Method for activating preconfigured cell configuration using medium access control (MAC) control element (CE)

Abstract

A wireless transmit / receive unit (WTRU) is capable of receiving a radio resource control (RRC) message including configuration information. The configuration information can include one or more pre-configured candidate cell configurations. Each of the pre-configured candidate cell configurations can include a special cell (SpCell) configuration, a secondary cell (SCell) configuration, and / or a candidate cell index. The WTRU can receive a medium access control (MAC) control element (CE). The MAC CE can indicate application of a first pre-configured candidate cell configuration of the one or more pre-configured candidate cell configurations and an activation state for each SCell in the first pre-configured candidate cell configuration. The WTRU can initiate a handover to the SpCell in the first pre-configured candidate cell configuration based on the indication in the MAC CE. The WTRU is capable of transmitting data to the SCell activated by the MAC CE.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 395,072 filed on August 4, 2022 and U.S. Provisional Patent Application No. 63 / 410,404 filed on September 27, 2022, which are hereby incorporated by reference in their entirety. Background Art

[0003] L1 / L2 based mobility may include inter-cell beam management in intra-distributed unit (DU) and intra-frequency scenarios. In this case, the serving cell remains unchanged (e.g., it is not possible to change the serving cell using L1 / 2 based mobility). In frequency range 2 (FR2) deployments, carrier aggregation (CA) may be used to utilize the available bandwidth (e.g., to aggregate multiple control channels (CCs) in one frequency band). These CCs may be transmitted using the same analog beam pair (e.g., gNB beams and / or WTRU beams). A WTRU may be configured with a Transmit Configuration Indicator (TCI) state (for receiving a Physical Downlink Control Channel (PDCCH) and / or a Physical Downlink Shared Channel (PDSCH). The number of TCI states may be quite large (e.g., 64). Each TCI state may include a Reference Signal (RS) and / or a Synchronization Signal Block (SSB). The WTRU may reference the TCI to set the beam of the WTRU. The SSB may be associated with a non-serving Physical Cell Identity (PCI). Medium Access Control (MAC) signaling (e.g., a TCI state indication for a WTRU-specific PDCCH Medium Access Control (MAC) Control Element (CE)) may activate the TCI state for Coreset / PDCCH. The MAC may indicate a TCI state associated with a non-serving PCI. CE to support PDCCH reception from non-serving cells. MAC signaling (e.g., TCI state activation / deactivation for WTRU-specific PDSCH) may activate a subset of (e.g., up to) 8 TCI states for PDSCH reception. The DCI may indicate which of the 8 TCI states are activated. In the case of multiple transmit / receive points (TRPs), unified TCI states with different update mechanisms (e.g., based on DCI) may be provided. Summary of the invention

[0004] Methods and / or apparatus are provided for activating a pre-configured cell configuration using a medium access control (MAC) control element (CE). The methods and / or apparatus may provide L1 / L2 based inter-cell mobility. The methods and apparatus may provide a downlink MAC CE for controlling simultaneous special cell (SpCell) and / or secondary cell (Scell) changes. The methods and / or apparatus may provide a two-stage activation of a serving cell, wherein an initial command activates target cell measurements, and / or a second command activates handover and / or switching. The methods and / or apparatus may provide network confirmation of a cell set determined by a WTRU.

[0005] The WTRU may receive a radio resource control (RRC) message including a list of candidate cells. The WTRU may perform one or more handover preparation processes associated with one or more SCells and / or candidate cells on the candidate cell list. The one or more handover preparation processes may include one or more of the following: performing measurements associated with one or more target SpCells), obtaining timing advance information for one or more target SpCells, and / or starting to track beams on one or more target SpCells. The WTRU may receive a MAC CE. The MAC CE may indicate a first SpCell (e.g., a current SpCell) and one or more second SpCells. The first SpCell may be the current SpCell. The one or more second SpCells may be target SpCells. The MAC CE may include one or more target SpCell indexes indicating one or more second SpCells associated with the handover. The WTRU may monitor one or more handover conditions for one or more second SpCells. The one or more handover conditions may include one or more of a timer, a measurement threshold, and / or beam failure detection. The measurement threshold may be associated with a radio link monitoring (RLM) measurement. When one or more handover conditions are met, the WTRU may transmit a reconfiguration complete message to a target SpCell (eg, one of one or more target SpCells).

[0006] The WTRU may receive a radio resource control (RRC) message including configuration information. The configuration information may include one or more preconfigured candidate cell configurations. Each of the preconfigured candidate cell configurations may include one or more of a special cell (SpCell) configuration, a secondary cell (SCell) configuration, and / or a candidate cell index. The WTRU may receive a medium access control (MAC) control element (CE). The MAC CE may indicate the application of a first preconfigured candidate cell configuration of one or more preconfigured candidate cell configurations and the activation status of each SCell in the first preconfigured candidate cell configuration. The WTRU may initiate a handover to a SpCell in the first preconfigured candidate cell configuration based on the reception of the MAC CE. The WTRU may send data to the SCell activated by the MAC CE.

[0007] The WTRU may determine whether to activate the SCell in the first preconfigured candidate cell configuration based on the activation status indicated in the MAC CE.

[0008] The MAC CE may indicate a transmit configuration indicator (TCI) state for one or more cells in the first preconfigured candidate cell configuration. The MAC CE may include a flag indicating whether the first preconfigured candidate cell configuration is applied as a primary cell group (MCG) and / or a secondary cell group (SCG). The MAC CE may include a flag indicating whether the first preconfigured candidate cell configuration corresponding to a previously reported index is applied.

