Method of considering SCell conditions during conditional mobility

Abstract

A method for configuring a wireless transmit / receive unit (WTRU) is provided. The method includes receiving one or more of a conditional handover (CHO) or a conditional primary-secondary serving cell (PSCell) add / 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 (SCell) and associated signal level thresholds can be provided, as well as radio resource control (RRC) reconfigurations to be applied when the one or more trigger conditions are satisfied. And when the triggering condition is met, the WTRU can execute the RRC reconfiguration and add the SCell meeting the corresponding threshold value. An indication of the added SCell can be transmitted to the network.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 395,099, filed on August 4, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0003] NR Release 16 introduced the concepts of Conditional Handover (CHO) and Conditional PSCell Addition / Change (CPA / CPC, or collectively referred to as CPAC), with the goal of reducing the likelihood of Radio Link Failure (RLF) and Handover Failure (HOF).

[0004] A conventional LTE / NR handover may be triggered by a measurement report, and nothing prevents the network from transmitting a HO command to a wireless transmit receive unit (WTRU) even in the absence of a 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., RSRP, RSRQ, etc.) of a neighboring cell becomes better than the primary serving cell (PCell) and / or, for example, better than the primary secondary serving cell (PSCell) in the case of dual connectivity (DC). The WTRU may monitor the serving cell and the neighboring cells and may transmit measurement reports when the conditions are met. Upon receiving such a report, the network (e.g., the current serving node / cell) may prepare a HO command (e.g., an RRC reconfiguration message with reconfigurationWithSync) and transmit it to the WTRU. The WTRU may perform the HO, which will result in the WTRU connecting to the target cell. Summary of the invention

[0005] The WTRU may be configured to consider the signal level of the candidate secondary cell (SCell) when performing conditional handover (CHO). In an embodiment, only candidate cells with a signal level above (usually greater than) a specific threshold are added as SCells. In an embodiment, the WTRU may be configured to consider the average signal level of the candidate cells (primary cell (PCell) + SCell, or only SCell) to decide whether to perform CHO. In an embodiment, if the average signal level of all candidate cells is greater than the average value of the current serving cell by a specific threshold, CHO can be performed. In an embodiment, the WTRU may be configured to add only a specific number of SCells that meet a specific threshold when CHO is performed. In an embodiment, the WTRU may be configured to determine the SCell state (e.g., activated, deactivated, dormant) based on the configured threshold and the signal level of the SCell when CHO is performed. In an embodiment, the WTRU may be configured to transmit an indication of the added SCell, SCell state, and SCell measurement results to the network when CHO execution is completed.

[0006] In an embodiment, a method of configuring a WTRU may include receiving a conditional handover (CHO) or conditional primary and secondary serving cell (PSCell) addition / change (CPAC) configuration with one or more trigger conditions from a network. The triggering 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, as well as a radio resource control (RRC) reconfiguration to be applied when one or more trigger conditions are met. The WTRU monitors the trigger conditions for the conditional reconfiguration and executes when the trigger conditions are met. The WTRU may also add an SCell that meets its threshold and then transmit an indication of the added SCell to the network.

[0007] The WTRU may perform a method or be configured to receive measurement configuration information indicating a list of cells to be measured from a network device. 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 associated with at least one of the serving PCell or the candidate PCell. The configuration information may also include a second trigger condition associated with at least one of the one or more serving SCells or one or more candidate SCells. 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 the 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.

[0008] In an embodiment, the measurement configuration information may include a specific indication of whether it is associated with a measurement report configuration or a CHO configuration. The WTRU may also determine that a first trigger condition is satisfied when a signal quality measurement of a candidate PCell exceeds a first signal quality threshold, and the WTRU may also determine that a second trigger condition is satisfied when a signal quality measurement of at least one of the candidate SCells exceeds a second signal quality threshold. The WTRU may determine that a second trigger condition is satisfied when an average signal quality of one or more candidate SCells exceeds a signal quality threshold.

[0009] 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 the SCell configuration for the candidate SCells having a signal quality measurement exceeding the signal quality threshold. In addition, the WTRU may be configured to determine the state of each of the candidate SCells having a signal quality measurement exceeding the 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. Based on the maximum number of SCells that can be configured by the WTRU, the signal quality measurement may also exceed the signal quality threshold. In an embodiment, multiple candidate SCells may be associated with the same frequency. The WTRU then applies the SCell configuration for the SCell with the highest signal quality measurement of multiple SCells associated with the same frequency. The WTRU may transmit a CHO completion message when performing a CHO to a candidate PCell. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0011] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0012] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0013] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0014] Figure 2 An example of a handover scenario in New Radio (NR) is illustrated.

[0015] Figure 3 An example of conditional handover configuration and execution is illustrated.

[0016] Figure 4 An example of layer 1 (L1) / layer 2 (L2) inter-cell mobility operation using carrier aggregation (CA) is illustrated.

[0017] Figure 5 An example of L1 / L2 inter-cell mobility deployed only in certain areas is illustrated.

