Methods, architectures, apparatuses and systems for uplink measurement based l1 / 2 mobility

Abstract

Procedures, methods, architectures, apparatuses, systems, devices, and computer program products using wireless transmit / receive unit (WTRU) configured for receiving first information indicative of one or more candidate target cells, downlink measurement resources and uplink resources, performing downlink measurements on the downlink measurement resources to obtain measurement results, and transmitting, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources, the one or more uplink reference signals including information indicative of the measurement results.

Description

METHODS, ARCHITECTURES, APPARATUSES AND SYSTEMS FOR UPLINK MEASUREMENT BASED Ll / 2 MOBILITYCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 574,346, filed April 4, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure is generally directed to the fields of communications including, for example, to methods, architectures, apparatuses, systems directed to layer 1 and / or layer 2 (L1 / L2) based mobility, for example to methods, apparatus and systems using precoding determination for Ll / 2 triggered mobility using uplink reference signals.SUMMARY

[0003] In a first aspect, the present principles are directed to a method implemented in a wireless transmit / receive unit (WTRU), the method including receiving first information indicative of one or more candidate target cells, downlink measurement resources and uplink resources, performing downlink measurements on the downlink measurement resources to obtain measurement results, and transmitting, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources, the one or more uplink reference signals including information indicative of the measurement results.

[0004] In embodiments, the method includes receiving an indication to perform cell switch towards a target cell, and transmitting second information indicating a handover completion on the target cell.

[0005] In embodiments, the target cell is from the one or more candidate target cells.

[0006] In embodiments, the uplink resources include a sounding reference signal (SRS) portion and a payload portion.

[0007] In embodiments, the uplink resources are respectively associated with one or more downlink measurement conditions.

[0008] In embodiments, the uplink resources are respectively associated with one or more candidate target cells.

[0009] The payload portion can include the downlink measurements.

[0010] In embodiments, the one or more uplink reference signals includes information identifying the WTRU. The information identifying the WTRU can be a temporary identifier. The information identifying the WTRU can be implied by use of the uplink resources.

[0011] In embodiments, the information indicative of the measurement results is implied by a selection of the one or more uplink resources.

[0012] In embodiments, transmitting the one or more uplink reference signals is activated by reception of an indication to transmit the one or more uplink reference signals.

[0013] In embodiments, transmitting the one or more uplink reference signals is activated by fulfilment of a condition. The one or more uplink reference signals can be transmitted to candidate target cells that fulfil the condition, the condition being that the measurement results for a respective beam of a candidate target cell are above a given value.

[0014] In a second aspect, the present principles are directed to a wireless transmit / receive unit, WTRU, including at least one processor configured to receive first information indicative of one or more candidate target cells, downlink measurement resources and uplink resources, perform downlink measurements on the downlink measurement resources to obtain measurement results, and transmit, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources, the one or more uplink reference signals including information indicative of the measurement results.

[0015] In embodiments, the at least one processor is configured to receive an indication to perform cell switch towards a target cell, and transmit second information indicating a handover completion on the target cell. The target cell can be from the one or more candidate target cells.

[0016] In embodiments, the uplink resources include a sounding reference signal (SRS) portion and a payload portion.

[0017] In embodiments, the uplink resources are respectively associated with one or more downlink measurement conditions.

[0018] In embodiments, the uplink resources are respectively associated with one or more candidate target cells.

[0019] In embodiments, the payload portion includes the downlink measurements.

[0020] In embodiments, the one or more uplink reference signals includes information identifying the WTRU. The information identifying the WTRU can be a temporary identifier. The information identifying the WTRU can be implied by use of the uplink resources.

[0021] In embodiments, the information indicative of the measurement results is implied by a selection of the one or more uplink resources.

[0022] In embodiments, the at least one processor is configured to transmit the one or more uplink reference signals upon reception of an indication to transmit the one or more uplink reference signals.

