH resource configurations, and is capable of receiving an indication as to whether a successful RAR reception of MsgB destined for the UE includes a CSI report and / or which type of CSI report is included in the PUCCH resource carrying the HARQ-ACK information of the MsgB PDSCH. Based on this indication, the UE is capable of determining an appropriate set of common PUCCH resources to use, and is also capable of identifying a PUCCH resource from the determined set of common PUCCH resources based on an explicit and / or implicit PUCCH resource indication (e.g., a combination of a PRI and a starting CCE index of the MsgB DCI).

[0105] According to another embodiment, a UE is capable of determining a PDSCH-to-HARQ-ACK feedback timing for HARQ-ACK feedback in response to a successful RAR received successfully in the MsgB PDSCH based on 1) information in a PDSCH-to-HARQ-ACK feedback timing indicator field of the DCI scheduling the MsgB PDSCH and 2) a PDSCH-to-HARQ-ACK feedback timing offset indicated explicitly and / or implicitly in a MAC sub-PDU destined for the UE.

[0106] Figure 2 FIG. 200 is an example illustration of a MAC sub-header with a BI of an example MAC sub-PDU for MsgB according to a possible embodiment. Figure 3 FIG. 300 is an example illustration of a MAC sub-header with a RAPID for a fallback RAR of an example MAC sub-PDU for MsgB according to a possible embodiment. Figure 4 FIG. 400 is an example illustration of a MAC sub-header with a PHFTO / PRI for a successful RAR of an example MAC sub-PDU for MsgB according to a possible embodiment. Figure 5 FIG. 500 is an example illustration of a MAC successful RAR of an example MAC sub-PDU of MsgB according to a possible embodiment.

[0107] A MAC PDU for the MsgB PDSCH can include one or more MAC sub-PDUs and optionally padding. Each MAC sub-PDU can include one of the following: a MAC sub-header with only a BI; a MAC sub-header with a RAPID and a MAC fallback RAR; or a MAC sub-header with a PHFTO / PRI and a MAC successful RAR.

[0108] In the MAC sub-header, "T1" can indicate the MAC sub-header type, where "T1" set to 0 can indicate a MAC sub-header with RAPID, and "T1" set to 1 can indicate a MAC sub-header with only BI or a MAC sub-header with PHFTO / PRI. Additionally, "T2" can also indicate the MAC sub-header type, where "T2" set to 0 can indicate a MAC sub-header with only BI, and "T2" set to 1 can indicate a MAC sub-header with PHFTO / PRI. "E" can be an extension flag, which can indicate whether the MAC sub-PDU including this MAC sub-header is the last MAC sub-PDU in the MAC PDU. The E field can be set to 1 to indicate at least one more subsequent MAC sub-PDU. The E field is set to 0 to indicate that the MAC sub-PDU including this MAC sub-header is the last MAC sub-PDU in the MAC PDU. "R" can indicate a reserved bit set to 0.

[0109] The MAC successful RAR in FIG. 500 can include a CSI request field and a transmit power control (TPC) command for the PUCCH used for scheduling. The MAC successful RAR can also include a UE contention resolution identity, a timing advance command, and a temporary C-RNTI. Examples of the 2-bit CSI request field are defined in Table 1, and examples of the 2-bit PUCCH TPC command are defined in Subclause 7.2.1 of TS38.213. In this example, the MAC fallback RAR can be the same as the MAC RAR of the 4-step random access procedure. If the UE receives a MAC sub-PDU including the MAC successful RAR, the UE can determine the PDSCH-to-HARQ-ACK feedback timing by applying the indicated PHFTO value to the value of the PDSCH-to-HARQ-ACK feedback timing indicator in the DCI.

[0110] Table 1: Examples of the CSI request field

[0111]

[0112] Figure 6 FIG. 600 is an example illustration of a MAC sub-header with BI of an example MAC sub-PDU for MsgB according to a possible embodiment. Figure 7 FIG. 700 is an example illustration of a MAC sub-header with RAPID for fallback RAR and successful RAR of an example MAC sub-PDU for MsgB according to a possible embodiment. Figure 8FIG. 800 is an example illustration of a MAC successful RAR for an example MAC sub-PDU for MsgB according to a possible embodiment. For example, each MAC sub-PDU can include one of the following: a MAC sub-header having only a BI; a MAC sub-header having a RAPID and a MAC fallback RAR; or a MAC sub-header having a RAPID and a MAC successful RAR.

[0113] In this example, a common PUCCH resource set can be configured for the two-step random access procedure. The MAC fallback RAR can be the same as the MAC RAR for the four-step random access procedure, except that a reserved 1 bit can be used to indicate the type of RAR, i.e., a fallback RAR or a successful RAR. The UE can receive a cell-specific configuration for a set of PHFTO values and can determine which timing offset value to apply to the PDSCH-to-HARQ_Feedback timing indicator value in the DCI scheduling the MsgB PDSCH based on the order of the MAC sub-PDUs for the UE within the MAC PDU of the MsgB PDSCH. For example, if the MAC sub-PDU destined for the UE is placed in the MAC PDU of the MsgB PDSCH in the fifth order, the UE can apply the fifth timing offset value from the set of PDSCH-to-HARQ_Feedback timing offset values.

[0114] At least some embodiments can provide MsgB transmissions within a MsgB window. In an embodiment, a network entity can enable or disable support for HARQ combining for the UE of the MsgB PDSCH via higher layer signaling depending on the deployment and / or usage scenario (e.g., cell size, expected average number of UEs performing the two-step random access procedure per MsgA occasion, number of active UEs, and PDCCH capacity). The UE can interpret the DCI field information of the DCI format for scheduling the MsgB PDSCH differently depending on the enabling / disabling of support for HARQ combining of the MsgB PDSCH.

[0115] In one example, if the average number of UEs performing the two-step random access procedure per MsgA occasion is high, HARQ combining for the MsgB PDSCH can be disabled. In the case of a large number of UEs performing the two-step random access procedure per MsgA occasion, it can be expected that the MsgB MAC PDU size is large. Thus, retransmission of the same MsgB MAC PDU may not be efficient. Instead, the network entity can retransmit the successful RAR for which its corresponding HARQ-ACK feedback has not been successfully received.

[0116] In one example, the following information is transmitted by means of DCI format 1_0 with a Cyclic Redundancy Check (CRC) scrambled by MsgB-RNTI to schedule the MsgB PDSCH:

[0117] - Frequency domain resource allocation bits

[0118] - If CORESET 0 is configured for the cell, then is the size of CORESET 0, and if CORESET 0 is not configured for the cell, then is the size of the initial DL bandwidth part

[0119] - Time domain resource allocation - 4 bits, as defined in subclause 5.1.2.1 of [TS38.214]

[0120] - VRB to PRB mapping according to Table 7.3.1.2.2-5 - 1 bit

[0121] - Modulation and coding scheme using Table 5.1.3.1-1 - 5 bits, as defined in subclause 5.1.3 of [TS38.214]

[0122] - TB scaling - 2 bits, as defined in subclause 5.1.3.2 of [TS38.214]

[0123] - PDSCH to HARQ_feedback timing indicator - 3 bits, as defined in subclause 9.2.3 of [TS38.213]

[0124] - If HARQ combining for MsgB PDSCH is supported and enabled in 3GPP Rel-16 NR, then new data indicator - 1 bit. Otherwise, 0 bit.

[0125] - If HARQ combining for MsgB PDSCH is supported and enabled in 3GPP Rel-16 NR, then redundancy version - 2 bits, as defined in Table 7.3.1.1.1-2. Otherwise, 0 bits.

[0126] - If HARQ combining for MsgB PDSCH is supported and enabled in 3GPP Rel-16 NR, then HARQ process number - 4 bits. Otherwise, 0 bits.

[0127] - If HARQ combining for MsgB PDSCH is supported and enabled in 3GPP Rel-16 NR, then reserved bits - 6 bits. Otherwise, 13 bits.

