Fast Setup / Resume

Abstract

A wireless transmit / receive unit (WTRU) may be configured for L1 / L2 triggered mobility (LTM). The WTRU may receive configuration information from a cell while the WTRU is in connected mode. The configuration information may indicate multiple LTM candidate cells. The WTRU may receive a measurement configuration while the WTRU is in inactive mode. The WTRU may perform measurements on one or more of the multiple LTM candidate cells while the WTRU is in inactive mode according to the measurement configuration. The WTRU may send a report including these measurements during a random access procedure. The WTRU may receive candidate configuration information for at least one LTM candidate cell of the multiple LTM candidate cells during the random access procedure. The WTRU may perform an LTM procedure for the at least one LTM candidate cell upon transitioning to connected mode.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 445,557, filed February 14, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to devices, methods, and systems for high speed secondary cell (SCell) and secondary cell group (SCG) setup and resume. Summary of the Invention

[0003] Described herein are devices, methods, and systems for enabling fast secondary cell (SCell) and secondary cell group (SCG) setup and resume. A wireless transmit / receive unit (WTRU) may be configured for Layer 1 (L1) and Layer 2 (L2)-based inter-cell mobility, measurements, and RRC_INACTIVE. In some implementations, the WTRU may be configured for fast setup / resume (e.g., early measurements and L1 / L2 triggered mobility (LTM) triggers during random access procedures). The WTRU may be configured to update LTM candidates in RRC_INACTIVE. The WTRU may be configured to maintain LTM early measurements in RRC_INACTIVE.

[0004] Described herein are devices, methods, and systems for fast SCG and SCell setup and resume based on early measurements and / or LTM triggers during a random access (RA) procedure. In some implementations, a WTRU may receive pre-configuration (e.g., configuration information) of LTM candidate cells in RRC_CONNECTED. The WTRU may receive measurement configuration in an RRC release. The WTRU may perform measurements in RRC_INACTIVE. The WTRU may report measurements related to LTM candidate cells during the random access procedure. For example, the WTRU may report measurements related to LTM candidate cells during the random access procedure (e.g., in a medium access control (MAC) control element (CE) with Msg 3 (for a four-step RA) or Msg A (for a two-step RA)). The WTRU may optionally perform early synchronization to a set of best candidate cells. In some implementations, the WTRU may receive indications (e.g., candidate configuration information) of candidate configurations and SCell activation and / or deactivation during the random access procedure. For example, the WTRU may receive an indication of candidate configurations and SCell activation or deactivation during a random access procedure (e.g., during a MAC CE with Msg4 (4-step RA) or Msg B (2-step RA)). In some implementations, the WTRU may perform an LTM procedure upon transitioning to RRC_CONNECTED. For example, the WTRU may apply a stored LTM Primary Cell (PCell) configuration and activate the SCell / SCG immediately upon entering RRC_CONNECTED.

[0005] In some examples, the WTRU may receive configuration information from a cell while the WTRU is in connected mode. The configuration information may indicate multiple LTM candidate cells. The WTRU may receive a measurement configuration while the WTRU is in inactive mode. The WTRU may perform measurements on one or more of the multiple LTM candidate cells while the WTRU is in inactive mode according to the measurement configuration. The WTRU may send a report including these measurements during a random access procedure. The WTRU may receive candidate configuration information for at least one LTM candidate cell of the multiple LTM candidate cells during the random access procedure. The WTRU may perform an LTM procedure for the at least one LTM candidate cell upon transitioning to connected mode.

[0006] In some examples, the WTRU may receive the measurement configuration via a radio resource control (RRC) release message while the WTRU is in an inactive mode. The WTRU may receive candidate configuration information via a medium access control (MAC) control element (CE). The WTRU may perform early synchronization to at least one LTM candidate cell before receiving the candidate configuration information. When the WTRU enters connected mode, it may apply the candidate configuration information of the at least one LTM candidate cell to perform the LTM procedure.

[0007] In some examples, the measurements that the WTRU performs on one or more of the multiple LTM candidate cells may consist of Reference Signal Received Power (RSRP) measurements. The WTRU may transmit a report via the MAC CE that includes the measurements related to the LTM candidate cells.

[0008] In some examples, the configuration information consists of parameters. The WTRU can select one or more LTM candidate cells based on the parameters. Furthermore, the WTRU can include an indication in a report (e.g., the same report including measurements of one or more of the LTM candidates) of the one or more selected LTM candidate cells. The parameters can include an RSRP threshold and / or a reference signal received quality (RSRQ) threshold.

[0009] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which: [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1 is a system diagram of an example communication system in which one or more disclosed aspects may be implemented. [Figure 1B] 1B is a system diagram illustrating an example WTRU (Wireless Transmit / Receive Unit) that may be used within the communication system illustrated in FIG. 1A. [Figure 1C] 1B is a system diagram illustrating an example RAN (Radio Access Network) and an example CN (Core Network) that may be used within the communication system illustrated in FIG. 1A. [Figure 1D] FIG. 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A. [Figure 2] FIG. 1 illustrates an exemplary high-level measurement model. [Figure 3] FIG. 2 illustrates exemplary radio resource control (RRC) states and transitions between RRC states. [Figure 4] FIG. 1 illustrates an exemplary L1 and L2 triggered mobility (LTM) with carrier aggregation (CA). [Figure 5] FIG. 1 illustrates an exemplary LTM baseline procedure. [Figure 6] 10 illustrates an example of using early measurements for fast setup of CA and dual connectivity (DC) when a WTRU switches from an inactive mode (eg, RRC_INACTIVE) to a connected mode (eg, RRC_CONNECTED). [Figure 7] 1 illustrates an example procedure and signaling for fast setup and / or resume. [Figure 8] FIG. 1 illustrates an exemplary procedure for fast setup and / or resume. [Figure 9] A diagram showing example procedures and signaling for LTM candidate maintenance in RRC_INACTIVE. [Figure 10] A diagram illustrating an example procedure for maintaining LTM candidates in RRC_INACTIVE. [Figure 11] A diagram showing example procedures and signaling for LTM early measurement maintenance in RRC_INACTIVE. [Figure 12] A diagram illustrating an example procedure for LTM early measurement maintenance in RRC_INACTIVE. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1A is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as, for example, code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (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 multicarrier (FBMC), etc.

[0012] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed aspects contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of 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, any of the WTRUs 102a, 102b, 102c, 102d may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals, and may include a UE (user equipment), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a PDA (personal digital assistant), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an IoT (Internet of Things) device, a watch or other wearable, an HMD (head mounted display), 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 the context of an industrial and / or automated processing chain), a consumer electronics device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a WTRU.

[0013] Additionally, the communications system 100 may include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications 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 eNodeB, a home Node B, a home eNodeB, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, etc. While the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0014] The base station 114a may be part of the RAN 104 / 113, which may further include other base stations and / or network elements (not shown), such as, for example, a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies and may be referred to as a cell (not shown). The frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services over a particular geographic area, which may be relatively fixed or may change over time. Furthermore, a cell may be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, e.g., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0015] 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., RF (radio frequency), microwave, centimeter wave, micrometer wave, IR (infrared), UV (ultraviolet), visible light, etc.). The air interface 116 may be established using any suitable RAT (radio access technology).

[0016] More specifically, as mentioned above, the communication system 100 may be a multiple-access system and may employ one or more channel access schemes, such as, for example, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. 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 establish the air interface 115 / 116 / 117 using, for example, wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA+ (HSPA+). HSPA may include High-Speed ​​Downlink Packet Access (HSDPA) and / or High-Speed ​​Ultralow-Limit Packet Access (HSUPA).

[0017] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0018] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as, for example, New Radio (NR) radio access, which may establish the air interface 116 using NR.

[0019] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement both LTE radio access and NR radio access, e.g., 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).

[0020] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as, for example, IEEE 802.11 (e.g., Wireless Fidelity (WiFi)), IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GERAN (GSM EDGE), etc.

[0021] 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as, for example, a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as, for example, IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as, for example, 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 shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0022] The RAN 104 / 113 may be in communication with the CN 106 / 115 and may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as, for example, different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as, for example, user authentication. 1A, it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs employing the same RAT or a different RAT than the RAN 104 / 113. For example, the CN 106 / 115, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, may also be in communication with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0023] Additionally, the CN 106 / 115 may serve 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 providing 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, for example, transmission control protocol (TCP), user datagram protocol (UDP), and / or IP in the TCP / IP (internet protocol) Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs that may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0024] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with separate wireless networks over separate wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based radio technology, and with a base station 114b, which may employ an IEEE 802.11 radio technology.

[0025] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, 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 GPS (Global Positioning System) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the above elements without departing from the spirit and scope of the present invention.

[0026] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors along with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any of other types of integrated circuits (ICs), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to a transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0027] The transmit / receive element 122 may be configured to transmit or receive signals to a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0028] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO techniques. 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.

[0029] 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 mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, for example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate according to multiple RATs, such as NR and IEEE 802.11.

[0030] The processor 118 of the WTRU 102 may be coupled to and may receive user input data through 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). Additionally, the processor 118 may output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information and store data in any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. 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 and store data in memory that is not physically located in the WTRU 102, such as in a server or host computer (not shown).

[0031] 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 device suitable for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., NiCd (nickel cadmium), NiZn (nickel zinc), NiMH (nickel metal hydride), Li-ion (lithium ion), etc.), solar cells, fuel cells, etc.

