Beam hopping impact to handover in ntn

Abstract

Embodiments of systems and methods are disclosed that relate to Handover (HO) or Conditional Handover (CHO) in which source and target cells operate in accordance with a same or different beam on / off schedules. In one embodiment, a method performed by a UE comprises obtaining information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, where the at least one cell comprises a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO. The method further comprises performing one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

Description

BEAM HOPPING IMPACT TO HANDOVER IN NTNTECHNICAL FIELD

[0001] The present disclosure relates to a wireless communications system and, more specifically, to handover or conditional handover in a wireless communications system, such as a Non-Terrestrial Network (NTN), that utilizes beam hopping.BACKGROUND

[0002] Conditional Handover (CHO) has been introduced in Release (Rel-) 16 of the 3rdGeneration Partnership Project (3GPP) specifications for New Radio (NR) to improve mobility robustness i.e. reduce the amount of Radio Link Failures (RLFs) and / or Handover Failures (HOFs) in the User Equipment (UE). Such failures could be caused by the fact that, when the UE is at or near the cell border and close to being triggered by the network to perform a handover, the UE may try to send a Layer 3 (L3) Measurement Report to the network. Such fails may occur when this L3 Measurement Report is not received by the source gNodeB (gNB) (e.g., due to some interference in the uplink (UL) and / or poor coverage). Such failures may also occur where, even if the source gNB receives the L3 Measurement Report, the UE does not receive the Handover Command (i.e., RRCReconfiguration message including a ReconfigurationWithSync) in response to the L3 Measurement Report to trigger the Handover (e.g., due to some interference in the downlink (DL) and / or poor DL coverage). Due to HOF and RLF, the UE would trigger a Radio Resource Control (RRC) Re-establishment procedure, which leads to more signaling exchanged between the UE and the network, and higher interruption time, since there is no service continuity. This is illustrated in Figure 1A (RLF failure due to failure of the source gNB to receive the L3 Measurement Report) and Figure IB (HOF and RLF due to the UE not receiving the Handover Command in response to the L3 Measurement Report), which leads to RRC Re-establishment, i.e., higher signaling and interruption time.

[0003] To improve mobility robustness, 3 GPP introduced in Rel- 16 the feature called CHO, which may be defined as a handover that is executed by the UE when one or more handover execution conditions are met. When configured with CHO, the UE starts evaluating the execution condition(s) upon receiving the CHO configuration, and the UE stops evaluating the execution condition(s) once a handover is executed. As described in clause 9.2.3.4.1 of 3GPP Technical Specification (TS) 38.300 V18.3.0), the following principles apply to CHO:• The CHO configuration contains the configuration of CHO candidate cell(s) generated by the candidate gNB(s) and execution condition(s) generated by the source gNB.• An execution condition may consist of one or two trigger condition(s) (CHO events A3 / A5, as defined in 3GPP TS 38.331 V18.3.0). Only single Reference Signal (RS) type is supported and at most two different trigger quantities (e.g., Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ), RSRP and Signal to Interference plus Noise Ratio (SINR), etc.) can be configured simultaneously for the evaluation of CHO execution condition of a single candidate cell.• Before any CHO execution condition is satisfied, upon reception of a Handover (HO) command (without CHO configuration), the UE executes the HO procedure as described in clause 9.2.3.2 of 3GPP TS 38.300, regardless of any previously received CHO configuration.• While executing a CHO, i.e. from the time when the UE starts synchronization with target cell, the UE does not monitor the source cell.

[0004] Figure 2 is a reproduction of Figure 9.2.3.4.2-1 of 3GPP TS 38.300, which illustrates the signaling flow for CHO for the Intra- Access and Mobility Management Function (AMF) / User Plane Function (UPF) scenario. As described in clause 9.2.3.4.2 of 3GPP TS 38.33, the steps of the CHO procedure are as follows:• Step 0. The UE context within the source gNB contains information regarding roaming and access restrictions which were provided either at connection establishment or at the last Timing Advance (TA) update.• Step 1. The source gNB configures the UE measurement procedures, and the UE reports according to the measurement configuration.• Step 2. The source gNB decides to use CHO, e.g. based on Measurement Report(s) and Radio Resource Management (RRM) information.• Step 3. The source gNB requests CHO for one or more candidate cells belonging to one or more candidate gNBs. A CHO request message is sent for each candidate cell.• Step 4. Admission Control may be performed by the target gNB. Slice-aware admission control is performed if the slice information is sent to the target gNB. If the Protocol Data Unit (PDU) sessions are associated with non-supported slices, the target gNB rejects such PDU Sessions.• Step 5. The candidate gNB(s) sends CHO response (HO REQUEST ACKNOWLEDGE) including configuration of CHO candidate cell(s) to the source gNB. The CHO response message is sent for each candidate cell.• Step 6. The source gNB sends an RRCReconfiguration message to the UE, containing the configuration of CHO candidate cell(s) and CHO execution condition(s).• NOTE 1 : CHO configuration of candidate cells can be followed by other reconfiguration from the source gNB.• NOTE la: A configuration of a CHO candidate cell cannot contain a Dual ActiveProtocol Stack (DAPS) handover configuration.• Step 7. The UE sends an RRCReconfigurationComplete message to the source gNB.• Step 7a If early data forwarding is applied, the source gNB sends the EARLY STATUS TRANSFER message.• Step 8. The UE maintains connection with the source gNB after receiving CHO configuration, and the UE starts evaluating the CHO execution conditions for the candidate cell(s). If at least one CHO candidate cell satisfies the corresponding CHO execution condition, the UE detaches from the source gNB, applies the stored corresponding configuration for that selected candidate cell, synchronizes to that candidate cell and completes the RRC handover procedure by sending RRCReconfigurationComplete message to the target gNB. The UE releases stored CHO configurations after successful completion of RRC handover procedure.• Step 8a / b The target gNB sends the HANDOVER SUCCESS message to the source gNB to inform the source gNB that the UE has successfully accessed the target cell. In return, the source gNB sends the SN STATUS TRANSFER message following the principles described in step 7 of Intra- AMF / UPF Handover in clause 9.2.3.2.1 of 3GPP TS 38.300.• NOTE 2: Late data forwarding may be initiated as soon as the source gNB receives the HANDOVER SUCCESS message.• Step 8c. The source gNB sends the HANDOVER CANCEL message toward the other signaling connections or other candidate target gNBs, if any, to cancel CHO for the UE.

[0005] In Release 17, a work item was carried out to define solutions enabling NR and Next Generation Radio Access Network (NG-RAN) to support Non-Terrestrial Networks (NTNs). Then, Release 18 introduced enhancements for NRNTN. As part of Release 19, a new work item, RP-234078, is proposed to define further enhancements for NG-RAN based NTNs. One of concerned objectives defined in RP-234078 is:Offer optimized performance especially when addressing handset terminals (including smartphones with -5.5 dBi antenna gain) w.r.t. downlink coverage considering the NTN deployment constraints such as payload power limitation, large satellite footprint and limited feeder link bandwidth. DL coverage enhancements are needed to accommodate satellite payload constraints which may be unable to have all its beams active with the « nominal » EIRP density per beam (see Section 6.1.1 in TR 38.821) at a given time due to limited power and limited feeder link bandwidth, while maximizing the number of beams that can be activatedsimultaneously, and ensuring that all user terminals can be served across the satellite foot print while maximizing the overall satellite throughput and ensuring that all satellite’s radio cells are kept alive even without traffic but allowing new users to join or preventing impact on end-user QoS.DL coverage enhancements can be considered at both• Link level to improve the link margin of selected physical channels in order to accommodate the EIRP reduction in FR1-NTN. A link margin improvement for physical channels (e.g., PDSCH and PDCCH) may be considered without impact on SSB design.• System level to support an efficient dynamic and flexible power sharing between beams or different beam pattem / size (i.e., wide or narrow) across the satellite foot print for FR1-NTN and FR2-NTN.

[0006] To reach the target, the most straightforward solution is to utilize beam time-division multiplexing (also known as beam hopping, beam based Discontinuous Transmission (DTX) / Discontinuous Reception (DRX), beam based on / off duration, cell based DTX / DRX, cell based on / off duration), where multiple beams across the satellite footprint are time multiplexed to provide coverage in the corresponding cells on the earth, which is illustrated in the example of Figure 3. As illustrated in the example of Figure 3, the UE is covered by beam #1 and is not covered by beam #2 and beam #3. From the time domain perspective with respect to the UE, as illustrated in Figure 4, the active / on duration of beam #1 is the active / on duration of the LTE, and the inactive / off durations of beam #2 and beam #3 are the inactive / off duration of the LTE. To the LTE, the pattern also is referred to as beam the on / off schedule of the LTE.SUMMARY

[0007] Embodiments of systems and methods are disclosed that relate to Handover (HO) or Conditional Handover (CHO) of a User Equipment (UE) from a source cell to target cell in which the source and target cells operate in accordance with a same beam on / off schedule or different beam on / off schedules. In one embodiment, a method performed by a UE configured with a HO or CHO that involves a source cell and at least one candidate target cell comprises obtaining information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, where the at least one cell comprises a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO. The method further comprises performing one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell. In this manner, negative impacts of HO or CHO in a network (e.g., a Non-Terrestrial Network (NTN)) that utilizes beam hopping can be mitigated.