[0128] At least some embodiments can provide a two-step random access procedure initiated by a network command. According to one embodiment, if the UE receives a command to initiate a random access procedure, the UE can also receive an indication of the random access procedure type for the initiated random access procedure (i.e., two-step RACH versus four-step RACH). The command to initiate a random access procedure can be received via a layer 1 indication (e.g., PDCCH instruction) or a higher layer indication (e.g., RRC parameter "Reconfiguration WithSync").

[0129] If a two-step contention-free random access procedure is indicated in the command, the UE can receive information on a dedicated PRACH preamble and / or dedicated MsgA PUSCH resources. In addition, the UE can receive an indication to request a CSI report and can send the CSI report in the MsgA PUSCH. The UE performing a contention-free two-step random access procedure can be in the RRC connected mode. Since the network entity knows the PRACH preamble and / or MsgA PUSCH resources assigned to the UE, the UE can not include a UE identifier (e.g., C-RNTI or CCCH SDU) in the MsgA PUSCH, but can include a CSI report in the MsgA PUSCH. The network entity can use the CSI report from the UE to schedule the UE-specific MsgB PDSCH or other PDSCH destined for the UE with an appropriate MCS, resource allocation (e.g., number of PRBs, number of symbols), and spatial setting (e.g., (multiple) TCI states, number of spatial layers, (multiple) precoders).

[0130] In a network-initiated two-step random access procedure, when transmitting the PRACH preamble and MsgA PUSCH, the UE can monitor, within the MsgB window (i.e., MsgB random access response window), DCI formats with CRC scrambled by a UE-specific identifier (e.g., C-RNTI) (i.e., PDCCH addressed to the UE-specific identifier) to receive the PDCCH scheduling the MsgB PDSCH.

[0131] In one example, the UE can perform a two-step or four-step random access procedure for PDCCH instructions by detecting DCI format 1_0 with a CRC scrambled by the C-RNTI and having the following information. If downlink data arrives at the UE and the UE does not have uplink synchronization (e.g., the "timeAlignmentTimer" has expired), the network entity can send a PDCCH instruction to initiate a random access procedure. In one embodiment, the network entity can determine the random access procedure type (two-step RACH vs. four-step RACH) based on the UE's radio resource management (RRM) measurement report (e.g., reference signal received power (RSRP) measurement) and / or path loss estimation. Together with the initiation of the two-step random access procedure, the network entity can request a CSI report. The CSI request and the random access procedure type can be jointly encoded in a bit field, or separately indicated in the DCI with different bit fields.

[0132] - Identifier of the DCI format - 1 bit

[0133] - The value of this bit field can always be set to 1, indicating the DL DCI format

[0134] - Frequency domain resource assignment - Bits, where, Given by Subclause 7.3.1.0. All bits in this field are set to one to indicate the initiation of a random access procedure based on a PDCCH instruction.

[0135] - Random access procedure type and CSI request indicator - X bits (e.g., X = 2) if the UE is configured with both a two-step random access configuration and a four-step random access configuration in the serving cell. If the UE is configured with either a two-step random access configuration or a four-step random access configuration in the serving cell, this field can be reserved.

[0136] - Random access preamble index - 6 bits of ra-Preamble Index according to Subclause 5.1.2 of [TS 38.321].

[0137] - UL / Supplementary Uplink (SUL) indicator - 1 bit. If the value of the "random access preamble index" is not all zeros and if the UE is configured with supplementaryUplink in ServingCellConfig in the cell, this field can indicate which UL carrier in the cell is to transmit the PRACH according to Table 7.3.1.1.1-1 of 3GPP TS 38.213; otherwise, this field can be reserved.

[0138] - SS / PBCH Index - 6 bits. If the value of "Random Access Preamble Index" is not all zeros, this field can indicate the SS / PBCH that should be used to determine the RACH occasion for PRACH transmission; otherwise, this field can be reserved.

[0139] - PRACH Mask Index - 4 bits. If the value of "Random Access Preamble Index" is not all zeros, according to Subclause 5.1.1 of [8, TS38.321], this field can indicate the RACH occasion associated with the SS / PBCH for PRACH transmission indicated by the "SS / PBCH Index"; otherwise, this field can be reserved.

[0140] - Reserved Bits - (10 - X) bits

[0141] Table 2: Examples of Random Access Procedure Types and CSI Request Indicators

[0142]

[0143] In another example, the UE can initiate a 2-step or 4-step random access procedure when receiving an "RRCReconConfiguration" message including the RRC parameter "ReconfigurationWithSync" (i.e., SpCell change, handover). According to one embodiment, the random access procedure type (2-step RACH vs. 4-step RACH) can be indicated in the RRC parameter "ReconfigurationWithSync", and the "RACH-ConfigDedicated-2Step" information element can include the dedicated preamble index and the dedicated MsgA PUSCH resource associated with the dedicated preamble index, as shown in Tables 3 and 4.

[0144] In one embodiment, if the UE is instructed to perform a 2-step random access procedure during an SpCell change, the UE can use the indicated new UE identity ("newUE-Identity") to send the UE identity in the MsgA PUSCH (e.g., for contention-based 2-step RACH), and monitor the PDCCH scheduling the MsgB PDSCH (e.g., monitor the DCI format with CRC scrambled by the new UE identity).

[0145] Table 3: SpCellConfig and ReconfigurationWithSync

[0146]

[0147] Table 4: RACH-ConfigDedicated-2Step Information Element

[0148]

[0149]

[0150] At least some embodiments can provide a search space configuration for MsgB. According to Subclause 10.1 of 3GPP TS38.213, the set of PDCCH candidates to be monitored by a UE is defined according to the PDCCH search space set. The search space set can be a common search space (CSS) set or a UE-specific search space (USS) set. The UE can monitor PDCCH candidates in one or more of the following search space sets:

[0151] - The Type0-PDCCH CSS set configured by pdcch-ConfigSIB1 in the master information block (MIB), or by searchSpaceSIB1 in PDCCH-ConfigCommon, or by searchSpaceZero in PDCCH-ConfigCommon for DCI formats with CRC scrambled by the system information (SI)-RNTI on the primary cell of the master cell group (MCG); - The Type0A-PDCCH CSS set configured by searchSpaceOtherSystemInformation in PDCCH-ConfigCommon for DCI formats with CRC scrambled by the SI-RNTI on the primary cell of the MCG;

[0152] - The Type1-PDCCH CSS set configured by ra-SearchSpace in PDCCH-ConfigCommon for DCI formats with CRC scrambled by the RA-RNTI or TC-RNTI on the primary cell;

[0153] - The Type2-PDCCH CSS set configured by pagingSearchSpace in PDCCH-ConfigCommon for DCI formats with CRC scrambled by the Paging (P)-RTNI on the primary cell of the MCG;

[0154] - The Type3-PDCCH CSS set configured by SearchSpace in PDCCH-Config (where searchSpaceType = common) for DCI formats with CRC scrambled by INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, or TPC-Sounding Reference Signal (SRS)-RNTI, and C-RNTI, MCS-C-RNTI, or Configured Scheduling (CS)-RNTI only for the primary cell; and

[0155] - The USS set configured by SearchSpace in PDCCH-Config (where searchSpaceType = ue-Specific) for DCI formats with CRC scrambled by C-RNTI, MCS-C-RNTI, SP-CSI-RNTI, or CS-RNTI.

[0156] According to one embodiment, the UE can be configured with two PDCCH search space sets related to the reception of the PDCCH scheduling the MsgB PDSCH for the two-step random access procedure. In one example, for the first PDCCH search space set, a new type of common search space set, i.e., the Type1A-PDCCH CSS set, can be configured for DCI formats with CRC scrambled by MsgB-RNTI on the SpCell through the cell-specific parameter "MsgB-SearchSpaceCommon" in PDCCH-ConfigCommon. For the second PDCCH search space set, the search space set provided by the UE-specific parameter "MsgB-SearchSpace" in PDCCH-Config and the corresponding CORESET can be configured for DCI formats with CRC scrambled by C-RNTI or other UE-specific RNTIs. In one example, the second PDCCH search space set can be the USS set configured by SearchSpace in PDCCH-Config (where searchSpaceType = ue-Specific).