[0032] Additionally, the processor 118 may be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of 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 being received from two or more neighboring base stations. It will be understood that the WTRU 102 may obtain location information through any suitable location-determination method while remaining consistent with an embodiment.

[0033] Additionally, the processor 118 may be coupled to other peripherals 138, which may include one or more software 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 e-compass, a satellite transceiver, a digital camera (for photos and / or videos), a Universal Serial Bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulated (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 a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction 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.

[0034] The WTRU 102 may include a full-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference either by hardware (e.g., a choke) or by signal processing by a processor (e.g., by a separate processor (not shown) or by the processor 118). In an aspect, the WTRU 102 may include a half-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or downlink (e.g., for reception)) may be half-duplex.

[0035] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to an embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. Additionally, the RAN 104 may also be in communication with the CN 106.

[0036] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0037] Each of the eNode-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. As shown in FIG. 1C , the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0038] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the above elements is depicted as part of the CN 106, it will be understood that any of the just-mentioned elements may be owned and / or operated by an entity other than the CN operator.

[0039] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during 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.

[0040] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. In general, the SGW 164 may route and forward user data packets to the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as, for example, anchoring the user plane during inter-eNode B handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0041] The SGW 164 may be connected to a PGW 166 that may provide the WTRUs 102a, 102b, 102c with access to a packet-switched network, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0042] The CN 106 may facilitate communication 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 communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IMS (IP Multimedia Subsystem) server) that serves as an interface between the CN 106 and the PSTN 108. Furthermore, 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.

[0043] Although the WTRU is described in Figures 1A-1D as a wireless terminal, it is expected that in certain exemplary embodiments, such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0044] In an exemplary embodiment, the other network 112 may be a WLAN.

[0045] A WLAN in infrastructure Basic Service Set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and out of the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs within a BSS may be sent through the AP, e.g., a source STA may send traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source and destination STA via a direct link setup (DLS). In one exemplary embodiment, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all STAs) may communicate directly with each other. The IBSS mode of communication is sometimes referred to herein as an "ad-hoc" mode of communication.

[0046] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width that is dynamically set by signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In a typical aspect, CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) may be implemented in an 802.11 system, for example. With CSMA / CA, STAs (e.g., every 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 in a given BSS at any given time.

[0047] For example, a HT (high throughput) STA may use a 40 MHz wide channel for communication by combining a 20 MHz primary channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0048] A Very High Throughput (VHT) STA may support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. A 40 MHz and / or 80 MHz channel may be constructed by combining contiguous 20 MHz channels. A 160 MHz channel may be constructed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may proceed to a segment parser, which may split the data into two streams. IFFT (inverse fast Fourier transform) processing and time-domain processing may be performed on each stream separately. The streams may be mapped onto two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations for the 80+80 configuration described above may be reversed and the combined data may be sent to the MAC (Media Access Control).

[0049] Sub-1 GHz modes of operation are supported by 802.11af and 802.11ah. The operating bandwidths of the channels and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TVWS (TV White Space) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to an exemplary embodiment, 802.11ah may support Meter Type Control / Machine-Type Communication, such as MTC devices in macro coverage areas. MTC devices may have limited capabilities, including support (e.g., only support) for limited and / or limited bandwidths. An MTC device may include a battery with a battery life above a threshold (eg, to maintain a very long battery life).

[0050] A WLAN system that may support multiple channels and channel bandwidths, e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah, includes a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the smallest bandwidth operating mode among all STAs operating in the BSS. In the 802.11ah example, the primary channel may be 1 MHz wide for a STA (e.g., an MTC-type device) that supports (e.g., only supports) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or NAV (Network Allocation Vector) setting may depend on the state of the primary channel. If the primary channel is busy, for example, due to a STA (that only supports a 1 MHz mode of operation) transmitting to the AP, the entire available frequency band may be considered busy even though most of the frequency band may remain idle and available.

[0051] In the United States, the available frequency bands that may be used by 802.11ah are 902 MHz to 928 MHz. In South Korea, the available frequency bands are 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0052] 1D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As mentioned above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. Additionally, the RAN 113 may be in communication with the CN 115.

[0053] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO techniques. For example, the gNBs 180a, 180b may utilize beamforming to transmit and / or receive signals to the gNBs 180a, 180b, and 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit and / or receive wireless signals to the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of the just-mentioned component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0054] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for separate transmissions, separate cells, and / or separate 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 different or scalable lengths (e.g., including different numbers of OFDM symbols and / or different absolute time lengths).

[0055] 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 without accessing another RAN (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize 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 unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as, for example, an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput in serving the WTRUs 102a, 102b, 102c.

[0056] 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 the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0057] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one SMF (Session Management Function) 183a, 183b, and possibly a DN (Data Network) 185a, 185b. While each of the above elements is depicted as part of the CN 115, it will be understood that any of the just-mentioned elements may be owned and / or operated by an entity other than the CN operator.

[0058] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling sessions for separate PDUs with separate requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized by the WTRUs 102a, 102b, 102c. For example, separate network slices may be established for separate use cases, such as services dependent on ultra-reliable, low-latency (URLLC) access, services dependent on enhanced massive mobile broadband (eMBB) access, services related to machine-type communications (MTC) access, etc. The AMF 162 may provide control plane functionality for switching between the RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0059] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. Additionally, the SMFs 183a, 183b may be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions, such as managing and assigning IP addresses for WTRUs, 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.

[0060] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface and may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as, for example, the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184, 184b may perform other functions such as, for example, routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0061] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IMS (IP Multimedia Subsystem) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired 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 DNs (data networks) 185a, 185b through an N3 interface to the UPFs 184a, 184b, and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0062] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein in connection with one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other device(s) described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0063] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or in an operator's network environment. For example, one or more emulation devices may perform one or more, or all, functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communications network to test other devices in the communications network. One or more emulation devices may perform one or more, or all, functions while temporarily implemented / deployed as part of a wired and / or wireless communications network. The emulation device may be directly coupled to another device for testing purposes and / or may perform testing using over-the-air (OTA) wireless communications.

[0064] The one or more emulation devices may perform one or more functions, inclusive, while not implemented / deployed as part of a wired and / or wireless communications network. For example, the emulation devices may be utilized in testing laboratories and / or testing scenarios in undeployed (e.g., testing) wired and / or wireless communications networks to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0065] In particular, the following abbreviations and acronyms are used herein: Acknowledgement (ACK), Block Error Rate (BLER), Bandwidth Part (BWP), Carrier Aggregation (CA), Channel Access Priority (CAP), Channel access priority class (CAPC), Component Carrier (CC), Clear Channel Assessment (CCA), Control Channel Element (CCE), Control Element (CE), Configured Grant or Cell Group (CG), Conditional Handover (CHO), Cyclic Prefix (CP), Conventional OFDM (relying on cyclic prefix) (CP-OFDM), Conditional PsCell addition (CPA), Conditional PsCell addition / change (CPAC), Conditional PsCell change (CPC), Channel Quality Indicator (CQI), Cyclic Redundancy Check (CRC), Channel State Information (CSI), Centralized Unit (CU), Contention Window(CW), Contention Window Size(CWS), Channel Occupancy(CO), Downlink Assignment Index(DAI), Dual Connectivity(DC), Downlink Control Information(DCI), Downlink feedback information(DFI), Dynamic grant(DG), Downlink(DL), Demodulation Reference Signal(DM-RS), Data Radio Bearer(DRB), enhanced Licensed Assisted Access(eLAA), Further enhanced Licensed AssistedAccess (FeLAA), Hybrid Automatic Repeat Request (HARQ), License Assisted Access (LAA), Listen Before Talk (LBT), Long Term Evolution (for example, from 3GPP LTE Release 8 and up) (LTE), Layers 1 and 2 triggered mobility (LTM), Layer 1 (L1), Layer 2 (L2), Negative ACK (NACK), Master cell group (MCG), Medium Access Control (MAC), Modulation and Coding Scheme (MCS), Multiple Input Multiple Output (MIMO), New Radio (NR), Orthogonal Frequency-Division Multiplexing (OFDM), Primary cell (PCell), Physical cell identity (PCI), Physical Layer (PHY), Process ID (PID), Paging Occasion (PO), Physical Random Access Channel (PRACH), Primary SCG Cell (PSCell), Primary Synchronization Signal (PSS), Random Access (or procedure) (RA), Random Access Channel (RACH), Random Access Response (RAR), Radio access network Central Unit (RCU), Radio Front end (RF), Radio Link Control (RLC), Radio Link Failure (RLF), Radio Link Monitoring (RLM), Radio Network Identifier (RNTI), RACH occasion (RO), Radio Resource Control (RRC), Radio Resource Management (RRM), Reference Signal (RS), Reference SignalReceived Power (RSRP), Received Signal Strength Indicator (RSSI), Secondary Cell (SCell), Secondary cell group (SCG), Service Data Unit (SDU), Special Cell (SpCell), Sounding Reference Signal (SRS), Synchronization Signal (SS), Secondary Synchronization Signal (SSS), Switching Gap (in a self-contained Wireless Local Area Networks and related technologies (IEEE 802.xx domain) (WLAN). The SpCell may refer to either a PCell of the MCG or a PSCell of the SCG, depending on whether the MAC entity is associated with an MCG or an SCG.

[0066] In RRC_CONNECTED, the WTRU can measure one or more beams of the cell. The WTRU may average the measurements (e.g., power values) to derive the cell quality. In some cases, the WTRU may be configured to consider a subset of the detected beams. The WTRU can perform filtering at two different levels: deriving beam quality at the physical layer and deriving cell quality from multiple beams at the RRC level. Cell quality from beam measurements is derived equally for serving and non-serving cells. The measurement report can include measurement results for one or more beams (e.g., X best beams) if the WTRU is configured to do so by the gNB. Figure 2 shows an example of a corresponding high-level measurement model.