[0023] In embodiments, the at least one processor is configured to transmit the one or more uplink reference signals upon fulfilment of a condition. The at least one processor can be configured to transmit the one or more uplink reference signals to candidate target cells that fulfilthe condition, the condition being that the measurement results for a respective beam of a candidate target cell are above a given value.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A more detailed understanding may be had from the detailed description below, given by way of example in conjunction with drawings appended hereto. Figures in such drawings, like the detailed description, are examples. As such, the Figures (FIGs.) and the detailed description are not to be considered limiting, and other equally effective examples are possible and likely. Furthermore, like reference numerals ("ref.") in the FIGs. indicate like elements, and wherein:

[0025] FIG. 1 A is a system diagram illustrating an example communications system;

[0026] FIG. IB is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1 A;

[0027] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A;

[0028] FIG. ID is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A;

[0029] FIG. 2 illustrates an example of a layer 1 and / or layer 2 (Ll / L2)-triggered mobility (LTM) procedure;

[0030] FIG. 3 illustrates an example scenario;

[0031] FIG. 4 illustrates a representative example of signaling / signal exchange; and

[0032] FIG. 5 is a flow chart illustrating example flow.DETAILED DESCRIPTION

[0033] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components and circuits have not been described in detail, so as not to obscure the following description. Further, embodiments and examples not specifically described herein may be practiced in lieu of, or in combination with, the embodiments and other examples described, disclosed or otherwise provided explicitly, implicitly and / or inherently (collectively "provided") herein. Although various embodiments are described and / or claimed herein in which an apparatus, system, device, etc. and / or any element thereof carries out an operation, process, algorithm, function, etc. and / or any portion thereof, it is to be understood that any embodiments described and / or claimed hereinassume that any apparatus, system, device, etc. and / or any element thereof is configured to carry out any operation, process, algorithm, function, etc. and / or any portion thereof.

[0034] Provided below are acronyms / abbreviations for terms and phrases commonly used in this application:

[0035] ACK Acknowledgement

[0036] BLER Block Error Rate

[0037] BWP Bandwidth Part

[0038] CAP Channel Access Priority

[0039] CAPC Channel access priority class

[0040] CCA Clear Channel Assessment

[0041] CCE Control Channel Element

[0042] CE Control Element

[0043] CG Configured grant or cell group

[0044] CP Cyclic Prefix

[0045] CP-OFDM Conventional OFDM (relying on cyclic prefix)

[0046] CQI Channel Quality Indicator

[0047] CRC Cyclic Redundancy Check

[0048] CSI Channel State Information

[0049] CW Contention Window

[0050] CWS Contention Window Size

[0051] CO Channel Occupancy

[0052] DAI Downlink Assignment Index

[0053] DCI Downlink Control Information

[0054] DFI Downlink feedback information

[0055] DG Dynamic grant

[0056] DL Downlink

[0057] DM-RS Demodulation Reference Signal

[0058] DRB Data Radio Bearer

[0059] eLAA enhanced Licensed Assisted Access

[0060] FeLAA Further enhanced Licensed Assisted Access

[0061] HARQ Hybrid Automatic Repeat Request

[0062] LAA License Assisted Access

[0063] LBT Listen-Before-Talk

[0064] LTE Long Term Evolution e.g., from 3 GPP LTE R8 and up

[0065] NACK Negative ACK

[0066] MCS Modulation and Coding Scheme

[0067] MIMO Multiple Input Multiple Output

[0068] NR New Radio

[0069] OFDM Orthogonal Frequency-Division Multiplexing

[0070] PHY Physical Layer

[0071] PID Process ID

[0072] PO Paging Occasion

[0073] PRACH Physical Random Access Channel

[0074] PSS Primary Synchronization Signal

[0075] RA Random Access (or procedure)

[0076] RACH Random Access Channel

[0077] RAR Random Access Response

[0078] RCU Radio access network Central Unit

[0079] RF Radio Front end

[0080] RLF Radio Link Failure

[0081] RLM Radio Link Monitoring

[0082] RNTI Radio Network Identifier

[0083] RO RACH occasion

[0084] RRC Radio Resource Control

[0085] RRM Radio Resource Management

[0086] RS Reference Signal

[0087] RSRP Reference Signal Received Power

[0088] RS SI Received Signal Strength Indicator

[0089] SDU Service Data Unit

[0090] SRS Sounding Reference Signal

[0091] SS Synchronization Signal

[0092] SSS Secondary Synchronization Signal

[0093] SWG Switching Gap (in a self-contained subframe)

[0094] SPS Semi-persistent scheduling

[0095] SUL Supplemental Uplink

[0096] TB Transport Block

[0097] TBS Transport Block Size

[0098] TCI Transmission Configuration Indication

[0099] TRP Transmission / Reception Point

[0100] TSC Time-sensitive communications

[0101] TSN Time-sensitive networking

[0102] UL Uplink

[0103] URLLC Ultra-Reliable and Low Latency Communications

[0104] WBWP Wide Bandwidth Part

[0105] WLAN Wireless Local Area Networks and related technologies (IEEE 8O2.xx domain)

[0106] Hereinafter, 'a' and 'an' and similar phrases are to be interpreted as 'one or more' and 'at least one'. Similarly, any term which ends with the suffix '(s)' is to be interpreted as 'one or more' and 'at least one'. The term 'may' is to be interpreted as 'may, for example'.

