Enabling layer 1 and layer 2 mobility

Abstract

A wireless transmit / receive unit (WTRU) may perform L1 / L2 handover of a primary cell. In one method, a WTRU configured with configuration information common to a plurality of candidate cells and individual configuration information specific to each candidate cell may receive an LTM indication for handover (HO) to a particular candidate cell. Upon receiving the indication of the LTM of the HO to the particular candidate cell, the WTRU may maintain 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

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 410,909, filed on September 28, 2022, and U.S. Provisional Application No. 63 / 395,215, filed on August 4, 2022. The entirety of U.S. Provisional Application Nos. 63 / 410,909 and 63 / 395,215 are incorporated herein by reference. Background Art

[0003] The present disclosure generally relates to an apparatus and method for mobility mechanisms. More specifically, the present technology relates to enabling layer 1 and layer 2 (L1 / L2) mobility.

[0004] Wireless communication systems have been expanded and diversified to provide various types of communication services, such as voice services or data services. In general, wireless communication systems are multiple access systems that can share available system resources (bandwidth, transmission power, etc.) to support communications with multiple users. Examples of such 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, single carrier frequency division multiple access (SC-FDMA) systems, and the like. Summary of the invention

[0005] A wireless transmit / receive unit (WTRU) may perform L1 / L2 switching of a primary cell via L1 / L2 triggered mobility (LTM). The LTM may have low latency during a handover (HO), where the WTRU may perform the HO based solely on an L1 / L2 indication (e.g., MAC CE), where a secondary cell or even a non-serving cell from a set of candidate LTMs may be promoted to become a new PCell. Therefore, it may be necessary for the WTRU to have appropriate pre-configuration for all possible target PCells. It may also be necessary for the WTRU to perform subsequent switching from one target PCell to another without the need for RRC reconfiguration.

[0006] The WTRU configured with a configuration common to multiple candidate cells and a configuration specific to each candidate cell may receive an LTM indication for HO to a specific candidate cell. Upon receiving the LTM indication for HO to the 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.

[0007] The WTRU may receive configuration information related to LTM. The configuration information related to LTM may include a candidate cell group configuration. The candidate cell group configuration may include common configuration information for a serving cell and at least one candidate cell. The configuration information may also include separate configuration information specific to the serving cell and each candidate cell in the at least one candidate cell. The WTRU may perform communication with the serving cell based on the common configuration information and the information specific to the serving cell. The WTRU may receive an LTM command indicating a handover (HO) to a candidate cell in the at least one candidate cell. The WTRU may release the information specific to the serving cell, while the WTRU may maintain the common information. Without performing a reconfiguration of the configuration information related to LTM, the WTRU may use the common configuration information and the information specific to the indicated candidate cell in the at least one candidate cell to perform a handover to the candidate cell as a serving cell. The WTRU may then transmit a HO completion message to the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0009] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0010] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0011] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0012] Figure 2 is a sequence flow chart illustrating an example of a handover process.

[0013] Figure 3 is a diagram illustrating an example of an excerpt of information elements related to RRC reconfiguration.

[0014] FIG. 4A to FIG. 4C is a diagram illustrating an example of an excerpt of an RRC reconfiguration related information element (IE).

[0015] Figure 5is a diagram illustrating an example of a master cell group (MCG) and a secondary cell group (SCG).

[0016] Figure 6 is a diagram illustrating an example of L1 / L2 inter-cell mobility operation.

[0017] Figure 7 is a diagram illustrating example ASN.1 code for capturing example L1 / L2 mobility signaling.

[0018] Figure 8 is a diagram illustrating an example of a WTRU storing a configuration until a L1 / L2 message is received.

[0019] Fig. 9 is a diagram illustrating an example of a WTRU storing a configuration until a L1 / L2 message is received.

[0020] Fig.10 is a diagram illustrating an example ASN.1 structure.

[0021] Fig.11 is a flow chart illustrating a method for a WTRU to perform L1 / L2 switching of a primary cell (PCell) in an optimal manner, which may not require RRC reconfiguration for subsequent PCell changes. DETAILED DESCRIPTION

[0022] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0023] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send 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 cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0024] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0025] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0026] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0027] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0028] 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) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0029] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0030] 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 together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0031] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0032] Figure 1AThe base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a microcell or a femtocell. As Figure 1A As shown, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0033] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the text and video, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0034] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0035] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0036] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0037] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC) and state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0038] The send / receive element 122 can be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station by air interface 116. For example, in one embodiment, the send / receive element 122 can be an antenna configured to send and / or receive an RF signal. In one embodiment, the send / receive element 122 can be a transmitter / detector configured to send and / or receive, for example, IR, UV or visible light signals. In another embodiment, the send / receive element 122 can be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 can be configured to send and / or receive any combination of wireless signals.

[0039] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0040] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0041] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0042] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0043] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0044] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0045] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via signal processing performed via hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0046] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0047] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0048] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0049] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0050] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0051] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0052] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0053] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include or may be in communication with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0054] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0055] In a representative embodiment, the other network 112 may be a WLAN.

