Beam management during satellite switch with resynchronization

Abstract

To implement channel monitoring, a user equipment (UE) receives, in a serving cell, a quasi co-location (QCL) configuration for monitoring a channel in a target cell with a same cell identity as the serving cell (1901); receives, in the serving cell, an indication of a time related to a change in coverage of at least one of the serving cell or the target cell (1905); and starts the monitoring of the channel in the target cell according to the QCL configuration and at the indicated time (1965).

Description

PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC BEAM MANAGEMENT DURING SATELLITE SWITCH WITH RESYNCHRONIZATION REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of the filing date of provisional U.S. Patent Application No.63 / 616,616 entitled “Beam Management During Satellite Switch with Resynchronization,” filed on December 30, 2023. The entire content of the provisional application is hereby expressly incorporated herein by reference FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to wireless communications and, more particularly, to improving the switching between non-terrestrial network (NTN) cells, at a user equipment (UE). BACKGROUND

[0003] This background description is provided for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] The objectives behind developing the fifth generation (5G) technology include providing a unified framework for such types of communication as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC).

[0005] The 5G technology relies primarily on legacy terrestrial networks. However, the 3rd Generation Partnership Project (3GPP) organization has proposed to extend 5G communications to non-terrestrial networks (NTNs) with 5G new radio (NR) technologies, or with the Long-Term- Evolution (LTE) technologies tailored for the Narrowband Internet-of-Thing (NB-IoT) or the enhanced Machine Type Communication (eMTC) scenarios. In an NTN, an RF transceiver is mounted on a satellite, an uncrewed aircraft system (UAS) such as a drone, balloon, plane, or another suitable apparatus. For simplicity, the discussion below refers to all such apparatus asPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC satellites. In addition to satellites, an NTN can include the sat-gateways that connect the Non- Terrestrial Network to a public data network, feeder links between sat-gateways and satellites, service links between satellites, and inter-satellite links (ISL) when satellites form constellations.

[0006] A satellite can belong to one of several types based on altitude, orbit, and beam footprint size. The types include Low-Earth Orbit (LEO) satellite, Medium-Earth Orbit (LEO) satellite, Geostationary Earth Orbit (GEO) satellite, UAS platform (including High Altitude Platform Station, HAPS), and High Elliptical Orbit (HEO) satellite. GEO satellites are also known as the Geosynchronous Orbit (GSO) satellites, and LEO / MEO satellites are also known as the non-GSO (NGSO) satellites.

[0007] A GSO satellite can communicate with one or several sat-gateways deployed over a satellite targeted coverage area (e.g. a region or even a continent). A non-GSO satellite at different times can communicate with one or several serving sat-gateways. An NTN is designed to ensure service and feeder link continuity between successive serving sat-gateways, with sufficient time duration to proceed with mobility anchoring and hand-over.

[0008] A satellite can support a transparent or a regenerative (with on board processing) payload, and typically generates several beams for a given service area bounded by the field of view. The footprints of the beams typically have an elliptic shape and depend on the on-board antenna configuration and the elevation angle. For a transparent payload implementation, a satellite can apply RF filtering and frequency conversion and amplification, and not change the waveform signal. For a regenerative payload implementation, a satellite can apply RF filtering, frequency conversion and amplification, demodulation and decoding, routing, and coding / modulation. This approach is effectively equivalent to implementing most of the functions of a base station, e.g., a gNB.

[0009] In these and other scenarios, a large number of UEs may need to frequently perform a handover from one cell to another cell due to rapid satellite movement. To mitigate the impact of the long service interruption time and the signaling overhead due to these types of handovers, different satellites can use the same Physical Cell Identity (PCI) when serving / covering the same geographical area. This can prevent UEs from triggering handover procedures due to the change of service-link (i.e., the link between the satellite and UE).PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0010] However, although the same-PCI approach creates the effect of a UE receiving service from the same cell after switching to a new satellite, the UE still needs to re-synchronize and align with the new beam provided by the new satellite. Yet performing beam alignment after switching to the new satellite may significantly disrupt the service continuity, and may even trigger a random access procedure (which makes the interruption of service continuity more severe). It is desirable therefore to make beam alignment in these scenarios more efficient. SUMMARY

[0011] Generally speaking, the techniques of this disclosure allow a connected UE to switch between the cells sharing the same identity such as PCI with minimum service interruption time.

[0012] An example embodiment of these techniques is a channel monitoring method implemented in a user equipment (UE). The method comprises receiving, in a serving cell, a quasi co-location (QCL) configuration for monitoring a channel in a target cell with a same cell identity as the serving cell; receiving, in the serving cell, an indication of a time related to a change in coverage of at least one of the serving cell or the target cell; and starting the monitoring of the channel in the target cell according to the QCL configuration and at the indicated time.

[0013] Another example embodiment of these techniques is configuration method implemented in a radio access network (RAN) node. The method comprises transmitting, to a user equipment (UE) and in a serving cell of the UE, an indication of a time related to a change in coverage of at least one of (a) the serving cell or (b) a target cell with a same cell identity as the serving cell; and transmitting, to the UE and in the serving cell, a quasi co-location (QCL) configuration for monitoring a channel in the target cell, the QCL configuration based on a determination of which reference signal is quasi-co-located with a transmission on the channel, for the UE in the target cell.

[0014] Yet another example embodiment of these techniques is a device comprising a transceiver and configured to implement one of the methods above. BRIEF DESCRIPTION OF THE DRAWINGSPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0015] Fig.1A is a block diagram of an example wireless communication system in which a user device and a base station associated with an NTN can implement the beam management techniques of this disclosure;

[0016] Fig.1B is a block diagram of an example base station in which a centralized unit (CU) and a distributed unit (DU) that can operate in the system of Fig.1A;

[0017] Fig.2A is a block diagram of an example protocol stack according to which the UE of Fig.1A communicates with base stations;

[0018] Fig.2B is a block diagram of an example protocol stack according to which the UE of Fig.1A communicates with a CU and a DU;

[0019] Fig.3A is a block diagram of an example NTN node with transparent payload implementation;

[0020] Fig.3B is a block diagram of an example NTN node with transparent payload implementation, in which a base station connects to multiple satellites via the same sat-gateway;

[0021] Fig.4A illustrates an exemplary user plane protocol stack for use with the architecture of Fig.3A;

[0022] Fig.4B illustrates an exemplary control plane protocol stack for use with the architecture of Fig.3A;

[0023] Fig.5 is a block diagram illustrating an example scenario in which a stationary UE switches from one satellite to another with a resynchronization procedure, without performing a handover (HO) procedure;

[0024] Fig.6 is a messaging diagram of an example scenario in which a UE in the connected state receives a TCI state activation indication shortly before a satellite switch with resynchronization takes place;

[0025] Fig.7 is a messaging diagram of an example scenario in which a UE in the connected state receives a PDCCH configuration including a deactivated TCI identity and activates the deactivated TCI identity shortly before a satellite switch with resynchronization takes place;PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0026] Fig.8 is a messaging diagram of an example scenario in which a UE in the connected state receives a PDSCH configuration including deactivated TCI states and activates one of the deactivated TCI states shortly before the satellite switch with resynchronization takes place;

[0027] Fig.9 is a messaging diagram of an example scenario in which a UE in the connected state receives a CSI measurement configuration including deactivated CSI-RS resources and activates the CSI-RS resources right before the satellite switch with resynchronization takes place.

[0028] Fig.10 is a messaging diagram of an example scenario in which a UE in the connected state receives an SSB index or an SSB time offset value that facilitates monitoring of the PDCCH at the UE after the satellite switch with resynchronization takes place.

[0029] Fig.11 is a flow diagram of an example method that can be implemented in a UE in the connected state, for activating a TCI State for the PDCCH monitoring, upon receiving a downlink control information;

[0030] Fig.12 is a flow diagram of an example method that can be implemented in a UE in the connected state, for receiving the PDCCH configuration including a deactivated TCI state identity and determining when to activate the deactivated TCI state identity;

[0031] Fig.13 is a flow diagram of an example method that can be implemented in a UE in the connected state, for receiving the PDSCH configuration including deactivated TCI states, and determining when to activate the deactivated TCI states;

[0032] Fig.14 is a flow diagram of an example method that can be implemented in a UE in the connected state, for receiving the CSI measurement configuration including deactivated CSI RS resources, and determining when to activate the deactivated CSI RS resources;

[0033] Fig.15 is a flow diagram of an example method that can be implemented in a UE in the connected state, for receiving an SSB index or an SSB time offset applicable after a satellite switch with resynchronization;

[0034] Fig.16 is a flow diagram of an example method that can be implemented in a BS, for activating a TCI State for PDCCH monitoring in a satellite switch with resynchronization procedure;PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0035] Fig.17A is a flow diagram of an example method that can be implemented in a BS, for configuring a deactivated TCI state identity in the PDCCH configuration, for activation during or after a satellite switch with resynchronization procedure;

[0036] Fig.17B is a flow diagram of an example method that can be implemented in a BS, for configuring deactivated TCI states in the PDSCH configuration, for activation during or after a satellite switch with resynchronization procedure;

[0037] Fig.17C is a flow diagram of an example method that can be implemented in a BS, for configuring deactivated CSI-RS resources in the CSI measurement configuration, for activation during or after a satellite switch with resynchronization procedure;

[0038] Fig.18 is a flow diagram of an example method that can be implemented in a BS, for configuring an SSB index or an SSB time offset applicable to a UE after the satellite switch with resynchronization takes place;

[0039] Fig.19 is a flow diagram of an example channel monitoring method in a UE; and

[0040] Fig.20 is a flow diagram of an example configuration method in a RAN node. DETAILED DESCRIPTION OF THE DRAWINGS

[0041] As discussed in more detail below, a user equipment (UE) and / or a network node of a radio access network (RAN) can use the techniques of this disclosure for beam managing during a switch between with synchronization between NTN (e.g., satellite) cells.