[0008] In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises, for at least one beam utilized for a cell involved in the HO or CHO, any one or more of the following: information that defines an on / off cycle of the beam for the cell, where the information that defines the on / off cycle comprises an on-duration duration which the cell is expected to perform transmission to the UE on the beam and an off-duration during which the cell is not expected to perform transmission to the UE on the beam; one or more timers that control on-durations during which the cell is expected to perform transmissions on the beam; one or more timers that control off-durations during which the cell is not expected to perform transmissions on the beam; one or more time instances that indicate a start and / or end of one or more on-durations during which the cell is expected to perform transmission on the beam; one or more time instances that indicate a start and / or end of one or more off- durations during which the cell is expected to perform transmission on the beam. In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO further comprises, for the cell involved in the HO or CHO, a corresponding cell identity, ID, and / or satellite ID. In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO further comprises information that indicates at least one of a footprint of the cell, a footprint of a corresponding satellite, or a footprint of the at least one beam.

[0009] In one embodiment, obtaining the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises receiving the information from the source cell via system information or dedicated signaling.

[0010] In one embodiment, obtaining the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises receiving information about the on / off schedule of the at least one candidate cell from the at least one candidate cell via system information.

[0011] In one embodiment, performing the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises determining one or more HO or CHO operations to be performed in one or more beam on-durations indicated by the information about the on / off schedule of the at least one beam of the at least one cell. In one embodiment, the one or more HO or CHO operations comprise any one or more of the following operations: receiving a configuration for CHO; performing cell search and / or measurement on the source cell and the at least one candidate target cell and, after determining that an execution condition for CHO is fulfilled for one of the at least one candidate target cells, processing Synchronization Signal Block (SSB) of the one of the at least one candidatetarget cells; performing uplink synchronization to the one of the at least one candidate target cells; performing fine time tracking and Channel State Information (CSI) measurement, on the one of the at least one candidate target cells.

[0012] In one embodiment, performing the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises performing the HO or CHO, taking into consideration the information about the on / off schedule of the at least one beam of the at least one cell. In one embodiment, performing the HO or CHO comprises suspending, restarting, and / or resuming one or more of operations of the HO or CHO, based on the information about the on / off schedule of the at least one beam of the at least one cell.

[0013] In one embodiment, performing the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises selecting one of the at least one candidate target cells as a target cell for the HO or CHO based on one or more criteria comprising at least one criterion related to the information about the on / off schedule of the at least one beam of the at least one cell.

[0014] In one embodiment, performing the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises transmitting, to either the source cell or a candidate target cell from among the at least one candidate target cells, information that indicates a preferred on / off schedule for at least one beam used on the candidate target cell.

[0015] Corresponding embodiments of a UE are also disclosed. In one embodiment, a UE configured with a HO or CHO that involves a source cell and at least one candidate target cell is adapted to obtain information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, where the at least one cell comprises a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO. The UE is further adapted to perform one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

[0016] In one embodiment, a UE configured with a HO or CHO that involves a source cell and at least one candidate target cell comprises a communication interface comprising a transmitter and a receiver, and processing circuitry associated with the communication interface. The processing circuitry is configured to cause the UE to obtain information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, where the at least one cell comprises a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO,or both the source cell and the at least one candidate target cell for the HO or CHO. The processing circuitry is further configured to cause the UE to perform one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

[0017] Embodiments of a method performed by a network node are also disclosed. In one embodiment, a method performed by a network node of a wireless communications system comprises transmitting, to a UE, information about an on / off schedule of at least one beam of at least one cell, where the at least one cell comprises a cell managed or operated by the network node and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.

[0018] In one embodiment, the network node is a serving network node that operates a serving cell of the UE, and the information about the on / off schedule of the at least one beam of the at least one cell comprises information about an on / off schedule of at least one beam of the serving cell of the UE and / or information about an on / off schedule of at least one beam of at least one candidate target cells for a HO or CHO of the UE.

[0019] In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell comprises, for at least one beam utilized for a cell, any one or more of the following: information that defines an on / off cycle of the beam for the cell, where the information that defines the on / off cycle comprises an on-duration duration which the cell is expected to perform transmission to the UE on the beam and an off-duration during which the cell is not expected to perform transmission to the UE on the beam; one or more timers that control on- durations during which the cell is expected to perform transmissions on the beam; one or more timers that control off-durations during which the cell is not expected to perform transmissions on the beam; one or more time instances that indicate a start and / or end of one or more on-durations during which the cell is expected to perform transmission on the beam; one or more time instances that indicate a start and / or end of one or more off-durations during which the cell is expected to perform transmission on the beam. In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell further comprises, for the cell, a corresponding cell identity, ID, and / or satellite ID. In one embodiment, the information about the on / off schedule of the at least one beam of the at least one cell further comprises, information that indicates at least one of: a footprint of the cell, a footprint of a corresponding satellite, or a footprint of the at least one beam.

[0020] In one embodiment, transmitting the information about the on / off schedule of the at least one beam of the at least one cell comprises transmitting the information via system information or dedicated signaling.

[0021] Corresponding embodiments of a network node are also disclosed. In one embodiment, a network node for a wireless communications system is adapted to transmit, to a UE, information about an on / off schedule of at least one beam of at least one cell, where the at least one cell comprises a cell managed or operated by the network node and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.

[0022] In one embodiment, a network node for a wireless communications system comprises processing circuitry configured to cause the network node to transmit, to a UE, information about an on / off schedule of at least one beam of at least one cell, where the at least one cell comprises a cell managed or operated by the network node and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0024] Figures 1 A and IB illustrate scenarios in which lack of mobility robustness may lead to Radio Link Failures (RLFs) and / or Handover Failures (HOFs), which lead to Radio Resource Control (RRC) Re-establishment;

[0025] Figure 2 illustrates the signaling flow for Conditional Handover (CHO);

[0026] Figure 3 illustrates an example of beam hopping;

[0027] Figure 4 illustrates a time domain perspective of beam hopping with respect to a particular User Equipment (UE);

[0028] Figure 5 illustrates a simplified example of handover with on / off schedule;

[0029] Figure 6 illustrates one example of a system in which embodiments of the present disclosure may be implemented;

[0030] Figure 7 illustrates the operation of the system of Figure 6, in accordance with a first set of embodiments of the present disclosure;

[0031] Figure 8 illustrates the operations of the Conditional Handover (CHO) procedure;

[0032] Figures 9 and 10 illustrate the Handover (HO) / CHO delay;

[0033] Figure 11 illustrates the operation of the system of Figure 6, in accordance with a second set of embodiments of the present disclosure;

[0034] Figure 12 illustrates the operation of the system of Figure 6, in accordance with a third set of embodiments of the present disclosure;

[0035] Figures 13 and 14 illustrate examples of extending the valid CHO time, in accordance with an embodiment of the present disclosure;

[0036] Figure 15 shows text from 3rdGeneration Partnership Project (3GPP) Technical Specification (TS) 38.331 vl7.6.0 regarding CondEvent Tl;

[0037] Figure 16 illustrates the operation of a User Equipment (UE), in accordance with another embodiment;

[0038] Figure 17 illustrates the operation of the system of Figure 6, in accordance with another set of embodiments of the present disclosure;

[0039] Figure 18 shows an example of a communication system in accordance with some embodiments of the present disclosure;

[0040] Figure 19 shows a User Equipment device (UE) in accordance with some embodiments of the present disclosure;

[0041] Figure 20 shows a network node in accordance with some embodiments of the present disclosure; and

[0042] Figure 21 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized in accordance with some embodiments of the present disclosure.DETAILED DESCRIPTION

[0043] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0044] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0045] There currently exist certain challenge(s). Beam hopping is most likely to be introduced in 3rdGeneration Partnership Project (3GPP) Release (Rel-) 19 Non-Terrestrial Network (NTN) enhancement. For a full load cell / beam, the duty cycle (active / on state and inactive / off state) of each beam may be fixed so the User Equipment (UE) in each cell / beam hasequal opportunity to be served. Limited by the hardware and / or antenna cost and complexity, in off state, no Synchronization Signal Block (SSB) transmissions and no other common signals are transmitted. In other words, SSB transmissions have to be time shifted between beams / cells, and even with such time shifted SSB transmissions, achieving an efficient beam hopping schedule may require long SSB periodicities, which increases the latency of cell searches and measurements in various cases.

[0046] It has been discussed that the beam on / off schedule should be signaled to the UE, and the UE performing cell measurement should be aware of the schedule to avoid useless reception / transmission costing power consumption.

[0047] However, an issue arises with respect to Handover (HO) and Conditional Handover (CHO), particularly in CHO in an NTN. A conditional handover (normal / legacy handover also has same issue) is well-suited to an NTN environment considering the deterministic nature of satellite movement and long Round-Trip Time (RTT). However, the beam on / off schedule could impact evaluation and execution of CHO, lowering the overall robustness of the procedure. For example, even if a UE is aware of beam on / off schedule for a CHO candidate cell and source cell, the UE still faces a risk when executing the CHO, since the UE may need to complete the entire CHO procedure during the available ‘on-duration’ after starting CHO. Otherwise, if the UE cannot complete the HO procedure during one ‘on-duration’ of the beam, the CHO procedure as well as the involved timers (T304, Random Access (RA) response window, some Hybrid Automatic Repeat Request (HARQ) / retransmission timer, etc.) has to extend across the off-duration with cost of non-negligible extended time delay and extra signaling overhead. A similar issues arises in relation to HO and CHO in general.

