Enabling Layer 1 and Layer 2 Mobility

Abstract

A wireless transmit / receive unit (WTRU) can perform L1 / L2 switching of a primary cell. In one approach, a WTRU configured with configuration information common to multiple candidate cells and separate configuration information specific to each candidate cell can receive an LTM indication for handover (HO) to a particular candidate cell. Upon receiving the LTM indication for HO to a particular candidate cell, the WTRU can retain the common configuration information, release the separate configuration information specific to the serving cell, and / or apply the separate configuration information specific to the target candidate cell.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 410,909, filed September 28, 2022, and U.S. Provisional Patent Application No. 63 / 395,215, filed August 4, 2022. U.S. Provisional Patent Application Nos. 63 / 410,909 and 63 / 395,215 are incorporated herein by reference in their entireties. [Background technology]

[0002] The present disclosure relates generally to devices and methods for mobility mechanisms, and more particularly to enabling Layer 1 and Layer 2 (L1 / L2) mobility.

[0003] Wireless communication systems have expanded and diversified to provide various types of communication services, such as voice or data services. Generally, wireless communication systems are multiple-access systems capable of sharing available system resources (e.g., bandwidth, transmit power) to support communication with multiple users. Examples of multiple-access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and Single Carrier Frequency Division Multiple Access (SC-FDMA) systems. Summary of the Invention

[0004] A wireless transmit / receive unit (WTRU) can perform an L1 / L2 switch of a primary cell via L1 / L2 triggered mobility (LTM). LTM can have low latency during handover (HO), and the WTRU can perform HO based solely on an L1 / L2 indication (e.g., MAC CE), and a secondary cell from the candidate LTM set, or even a non-serving cell, can be promoted to become the new PCell. Therefore, it may be necessary for the WTRU to have proper pre-configuration of all possible target PCells. It may also be necessary for the WTRU to perform subsequent switches from one target PCell to another without requiring RRC reconfiguration.

[0005] A WTRU configured with a common configuration for multiple candidate cells and a specific configuration for each candidate cell may receive an LTM indication for HO to a specific candidate cell. Upon receiving an LTM indication for HO to a specific candidate cell, the WTRU may maintain the common configuration, release the current cell-specific configuration, and / or apply a configuration specific to the target candidate cell.

[0006] The WTRU may receive configuration information related to the LTM. The configuration information related to the LTM may include a candidate cell group configuration. The candidate cell group configuration may include common configuration information for the serving cell and the at least one candidate cell. The configuration information may also include separate configuration information specific to the serving cell and each of the at least one candidate cell. The WTRU may perform communication with the serving cell based on the common configuration information and the serving cell-specific information. The WTRU may receive an LTM command indicating a handover (HO) to a candidate cell of the at least one candidate cell. The WTRU may release the serving cell-specific information, while the WTRU may maintain the common information. Without performing a reconfiguration of the LTM-related configuration information, the WTRU may perform a handover to the candidate cell as the serving cell using the common configuration information and the information specific to the indicated candidate cell of the at least one candidate cell. The WTRU may then send an HO complete message to the network. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1C] 1A is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] 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, according to one embodiment. [Figure 2]FIG. 10 is a sequence flow diagram illustrating an example of a handover procedure. [Figure 3] FIG. 10 is a diagram showing an example of an excerpt of information elements related to RRC reconfiguration. [Figure 4A] FIG. 10 is a diagram illustrating an example of an excerpt of an RRC reconfiguration related information element (IE). [Figure 4B] FIG. 10 is a diagram illustrating an example of an excerpt of an RRC reconfiguration related information element (IE). [Figure 4C] FIG. 10 is a diagram illustrating an example of an excerpt of an RRC reconfiguration related information element (IE). [Figure 5] FIG. 1 is a diagram illustrating an example of a master cell group (MCG) and a secondary cell group (SCG). [Figure 6] FIG. 1 illustrates an example of L1 / L2 inter-cell mobility operation. [Figure 7] FIG. 10 illustrates an exemplary ASN.1 code for capturing exemplary L1 / L2 mobility signaling. [Figure 8] 1 illustrates an example of a WTRU storing configuration until receiving an L1 / L2 message. [Figure 9] 1 illustrates an example of a WTRU storing configuration until receiving an L1 / L2 message. [Figure 10] FIG. 1 is a diagram illustrating an example of an ASN.1 structure. [Figure 11] 10 is a flowchart illustrating a method for a WTRU to perform L1 / L2 switching of a primary cell (PCell) in an optimal manner that may not require RRC reconfiguration for subsequent PCell changes. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. Communications system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. Communications system 100 may enable multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0009] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments 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, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and / or "STA," may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a mobile phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., for remote surgery), an industrial device and application (e.g., a robot and / or other wireless device operating in an industrial and / or automated processing chain context), a consumer electronics device, a device operating on a commercial wireless network and / or an industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0010] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device 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, an NR Node B, a site controller, an access point (AP), a wireless router, etc. Although 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.

[0011] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), 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, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a specific geographic area, which may be relatively fixed or may change over time. A cell may be further 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, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers per sector of the cell, for example, using beamforming to transmit and / or receive signals in desired spatial directions.

[0012] 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 communications link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0013] More specifically, as noted above, the communications system 100 may be a multiple-access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114 a and the WTRUs 102 a, 102 b, 102 c in the RAN 104 / 113 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 wideband CDMA (WCDMA). WCDMA may include communications protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0014] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0015] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access, which may establish the air interface 116 using NR technology.

[0016] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement 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).

[0017] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0018] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wired local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). 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 need to access the Internet 110 through the CN 106 / 115.

[0019] The RAN 104 / 113 may communicate with the CN 106 / 115, which 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 different throughput, latency, error tolerance, reliability, data throughput, and mobility requirements. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs employing the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0020] The CN 106 / 115 may also 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, which use common communication protocols such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP 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, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0021] 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 different wireless networks over different wireless links.) For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based wireless technology, and a base station 114b, which may employ an IEEE 802.2 wireless technology.

[0022] 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 global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0023] 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 associated with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. 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.

[0024] The transmit / receive element 122 may be configured to transmit or receive signals to or from 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 one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR signals, UV signals, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals 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.

[0025] 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 technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0026] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0027] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, the processor 118 may access information from and store data in any type of suitable 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, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0028] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0029] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0030] The processor 118 may further 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 electronic 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.

[0031] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals associated with a particular subframe (e.g., 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 for reducing and or substantially eliminating self-interference either through hardware (e.g., chokes) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of either 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)).

[0032] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As noted above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0033] The RAN 104 may include eNodeBs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 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 an embodiment, the eNodeBs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0034] Each of the eNodeBs 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 eNodeBs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0035] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0036] The MME 162 may be connected to each of the eNodeBs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function 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.