[0107] A symbol ' / ' (e.g., forward slash) may be used herein to represent 'and / or', where for example, 'A / B' may imply 'A and / or B'.

[0108] In this description, “perform LTM” or “perform LTM” procedures refers to performing any / all of the steps described in FIG. 2 for NR, or similar procedures for 6G. Specifically, early synchronization in DL and / or UL to one or more of the candidate cells, performing layer 1 (LI) measurements and reporting on one or more of the candidate cells, switching (i.e. performing handover) between candidate cells (“Perform LTM” can mean that the WTRU (e.g., UE) moves / switches between multiple candidate cells during the procedure).

[0109] The one or more candidate cell sets may be groups of more than one RRC configuration corresponding to a handover configuration for one or more candidate SpCells and optionally SCells. This may be modelled or received as one or more complete RRC Reconfiguration messages, one or more cell group configurations, or one or more cell configurations. Each of the candidate cell configurations may include a candidate configuration identifier, and each of the candidate cell groups may include a candidate cell group identifier. If the grouping is performed at RRC, the switching between different sets of candidate cells may include updating the serving cell indexes or candidate configuration indexes which are used in LI and MAC signalling to refer to specific indexes (for example a MAC CE triggering the reconfiguration may include a candidate configuration index informing the WTRU (e.g., UE) which cell to perform the reconfiguration to).

[0110] The one or more candidate cell groups may be configured as a single list or group of candidate cell configurations at RRC. The grouping may occur at the early sync or LTM execution phase rather than the configuration phase - what this means is that the candidate cell set may be considered as a single group in terms of an RRC configuration list or group, while the cells selected for performing early sync, LI measurements, and LTM execution depend on a further groupinginto multiple subsets of the overall candidate cell list. In other words, the grouping itself may not be modelled at RRC using candidate configuration identifiers, but the grouping is executed as part of the early sync or the LTM execution procedure.

[0111] Throughout this disclosure, when referring to an LTM candidate configuration, this may apply to any type of preconfigured cell information. For example, a WTRU (e.g., UE) may be configured with one or more conditional reconfigurations such as conditional handover (CHO), conditional primary secondary cell (PSCell) addition (CPA) or conditional PSCell change (CPC) which are valid before and / or after a cell change, or valid in certain cells.

[0112] Synchronization Signal Block (SSB) or SS / PBCH block, which may include at least one of the following: PSS (Primary Synchronization Signal), SSS (Secondary Synchronization Signal), Physical Broadcast Channel PBCH (Data, MIB) and PBCH (DMRS). The SSBs may be transmitted by the network (NW) node (e.g., base station, TRP, relay node, RIS unit) in different directions as beams. The number of SSB beams in an SSB burst set, which may be transmitted periodically within an interval (e.g., 5ms) may depend on the carrier frequency. For example, an SSB burst may contain 4 SSBs for frequency range 1 (FR1) (< 3GHz), 8 SSBs for FR1 (3 to 6GHz) and 64 SSBs for frequency range 2 (FR2). Certain SSBs may be transmitted as on-demand SSBs (OD-SSBs), which may possibly consist of a subset of SSBs in a burst. Such OD-SSBs may be transmitted aperiodically, semi-persistently, or periodically with certain periodicity. The transmission of such OD-SSBs may be triggered by the NW node or WTRU (e.g., UE) (e.g., via transmission of an UL WUS). Some SSBs may include slim / lean SSBs, which may include PSS only, PSS and SSS-only, PBCH or a subset of MIB-only, for example.

[0113] Channel state information reference signal (CSLRS), which may include at least one of the following: CSI-RS resource set (ID), CSLRS resource (ID / index), resource mapping, power control offset values (e.g., with respect to PDSCH, SSB), scrambling ID, periodicity, offset and QCL info. CSLRS may be transmitted in DL by the NW node as CSLRS beams, via different resource types including periodic, semi-persistent and aperiodic.