[0056] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries the service to and / or out of the BSS. Services originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Services originating from the STA and destined for the target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Services between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit services to the AP, and the AP may deliver services to the target STA. Services between STAs within the BSS may be considered and / or referred to as point-to-point services. Point-to-point services may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11eDLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0057] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP can send beacons on a fixed channel (such as a primary channel). The primary channel can be a fixed width (e.g., a 20MHz wide bandwidth) or a width dynamically set via signaling. The primary channel can be an operating channel of the BSS and can be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) can listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a specific STA, the specific STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0058] A high throughput (HT) STA may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0059] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For the 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be individually processed by inverse fast Fourier transform (IFFT) and time domain processing. These streams can be mapped to two 80MHz channels, and the data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0060] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0061] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0062] In the United States, the available frequency bands for 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0063] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0064] The RAN 113 may include gNBs 180a, 180b, 180c, but it should be understood that the RAN 113 may include any number of gNBs while being consistent with the embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 108b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Therefore, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. 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 an unlicensed spectrum, while the remaining component carriers may be on a 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 gNB 180a and gNB 180b (and / or gNB 180c).

[0065] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0066] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the evolved Node-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0067] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0068] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0069] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0070] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0071] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0072] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108 or may communicate with the IP gateway. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DN 185a, 185b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the local data network (DN) 185a, 185b.

[0073] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein for one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182ab, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0074] The simulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices can perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices can perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing purposes and / or can use over-the-air wireless communications to perform testing.

[0075] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication performed via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0076] This document describes methods and devices that can implement carrier aggregation (CA). CA can enable transmission or reception on multiple component carriers at the same time, while other methods and devices that cannot perform CA can access one of these component carriers. Each node (e.g., Node B, eNB, gNB, etc.) can serve multiple cells. The cells can be collectively referred to as service cells. The service cells served by the node can be referred to as cell groups. The service cells in the cell group can be divided into a primary cell (PCell) and one or more secondary cells (SCells). In one example, the PCell can operate on a primary frequency, where the WTRU can perform an initial connection establishment process. After the initial connection to the PCell, one or more SCells can be configured and / or added. The SCell can be activated or deactivated to meet on-demand changes in communications with the network (e.g., UL / DL throughput required by the WTRU, available network resources, etc.).

[0077] During dual connectivity (DC), the WTRU may be connected to multiple nodes. For example, the WTRU may be connected to a primary node and one or more secondary nodes. Each of the primary node and the secondary node may serve multiple cells. The primary node may serve a cell group, which may be referred to as a primary cell group (MCG). The secondary node may serve a cell group, which may be referred to as a secondary cell group (SCG). The primary cell for the primary cell group may be referred to as a PCell, and (for example, in the case of configuring DC), and the primary cell for the secondary cell group may be referred to as a primary secondary cell (PSCell).

[0078] The term special cell (SpCell) may refer to 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.

[0079] In one embodiment, the WTRU may receive a radio resource control (RRC) reconfiguration, which may include a SpCell configuration that may be associated with each SCell or a 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 a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may release the current SpCell configuration (e.g., when the current SpCell is associated with cell a). In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may release the current SCell configuration (e.g., when the current SCell is associated with cell b). In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may apply a SpCell configuration associated with another cell (e.g., cell b). In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may apply a SCell configuration associated with another cell (e.g., cell a). In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may reset the RLF counter and / or may stop one or more (or, for example, any) running RLF timers for the SpCell. In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may determine the SCell state of cell a (e.g., based on signal level, pre-configured behavior, based on an indication received in an L1 / L2 indication, etc.). In one example, upon receiving an L1 / L2 mobility set indication that promotes a SCell (e.g., cell b) to become a SpCell (e.g., when the current SpCell may be cell a), the WTRU may transmit an indication to the network indicating successful completion of the L1 / L2 mobility and / or including additional information (such as, for example, the selected SCell state of the old SpCell, measurement results of the serving / candidate cells, etc.).In addition, the non-serving cell may become a new PCell and / or SpCell.

[0080] In one embodiment, the WTRU may receive an RRC reconfiguration that includes an L1 / L2 mobility candidate cell list configuration and / or includes cells other than the current SpCell and Scell. In one example, the configuration may include a SpCell configuration and / or an SCell configuration, which may be associated with one or more candidate cells 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 involving a candidate cell, if the indication indicates that the candidate cell may become an SCell, the WTRU may apply the SCell configuration associated with the candidate cell. In one example, upon receiving an L1 / L2 mobility set indication involving a candidate cell, if the indication indicates that the candidate cell may become an SpCell, the WTRU may apply the SpCell configuration associated with the candidate cell.

[0081] In one embodiment, the WTRU may receive an RRC reconfiguration that includes an L1 / L2 mobility candidate cell group list configuration and includes cells other than the current SpCell and SCell. In one example, the configuration may include a SpCell configuration and / or a SCell configuration that may be associated with one or more candidate cells or each candidate cell. In one example, upon receiving an indication of an L1 / L2 mobility set involving a candidate, the WTRU may apply a cell group configuration that includes any associated SpCell configurations and SCell configurations.

[0082] Figure 2 is a diagram illustrating an example of a handover process 200. For example, Figure 2As shown, at 212, the WTRU 202 may send data to and / or receive data from the source gNodeB (gNB) 204. Data may be sent to and / or received from the user plane function (UPF) 210. At 214, the access and mobility management function (AMF) may manage the connection and mobility tasks of the WTRU between the source gNB 204 and the target gNB 206 by providing mobility control information. The WTRU 202 context within the source gNodeB (gNB) 204 may contain information about roaming and / or access restrictions, which may be provided (e.g., at connection establishment and / or at the last TA (timing advance) update). For example, at 216, the WTRU 202 may perform measurements and reports. The source gNB 204 may configure the WTRU with a measurement configuration and / or the WTRU 202 may report according to the reporting trigger conditions indicated in the measurement configuration. At 218, the source gNB 204 may decide to hand over the WTRU 202 (e.g., based on the received measurement report). At 220, the source gNB 204 may issue a handover request message (which may be a transparent RRC container passing information) to the target gNB 206 to prepare for the handover on the target side. In one example, the information may include the target cell ID, the security key for the gNB (KgNB*), the cell radio network identifier (C-RNTI) of the WTRU 202 in the source gNB 204, the RRM (Radio Power Management) configuration including the WTRU inactive time, the basic access stratum configuration (AS configuration) including antenna information and DL (downlink) carrier frequency, the current quality of service (QoS) flow to data radio bearer (DRB) mapping rules applied to the WTRU, the system information block 1 (SIB1) from the source gNB, the WTRU capabilities for different RATs, and packet data unit (PDU) session related information. In one example, the information may include the measurement information reported by the WTRU, which includes, for example, beam related information (if available).