[0037] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during inter-eNodeB handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0038] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0039] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional landline communications devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. Additionally, 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.

[0040] Although the WTRU is illustrated in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may use a wired communication interface (e.g., temporarily or permanently) with a communication network.

[0041] In a representative embodiment, the other network 112 may be a WLAN.

[0042] A WLAN in infrastructure Basic Service Set (BSS) mode may have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access to or interface with a Distribution System (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating from outside the BSS to a STA 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 to be delivered to the respective destination. Traffic between STAs within a BSS may be sent through the AP, for example, where a source STA may send traffic to the AP, and the AP 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 STA and a destination STA using a direct link setup (DLS). In certain representative embodiments, 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 of the STAs) may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad hoc" communication mode.

[0043] 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 configured via 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 certain representative embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If a particular STA senses / detects and / or determines that the primary channel is busy, the particular STA may back off. One STA (e.g., only one station) may transmit in a given BSS at any given time.

[0044] High Throughput (HT) STAs may use 40 MHz wide channels for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0045] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be sent to Medium Access Control (MAC).

[0046] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths 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 the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter-type control / machine-type communications, such as MTC devices, within a macro coverage area. MTC devices may have limited capabilities, including, for example, support for (e.g., only support for) certain specific and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0047] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be configured and / or limited by the STAs among all STAs operating in the BSS that support the minimum bandwidth operating mode. In an 802.11ah example, the primary channel can be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) 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 Network Allocation Vector (NAV) configuration can depend on the status of the primary channel. For example, if the primary channel is busy due to a STA (that only supports 1 MHz operating mode) transmitting to the AP, the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and be available for use.

[0048] In the United States, the available frequency band that can be used by 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0049] 1D is a system diagram illustrating the RAN 113 and the CN 115, according to one 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. The RAN 113 may also communicate with the CN 115.

[0050] 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 an embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNB 180a, 180b may transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c using beamforming. Thus, the gNB 180a may transmit wireless signals to and / or receive wireless signals from the WTRU 102a using, for example, multiple antennas. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0051] 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 different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0052] 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., eNodeBs 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 an eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0053] 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.

[0054] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements is shown as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] 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 function 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 different PDU sessions with different 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 the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0056] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also 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 allocating 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.

[0057] 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, thereby providing the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0058] 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 IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0059] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to 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 simulate network and / or WTRU functions.

[0060] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or an operator 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 devices may be directly coupled to another device for testing purposes and / or may perform testing using terrestrial wireless communications.

[0061] One or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communications network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communications network to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, e.g., one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0062] Methods and devices that may implement carrier aggregation (CA) are described herein. CA may enable simultaneous transmission or reception on multiple component carriers, while other methods and devices that are not capable of CA may access one of the component carriers. Each node (e.g., Node B, eNB, gNB, etc.) may serve multiple cells. The cells may be collectively referred to as serving cells. The serving cells served by a node may be referred to as a cell group. The serving cells within a cell group may be divided into a primary cell (PCell) and one or more secondary cells (SCells). In one example, the PCell may operate on a primary frequency on which a WTRU may perform an initial connection establishment procedure. After the initial connection to the PCell, one or more SCells may be configured and / or added. The SCells may be activated or deactivated to meet fluctuations in demand for communication with the network (e.g., UL / DL throughput required by the WTRU, available network resources, etc.).

[0063] During dual connectivity (DC), a WTRU may be connected to multiple nodes. For example, the WTRU may be connected to a master node and one or more secondary nodes. Each of the master node and secondary nodes may serve multiple cells. The master node may serve a cell group that may be referred to as a master cell group (MCG). The secondary node may serve a cell group that may be referred to as a secondary cell group (SCG). The primary cell for the master cell group may be referred to as a PCell (e.g., when DC is configured), and the primary cell for the secondary cell group may be referred to as a primary secondary cell (PSCell).

[0064] The term special cell (SpCell) can refer to either a PCell of an MCG or a PSCell of an SCG. There is one Medium Access Control (MAC) entity associated with the MCG and another MAC entity associated with the SCG.

[0065] In one embodiment, the WTRU may receive a Radio Resource Control (RRC) reconfiguration, which may include an SpCell configuration that may be associated with each SCell or an SCell configuration associated with each SpCell. The WTRU may perform one or more of the following actions: In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may release the current SpCell configuration (e.g., the current SpCell is associated with cell a). In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may release the current SCell configuration (e.g., the current SCell is associated with cell b). In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may apply an SpCell configuration associated with another cell (e.g., cell b). In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may apply an SCell configuration associated with another cell (e.g., cell a). In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may reset an RLF counter and / or stop one or more (or, e.g., any) running RLF timers for the SpCell. In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may determine the SCell state of cell a (e.g., based on signal levels, preconfigured behavior, based on instructions received in the L1 / L2 indication, etc.).In one example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell can be cell a), the WTRU may send an indication to the network indicating successful completion of the L1 / L2 mobility and / or including additional information (e.g., selected SCell status of the old SpCell, measurement results of serving / candidate cells, etc.) In addition, the non-serving cell may become the new PCell and / or SpCell.

[0066] In one embodiment, the WTRU may receive an RRC reconfiguration that includes an L1 / L2 mobility candidate cell list configuration and / or that includes cells other than the current SpCell and Scell. In one example, the configuration may include an SpCell configuration and / or an SCell configuration, which may be associated with one or more, or each, candidate cell. The WTRU may perform one or more of the following actions: In one example, upon receiving an L1 / L2 mobility set indication that includes a candidate cell, the WTRU may apply the SCell configuration associated with the candidate cell if the candidate cell indicates that it can be an SCell. In one example, upon receiving an L1 / L2 mobility set indication that includes a candidate cell, the WTRU may apply the SpCell configuration associated with the candidate cell if the candidate cell indicates that it can be an SpCell.

[0067] In one embodiment, the WTRU may receive an RRC reconfiguration that includes an L1 / L2 mobility candidate cell group list configuration and that includes cells other than the current SpCell and SCell. In one example, the configuration may include an SpCell configuration and / or an SCell configuration that may be associated with one or more, or each, candidate cell. In one example, upon receiving an L1 / L2 mobility set indication that includes candidates, the WTRU may apply the cell group configuration that includes any associated SpCell and SCell configurations.