[0009] The MAC CE may be a first MAC CE. The WTRU may be further configured to receive a second MAC CE that activates a first pre-configured candidate cell configuration indicated in the first MAC CE. The MAC CE may be a first MAC CE. The WTRU may be further configured to receive a second MAC CE that initiates target SpCell measurements. The WTRU may be further configured to receive a second MAC CE that indicates which SpCells in the first pre-configured candidate cell configuration to initiate SpCell handover with.

[0010] The handover may be a conditional handover to the plurality of SpCells. The conditional handover may be based on the plurality of SpCells and one or more radio quality measurements of the first preconfigured candidate cell configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented.

[0012] Figure 1Bis an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system.

[0013] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within an illustrated communication system.

[0014] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of another example RAN and another example CN for use within the illustrated communication system.

[0015] Figure 2 Depicted is an example handover scenario.

[0016] Figure 3 Example conditional handoff configuration and / or execution processes are depicted.

[0017] Figure 4 Example L1 / L2 inter-cell mobility operations are depicted.

[0018] Figure 5 Example medium access control (MAC) control element (CE) coding is depicted.

[0019] Figure 6 Depicted are example operations for special cell (SpCell) and secondary cell (SCell) switching using MAC CE.

[0020] Figure 7 An example MAC CE decoding with additional bits is depicted.

[0021] Figure 8 An example MAC CE decoding with an additional octet is depicted.

[0022] Fig. 9 An example MAC CE decoding with a single octet is depicted.

[0023] Fig.10 Another example MAC CE coding is depicted.

[0024] Fig.11 Another example MAC CE coding is depicted. DETAILED DESCRIPTION

[0025] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0026] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the 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), consumer electronic devices, and devices 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.

[0027] 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 configured to wirelessly interface with one or more 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.

[0028] 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 a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, for example, one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0029] 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).

[0030] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, among others. 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).

[0031] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0032] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0033] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0034] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (e.g., Wireless Fidelity (WiFi)), IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0035] Figure 1A The base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0036] 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 1AAlthough 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, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal 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.

[0041] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0042] 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.

[0043] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0044] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0045] 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.

[0046] 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.

[0047] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device and activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor and / or humidity sensor.

[0048] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0049] 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.

[0050] 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.

[0051] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0052] 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.

[0053] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0054] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0055] 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.

[0056] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include or may be in communication with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0057] Although the WTRU Figures 1A to 1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may (eg, temporarily or permanently) employ a wired communications interface with a communications network.

[0058] In a representative embodiment, the other network 112 may be a WLAN.

[0059] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or out of the BSS. Traffic originating from outside the BSS to a STA may be reached by the AP and may be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Direct link establishment (DLS) may be utilized to transmit point-to-point traffic between a source STA and a destination STA (e.g., directly between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0060] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0061] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0062] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by the transmitter STA. At the receiver of the receiver STA, the operations for the 80+80 configuration described above can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0063] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0064] 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.

[0065] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0066] 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.

[0067] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, 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 an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and the gNB 180b (and / or the gNB 180c).

[0068] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0069] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while also not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-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 eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-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.

[0070] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0071] Figure 1DThe illustrated CN 115 may include one or more of AMFs 182a, 182b, one or more of UPFs 184a, 184b, one or more session management functions (SMFs) 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.

[0072] 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 for 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 and mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services 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.

[0073] 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 the service routing performed by the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy implementation and QoS, and providing downlink data notifications. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0074] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring, etc.

[0075] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0076] 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 items may be performed by one or more simulation devices (not shown): WTRU102a-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 can be used to test other devices and / or simulate network and / or WTRU functions.

[0077] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0078] 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 lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0079] Figure 2 An example handover scenario 200 is depicted. At 204, the WTRU context within the source gNB 203 may include user data and / or information regarding roaming and / or access restrictions, which are provided, for example, at connection establishment and / or at the last timing advance (TA) update. At 208, the source gNB 203 and / or the target gNB 205 may configure mobility information provided by the access and mobility management function (AMF) 207. At 212, the source gNB 203 may configure WTRU measurement control, procedures and / or WTRU reporting, for example, based on the measurement configuration. At 216, the source gNB 203 may determine to handover the WTRU 201 based on, for example, the received measurements. At 220, the source gNB 203 may transmit a handover request message to the target gNB 205. The handover request message may include a transparent RRC container with the necessary information to prepare for the handover at the target side. The information may include one or more of the following: target cell ID, KgNB*, cell radio network temporary identifier (C-RNTI) of WTRU 201 in source gNB 203, RRM configuration including WTRU inactive time, basic AS configuration including antenna information and DL carrier frequency, current QoS flow to DRB mapping rules applied to WTRU 201, SIB1 from source gNB 203, WTRU capabilities for different random access technologies (RATs), protocol data unit (PDU) session related information and / or measurement information reported by WTRU including beam related information (if available).

[0080] At 224, admission control may be performed by the target gNB 205. If the WTRU 201 may be admitted, the target gNB 205 may prepare to utilize L1 / L2 handover. At 228, the target gNB 205 may transmit a handover confirmation (ACK) (e.g., such as a handover request confirmation) to the source gNB 203. The handover ACK may include a transparent container to be transmitted as an RRC message to the WTRU 201 to perform the handover. At 232, the source gNB 205 may trigger the Uu handover by transmitting an RRCReconfiguration message to the WTRU 201. The RRCReconfiguration message may include the information required to access the target cell: at least the target cell ID, the new C-RNTI, and / or the target gNB 205 security algorithm identifier for the selected security algorithm. The RRCReconfiguration message transmitted at 232 may also include a dedicated random access channel (RACH) resource set, an association between RACH resources and SSBs, an association between RACH resources and WTRU-specific channel state information reference signal (CSI-RS) configuration, common RACH resources and / or system information of the target cell, etc.

