Timing acquisition and handover based on L1 / L2

Abstract

A user equipment (UE) includes a set of transceivers and a processor. The processor is configured to operate the UE in an RRCCONNECTED mode with the first TRP; receiving, via the set of transceivers, a PDCCH command in a search space set associated with at least one of the first TRP or the second TRP; in response to information indicated by the PDCCH command, determining a PRACH resource to be used for a RACH process with the second TRP; and transmitting, via the set of transceivers, a RACH preamble on the PRACH resource to obtain an initial timing advance (TA) towards the second TRP.

Description

Technical Field

[0001] The present application generally relates to wireless communication systems, including timing acquisition and handover. Background Art

[0002] Wireless mobile communication technologies use various standards and protocols to send data between base stations and wireless communication devices. Wireless communication system standards and protocols may include, for example, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and the IEEE 802.11 standard for wireless local area networks (WLANs) (commonly referred to within industry organizations as WLANs). ).

[0003] As envisioned by 3GPP, different wireless communication system standards and protocols may use various radio access networks (RANs) to communicate between base stations of the RAN (which may also sometimes be referred to as RAN nodes, network nodes, or simply nodes) and wireless communication devices referred to as user equipment (UE). 3GPP RANs may include, for example, Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or Next Generation Radio Access Network (NG-RAN).

[0004] Each RAN may use one or more radio access technologies (RATs) to perform communications between base stations and UEs. For example, GERAN implements GSM and / or EDGE RAT, UTRAN implements Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RAT, E-UTRAN implements LTE RAT (sometimes referred to as LTE), and NG-RAN implements NR RAT (sometimes referred to herein as 5G RAT, 5G NR RAT, or NR). In some deployments, E-UTRAN may also implement NR RAT. In some deployments, NG-RAN may also implement LTE RAT.

[0005] The base stations used by the RAN may correspond to the RAN. An example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly denoted as an evolved Node B, enhanced Node B, eNodeB, or eNB). An example of an NG-RAN base station is a Next Generation Node B (sometimes also referred to as a g-Node B or gNB).

[0006] The RAN provides communication services together with external entities through its connection with the Core Network (CN). For example, E-UTRAN may utilize the Evolved Packet Core (EPC) and NG-RAN may utilize the 5G Core Network (5GC). BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To easily identify the discussion of any particular element or action, the most significant digit(s) in a reference number refers to the drawing number that first introduces the element.

[0008] Figure 1 An example wireless communication system including a UE, a first transmit and receive point (TRP), and a second TRP is shown.

[0009] Figure 2 A first example method of a UE performing wireless communication is shown.

[0010] Figure 3 Shown according to Figure 2 An example timing diagram of Physical Downlink Control Channel (PDCCH) command transmission for an intra-cell mTRP implementation of the illustrated method.

[0011] Figure 4 An example of an enhanced PDCCH order downlink control information (DCI) format for triggering an inter-cell multi-TRP (mTRP) random access channel (RACH) procedure is shown.

[0012] Figure 5 Shown according to Figure 2 Another example timing diagram of PDCCH command transmission for some embodiments of the illustrated method.

[0013] Figure 6 A second example method for a UE to perform wireless communications is shown.

[0014] Figure 7 A third example method of a UE performing wireless communications is shown.

[0015] Figure 8 An example Abstract Syntax Notation One (ASN.1) message for Physical Cell ID (PCI) based pre-configuration of a target candidate cell for L1 / L2 based handover is shown.

[0016] Fig. 9 An example cell group-based preconfiguration of target candidate cells for L1 / L2 based handover is shown.

[0017] Fig.10 An example medium access control (MAC) control element (CE) (MAC CE) for triggering L1 / L2 based handover is shown.

[0018] Fig.11 An example DCI format for triggering L1 / L2 based handover is shown.

[0019] Fig.12 A first example method of a base station performing wireless communications is shown.

[0020] Fig.13 A second example method of a base station performing wireless communications is shown.

[0021] Fig.14 A third example method of a base station performing wireless communications is shown.

[0022] Fig.15 An example architecture of a wireless communication system according to embodiments disclosed herein is illustrated.

[0023] Fig.16 A system for performing signaling between a wireless device and a network device according to embodiments disclosed herein is illustrated. DETAILED DESCRIPTION

[0024] Various embodiments are described with respect to UE. However, reference to UE is provided for illustrative purposes only. The example embodiments may be used with any electronic component that can establish a connection with a network and is configured with hardware, software and / or firmware for exchanging information and data with the network. Therefore, UE described herein is used to represent any suitable electronic device.

[0025] New mobile services that require low latency and high reliability performance, such as Ultra-Reliable and Low Latency Communications (URLLC), are emerging. While the 5G 3GPP standard has been designed to address these services from the beginning, the evolution of 5G RATs requires continuous enhancement of mobility robustness for these challenging scenarios.

[0026] Figure 1 An example wireless communication system 100 including a UE 102, a first TRP 104, and a second TRP 106 is shown. The UE 102 can communicate with one or more of the first TRP 104 or the second TRP 106 on a downlink (DL) and an uplink (UL). In various embodiments, the UE 102 can communicate with the first TRP 104, the second TRP 106, or both the first TRP 104 and the second TRP 106 (e.g., in an mTRP scenario). Each TRP can be a macro cell, a small cell, a pico cell, a femto cell, a remote radio head, a relay node, etc. One or more of the UE 102, the first TRP 104, or the second TRP 106 can use multiple-input multiple-output (MIMO) communication technology.

[0027] In some scenarios, the UE 102, the first TRP 104, or the second TRP 106 may have multiple antenna panels, and the antenna panels may be used to communicate with both the first TRP 104 and the second TRP 106 simultaneously or alternately during the same period.

[0028] In some cases, UE 102 can communicate with the first TRP 104 and the second TRP 106 in an mTRP scenario, or can communicate in a single TRP or mTRP scenario using MIMO communication technology. In some cases, UE 102 can switch from the first TRP 104 to the second TRP 106, or vice versa.

[0029] In some embodiments, UE 102 can communicate with another TRP (e.g., a third TRP) simultaneously or concurrently. The first TRP 104, the second TRP 106, or other TRPs can also communicate with other UEs simultaneously or concurrently.

