CN119836816A - Method for considering SCell conditions during conditional mobility - Google Patents

Abstract

A method for configuring a wireless transmit/receive unit (WTRU) is provided, the method comprising receiving one or more of a conditional handover (CHO) or a conditional primary/secondary serving cell (PSCell) addition/change (CPAC) configuration including one or more trigger conditions from a network. The trigger condition can include a candidate primary cell (PCell) or PSCell and an associated signal level threshold. A set of candidate secondary cells (SCells) and associated signal level thresholds can be provided, as well as a radio resource control (RRC) reconfiguration to be applied when the one or more trigger conditions are met. When the trigger condition is met, the WTRU can perform the RRC reconfiguration and add a SCell that meets its corresponding threshold. An indication of the added SCell can be transmitted to the network.

Description

Method for considering SCell conditions during conditional mobility

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional application No. 63/395,099, filed 8/4 at 2022, the entire contents of which are incorporated herein by reference.

Background

Release 16 NR introduced the concept of Conditional Handover (CHO) and conditional PSCell addition/change (CPA/CPC, or collectively CPAC) with the aim of reducing the likelihood of Radio Link Failure (RLF) and handover failure (HOF).

Conventional LTE/NR handover may be triggered by a measurement report, and nothing prevents the network from transmitting HO commands to a Wireless Transmit Receive Unit (WTRU), even in the absence of a received measurement report. For example, the WTRU may be configured with an A3 event that triggers transmission of a measurement report when the radio signal level/quality (e.g., RSRP, RSRQ, etc.) of a neighboring cell becomes better than the primary serving cell (PCell) and/or better than the primary secondary serving cell (PSCell), e.g., in the case of Dual Connectivity (DC). The WTRU may monitor the serving cell and the neighbor cell and may transmit a measurement report when a condition is met. Upon receiving such a report, the network (e.g., the current serving node/cell) may prepare and transmit a HO command (e.g., RRC reconfiguration message with reconfigurationWithSync) to the WTRU. The WTRU may perform a HO, which will result in the WTRU being connected to the target cell.

Disclosure of Invention

The WTRU may be configured to consider signal levels of candidate secondary cells (scells) when performing Conditional Handover (CHO). In an embodiment, only candidate cells having a signal level above (typically greater than) a certain threshold are added as scells. In an embodiment, the WTRU may be configured to decide whether to perform CHO taking into account the average signal level of the candidate cells (primary cell (PCell) +scell, or SCell only). In an embodiment, CHO may be performed if the average signal level of all candidate cells is greater than the average of the current serving cell by a certain threshold. In embodiments, the WTRU may be configured to add only a specific number of scells that meet a specific threshold when CHO is performed. In embodiments, the WTRU may be configured to determine SCell status (e.g., activated, deactivated, dormant) based on the configured threshold and the signal level of the SCell at CHO execution. In an embodiment, the WTRU may be configured to transmit an indication of the added SCell, SCell status, and SCell measurements to the network upon completion of CHO execution.

In an embodiment, a method of configuring a WTRU may include receiving a Conditional Handover (CHO) or conditional primary secondary serving cell (PSCell) add/change (CPAC) configuration from a network with one or more trigger conditions. The trigger event may include one or more of a candidate primary cell (PCell) or PSCell and an associated signal level threshold. The configuration may include a set of candidate secondary cells (scells) and associated signal level thresholds, and a Radio Resource Control (RRC) reconfiguration to apply when one or more trigger conditions are met. The WTRU monitors a trigger condition for a condition reconfiguration and performs when the trigger condition is met. The WTRU may also add scells that meet its threshold and then transmit an indication of the added scells to the network.

The WTRU may perform a method or be configured to receive measurement configuration information from a network device indicating a list of cells to measure. The cell list may include a serving primary cell (PCell), one or more serving secondary cells (scells), a candidate PCell, and one or more candidate scells. The configuration information may also include a first trigger condition related to at least one of the serving PCell or the candidate PCell. The configuration information may also include a second trigger condition related to at least one of the one or more serving scells or the one or more candidate scells. A measurement of a signal associated with the cell list and determining whether the first trigger condition and the second trigger condition are met. If the trigger condition is met, the WTRU may further determine whether measurement configuration information is associated with a Conditional Handover (CHO). If the measurement is not associated with CHO, the WTRU transmits a layer 1 (L1) or layer 3 (L3) measurement report. If the measurement event is associated with CHO, the WTRU performs CHO to the candidate PCell.

In an embodiment, the measurement configuration information may include a specific indication of whether it is associated with a measurement report configuration or CHO configuration. The WTRU may also determine that a first trigger condition is met when the signal quality measurements of the candidate pcells exceed a first signal quality threshold, and may also determine that a second trigger condition is met when the signal quality measurements of at least one of the candidate scells exceed a second signal quality threshold. The WTRU may determine that the second trigger condition is met when the average signal quality of the one or more candidate scells exceeds a signal quality threshold.

In an embodiment, the measurement configuration information may include an indication of a signal quality threshold for one or more of the candidate scells, and the WTRU may apply SCell configuration for the candidate scells having a signal quality measurement exceeding the signal quality threshold. Further, the WTRU may be configured to determine a state of each of the candidate scells having a signal quality measurement exceeding a signal quality threshold. When doing so, the state of the candidate SCell may be in an active state, an inactive state, or a dormant state. The signal quality measurement may also exceed a signal quality threshold based on a maximum number of scells configurable by the WTRU. In an embodiment, multiple candidate scells may be associated with the same frequency. The WTRU then applies SCell configuration for the SCell with the highest signal quality measurement for multiple scells associated with the same frequency. The WTRU may transmit a CHO complete message when performing CHO to the candidate PCell.

Drawings

FIG. 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

Fig. 1B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communication system illustrated in fig. 1A according to an embodiment;

Fig. 1C is a system diagram illustrating an example Radio Access Network (RAN) and an example Core Network (CN) that may be used within the communication system illustrated in fig. 1A, according to an embodiment;

Fig. 1D is a system diagram illustrating another example RAN and another example CN that may be used within the communication system illustrated in fig. 1A according to an embodiment;

fig. 2 illustrates an example of a handover scenario in a New Radio (NR).

Fig. 3 illustrates an example of conditional handover configuration and execution.

Fig. 4 illustrates an example of a layer 1 (L1)/layer 2 (L2) inter-cell mobility operation using Carrier Aggregation (CA).

Fig. 5 illustrates an example of L1/L2 inter-cell mobility deployed only in certain areas.

Fig. 6 illustrates an example process performed by a WRTU in response to receiving measurement event configuration information.

Detailed Description

Fig. 1A is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. Communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcast, etc., to a plurality of wireless users. Communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, communication system 100 may employ one or more channel access methods such as Code Division Multiple Access (CDMA), time Division Multiple Access (TDMA), frequency Division Multiple Access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT-spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and Filter Bank Multicarrier (FBMC), among others.

As shown in fig. 1A, the communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104/113, CNs 106/115, public Switched Telephone Networks (PSTN) 108, the internet 110, and other networks 112, although it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the UEs 102a, 102b, 102c, 102d (any of which may be referred to as a "station" and/or "STA") may be configured to transmit and/or receive wireless signals and may include user equipment (WTRU), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular telephones, personal Digital Assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, internet of things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in an industrial and/or automated processing chain environment), consumer electronics devices, devices operating on a commercial and/or industrial wireless network, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

Communication system 100 may also include base station 114a and/or base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114B may be transceiver base stations (BTSs), node bs, evolved node bs, home evolved node bs, gnbs, NR node bs, site controllers, access Points (APs), wireless routers, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

Base station 114a may be part of RAN 104/113 that may also include other base stations and/or network elements (not shown), such as Base Station Controllers (BSCs), radio Network Controllers (RNCs), relay nodes, and the like. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a particular geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of a cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio Frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable Radio Access Technology (RAT).

More specifically, as noted above, communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA and SC-FDMA, among others. For example, a base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) terrestrial radio access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interfaces 115/116/117.WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or evolved HSPA (hspa+). HSPA may include high speed Downlink (DL) packet access (HSDPA) and/or High Speed UL Packet Access (HSUPA).