[0083] 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 requested resources for the WTRU 202 and may transmit a HANDOVER REQUEST ACKNOWLEDGE to the source gNB 204, which may include a transparent container to be transmitted as an RRC message to the WTRU to perform the handover.

[0084] 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 RRCReconfiguration message to the WTRU 202, which may contain information for accessing the target cell. In one example, the information for accessing the target cell may include a target cell ID, an updated C-RNTI, and a target gNB 206 security algorithm identifier for a selected security algorithm. In another example, the information for accessing the target cell may include a set of dedicated RACH resources, an association between RACH resources and SSBs, an association between RACH resources and WTRU-specific CSI-RS configurations, common RACH resources, and system information of the target cell, among others. For one example, if a dual active protocol stack (DAPS) is configured, the source connection may be maintained after transmitting the handover (HO) command. For another example, after transmitting the HO command, there may be no UL or DL ​​communication between the WTRU and the source gNB 204. At 228, the source gNB 204 may deliver buffered data and / or new data from the UPF 210 to the WTRU 202. At 230, the WTRU 202 may disengage from the previous cell and synchronize to the next cell.

[0085] At 232, the source gNB 204 may send an Early State Transfer message. For example, when a DAPS handover is performed, the source gNB 204 may send an Early State Transfer message. At 234, the source gNB 204 may transmit an SN STATUS TRANSFER message to the target gNB 206 to convey the uplink PDCP (Packet Data Convergence Protocol) SN receiver state and the downlink PDCP SN transmitter state of the DRBs to which PDCP state preservation (e.g., for RLC AM) may be applied. The 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 a RAN Handover Complete. The WTRU 202 may synchronize to the target cell and / or may complete the RRC handover procedure by transmitting an RRCReconfigurationComplete message to the target gNB 206. At 240, the target gNB 205 may send a HANDOVER SUCCESS message to the source gNB 204. At 242, the source gNB 204 may send an SN STATE TRANSFER message to the target gNB. 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. The data may be sent to the UPF 210. At 244, the target gNB 206 may transmit a PATH SWITCH REQUEST message to the AMF 208 to trigger the 5GC to switch the DL data path towards the target gNB 206 and / or establish an NG-C interface instance towards the target gNB 206. At 246, the 5GC may switch the DL data path to the target gNB 206. In one example, the UPF 210 may transmit one or more "end marker" packets 248 to the source gNB 204 on the old path 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 transmit a WTRUCONTEXT RELEASE to notify the source gNB 204 of the handover success. In one example, the source gNB 204 may then release the radio and / or C-plane related resources associated with the WTRU context.In one example, any ongoing data forwarding may continue.

[0086] A message may be received by a WTRU, which 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 a serving cell and at least one candidate cell, and / or individual configuration information specific to the serving cell and each candidate cell in the at least one candidate cell. For example, the candidate cell group configuration may be applied as a primary cell group (MCG) or a secondary cell group (SCG). In another example, the candidate cell group configuration may replace a pre-configured MCG configuration or a pre-configured SCG configuration.

[0087] The WTRU may perform communication with the serving cell based on the common configuration information and the configuration information specific to the serving cell. The WTRU may also receive an LTM command indicating a handover (HO) to a candidate cell in the at least one candidate cell. For example, the received LTM-related configuration information 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 an index value for each candidate cell in the at least one candidate cell. The LTM command may include a unique index. A unique index may be assigned to a candidate cell in the at least one candidate cell.

[0088] The WTRU may also release the 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 the information specific to the indicated candidate cell in the at least one candidate cell without performing a reconfiguration of the configuration information related to LTM. For example, the handover may be performed without performing the reconfiguration of the configuration information related to LTM, and without performing another RRC configuration / reconfiguration via an RRC configuration message. The handover to the candidate cell as the serving cell may be based on an incremental configuration, for example. The incremental configuration may include a change in at least one parameter in the configuration information related to LTM. For example, the incremental configuration may include a change in a parameter in the configuration information related to LTM.

[0089] The WTRU may apply the common configuration information to the at least one candidate cell.The WTRU may also apply the individual configuration information specific to the indicated candidate cell of the at least one candidate cell.

[0090] Figure 3 is a diagram illustrating an example of an excerpt of configuration information and information elements related to an RRCReconfiguration message. In one example, the handover (HO) command may be an RRCReconfiguration message including reconfigurationWithSync. As described herein, the RRCReconfiguration message may be transmitted to the WTRU during handover initiation. The RRCReconfiguration message may include the information for accessing the target cell. The RRCReconfiguration message may include an RRCReconfiguration information element 302. The RRCReconfiguration information element 302 may include a secondaryCellGroup configuration parameter 304. The secondaryCellGroup configuration parameter 304 may include a CellGroupConfig parameter 402a. The secondaryCellGroup configuration parameter 304 may be included if the SCG is configured or enabled during dual connectivity, as shown at 306.

