Wireless transmit / receive unit and implementation method thereof

Abstract

The invention provides a wireless transmit / receive unit and a method for implementing the same. The wireless transmit / receive unit is configured to operate with a primary cell group (MCG) and a secondary cell group (SCG), the method comprising: performing uplink transmission in the MCG when the SCG is deactivated; determining that data associated with the SCG is available for transmission; and sending a message to a network device associated with the MCG, wherein the message indicates that the data associated with the SCG is available for transmission.

Description

[0001] This divisional application is a divisional application with a filing date of September 29, 2020, application number 202080075547.1, and invention name “Conditional Mobility with Multiple Connections”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 908,876 filed on October 1, 2019, U.S. Provisional Patent Application No. 62 / 930,891 filed on November 5, 2019, U.S. Provisional Patent Application No. 62 / 972,842 filed on February 11, 2020, and U.S. Provisional Patent Application No. 63 / 061,225 filed on August 5, 2020, the disclosures of which are incorporated herein by reference in their entirety. Background Art

[0004] Mobile communications are evolving and have entered the fifth generation - 5G. A wireless transmit receive unit (WTRU) may be configured with multiple connectivity. For example, a WTRU may be configured to communicate with two network nodes that may be connected via a backhaul. The network nodes may provide network access to the WTRU using the same radio access technology (RAT) or using different RATs. The WTRU may transmit messages to or receive messages from a network node. The WTRU and the network node may determine each other's condition and / or status via messaging. Summary of the invention

[0005] Systems, methods and tools for handling mobility and multi-connection related tasks associated with a wireless transmit receive unit (WTRU) are described herein. A WTRU as described herein may receive a radio resource control (RRC) message from a network entity, wherein the RRC message may indicate a conditional reconfiguration to be applied by the WTRU and a condition (e.g., a measurement condition) for applying the conditional reconfiguration. The conditional reconfiguration may be associated with a primary secondary cell (PSCell) change, a PSCell addition, a secondary cell group (SCG) change, an SCG addition, etc. The RRC message may indicate a plurality of candidate PSCells associated with the conditional reconfiguration. In response to receiving the RRC message, the WTRU may transmit a first message to the network entity and indicate in the first message that the WTRU has received the RRC message. The WTRU may monitor the conditions for applying the conditional reconfiguration and may determine that the conditions for applying the conditional reconfiguration are met. The WTRU may transmit a second message to the network entity (e.g., based on determining that the conditions for applying the conditional reconfiguration are met), wherein the second message may indicate that the conditions for applying the conditional reconfiguration are met. The WTRU may apply the conditional reconfiguration. In some scenarios, the WTRU may determine that the application of the conditional reconfiguration has resulted in a failure. In response to such a failure, the WTRU may transmit a third message to the network entity, where the third message may indicate the failure to the network entity.

[0006] The network entity described herein may be associated with a master cell group (MCG) of the WTRU, and the WTRU may be configured to transmit at least one of the first message, the second message, or the third message in the MCG. The WTRU may receive a conditional handover command from the network entity while the conditional reconfiguration is still pending, and the WTRU may prioritize execution of the conditional handover command over execution of the conditional reconfiguration. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented.

[0008] Figure 1B It is shown that according to one embodiment, Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) for use within a communication system is shown.

[0009] Figure 1C is a diagram according to one embodiment which can be Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) for use within a communication system is shown.

[0010] Figure 1D is a diagram according to one embodiment which can be Figure 1AA system diagram of another exemplary RAN and another exemplary CN used within the communication system shown.

[0011] Figure 2 is a diagram showing an exemplary timing for beam failure reporting, beam failure configuration, and beam failure recovery.

[0012] Figure 3 is a diagram showing an example of applying SCG configuration based on conditions.

[0013] Figure 4 is a diagram showing an example of applying SCG configuration based on detection of radio link failure.

[0014] Figure 5 is a diagram illustrating an example of an enhanced recovery action.

[0015] Figure 6 is a diagram illustrating an example of monitoring of multiple conditional reconfigurations. DETAILED DESCRIPTION

[0016] Figure 1A 1 is a schematic diagram illustrating an exemplary 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, filter bank multi-carrier (FBMC), etc.

[0017] like Figure 1AAs 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 WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), 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.

[0018] 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. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0019] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. 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, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the 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 transmit and / or receive signals in a desired spatial direction.

[0020] 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).

[0021] 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, SC-FDMA, etc. 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).

[0022] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0023] In one 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).

[0024] In one 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 implement LTE radio access and NR radio access together, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0025] 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), GSM Enhanced Data Rates for Evolution (EDGE), GSM EDGE (GERAN), etc.

[0026] Figure 1AThe base station 114b in the 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 a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. 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 one 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.

[0027] 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, delay 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 specification, 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. 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.

[0028] 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 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.

[0029] 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.

[0030] Figure 1B is a system diagram illustrating an exemplary 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 subcombination of the foregoing elements while remaining consistent with an embodiment.

[0031] 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), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functions that enable 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.

[0032] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0033] Although the transmit / receive element 122 is Figure 1B 1 as a single element, 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.

[0034] 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. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0035] The processor 118 of the WTRU 102 may be coupled to 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) and may receive user input data therefrom. 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, a secure digital (SD) memory card, and the like. 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).

[0036] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0037] 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.

[0038] 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, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0039] 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 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 for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, 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 UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0040] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As described 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.

[0041] 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.

[0042] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0043] 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 a CN operator.

[0044] 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, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. 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.

[0045] 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 inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0046] 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.

[0047] 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 serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0048] Although the WTRU Figures 1A to 1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0049] In a representative embodiment, the other network 112 may be a WLAN.

[0050] 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 carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent by the AP, for example, wherein the source STA may send traffic to the AP, and the AP may deliver the traffic to the destination 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 sent between the source and destination STAs (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 (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

[0051] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may transmit a beacon 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.

[0052] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0053] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel 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 the 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 data can be transmitted by transmitting STA. At the receiver of the receiving STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be sent to the medium access control (MAC).

[0054] 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 a threshold (e.g., to maintain very long battery life).

[0055] 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) 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 the 1MHz operating mode) is transmitting to the AP, the entire available frequency band may be considered busy even if most of the frequency bands remain idle and may be available.

[0056] 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.

[0057] Figure 1D 1 is a system diagram showing the RAN 113 and the CN 115 according to one 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.

[0058] 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 to communicate 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 transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0059] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. 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 transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or continuously varying absolute time lengths).

[0060] 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 also 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 or connect with the gNBs 180a, 180b, 180c while also communicating or connecting with other RANs, such as the evolved Node-Bs 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 evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-Bs 160a, 160b, 160c may serve as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0061] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, 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.

[0062] 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 a CN operator.

[0063] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c via the N2 interface in the RAN 113 and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of 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 services used 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, 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-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0064] 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 UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0065] 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, providing mobility anchoring, etc.

[0066] 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 serves 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 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 an N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0067] 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 reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to emulate 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.

[0068] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, the one or more simulation devices may perform one or more 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. The 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.

[0069] The one or more simulation devices may 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 may be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which may include one or more antennas) may be used by the simulation device to transmit and / or receive data.

[0070] When referred to herein, a network may include one or more gNBs, one or more transmit / receive points (TRPs), and / or one or more nodes associated with a radio access network. When referred to herein, MR-DC (Multi-Radio Dual Connectivity) may indicate dual connectivity to an E-UTRA node and an NR node, or dual connectivity to two NR nodes.

[0071] The WTRU may be configured with multiple connections, such as dual connections. For example, the WTRU may be configured to utilize resources provided by two nodes (e.g., two network nodes). The two nodes may be connected, for example, via a non-ideal backhaul. The nodes may provide network access to the WTRU using the same RAT or using different RATs. In an example, a first network node may act as a master node (MN), the MN may be configured to control resources associated with one or more cells associated with the same master cell group (MCG), and a second network node may act as a secondary node (SN), the SN may be configured to control resources associated with one or more cells associated with the same secondary cell group (SCG). The MN and the SN may be connected via a network interface. At least the MN may be connected to the core network. The exemplary implementations described herein may be applicable to various use cases, including cases where the WTRU may be configured with more than one secondary cell group (e.g., possibly controlled by more than one secondary node). In the example case of dual connectivity, the WTRU may be configured to implement multiple medium access controls or MACs (e.g., via corresponding MAC entities). One or more MACs (e.g., MAC entities) may be associated with an MCG, and one or more MACs (e.g., MAC entities) may be associated with an SCG. The WTRU may be configured to receive and process radio resource control (RRC) messages, such as RRC reconfiguration messages, via the MCG. The RRC messages (e.g., RRC reconfiguration messages) may be associated with (e.g., include information for) an SCG addition, an SCG change or modification, and / or an SCG release.

[0072] The delay associated with the initial setup and activation of the SCG may impact the performance of multi-connectivity. There may be a delay between a first time instance when the WTRU determines that additional radio resources are needed (e.g., for high throughput data transmission) and a second time instance when the WTRU is ready to transmit on the SCG. The delay may be associated with (e.g., caused by) aspects including signaling delays on the Uu interface (e.g., buffer status, measurement reports, etc.), signaling delays on the Xn interface (e.g., coordination between the master node and the secondary node), etc.

[0073] Interruptions in the mobility process may impact the performance of multi-connectivity. In an example, mobility robustness may be supported, at least when the SCG bearer is terminated in the SN, for example, because a failed SCG change may interrupt ongoing data transmission. Due to inter-node coordination between the MN and the target SN, the delay from the WTRU sending a measurement report to the WTRU receiving an RRCReconfiguration may be uncertain. This may result in an SCG change being too late or too early. The SCG may be deployed in higher frequencies (e.g., in frequency range 2 (FR2), such as between 24.25 GHz and 52.6 GHz), where the cell size may be small and beamforming may result in fragile links.

[0074] The mobility interactions between different connection legs of a multi-connected WTRU may be affected. The WTRU may be configured to perform network controlled mobility operations of the MCG and conditional mobility operations of the SCG. The WTRU may be configured to perform network controlled mobility operations of the SCG and conditional mobility operations of the MCG. The WTRU may be configured to perform conditional mobility operations for both the MCG and the SCG. The behavior of the WTRU may be affected by the impact (e.g., success / failure) of concurrent mobility procedures performed on different layers in a multi-connected scenario (e.g., may be inconsistent due to the above reasons).

[0075] The WTRU may be configured to perform mobility-related operations in a multi-connection scenario. The description of conditional handover (CHO) provided herein may be at least partially applicable to conditional reconfiguration, and vice versa. Similarly, the description related to conditional PS cell addition and / or change (CPAC) may be at least partially applicable to conditional PS cell change (CPC), and vice versa. An example of CPAC may include performing a reconfiguration associated with a secondary cell group if a pre-configured execution condition or trigger is met. Such execution conditions and / or triggers may be pre-configured, for example, by a network entity via high-level signaling. The examples provided herein regarding a master node (MN) may be at least partially applicable to a master cell group (MCG), and vice versa. The examples provided herein regarding a secondary node (SN) may be at least partially applicable to a secondary cell group (SCG), and vice versa.

[0076] The WTRU may apply a configuration associated with a secondary cell group based on a condition (e.g., based on a pre-configured condition). The WTRU may be configured to perform a cell group configuration or reconfiguration on the secondary cell group if the pre-configured condition is met. The secondary cell group may correspond to (e.g., use) the same RAT as the primary cell group, or the second cell group may use a RAT different from the RAT used by the primary cell group (e.g., the second cell group may be a multi-radio secondary cell group). The secondary cell group configuration or reconfiguration may be synchronized (e.g., including a preamble transmission that may be configured using a configuration parameter such as reconfigurationWithSync). The cell group configuration or reconfiguration may be signaled as part of an RRC reconfiguration message.

[0077] The WTRU may be configured with (e.g., the WTRU may receive) one or more multi-connectivity conditional reconfigurations, for example, where at least one reconfiguration may be associated with an MCG and at least one reconfiguration may be associated with an SCG. The WTRU may be configured with multiple conditional reconfigurations, where a first subset of the conditional reconfigurations may be associated with a primary cell group, and a second subset of (e.g., the remaining) conditional reconfigurations may be associated with a secondary cell group. The WTRU may be configured with multiple conditional reconfigurations, where the multiple conditional reconfigurations may correspond to a primary cell group and a secondary cell group. If a trigger condition (e.g., a trigger condition associated with the conditional reconfiguration) is met, the WTRU may apply the MCG reconfiguration and / or the SCG reconfiguration. The WTRU may be configured with multiple conditional reconfigurations, where one or more conditional reconfigurations associated with the secondary cell group may be linked to a conditional reconfiguration of the primary cell group. If the first trigger condition is met, the WTRU may apply the conditional reconfiguration associated with the primary cell group. If the second trigger condition is met, the WTRU may apply the conditional reconfiguration associated with the secondary cell group linked to the currently activated primary cell group.