[0157] In one embodiment, the UE can be configured with two different MsgB windows, namely a first MsgB window associated with a first PDCCH search space set (e.g., CSS) and a second MsgB window associated with a second PDCCH search space set (e.g., USS), where a given MsgB time window can be defined based on the start time and duration relative to the end time of the MsgA (PRACH and MsgA PUSCH) transmission. For example, the first MsgB window can be configured with a longer duration than the second MsgB window, because the network entity can transmit multiple MsgB PDSCHs with different MAC PDUs within the first MsgB window to send many successful RARs and / or fallback RARs associated with one MsgA occasion. In another embodiment, the UE can be configured with the same MsgB window for the first PDCCH search space set and the second PDCCH search space set. Separate search space / CORESET configurations for the broadcast / multicast MsgB PDSCH (scheduled by DCI addressed to the MsgB-RNTI) and the unicast MsgB PDSCH (scheduled by DCI addressed to the UE-specific RNTI) can allow PDCCH transmissions optimized for broadcast and unicast depending on the PDCCH type.

[0158] In an embodiment of the contention-based two-step random access procedure, if the UE includes a UE-specific RNTI in the MsgA PUSCH, the UE can monitor PDCCH candidates in the first PDCCH search space set within the first MsgB window and in the second PDCCH search space set within the second MsgB window when transmitting the PRACH preamble and the MsgA PUSCH, where the first MsgB window can be the same as or different from the second MsgB window. If the UE has successfully completed the contention-based two-step random access procedure (including fallback operations to the four-step random access procedure), but has not been provided with other UE-specific search space sets, the UE can monitor PDCCH candidates for fallback / compact DCI formats (e.g., DCI format 0_0 and DCI format 1_0) with CRC scrambled by the UE-specific RNTI (e.g., C-RNTI) in the second PDCCH search space set provided by MsgB-SearchSpace.

[0159] For PDCCH monitoring in the search space sets provided for MsgB-SearchSpaceCommon and MsgB-SearchSpace and for corresponding MsgB PDSCH reception, the UE can assume the same antenna port quasi-configuration parameters as those associated with the antenna port quasi-configuration parameters of the SS / PBCH block or CSI-RS resource, and the UE uses these parameters for MsgA (i.e., PRACH preamble and MsgA PUSCH) resource selection.

[0160] If the UE receives the MsgB PDSCH by detecting a DCI format with a CRC scrambled by the MsgB-RNTI in the first PDCCH search space set, and a fallback RAR intended for the UE is found in the received MsgB PDSCH, the UE can perform a retransmission of the MsgA PUSCH (or transmission of the Msg3 PUSCH) according to the UL grant indicated in the fallback RAR. The first search space set provided by MsgB-SearchSpaceCommon (i.e., the Type1A-PDCCH CSS set), the corresponding CORESET, and the TC-RNTI indicated in the fallback RAR can be used for PDCCH scheduling of the retransmission of the MsgA PUSCH. On the other hand, the PDCCH addressed to the UE-specific RNTI (e.g., C-RNTI) in the second search space set provided by MsgB-SearchSpace can indicate successful contention resolution. Therefore, the UE can continue to monitor the first PDCCH search space set and the second PDCCH search space set during the fallback operation. If the UE receives the MsgB PDSCH by detecting a DCI format with a CRC scrambled by the UE-specific RNTI in the second PDCCH search space set and successfully decodes the MsgB PDSCH, the UE can consider that the contention-based two-step random access procedure is successfully completed.

[0161] In the implementation of the contention-free two-step random access procedure, the UE can monitor the MsgB PDCCH only in the second PDCCH search space set (i.e., USS) provided by MsgB-SearchSpace. If the contention-free two-step random access procedure is initiated by a PDCCH command, the UE can assume that the MsgB PDCCH and the PDCCH command have the same demodulation reference signal (DM-RS) antenna port quasi-collocation attribute.

[0162] If a UE-specific MsgB search space set (e.g., MsgB-SearchSpace) is provided to the UE, the UE may not expect to be provided with another search space set for monitoring the PDCCH in the CORESET associated with the search space set provided by MsgB-SearchSpace.

[0163] At least some embodiments are capable of providing PRACH power settings when the UE reverts from a two-step RACH to a four-step RACH. The PRACH preamble power control parameters can include powerRampingStep and preambleReceivedTargetPower. In one implementation, the UE can receive separate sets of PRACH preamble power control parameters for the two-step random access procedure and the four-step random access procedure, respectively. In another implementation, if the PRACH preamble power control parameters for the two-step random access procedure are not configured separately, the UE can assume that they are the same as the PRACH preamble power control parameters for the four-step random access procedure.

[0164] According to Subclause 7.4 of 3GPP TS 38.213, the UE determines the transmission power P of the physical random access channel (PRACH) on the active UL BWP b of the carrier f of the serving cell c based on the DL RS of the serving cell c in the transmission occasion i PRACH，b，f，c (i) as

[0165] P PRACH，b，f，c (i) = min{P CMAX，f，c (i), P PRACH，target，f，c + PL b，f，c} [dBm] ,

[0166] where P CMAX，f，c (i) is the maximum output power configured for the UE as defined in [TS 38.101-1], [TS 38.101-2], and [TS 38.101-3] for the carrier f of the serving cell c within the transmission occasion i, P PRACH，target，f，c is the PRACH target received power PREAMBLE_RECEIVED_TARGET_POWER provided by the higher layers [TS 38.321] for the active UL BWP b of the carrier f of the serving cell c, and PL b，f，cis the path loss of the active ULBWP b of carrier f, which is based on the DL RS associated with the PRACH transmission on the active DL BWP of serving cell c and is calculated by the UE in dB as referenceSignalPower in dBm - the higher layer filtered RSRP, where RSRP is defined in [TS 38.215] and the higher layer filter configuration is defined in [TS 38.331]. If the active DL BWP is the initial DL BWP and is used for SS / PBCH block and CORESET multiplexing mode 2 or 3 as described in sub - clause 13 of [38.213], the UE is able to determine the PL based on the SS / PBCH block associated with the PRACH transmission b，f，c .

[0167] If within the RAR window, the UE does not receive any RAR (e.g., successful RAR, fallback RAR, or MsgBPDCCH addressed to C - RNTI) for a two - step RACH intended for the UE or an RAR for a four - step RACH that contains a preamble identifier corresponding to the preamble sequence transmitted by the UE, the UE is able to determine the transmission power for subsequent PRACH transmissions as follows [TS 38.321]:

[0168] 1> If PREAMBLE_TRANSMISSION_COUNTER is greater than one; and

[0169] 1> If no notification to pause the power ramping counter is received from the lower layer; and

[0170] 1> If the selected SSB or CSI - RS has not changed from the selection in the previous random access preamble transmission:

[0171] 2> Increment PREAMBLE_POWER_RAMPING_COUNTER by 1.

[0172] 1> Select the value of DELTA_PREAMBLE according to clause 7.3 of [TS 38.321];

[0173] 1> Set PREAMBLE_RECEIVED_TARGET_POWER to preambleReceivedTargetPower + DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER – 1)×PREAMBLE_POWER_RAMPING_STEP.

[0174] If the UE changes the spatial domain transmission filter before PRACH retransmission, layer 1 can notify the higher layer to pause the power ramping counter.

[0175] During a two-step random access procedure, if the UE has transmitted the PRACH and MsgA PUSCH a configured number of times (e.g., N times) and has not successfully received MsgB destined for the UE, the UE reverts to a four-step random access procedure and only retransmits the PRACH.