[0068] 2 illustrates an example handover procedure 200. For example, as shown in FIG. 2, at 212, the WTRU 202 may transmit data to and / or receive data from the source gNodeB (gNB) 204. The data may be transmitted to and / or received from the User Plane Function (UPF) 210. At 214, the Access and Mobility Management Function (AMF) may manage connection and mobility tasks for the WTRU between the source gNodeB 204 and the target gNB 206 by providing mobility control information. The WTRU 202 context in the source gNodeB (gNB) 204 may include information regarding roaming and / or access restrictions, which may be provided (e.g., at connection establishment and / or the last Timing Advance (TA) update). For example, at 216, the WTRU 202 may perform measurements and reporting. The source gNB 204 may configure the WTRU with the measurement configuration, and / or the WTRU 202 may report according to a reporting trigger condition indicated in the measurement configuration. At 218, the source gNB 204 may decide to handover the WTRU 202 (e.g., based on the received measurement report). At 220, the source gNB 204 may issue a handover request message to the target gNB 206, which may be passing a transparent RRC container with information to prepare the handover on the target side. In one example, the information may include a target cell ID, a security key for the gNB (key for the gNB, KgNB *The information may include the WTRU's 202 RAT, the cell radio network identifier (C-RNTI) of the WTRU 202 in the source gNB 204, radio resource management (RRM) configuration including WTRU inactivity time, access stratum configuration (AS configuration) including antenna information and downlink (DL) carrier frequency, current quality of service (QoS) flow-to-data radio bearer (DRB) mapping rules applied to the WTRU, system information block 1 (SIB1) from the source gNB, WTRU capabilities for different RATs, and packet data unit (PDU) session-related information. In one example, the information may include WTRU-reported measurement information, including, for example, beam-related information, if available.

[0069] At 222, admission control may be performed by the target gNB 206. For example, at 224, if the WTRU 202 is admitted, the target gNB 206 may prepare the resources needed for the WTRU 202 and may send a handover request acknowledgement to the source gNB 204, which may include a transparent container that is sent as an RRC message to the WTRU to perform the handover.

[0070] At 226, the source gNB 204 may initiate a RAN handover procedure. For example, the source gNB 204 may trigger the handover by sending an RRC reconfiguration message to the WTRU 202, which may include information used to access the target cell. In one example, the information used to access the target cell may include a target cell ID, an updated C-RNTI, and a target gNB 206 security algorithm identifier for the selected security algorithm. In another example, the information used to access the target cell may include a set of dedicated RACH resources, an association between the RACH resources and SSB(s), an association between the RACH resources and WTRU-specific CSI-RS configuration(s), common RACH resources, and system information of the target cell, etc. As an example, if a dual active protocol stack (DAPS) is configured, the source connection may be maintained after a handover (HO) command is sent. In another example, there may be no UL or DL ​​communication between the WTRU and the source gNB 204 after the HO command is sent. At 228, the source gNB 204 may deliver the buffered data and / or new data from the UPF(s) 210 to the WTRU 202. At 230, the WTRU 202 may detach from the previous cell and synchronize to the next cell.

[0071] The source gNB 204 may send an Early Status Transfer message at 232. For example, the source gNB 204 may send the Early Status Transfer message when a DAPS handover is performed. At 234, the source gNB 204 may send an SN STATUS TRANSFER message to the target gNB 206 to convey uplink PDCP (Packet Data Convergence Protocol) SN receiver status and / or downlink PDCP SN transmitter status of DRBs for which PDCP status preservation may apply (e.g., in the case of RLC AM). Data sent to the source gNB 204 at 212a may be redirected to the target gNB 206 and buffered at 236 for transmission to the WTRU 202. At 238, the WTRU 202 may perform RAN handover completion. The WTRU 202 may synchronize to the target cell and / or complete the RRC handover procedure by sending an RRC reconfiguration complete message to the target gNB 206. The target gNB 205 may send a handover success message to the source gNB 204 at 240. The source gNB 204 may send an SN status transfer message to the target gNB at 242. The data sent to the source gNB 204 at 212b may be redirected to the target gNB 206 and buffered at 236 for transmission to the WTRU 202. At 212c, the WTRU 202 may send uplink data to the target gNB 206 and / or receive buffered data from the target gNB 204. The uplink data may be sent to the UPF 210. At 244, the target gNB 206 may send a path switch request message to the AMF 208 to trigger the 5GC to switch the DL data path toward the target gNB 206 and / or establish an NG-C interface instance toward the target gNB 206. At 246, the 5GC may switch the DL data path toward the target gNB 206.In one example, the UPF 210 may send one or more "end marker" packets 248 on the old path to the source gNB 204 for each PDU session / tunnel and may then release any U-plane / TNL resources toward the source gNB 204. At 250, the AMF 208 may acknowledge the path switch request message with a path switch request acknowledge message. At 252, upon receiving the path switch request acknowledge message from the AMF 208, the target gNB 206 may send a WTRU context release to notify the source gNB 204 about the successful handover. In one example, the source gNB 204 may then release radio and / or C-plane related resources associated with the WTRU context. In one example, any ongoing data transfer may continue.

[0072] A message may be received by the WTRU that may include configuration information related to L1 / L2 triggered mobility (LTM). The configuration information related to LTM may be received via a medium access control element (MAC EE), a physical layer downlink control information (PHY DCI), or one or more radio resource control (RRC) configuration / reconfiguration messages. The configuration information related to LTM may include a candidate cell group configuration. The candidate cell group configuration may include common configuration information for the serving cell and at least one candidate cell, and / or separate configuration information specific to the serving cell and each of the at least one candidate cell. For example, the candidate cell group configuration may be applied as a master cell group (MCG) or a secondary cell group (SCG). In another example, the candidate cell group configuration may replace a preconfigured MCG configuration or a preconfigured SCG configuration.

[0073] The WTRU may perform communication with the serving cell based on common configuration information and serving cell-specific configuration information. The WTRU may further receive an LTM command indicating a handover (HO) to a candidate cell of the at least one candidate cell. For example, the received configuration information related to the LTM may be received via a medium access control element (MAC EE), a physical layer downlink control information (PHY DCI), or one or more radio resource control (RRC) reconfigurations. The LTM command may include an existing index list. The existing index list may configure each candidate cell of the at least one candidate cell with an index value. The LTM command may include a unique index. The unique index may be assigned to the candidate cell of the at least one candidate cell.

[0074] The WTRU may further release information specific to the serving cell. The WTRU may perform a handover to the candidate cell as the serving cell using the common configuration information and information specific to the indicated candidate cell of the at least one candidate cell without performing a reconfiguration of the configuration information related to the LTM. For example, the handover may be performed without performing a separate RRC configuration / reconfiguration via an RRC configuration message and without performing a reconfiguration of the configuration information related to the LTM. The handover to the candidate cell as the serving cell may be based on, for example, a delta configuration. The delta configuration may include a change in at least one parameter in the configuration information related to the LTM. For example, the delta configuration may include a change in one parameter in the configuration information related to the LTM.