[0078] Configuration aspects associated with conditional secondary cell group configuration or reconfiguration may be described herein. The WTRU may be configured to apply the SCG configuration if a pre-configured condition is met. The SCG configuration may include one or more of the following: a configuration of a special cell (e.g., spCellConfig), which may include PSCell configuration information; a configuration to perform reconfiguration with synchronization; a radio bearer configuration, which may include packet data convergence protocol (PDCP) configuration information, radio link control (RLC) configuration information and / or logical channel configuration information; a MAC configuration (e.g., configuration information of a MAC entity associated with a cell group); or a configuration associated with zero or more SCells to be added, modified and / or released.

[0079] The WTRU may be configured with links (e.g., mappings, associations, relationships, etc.) between SCG configurations and trigger conditions. One SCG configuration may be associated with multiple trigger conditions. Multiple SCG configurations may be associated with a single trigger condition. The WTRU may be configured to determine which one or more conditional SCG configurations may be applicable to a given MCG configuration. The WTRU may use such determinations to perform monitoring associated with one or more SCG configurations. For example, the WTRU may be configured to monitor trigger conditions associated with those SCG configurations that are linked to the currently active MCG configuration. The WTRU may be configured with links between MCG candidates and SCG candidates. In an example, the WTRU may be configured with links between candidates for conditional handover (CHO) (e.g., on an MCG) and candidates for conditional SCG reconfiguration. For example, such links may be used to exploit certain network (NW) preferences and / or restrictions on the combination of MNs and SNs to which the WTRU can be connected. The behavior of the WTRU may be affected by links as described herein. Links may, for example, imply or control the behavior of the WTRU with respect to CHO and / or PSCell changes.

[0080] As a result of performing CHO, the WTRU may trigger a conditional SCG reconfiguration. In an example, the WTRU may be configured to trigger a conditional SCG reconfiguration at or after CHO. Conditional SCG reconfiguration may be triggered due to a lack of link between the CHO target and the current PSCell or SCG configuration. In an example, the WTRU may be configured with an SCG configuration corresponding to a CHO candidate (e.g., a candidate master node). The WTRU may trigger a PSCell configuration based on the triggering of CHO. The WTRU may be configured with multiple conditions (e.g., as described herein) for performing SCG reconfiguration after CHO. For example, if one or more conditions are met, the WTRU may perform a PSCell change to the link configuration, and if any conditions are not met, the WTRU may release or suspend the SCG configuration, or maintain the current configuration.

[0081] The WTRU may trigger CHO as a result of a conditional SCG reconfiguration. For example, the WTRU may be configured to trigger CHO when or after a triggering condition PSCell changes. One or more aspects of the above examples (e.g., for performing a conditional SCG reconfiguration as a result of CHO execution) may be applicable to performing CHO as a result of a conditional SCG reconfiguration. For example, the WTRU may be configured with multiple conditions for performing CHO after an SCG reconfiguration (e.g., as described herein). If one or more conditions are met, the WTRU may perform CHO, and if any conditions are not met, the WTRU may release or suspend CHO.

[0082] The WTRU may decide to suspend, release, or keep active the currently active SCG configuration after the CHO based on certain conditions related to the link. For example, the WTRU may perform a CHO on a target and may decide to activate, suspend, or release the current SCG configuration based on the link of the SCG configuration with the target. For example, if the WTRU is configured with a link between the CHO and the current SCG, it may continue to operate on the SCG. If the WTRU is not configured with a link between the CHO and the current SCG, the WTRU may suspend the SCG, release the SCG, activate a different SCG, or perform a reconfiguration on a different SCG.

[0083] The WTRU may suspend or release certain bearers (e.g., data radio bearers (DRBs) and / or signaling radio bearers (SRBs)) based on one or more conditions related to the link. For example, if there is no link between the CHO candidate and the current SCG or between the PSCell candidate and the current PCell, the WTRU may suspend or release the DRB during a CHO or conditional PSCell change. If there is a link as described herein, the WTRU may be configured with a list of bearers to be suspended and / or released. If there is no link as described herein, the WTRU may be configured with a list of bearers to be suspended and / or released.

[0084] The WTRU may perform a radio bearer reconfiguration (e.g., from a split bearer to an MCG / SCG bearer) based on certain conditions related to the linkage described herein. For example, the WTRU may perform a radio bearer reconfiguration when no linkage exists. For example, if no linkage exists between the CHO target and the current PSCell, the WTRU may reconfigure one or more split bearers (e.g., all split bearers) as MCG bearers or SCG bearers.

[0085] The WTRU may decide to reconfigure portions of the SCG configuration after CHO based on certain conditions related to linkage as described herein. For example, the WTRU may be provided with a reconfiguration of the SCG. The WTRU may apply such reconfiguration under the condition that (e.g., only under the condition that) the CHO target is not linked to the currently active SCG configuration. If there is a linkage (e.g., between the CHO target and the currently active SCG configuration), the WTRU may not apply such reconfiguration.

[0086] The WTRU may consider a subset of configured conditional PSCell candidates (e.g., only a subset of configured conditional PSCell candidates) that the WTRU is allowed to access to perform a conditional PSCell change based on a given active PCell or MCG configuration. For example, after selecting a CHO candidate, the WTRU may select a subset of corresponding PSCell candidates (e.g., only a subset of corresponding PSCell candidates) that the WTRU is allowed to use in case a PSCell reconfiguration is triggered together with or as a result of CHO.

[0087] The WTRU may consider a subset of configured conditional handover (HO) candidates (e.g., PCell) that the WTRU is allowed to access to perform conditional handover based on a given active PSCell or SCG configuration. This behavior of the WTRU may also apply when a conditional PSCell configuration triggers CHO (e.g., after or during a conditional PSCell configuration).

[0088] The WTRU may apply a deviation in the triggering condition for conditional HO to the PCell, for example, depending on the presence of a link between the current PSCell and the CHO candidate (for example, the WTRU may prioritize candidates with a link over candidates without a link). For example, the WTRU may be configured with triggering conditions for conditional HO candidates based on measurements. The WTRU may also be configured with a deviation in such measurements or with different measurements depending on whether there is a link between the CHO candidate and the current PSCell. The WTRU may apply a deviation in the triggering condition for a conditional PSCell change based on the presence of a link between the current PCell and the conditional PSCell candidate. This behavior of the WTRU may also be applied in the case of a conditional PSCell configuration. The WTRU may decide to select one or more candidates using priority based on the presence of a link between the current PCell / PSCell and the conditional PCell / PSCell candidate in question (for example, if there are multiple candidates and a CHO or conditional PSCell change is triggered).

[0089] The WTRU may receive signaling and / or identification of a link, for example, from a higher layer. The WTRU may receive explicit signaling of such a link during MCG and / or SCG conditional HO execution. Such explicit signaling may be in one or more of the following forms. If CHO is performed on a candidate (e.g., for each candidate), the WTRU may receive a list of allowed or linked PSCells and / or applicable SCG configurations for each PCell CHO candidate. If conditional SCG reconfiguration is performed, the WTRU may receive, for example, a list of allowed or linked PCells and / or applicable MCG configurations for a PSCell candidate (e.g., for each PSCell candidate). The WTRU may receive an identifier with a cell configuration (e.g., with each cell configuration). For example, if the MCG and SCG have the same identifier or a related identifier, the WTRU may assume a link between the MCG and the SCG. The WTRU may receive a table of linked PCells and / or PSCells (e.g., a table such as a cell ID), for example, via dedicated configuration information or via a SIB. The WTRU may be configured with multiple conditions that trigger reconfiguration. For example, if there is a link between the candidate cell associated with the reconfiguration and the serving cell (e.g., the serving cell associated with the MCG and / or SCG), the first condition may be applied, and if there is no link between the candidate cell associated with the reconfiguration and the serving cell (e.g., the serving cell associated with the MCG and / or SCG), the second condition may be applied.

[0090] The WTRU may implicitly determine a link based on one or more of the following. The WTRU may implicitly determine such a link based on a relationship between parameters associated with each configuration. The WTRU may consider a cell to be linked if the cells have the same cell security parameters or there is a relationship between the security parameters of the cells. In an example, the WTRU may consider a cell to be linked if there is a direct relationship in the cell ID. In an example, the WTRU may consider a cell to be linked if the cells have the same configuration for a particular bearer (e.g., a separate bearer). For example, if the SCG and MCG are included (e.g., configured) in the same RRC reconfiguration message, the WTRU may consider linking the SCG to the MCG. For example, the link may be explicit or implicit by including a masterCellGroup configuration and a secondaryCellGroup configuration in the RRCReconfiguration message.

[0091] The link between the MCG candidate and the SCG candidate may depend on a specific trigger condition. The link between the MCG candidate and the SCG candidate may depend on a specific trigger for CHO and / or conditional PSCell change. The WTRU may be configured with a first set of one or more triggers based on the assumption that a first link or a set of links exists, and the WTRU may be configured with a second set (e.g., separate) of one or more triggers based on the assumption that a second link or a set of links exists. In an example, the WTRU may be configured with conditional PSCell candidates 1 and 2. Conditional PSCell candidate 1 may have a link with the current PCell, and conditional PSCell candidate 2 may not have a link with the current PCell. Such a link may apply to triggers (e.g., only triggers) of data arrival on the SCG bearer, but not to triggers of SCG cell quality. For example, if the WTRU triggers a conditional PSCell change due to data arrival while residing on the current PCell, the WTRU may prioritize the PSCell change or limit it to PSCell candidate 1 (e.g., instead of PSCell candidate 2). If the WTRU triggers a conditional PSCell change due to SCG cell quality, the WTRU may allow the PSCell to be changed to either PSCell Candidate 1 or PSCell Candidate 2 without giving priority to either candidate.

[0092] The WTRU may receive a general cell group configuration that may be used as an MCG or SCG configuration. The WTRU may receive one or more conditions associated with applying a CG configuration as an MCG configuration or an SCG configuration. In an example, the WTRU may be configured with a first set of one or more conditions, whereby the general cell group configuration may be applied as an MCG configuration, and may be configured with a second set (e.g., which may be different from the first set) of one or more conditions, whereby the general cell group configuration may be applied as an SCG configuration. In an example, the WTRU may receive a general cell group configuration that may be used for conditional PSCell addition and / or conditional PSCell change. For example, if the conditions for conditional PSCell addition and / or conditional PSCell change are met and the WTRU does not have an active SCG configuration, the WTRU may perform a conditional PSCell addition. If the conditions for conditional PSCell addition and / or conditional PSCell change are met and the WTRU has an active SCG configuration, the WTRU may perform a conditional PSCell change. If the general cell group is configured for conditional PSCell addition and conditional PSCell change, the examples described herein may apply.

[0093] If the WTRU is also configured with other non-generic CG candidates, the WTRU may identify the generic CG. For example, in addition to the MCG-specific or SCG-specific configurations, the WTRU may be configured with one or more generic CG configurations. The WTRU may identify the generic CG configuration based on explicit signaling (e.g., based on the corresponding identity or identifier included in the generic CG configuration, or based on the use of a separate information element (IE) for the generic CG configuration). The WTRU may identify the generic configuration based on a complete (e.g., not an incremental) configuration that has been provided for the generic CG configuration.

[0094] The CG configuration may be provided as incremental signaling (e.g., in addition to other signaling). The WTRU may receive a generic CG configuration as incremental signaling and may apply the incremental signaling to derive the resulting MCG or SCG configuration. In the case where separate incremental configurations are provided for the MCG and SCG, one or more of the following items may be applied. The CG configuration may be provided in separate sections, for example, an incremental configuration associated with the MCG and an incremental configuration associated with the SCG. In an example, if the WTRU decides to apply a conditional CG configuration to the SCG, the WTRU may apply the incremental configuration associated with the SCG to the current SCG configuration (e.g., while ignoring the incremental configuration associated with the MCG). In an example, the WTRU may apply both the MCG configuration and the SCG incremental configuration, regardless of which CG is changed.

[0095] In the case where the CG configuration is provided as incremental signaling to the MCG or SCG, one or more of the following may apply. The CG configuration may be provided as an incremental configuration to a currently configured CG (e.g., MCG or SCG). If the CG configuration is provided with respect to the MCG and if CHO is performed on the PCell, the WTRU may apply the incremental configuration to its current MCG configuration (e.g., to derive the MCG configuration after the CHO). If the CG configuration is provided relative to the MCG and if a conditional PSCell change is performed, the WTRU may apply the incremental configuration to its current MCG configuration (e.g., to derive the SCG configuration after the conditional PSCell change). If the CG configuration is provided as an incremental configuration relative to the SCG and if a conditional PSCell change is performed, the WTRU may apply the incremental configuration to its current SCG configuration (e.g., to derive the SCG configuration after the conditional PSCell change). The WTRU may receive signaling (e.g., in the candidate configuration itself) regarding whether the incremental configuration is applied to the MCG or the SCG.

[0096] The WTRU may be configured with one or more trigger conditions for auxiliary cell group configuration or reconfiguration. The WTRU may be configured to apply a reconfiguration associated with an auxiliary cell group when one or a combination of the trigger conditions described herein are met. For example, the WTRU may be configured to apply SCG reconfiguration when measurement-based conditions are met. The measurement-based conditions may correspond to cell quality measurements such as RSRP, RSRQ, or SINR. The measurement-based conditions may be configured, for example, as measurement events (e.g., Ax, Bx, etc.) with one or more appropriate thresholds. If the measurement-based conditions and one or more of the following trigger conditions are met, the WTRU may apply SCG reconfiguration.