[0018] Figure 6 An example process performed by a WRTU in response to receiving measurement event configuration information is illustrated. DETAILED DESCRIPTION

[0019] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the 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 multi-carrier (FBMC), etc.

[0020] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but 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 UE 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include a user equipment (WTRU), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0021] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is 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 other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, 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.

[0022] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to send 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 a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific 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. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0023] 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, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0024] More specifically, as noted above, the 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. For example, the 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), which may use Wideband CDMA (WCDMA) to establish the air interface 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).

[0025] 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) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0027] In an embodiment, 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 together implement LTE radio access and NR radio access, for example using the 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 transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0028] 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, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0029] Figure 1AThe base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky 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 picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0030] The RAN 104 / 113 may be in communication with the CN 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, 102d. 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, etc. 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 described in detail in the text and video, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. 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, etc. 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. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0031] 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. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0032] 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 via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0033] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, 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 peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0034] 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 associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC) and state machine, etc. 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 the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0035] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0036] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, 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.

[0037] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0038] 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 (e.g., 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 a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, and a secure digital (SD) memory card, among others. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0039] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the 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 cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0040] The processor 118 may also be coupled to the 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 the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) 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 will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0041] The processor 118 may also be coupled to other peripherals 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 peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device and activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor and / or humidity sensor.

[0042] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0043] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0044] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-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 evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0045] 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, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0046] Figure 1C The illustrated CN 106 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 is depicted as being 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.

[0047] 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 serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0048] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0049] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0050] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 networks and / or wireless networks owned and / or operated by other service providers.

[0051] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communication interface with a communication network.

[0052] In a representative embodiment, the other network 112 may be a WLAN.

[0053] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or out of the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by 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, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a 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 within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0054] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set 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, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0055] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0056] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0057] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above (greater than) a threshold (e.g., to maintain very long battery life).

[0058] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) 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 a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing 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 a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0059] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South 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.

[0060] Figure 1D1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0061] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0062] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0063] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle 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 eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0064] Each of the gNBs 180a, 180b, 180c may be associated with a specific 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 slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0065] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is 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.

[0066] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for: authenticating the user of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of service utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-APro, and / or non-3GPP access technologies, such as WiFi.

[0067] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating 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, etc.

[0068] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring, etc.

[0069] 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. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0070] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with respect to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU 102a-102d, base station 114a-114b, evolved Node 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 device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0071] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation 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 simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0072] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0073] Figure 2 An example handover scenario in New Radio (NR) is depicted. At step 0, the context of the WTRU within the source gNB 204 may be provided by the Access and Mobility Management Function (AMF). The WTRU context may include information about roaming and access restrictions, which is provided at connection establishment or at the last timing advance (TA) update. At step 1, the source gNB 204 configures the WTRU measurement process and the WTRU 202 reports according to the measurement configuration. At step 2, the source gNB 204 may decide to hand over the WTRU 202 based on the received measurements.

[0074] At step 3, the source gNB 204 then issues a handover request message to the target gNB 206, for example, by passing a transparent radio resource control (RRC) container with the necessary information for preparing the handover on the target side. This information may include at least the target cell ID, KgNB, C-RNTI (radio link identifier) ​​of the WTRU 202 in the source gNB 204, radio resource management (RRM) configuration including WTRU inactivity time, 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. In addition, in some examples, this 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. In addition, if WTRU 202 is admitted, the target gNB 206 utilizes L1 / L2 to prepare for the handover and transmits a handover request confirmation to the source gNB 204 at step 5, which handover request confirmation may include a transparent container to be transmitted as an RRC message to WTRU 202 to perform the handover.

[0075] Once the handover request confirmation has been delivered, the handover execution begins so that the WTRU 202 can detach from the old cell and synchronize to the new cell. In step 6, the source gNB 202 triggers the Uu handover by transmitting an RRCReconfiguration message to the WTRU 202, which contains the information required to access the target cell, such as the target cell ID, the new C-RNTI and / or the 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) configurations, common RACH resources and system information of the target cell, etc. In some examples, the buffered data and the new data are delivered from the UPF 210.

[0076] As the detachment begins, in step 7, the source gNB 204 transmits an Early Handover State Transfer Data and SN State Transfer message to the target gNB to convey the uplink PDCP SN receiver state and downlink PDCP SN transmitter state of the DRBs to which PDCP state preservation (e.g., for Radio Link Control (RLC) AM) is applied. User data may be provided to the source gNB 202 and then to the target gNB 206. In step 8, the WTRU 202 synchronizes to the target cell and completes the RRC handover procedure by transmitting an RRCReconfigurationComplete message to the target gNB 206.