[0075] The WTRU may apply common configuration information to the at least one candidate cell. The WTRU may further apply separate configuration information specific to an indicated candidate cell of the at least one candidate cell.

[0076] 3 is a diagram illustrating an example of configuration information and excerpts of information elements for an RRC Reconfiguration message. In one example, a handover (HO) command may be an RRC Reconfiguration message including a reconfigurationWithSync. As described herein, the RRC Reconfiguration message may be sent to the WTRU during handover initiation. The RRC Reconfiguration message may include information used to access the target cell. The RRC Reconfiguration message may include an RRC Reconfiguration information element 302. The RRC Reconfiguration information element 302 may include a secondaryCellGroup configuration parameter 304. The secondaryCellGroup configuration parameter 304 may include a CellGroupConfig parameter 402a. As shown at 306, the secondaryCellGroup configuration parameter 304 may be included provided that an SCG is configured or enabled during dual connectivity.

[0077] The RRCReconfiguration information element 302 may include additional information elements. For example, the RRCReconfiguration information element 302 may include an RRCReconfiguration information element 308. The RRCReconfiguration information element 308 may include a masterCellGroup configuration parameter 310. The masterCellGroup configuration parameter 310 may include a CellGroupConfig parameter 402b. The masterCellGroup configuration parameter 310 may be included in each RRCReconfiguration message that includes an MCG, as shown in

[0078] 4A-4C show examples of additional excerpts of configuration information and information elements related to the RRCReconfiguration message. Figures 4B and 4C are continuations of the example excerpt shown in Figure 4A. As shown in Figure 3, the RRCReconfiguration message may include a cell group configuration or CellGroupConfig 402 (e.g., masterCellGroup 310 CellGroupConfig 402b, and possibly secondaryCellGroup 304 CellGroupConfig 402a if dual connectivity (DC) is configured).

[0079] For example, CellGroupConfig 402 may include a cellGroupId parameter 404, a MAC-CellGroupConfig parameter 406, a PhysicalCellGroupConfig parameter 408, and / or an SpCellConfig parameter 410. MAC-CellGroupConfig may include configuration of MAC layer and / or protocol parameters for a particular cell group. For example, the particular cell group may be an MCG and / or SCG. Similarly, PhysicalCellGroupConfig may include configuration of MAC layer and / or protocol parameters for a particular cell group. SpCellConfig 410 may include a servCellIndex parameter 412 and / or a reconfigurationWithSync parameter 416. ServCellIndex parameter 412 may include a servCellIndex parameter 414. ReconfigurationWithSync parameter 416 may include a ReconfigurationWithSync parameter 418. ReconfigurationWithSync parameter 416 may be included provided that ReconfWithSync is configured or enabled during dual connectivity, as shown at 420.

[0080] The ReconfigurationWithSync parameter 418a may include an spCellConfigCommon parameter 422. The spCellConfigCommon parameter 422 may include a ServingCellConfigCommon parameter 424. The SCellConfig 426 may include an sCellConfigCommon parameter 428 and / or an sCellConfigDedicated parameter 430. The sCellConfigCommon parameter 428 may include a ServingCellConfigCommon parameter 424a. The sCellConfigDedicated parameter 430 may include a ServingCellConfig parameter 432.

[0081] 5 illustrates an example of a master cell group (MCG) 502a and a secondary cell group (SCG) 502b. The cell group configuration may include the configuration of each of the cells (e.g., cells operating in carrier aggregation (CA)) that belong to the cell group. The cells, collectively known as serving cells, may be divided into primary cells 504a, 504b and secondary cells 506a, 506b. In one example, the primary cells 504a, 504b may be operating on a primary frequency on which a WTRU performs an initial connection establishment procedure. In one example, the primary cells 504a, 504b may be operating on a primary frequency on which a WTRU initiates a connection re-establishment procedure. In one example, the primary cells 504a, 504b may be operating on a primary frequency, and the WTRU is the cell designated as the primary cell 504a, 504b in a handover procedure. In one example, the primary cell 504a for the master cell group 502a may be referred to as a PCell, and the primary cell 504b for the secondary cell group 502b (e.g., when DC is configured) may be referred to as a PSCell (primary secondary cell). The term special cell (SpCell) 508 may refer to the PCell 504a and / or the PSCell 504b. In one example, the SCells 506a, 506b may be cells providing other carriers used during carrier aggregation for the corresponding cell group.

[0082] Many operations, such as radio link monitoring (RLM) and related Radio Link Failure (RLF) detection and recovery, may be associated with the primary cell. For example, operations may be associated with only the primary cell. Each serving cell may be identified by a servCellIndex (serving cell index) that ranges from 0 to 31. In one example, a PCell may be assigned a servCellIndex value of 0. In another example, a PCell may always be assigned a servCellIndex value of 0.

[0083] Inter-cell L1 / 2 mobility can manage beams in the case of CA. However, in one example, cell change and / or addition may not be supported. In one embodiment, one or more mechanisms and / or procedures for L1 / L2-based inter-cell mobility for mobility latency reduction may be specified. For example, to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction, configuration and / or maintenance for multiple candidate cells may be performed to enable fast application of configuration for candidate cells (e.g., in RAN2, RAN3, etc.). For example, to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction, a dynamic switching mechanism between candidate cells as serving cells (e.g., including SpCells and SCells) for potentially applicable scenarios may be based on L1 / L2 signaling (e.g., in RAN2, RAN1, etc.). For example, L1 extensions for inter-cell beam management, including, for example, L1 measurement and reporting and / or beam direction (e.g., in RAN1, RAN2, etc.), may be performed to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction. In one example, early RAN2 involvement may be performed (e.g., may be required), which includes the possibility of further clarifying the interaction between L1 extensions for inter-cell beam management and dynamic switching mechanisms between candidate cells as serving cells. For example, timing advance (TA) management may be performed (e.g., in RAN1, RAN2, etc.) to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction.

[0084] To support L1 / L2 mobility, central unit-distributed unit (CU-DU) interface signaling may be performed (e.g., in RAN3) to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction. In one example, FR2-specific extensions may not be excluded.

[0085] The L1 / L2 based inter-cell mobility procedure may be applicable to one or more of the following scenarios: standalone, carrier aggregation (CA) and new radio dual connectivity (NR-DC) with serving cell change within one cell group (CG); intra-DU case and intra-CU inter-DU case (e.g. applicable to standalone and CA when no new RAN interface is expected); both intra-frequency and inter-frequency, both FR1 and FR2; source and target cells may be synchronous or asynchronous, and may not include the inter-CU case.