[0030] In wireless communication systems such as Figure 1 In the described wireless communication system, it is desired that the UE obtain an initial timing advance (TA) for a second (or additional) TRP. For example, when the UE will operate in an mTRP scenario involving a second TRP, or when the UE will switch to the second TRP, the initial TA may be used. Therefore, it may be useful for the UE to trigger a RACH process to obtain an initial TA towards the second mTRP.

[0031] In addition, in wireless communication systems such as reference Figure 1 In the wireless communication system described, it is desirable to reduce inter-cell mobility delay. As described herein, inter-cell mobility delay can be reduced by providing a pre-configuration of a target candidate cell to the UE (i.e., providing the pre-configuration before issuing an L1 / L2 handover command), so that the delay of L1 / L2-based handover can be reduced.

[0032] This document also describes an example inter-cell L1 / L2 handover trigger command. In the current 3GPP standard version, the handover command is carried in a layer 3 (L3) radio resource control (RRC) message. In some cases, the L1 / L2 handover trigger command described herein is combined with a trigger related to inter-cell mTRP beam management (e.g., a RACH process trigger).

[0033] Figure 2 A first example method 200 for UE to perform wireless communication is shown. The method 200 may be referred to as Figure 1 The method 200 may be performed by a UE described herein or by other UEs described herein. The method 200 may be performed using a processor, a set of transceivers (eg, one or more transceivers), or other components of a UE.

[0034] At 202, method 200 may include operating the UE in an RRC connected (RRC_CONNECTED) mode with a first TRP (e.g., TRP#1).

[0035] At 204, method 200 may include receiving a PDCCH command (ie, DCI format 1_0). The PDCCH command may be received in a search space set associated with at least one of the first TRP or the second TRP (eg, TRP #2).

[0036] At 206, method 200 may include determining, in response to information indicated by the PDCCH order, a PRACH resource to be used for a RACH procedure with a second TRP. Thus, the PDCCH order includes information that can be used to trigger a RACH procedure. The RACH procedure may be a contention-free RACH (CFRA) procedure or a contention-based RACH (CBRA) procedure triggered by the PDCCH order.

[0037] At 208, method 200 may include sending a RACH preamble on the PRACH resource to obtain an initial TA toward the second TRP.

[0038] The method 200 may be embodied, extended, or modified in various ways, as described in the following paragraphs and elsewhere in this specification.

[0039] In some embodiments, method 200 can be implemented as a method for triggering a cross-TRP RACH process by a PDCCH command, because a PDCCH command sent by one TRP (i.e., a first TRP) can trigger a RACH process for another TRP (i.e., a second TRP). Various cross-TRP RACH processes triggered by PDCCH command implementation schemes are described below.

[0040] In some embodiments of method 200, the first TRP and the second TRP may share a PCI (e.g., an intra-cell mTRP scenario). In these embodiments, at 204, a PDCCH command may be received in a search space set associated with the first TRP (e.g., in a search space set of "coresetPoolIndex=0"). The information indicated by the PDCCH command may include a synchronization signal block (SSB) index and a random access (RA) preamble index associated with the SSB identified by the SSB index. For scenarios in which the PRACH resources determined at 206 are to be used for a CBRA process, the UE may receive (e.g., from the first TRP and before receiving the PDCCH command) multiple SSBs associated with the first TRP and the second TRP for each PRACH opportunity, and multiple contention-based preambles for each SSB. The SSB index may then be used to identify one of the multiple contention-based preambles for the SSB identified by the SSB index. For the scenario where the PRACH resources determined at 206 are to be used for the CFRA procedure, the UE may dynamically select the PRACH resources in response to information indicated by the PDCCH order (eg, SSB index and RA preamble index).

[0041] Figure 3 Shown according to Figure 2 An example timing diagram 300 of PDCCH command transmission for an intra-cell mTRP implementation of the illustrated method (where the first TRP and the second TRP have the same PCI). The timing diagram assumes that the UE is in RRC_CONNECTED mode with the first TRP.

[0042] As shown, the first TRP (e.g., Figure 1 The first search space set (eg, "coresetPoolIndex=0") of the first TRP or TRP#1 shown may include search spaces 302, 304, and 306. The second TRP (eg, Figure 1 A second search space set (e.g., “coresetPoolIndex=1”) of a second TRP or TRP#2 as shown may include search spaces 308 and 310. A first group of SSBs (e.g., SSBs #1, #2, and #3) may be associated with the first search space set (i.e., “coresetPoolIndex=0”), and a second group of SSBs (e.g., SSBs #4, #5, and #6) may be associated with the second search space set (i.e., “coresetPoolIndex=1”).

[0043] As also shown in the figure, a base station (e.g., gNB) may send a PDCCH command 312 (i.e., DCI format 1_0) in the search space 304 of the first TRP. Upon receiving the PDCCH command, the UE may determine, for example, that the PDCCH command indicates <SSB#4, preamble 6>. Upon receiving this DCI, the UE may send preamble 6 associated with SSB#4 to obtain the initial TA towards the second TRP.

[0044] Return Figure 2 , and in some embodiments of method 200, the first TRP and the second TRP may be associated with different PCIs (e.g., an inter-cell mTRP scenario). In these embodiments, the PDCCH command may be received in the search space set associated with the first TRP (e.g., in the search space set with "coresetPoolIndex = 0"). The information indicated by the PDCCH command may identify the TRP associated with the triggered RACH procedure (e.g., the information may include the PCI of the second TRP). The UE may receive the PRACH resource configuration of each non-serving cell in the "additionalPCIlist" (e.g., from the first TRP and before receiving the PDCCH command), where each non-serving cell in the "additionalPCIlist" is configured with an "additional PCI" index in the "additionalPCIlist". The PDCCH command may identify the non-serving cell in the "additionalPCIlist" by its "additionalPCI" index. The TRP determined by the PDCCH command may be identified in different ways, and some examples are described below.