[0048] A simplified example of handover with on / off schedule is shown in Figure 5. In this example, the UE is served by a source cell with beam #1 and is to change to a target cell with beam #4. Due to unaligned beam on / off schedules, the UE cannot complete the HO procedure in one on- duration.

[0049] Given that, it is desirable to provide a mechanism(s) to mitigate negative effects of the beam on / off schedule to the HO or CHO in NTN.

[0050] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. Embodiments of the present disclosure relate to a set(s) of mechanisms for a UE served by a first cell (Celli) served or managed by a first network node (NW1) changing, e.g., handover (HO) or CHO, to a second cell (Cell2) served or managed by a second network node (NW2), in which Celli and / or Cell2 operate in accordance with the same beam on / off schedule or different beam on / off schedules.

[0051] Note that while the description herein sometimes focuses on embodiments of the solution in a NTN, embodiments of the solution disclosed herein may also be used in a Terrestrial Network (TN). Note that beam duty cycle based operation may be applied in TN cells, where different terminology may be used such as, e.g., cell discontinuous reception and / or transmission or cell discontinuous downlink and / or uplink.

[0052] In embodiments of the present disclosure, a UE is provided with information about at least one cell (e.g., the candidate target cell, Cell2) regarding its beam on / off schedule.

[0053] According to a first embodiment, a method in a UE comprises determining one or more DL and / or UL (denoted herein as “DL / UL”) operations in a CHO procedure to be contained in one or more beam on-durations of a source cell and / or a candidate target cell of the CHO procedure. In one embodiment, the determination is based on one or more determination rules. In one embodiment, the one or more determination rules are provided (e.g., by the UE) to at least one network node (e.g., the network node managing the source cell, Cell 1). In another embodiment, the one or more determination rules are received, by the UE, from a network node (e.g., the network node managing the source cell, Cell 1).

[0054] In one embodiment, the UE determines to suspend and / or restart and / or resume one or more DL / UL operations in the HO or CHO procedure depending on one or more beam on-duration of the source cell and / or the candidate target cell.

[0055] According to a second embodiment, a method in a UE comprises starting HO or CHO or starting one or more operations in HO or CHO with respect to various criteria regarding a beam on / off schedule of a source cell of the HO or CHO and / or a beam on / off schedule of the candidate target cell of the HO or CHO.

[0056] According to a third embodiment, a method in a UE comprises determining the target cell in CHO given that there is more than one candidate target cell provided to the UE with respect to various criteria regarding the beam on / off schedule.

[0057] Certain embodiments may provide one or more of the following technical advantage(s). Embodiments of the present disclosure mitigate negative impacts of HO or CHO in an NTN that utilizes beam hopping.

[0058] Now, a more detailed description of embodiments of the present disclosure will be provided.

[0059] As used herein, the term “satellite” used herein may also be referred to as a “satellite node”, “satellite access node” (SAN), “NTN node”, “node in space” (i.e., outer space), etc. A base station (BS) or Radio Network Node (RNN) associated with a satellite might include both a regenerative satellite, where the BS or RNN is the satellite payload, i.e. the BS or RNN isintegrated with the satellite, or a transparent satellite, where the satellite payload is a relay and BS or RNN is on the ground (i.e. the satellite relays the communication between the BS or RNN on the ground and the UE).

[0060] The term “node” is used herein and may refer to either a network node or a UE. Examples of network nodes are NodeB, Base Station (BS), Multi -Standard Radio (MSR) radio node such as MSR BS, eNodeB (eNB), gNodeB (gNB), Master eNB (MeNB), Secondary eNB (SeNB), Satellite Access Node (SAN), Location Measurement Unit (LMU), Integrated Access Backhaul (IAB) node, network controller, Radio Network Controller (RNC), Base Station Controller (BSC), relay, donor node controlling relay, Base Transceiver Station (BTS), Central Unit (e.g. in a gNB), Distributed Unit (e.g. in a gNB), Baseband Unit, Centralized Baseband, Centralized or Cloud-Computing based RAN (C-RAN), Access Point (AP), transmission points, transmission nodes, Transmission Reception Point (TRP), Remote Radio Unit (RRU), Remote Radio Head (RRH), nodes in Distributed Antenna System (DAS), core network node (e.g. Mobile Switching Center (MSC), Mobility Management Entity (MME), etc. in the case of 4thGeneration (4G) or Access and Mobility Management Function (AMF), User Plane Function (UPF), etc. in the case of 5thGeneration (5G)), Operations and Maintenance (O&M), Operation Support System (OSS), Self-Organizing Network (SON), positioning node (e.g. Evolved Serving Mobile Location Center (E-SMLC)), etc.

[0061] The non-limiting term “UE” refers to any type of wireless device communicating with a network node and / or with another UE in a cellular or mobile communication system. Examples of a UE are target device, Device to Device (D2D) UE, Vehicular to Vehicular (V2V) UE, machine type UE, Machine Type Communication (MTC) UE or UE capable of Machine to Machine (M2M) communication, Personal Digital Assistant (PDA), tablet, mobile terminals, smart phone, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), Universal Serial Bus (USB) dongles, etc.

[0062] The term “radio access technology”, or RAT, may refer to any RAT e.g. Universal Terrestrial Radio Access (UTRA), Evolved UTRA (E-UTRA), Narrow Band Internet of Things (NB-IoT), WiFi, Bluetooth, next generation RAT, New Radio (NR), 4G, 5G, 6thGeneration (6G), NR NTN, loT NTN, Long Term Evolution (LTE) NTN, etc. Any of the equipment denoted by the term node, network node, or radio network node may be capable of supporting a single or multiple RATs.

[0063] The term “signal” or “radio signal” as used herein can be any physical signal or physical channel. Examples of DL physical signals are Reference Signals (RSs) such as Cell Specific RS (CRS), NR-IoT RS (NRS), Narrowband Primary Synchronization Signal (NPSS),Narrowband Secondary Synchronization Signal (NSSS), Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Channel State Information (CSI) RS (CSI-RS), Demodulation Reference Signal (DMRS) signals in Secondary Signal (SS) / Physical Broadcast Channel (PBCH) Block (SSB) (also referred to herein as “Synchronization Signal Block”), Discovery Reference Signal (DRS), Positioning Reference Signal (PRS), etc. A RS may be periodic, e.g. RS occasion carrying one or more RSs may occur with certain periodicity, e.g. 20 milliseconds (ms), 40 ms, etc. A RS may also be aperiodic. Each SSB carries NR-PSS, NR-SSS, and NR-PBCH in 4 successive symbols. One or multiple SSBs are transmitted in one SSB burst which is repeated with certain periodicity, e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms. The UE is configured with information about SSB on cells of certain carrier frequency by one or more SS / PBCH Block Measurement Timing Configuration (SMTC) configurations. The SMTC configuration includes parameters such as SMTC periodicity, SMTC occasion length in time or duration, SMTC time offset with respect to a reference time (e.g. serving cell’s System Frame Number (SFN)), etc. Therefore, SMTC occasions may also occur with a certain periodicity, e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms. Examples of UL physical signals are reference signal such as SRS, DMRS etc. The term physical channel refers to any channel carrying higher layer information e.g. data, control etc. Examples of physical channels are PBCH, Narrowband PBCH (NPBCH), Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), Physical Uplink Control Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), short PDCCH (sPDCCH), short PDSCH (sPDSCH), short PUCCH (sPUCCH), short PUSCH (sPUSCH), MTC PDCCH (MPDCCH), Narrowband PDCCH (NPDCCH), Narrowband PDSCH (NPDSCH), Enhanced PDCCH (E-PDCCH), Narrowband PUSCH (NPUSCH), etc.

[0064] The term “carrier frequency” as used herein is also referred to as Component Carrier (CC), frequency layer, layer, carrier, frequency, serving carrier, frequency channel, radio channel, radio frequency channel, Positioning Frequency Layer (PFL), Measurement Object (MO), etc. The carrier frequency belongs to certain frequency band, which may contain one or multiple carrier frequencies based on its passband (e.g. size of the band in frequency domain) and / or bandwidth of the carriers and / or the channel raster etc. The carrier frequency related information is transmitted to the UE by a network node using a frequency channel number or identifier via message, e.g. Radio Resource Control (RRC). Examples of the channel number or identifier, which may be predefined, are Absolute Radio Frequency Channel Number (ARFCN), NR-ARFCN, etc.

[0065] The term “time resource” as used herein may correspond to any type of physical resource or radio resource expressed in terms of length of time. Examples of time resources aresymbol, time slot, subframe, radio frame, Transmission Time Interval (TTI), interleaving time, slot, sub-slot, mini-slot, System Frame Number (SFN) cycle, hyper-SFN (H-SFN) cycle, etc.

[0066] In the present disclosure, the term Non-Terrestrial Network (NTN) may, depending on the context, refer to either or both of NR NTN and loT NTN, and sometimes the term is used to refer to only NR NTN. Thus, even though the embodiments outlined below are described mainly in terms of NR based NTNs, they are equally applicable in an NTN based on LTE technology (and in particular loT NTN).