[0097] The trigger condition may be associated with the user plane state. For example, if the measurement-based condition and the user plane-based condition are met, the WTRU may be configured to apply the SCG configuration. For example, the user plane condition may be met if one or more of the following occurs. The user plane condition may be met based on data associated with a pre-configured logical channel (LCH) or logical channel group (LCG) becoming available for transmission (e.g., such LCH / LCG may correspond to an SCG bearer or a separated bearer). The user plane condition may be met if the buffer status of one or more bearers reaches a threshold (e.g., the threshold may correspond to a data separation threshold, or may be derived from a data separation threshold for multiple bearers). For example, if the WTRU determines that the amount of pending PDCP and RLC data on all separated bearers is above a threshold, the user plane condition may be met, which may trigger the application of the SCG configuration or the activation of the SCG. The user plane condition may be met if the delay associated with the data transmission becomes above a pre-configured threshold. The user plane condition may be met if the delay associated with the scheduling request becomes above a pre-configured threshold. The user plane condition may be met if the number of RLC retransmissions becomes greater than a pre-configured threshold. The user plane condition may be met if one or more conditions of the buffer status related to a time aspect are met. For example, whether the user plane condition may be met may be determined based on the amount of time that the buffer status (e.g., for one bearer or a subset of bearers) exceeds a threshold (e.g., the trigger may be the amount of time that the threshold is exceeded). The user plane condition may be met if the amount of increase in the buffer status (e.g., per unit of time) is greater than a threshold. The user plane condition may be met if a buffer status report (BSR) is triggered or transmitted (e.g., the triggering of a BSR may be associated with the presence of another condition, such as the buffer status of one or more separate bearers being above a threshold).

[0098] In an example, the WTRU may be configured with two thresholds for a split bearer (e.g., for each split bearer). For example, if the PDCP and RLC data pending for (e.g., any) bearer is above a first threshold, the WTRU may activate or apply an SCG configuration. With the SCG configuration activated or applied, the WTRU may continue to submit data to (e.g., only to) the MCG branch of the split bearer. For example, if the PDCP / RLC data pending for the bearer is above a second threshold, the WTRU may submit data to the SCG branch of the split bearer. The WTRU may follow similar deactivation rules.

[0099] The triggering condition may be associated with SRB3.The WTRU may be configured to apply the SCG configuration in the event that the WTRU cannot comply with the RRCReconfiguration message received over SRB3, for example, if the PSCell associated with the stored SCG configuration may satisfy measurement and / or suitability criteria.

[0100] The trigger condition may be associated with an SCG failure. The WTRU may be configured to apply the SCG configuration when an SCG failure is detected. The SCG configuration may correspond to an SN change. An SCG failure may be detected if one or more of the following conditions are met. An SCG failure may be detected in response to detecting a radio link failure with the SCG. An SCG failure may be detected in response to detecting a reconfiguration with a synchronization failure with the SCG. An SCG failure may be detected in response to detecting an SCG configuration failure. An SCG failure may be detected in response to receiving an integrity check failure indication regarding SRB3 from an SCG lower layer.

[0101] The trigger condition may be associated with a beam failure (e.g., for a PSCell of an SCG). The WTRU may be configured to apply the SCG configuration and / or activate a dormant SCG (e.g., as described herein) in the event of a beam failure detected on a PSCell. The WTRU may continue to perform beam monitoring on a cell in the event of a suspended and / or dormant SCG or a dormant SCell (e.g., a cell operating on a secondary frequency to provide additional radio resources to a WTRU configured with CA). In the event of a beam failure, the WTRU may initiate a beam failure recovery procedure and / or activate a dormant SCG, PSCell and / or SCell (e.g., in order to receive a random access channel (RACH) response on a physical downlink control channel (PDCCH) for a beam failure recovery procedure).

[0102] The trigger condition may be associated with the MCG radio link state. The WTRU may be configured to apply the SCG configuration based on the radio link state associated with the MCG. For example, the WTRU may be configured to apply the SCG configuration in the event of an RLF detected in the MCG. In an example, the WTRU may be configured to perform an RRC implementation based on a stored SCG in the presence of an MCG RLF. One or more of the following may apply. For the case of an MCG RLF, if the WTRU has stored a configuration for the SCG and the PSCell associated with the SCG meets the applicability criteria, and if SRB3 or a separate SRB1 is configured for the SCG, the WTRU may apply the stored SCG configuration and / or transmit an MCG failure message to the SCG (e.g., indicating the cause of the MCG failure and a trigger for applying an SCG configuration such as an MCG RLF). For the case of an MCG RLF, the WTRU may initiate a re-establishment. As part of the re-establishment, the WTRU may perform cell selection. If the selected cell is the same as the PSCell associated with the SCG configuration, the WTRU may apply the stored SCG configuration and / or transmit an MCG failure message to the SCG, for example, to indicate the cause of the MCG failure and a trigger for applying the SCG configuration such as MCG RLF. For the case of MCG RLF, if the WTRU is configured with a generic cell group configuration, the WTRU may promote the cell group configuration to an MCG configuration and may perform a conditional handover to the promoted MCG configuration.

[0103] A trigger condition may be associated with the execution of a conditional reconfiguration of an MCG. The WTRU may be configured to apply the SCG configuration if a conditional reconfiguration associated with the MCG is successfully executed. For example, if one or more additional trigger conditions described herein are met, the WTRU may be configured to perform a conditional SCG configuration after the conditional MCG configuration. The WTRU may be configured to release the SCG configuration if a conditional reconfiguration is applied to an MCG and the current SCG configuration is not linked to such an MCG.

[0104] There may be interaction (e.g., information exchange) between the monitoring process for conditional MCG reconfiguration and the monitoring process for conditional SCG reconfiguration. The WTRU may be configured to simultaneously monitor trigger conditions associated with conditional SCG reconfiguration and trigger conditions associated with conditional MCG reconfiguration. The WTRU may be configured to start monitoring one or more trigger conditions associated with one or more SCG reconfigurations, where these SCG reconfigurations may be linked to MCG configurations that may be active or may satisfy the trigger conditions.

[0105] If the trigger conditions for MCG (re)configuration and / or SCG (re)configuration are met (for example, simultaneously), the WTRU may be configured to prioritize MCG reconfiguration. After MCG reconfiguration, if the stored SCG is linked to the serving MCG, the WTRU may apply the SCG reconfiguration; if the stored SCG is not linked to the serving MCG, the WTRU may release the SCG configuration. If the trigger conditions for MCG and SCG (re)configuration are met (for example, simultaneously), the WTRU may be configured with rules to determine which (re)configuration takes priority. For example, the priority setting rules may be based on the relative cell qualities of the MCG and SCG.

[0106] If a trigger condition associated with an MCG is met while a conditional SCG reconfiguration is in progress, the WTRU may be configured with the following behavior. The WTRU may be configured to release the SCG reconfiguration and trigger an MCG reconfiguration. This behavior may be limited to situations where the SCG reconfiguration is not linked to an MCG reconfiguration. The WTRU may be configured to continue with the MCG and SCG reconfiguration. The WTRU may be configured to indicate the SCG reconfiguration to the MCG.

[0107] If a trigger condition associated with an SCG is met while a conditional MCG reconfiguration is in progress, the WTRU may be configured with the following behavior. The WTRU may be configured to defer SCG reconfiguration, for example, until the MCG reconfiguration is complete or until the MCG reconfiguration fails. The WTRU may indicate to the MCG that an SCG reconfiguration is triggered (for example, in the event that the MCG reconfiguration is successful). The WTRU may report an MCG failure to the SCG (for example, in the event that the MCG fails).

[0108] The WTRU may be configured to handle the SCG state based on conditions. For example, the WTRU may be configured to activate (or deactivate) the SCG (e.g., SCG configuration) based on one or more pre-configured triggers. For example, the WTRU may be configured with one or more SCG configurations that may be dormant, and the WTRU may be further configured with one or more configurations or conditions for activating the SCG configuration (e.g., changing the SCG configuration from a dormant state to an activated state) or suspending the SCG configuration (e.g., changing the SCG configuration from an activated state to a dormant state). The dormant state may be characterized by one or more conditions such as conditions associated with a dormant SCell, where the WTRU may perform channel quality indicator (CQI) / radio resource management (RRM) measurements but may not decode the PDCCH. In an example, putting the SCG configuration in a dormant state may mean storing the SCG configuration at the WTRU but not applying it. The WTRU may apply any trigger described herein (e.g., regarding conditional PSCell changes or additions) to activate the SCG. The WTRU may operate with multiple activated SCGs if the triggers for activating these SCGs are met but the triggers for deactivating the SCGs are not met.

[0109] Given multiple SCG configurations, the WTRU may select an SCG for activation. For example, the WTRU may be configured with multiple dormant SCG configurations, and each SCG configuration may include a PSCell and zero or more SCells. The WTRU may select an SCG for activation based on pre-configured criteria. The WTRU may select the SCG with the best PSCell or SCell (e.g., based on RRM measurements). The WTRU may select the SCG with the best PSCell or SCell based on channel state information (CSI) measurements. The WTRU may select an SCG configured with dedicated RACH resources. The WTRU may select an SCG with the maximum number of beams above a threshold. The WTRU may select an SCG with the maximum number of SCells that meet the minimum RSRP, RSRQ, SINR and / or CSI thresholds. The WTRU may select the last active SCG.

[0110] The WTRU may be configured to indicate SCG activation to the network based on the activation of the SCG. The WTRU may transmit a scheduling request to the selected SCG (e.g., if valid scheduling request (SR) resources are configured and / or if UL time alignment is valid). The WTRU may provide an activation indication using any of the mechanisms described herein for indicating an acceptable SCG.

[0111] The WTRU may provide an indication to a dormant SCG, for example, based on an action on the MCG. The WTRU may be configured to perform one or more actions on a dormant SCG based on one or more triggers discussed herein (e.g., before or as part of activating the dormant SCG). These actions may be performed in a predefined order. The actions may include, for example, one or more of the following items. The action may include transmitting an SR to the SCG. The action may include transmitting a RACH message (e.g., a RACH preamble) to the SCG. These actions may include transmitting a CSI reference signal (CSI-RS) report and / or beam measurement to the SCG. These actions may include initiating the transmission of an SRS. These actions may include initiating a beam management process on the SCG. These actions may include changing beam management behavior or configuration with the SCG (e.g., changing from a wide beam to a narrow beam, changing the number of beams monitored / reported, etc.). These actions may include initiating PDCCH monitoring on the SCG. For example, the WTRU may start normal PDCCH monitoring after the transmission. The WTRU may perform PDCCH monitoring for a response and, for example, if the response is positive (eg, indicating SCG activation), may continue such monitoring after receiving the response.

[0112] The activation of the SCG may be signaled by the network (e.g., by the MCG via RRC signaling or a MAC control element (CE)). The activation of the SCG may be characterized at the WTRU, for example, by active PDCCH monitoring on the SCG. The WTRU may (e.g., prior to such activation) be configured with a trigger to initiate an action (e.g., one or more actions described herein) prior to receiving an activation message.

[0113] The WTRU may be configured with a dedicated RACH configuration and / or a SR configuration to send an indication to the SCG. The WTRU may be configured with a dedicated RACH configuration and / or a dedicated SR configuration to perform access to a dormant SCG. The WTRU may perform a RACH procedure or send an SR to a dormant SCG based on one or more of the following items. The WTRU may perform a RACH procedure or send an SR to a dormant SCG based on a timing advance timer (TAT) associated with an MCG and / or SCG (for example, if the TAT times out at the SCG, the WTRU may perform a RACH). The WTRU may perform a RACH procedure or send an SR to a dormant SCG based on the WTRU's configuration regarding random access and / or scheduling requests. For example, if the WTRU is not configured with SR resources, the WTRU may perform a RACH procedure, or if the WTRU is configured with dedicated RACH resources, the WTRU may perform a RACH procedure. When referred to herein, performing a RACH or RACH procedure may include transmitting and / or receiving random access related messages, such as a random access preamble, a random access request, a random access response, and the like.

[0114] For example, if the amount of PDCP or RLC data at one or more separated bearers (e.g., at all separated bearers) exceeds a threshold, the WTRU may trigger a BSR to the MCG and trigger a random access and / or scheduling request to the SCG. For example, if the WTRU triggers a BSR transmission (e.g., to the MCG), the WTRU may initiate a SR or RACH request to transmit to the SCG. For example, if the BSR is triggered, the triggering of the SR or RACH to the SCG may be conditional on the available data on one or more separated bearers (e.g., all separated bearers). If the available data at the WTRU on one or more separated bearers (e.g., on all separated bearers) exceeds a threshold (e.g., at the time of the BSR), the WTRU may transmit a SR or RACH request. The WTRU may be configured with a BSR trigger associated with a trigger involving data arrival.