[0081] At 244, the source gNB 203 may transmit an SN state transfer message to the target gNB 205 to transfer, for example, the UL packet PDCP SN receiver state and / or the downlink PDCP SN transmitter state of the data radio barrier (DRB) to which the packet data convergence protocol (PDCP) state preservation (e.g., for the radio link control (RLC) acknowledgement mode (AM)) applies. The SN state transfer procedure may transfer the uplink PDCP SN and / or HFN receiver state and / or the downlink PDCP SN and / or HFN transmitter state. The transfer may occur from the source to the target NG-RAN node during an Xn handover, between NG-RAN nodes involved in dual connectivity, and / or after retrieving the WTRU context for RRC reestablishment. The transfer may occur for each corresponding DRB of the source DRB configuration to which the PDCP SN and HFN state preservation applies. At 248, the WTRU 201 may synchronize with the target cell and / or complete the RRC handover procedure by transmitting an RRCReconfigurationComplete message to the target gNB 205. At 252, the UPF 209 may transmit user data to the source gNB 203 and / or the target gNB 205 (e.g., via the source gNB 203). At 256, the target gNB 203 may buffer the user data received from the source gNB. At 260, the WTRU 201, the source gNB 203, and / or the target gNB 205 may complete the RAN handover. At 264, the target gNB 205 may indicate a handover success to the source gNB 203. At 268, the source gNB 203 may indicate an SN state transfer to the target gNB 205. At 272, the UPF 209 may transmit the user data to the source gNB 203 and / or the target gNB 205 (e.g., via the source gNB 203). At 276, the target gNB 205 may communicate the user data with the WTRU 201 and / or the UPF 209.

[0082] At 280, the target gNB 205 may transmit a path switch request message to the AMF 207, e.g., to trigger the core network (e.g., 5GC) to switch the DL data path towards the target gNB 205 and / or establish a next generation control plane (NG-C) interface instance towards the target gNB 205. At 284, the core network may switch the DL data path towards the target gNB 205. At 288, the UPF 209 may transmit one or more "end marker" packets on the old path to the source gNB 203 per PDU session and / or tunnel. The UPF 209 may then release any U-plane and / or transport network layer (TNL) resources towards the source gNB 203 at 288. At 292, the target 205 handles the user data. At 296, the AMF 207 may acknowledge the path switch request message with a path switch request acknowledgement message. At 298, upon receiving the Path Switch Request Ack message from the AMF 207, the target gNB 205 may transmit a UE CONTEXT RELEASE message to the source gNB 203. The target gNB 205 may transmit the UE CONTEXT RELEASE message to, for example, notify the source gNB 203 of the handover success. The source gNB 203 may then (e.g., based on receipt of the UE CONTEXT RELEASE message) release the radio and / or C-plane related resources associated with the WTRU context ( Figure 2 Any ongoing data forwarding may continue.

[0083] Conditional Handover (CHO) and Conditional Primary and Secondary Serving Cell (PSCell) Addition / Change (CPA / CPC, or collectively referred to as CPAC) may be provided. CHO and / or CPAC may reduce the likelihood of Radio Link Failure (RLF) and / or Handover Failure (HOF).

[0084] Traditional handovers may typically be triggered by measurement reports, but there is nothing preventing the network from transmitting a handover (HO) command to the WTRU even if no measurement report is received. For example, in the case of dual connectivity (DC), when the radio signal level / quality (RSRP, RSRQ, etc.) of a neighboring cell becomes better than the primary serving cell (PCell) or PSCell, the WTRU is configured with an A3 event that triggers a measurement report to be transmitted. The WTRU may monitor the serving cell and / or neighboring cells and may transmit measurement reports when one or more conditions are met. Upon receiving such a report, the network (e.g., the current serving node / cell) may prepare a HO command (e.g., such as an RRC reconfiguration message with reconfigurationWithSync). The network may transmit the HO command to the WTRU. The WTRU may perform (e.g., immediately perform) the HO so that the WTRU is connected to the target cell.

[0085] Conditional handover (CHO) may include preparing multiple handover targets (e.g., compared to only one target in a conventional HO). The WTRU may not perform the CHO immediately as in the case of a conventional handover. For example, the WTRU may be configured with one or more trigger conditions (e.g., a set of radio conditions). When / if the one or more trigger conditions are met, the WTRU may perform a handover towards one of the targets.

[0086] The CHO command may be transmitted when the radio conditions towards the current serving cell are still favorable. Transmitting the CHO command under favorable conditions may mitigate two major failure points in conventional handovers: failure to transmit measurement reports (e.g., if the link quality to the current serving cell is below an acceptable level when the measurement report is triggered in a normal handover) and failure to receive the handover command (e.g., if the link quality to the current serving cell is below an acceptable level after the WTRU has transmitted the measurement report but before the WTRU has received the HO command).

[0087] The trigger conditions for CHO may be based on the radio quality of the serving cell and / or neighboring cells (e.g., similar to the conditions used in conventional NR / LTE for triggering measurement reports). For example, the WTRU may be configured with CHO with trigger conditions similar to A3 and associated HO commands. The WTRU may monitor the current serving cell. When the A3 trigger conditions are met, the WTRU may execute the associated HO command and / or switch the WTRU's connection towards the target cell (e.g., instead of transmitting a measurement report).