[0067] Figure 6 illustrates one example of a system 600 in which embodiments of the present disclosure may be implemented. As illustrated, the system 600 includes a UE 602 served by a first cell 604-1 operated or managed by a first network node 606-1. The system 600 also includes a second cell 604-2 operated or managed by a second network node 606-2. The first network node 606-1 and the second network node 606-1 are, in some embodiments, satellites or NTN nodes; however, the present disclosure is not limited thereto. In operation, the UE 602 changes, e.g., via a HO or CHO, from the first cell 604-1 (i.e., a serving / source cell) to the second cell 604-2 (i.e., a neighbor cell / candidate target cell for CHO / HO). In the embodiments described herein, the first cell 604-1 and the second cell 604-2 operate in accordance with the same beam on / off schedule or different beam on / off schedules. As described below, the beam on / off schedule of the first cell 604-1 and / or the beam on / off schedule of the second cell 604-2 are utilized by the UE 602 in association with performing one or more operations related to the HO or CHO procedure.

[0068] Note that, the first cell 604-1 is referred to as the “serving cell” of the UE 602 when referring to operations that are outside of the HO or CHO procedure and referred to as the “source cell” of the UE 602 when referring to HO or CHO operations. Likewise, the second cell 604-2 is referred to as a “neighbor cell” of the UE 602 when referring to operations that are outside of the HO or CHO procedure and referred to as the “candidate target cell” of the UE 602 when referring to HO or CHO operations.

[0069] Figure 7 illustrates the operation of the UE 602, the first network node 606-1, and the second network node 606-2 of Figure 6, in accordance with a first set of embodiments of the present disclosure. Optional steps are represented by dashed lines / boxes. As illustrated, the UE 602 obtains the beam on / off schedule of the first cell 604-1 and / or the beam on / off schedule of the second cell 604-2 (step 700). Note that, in the context of a CHO, there may be one or more second cells 604-2; however, a single second cell 604-2 is used in the examples described herein for clarity and ease of discussion. For each cell for which the UE 602 obtains the respective beam on / off schedule, the beam on / off schedule of that cell (i.e., the first cell 604-1 or the second cell 604-2)includes information that indicates (explicitly or implicitly), for at least one beam utilized for the cell, any one or more of the following:• an on / off cycle of the beam for the cell, where the information that defines the on / off cycle includes an on-duration during which the cell is expected to perform transmission to the UE on that beam and an off-duration during which the cell is not expected to perform transmission to the UE on that beam;• one or more timers controlling on-durations during which the cell is expected to perform transmission on that beam;• one or more timers controlling off-durations during which the cell is not expected to perform transmission on that beam;• a time instance(s) of a start and / or end of an on-duration(s) during which the cell is expected to perform transmission on that beam;• a time instance(s) of a start and / or end of an off-duration(s) during which the cell is not expected to perform transmission on that beam.In the above, a time instance can be represented in various ways. For example, a time instance may be represented by any of the following:• a Universal Coordinated Time (UTC) timestamp;• any suitable combination of one or more of H-SFN, SFN, subframe number, slot number, and symbol number (e.g., of the serving or source cell, which in the example of Figures 6 and 7 is the first cell 604-1) - all optionally combined with a time reference. For instance, a time instance may be represented by any one of the following: o H-SFN + SFN, o H-SFN + SFN + subframe number, o H-SFN + SFN + slot number, o SFN + subframe number, or o SFN + slot number;• a combination of a (possibly coarse) UTC timestamp and any of the above combinations of one or more of H-SFN, SFN, subframe number, slot number, and symbol number (e.g., of the serving or source cell, which in the example of Figures 6 and 7 is the first cell 604- 1), for instance: o UTC timestamp + H-SFN + SFN o UTC timestamp + SFN o UTC timestamp + SFN + subframe number o UTC timestamp + SFN + slot number

[0070] Note that the on / off schedule for a cell may include separate information for each of one or more beams utilized for that cell, common information for all beams utilized for that cell, or a combination thereof. For example, the on / off cycle (e.g., on-duration and off-duration) may be the same for all of the beams in the cell, in which case the on / off cycle may be common information applicable for all of the beams of that cell, whereas the start and / or end times of the on-durations and / or off-durations are different for different beams, in which case separate start and / or end times for on-durations and / or off-durations may be included in the on / off schedule for each beam.

[0071] Further, for precise estimation, the on / off schedule may also contain or be associated with a corresponding Cell Identity (ID) and / or satellite ID. Further yet, the on / off schedule may also contain or be associated with information that indicates a footprint of the corresponding beam, cell, and / or satellite. By this, the UE 602 may acquire ephemeris data and determine a delay difference from cells or satellites (e.g., the source satellite and the target satellite in HO or CHO) and determine when the on / off schedule of the beam(s) will be expected to be received.

[0072] The UE 602 may obtain the beam on / off schedule of the second cell 604-2 (i.e., the candidate target cell in the HO or CHO procedure) via one of the following options. Note that, for CHO, there may be more than one candidate target cell, in which case the UE 602 may obtain the beam on / off schedule of each of the candidate target cells using one of the following options.• Option 1 : The first network node 606-1 may send a signaling (e.g., handover request message) to the second network node 606-1 (e.g., via the X2 or XN interface) between the first network node 606-1 and the second network node 606-2 to request the on / off schedule of the second cell 604-2 (step 700-1 A) and receive a response from the second network node 606-2 including the on / off schedule of the second cell 604-2 (step 700- IB). Steps 600-1A and 600-1B may be performed for each of one or more second cells 604-2 (i.e., each of one or more neighbor cells). The first network node 606-1 (i.e., the serving network node) transmits the on / off schedule of each second cell 604-2 (i.e., each neighbor / candidate target cell) to the UE 602, e.g., via system information in the first cell 604-1 (i.e., the serving cell) or via Radio Resource Control (RRC) signaling (step 700- 1C). The UE 602 reads the system information of the first cell 604-1 and obtains the on / off schedule of the second cell(s) 604-2 (and optionally the on / off schedule of the first cell 604-1) from the system information read on the first cell 604-1 (step 700- ID).• Option 2: Each second network node 606-2 (i.e., each neighbor network node) transmits system information including the on / off schedule of the second cell 604-2 (step 700-2A). The UE 602 reads the system information of each second cell 604-2 (i.e., each neighborcell), and obtains the on / off schedule second cell 604-2 (i.e., each neighbor cell) from the respective system information (step 700-2B). Note that the UE 602 obtain the beam on / off schedule of the first cell 604-1 from the system information transmitted by the first network node 606-1 on the first cell 604-1.

[0073] In one embodiment, the UE determines one or more operations in the HO or CHO procedure to be contained in (i.e., performed in) one or more of the beam on-durations of the source cell and / or the candidate target cell (step 702). Note that the HO or CHO is a HO or CHO from a particular beam in the first cell 604-1 to a particular beam in the second cell 604-2. The particular beams may correspond to, for example, certain SSB indices, where these beams or SSB indices are associated to the respective information (e.g., on / off cycle, on-duration start time(s) and / or end time(s), and / or off-duration start and / or end time(s)) contained in the on / off schedules for the respective cells. In one example, the operations in the CHO procedure, as demonstrated in Figure 8, are categorized at least as follows:• Operation 1 : The UE receives RRC reconfiguration for CHO.• Operation 2: The UE performs cell search / measurement on the source cell and candidate target cell, and after determining fulfilling the condition for handover, processes the SSB of the target cell.• Operation 3: The UE performs UL synchronization to the target cell. If UE performs UL synchronization via Random Access Channel (RACH), the UE sends the preamble on the first available Physical Random Access Channel (PRACH) occasion in the target cell. After RACH toward the target cell is completed successfully, the handover procedure is completed.• Operation 4: After accessing the target cell, the UE performs fine time tracking to acquire accurate timing information and perform CSI measurement to improve the data transmission performance. Then the UE could perform normal data transmission / reception.

[0074] Depending on the acquired beam on / off schedule, one or more operations are completed in one or more on-durations, in other words, the UE completes operations as per granularity of on-duration, in accordance with the determination of step 702 (step 704).

[0075] In one example, if the on-duration (i.e., the on-duration of the source beam in the source cell and / or the on-duration of the target beam in the candidate target cell) is equal to or larger than a threshold, TH1, then in step 702 the UE 602 determines that all operations in the CHO procedure are to be completed in one on-duration. If, in step 704, the UE 602 cannot complete all operations of CHO procedure in one on-duration, then the UE 602 restarts one or more of the operations of the CHO procedure repeatedly in the consecutive on-duration. In particular, the UE602 restarts from measuring the power level, e.g., Reference Signal Received Power (RSRP), of the candidate target cell to evaluate if conditions of CHO still are valid or not.

[0076] In another example, if the on-duration (i.e., the on-duration of the source beam in the source cell and / or the on-duration of the target beam in the candidate target cell) is equal to or less than a threshold, TH2, then in step 702 the UE 602 determines that each operation is to be completed in one on-duration until the CHO procedure completes. In step 704, if the UE 602 cannot complete an operation in one on-duration, then the UE 602 restarts that operation repeatedly in the consecutive on-duration, and then continues. In particular, the UE 602 restarts from measuring the power level, e.g., RSRP, of the candidate target cell to evaluate if conditions of CHO still are valid or not.