[0115] The WTRU may receive an indication from the network (e.g., from the MCG) to start the process to the SCG. The indication may be included in, for example, a downlink control information (DCI) message, a MAC CE, or an RRC message. The WTRU may initiate an SR or RACH process to the SCG in response to receiving such a message. The WTUR may initiate a process to the SCG with or without transmitting an RRC message to the SCG. For example, the WTRU may initiate a RACH process to the SCG without transmitting an RRC reconfiguration-related message to the SCG. For example, the WTRU may perform a beam failure recovery process based on a trigger. The WTRU may initiate a beam management process based on a trigger. The WTRU may perform a sequence of one or more actions described herein in any order based on the triggers described herein. For example, the WTRU may (e.g., first) transmit a RACH request and (e.g., after the RACH request is transmitted) start monitoring the CSI-RS, start reporting the CSI-RS, and / or change aspects of CSI-RS monitoring and / or reporting.

[0116] The WTRU may initiate CSI-RS measurements and report to the SCG based on a trigger (e.g., one or more of the triggers described herein). The WTRU may implicitly provide an indication to the SCG, for example, by reporting CSI-RS measurements. The WTRU may maintain one or more behaviors associated with sending an indication or message to the SCG (e.g., CSI-RS measurements and / or reporting), for example, for a period of time or until an activation command is received (e.g., by the MCG or SCG). The CSI-RS measurement / reporting configuration may be specific to a time period between the trigger and the activation command, which may be referred to as an SCG warm-up time period. For example, the WTRU may remain in the SCG warm-up for a limited period of time before resuming the WTRU process associated with the SCG sleep state. For example, the WTRU may start a timer based on a trigger of an indication to the SCG. For example, if the WTRU receives an activation command, the WTRU may change the SCG to an activated state and perform processes associated with the activated state (e.g., normal connection mode processes). The WTRU may stop processes associated with the SCG warm-up time period and may perform processes associated with the SCG sleep state, for example, if the timer expires.

[0117] Beam management may be provided for dormant SCGs. The WTRU may select beams on which the WTRU may perform beam management for one or more dormant SCGs. The WTRU may be configured to perform beam management for a dormant SCG. The WTRU may selectively perform beam management on a subset of SCGs (e.g., if multiple SCGs are configured). The WTRU may be configured to perform beam management (e.g., for at least N SCGs and / or for at least M SCells). In an example, the WTRU may be configured to perform beam management on, for example, the first K PCells and SCells for which the reference signal received power (RSRP) and / or reference signal received quality (RSRQ) and / or signal to interference plus noise ratio (SINR) is above a threshold. The values ​​of N, M, and K may be pre-configured.

[0118] The WTRU may be configured to activate an SCG if a beam failure is detected for at least one SCell within the SCG. The WTRU may then perform a beam failure recovery procedure defined for the SCG. The WTRU may enter a dormant state for the SCG (e.g., based on a successful beam failure recovery). The WTRU may activate a second dormant SCG (e.g., based on a beam recovery failure in a first dormant SCG). If the beam quality associated with the second SCG is above a threshold, the WTRU may activate the second dormant SCG. The WTRU may select an SCG for activation based on pre-configured criteria as described herein. If beam failure recovery in a dormant SCG fails, the WTRU may report such failure to the MCG, for example, using an SCG failure indication procedure. The WTRU may delay (e.g., may perform at a later time) beam failure indication and / or beam failure recovery for a dormant SCG.

[0119] A WTRU performing beam management for a dormant SCG that triggers a beam failure may perform a beam failure indication and / or report to the network, for example, followed by a beam failure recovery process. The indication and / or recovery process may be delayed to a later time or until a trigger condition is met. The WTRU may maintain a beam failure state (e.g., a beam failure may remain pending) and corresponding information until a future trigger. The WTRU may take action on the beam failure (e.g., provide a beam failure indication and / or perform beam failure recovery), for example, based on a future trigger (e.g., when a future trigger occurs or after a future trigger occurs). The triggers described herein may include one or more of the following. The trigger may be the WTRU receiving an SCG activation message or command from the network. The trigger may be the WTRU deciding (e.g., based on the trigger described herein) to autonomously activate the SCG. The trigger may be the WTRU performing a state transition (e.g., "connected" to "inactive" or vice versa). The trigger may be (e.g., any) trigger associated with data arriving at the WTRU, such as data arriving at a bearer, where the bearer may be configured to trigger such an action (e.g., an SCG bearer or a split bearer), or where the bearer may have a specific characteristic associated with latency or similar QoS characteristics (e.g., a bearer associated with a logical channel priority (LCP) limit). The trigger may be the current buffer status at the WTRU, such as the buffer status associated with one or more bearers being above or below a threshold (e.g., ul-dataSplitThreshold). The trigger may include the expiration of a timer. The trigger may include a mobility event at the MCG and / or SCG (e.g., HO, conditional HO, SCG change, or conditional SCG change). The trigger may be to trigger a measurement report based on other measurement-related triggers associated with the MCG and / or SCG. For example, the WTRU may report a pending beam failure indication based on a measurement event related to cell quality in the MCG and / or SCG configured at the WTRU, or the WTRU may report a beam failure on a dormant SCG as part of an RRM-triggered measurement report associated with the event. The trigger may be the WTRU receiving a reconfiguration from the network (e.g., the WTRU receiving a new beam failure recovery configuration). The trigger may be based on measurements of candidate or failed beams (e.g., if one or more candidate beams are measured above a threshold after a beam failure declaration, the WTRU may trigger a beam failure recovery action).

[0120] The WTRU may be configured with one or more conditions that make a beam failure pending. The WTRU may be configured with one or more conditions for delaying beam failure recovery. If one or more conditions associated with delaying beam failure recovery are not met, the WTRU may initiate beam failure recovery (e.g., immediately or shortly after the beam failure), which may include activating a dormant SCG. For example, the WTRU may delay beam failure recovery if at least one of the following conditions is met. The WTRU may delay beam failure recovery based on the type or amount of data available for transmission at the WTRU. The WTRU may delay beam failure recovery based on network configuration. For example, the WTRU may be configured to delay beam failure recovery if the data waiting to be transmitted at the WTRU is associated with a specific LCH or a specific radio bearer. For example, the WTRU may be configured with a set of LCHs for which the WTRU should perform beam failure recovery (e.g., immediately after the beam failure) if data is available for transmission via the bearer. For example, the WTRU may be configured to delay beam failure recovery if the amount of data available for transmission at the WTRU for a subset of radio bearers is below a threshold. As another example, configuration information may be provided to the WTRU (e.g., if the SCG is suspended) indicating when the WTRU should delay a beam failure recovery procedure and / or when the WTRU should perform beam failure recovery without delay (e.g., immediately after a beam failure). Such configuration information may be provided explicitly (e.g., via higher layer signaling) or determined implicitly, such as RS-based configuration if the SCG is dormant and / or beam recovery resource-based configuration (e.g., the configuration may indicate whether the WTRU is configured with beam recovery resources when the SCG is suspended or not suspended, the configuration may indicate corresponding beam recovery resources used by the WTRU when the SCG is suspended and not suspended, etc.).

[0121] The WTRU may report beam failure events in an SCG to the MCG. For example, the WTRU may report beam failure events detected on a dormant SCG to the MCG. The beam failure indication or report provided by the WTRU may include one or more of the following items. The beam failure indication or report may include a report of a beam failure event (e.g., a failure type). The beam failure indication or report may include a report of a beam index or an identification of a failed beam. The beam failure indication or report may include an identification of a specific SCG configuration in which the beam failure occurred (e.g., if the WTRU has multiple stored or dormant SCG configurations). The beam failure indication or report may include measurements of the failed beam, all candidate beams, or a subset of candidate beams (e.g., the N best candidates). The beam failure indication or report may include, for example, one or more of an RRC message (e.g., an SCGFailureIndication message or an equivalent RRC message), a MAC CE, a physical uplink control channel (PUCCH) transmission, an SR transmission, or similar uplink control information (UCI) transmission, and / or a random access preamble transmission.

[0122] The WTRU may receive a configuration (e.g., a new configuration) for a pending beam failure event. The WTRU may receive a configuration (e.g., a new configuration) for beam recovery (e.g., RACH resources and / or candidate beams) after a beam failure indication. The WTRU may receive the configuration from the MN, for example, via an RRC message, a MAC CE, and / or a DCI. The WTRU may receive the configuration after the transmission of a beam failure indication. The WTRU may receive the configuration based on one or more of the triggers discussed herein (e.g., independent of the transmission of the failure indication). For example, if beam failure recovery is triggered, the WTRU may apply the configuration for beam failure recovery (e.g., based on the reception of the configuration). For example, the WTRU may store the received RACH configuration for beam failure recovery and apply the configuration when a beam failure recovery for a pending beam failure is triggered. The WTRU may maintain the application of the most recently received configuration for beam failure recovery.

[0123] For example, based on whether the WTRU receives a new configuration associated with a beam failure in response to the WTRU sending a beam failure indication, the WTRU may decide whether to perform a beam failure recovery action in response to detecting a beam failure (e.g., immediately thereafter) or to delay the beam failure recovery action (e.g., until a later time, such as until a dormant SCG is activated). In one example, if the WTRU does not receive a configuration in response to sending a beam failure report or indication, the WTRU may delay beam failure recovery (e.g., until a future trigger occurs as discussed herein).

[0124] When beam failure recovery is pending on a dormant SCG, the WTRU may have the following behavior. For example, the WTRU may detect a beam failure on a dormant SCG and leave the beam failure pending until a trigger (e.g., one or more triggers indicated herein) occurs. When beam failure recovery is pending on a dormant SCG, the WTRU may perform one or more of the following. The WTRU may stop (e.g., all) beam measurements on (e.g., all) beams of the dormant SCG until a later time (e.g., until a beam failure recovery action or a beam failure recovery trigger is triggered). For example, the WTRU may stop (e.g., all) beam measurements on (e.g., all) beams of the dormant SCG until the SCG is activated. The WTRU may start beam measurements after an activation process or during an activation process. Beam measurements may be facilitated by transmitting RS signals at the time of activation (e.g., by the network). The WTRU may initiate a beam recovery process after performing initial measurements after activation or during activation. The WTRU may continue to perform beam measurements on the failed beam and / or candidate beams after a beam failure and while beam failure recovery is pending. The WTRU may perform beam measurements on the failed beam and / or one or more candidate beams with reduced frequency, strength, or measurement period. For example, the WTRU may perform measurements based on a new RS periodicity determined for performing beam measurements, where the RS periodicity may be configured by the network prior to beam failure or after a beam failure indication to the network.

[0125] For example, if the beam improves, the WTRU may cancel a pending beam failure recovery. For example, if the failed beam measurement improves while the beam failure remains pending, the WTRU may cancel a pending beam failure recovery. For example, if a trigger occurs (e.g., a later activation), the WTRU may avoid performing the beam failure recovery procedure. The WTRU that cancels the pending beam failure recovery may provide an indication of the cancellation to the network. The cancellation message may be similar to the original message indicating the pending beam failure recovery.

[0126] The time at which the WTRU reports a beam failure, receives a configuration associated with a beam failure, or recovers from a beam failure may vary based on multiple factors. For example, the WTRU may report a beam failure at or around the time that the beam failure occurs (e.g., immediately after detecting the beam failure). The WTRU may receive a configuration associated with the beam failure after the report, and the WTRU may begin beam failure recovery upon activation. The WTRU may report a beam failure to the network (e.g., at or around the time that the failure occurs), receive a beam failure configuration, such as a new beam failure configuration (e.g., a new beam failure configuration may provide dedicated RACH resources), at or around the time of the beam failure report, and perform beam failure recovery actions after activation of the SCG where the beam failure occurred.

[0127] The WTRU may report a beam failure at or around the time the failure occurs (e.g., immediately after the failure), receive a configuration associated with the beam failure when the SCG is activated, and initiate beam failure recovery when activated. For example, the WTRU may report a beam failure to the network at or around the time the failure occurs (e.g., immediately after the failure), receive a beam failure configuration with activation, such as a new beam failure configuration (e.g., the new beam failure configuration may provide dedicated RACH resources), and perform beam failure recovery actions according to the received configuration after activating the SCG.

[0128] The WTRU may report beam failure upon activation of the SCG, receive RACH configuration upon activation, and perform beam failure recovery upon activation. For example, the WTRU may detect beam failure but delay reporting and recovery of beam failure until activation of the SCG. The WTRU may report beam failure indications during activation and may receive corresponding configurations for beam failure recovery. The WTRU may perform beam failure recovery for the SCG, for example, after activation and / or after receiving configurations.

[0129] The WTRU may decide not to report a beam failure and then receive a RACH configuration upon activation of the SCG and perform beam failure recovery upon activation. For example, the WTRU may detect a beam failure and perform recovery actions upon activation of the SCG. The WTRU may receive a RACH configuration upon activation (e.g., as part of the signaling of the activation process). The WTRU may perform beam failure recovery for the SCG based on the configuration received at or after the activation signaling.