[0114] Channel state information (CSI), which may include at least one of the following: channel quality index (CQI), rank indicator (RI), precoding matrix index (PMI), an LI channel measurement (e.g., RSRP such as Ll-RSRP, or SINR), CSLRS resource indicator (CRI), SS / PBCH block resource indicator (SSBRI), layer indicator (LI) and / or any other measurement quantity measured by the WTRU (e.g., UE) from the configured CSLRS or SS / PBCH (SSB) block.

[0115] Channel conditions refers to any conditions relating to the state of the radio / channel, which may be determined by the WTRU (e.g., UE) from: a WTRU (e.g., UE) measurement (e.g., Ll / SINR / RSRP, CQI / MCS, channel occupancy, RSSI, power headroom, exposure headroom),L3 / mobility-based measurements (e.g. RSRP, RSRQ, s-measure), an RLM state, and / or channel availability in unlicensed spectrum (e.g. whether the channel is occupied based on determination of an LBT procedure or whether the channel is deemed to have experienced a consistent LBT failure).

[0116] An LI measurement herein may consist of a measurement of RSRP, RSRP, RSSI, etc., performed by a WTRU (e.g., UE) of a cell, beam, set of cells, or set of beams. Such LI measurement may be similar to L3 measurements reported in RRM, with differences in the filtering, reference signals measured, reporting mechanisms, etc.

[0117] LI measurement can apply also to RRM reporting. Herein, measurements refer to LI measurements for LTM. Certain embodiments herein may apply also to RRM / L3 measurements, as well as other measurements (e.g., measurements of speed, location, height, traffic, etc.).

[0118] LTM cell switch can apply also to any type of handover execution. Herein, the LTM cell switch refers to Ll / 2 triggered mobility whereby a preconfigured RRC configuration is applied when the WTRU (e.g., UE) receives an indication using MAC CE or when a certain condition is met at the WTRU (e.g., UE). Certain embodiments may apply to an RRC reconfiguration, an RRC conditional reconfiguration, as well as any other type of mobility procedure.

[0119] Throughout this disclosure, the terms, channels, and protocol design for 5G NR is assumed, however it should be understood that the methods taught apply equally to any cellular network such as a 3G 3GPP system. In the context of a 6G or future generation wireless network, some functions may or may not be necessary, depending on the system architecture, protocol design, and physical channel design, however it is assumed that a system operates using the general principle that configurations are provided by an upper (e.g., RRC) layer which apply to multiple target cells, beam, or TRPs and the lower layer (e.g., MAC, LI) controls switching between the configurations.

[0120] Example Communications System

[0121] The methods, apparatuses and systems provided herein are well-suited for communications involving both wired and wireless networks. An overview of various types of wireless devices and infrastructure is provided with respect to FIGs. 1A-1D, where various elements of the network may utilize, perform, be arranged in accordance with and / or be adapted and / or configured for the methods, apparatuses and systems provided herein.

[0122] FIG. 1A is a system diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiplewireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 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), singlecarrier FDMA (SC-FDMA), zero-tail (ZT) unique-word (UW) discreet Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block- filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0123] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated 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 a "STA", may be configured to transmit and / or receive wireless signals and may include (or be) a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi- Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0124] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d, e.g., to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the networks 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node-B (NB), an eNode-B (eNB), a Home Node-B (HNB), a Home eNode-B (HeNB), a gNode-B (gNB), a NR Node-B (NR NB), a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0125] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in an embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0126] 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).

[0127] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed Uplink Packet Access (HSUPA).

[0128] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE- Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0129] 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).

[0130] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0131] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0132] The base station 114b in FIG. 1 A may be a wireless router, Home Node-B, Home eNode- B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In an 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 an 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 any of a small cell, picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0133] 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 varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1 A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or adifferent RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing an NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing any of a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0134] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide 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), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications 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 / 114 or a different RAT.

[0135] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with 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.

[0136] FIG. IB is a system diagram illustrating an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include 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 elements / peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0137] 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 in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, 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 118may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together, e.g., in an electronic package or chip.

[0138] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in an embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In an embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0139] Although the transmit / receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit / receive elements 122. For example, the WTRU 102 may employ MIMO technology. Thus, in an 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.