[0042] Referring first to Fig.1A, an example wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The base stations 104 and 106 can operate in a RAN 105 connected to the core network (CN) 110. The CN 110 can be implemented as an evolved packet core (EPC) 111 or a fifth generation (5G) core (5GC) 160, for example. The CN 110 can also be implemented as a sixth generation (6G) core in another example.

[0043] The base station 104 covers a cell 124 and a cell 125, and the base station 106 covers a cell 126. In an NTN implementation, the cells 124 and 125 can correspond to different satellites but share the same cell identifier. If the base station 104 is a gNB, the cell 124 is an NR cell. If the base station 104 is an ng-eNB or eNB, the cell 124 is an evolved universal terrestrial radio access (E- UTRA) cell. Similarly, if the base station 106 is a gNB, the cell 126 is an NR cell, and if the basePATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC station 106 is an ng-eNB or eNB, the cell 126 is an E-UTRA cell. The cells 124 and 126 can be in the same Radio Access Network Notification Areas (RNA) or different RNAs. In general, the RAN 105 can include any number of base stations, and each of the base stations can cover one, two, three, or any other suitable number of cells. The UE 102 can support at least a 5G NR (or simply, “NR”) or E-UTRA air interface to communicate with the base stations 104 and 106. Each of the base stations 104, 106 can connect to the CN 110 via an interface (e.g., S1 or NG interface). The base stations 104 and 106 also can be interconnected via an interface (e.g., X2 or Xn interface) for interconnecting NG RAN nodes.

[0044] Among other components, the EPC 111 can include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. The SGW 112 in general is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to one or more external packet data networks, e.g., an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network. The 5GC 160 includes a User Plane Function (UPF) 162 and an Access and Mobility Management Function (AMF) 164, and / or Session Management Function (SMF) 166. Generally speaking, the UPF 162 is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions.

[0045] As illustrated in Fig.1A, the base station 104 supports a cell 124, and the base station 106 supports a cell 126. The cells 124 and 126 can partially overlap, so that the UE 102 can select, reselect, or hand over from one of the cells 124 and 126 to the other. To directly exchange messages or information, the base station 104 and base station 106 can support an X2 or Xn interface. In general, the CN 110 can connect to any suitable number of base stations supporting NR cells and / or EUTRA cells.

[0046] As discussed in detail below, the UE 102 and / or the RAN 105 may utilize the techniques of this disclosure when the radio connection between the UE 102 and the RAN 105 is suspended, e.g., when the UE 102 operates in an inactive or idle state of the protocol for controlling radio resources between the UE 102 and the RAN 105. For clarity, the examples below refer to the RRC_INACTIVE or RRC_IDLE state of the RRC protocol.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0047] The base station 104 is equipped with processing hardware 130 that can include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable memory storing instructions that the one or more general-purpose processors execute. Additionally or alternatively, the processing hardware 130 can include special-purpose processing units. The processing hardware 130 in an example implementation includes a processor 132 to process data that the base station 104 will transmit in the downlink direction, or process data received by the base station 104 in the uplink direction. The processing hardware 130 can also include a transmitter 136 configured to transmit data in the downlink direction. The processing hardware further can include a receiver 134 configured to receive data in the uplink direction. The base station 106 can include generally similar components. In particular, components 140, 142, 144, and 146 of the base station 106 can be similar to the components 130, 132, 134, and 136, respectively.

[0048] The UE 102 is equipped with processing hardware 150 that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or special-purpose processing units. The processing hardware 150 in an example implementation includes a processor 152 to process data that the UE 102 will transmit in the uplink direction, or process data received by UE 102 in the downlink direction. The processing hardware 150 can also include a transmitter 156 configured to transmit data in the downlink direction. The processing hardware further can include a receiver 154 configured to receive data in the uplink direction.

[0049] Fig.1B depicts an example distributed or disaggregated implementation of any one or more of the base stations 104, 106. In this implementation, the base station 104, 106 includes a central unit (CU) 172 and one or more distributed units (DUs) 174. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and a computer- readable memory storing machine-readable instructions executable on the general-purpose processor(s), and / or special-purpose processing units. For example, the CU 172 can include a PDCP controller, a RRC controller and / or a RRC inactive controller. In some implementations, the CU 172 can include a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures. In further implementations, the CU 172 does not include an RLC controller.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0050] Each of the DUs 174 also includes processing hardware that can include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or special-purpose processing units. For example, the processing hardware can include a MAC controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure), and / or an RLC controller configured to manage or control one or more RLC operations or procedures. The process hardware can also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0051] In some embodiments, the RAN 105 supports Integrated Access and Backhaul (IAB) functionality. In some implementations, the DU 174 operates as an IAB-node, and the CU 172 operates as an IAB-donor. In some embodiments, the RAN 105 supports Non-Terrestrial Network (NTN) functionality.

[0052] In some implementations, the CU 172 can include a logical node CU-CP 172A that hosts the control plane part of the PDCP protocol of the CU 172. The CU 172 can also include logical node(s) CU-UP 172B that hosts the user plane part of the PDCP protocol and / or Service Data Adaptation Protocol (SDAP) protocol of the CU 172. The CU-CP 172A can transmit control information (e.g., RRC messages, F1 application protocol messages), and the CU-UP 172B can transmit the data packets (e.g., SDAP PDUs or Internet Protocol packets).

[0053] The CU-CP 172A can be connected to multiple CU-UP 172B through the E1 interface. The CU-CP 172A selects the appropriate CU-UP 172B for the requested services for the UE 102. In some implementations, a single CU-UP 172B can connect to multiple CU-CP 172A through the E1 interface. The CU-CP 172A can connect to one or more DU 174s through an F1-C interface. The CU-UP 172B can connect to one or more DU 174 through the F1-U interface under the control of the same CU-CP 172A. In some implementations, one DU 174 can connect to multiple CU-UP 172B under the control of the same CU-CP 172A. In such implementations, the connectivity between a CU-UP 172B and a DU 174 is established by the CU-CP 172A using Bearer Context Management functions.

[0054] Fig.2A illustrates, in a simplified manner, an example protocol stack 200 according to which the UE 102 can communicate with an eNB / ng-eNB or a gNB (e.g., one or more of the base stations 104, 106).PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0055] In the example stack 200, a physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A in turn provides RLC channels to an EUTRA PDCP sublayer 208 and, in some cases, to an NR PDCP sublayer 210. Similarly, the NR PHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides data transfer services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 in turn can provide data transfer services to Service Data Adaptation Protocol (SDAP) 212 or a radio resource control (RRC) sublayer (not shown in Fig.2A). The UE 102, in some implementations, supports both the EUTRA and the NR stack as shown in Fig.2A, to support handover between EUTRA and NR base stations and / or to support DC over EUTRA and NR interfaces. Further, as illustrated in Fig.2A, the UE 102 can support layering of NR PDCP 210 over EUTRA RLC 206A, and SDAP sublayer 212 over the NR PDCP sublayer 210.

[0056] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets (e.g., from an Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer 208 or 210) that can be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer 206A or 206B) that can be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure for simplicity refers to both SDUs and PDUs as “packets.”

[0057] On a control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 can provide signaling radio bearers (SRBs) or RRC sublayer (not shown in Fig.2A) to exchange RRC messages or non-access-stratum (NAS) messages, for example. On a user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 can provide Data Radio Bearers (DRBs) to support data exchange. Data exchanged on the NR PDCP sublayer 210 can be SDAP PDUs, Internet Protocol (IP) packets or Ethernet packets.

[0058] Fig.2B illustrates, in a simplified manner, an example protocol stack 250, which the UE 102 can communicate with a DU (e.g., DU 174) and a CU (e.g., CU 172). The radio protocol stack 200 is functionally split as shown by the radio protocol stack 250 in Fig.2B. The CU at any of the base stations 104 or 106 can hold all the control and upper layer functionalities (e.g., RRC 214, SDAP 212, NR PDCP 210), while the lower layer operations (e.g., NR RLC 206B, NR MAC 204B,PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC and NR PHY 202B) are delegated to the DU. To support connection to a 5GC, NR PDCP 210 provides SRBs to RRC 214, and NR PDCP 210 provides DRBs to SDAP 212 and SRBs to RRC 214.