[0091] The RRCReconfiguration information element 302 may include additional information elements. For example, the RRCReconfiguration information element 302 may include the RRCReconfiguration information element 308. The RRCReconfiguration information element 308 may include the masterCellGroup configuration parameter 310. The masterCellGroup configuration parameter 310 may include the CellGroupConfig parameter 402b. The masterCellGroup configuration parameter 310 may also be included in each RRCReconfiguration message that includes the MCG, as indicated.

[0092] FIG. 4A to FIG. 4C is a diagram illustrating an example of additional excerpts for configuration information and information elements related to an RRCReconfiguration message. Figure 4B and 4C yes Figure 4A Continuation of the example excerpt shown. Figure 3As shown, the RRCReconfiguration message may include the cell group configuration or CellGroupConfig 402 (eg, including masterCellGroup 310 CellGroupConfig 402b, and possibly secondaryCellGroup 304 CellGroupConfig 402a (when dual connectivity (DC) is configured)).

[0093] For example, CellGroupConfig 402 may include cellGroupId parameter 404, MAC-CellGroupConfig parameter 406, PhysicalCellGroupConfig parameter 408 and / or SpCellConfig parameter 410. MAC-CellGroupConfig may include configuration of parameters of the MAC layer and / or protocol for a specific cell group. For example, the specific cell group may be an MCG and / or an SCG. Similarly, PhysicalCellGroupConfig may include configuration of parameters of the MAC layer and / or protocol for a specific cell group. SpCellConfig 410 may include servCellIndex parameter 412 and / or reconfigurationWithSync parameter 416. servCellIndex parameter 412 may include ServCellIndex parameter 414. reconfigurationWithSync parameter 416 may include ReconfigurationWithSync parameter 418. Under the condition that ReconfWithSync is configured or enabled during dual connectivity, reconfigurationWithSync parameter 416 may be included, as shown at 420.

[0094] ReconfigurationWithSync parameter 418a may include spCellConfigCommon parameter 422. spCellConfigCommon parameter 422 may include ServingCellConfigCommon parameter 424. SCellConfig 426 may include sCellConfigCommon parameter 428 and / or sCellConfigDedicated parameter 430. sCellConfigCommon parameter 428 may include ServingCellConfigCommon parameter 424a. sCellConfigDedicated parameter 430 may include ServingCellConfig parameter 432.

[0095] Figure 5 is a diagram illustrating an example of a primary cell group (MCG) 502a and a secondary cell group (SCG) 502b. The cell group configuration may include the configuration of each cell in the cells belonging to the cell group (e.g., those cells operating in carrier aggregation (CA)). The cells (collectively referred to 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 operate on a primary frequency, where the WTRU performs an initial connection establishment procedure. In one example, the primary cells 504a, 504b may operate on a primary frequency, where the WTRU initiates a connection reestablishment procedure. In one example, the primary cells 504a, 504b may operate on a primary frequency, where the WTRU is the cell indicated as the primary cell 504a, 504b during the handover process. In one example, the primary cell 504a for the primary cell group 502a may be referred to as a PCell, and (e.g., when DC is configured) the primary cell 504b for the secondary cell group 502b 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 SCell 506a, 506b may be a cell that provides other carriers that are used for the corresponding cell group during carrier aggregation.

[0096] Many operations, such as radio link monitoring (RLM) and associated radio link failure (RLF) detection and recovery, may be related to the primary cell. For example, the operation may be related only to the primary cell. Each serving cell may be identified by a servCellIndex (serving cell index) that takes a value 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.

[0097] Inter-cell L1 / L2 mobility can manage beams in a CA situation. However, in one example, cell changes and / or additions may not be supported. In one embodiment, one or more mechanisms and / or processes for L1 / L2-based inter-cell mobility for reducing mobility delays may be specified. For example, in order to specify mechanisms and processes for L1 / L2-based inter-cell mobility for reducing mobility delays, configuration and / or maintenance for multiple candidate cells may be performed to allow rapid application of configurations for candidate cells (e.g., at RAN2, RAN3, etc.). For example, in order to specify mechanisms and processes for L1 / L2-based inter-cell mobility for reducing mobility delays, a dynamic switching mechanism between candidate cells that are serving cells (e.g., including SpCells and SCells) for potentially applicable scenarios may be based on L1 / L2 signaling (e.g., at RAN2, RAN1, etc.). For example, to specify mechanisms and procedures for L1 / L2 based inter-cell mobility for reducing mobility delay, L1 enhancements may be performed for inter-cell beam management, for example, including L1 measurements and reporting, and / or beam indication (e.g., at RAN1, RAN2, etc.). In one example, early RAN2 involvement (e.g., as may be necessary) may be performed, including further clarifying the possibility of interaction between L1 enhancements for inter-cell beam management and dynamic switching mechanisms between candidate cells as serving cells. For example, to specify mechanisms and procedures for L1 / L2 based inter-cell mobility for reducing mobility delay, timing advance (TA) management may be performed (e.g., at RAN1, RAN2, etc.).

[0098] In order to specify the mechanisms and procedures for L1 / L2 based inter-cell mobility to reduce mobility latency, if necessary, central unit-distributed unit (CU-DU) interface signaling may be performed to support L1 / L2 mobility (e.g., at RAN3, etc.). In one example, FR2 specific enhancements may not be excluded.

[0099] The L1 / L2-based inter-cell mobility process can be applied to one or more of the following scenarios: standalone networking, carrier aggregation (CA), and new radio dual connectivity (NR-DC) cases with serving cell changes within a cell group (CG); intra-DU cases and intra-CU inter-DU cases (for example, applicable to standalone networking and CA when no new RAN interface is expected); both intra-frequency and inter-frequency; both FR1 and FR2; the source cell and the target cell can be synchronized or asynchronous; and the inter-CU case may not be included.