[0077] In the handover completion 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 an SN state transfer (step 8b). At step 9, the target gNB 206 transmits a Path Switch Request message to the AMF 208 to trigger the 5GC to switch the DL data path towards the target gNB 206 and establish an NG-C interface instance towards the target gNB 206. In this step 10, the 5GC switches the DL data path towards 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 may then release any U-plane / TNL resources towards the source gNB 202. In step 11, the AMF 208 acknowledges the Path Switch Request message with a Path Switch Request Acknowledge message. Upon receiving the Path Switch Request Ack message from the AMF 208, the target gNB 206 transmits a WTRU Context Release to notify the source gNB 204 of the handover success. 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.

[0078] NR Release 16 introduces the concepts of Conditional Handover (CHO) and Conditional Primary and Secondary Serving Cell (PSCell) Addition / Change (CPA / CPC, or collectively referred to as CPAC), which have the potential to reduce the likelihood of Radio Link Failure (RLF) and Handover Failure (HOF).

[0079] Traditional LTE / NR handovers may typically be triggered by measurement reports, and there is nothing that prevents the network from transmitting a HO command to the WTRU even in the absence of a 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 a neighboring cell becomes better than the primary serving cell (PCell) or, in the case of DC, also better than the PSCell. The WTRU monitors the serving cell and the neighboring cells and may transmit measurement reports when conditions are met. Upon receiving such a report, the network (e.g., the current serving node / cell) may prepare a HO command. The HO command may be an RRC reconfiguration message with reconfigurationWithSync, which may be transmitted to the WTRU, which immediately executes the HO command, resulting in the WTRU connecting to the target cell.

[0080] CHO may be different from a traditional handover. For example, multiple handover targets may be prepared. In addition, the WTRU may not perform CHO immediately. The WTRU may be configured with trigger conditions (such as a set of radio conditions), and if the trigger conditions are met, the WTRU may perform a handover towards one of the targets.

[0081] The CHO command may be transmitted while the radio conditions towards the current serving cell are still good, thereby reducing, among other things, the risk of failure to transmit a measurement report (e.g., when the link quality to the current serving cell drops below (e.g., less than) an acceptable level when the measurement report is triggered in a normal handover) and failure to receive a handover command (e.g., when the link quality to the current serving cell drops below an acceptable level after the WTRU has transmitted a measurement report but before it receives a HO command).

[0082] Figure 3 An example of conditional handover configuration and execution is shown. Figure 3 As contemplated in , the triggering 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 the neighboring cell / potential target node 306, such as the conditions used to trigger measurement reports in traditional LTE / NR. The CHO request from the source node 304 to the potential target node 306 (e.g., from step 1) may result in a CHO request confirmation (e.g., RRCReconfiguration) in step 2.

[0083] In step 3, the WTRU 302 may be configured with CHO with a trigger condition similar to A3 (or A5) and an 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, for example, A5) trigger condition is met, the WTRU may perform the 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 a path switch and / or release the context.

[0084] CHO may help prevent unnecessary re-establishment in the event of a radio link failure. For example, a WTRU may be configured with multiple CHO targets and the WTRU experiences RLF before the triggering condition with any of these targets is met. Conventional operation may result in an RRC re-establishment procedure that may also cause a considerable interruption time of the WTRU's bearers. However, in the case of CHO, if the WTRU terminates a cell for which it has CHO associated with it (i.e., a target cell may have been prepared for it) after detecting an RLF, the WTRU may directly execute the HO command associated with that target cell instead of continuing with the full re-establishment procedure.

[0085] CPC and CPA may be extensions of CHO, but in a DC scenario. In addition, the WTRU may be configured with trigger conditions for PSCell change or addition, and when the trigger conditions are met, it may execute the associated PSCell change or PSCell add command.

[0086] 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 primarily described in the context of measurement objects, reporting configurations, and measurement ID configurations, the concepts may be applied to measurement configurations that include any of the foregoing configurations.

[0087] The measurement object may specify what the WTRU must measure and / or information on how the measurement may be performed. In an embodiment, this information may include, for example, the RAT, frequency, subcarrier spacing, SSB periodicity / offset / duration, reference signals and signal types to be measured, a list of allowed / excluded neighbor cells of the RAT / frequency of interest to be measured, measurement gaps, offsets that may be applied to prioritize / de-prioritize certain cells, etc.

[0088] A WTRU may be configured with multiple measurement objects, and a WTRU may have measurement configurations that may be associated with different frequencies or even different RATs.A WTRU may be configured with up to 64 measurement objects, and each measurement object may be identified by a measurement object ID.

[0089] The reporting configuration may specify what 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 and / or 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., a periodic reporting configuration) or some radio condition based on 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.

[0090] A measurement object may be associated with one or more reporting configurations. The association may be made via a measurement ID. For example, a measurement ID configuration may be a list of measurement IDs, measurement object IDs, and / or reporting configuration IDs. As noted herein, a WTRU may be configured with up to 64 measurement IDs.

[0091] The WTRU may be configured with event-triggered reporting by any of the following, including, but not limited to: event A1, where the serving cell becomes greater than a threshold; event A2, where the serving cell 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 for) a PCell or a 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 an SCell (e.g., only for an SCell, such as for a secondary cell in carrier aggregation (CA)). Events A4 and B1 may be related to neighbor cell measurements (eg, and may not be related to any serving cell).