[0059] Fig.3A illustrates a certain type of NTN deployment 300A referred to as transparent payload architecture, which involves a satellite gateway 302 and a “transparent” satellite 304 for extending the range of the Uu interface. The satellite 304 implements a frequency conversion and a Radio Frequency (RF) amplifier in both the uplink and downlink directions. The satellite function is similar to that of an analogue RF repeater. As a result, the satellite 304 repeats the Uu radio interface from the feeder link (between the NTN gateway and the satellite) to the service link (between the satellite and the UE) in the downlink direction and vice versa in the uplink direction. The Satellite Radio Interface (SRI) on the feeder link is the Uu, and the NTN gateway 302 supports all necessary functions to forward the signal of the Uu interface. The NTN gateway 302 can be placed at the same site where the base station (e.g., eNB, gNB) 104 locates, or be connected to the base station 104 at a distance via a wired link. It is also possible to connect more than one NTN gateway to a base station. Different transparent satellites may be connected to the same base station on the ground, via the same NTN gateway, or via different NTN gateways. Fig.3B illustrates the case 300B where two different satellites (304 and 306) are connected to the same base station 104 via the same NTN gateway 302, and these two satellites (304 and 306) are covering the Earth surface using two different Physical Cell IDs (PCIs).

[0060] An NTN user plane protocol stack 400A involving the UE 102, the satellite 304, the NTN gateway 302, the NR base station (i.e., gNB) 104, and the UPF 114 is illustrated in Fig.4A. The diagram of the NTN user plane protocol stack is similar to that of the terrestrial network (TN), with the addition of two new nodes, the satellite 304 and the NTN gateway 302, being placed in the middle of the NR-Uu interface. Similarly, an NTN control plane protocol stack 400B illustrated in Fig.4B is also similar to that of the terrestrial network.

[0061] In terms of the satellite moving pattern, there are three types of service links that are supported in NTN: (i) Earth-fixed: provisioned by beam(s) continuously covering the same geographical areas all the time (e.g., the case of GEO / GSO satellites); (ii) Quasi-Earth-fixed: provisioned by beam(s) covering one geographic area for a limited period and a different geographic area during another period (e.g., the case of LEO / MEO satellites capable of usingPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC steerable beams); and (iii) Earth-moving: provisioned by beam(s) whose coverage area slides over the Earth surface (e.g., the case of LEO / MEO satellites using fixed or non-steerable beams).

[0062] With LEO / MEO satellites, the eNB can provide either quasi-Earth-fixed cell coverage or Earth-moving cell coverage. With GEO satellites, the eNB can provide Earth fixed cell coverage.

[0063] Although the transparent payload architecture illustrated in Figs.3A / 3B is the current focus of the 3GPP development, the regenerative payload architecture that installs the BS functions on the satellite is also a possible NTN deployment in the future. In such an architecture, the Uu only exists between the satellite and the UE. In general, the techniques of this disclosure can apply to the transparent payload architecture as well as the regenerative payload architecture.

[0064] Due to the nature of the long propagation delay in NTN, the HO interruption time in NTN is usually much longer than that in the terrestrial network (TN). Moreover, as certain satellites (e.g., LEO or MEO satellites) are constantly moving and so do the cells (on the Earth) projected by these satellites, there could be a large number of UEs that need to be handed over to another cell at any time. As a result, a HO “signaling storm,” or a sudden spike in the volume of transmissions, is significantly more likely in NTN than in TN. To reduce the impact of long HO interruption time and mitigate the HO signaling storm in an NTN, 3GPP proposed to reduce the number of overall handover attempts by allowing a deployment scenario referred to as “satellite switch with re- synchronization.” In this deployment scenario, an upcoming cell of a LEO or MEO satellite can use the same PCI as the cell that was previously serving the same geographic area, which means that a LEO / MEO cell may need to change its PCI while moving from one geographic area to another.

[0065] Fig.5 is an example satellite-switch-with-resynchronization scenario 500, in which a stationary UE switches from one satellite to another without performing a HO procedure, because both satellites provide / project a cell in the same geographical area (at different times) using the same PCI (or, more generally, the same cell identifier). In this example, initially at time T1, the UE 102 is served by the cell provided by the satellite 304, and the Synchronization Signal Blocks (SSBs) emitted from satellite 304 indicates the PCI of the cell at time T1 (denoted as PCIT1) is k. It is further assumed that at time T1, the UE 102 monitors the PDCCH transmitted from the antenna port quasi co-located (QCL) with the antenna port transmitting beam b1 (i.e., UE 102 receivesPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC services from the antenna port providing beam b1), where beam b1can be either the beam offering SSBs or the beam offering Channel State Information Reference Signals (CSI-RSs).

[0066] At a later time T2, the satellite 304 is moving away from the UE 102 and stops serving the geographic area where the UE is located. Meanwhile, another satellite 306 managed by the same BS moves in and starts serving the same geographic area using the same PCI (i.e., PCIT2= k). Because the goal of the satellite switch with resynchronization procedure is to minimize the service interruption time, the UE 102 generally expects no (or almost zero) coverage gap around the time when the satellite switch occurs.

[0067] However, even if the satellites provide the respective coverage seamlessly without triggering a handover procedure, without proper beam management / alignment, the UE 102 may not be able to monitor / decode the PDCCH immediately after switching over to the new beam b3of the new satellite 306. This is because the UE 102 maintains the original PDCCH configuration and applies this PDCCH configuration to incorrectly decode the PDCCH. More particularly, the UE 102 may rely on assumptions about channel properties that were applicable only when the UE 102 received service from the satellite 304 via the beam b1. Because the network cannot guarantee service continuity if the UE 102 cannot decode the PDCCH after a satellite switch, it is desirable to provide the UE 102 with an updated PDCCH configuration and / or beam configurations, including Transmission Configuration Indicator (TCI) state configurations (based on the new beam setup for the satellite 306), before the satellite switch occurs.

[0068] Next, several example scenarios in which a UE and / or a RAN perform the techniques of this disclosure for configuring a UE with the beam(s) and / or the TCI state(s) for the PDCCH monitoring in a satellite switch with resynchronization procedure are discussed with reference to Figs.6-10. Generally speaking, similar events in Figs.6-10 are labeled with reference numbers that have the same lower-order digits. For example, event 604 is similar to event 704, event 610 is similar to events 710, 810, and 910, and event 620 is similar to events 720 and 820. For brevity, similar events are not discussed in detail in each instance, but the discussion of a certain event with reference to one of the figures also applies to similar events in other figures.

[0069] For simplicity, the term “idle state” is used below to refer to the RRC_IDLE state and / or RRC_INACTIVE state. The term “connected state” refers to the RRC_CONNECTED state.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0070] Fig.6 is a messaging diagram 600 of an example scenario 600 in which the UE 102 in the connected state receives a TCI state activation indication shortly before a satellite switch with resynchronization takes place. In Fig.6, the UE 102 initially connects to the NTN cell 124 managed by the BS 104 through the satellite 304. While remaining 602 in the connected state, the UE 102 receives 606, in the NTN cell 124, a system information message including a t-Service value of a first cell (i.e., NTN Cell 124), where t-Service denotes the time at which the first cell will stop serving the area. The UE 102 may also receive 604, in the NTN cell 124, via the system information, a t-ServiceStart value of a second cell (i.e., NTN cell 125) denoting the time upon which the second cell will start serving the area. The UE 102 can receive 604, 606 the t-Service value and the t-ServiceStart value in a single message.

[0071] In one implementation, the time instance indicated by t-ServiceStart is always earlier than the time instance indicated by t-Service, which corresponds to the deployment scenario in which the incoming cell and outgoing cell of the same PCI overlap with each other in terms of the cell coverage. In another implementation, the time instance indicated by t-ServiceStart is later than the time instance indicated by t-Service, which corresponds to the deployment scenario in which there is a coverage gap between the incoming cell and the outgoing cell of the same PCI. In one implementation, the BS 104 provisions satellite switch with resynchronization (a satellite switch that does not involve a handover, with the PCI unchanged) using a particular Information Element (IE) in the system information. In this case, if the UE 102 only receives the t-Service value but does not receive the t-ServiceStart value from the BS 104, the UE 102 assumes the time instance at which the second cell (i.e., the cell 125) will start serving the area is identical to the time instance upon which the first cell (i.e., Cell 124) will stop serving the area (i.e., t-ServiceStart is equivalent to t-Service).