[0130] The WTRU may not report beam failure or receive RACH configuration and still perform beam failure recovery when the SCG is activated (e.g., with the original or existing RACH configuration). For example, the WTRU may perform recovery (e.g., without reporting recovery) at or after SCG activation, for example, by utilizing a stored RACH configuration. Such a stored RACH configuration may have been received before the beam failure (e.g., if the SCG was put into a dormant state or while the SCG was in a dormant state).

[0131] The WTRU may report a beam failure at or around the time the failure occurs (e.g., immediately after the beam failure), periodically receive a RACH configuration after the failure (e.g., immediately after the failure), and perform beam failure recovery when the SCG is activated. For example, the WTRU may report a beam failure to the MCG at or around the time the failure occurs (e.g., immediately after the beam failure). While a beam failure on the SCG is pending, the WTRU may continue to report measurements to the network periodically (e.g., based on a configured period). The WTRU may update its RACH configuration, for example, as part of a periodic reporting process. The WTRU may receive a configuration while a beam failure is pending. The WTRU may perform beam failure recovery with the last stored configuration when activated (e.g., when or after activating the SCG).

[0132] Figure 2 An example timing of beam failure reporting, configuration, and recovery is shown. Figure 2 In the exemplary scenario shown, the WTRU may report a beam failure at or around the time the beam failure occurs (e.g., immediately after the beam failure), receive configuration when the SCG is activated, and recover from the beam failure when activated. Figure 2 The numbers shown in the figure may be used as an example to show the order in which the operations occur, but in other examples, the order of occurrence or the interactions and / or the participants in the interactions shown in the figure may be different. Figure 2 As shown in the example in, the WTRU may perform one or more of the following. The WTRU may receive an SCG suspension message (e.g., an RRC message) from the MN. The WTRU may suspend the SCG and may continue to perform beam measurements on one or more SCGSCells while the SCG is suspended. A beam failure may be detected at the WTRU on a cell associated with the SCG (e.g., at a subsequent time). The WTRU may transmit a beam failure indication message to the MN. The MN may decide (e.g., at a subsequent time) to activate the failed SCG and may send an SCG activation RRC message (e.g., including beam failure recovery resources) to the WTRU. The WTRU may perform a beam failure recovery procedure (e.g., a RACH procedure) on the SCG (e.g., using resources provided in the SCG activation RRC message).

[0133] The WTRU may be configured to handle MCG failures during an SCG dormant state. For example, the WTRU may detect an MCG failure when at least one SCG is in a dormant state. In this case, the WTRU may not declare a radio link failure (RLF), for example, the RLF may not be declared immediately. The WTRU may be configured to activate a dormant SCG, and in the event of a successful activation, the WTRU may transmit an MCG failure report to the SCG. The MCG failure report may be transmitted during the process of indicating SCG activation to the network, or the MCG failure report may be transmitted after (e.g., immediately following) the process of SCG activation.

[0134] The WTRU may be configured to deactivate an SCG based on one or more pre-configured triggers. The WTRU may apply one or more triggers described herein (e.g., as described with respect to conditional PSCell changes) to the case of deactivating an SCG. For example, a trigger applicable to changing from one SCG to another SCG may be applicable to deactivating an SCG when a separate SCG is activated.

[0135] The WTRU may be configured to handle conditional SCG reconfiguration failures. There may be trigger conditions associated with conditional SCG reconfiguration failures. For example, if a previous conditional SCG reconfiguration failed, the WTRU may be triggered to apply a conditional SCG configuration or reconfiguration. The WTRU may be configured with multiple conditional SCG configurations, and if the conditional SCG reconfiguration fails for the first SCG, the WTRU may attempt to apply the conditional reconfiguration to a second SCG. In an example, the WTRU may be configured to report the failure of a conditional SCG reconfiguration to the MCG. For example, if all conditional SCG reconfigurations fail, if n (e.g., n>=1) conditional SCG reconfigurations fail, or if no conditional SCG reconfiguration satisfies the configured trigger conditions for the SCG reconfiguration, this may be accomplished via an SCG failure information message.

[0136] The WTRU may receive an indication or configuration of an acceptable SCG. The WTRU may be configured to determine (e.g., based on measurements) the acceptability of a stored or received SCG configuration. For example, the WTRU may determine the acceptability of an SCG configuration based on measurements of any or all cells associated with the SCG (e.g., RSRP / RSRQ measurements of cells above a threshold). The WTRU may determine the acceptability of an SCG or SCG configuration based on PSCell quality above a threshold.

[0137] The WTRU may determine the acceptability of the SCG or SCG configuration based on a timer associated with the SCG timeout. Such timers may indicate the last time the WTRU accessed the SCG, the last time the WTRU performed a recovery procedure to enter the RRC_CONNECTED state, and so on. The WTRU may determine the acceptability of the SCG or SCG configuration based on CSI measurements performed on a cell of the SCG (e.g., a PSCell of the SCG). For example, the WTRU may perform CSI measurements on a PSCell without reporting such measurements to the network. The WTRU may determine the acceptability of the SCG or SCG configuration based on beam measurements performed on the SCG. For example, the WTRU may determine whether the SCG or SCG configuration is acceptable based on whether a beam failure is detected in the PSCell of the SCG. The WTRU may perform beam failure detection on a PSCell of a dormant SCG and may activate a dormant SCG (e.g., to perform beam failure recovery).

[0138] The beam measurements performed on the SCG may or may not be associated with triggers associated with conditional SCG addition and / or reconfiguration. The WTRU may indicate the acceptability of the SCG or SCG configuration to the network. The WTRU's indication of the acceptability of the SCG or SCG configuration to the network may occur under one or more of the following conditions. When the WTRU decides to activate a suspended or dormant SCG while the WTRU is in RRC_CONNECTED, the WTRU may indicate the acceptability of the SCG or SCG configuration to the network. When the WTRU recovers from "inactive" to RRC_CONNECTED with a stored SCG or SCG configured to the WTRU in a recovery message, the WTRU may indicate the acceptability of the SCG or SCG configuration to the network. When the WTRU decides to suspend an active SCG while the WTRU is in RRC_CONNECTED, the WTRU may indicate the acceptability of the SCG or SCG configuration to the network. If the WTRU determines that the SCG changes from acceptable to unacceptable or from unacceptable to acceptable (for example, if the WTRU detects beam failure on the PSCell), the WTRU may indicate the acceptability of the SCG or SCG configuration to the network.

[0139] The WTRU may trigger the transmission of an RRC failure message to the MCG based on the determination of an unacceptable SCG or SCG configuration. If the stored and / or configured SCG is unacceptable (e.g., an SCGFailureIndication message may be triggered based on measurements of the stored / configured SCG), the WTRU may send an RRC failure message (e.g., SCGFailureIndication) to the MCG. The WTRU may be instructed by the network (e.g., during a transition from "inactive" to "connected") to restore the stored SCG configuration (e.g., in a restore message or command to the WTRU). The WTRU may compare measurements of the PSCell associated with the stored SCG configuration (e.g., collected during "inactive"), and if the PSCell quality is below a threshold, an SCG failure (e.g., SCGFailureIndication) or another RRC error message may be transmitted to the MCG. The error message transmission may be performed prior to transmitting a random access channel (RACH) request to the SCG or prior to the WTRU attempting to access the SCG. During the WTRU's transition to RRC_CONNECTED, the WTRU may be configured with an SCG configuration in a resume message from the network. The WTRU may determine whether the measurement of the PSCell of the SCG is above a threshold (before accessing the SCG). The WTRU may send an RRC error message after or together with an RRC complete message indicating that the WTRU transitioned to RRC_CONNECTED (for example, if the measurement of the PSCell of the SCG is not above a threshold). The WTRU may be configured with a dormant SCG and / or a suspended SCG. The WTRU may trigger the activation of a dormant and / or suspended SCG based on certain triggers (for example, data-related triggers), and may send an RRC failure message to the MCG or another SCG if the WTRU determines that the SCG or one of the previously dormant and / or suspended SCGs is determined to be unacceptable.

[0140] If the SCG is acceptable, the WTRU may perform random access to the SCG. The WTRU may indicate whether the SCG is acceptable via one or more random access messages to the SCG. If the SCG is acceptable, the WTRU may perform random access to the SCG, and if the SCG is not acceptable, the WTRU may not perform random access to the SCG. The WTRU may be configured with an SCG and may store the configuration when the WTRU is in an "inactive" state. The WTRU may receive a recovery message from the network with an indication to recover the stored SCG. The WTRU may evaluate whether the SCG is acceptable, and if the SCG is acceptable, the WTRU may initiate random access to the PSCell of the stored SCG. If the SCG is determined to be unacceptable to the WTRU, the WTRU may abandon performing the RACH procedure. If the WTRU determines that the SCG is unacceptable, the WTRU may keep the SCG configuration in a dormant or suspended state until the WTRU is reconfigured with a new SCG. The WTRU may then release the stored configuration. The WTRU may be configured with an SCG in the recovery message that the WTRU can access when in RRC_CONNECTED, and the WTRU may determine whether the SCG is acceptable. If the SCG is determined to be acceptable, the WTRU may perform random access to the configured SCG. If the SCG is not acceptable, the WTRU may forgo performing random access to the configured SCG. The WTRU may perform contention-free or contention-based random access depending on whether the SCG is acceptable. For example, if the SCG is acceptable, the WTRU may perform contention-free random access, and if the SCG is not acceptable, the WTRU may perform contention-based random access.

[0141] The WTRU may access the SCG (e.g., perform one or more access operations, such as a random access operation to the SCG) before initiating a recovery procedure to the MCG. In an example, the WTRU may be configured to perform an access operation to the SCG during a transition from INACTIVE to RRC_CONNECTED (e.g., based on a stored SCG configuration). The WTRU may perform the access operation before initiating a recovery procedure to the MCG, during a recovery procedure to the MCG (e.g., as part of a recovery procedure to the MCG), or before completing a recovery procedure.

[0142] Accessing the SCG before the recovery process to the MCG may include one or more of the following: performing a RACH process to the SCG, transmitting an RRC message or data PDU to the SCG, performing a beam failure recovery process to the SCG, and / or transmitting an uplink control signal (e.g., SR, PUCCH) to the SCG. The access process to the SCG may include one or more other operations or processes described herein with respect to a dormant SCG.

[0143] The WTRU may determine whether it is allowed to access the SCG prior to a recovery procedure to the MCG (e.g., prior to transmitting a recovery request or initiating a recovery operation) based on one or more of the following conditions. The WTRU may determine whether it is allowed to access the SCG based on conditions related to the time criticality of the data arriving at the WTRU. For example, if the data at the WTRU will be transmitted on an LCH that is pre-configured (e.g., via LCP restrictions or a specific L1 profile) to allow RACH procedures, a RACH procedure to the SCG may be allowed prior to the recovery procedure or upon completion of the recovery procedure (e.g., based on the time criticality of the LCH). The WTRU may determine whether it is allowed to access the SCG based on conditions related to the bearer type associated with the data arriving at the WTRU. For example, if the data arriving at the WTRU will be transmitted via an SCG bearer, a RACH procedure to the SCG may be allowed prior to the recovery procedure or upon completion of the recovery procedure. The WTRU may determine whether it is allowed to access the SCG based on a combination of the above conditions. For example, if the data arriving at the WTRU is to be transmitted via an SCG bearer, a RACH procedure to the SCG may be allowed before or upon completion of the recovery process, and the LCH associated with the data is configured with an LCP restriction or a specific L1 profile that allows the RACH procedure. The WTRU may determine whether to allow access to the SCG based on a comparison of the priorities of data intended for transmission to the MCG and the SCG. For example, if data pending at the WTRU during the recovery process indicates that the priority of the SCG data is higher than the priority of the MCG data, a RACH procedure to the SCG may be allowed before or upon completion of the recovery process. The WTRU may determine whether to allow access to the SCG based on information included in a paging message. For example, the network may request that a RACH procedure to the SCG be performed before or upon completion of the recovery process, such as via a specific indication in a paging message.

[0144] A WTRU configured to access an SCG prior to performing a recovery procedure on an MCG may delay the initiation of the recovery procedure or one or more actions associated with the recovery procedure, for example, until access to the SCG is successfully completed. The WTRU may provide an indication of successful SCG access or failed SCG access to the network during the recovery procedure. For example, the WTRU may include an SCGFailureInformation message in the recovery complete message. The WTRU may include a pass / fail indication in the recovery message to indicate the pass / fail status of the SCG access prior to the recovery procedure. The WTRU may select from a subset of RACH preambles to indicate the pass / fail status of the SCG access prior to the recovery procedure. The WTRU may select a RACH type (e.g., 2-step RACH versus 4-step RACH), or include a pass / fail indication in data transmitted using a 2-step RACH procedure.

[0145] The WTRU may be configured to handle MCG failure during (e.g., simultaneously with) an acceptability indication procedure for an SCG. For example, the WTRU may detect a RLF associated with an MCG while a procedure associated with an acceptability indication or conditional SCG configuration has begun or is in progress. In this case, the WTRU may not, for example, immediately declare an RLF. The WTRU may wait for the result of the acceptability indication or the conditional SCG configuration for the SCG. The WTRU may indicate an MCG failure based on a determination that the acceptability indication or conditional SCG configuration for the SCG is successful. The WTRU may declare an RLF based on an unsuccessful acceptability indication for the SCG. The WTRU may be configured with a timer or time period for completing the acceptability indication or conditional SCG configuration, and if the acceptability indication or conditional SCG configuration is not completed before the timer or time period expires, the WTRU may trigger connection reestablishment.