[0067] In some cases, the WTRU may be configured for RRC connected states and state transitions. In NR, the WTRU is configured in one of three RRC states: RRC_CONNECTED, RRC_INACTIVE, and RRC_IDLE. RRC_CONNECTED is also referred to as "CONNECTED mode." RRC_INACTIVE is sometimes referred to in this document as "INACTIVE mode." RRC_IDLE is also referred to as "IDLE mode." Figure 3 shows an example of different RRC states and the transitions between them.

[0068] In some cases, the WTRU may be configured for inter-cell L1 / L2 triggered mobility (LTM). The WTRU may use inter-cell beam management to manage beams with CA. The WTRU may use mechanisms and procedures related to L1 / L2-based inter-cell mobility for mobility latency reduction. L1 / L2-based inter-cell mobility mechanisms and procedures for mobility latency reduction configuration and maintenance for multiple candidate cells may enable rapid application of configurations to candidate cells. Furthermore, L1 / L2-based inter-cell mobility mechanisms and procedures for mobility latency reduction may determine a dynamic switch mechanism for candidate serving inter-cells, including SpCells and SCells (e.g., for potential application scenarios based on L1 / L2 signaling). Furthermore, L1 / L2-based inter-cell mobility mechanisms and procedures for mobility latency reduction may provide L1 extensions for inter-cell beam management, including L1 measurement and reporting and beam indication. Additionally, L1 / L2-based inter-cell mobility mechanisms and procedures for reducing mobility latency may provide timing advance management. Furthermore, L1 / L2-based inter-cell mobility mechanisms and procedures for reducing mobility latency may provide CU-DU interface signaling to support L1 / L2 mobility, if necessary. Frequency Range 2 (FR2)-specific enhancements are not precluded. Furthermore, in some cases, L1 / L2-based inter-cell mobility procedures may be applicable to one or more of the following scenarios:Does not include standalone, CA, and NR-DC cases where the serving cell changes within one CG, intra-DU cases and intra-DU inter-CU cases (e.g., applicable to standalone and CA and cases where no new RAN interface is expected), both intra-frequency and inter-frequency, both Frequency Range 1 (FR1) and FR2, source cell and target cell are synchronous (e.g., applicable to standalone and CA and cases where no new RAN interface is expected), both intra-frequency and inter-frequency, both Frequency Range 1 (FR1) and FR2, synchronous or asynchronous source cell and target cell, and / or inter-CU cases.

[0069] L1 / L2-based mobility and inter-cell beam management can support intra-DU and intra-frequency scenarios. In the above cases, the serving cell may remain the same (e.g., there is no possibility to change the serving cell using L1 / L2-based mobility). In FR2 deployments, CA may be used to aggregate multiple CCs in one band to utilize available bandwidth. These CCs may be transmitted on the same analog beam pair (e.g., gNB beam and WTRU beam). The WTRU can configure the TCI states for PDCCH and PDSCH reception. There may be a fairly large number of TCI states (e.g., 64). Each TCI state may include an RS or SSB that the WTRU references to configure its beam. The SSB may be associated with a non-serving PCI. MAC signaling (e.g., "WTRU-specific PDCCH MAC CE TCI State Indication") can activate the TCI states for the core set and / or PDCCH. Reception of PDCCH from non-serving cells is supported by the MAC CE indicating the TCI state associated with the non-serving PCI. MAC signaling (e.g., "Activate / Deactivate TCI State for WTRU-Specific PDSCH") can activate a subset of (up to) eight TCI states for PDSCH reception. The DCI indicates the eight TCI states. The WTRU can also support "unified TCI states" with different update mechanisms (e.g., DCI-based), but not multi-TRP. The WTRU can support unified TCI states with multi-TRP.

[0070] The WTRU can use LTM to improve handover latency. In traditional L3 handover or conditional configuration, the WTRU can first send measurement reports using RRC signaling. In response to the measurement transmission, the network can provide further measurement configuration and potentially conditional handover configuration. In traditional handover, the network provides the target cell configuration after the WTRU reports using RRC signaling that the cell meets the configured radio quality criteria. In conditional handover, the network provides the target cell configuration as well as metrics that determine when the WTRU should pre-trigger CHO configuration to reduce handover failure rates due to delays in sending measurement reports or receiving RRC reconfiguration. Both of these L3 methods can suffer from delays associated with sending measurement reports and receiving target configuration, especially in the case of traditional (non-conditional) handover. LTM may enable fast application of candidate cell configurations by dynamically switching between SCells or switching PCells (e.g., switching roles between SCell and PCell) without performing RRC signaling. In the case of inter-CU, this may not be included because the PDCP anchor needs to be relocated, so an RRC-based approach may be required to support inter-CU handover.

[0071] In a conventional L3 handover mechanism, the currently active SCell may be released before the WTRU completes the handover to the target cell within the coverage area of ​​the new site. Active SCells can only be added after a successful handover, resulting in reduced throughput during the handover. Thus, one of the goals of L1 / 2 is to enable immediate CA operation upon a serving cell change.

[0072] FIG. 4 illustrates an example of LTM operation. In FIG. 4, a candidate cell group is configured by RRC, and dynamic switching between the PCell and SCell is achieved using L1 / 2 signaling. FIG. 5 illustrates an example LTM baseline procedure 500. The WTRU sends a Measurement Report message to the gNB at 501. The gNB decides to use LTM and initiates LTM candidate preparation at 502. The gNB sends an RRC Reconfiguration message to the WTRU at 503, including the configuration of one or more LTM candidate target cells. The WTRU stores the configuration of the LTM candidate target cells and sends an RRC Reconfiguration Complete message to the gNB at 504. The WTRU can perform DL synchronization and TA acquisition with the candidate target cells before receiving the LTM cell switch command at 505. In some cases, the WTRU is configured to support DL synchronization with the candidate cell before the SSB-based cell switch command. In some cases, the WTRU is configured to support TA acquisition with the candidate cell before the PDCCH-ordered RACH-based LTM cell switch command. The PDCCH order is triggered by the source cell. At 506, the WTRU may perform L1 measurements on the configured LTM candidate target cell(s) and send lower layer measurement reports to the gNB. In some cases, the WTRU is configured to transmit lower layer measurement reports over L1 or MAC. At 507, the gNB may decide to perform an LTM cell switch to the target cell and send a MAC CE triggering the LTM cell switch. The gNB may send the MAC CE triggering the LTM cell switch by including a candidate configuration index for the target cell. The WTRU switches to the configuration of the LTM candidate target cell. The WTRU may receive a beam indication. At 508, the WTRU may perform a random access procedure towards the target cell if a TA is not available. At 509, the WTRU may indicate successful completion of the LTM cell switch to the target cell.An uplink signal or message after the WTRU switches to the target cell may be used to indicate that the LTM cell switch has been successfully completed.

[0073] In some cases, the WTRU may be configured for NR early measurements. The network can configure the WTRU with carrier aggregation (CA) or / and dual connectivity (DC) to increase per-user data rates (and potentially reliability). CA allows the WTRU to simultaneously transmit and receive data to and from multiple cells of a given gNB operating on different carrier frequencies. Meanwhile, DC allows the WTRU to connect to two serving gNBs, known as the master node (MN) and secondary node (SN). When operating in DC, the WTRU may further be configured with CAs in the MN and / or SN. The set of cells under the MN configured for the WTRU is called the master cell group (MCG), and those under the SN are called the secondary cell group (SCG). The primary cell of the MCG is called the PCell, and the primary cell of the SCG is called the PSCell. The term SPCell (special cell) is used to refer to either the PCell or the PSCell. Cells other than the SPC cells are called SC cells (secondary cells).

[0074] The network may decide to configure CA and / or DC for the WTRU based on measurement reports received from the WTRU for neighboring cells. Note that nothing prevents the network from blindly configuring CA and / or DC (e.g., without receiving measurement reports).

[0075] Early measurement reporting may be used to enable rapid setup of CA and / or DC as soon as the WTRU transitions to RRC_CONNECTED (e.g., IDLE / INACTIVE measurements). The WTRU may be configured to perform neighbor cell measurements while the WTRU is in RRC_INACTIVE or RRC_IDLE. Measurements are performed on intra-frequency, inter-frequency, or inter-RAT neighbor cells. When the WTRU transitions to the RRC_CONNECTED state, the WTRU may send measurements to inform the network if there are any candidate neighbor cells that can be configured in CA or DC mode for the WTRU.