[0045] The PDCCH command includes a set of fields. In some cases, this set of fields may be enhanced to include a field identifying the TRP associated with the triggered RACH procedure (e.g., Figure 2 the second TRP in ). In 3GPP Release 17 (Rel-17), the PCI of the serving cell of the UE and up to seven additional PCIs may be configured for the UE's multi-DCI (mDCI) mTRP operation by RRC signaling. However, only one of the seven additional PCIs may be associated with a set of active TCI states of the UE (e.g., Figure 2the active TCI state of the second TRP in), and the remaining PCIs are not associated with this set of active TCI states. As a result, and in some embodiments, the PDCCH command can be enhanced to include a one-bit field that identifies the TRP associated with the triggered RACH procedure. The one-bit field can identify the TRP as the serving cell of the UE (e.g., for resynchronization purposes) or a non-serving cell associated with this set of active TCI states. For example, when the one-bit field is set to "0", the field can indicate that the triggered RACH procedure is for the serving cell of the UE; and when the one-bit field is set to "1", the field can indicate that the triggered RACH procedure is for a non-serving cell associated with this set of active TCI states (e.g., a non-serving cell associated with the second TRP). In other embodiments, the PDCCH command can be enhanced to include a three-bit field that identifies the TRP associated with the triggered RACH procedure. The three-bit field can identify the TRP as the serving cell of the UE (e.g., for resynchronization purposes) or any one of the seven non-serving cells configured for the mDCI mTRP operation of the UE by RRC signaling (e.g., Figure 2 any non-serving cell of the second TRP in). In this way, the initial TA of the TRP (e.g., the second TRP) can be obtained before activating the TRP.

[0046] Figure 4 shows an example of the enhanced PDCCH command DCI format 400 for triggering an inter-cell mTRP RACH procedure. The PDCCH command DCI format 400 (e.g., enhanced DCI format 1_0) can include a set of fields, including a RA preamble index field 402, a normal UL or supplementary UL (UL / SUL) indicator field 404, a SSB index field 406, a PRACH mask index field 408, a PCI field 410, one or more reserved bits 412, and / or a cyclic redundancy check (CRC) field 414.

[0047] As mentioned before, the PCI field 410 can be a one-bit field or a three-bit field. When the PCI field 410 is a three-bit field (e.g., a three-bit field indicating an "additional PCI" index value), an example interpretation of the three bits is shown in Table 1:

[0048]

[0049] Table 1

[0050] In some embodiments, method 200 can be implemented as a method for triggering a TRP-specific RACH process through a PDCCH command, because a PDCCH command sent by one TRP (i.e., the second TRP) can trigger a RACH process for the same TRP (i.e., the second TRP). A separate PRACH resource can be configured according to each SSB index of each search space set. In these embodiments, at 204, a PDCCH command can be received in a search space set associated with the second TRP (e.g., in a search space set with "coresetPoolIndex=0"). More generally, a PDCCH command received in a search space set with "coresetPoolIndex=i"; where (i=0,1), can be used to trigger a RACH process toward the corresponding TRP associated with "coresetPoolIndex=i". The information indicated by the PDCCH command may include an SSB index and an RA preamble index, as described above. In some embodiments, the UE may receive a Type 1-PDCCH common search space (CSS) set configuration from the first TRP and for each non-serving cell configured in the "additionalPCIlist" before receiving the PDCCH command; and a random access response (RAR) window configuration. After sending the RACH preamble at 208, the UE may monitor the Type 1-PDCCH CSS set associated with the second TRP to obtain the RAR according to the Type 1-PDCCH CSS set configuration for the second TRP and according to the RAR window configuration for the second TRP.

[0051] Figure 5 Shown according to Figure 2 Another example timing diagram 500 of PDCCH command transmission for some embodiments of the illustrated method. The timing diagram assumes that the UE is in RRC_CONNECTED mode with the first TRP.

[0052] As shown, the first TRP (e.g., Figure 1 The first search space set (eg, "coresetPoolIndex=0") of the first TRP or TRP#1 shown may include search spaces 502, 504, and 506. The second TRP (eg, Figure 1The second search space set of the second TRP (e.g., "coresetPoolIndex = 1") shown (e.g., TRP#2) may include search spaces 508 and 510. The first set of SSBs (e.g., SSB#1, #2, and #3) may be associated with the first search space set (i.e., "coresetPoolIndex = 0"), and the second set of SSBs (e.g., SSB#4, #5, and #6) may be associated with the second search space set (i.e., "coresetPoolIndex = 1").

[0053] Also as shown, the base station (e.g., gNB) may send a PDCCH command 512 (i.e., DCI format 1_0) in the search space 508 of the second TRP. When receiving the PDCCH command, the UE may determine, for example, that the PDCCH command indicates <SSB#4, preamble 6>. When receiving this DCI, the UE may send preamble 6 associated with SSB#4 to obtain the initial TA towards the second TRP.

[0054] Figure 6 A second example method 600 for a UE to perform wireless communication is shown. Method 600 may be performed by the UE described with reference to Figure 1 or other UEs described herein. Method 600 may be performed using a processor, a set of transceivers (e.g., one or more transceivers), or other components of the UE.

[0055] At 602, method 600 may include operating the UE in RRC_CONNECTED mode with a first TRP (e.g., TRP#1).

[0056] At 604, method 600 may include receiving an indication of a set of one or more PRACH resources from the first TRP and for a second TRP configured in the "additionalPCIlist". The PRACH resources may be indicated according to an SSB or a channel state information reference signal (CSI-RS).

[0057] At 606, method 600 may include receiving at least one of a reference signal received power (RSRP) threshold of an SSB or an RSRP threshold of a CSI-RS from the first TRP.

[0058] At 608, method 600 may include, in response to determining that at least one of the RSRP threshold of the SSB or the RSRP threshold of the CSI-RS is satisfied, using the indication of the set of one or more PRACH resources to determine the PRACH resource to be used for a RACH procedure with the second TRP. The RACH procedure may be a CFRA procedure or a CBRA procedure.

[0059] At 610, method 600 may include sending a RACH preamble code on a PRACH resource to obtain an initial TA toward a second TRP.

[0060] Since the RACH procedure is based at least in part on the UE's determination that the RSRP threshold for the SSB or the RSRP threshold for the CSI-RS is met, the method 600 is considered a UE-triggered method.

[0061] In some embodiments of method 600, the UE may receive a Type 1-PDCCH CSS set configuration and a RAR window configuration from the first TRP and for the second TRP. After sending the RACH preamble at 608, the UE may monitor the Type 1-PDCCH CSS set associated with the second TRP to obtain the RAR according to the Type 1-PDCCH CSS set configuration for the second TRP and according to the RAR window configuration for the second TRP.

[0062] Method 600 may be embodied, extended, or modified in various ways, as described in the following paragraphs and elsewhere in this specification.

[0063] Figure 7 A third example method 700 for a UE to perform wireless communication is shown. The method 700 may be implemented by reference Figure 1 The method 700 may be performed by a UE described herein or by other UEs described herein. The method 700 may be performed using a processor, a set of transceivers (eg, one or more transceivers), or other components of a UE.