[0092] In the case of CHO, it is contemplated that the WTRU may perform a HO command instead of transmitting a measurement report when the reporting conditions are met. In the case of CHO, an event-triggered reporting configuration may be defined to include one or more of the following: CondEvent A3, where the neighbor becomes offset greater than SpCell; CondEvent A4, 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.

[0093] The CHO configuration may contain a conditional reconfiguration ID, a conditional reconfiguration trigger condition, and / or an RRC reconfiguration (e.g., HO command) to be performed when the condition is met. The trigger condition may be a reference to 1 or 2 measurement IDs, and if 2 measurement IDs are specified, both measurement IDs typically refer to the same measurement object (e.g., one measID associates a measurement object related to the PCell with an A3 event, and another measID associates the same measurement object with an A5 event). In Release 17, a WTRU may be configured with up to 8 CHO configurations.

[0094] 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 assume states other than the active state. These other states may include a deactivated / inactivated state, which may be a power saving state for the WTRU, where the WTRU has a configured SCell or PSCell of interest but does not perform any active UL / DL transmission / reception via the cell of interest. In the case of a PSCell, the WTRU may perform some processing related to the PSCell, such as radio link monitoring and beam failure detection. Another state for the SCell and PCell may include a dormant state, which may be applicable only to the SCell and may be considered to be an intermediate state between the deactivated state and the active state. The dormant state may be similar to the deactivated state in that the WTRU stops PDCCH monitoring of 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 on the SCell. Therefore, the network can be aware of the current channel status of the SCell, and the SCell in a dormant state (eg, or also referred to as a dormant SCell) can be quickly activated when needed (eg, for a WTRU that may require a larger data rate / capacity).

[0095] In NR Release 17, inter-cell L1 / L2 mobility can manage beams in CA situations without supporting cell changes / additions. In Release 18, one of the envisioned purposes may be to specify mechanisms and procedures for L1 / L2-based inter-cell mobility to reduce mobility delays. In an implementation scheme, mechanisms and procedures for L1 / L2-based inter-cell mobility to reduce mobility delays may be specified. Configuration and maintenance for multiple candidate cells may be specified to allow rapid application of configurations for candidate cells (RAN2, RAN3). A dynamic switching mechanism in candidate serving cells (e.g., including special cells (SpCells) and SCells) for potentially applicable scenarios based on L1 / L2 signaling (RAN2, RAN1) 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 master cell group (MCG) or an SCG. L1 enhancements may be provided for inter-cell beam management, including L1 measurements and reporting and beam indications (RAN1, RAN2). Early RAN2 involvement may be necessary, including further clarification of the possibility of interaction with dynamic switching. Timing advance management (RAN1, RAN2) and CU-DU interface signaling may also be provided to support L1 / L2 mobility ((RAN3) if necessary). FR2 specific enhancements may not be excluded. In addition, the L1 / L2 based inter-cell mobility procedures are applicable to various scenarios, such as standalone deployments where the serving cell changes within a configured grant or cell group (CG), CA and NR-DC cases, intra-DU cases and intra-CU inter-DU cases (applicable to standalone deployments and CA when no new RAN interface is expected), intra-frequency, inter-frequency, FR1, FR2, source cell and target cell synchronous or asynchronous, and excluding inter-CU cases.

[0096] L1 / L2-based mobility initially started in NR Release 17, and inter-cell beam management in Release 17 addresses both intra-DU scenarios and intra-frequency scenarios. In this case, the serving cell remains unchanged (i.e., it is not possible 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, for example, to aggregate multiple CCs in one band. These CCs are typically transmitted with the same analog beam pair (gNB beam and WTRU beam). The WTRU may be configured with TCI states (which may have a considerable number, e.g., 64) for receiving the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH). Each TCI state includes an RS or SSB that the WTRU references in order to set its beam. For Release 17, the SSB may be associated with a non-serving PCI. MAC signaling ("TCI state indication for WTRU-specific PDCCH MAC control element (CE)") activates the TCI state for Coreset / PDCCH. Receipt of PDCCH from non-serving cells may be supported by a MAC CE indicating the 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. The downlink control information (DCI) indicates a specific TCI state among the 8 TCI states. Release 17 also supports "unified TCI states" with a different update mechanism (DCI-based) but without multiple transmit / receive points (TRPs). Release 18 may support unified TCI states with multiple TRPs.

[0097] L1 / L2 inter-cell mobility can be used to improve handover latency, either with a regular L3 handover or conditional on the WTRU first transmitting measurement reports using RRC signaling. In response, the network may provide additional measurement configurations and potential CHO configurations. With CHO, the network provides the configuration for the target cell after the WTRU uses RRC signaling to report that the cell meets the configured radio quality criteria. For conditional handover, in order 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 as well as the measurement criteria that determine when the WTRU can trigger the CHO configuration. Both L3 methods may result in a certain amount of delay due to the transmission of measurement reports and the reception of the target configuration, especially in the case of regular (non-conditional) handover.