[0072] The UE 102 optionally also receives 610, via the system information, a dedicated RRC message, or a DL MAC CE, an ssb-positionsInBurst IE indicating / including the time domain positions of the SSBs transmitted by the satellite 306 in an SS-burst as defined, for example, in 3GPP TS 38.213, clause 4.1. The ssb-positionsInBurst IE that indicates the time domain positions of the SSBs transmitted by the satellite 306 can be the same as or different than the ssb- positionsInBurst IE that indicates the time domain positions of the SSBs transmitted by the satellite 304.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0073] Similarly, the UE 102 optionally receives 620, via a dedicated RRC message, a csi- MeasConfig IE including the configuration for at least one non-zero power CSI-RS resource (i.e., nzp-CSI-RS-Resource IE) used by the cell 125. The configuration for the at least one non-zero power CSI-RS resource can contain the information elements shown below, as defined in 3GPP TS 38.331, clause 6.3.2: NZP-CSI-RS-Resource ::= SEQUENCE { nzp-CSI-RS-ResourceId NZP-CSI-RS-ResourceId, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (-8..15), powerControlOffsetSS ENUMERATED{db-3, db0, db3, db6} OPTIONAL, -- Need R scramblingID ScramblingId, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, -- Cond PeriodicOrSemiPersistent cl-InfoPeriodicCSI-RS TCI-StateId OPTIONAL, -- Cond Periodic }PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0074] At a later time but before the cell 124 stops serving the area (i.e., before t-Service), the UE 102 receives 630 a PDSCH configuration (e.g., a pdsch-Config IE) including at least one TCI State configuration (e.g., TCI-State) referring to the SSB or the non-zero power CSI-RS resource transmitted / used by the cell 125.The TCI state configuration can contain the information elements shown below, as defined in 3GPP TS 38.331, clause 6.3.2. For the at least one TCI State configuration provided in the event 630, either the csi-rs IE refers to one of the non-zero power CSI-RS resources configured for the cell 125, or the ssb IE refers to SSB transmitted by the Cell 125. TCI-State ::= SEQUENCE { tci-StateId TCI-StateId, qcl-Type1 QCL-Info, qcl-Type2 QCL-Info OPTIONAL, -- Need R ..., } QCL-Info ::= SEQUENCE { cell ServCellIndex OPTIONAL, -- Need R bwp-Id BWP-Id OPTIONAL, -- Cond CSI-RS-Indicated referenceSignal CHOICE { csi-rs NZP-CSI-RS-ResourceId, ssb SSB-Index }, qcl-Type ENUMERATED {typeA, typeB, typeC, typeD}, ... }PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0075] After receiving 630 the TCI State configuration, the UE 102 receives 640 a PDCCH configuration including at least one of the TCI-State configured for the cell 125. An example format of the PDCCH configuration, which the UE 102 can receive 640, is illustrated below. In this example, the PDCCH configuration adds one TCI-State (i.e., TCI-StateId 2) configured for the cell 125 and removes all other TCI-States configured for the cell 124 (i.e., TCI-StateId 1). As a result, upon receiving the PDCCH configuration, the UE 102 can immediately activate TCI-StateId 2 and begin to monitor the PDCCH based on the TCI state configuration associated with TCI-StateId 2. This is because TCI-StateId 2 is only the TCI-State available after the UE 102 receives 640 the PDCCH configuration.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0076] In one implementation, the PDCCH configuration is associated with a flag / value / indication that delays the application of the PDCCH configuration until the moment when the satellite switch with resynchronization takes place. In another implementation, the ControlResourceSet IE is associated with a flag / value / indication that delays the application / compliance of the ControlResourceSet configuration until the moment when the satellite switch with resynchronization takes place. Yet in another implementation, the tci-StatesPDCCH- ToAddList IE or the tci-StatesPDCCH-ToReleaseList IE is associated with a flag / value / indication that delays the application of the tci-StatesPDCCH-ToAddList or tci-StatesPDCCH-ToReleaseList until the moment when the satellite switch with resynchronization takes place. In one implementation, if the PDCCH configuration / ControlResourceSet IE / tci-StatesPDCCH-ToAddList IE is associated with a flag / value / indication, the UE 102 delays the application / compliance of the PDCCH configuration / ControlResourceSet / tci-StatesPDCCH-ToAddList for X time units, where the value X can be provided by the BS 104 or can be a constant value hardcoded within the UE 102.

[0077] In another implementation, the UE 102 receives 640 the PDCCH configuration in theexample format below. In this example, the PDCCH configuration adds one TCI State (i.e., TCI-StateId 2) configured for the cell 125 without removing the other TCI States configured for Cell124 (i.e., TCI-StateId 1, assuming it was configured for the cell 124 before). As a result, uponPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC receiving the PDCCH configuration, the UE 102 has multiple TCI States available and has to rely on receiving of a MAC CE designated to conveying TCI State Indication for a UE-specific PDCCH (see event 650 below). An example format for this downlink MAC CE is defined in 3GPP TS 38.321, clause 6.1.3.15).

[0078] Immediately or shortly before the satellite switch with resynchronization takes place (i.e., immediately or shortly before t-Service), the UE 102 receives 650 a TCI State Indication for UE- specific PDCCH MAC CE indicating ‘TCI-StateId 2’ as the TCI State to be activated. In response to the receiving 650 of the downlink MAC CE, the UE 102 monitors 660 the PDCCH in the cell 125 using the CSI-RS or SSB resource indicated by TCI-StateId 2. Before starting to monitor 660 the PDCCH transmitted in the cell 125, the UE 102 may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS 104, and / or based on the propagation delay difference the UE estimates / calculates.

[0079] In one implementation, the UE 102 starts 660 the monitoring of the PDCCH at t-Service or at t-ServiceStart, rather than immediately upon receiving 650 the TCI State Indication for UE- specific PDCCH MAC CE. In another implementation, the UE 102 delays the starting 660 of the PDCCH monitoring for X time units after receiving 650 the TCI State Indication for UE-specific PDCCH MAC CE, where the value X can be provided by the BS 104 or can be a constant value hardcoded within the UE 102.

[0080] In some implementations, to indicate to the UE 102 that that the reception 650 need not coincide with the start 660 of the PDCCH monitoring, the BS 104 uses a downlink MAC CEPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC dedicated to conveying a TCI state for non-immediate application at the UE. This MAC CE can have a dedicated Logic Channel Identity (LCID), so that the UE 102 can distinguish this MAC CE from a MAC CE for immediate application of a TCI state at the UE. In some implementations, the MAC CE dedicated to conveying a TCI state for non-immediate application has the same format as the “regular” MAC CE for conveying a TCI state for immediate application. In any case, the UE 102 can determine that MAC CE is of the type that calls for the UE 102 waiting until t-Service or t- ServiceStart to apply the indicated TCI state.

[0081] In the example scenario of Fig.6, t-ServiceStart occurs later than t-Service. In other words first the cell 124 stops 670 serving the area at t-Service, and then the cell 125 starts 680serving the area at t-ServiceStart. Because the UE 102 already started 660 (assuming 660 and 670take place at the same time) monitoring the PDCCH based on the up-to-date channel property assumption of the TCI-StateId 2, the UE 102 can successfully decode the PDCCH transmitted in the cell 125 after t-ServiceStart, and thus the UE 102 can successfully communicate 690 in the cell 125 after t-ServiceStart.

[0082] Next, Fig.7 illustrates an example scenario 700 in which the UE 102 in the connected state receives a PDCCH configuration including a deactivated TCI identity and actives the deactivated TCI identity immediately or shortly before the satellite switch with resynchronization takes place. The scenario 700 is generally similar to the scenario 600, with the differences discussed below. In Fig.7, while remaining 702 in the connected state, the UE 102 receives 706, in the NTN Cell 124, a system information message including a t-Service value, where t-Service indicates the time at which the first cell will stop serving the area in which the UE 102 operates, and the second cell will start serving the area.

[0083] After the UE 102 receives 730 a PDSCH configuration (e.g., a pdsch-Config IE) including at least one TCI State referring to the SSB or the non-zero power CSI-RS resource transmitted / used in the cell 125, the UE 102 further receives 742 a PDCCH configuration including a reference to one of the TCI State Identities (e.g., TCI-StateIds) configured 730 for the cell 125. The PDCCH configuration thus identifies the TCI State which the UE 102 is to activate later (when the UE 102 receives 742 the PDCCH configuration, this TCI State is deactivated). In an example implementation illustrated below, the PDCCH configuration includes, within the ControlResourceSet IE, an IE that indicates which TCI state in the list of TCI states the UE 102PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC should activate for PDCCH monitoring in the new NTN cell. In this example implementation, the IE is named TCI-StateID-toBeActivated and includes an integer value identifying the TCI-StateId of TCI state to be activated. In another implementation, one of the TCI-StateId values within the tci- StatesPDCCH-ToAddList structure is followed (or preceded) by a flag indicating that the UE 102 is to activate this particular TCI state, while the remaining TCI-StateId values within the tci- StatesPDCCH-ToAddList structure are not associated with this flag.

[0084] Subsequently, at time t-Service, the cell 124 stops 770 serving the area, and the cell 125 starts 780 serving the area. Unlike the scenario of Fig.6, here the UE 102 receives 706 only the t- Service value, and does not receive a t-ServiceStart value of the event 604, for example. At this time, the UE 102 activates 762 the TCI state corresponding to the TCI-StateId which the PDCCH configuration specified 742. The UE 102 begins 762 to monitor the PDCCH transmitted in the cell 125 using the channel property assumption of the CSI-RS or the SSB corresponding to the activated TCI-StateId. Prior to the monitoring 762 of the PDCCH transmitted in the cell 125, the UE 102 may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS 104, and / or based on the propagation delay difference the UE 102 estimates or calculates. In one implementation, when the UE 102 activates 762 a TCI-StateId, the UE 102 additionally deactivates all the other TCI-StateIds configured in the PDCCH configuration.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0085] Next, Fig.8 is illustrated an example scenario 800 in which the UE 102 operating in the connected state receives a PDSCH configuration including deactivated TCI states, and actives one of the deactivated TCI states immediately or shortly before the satellite switch with resynchronization takes place. The scenario 800 is generally similar to the scenario 600, with the differences discussed below.