[0088] Figure 3 An example conditional handover configuration and / or execution process 300 is depicted. At 304, the example CHO configuration and execution process may include the source node 303 transmitting a CHO request to one or more target nodes 305. At 308, the one or more target nodes 305 may respond with a CHO request ACK. At 312, the source node 303 may transmit a CHO configuration message to the WTRU 301. At 316, the WTRU 301 may monitor one or more CHO conditions of the target node 305. At 320, when the conditions are met, the WTRU 301 may perform a HO. At 324, the WTRU 301 may transmit a CHO confirmation message to the target node 305. At 328, the target node 305 may perform a path switch and / or a WTRU 301 context release.

[0089] In case of RLF, CHO may prevent unnecessary reestablishment. For example, a WTRU may be configured with multiple CHO targets. In this case, the WTRU may experience RLF before the triggering conditions are met for any of the targets. Conventional HO operations may cause an RRC reestablishment procedure that may incur a significant outage time for the WTRU's bearers. With CHO, if the WTRU terminates a cell for which it has an associated CHO after detecting an RLF (e.g., the target cell is already ready for CHO), the WTRU may directly execute the HO command associated with the target cell (e.g., instead of continuing with a full reestablishment procedure).

[0090] CPC and / or CPA may be an extension of CHO in a dual connectivity (DC) scenario. The WTRU may be configured with trigger conditions for PSCell change and / or addition. If the trigger conditions are met, the WTRU may execute the associated PSCell change and / or PSCell add command.

[0091] Inter-cell L1 / L2 mobility can be used to manage beams in CA. Inter-cell mobility based on L1 / L2 can support mobility delay reduction. Inter-cell mobility based on L1 / L2 may include configuration and / or maintenance for multiple candidate cells, for example, to allow configuration for candidate cells to be quickly applied. Inter-cell mobility based on L1 / L2 may include a dynamic switching mechanism between candidate serving cells (e.g., including SpCell and / or SCell), for example, for potential applicable scenarios based on L1 / L2 signaling. Inter-cell mobility based on L1 / L2 may include one or more L1 enhancements for inter-cell beam management (e.g., L1 measurement and / or reporting, and / or beam indication). Inter-cell mobility based on L1 / L2 may include timing advance management. If necessary, inter-cell mobility based on L1 / L2 may include centralized unit-distributed unit (CU-DU) interface signaling to support L1 / L2 mobility.

[0092] L1 / L2-based inter-cell mobility is applicable to independent, CA, and NR-DC situations with serving cell changes within one cell group (CG). L1 / L2-based inter-cell mobility is applicable to intra-DU situations and intra-CU inter-DU situations (e.g., applicable to independent and / or CA). L1 / L2-based inter-cell mobility is applicable to both intra-frequency and inter-frequency. L1 / L2-based inter-cell mobility is applicable to both frequency range 1 (FR1) and frequency range 2 (FR2). L1 / L2-based inter-cell mobility may be applicable when the source cell and the target cell are synchronized or asynchronous. When the inter-CU situation is not included, L1 / L2-based inter-cell mobility may be applicable.

[0093] L1 / L2 based mobility may include inter-cell beam management in intra-DU and intra-frequency scenarios. In this case, the serving cell remains unchanged (e.g., it is not possible to change the serving cell using L1 / L2 based mobility). In FR2 deployments, carrier aggregation (CA) may be used to aggregate multiple control channels (CCs) in one frequency band using the available bandwidth (e.g.). These CCs may be transmitted using the same analog beam pair (e.g., gNB beam and / or WTRU beam). The WTRU may be configured with a transmission configuration indicator TCI state for receiving a physical downlink control channel (PDCCH) and / or a physical downlink shared channel (PDSCH). Each TCI state may include a reference signal (RS) and / or synchronization signal block (SSB) that the WTRU references to set the beam of the WTRU. The SSB may be associated with a non-serving physical cell identity (PCI). Medium access control (MAC) signaling (e.g., a TCI state indication for a WTRU-specific PDCCH medium access control (MAC) control element (CE)) may activate the TCI state for the Coreset / PDCCH. Reception of PDCCH from non-serving cells may be supported by a MAC CE indicating the TCI state associated with the non-serving PCI. MAC signaling (e.g., TCI state activation / deactivation for WTRU-specific PDSCH) may activate a subset of (e.g., up to) 8 TCI states for PDSCH reception. The DCI may indicate which of the 8 TCI states are activated. In case of multiple transmit / receive points (TRPs), unified TCI states with different update mechanisms (e.g., based on DCI) may be provided.

[0094] When using regular L3 handover or conditional handover, the WTRU may use RRC signaling to transmit measurement reports. In response to the measurement reports, the network may provide additional measurement configurations and / or CHO configurations. With regular HO, the network may provide configurations for the target cell after the WTRU uses RRC signaling to report that the cell meets the configured radio quality criteria. With CHO, the network may provide the target cell configuration and / or measurement criteria that determine when the WTRU should trigger the CHO configuration in advance (e.g., in order to reduce the HO failure rate due to delays in transmitting measurement reports and then receiving RRC reconfiguration). Both CHO and conditional HO may suffer a certain amount of delay, for example due to transmitting measurement reports and / or receiving target configurations, especially in the case of regular (non-conditional) HO.