[0064] At 702, method 700 may include operating the UE in an RRC_CONNECTED mode with a first TRP (e.g., TRP#1).

[0065] At 704, method 700 may include receiving a MAC CE for unified TCI state activation from the first TRP.

[0066] At 706, method 700 may include, in response to determining that the TCI state activated by the MAC CE is associated with a search space or reference signal (e.g., a quasi-co-site (QCL) source reference signal (RS)) of the second TRP, triggering a RACH process to acquire an initial TA toward the second TRP.

[0067] Method 700 may be embodied, extended, or modified in various ways, as described in the following paragraphs and elsewhere in this specification.

[0068] As mentioned previously, inter-cell mobility delay may be reduced by providing pre-configuration of target candidate cells to the UE (ie, providing pre-configuration before issuing an L1 / L2 handover command), so that the delay of L1 / L2 based handover may be reduced.

[0069] Figure 8 An example ASN.1 message 800 for PCI-based pre-configuration of target candidate cells for L1 / L2-based handover is shown. Message 800 can be sent from a TRP in RRC_CONNECTED mode with the UE to a UE and received by the UE. The message can be received by the UE before the TRP sends a handover command to the UE, the target of which is a non-serving cell (or neighboring cell) in the "additionalPCIlist". As shown, a list of neighbor cell PCIs can be provided to the UE in an "additionalPCI-r17" information element (IE) 804 of an "SSB-MTC-AdditionalPCI-r17" IE (as in 3GPP Rel-170) 802. However, the "SSB-MTC-AdditionalPCI-r17" IE 802 can be enhanced to include the RRC configuration of one or more (or each) neighboring cells listed in the "additionalPCI-r17" IE 804. For example, the "SSB-MTC-AdditionalPCI-r17" IE 802 may be enhanced to include a cell configuration IE 806 (e.g., a "CellConfig-r18" IE). The cell configuration IE 806 may include the RRC configuration of one or more (or each) of the neighboring cells listed in the "additionalPCI-r17" IE 804. For the purposes of this description, "additionalPCI-r17" is an example of a PCI list (i.e., an example of "additionalPCIlist").

[0070] Fig. 9 An example cell group (CG)-based pre-configuration of target candidate cells for L1 / L2-based handover is shown. Based on the CG-based pre-configuration, the TRP in RRC_CONNECTED mode with the UE can send an RRC configuration including a list 900 of CGs (e.g., CG1, CG2, CG3, and CG4) to the UE. The RRC configuration may also include a configuration 902 of target candidate cells for L1 / L2-based handover, and an indicator 904 of the target candidate cell (e.g., an indicator of a primary serving cell (PCell) or a primary secondary serving cell (PSCell)).

[0071] CG-based pre-configuration of target candidate cells for L1 / L2-based handover can reduce overhead in some cases because configuration 902 can be provided for a group of cells (or component carriers (CCs)) - compared to PCI-based pre-configuration of target candidate cells for L1 / L2-based handover, which includes one configuration for each target candidate cell (or CC).

[0072] Fig.10 and Fig.11 An example of an inter-cell L1 / L2 handover trigger command is illustrated. Fig.10 An example MAC CE 1000 for triggering L1 / L2-based handover is shown. MAC CE 1000 may be a new MAC CE introduced to trigger L1 / L2-based handover (and especially L2-based handover) to a target cell. MAC CE 1000 may be identified by a MAC subheader with a dedicated logical channel ID (LCID).

[0073] In some cases, the MAC CE 1000 may have a fixed size and consist of a single octet of bits. The MAC CE 1000 (or octet) may include, for example, an additional PCI or CG-ID field 1002. The additional PCI or CG-ID field 1002 may include a PCI or CG-ID associated with the target cell. The additional PCI or CG-ID field 1002 may include a PCI or CG-ID associated with the target cell. In some cases, the PCI or CG-ID field 1002 may be a three-bit field. The MAC CE 1000 may also include a reserved bit 1004. In some cases, the reserved bit 1004 may be set to "0".

[0074] In some cases, PCI or CG-ID field 1002 may be a three-bit field. In some cases, reserved bit 1004 may be set to "0".

[0075] In some embodiments, the MAC CE 1000 may include additional fields for CG-based signaling. For example, the MAC CE 1000 may include a field indicating which cell of the CG is used as the PCell or PSCell after L1 / L2 handover.

[0076] Fig.11An example DCI format 1100 for triggering an L1 / L2-based handover (and in particular an L1-based handover) to a target cell is shown. In some embodiments, the DCI format 1100 may be an enhanced DCI format 1_0 and may be used to trigger an L1 / L2-based handover and / or RACH process. The DCI format 1100 may include an RA preamble index field 1102, an UL / SUL indicator field 1104, an SSB index field 1106, a PRACH mask index field 1108, an additional PCI or CG-ID field 1110, a handover (HO) trigger field 1112, one or more reserved bits 1114, and / or a CRC field 1116. The additional PCI or CG-ID field 1110 may include a PCI or CG-ID associated with the target cell. In some cases, the additional PCI or CG-ID field 1110 may be a three-bit field. The handover trigger field 1112 may indicate whether one or both of the L1 / L2-based handover or RACH process is triggered for the PCI or CG-ID identified in the additional PCI or CG-ID field 1110 (i.e., the handover trigger field 1112 may be used to distinguish between L1 / L2 inter-cell handover and inter-cell beam management (e.g., initial TA acquisition)). In some cases, the reserved bit 1004 may be set to "0".

[0077] In some cases, the handover trigger field 1112 may be an N-bit field (eg, N=2-bit field). Table 2 shows an example interpretation of various 2-bit values ​​of the handover trigger field 1112:

[0078]

[0079] Table 2

[0080] For both MAC CE-based and DCI-based L1 / L2-based handover to the target cell, upon receiving MAC CE or DCI, the UE may Figure 8 or Fig. 9 The preconfiguration described in the example above starts to apply the preconfigured target cell configuration.

[0081] Fig.12 A first example method 1200 for a base station to perform wireless communication is shown. The method 1200 may be implemented by reference Figure 1 The method 1200 may be performed by the first TRP described herein or by other TRPs described herein. The method 1200 may be performed using a processor, a set of transceivers (e.g., one or more transceivers), or other components of a base station.