[0140] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0141] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or 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 the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), readonly 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).

[0142] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the 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, and the like.

[0143] 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 over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0144] The processor 118 may further be coupled to other elements / peripherals 138, which may include one or more software and / or hardware modules / units that provide additional features, functionality and / or wired or wireless connectivity. For example, the elements / peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (e.g., for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The elements / peripherals 138 may include one or more sensors, the sensors may be one or more of 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.

[0145] 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 particular subframes for both the uplink (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 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g.,associated with particular subframes for either the uplink (e.g., for transmission) or the downlink (e.g., for reception)).

[0146] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0147] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-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 an embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0148] Each of the eNode-Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink (UL) and / or downlink (DL), and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0149] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any one of these elements may be owned and / or operated by an entity other than the CN operator.

[0150] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an SI 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, and the like. 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.

[0151] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via the SI 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 user planes during inter-eNode-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0152] 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.

[0153] 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 communicate 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0154] Although the WTRU is described in FIGs. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0155] In representative embodiments, the other network 112 may be a WLAN.

[0156] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802. l ie DLS or an 802.1 Iz tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc" mode of communication.

[0157] When using the 802.1 lac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used bythe STAs to establish a connection with the AP. In certain representative embodiments, Carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0158] High throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadj acent 20 MHz channel to form a 40 MHz wide channel.

[0159] Very high throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse fast fourier transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above-described operation for the 80+80 configuration may be reversed, and the combined data may be sent to a medium access control (MAC) layer, entity, etc.

[0160] Sub 1 GHz modes of operation are supported by 802.1 laf and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.1 laf and 802.1 lah relative to those used in802.1 In, and 802.1 lac. 802.1 laf supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV white space (TVWS) spectrum, and 802.1 lah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment,802.1 lah may support meter type control / machine-type communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0161] WLAN systems, which may support multiple channels, and channel bandwidths, such as802.1 In, 802.1 lac, 802.1 laf, and 802.1 lah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channelmay be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.1 lah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0162] In the United States, the available frequency bands, which may be used by 802.1 lah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.1 lah is 6 MHz to 26 MHz depending on the country code.

[0163] FIG. ID is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an 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.

[0164] 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 an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the WTRUs 102a, 102b, 102c. Thus, the gNB 180a, for example, may use multiple antennas to transmit 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0165] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or differentportions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., including a varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0166] 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 the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non- standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non- standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0167] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and the like. As shown in FIG. ID, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0168] The CN 115 shown in FIG. ID may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0169] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with differentrequirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b, e.g., to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and / or the like. 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.

[0170] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP -based, non-IP based, Ethernet-based, and the like.

[0171] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, e.g., 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 multihomed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0172] 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0173] In view of FIGs. 1 A-1D, and the corresponding description of FIGs. 1 A-1D, one or more, or all, of the functions described herein with regard to any of: WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a- b, SMFs 183a-b, DNs 185a-b, and / or any other element(s) / device(s) described herein, may be performed by one or more emulation elements / devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0174] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may performing testing using over-the-air wireless communications.

[0175] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0176] 3GPP has introduced LTM in Rel-18 and agreed to a work item for enhancement in Rel- 19 [1], It is expected that 6G mobility will use LTM procedures introduced to NR as a baseline.3GPP TS 38.300 vl8.1.0 [2], section 9.2.3.5 describes LTM as follows:

[0177] LTM is a procedure in which a gNB receives LI measurement report(s) from a UE, and on their basis the gNB changes UE serving cell by a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency as described in Annex G.

[0178] When configured by the network, it is possible to activate TCI states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTMcandidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

[0179] When configured by the network, it is possible to initiate UL TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTA as the current serving cells or NTA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by PDCCH order as specified in clause 9.2.6 or realized through UE-based TA measurement as configured by RRC. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH -based LTM cell switch. If the TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE applies the TA value by itself if available. Meanwhile, the UE performs RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE performs RACH- based LTM cell switch.

[0180] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes requesting a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

[0181] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UEshall not trigger random access procedure if it does not have a valid PUCCH resource for triggered SRs.

[0182] The following principles apply to LTM:- Security key is maintained upon an LTM cell switch;- Subsequent L TM is supported.