[0095] Compared to conventional L3 HO or conditional handover, L1 / L2 inter-cell mobility can improve HO latency. L1 / L2-based inter-cell mobility can enable fast application of configuration for candidate cells, including, for example, dynamically switching between SCells and / or switching PCells (e.g., switching roles between SCells and PCells) without performing RRC signaling. For example, L1 / L2-based inter-cell mobility may not support the inter-CU case because it requires relocation of the PDCP anchor. RRC-based methods can support inter-CU handover.

[0096] In an example, a conventional L3 handover mechanism may include releasing the active SCell before the WTRU completes the handover to a target cell in the coverage area of ​​the new site. The active SCell may (e.g., only) be added back after a successful HO. This may result in a decrease in throughput during the handover. L1 / L2 based inter-cell mobility may enable CA operation to be enabled immediately when the serving cell changes.

[0097] Figure 4 An example of L1 / L2 inter-cell mobility operations 400 is depicted. At 404, in the example L1 / L2 inter-cell mobility operations 400, a candidate cell group can be configured through RRC and / or dynamic switching of PCells and / or SCells. At 408, dynamic switching of PCells and / or SCells can be implemented using L1 / L2 signaling.

[0098] At 412, in order to perform fast switching between cells, particularly SpCells (e.g., PCells and / or PSCells), pre-configuration of candidate cells may be performed at the RRC layer. In an example, the configuration may be applied upon receiving an indication from L1 / L2. The candidate cell may have one or more of a SpCell configuration and / or a SCell configuration. The SpCell configuration and / or the SCell configuration may be dynamically applied based on an indication at a lower layer.

[0099] Additional configuration associated with the preconfigured SCell and / or SpCell may be provided. For example, measurement configuration and / or configuration assigned to candidate cells so that at least one of synchronization, TA management, inter-cell beam management, RLM and / or BFD procedures may be performed before and / or during reconfiguration.

[0100] It may be desirable to, for example, refer to the pre-configuration in the RRC in an efficient manner to minimize the signaling required to perform the handover.

[0101] The WTRU may be configured to receive an RRC message including a list of candidate cells. The WTRU may perform one or more HO preparation procedures associated with one or more SCells or candidate cells on the candidate cell list. The one or more HO preparation procedures may include one or more of the following: performing measurements associated with one or more target SpCells, obtaining timing advance information for one or more target SpCells, and / or starting tracking beams on one or more target SpCells. The WTRU may receive a medium access control (MAC) control element (CE). The MAC CE may indicate a first SpCell and one or more second SpCells. The first SpCell may be the current SpCell. The one or more second SpCells may be target SpCells (e.g., one or more target SpCells). The MAC CE may include a target SpCell index indicating one or more second SpCells associated with the HO. The WTRU may monitor one or more HO conditions for one or more second SpCells. The one or more HO conditions may include one or more of a timer, a measurement threshold, and / or a beam failure detection (BFD). The measurement threshold may be associated with a radio link monitoring (RLM) measurement. When one or more HO conditions are met, the WTRU may transmit a reconfiguration complete message to a target SpCell (eg, one of the one or more target SpCells).

[0102] MAC CE may be used to signal a cell switch (e.g., to improve the reliability of the cell switch command). MAC CE may be sent using HARQ as compared to using L1 signaling such as DCI. Transmitting using HARQ may improve the reliability of transmission by reducing the likelihood of downlink control commands being lost over the air.

[0103] The MAC CE may include information referring to the index of the RRC configuration of the cells involved in the specific part of the configuration (e.g., activation) and / or reconfiguration (e.g., changing role from SCell to SpCell) as the current serving cell and / or L1 / L2 mobility process. The MAC CE may provide an indication of the current role of these cells with reference to the index of the cells, and / or indicate the activation state of the cells. The index of the cells and / or the indication of the current role of these cells may identify the configuration to be applied and / or which configuration(s) to release.

[0104] Figure 5An example MAC CE decoding 500 is depicted. The network may transmit the MAC CE 500 to the WTRU. Prior to receiving the MAC CE 500, the WTRU may receive configuration information from the network. In the example MAC CE decoding 500, the network may first pre-configure a list of (e.g., up to 32) cells using RRC signaling with SCell configurations and / or SpCell configurations and indices. For example, the WTRU may receive an RRC message including the configuration information. The configuration information may include one or more pre-configured candidate cell configurations. Each pre-configured candidate cell configuration may include a SpCell configuration, an SCell configuration, and / or a candidate cell index.

[0105] The MAC CE 500 may indicate one of the preconfigured candidate cell configurations to be applied. For example, the MAC CE 500 may indicate which of the preconfigured candidate cell configurations are to be applied. The MAC CE 500 may indicate the activation state (e.g., such as activated or deactivated) for each SCell in the indicated preconfigured candidate cell configuration. One of the 32 bits in octet 2 504b to octet 5 504e may be used to identify each of the 32 cells in the preconfigured candidate cell configuration, and the bitmap (e.g., candidate cell index) may be used to configure, activate and / or deactivate each cell as an SCell. An integer "1" may indicate that the cell is activated as a serving cell. An integer "0" may indicate that the candidate is deactivated as a serving cell. A specific cell may be identified using the SpCell index (e.g., a value between 0 and 31) in octet 1 504a. Although the remaining 3 bits are shown as reserved, these bits may be defined for specific purposes (e.g., to enable enhancements in future releases, such as conditional L1 / 2 cell switching, inter-CU reconfiguration, or to indicate specific scenarios, such as NR-DC and / or DAP handover).