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology, such as evolved UMTS terrestrial radio access (E-UTRA), which may use Long Term Evolution (LTE) and/or LTE-advanced (LTE-a) and/or LTE-advanced Pro (LTE-a Pro) to establish the air interface 116.

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access that may establish the air interface 116 using a New Radio (NR).

In embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, e.g., using a Dual Connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions to/from multiple types of base stations (e.g., enbs and gnbs).

In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., wireless fidelity (WiFi)), IEEE 802.16 (i.e., worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000 1X, CDMA EV-DO, tentative standard 2000 (IS-2000), tentative standard 95 (IS-95), tentative standard 856 (IS-856), global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), and GSM EDGE (GERAN).

The base station 114B in fig. 1A may be, for example, a wireless router, home node B, home evolved node B, or access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as businesses, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for use by drones), and roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.11, to establish a Wireless Local Area Network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.15, to establish a Wireless Personal Area Network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-a Pro, NR, etc.) to establish a pico cell or femto cell. As shown in fig. 1A, the base station 114b may have a direct connection with the internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106/115.

The RANs 104/113 may communicate with the CNs 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102 d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location based services, prepaid calling, internet connectivity, video distribution, etc., and/or perform high level security functions such as user authentication. Although not shown in fig. 1A, it should be appreciated that the RANs 104/113 and/or CNs 106/115 may communicate directly or indirectly with other RANs that employ the same RAT as the RANs 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113 that may utilize NR radio technology, the CN 106/115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA 2000, wiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112.PSTN 108 may include circuit-switched telephone networks that provide Plain Old Telephone Services (POTS). The internet 110 may include a global system for interconnecting computer networks and devices using common communication protocols, such as Transmission Control Protocol (TCP), user Datagram Protocol (UDP), and/or Internet Protocol (IP) in the TCP/IP internet protocol suite. Network 112 may include wired and/or wireless communication networks owned and/or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RANs 104/113 or a different RAT.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in fig. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based radio technology, and with a base station 114b, which may employ an IEEE 802 radio technology.

Fig. 1B is a system diagram illustrating an example WTRU 102. As shown in fig. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and/or other peripheral devices 138, etc. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuit (IC), a state machine, or the like. The processor 118 may perform signal decoding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to a transmit/receive element 122. Although fig. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

The transmit/receive element 122 may be configured to transmit signals to and receive signals from a base station (e.g., base station 114 a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF signals and optical signals. It should be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted as a single element in fig. 1B, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

Transceiver 120 may be configured to modulate signals to be transmitted by transmit/receive element 122 and demodulate signals received by transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, therefore, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker/microphone 124, a keypad 126, and/or a display/touchpad 128, such as a Liquid Crystal Display (LCD) display unit or an Organic Light Emitting Diode (OLED) display unit. The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include Random Access Memory (RAM), read Only Memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 may include a Subscriber Identity Module (SIM) card, a memory stick, a Secure Digital (SD) memory card, and the like. In other embodiments, the processor 118 may physically have no memory access information located on the WTRU 102, such as on a server or home computer (not shown), and store the data in that memory.

The processor 118 may receive power from the power source 134 and may be configured to allocate and/or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry battery packs (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114 b) over the air interface 116 and/or determine its location based on the timing of signals received from two or more nearby base stations. It should be appreciated that the WTRU 102 may acquire location information by any suitable location determination method while remaining consistent with an embodiment.

The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software modules and/or hardware modules that provide additional features, functionality, and/or wired or wireless connectivity. For example, the number of the cells to be processed, peripheral devices 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (for photographs and/or video), universal Serial Bus (USB) ports, vibrating devices, television transceivers, hands-free headphones, and the like,Modules, frequency Modulation (FM) radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and/or augmented reality (VR/AR) devices, and activity trackers, among others. The peripheral devices 138 may include one or more sensors, which may be one or more of gyroscopes, accelerometers, hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors, geographic position sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and/or humidity sensors.

WTRU 102 may include a full duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and/or simultaneous. The full duplex radio station may comprise an interference management unit 139 for reducing and/or substantially eliminating self-interference via hardware (e.g. choke) or via signal processing by a processor (e.g. a separate processor (not shown) or via processor 118). In embodiments, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or downlink (e.g., for reception)).

Fig. 1C is a system diagram illustrating a RAN 104 and a CN 106 according to an embodiment. As noted above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using an E-UTRA radio technology. RAN 104 may also communicate with CN 106.

RAN 104 may include enode bs 160a, 160B, 160c, but it should be understood that RAN 104 may include any number of enode bs while remaining consistent with an embodiment. The enode bs 160a, 160B, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102B, 102c over the air interface 116. In one embodiment, the evolved node bs 160a, 160B, 160c may implement MIMO technology. Thus, the enode B160a may use multiple antennas to transmit wireless signals to and/or receive wireless signals from the WTRU 102a, for example.

Each of the evolved node bs 160a, 160B, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and/or DL, and the like. As shown in fig. 1C, the enode bs 160a, 160B, 160C may communicate with each other over an X2 interface.

The CN 106 shown in fig. 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the evolved node bs 162a, 162B, 162c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating the user of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, and the like. MME 162 may provide a control plane function for switching between RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and/or WCDMA.

SGW 164 may be connected to each of the evolved node bs 160a, 160B, 160c in RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102 c. The SGW 164 may perform other functions such as anchoring user planes during inter-enode B handover, triggering paging when DL data is available to the WTRUs 102a, 102B, 102c, and managing and storing the contexts of the WTRUs 102a, 102B, 102 c.

The SGW 164 may be connected to a PGW 166 that may provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network (such as the PSTN 108) to facilitate communications between the WTRUs 102a, 102b, 102c and legacy landline communication devices. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers.

Although the WTRU is described in fig. 1A-1D as a wireless terminal, it is contemplated that in some representative embodiments such a terminal may use a wired communication interface with a communication network (e.g., temporarily or permanently).

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in an infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP may have an access or interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic to and/or from the BSS. Traffic originating outside the BSS and destined for the STA may arrive through the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, e.g., where the source STA may transmit traffic to the AP and the AP may deliver the traffic to the target STA. Traffic between STAs within a BSS may be considered and/or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between a source STA and a target STA (e.g., directly between them) using Direct Link Setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunnel DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all STAs among STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

When using the 802.11ac infrastructure mode of operation or similar modes of operation, the AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access/collision avoidance (CSMA/CA) may be implemented, for example, in an 802.11 system. For CSMA/CA, STAs (e.g., each STA), including the AP, may listen to the primary channel. If the primary channel is listened to/detected by a particular STA and/or determined to be busy, the particular STA may backoff. One STA (e.g., only one station) may transmit at any given time in a given BSS.

High Throughput (HT) STAs may communicate using 40MHz wide channels (e.g., via a combination of a primary 20MHz channel and an adjacent or non-adjacent 20MHz channel) to form a 40MHz wide channel.

Very High Throughput (VHT) STAs may support channels that are 20MHz, 40MHz, 80MHz and/or 160MHz wide. The 40MHz channel and/or the 80MHz channel may be formed by combining consecutive 20MHz channels. The 160MHz channel may be formed by combining 8 consecutive 20MHz channels, or by combining two non-consecutive 80MHz channels (this may be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data may pass through a segment parser that may split the data into two streams. An Inverse Fast Fourier Transform (IFFT) process and a time domain process may be performed on each stream separately. These streams may be mapped to two 80MHz channels and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be transferred to a Medium Access Control (MAC).

The 802.11af and 802.11ah support modes of operation below 1 GHz. Channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11 ac. The 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the television white space (TVWS) spectrum, and the 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter type control/machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including supporting (e.g., supporting only) certain bandwidths and/or limited bandwidths. MTC devices may include batteries with battery lives above (greater than) a threshold (e.g., to maintain very long battery lives).

WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11 ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by STAs from all STAs operating in the BSS (which support a minimum bandwidth mode of operation). In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only) 1MHz modes, the primary channel may be 1MHz wide, even though the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and/or other channel bandwidth modes of operation. The carrier sense and/or Network Allocation Vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example because the STA is transmitting to the AP (supporting only 1MHz mode of operation), the entire available frequency band may be considered busy even though most of the frequency band remains idle and possibly available.

The available frequency band for 802.11ah in the united states is 902MHz to 928MHz. In korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

Fig. 1D is a system diagram illustrating a RAN 113 and a CN 115 according to an embodiment. As noted above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, 102c over an air interface 116. RAN 113 may also communicate with CN 115.

RAN 113 may include gnbs 180a, 180b, 180c, but it should be understood that RAN 113 may include any number of gnbs while remaining consistent with an embodiment. Each of the gnbs 180a, 180b, 180c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, gnbs 180a, 180b, 180c may implement MIMO technology. For example, gnbs 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from gnbs 180a, 180b, 180 c. Thus, the gNB 180a may use multiple antennas to transmit wireless signals to and/or receive wireless signals from the WTRU 102a, for example. In an embodiment, the gnbs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on the unlicensed spectrum while the remaining component carriers may be on the licensed spectrum. In an embodiment, the gnbs 180a, 180b, 180c may implement coordinated multipoint (CoMP) techniques. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180 c).

The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using transmissions associated with the scalable parameter sets. For example, the OFDM symbol interval and/or OFDM subcarrier interval may vary from one transmission to another, from one cell to another, and/or from one portion of the wireless transmission spectrum to another. The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of various lengths or of a length that can be extended (e.g., including different numbers of OFDM symbols and/or absolute time lengths that vary continuously).

The gnbs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in an independent configuration and/or in a non-independent configuration. In a standalone configuration, the WTRUs 102a, 102B, 102c may communicate with the gnbs 180a, 180B, 180c while also not accessing other RANs (e.g., such as the enode bs 160a, 160B, 160 c). In an independent configuration, the WTRUs 102a, 102b, 102c may use one or more of the gnbs 180a, 180b, 180c as mobility anchor points. In an independent configuration, the WTRUs 102a, 102b, 102c may use signals in unlicensed frequency bands to communicate with the gnbs 180a, 180b, 180 c. In a non-standalone configuration, the WTRUs 102a, 102B, 102c may communicate/connect with the gnbs 180a, 180B, 180c while also communicating/connecting with another RAN (such as the enode bs 160a, 160B, 160 c). For example, the WTRUs 102a, 102B, 102c may implement DC principles to communicate with one or more gnbs 180a, 180B, 180c and one or more enodebs 160a, 160B, 160c substantially simultaneously. In a non-standalone configuration, the enode bs 160a, 160B, 160c may act as mobility anchors for the WTRUs 102a, 102B, 102c and the gnbs 180a, 180B, 180c may provide additional coverage and/or throughput for serving the WTRUs 102a, 102B, 102 c.

Each of the gnbs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and/or DL, support of network slices, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Functions (UPFs) 184a, 184b, and routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, etc. As shown in fig. 1D, gnbs 180a, 180b, 180c may communicate with each other through an Xn interface.

The CN 115 shown in fig. 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it should be understood that any of these elements may be owned and/or operated by an entity other than the CN operator.

AMFs 182a, 182b may be connected to one or more of gNB 180a, 180b, 180c in RAN 113 via an N2 interface and may act as a control node. For example, the AMFs 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMFs 182a, 182b may use network slices to customize CN support for the WTRUs 102a, 102b, 102c based on the type of services utilized by the WTRUs 102a, 102b, 102 c. For example, different network slices may be established for different use cases, such as services relying on ultra-high reliability low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and/or services for Machine Type Communication (MTC) access, etc. AMF 162 may provide control plane functionality for switching between RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-a Pro, and/or non-3 GPP access technologies, such as WiFi.

The SMFs 183a, 183b may be connected to AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to UPFs 184a, 184b in the CN 115 via an N4 interface. SMFs 183a, 183b may select and control UPFs 184a, 184b and configure traffic routing through UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, ethernet-based, and the like.

UPFs 184a, 184b may be connected to one or more of the gnbs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to a packet-switched network, such as the internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-host PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring, among others.

The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may connect to the local Data Networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

In view of the fig. 1A-1D and the corresponding descriptions of fig. 1A-1D, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-102D, base stations 114a-114b, evolved nodes B 160a-160c、MME 162、SGW 164、PGW 166、gNB 180a-180c、AMF 182a-182b、UPF 184a-184b、SMF 183a-183b、DN 185a-185b, and/or any other devices described herein may be performed by one or more emulating devices (not shown). The emulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation device may be used to test other devices and/or analog network and/or WTRU functions.

The simulated device may be designed to enable one or more tests of other devices in a laboratory environment and/or in an operator network environment. For example, one or more emulated devices may perform one or more functions or all functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. One or more emulation devices can perform one or more functions or all functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and/or may perform testing using over-the-air wireless communications.

One or more emulation devices can perform one or more (including all) functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the simulation device may be used in a test laboratory and/or a test scenario in a non-deployed (e.g., test) wired and/or wireless communication network in order to enable testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and/or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation device to transmit and/or receive data.

Fig. 2 depicts an example handover scenario in a New Radio (NR). At step 0, the context of the WTRU within the source gNB 204 may be provided by an access and mobility management function (AMF). The WTRU context may include information about roaming and access restrictions, which may be provided at connection setup or at the time of the last Timing Advance (TA) update. At step 1, the source gNB 204 configures the WTRU measurement procedures and the WTRU 202 reports according to the measurement configuration. At step 2, the source gNB 204 may decide to handover the WTRU 202 based on the received measurements.

At step 3, the source gNB 204 then issues a handover request message to the target gNB 206, e.g., by passing a transparent Radio Resource Control (RRC) container with the necessary information for preparing the handover at the target side. The information may include at least a C-RNTI (radio link identifier) of the target cell ID, kgNB, WTRU 202 in the source gNB 204, a Radio Resource Management (RRM) configuration including WTRU inactivity time, a basic AS configuration including antenna information and/or DL carrier frequency, current QoS flow to Data Radio Bearer (DRB) mapping rules applied to the WTRU 202, SIB1 from the source gNB 204, WTRU capabilities for different RATs, and/or PDU session related information. Further, in some examples, the information may also include measurement information reported by the WTRU, including beam-related information (if available). Thereafter, at step 4, admission control may be performed by the target gNB 206. Further, if the WTRU 202 is admitted, the target gNB 206 prepares a handover with L1/L2 and transmits a handover request acknowledgement to the source gNB 204 at step 5, which may include a transparent container to be transmitted as an RRC message to the WTRU 202 to perform the handover.

Once the handover request acknowledgement has been delivered, handover execution begins so that the WTRU 202 may be separated from the old cell and synchronized to the new cell. In step 6, the source gNB 202 triggers a Uu handover by transmitting RRCReconfiguration a message to the WTRU 202, the RRCReconfiguration message containing information required to access the target cell, such as a target cell ID, a new C-RNTI, and/or a target gNB security algorithm identifier for the selected security algorithm. The RRCReconfiguration message may also include any combination of a set of dedicated Random Access Channel (RACH) resources, an association between RACH resources and Synchronization Signal Blocks (SSBs), an association between RACH resources and WTRU-specific CSI Reference Signal (RS) configuration, system information of common RACH resources and target cells, etc. In some examples, the buffered data and new data are delivered from the UPF 210.

As the separation begins, in step 7, the source gNB 204 conveys early transition state transition data and SN state transition messages to the target gNB to convey an uplink PDCP SN receiver state and a downlink PDCP SN transmitter state of the DRB to which PDCP state reservation (e.g., for Radio Link Control (RLC) AM) is applied. User data may be provided to source gNB 202 and then to target gNB 206. In step 8, the WTRU 202 synchronizes to the target cell and completes the RRC handover procedure by transmitting RRCReconfigurationComplete a message to the target gNB 206.