[0082] At 1202, method 1200 can include communicating with a UE in an RRC_CONNECTED mode.

[0083] At 1204, method 1200 can include sending a PDCCH command (ie, DCI format 1_0). The PDCCH command can be sent in a search space set associated with at least one of a base station (or a first TRP (TRP#1)) or a second TRP (eg, TRP#2).

[0084] The method 1200 may be embodied, extended, or modified in various ways, as described elsewhere in this specification.

[0085] Fig.13 A second example method 1300 for a base station to perform wireless communication is shown. The method 1300 may be implemented by reference Figure 1 The method 1300 may be performed by the first TRP described herein or by other TRPs described herein. The method 1300 may be performed using a processor, a set of transceivers (e.g., one or more transceivers), or other components of a base station.

[0086] At 1302, method 1300 can include communicating with a UE in an RRC_CONNECTED mode.

[0087] At 1304, method 1300 may include sending an indication of a set of one or more PRACH resources to the UE and for a second TRP configured in the “additionalPCIlist.” The PRACH resources may be used for the second TRP configured in the “additionalPCIlist” and may be indicated based on the SSB or CSI-RS.

[0088] At 1306, method 1300 can include sending at least one of an RSRP threshold for SSB or an RSRP threshold for CSI-RS to the UE.

[0089] The method 1300 may be embodied, extended, or modified in various ways, as described elsewhere in this specification.

[0090] Fig.14 A third example method 1400 for a base station to perform wireless communication is shown. The method 1400 may be implemented by reference Figure 1 The method 1400 may be performed by the first TRP described herein or by other TRPs described herein. The method 1400 may be performed using a processor, a set of transceivers (e.g., one or more transceivers), or other components of a base station.

[0091] At 1402, method 1400 can include communicating with a UE in an RRC_CONNECTED mode.

[0092] At 1404, method 1400 may include sending a MAC CE for unified TCI state activation to the UE. The TCI state activated by the MAC CE may be associated with a search space or reference signal of the second TRP, and a RACH process may be triggered by the UE to acquire an initial TA toward the second TRP.

[0093] The method 1400 may be embodied, extended, or modified in various ways, as described elsewhere in this specification.

[0094] Embodiments contemplated herein include an apparatus having means for performing one or more elements of methods 200, 600, 700, 1200, 1300, or 1400. In the context of methods 200, 600, or 700, the apparatus may be, for example, an apparatus of a UE (such as wireless device 1602 as a UE, as described herein). In the context of methods 1200, 1300, or 1400, the apparatus may be, for example, an apparatus of a base station (such as network device 1620 as a base station, as described herein).

[0095] Embodiments contemplated herein include one or more non-transitory computer-readable media storing instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of methods 200, 600, 700, 1200, 1300, or 1400. In the context of methods 200, 600, or 700, the non-transitory computer-readable medium may be, for example, a memory of a UE (such as memory 1606 of wireless device 1602 as a UE, as described herein). In the context of methods 1200, 1300, or 1400, the non-transitory computer-readable medium may be, for example, a memory of a base station (such as memory 1624 of network device 1620 as a base station, as described herein).

[0096] Embodiments contemplated herein include an apparatus having logic, modules, or circuits for performing one or more elements of methods 200, 600, 700, 1200, 1300, or 1400. In the context of methods 200, 600, or 700, the apparatus may be, for example, an apparatus of a UE (such as wireless device 1602 as a UE, as described herein). In the context of methods 1200, 1300, or 1400, the apparatus may be, for example, an apparatus of a base station (such as network device 1620 as a base station, as described herein).

[0097] Embodiments contemplated herein include an apparatus having one or more processors and one or more computer-readable media that use or store instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of methods 200, 600, 700, 1200, 1300, or 1400. In the context of methods 200, 600, or 700, the apparatus may be, for example, an apparatus of a UE (such as wireless device 1602 as a UE, as described herein). In the context of methods 1200, 1300, or 1400, the apparatus may be, for example, an apparatus of a base station (such as network device 1620 as a base station, as described herein).

[0098] Embodiments contemplated herein include a signal as described in or associated with one or more elements of methods 200 , 600 , 700 , 1200 , 1300 , or 1400 .

[0099] Embodiments contemplated herein include a computer program or computer program product having instructions, wherein when the program is executed by a processor, the processor is caused to perform one or more elements of methods 200, 600, 700, 1200, 1300, or 1400. In the context of methods 200, 600, or 700, the processor may be a processor of a UE (such as processor 1604 of wireless device 1602 as a UE, as described herein), and the instructions may be located, for example, in the processor and / or on a memory of the UE (such as memory 1606 of wireless device 1602 as a UE, as described herein). In the context of methods 1200, 1300, or 1400, the processor may be a processor of a base station (such as processor 1622 of network device 1620 as a base station, as described herein), and the instructions may be located, for example, in the processor and / or on a memory of the base station (such as memory 1624 of network device 1620 as a base station, as described herein).

[0100] Fig.15 An example architecture of a wireless communication system 1500 according to an embodiment disclosed herein is illustrated. The description provided below is for an example wireless communication system 1500 operating in conjunction with the LTE system standard and / or the 5G or NR system standard provided in the 3GPP technical specifications.

[0101] like Fig.15As shown, wireless communication system 1500 includes UE 1502 and UE 1504 (however, any number of UEs may be used). In this example, UE 1502 and UE 1504 are illustrated as smartphones (e.g., handheld touch screen mobile computing devices capable of connecting to one or more cellular networks), but may also include any mobile or non-mobile computing device configured for wireless communication.

[0102] UE 1502 and UE 1504 may be configured to be communicatively coupled to RAN 1506. In an embodiment, RAN 1506 may be NG-RAN, E-UTRAN, etc. UE 1502 and UE 1504 utilize connections (or channels) (shown as connection 1508 and connection 1510, respectively) with RAN 1506, where each connection (or channel) includes a physical communication interface. RAN 1506 may include one or more base stations, such as base station 1512 and base station 1514, to implement connection 1508 and connection 1510.

[0103] In this example, connection 1508 and connection 1510 are air interfaces that enable such communicative coupling and may conform to the RAT used by RAN 1506, such as, for example, LTE and / or NR.