[0183] LTM supports both intra-gNB-DU and intra-gNB-CU inter-gNB-DU mobility. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. The following scenarios are supported:- PCell change in non-CA scenario and non-DC scenario;- PCell and SCell(s) change in CA scenario;- Dual connectivity scenario, PCell and MCG SCell(s) change and intra-SN PSCell and SCG SCell(s) change without MN involvement. LTM for simultaneous PCell and PSCell change is not supported.

[0184] While the UE has stored LTM candidate configurations the UE can also execute any L3 handover command sent by the network.

[0185] Rel-18 LTM procedure is represented in FIG. 2.

[0186] Uplink based mobility was discussed during the initial standardization phase of NR. In general, this was discussed separately for RRC CONNECTED and for RRC IDLE / INACTIVE. The general principle is that the WTRU (e.g., UE) transmits a signal using an uplink channel which is detectable by more than one cell / TRP. The network then performs measurements on this uplink signal from the WTRU (e.g., UE) and determines which of the cells / TRPs is best suited to serve the WTRU (e.g., UE).

[0187] This was not adopted for NR, due to a majority of companies favouring the more traditional downlink measurement-based mobility approach. However, since LTM mobility has been introduced and is likely to be the baseline approach for 6G radio, an uplink measurement scheme starts to become more suitable. More functions can be performed with lower latency, for example obtaining uplink synchronisation to a target cell, and performing the handover / cell switch. In particular, for certain use-cases such as uplink-only TRP or high frequency cases whereby the uplink coverage is likely to be smaller than the downlink coverage or is likely to suffer from different channel propagation conditions.

[0188] Benefits of LTM include reducing handover latency by reducing the signalling necessary on a source cell with degrading quality, and reducing the handover interruption time. WTRU (e.g.,UE) based handover decision, using CHO, can improve robustness at the expense of lack of network control.

[0189] The following description proposed methods / procedures to further improve mobility latency, robustness, interruption and cover more diverse deployment scenarios by utilising uplink measurements.

[0190] The base station such as gNB (e.g., a central unit (CU) in case of CU / distributed unit (DU) split architecture - note: RRC resides in CU) may configure potential LTM candidates using RRC signalling. According to embodiments, the WTRU (e.g., UE) may receive the LTM candidate configurations using a (e.g., RRC Reconfiguration) message, for example during the “LTM preparation” phase shown in FIG. 2. The WTRU (e.g., UE) may store the LTM candidate configurations to later apply upon receiving an indication using Ll / 2 signalling (e.g., MAC CE) to perform a cell switch, for example in the “LTM execution” phase shown in FIG. 2.

[0191] According to embodiments, the configuration of potential LTM candidates may include candidate sets. For example, a first set which may e.g., be suitable for a first path (for example, a WTRU (e.g., UE) turns left and takes first road) and a second set which may e.g., be suitable for a second path (e.g., WTRU (e.g., UE) turns right and takes second road)

[0192] According to embodiments, some or all of the candidate set information may be broadcasted in system information, and the WTRU (e.g., UE) may enable the pre-configuration of these broadcast configurations, for example, in a case of (e.g., upon) receiving an indication, for example, in dedicated signalling (e.g., RRC Reconfiguration) which may refer to the broadcast one or more configurations (e.g. using an index or identifier)

[0193] According to embodiments, the configuration may include all or a subset of the potential cells in a specific area (for example all cells belonging to the CU with which the WTRU (e.g., UE) is currently connected or cells within a particular geographical area). These cells may not yet have been detected or measured by the WTRU (e.g., UE), but are configured in advance. According to embodiments, after the initial configuration of LTM candidate configurations, the WTRU (e.g., UE) may receive an update to the configuration to modify, add, remove, or replace any part of the LTM candidate configurations.

[0194] According to embodiments, the WTRU (e.g., UE) may receive an indication to enable or disable some or all of the LTM configurations. For example, if it is predicted that the WTRU (e.g., UE) mobility would be better handled using L3 (e.g. RRC measurement report, RRC reconfiguration, conditional reconfiguration) then LTM may be disabled, and on the other hand if it is predicted that LTM would better suit the WTRU (e.g., UE) mobility then LTM may be enabled (e.g. a previously configured and disabled LTM configuration may be re-enabled).

[0195] The configuration may in some embodiments be based on a prediction model internal to, and determined by, the network (e.g., gNB). This prediction may, for example, be based on what it (the NW prediction model) determines to be the WTRUs (e.g., UEs) most likely paths.