In the handover complete portion of the scenario, in step 8a, a HO success signal may be transmitted from the target gNB 206 to the source gNB 204, where the source gNB 204 provides SN status transfer (step 8 b). At step 9, target gNB 206 transmits a path switch request message to AMF 208 to trigger 5GC to switch DL data paths towards target gNB 206 and establish NG-C interface instances towards target gNB 206. In this step 10, the 5GC switches the DL data path toward the target gNB 206. The UPF 210 transmits one or more "end-marker" packets to the source gNB 202 on the old path for each PDU session/tunnel, and then any U-plane/TNL resources may be released towards the source gNB 202. In step 11, the AMF 208 acknowledges the path switch request message with a path switch request acknowledgement message. Upon receiving the path switch request acknowledgement message from the AMF 208, the target gNB 206 transmits a WTRU context release to inform the source gNB 204 of the success of the handover. The source gNB 204 may then release the radio and C-plane related resources associated with the WTRU context in step 12. In addition, any ongoing data forwarding may continue.

NR release 16 introduces the concept of Conditional Handover (CHO) and conditional primary and secondary serving cell (PSCell) addition/change (CPA/CPC, or collectively CPAC), which has the potential to reduce the likelihood of Radio Link Failure (RLF) and handover failure (HOF).

Conventional LTE/NR handover may typically be triggered by measurement reports, and nothing prevents the network from transmitting HO commands to the WTRU even in the absence of a received measurement report. For example, the WTRU may be configured with an A3 event that triggers the transmission of a measurement report when the radio signal level/quality (e.g., reference Signal Received Power (RSRP), reference Signal Received Quality (RSRQ), etc.) of the neighbor cell becomes better than the primary serving cell (PCell) or better than the PSCell in the case of DC. The WTRU monitors the serving cell and the neighboring cell and may transmit a measurement report when a condition is met. Upon receiving such a report, the network (e.g., the current serving node/cell) may prepare the HO command. The HO command may be an RRC reconfiguration message with reconfiguration WithSync, which may be transmitted to the WTRU, which immediately executes the HO command, resulting in the WTRU being connected to the target cell.

CHO may be different from conventional handover. For example, a plurality of handover targets are prepared. Furthermore, the WTRU may not immediately perform CHO. The WTRU may be configured with a trigger condition (such as a set of radio conditions) and if the trigger condition is met, the WTRU may perform a handover towards one of the targets.

The CHO command may be transmitted while radio conditions towards the current serving cell are still good, thereby reducing the risk of inter alia transmitting measurement reports failing (e.g., in case the link quality to the current serving cell drops below (e.g., below) an acceptable level when the measurement report is triggered in normal handover) and receiving handover commands failing (e.g., in case the link quality to the current serving cell drops below an acceptable level after the WTRU has transmitted the measurement report but before it receives the HO command).

Fig. 3 illustrates an example of conditional handover configuration and execution. As contemplated in fig. 3, the trigger conditions for CHO may include any combination of the following. In step 1, the request may also be based on the radio quality of the serving cell/source node 304 and neighboring cells/potential target nodes 306, e.g. the conditions used to trigger measurement reporting in conventional LTE/NR. A CHO request from source node 304 to potential destination node 306 (e.g., from step 1) may result in CHO request acknowledgement in step 2 (e.g., RRCReconfiguration).

In step 3, the WTRU 302 may be configured with CHO with A3 (or A5) like trigger condition and associated HO command. In step 4, the WTRU 302 monitors the current cell and the serving cell for target cell candidates. When the A3 (or A5, for example) trigger condition is met, the WTRU may perform an associated HO command in step 6 (e.g., instead of or in addition to transmitting a measurement report). The WTRU 302 may switch its connection towards the target cell/target node 306. In step 7, the target node 306 may perform path switching and/or release context.

CHO may help prevent unnecessary re-establishment in case of radio link failure. For example, the WTRU may be configured with multiple CHO targets and the WTRU experiences RLF before trigger conditions with any of these targets are met. Conventional operations may result in an RRC reestablishment procedure that may also cause a significant interruption time of the WTRU's bearers. However, in the case of CHO, if the WTRU terminates its cell with CHO associated with it after RLF is detected (i.e., it may have already prepared a target cell for it), the WTRU may directly execute the HO command associated with the target cell instead of continuing the full re-establishment procedure.

CPC and CPA may be extensions of CHO, but in DC scenarios. Further, the WTRU may be configured with a trigger condition for a PSCell change or addition, and when the trigger condition is met, it may execute an associated PSCell change or PSCell addition command.

The measurement configuration provided to the WTRU may include any combination of the following. The measurement configuration may include a measurement object, a reporting configuration, a measurement ID configuration, an S-measurement configuration, a quantity configuration, and/or a measurement gap configuration. Although the present disclosure is mainly described in the context of measurement objects, reporting configurations and measurement ID configurations, the idea is applicable to measurement configurations including any of the foregoing configurations.

The measurement object may specify what the WTRU must measure and/or information about how the measurement may be performed. In embodiments, this information may include, for example, RAT, frequency, subcarrier spacing, SSB periodicity/offset/duration, reference signals and signal types to be measured, list of allowed/excluded neighbor cells for the RAT/frequency of interest to be measured, measurement gap, offset applicable to prioritizing/de-prioritizing certain cells, and so forth.

The WTRU may be configured with multiple measurement objects and may have measurement configurations that may be related to different frequencies or even different RATs. The WTRU may be configured with up to 64 measurement objects, and each measurement object may be identified by a measurement object ID.

The reporting configuration may specify what content to report (e.g., reference signal type (such as CSI-RS or SSB), number of beams and cell levels to report (such as RSRP/RSRQ), maximum number of cells or/and beams to report, etc.), and/or reporting criteria. In response to receiving the reporting configuration, the WTRU may transmit a measurement report or perform an associated HO configuration in the case of CHO. The reporting criteria may be the expiration of a periodic timer (e.g., periodic reporting configuration) or based on some radio conditions of the serving cell and/or neighboring cells. The WTRU may be configured with up to 64 reporting configurations, and each reporting configuration may be identified by a reporting configuration ID.

The measurement object may be associated with one or more reporting configurations. The association may be by measuring the ID. For example, the measurement ID configuration may be a list of measurement IDs, measurement object IDs, and/or report configuration IDs. As noted herein, a WTRU may be configured with up to 64 measurement IDs.

The WTRU may be configured with event triggered reporting by any of event A1, where the serving cell becomes greater than a threshold, event A2, where the service becomes less than a threshold, event 3, where the neighbor becomes offset greater than SpCell, event A4, where the neighbor becomes greater than a threshold, event A5, where the SpCell becomes less than threshold 1 and the neighbor becomes greater than threshold 2, event A6, where the neighbor becomes offset greater than SCell, event B1, where the inter-RAT neighbor becomes greater than a threshold, and/or event B2, where the PCell becomes less than threshold 1 and the inter-RAT neighbor becomes greater than threshold 2. The term SpCell may be used herein to refer to a PCell (primary cell), or in the case of DC, to a primary secondary cell (PSCell). Events A3, A5, B2 may be configured for (e.g., only configured for) PCell or PSCell. However, it is contemplated that events A1, A2, A3, A5, B2 may be configured for any serving cell. Event A6 may be configured for scells (e.g., for scells only, such as for secondary cells in Carrier Aggregation (CA)). Events A4 and B1 may be related to neighbor cell measurements (e.g., and may not be related to any serving cell).

In the CHO case, it is contemplated that the WTRU may perform HO commands instead of transmitting measurement reports when reporting conditions are met. In the case of CHO, the event triggered reporting configuration may be defined to include one or more of CondEvent A where the neighbor becomes offset greater than SpCell, condEvent A where the neighbor becomes greater than a threshold, condEvent A5 where SpCell becomes less than threshold 1 and the neighbor becomes greater than threshold 2.

CHO configurations may include a condition reconfiguration ID, a condition reconfiguration trigger condition, and/or an RRC reconfiguration (e.g., HO command) to be performed when the condition is satisfied. The trigger condition may be a reference to 1 or 2 measurement IDs, and if 2 measurement IDs are specified, the two measurement IDs generally refer to the same measurement object (e.g., one measID associates the PCell related measurement object with an A3 event and another measID associates the same measurement object with an A5 event). In release 17, the WTRU may be configured with a maximum of 8 CHO configurations.