[0098] L1 / L2 based inter-cell mobility may allow fast application of configuration for candidate cells, including dynamic switching between SCells and switching of PCells (e.g., switching roles between SCells and PCells), without performing RRC signaling. The inter-CU case is not included in Release 18 as this requires relocation of the PDCP anchor point and has been excluded from the work items. An RRC based approach may be desirable, such as to support inter-CU handovers. L1 / L2 may allow CA operation to be enabled immediately upon serving cell change.

[0099] Figure 4 An example of L1 / L2 inter-cell mobility operation using carrier aggregation (CA) is shown, whereby a candidate cell group may be configured by RRC and dynamic switching of PCells and SCells may be achieved using L1 / L2 signaling.

[0100] As discussed herein, Release 18 does not introduce support for inter-CU handover using L1 / L2 signaling. Therefore, regular or conditional handover may be required to at least cover this case. Regular or conditional handover may be required to support any mobility from any specific L1 / L2 mobility area to another mobility area. Figure 5 As shown, L1 / L2 inter-cell mobility may be deployed only in certain areas. In addition, the network may divide the deployment of the network into multiple L1 / L2 mobility areas for other reasons (such as cell planning) or due to restrictions on the maximum number of cell configurations that can be stored in the WTRU402 at the same time.

[0101] Figure 5 A scenario is shown where there are two gNBs, the first gNB serving cells 1 to 3, and the second gNB serving cells 4 to 8. The WTRU may first be in the first gNB and configured with a CHO configuration towards cell 4 of the second gNB. While in the coverage area of ​​the first gNB, different SCells may be added / removed or activated / deactivated using L1 / L2 signaling. Although not shown in the figure, L1 / L2 may be used to switch from PCell to SCell and vice versa.

[0102] The CHO triggering conditions may be based on events (e.g., condA3 / A5) that are based on the serving PCell and / or target PCell conditions. When the CHO conditions are met and the WTRU hands over to the second gNB, in some examples, it may not be possible to optimally decide on the appropriate set of SCells to be configured for the WTRU (e.g., because the triggering of CHO may not take into account the radio conditions of the candidate SCells). Additionally, if it is desired to utilize L1 / L2 mobility in the candidate gNB, the current mechanism may force the network (e.g., blindly) to configure possible cells (e.g., cell 5 to cell 8) as candidate cells for L1 / L2 mobility candidate cells. In an embodiment, it may be desirable to configure CHO such that the WTRU can not only select the best candidate PCell, but also take into account the conditions of the serving SCell and the candidate SCells.

[0103] The following discussion focuses mainly on the CHO case. However, the implementation scheme may be applicable to the case of CPA or CPC (for example, PSCell conditions instead of PCell conditions, and SCell refers to SCG SCell). In addition, in the following description, it may be assumed that L1 / L2 mobility signaling includes an indication that the SCell is promoted to PCell. The associated configuration / signaling may also be applicable to the case where a non-serving neighboring cell is also promoted to PCell. In addition, in the following discussion, L1 / L2 signaling may refer to MAC CE or DCI. In addition, the term "cell meets the 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" may also be used interchangeably. It should be noted that the implementation scheme may be applicable even without L1 / L2 mobility (for example, an enhancement to traditional CHO operation).

[0104] The WTRU may be configured to perform CHO based on the signal level of one or more candidate SCells (e.g., individually). For example, the WTRU may be configured with a CHO configuration that includes trigger conditions for a particular candidate PCell, associated candidate SCells that are added as additional carriers when the CHO trigger conditions are met, and / or additional signal level thresholds (e.g., RSRP thresholds) for the SCells that the WTRU checks before adding the SCell.

[0105] In an embodiment, a signal level (e.g., RSRP) threshold may be configured for candidate SCells. When performing CHO and applying the CHO configuration when the CHO trigger condition for the PCell is met, the WTRU may check the signal level of the candidate SCells and apply (e.g., only apply) the SCell configuration for those cells with signal levels that meet the configured threshold.

[0106] In an embodiment, different signal level thresholds may be configured for each candidate SCell. For example, different signal levels may be associated with thresholds for a given candidate SCell (e.g., SCell 1 has an RSRQ threshold associated with it, SCell 2 has an RSRP threshold associated with it, etc.).

[0107] Signal level thresholds may be associated with subsets of candidate SCells. In an embodiment, for example, a cell list (e.g., a PCI list) may be associated with a specific threshold. In an embodiment, a specific threshold may be associated with a cell of a given frequency or a given frequency range. As another example, a specific set of cells may have a threshold that may be associated with RSRQ, while other sets of cells may have a threshold associated with RSRP.