[0146] The WTRU may provide SCG acceptability information to the MCG via a RACH procedure (e.g., a 2-step RACH procedure). The WTRU may initiate a RACH procedure to the MCG to indicate whether a stored, configured and / or suspended SCG is acceptable. In an example, the WTRU may initiate a new RACH procedure to indicate the acceptability of a stored, configured and / or suspended SCG. In an example, the WTRU may provide acceptability information in a RACH procedure triggered for other purposes (e.g., resuming to RRC_CONNECTED). The WTRU may perform a RACH procedure on the MCG when resuming to the RRC_CONNECTED state and may provide an indication of the validity of the SCG configuration in the RACH procedure. The WTRU may provide acceptability information as part of the payload of the two-step RACH procedure (e.g., in MSG B of the RACH procedure). The WTRU may provide an indication in MSG B as to whether the SCG is valid. A WTRU in RRC_CONNECTED with a suspended and / or dormant SCG may be configured with one or more dedicated preambles associated with acceptable or unacceptable SCGs and may perform a RACH procedure using the appropriate preamble (e.g., depending on the WTRU's measurements and determination of the acceptability of the SCG). The WTRU may perform such a RACH procedure based on receiving an indication (e.g., a PDCCH command) from the network to perform the RACH procedure.

[0147] The WTRU may transmit a Medium Access Control (MAC) Control Element (CE) to the MCG with information or an indication of the acceptability of the SCG. The WTRU may transmit a MAC CE to the MCG to indicate the acceptability of the SCG, the reason for unacceptability, the specific SCG configuration for which the WTRU is reporting its acceptability information, and / or any combination thereof.

[0148] The WTRU may be configured to support concurrent (e.g., coexisting) CPAC and CHO configurations, including concurrently receiving CPAC and CHO configurations. In an example, when an RRC configuration or reconfiguration associated with CHO may already exist on the WTRU (e.g., may have been stored) and / or when the WTRU may have begun monitoring a trigger condition for CHO, the WTRU may receive an RRC configuration or reconfiguration message associated with CPAC (e.g., associated with a CPAC configuration). The WTRU may receive the CPAC configuration via one or more signaling radio bearers (SRBs) such as SRB1 or SRB3. The CPAC configuration may be associated with changes within a secondary node (intra-SN) or between secondary nodes (inter-SN). In an example, when an RRC configuration or reconfiguration associated with CPAC may already exist on the WTRU (e.g., may have been stored) and / or when the WTRU may have begun monitoring a trigger condition for CPAC, the WTRU may receive an RRC configuration or reconfiguration message associated with CHO (e.g., associated with a CHO configuration). The WTRU may receive the CHO configuration via one or more SRBs, such as via SRB1.

[0149] If the WTRU is configured with both CPAC and CHO configurations, the WTRU may be configured to handle the CPAC configuration or reconfiguration using one or more of the following exemplary methods. Different WTRU behaviors may be defined herein based on WTRU and / or network capabilities to support concurrent (e.g., coexisting) CPAC and CHO configurations. For example, some WTRUs may be able to handle coexisting CPAC and CHO configurations, but may not be configured to monitor CPAC and CHO trigger conditions. Some WTRUs may be able to monitor CPAC and CHO trigger conditions simultaneously, but may be configured to perform one configuration or reconfiguration at a time (e.g., for CPAC or CHO). Some WTRUs may be able to perform CPAC and CHO configurations or reconfigurations simultaneously. In a first exemplary method, the WTRU may be configured to perform one (e.g., only one) of the configurations (e.g., for CHO or CPAC). If the WTRU receives a CPAC configuration and the WTRU has received and / or stored a valid CHO configuration, the WTRU may be configured to send an indication to the SCG (e.g., to the SN associated with the SCG). If the WTRU receives a CHO configuration (e.g., from a MN) while the WTRU has already received and / or stored a valid CPAC configuration, the WTRU may be configured to send an indication to the SCG (e.g., to a SN associated with the SCG). The indication sent by the WTRU may indicate that the WTRU may not be able to comply with the CPAC configuration or the CHO configuration (e.g., because the other of the CPAC or CHO configurations already exists on the WTRU). The indication may list having a conflicting configuration from the MN as the reason for not being able to comply with the CPAC configuration or the CHO configuration.

[0150] In a second exemplary method, the WTRU may be configured to receive and / or store both CPAC and CHO configurations. The WTRU may choose to monitor trigger conditions associated with CHO and ignore monitoring trigger conditions associated with CPAC, or the WTRU may choose to monitor trigger conditions associated with CPAC and ignore monitoring trigger conditions associated with CHO.

[0151] In a third exemplary method, the WTRU may be configured to receive and / or store CPAC and CHO configurations and monitor trigger conditions associated with the CPAC and CHO configurations.

[0152] The behavior of the WTRU when trigger conditions associated with CHO and CPAC are met (e.g., simultaneously) may be defined or pre-configured (e.g., by a network entity). For example, the WTRU may be configured to perform one or more actions associated with the CPAC configuration based on the status of one or more trigger conditions associated with the CHO configuration. The WTRU may be configured with one or more of the following behaviors.

[0153] The WTRU may prioritize CHO over CPAC. For example, the WTRU may be configured to prioritize CHO over CPAC if one or more trigger conditions associated with both CHO and CPAC are met (e.g., simultaneously). In an example, for example, the WTRU may abort an ongoing CPAC action if one or more trigger conditions for CHO are met. The WTRU may be configured to release one or more (e.g., all) CPAC configurations and / or stop monitoring trigger conditions associated with CPAC configurations.

[0154] The WTRU may disable one or more CPAC actions. For example, the WTRU may be configured to disable one or more actions related to CPAC in response to determining that a CHO trigger is about to occur (e.g., based on the WTRU's evaluation of one or more CHO trigger conditions). The WTRU may be configured to disable one or more CPAC actions based on a pre-configured trigger condition. In an example, the pre-configured trigger condition may be a measurement event associated with the CHO trigger condition. For example, if the CHO trigger condition satisfies an entry condition (e.g., if a timer associated with the CHO trigger condition is running), the WTRU may be configured to stop monitoring the trigger condition associated with CPAC.

[0155] The WTRU may support concurrent execution of CHO and CPC (e.g., without prioritizing one over the other), including, for example, triggering or executing CHO and CPAC simultaneously. For example, the WTRU may trigger CHO while CPAC is in progress, or the WTRU may trigger CHO while CPAC is in progress.

[0156] The behavior of the WTRU as described in other parts of the present disclosure (e.g., related to conditional reconfiguration, monitoring of triggering conditions for conditional reconfiguration, and messaging between the WTRU and network nodes associated with conditional reconfiguration) may not be affected by the WTRU's reception and processing of concurrent CHO and CPC configurations.

[0157] The WTRU may be configured to transmit (e.g., in an RRC completion message, such as an RRCReconfigurationComplete message) an indication that a CPAC execution trigger condition is satisfied. The indication may be transmitted to a cell that may depend on the process or trigger of CHO. The WTRU may transmit an indication that a CPAC execution trigger is satisfied to a CHO candidate (e.g., a target of a triggered CHO). The WTRU may transmit an indication that a CPAC execution trigger is satisfied to a PCell to which the WTRU is connected before triggering CHO. The WTRU may determine the destination cell for the indication based on the timing of the triggering of CHO and / or CPAC. In an example, if CPAC is triggered at the same time as CHO, the WTRU may transmit the indication to the source PCell. In an example, if the trigger time of CHO occurs after the trigger time of CPAC, the WTRU may transmit the indication to the source PCell. In an example, if the CPAC trigger condition is satisfied after CHO is triggered, such as when the CPAC trigger condition is satisfied after an offset time has passed after triggering CHO, the WTRU may transmit an indication to the CHO target. The offset time may be a configured time period or may be defined based on the steps or actions taken by the WTRU in association with CHO. For example, the WTRU may send an indication to the CHO target if it has completed synchronization with the CHO target, if the WTRU has applied the CHO target cell configuration, etc.

[0158] The WTRU may be configured to not transmit an indication of CPAC execution in some cases (e.g., if CPAC is triggered simultaneously with CHO, if CPAC is triggered during an ongoing CHO, etc.). In an example, if a triggering condition (e.g., for CPAC) is met during the execution of CHO, the WTRU may forgo transmission of such an indication. In an example, if a triggering condition (e.g., for CPAC) occurs after CHO is completed (e.g., after receiving an acknowledgement associated with a transmission complete message to the target), the WTRU may transmit the indication.

[0159] The WTRU may be configured to transmit an indication of CPAC execution to a network node (e.g., to an auxiliary node) in the event of a CHO failure. For example, such a failure may occur if the WTRU has not yet transmitted an indication of CPAC execution or the transmission of the indication of CPAC execution is delayed due to the occurrence of CHO. The WTRU may include the indication of CPAC execution in a failure message (e.g., a MCGFailureInformation message), which may be transmitted after a failed CHO.

[0160] The WTRU may be configured to delay transmission of a CPAC execution indication until CHO is complete. For example, if CPAC and CHO are triggered simultaneously, or if CHO is in progress when the CPAC trigger condition is met, the WTRU may delay transmission. If CHO may be triggered in the near future (e.g., if a trigger time associated with a CHO event begins), the WTRU may delay transmission of the indication. The WTRU may continue to transmit the indication after CHO is complete or if CHO is not triggered (e.g., if the trigger time has not expired and / or if CHO is not executed).

[0161] The WTRU may determine whether to send an indication of CPAC triggering to the primary node or the secondary node, for example, based on the configuration of an SRB (e.g., SRB3) and / or the execution of CHO. For example, if SRB3 is configured and CHO is ongoing, the WTRU may send an indication via SRB3.

[0162] The WTRU may be configured with events (e.g., measurement events) and / or trigger conditions that apply to both CHO and CPAC. For example, the WTRU may be configured with a single event that applies to both CHO and CPAC (e.g., by including configuration of both MCG and SCG in the conditional reconfiguration candidates). The WTRU may be configured with an offset or threshold associated with a trigger condition (e.g., measurement event), and for example, if the trigger condition applies to both CHO and CPAC, the offset or threshold may be applied to CHO or CPAC. The WTRU may be configured to apply CHO if the trigger condition meets a first threshold, and to apply CPAC if the trigger condition meets a second threshold.

[0163] The WTRU may be configured to process CPAC candidates based on CHO or HO. The WTRU may be configured to perform one or more of the following when processing a CPAC configuration (e.g., when completing a CHO process). The radio resource configuration associated with the CPAC configuration may be a function of the current MCG. In an example, the WTRU may be configured to perform CHO when connected to the same SCG. In an example, the WTRU may be configured to perform HO when connected to the same SCG. The impact of changing the MCG (e.g., switching to another MCG) when connected to the same SCG may include that one or more stored CPAC configurations may or may not be valid in the target MCG. The WTRU may be configured to determine the validity of a stored CPAC configuration based on a CHO or HO process. The WTRU may be configured to indicate (e.g., to a secondary node) the status of a CHO or HO process. Such an indication may be used (e.g., by a secondary node) to determine whether the CPAC configuration is valid and / or to reconfigure (e.g., update) the existing CPAC configuration if the existing CPAC configuration is no longer valid. Even if one or more of the following techniques are described in the context of CHO, these techniques may also be applicable to both CHO and HO.

[0164] If the WTRU successfully completes the CHO process and / or if the trigger conditions associated with CHO are met, the WTRU may be configured to perform one or more actions associated with the stored CPAC configuration (if any). The WTRU may be configured to perform one or more of the following. If the WTRU successfully completes the CHO, the WTRU may transmit an indication to the SCG (e.g., to a network node associated with the SCG). The WTRU may include the identity of the new PCell in the indication. If the SRB (e.g., SRB3) is configured for the SCG, the WTRU may transmit such an indication. If a stored CPAC configuration is received from a secondary node, for example, if the WTRU determines that the primary node is not involved in the CPAC configuration, the WTRU may transmit such an indication.

[0165] If one or more trigger conditions associated with CHO are met, the WTRU may transmit an indication to the SCG (e.g., to a network node associated with the SCG). The WTRU may include an identity of the cell that meets one or more CHO trigger conditions. The WTRU may transmit such an indication if an SRB (e.g., SRB3) is configured for the SCG. The WTRU may transmit such an indication if a stored CPAC configuration is received from a secondary node, for example, if the WTRU determines that the primary node is not involved in the CPAC configuration.

[0166] The WTRU may be configured to release (e.g., autonomously release) the stored CPAC configuration if the CHO completes successfully. The WTRU may stop monitoring the trigger condition associated with the released CPAC configuration. The WTRU may send an indication to the SCG (e.g., to a network node associated with the SCG) indicating the release of the CPAC configuration.