[0086] Inter-cell beam management may address intra-DU and / or intra-frequency scenarios. In one example, the serving cell may remain unchanged (e.g., there may be no possibility to change the serving cell using L1 / 2-based mobility). In FR2 deployments, CA may be used to utilize available bandwidth, for example, to aggregate multiple CCs in one band. These component carriers (CCs) may be transmitted using the same analog beam pair (gNB beam and WTRU beam). The WTRU may be configured with TCI states (e.g., may have a fairly large number, e.g., 64) for reception of the PDCCH and / or PDSCH. 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., a TCI state indication for a WTRU-specific PDCCH MAC CE) may activate the TCI state for the Coreset / PDCCH. Reception of PDCCH from non-serving cells may be supported by the MAC CE indicating the TCI state associated with the non-serving PCI. MAC signaling (e.g., TCI state activation / deactivation for WTRU-specific PDSCH) may activate a subset of the TCI states for PDSCH reception (e.g., up to eight TCI states for PDSCH reception). The DCI may indicate the TCI state (e.g., any of the eight TCI states). There may be a "unified TCI state" with a different update mechanism (DCI-based) but not with multi-TRP. There may be a unified TCI state with multi-TRP.

[0087] The overall objective of L1 / L2 inter-cell mobility may be to improve handover latency. In traditional or conditional L3 handover, the WTRU may first send a measurement report using RRC signaling. In response to the measurement report, the network may provide further measurement configuration and / or conditional handover configuration. In traditional handover, the network may provide a configuration for the target cell after the WTRU reports using RRC signaling that the cell meets the configured radio quality criteria. In conditional handover, to reduce handover failure rates due to delays in sending measurement reports and then receiving RRC reconfiguration, the network provides the target cell configuration in advance, as well as metrics that determine when the WTRU can trigger CHO configuration. Both of these L3 methods may experience a certain amount of delay, especially, for example, in the case of traditional (non-conditional) handover, due to the sending of measurement reports and receiving the target configuration. In particular, for example, L1 / L2-based inter-cell mobility may aim to enable fast application of configurations for candidate cells, including, for example, dynamic switching between SCell and PCell (e.g., switching roles between SCell and PCell) without performing RRC signaling. The inter-CU case may require PDCP anchor relocation and may not be included in the R18 work, as it may have already been excluded from the work items. Therefore, an RRC-based approach may be required to support inter-CU handover. One of the aims of L1 / L2 may be to enable CA operation to be instantly enabled upon serving cell change.

[0088] Figure 6 illustrates an example of L1 / L2 inter-cell mobility operation. For example, candidate cell groups may be configured by RRC, and dynamic switching between PCells and SCells may be achieved using L1 / L2 signaling. As mentioned above, functionality may be introduced to perform HO via L1 / L2 signaling within a given mobility set (e.g., within a subset of cells of a given gNB), where the SCell may become the new PCell. As shown in the structure of the RRC reconfiguration message and the related structures discussed previously, the SpCell (e.g., PCell or PSCell) may require separate configuration compared to the SCell, as there may be some functionality and WTRU behavior that may be related to (e.g., only) the SpCell. Because configuration of only one sPCell per cell group may be allowed, L1 / L2 switching from the SCell to the PCell may not be possible with the current RRC signaling structure.

[0089] The L1 / L2 mobility signaling may include an indication as to which SCell can be promoted to a PCell. However, the solution and related configurations / signaling may also be applicable to cases where a non-serving neighbor cell can be promoted as a PCell. For example, in the following description, unless otherwise specified, it may be assumed that the previous PCell is demoted to become an SCell upon reception of L1 / L2 mobility signaling promoting the SCell to a PCell. In one example, in the following description, L1 / L2 signaling may refer to MAC CE or DCI. An SpCell configuration may be used for the SCell. In one example, for each SCell, the WTRU may be configured with an associated sPCellConfig. The WTRU may store this configuration without applying it.

[0090] For example, in step 610, the RRC may initially configure cells 602, 604, 606, and 608 as candidate cells. The RRC may also initially activate cell 602 as a PCell and cell 604 as an SCell. In steps 612 and 614, dynamic switching of the SCell between cell 604 and cell 606 may be initiated (e.g., via L1 / L2 signaling). For example, in step 612, the SCell may be cell 606. In another example, in step 614, the SCell may be cell 604. In step 616, L1 / L2 signaling may dynamically switch the PCell to cell 604 and the SCell to cell 608 to terminate the L1 / L2 inter-cell mobility operation.

[0091] 7 illustrates an example ASN.1 code for capturing example L1 / L2 mobility signaling. In an example, a WTRU may be configured with an SCellConfig associated with an SpCell (e.g., per cell group). The WTRU may store this configuration but may not apply it until, for example, the WTRU receives an L1 / L2 message indicating that the corresponding SpCell may now be demoted to become an SCell.

[0092] The SCellConfig 426a may include an sCellConfigCommon parameter 428a, an sCellConfigDedicated parameter 430a, and / or an sCellSpCellConfig parameter 702. The sCellConfigCommon parameter 428a may include a ServingCellConfigCommon parameter 424b. The sCellConfigDedicated parameter 430a may include a ServingCellConfig parameter 432a. The sCellSpCellConfig parameter 702 may include an SpCellConfig parameter 704. The sCellSpCellConfig parameter 702 may be included provided that an L1_L2_mobility_SCell is configured or enabled during dual connectivity, as shown at 706. If the sCellSpCellConfig parameter 702 is present, it may include parameters to be used for this SCell if the WTRU receives an L1 / L2 mobility indication promoting this SCell to an SpCell. L1_L2_mobility_SCell may optionally be present if this SCell is part of an L1 / L2 mobility set group and can be promoted to an SCell upon receipt of such an L1 / L2 indication from the network.

[0093] 8 shows an example of a WTRU storing a configuration until receiving an L1 / L2 message. In one example, an IE (eg, spCellSCellConfig) may be added to the SpCellConfig IE.

[0094] The SpCellConfig 410a may include a servCellIndex parameter 412a, a reconfigurationWithSync parameter 416a, and / or an spCellSCellConfig parameter 802. The ServCellIndex parameter 412a may include a ServCellIndex parameter 414a. The reconfigurationWithSync parameter 416a may include a ReconfigurationWithSync parameter 418b. The reconfigurationWithSync parameter 416a may be included provided that ReconfWithSync is configured or enabled during dual connectivity, as shown at 420a. The spCellSCellConfig parameter 802 may include a SCellConfig parameter 804. The spCellSCellConfig parameter 802 may be included provided that L1_L2_mobility_SpCell is configured or enabled during dual connectivity, as shown at 806. If the spCellSCellConfig parameter 802 is present, this field may contain parameters to be used for this SpCell if the WTRU receives an L1 / L2 mobility indication to demote this SpCell to an SCell. L1_L2_mobility_SpCell may optionally be present if this SpCell is part of an L1 / L2 mobility set group and may be demoted to an SCell upon receipt of such an L1 / L2 indication from the network.