[0106] The combination of an integer value for the SpCell index and a bitmap identifying the SCell may be an efficient decoding method for performing both SCell activation and deactivation and SpCell changes using a single MAC CE. For example, the WTRU may initiate a handover to the SpCell in the indicated preconfigured candidate cell configuration (e.g., in the SPCell index) based on the MAC CE 500. The WTRU may be configured to send data to the SCell activated by the MAC CE 500. For example, the WTRU may determine whether to activate the SCell in the indicated preconfigured candidate cell configuration based on the activation state indicated in the MAC CE 500. As described herein, the MAC CE 500 may indicate the TCI state for one or more cells in the indicated preconfigured candidate cell configuration.

[0107] Figure 6 Example operations 600 of SpCell and / or SCell switching using MAC CE are depicted. A network 610 may have an RRC layer 612 and a MAC layer 614. A WTRU 620 may have a MAC layer 622 and an RRC layer 624. SpCell switching may also be referred to as handover. If the SpCell is a PSCell, the SpCell switching may be referred to as an SCG change. RRC signaling may be used to change the SpCell. The RRC may perform one or more procedures, such as releasing the current SpCell configuration, deriving new security keys, applying a new SpCell configuration, resetting counters, indicating to lower layers to flush buffers (e.g., performing a MAC reset), etc. After applying the new SpCell configuration, the WTRU 620 may complete the handover by transmitting a reconfiguration complete message to the new SpCell. The RRC procedures used to perform and / or complete the reconfiguration may remain unchanged. Additional enhancements may be made to further optimize the reconfiguration process (eg, using a MAC CE to indicate handover completion, and / or implicit handover completion based on decoding of the first uplink and / or downlink transmission and / or reception).

[0108] At 604, initiating RRC reconfiguration may include simultaneously using a change of configured SpCells and SCells that were pre-provided using RRC signaling and activated using a MAC CE. The RRC reconfiguration may work with existing RRC reconfiguration procedures and / or with enhanced RRC (e.g., MAC and / or RLC, etc.) procedures. For example, the network 610 may transmit the RRC reconfiguration from its RRC layer 612 to the RRC layer 624 of the WTRU 620. In addition to dynamically initiating handover (SpCell change) and performing SCell changes (e.g., activation / deactivation), a relatively large (e.g., up to 32) number of cells may be configured with pre-configured SpCell and / or SCell configurations, and / or a limited number of cells may be activated as serving cells (e.g., up to 8). At 608, truncated versions of many existing MAC CEs may be used for conventional operations. For example, SCell activation and / or deactivation, power headroom reporting (PHR) and / or beam failure recovery (BFR) have truncated versions that may be advantageously used to reduce resources instead of full versions. For example, the SCell portion of the MAC CE may not activate and / or deactivate the SCell. The SCell portion of the MAC CE may inform the WTRU 620 which of the candidate cells may be considered as SCells and which candidate cells are not considered as SCells. For example, the network 610 may transmit a cell activation command from its MAC layer 614 to the MAC layer 622 of the network 620 at 608. Those candidate cells configured as SCells may then undergo separate activation and / or deactivation.

[0109] Figure 7 An example MAC CE decoding 700 with additional bits is depicted. The MAC CE decoding 700 may be further optimized, for example, by reinterpreting the 32 bits used for the reference SCell. The MAC CE decoding 700 may include first considering that the cell (eg, or configuration) indicated in the SpCell Index field is not included in the SCell list.

[0110] Example MAC CE decoding 700 may include using an additional bit for another purpose (e.g., when used with Figure 5 500). Since one of the cells is indicated as a PCell, the cell cannot be an SCell at the same time. Therefore, the PCell index may be removed from the bitmap and / or the remaining (e.g., only the remaining) 31 cells may be referenced. The PCell may have (e.g., always have) an index of 0, and the SCell may have (e.g., always have) an index of 1-31. In the example MAC CE decoding 700, for example, the index may be renumbered from the PCell index + 1 to 32 and from the PCell index to 31 to correctly interpret the MAC CE and / or identify the correct RRC configuration to be applied.

[0111] Figure 8 Another example MAC CE decoding 800 with additional octets is depicted. The MAC CE 800 may include one or more additional octets 804a-f (eg, when used with Figure 5 800). In an example, one or more octets 804a-f may indicate one or more target SpCell indexes. The target SpCell may be indicated before activating the cell change, for example, to perform some handover preparation steps. The handover preparation steps may include starting to perform measurements (such as RLM and / or BFD), synchronizing to the target cell before handover, obtaining timing advance information for the target before cell switching, and / or starting to track beams on the target cell. One or more of the handover preparation steps may be activated before switching the SpCell, for example, to improve the latency and / or reliability of the cell switching itself. The MAC CE 800 may provide an indication of one or more transmit configuration indicator (TCI) states associated with the target cell to perform measurements (e.g., inter-cell beam management, uplink synchronization, and / or other processes). For example, the MAC CE 800 may indicate the TCI state for one or more cells in a preconfigured candidate cell configuration.

[0112] In an example, both the current SpCell and / or the target SpCell may be indicated when switching to the new SpCell while activating radio link monitoring and / or other handover preparation steps on the new SpCell.

[0113] In an example, it may not be necessary to provide a SpCell index. The MAC CE may provide (e.g., only provide) a target SpCell index and may provide one or more target or current SCells. In this case, the WTRU may not immediately activate any SpCell switching. Instead, the WTRU may initiate handover preparation steps, such as one or more of the processes described above.