[0076] FIG. 6 shows an example procedure 600 for using early measurements for fast setup of CA / DC when a WTRU switches from RRC_INACTIVE to RRC_CONNECTED, at 600. The WTRU is provided with an early measurement configuration upon transitioning to RRC_INACTIVE, at 601. The WTRU performs measurements while the WTRU is RRC_INACTIVE, at 602. When the WTRU transitions to RRC_CONNECTED mode (e.g., when the WTRU receives a page due to DL data arrival, at 603, or when UL data needs to be transmitted), the WTRU triggers an RRC resume procedure by sending an RRC resume request message, at 604. The network may request the WTRU to send measurements performed during RRC_INACTIVE mode in an RRC Resume message 605, which the WTRU provides in an RRC Resume Complete message 606. Based on the RRC resume complete message 606, the network may immediately configure CA / DC, at 607, if such candidate cells are available. The network sends an RRCReconfiguration message containing the CA / DC configuration at 608, and the WTRU responds with an RRCReconfigurationComplete message at 609 and can start operating with CA / DC. Without early measurements, the configuration of CA / DC could be significantly delayed, as the WTRU would need to configure measurements to be performed after transitioning to RRC_CONNECTED, and the network would need to wait until the WTRU performed these measurements and sent a measurement report before configuring CA / DC. The IDLE / INACTIVE measurement configuration may be provided to the WTRU via a dedicated message (e.g., the measIdleConfig information element (IE) in the RRCRelease message when the WTRU transitions to IDLE / INACTIVE). Additionally or alternatively, the WTRU may obtain the IDLE / INACTIVE measurement configuration from SIB11 (e.g., in the measIdleConfig-SIB IE).

[0077] The measIdleConfig IE may include one or more of a list of NR carrier frequencies to be measured, a list of EUTRA (Evolved Universal mobile telecommunications system Terrestrial Access) (e.g., LTE) frequencies, an idle measurement period, and / or a coverage area.

[0078] A list of NR carrier frequencies may be measured for CA and / or DC candidate NR cells. In some cases, the list of NR carrier frequencies may include additional information, including, but not limited to, one or more of: a list of cells to be measured, the quality to be measured (e.g., RSRP or RSRQ), RSRP / RSRQ thresholds indicating which cells to include in the measurement report, SSB and beam configuration details, etc.

[0079] The list of frequencies for EUTRA (e.g., LTE) may correspond to inter-RAT candidate cells for DC with NR (e.g., EN-DC, NE-DC). The list of EUTRA frequencies may include additional information, including, but not limited to, one or more of a list of cells to be measured, the qualities to be measured (e.g., RSRP and / or RSRQ), RSRP / RSRQ thresholds indicating which cells to include in the measurement report, etc.

[0080] In some examples, the idle measurement duration may be a value ranging from 10 seconds to 300 seconds. The idle measurement may specify the time that the WTRU performs measurements while IDLE / INACTIVE.

[0081] The coverage area may specify a list of frequencies (e.g., optionally cells within those frequencies). If the WTRU reselects to a cell that is not included in this coverage area, the WTRU may stop measurements. In some cases, the coverage area is arbitrary. In such cases, the WTRU may be configured with one or both of a list of NR frequencies and / or a list of EUTRA frequencies.

[0082] For FR2, IDLE / INACTIVE mode measurement results reported during RRC connection setup or after RRC connection resume may be reused to improve SCell and / or SCG setup latency. New measurement requirements for FR2 may be determined so that measurements are taken and reported more quickly, making them "fresher," to account for FR2 radio conditions that are likely to change rapidly due to shorter distances and smaller cell coverage. Additionally, signaling mechanisms may be introduced to enable measurements to be reported earlier. L1 / 2 triggered mobility (LTM) may be used to reduce mobility latency. In some cases, the WTRU may be configured to use early measurement in conjunction with the LTM feature to improve setup time when transitioning from RRC_INACTIVE to RRC_CONNECTED.

[0083] The term "early measurements" may refer to radio quality measurements that the WTRU is configured to perform during RRC_IDLE or RRC_INACTIVE and report during setup or after resumption of an RRC connection.

[0084] The terms "performing LTM" or "performing an LTM procedure" may refer to performing one or more (e.g., all) of the steps described in FIG. 5. In particular, "performing LTM" or "performing an LTM procedure" may refer to performing early synchronization on the DL and / or UL to one or more of the candidate cells, performing L1 measurements and reporting to one or more of the candidate cells, and switching (e.g., performing a handover) between candidate cells. Additionally, "performing LTM" may refer to the WTRU moving or switching between multiple candidate cells during the procedure.

[0085] The one or more candidate cell sets may be a group of one or more RRC configurations corresponding to handover configurations of one or more candidate SpCells and, optionally, SCells. The RRC configurations may be modeled or received as one or more complete RRC reconfiguration messages, one or more cell group configurations, and / or one or more cell configurations. Each of the candidate cell configurations (e.g., candidate configuration information) may include a candidate configuration identifier. Each of the candidate cell groups may include a candidate cell group identifier. If grouping is performed by RRC, switching between different sets of candidate cells may include updating the serving cell index and / or candidate configuration index. In L1, the serving cell index or candidate configuration index may be used. MAC signaling may be used to reference a specific index. For example, a MAC CE triggering a reconfiguration may include a candidate configuration index that notifies the WTRU to perform a reconfiguration on a specific cell.

[0086] One or more candidate cell groups may be configured in RRC as a list or group of candidate cell configurations. The grouping may occur during the initial synchronization or LTM execution phase rather than during the configuration phase. In this way, the candidate cell set can be considered as a group from the perspective of an RRC configuration list or group. Furthermore, the cells selected for early synchronization, L1 measurements, and LTM execution may depend on further grouping of the entire candidate cell list into subsets. In other words, the grouping itself may not be modeled in RRC using candidate configuration identifiers. However, the grouping may be performed as part of the early synchronization or LTM execution procedure.

[0087] As provided herein, LTM candidate configuration may be applied to any type of pre-configured cell information. For example, a WTRU may be configured with one or more conditional reconfigurations, including, but not limited to, conditional handover (CHO), conditional PSCell addition (CPA), and / or conditional PSCell change (CPC). Each such conditional reconfiguration may be valid before and after a cell change, or may be valid for a particular cell.

[0088] The introduction of LTM allows the WTRU to perform inter-cell mobility procedures with lower latency. Pre-configured RRC reconfiguration to a new cell may be triggered by the MAC CE based on L1 measurement reports and may be controlled by the DU instead of the CU. In RRC_CONNECTED, a WTRU configured with LTM can maintain multiple SpCell and SCell configurations even if the SpCell and SCell are not currently active.

[0089] A WTRU transitioning to RRC_INACTIVE to save power may release configurations for conditional reconfigurations (e.g., CHO, CPAC). The transition to RRC_INACTIVE may require an RRC procedure to return to RRC_CONNECTED and / or to (re)setup candidates. LTM candidates may also be released upon transition to RRC_INACTIVE. However, in some embodiments, overhead and latency may be reduced by allowing storage of multiple candidate cells in the RRC_INACTIVE state that are applied upon reconfiguration (handover) triggered by lower layers (e.g., MAC CE).

[0090] Additionally, initial measurement enhancements in FR2 to support faster SCG and SCell setup may introduce new, more challenging measurement requirements in RRC_IDLE and RRC_INACTIVE, which may increase the WTRU's processing requirements and therefore power consumption. Furthermore, in FR2, cell coverage is smaller than, for example, FR1. As a result, a WTRU may be configured with a relatively large number of measurement neighbor cells, which, along with more challenging measurement performance requirements, may contribute significantly to the WTRU's power consumption.

[0091] In some cases, the WTRU may be configured to store some or all of the LTM candidate cell configuration even when the connection is suspended and the WTRU transitions to RRC_INACTIVE. This may enable the WTRU to perform RRC reconfiguration faster upon handover. Additionally or alternatively, the LTM procedure may be able to resume immediately or near-instantly upon resumption of the RRC connection, thereby avoiding the need to perform RRC reconfiguration to reconfigure the candidates. Furthermore, storing the candidate cell configuration in RRC_INACTIVE may enable the use of LTM or LTM-like procedures upon RRC state changes. These procedures may be used to activate RRC reconfiguration based on the stored configuration, to configure the SpCell (e.g., the cell where the connection is resumed), and / or to configure the SCell. This may improve the transition from RRC_INACTIVE to RRC_CONNECTED because only limited RRC messages are required to perform the setup (or resume) and the configuration is already stored. The WTRU processing burden can be limited by maintaining and determining the optimal target configuration during RRC_INACTIVE and / or by considering only candidate configurations associated with the current cell after performing cell reselection in RRC_INACTIVE.

[0092] In the case of fast RRC resumption, storing only the SpCell configuration for the current cell (e.g., LTM) may be sufficient to improve the speed of the transition to RRC_CONNECTED, since the pre-configured RRC configuration for the SpCell (e.g., PCell) can be applied upon RRC connection resumption. In this way, signaling all or part of the configuration in the RRC Resume message can be avoided, since the RRC configuration for the current cell is already stored. In addition to faster PCell setup, multiple target configurations may be stored to enable faster SCG and / or SCell setup. By utilizing initial measurements in combination with storing candidate cell configurations, SCells can be activated very quickly during or after RRC connection resumption, without having to perform a relatively time-consuming RRC reconfiguration procedure to provide the complete configuration after RRC connection resumption to the current cell (SpCell).

[0093] In some cases, the WTRU may be configured to disable and / or remove LTM candidate cells while remaining in the RRC_INACTIVE state. The WTRU may dynamically disable and / or remove one or more LTM candidate configurations while remaining in the RRC_INACTIVE state. In some cases, the WTRU may remove one or more LTM configurations based on the satisfaction of some condition. For example, the candidate configurations are considered valid for a predetermined period of time. In an example, the WTRU may start this period upon transitioning to RRC_INACTIVE (e.g., upon receiving a suspend configuration) and may remove the configurations upon expiration of the period. Upon completion of the period (or some time before expiration), the WTRU may initiate a resumption procedure to indicate that one or more LTM candidate configurations are about to expire.