The WTRU typically maintains the PCell in an active state (e.g., the WTRU continuously monitors the PDCCH of the PCell), while the SCell and PSCell may take states other than the active state. These other states may include a deactivated/deactivated state, which may be a power saving state for a WTRU with a configured SCell or PSCell of interest but not performing any active UL/DL transmission/reception via the cell of interest. In the case of PSCell, the WTRU may perform some processing related to PSCell, such as radio link monitoring and beam fault detection. Another state for scells and PCell may include a dormant state, which may be applicable only to scells and may be considered an intermediate state between a deactivated state and an active state. The dormant state may be similar to the inactive state in that the WTRU stops PDCCH monitoring for the SCell of interest, but the dormant state may be similar to the active state in that the WTRU still performs CSI/CQI measurements and beam management for the SCell. Thus, the network may be aware of the current channel state of the SCell, and the SCell in dormant state (e.g., or also referred to as the SCell in dormant) may be activated quickly when needed (e.g., a greater data rate/capacity may be needed for the WTRU).

Within NR release 17, inter-cell L1/L2 mobility can manage beams in the CA case without supporting cell change/addition. In release 18, one of the envisaged purposes may be to specify a mechanism and procedure for L1/L2 based inter-cell mobility for reducing mobility latency. In an embodiment, mechanisms and procedures for L1/L2 based inter-cell mobility to reduce mobility latency may be specified. Configuration and maintenance for multiple candidate cells may be specified to allow quick application of configuration for candidate cells (RAN 2, RAN 3). Dynamic handover mechanisms in candidate serving cells (e.g., including special cells (spcells) and scells) for potentially applicable scenarios based on L1/L2 signaling (RAN 2, RAN 1) may also be provided. SpCell may refer to the PCell of an MSG or the PSCell of a Secondary Cell Group (SCG), depending on whether the MAC entity is associated with a primary cell group (MCG) or an SCG. L1 enhancements may be provided for inter-cell beam management, including L1 measurements and reporting, as well as beam pointing (RAN 1, RAN 2). Early RAN2 participation may be necessary, including further elucidating the possibilities of interaction with dynamic handoffs. Timing advance management (RAN 1, RAN 2) and CU-DU interface signaling may also be provided to support L1/L2 mobility (if needed, (RAN 3)). FR2 specific enhancements may not be excluded. Furthermore, the L1/L2 based inter-cell mobility procedure is applicable to various scenarios such as independent deployment of serving cells changing within one configured grant or Cell Group (CG), CA and NR-DC cases, intra-DU cases and inter-CU DU cases (applicable to independent deployment and CA when a new RAN interface is not desired), intra-frequency, inter-frequency, FR1, FR2, source and target cells synchronized or unsynchronized and inter-CU not included cases.

L1/L2 based mobility initially starts in NR release 17 and inter-cell beam management in release 17 solves the problem of intra-DU scenarios and intra-frequency scenarios. In this case, the serving cell remains unchanged (i.e., it is impossible to change the serving cell using L1/L2-based mobility). In FR2 deployments, CA may typically be used in order to utilize the available bandwidth, e.g., to aggregate multiple CCs in one frequency band. These CCs are typically transmitted with the same pair of analog beams (the gNB beam and the WTRU beam). The WTRU may be configured with TCI status (which may have a significant number, e.g., 64) for receiving a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH). Each TCI state includes an RS or SSB that the WTRU references to set its beam. For release 17, ssb may be associated with a non-serving PCI. MAC signaling ("TCI status indication for WTRU-specific PDCCH MAC Control Element (CE)) activates the TCI status for Coreset/PDCCH. Receiving a PDCCH from a non-serving cell may be supported by a MAC CE indicating a TCI state associated with the non-serving PCI. MAC signaling ("TCI state activation/deactivation for WTRU-specific PDSCH") activates a subset of (up to) 8 TCI states for PDSCH reception. Downlink Control Information (DCI) indicates a specific TCI state among 8 TCI states. Release 17 also supports a "unified TCI state" with different update mechanisms (based on DCI) but without multiple transmit/receive points (TRP). Version 18 may support a unified TCI state with multiple TRPs.

L1/L2 inter-cell mobility may be used to improve handover delay, either with conventional L3 handover or on condition that the WTRU first uses RRC signaling to transmit measurement reports. In response, the network may provide additional measurement configurations and potential CHO configurations. With CHO, after the WTRU reports that the cell meets the configured radio quality criteria using RRC signaling, the network provides configuration for the target cell. For conditional handover, to reduce the handover failure rate due to delays in transmitting measurement reports and then receiving RRC reconfiguration, the network provides the target cell configuration in advance and measurement criteria to determine when the WTRU may trigger CHO configuration. Both L3 methods may lead to a certain amount of delay due to the transmission of measurement reports and the reception of target configurations, especially in case of regular (unconditional) handover.

L1/L2 based inter-cell mobility may allow for fast application of configuration for candidate cells, including dynamic handover between scells and handover of PCell (e.g., switching roles between SCell and PCell), without performing RRC signaling. inter-CU cases are not included in release 18 because this requires relocation of the PDCP anchor and has been excluded from the work item. An RRC-based approach may be desirable, such as to support inter-CU handover. L1/L2 may allow CA operation to be enabled immediately upon a serving cell change.

Fig. 4 illustrates an example of an L1/L2 inter-cell mobility operation using Carrier Aggregation (CA), whereby candidate cell groups may be configured by RRC and dynamic handover of PCell and SCell may be achieved using L1/L2 signaling.

As discussed herein, release 18 does not introduce support for inter-CU handover using L1/L2 signaling. Therefore, regular or conditional handoffs may be required to cover at least this situation. Conventional or conditional handoffs may be required to support any mobility from any particular L1/L2 mobility region to another mobility region. As shown in fig. 5, L1/L2 inter-cell mobility may be deployed only in certain areas. Furthermore, the network may divide its deployment into multiple L1/L2 mobility areas for other reasons (such as cell planning) or due to limitations on the maximum number of cell configurations that may be stored in the WTRU 402 at the same time.

Fig. 5 shows a scenario where there are two gnbs, a first gNB being serving cells 1 to 3 and a second gNB being serving cells 4 to 8. The WTRU may first be in the first gNB and configured with CHO configuration towards cell 4 of the second gNB. While in the coverage area of the first gNB, L1/L2 signaling may be used to add/remove or activate/deactivate different SCells. Although not shown in the drawings, the PCell may be switched to the SCell using L1/L2, and vice versa.

CHO trigger conditions may be based on events (e.g., condA/A5) based on serving PCell and/or target PCell conditions. When CHO conditions are met and the WTRU hands over to the second gNB, in some examples, a proper set of scells to configure for the WTRU may not be optimally decided (e.g., because CHO triggers may not take into account radio conditions of candidate scells). Additionally, if L1/L2 mobility is desired to be utilized in the candidate gcb, the current mechanism may force the network (e.g., blindly) to configure possible cells (e.g., cell 5-cell 8) as candidate cells for the L1/L2 mobility candidate cell. In embodiments, it may be desirable to configure CHO so that the WTRU may not only select the best candidate PCell, but may also consider the conditions of serving SCell and candidate SCell.

The following discussion focuses primarily on the CHO case. However, embodiments may be applicable to the case of CPA or CPC (e.g., PSCell conditions instead of PCell conditions, and SCell refers to SCG SCell). Further, in the following description, it may be assumed that L1/L2 mobility signaling contains an indication that SCell is promoted to PCell. The associated configuration/signaling may also be applicable in case non-serving neighbor cells are also promoted to PCell. Further, in the following discussion, L1/L2 signaling may refer to MAC CE or DCI. In addition, the term "cell satisfaction threshold" is used to mean that the signal level of the cell may be higher than the signal level threshold associated with the cell. The terms "candidate" and "target" are also used interchangeably. It should be noted that embodiments may be applicable even without L1/L2 mobility (e.g., enhancements to traditional CHO operations).