[0104] In some embodiments, UE 1502 and UE 1504 may also directly exchange communication data via side link interface 1516. UE 1504 is shown as being configured to access an access point (shown as AP 1518) via connection 1520. By way of example, connection 1520 may include a local wireless connection, such as a connection conforming to any IEEE 802.11 protocol, wherein AP 1518 may include In this example, AP 1518 may not be connected to another network (eg, the Internet) through CN 1524.

[0105] In an embodiment, UE 1502 and UE 1504 may be configured to communicate with each other or with base station 1512 and / or base station 1514 over a multi-carrier communication channel using orthogonal frequency division multiplexing (OFDM) communication signals according to various communication techniques, such as, but not limited to, orthogonal frequency division multiple access (OFDMA) communication techniques (e.g., for downlink communication) or single carrier frequency division multiple access (SC-FDMA) communication techniques (e.g., for uplink and ProSe or sidelink communication), although the scope of the embodiments is not limited in this respect. OFDM signals may include multiple orthogonal subcarriers.

[0106] In some embodiments, all or part of base station 1512 or base station 1514 may be implemented as one or more software entities running on a server computer as part of a virtual network. In addition, or in other embodiments, base station 1512 or base station 1514 may be configured to communicate with each other via interface 1522. In an embodiment where wireless communication system 1500 is an LTE system (e.g., when CN 1524 is an EPC), interface 1522 may be an X2 interface. The X2 interface may be defined between two or more base stations (e.g., two or more eNBs, etc.) connected to the EPC and / or between two eNBs connected to the EPC. In an embodiment where wireless communication system 1500 is an NR system (e.g., when CN 1524 is a 5GC), interface 1522 may be an Xn interface. The Xn interface is defined between two or more base stations (e.g., two or more gNBs, etc.) connected to the 5GC, between base station 1512 (e.g., gNB) and eNB connected to the 5GC, and / or between two eNBs connected to the 5GC (e.g., CN 1524).

[0107] RAN 1506 is shown as being communicatively coupled to CN 1524. CN 1524 may include one or more network elements 1526 configured to provide various data and telecommunication services to customers / subscribers (e.g., UE 1502 and users of UE 1504) connected to CN 1524 via RAN 1506. The components of CN 1524 may be implemented in one physical device or separate physical devices including components for reading and executing instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium).

[0108] In an embodiment, CN 1524 may be an EPC, and RAN 1506 may be connected to CN 1524 via an S1 interface 1528. In an embodiment, S1 interface 1528 may be divided into two parts: an S1 user plane (S1-U) interface, which carries traffic data between base station 1512 or base station 1514 and a serving gateway (S-GW); and an S1-MME interface, which is a signaling interface between base station 1512 or base station 1514 and a mobility management entity (MME).

[0109] In an embodiment, CN 1524 may be a 5GC, and RAN 1506 may be connected to CN 1524 via an NG interface 1528. In an embodiment, NG interface 1528 may be divided into two parts: an NG user plane (NG-U) interface, which carries traffic data between base station 1512 or base station 1514 and a user plane function (UPF); and an S1 control plane (NG-C) interface, which is a signaling interface between base station 1512 or base station 1514 and an access and mobility management function (AMF).

[0110] In general, the application server 1530 may be an element that provides applications that use Internet Protocol (IP) bearer resources with the CN 1524 (e.g., packet-switched data services). The application server 1530 may also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for the UE 1502 and UE 1504 via the CN 1524. The application server 1530 may communicate with the CN 1524 via the IP communication interface 1532.

[0111] Fig.16 A system 1600 for performing signaling 1640 between a wireless device 1602 and a network device 1620 according to an embodiment disclosed herein is illustrated. The system 1600 may be part of a wireless communication system as described herein. The wireless device 1602 may be, for example, a UE of a wireless communication system. The network device 1620 may be, for example, a base station (e.g., an eNB or a gNB) of a wireless communication system.

[0112] The wireless device 1602 may include one or more processors 1604. The processor 1604 may execute instructions to cause various operations of the wireless device 1602 to be performed, as described herein. The processor 1604 may include one or more baseband processors implemented using, for example, a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof for performing the operations described herein.

[0113] The wireless device 1602 may include a memory 1606. The memory 1606 may be a non-transitory computer-readable storage medium storing instructions 1608 (which may include, for example, instructions executed by the processor 1604). The instructions 1608 may also be referred to as program code or a computer program. The memory 1606 may also store data used by the processor 1604 and results computed by the processor.

[0114] The wireless device 1602 may include one or more transceivers 1610, which may include radio frequency (RF) transmitter and / or receiver circuitry that uses an antenna 1612 of the wireless device 1602 to facilitate signaling (e.g., signaling 1640) transmitted or received by the wireless device 1602 with other devices (e.g., network device 1620) according to a corresponding RAT.

[0115] The wireless device 1602 may include one or more antennas 1612 (e.g., one, two, four, or more). For implementations with multiple antennas 1612, the wireless device 1602 may take full advantage of the spatial diversity of such multiple antennas 1612 to send and / or receive multiple different data streams on the same time-frequency resources. This behavior may be referred to as, for example, MIMO behavior (referring to multiple antennas used at each of the transmitting device and the receiving device to implement this aspect). The MIMO transmission performed by the wireless device 1602 may be implemented based on pre-coding (or digital beamforming) applied at the wireless device 1602, which multiplexes the data streams across the antennas 1612 based on known or assumed channel characteristics, so that each data stream is received with appropriate signal strength relative to the other streams and at a desired location in the spatial domain (e.g., the location of the receiver associated with the data stream). Certain embodiments may use a single-user MIMO (SU-MIMO) approach (where data streams are all directed to a single receiver) and / or a multi-user MIMO (MU-MIMO) approach (where separate data streams may be directed to separate (different) receivers in different locations in the spatial domain).

[0116] In certain embodiments with multiple antennas, the wireless device 1602 may implement analog beamforming techniques whereby the phases of signals transmitted by the antennas 1612 are relatively adjusted so that the (joint) transmissions of the antennas 1612 are directional (this is sometimes referred to as beam steering).

[0117] The wireless device 1602 may include one or more interfaces 1614. The interfaces 1614 may be used to provide input to or output from the wireless device 1602. For example, a wireless device 1602 that is a UE may include an interface 1614, such as a microphone, a speaker, a touch screen, buttons, etc., to allow a user of the UE to provide input and / or output to the UE. Other interfaces of such a UE may consist of transmitters, receivers, and other circuits (e.g., in addition to the transceiver 1610 / antenna 1612 already described), which allow communication between the UE and other devices and may be performed according to known protocols (e.g., etc.) to perform the operation.