[0094] In some cases, the WTRU may receive a message from the network during RRC_INACTIVE indicating that one or more LTM configurations are to be deleted and / or removed. In an example, the WTRU may receive a paging message from the network (e.g., in a short message) indicating that keeping LTM candidate cells INACTIVE is disabled and / or that the WTRU should delete one or more (e.g., all) stored candidate configurations. In an example, the WTRU may receive the indication via an alternative DL message (e.g., RAR, Msg4, or Msg B). In an example, the WTRU may receive an indication to delete and / or remove one or more LTM candidates. The WTRU may receive an indication to delete and / or remove one or more LTM candidates via an index that points to a particular LTM candidate configuration.

[0095] In some cases, the WTRU may disable and / or delete one or more LTM candidate configurations based on an indication in the system information. For example, the WTRU may release from one cell (e.g., by receiving an RRC Release message) and perform cell reselection to a new cell. If the system information of the current serving cell indicates that the stored LTM candidate configurations are not supported in the new cell, the WTRU may reselect to another cell or release the stored LTM candidate configurations.

[0096] In some cases, the WTRU may disable and / or remove one or more LTM candidate configurations based on the characteristics of the WTRU. For example, the WTRU may be considered "highly mobile" (e.g., based on a maintained mobility state estimation (MSE) value) and may choose to remove one, a subset, or all of the LTM candidate configurations. Alternatively, the WTRU may be provided with dedicated parameters (e.g., configured in an RRC Release message) that are used to evaluate where the WTRU is in a high-mobility state. In examples, this may be based on WTRU GNSS location information, WTRU sensor data, and / or the number of cell reselections performed within a period of time.

[0097] In some cases, the WTRU may be configured for fast setup / resume (e.g., via early measurements and LTM triggers during the random access procedure). In some cases, the WTRU may be configured to receive a pre-configuration of LTM candidate cells in RRC_CONNECTED. In some cases, the WTRU is configured to receive a measurement configuration in RRC Release. In some cases, the WTRU is configured to perform measurements in RRC_INACTIVE. In some cases, the WTRU is configured to report measurements related to LTM candidate cells during the random access procedure. For example, the WTRU may be configured to report measurements in MAC CE with Msg3 (e.g., 4-step RA) and / or Msg A (e.g., 2-step RA). In some cases, the WTRU may be configured to optionally perform early synchronization to a set of best candidate cells. In some cases, the WTRU may be configured to receive a candidate configuration and an indication of SCell activation and / or deactivation during the random access procedure. For example, the WTRU may be configured to receive a MAC CE indication in Msg4 (e.g., a 4-step RA) or Msg B (e.g., a 2-step RA). In some cases, the WTRU may be configured to perform an LTM procedure upon transitioning to RRC_CONNECTED. For example, the WTRU may be configured to activate the SCell / SCG and apply the stored LTM PCell configuration immediately upon entering RRC_CONNECTED.

[0098] 7 and 8 show example fast setup / resume procedures and signaling at 700 and 800. At 701 and 801, a WTRU may be configured to receive pre-configuration of LTM candidate cells in RRC_CONNECTED. At 707, the WTRU may receive configuration information. The configuration information may include an indication of one or more candidate cells (e.g., SpCells and / or SCells). For example, the WTRU may receive the configuration of one or more candidate cells (e.g., in candidate configuration information) using RRC connection reconfiguration. The WTRU may be configured to store candidate configurations (e.g., candidate cells) that may trigger handover or RRC reconfiguration using lower layer signaling (e.g., MAC CE).

[0099] At 702 and 802, the WTRU may be configured to receive a measurement configuration in an RRC Release. At 708, the WTRU receives a measurement configuration for performing early measurements. In some examples, the measurement configuration may be received in an RRC Reconfiguration message while the WTRU is in a CONNECTED state. Alternatively, the measurement configuration may be received while the WTRU is in an inactive mode. In some examples, the measurement configuration may be received separately in an RRC Release message including a suspend configuration. In some examples, the measurement configuration may be received partially in an SIB. The measurement configuration may include a list of carriers and / or cells on which to perform measurements while in the RRC_INACTIVE state. The measurement configuration may include a coverage area (e.g., a list of cells or carriers on which the WTRU may be camped when the measurements are performed). The measurement configuration may include measurement parameters for determining how the measurements should be performed. The measurement parameters may include, for example, a radio quality threshold for including reports, one or more averaging or filtering parameters, and / or measurement prioritization. In some examples, the radio quality threshold for including reports may be used to report cells if the measurements exceed an RSRP threshold. In some examples, the averaging or filtering parameters may provide an indication of the number of samples to use for measurement averaging. In some examples, the measurement prioritization may provide an indication of which cells to report if more than the maximum number of measurements are allowed to be reported.

[0100] In some cases, the RRC connection release may include one or more of the CSI-RS resource configuration, the CSI-RS reporting configuration, and a beta offset parameter used for PUSCH multiplexing. In some cases, the RRC connection release may be used when the WTRU performs a random access procedure, such as when the WTRU performs CSI-RS reporting when it transmits Msg3 and / or Msg5.

[0101] In 703 and 803, the WTRU may be configured to perform measurements in RRC_INACTIVE. Upon receiving an RRC release, the WTRU stores the access stratum (AS) context information, and after transitioning to RRC_INACTIVE, the WTRU performs measurements according to the received configuration. Optionally, the WTRU may also save LTM candidate cell information and the initial measurement configuration. The WTRU may store the measurement results for later reporting, for example, upon RRC connection resumption. A validity time may be set for the measurement. Optionally, the WTRU may report the measurement if it is valid according to the validity time. For example, the WTRU may discard the measurement after it has expired.

[0102] At 704 and 804, the WTRU may be configured to report configured measurements related to the LTM candidate cells in the MAC CE using Msg3 711 (e.g., for a 4-step RA) or Msg A (e.g., for a 2-step RA), or via small data transmission. The WTRU may be configured to report the stored measurements from 703 during the random access procedure. At 709, the WTRU may indicate that measurements are available by selecting one from a set of configured random access preambles or resources. At 710, the gNB may provide an uplink grant in a random access response (RAR) providing a grant large enough to include some or all of the measurement results. In some cases, the amount of data granted in the RAR determines whether and how many measurement results are included in the uplink message 711. In some cases, the WTRU may transmit the results multiple times if the initial grant is too small. For example, if the initial grant is too small, the WTRU may transmit the results over multiple transmissions via small data transmission methods (e.g., dynamic grants and / or configured grants for subsequent transmissions). In some cases, the WTRU may be pre-configured in the uplink grant to transmit measurement results in Msg A. Depending on the amount of available data provided in the uplink grant received in the RAR, the WTRU may decide which results to transmit. For example, the WTRU may determine that the best N measurements of neighboring cells are to be reported. In some cases, the WTRU may include measurement results in the RAR up to the maximum value allowed in the received uplink grant.

[0103] In some cases, the PDCCH scheduling Msg2 710, RAR, may include an indication (e.g., a 1-bit field) called "Request LTM Measurements." The WTRU may use this indication to decide whether to transmit measurement results. For example, if the field is "1," the WTRU may determine and transmit measurements in Msg3 711 (e.g., in the MAC CE within Msg3 711). In some examples, if the field is "0," the WTRU may decide not to transmit measurements (if any). In some cases, the "LTM Measurement Request" indication may be in the RAR 711. In some cases, the measurement results are included in the MAC CE sent with Msg3 711 or Msg A. In some cases, the measurement results are included in the RRC message or MAC CE, in Msg5 713 (e.g., RRC Resume Complete) or in an RRC message following the connection resumption (e.g., WTRU Information Response).

[0104] In some cases, the WTRU may be configured to provide measurements using CSI reporting (e.g., using UCI). The WTRU may be configured to send measurements in Msg3 711 or Msg5 713 as part of an LTM candidate configuration in an RRC reconfiguration, as part of an early measurement configuration in an RRC release, or using any pre-configured parameters broadcast in the broadcast system information. In some cases, the PDCCH scheduling Msg2 or Msg2 710 may include a pointer (e.g., a bit field) to a PUCCH resource. The WTRU may use the pointer to send the measurements. If one or more PUCCH resources are configured (e.g., in 701 and / or 702), the WTRU may use the pointer to select one of the resources. In some cases, reception of the PDCCH scheduling Msg2 710 and / or Msg2 710 may trigger the WTRU to transmit a PUCCH, in which case the measurements may be in the PUCCH.

[0105] In some cases, the MAC CE sent from the WTRU may include a flag / indicator that may indicate that the state of one or more LTM candidate cells (e.g., SpCell and SCell(s)) is the same or similar (e.g., within a threshold delta RSRP) to the state when the WTRU was suspended. For example, the flag / indicator may indicate to the network that the WTRU can be resumed with the same cell group configuration as before.

[0106] In some cases, the MAC CE sent by the WTRU may be based on an event configured for the WTRU while in the CONNECTED state or in an RRC Release message. For example, the WTRU may include cell indices in the LTM candidate set list that meet certain radio signal level conditions. This event corresponds to the WTRU if a cell index in the LTM candidate set list exceeds a configured RSRP threshold.

[0107] In some cases, the WTRU may send a MAC CE containing measurement-related information for the LTM candidate cells. In some cases, the WTRU may send a detailed L3 measurement report, which may contain information about cells outside the LTM candidate list (e.g., an RRC Resume Complete message).