[0095] 9 shows an example of a WTRU that stores configuration until receiving an L1 / L2 message. In one example, an additional SCell can be added using the sCellToAddModList IE in CellGroupConfig, and the serving cell index of this SCell can be associated with the SpCell. In one example, the WTRU can be configured with a list of candidate cells, each of which can be provided using one or more of CandidateCellIndex (and / or servingCellIndex), SpCellConfig, SCellConfig, and / or OtherConfig.

[0096] SpCellConfig 410b may include a servCellIndex parameter 412b, a reconfigurationWithSync parameter 416b, and / or an spCellSCellIndex parameter 902. ServCellIndex parameter 412b may include ServCellIndex parameter 414b. ReconfigurationWithSync parameter 416b may include ReconfigurationWithSync parameter 418c. ReconfigurationWithSync parameter 416b may be included provided that ReconfWithSync is configured or enabled during dual connectivity, as shown at 420b. spCellSCellIndex parameter 902 may include ServCellIndex parameter 904. spCellSCellIndex parameter 902 may be included provided that L1_L2_mobility_SpCell is configured or enabled during dual connectivity, as shown at 806a. If the spCellSCellindex parameter 902 is present, this field may contain parameters to be used for this SpCell if the WTRU receives an L1 / L2 mobility indication to demote this SpCell to an SCell. L1_L2_mobility_SpCell may optionally be present if this SpCell is part of an L1 / L2 mobility set group and may be demoted to an SCell upon receipt of such an L1 / L2 indication from the network.

[0097] 10 is a diagram illustrating an example of an ASN.1 structure. CandidateCellConfig 1002 may include a candidateCellIndex parameter 1004, an spCellConfig parameter 1008, an sCellConfig parameter 1012, and / or an otherCellConfig parameter 1016. CandidateCellIndex parameter 1004 may include a ServCellIndex parameter 1006. The spCellConfig parameter 1008 may include an spCellConfig parameter 1010. The sCellConfig parameter 1012 may include an sCellConfig parameter 1014. The otherCellConfig parameter 1016 may include an OtherCellConfig parameter 1018. The candidateCellIndex parameter 1004 may relate to a short identity and may be used to uniquely identify a candidate L1 / L2 mobility cell. The spCellConfig parameter 1008, if present, may contain parameters to be used for this cell if the WTRU receives an L1 / L2 mobility indication configuring this cell as an SpCell. The sCellConfig parameter 1012, if present, may contain parameters to be used for this cell if the WTRU receives an L1 / L2 mobility indication configuring this cell as an SCell. The otherCellConfig parameter 1016, if present, may contain parameters to be used for this cell if this cell is configured as part of the cell's measurement set.

[0098] Each candidate cell may be given one or more potential configurations. If the cell may be configured as an SpCell at some point in the future, the cell may be configured with SpCellConfig. If the cell may be configured as an SCell at some point in the future, the cell may be configured with SCellConfig. Additional configurations (e.g., OtherCellConfig) may include parameters to be used under specific circumstances. For example, it may be possible for the WTRU to configure more cells than just SPCells for performing RLM measurements. In one example, these cells may be SCells or candidate cells (e.g., potential SCells but not currently configured as such). These cells using the "other" configuration may have intermediate states, e.g., cells that are monitored for any or more of RLM, beam tracking, BFD, PDDCH monitoring, and timing advance maintenance before becoming the active PCell and / or SCell. These cells may be configured to use the "other" configuration by L1 / L2 mobility commands. A unique index (e.g., candidateCellIndex) may be assigned to each configured candidate cell (a candidate cell associated with multiple configurations as described above). This index may be referenced by L1 / L2 mobility commands (e.g., MAC CE or DCI) when setting the cell's state or when switching it to an SpCell (from an SCell) or vice versa. Alternatively, or in addition, each cell may be configured with an index value using the existing servCellIndex and / or sCellIndex (e.g., contained in SpCellConfig and SCellConfig), which may be referenced by L1 / L2 mobility commands.

[0099] Upon receiving an L1 / L2 mobility command informing the WTRU which cells are SPCells, which cells are SCells, and potentially which cells are included in the "other" cell group, the WTRU may reassign servCellIndex and / or sCellIndex according to the arrangement, e.g., so that existing L1, MAC, and / or RRC procedures can refer to these indices. For example, the PCell may be assigned servCellIndex 0, and the SCells may be assigned servCellIndex and sCellIndex 1...N, e.g., in the order of their candidateCellIndex. The WTRU may apply the relevant configurations according to the L1 / L2 command assignment. For example, the WTRU may release the current SpCellConfig and SCell configurations and apply the new configurations. Alternatively or in addition, the WTRU may modify the existing configurations according to the new assignments. For example, the WTRU may move the new PCell from servCellIndex N to servCellIndex 0 and move the SCell indicated in the L1 / L2 mobility command to servCellIndex 1...N.

[0100] The WTRU may be configured with a list of candidate cell groups. Each candidate cell group may include one or more of: candidateCellGroupIndex, cellGroupId, SpCellConfig (e.g., one or more potential SPCells), SCellConfig (e.g., a list of SCells), OtherConfig, rlc-BearerToAddModList (e.g., a list of RLC-BearerConfigs), rlc-BearerToReleaseList (e.g., a list of LogicalChannelIdentities), MAC-CellGroupConfig, and / or PhysicalCellGroupConfig. In an example, the WTRU may be configured with one candidate cell group configuration per candidate SpCell, including a list of potential SCells. Upon receiving an L1 / L2 mobility indication, the WTRU may apply the cell group configuration and / or apply the SpCell configuration. The WTRU may receive, for example, in the same L1 / L2 mobility indication (e.g., the SpCell and SCell may be indicated in the same MAC CE) and / or in separate indications (e.g., in separate MAC CEs), which of one or more listed SCells to configure. The WTRU may re-assign serving cell identities as described above. The WTRU may move the PCell to identity 0 and any configured SCell, for example, from index 1 to 31.

[0101] In one example, a WTRU may be configured with one candidate cell group configuration for each combination of SpCell and / or SCell. For example, if the SpCell is cell A or cell B and the SCell is cell A, and / or cell B, and / or cell C, the WTRU may be configured with six cell group configurations: (1) the SpCell may be cell A and the SCell may be cell B, (2) the SpCell may be cell A and the SCell may be cell C, (3) the SpCell may be cell A and the SCell may be cell B and / or cell C, (4) the SpCell may be cell B and the SCell may be cell A, (5) the SpCell may be cell B and the SCell may be cell C, and / or (6) the SpCell may be cell B and the SCell may be cell A and / or cell C.