[0114] In an example, one bit (e.g., one bit out of R bits) may indicate whether the MAC CE command corresponds to a primary cell group (MCG) (e.g., PCell and / or SCell) and / or a secondary cell group (SGC) (e.g., PSCell, SCell).

[0115] In an example, the index of the SpCell of the MCG and / or the SpCell of the SCG may be included in the same command.

[0116] The indication of the target SpCell may require one or more conditions to activate the SpCell change (e.g., conditional handover). The one or more conditions may include, for example, process conditions, timers, and / or measurement conditions (e.g., conditional handover may be configured). The WTRU may begin evaluating the triggering conditions upon receiving the relevant target SpCell indication in the MAC CE. When the conditions are met, a handover may be initiated. For example, the WTRU may initiate a handover based on one or more radio quality measurements of the SpCell in the pre-configured candidate cell configuration.

[0117] One or more conditions may include a second MAC CE indicating an "activate" command, such as "activate the configuration indicated in the previous MAC CE". For example, upon receiving the target PCell indication, the WTRU may start performing and / or reporting measurements. When the reported measurements are determined by the network to be applicable for performing a cell change, the network may activate the cell change.

[0118] Fig. 9 Another example MAC CE decoding 900 having a single octet is depicted. The activation MAC CE may be a single octet 904, which may include, for example, Fig. 9 A single activation bit is shown. The Activation MAC CE may include multiple bits indicating one of several previously activated configurations.

[0119] Activation at the MAC may be performed in 2 phases. The first activation phase may include receiving an activation MAC CE at the WTRU indicating a target configuration (e.g., a target SpCell). The second activation phase may include activating a cell change with an activation MAC CE. For example, the network may first activate N target SpCells using a first MAC CE. The network may then confirm which of those N target SpCells perform the SpCell change using the N bits in a second MAC CE.

[0120] In an example, the Activation MAC CE may confirm the WTRU selection of the target configuration. For example, the WTRU may be configured with measurements. For example, the WTRU may report a list of one or more best cells (e.g., using RRC measurement reports, some L1 measurement reports, and / or in an uplink MAC CE). The activation may reference the reported list of cells, and the WTRU may use the stored RRC configuration to initiate a SpCell change to the previously reported best cell.

[0121] Fig.10 Another example MAC CE decoding 1000 is depicted. The MAC CE decoding 1000 may include a SpCell index, a target SpCell index, and / or 32 bits, as described herein. The MAC CE decoding 1000 may include one or more octets 1004a-g to indicate some additional configuration.

[0122] In an example, the additional one or more octets 1004a-g may inform the WTRU which SCells to activate and / or deactivate. (e.g., in Fig.10 The 32 bits (marked as "C" in the ) may indicate which of the candidate cells are considered SCells. In this example, the maximum number of serving cells may be 8 candidates (e.g., 1 SpCell and 7 SCells) out of the possible 32 candidates. The additional octet(s) 1004a-g may indicate which of the 7 SCells are activated / deactivated. The additional octet(s) 1004a-g may inform the WTRU of any additional candidate cell roles. For example, the additional octet(s) may inform the WTRU which cells are used for L1 inter-cell beam management procedures (e.g., the possibility of performing beam management procedures on cells other than the current SpCell), which cells perform RLM, etc.

[0123] In an example, one or more candidate cell configurations may include one or more cell group configurations (e.g., using IE CellGroupConfig). The candidate cell configuration may include one or more RRC reconfigurations (e.g., using RRC reconfiguration messages). For example, when the candidate cell belongs to a different DU (e.g., in this case, a new cell group configuration may be required because the new cell group configuration may include DU-specific information, such as RLC and / or MAC configuration) and / or CU (e.g., in this case, RRC reconfiguration may be used), the candidate cell configuration may include one or more cell group configurations and / or RRC reconfigurations. For example, the RRC reconfiguration may include CU-specific information, such as PDCP and / or SDAP configuration and / or measurement configuration.

[0124] In an example, the MAC CE triggering the cell change may point to a cell group configuration and / or a complete RRC reconfiguration. In this case, an explicit index (e.g., similar to Figure 7 , but for example, where the index points to a cell group index or a full configuration index rather than a SpCell index). The pre-configured candidate configuration may include necessary information, such as including serving cells (e.g., SpCells and SCells to be configured when activating a cell group).

[0125] In an example, the MAC CE may indicate a cell group index and / or a complete configuration index. In some examples, the MAC CE may additionally or alternatively specify which cells are to be included. For example, a cell group (e.g., corresponding to a particular DU) may be preconfigured and / or associated to multiple potential target cells (e.g., belonging to the DU). For example, the MAC CE may indicate a cell group and a cell to be configured as a SpCell and a cell to be configured as a SCell. Fig.11 Example coding is provided in .

[0126] Fig.11 Depicted is another example MAC CE decoding 1100. The MAC CE decoding 1100 may include a cell group index provided in octet 1 1104a, a SpCell index provided in octet 2 1104b, and / or octets 3 1104c-6 1104f may be used to indicate which SCells are to be configured as part of the cell group.

[0127] In some examples, if the CU changes, the network may provide a MAC CE including an RRC reconfiguration index, if the DU changes, the network may provide a MAC CE including a cell group index, and / or if the cell changes but, for example, does not change the CU and / or DU, the network may provide a MAC CE including a candidate cell index (e.g., only a candidate cell index). The type and / or content of the MAC CE sent to the WTRU may be used to determine whether to perform an intra-DU (e.g., no cell group change) procedure (e.g., no MAC reset), an inter-DU (e.g., cell group may change) procedure (e.g., MAC reset and / or RLC reestablishment), and / or an inter-CU (e.g., full RRC reconfiguration or RB configuration may change) procedure (e.g., PDCP reestablishment, security refresh).