[0108] In some cases, the WTRU may determine one or more of the following: whether to include a MAC CE containing the measurement results in msg3 711 (e.g., whether to include a MAC CE containing the measurement results in msg3 711 (or msg A), whether to include a MAC CE containing the measurement results in msg5 713, whether to multiplex the measurement results as CSI into PUSCH msg3 711 or msg A, the number of cells or SSB indexes for which the measurement results are reported, an indication of the applicable CSI reporting configuration or aperiodic CSI trigger state, the SSB index or set of CSI-RS resources for which the measurements are provided as a function of the size of the msg3 711 or msg A grant, characteristics of the grant for msg3 711 such as frequency allocation, an indication from a random access response grant or DCI directed to the TC-RNTI, and / or the SSB index associated with the random access opportunity used to transmit the PRACH. In an example, the WTRU may determine whether to include a MAC CE containing the measurement results in msg3 711 (or msg A), whether to include a MAC CE containing the measurement results in msg5 713, whether to multiplex the measurement results as CSI into PUSCH msg3 711 or msg A, the number of cells or SSB indexes for which the measurement results are reported, an indication of the applicable CSI reporting configuration or aperiodic CSI trigger state, characteristics of the grant for msg3 711 such as frequency allocation, a random access response grant or an indication from a DCI directed to the TC-RNTI, and / or the SSB index associated with the random access opportunity used to transmit the PRACH. When determining a function of the grant size, the WTRU may include measurement results if the size of such grant exceeds a predefined or configured threshold. As an example, if the WTRU determines the indication from a random access response grant or from a DCI addressed to the TC-RNTI, the indication may be determined from existing fields. The existing fields may consist of one or more of a time domain resource allocation (TDRA), a modulation and coding scheme (MCS), and / or a transmit power control (TPC). In an example, if the WTRU determines an SSB index, the WTRU may report CSI measurements or MAC-based measurements for this SSB index. In an example, if the WTRU determines an SSB index, the WTRU may determine a set of CSI-RS resources for CSI measurements as resources quasi-co-located with the SSB index.

[0109] In some cases, the configuration for multiplexing CSI reports in msg3 711 or msg A PUSCH may include one or more of the following: multiplexing information (e.g., beta offset and maximum code rate), one or more CSI report configurations, one or more aperiodic CSI trigger states, one or more resource sets for channel measurement (e.g., SSB or CSI-RS resource sets), one or more resource sets for interference measurement (e.g., non-zero power CSI-RS or CSI for interference measurement (CSI-IM)).

[0110] In some cases, the WTRU may be instructed to determine a timing advance for a candidate cell. The WTRU may determine the timing advance by transmitting a random access preamble to the candidate cell. The WTRU may receive a PDCCH order when the WTRU is in an INACTIVE state. The order includes one or more PCIs of the candidate cell, SSBs or CSI-RS associated with the PCI, a preamble index, etc. The timing advance for the candidate cell may be received from the serving cell on the PDSCH.

[0111] In some cases, the WTRU may transmit the same preamble towards the candidate cell that it used in Msg1 709 and may not be indicated the preamble index. The WTRU may determine the random access opportunity from the SSB and / or CSI-RS reported or prepared to be reported as part of the LTM measurements. The WTRU may also use the same PRACH mask index that it used for the PRACH transmission of Msg1. In some cases, the PDCCH scheduling Msg2 710 or Msg2 710 may include instructions for the WTRU to transmit a preamble towards, for example, the candidate cell. The order may be a one-bit indication. The WTRU may reuse one or more RACH parameters used in Msg1 709.

[0112] At 705 and 805, the WTRU may be configured to receive an LTM execution trigger with a candidate configuration and an indication of SCell activation and / or deactivation (e.g., and / or other candidate configuration information). In some solutions, the WTRU may receive the LTM execution trigger in a MAC CE transmitted along with Msg4 712 (e.g., RRC Resume). In some cases, the WTRU may be configured to receive the LTM execution trigger in a DL transmission separate from Msg4 712. For example, the WTRU may be configured to receive the LTM execution trigger in a DL transmission separate from Msg4 712 before or after Msg4 712, or after Msg5 713. In some cases, the LTM trigger may include an index to an SpCell. In some cases, the SpCell may be the cell from which the random access procedure was initiated. In some cases, the LTM execution may include an indication of the SCell to activate.

[0113] At 706 and 806, the WTRU may be configured to perform an LTM procedure (e.g., an LTM PCell configured for the current cell or a new cell with activation of the SCell / SCG). The WTRU may apply the stored configuration according to the indication(s) received in the LTM trigger. This may include the SpCell and / or SCell. In some cases, if the LTM trigger is received before or simultaneously with Msg4 712, the WTRU may apply the configuration before sending Msg5. In some cases, the RRC state may change to RRC_CONNECTED. The WTRU may be configured to send an RRC resume complete (Msg5) using the applied (stored) configuration as indicated at 705 and 805.

[0114] In some cases, the WTRU may be configured for LTM candidate update in RRC_INACTIVE. In some cases, the WTRU may be configured to receive a configuration (e.g., configuration information) of LTM candidate cells from a first cell. In some cases, the WTRU may be configured to determine a first set of LTM candidate cells from the received configuration based on an enabling condition associated with the first cell. In some cases, the WTRU is configured to perform LTM using the first set of candidate cells. In some cases, the WTRU is configured to receive an RRC release and suspend the RRC connection. In some cases, the WTRU may be configured to reselect a second cell and determine a second set of LTM candidate cells from the received configuration. In some cases, the WTRU may be configured to reselect a second cell and determine a second set of LTM candidate cells from the received configuration based on an enabling condition associated with the second cell (e.g., a list of valid cell IDs, an RSRP threshold, etc.). In some cases, the WTRU is configured to resume the RRC connection with the second cell. In some cases, the WTRU is configured to perform LTM using the second set of candidate cells.

[0115] 9 and 10 show example procedures and signaling for maintaining LTM candidates in RRC_INACTIVE at 900 and 1000. At 901 and 1001, a WTRU may be configured to receive configuration information indicating an LTM candidate cell from a first cell. The WTRU may receive configurations for one or more candidate SpCells and / or SCells. For example, the WTRU may receive configuration information indicating one or more candidate SpCells and / or SCells using RRC connection reconfiguration 908. The WTRU may receive configurations for one or more candidate SpCells and / or SCells using RRC connection reconfiguration 908. The WTRU may store candidate configurations that may trigger handover or RRC reconfiguration using lower layer signaling (e.g., MAC CE). The WTRU may receive a configuration providing an association between a particular serving (or camped on) cell and valid configuration candidates (e.g., valid configuration candidates for each selected eligible cell possibility) for the serving (or camped on) cell before releasing to RRC_INACTIVE.

[0116] At 902 and 1002, the WTRU may be configured to determine a first set of LTM candidate cells. From the configured set, the WTRU may determine a subset of LTM candidate cells that are valid for the current serving cell. The WTRU may determine which cells are valid based on the configuration received at 901 or 1001.

[0117] At 903 and 1003, the WTRU may be configured to perform LTM using a first set of candidate cells. Using the first set of candidate cells, the WTRU may perform LTM. The WTRU may perform a cell switch between cells in the first set of candidate cells. In some cases, the WTRU may perform a cell switch between cells in the first set of candidate cells upon receiving one or more MAC CEs indicating a change of SpCell and / or activation or deactivation of an SCell.

[0118] At 904 and 1004, the WTRU may be configured to suspend the RRC connection. Upon receiving an RRC release 909 with a suspend configuration, the WTRU may transition to RRC_INACTIVE and retain the stored LTM candidate configurations configured in 901 (or 1001). The WTRU may receive an indication of which of the candidate configurations to keep or release in the RRC release 909 or as part of the pre-configuration received in 901 or 1001. For example, the RRC release message 909 may include an indication to store the first candidate cell configuration and release the second candidate cell configuration. Additionally or alternatively, as part of the cell (pre-configuration) candidates in 901 (or 1001), the WTRU may receive an indication for each configuration candidate of which cell (e.g., SpCell) within the candidates is valid. Upon receiving the RRC release message 909, the WTRU may determine that the candidate cell configuration for the current SpCell can be released. The current SpCell may be a cell that has received RRC Release 909.

[0119] At 905 and 1005, the WTRU may be configured to select or reselect to a second cell. In RRC_INACTIVE, the WTRU may perform measurements and evaluations for cell reselection. The WTRU may determine that a new (e.g., second) cell is more suitable than the current (e.g., first) cell and perform cell reselection to the second cell. When the WTRU performs cell reselection, the WTRU may obtain system information for the second cell. Additionally, the WTRU may receive a list of neighboring carriers and / or cells. From the list of neighboring carriers and / or cells, the WTRU may determine and update a valid (e.g., in use) candidate set. For example, the WTRU may use a first LTM candidate set while camped on the first cell and a second LTM candidate set after performing reselection to the second cell (e.g., cell1.set1, cell2.set2). This decision may be based on validity conditions. For example, this determination may be based on determining which candidate cell configurations received in 901 or 1001 are also broadcast in the new / second cell system information as neighbor cells. In some cases, an LTM-specific information element (IE) is broadcast to indicate which cells can be considered valid LTM neighbor cells. In some cases, the broadcast information may include certain specific parameters to be applied, including, but not limited to, a measurement report trigger threshold and / or cell associations (e.g., associations in which cells belong to the same group or different groups for reporting). In some cases, the WTRU may review an existing idle mode neighbor list to determine neighbor cells. If the candidate cell appears in the neighbor list, the WTRU may determine that the candidate cell is valid for the second cell. If the candidate cell does not appear in the neighbor list, the WTRU may determine that the candidate cell is invalid for the second cell.