[0118] The wireless device 1602 may include one or more TA acquisition and handover modules 1616. The TA acquisition and handover module 1616 may be implemented via hardware, software, or a combination thereof. For example, the TA acquisition and handover module 1616 may be implemented as a processor, circuit, and / or instructions 1608 stored in the memory 1606 and executed by the processor 1604. In some examples, the TA acquisition and handover module 1616 may be integrated within the processor 1604 and / or the transceiver 1610. For example, the TA acquisition and handover module 1616 may be implemented by a combination of software components (e.g., executed by a DSP or general purpose processor) and hardware components (e.g., logic gates and circuits) within the processor 1604 or the transceiver 1610.

[0119] The TA acquisition and handover module 1616 may be used in various aspects of the present disclosure, such as Figures 1 to 14 The TA acquisition and handover module 1616 may be configured to, for example, acquire an initial TA of a TRP, receive a pre-configuration of a target candidate cell, or receive an L1 / L2 handover trigger command.

[0120] The network device 1620 may include one or more processors 1622. The processor 1622 may execute instructions to perform various operations of the network device 1620, as described herein. The processor 1622 may include one or more baseband processors implemented using, for example, a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0121] Network device 1620 may include memory 1624. Memory 1624 may be a non-transitory computer-readable storage medium storing instructions 1626 (which may include, for example, instructions executed by processor 1622). Instructions 1626 may also be referred to as program code or a computer program. Memory 1624 may also store data used by processor 1622 and results calculated by the processor.

[0122] The network device 1620 may include one or more transceivers 1628, which may include RF transmitter and / or receiver circuits that use an antenna 1630 of the network device 1620 to facilitate signaling (e.g., signaling 1640) to and / or from the network device 1620 and other devices (e.g., wireless device 1602) according to a corresponding RAT.

[0123] The network device 1620 may include one or more antennas 1630 (e.g., one, two, four, or more). In an embodiment with multiple antennas 1630, the network device 1620 may perform MIMO, digital beamforming, analog beamforming, beam steering, etc. as described.

[0124] The network device 1620 may include one or more interfaces 1632. The interface 1632 may be used to provide input to or output from the network device 1620. For example, the network device 1620 as a base station may include an interface 1632 consisting of a transmitter, a receiver, and other circuits (e.g., in addition to the transceiver 1628 / antenna 1630 already described), which enables the base station to communicate with other equipment in the core network and / or enables the base station to communicate with external networks, computers, databases, etc., for the purpose of operating, managing, and maintaining the base station or other equipment that can be operably connected to the base station.

[0125] The network device 1620 may include one or more mobility and handover modules 1634. The mobility and handover modules 1634 may be implemented via hardware, software, or a combination thereof. For example, the mobility and handover modules 1634 may be implemented as processors, circuits, and / or instructions 1626 stored in the memory 1624 and executed by the processor 1622. In some examples, the mobility and handover modules 1634 may be integrated within the processor 1622 and / or the transceiver 1628. For example, the mobility and handover modules 1634 may be implemented by a combination of software components (e.g., executed by a DSP or general purpose processor) and hardware components (e.g., logic gates and circuits) within the processor 1622 or the transceiver 1628.

[0126] The mobility and handover module 1634 may be used in various aspects of the present disclosure, such as Figures 1 to 14 The mobility and handover module 1634 may be configured to, for example, configure a RACH procedure for the wireless device 1602, send a pre-configuration for a target candidate cell to the wireless device 1602, or send a L1 / L2 handover trigger command to the wireless device 1602.

[0127] For one or more embodiments, at least one of the components set forth in one or more of the foregoing figures may be configured to perform one or more operations, techniques, processes, and / or methods as described herein. For example, a baseband processor as described herein in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein. For another example, circuits associated with a UE, a base station, a network element, etc. as described above in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein.

[0128] Unless otherwise expressly stated, any of the above embodiments may be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise form disclosed. In view of the above teachings, modifications and variations are possible or can be obtained from the practice of various embodiments.

[0129] Embodiments and implementations of the systems and methods described herein may include various operations that may be embodied in machine executable instructions to be executed by a computer system. A computer system may include one or more general or special purpose computers (or other electronic devices). A computer system may include hardware components that include specific logic components for performing operations; or may include a combination of hardware, software, and / or firmware.

[0130] It should be appreciated that the systems described herein include descriptions of specific embodiments. These embodiments may be combined into a single system, partially combined into other systems, separated into multiple systems, or otherwise divided or combined. In addition, it is contemplated that parameters, attributes, aspects, etc. of another embodiment may be used in one embodiment. For clarity, these parameters, attributes, aspects, etc. are described only in one or more embodiments, and it should be appreciated that these parameters, attributes, aspects, etc. may be combined with or substituted for parameters, attributes, aspects, etc. of another embodiment unless expressly stated herein.

[0131] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0132] Although the foregoing has been described in considerable detail for the sake of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles of the invention. It should be noted that there are many alternative ways to implement both the processes and the apparatus described herein. Therefore, the embodiments of the present invention should be regarded as illustrative rather than restrictive, and the specification is not limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A user equipment (UE), the user equipment (UE) comprising: A set of transceivers; and A processor, the processor being configured to: operating the UE in an RRC connected mode with a first transmit and receive point (TRP); receiving, via the set of transceivers, a physical downlink control channel (PDCCH) command in a search space set associated with at least one of the first TRP or the second TRP; determining, in response to information indicated by the PDCCH order, a physical random access channel (PRACH) resource to be used for a random access channel (RACH) procedure with the second TRP; as well as A RACH preamble is sent on the PRACH resource via the set of transceivers to obtain an initial timing advance (TA) toward the second TRP.

2. The UE according to claim 1, wherein: The first TRP and the second TRP share a physical cell ID (PCI); The search space set in which the PDCCH command is received is associated with the first TRP; as well as The information indicated by the PDCCH order includes a synchronization signal block (SSB) index and a random access (RA) preamble index associated with the SSB identified by the SSB index.

3. The UE according to claim 2, wherein: The PRACH resource is used for a contention-based random access (CBRA) procedure; The processor is configured to: Received via the set of transceivers a plurality of SSBs associated with the first TRP and the second TRP for each PRACH opportunity; as well as Multiple contention-based preambles per SSB; The SSB index identifies one of the plurality of SSBs; as well as The RA preamble index identifies one contention-based preamble among the plurality of contention-based preambles for each SSB identified by the SSB index.