The WTRU may be configured to perform CHO (e.g., separately) based on the signal levels of one or more candidate scells. For example, the WTRU may be configured with a CHO configuration containing trigger conditions for a particular candidate PCell, associated candidate scells that are added as additional carriers when CHO trigger conditions are met, and/or additional signal level thresholds (e.g., RSRP thresholds) for scells that the WTRU checks before adding scells.

In an embodiment, one signal level (e.g., RSRP) threshold may be configured for candidate scells. Upon performing CHO and applying CHO configuration when CHO trigger conditions for PCell are met, the WTRU may check the signal levels of candidate scells and apply (e.g., apply only) SCell configuration for those cells having signal levels that meet the configured threshold.

In an embodiment, a different signal level threshold may be configured for each candidate SCell. For example, different semaphores may be associated with the threshold of a given candidate SCell (e.g., SCell1 having an RSRQ threshold associated therewith, SCell2 having an RSRP threshold associated therewith, etc.).

The signal level threshold may be associated with a subset of candidate scells. In an embodiment, for example, a cell list (e.g., a PCI list) may be associated with a particular threshold. In an embodiment, a particular threshold may be associated with a cell of a given frequency or a given frequency range. As another example, a particular set of cells may have a threshold that may be related to RSRQ, while other sets of cells have a threshold that is related to RSRP.

The WTRU may be configured to apply the configuration of all candidate scells that meet their corresponding thresholds. In an embodiment, the WTRU may be configured to apply a configuration of up to N (e.g., where N may be configured by the network or fixed in 3GPP specifications) best candidate scells that meet their corresponding thresholds.

The WTRU may be configured with different prioritization of candidate scells (e.g., based on frequency or other network-specific reasons), and if more than N candidate scells meet their corresponding thresholds, the WTRU may rank the candidate scells according to their priorities and may apply the configuration of the first N of the candidate scells (i.e., if SCellx has a higher priority than SCelly and SCellx still meets its corresponding threshold, candidate SCellx with a signal level lower than SCelly may ultimately be selected).

The signal levels of the PCell and the candidate scells may be considered together. In an embodiment, CHO execution conditions may consider both the candidate PCell signal level and the candidate SCell signal level. For example, in case (e.g., only if) both the candidate PCell and the one or more candidate scells meet the configured threshold, the trigger condition for CHO to a specific candidate PCell may be considered to be met.

CHO execution conditions may consider average measurements between more than one candidate cell. For example, the triggering condition may be considered to have been met if one or more of (a) if the average signal level of all candidate cells is above a threshold, (b) if the average signal level of all candidate cells is greater than the average signal level of all current serving cells by more than a certain threshold, (c) if the average of the N best candidate cells is above a threshold, (d) if the average of the N best candidate cells is greater than the average of the N best current serving cells by more than a certain threshold, etc.

During averaging, the PCell and/or candidate PCell may carry a larger weight than the SCell and candidate scells, e.g., assuming that there are 3 serving scells and 4 candidate scells. The average value of the serving cell may be calculated as:

f_ rsrp _pcell+ (1-f) (rsrp _scell1+ rsrp _scell2+ rsrp _scell3)/3, and for a candidate cell, it can be calculated as:

f*rsrp_PCell+(1-f)*(rsrp_candidate_SCell1

+rsrp_candidate_SCell2+rsrp_candidate_SCell3

+rsrp_candidate_SCell4)/4。

The scaling/weighting factor may be the same for all scells or may be different for each SCell. The scaling/weighting factors may be configured by the network or may be predefined in the standard.

In embodiments, averaging may be performed on scells (e.g., only scells), while candidate pcells may be compared separately (e.g., with an absolute threshold or a relative threshold compared to the current PCell). Alternatively or additionally, averaging may be performed on candidate scells. In some examples, the candidate PCell may be compared to an absolute threshold, and the candidate scells may be averaged and compared to the absolute threshold. A trigger condition for CHO may be considered to be fulfilled if the candidate PCell is above a certain threshold and the average signal level of all candidate scells is above a certain threshold and/or if the candidate PCell is above a certain threshold and the average signal level of the N best candidate scells is above a certain threshold.

In some examples, the candidate PCell may be compared to an absolute threshold, and the candidate scells may be averaged and may be compared to an average of the current scells, where the trigger condition for CHO may be considered satisfied if the candidate PCell is above a certain threshold and the average signal level of all candidate scells is greater than the average signal level of all current serving scells by more than a certain threshold, and/or if the candidate PCell is above a certain threshold and the average signal level of the N best candidate scells is greater than the average signal level of the N best current serving cells by a certain threshold.

In an embodiment, the candidate PCell may be compared to the current PCell, the candidate scells averaged and compared to an absolute threshold and an average of the current SCell. A trigger condition for CHO may be considered to be met if the candidate PCell is greater than the current PCell and the average signal level of all candidate scells is greater than a certain threshold, and/or the candidate PCell has a certain threshold greater than the current PCell and the average signal level of all N best candidate scells is greater than a certain threshold.

In an embodiment, the candidate PCell is compared to the current PCell, the candidate scells are averaged and compared to the average of the current scells. For example, the trigger condition for CHO may be considered to be met if the candidate PCell is greater than the current PCell by a certain threshold and the average signal level of the N best candidate scells is greater than the average signal level of all current serving scells by more than a certain threshold, and/or if the candidate PCell is higher than the current PCell and the average signal level of the N best candidate scells is greater than the average signal level of the N best current serving cells by a certain threshold.

In embodiments, the same measurement quantity (e.g., RSRP or RSRQ) and associated threshold values may be configured for all candidate scells as well as candidate pcells. For example, the same measurement quantity (e.g., RSRP or RSRQ) and associated threshold may be configured for all candidate scells, but different measurement quantities and associated thresholds may be configured for candidate pcells. Candidate scells may be associated with different thresholds or even different measurement quantities (e.g., RSRP or RSRQ). This may be different for each candidate SCell or the same for a particular set of candidate scells.

The SCell to be added may be selected based on a relative comparison of signal levels of candidate scells. For example, the WTRU may be configured with a CHO configuration containing trigger conditions for a particular target PCell, the associated SCell to be added as an additional carrier. The maximum number of scells that can be added when CHO trigger conditions are met may be further defined. For example, the WTRU may perform (a) identifying the best candidate scells in each frequency, (b) ordering the candidate scells according to signal quality, and/or (c) taking the first m scells (e.g., where m equals the maximum number of configured scells) and applying their corresponding SCell configuration when the CHO trigger condition (based on the target PCell) is met. A signal level threshold may be specified (e.g., in addition to the maximum number of scells). For example, when configured in this manner, the WTRU may perform (a) identifying the best SCell candidate in each frequency that also satisfies the configured threshold when a CHO trigger condition is satisfied (e.g., based on the target PCell), (b) ordering the candidate scells according to signal quality, and/or (c) taking the first m scells (e.g., where m is equal to the maximum number of scells configured) and applying the corresponding SCell configuration.

The signal level threshold may be the same for all scells. For example, the signal level threshold may be specified per candidate SCell or per a given set of scells. The signal level threshold may be specified per carrier frequency or per a given set/range of carrier frequencies.

The WTRU may determine which SCell(s) to activate based on any combination of factors. For example, the WTRU may add an SCell in an active state, a deactivated state, or a dormant state when the WTRU decides to apply a given SCell configuration when the CHO trigger condition and SCell addition condition described above are met. In embodiments, the WTRU may be configured to determine SCell status (e.g., active, inactive, dormant) based on a signal level threshold or a maximum number of cells. In an embodiment, two thresholds may be configured, wherein candidate scells having a signal level above a first threshold are added as activated scells, candidate scells having a signal level between the first threshold and a second threshold are added as dormant scells, and candidates having a signal level below/less than the second threshold are added as deactivated scells. In embodiments, the WTRU may be configured with a maximum number of scells to be added to an active state (e.g., n_active), a inactive state (e.g., n_inactive), or/and a dormant state (e.g., n_dormant), and the WTRU may add the best n_active candidate cell as an active SCell, the next n_dormant best cell as a dormant SCell, and the next n_inactive best cell as a inactive SCell.