[0120] In some cases, the WTRU may receive an indication as part of a candidate cell configuration at 901 or 1001. The indication may specify valid cells (e.g., camped-on cells or SpCells) among one or more candidate cell configurations. Based on the preconfigured information, the WTRU may determine which candidate cells are valid for the new cell during or after cell reselection.

[0121] In some cases, the WTRU may prioritize cell reselection over cells in the current LTM candidate set. For example, the WTRU may be configured to add a certain offset to measurements of cells belonging to the LTM candidate list when performing cell ranking and / or comparison based on cell reselection. The WTRU may set individual cell reselection priorities for cells belonging to the LTM candidate list. The WTRU may set an offset to apply to the cell reselection priorities of cells belonging to the LTM candidate set.

[0122] In some cases, after performing cell reselection, the WTRU may determine the LTM candidate set to use based on which candidate cell list the WTRU is camped on in the current cell (e.g., the target cell of the cell reselection).

[0123] In some cases, if the WTRU performs cell reselection to a cell that belongs to the current LTM candidate set, the WTRU may maintain the current candidate set.

[0124] In some cases, after performing cell reselection, if the WTRU determines that there are multiple LTM candidate sets corresponding to the selected cell, the WTRU may determine the LTM candidate set to use based on the number of neighboring cells belonging to the LTM candidate set that the WTRU is able to measure. For example, the WTRU may determine the LTM candidate set to use based on the number of neighboring cells that the WTRU is able to measure with a signal level at least better than a set threshold. Furthermore, the WTRU may determine the LTM candidate set to use by selecting the LTM candidate set that has the current camped cell and the closest neighboring cell that the WTRU detects with a good level. At 906 and 1006, the WTRU may be configured to resume the RRC connection for the second cell. When resuming the RRC connection for the second cell, the WTRU may enable LTM using the set of LTM candidates determined at 905 or 1005. In some cases, the new set of candidate cells may be assigned new candidate cell indices. In some cases, the WTRU may be configured to assign new candidate cell indices (e.g., from 0 to 31) to the new set of candidate cells. In some cases, the WTRU may be configured to assign new candidate cell indices to the new set of candidate cells in the order received in the configuration of 901 or 1001.

[0125] At 907 and 1007, the WTRU may be configured to perform LTM using the second set of candidate cells. The WTRU may perform the LTM procedure described herein. For example, the WTRU may perform the LTM procedure by performing one or more (e.g., all) of the steps described in FIG. 5. The WTRU may perform the LTM procedure by one or more of: performing early synchronization on the DL and / or UL to one or more candidate cells; performing L1 measurements and reporting to one or more candidate cells; and / or switching (e.g., performing a handover) between candidate cells.

[0126] In some cases, the WTRU is configured for coverage area RAU update. In some cases, after cell reselection, the WTRU may determine that a cell is not one of the LTM candidate cells. For example, the WTRU may determine that no SpCell configuration is stored for the cell or that no valid target cell candidates are stored. In such a case, the WTRU may initiate RRC Resume and inform the network that the cell is out of LTM coverage. In some cases, the LTM coverage area may be a list of carriers or cells. In some cases, the LTM coverage area may be one or more specific RAN Notification Areas (RNAs). If the newly selected cell does not belong to a coverage area, the WTRU may initiate RRC Resume. The RRC Resume may indicate a new cause value (e.g., out of LTM coverage). The WTRU may send an uplink indication following the RRC Resume, for example, in a WTRU Assistance Information message. The WTRU may release some or all of the configured LTM candidate configuration. After this indication, the WTRU may receive a new LTM candidate set and a new coverage area. The connection may be interrupted again.

[0127] In some cases, once the WTRU determines that it is outside the LTM coverage area, the WTRU may not trigger a resume procedure to update the network that the WTRU is outside the LTM coverage area. Rather, the WTRU may release the LTM configuration and continue to operate in a legacy INACTIVE state. Once the connection is resumed, the WTRU may send an indication that the LTM configuration has been released (e.g., with a new cause value in the resume message, using a specific configured RACH preamble, using a MAC CE multiplexed with the resume message, etc.).

[0128] In some cases, once the WTRU determines that it is outside the LTM-enabled area, the WTRU may not trigger a resume procedure to update the network that the WTRU is outside the LTM-enabled area. The WTRU may retain its LTM configuration but may consider it inactive or inactive (e.g., not perform any LTM-related actions that the WTRU was configured to perform while in INACTIVE state). The WTRU may continue to operate in a legacy INACTIVE state. If the WTRU reselects to a cell that belongs to the LTM candidate set, the WTRU may consider the LTM candidate set to be active and may start performing LTM-related actions that the WTRU was configured to perform while in INACTIVE state.

[0129] In some cases, the WTRU may be configured for LTM early measurement maintenance in RRC_INACTIVE. In some cases, the WTRU may be configured to receive configuration information of pre-configured LTM candidate cells from a first cell (e.g., via RRC reconfiguration). In some cases, the WTRU may be configured to receive an indication (e.g., via an RRC release) to enable measurements of pre-configured LTM candidate cells in RRC_INACTIVE. In some cases, the WTRU may be configured to reselect to a second cell. In some cases, the WTRU may be configured to receive cell-specific information (e.g., current neighbors) from the second cell. In some cases, the WTRU may be configured to determine a subset of cells based on the cell-specific information from the pre-configured LTM candidate cells and the second cell, and perform radio quality measurements on the subset of cells. The WTRU may send an RRC resume request message 910 to the gNB and receive an RRC resume message 911 in response. In some cases, the WTRU may be configured to resume the RRC connection on the second cell and report radio quality measurements corresponding to a subset of the cells to the second cell (eg, in an RRC resume complete message 912).

[0130] 11 and 12 show example procedures and signaling for maintaining LTM early measurements in RRC_INACTIVE. At 1101 and 1201, a WTRU may be configured to receive pre-configuration of LTM candidate cells in RRC_CONNECTED. The WTRU may receive the configuration of one or more candidate cells (e.g., SpCell and / or SCell). For example, the WTRU may receive the configuration of one or more candidate cells using RRC connection reconfiguration 1107. The WTRU stores the candidate configuration (e.g., candidate cells) for which handover or RRC reconfiguration may be triggered using lower layer signaling (e.g., MAC CE).

[0131] At 1102 and 1202, the WTRU may be configured to receive a measurement configuration for an LTM cell in an RRC release 1108. The WTRU may receive the measurement configuration for performing early measurements. In particular, the WTRU may receive the measurement configuration for performing early measurements on an LTM candidate cell. In some cases, the measurement configuration may be received in an RRC reconfiguration message 1107. In other cases, the measurement configuration may be received separately in an RRC release message 1108 containing a suspend configuration. The measurement configuration may include a list of carriers and / or cells on which to perform measurements while in the RRC_INACTIVE state. The measurement configuration may further include a validity area. For example, the validity area may be a list of cells or carriers on which the WTRU may be camped when the measurements are performed. The measurement configuration may further include measurement parameters for determining how the WTRU performs the measurements. The measurement parameters may include, but are not limited to, one or more of a radio quality threshold for including reports, averaging or filtering parameters, and / or measurement prioritization. The WTRU may decide to report a measurement based on a radio quality threshold for including the measurement in the report (e.g., the WTRU may report a cell if the measurement exceeds an RSRP threshold). The WTRU may decide to perform a measurement based on averaging or filtering parameters, including an indication of the number of samples to use in averaging the measurement. The WTRU may decide to report a measurement based on the priority of the measurement for the reporting cell if more than the maximum number of measurements may be reported.

[0132] In some cases, the measurement configuration may indicate that the WTRU should perform measurements on all LTM candidate cells. In other cases, the measurement configuration may indicate that the WTRU should perform measurements on a subset of the LTM candidate cells. The measurement configuration may also include a configuration to measure cells outside the LTM candidate set. In some cases, the measurement configuration may include one or more of the relative priorities for measurements, reporting of different sets of LTM and / or non-LTM candidate cells.

[0133] At 1103 and 1203, the WTRU may be configured to reselect to the second cell. In RRC_INACTIVE, the WTRU may perform measurements and evaluations for cell reselection. In some cases, the WTRU may determine that a new (e.g., second) cell is more suitable than the current (e.g., first) cell and may perform cell reselection to the second cell.

[0134] At 1104 and 1204, the WTRU may be configured to receive cell-specific information (e.g., current neighbors) from the second cell. If the WTRU performs cell reselection, the WTRU may obtain system information of the second cell. The WTRU may receive a list of neighboring carriers and / or cells. In some cases, the neighbor list may be an existing idle mode neighbor cell. In some cases, the neighbor list may be a separate list for determining early measurement neighbors.

[0135] At 1105 and 1205, the WTRU may be configured to determine and measure a subset of LTM cells based on the configuration from the first and second cells. In some cases, the WTRU may determine and update valid (e.g., in use) early measurement values ​​from a list of neighboring carriers and / or cells. For example, the WTRU may use a first set of early measurement candidates while camped on the first cell and a second set of early measurement candidates after performing reselection to the second cell (e.g., Cell 1. Measurement Set 1, Cell 2. Measurement Set 2). This determination may be based on checking whether the measurement configuration received in 1101 or 1201 is also broadcast in the new / second cell system information as a neighbor cell. In some cases, if the cell configured for early measurement appears in the neighbor list, the WTRU may be considered valid for the second cell. In some cases, if the cell configured for early measurement does not appear in the neighbor list, the WTRU may be considered not valid for the second cell.