[0077] In another example, if the on-duration (i.e., the on-duration of the source beam in the source cell and / or the on-duration of the target beam in the candidate target cell) is equal to or less than a threshold, TH3, then in step 702 the UE 602 determines that, for some of the operations, each operation is to be completed in one on-duration and, for some other operations, more than one operation is to be completed in one on-duration until CHO procedure completes. One example is presented as follows:• Operation 1 and Operation 2 are completed in one on-duration;• Operation 3 is completed in one on-duration; and• Operation 4 is completed in one on-duration.

[0078] In particular for the UL synchronization / transmission, as an additional embodiment, the UE 602 initiates the first transmission of the UL synchronization procedure in a time occasion / slot when the respective beam is expected to be in on-duration according to the on / off duration schedule.• In one option, the first transmission is initiated in a RACH procedure. In case of 2-step Random Access (RA), the first transmission is a MsgA transmission. In case of 4-step RA, the first transmission is a Msgl transmission.• In one option, the first transmission is a UL transmission initiated on PUSCH.

[0079] Given the above solution, the HO / CHO procedure delay is demonstrated in Figure 9 and Figure 10. It can be observed that the overall handover delay is completed in one on-duration (Figure 9) or split into two on-durations (Figure 10) of the target cell.

[0080] It is worth noting that the categories of HO / CHO operations given above are one example of categorizing operations in the CHO procedure. The operations may be categorized differently, e.g., with more or less categories. In one example, each message in the RACHprocedure is treated as one operation. In another example, message 1 and message 2 in the RACH procedure containing the Random Access Response (RAR) window is treated as one operation.

[0081] In one embodiment, the determination is based on one or more determination rules. In one embodiment, the one or more determination rules are provided (e.g., by the UE) to at least one network node (e.g., the network node managing the source cell, Cell 1). In another embodiment, the one or more determination rules are received, by the UE, from a network node (e.g., the network node managing the source cell, Cell 1). More specifically, in one embodiment, the one or more determination rules are determined in accordance with one of the following two options:• In one option, the UE 602 determines the determination rule(s) (i.e., the rule(s) about which operations can be performed in on-duration(s)), e.g., as a UE capability or Uplink Control Information (UCI) information, which is reported to at the least one network node (e.g., the network node 606-1 operating or managing the first cell 604-1 (i.e., the source cell)).• In another option, at the least one network node (e.g., the network node 606-1 managing the first cell 604-1 (i.e., the source cell)) provides the one or more determination rules to the UE 602, and the UE 602 may acknowledge and follow the rule(s), e.g., if the UE 602 is capable of following the rule(s).

[0082] Figure 11 illustrates the operation of the UE 602, the first network node 606-1, and the second network node 606-2, in accordance with a second set of embodiments. Optional steps are represented by dashed lines / boxes. As illustrated, the UE 602 obtains the beam on / off schedule of the first cell 604-1 and / or the beam on / off schedule of the second cell 604-2 (step 1100). Note that step 1100 corresponds to step 700 of Figure 7 and all of the details regarding step 700 above are equally applicable here to step 1100. The UE 602 performs operations of the HO or CHO procedure to perform handover of the UE 602 from the first cell 604-1 operated or managed by the first network node 606-1 to the second cell 604-2 operated or managed by the second network node 606-2, taking into consideration the on / off schedule of the first cell 604-1 (i.e., the source cell) and / or the on / off schedule of the second cell 604-2 (i.e., the candidate target cell) (step 1102). More specifically, in one embodiment, the UE suspends and / or restarts and / or resumes one or more DL or UL operations in the HO / CHO procedure depending on one or more beam on-durations of the first cell 604-1 (i.e., the source cell) and / or one or more beam on-durations of the second cell 604-2 (i.e., the candidate target cell) (step 1102A).• In one example, the UE 602 conducts one operation of the HO / CHO procedure in one on- duration but cannot complete it before end of the on-duration. Then, the UE 602 suspends this operation in the subsequent off-duration and resumes the operation in the consecutive on-duration.• In one example, the UE 602 conducts one operation of the HO / CHO procedure in one on- duration but cannot complete it before end of the on-duration. Then, the UE 602 suspends this operation in the subsequent off-duration and restarts the operation in the consecutive on-duration.• In one particular example, at the least one of the timers (e.g., T304, RA response window (ra-ResponseWindow some HARQ / retransmission timer, or the like) related to the HO / CHO procedure is extended to cover at least one on-duration.• In one particular example, at least one of the timers (e.g., T304, RA response window (ra- ResponseWindow), some HARQ / retransmission timer, or the like) related to the HO / CHO procedure is extended to cover at the least a time period including Ml instances of consecutive on-durations, where Ml is determined by the on / off schedule of the first cell 604-1 (i.e., the source cell) and / or the on / off schedule of the second cell (i.e., the candidate target cell). If the timer does not expire before end of one on-duration, then the UE suspends the timer in the subsequent off-duration and resumes the timer in the consecutive on-duration until either the operation completes or the end of Ml instances of consecutive on-durations is reached.

[0083] Furthermore, the operations and / or timers for beam on / off schedule of the first cell 604-1 (i.e., the source cell) and / or the second cell 604-2 (i.e., the candidate target cell) are configured to the UE 602 by the first network node 606-1 and / or the second network node 606-2, provided the first cell 604-1 and / or the second cell 604-2 applies a beam on / off schedule. This configuration is an additional configuration different from the configuration(s) provided by the network for a scenario in which the source cell and / or the candidate target cell do not apply a beam on / off schedule.

[0084] Alternatively, the operations and / or timers for beam on / off schedule of the first cell 604-1 (i.e., the source cell) and / or the second cell 604-2 (i.e., the candidate target cell) are configured to the UE 602 by the first network node 606-1 and / or the second network node 606-2, provided that the first cell 604-1 and / or the second cell 604-1 applies a beam on / off schedule that fulfills one or more predefined or configured criteria. The one or more criteria may include at least one of the following.• On-duration of the source cell and / or the candidate target cell is longer / shorter than a threshold;• Off-duration of the source cell and / or the candidate target cell is longer / shorter than a threshold;• Ratio between on-duration of the source cell and / or the candidate target cell is longer / shorter than a threshold;• Periodicity of on / off-duration of the source cell and / or the candidate target cell is longer / shorter than a threshold;• Periodicity of on / off-duration of the source cell and / or the candidate target cell is longer / shorter than a threshold.

[0085] Figure 12 illustrates the operation of the UE 602, the first network node 606-1, and the second network node 606-2, in accordance with a third set of embodiments. Optional steps are represented by dashed lines / boxes. As illustrated, the UE 602 obtains the beam on / off schedule of the first cell 604-1 and / or the beam on / off schedule of the second cell 604-2 (step 1200). Note that step 1200 corresponds to step 700 of Figure 7 and all of the details regarding step 700 above are equally applicable here to step 1200. The UE 602 starts the HO / CHO procedure or starts one or more operation in the HO / CHO procedure with respect to one or more criteria including at least one criterion related to the beam on / off schedule of the first cell 604-1 (i.e., the source cell) and / or beam on / off schedule of the second cell 604-2 (i.e., the candidate target cell) (step 1202). In this way, the UE acquires some time instances of on-duration of the serving cell and / or some time instances of on-duration of candidate target cell, e.g., tl-1, tl-2 and / or t2- 1 , t2-2 as shown in Figure 9 and Figure 10. In the examples of Figures 7 and 8, tl-1, tl-2 and the on / off schedule of source cell and t2- 1 , t2-2 and the on / off schedule of candidate target cell are obtained by the UE 602 (e.g., in step 1200) prior to the HO / CHO, and t2- 1 , t2-2 is the next closest on-duration of the candidate target cell after tl-1, tl-2 as on-duration of the candidate target cell. Given this information, the UE 602 may in step 1202 perform at the least one of below:• In one example, the UE 602 starts the HO / CHO procedure, e.g., performing cell search (including measuring SSB) of the source cell from tl-1.• In another example, the UE 602 starts the HO / CHO procedure, e.g., performing cell search (including measuring SSB) of the candidate target cell from t2-l.• In another example, the UE 602 suspends / skips cell search (e.g. measure SSB) of the source cell and the candidate target cell from tl-2 to t2-l, i.e., during Tdelta, which depends on the on / off schedule of the source cell and the candidate target cell and the propagation delay from between the timing reference between the source cell and the candidate target cell to the UE.

[0086] In one additional embodiment, the UE 602 is able to execute CHO between Tl-1 and Tl-2 (regarding CondEvent Tl, as quoted in the text shown in Figure 15 which is from 3GPP TS 38.331 vl7.6.0 ) and extend the valid CHO time until the next on-duration or the next M2 timesof on-duration after Tl-1 and Tl / 2, e.g., extending the valid CHO time until the on-duration of t2- 1 and t2-2 in Figure 13 or t3 - 1 and t3-2 in Figure 14.