[0086] Here, after receiving 820 the csi-MeasConfig IE containing the configuration for at least one non-zero power CSI-RS resource used by the cell 125, the UE 102 receives 832 a PDSCH configuration including at least one TCI State referring to the SSB or the non-zero-power CSI-RS resource in the cell 125. The received 832 PDSCH configuration indicates which at least one TCI State the UE 102 is to activate later, generally similar to the technique of Fig.7 and particularly the event 742. To this end, the PDSCH configuration can include an appropriate flag, indicator, or value for example.

[0087] One such example implementation is illustrated below. Here, the TCI State to be activated (e.g., TCI-StateId 2) contains an enumerated-type IE (e.g., toBeActivated{true}) within the TCI-State IE, while the TCI State not being deactivated (e.g., TCI-StateId 1 and 5) contains no enumerated-type IE within the TCI-State IE.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PCIn another implementation, another IE (e.g., a TCI-StateID-toBeActivated indicator, containing an integer value pointing to the TCI-StateId) within the pdsch-Config IE indicates the TCI State to be activated.

[0088] The UE 102 then can receive 840 a PDCCH configuration including one or more the TCI- StateIds pointing to the TCI States configured 832 for the cell 125 (i.e., pointing to the TCI States being deactivated via the event 832).

[0089] Subsequently, at time t-ServiceStart, the cell 125 starts 880 serving the area. At time t- Service (which is later than t-ServiceStart in this example), the cell 124 stops 870 serving the area. At time t-Service, the UE 102 activates 862 the TCI state corresponding to the TCI-StateId referenced in the PDCCH configuration and associated with a flag (in this example, toBeActivated) received 832 in the PDSCH configuration. The UE 102 monitors 862 the PDCCH transmitted in the cell 125 using the channel property assumption of the CSI-RS or the SSB referred by the TCI- StateId being activated. Before the monitoring 862 of the PDCCH in the cell 125, the UE 102 may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS 104, and / or based on the propagation delay difference the UE 102 estimates or calculates.

[0090] In one implementation, when the UE 102 activates 862 the TCI state, the UE 102 at this time also deactivates all the other TCI states configured 840 in the PDCCH configuration. In one implementation, the UE 102 activates 862 the TCI State associated with a flag or indicated by an indication / value in the PDSCH configuration, at t-ServiceStart instead of at t-Service.

[0091] Now referring to Fig.9, in an example scenario900, the UE 102 operating 902 in the connected state receives a CSI measurement configuration including deactivated CSI-RS resources,PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC and activates the CSI-RS resources immediately or shortly before the satellite switch with resynchronization takes place. The scenario 900 is generally similar to the scenario 700, with the differences discussed below.

[0092] In Fig.9, after receiving 910 the ssb-positionsInBurst IE indicating / including the time domain positions of the SSBs transmitted by the satellite 306, the UE receives 922 the csi- MeasConfig IE including at least one non-zero-power CSI-RS resource used in the cell 125. The csi-MeasConfig IE identifies at least one non-zero-power CSI-RS resource which the UE 102 is to activate later and for monitoring PDCCH in the target NTN cell. Generally similar to the implementations discussed above with reference to Figs.7 and 8, the csi-MeasConfig IE includes a flag or another suitable indicator to specify the relevant non-zero-power CSI-RS resource. One such example implementation is illustrated below. Here, the non-zero-power CSI-RS resource for activation (NZP-CSI-RS-ResourceId 2) is associated with an enumerated-type IE (e.g., toBeActivated{true}) within the NZP-CSI-RS-Resource IE, while the non-zero-power CSI-RS resources which the BS 104 is not instructing the UE 102 to activate (e.g., NZP-CSI-RS-ResourceId 3) are not associated with an enumerated-type IE within the NZP-CSI-RS-Resource IE. More specifically, here the entry in the list corresponding to NZP-CSI-RS-ResourceId 2 includes the toBeActivated flag, whereas the remaining entries in the list do not include the toBeActivated flag.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0093] In another implementation, the csi-MeasConfig IE includes another IE to specify the non- zero-power CSI-RS resource to be activated. For example, the csi-MeasConfig IE can include a NZP-CSI-RS-toBeActivated IE containing an integer value pointing to the NZP-CSI-RS-ResourceId to be activated.

[0094] The UE 102 then receives 930 a PDSCH configuration including at least one TCI State referring to the non-zero-power CSI-RS resource used in the cell 125, and then receives 944 a PDCCH configuration including one of the TCI-StateIds corresponding to the TCI-States referring to the NZP-CSI-RS-Resource used in the cell 125.

[0095] At time t-Service, the cell 124 stops 970 serving the area, and the cell 125 starts 980 serving the area. At this time, the UE 102 activates 962 the NZP-CSI-RS-Resource specified 922 in the csi-MeasConfig as discussed above. The UE 102 also selects the TCI-StateId (specified 944 in the PDCCH configuration) corresponding to the TCI-State that refers to the NZP-CSI-RS-Resource the UE 102 is activating. The UE 102 begins 962 to monitor the PDCCH transmitted in the cell 125 using the channel property assumption of the CSI-RS referred by the TCI State / TCI-StateId being activated. Similar to the examples above, the UE 102 may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS 104, and / or based on the propagation delay difference estimated / calculated by the UE 102. In one implementation, when the UE 102 activates 962 a TCI-StateId (and the corresponding TCI state), the UE 102 also deactivates all the other TCI-StateIds (and the corresponding TCI states) configured 944 in the PDCCH configuration.

[0096] Fig.10 is a messaging diagram of an example scenario 1000 in which the UE 102 in the connected state receives an SSB index or an SSB time offset value that facilitates he monitoring of the PDCCH after a satellite switch with resynchronization takes place. The scenario 1000 is generally similar to the scenario 700, with the differences discussed below. Here, after receiving 1010 the ssb-positionsInBurst IE indicating / including the time domain positions of the SSBs transmitted by the satellite 306, the UE receives 1012 an SSB index or an SSB time offset value for application after t-Service.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0097] At time t-Service, the cell 124 stops 1070 serving the area, and the cell 125 starts 1080 serving the area. At this time, the UE 102 synchronizes 1064 with the SSB transmitted in the cell 125 based on the timing difference implied by the SSB index or the SSB time offset provided 1012 earlier, and monitors 1064 PDCCH by using the channel property assumption of the SSB. Before synchronizing 1064 with the SSB transmitted in cell 125, the UE 102 may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS 104, and / or based on the propagation delay difference the UE 102 estimates or calculates.

[0098] For clarity, several example methods which the UE 102 or the base station 104 can implement are discussed next with reference to Figs.11-20. In these diagrams, dashed lines are used to indicate that the corresponding block is optional, in at least some of the implementations of the method. Generally speaking, similar events in Figs.11-20 are labeled with reference numbers that have the same lower-order digits. For example, event 1110 is similar to event 1210, and event 1263 is similar to event 1363.

[0099] Each of the methods of Figs.11-20 can be implemented as software instructions stored on a computer-readable medium and executable by one or more processors.

[0100] Fig.11 is a flow diagram of an example method 1100 that can be implemented in a UE (e.g., UE 102 in this disclosure), for activating a TCI State for the PDCCH monitoring, upon receiving a downlink control information. Initially, at block 1102, the UE receives, from a BS, via the system information or via a dedicated RRC message, a first time instance at which the first cell will stop serving the area. The UE may also receive, at block 1104, from the BS, via the system information or via a dedicated RRC message, a second time instance at which the second cell having the same PCI as the first cell will start serving the area, where the second time instance can be earlier or later than the first time instance. In some implementations, the UE receives both the first time instance and the second time instance within a same message, at block 1103.

[0101] At block 1110, the UE may receive, from the BS, via the system information or via a dedicated RRC message, the time domain positions of the SS-blocks transmitted in the second cell (i.e., ssb-PositionsInBurst). At block 1112, the UE can receive an SSB index or offset, which the UE can apply at t-Service.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0102] At block 1120, the UE receives, from the BS, via a dedicated RRC Message, a CSI Measurement configuration including at least one non-zero power CSI-RS resource used by the second cell. The UE further receives, at block 1130, from the BS, a PDSCH configuration including at least one TCI State referring to the SSB or the non-zero power CSI-RS resource used by the second cell. The UE also receives, at block 1140, from the BS, via a dedicated RRC Message, a PDCCH configuration including at least one of the TCI-StateIds corresponding to the TCI States configured at block 1130 for the second cell. The PDCCH configuration may further include a flag / indication instructing the UE to delay the application of the PDCCH configuration for a certain period of time, such as until the first time instance or until the second time instance (if signaled earlier).

[0103] At block 1150, when the UE has been configured with more than one TCI-StateIds via the PDCCH configuration, the UE receives, from the BS, via a downlink MAC CE, an indication indicating which TCI-StateId configured in the PDCCH configuration is to be activated upon the first or the second time instance (if being signaled earlier). The downlink MAC CE may further instruct the UE to delay the activation of the indicated TCI-StateId for a certain period of time, until the first time instance, or until the second time instance (if the second time instance is signaled earlier).