[0167] The WTRU may be configured to suspend (e.g., autonomously suspend) a stored CPAC configuration if the CHO completes successfully. The WTRU may stop monitoring a trigger condition associated with the suspended CPAC configuration. The WTRU may send an indication to the SCG (e.g., to a network node associated with the SCG) indicating the suspension of the CPAC configuration. The WTRU may be configured to receive a command (e.g., from the SCG) to activate and / or reconfigure the suspended CPAC configuration.

[0168] The WTRU may be configured to selectively release or suspend CPAC configurations based on the completion of CHO. The WTRU may be configured to suspend or release CPAC configurations based on one or more of the following conditions. The WTRU may be configured to suspend or release CPAC configurations based on the origin of the CPAC configurations. For example, the WTRU may be configured to release or suspend those CPAC configurations received from the secondary node and maintain the CPAC configurations received from the primary node. The WTRU may be configured to release or suspend those CPAC configurations received from the primary node and maintain the CPAC configurations received from the secondary node.

[0169] The WTRU may be configured to suspend or release a CPAC configuration based on the compatibility of the CPAC configuration with the cell group. For example, the WTRU may be configured to release a CPAC configuration that is no longer compatible with the new MCG after CHO. The WTRU may be configured with compatibility information about the CPAC configuration of (e.g., each) CHO candidate, for example, via a link configuration. The WTRU may maintain those (e.g., only those) CPAC configurations associated with the CHO candidate that successfully completed CHO.

[0170] The WTRU may be configured to suspend or release a CPAC configuration based on an explicit configuration. For example, the WTRU may be explicitly configured (e.g., by the network) as to which one or more CPAC configurations may be maintained after a successful CHO or HO procedure. The WTRU may be explicitly configured (e.g., by the network) as to which one or more CPAC configurations should be released after a successful CHO or HO procedure.

[0171] The WTRU may be configured to process one or more CHO candidates based on CPAC. The WTRU may be configured to process a CHO configuration based on the completion of a CPAC process. The radio resource configuration associated with the CHO configuration may be a function of the current SCG associated with the WTRU. In an example, the WTRU may be configured to perform CPAC when one or more CHO configurations are stored and / or if the WTRU is connected to the same MCG.

[0172] The WTRU may be configured to determine the validity of a stored CHO configuration based on the execution of a CPAC procedure. The WTRU may be configured to indicate the status of the CPAC procedure to the master node. Such indication may be used by the master node to determine whether the CHO configuration is valid and / or to reconfigure the CHO configuration if the CHO configuration is no longer valid.

[0173] The WTRU may be configured to determine possible CHO candidates based on the serving SCG. The WTRU may be configured with an association (e.g., a mapping) between a CPAC configuration and a CHO configuration. More than one CPAC configuration may be associated with the same CHO configuration, and vice versa. For example, if the serving SCG changes due to a CPAC process, the WTRU may be configured to activate and deactivate one or more linked CHO configurations. The WTRU may release a CHO configuration that is not linked to the current SCG. The WTRU may be configured to report an indication of the status of the CHO candidate to the MCG (e.g., to a network node associated with the MCG) based on a successful CPAC completion. The WTRU may be configured to perform one or more functions described herein for (e.g., only for) a CPAC configuration configured by the SCG.

[0174] If the WTRU successfully completes the CPAC procedure, if a trigger condition associated with CPAC is met, etc., the WTRU may be configured to perform one or more actions associated with a stored CHO configuration (if any). The WTRU may be configured with one or more of the following behaviors.

[0175] When the WTRU completes CPAC (e.g., if CPAC completes successfully, if CPAC results in a failure, etc.), the WTRU may transmit an indication to the MCG (e.g., to a network node associated with the MCG). The WTRU may include the identity of the new PSCell in the indication. The WTRU may transmit such an indication if the relevant CPAC configuration is received from the SCG (e.g., from a network node associated with the SCG). The WTRU may transmit such an indication if the CPAC configuration is received from a secondary node, for example, if the WTRU can determine that the primary node is not involved in the CPAC configuration.

[0176] If one or more trigger conditions associated with CPAC are met, the WTRU may transmit an indication to the MCG (e.g., to a network node associated with the SCG). The WTRU may include the identity of the cell that meets the CPAC condition. If a CPAC configuration is received from a secondary node, for example, if the WTRU can determine that the primary node is not involved in the CPAC configuration, the WTRU may transmit such an indication.

[0177] The WTRU may selectively release or suspend the CHO configuration based on CPAC completion. The WTRU may be configured to suspend or release the CHO configuration based on one or more of the following conditions. The WTRU may be configured to suspend or release the CHO configuration based on the origin of the CPAC configuration. For example, the WTRU may be configured to suspend or release the CHO configuration if the CPAC configuration is received from a secondary node.

[0178] The WTRU may be configured to suspend or release a CHO configuration based on an explicit configuration. For example, the WTRU may be explicitly configured as to which one or more CHO configurations should be maintained after a successful CPAC procedure. The WTRU may be explicitly configured as to which one or more CHO configurations should be released after a successful CPAC procedure.

[0179] The WTRU may be configured to handle concurrent CPAC configurations initiated by a master node (MN) and a second node (SN). A CPAC configuration from one cell group may override a CPAC configuration from another cell group. The WTRU may be configured to receive a CPAC configuration from a MN or SN. The WTRU may be configured to handle CPAC configurations from one (e.g., only one) cell group under pre-configured conditions. For example, if the CPAC configuration is prioritized based on the SRB (e.g., SRB1 or SRB3) in which the CPAC configuration is received, one or more of the following items may apply. The examples described herein in the context of CPAC configuration initiated by the MN and / or SN may also apply to situations where an RRC reconfiguration initiated by the MN and / or SN may affect a stored SCG configuration and / or an active SCG configuration. The examples described herein may also apply if the WTRU is configured to store at least one CPAC initiated by the SN at the WTRU (e.g., upon receiving an RRC reconfiguration from the MN). The examples described herein may also apply if the WTRU is configured to store at least one CPAC initiated by the MN at the WTRU (eg, upon receiving an RRC reconfiguration from the SN).

[0180] The WTRU may be configured to prioritize CPAC configurations based on the earliest arrival time of the CPAC configurations. In an example (e.g., if the WTRU receives a CPAC configuration from the SN, while the WTRU has a valid CPAC configuration received from the MN and stored at the WTRU), the WTRU may ignore the CPAC configuration received from the SN. The WTRU may be configured to send a failure message to the SN, indicating that the CPAC configuration cannot be complied with and the reason why it cannot be complied with (e.g., an earlier configuration from a different cell group exists at the WTRU). In an example (e.g., if the WTRU receives a CPAC configuration from the MN, while the WTRU has a valid CPAC configuration received from the SN and stored at the WTRU), the WTRU may ignore the CPAC configuration received from the MN. The WTRU may be configured to send a failure message to the MN, indicating that the CPAC configuration cannot be complied with and the reason why it cannot be complied with (e.g., an earlier configuration from a different cell group exists at the WTRU).

[0181] The WTRU may be configured to prioritize CPAC configurations based on their latest arrival time. In an example (e.g., if the WTRU receives a CPAC configuration from the SN while the WTRU has a valid CPAC configuration received from the MN), the WTRU may release the CPAC configuration received from the MN and process (e.g., store) the CPAC configuration received from the SN. The WTRU may be configured to send a failure message to the MN indicating the inability to comply with the CPAC configuration and the reason for the inability to comply (e.g., the CPAC configuration was overwritten by a new or later arriving configuration).

[0182] In an example (e.g., if the WTRU receives a CPAC configuration from the MN while the WTRU has a valid CPAC configuration received from the SN), the WTRU may release the CPAC configuration received from the SN and process (e.g., store) the CPAC configuration received from the MN. The WTRU may be configured to send a failure message to the SN indicating the inability to comply with the CPAC configuration and the reason for the inability to comply (e.g., the CPAC configuration was overwritten by a new or later arriving configuration).

[0183] The WTRU may be configured to prioritize CPAC configurations based on a cell group or SRB associated with the WTRU. In an example, the WTRU may prioritize a CPAC configuration received from a MN regardless of the presence of an earlier CPAC configuration received from a SN. In an example, the WTRU may be configured to prioritize a CPAC configuration received on a first SRB (e.g., SRB1) over a CPAC configuration received on a second SRB (e.g., SRB3).

[0184] The WTRU may be configured to prioritize CPAC configurations based on an explicit indication. The WTRU may be configured to prioritize CPAC configurations based on an explicit priority indication, such as an explicit priority indication included as part of the CPAC configuration. The WTRU may be configured to override a low priority CPAC configuration with a high priority CPAC configuration.

[0185] The WTRU may be configured to process a CPAC configuration from one cell group based on a CPAC configuration from another cell group. The WTRU may be configured to receive and process CPAC configurations from MCGs and SCGs. If the WTRU receives a CPAC configuration associated with the same target PSCell, the WTRU may be configured with rules for processing the CPAC configuration. For example, the WTRU may be configured to replace or modify an existing CPAC configuration with another CPAC configuration (e.g., a new CPAC configuration) when the PSCell configuration associated with the CPAC configuration is the same. The WTRU may be configured to replace or modify an existing CPAC configuration when (e.g., only when) an earlier CPAC configuration is received from the same cell group. The WTRU may be configured to report (e.g., to a network node) the cell group whose CPAC configuration is overwritten or modified.

[0186] For example, if CPAC is configured, the WTRU may be configured to handle SCG failure. If CPAC is configured for the WTRU, the WTRU may trigger an SCG failure (e.g., SCG RLF, CPAC failure, etc.). For example, the WTRU may initiate CPAC on a PSCell candidate (e.g., a stored PSCell candidate based on a previously received configuration message) with or without transmitting an SCGFailureInformation message to the MN.

[0187] The WTRU may determine which one or more of the above actions to follow (e.g., triggering CPAC and / or performing SCG failure procedures) based on one or more of the following items. The WTRU may determine its behavior based on the existence of a CHO configuration and / or a CHO procedure currently in progress. For example, if the WTRU is currently performing CHO when CPAC is triggered, the WTRU may perform CPAC on the candidate PSCell after SCG failure. The WTRU may initiate an SCG failure procedure to the MN (e.g., transmitting an SCG failure indication, such as an SCGFailureInformation message).

[0188] The WTRU may determine its behavior based on the node (MN or SN) that configures the CPAC and / or the SRB used to configure the CPAC. For example, if the CPAC candidate is configured by the SN or via a certain SRB such as SRB3, the WTRU may perform CPAC on the candidate PSCell after an SCG failure. Otherwise, the WTRU may initiate an SCG failure procedure (e.g., transmit an SCGFailureInformation message).

[0189] The WTRU may determine its behavior based on the presence of a CHO configuration, such as a CHO configuration linked to a CPAC configuration. For example, if the WTRU does not have a CHO configuration linked to a CPAC candidate, the WTRU may perform CPAC on a candidate PSCell after an SCG failure. If the WTRU has a CHO configuration when an SCG failure occurs, or if such a CHO configuration is linked to a CPAC candidate, the WTRU may initialize the SCG failure procedure (e.g., transmitting an SCGFailureInformation message to the MN).

[0190] An SCG may be added for the WTRU. Figure 3 An example of applying an SCG configuration when a condition is met is shown. The WTRU may be in a connected state with a source MCG. The WTRU may receive a message (e.g., an RRCReconfiguration or RRCConnectionReconfig message) from an MCG (e.g., an MN associated with the MCG) that includes or indicates an SCG configuration, an SCG reconfiguration, and / or a trigger condition for performing the SCG configuration or reconfiguration (e.g., the SCG configuration or reconfiguration may be conditional). As described herein, the SCG configuration or reconfiguration may be related to a PSCell change or addition. In response to receiving the message, the WTRU may store the SCG configuration or reconfiguration and may begin monitoring for the trigger condition included or indicated in the message. The WTRU may be configured to transmit a first message to the MN based on receipt of a configuration message (e.g., Figure 3 The WTRU may indicate in a first message (e.g., RRC Response 1) that the WTRU has received and / or stored the conditional SCG configuration or reconfiguration and has started monitoring the triggering conditions included therein (e.g., so that the network may be aware of the state and / or subsequent actions of the WTRU). In an example, the first message (e.g., RRC Response 1) may correspond to an RRC Reconfiguration Complete message. If (e.g., at a later point in time) the triggering condition is met, the WTRU may transmit a second message (e.g., RRC Response, such as Figure 3The WTRU may indicate in the second message (e.g., RRC Response 2) that the triggering condition for applying the conditional SCG configuration or reconfiguration is met. The WTRU may apply the SCG configuration or reconfiguration in response to determining that the triggering condition is met. For example, the WTRU may initialize a RACH procedure to the candidate SCG. The WTRU may, for example, indicate in the second message (e.g., RRC Response 2) that the triggering condition for applying the conditional SCG configuration or reconfiguration is met. Figure 3 The WTRU may transmit a third message to the MN, and the third message may indicate the failure. In the example, the third message may correspond to an RRC reconfiguration failure message.