4. The UE according to claim 2, wherein: The PRACH resources are used for a Contention Free Random Access (CFRA) procedure; and The processor is configured to: Received via the set of transceivers a plurality of SSBs associated with the first TRP and the second TRP for each PRACH opportunity; as well as Multiple contention-based preambles per SSB; as well as The PRACH resource is dynamically selected in response to the information indicated by the PDCCH order.

5. The UE according to claim 1, wherein: The first TRP and the second TRP are associated with different physical cell IDs (PCIs); The search space set in which the PDCCH command is received is associated with the first TRP; and The information indicated by the PDCCH command identifies the second TRP as the TRP associated with the triggered RACH process.

6. A UE according to claim 5, wherein the processor is configured to receive the PRACH resource configuration of each non-service cell in the "additionalPCIlist" from the first TRP via the group of transceivers before receiving the PDCCH command, wherein each non-service cell in the "additionalPCIlist" is configured with an "additional PCI" index in the "additionalPCIlist".

7. A UE according to claim 5, wherein the PDCCH command includes a set of fields, the set of fields including a one-bit field identifying a non-serving cell associated with the second TRP, and the non-serving cell is associated with a set of active transmission configuration indicator (TCI) states of the second TRP.

8. The UE according to claim 5, wherein the PDCCH command includes a set of fields, the set of fields including a three-bit field identifying a non-service cell associated with the second TRP, the three-bit field indicating an "additional PCI" index value of a non-service cell in a set of non-service cells identifying the second TRP.

9. The UE according to claim 8, wherein: The set of non-serving cells is configured by radio resource control (RRC) signaling; A first non-serving cell in the set of non-serving cells is associated with a set of active transmission configuration indicator (TCI) states; and At least a second non-serving cell in the set of non-serving cells is not associated with the set of active TCI states.

10. The UE of claim 1, wherein the RACH procedure is a contention-free random access (CFRA) procedure or a contention-based random access (CBRA) procedure triggered by the PDCCH order.

11. The UE of claim 1, wherein the search space set is associated with "coresetPoolIndex=0".

12. The UE according to claim 1, wherein: The search space set is associated with the second TRP; and The information indicated by the PDCCH order includes a synchronization signal block (SSB) index and a random access (RA) preamble index associated with the SSB identified by the SSB index.

13. The UE according to claim 12, wherein: The processor is configured to: For each non-serving cell configured in "additionalPCIlist", receiving from the first TRP via the set of transceivers before receiving the PDCCH command Type 1 - PDCCH common search space (CSS) set configuration; and Random Access Response (RAR) window configuration; and After sending the RACH preamble, according to the Type 1-PDCCH CSS set configuration for the second TRP and according to the RAR window configuration for the second TRP, the Type 1-PDCCH CSS set associated with the second TRP is monitored to obtain the RAR.

14. The UE according to claim 1, wherein: The processor is configured to receive from the first TRP before receiving a handover command targeting a non-serving cell included in the "additionalPCIlist" The "additionalPCIlist"; and The radio resource control (RRC) configuration of each non-serving cell included in the "additionalPCIlist".

15. The UE according to claim 1, wherein: The processor is configured to receive a radio resource control (RRC) configuration from the first TRP via the set of transceivers prior to receiving a handover command targeting a non-serving cell, the radio resource control (RRC) configuration comprising, List of cell groups; as well as For each cell group in the list of cell groups, Configuration of target candidate cells for handover based on layer 1 / layer 2 (L1 / L2); as well as An indicator of the target candidate cell.

16. A UE according to claim 1, wherein the processor is configured to receive a medium access control (MAC) control element (CE) (MAC CE) from the first TRP triggering a layer 1 / layer 2 (L1 / L2) based handover to a target cell, the MAC CE including a physical cell ID (PCI) or a cell group ID (CG-ID) associated with the target cell.

17. The UE according to claim 1, wherein: The processor is configured to receive, via the set of transceivers and from the first TRP, downlink control information (DCI), the downlink control information (DCI) having a format including: Additional Physical Cell ID (PCI) or Cell Group ID (CG-ID) field; and A handover trigger field, wherein the handover trigger field indicates whether to trigger a layer 1 / layer 2 (L1 / L2) based handover or one or both of the RACH process for the PCI or CG-ID identified in the additional PCI or CG-ID field.

18. A user equipment (UE), the user equipment (UE) comprising: A set of transceivers; and A processor, the processor being configured to: operating the UE in an RRC connected mode with a first transmit and receive point (TRP); receiving, via the set of transceivers, from the first TRP and for a second TRP configured in "additionalPCIlist", an indication of a set of one or more physical random access channel (PRACH) resources per synchronization signal block (SSB) or channel state information reference signal (CSI-RS); receiving, via the set of transceivers and from the first TRP, at least one of a reference signal received power (RSRP) threshold for SSB or an RSRP threshold for CSI-RS; determining, in response to determining that at least one of the RSRP threshold for SSB or the RSRP threshold for CSI-RS is satisfied, a PRACH resource to be used for a random access channel (RACH) procedure with the second TRP using the indication of the set of one or more PRACH resources; as well as A RACH preamble is sent on the PRACH resource via the set of transceivers to obtain an initial timing advance (TA) toward the second TRP.

19. The UE according to claim 18, wherein: The processor is configured to: receiving from the first TRP and for the second TRP via the set of transceivers, Type 1 - Physical Downlink Control Channel (PDCCH) Common Search Space (CSS) set configuration; and Random Access Response (RAR) window configuration; and After sending the RACH preamble, a Type 1-PDCCH CSS set is monitored according to the Type 1-PDCCH CSS set configuration and according to the RAR window configuration.

20. A user equipment (UE), the user equipment (UE) comprising: A set of transceivers; and A processor, the processor being configured to: operating the UE in an RRC connected mode with a first transmit and receive point (TRP); receiving, via the set of transceivers and from the first TRP, a medium access control (MAC) control element (CE) for unified transmit configuration indicator (TCI) state activation (MAC CE); In response to determining that the TCI state activated by the MAC CE is associated with a search space or reference signal of a second TRP, a random access channel (RACH) process is triggered to acquire an initial timing advance (TA) toward the second TRP.

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