[0100] Inter-cell beam management can handle intra-DU scenarios and intra-frequency scenarios. In one example, the serving cell may remain unchanged (e.g., if it is not possible to change the serving cell using L1 / L2-based mobility). In FR2 deployments, CA can be used to utilize the available bandwidth, for example, to aggregate multiple CCs in one frequency band. These component carriers (CCs) can be transmitted with the same analog beam pair (gNB beam and WTRU beam). The WTRU may be configured with TCI states for receiving PDCCH and / or PDSCH (e.g., which may have a considerable number, such as 64). Each TCI state may include an RS or SSB referenced by the WTRU to set 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 Coreset / PDCCH. Receipt of PDCCH from a non-serving cell may be supported by a MAC CE indicating a TCI state associated with a non-serving PCI. MAC signaling (e.g., TCI state activation / deactivation for WTRU-specific PDSCH) may activate a subset of TCI states for PDSCH reception (e.g., up to 8 TCI states for PDSCH reception). DCI may indicate the TCI state (e.g., which TCI state among 8 TCI states). There may be a "unified TCI state" with a different update mechanism (based on DCI), but there may not be multiple TRPs. There may be a unified TCI state with multiple TRPs.

[0101] The overall goal of L1 / L2 inter-cell mobility may be to improve handover latency. For conventional L3 handover or conditional handover, the WTRU may first transmit a measurement report using RRC signaling. In response to the measurement report, the network may provide additional measurement configurations and / or may provide conditional handover configurations. For conventional handover, the network provides the configuration for the target cell after the WTRU uses RRC signaling to report that the cell meets the configured radio quality criteria. For conditional handover, in order to reduce the handover failure rate due to the delay in transmitting the measurement report and then receiving the RRC reconfiguration, the network provides the target cell configuration in advance and the measurement criteria for determining when the WTRU can trigger the CHO configuration. Due to the transmission of the measurement report and the reception of the target configuration, these L3 methods may experience a certain amount of delay, especially, for example, in the case of conventional (non-conditional) handover. In particular, for example, L1 / L2-based inter-cell mobility may be intended to allow rapid application of configurations for candidate cells, including, for example, dynamic switching between SCells and switching of PCells (e.g., switching roles between SCells and PCells), without performing RRC signaling. The inter-CU case may not be included in the R18 work, as this may require relocation of the PDCP anchor point and may have been excluded from the work items. Therefore, an RRC-based approach may be required to support inter-CU handover. One of the purposes of L1 / L2 may be to allow CA operation to be enabled immediately upon serving cell change.

[0102] Figure 6 is a diagram illustrating an example of L1 / L2 inter-cell mobility operations. For example, the candidate cell group may be configured via RRC, and dynamic switching of the PCell and SCell may be achieved using L1 / L2 signaling. As described 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 related structures discussed previously, the SpCell (e.g., PCell or PSCell) may need to be configured separately compared to the SCell, as there may be several functions and WTRU behaviors that may be (e.g., only) related to the SpCell. With the current RRC signaling structure, L1 / L2 switching of SCell to PCell may not be feasible, as configuration of only one sPCell per cell group may be allowed.

[0103] L1 / L2 mobility signaling may include an indication of which SCell may be promoted to PCell. However, these solutions and associated configuration / signaling may also be applicable to situations where a non-serving neighboring cell may be promoted to a PCell. For example, in the description below, unless otherwise specified, it may be assumed that upon receipt of L1 / L2 mobility signaling to promote an SCell to a PCell, the previous PCell is downgraded to become an SCell. In one example, in the description below, L1 / L2 signaling may refer to a MAC CE or a DCI. SpCell configuration may be used for SCell. In one example, for each SCell, the WTRU may be configured with an associated sPCellConfig. The WTRU may store the configuration without applying the configuration.

[0104] 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 a 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. For 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 complete the L1 / L2 inter-cell mobility operation.

[0105] Figure 7 is a diagram illustrating example ASN.1 code for capturing example L1 / L2 mobility signaling. In one example, the WTRU may be configured with an SCellConfig associated with a SpCell (e.g., for each cell group). The WTRU may store the configuration but may not apply it until the WTRU receives an L1 / L2 message, for example, indicating that the corresponding SpCell may now be downgraded to become an SCell.

[0106] 426a, sCellConfigCommon parameter 428a, sCellConfigDedicated parameter 430a, and / or sCellSpCellConfig parameter 702. sCellConfigCommon parameter 428a may include ServingCellConfigCommon parameter 424b. sCellConfigDedicated parameter 430a may include ServingCellConfig parameter 432a. sCellSpCellConfig parameter 702 may include SpCellConfig parameter 704. sCellSpCellConfig parameter 702 may be included if L1_L2_mobility_SCell is configured or enabled during dual connectivity, as shown at 706. If sCellSpCellConfig parameter 702 is present, it may contain parameters to be used for the SCell in the event that the WTRU receives an L1 / L2 mobility indication to promote the SCell to a SpCell. The L1_L2_mobility_SCell may optionally exist if it is part of a L1 / L2 mobility set group and may be promoted to a SCell upon receiving such L1 / L2 indication from the network.

[0107] Figure 8 is a diagram illustrating an example of a WTRU storing a configuration until a L1 / L2 message is received.In one example, an IE (eg, spCellSCellConfig) may be added to the SpCellConfig IE.