[0176] In one embodiment, if the UE switches from a two-step random access procedure to a four-step random access procedure and only retransmits the PRACH after N MsgA transmissions, the power ramping counter can be paused. Alternatively, the power ramping counter (i.e., PREAMBLE_POWER_RAMPING_COUNTER) can be reset to one. Additionally, the UE can set PREAMBLE_RECEIVED_TARGET_POWER to preambleReceivedTargetPower1 + DELTA_PREAMBLE1 + (PREAMBLE_POWER_RAMPING_COUNTER – 1) × PREAMBLE_POWER_RAMPING_STEP1, where preambleReceivedTargetPower1, DELTA_PREAMBLE1, and PREAMBLE_POWER_RAMPING_STEP1 are parameters associated with the four-step random access configuration. If the PRACH configuration (including PRACH occasion and PRACH format) for two-step RACH is configured to be different from the PRACH configuration for four-step RACH, the UE can apply these methods. Pausing the power ramping counter can provide a trade-off between avoiding unnecessary high interference caused by PRACH transmission and avoiding long random access delays due to multiple PRACH retransmissions. If the UE changes the uplink carrier used for the random access procedure when switching from two-step RACH to four-step RACH (e.g., from supplementary uplink (SUL) to non-supplementary uplink (NUL) or from NUL to SUL), the UE can reset the power ramping counter to one.

[0177] In another embodiment, if after N MsgA transmissions, the UE switches from a two-step random access procedure to a four-step random access procedure and only retransmits the PRACH, the MAC of the UE can increment the preamble power ramping counter by 1 if it has not received a notification to pause the power ramping counter from the lower layer.

[0178] In addition, the UE is capable of setting PREAMBLE_RECEIVED_TARGET_POWER to preambleReceivedTargetPower1 + DELTA_PREAMBLE1 + (PREAMBLE_POWER_RAMPING_COUNTER – 1) × PREAMBLE_POWER_RAMPING_STEP1, where preambleReceivedTargetPower1, DELTA_PREAMBLE1, and PREAMBLE_POWER_RAMPING_STEP1 are parameters associated with the 4-step random access configuration.

[0179] Alternatively, the UE is capable of setting PREAMBLE_RECEIVED_TARGET_POWER to preambleReceivedTargetPower1 + DELTA_PREAMBLE1 + (PREAMBLE_POWER_RAMPING_COUNTER – 2) × PREAMBLE_POWER_RAMPING_STEP2 + PREAMBLE_POWER_RAMPING_STEP1, where PREAMBLE_POWER_RAMPING_STEP2 is the preamble power ramping step associated with the 2-step random access configuration.

[0180] For example, PREAMBLE_RECEIVED_TARGET_POWER can be the PRACH target received power provided by a higher layer for an active UL BWP, which can be the power expected to be received at the gNB. Before applying power ramping, preambleReceivedTargetPower1 can be the initial PRACH target received power for 4-step RACH. DELTA_PREAMBLE1 can be a power offset value based on the preamble format, where the preamble format can be configured by a higher layer such as the RRC layer. PREAMBLE_POWER_RAMPING_STEP, such as powerRampingStep, can be a power ramping factor.

[0181] If the 2-step RACH and the 4-step RACH have the same PRACH configuration (e.g., the PRACH occasion is shared between the 2-step and 4-step RACH), the UE is capable of applying these methods. According to another embodiment, if the 2-step RACH and the 4-step RACH have different PRACH configurations, the UE is capable of performing various embodiments.

[0182] Figure 9FIG. 900 is an example flow chart illustrating the operation of a device such as UE 110 according to a possible embodiment. At 910, a command can be received from a network entity. The command can initiate a random access procedure. The command can include information on the type of random access procedure. The type of random access procedure can be one selected from a two-step random access procedure and a four-step random access procedure. The command can be received via the physical layer (such as in a PDCCH instruction) or via a higher layer (such as in RRC parameters).

[0183] At 920, when the type of random access procedure is a two-step random access procedure, a MsgA transmission can be transmitted in response to receiving the command. According to a possible embodiment, the type of random access procedure can be determined to be a two-step random access procedure based on information, and a MsgA transmission can be transmitted in response to determining that the type of random access procedure is a two-step random access procedure.

[0184] According to a possible embodiment, the command can be a downlink control information including an indication to initiate a random access procedure based on a PDCCH instruction. According to another possible embodiment, the command can be a handover command in a higher layer message including a plurality of radio resource control parameters for reconfiguring a radio resource control configuration. The handover can include reconfiguration and synchronization of a plurality of radio resource control parameters. The MsgA transmission can be transmitted in response to receiving the handover command in the higher layer message. For example, the higher layer message can be an "RRCReconfiguration" message, and the handover command can be a "ReconfigurationWithSync" parameter, which can indicate a SpCell change, i.e., a handover and other reconfigurations. The SpCell can be a specific primary cell of a cell group, for example, the primary cell (PCell) of a master cell group (MCG) and the primary secondary cell (PSCell) of a secondary cell group (SCG).

[0185] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, information on at least one dedicated PRACH preamble and at least one corresponding set of PRACH occasions for the two-step random access procedure can be received. The transmission of MsgA can include transmitting a dedicated PRACH preamble among the at least one dedicated PRACH preambles on a PRACH occasion included in the at least one set of PRACH occasions. The set of PRACH occasions can be associated with the dedicated PRACH preamble. For example, according to one embodiment, the type of the random access procedure (two-step RACH versus four-step RACH) can be indicated in the RRC parameter "ReconfigurationWithSync", and the "ConfigDedicated-2Step" information element can include a dedicated preamble index and a dedicated MsgA PUSCH resource associated with the dedicated preamble index.

[0186] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, information on at least one dedicated MsgA PUSCH resource can be received. The at least one dedicated MsgA PUSCH resource can be associated with at least one dedicated PRACH preamble and with at least one set of PRACH occasions for the two-step random access procedure. The transmission of MsgA can include transmitting a dedicated PRACH preamble on a PRACH occasion and transmitting a corresponding MsgA PUSCH on the dedicated MsgA PUSCH resource among the at least one dedicated MsgA PUSCH resources.

[0187] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, an indication to request a CSI report can be received. The transmission of MsgA can include a MsgA PUSCH containing a CSI report. According to a possible embodiment, the reception command can include receiving a DCI that includes a field indicating an indication of a CSI report jointly encoded with information on the type of the random access procedure. For example, the CSI request and the type of the random access procedure can be jointly encoded in a bit field, or can be indicated in different bit fields in the DCI respectively.

[0188] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, a configuration of a first PDCCH search space set and a second PDCCH search space set for reception of the PDCCH can be received in response to the transmission of MsgA. After the transmission of MsgA, in the two-step random access procedure, a plurality of PDCCH candidates can be monitored in at least one of the first PDCCH search space set and the second PDCCH search space set.

[0189] According to possible embodiments, monitoring multiple PDCCH candidates can include monitoring multiple PDCCH candidates within a time window. The start time of the time window can be based on the end time of the MsgA transmission and the configurations of the first PDCCH search space set and the second PDCCH search space set. The time window associated with the first PDCCH search space set can be different from the time window associated with the second PDCCH search space set, or can be the same as the time window associated with the second PDCCH search space set. The time window can be defined according to the start time relative to the end time of the MsgA transmission, and can be defined according to the duration of the time window.

[0190] According to possible embodiments, the first PDCCH search space set can be a common search space set for DCI formats with cyclic redundancy checks scrambled by a first identifier. The second PDCCH search space set can be a UE-specific search space set for DCI formats with cyclic redundancy checks scrambled by a second identifier.

[0191] According to a possible example of the above embodiments, the first identifier can be a MsgB-RNTI determined based on the PRACH occasion for the PRACH preamble transmission for the MsgA transmission. The MsgB-RNTI can be used to receive the PDCCH scheduling the MsgB PDSCH corresponding to the MsgA transmission. The MsgB PDSCH can be decoded. It can be determined whether the MsgB PDSCH includes a fallback RAR intended for the UE.