[0108] The WTRU may be configured to apply configurations of all candidate SCells that satisfy their corresponding thresholds. In an embodiment, the WTRU may be configured to apply configurations of up to N (eg, where N may be configured by the network or fixed in the 3GPP specification) best candidate SCells that satisfy their corresponding thresholds.

[0109] The WTRU may be configured with different prioritizations of candidate SCells (e.g., based on frequency or other network-specific reasons), and if more than N candidate SCells satisfy their corresponding thresholds, the WTRU may sort these candidate SCells according to their priorities, and may apply the configuration of the first N candidate SCells among these candidate SCells (i.e., if SCellx has a higher priority than SCelly and SCellx still satisfies its corresponding threshold, then candidate SCellx with a lower signal level than SCelly may be ultimately selected).

[0110] The signal levels of the PCell and the candidate SCell may be considered together. In an embodiment, the CHO execution condition may consider both the candidate PCell signal level and the candidate SCell signal level. For example, the triggering condition for CHO to a particular candidate PCell may be considered met if (e.g., only if) both the candidate PCell and one or more candidate SCells meet the configured threshold.

[0111] The CHO execution condition may consider average measurements between more than one candidate cell. For example, the trigger condition may be considered to have been met if one or more of the following apply: (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.

[0112] During averaging, PCell and / or candidate PCell may carry a greater weight than SCell and candidate SCell, for example, assuming there are 3 serving SCells and 4 candidate SCells. The average value of the serving cell may be calculated as:

[0113] f*rsrp_PCell+(1-f)*(rsrp_SCell1+rsrp_SCell2+rsrp_SCell3) / 3, and for the candidate cell, it can be calculated as:

[0114] f*rsrp_PCell+(1-f)*(rsrp_candidate_SCell1

[0115] +rsrp_candidate_SCell2+rsrp_candidate_SCell3

[0116] +rsrp_candidate_SCell4) / 4.

[0117] The scaling / weighting factors 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.

[0118] In an embodiment, averaging may be performed on SCells (e.g., only on SCells), while candidate PCells may be compared individually (e.g., using 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, candidate PCells may be compared to an absolute threshold, and candidate SCells may be averaged and compared to the absolute threshold. If the candidate PCell is above a particular threshold and the average signal level of all candidate SCells is above a particular threshold, and / or if the candidate PCell is above a particular threshold and the average signal level of the N best candidate SCells is above a particular threshold, then the triggering conditions for CHO may be considered met.

[0119] In some examples, the candidate PCell can be compared to an absolute threshold, and the candidate SCells can be averaged and compared to the average of the current SCell, where the trigger conditions for CHO are considered to be met 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.

[0120] In an implementation scheme, the candidate PCell may be compared to the current PCell, the candidate SCells may be averaged and compared to an absolute threshold and the average of the current SCell. 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, then the triggering conditions for CHO may be considered met.

[0121] In an implementation scheme, the candidate PCell is compared with the current PCell, and the candidate SCells are averaged and compared with the average of the current SCell. For example, if the candidate PCell is larger than the current PCell by a certain threshold and the average signal level of the N best candidate SCells is larger 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 larger than the average signal level of the N best current serving cells by a certain threshold, then the triggering conditions for CHO may be considered to be met.

[0122] In an embodiment, the same measurement quantity (e.g., RSRP or RSRQ) and associated threshold value 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 value may be configured for all candidate SCells, but different measurement quantities and associated threshold values ​​may be configured for candidate PCells. Candidate SCells may be associated with different threshold values ​​or even different measurement quantities (e.g., RSRP or RSRQ). This may be different for each candidate SCell, or may be the same for a particular set of candidate SCells.

[0123] The SCell to be added may be selected based on a relative comparison of the signal levels of the candidate SCells. For example, the WTRU may be configured with a CHO configuration that contains trigger conditions regarding a specific target PCell and the associated SCell to be added as an additional carrier. The maximum number of SCells that may be added when the CHO trigger condition is met may be further defined. For example, the WTRU may perform the following when the CHO trigger condition is met (based on the target PCell): (a) identify the best candidate SCell in each frequency, (b) sort these candidate SCells according to signal quality, and / or (c) take the top m SCells (e.g., where m is equal to the maximum number of configured SCells) and apply their corresponding SCell configurations. Signal level thresholds may be specified (e.g., in addition to the maximum number of SCells). For example, when configured in this manner, the WTRU may perform the following when a CHO trigger condition is met (e.g., based on the target PCell): (a) identify the best SCell candidates in each frequency that also meet the configured threshold, (b) sort these candidate SCells based on signal quality, and / or (c) take the first m SCells (e.g., where m is equal to the maximum number of configured SCells) and apply the corresponding SCell configuration.

[0124] 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.