[0102] The L1 / L2 mobility indication may include a pointer to a candidate cell group configuration, and upon receiving it, the WTRU may apply the associated cell group configuration, e.g., replace (e.g., release) any previously configured serving cells and / or configure (e.g., add) new serving cells and / or assign them pre-configured explicit serving cell identities.

[0103] In one example, the WTRU may be configured with a cell group configuration that may be associated with one or more potential SPCells and / or one or more potential SCells. The L1 / L2 mobility indication may include a candidate cell group configuration, a candidate cell to be configured as an SpCell, and / or a pointer to a candidate cell to be configured as an SCell. In one example, upon receiving the L1 / L2 mobility indication, the WTRU may apply the indicated candidate cell group configuration and / or the associated candidate cell configuration using any of the methods previously described.

[0104] In one example, each candidate cell group configuration may be pre-configured as being either a master cell group (MCG) or a secondary cell group (SCG) configuration. Upon receiving an L1 / L2 mobility command, the WTRU may replace the current MCG or SCG with the indicated cell group configuration, for example, depending on whether the pre-configuration is associated with an MCG or an SCG. In one example, the candidate cell group may not be associated with an SCG or an MCG. The WTRU may apply the candidate cell group configuration to an MCG or an SCG, for example, depending on the indication received in the L1 / L2 mobility command regarding whether the candidate cell group configuration can be applied as an MCG or an SCG.

[0105] In one example, the WTRU may be configured with a list of candidate RRC reconfigurations, each of which may be provided with one or more of a radio bearer configuration, an MCG configuration (e.g., CellGroupConfig), an SCG configuration (e.g., CellGroupConfig), a CellGroupConfig (e.g., no CSG / MCG specified), a full configuration flag, a measurement configuration, a master key update, SIB1, and / or other configurations.

[0106] In one example, the WTRU may be configured with one candidate RRC configuration per candidate SpCell. In one example, the WTRU may be configured with one candidate RRC configuration per combination of SPCell and SCell. In one example, the WTRU may be configured with one candidate RRC reconfiguration per cell group configuration. In one example, the WTRU may be configured with one or more candidate RRC reconfigurations, one or more candidate cell group configurations, one or more candidate SPCells, and / or one or more candidate Scells. The L1 / L2 mobility indication may indicate one or more of the candidate RRC reconfigurations, candidate cell group configurations, candidate SpCell configurations, and candidate SCell configurations. The WTRU may apply the indicated configurations and / or combinations of the indicated configurations according to any of the methods or examples described above.

[0107] In one example, upon receiving the L1 / L2 mobility signaling indication, the WTRU performs the following operations: release CellGroupConfig associated with the current cell group(s), apply one or more CellGroupConfigs indicated to be configured as new cell group configurations, release one or more measurement configurations associated with the current RRC configuration, apply one or more new measurement configurations associated with the new allocation, perform a master key update, apply a full reconfiguration, store the SIB1 configuration, update the physical cell group configuration (release the current configuration and apply the new configuration), update the MAC cell group configuration (release the current configuration and apply the new configuration), The UE may perform one or more of the following: releasing logical channels (applying configurations), releasing logical channels (RLC bearer configurations), adding logical channels (RLC bearer configurations), updating all servingCellIndexes and sCellIndexes of the current serving cell based on the new allocation as described above, releasing the sPCellConfig associated with the current PCell, applying the sCellConfig associated with the current PCell, releasing the sCellConfig associated with the SCell indicated to be promoted to the PCell, and / or applying the sPCellConfig associated with the indicated SCell.

[0108] In one example, upon receiving an L1 / L2 mobility signaling indication, the WTRU may reset counters used while performing radio link monitoring (RLM) on the SpCell. For example, N310 may be used to count the number of "out of sync" indications from lower layers. In another example, N311 may be used to count the number of "in sync" indications from lower layers. In one example, upon receiving an L1 / L2 mobility signaling indication, the WTRU may stop any running timers used while performing RLM for the SpCell. For example, T310 may be started upon detecting a physical layer problem for the SpCell, e.g., upon receiving N310 consecutive out of sync indications from lower layers. For example, T312 may be started upon triggering a measurement report for a measurement identity for which T312 may be configured while T310 in the SpCell is running.

[0109] In one example, upon receiving the L1 / L2 signaling, the WTRU may keep the current SpCell as an active SCell. In one example, upon receiving the L1 / L2 signaling, the WTRU may keep the current SpCell as an SCell, but in a dormant state (e.g., associating the cell with a dormant bandwidth portion). In one example, upon receiving the L1 / L2 signaling, the WTRU may keep the current SpCell as an SCell, but in a deactivated state. In one example, upon receiving the L1 / L2 signaling, the WTRU may release the cell configuration associated with the current SpCell rather than demoting it to an SCell (e.g., applied to the previous SpCell). In one example, the L1 / L2 signaling may include an instruction regarding one of the above behaviors regarding the handling of the current SpCell (e.g., release, keep dormant as SCell, keep deactivated as SCell, keep active as SCell, etc.). In one example, the WTRU may be configured as to which of the above behaviors regarding the handling of the current SpCell applies (e.g., release, keep dormant as SCell, keep deactivated as SCell, keep active as SCell, etc.) prior to receiving an L1 / L2 mobility indication (e.g., dedicated signaling via RRC / MAC, broadcast signaling, etc.). In one example, the behavior regarding the current SpCell during L1 / L2 mobility may be the same for any cell in the serving cell list and / or candidate set list.

[0110] In one example, the WTRU may be configured with different behaviors regarding the handling of the current SpCell depending on (e.g., type) of the current SpCell. For example, the WTRU may be configured to keep the cell as an active SCell if the frequency of the SpCell is equal to a particular value and / or falls within a particular range of values, but may keep the cell as a deactivated SCell if the frequency of the PCell is different from a particular value and / or does not fall within a given range of values. Apart from frequency, other criteria such as bandwidth may also be used. It may also be envisioned that the behavior may be explicitly indicated for each candidate / serving cell (e.g., as part of the SpCell configuration associated with that given cell, as part of the SCellConfig, etc.).

[0111] In one example, the determination of the SCell state (e.g., for an SpCell that is currently an SCell) may be based on the signal level of the cell. For example, two thresholds may be configured, where if the cell has a signal level above the first threshold, the SCell state may be activated. For example, two thresholds may be configured, where if the cell has a signal level between the first threshold and the second threshold, the SCell state may be dormant. For example, two thresholds may be configured, where if the cell's signal level falls below the second threshold, the SCell state may be deactivated.