The conditions of the threshold and the maximum cell number may be combined. In an embodiment, an additional threshold may be specified, and SCell may not be added at CHO execution if its signal level is below the associated threshold. Furthermore, in embodiments, as in the previous section, the threshold may be common for all frequencies/scells, or may be different for each frequency/SCell.

The WTRU may be configured to determine a candidate set list for L1/L2 mobility. For example, the WTRU may be configured to release SCell configurations (e.g., for the above embodiments) of candidate cells that do not satisfy the SCell addition condition. The WTRU may be configured to store SCell configurations of candidate cells that do not satisfy SCell addition conditions (e.g., according to any of the embodiments described above) and treat them as part of the L1/L2 mobility set. For example, the WTRU may expect a future L1/L2 mobility indication, which may indicate that a cell within the mobility set becomes an SCell or even a PCell. In embodiments, a combination of the two is possible. In an embodiment, the WTRU may be configured to add a particular SCell (e.g., signal level above/greater than a particular threshold, the first n cells, etc.), maintain the configuration of the particular cell as part of the L1/L2 mobility set list (e.g., signal level between two thresholds, etc.), and release the configuration of the particular cell (e.g., signal level below a particular threshold).

The WTRU may be configured with multiple L1/L2 mobility candidate set lists that may be applied when performing CHO. In performing CHO, the candidate set to be applied may depend on the results of CHO evaluations. For example, in case the target PCell satisfies a conditional triggering condition, the set of scells or L1/L2 candidate cells to be configured may depend on the result of SCell/target candidate cell measurements. In an embodiment, if target candidate cell 1 is greater than candidate cell 4, L1/L2 candidate set a (e.g., cells 1,2, 3) may be applied, while if target candidate cell 4 is greater than candidate cell 1, L1/L2 candidate set B (e.g., cells 4, 5, 6) may be applied. The result of the comparison of cell 1 and cell 4 is an indicator of the area of the PCell that the WTRU has entered, and thus these candidate cells are most likely to be used. In an embodiment, where the WTRU may enter the PCell in northwest, then cells 1,2,3 are the most likely and cell 1 has a larger measurement than cell 4, while the WTRU enters the PCell in northwest, then cells 4, 5, 6 are the most likely and cell 4 has a larger measurement than cell 1.

The WTRU may transmit a response signal. For example, the WTRU may inform the network of the decision regarding candidate scells, which the WTRU has applied according to any of the embodiments described above. Further, the WTRU may provide to the network one or more of (a) scells that have been added (e.g., whose configuration has been applied), (b) candidate scells that have not been added, (c) state of scells that have been added (e.g., activated, deactivated, dormant), (d) candidate scells that have been released, (e) candidate scells that have not been added but remain part of the L1/L2 mobility set, and/or (f) measurements of candidate/added/released scells. Other information is provided in addition to or separately from the above list. The content of the response may be based on whether the configuration information is associated with the measurement report or CHO. For example, as noted above, the reporting configuration may specify what the WTRU is to report. The WTRU may transmit a measurement report if the reporting configuration designation is associated with the measurement report. If the reporting configuration is associated with CHO, the WTRU may perform CHO to the candidate PCell.

The indication of the added SCell may be included in an RRC reconfiguration complete message. The information about the SCell may be transmitted in a separate message, such as in another RRC message (e.g., autonomously by the WTRU or upon request from the network) or in a MAC CE.

With reference to the discussion above, in embodiments, the WTRU may receive a CHO configuration including one or more of (i) candidate PCell and associated signal level thresholds (e.g., absolute or relative to the current PCell) as CHO trigger conditions, (ii) a set of candidate scells and associated signal level thresholds (e.g., one threshold for all, a separate threshold for each, etc.), and/or (iii) RRC reconfiguration (e.g., HO command) to be applied when CHO conditions are met. The WTRU may further monitor CHO trigger conditions. Upon satisfaction of the CHO trigger condition, the WTRU may perform CHO, but only add scells that meet its threshold, and then transmit an indication to the network regarding the added scells and additional information, such as measurements of all candidate/added scells (e.g., in an RRC reconfiguration complete message, in a separate message, etc.).

The WTRU may receive a CHO configuration including one or more of (a) a set of candidate PCell and SCell as CHO trigger conditions and an associated average signal level threshold (e.g., absolute or relative to the serving cell) and/or (ii) an RRC reconfiguration (e.g., HO command) to apply when CHO conditions are met. The WTRU may monitor for CHO trigger conditions and perform CHO and transmit information to the network, such as measurements of candidate/added scells (e.g., in an RRC reconfiguration complete message, in a separate message, etc.), when CHO trigger conditions are met (e.g., average signal level of all candidate cells is above a configured threshold, average signal level of all candidate cells is greater than average signal level of all current serving cells by more than a configured threshold, etc.).

The WTRU may receive a CHO configuration including one or more of (i) candidate PCell and associated signal level threshold (e.g., absolute or relative to the current PCell) as CHO trigger conditions, (ii) a set of candidate scells and associated signal level threshold and a maximum number of scells that may be added (m) and/or (iii) RRC reconfiguration (e.g., HO command) to apply when CHO conditions are met. The WTRU may monitor CHO trigger conditions. Upon satisfaction of the CHO trigger condition, the WTRU may perform CHO (e.g., only add up to the first m scells that satisfy the SCell threshold). The WTRU may transmit an indication (e.g., in an RRC reconfiguration complete message, in a separate message, etc.) to the network regarding which scells are added and/or additional information (such as measurements of candidate/added scells).

The WTRU may receive a CHO configuration including one or more of (i) candidate PCell and associated signal level thresholds (e.g., absolute or relative to the current PCell) as CHO trigger conditions, (ii) a set of candidate scells and associated signal level thresholds (e.g., thresh1, thresh 2) and/or (iii) RRC reconfiguration (e.g., HO command) to be applied when CHO conditions are met. The WTRU may continue to monitor for CHO trigger conditions. Upon satisfaction of the CHO trigger condition, the WTRU may perform CHO while setting the state of the SCell according to (a) disabling the SCell if the signal level of the SCell is below thresh1, (b) setting the SCell to dormant if the signal level of the SCell is between thresh1 and thresh2 and/or (c) activating the SCell if the signal level of the SCell is above thresh 2. The WTRU then transmits an indication (e.g., in an RRC reconfiguration complete message, in a separate message, etc.) to the network regarding the state of the SCell and additional information, such as measurements of candidate/added scells.

Fig. 6 illustrates an example process 600 performed by a WRTU in response to receiving measurement event configuration information. At 602, a WTRU may be configured to receive measurement configuration information from a network device indicating a list of cells to measure. The cell list may include a serving primary cell (PCell), one or more serving secondary cells (scells), a candidate PCell, and one or more candidate scells. The configuration information may also include a first trigger condition related to at least one of the serving PCell or the candidate PCell. The configuration information may also include a second trigger condition related to at least one of the one or more serving scells or the one or more candidate scells.

At 604, the WTRU measures a cell configured to be measured. The radio conditions to be measured for the source PCell, the target PCell, the one or more source scells, and the one or more target scells may include, for example, one or more of absolute/relative thresholds of individual source/target PCell and source/target SCell, absolute/relative thresholds of averages of the source PCell and source SCell, and the target PCell and target SCell. Other signal quality conditions may also be included.

At 606, the WTRU monitors signals associated with the cell list to determine whether the first trigger condition and the second trigger condition are met. At 608, the WTRU determines whether the first trigger condition and the second trigger condition are met. If the trigger condition is not met, the WTRU continues to monitor for cells configured to be measured at 608. If the trigger condition is met at 608, the WTRU determines whether the measurement configuration is associated with a Conditional Handover (CHO) at 610. If the measurement is not associated with CHO at 610, the WTRU transmits a measurement report, such as a layer 1 (L1) or layer 3 (L3) measurement report, at 616. The report may include serving PCell/SCell, target PCell/SCell, or other measurements. If the measurement event is associated with CHO at 610, the WTRU performs CHO to the candidate PCell at 612. For example, at 614, the WTRU transmits an indication to the network indicating CHO. The message transmitted by the WTRU may be a HO complete message.