[0087] Ideally, Tl-1 and Tl-2 are configured at least in the on-duration of the candidate target cell, to enable the UE 602 to conduct CHO by measuring available SSB of the candidate target cell immediately without missing any SSB in off-duration. In some cases, if Tl-1 and Tl-2 are configured not in the on-duration of the candidate target cell or Tl-1 is close to the end of the on- duration of the candidate target cell with a distance less than a threshold, which results in that the UE is able to conduct and complete CHO with measuring available SSB of the candidate target cell from the next on-duration or the next M2 times of on-duration after Tl-1 and Tl / 2 by extension. The UE 602 may further inform the first network node 606-1 (i.e., the source network node) of the extra delay due to on-duration before conducting CHO, in order to avoid causing the first network node 606-1 to determine a handover failure because Tl-2 is reached.

[0088] Figure 16 illustrates the operation of the UE 602, in accordance with another embodiment. Note that while illustrated separately from the embodiments of Figures 7, 11, and 12 described above, the process of Figure 16 may be utilized in combination with that of Figures 7, 11, and 12, e.g., in order to select a target cell for the HO / CHO from among the candidate target cells. As illustrated, the UE 602 obtains the beam on / off schedule of one or more candidate target cells (i.e., one or more second cells 604-2) and, optionally, the source / serving cell (i.e., the first cell 604-1) (step 1600). Note that step 1600 corresponds to step 700 of Figure 7 and all of the details regarding step 700 above are equally applicable here to step 1600. The UE 602 selects one of the candidate target cells as a target cell for a CHO based one or more criteria including at least one criterion related to the beam on / off schedules of the candidate target cells and optionally the beam on / off schedule of the serving / source cell. The at least one criteria may include any one or more of the following:• In one example, the UE 602 selects the candidate target cell for which the on-duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is closest to the time instance to execute CHO, if the received signal level, e.g., RSRP of the target cell is higher than a threshold.• In another example, the UE 602 is to select the candidate target cell for which the on- duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is longest, if the received signal level, e.g., RSRP of the candidate target cell is higher than a threshold.• In another example, the UE 602 is to select the candidate target cell for which the off- duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is shortest, if the received signal level, e.g., RSRP of the candidate target cell is higher than a threshold.• In another example, the UE 602 is to select the candidate target cell for which the periodicity of on / off-duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is shortest, if the received signal level, e.g., RSRP of the candidate target cell is higher than a threshold.• In another example, the UE 602 is to select the candidate target cell for which the periodicity of on / off-duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is longest, if the received signal level, e.g., RSRP of the target cell is higher than a threshold.• In another example, the UE 602 is to select the candidate target cell for which the ratio of on / off-duration of the beam to which the UE 602 would be handed over (e.g., the beam of the candidate target cell that covers the geographic location at which the UE 602 is located) is largest, if the received signal level, e.g., RSRP of the candidate target cell is higher than a threshold.

[0089] It may also happen that the UE 602 cannot obtain the on / off schedule of the candidate target cell. This could be because, for example, either the serving cell not providing the on / off schedule of the candidate target cell to the UE 602 or the UE 602 not being able to read the system information of the candidate target cell. In this case, the UE 602 may generate its preferred on / off schedule for the candidate target cell.

[0090] In this regard, Figure 17 illustrates the operation of the UE 602, the first network node 606-1, and the second network node 606-2, in accordance with another set of embodiments. Optional steps are represented by dashed lines / boxes. Note that while illustrated separately from the embodiments of Figures 7, 11, 12, and 16, the process of Figure 17 may be utilized in combination with that of Figures 7, 11, 12, and 16, e.g., in a scenario in which the UE 602 does not or is not able to obtain the beam on / off schedule for the second cell 604-2. As illustrated, the UE 602 may obtain the beam on / off schedule of the first cell 604-1, e.g., via system information or RRC signaling (step 1700). The UE 602 performs a CHO or HO procedure whereby the UE 602 is handed over from the first cell 604-1 (i.e., the source cell) operated or managed by the firstnetwork node 606-1 to the second cell 604-2 (i.e., the target cell) operated or managed by the second network node 606-2 (step 1702). Upon being triggered to handover to the second cell 604- 2 (i.e., the target cell) operated or managed by the second network node 606-2, the UE 602 transmits a first transmission towards the second cell 604-2 (step 1702-1). The first transmission not only indicates an access request to the second cell 604-2, but also indicates information regarding a preferred beam on / off schedule for the second cell 604-2. This information regarding the preferred beam on / off schedule for the second cell 604-2 includes any one or more of the following:• the UE’s preferred beam on / off schedule for the second cell 604-2;• how soon that the UE 602 expects the relevant beam on the second cell 604-2 to be active in transmission;• how soon that the UE 602 expects the relevant beam on the second cell 604-2 to be active in reception.

[0091] In the procedure of Figure 16, the handover may be a normal handover scenario, i.e., the source network sends a handover command to the UE indicating that the UE shall perform the handover towards the target cell, or the handover may be triggered by a CHO configuration.

[0092] In one embodiment, the UE 602 indicates the information regarding the preferred beam on / off schedule for the second cell 604-2 via a specific PRACH resource (e.g., PRACH preamble, or a RACH occasion in frequency domain and / or time domain) used for the first transmission in step 1702-1. There may be multiple specific PRACH resources configured to the UE 602. In an example, the UE 602 is configured with a specific PRACH preamble associated with a specific on / off schedule.

[0093] In one embodiment, the UE 602 indicates the information regarding the preferred beam on / off schedule for the second cell 604-2 in a RRC signaling or a Medium Access Control (MAC) Control Element (CE) in the first transmission of step 1702-1.

[0094] In one embodiment, the UE 602 indicates the information regarding the preferred beam on / off schedule for the second cell 604-2 in a RRC signaling or a MAC CE in the first transmission and / or a second transmission. This may be the case when the first transmission can only carry limited information. The additional information may then be carried in the second transmission towards the second cell 604-2.

[0095] In alternative embodiment, before being triggered to handover to the second cell 604- 2, the UE 602 indicates the information regarding the preferred beam on / off schedule for the second cell 604-2 to the first network node 606-1 (i.e., the serving network node), and the first network node 606-1 may further send a handover request containing the UE indicated informationto the second network node 606-2 operating or managing the second cell 604-2, e.g., via the associated X2 or XN interface, and the second network node 606-2 may accept, reject, or update its on / off schedule accordingly. The first network node 606-1 may forward the second network node’s response to the UE 602. If the second network node 606-2 has rejected the UE’s preferred on / off schedule, the UE 602 and / or the first network node 606-1 may decide to select another candidate target cell instead. Alternatively, the handover is determined as failed if there is no other candidate target cell which can be further selected for the UE 602.

[0096] Figure 18 shows an example of a communication system 1800 in which embodiments of the present disclosure may be implemented. Note that the network nodes 606-1 and 606-2 of Figure 6 may correspond to two of the network nodes 1810 of Figure 18, and the UE 602 may correspond to one of the UEs 1812 of Figure 18.

[0097] In the example, the communication system 1800 includes a telecommunication network 1802 that includes an access network 1804, such as a Radio Access Network (RAN), and a core network 1806, which includes one or more core network nodes 1808. The access network 1804 includes one or more access network nodes, such as network nodes 1810A and 1810B (one or more of which may be generally referred to as network nodes 1810), or any other similar Third Generation Partnership Project (3GPP) access nodes or non-3GPP Access Points (APs). Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1802 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1802 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1802, including one or more network nodes 1810 and / or core network nodes 1808.

[0098] Examples of an ORAN network node include an Open Radio Unit (O-RU), an Open Distributed Unit (O-DU), an Open Central Unit (O-CU), including an O-CU Control Plane (O- CU-CP) or an O-CU User Plane (O-CU-UP), a RAN intelligent controller (near-real time or non- real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such asan Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies. The network nodes 1810 facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 1812A, 1812B, 1812C, and 1812D (one or more of which may be generally referred to as UEs 1812) to the core network 1806 over one or more wireless connections.

[0099] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 1800 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 1800 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0100] The UEs 1812 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 1810 and other communication devices. Similarly, the network nodes 1810 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1812 and / or with other network nodes or equipment in the telecommunication network 1802 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1802.

[0101] In the depicted example, the core network 1806 connects the network nodes 1810 to one or more hosts, such as host 1816. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 1806 includes one more core network nodes (e.g., core network node 1808) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 1808. Example core network nodes include functions of one or more ofa Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-Concealing Function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0102] The host 1816 may be under the ownership or control of a service provider other than an operator or provider of the access network 1804 and / or the telecommunication network 1802, and may be operated by the service provider or on behalf of the service provider. The host 1816 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0103] As a whole, the communication system 1800 of Figure 18 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 1800 may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable Second, Third, Fourth, or Fifth Generation (2G, 3G, 4G, or 5G) standards, or any applicable future generation standard (e.g., Sixth Generation (6G)); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any Low Power Wide Area Network (LPWAN) standards such as LoRa and Sigfox.

[0104] In some examples, the telecommunication network 1802 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunication network 1802 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1802. For example, the telecommunication network 1802 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing enhanced Mobile Broadband (eMBB) services to other UEs, and / or massive Machine Type Communication (mMTC) / massive Internet of Things (loT) services to yet further UEs.

[0105] In some examples, the UEs 1812 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1804 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1804. Additionally, a UE may be configured for operating in single- or multi-Radio Access Technology (RAT) or multi -standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e. being configured for Multi-Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC).