[0128] MAC CE decoding 1100 may combine in a single command a current SpCell (e.g., PCell, PSCell), a target SpCell (e.g., PCell, PSCell), one or more SCells, activation and / or deactivation of one or more SCells, and / or an indication of which cells belong to a group of cells to which additional requirements apply. Alternatively or additionally, MAC CE decoding 1100 may combine a target cell group configuration, a target RRC reconfiguration, a target DU, and / or a target CU.

Claims

1. A wireless transmit / receive unit (WTRU), the wireless transmit / receive unit (WTRU) comprising a processor, the processor configured to: receiving a radio resource control (RRC) message including configuration information, the configuration information including one or more preconfigured candidate cell configurations, wherein each of the preconfigured candidate cell configurations includes a special cell (SpCell) configuration, one or more secondary cell (SCell) configurations, and a candidate cell index; Receiving a medium access control (MAC) control element (CE), the medium access control (MAC) control element (CE) indicating application of a first preconfigured candidate cell configuration of the one or more preconfigured candidate cell configurations and an activation state of each SCell in the first preconfigured candidate cell configuration; Initiating a handover to the SpCell in the first pre-configured candidate cell configuration based on receiving the MAC CE; as well as Send data to the SCell activated by the MAC CE.

2. The WTRU of claim 1 , wherein the processor is further configured to: Determine whether to activate the SCell in the first preconfigured candidate cell configuration based on the activation status indicated in the MAC CE.

3. The WTRU of claim 1 , wherein the MAC CE indicates a transmit configuration indicator (TCI) status for one or more cells in the first preconfigured candidate cell configuration.

4. The WTRU of claim 1 , wherein the MAC CE includes a flag indicating whether the first pre-configured candidate cell configuration is applied as a primary cell group (MCG) or a secondary cell group (SCG).

5. The WTRU of claim 1 , wherein the MAC CE includes a flag indicating whether to apply the first preconfigured candidate cell configuration corresponding to a previously reported index.

6. The WTRU according to claim 1, wherein the MAC CE is a first MAC CE that performs one or more handover preparation steps, the WTRU is further configured to receive a second MAC CE, the second MAC CE activates the first preconfigured candidate cell configuration indicated in the first MAC CE, and the one or more handover preparation steps are configured to perform measurements to synchronize the target SpCell before the handover.

7. The WTRU of claim 1, wherein the MAC CE is a first MAC CE, and the WTRU is further configured to receive a second MAC CE, wherein the second MAC CE initiates target SpCell measurement.

8. The WTRU of claim 1, wherein the processor is further configured to receive a second MAC CE indicating which SpCells in the first preconfigured candidate cell configuration are to initiate SpCell handover.

9. The WTRU of claim 1, wherein the handover is a conditional handover to a plurality of SpCells.

10. The WTRU of claim 9, wherein the conditional handover is based on one or more radio quality measurements of the plurality of SpCells and the first preconfigured candidate cell configuration.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving a radio resource control (RRC) message including configuration information, the configuration information including one or more preconfigured candidate cell configurations, wherein each of the preconfigured candidate cell configurations includes a special cell (SpCell) configuration, one or more secondary cell (SCell) configurations, and a candidate cell index; Receiving a medium access control (MAC) control element (CE), the medium access control (MAC) control element (CE) indicating application of a first preconfigured candidate cell configuration of the one or more preconfigured candidate cell configurations and an activation state of each SCell in the first preconfigured candidate cell configuration; Initiate handover to the SpCell in the first pre-configured candidate cell configuration based on the indication in the MAC CE; as well as Send data to the SCell activated by the MAC CE.

12. The method according to claim 11, further comprising: Determine whether to activate the SCell in the first preconfigured candidate cell configuration based on the activation status indicated in the MAC CE.

13. The method of claim 11, wherein the MAC CE indicates a transmit configuration indicator (TCI) state for one or more cells in the first preconfigured candidate cell configuration.

14. The method of claim 11, wherein the MAC CE includes a flag indicating whether the first pre-configured candidate cell configuration is applied as a primary cell group (MCG) or a secondary cell group (SCG). 15 . The method according to claim 11 , wherein the MAC CE includes a flag indicating whether to apply the first preconfigured candidate cell configuration corresponding to a previously reported index.

16. The method of claim 11, wherein the MAC CE is a first MAC CE that performs one or more handover preparation steps, the WTRU is further configured to receive a second MAC CE that activates the first preconfigured candidate cell configuration indicated in the first MAC CE, and the one or more handover preparation steps are configured to perform measurements to synchronize the target SpCell before the handover.

17. The method of claim 11, wherein the MAC CE is a first MAC CE, and the WTRU is further configured to receive a second MAC CE, wherein the second MAC CE initiates target SpCell measurement.

18. The method of claim 11, the processor being further configured to receive a second MAC CE, the second MAC CE indicating which SpCells in the first pre-configured candidate cell configuration are to initiate SpCell handover.

19. The method of claim 11, wherein the handover is a conditional handover to a plurality of SpCells.

20. The method of claim 19, wherein the conditional handover is based on one or more radio quality measurements of the plurality of SpCells and the first preconfigured candidate cell configuration.

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