[0104] At block 1160, after receiving the PDCCH configuration or after receiving the downlink MAC CE for TCI-StateId activation, the UE activates, the TCI-StateId indicated at block 1140 or 1150. In one implementation, instead of executing the block 1150 immediately after receiving the PDCCH configuration or receiving the downlink MAC CE for TCI-StateId activation, the UE delays the application of the PDCCH configuration by a certain period of time, or waits until the first time instance or until the second time instance (if signaled earlier). After that, at block 1161, the UE monitors the PDCCH transmitted in the second cell using the channel property assumption of the SSB or CSI-RS resource referred by the activated TCI-StateId.

[0105] Fig.12 is a flow diagram of an example method 1200 that can be implemented by a UE (e.g., UE 102 in this disclosure) in the connected state, for receiving the PDCCH configuration including a deactivated TCI state identity, and determining when to activate the deactivated TCI state identity. The flow diagram in Fig.12 is similar to that in Fig.11, with the differences discussed below. After receiving a PDSCH configuration from the BS at block 1230, the UEPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC receives, at block 1242, from the BS, a PDCCH configuration including one of the TCI-StateIds configured for the second cell, where the one TCI-StateId is to be activated later (i.e., being deactivated at the moment) and is associated with a flag or indicated by an indication / value.

[0106] At block 1262, at the first time instance or the second time instance (if signaled earlier), the UE activates the one TCI-StateId associated with the flag or indicated by the indication / value, for PDCCH monitoring. At this time, the UE may also deactivate all the other TCI-StateIds except the one being activated. The UE then monitors, at block 1263, the PDCCH transmitted in the second cell using the channel property assumption of the SSB or the CSI-RS resource referred by the TCI-StateId being activated in 1262.

[0107] Fig.13 is a flow diagram of an example method 1300 that can be implemented by a UE (e.g., UE 102 in this disclosure) in the connected state, for receiving the PDSCH configuration including deactivated TCI states, and determining when to activate the deactivated TCI states. The flow diagram in Fig.13 is similar to that in Fig.11, with the differences discussed below. After receiving a CSI measurement configuration from the BS at block 1320, the UE receives, at block 1332, from the BS, a PDSCH configuration including at least one TCI State referring to the SSB or the non-zero power CSI-RS resource used by the second cell, where the at least one TCI State is to be activated later (i.e., being deactivated at the moment) and is associated with a flag or indicated by an indication / value. The UE then receives, at block 1340, a PDCCH configuration including one of the TCI-StateIds corresponding to the TCI-States associated with a flag or indicated by an indication / value.

[0108] At block 1362, at the first time instance or the second time instance (if signaled earlier), the UE activates the TCI-StateId configured at block 1340,whose TCI State is associated with a flag or indicated by an indication / value, for PDCCH monitoring. At this time, the UE may also deactivate all the other TCI-StateIds except the one being activated. The UE monitors, at block 1363, the PDCCH transmitted in the second cell using the channel property assumption of the SSB or the CSI-RS resource referred by the TCI-StateId being activated at block 1362.

[0109] Fig.14 is a flow diagram of an example method 1400 that can be implemented by a UE (e.g., UE 102 in this disclosure) in the connected state, for receiving the CSI measurement configuration including deactivated CSI RS resources, and determining when to activate the deactivated CSI RS resources. The flow diagram in Fig.14 is similar to that in Fig.11, with thePATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC differences discussed below. After receiving from the BS the time domain positions of the SS- blocks transmitted in the second cell, the UE receives, at block 1422, from the BS, a CSI Measurement configuration including at least one non-zero power CSI-RS resource used by the second cell, where the at least one non-zero power CSI-RS resource is associated with a flag or indicated by an indication / value.

[0110] At block 1430, the UE receives from the BS, a PDSCH configuration including at least one TCI State referring to the non-zero power CSI-RS resource used by the second cell, where the at least one TCI State is to be activated later. The UE then receives, at block 1444, a PDCCH configuration including one of the TCI-StateIds corresponding to the TCI States referring to the non-zero power CSI-RS resources used by the second cell.

[0111] At block 1462, at the first time instance or the second time instance (if signaled earlier), the UE activates, the TCI-StateId configured at block 1444, whose TCI State refers to the non-zero power CSI-RS resource used by the second cell, for PDCCH monitoring. At this time, the UE may also deactivate all the other TCI-StateIds except the one being activated. At block 1463, the UE monitors the PDCCH transmitted in the second cell using the channel property assumption of the CSI-RS resource referred by the TCI-StateId being activated at block 1462.

[0112] Fig.15 is a flow diagram of an example method 1500 that can be implemented by a UE (e.g., UE 102 in this disclosure) in the connected state, for receiving an SSB index or an SSB time offset applicable after the satellite switch with resynchronization. The flow diagram in Fig.15 is similar to that in Fig.11, with the differences discussed below. After receiving from the BS the time domain positions of the SS-blocks transmitted in the second cell, the UE receives, at block 1512, from the BS, an SSB index and / or an SSB time offset value to be applied after the first time or the second time instance (if signaled earlier).

[0113] At block 1564, at the first time instance or the second time instance (if signaled earlier), the UE synchronizes with the SSB based on the timing difference implied by the SSB index or the SSB time offset provided at block 1512, and monitors the PDCCH in the second cell using the channel property assumption of the SSB being synchronized. Prior to synchronizing with the SSB transmitted in the second cell, the UE may need to shift the downlink frame / subframe / slot timing based on a timing offset value provided by the BS, and / or based on the propagation delay difference estimated / calculated by the UE.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0114] Next, Fig.16 illustrates an example method 1600 that can be implemented by a BS (e.g., BS 104 in this disclosure), for activating a TCI State for the PDCCH monitoring in a satellite switch with resynchronization procedure. At block 1604, the BS transmits, to a UE, via the system information or via a dedicated RRC message, a first time instance at which the first cell will stop serving the area. The BS may also transmit, at block 1606, to the UE, via the system information or via a dedicated RRC Message, a second time instance upon which a second cell having the same PCI as the first cell will start serving the area. In some implementations, the BS transmits the first time instance and the second instance in a single message.

[0115] When the BS does not send to the UE the second time instance but sends other information relevant to the satellite switch with resynchronization procedure, the UE can infer that the second cell of the same PCI (as the first cell) will start serving the area at the same time when the first cell will stop serving the area. At block , the BS may transmit, at block 1610, to the UE, the time domain positions of the SSBs transmitted in the second cell.

[0116] At block 1640, the BS transmits, to the UE, via a dedicated RRC Message, a PDCCH configuration including more than one TCI-StateIds, where each TCI-StateId corresponds to a TCI State configuration provided in a PDSCH configuration. At block 1645, the BS determines which reference signal (i.e., which SSB or CSI-RS resource) is quasi-co-located with the PDCCH DMRS transmission for the UE in the second cell. The determination at block 1645 can be based on a CSI report from the UE, the GNSS information of the UE, and / or the ephemeris information of the out- going satellite as well as the in-coming satellite. Finally, at block 1650, the BS transmits, to the UE, via a downlink MAC CE, an indication of which TCI-StateId configured in the PDCCH configuration is to be activated after X time units, or after the first or the second time instance (if being signaled earlier).

[0117] Fig.17A is a flow diagram of an example method 1700A that can be implemented by a BS (e.g., BS 104 in this disclosure), for configuring a deactivated TCI state identity in the PDCCH configuration, where the deactivated TCI state identity is to be activated in a satellite switch with resynchronization procedure. The flow diagram in Fig.17A is similar to that in Fig.16, with the differences discussed below. After transmitting (at block 1710) to the UE the time domain positions of the SSBs transmitted in the second cell, the BS determines, at block 1745, which reference signal (i.e., which SSB or CSI-RS resource) is quasi-co-located with the PDCCH DMRS transmission forPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC the UE in the second cell. After that, the BS transmits, at block 1742, to the UE, a PDCCH configuration indicating (via a flag / indication / value) which TCI-StateId is to be activated (i.e., being deactivated at the moment) after the first or the second time instance (if being signaled earlier), where the TCI-StateId being deactivated refers to the reference signal (i.e., the SSB or CSI- RS resource) determined at block 1745.

[0118] Fig.17B is a flow diagram of an example method 1700B that can be implemented by a BS (e.g., BS 104 in this disclosure), for configuring deactivated TCI states in the PDSCH configuration, where the deactivated TCI states are to be activated in a satellite switch with resynchronization procedure. The flow diagram in Fig.17B is similar to that in Fig.17A, with the differences discussed below. After determining (at block 1745) which reference signal is quasi-co- located with the PDCCH DMRS transmission for the UE in the second cell, the BS transmits, at block 1732, to the UE, a PDSCH configuration indicating (via a flag / indication / value) which TCI- State is to be activated (i.e., being deactivated at the moment) after the first or the second time instance (if being signaled earlier), where the TCI State being deactivated refers to the reference signal determined at block 1745.

[0119] Fig.17C is a flow diagram of an example method 1700C that can be implemented by a BS (e.g., BS 104 in this disclosure), for configuring deactivated CSI-RS resources in the CSI measurement configuration, where the deactivated CSI-RS resources are to be activated in a satellite switch with resynchronization procedure. The flow diagram in Fig.17C is similar to that in Fig.16, with the differences discussed below. After transmitting (at block 1710) to the UE the time domain positions of the SSBs transmitted in the second cell, the BS determines, at block 1745, which CSI-RS resource is quasi-co-located with the PDCCH DMRS transmission for the UE in the second cell. After that, the BS transmits, at block 1722, to the UE, a CSI measurement configuration indicating (via a flag / indication / value) which non-zero-power CSI resource is to be activated (i.e., being deactivated at the moment) after the first or the second time instance (if being signaled earlier).