[0192] According to another possible example of the above embodiments, the second identifier can be a user equipment specific identifier, and the MsgA transmission can include a MsgA PUSCH that includes the user equipment specific identifier. According to possible embodiments, the MsgA transmission can include a contention-based PRACH preamble transmission. Monitoring multiple PDCCH candidates can include monitoring multiple PDCCH candidates in the first PDCCH search space set and the second PDCCH search space set.

[0193] Figure 10FIG. 1000 is an example flowchart illustrating the operation of an apparatus such as network entity 120 according to a possible embodiment. At 1010, a command to initiate a random access procedure can be transmitted. The command can include information on the type of random access procedure. The type of random access procedure can be one of a two-step random access procedure and a four-step random access procedure selected therefrom. According to a possible implementation, before transmitting the command, it can be determined whether the type of random access procedure is a two-step random access procedure or a four-step random access procedure, and the command can be transmitted in response to the determination. At 1020, based on the type of random access procedure being a two-step random access procedure, a MsgA transmission can be received in response to the transmission of the command.

[0194] Figure 11 FIG. 1100 is an example flowchart illustrating the operation of an apparatus such as UE 110 according to a possible embodiment. At 1110, a first transmission power for a first PRACH preamble can be determined in a two-step random access procedure based on a first set of power control parameters. At 1120, the first PRACH preamble can be transmitted in the two-step random access procedure based on the first transmission power.

[0195] At 1130, it can be determined to switch from a two-step random access procedure to a four-step random access procedure. Determining the switch can include determining to switch from a two-step random access procedure to a four-step random access procedure in response to a MsgA PRACH transmission based on the MsgA PRACH transmission being performed a threshold number of times in the two-step random access procedure without successfully receiving a MsgB RAR message.

[0196] At 1140, in response to determining the switch, a second transmission power can be determined based on the first set of power control parameters and a second set of power control parameters for subsequent second PRACH preamble transmissions in the four-step random access procedure. At 1150, the subsequent second PRACH preamble can be transmitted in the four-step random access procedure based on the second transmission power.

[0197] According to a possible embodiment, the operation can include transmitting a MsgA PUSCH associated with the first PRACH preamble in the two-step random access procedure.

[0198] According to a possible embodiment, the operation can include receiving a two-step random access channel configuration and a four-step random access channel configuration. According to a possible implementation, the two-step random access channel configuration can include a first set of power control parameters, and the four-step random access channel configuration can include a second set of power control parameters. According to a possible implementation, the two-step random access channel configuration can include a first PRACH preamble format, and the four-step random access channel configuration includes a second PRACH preamble format. The first transmission power can depend on a first power offset corresponding to the first preamble format, and the second transmission power can depend on a second power offset corresponding to the second preamble format.

[0199] According to a possible embodiment, the first set of power control parameters can include a first power ramp factor and a first initial preamble reception target power, and the second set of power control parameters can include a second power ramp factor and a second initial preamble reception target power. According to a possible implementation, the operation can include incrementing a preamble power ramp counter by 1 before determining the second transmission power. According to a possible implementation, the operation can include setting the second PRACH target reception power to be equal to the value of the second initial preamble reception target power + a second preamble format-specific power offset + (the preamble power ramp counter - 2) × the first power ramp factor + the second power ramp factor. According to a possible implementation, based on the downlink reference signal of serving cell c in transmission occasion i, the second transmission power P PRACH，b，f，c (i) is determined as:

[0200] P PRACH，b，f，c (i) = min{P CMAX，f，c (i), P PRACH，target，f，c + PL b，f，c} [dBm] .

[0201] P CMAX，f，c (i) can be the maximum output power configured for the UE for the carrier f of serving cell c within transmission occasion i. P PRACH，target，f，c can be the second PRACH target reception power provided by a higher layer for the active UL BWP b of the carrier f of serving cell c, where the higher layer is above the physical layer. PL b，f，c can be the path loss for the active UL BWP b of the carrier f based on the downlink reference signal associated with the second PRACH preamble transmission, where the downlink reference signal is on the active DL BWP of serving cell c, and where the path loss PL b，f，c is calculated by the UE. The second PRACH target reception power P PRACH，target，f，c can be provided by a higher layer.

[0202] Figure 12 FIG. 1200 is an example flow chart showing the operation of a device such as network entity 120 according to a possible embodiment. At 1210, it is possible to transmit a 2-step random access channel configuration including a first set of power control parameters and a 4-step random access channel configuration including a second set of power control parameters. At 1220, it is possible to receive a first PRACH preamble in a 2-step random access procedure based on a first transmission power determined based on a first set of transmission power parameters for the first PRACH preamble. At 1230, it is possible to receive a subsequent second PRACH preamble in a 4-step random access procedure based on a second transmission power determined based on a first set of power control parameters and a second set of power control parameters for subsequent second PRACH preamble transmissions. The first PRACH preamble and the subsequent second PRACH preamble can be transmitted from the same UE.

[0203] Figure 13 FIG. 1300 is an example flow chart illustrating the operation of a device such as UE 110 according to a possible embodiment. At 1310, it is possible to receive at least one common PUCCH resource set configuration for a 2-step random access procedure. At 1320, it is possible to determine at least one common PUCCH resource set based on the at least one common PUCCH resource set configuration.

[0204] At 1330, it is possible to transmit a PRACH and a corresponding MsgA PUSCH. The MsgA PUSCH can be user data transmission from the UE to the network entity in a 2-step random access procedure.

[0205] At 1340, it is possible to receive a MsgB PDSCH in response to the transmitted PRACH and MsgA PUSCH. The MsgB can be a message from the network entity to the UE in a 2-step random access procedure. At 1350, it is possible to decode the received MsgB PDSCH. At 1360, it is possible to identify a successful RAR intended for the UE from the decoded MsgB PDSCH.

[0206] At 1370, it is possible to determine a common PUCCH resource set in the at least one common PUCCH resource set and a PUCCH resource in the common PUCCH resource set based on the successful RAR. At 1380, it is possible to transmit at least HARQ-ACK feedback information for the MsgB PDSCH on the PUCCH resource.

[0207] According to a possible embodiment, each of the at least one common PUCCH resource set configurations defines each of the at least one common PUCCH resource sets.

[0208] According to possible embodiments, a DCI format addressed to the MsgB-RNTI can be detected. The MsgB-RNTI can be a radio network temporary identifier for multiple UEs that is used to select a specific PRACH occasion for PRACH preamble transmission in a two-step random access procedure. The DCI format addressed to the MsgB-RNTI can be a DCI format included in the PDCCH that has a CRC scrambled by the MsgB-RNTI. The MsgB PDSCH can be received based on the detected DCI format.

[0209] According to possible embodiments, a specific common PUCCH resource set configuration of at least one common PUCCH resource set configuration can be used for a four-step random access procedure.

[0210] According to possible embodiments, at least transmitting HARQ-ACK feedback information can include: based on a successful RAR intended for the UE identified from the decoded MsgB PDSCH and based on HARQ-ACK information including an affirmative acknowledgment, at least transmitting HARQ-ACK feedback information. For example, the UE can transmit HARQ-ACK information only when the HARQ-ACK information is an affirmative acknowledgment (no HARQ-ACK transmission for NACK).

[0211] According to possible embodiments, a successful RAR can include an indication of whether CSI reporting is multiplexed with HARQ-ACK information on a PUCCH resource. The common PUCCH resource set can be determined based on this indication. According to possible implementations, this indication can also include information on the CSI reporting type. The common PUCCH resource set can be determined based on the information on the CSI reporting type.

[0212] According to possible embodiments, each of at least one common PUCCH resource set configuration includes information on the PUCCH format.

[0213] According to possible embodiments, a higher layer UE identifier can be sent on the MsgA PUSCH. For example, the higher layer UE identifier can be included in a common control channel service data unit (CCCH SDU). According to possible implementations, identifying a successful RAR intended for the UE can include identifying a successful RAR with a contention resolution identifier, where the contention resolution identifier is based on the higher layer UE identifier.