[0125] The WTRU may determine which SCell(s) to activate based on any combination of factors. For example, when the WTRU decides to apply a given SCell configuration when the above-mentioned CHO trigger condition and SCell addition condition are met, the WTRU may add an SCell in an activated state, a deactivated state, or a dormant state. In an embodiment, the WTRU may be configured to determine the SCell state (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 higher than a first threshold are added as activated SCells, candidate SCells having a signal level between the first threshold and the second threshold are added as dormant SCells, and candidates having a signal level lower than / less than the second threshold are added as deactivated SCells. In an embodiment, the WTRU may be configured with a maximum number of SCells to be added to an activated state (e.g., n_activated), a deactivated state (e.g., n_deactivated), or / and a dormant state (e.g., n_dormant), and the WTRU may add the best n_activated candidate cell as an activated SCell, add the next n_dormant best cell as a dormant SCell, and add the next n_deactivated best cell as a deactivated SCell.

[0126] The conditions of the threshold and the maximum number of cells may be combined. In an embodiment, an additional threshold may be specified, and if the signal level of the SCell is below the associated threshold, the SCell may not be added when CHO is performed. Furthermore, in an embodiment, as in the embodiments in the previous section, the threshold may be common for all frequencies / SCells, or may be different for each frequency / SCell.

[0127] The WTRU may be configured to determine a candidate set list for L1 / L2 mobility. For example, the WTRU may be configured to release the SCell configuration of a candidate cell that does not meet the SCell addition condition (e.g., for the above-mentioned embodiments). The WTRU may be configured to store the SCell configuration of the candidate cell that does not meet the SCell addition condition (e.g., according to any of the above-mentioned embodiments) and regard them as part of the L1 / L2 mobility set. For example, the WTRU may anticipate future L1 / L2 mobility indications that may indicate that a cell within the mobility set becomes an SCell or even a PCell. In an embodiment, a combination of the above two is possible. In an embodiment, the WTRU may be configured to add a specific SCell (e.g., the signal level is above / greater than a specific threshold, the first n cells, etc.), keep the configuration of a specific cell as part of the L1 / L2 mobility set list (e.g., the signal level is between two thresholds, etc.), and release the configuration of a specific cell (e.g., the signal level is below a specific threshold).

[0128] The WTRU may be configured with multiple L1 / L2 mobility candidate set lists that can be applied when performing CHO. When performing CHO, the candidate set to be applied may depend on the results of the CHO evaluation. For example, in the case where the target PCell meets the conditional trigger condition, the set of SCells or L1 / L2 candidate cells to be configured may depend on the results of the SCell / target candidate cell measurements. In an implementation scheme, if the target candidate cell 1 is larger than the candidate cell 4, the L1 / L2 candidate set A (e.g., cells 1, 2, 3) may be applied, and if the target candidate cell 4 is larger than the candidate cell 1, the L1 / L2 candidate set B (e.g., cells 4, 5, 6) may be applied. The comparison result of cell 1 and cell 4 is an indicator of the area of ​​the PCell that the WTRU has entered, and therefore these candidate cells are most likely to be used. In an implementation scheme, the WTRU may enter the PCell in the northwest, then cells 1, 2, 3 are the most likely and cell 1 has a larger measurement result than cell 4, while the WTRU enters the PCell in the northeast, then cells 4, 5, 6 are the most likely and cell 4 has a larger measurement result than cell 1.

[0129] The WTRU may transmit a response signal. For example, the WTRU may notify the network of a decision regarding a candidate SCell, which the WTRU has applied according to any of the above embodiments. In addition, the WTRU may provide the network with one or more of the following: (a) SCells that have been added (e.g., their configuration has been applied), (b) candidate SCells that have not yet been added, (c) the status of SCells that have been added (e.g., activated, deactivated, dormant), (d) candidate SCells that have been released, (e) candidate SCells that have not yet been added but remain part of the L1 / L2 mobility set, and / or (f) measurement results of candidate / added / released SCells. Other information may be provided in addition to the above or separately. The content of the response may be based on whether the configuration information is associated with a measurement report or with a CHO. For example, as noted above, the report configuration may specify what the WTRU is to report. If the report configuration specifies association with a measurement report, the WTRU may transmit a measurement report. If the report configuration is associated with a CHO, the WTRU may perform a CHO to a candidate PCell.

[0130] An indication about the added SCell may be included in the RRC Reconfiguration Complete message.The information about the SCell may be transmitted in a separate message, such as in another RRC message (eg, by the WTRU autonomously or upon request from the network) or in a MAC CE.

[0131] Referring to the above discussion, in an embodiment, the WTRU may receive a CHO configuration that includes one or more of the following: (i) candidate PCells 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) an RRC reconfiguration (e.g., a HO command) to be applied when the CHO condition is met. The WTRU may further monitor the CHO trigger condition. When the CHO trigger condition is met, the WTRU may perform CHO, but only add the SCells that meet their thresholds, and then transmit to the network an indication of 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.).

[0132] The WTRU may receive a CHO configuration including one or more of: (a) a set of candidate PCells and SCells as CHO triggering 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., a HO command) to be applied when the CHO conditions are met. The WTRU may monitor the CHO triggering conditions and perform CHO and transmit information to the network, such as measurements of the candidate / added SCells (e.g., in an RRC reconfiguration complete message, in a separate message, etc.) when the CHO triggering conditions are met (e.g., the average signal level of all candidate cells is above a configured threshold, the average signal level of all candidate cells is greater than the average signal level of all current serving cells by more than a configured threshold, etc.).