[0136] Upon determining which new cells are configured for early measurements, the WTRU may perform measurements on those cells according to the associated measurement requirements. In some cases, the set of requirements valid for LTM candidate cells may differ from the set of requirements valid for non-LTM cells. For example, the set of requirements valid for LTM candidate cells may have a higher sampling rate, shorter filtering, and / or a shorter timescale. In some cases, the WTRU may perform different types of measurements on LTM candidate cells and non-LTM candidate cells. For example, the WTRU may perform L1 beam RSRP measurements on LTM candidate cells. In some examples, the WTRU may perform L3 (e.g., L3 filtered) measurements or cell-level RSRP measurements on non-LTM candidate cells. The cell-level RSRP measurements may be, for example, an average of the RSRP of multiple beams. The WTRU may additionally or alternatively be configured to perform different measurement types on different LTM candidate cells. For example, cells belonging to the same DU as the current cell may be configured with one type of measurement, and cells belonging to a different DU from the current cell may be configured with a different type of measurement. The particular cell to which a particular measurement type applies may depend on the configured relationship between that cell and the current cell. For example, LTM and / or non-LTM cells may be configured as a group. If the current cell and the measurement cell belong to the same group, one type of measurement applies; otherwise, a different measurement method applies. Measurements may also depend on the frequency band of the neighboring cell. For example, FR2 carriers may use one set of measurement requirements and FR1 carriers may use another. In some cases, limits may be placed on measurements (e.g., to maximize the number of cells or carriers that are measured, or to maximize the number of cells or carriers from a particular group that are measured).

[0137] In some cases, if a WTRU is configured with LTM and sent to the INACTIVE state, the WTRU may continue to perform early measurements for the entire duration of the INACTIVE state. That is, the WTRU may perform early measurements until the WTRU transitions to the CONNECTED state. Therefore, the WTRU may ignore the measIdleDuration configuration related to early measurements. Alternatively, the WTRU may be explicitly configured with a very long measIdleDuration (e.g., infinite duration), effectively disabling the duration limit.

[0138] In some cases, the WTRU may stop early measurement for a given cell configured for early measurement if the cell does not belong to the LTM candidate set saved according to the legacy measIdleDuration. The WTRU may stop early measurement for a given cell, but may continue early measurement for a given cell configured for early measurement if the cell belongs to the saved LTM candidate set, even after the measIdleDuration has elapsed.

[0139] At 1106 and 1206, the WTRU may be configured to report a subset of measured cells to the second cell. The WTRU can report stored measurements of the subset of cells to the second cell. In some cases, the report may be sent as a MAC CE, for example, with Msg3, Msg5, or another uplink RRC message. In some cases, the report is an RRC message or an extension of an RRC message, including, but not limited to, RRC Restart Request 1110, RRC Restart Complete 1112, and / or WTRU Information Response. As an example, if the WTRU measures LTM candidate cells and non-LTM candidate cells during RRC_INACTIVE and the uplink grant provided to send Msg3 or Msg5 containing the measurement results is not sufficient to include all results, the WTRU may prioritize including LTM candidate cell measurements over non-LTM cell measurements. In an example, a limit specifying the maximum number of measurement results to include can be configured in the reporting configuration. The limit may be configured in reporting configuration as part of step 2. For example, multiple limits may be specified to include X cells belonging to one group and Y cells belonging to another group in a report. In this manner, the specified multiple limits may be used by the gNB to decide whether to configure one CSG or another CSG based on, for example, SCell measurements for each group.

[0140] In some cases, the WTRU is configured for coverage area RAU update. In some examples, after cell reselection, the WTRU may determine that the cell is not one of the LTM candidate cells. In examples, the WTRU may determine that no SpCell configuration is stored for the cell and / or that no valid target cell candidates are stored for the cell. In examples, the WTRU may determine that the WTRU is outside of a configured set of early measurements. For example, the WTRU may determine that the WTRU is outside of an early measurement coverage area. In such a case, the WTRU may initiate RRC Resume and inform the network that the WTRU is out of coverage for LTM early measurements. In some cases, the LTM coverage area may be a list of carriers or cells. In one or more other cases, the LTM coverage area may be specific to one or more RAN Notification Areas (RNAs). If the newly selected cell does not belong to a coverage area, the WTRU may initiate RRC Resume. In some cases, the RRC Resume may indicate a new cause value (e.g., out of LTM coverage). In other cases, the WTRU may send an uplink indication following the RRC Resume, for example in a UE / WTRU Assistance Information message. In some cases, the WTRU may release some or all of the configured LTM candidate set. After this indication, the WTRU may receive a new set of LTM candidates and a new coverage area. In that case, the connection may be suspended again.

[0141] Although features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with the other features and elements. Furthermore, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electrical signals (transmitted over wired or wireless connections) and computer-readable recording media. Examples of computer-readable recording media include, but are not limited to, ROM (described), RAM (random access memory), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, and optical media such as magneto-optical media, e.g., CD-ROM disks and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, a WTRU, a terminal, a base station, an RNC, or any host computer.

Claims

1. 1. A wireless transmit / receive unit (WTRU), comprising: receiving configuration information from a first cell while the WTRU is in a connected mode, the configuration information indicating a plurality of L1 / L2 triggered mobility (LTM) candidate cells; receiving a measurement configuration while the WTRU is in an inactive mode; performing measurements on one or more of the plurality of LTM candidate cells while the WTRU is in the inactive mode according to the measurement configuration; sending a report during a random access procedure including measurements related to one or more of the plurality of LTM candidate cells; receiving candidate configuration information for at least one LTM candidate cell among the plurality of LTM candidate cells during the random access procedure; When the transition to the connected mode is made, an LTM procedure is performed for the at least one LTM candidate cell. A processor configured to 1. A WTRU comprising:

2. 10. The WTRU of claim 1, wherein the configuration information is received via a radio resource control (RRC) message while the WTRU is in the inactive mode.

3. 3. The WTRU of claim 1 or 2, wherein the configuration information is received via a Medium Access Control (MAC) Control Element (CE).

4. The WTRU of claim 1 , wherein the processor is configured to perform early synchronization to the at least one LTM candidate cell before receiving the candidate configuration information.

5. 5. The WTRU of claim 1, wherein the processor is configured, upon entering the connected mode, to apply the candidate configuration information of the at least one LTM candidate cell to perform the LTM procedure.

6. 6. The WTRU of claim 1, wherein the measurements made for the one or more of the plurality of LTM candidate cells include reference signal received power (RSRP) measurements for the one or more of the LTM candidate cells.

7. 7. The WTRU of claim 1, wherein the processor is configured to send the report including the measurements related to the plurality of LTM candidate cells via a medium access control (MAC) control element (CE).

8. The configuration information includes parameters, and the processor: selecting one or more LTM candidate cells from the plurality of LTM candidate cells based on the parameter, and the report including an indication of the one or more selected LTM candidate cells.

8. The WTRU of claim 1, configured to:

9. 10. The WTRU of claim 8, wherein the parameter comprises a reference signal received power (RSRP) threshold or a reference signal received quality (RSRQ) threshold.

10. To perform the LTM procedure for the at least one LTM candidate cell upon transition to the connected mode, the processor: Applying configuration information to a primary cell associated with the at least one LTM candidate cell and activating one or more secondary cells upon entering a connected mode.

10. The WTRU of claim 1, configured to:

11. 1. A method performed by a wireless transmit / receive unit (WTRU), comprising: receiving configuration information from a first cell while the WTRU is in a connected mode, the configuration information indicating a plurality of L1 / L2 triggered mobility (LTM) candidate cells; receiving a measurement configuration while the WTRU is in an inactive mode; performing measurements on one or more of the plurality of LTM candidate cells while the WTRU is in the inactive mode according to the measurement configuration; sending a report during a random access procedure including measurements related to one or more of a plurality of LTM candidate cells; receiving candidate configuration information for at least one LTM candidate cell among the plurality of LTM candidate cells during the random access procedure; performing an LTM procedure for the at least one LTM candidate cell when the WTRU transitions to the connected mode; A method comprising:

12. 12. The method of claim 11, wherein the configuration information is received via a radio resource control (RRC) message while the WTRU is in the inactive mode.

13. 13. The method of claim 11 or 12, wherein the configuration information is received via a Medium Access Control (MAC) Control Element (CE).

14. 14. The method of any one of claims 11 to 13, further comprising early synchronization to the at least one LTM candidate cell before receiving the candidate configuration information.

15. 15. The method of claim 11, further comprising applying the candidate configuration information for the at least one LTM candidate cell to perform the LTM procedure when the WTRU enters the connected mode.

16. 16. The method of any one of claims 11 to 15, wherein the measurements made for the one or more of the plurality of LTM candidate cells include reference signal received power (RSRP) measurements for one or more of the LTM candidate cells.

17. 17. The method of any one of claims 11 to 16, wherein the report including the measurements related to the plurality of LTM candidate cells is sent via a Medium Access Control (MAC) Control Element (CE).

18. the configuration information includes parameters; selecting one or more LTM candidate cells from the plurality of LTM candidate cells based on the parameter, wherein the report includes an indication of the one or more selected LTM candidate cells; 18. The method of any one of claims 11 to 17, further comprising:

19. 20. The method of claim 18, wherein the parameter comprises a reference signal received power (RSRP) threshold or a reference signal received quality (RSRQ) threshold.

20. performing the LTM procedure for the at least one LTM candidate cell when the WTRU transitions to the connected mode; applying configuration information to a primary cell associated with the at least one LTM candidate cell and activating one or more secondary cells when the WTRU enters a connected mode; 20. The method according to any one of claims 11 to 19, comprising:

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