[0214] According to a possible embodiment, an indication can be received. The indication can indicate whether to allow at least one retransmission of the transport block of MsgB PDSCH by a network entity, so that the UE can receive and combine the data of the transport block for each transmission of the transport block by the network entity. The DCI for scheduling the transport block can be received based on the indication. For example, the operation can include receiving and combining the data of the transport block for multiple transmissions of the transport block by the network entity if the network entity is allowed to retransmit the transport block of MsgB PDSCH.

[0215] According to a possible implementation, receiving the DCI can include receiving a DCI including at least one field related to the combination of the data of the transport block in response to receiving an indication that allows at least one retransmission of the transport block of MsgB PDSCH by a network entity. In response to receiving an indication that does not allow at least one retransmission of the transport block of MsgB PDSCH by a network entity, the DCI can be received without at least one field related to the combination of the data of the transport block. For example, if HARQ combination of MsgB PDSCH is supported and enabled in 3GPP Rel-16 NR, the field can be a new data indicator field of 1 bit. Otherwise, it is 0 bit. If the configuration does not support HARQ combination, the new data indicator field can be reserved (i.e., not used).

[0216] Figure 14 FIG. 1400 is an example flowchart illustrating the operation of a device such as network entity 120 according to a possible embodiment. At 1410, at least one common PUCCH resource set configuration for a two-step random access procedure can be transmitted. The at least one common PUCCH resource set configuration can configure at least one common PUCCH resource set. At 1420, a PRACH and a corresponding MsgA PUSCH can be received. At 1430, a MsgB PDSCH can be transmitted in response to the received PRACH and MsgA PUSCH. The MsgB PDSCH can include a successful RAR intended for the UE. At 1440, at least HARQ-ACK feedback information for the MsgB PDSCH can be received on the PUCCH resource of the common PUCCH resource set in the at least one common PUCCH resource set. The common PUCCH resource set and the PUCCH resource can be determined based on the successful RAR.

[0217] It should be understood that, despite the specific steps as shown in the figures, various additional or different steps can be performed depending on the embodiment, and one or more of the specific steps can be rearranged, repeated, or completely eliminated depending on the embodiment. In addition, some of the steps performed when performing other steps can be repeated simultaneously on an ongoing or continuous basis. Further, different steps can be performed by different elements of the disclosed embodiments or within a single element of the disclosed embodiments. Additionally, a network entity such as a base station, a transmission and reception point, a mobility management entity, or other network entity can perform the reciprocal operations of the UE. For example, the network entity can transmit the signals received by the UE and can receive the signals transmitted by the UE. The network entity can also process and operate on the signals sent and received.

[0218] Figure 15 FIG. Figure 15 is an exemplary block diagram of an apparatus 1500 such as UE 110, network entity 120, or any other wireless communication device disclosed herein according to a possible embodiment. The apparatus 1500 can include a housing 1510, a controller 1520 coupled to the housing 1510, an audio input and output circuit 1530 coupled to the controller 1520, a display 1540 coupled to the controller 1520, a memory 1550 coupled to the controller 1520, a user interface 1560 coupled to the controller 1520, a transceiver 1570 coupled to the controller 1520, at least one antenna 1575 coupled to the transceiver 1570, and a network interface 1580 coupled to the controller 1520. The apparatus 1500 may not necessarily include all of the illustrated elements for different embodiments of the present disclosure. The apparatus 1500 can perform the methods described in all embodiments.

[0219] The display 1540 can be a viewfinder, a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a plasma display, a projection display, a touch screen, or any other device that displays information. The transceiver 1570 can be one or more transceivers capable of including a transmitter and / or a receiver. The audio input and output circuitry 1530 can include a microphone, a speaker, a transducer, or any other audio input and output circuitry. The user interface 1560 can include a keypad, a keyboard, buttons, a touchpad, a joystick, a touch screen display, another additional display, or any other device for providing an interface between the user and the electronic device. The network interface 1580 can be a universal serial bus (USB) port, an Ethernet port, an infrared transmitter / receiver, an IEEE 1394 port, a wireless transceiver, a WLAN transceiver, or any other interface capable of connecting the device to a network, a device, and / or a computer and capable of transmitting and receiving data communication signals. The memory 1550 can include random access memory (RAM), read only memory (ROM), optical memory, solid state memory, flash memory, removable memory, a hard disk drive, a cache, or any other memory capable of being coupled to the device.

[0220] The device 1500 or the controller 1520 can implement any operating system, such as Microsoft Android TM or any other operating system. For example, the device operating software can be written in any programming language such as C, C++, Java, or Visual Basic. The device software can also be in, for example framework, Run on an application framework of a framework or any other application framework. The software and / or operating system can be stored in the memory 1550, anywhere on the device 1500, in cloud storage, and / or anywhere capable of storing the software and / or operating system. The device 1500 or the controller 1520 can also use hardware to implement the disclosed operations. For example, the controller 1520 can be any programmable processor. In addition, the controller 1520 can perform some or all of the disclosed operations. For example, at least some operations can be performed using cloud computing and the controller 1520 can perform other operations. At least some operations can also be performed by computer-executable instructions executed by at least one computer processor. The disclosed embodiments can also be implemented on a general-purpose or special-purpose computer, a programmed microprocessor or microcontroller, peripheral integrated circuit elements, application-specific integrated circuits or other integrated circuits, hardware / electronic logic circuits (such as discrete element circuits), programmable logic devices (such as programmable logic arrays, field-programmable gate arrays, etc.). Generally, the controller 1520 can be any controller or processor device or equipment capable of operating the device and implementing the disclosed embodiments. Some or all of the additional elements of the device 1500 can also perform some or all of the operations of the disclosed embodiments.

[0221] In operation, the device 1500 can perform the methods and operations of the disclosed embodiments. The transceiver 1570 can transmit and receive signals, including data signals and control signals, which can include corresponding data and control information. The controller 1520 can generate and process the transmitted and received signals and information.

[0222] In an operation according to a possible embodiment, the transceiver 1570 can receive a command from a network entity. The command can initiate a random access procedure. The command can include information about the type of the random access procedure. The type of the random access procedure can be one selected from a two-step random access procedure and a four-step random access procedure. The controller 1520 can determine that the type of the random access procedure is a two-step random access procedure based on the information indicating that the type of the random access procedure is a two-step random access procedure. When the type of the random access procedure is a two-step random access procedure, the transceiver 1570 can transmit a MsgA transmission in response to receiving the command.

[0223] According to a possible embodiment, the command can be downlink control information including an indication to initiate a random access procedure based on a PDCCH instruction. According to another possible embodiment, the command can be a handover command in a higher layer message including multiple radio resource control parameters for reconfiguring a radio resource control configuration. The handover can include reconfiguring multiple radio resource control parameters and synchronization. The transceiver 1570 can transmit a MsgA transmission in response to receiving the handover command in the higher layer message.

[0224] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, the transceiver 1570 is capable of receiving information on at least one dedicated PRACH preamble and at least one corresponding set of PRACH occasions for the two-step random access procedure. The transceiver 1570 is capable of transmitting a MsgA transmission by transmitting a dedicated PRACH preamble among the at least one dedicated PRACH preambles on a PRACH occasion in a set of PRACH occasions in at least one group of PRACH occasions. The set of PRACH occasions can be associated with the dedicated PRACH preamble. According to a possible implementation, when the type of the random access procedure is a two-step random access procedure, the transceiver 1570 is capable of receiving information on at least one dedicated MsgA PUSCH resource associated with at least one dedicated PRACH preamble and associated with at least one set of PRACH occasions for the two-step random access procedure. The transceiver 1570 is capable of transmitting a MsgA transmission by transmitting a dedicated PRACH preamble on a PRACH occasion and transmitting a corresponding MsgA PUSCH on the dedicated MsgA PUSCH resource of at least one dedicated MsgA PUSCH resource.