[0108] The SpCellConfig 410a may include a servCellIndex parameter 412a, a reconfigurationWithSync parameter 416a, and / or a 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 if 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 if L1_L2_mobility_SpCell is configured or enabled during dual connectivity, as shown at 806. If the spCellSCellConfig parameter 802 is present, then this field may contain parameters to be used for the SpCell in the event that the WTRU receives an L1 / L2 mobility indication to downgrade the SpCell to a SCell. The L1_L2_mobility_SpCell may optionally exist if it is part of a L1 / L2 mobility set group and may be downgraded to a SCell upon receiving such L1 / L2 indication from the network.

[0109] Fig. 9 is a diagram illustrating an example of a WTRU that stores a configuration until an L1 / L2 message is received. In one example, an additional SCell may be added using the sCellToAddModList IE of the CellGroupConfig, and the serving cell index of the SCell may be associated with the SpCell. In one example, the WTRU may be configured with a list of candidate cells, and each candidate cell may be provided with one or more of: CandidateCellIndex (and / or servingCellIndex); SpCellConfig; SCellConfig; and / or OtherConfig.

[0110] The SpCellConfig 410b may include a servCellIndex parameter 412b, a reconfigurationWithSync parameter 416b, and / or a spCellSCellIndex parameter 902. The servCellIndex parameter 412b may include a ServCellIndex parameter 414b. The reconfigurationWithSync parameter 416b may include a ReconfigurationWithSync parameter 418c. The reconfigurationWithSync parameter 416b may be included if ReconfWithSync is configured or enabled during dual connectivity, as shown at 420b. The spCellSCellIndex parameter 902 may include a ServCellIndex parameter 904. The spCellSCellIndex parameter 902 may be included if 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 in case the WTRU receives an L1 / L2 mobility indication to downgrade this SpCell to a SCell. This SpCell may optionally be present if the L1_L2_mobility_SpCell is part of a L1 / L2 mobility set group and may be downgraded to a SCell upon receiving such an L1 / L2 indication from the network.

[0111] Fig.10is a diagram illustrating an example ASN.1 structure. CandidateCellConfig 1002 may include a candidateCellIndex parameter 1004, a spCellConfig parameter 1008, an sCellConfig parameter 1012, and / or an otherCellConfig parameter 1016. The candidateCellIndex parameter 1004 may include a ServCellIndex parameter 1006. The spCellConfig parameter 1008 may include a SpCellConfig parameter 1010. The sCellConfig parameter 1012 may include a SCellConfig parameter 1014. The otherCellConfig parameter 1016 may include an OtherCellConfig parameter 1018. The candidateCellIndex parameter 1004 may relate to a short identifier and may be used to uniquely identify a candidate L1 / L2 mobility cell. If the spCellConfig parameter 1008 is present, it may contain parameters to be used for the cell in the event that the WTRU receives an L1 / L2 mobility indication configuring the cell as a SpCell. If the sCellConfig parameter 1012 is present, it may contain parameters to be used for the cell if the WTRU receives an L1 / L2 mobility indication that the cell is configured as an SCell. If the otherCellConfig parameter 1016 is present, it may contain parameters to be used for the cell if the cell is configured as part of the measurement set of the cell.

[0112] Each candidate cell may be provided with one or more potential configurations. If a cell may be configured as a SpCell at some point in the future, the cell may be configured with SpCellConfig. If a cell may be configured as a SCell at some point in the future, the cell may be configured with SCellConfig. Additional configurations (e.g., OtherCellConfig) may contain parameters that will be used in certain circumstances. For example, more cells than just SpCell may be configured for the WTRU to perform RLM measurements on, and in one example, these cells may be SCells, or they may be candidate cells (e.g., potential SCells, but not currently configured as such). These cells using the "other" configuration may have an intermediate state, for example, cells that are monitored according to any one or one or more of the following before becoming an active PCell and / or SCell: RLM, beam tracking, BFD, PDDCH monitoring, timing advance maintenance. These cells may be configured to use the "other" configuration via 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 state of a cell or switching it (from SCell to SpCell) or vice versa. Alternatively or in combination, an index value may be configured for each cell using existing servCellIndex and / or sCellIndex (e.g., contained in SpCellConfig and SCellConfig), which may be referenced by L1 / L2 mobility commands.

[0113] When an L1 / L2 mobility command is received that informs 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, for example so that existing L1, MAC and / or RRC processes can reference these indexes. For example, the PCell may be assigned servCellIndex 0, and the SCell may be assigned servCellIindex and sCellIndex 1...N, for example in the order of their candidateCellIndex. The WTRU may apply relevant configurations according to the L1 / L2 command assignments, for example, the WTRU may release the current SpCellConfig and SCell config and may apply the new configuration. Alternatively or in combination, the WTRU may modify the existing configuration according to the new assignment. For example, the WTRU may move the new PCell from servCellIndex N to servCellIndex 0, and move the SCells already indicated in the L1 / L2 mobility command to servCellIndex 1...N.

[0114] The WTRU may be configured with a list of candidate cell groups. Each candidate cell group in the candidate cell group may include one or more of the following: 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-BearerConfig); rlc-BearerToReleaseList (e.g., a list of LogicalChannelIdentity); MAC-CellGroupConfig; and / or PhysicalCellGroupConfig. In one example, the WTRU may be configured with one candidate cell group configuration for each candidate SpCell, the candidate cell group configuration containing 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 a separate indication (e.g., in a separate MAC CE), which SCell of the one or more listed SCells is to be configured. The WTRU may reassign the serving cell identity as previously described. The WTRU may move the PCell to identity 0 and any configured SCell, for example, from index 1 up to 31.