[0112] In an example, a WTRU may be configured with only one SpCellConfig that is initially associated with the current SpCell but may become associated with a new SpCell when the SCell is promoted to an SpCell. For example, the WTRU may not need to re-apply the SpCellConfiguration when another cell becomes an SpCell. In one example, some parts / IEs of the SpCellConfig may be shared by all cells, while other parts may be explicitly associated with a given cell. For example, a dedicated serving cell configuration for an SpCell (e.g., spCellConfigDedicated IE) may be specific to each cell, while the rest of the SpCellConfig may be reused by each cell. Which IEs are shared may be fixed in the 3GPP RRC specifications, and / or the network may dynamically (e.g., implicitly or explicitly) indicate to the WTRU which IEs may and may not be shared.

[0113] In the example of providing a candidate cell list, the candidate cell list may include a list of "delta" configurations (e.g., SpCell parameters that differ from the initial SpCell configuration) rather than a list of complete SpCell and / or SCell configurations. In one example, when L1 / L2 mobility signaling is received, the WTRU may retain the SpCell configuration / IEs that may be shared by all cells, but may apply IEs that may be explicitly associated with the SCell that is being promoted to become an SpCell.

[0114] FIG. 11 is a flowchart illustrating a method for a WTRU to perform an L1 / L2 switch of a primary cell (PCell) in a manner that may not require RRC reconfiguration for a subsequent PCell change. The method may include, for example, releasing cell-specific information for the source cell while maintaining common information during handover. In other words, for example, the WTRU can perform an L1 / L2 switch of the PCell without performing a new subsequent cell group configuration. At 1102, the WTRU may receive configuration information for one or more candidate cells for LTM. The configuration information may include a configuration common to multiple cells (e.g., a serving cell and a candidate cell) and / or a configuration specific to each candidate cell. At 1104, the WTRU may receive an LTM command indicating a handover (HO) to the candidate cell. The LTM command may include, for example, a medium access control element (MAC EE) or physical layer downlink control information (PHY DCI). At 1106, the WTRU may retain and / or apply a configuration shared by multiple cells. At 1108, the WTRU may release the configuration associated with the current serving cell. At 1110, the WTRU may apply a configuration specific to the indicated candidate cell. At 1112, the WTRU may send an HO complete message to the network. In this approach, the WTRU may receive configuration information including configuration common to multiple cells and / or configuration specific to each candidate cell. The WTRU may perform an L1 / L2 switch of the primary cell with minimal signaling requirements and without RRC configuration in between. In other words, the WTRU may perform an L1 / L2 switch of the primary cell without sending and receiving complete WTRU configuration information. The WTRU may perform one or more L1 / L2 switches of the primary cell. In this approach, the WTRU may receive additional LTM commands but may not receive additional RRC configurations. For example, the WTRU may receive a second handover LTM command indicating an HO to the previous candidate cell without additional reconfiguration.

Claims

1. 1. A method performed by a wireless transmit / receive unit (WTRU), comprising: receiving a candidate cell group configuration common to a group of candidate cells and at least one candidate radio resource control (RRC) configuration respectively associated with at least one candidate cell of said group of candidate cells; receiving an L1 / L2 mobility indication indicating a cell switch to a target cell within the group of candidate cells; replacing a current WTRU RRC configuration with the candidate cell group configuration; applying a candidate RRC configuration from the at least one candidate RRC configuration associated with the target cell in addition to the candidate cell group configuration for performing the cell switch; A method for providing the above. receiving a second L1 / L2 indication indicating a second cell switch to a second target cell of the group of candidate cells; replacing the candidate RRC configuration associated with the target cell with a second candidate RRC configuration associated with the second target cell; applying a second candidate RRC configuration associated with the candidate cell group configuration and the second target cell; The method of claim 1 further comprising:

3. The method of claim 1 , wherein the candidate cell group configuration is applied as a master cell group (MCG) or a secondary cell group (SCG).

4. The method of claim 1, wherein only one candidate RRC configuration associated with one candidate cell is received.

5. The method of claim 1, wherein the at least one candidate RRC configuration includes a candidate cell list, and the candidate cell list includes a list of delta configurations associated with an initial target cell configuration.

6. The method of claim 1, wherein the L1 / L2 mobility indication includes a Medium Access Control Control Element (MAC ECE).

7. The method described in claim 6, wherein the L1 / L2 mobility indication includes a pointer to the target cell.

8. The method described in claim 6, wherein the L1 / L2 mobility indication includes one or more candidate RRC configurations.

9. The method of claim 1 , wherein the current WTRU RRC configuration comprises a pre-configured MCG configuration or a pre-configured SCG configuration.

10. The step of sending an RRC completion message to the target cell. The method of claim 1 further comprising:

11. 1. A wireless transmit / receive unit (WTRU), comprising: A transceiver; receiving a candidate cell group configuration common to a group of candidate cells and at least one candidate radio resource control (RRC) configuration respectively associated with at least one candidate cell of the group of candidate cells; receiving an L1 / L2 mobility indication indicating a cell switch to a target cell within the group of candidate cells; replacing a current WTRU RRC configuration with the candidate cell group configuration; applying a candidate RRC configuration among the at least one candidate RRC configuration associated with the target cell in addition to the candidate cell group configuration for performing the cell switch; and a processor configured to A WTRU comprising:

12. The processor: receiving a second L1 / L2 indication indicating a second cell switch to a second target cell of the group of candidate cells; replacing the candidate RRC configuration associated with the target cell with a second candidate RRC configuration associated with the second target cell; Applying a second candidate RRC configuration associated with the candidate cell group configuration and the second target cell. The WTRU of claim 11 further configured to:

13. The WTRU of claim 11 , wherein the candidate cell group configuration is applied as a master cell group (MCG) or a secondary cell group (SCG).

14. The WTRU of claim 11, wherein only one candidate RRC configuration associated with one candidate cell is received.

15. The WTRU of claim 11 , wherein the at least one candidate RRC configuration comprises a candidate cell list, the candidate cell list comprising a list of delta configurations associated with an initial target cell configuration.

16. The WTRU of claim 11, wherein the L1 / L2 mobility indication includes a Medium Access Control Control Element (MAC ECE).

17. The WTRU of claim 16, wherein the L1 / L2 mobility indication includes a pointer to the target cell.

18. The WTRU of claim 16, wherein the L1 / L2 mobility indication includes one or more candidate RRC configurations.

19. The WTRU of claim 11 , wherein the current WTRU RRC configuration includes a preconfigured MCG configuration or a preconfigured SCG configuration.

20. The processor, The WTRU of claim 11 , further configured to send an RRC complete message to the target cell.

Images