The measurement configuration information may include a specific indication of whether it is associated with a measurement report configuration or CHO configuration. The WTRU may also determine that a first trigger condition is met when the signal quality measurements of the candidate pcells exceed a first signal quality threshold, and may also determine that a second trigger condition is met when the signal quality measurements of at least one of the candidate scells exceed a second signal quality threshold. The WTRU may determine that the second trigger condition is met when the average signal quality of the one or more candidate scells exceeds a signal quality threshold.

The measurement configuration information may include an indication of a signal quality threshold for one or more of the candidate scells, and the WTRU may apply SCell configuration for the candidate scells having signal quality measurements exceeding the signal quality threshold. The WTRU may be configured to determine a state of each of the candidate scells having a signal quality measurement exceeding a signal quality threshold. The state of the candidate SCell may be an active state, an inactive state or a dormant state. The signal quality measurement may also exceed a signal quality threshold based on a maximum number of scells configurable by the WTRU. In an embodiment, multiple candidate scells may be associated with the same frequency. The WTRU then applies SCell configuration for the SCell with the highest signal quality measurement for multiple scells associated with the same frequency. Further, the WTRU may transmit a CHO complete message when performing CHO to the candidate PCell.

The WTRU may be configured to receive measurement configuration information indicating a trigger condition associated with CHO from a serving primary cell (PCell) to a candidate PCell. The candidate PCell may be associated with one or more candidate secondary cells (scells). The trigger condition may include a comparison of a measurement of a signal received from the serving PCell with a measurement of a signal received from the candidate PCell. The trigger condition may also include measurements associated with one or more candidate scells. The WTRU determines whether a first trigger condition is met based on a comparison of a measurement of a signal received from a serving PCell and a measurement of a signal received from a candidate PCell. The WTRU also determines whether a second trigger condition is met based on measurements associated with one or more candidate scells. Once both trigger conditions are met, the WTRU performs CHO and transmits a CHO complete message to the network. In an embodiment, the second trigger condition may be based on an average signal level of the serving PCell and the SCell and an average signal level of the target PCell and the SCell.

Claims (20)

1. A wireless transmit receive unit (WTRU), the wireless transmit receive unit (WTRU) comprising: A processor, the processor being configured to: Receive measurement configuration information, the measurement configuration information indicating: a list of cells to be measured, wherein the list of cells includes a serving primary cell (PCell), one or more serving secondary cells (SCells), a candidate PCell, and one or more candidate SCells, a first trigger condition associated with at least one of the serving PCell or the candidate PCell, and a second trigger condition related to at least one of the one or more serving SCells or the one or more candidate SCells; performing measurements of signals associated with one or more cells included in the cell list; and Determining that the first trigger condition and the second trigger condition are satisfied; The processor is further configured to: transmitting a measurement report based on determining that the measurement configuration information is associated with a measurement report, wherein the measurement report comprises a layer 1 (L1) or layer 3 (L3) measurement report; or A conditional handover (CHO) is performed to the candidate PCell based on determining that the measurement configuration information is associated with CHO. 2. The WTRU of claim 1 , wherein the measurement configuration information includes an indication of whether the measurement configuration information is associated with a measurement reporting configuration or a CHO configuration. 3. The WTRU of claim 1 , wherein the processor is configured to: When the signal quality measurement of the candidate PCell exceeds a first signal quality threshold, determining that the first trigger condition is satisfied; and When the signal quality measurement of at least one of the one or more candidate SCells exceeds a second signal quality threshold, it is determined that the second trigger condition is met. 4. The WTRU of claim 1 , wherein the processor is configured to: When the average signal quality of the one or more candidate SCells exceeds a signal quality threshold, it is determined that the second trigger condition is met. 5. The WTRU of claim 1 , wherein the measurement configuration information includes an indication of a signal quality threshold for the one or more candidate SCells; and Wherein the processor is configured to apply the SCell configuration for each of the one or more candidate SCells having a signal quality measurement exceeding the signal quality threshold. 6. A WTRU according to claim 5, wherein the processor is further configured to determine the state of each of the one or more candidate SCells having the signal quality measurement exceeding the signal quality threshold, wherein the state is one of an active state, an inactive state, or a dormant state. 7. The WTRU of claim 1 , wherein the processor is further configured to: determining that the measurement configuration information is associated with a measurement report; and The measurement report is transmitted based on determining that the measurement configuration information is associated with the measurement report. 8. The WTRU of claim 1 , wherein a plurality of the one or more candidate SCells are associated with the same frequency; and Wherein the processor is configured to apply the SCell configuration for the SCell having the highest signal quality measurement of the plurality of SCells associated with the same frequency. 9. The WTRU of claim 1 , wherein the processor is further configured to transmit a CHO complete message when performing the CHO to the candidate PCell. 10. A method for a wireless transmit receive unit (WTRU), the method comprising: Receive measurement configuration information, the measurement configuration information indicating: a list of cells to be measured, wherein the list of cells includes a serving primary cell (PCell), one or more serving secondary cells (SCells), a candidate PCell, and one or more candidate SCells, a first trigger condition associated with at least one of the serving PCell or the candidate PCell, and a second trigger condition related to at least one of the one or more serving SCells or the one or more candidate SCells; performing measurements of signals associated with the cell list; Determining that the first trigger condition and the second trigger condition are satisfied; and A conditional handover (CHO) is performed to the candidate PCell based on determining that the measurement configuration information is associated with CHO. 11. The method of claim 10, wherein the measurement configuration information comprises an indication of whether the measurement configuration information is associated with a measurement reporting configuration or a CHO configuration. 12. The method according to claim 10, further comprising: When the signal quality measurement of the candidate PCell exceeds a first signal quality threshold, determining whether the first trigger condition is met; and When the signal quality measurement of at least one of the one or more candidate SCells exceeds a second signal quality threshold, it is determined whether the second trigger condition is met. 13. The method according to claim 10, further comprising: When the average signal quality of the one or more candidate SCells exceeds a signal quality threshold, it is determined whether the second trigger condition is met. 14. The method according to claim 10, further comprising: The SCell configuration is applied for each of the one or more candidate SCells having a signal quality measurement exceeding a signal quality threshold of the one or more candidate SCells, wherein the measurement configuration information includes an indication of the signal quality threshold. 15. The method according to claim 10, further comprising: A state of each of the one or more candidate SCells having the signal quality measurement exceeding the signal quality threshold is determined, wherein the state is one of an active state, an inactive state, or a dormant state. 16. The method according to claim 10, further comprising: receiving second measurement configuration information; and A measurement report is transmitted based on determining that the second measurement configuration information is associated with a measurement report, wherein the measurement report comprises a layer 1 (L1) or layer 3 (L3) measurement report. 17. The method according to claim 10, further comprising: The SCell configuration is applied for the SCell having the highest signal quality measurement of a plurality of SCells associated with a same frequency, wherein a plurality of the one or more candidate SCells are associated with the same frequency. 18. The method according to claim 10, further comprising: A CHO completion message is transmitted when the CHO to the candidate PCell is performed. 19. A wireless transmit receive unit (WTRU), the wireless transmit receive unit (WTRU) comprising: A processor, the processor being configured to: receiving measurement configuration information indicating a trigger condition associated with a conditional handover (CHO) from a serving primary cell (PCell) to a candidate PCell, wherein the candidate PCell is associated with one or more candidate secondary cells (SCells), and wherein the trigger condition comprises a first trigger condition based on a comparison of a measurement of a signal received from the serving PCell with a measurement of a signal received from the candidate PCell, and a second trigger condition based on a measurement associated with the one or more candidate SCells; determining that the first trigger condition is satisfied based on the comparison of the measurement of the signal received from the serving PCell and the measurement of the signal received from the candidate PCell; Determining that the second trigger condition is satisfied based on measurements associated with the one or more candidate SCells; and The CHO is performed and a CHO completion message is transmitted to the network. 20. The WTRU of claim 18, wherein the second trigger condition is based on an average signal level of the serving PCell and SCell and an average signal level of a target PCell and SCell.