[0120] Fig.18 is a flow diagram of an example method 1800 that can be implemented by a BS (e.g., BS 104 in this disclosure), for configuring an SSB index or an SSB time offset applicable to a UE after the satellite switch with resynchronization takes place. The flow diagram in Fig.18 is similar to that in Fig.16, with the differences discussed below. After transmitting (at block 1810) toPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC the UE the time domain positions of the SSBs transmitted in the second (target) cell, the BS determines, at block 1845, which SSB is quasi-co-located with the PDCCH DMRS transmission for the UE in the second (target) cell. After that, the BS transmits, at block 1812, to the UE, an SSB index and / or an SSB time offset value to be applied after the first time or the second time instance (if being signaled earlier).

[0121] Fig.19 is a flow diagram of an example channel monitoring method 1900, which can be implemented in a UE such as the UE 102.

[0122] At block 1902, the UE receives, in a serving cell, a QCL configuration for monitoring a channel in a target cell, where the serving cell and the target cell have the same PCI (see, e.g., events 630, 730, 832, 930, 1012; see also blocks 1112, 1120, 1130, 1140, 1212, 1220, 1230, 1242, 1312, 1320, 1332, 1430, 1412, 1422, 1430, 1444, 1510). The QCL configuration in various embodiments and / or scenarios can include can configure multiple TCI states, include an indication of SSB positions of the target cell, include a configuration of at least one non-zero power CSI-RS resource for the target cell, include a PDSCH configuration including a configuration for the plurality of TCI states or the configuration of the at least one non-zero power CSI-RS resource for the target cell, or a PDCCHconfiguration including at least one TCI state identifier.

[0123] At block 1905, the UE receives, in the serving cell, an indication of time related to a change in coverage in the area where the UE is located, for the serving cell and / or the target cell (see, e.g., events 604, 606, 650, 706, 804, 906, 1006; see also blocks 1102, 1104, 1112, 1202, 1206, 1212, 1304, 1306, 1312, 1404, 1406, 1412, 1504, 1506).

[0124] At block 1965, the UE receives starts the monitoring of the channel in the target cell according to the QCL configuration, and at the indicated time (see, e.g., events 660, 762, 862, 962, 1064; see also blocks 1161, 1263, 1363, 1463, 1564).

[0125] Fig.20 is a flow diagram of an example configuration method 2000 that ca be implemented in a RAN node such as the base station 104.

[0126] At block 2001, the RAN node transmits, to a UE and in a serving cell, an indication of time related to a change in coverage in the area where the UE is located, for the serving cell and / or a target cell (see, e.g., events 604, 606, 650, 706, 804, 906, 1006; see also blocks 1102, 1104, 1112, 1202, 1206, 1212, 1304, 1306, 1312, 1404, 1406, 1412, 1504, 1506).PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0127] At block 2007, the RAN node transmits, to the UE and in the serving cell, a QCL configuration for monitoring a channel in the target cell, where the QCL configuration is based on a determination of which reference signal is quasi co-located with a transmission on the channel (see, e.g., events 630, 730, 832, 930, 1012; see also blocks 1645, 1745, 1845).

[0128] The following list of examples reflects a variety of the embodiments explicitly contemplated by the present disclosure.

[0129] Example 1. A channel monitoring method implemented in a user equipment (UE), the method comprising: receiving, in a serving cell, a quasi co-location (QCL) configuration for monitoring a channel in a target cell with a same cell identity as the serving cell; receiving, in the serving cell, an indication of a time related to a change in coverage of at least one of the serving cell or the target cell; and starting the monitoring of the channel in the target cell according to the QCL configuration and at the indicated time.

[0130] Example 2. The method of example 1, wherein: the QCL configuration configures a plurality of Transmission Configuration Indication (TCI) states; the method further comprising: receiving, in the serving cell and subsequently to receiving the QCL configuration, an indication of a TCI state in the plurality of TCI states, for the monitoring of the channel.

[0131] Example 3. The method of example 2, wherein: the receiving of the indication of the time includes the receiving of the indication of the TCI state; and the starting of the monitoring of the channel in the target cell occurs immediately upon the receiving of the indication of the TCI state.

[0132] Example 4. The method of example 2, wherein: the receiving of the indication of the time includes the receiving of the indication of the TCI state; and the starting of the monitoring of the channel in the target cell occurs after a predetermined amount of time after the receiving of the indication of the TCI state.

[0133] Example 5. The method of example 4, wherein: the receiving of the indication of the time further includes receiving an offset value, wherein the predetermined amount of time after the receiving of the indication of the TCI state is based on the received offset value.

[0134] Example 6. The method of example 2, further comprising: subsequently to the receiving of the indication of the TCI state, delaying the starting of the monitoring until the indicated time.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0135] Example 7. The method of example 6, wherein the indication of the time includes: a first time when a coverage in the serving cell ends for the UE, and a second time when a coverage in the target cell begins for the UE; wherein the starting of the monitoring occurs at a later one of the first time and the second time.

[0136] Example 8. The method of any of examples 4-7, wherein: the indication of the TCI state is included in a medium access control (MAC) control element (CE) of a type dedicated to conveying the TCI state for non-immediate application at the UE.

[0137] Example 9. The method of any of examples 2-8, wherein the QCL configuration includes one or more of: (i) an indication of Synchronization Signal Block (SSB) positions of the target cell, (ii) a configuration of at least one non-zero power Channel State Information reference signal (CSI- RS) resource for the target cell, (iii) a Physical Downlink Shared Channel (PDSCH) configuration including a configuration for the plurality of TCI states or the configuration of the at least one non- zero power CSI-RS resource for the target cell, or (iv) a Physical Downlink Control Channel (PDCCH) configuration including at least one TCI state identifier.

[0138] Example 10. The method of example 1, further comprising: receiving, in a message including the QCL configuration, an indication of a TCI state for the monitoring of the channel.

[0139] Example 11. The method of example 10, wherein: the QCL configuration includes a PDCCH configuration that comprises (i) a plurality of TCI state identifiers and (ii) an indication of which in the plurality of TCI state identifiers corresponds to the TCI state for the monitoring of the channel.

[0140] Example 12. The method of example 11, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a configuration of at least one non-zero power CSI-RS resource for the target cell, or (iii) a PDSCH configuration including a configuration for the plurality of TCI states or the configuration of the at least one non-zero power CSI-RS resource for the target cell.

[0141] Example 13. The method of example 10, wherein: the QCL configuration includes a Physical Downlink Shared Channel (PDSCH) configuration that comprises (i) a plurality of TCI state configurations and (ii) an indication of which in the plurality of the TCI state configurations applies to the TCI state for the monitoring of the channel.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0142] Example 14. The method of example 13, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a configuration of at least one non-zero power CSI-RS resource for the target cell, or (iii) a PDCCH configuration including at least one TCI state identifier.

[0143] Example 15. The method of example 10, wherein: the QCL configuration includes a CSI measurement configuration that comprises (i) a plurality of CSI reference signal (CSI-RS) configurations and (ii) an indication of which of the plurality of CSI-RS configurations the UE is to use for the monitoring of the channel, wherein the TCI state is associated with the indicated one of the plurality of CSI-RS configurations.

[0144] Example 16. The method of example 15, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a PDSCH configuration including a configuration for the plurality of TCI states or the configuration of the at least one non- zero power CSI-RS resource for the target cell, or (iii) a Physical Downlink Control Channel (PDCCH) configuration including at least one TCI state identifier.

[0145] Example 17. The method of any of examples 10-16, wherein: the indication of the time indicates when a coverage in the serving cell ends for the UE.

[0146] Example 18. The method of any of the previous examples, wherein: the indication of the time further indicates when a coverage in the target cell begins for the UE; wherein the starting of the monitoring occurs at a later one of the first time and the second time.

[0147] Example 19. The method of example 1, wherein: the QCL configuration indicates an SSB parameter for the monitoring for the channel at the indicated time.

[0148] Example 20. The method of example 18, further comprising: synchronizing with an SSB transmitted in the target cell, using the SSB parameter; wherein the monitoring of the channel in the target cell is based on the SSB.

[0149] Example 21. The method of any of the preceding examples, further comprising: refraining from performing a handover procedure when switching from the serving cell to the target cell.

[0150] Example 22. A configuration method implemented in a radio access network (RAN) node, the method comprising: transmitting, a user equipment (UE) and in a serving cell of the UE, an indication of a time related to a change in coverage of at least one of (a) the serving cell or (b) aPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC target cell with a same cell identity as the serving cell; and transmitting, to the UE and in the serving cell, a quasi co-location (QCL) configuration for monitoring a channel in the target cell, the QCL configuration based on a determination of which reference signal is quasi-co-located with a transmission on the channel, for the UE in the target cell.

[0151] Example 23. The method of example 22, wherein the reference signal is a Synchronization Signal Block (SSB) signal.