[0115] In one example, the WTRU may be configured to have one candidate cell group configuration for each SpCell and / or SCell combination. 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 the following 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.

[0116] The L1 / L2 mobility indication may include a pointer to a candidate cell group configuration, and upon receipt of the candidate cell group configuration, the WTRU may apply the associated cell group configuration, for example, thereby replacing (e.g., releasing) any previously configured serving cells and / or configuring (e.g., adding) new serving cells and / or assigning them pre-configured explicit serving cell identifiers.

[0117] 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 pointer to a candidate cell group configuration, a candidate cell to be configured as a SpCell, and / or a candidate cell to be configured as a SCell. In one example, upon receiving the L1 / L2 mobility indication, the WTRU may apply the indicated candidate cell group configuration and / or may apply the associated candidate cell configuration using any of the methods previously described.

[0118] In one example, each candidate cell group configuration may be pre-configured as a primary 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, based on an indication received in an L1 / L2 mobility command as to whether the candidate cell group configuration may be applied as an MCG or an SCG.

[0119] 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 the following: radio bearer configuration; MCG configuration (e.g., CellGroupConfig); SCG configuration (e.g., CellGroupConfig); CellGroupConfig (e.g., unspecified CSG / MCG); full configuration flag; measurement configuration; master key update; SIB1; and / or other configurations.

[0120] In one example, the WTRU may be configured with one candidate RRC configuration for each candidate SpCell. In one example, the WTRU may be configured with one candidate RRC configuration for each SpCells and SCell combination. In one example, the WTRU may be configured with one candidate RRC reconfiguration for each 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 following candidates: candidate RRC reconfiguration, candidate cell group configuration, candidate SpCell configuration, and candidate SCell configuration. The WTRU may apply the indicated configuration and / or a combination of the indicated configurations according to any of the methods or examples described above.

[0121] In one example, when the WTRU receives an L1 / L2 mobility signaling indication, it may perform one or more of the following: release the CellGroupConfig associated with the current cell group; apply one or more CellGroupConfigs indicated as configured as a new cell group configuration; release one or more measurement configurations associated with the current RRC configuration; apply new one or more measurement configurations associated with the new assignment; perform a master key update; apply a complete 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); release the logical channel (RLC bearer configuration); add a logical channel (RLC bearer configuration); update the servingCellIndex and sCellIndex of all current serving cells in the current serving cell based on the new assignment, as described above; release the sPCellConfig associated with the current PCell; apply the sCellConfig associated with the current PCell; release the sCellConfig associated with the SCell indicated as promoted to PCell; and / or apply the sPCellConfig associated with the indicated SCell.

[0122] In one example, when the WTRU receives an L1 / L2 mobility signaling indication, it may reset the counters used when 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. For another example, N311 may be used to count the number of "in-sync" indications from lower layers. In one example, when the WTRU receives an L1 / L2 mobility signaling indication, it may stop any running timers used when performing RLM for the SpCell. For example, T310 may be started when a physical layer problem is detected for the SpCell (e.g., when N310 continuous out-of-sync indications are received from lower layers). For example, when T310 in the SpCell is running, T312 may be started when a measurement report for a measurement identifier (for which T312 has been configured) is triggered.

[0123] In one example, upon receiving L1 / L2 signaling, the WTRU may maintain the current SpCell as an active SCell. In one example, upon receiving L1 / L2 signaling, the WTRU may maintain the current SpCell as a SCell, but in a dormant state (e.g., associating the cell with a dormant bandwidth portion). In one example, upon receiving L1 / L2 signaling, the WTRU may maintain the current SpCell as a SCell, but in a deactivated state. In one example, upon receiving L1 / L2 signaling, the WTRU may release the cell configuration associated with the current SpCell instead of downgrading it to a SCell (e.g., applying it to the previous SpCell). In one example, the L1 / L2 signaling may include an indication of one of the above actions regarding the processing of the current SpCell (e.g., release, maintain the SCell in a dormant state, maintain the SCell in a deactivated state, maintain the SCell in an active state, etc.). In one example, prior to receiving the L1 / L2 mobility indication (e.g., dedicated signaling via RRC / MAC, broadcast signaling, etc.), the WTRU may be configured as to which of the above behaviors regarding the handling of the current SpCell to be applied (e.g., release, keep the SCell dormant, keep the SCell deactivated, keep the SCell active, etc.). In one example, the behavior regarding the current SpCell on L1 / L2 mobility may be the same for any cell in the serving cell list and / or candidate set list.

[0124] In one example, the WTRU may be configured with different behaviors regarding the handling of the current SpCell, depending on the current SpCell (e.g., type). For example, the WTRU may be configured to maintain the cell as an active SCell if the frequency of the SpCell is equal to a particular value and / or is within a particular value range, but may maintain the cell as a deactivated SCell if the frequency of the PCell is different from a certain value and / or is not within a given value range. In addition to frequency, other criteria (such as bandwidth) may also be used. It is also contemplated 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.).

[0125] In one example, the determination of the SCell state (e.g., for a SpCell that has now become a SCell) can be based on the signal level of the cell. For example, two thresholds can be configured, where if the cell has a signal level above a first threshold, the SCell state can be activated. For example, two thresholds can be configured, where if the cell has a signal level between a first threshold and a second threshold, the SCell state can be dormant. For example, two thresholds can be configured, where if the cell has a signal level between a first threshold and a second threshold, the SCell state can be deactivated.