[0225] According to a possible embodiment, when the type of the random access procedure is a two-step random access procedure, the transceiver 1570 is capable of receiving a configuration of a first PDCCH search space set and a second PDCCH search space set for receiving a PDCCH in response to transmitting a MsgA transmission. After the transceiver 1570 transmits a MsgA transmission, the controller 1520 is capable of monitoring a plurality of PDCCH candidates in at least one of the first PDCCH search space set and the second PDCCH search space set in the two-step random access procedure. According to a possible implementation, the first PDCCH search space set can be a common search space set for a DCI format with a cyclic redundancy check scrambled by a first identifier. The second PDCCH search space set can be a UE-specific search space set for a DCI format with a cyclic redundancy check scrambled by a second identifier.

[0226] In operation according to a possible embodiment, the controller 1520 is capable of determining a first transmission power for a first PRACH preamble in a two-step random access procedure based on a first set of power control parameters. The transceiver 1570 is capable of transmitting the first PRACH preamble in the two-step random access procedure based on the first transmission power. The controller 1520 is capable of determining a switch from the two-step random access procedure to a four-step random access procedure. The controller 1520 is capable of determining a second transmission power in response to determining the switch based on the first set of power control parameters and a second set of power control parameters for transmission of a subsequent second PRACH preamble in the four-step random access procedure. The transceiver 1570 is capable of transmitting the subsequent second PRACH preamble in the four-step random access procedure based on the second transmission power.

[0227] According to a possible embodiment, the transceiver 1570 is capable of transmitting a MsgA PUSCH associated with the first PRACH preamble in a two-step random access procedure.

[0228] According to a possible embodiment, the transceiver 1570 is capable of receiving a two-step random access channel configuration and a four-step random access channel configuration. The two-step random access channel configuration can include a first set of power control parameters, and the four-step random access channel configuration can include a second set of power control parameters. The two-step random access channel configuration can include a first PRACH preamble format, and the four-step random access channel configuration can include a second PRACH preamble format. The first transmission power can depend on a first power offset corresponding to the first preamble format, and the second transmission power can depend on a second power offset corresponding to the second preamble format.

[0229] According to a possible embodiment, the first set of power control parameters can include a first power ramp factor and a first initial preamble received target power. The second set of power control parameters can include a second power ramp factor and a second initial preamble received target power. The controller 1520 can increment a preamble power ramp counter by 1 before determining the second transmission power. The controller 1520 can set the second PRACH target received power to be equal to the value of the second initial preamble received target power + a second preamble format specific power offset + (the preamble power ramp counter - 2) × the first power ramp factor + the second power ramp factor. The controller 1520 can determine a second transmission power P PRACH，b，f，c (i) for transmission of the second PRACH preamble on the active UL BWP b of the serving cell c on the carrier f as:

[0230] P PRACH，b，f，c (i) = min{P CMAX，f，c (i), P PRACH，target，f，c + PLb，f，c} [dBm]。

[0231] P CMAX，f，c (i) can be the maximum output power configured for the UE for carrier f of the serving cell c within transmission occasion i. P PRACH，target，f，c can be the second PRACH target reception power provided by the higher layer for the active UL BWP b of carrier f of the serving cell c, where the higher layer can be higher than the physical layer. PL b，f，c can be the path loss for the active UL BWP b of carrier f based on the downlink reference signal associated with the second PRACH preamble transmission, where the downlink reference signal can be on the active DL BWP of the serving cell c, and where the path loss PL b，f，c can be calculated by the UE.

[0232] According to a possible embodiment, the controller 1520 can determine to switch from the two-step random access procedure to the four-step random access procedure based on performing MsgA PRACH transmissions for a threshold number of times in the two-step random access procedure without successfully receiving the MsgB RAR message in response to the MsgA PRACH transmission.

[0233] In an operation according to another possible embodiment, the transceiver 1570 can receive at least one common PUCCH resource set configuration for the two-step random access procedure. The controller 1520 can determine at least one common PUCCH resource set based on the at least one common PUCCH resource set configuration. The transceiver 1570 can transmit a PRACH and the corresponding MsgA PUSCH. The transceiver 1570 can receive the MsgB PDSCH in response to the transmitted PRACH and MsgA PUSCH. The controller 1520 can decode the received MsgB PDSCH. The controller 1520 can identify a successful RAR intended for the UE from the decoded MsgB PDSCH. The controller 1520 can determine the common PUCCH resource set in the at least one common PUCCH resource set and the PUCCH resources in the common PUCCH resource set based on the successful RAR. The transceiver 1570 can transmit at least HARQ-ACK feedback information for the MsgB PDSCH on the PUCCH resources.

[0234] According to a possible embodiment, each of the at least one common PUCCH resource set configurations can define each of the at least one common PUCCH resource sets.

[0235] According to a possible embodiment, the controller 1520 is capable of detecting a DCI format addressed to the MsgB-RNTI. The DCI format addressed to the MsgB-RNTI can be a DCI format included in the PDCCH having a CRC scrambled by the MsgB-RNTI. The MsgB PDSCH can be received based on the detected DCI format.

[0236] According to a possible embodiment, a specific common PUCCH resource set configuration of at least one common PUCCH resource set configuration can be used for a 4-step random access procedure.

[0237] According to a possible embodiment, the transceiver 1570 can transmit at least HARQ-ACK feedback information based on a successful RAR destined for the device identified from the decoded MsgB PDSCH and based on HARQ-ACK information including a positive acknowledgment.

[0238] According to a possible embodiment, the successful RAR can include an indication of whether CSI reporting is multiplexed with HARQ-ACK information on a PUCCH resource. The common PUCCH resource set can be determined based on the indication. According to a possible implementation, the indication can also include information on the CSI report type. The common PUCCH resource set can be determined based on the information on the CSI report type.

[0239] According to a possible embodiment, each of at least one common PUCCH resource set configuration can include information on the PUCCH format.

[0240] An embodiment can provide a method in a UE. The method can include receiving one or more common PUCCH resource set configurations for a 2-step random access procedure. The method can include determining one or more common PUCCH resource sets based on the one or more common PUCCH resource set configurations. The method can include transmitting a PRACH on a PRACH occasion and a corresponding MsgA PUSCH. The method can include detecting a DCI format addressed to the MsgB-RNTI. The MsgB-RNTI can be based at least on the PRACH occasion. The method can include receiving the MsgB PDSCH based on the detected DCI format. The method can include decoding the received MsgB PDSCH. The method can include identifying a successful RAR destined for the UE from the decoded MsgB PDSCH. The method can include determining the common PUCCH resource set and the PUCCH resources in the common PUCCH resource set based on the successful RAR. The method can include transmitting at least HARQ-ACK feedback information on the PUCCH resources.

[0241] According to possible embodiments, each of one or more common PUCCH resource set configurations can define each of one or more common PUCCH resource sets.

[0242] According to possible embodiments, the DCI format addressed to the MsgB-RNTI can be a DCI format included in the PDCCH with a CRC scrambled by the MsgB-RNTI.

[0243] According to possible embodiments, the common PUCCH resource set configuration of one or more common PUCCH resource set configurations can be used for a 4-step random access procedure.

[0244] According to possible embodiments, the HARQ-ACK feedback information can be an affirmative acknowledgment.

[0245] According to possible embodiments, a successful RAR can include an indication of whether CSI reports are multiplexed with HARQ-ACK information on a PUCCH resource. The common PUCCH resource set can be determined based on this indication. According to possible implementations, this indication can include information on the CSI report type. The common PUCCH resource set can be determined based on the information on the CSI report type.

[0246] According to possible embodiments, each of one or more common PUCCH resource set configurations can include information on the PUCCH format.

[0247] According to possible embodiments, the method can include transmitting a higher layer UE identifier (e.g., a CCCH SDU) on the MsgA PUSCH.