[0106] In the example, a hub 1814 communicates with the access network 1804 to facilitate indirect communication between one or more UEs (e.g., UE 1812C and / or 1812D) and network nodes (e.g., network node 1810B). In some examples, the hub 1814 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1814 may be a broadband router enabling access to the core network 1806 for the UEs. As another example, the hub 1814 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1810, or by executable code, script, process, or other instructions in the hub 1814. As another example, the hub 1814 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 1814 may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub 1814 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1814 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1814 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0107] The hub 1814 may have a constant / persistent or intermittent connection to the network node 1810B. The hub 1814 may also allow for a different communication scheme and / or schedule between the hub 1814 and UEs (e.g., UE 1812C and / or 1812D), and between the hub 1814 and the core network 1806. In other examples, the hub 1814 is connected to the core network 1806 and / or one or more UEs via a wired connection. Moreover, the hub 1814 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 1804 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1810 while still connected via the hub 1814 via a wired or wireless connection. In some embodiments, the hub 1814 may be a dedicated hub - that is, a hub whoseprimary function is to route communications to / from the UEs from / to the network node 1810B. In other embodiments, the hub 1814 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and the network node 1810B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0108] Figure 19 shows a UE 1900 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged, and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, Voice over Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart device, wireless Customer Premise Equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0109] A UE may support Device-to-Device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehi cl e-to- Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle- to-Everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0110] The UE 1900 includes processing circuitry 1902 that is operatively coupled via a bus 1904 to an input / output interface 1906, a power source 1908, memory 1910, a communication interface 1912, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 19. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0111] The processing circuitry 1902 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1910. The processing circuitry 1902 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1902 may include multiple Central Processing Units (CPUs).

[0112] In the example, the input / output interface 1906 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1900. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0113] In some embodiments, the power source 1908 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1908 may further include power circuitry for delivering power from the power source 1908 itself, and / or an external power source, to the various parts of the UE 1900 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1908. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1908 to make the power suitable for the respective components of the UE 1900 to which power is supplied.

[0114] The memory 1910 may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removablecartridges, flash drives, and so forth. In one example, the memory 1910 includes one or more application programs 1914, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1916. The memory 1910 may store, for use by the UE 1900, any of a variety of various operating systems or combinations of operating systems.

[0115] The memory 1910 may be configured to include a number of physical drive units, such as Redundant Array of Independent Disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, High Density Digital Versatile Disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, Holographic Digital Data Storage (HDDS) optical disc drive, external mini Dual In-line Memory Module (DIMM), Synchronous Dynamic RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and / or Internet Protocol Multimedia Services Identity Module (ISIM), other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as a ‘SIM card.’ The memory 1910 may allow the UE 1900 to access instructions, application programs, and the like stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system, may be tangibly embodied as or in the memory 1910, which may be or comprise a device-readable storage medium.

[0116] The processing circuitry 1902 may be configured to communicate with an access network or other network using the communication interface 1912. The communication interface 1912 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1922. The communication interface 1912 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 1918 and / or a receiver 1920 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1918 and receiver 1920 may be coupled to one or more antennas (e.g., the antenna 1922) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0117] In the illustrated embodiment, communication functions of the communication interface 1912 may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, NFC, location-based communication such as the use of the Global Positioning System (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol / Internet Protocol (TCP / IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

[0118] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1912, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected, an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0119] As another example, a UE comprises an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0120] A UE, when in the form of an loT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application, and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a television, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. AUE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 1900 shown in Figure 19.

[0121] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0122] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g., by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator and handle communication of data for both the speed sensor and the actuators.

[0123] Figure 20 shows a network node 2000 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment in a telecommunication network. Examples of network nodes include, but are not limited to, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), NR Node Bs (gNBs)), and 0-RAN nodes or components of an 0-RAN node (e.g., 0-RU, 0-DU, O-CU).

[0124] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an 0-RAN access node), and / or Remote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a Distributed Antenna System (DAS).

[0125] Other examples of network nodes include multiple Transmission Point (multi-TRP) 5G access nodes, Multi -Standard Radio (MSR) equipment such as MSR BSs, network controllers such as Radio Network Controllers (RNCs) or BS Controllers (BSCs), Base Transceiver Stations (BTSs), transmission points, transmission nodes, Multi-Cell / Multicast Coordination Entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0126] The network node 2000 includes processing circuitry 2002, memory 2004, a communication interface 2006, and a power source 2008. The network node 2000 may be composed of multiple physically separate components (e.g., a NodeB component and an RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 2000 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair may in some instances be considered a single separate network node. In some embodiments, the network node 2000 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory 2004 for different RATs) and some components may be reused (e.g., a same antenna 2010 may be shared by different RATs). The network node 2000 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 2000, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node 2000.

[0127] The processing circuitry 2002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, or any other suitable computing device, resource, or combination of hardware, software, and / or encoded logic operable to provide, either alone or in conjunction with other network node 2000 components, such as the memory 2004, to provide network node 2000 functionality.

[0128] In some embodiments, the processing circuitry 2002 includes a System on a Chip (SOC). In some embodiments, the processing circuitry 2002 includes one or more of Radio Frequency (RF) transceiver circuitry 2012 and baseband processing circuitry 2014. In some embodiments, the RF transceiver circuitry 2012 and the baseband processing circuitry 2014 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. Inalternative embodiments, part or all of the RF transceiver circuitry 2012 and the baseband processing circuitry 2014 may be on the same chip or set of chips, boards, or units.

[0129] The memory 2004 may comprise any form of volatile or non-volatile computer- readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, RAM, ROM, mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD), or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device- readable, and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 2002. The memory 2004 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 2002 and utilized by the network node 2000. The memory 2004 may be used to store any calculations made by the processing circuitry 2002 and / or any data received via the communication interface 2006. In some embodiments, the processing circuitry 2002 and the memory 2004 are integrated.

[0130] The communication interface 2006 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 2006 comprises port(s) / terminal(s) 2016 to send and receive data, for example to and from a network over a wired connection. The communication interface 2006 also includes radio front-end circuitry 2018 that may be coupled to, or in certain embodiments a part of, the antenna 2010. The radio front-end circuitry 2018 comprises filters 2020 and amplifiers 2022. The radio front-end circuitry 2018 may be connected to the antenna 2010 and the processing circuitry 2002. The radio front-end circuitry 2018 may be configured to condition signals communicated between the antenna 2010 and the processing circuitry 2002. The radio front-end circuitry 2018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 2018 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters 2020 and / or the amplifiers 2022. The radio signal may then be transmitted via the antenna 2010. Similarly, when receiving data, the antenna 2010 may collect radio signals which are then converted into digital data by the radio front-end circuitry 2018. The digital data may be passed to the processing circuitry 2002. In other embodiments, the communication interface 2006 may comprise different components and / or different combinations of components.

[0131] In certain alternative embodiments, the network node 2000 does not include separate radio front-end circuitry 2018; instead, the processing circuitry 2002 includes radio front-endcircuitry and is connected to the antenna 2010. Similarly, in some embodiments, all or some of the RF transceiver circuitry 2012 is part of the communication interface 2006. In still other embodiments, the communication interface 2006 includes the one or more ports or terminals 2016, the radio front-end circuitry 2018, and the RF transceiver circuitry 2012 as part of a radio unit (not shown), and the communication interface 2006 communicates with the baseband processing circuitry 2014, which is part of a digital unit (not shown).

[0132] The antenna 2010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 2010 may be coupled to the radio front-end circuitry 2018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 2010 is separate from the network node 2000 and connectable to the network node 2000 through an interface or port.

[0133] The antenna 2010, the communication interface 2006, and / or the processing circuitry 2002 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node 2000. Any information, data, and / or signals may be received from a UE, another network node, and / or any other network equipment. Similarly, the antenna 2010, the communication interface 2006, and / or the processing circuitry 2002 may be configured to perform any transmitting operations described herein as being performed by the network node 2000. Any information, data, and / or signals may be transmitted to a UE, another network node, and / or any other network equipment.

[0134] The power source 2008 provides power to the various components of the network node 2000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 2008 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 2000 with power for performing the functionality described herein. For example, the network node 2000 may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 2008. As a further example, the power source 2008 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0135] Embodiments of the network node 2000 may include additional components beyond those shown in Figure 20 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 2000 may include userinterface equipment to allow input of information into the network node 2000 and to allow output of information from the network node 2000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 2000. In some embodiments providing a core network node, such as core network node 108 of FIG. 18, some components, such as the radio front-end circuitry 2018 and the RF transceiver circuitry 2012 may be omitted.

[0136] Figure 21 is a block diagram illustrating a virtualization environment 2100 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices, and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more Virtual Machines (VMs) implemented in one or more virtualization environments 2100 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, a UE, a core network node, or a host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 2100 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface. Virtualization may facilitate distributed implementations of a network node, a UE, a core network node, or a host.

[0137] Applications 2102 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 2100 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0138] Hardware 2104 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, an input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 2106 (also referred to as hypervisors or Virtual Machine Monitors (VMMs)), provide VMs 2108 A and 2108B (one or more of which may be generally referred to as VMs 2108), and / or perform any of the functions, features, and / or benefits described in relation with some embodiments describedherein. The virtualization layer 2106 may present a virtual operating platform that appears like networking hardware to the VMs 2108.