[0133] The WTRU may receive a CHO configuration that includes one or more of the following: (i) candidate PCells 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 and a maximum number of SCells (m) that may be added, and / or (iii) an RRC reconfiguration (e.g., a HO command) to be applied when the CHO condition is met. The WTRU may monitor the CHO trigger condition. When the CHO trigger condition is met, the WTRU may perform CHO (e.g., only add up to the first m SCells that meet the SCell threshold). The WTRU may transmit an indication to the network (e.g., in an RRC reconfiguration complete message, in a separate message, etc.) about which SCells are added and / or additional information (such as measurements of the candidate / added SCells).

[0134] The WTRU may receive a CHO configuration including one or more of the following: (i) candidate PCells 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, thresh2), and / or (iii) an RRC reconfiguration (e.g., a HO command) to be applied when the CHO condition is met. The WTRU may continue to monitor the CHO trigger condition. When the CHO trigger condition is met, the WTRU may perform CHO while setting the state of the SCell according to the following: (a) if the signal level of the SCell is below thresh1, deactivate the SCell; (b) if the signal level of the SCell is between thresh1 and thresh2, set the SCell to sleep and / or (c) if the signal level of the SCell is above thresh2, activate the SCell. The WTRU then transmits an indication of the state of the SCell and additional information (such as measurements of the candidate / added SCell) to the network (e.g., in an RRC reconfiguration complete message, in a separate message, etc.).

[0135] Figure 6 An example process 600 performed by a WTRU in response to receiving measurement event configuration information is illustrated. At 602, the WTRU may be configured to receive measurement configuration information from a network device indicating a list of cells to be measured. 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 associated with at least one of the serving PCell or the candidate PCell. The configuration information may also include a second trigger condition associated with at least one of the one or more serving SCells or the one or more candidate SCells.

[0136] At 604, the WTRU measures the cell configured to be measured. The radio conditions to be measured for the source PCell, the target PCell, one or more source SCells, and one or more target SCells may include, for example, one or more of absolute / relative thresholds for individual source / target PCells and source / target SCells, and absolute / relative thresholds for the average of the source PCell and source SCell and the target PCell and target SCell. Other signal quality conditions may also be included.

[0137] At 606, the WTRU monitors a signal associated with the cell list to determine whether a first trigger condition and a 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 the cell configured to be measured at 608. If the trigger condition is met at 608, the WTRU determines at 610 whether the measurement configuration is associated with conditional handover (CHO). If the measurement at 610 is not associated with CHO, the WTRU transmits a measurement report, such as a layer 1 (L1) or layer 3 (L3) measurement report, at 616. The report may include measurement results of the serving PCell / SCell, the target PCell / SCell, or others. If the measurement event at 610 is associated with CHO, the WTRU performs CHO to the candidate PCell at 612. For example, at 614, the WTRU transmits an indication indicating CHO to the network. The message transmitted by the WTRU may be a HO completion message.

[0138] The measurement configuration information may include a specific indication of whether it is associated with a measurement report configuration or a CHO configuration. The WTRU may also determine that a first trigger condition is satisfied when a signal quality measurement of a candidate PCell exceeds a first signal quality threshold, and the WTRU may also determine that a second trigger condition is satisfied when a signal quality measurement of at least one of the candidate SCells exceeds a second signal quality threshold. The WTRU may determine that a second trigger condition is satisfied when an average signal quality of one or more candidate SCells exceeds a signal quality threshold.

[0139] 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 the SCell configuration for the candidate SCells having a signal quality measurement that exceeds the signal quality threshold. The WTRU may be configured to determine the state of each of the candidate SCells having a signal quality measurement that exceeds the signal quality threshold. The state of the candidate SCell may be an active state, an inactive state, or a dormant state. Based on the maximum number of SCells that can be configured by the WTRU, the signal quality measurement may also exceed the signal quality threshold. In an embodiment, multiple candidate SCells may be associated with the same frequency. The WTRU then applies the SCell configuration for the SCell with the highest signal quality measurement of multiple SCells associated with the same frequency. In addition, the WTRU may transmit a CHO completion message when performing a CHO to a candidate PCell.

[0140] 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 measurements of signals received from the serving PCell with measurements of signals received from the candidate PCell. The trigger condition may also include measurements associated with one or more candidate SCells. The WTRU determines whether the first trigger condition is met based on a comparison of measurements of signals received from the serving PCell with measurements of signals received from the candidate PCell. The WTRU also determines whether the 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 completion message to the network. In an embodiment, the second trigger condition may be based on the average signal level of the serving PCell and the SCell and the average signal level of the target PCell and the SCell.

Claims

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; as well as 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; as well as 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; as well as 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; as well as 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.

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