[0248] According to possible implementations, identifying a successful RAR destined for a UE can include identifying a successful RAR having a contention resolution identifier. The contention resolution identifier can be based on the higher layer UE identifier.

[0249] At least some of the methods of the present disclosure can be implemented on a programmed processor. However, controllers, flowcharts, and modules can also be implemented on general or special purpose computers, programmed microprocessors or microcontrollers and peripheral integrated circuit elements, integrated circuits, hardware electronic or logic circuits (such as discrete components, programmable logic devices, etc.). Generally, any device on which a finite state machine capable of implementing the flowcharts shown in the figures resides can be used to implement the processor functions of the present disclosure.

[0250] At least some embodiments can improve the operation of the disclosed devices. Similarly, while the present disclosure has been described in terms of its specific embodiments, it will be apparent that many alternatives, modifications, and variations will be obvious to those skilled in the art. For example, the various components of an embodiment can be interchanged, added, or replaced in other embodiments. Similarly, all of the elements of each figure are not necessary for the operation of the disclosed embodiments. For example, one of ordinary skill in the art in the field of the disclosed embodiments can practice and use the teachings of the present disclosure by using only the elements of the independent claims. Accordingly, the embodiments of the present disclosure described herein are intended to be illustrative and not limiting. Various changes can be made without departing from the spirit and scope of the present disclosure.

[0251] In this document, relational terms such as "first", "second", etc. may be used solely to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual such relationship or order between such entities or actions. A phrase followed by a list such as "at least one of...", "at least one selected from the group of...", or "at least one selected from..." is defined to mean one, some, or all of the elements in the list, but not necessarily all of the elements. The terms "comprises", "comprising", "including", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "a", "an", etc. does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Similarly, the term "another" is defined as at least second or more. As used herein, the terms "including", "having", etc. are defined as "comprising". In addition, the background art section is not submitted as prior art but is written as the inventor's own understanding of the context of some embodiments at the time of filing and includes the inventor's own recognition of any problems in the prior art and / or problems encountered by the inventor in their own work.

Claims

1. A method at a user equipment (UE) for wireless communication, the method comprises: determining a first transmission power of a first physical random access channel (PRACH) preamble for a two-step random access procedure based on a first set of power control parameters; transmitting the first PRACH preamble based on the first transmission power; determining to switch to a four-step random access procedure; determining a second transmission power based on the first set of power control parameters and a second set of power control parameters for a second PRACH preamble for the four-step random access procedure; transmitting the second PRACH preamble based on the second transmission power, wherein the method further comprises: incrementing a preamble power ramp counter by 1 before determining the second transmission power; and setting a second PRACH target received power to be equal to the following value: second initial preamble received target power + second preamble format specific power offset + (the preamble power ramp counter - 2) × first power ramp factor + second power ramp factor.

2. The method according to claim 1, further comprising transmitting a MsgA physical uplink shared channel (PUSCH) associated with the first PRACH preamble.

3. The method according to claim 1, further comprising receiving a two-step RACH configuration and a four-step RACH configuration.

4. The method according to claim 3, wherein, the two-step RACH configuration comprises the first set of power control parameters, and wherein the four-step RACH configuration comprises the second set of power control parameters.

5. The method according to claim 3, wherein, the two-step RACH configuration comprises a first PRACH preamble format, wherein the four-step RACH configuration comprises a second PRACH preamble format, and wherein the first transmission power depends on a first power offset corresponding to the first PRACH preamble format, and the second transmission power depends on a second power offset corresponding to the second PRACH preamble format.

6. The method according to claim 1, wherein: the first set of power control parameters comprises a first power ramp factor and a first initial preamble received target power; and the second set of power control parameters comprises a second power ramp factor and a second initial preamble received target power.

7. The method according to claim 1, wherein, Based on the transmission opportunity i in the serving cell c for the downlink reference signal, calculate the following for the carrier of the serving cell c of the serving cell f for the active uplink bandwidth part b the second transmission power for the second PRACH preamble : ， Among them, is the maximum output power configured for the UE of the carrier i for the serving cell c within the said transmission opportunity f ​ Among them, is the second PRACH target receiving power, and wherein, is the path loss for the carrier f of the active uplink bandwidth part b based on a downlink reference signal associated with the second PRACH preamble, wherein the downlink reference signal is on the active downlink bandwidth part of the serving cell c of the active downlink bandwidth part.

8. A user equipment (UE) capable of: determining a first transmission power of a first physical random access channel (PRACH) preamble for a two-step random access procedure based on a first set of power control parameters ； and transmitting the first PRACH preamble based on the first transmission power, determining to switch to a four-step random access procedure; determining a second transmission power based on the first set of power control parameters and a second set of power control parameters for a second PRACH preamble for the four-step random access procedure, transmitting the second PRACH preamble based on the second transmission power, incrementing a preamble power ramp counter by 1 before determining the second transmission power; and Set the second PRACH target reception power to be equal to the following value: the second initial preamble reception target power + the second preamble format specific power offset + (the preamble power ramp counter - 2) × the first power ramp factor + the second power ramp factor.

9. The UE according to claim 8, wherein, the UE is capable of transmitting, during the two-step random access procedure, a MsgA physical uplink shared channel PUSCH associated with the first PRACH preamble.

10. The UE according to claim 8, wherein, the UE is capable of receiving a two-step RACH configuration and a four-step RACH configuration.

11. The UE according to claim 10, wherein, the two-step RACH configuration includes the first set of power control parameters, and wherein the four-step RACH configuration includes the second set of power control parameters.

12. The UE according to claim 10, wherein, the two-step RACH configuration includes a first PRACH preamble format, wherein the four-step RACH configuration includes a second PRACH preamble format, and wherein the first transmission power depends on a first power offset corresponding to the first PRACH preamble format, and the second transmission power depends on a second power offset corresponding to the second PRACH preamble format.

13. The UE according to claim 8, wherein: the first set of power control parameters includes a first power ramp factor and a first initial preamble reception target power; and the second set of power control parameters includes a second power ramp factor and a second initial preamble reception target power.

14. The UE according to claim 8, wherein, The UE can be based on the transmission occasion i in the serving cell c of the downlink reference signal, and calculate, based on the following, the second transmission power for the second PRACH preamble on the c carrier f of the active uplink bandwidth part b in the serving cell : ， Among them, is the maximum output power configured for the UE for the carrier i of the serving cell c within the said transmission occasion, f ​ wherein, is the second PRACH target received power, and Among them, is the path loss for the carrier f of the active uplink bandwidth part b based on the downlink reference signal associated with the second PRACH preamble, where the downlink reference signal is on the active downlink bandwidth part of the serving cell c .

15. A processor for wireless communication, the processor comprises: at least one controller, the at least one controller being coupled to at least one memory and configured to cause the processor to: determine a first transmission power for a first physical random access channel PRACH preamble for a two-step random access procedure based on a first set of power control parameters; transmit the first PRACH preamble based on the first transmission power; determine to switch to a four-step random access procedure; determine a second transmission power based on the first set of power control parameters and a second set of power control parameters for a second PRACH preamble for the four-step random access procedure; transmit the second PRACH preamble based on the second transmission power, increment a preamble power ramp counter by 1 before determining the second transmission power; and set the second PRACH target reception power to be equal to the following value: the second initial preamble reception target power + the second preamble format specific power offset + (the preamble power ramp counter - 2) × the first power ramp factor + the second power ramp factor.

16. The processor according to claim 15, wherein, the at least one controller is configured to cause the processor to: transmit a MsgA physical uplink shared channel PUSCH associated with the first PRACH preamble.

17. The processor according to claim 15, wherein, the at least one controller is configured to cause the processor to: receive a two-step RACH configuration and a four-step RACH configuration.

18. The processor according to claim 17, wherein, the two-step RACH configuration includes the first set of power control parameters, and wherein the four-step RACH configuration includes the second set of power control parameters.

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