[0139] The VMs 2108 comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer 2106. Different embodiments of the instance of a virtual appliance 2102 may be implemented on one or more of VMs 2108, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as Network Function Virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers and customer premise equipment.

[0140] In the context of NFV, a VM 2108 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 2108, and that part of the hardware 2104 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 2108 on top of the hardware 2104 and corresponds to the application 2102.

[0141] The hardware 2104 may be implemented in a standalone network node with generic or specific components. The hardware 2104 may implement some functions via virtualization. Alternatively, the hardware 2104 may be part of a larger cluster of hardware (e.g., such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 2110, which, among others, oversees lifecycle management of the applications 2102. In some embodiments, the hardware 2104 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 2112 which may alternatively be used for communication between hardware nodes and radio units.

[0142] Although the computing devices described herein (e.g., UEs, network nodes) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions, and methods disclosed herein. Determining, calculating,obtaining, or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0143] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0144] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

CLAIMS1. A method performed by a User Equipment, UE, (602) configured with a Handover, HO, or Conditional Handover, CHO, that involves a source cell (604-1) and at least one candidate target cell (604-2), the method comprising: obtaining (700; 1100; 1200; 1600; 1700) information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, the at least one cell comprising a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO; and performing (702; 1102; 1202; 1602; 1702) one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

2. The method of claim 1, wherein the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises for a cell involved in the HO or CHO for at least one beam utilized for the cell, any one or more of the following: information that defines an on / off cycle of the beam for the cell, where the information that defines the on / off cycle comprises an on-duration duration which the cell is expected to perform transmission to the UE on the beam and an off-duration during which the cell is not expected to perform transmission to the UE on the beam; one or more timers that control on-durations during which the cell is expected to perform transmissions on the beam; one or more timers that control off-durations during which the cell is not expected to perform transmissions on the beam; one or more time instances that indicate a start and / or end of one or more on-durations during which the cell is expected to perform transmission on the beam; one or more time instances that indicate a start and / or end of one or more off-durations during which the cell is expected to perform transmission on the beam.

3. The method of claim 2, wherein the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO further comprises, for the cell involved in the HO or CHO, a corresponding cell identity, ID, and / or satellite ID.

4. The method of claim 2 or 3, wherein the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO further comprises, information that indicates at least one of a footprint of the cell, a footprint of a corresponding satellite, or afootprint of the at least one beam.

5. The method of any of claims 1 to 4, wherein obtaining (700) the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises receiving (700- 1C) the information from the source cell via system information or dedicated signaling.

6. The method of any of claims 1 to 4, wherein obtaining (700) the information about the on / off schedule of the at least one beam of the at least one cell involved in the HO or CHO comprises receiving (700-2A) information about the on / off schedule of the at least one candidate cell from the at least one candidate cell via system information.

7. The method of any of claims 1 to 6, wherein performing (702) the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises: determining (702) one or more HO or CHO operations to be performed in one or more beam on-durations indicated by the information about the on / off schedule of the at least one beam of the at least one cell.

8. The method of claim 7, wherein the one or more HO or CHO operations comprise any one or more of the following operations: receiving a configuration for CHO; performing cell search and / or measurement on the source cell and the at least one candidate target cell and, after determining that an execution condition for CHO is fulfilled for one of the at least one candidate target cells, processing Synchronization Signal Block, SSB, of the one of the at least one candidate target cells; performing uplink synchronization to the one of the at least one candidate target cells; performing fine time tracking and Channel State Information, CSI, measurement, on the one of the at least one candidate target cells.

9. The method of any of claims 1 to 6, wherein performing (1102) the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises: performing (1102) the HO or CHO, taking into consideration the information about theon / off schedule of the at least one beam of the at least one cell.

10. The method of claim 9, wherein performing (1102) the HO or CHO comprises suspending, restarting, and / or resuming (1102A) one or more of operations of the HO or CHO, based on the information about the on / off schedule of the at least one beam of the at least one cell.

11. The method of any of claims 1 to 6, wherein performing (1602) the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises selecting (1602) one of the at least one candidate target cells as a target cell for the HO or CHO based on one or more criteria comprising at least one criterion related to the information about the on / off schedule of the at least one beam of the at least one cell.

12. The method of any of claims 1 to 6, wherein performing (1702) the one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell comprises transmitting (1702-1), to either the source cell or a candidate target cell from among the at least one candidate target cells, information that indicates a preferred on / off schedule for at least one beam used on the candidate target cell.

13. A User Equipment, UE, (602) configured with a Handover, HO, or Conditional Handover, CHO, that involves a source cell (604-1) and at least one candidate target cell (604-2), the UE (602) adapted to: obtain (700; 1100; 1200; 1600; 1700) information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, the at least one cell comprising a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO; and perform (702; 1102; 1202; 1602; 1702) one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

14. The UE of claim 13, further adapted to perform the method of any of claims 2 to 12.

15. A User Equipment, UE, (602; 1900) configured with a Handover, HO, or Conditional Handover, CHO, that involves a source cell (604-1) and at least one candidate target cell (604-2), the UE (602; 1900) comprising:a communication interface (1912) comprising a transmitter (1918) and a receiver (1920); and processing circuitry (1902) associated with the communication interface (1912), the processing circuitry (1902) configured to cause the UE (602; 1900) to: obtain (700; 1100; 1200; 1600; 1700) information about an on / off schedule of at least one beam of at least one cell involved in a HO or CHO, the at least one cell comprising a source cell for the HO or CHO, at least one candidate target cell for the HO or CHO, or both the source cell and the at least one candidate target cell for the HO or CHO; and perform (702; 1102; 1202; 1602; 1702) one or more actions related to the HO or CHO based on the information about the on / off schedule of the at least one beam of the at least one cell.

16. The UE of claim 15, wherein the processing circuitry (1902) is further configured to cause the UE (602; 1900) to perform the method of any of claims 2 to 12.

17. A method performed by a network node (606-1 or 606-2) of a wireless communications system, the method comprising: transmitting (700; 1100; 1200; 1600; 1700), to a User Equipment, UE, (602), information about an on / off schedule of at least one beam of at least one cell, the at least one cell comprising a cell managed or operated by the network node (606-1 or 606-2) and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.

18. The method of claim 17, wherein the network node (606-1) is a serving network node (606- 1) that operates a serving cell (604-1) of the UE (602), and the information about the on / off schedule of the at least one beam of the at least one cell comprises: information about an on / off schedule of at least one beam of the serving cell (604-1) of the UE (602); and / or information about an on / off schedule of at least one beam of at least one candidate target cells (604-2) for a Handover, HO, or a Conditional Handover, CHO, of the UE (602).

19. The method of any of claims 17 to 18, wherein the information about the on / off schedule of the at least one beam of the at least one cell comprises for a cell for at least one beam utilized for the cell, any one or more of the following: information that defines an on / off cycle of the beam for the cell, where the information thatdefines the on / off cycle comprises an on-duration duration which the cell is expected to perform transmission to the UE on the beam and an off-duration during which the cell is not expected to perform transmission to the UE on the beam; one or more timers that control on-durations during which the cell is expected to perform transmissions on the beam; one or more timers that control off-durations during which the cell is not expected to perform transmissions on the beam; one or more time instances that indicate a start and / or end of one or more on-durations during which the cell is expected to perform transmission on the beam; one or more time instances that indicate a start and / or end of one or more off-durations during which the cell is expected to perform transmission on the beam.

20. The method of claim 19, wherein the information about the on / off schedule of the at least one beam of the at least one cell further comprises, for the cell, a corresponding cell identity, ID, and / or satellite ID.

21. The method of claim 19 or 20, wherein the information about the on / off schedule of the at least one beam of the at least one cell further comprises, information that indicates at least one of a footprint of the cell, a footprint of a corresponding satellite, or a footprint of the at least one beam.

22. The method of any of claims 17 to 21, wherein transmitting (700) the information about the on / off schedule of the at least one beam of the at least one cell comprises transmitting (700- 1C) the information via system information or dedicated signaling.

23. A network node (606-1 or 606-2) for a wireless communications system, the network node (606-1 or 606-2) adapted to: transmit (700; 1100; 1200; 1600; 1700), to a User Equipment, UE, (602), information about an on / off schedule of at least one beam of at least one cell, the at least one cell comprising a cell managed or operated by the network node (606-1 or 606-2) and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.

24. The network node (606-1 or 606-2) of claim 23, further adapted to perform the method of any of claims 18 to 22.

25. A network node (606-1 or 606-2) for a wireless communications system, the network node (606-1 or 606-2) comprising processing circuity (2002) configured to cause the network node (606-1 or 606-2) to: transmit (700; 1100; 1200; 1600; 1700), to a User Equipment, UE, (602), information about an on / off schedule of at least one beam of at least one cell, the at least one cell comprising a cell managed or operated by the network node (606-1 or 606-2) and / or one or more neighboring cells managed or operated by one or more neighboring network nodes.

26. The network node (606-1 or 606-2) of claim 25, wherein the processing circuity is further configured to cause the network node to perform the method of any of claims 18 to 22.

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