[0152] Example 24. The method of example 22, wherein the reference signal is a Channel State Information reference signal (CSI-RS).

[0153] Example 25. The method of any of examples 22-24, further comprising: making the determination using a CSI report from the UE.

[0154] Example 26. The method of any of examples 22-25, further comprising: making the determination using a Global navigation satellite system (GNSS) information from the UE.

[0155] Example 27. The method of any of examples 22-26, further comprising: making the determination using first ephemeris information of a first satellite with which the serving cell is associated and / or second ephemeris information of a second satellite with which the target cell is associated.

[0156] Example 28. The method of any of examples 22-27, wherein the indication of the time includes: a first time when a coverage in the serving cell ends for the UE, or a second time when a coverage in the target cell begins for the UE.

[0157] Example 29. The method of any of examples 22-28, wherein: the QCL configuration configures a plurality of Transmission Configuration Indication (TCI) states; the method further comprising: transmitting, in the serving cell and subsequently to transmitting the QCL configuration, an indication of a TCI state in the plurality of TCI states, for the monitoring of the channel.

[0158] Example 30. The method of example 29, wherein: the indication of the TCI state is included in a medium access control (MAC) control element (CE) of a type dedicated to conveying the TCI state for non-immediate application at the UE.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC

[0159] Example 31. The method of example 29 or 30, wherein the QCL configuration includes one or more of: (i) an indication of Synchronization Signal Block (SSB) positions of the target cell, (ii) a configuration of at least one non-zero power Channel State Information reference signal (CSI- RS) resource for the target cell, (iii) a Physical Downlink Shared Channel (PDSCH) configuration including a configuration for the plurality of TCI states or the configuration of the at least one non- zero power CSI-RS resource for the target cell, or (iv) a Physical Downlink Control Channel (PDCCH) configuration including at least one TCI state identifier.

[0160] Example 32. The method of any of examples 22-31, further comprising: transmitting, in a message including the QCL configuration, an indication of a TCI state for the monitoring of the channel.

[0161] Example 33. The method of example 32, wherein: the QCL configuration includes a PDCCH configuration that comprises (i) a plurality of TCI state identifiers and (ii) an indication of which in the plurality of TCI state identifiers corresponds to the TCI state for the monitoring of the channel.

[0162] Example 34. The method of example 33, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a configuration of at least one non-zero power CSI-RS resource for the target cell, or (iii) a PDSCH configuration including a configuration for the plurality of TCI states or the configuration of the at least one non-zero power CSI-RS resource for the target cell.

[0163] Example 35. The method of example 34, wherein: the QCL configuration includes a Physical Downlink Shared Channel (PDSCH) configuration that comprises (i) a plurality of TCI state configurations and (ii) an indication of which in the plurality of the TCI state configurations applies to the TCI state for the monitoring of the channel.

[0164] Example 36. The method of example 35, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a configuration of at least one non-zero power CSI-RS resource for the target cell, or (iii) a PDCCH configuration including at least one TCI state identifier.

[0165] Example 37. The method of example 36, wherein: the QCL configuration includes a CSI measurement configuration that comprises (i) a plurality of CSI reference signal (CSI-RS)PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC configurations and (ii) an indication of which of the plurality of CSI-RS configurations the UE is to use for the monitoring of the channel, wherein the TCI state is associated with the indicated one of the plurality of CSI-RS configurations.

[0166] Example 38. The method of example 37, wherein the QCL configuration further includes one or more of: (i) an indication of SSB positions of the target cell, (ii) a PDSCH configuration including a configuration for the plurality of TCI states or the configuration of the at least one non- zero power CSI-RS resource for the target cell, or (iii) a Physical Downlink Control Channel (PDCCH) configuration including at least one TCI state identifier.

[0167] Example 39. The method of any of the preceding examples, wherein: the channel in the target cell is a PDCCH.

[0168] Example 40. The method of any of the preceding examples, wherein: the cell identity is a physical cell identifier (PCI).

[0169] Example 41. The method of any of the preceding examples, wherein: the first cell and the second cell are associated with a non-terrestrial network (NTN).

[0170] Example 42. A device comprising a transceiver and configured to implement a method according to any of the preceding examples.

[0171] The following description may be applied to the description above.

[0172] Generally speaking, description for one of the above figures can apply to another of the above figures. Examples, implementations and methods described above can be combined, if there is no conflict. An event or block described above can be optional or omitted. For example, an event or block with dashed lines in the figures can be optional. In some implementations, “message” is used and can be replaced by “information element (IE)”, and vice versa. In some implementations, “IE” is used and can be replaced by “field”, and vice versa. In some implementations, “configuration” can be replaced by “configurations” or “configuration parameters”, and vice versa. In some implementations, “some” means “one or more”. In some implementations, “at least one” means “one or more”.

[0173] A user device in which the techniques of this disclosure can be implemented (e.g., the UE 102) can be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a healthPATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device can operate as an internet-of-things (IoT) device or a mobile-internet device (MID). Depending on the type, the user device can include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0174] Certain embodiments are described in this disclosure as including logic or a number of components or modules. Modules may can be software modules (e.g., code, or machine-readable instructions stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module can comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

[0175] The term “or” as used herein is to be interpreted as an inclusive or meaning any one or any combination, unless expressly indicated otherwise, mutually exclusive, or indicated otherwise by context. Therefore, herein, the expression “A or B” means “A, B, or both A and B.”

[0176] When implemented in software, the techniques can be provided as part of the operating system, a library used by multiple applications, a particular software application, etc. The software can be executed by one or more general-purpose processors or one or more special-purpose processors.

[0177] Upon reading this disclosure, those of skill in the art will appreciate still additional and alternative structural and functional designs for handling mobility between base stations through the principles disclosed herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to thePATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those of ordinary skill in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.

Claims

PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC What is claimed is:

1. A channel monitoring method implemented in a user equipment (UE), the method comprising: receiving, in a serving cell, a quasi co-location (QCL) configuration for monitoring a channel in a target cell with a same cell identity as the serving cell; receiving, in the serving cell, an indication of a time related to a change in coverage of at least one of the serving cell or the target cell; and starting the monitoring of the channel in the target cell according to the QCL configuration and at the indicated time.

2. The method of claim 1, wherein: the QCL configuration configures a plurality of Transmission Configuration Indication (TCI) states; the method further comprising: receiving, in the serving cell and subsequently to receiving the QCL configuration, an indication of a TCI state in the plurality of TCI states, for the monitoring of the channel.

3. The method of claim 2, wherein: the receiving of the indication of the time includes the receiving of the indication of the TCI state; and the starting of the monitoring of the channel in the target cell occurs immediately upon the receiving of the indication of the TCI state.

4. The method of claim 2, wherein: the receiving of the indication of the time includes the receiving of the indication of the TCI state; and the starting of the monitoring of the channel in the target cell occurs after a predetermined amount of time after the receiving of the indication of the TCI state.

5. The method of claim 4, wherein:PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC the receiving of the indication of the time further includes receiving an offset value, wherein the predetermined amount of time after the receiving of the indication of the TCI state is based on the received offset value.

6. The method of claim 2, further comprising: subsequently to the receiving of the indication of the TCI state, delaying the starting of the monitoring until the indicated time.

7. The method of claim 6, wherein the indication of the time includes: a first time when a coverage in the serving cell ends for the UE, and a second time when a coverage in the target cell begins for the UE; wherein the starting of the monitoring occurs at a later one of the first time and the second time.

8. The method of any of claims 4-7, wherein: the indication of the TCI state is included in a medium access control (MAC) control element (CE) of a type dedicated to conveying the TCI state for non-immediate application at the UE.

9. A configuration method implemented in a radio access network (RAN) node, the method comprising: transmitting, a user equipment (UE) and in a serving cell of the UE, an indication of a time related to a change in coverage of at least one of (a) the serving cell or (b) a target cell with a same cell identity as the serving cell; and transmitting, to the UE and in the serving cell, a quasi co-location (QCL) configuration for monitoring a channel in the target cell, the QCL configuration based on a determination of which reference signal is quasi-co-located with a transmission on the channel, for the UE in the target cell.

10. The method of claim 9, wherein the indication of the time includes: a first time when a coverage in the serving cell ends for the UE, or a second time when a coverage in the target cell begins for the UE.PATENT APPLICATION Attorney Docket No.: 31730 / 307067-00 PC 11. The method of claim 9 or 10, wherein: the QCL configuration configures a plurality of Transmission Configuration Indication (TCI) states; the method further comprising: transmitting, in the serving cell and subsequently to transmitting the QCL configuration, an indication of a TCI state in the plurality of TCI states, for the monitoring of the channel.

12. The method of claim 11, wherein: the indication of the TCI state is included in a medium access control (MAC) control element (CE) of a type dedicated to conveying the TCI state for non-immediate application at the UE.

13. The method of any of claims 9-12, further comprising: transmitting, in a message including the QCL configuration, an indication of a TCI state for the monitoring of the channel.

14. The method of claim 12, wherein: the QCL configuration includes a PDCCH configuration that comprises (i) a plurality of TCI state identifiers and (ii) an indication of which in the plurality of TCI state identifiers corresponds to the TCI state for the monitoring of the channel.

15. A device comprising a transceiver and configured to implement a method according to any of the preceding claims.

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