[0126] In one example, the WTRU may be configured with only one SpCellConfig that is initially associated with the current SpCell, but when the SCell is promoted to SpCell, it may become associated with the new SpCell. For example, when another cell becomes a SpCell, the WTRU may not need to reapply the SpCellConfiguration again. 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 service cell configuration for a 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 specification, and / or the network may dynamically indicate to the WTRU (e.g., implicitly or explicitly) which IEs may be shared and which IEs may not be shared.

[0127] Where an example of a candidate cell list is provided, the candidate cell list may contain 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 receiving L1 / L2 mobility signaling, the WTRU may maintain the configuration / IEs of the SpCell 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 a SpCell.

[0128] Fig.11 1104, the WTRU may receive an LTM command indicating a handover (HO) to a candidate cell. The LTM command may include, for example, a medium access control element (MAC EE) or a physical layer downlink control information (PHY DCI). In 1106, the WTRU may maintain and / or apply a configuration shared by multiple cells. In 1108, the WTRU may release the configuration associated with the current serving cell. In 1110, the WTRU may apply a configuration specific to the indicated candidate cell. In 1112, the WTRU may transmit a HO complete message to the network. In this method, the WTRU may receive 1 configuration information including configurations common to multiple cells and / or configurations specific to each candidate cell. The WTRU may perform an L1 / L2 handover of the primary cell with minimal signaling requirements and without RRC configuration in between. In other words, the WTRU may perform an L1 / L2 handover of the primary cell without sending and receiving complete WTRU configuration information. The WTRU may perform one or more L1 / L2 handovers of the primary cell. In this method, 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 a HO to a previous candidate cell without additional reconfiguration.

Claims

1. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information related to L1 / L2 triggered mobility (LTM), wherein the configuration information comprises a candidate cell group configuration, wherein the candidate cell group configuration comprises common configuration information for a serving cell and at least one candidate cell, and wherein the configuration information comprises individual configuration information specific to the serving cell and each of the at least one candidate cell; performing communications with the serving cell based on the common configuration information and the information specific to the serving cell; receiving an LTM command indicating a handover (HO) to a candidate cell among the at least one candidate cell; releasing the information specific to the serving cell; as well as Handover to the candidate cell as a serving cell is performed using the common configuration information and the information specific to the indicated candidate cell of the at least one candidate cell without performing reconfiguration of the configuration information related to LTM.

2. The method of claim 1, wherein the received LTM-related configuration information is 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.

3. The method of claim 1, wherein the candidate cell group configuration is a first candidate cell group configuration, wherein performing the handover without performing the reconfiguration of the configuration information related to LTM comprises: The handover is performed without receiving a second candidate cell group configuration.

4. The method of claim 1, wherein the LTM command comprises an existing index list, wherein the existing index list configures an index value for each candidate cell in the at least one candidate cell. 5 . The method of claim 1 , wherein the LTM command comprises a unique index, wherein the unique index is assigned to a candidate cell among the at least one candidate cell. 6 . The method according to claim 1 , wherein the candidate cell group configuration is applied as a master cell group (MCG) or a secondary cell group (SCG).

7. The method according to claim 1, wherein the candidate cell group configuration replaces a pre-configured MCG configuration or a pre-configured SCG configuration.

8. The method according to claim 1, further comprising: Applying the common configuration information to the at least one candidate cell; as well as The individual configuration information specific to the indicated candidate cell of the at least one candidate cell is applied.

9. The method of claim 1, wherein the handover to the candidate cell is based on an incremental configuration, wherein the incremental configuration comprises a change of at least one parameter in the configuration information related to LTM.

10. The method of claim 9, wherein the incremental configuration comprises a change of a parameter in the configuration information associated with the LTM.

11. A wireless transmit / receive unit (WTRU), comprising: Transceiver; and A processor, the processor being configured to: receiving, via the transceiver, configuration information related to L1 / L2 triggered mobility (LTM), wherein the configuration information comprises a candidate cell group configuration, wherein the candidate cell group configuration comprises common configuration information for a serving cell and at least one candidate cell, and wherein the configuration information comprises individual configuration information specific to the serving cell and each of the at least one candidate cell; performing communications with the serving cell based on the common configuration information and the information specific to the serving cell; receiving, via the transceiver, an LTM command indicating a handover (HO) to a candidate cell among the at least one candidate cell; releasing the information specific to the serving cell; as well as Handover to the candidate cell as a serving cell is performed using the common configuration information and the information specific to the indicated candidate cell of the at least one candidate cell without performing reconfiguration of the configuration information related to LTM.

12. The WTRU of claim 11, wherein the received LTM-related configuration information is 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.

13. The WTRU of claim 11 , wherein the candidate cell group configuration is a first candidate cell group configuration, wherein performing the handover without performing the reconfiguration of the configuration information related to LTM comprises: The handover is performed without receiving a second candidate cell group configuration.

14. The WTRU of claim 11, wherein the LTM command comprises an existing index list, wherein the existing index list configures an index value for each candidate cell in the at least one candidate cell.

15. The WTRU of claim 11, wherein the LTM command includes a unique index, wherein the unique index is assigned to a candidate cell among the at least one candidate cell.

16. 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).

17. The WTRU of claim 11, wherein the candidate cell group configuration replaces a pre-configured MCG configuration or a pre-configured SCG configuration.

18. The WTRU of claim 11 , wherein the processor is further configured to: applying the common configuration information to the at least one candidate cell; and The individual configuration information specific to the indicated candidate cell of the at least one candidate cell is applied.

19. The WTRU of claim 11, wherein the handover to the candidate cell is based on an incremental configuration, wherein the incremental configuration comprises a change of at least one parameter in the configuration information related to LTM.

20. The WTRU of claim 19, wherein the incremental configuration comprises a change in a parameter in the configuration information related to LTM.

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