[0191] Figure 4 An example of applying an SCG configuration or reconfiguration (e.g., a conditional SCG configuration or reconfiguration as described herein) in the presence of an RLF is shown. The WTRU may detect a radio link problem, such as an RLF, in an MCG, for example, while monitoring a trigger condition for applying the SCG configuration or reconfiguration. In this case, the WTRU may accelerate the application of the stored SCG configuration and may, for example, access the corresponding SCG without waiting for the trigger condition to be met (e.g., via a random access procedure). If the random access is successful, the WTRU may indicate an MCG failure to the SCG. If the WTRU cannot access the SCG, the WTRU may declare an RLF. The WTRU may be configured with a general cell group configuration so that the configuration may be applied as an MCG configuration or an SCG configuration. In the event of an MCG RLF, the WTRU may promote the general cell group configuration to an MCG configuration and perform a conditional handover to the MCG corresponding to the promoted MCG configuration.

[0192] The WTRU may be configured to apply conditional MCG reconfiguration, for example when connected to an SCG. Figure 5An example of a WTRU performing an enhanced recovery action is shown. The WTRU may be configured with multiple connections, for example, to a source MCG and a source SCG. The WTRU may receive a conditional reconfiguration associated with the MCG. The WTRU may begin monitoring a trigger condition for a conditional MCG reconfiguration. In an example, the WTRU may encounter a radio link problem in the source MCG, for example, while waiting for a trigger condition for a candidate MCG. In this case, the WTRU may be configured to perform one or more enhanced recovery actions. The enhanced recovery action may include one or more of the following items. The enhanced recovery action may include transmitting MCG failure information via the source SCG. The enhanced recovery action may include triggering connection reestablishment. For example, if the WTRU selects a candidate MCG, the WTRU may perform CHO (for example, to the candidate MCG) using a stored MCG reconfiguration. The WTRU may be configured with one or more rules regarding whether to transmit MCG failure information via the source SCG and / or trigger connection reestablishment. One or more rules may be based on an evaluation of the cell quality associated with the source SCG and the candidate MCG, the presence of SCG bearers, the presence of SRB3 or separated SRB1 / 2, and the like.

[0193] In an example, the WTRU may be configured to transmit MCG failure information via the source SCG for recovery if one or more of the following conditions are met. The WTRU may be configured to transmit MCG failure information via the source SCG if the quality of the source SCG is better than the cell quality threshold and the quality of the candidate MCG is lower than the cell quality threshold. The WTRU may be configured to transmit MCG failure information via the source SCG if the source SCG is configured with SRB3 and / or separated SRB1 / 2. If any condition is not met, the WTRU may trigger connection reestablishment. When performing connection reestablishment, for example, if the cell quality of the SCG meets the minimum threshold, the WTRU may transmit MCG failure information to the SCG.

[0194] In one or more recovery options, the WTRU may be configured with rules that determine the release of the source SCG connection and / or SCG configuration. For example, the WTRU may be configured to continue transmitting data to the source SCG until the result of the conditional reconfiguration on the MCG is known. If the conditional handover on the MCG fails, the WTRU may indicate the failure by sending MCG failure information to the source SCG. If the conditional handover on the MCG is successful, for example, if the source SCG configuration is not linked to the candidate MCG configuration, the WTRU may release the source SCG configuration. If the source SCG configuration is linked to the candidate MCG configuration, the WTRU may retain the source SCG configuration.

[0195] The WTRU may be provided with simultaneous conditional MCG reconfiguration and SCG reconfiguration. Figure 6An example of a WTRU monitoring a conditional configuration or reconfiguration is shown. The WTRU may be configured with multiple connections, for example, to a source MCG and a source SCG. The WTRU may receive an RRC message, such as an RRCReconfiguration message, which includes an SCG configuration or reconfiguration (e.g., a conditional SCG configuration or reconfiguration) of a candidate SCG1 and a trigger condition for the configuration or reconfiguration. The WTRU may store the SCG configuration or reconfiguration and may start monitoring the trigger condition associated with SCG1. Such a reconfiguration may correspond to an SCG change process. The WTRU may also receive an RRC reconfiguration message including, for example, a conditional MCG configuration or reconfiguration corresponding to a switch to a candidate MCG. The WTRU may also receive, for example, a conditional SCG configuration or reconfiguration corresponding to the addition of SCG2 linked to a candidate MCG. In terms of monitoring conditional reconfiguration, the WTRU may be configured to perform one or more of the following items. The WTRU may perform monitoring on three candidates: candidate SCG1, candidate SCG2, and candidate MCG. The WTRU may perform selective monitoring, in which one or more of the following items may be applied. The WTRU may be configured to monitor a layer (e.g., one of the candidate layers). For example, if the WTRU is configured with a candidate MCG reconfiguration, the monitoring of the SCG may be suspended. In addition to monitoring the MCG reconfiguration, the WTRU may select a subset of SCG reconfigurations to monitor. For example, the WTRU may perform monitoring of candidate SCG1 and candidate MCG and may suspend monitoring of candidate SCG2. If the candidate MCG meets the trigger condition, the WTRU may start monitoring the trigger condition for SCG2. The WTRU may monitor the candidate MCG and candidate SCG2 and may suspend monitoring of candidate SCG1.

[0196] If the candidate MCG is successfully reconfigured, the WTRU may be configured to perform one of the following operations. If the candidate MCG reconfiguration is triggered, the WTRU may release the source SCG configuration. If the source SCG is not linked to the candidate MCG configuration, the WTRU may release the source SCG configuration. The WTRU may continue to use the source SCG configuration until there is an explicit indication from the candidate MCG.

[0197] In an exemplary implementation, the WTRU may be configured with a conditional reconfiguration information element (IE) (e.g., conditionalReconfiguration) in an RRC message such as an RRCReconfiguration message. Such IE may carry information about a target PCell (e.g., for MCG reconfiguration) and / or a target PSCell (e.g., for SCG reconfiguration) having respective associated trigger conditions. The WTRU may receive a conditional reconfiguration IE (e.g., conditionalReconfiguation) associated with a PSCell change via SRB3 and a conditional reconfiguration IE associated with a PCell change via SRB1. The WTRU may be configured to ensure that one (e.g., only one) conditional reconfiguration IE associated with an MCG or SCG is active.

[0198] The stored PSCell Conditional Reconfiguration IE may be removed based on the reception of the PCell Conditional Reconfiguration IE. A conditional handover configuration (CHO-Config) may be added or modified. The WTRU may perform one or more of the following (e.g., for the CHO-ConfigId received in the cho-ConfigToAddModListIE, for each CHO-ConfigId received in the cho-ConfigToAddModList IE, and so on). If the cho-ConfigToAddModList includes an mn-ExecutionCond, and there is at least one entry with sn-ExecutionCond in the cho-ConfigToAddModList within the VarCHO-Config, the WTRU may remove the entry associated with the sn-ExecutionCond in the VarCHO-Config and report an SCG configuration failure (e.g., based on an inability to comply with the RRCReconfiguration received via SRB3 and / or based on a conflict with the MCG configuration). If there is an entry with a matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config, the WTRU may replace the entry with the value received for that CHO-ConfigId. If there is no entry with a matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config, the WTRU may add a new entry for the CHO-ConfigId within VarCHO-Config. The WTRU may perform conditional handover monitoring, for example, as specified herein.

[0199] For example, if at least one PCell conditionalReconfiguration is stored, the WTRU may be configured to ignore the received PSCell conditionalReconfiguration. The WTRU may perform one or more of the following (e.g., for the CHO-ConfigId received in the cho-ConfigToAddModList IE, for each CHO-ConfigId received in the cho-ConfigToAddModList IE, etc.). If cho-ConfigToAddModList includes sn-ExecutionCond and there is at least one entry with mn-ExecutionCond in the cho-ConfigToAddModList within the VarCHO-Config, the WTRU may report an SCG configuration failure (e.g., based on an inability to comply with the RRCReconfiguration received via SRB3 and / or based on a conflict with an MCG configuration). If cho-ConfigToAddModList includes sn-ExecutionCond, no entry with mn-ExecutionCond exists in cho-ConfigToAddModList within VarCHO-Config, and there is an entry with matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config, then the WTRU may replace the entry with the value received for CHO-ConfigId. If cho-ConfigToAddModList includes sn-ExecutionCond, no entry with mn-ExecutionCond exists in cho-ConfigToAddModList within VarCHO-Config, and there is no entry with matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config, then the WTRU may add a new entry for that CHO-ConfigId within VarCHO-Config. If cho-ConfigToAddModList includes sn-ExecutionCond but there is no entry with mn-ExecutionCond in cho-ConfigToAddModList within VarCHO-Config, the WTRU may perform conditional handover monitoring, for example, as specified herein.

[0200] The above logic can be explained by the following:

[0201] For each CHO-ConfigId received in the cho-ConfigToAddModList IE, the WTRU shall:

[0202] 1> If cho-ConfigToAddModList includes mn-ExecutionCond:

[0203] 2> If there is at least one entry with sn-ExecutionCond in cho-ConfigToAddModList within VarCHO-Config:

[0204] 3>Remove the entry associated with sn-ExecutionCond in VarCHO-Config.

[0205] 3> Report SCG configuration failure according to the sub-clause corresponding to "Unable to comply with RRCReconfiguration received via SRB3", possibly with a new clause "Conflict with MCG configuration"

[0206] 1> If there is an entry with a matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config:

[0207] 2>Replace the entry with the value received for that CHO-ConfigId;

[0208] 1> Otherwise:

[0209] 2>Add a new entry for this CHO-ConfigId in VarCHO-Config;

[0210] 1>Execute the conditional switching monitoring as specified in this article;

[0211] For each CHO-ConfigId received in the cho-ConfigToAddModList IE, the WTRU shall:

[0212] 1> If cho-ConfigToAddModList includes sn-ExecutionCond:

[0213] 2> If there is at least one entry with mn-ExecutionCond in cho-ConfigToAddModList within VarCHO-Config:

[0214] 3> Possible new failure clauses according to the sub-clause corresponding to "Unable to comply with RRCReconfiguration received via SRB3"

[0215] "Conflict with MCG configuration", reports SCG configuration failure

[0216] 2> Otherwise

[0217] 3> If there is an entry with a matching CHO-ConfigId in cho-ConfigToAddModList within VarCHO-Config:

[0218] 4>Replace the entry with the value received for that CHO-ConfigId;

[0219] 3> Otherwise:

[0220] 4>Add a new entry for this CHO-ConfigId in VarCHO-Config; 3>Perform conditional switching monitoring as specified in this article;

[0221] Although the features and elements of the present disclosure may consider new radio (NR) or 5G specific protocols, it should be understood that the solutions described herein are not limited to this scenario and are also applicable to other wireless systems. Although the features and elements are described above in a specific combination, it will be understood by those of ordinary skill in the art that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software or firmware that is incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with the software can be used to implement a radio frequency transceiver for the device described herein.

Claims

1. A wireless transmit / receive unit (WTRU), comprising: a processor configured to operate with a master cell group (MCG) and a secondary cell group (SCG), wherein the processor is configured to: When the SCG is deactivated, performing one or more uplink transmissions in the MCG; determining that data associated with the SCG is available for transmission; and A message is sent to a network device associated with the MCG, wherein the message indicates that the data associated with the SCG is available for transmission.

2. The WTRU of claim 1 , wherein: The processor being configured to determine that data associated with the SCG is available for transmission includes the processor being configured to determine that the data is associated with a radio bearer associated with the SCG.

3. The WTRU of claim 1 , wherein: After sending the message to the network device, the processor is further configured to activate the SCG to transmit the data associated with the SCG.

4. The WTRU of claim 3, wherein: The data is transmitted to a network device associated with the SCG.

5. The WTRU of claim 4, wherein: The network device associated with the SCG includes a base station configured to operate as a secondary node (SN) for the WTRU.

6. The WTRU of claim 1 , wherein: The network device associated with the MCG includes a base station associated with the MCG.

7. The WTRU of claim 6, wherein: The processor is further configured to receive configuration information about the MCG and the SCG from the base station.

8. The WTRU of claim 7 wherein: The configuration information indicates that the SCG is a deactivated SCG.

9. The WTRU of claim 7 wherein: The configuration information indicates that the SCG is an activated SCG, and wherein the processor is further configured to deactivate the SCG based on a condition.

10. The WTRU of claim 1 wherein: The processor is configured to: when the SCG is deactivated, not monitor a physical downlink control channel associated with the SCG.

11. A method implemented by a wireless transmit / receive unit (WTRU) configured to operate with a master cell group (MCG) and a secondary cell group (SCG), the method comprising: When the SCG is deactivated, performing uplink transmission in the MCG; determining that data associated with the SCG is available for transmission; and A message is sent to a network device associated with the MCG, wherein the message indicates that the data associated with the SCG is available for transmission.

12. The method according to claim 11, further comprising: After sending the message to the network device, the SCG is activated to transmit the data associated with the SCG.

13. The method according to claim 12, wherein: The data is transmitted to a network device associated with the SCG.

14. The method according to claim 11, wherein: The network device associated with the MCG includes a base station associated with the MCG.

15. The method according to claim 14, further comprising: Configuration information about the MCG and the SCG is received from the base station, wherein the configuration information indicates that the SCG is a deactivated SCG.

Images