[0196] According to embodiments, the candidate cell configurations may contain all or part of the information used (e.g., necessary) to complete a reconfiguration (e.g., handover) to the candidate cell, such as channel configurations (e.g., PRACH, DPCCH, DPSCH), CORESET, BWP, security parameters, layer 2 (L2) parameters (e.g., MAC, RLC, PDCP), radio bearer configurations, and so on.

[0197] LTM execution trigger herein refers to a condition for performing LTM (e.g. a conditional handover trigger or measurement report trigger), which is either configured or indicated by the network to the WTRU (e.g., UE), or estimated / determined by the WTRU (e.g., UE).

[0198] A trigger may be based on parameter based on time, e.g. Absolute or relative time measured time at WTRU (e.g., UE); system frame number (SFN); Subframe number.

[0199] A trigger may be based on radio quality measurement or predicted radio quality one or more of the serving cells or target cells, e.g.: RSRP (beam or cell); RSRQ (Reference Signal Received Quality) (beam or cell); cri-RI-PMI-CQI; cri-RI-il; cri-RI-il-CQI; cri-RI-CQI; cri- RSRP; ssb-Index-RSRP; cri-RI-LI-PMI-CQI).

[0200] A trigger may be based on parameter based on Position, e.g. : an area (e.g. defined by reference point and radius) or range of co-ordinates; a distance threshold from a reference location.

[0201] A trigger may be based on any layer 3 (L3) measurement event, for example : Event Al (Serving becomes better than threshold); Event A2 (Serving becomes worse than threshold); Event A3 (Neighbor becomes offset better than SpCell); Event A4 (Neighbor becomes better than threshold); Event A5 (SpCell becomes worse than threshold 1 and neighbor becomes better than threshold2); Event A6 (Neighbour becomes offset better than SCell); Event Bl (Inter RAT neighbour becomes better than threshold); Event B2 (primary cell (PCell) becomes worse than thresholdl and inter RAT neighbor becomes better than threshold2).

[0202] A trigger may be based on any LI measurement event or condition, for example any event defined which utilizes LI beam measurements to evaluate whether a criteria or condition is met.

[0203] A trigger may be based on any predicted event, for example using any of the measurement quantities previously listed under “Measured or predicted CSI information”.

[0204] A trigger may be based on an (e.g., explicit) indication from the network. For example, the WTRU (e.g., UE) may enable CSI reporting based on an (e.g., explicit) indication (e.g. a MAC CE) received from the network. The WTRU (e.g., UE) may execute LTM cell switch upon receiving a second MAC CE from the network.

[0205] A trigger may be based on a measured, predicted, or estimated throughput, error rate, buffer status, or QoS parameter.

[0206] A trigger may be based on an evaluation metric, for example a time-to-trigger, a hysteresis, offset (e.g. a radio quality measurement offset), a measurement filtering configuration.

[0207] The trigger may include one or more conditions under which the WTRU (e.g., UE) is allowed to any action related to LTM. For example, the WTRU (e.g., UE) may perform one or more of the following procedures.

[0208] The WTRU (e.g., UE) may perform early timing advance (TA) acquisition. The WTRU (e.g., UE) may trigger a RACH to a target LTM cell. The WTRU (e.g., UE) may receive a TA value in a RAR. RAR may come from target cell, or via source cell. The WTRU (e.g., UE) may receive a TA value in a MAC CE triggering the cell switch. The WTRU (e.g., UE) may perform power ramping and preamble retransmission on the target if a RAR / MAC CE is not received. The WTRU (e.g., UE) may acquire the TA value of a candidate LTM cell by measurement, and trigger when complete. The WTRU (e.g., UE) may support and be configured with WTRU (e.g., UE)-based TA measurement, whereby the WTRU (e.g., UE) acquires the TA value(s) of the candidate cell(s) by measurement.

[0209] The WTRU (e.g., UE) may perform switching off CSI reporting. The WTRU (e.g., UE) may be allowed to, or required to, switch off CSI reporting in order to reduce reporting overhead in the uplink. The CSI reporting may be reduced rather than switched off. For example, reduced number of cells or beams reporting, or a reduced frequency of reporting. The WTRU (e.g., UE) may resume CSI reporting when the condition is no longer met.

[0210] The WTRU (e.g., UE) may perform switching on or updating the CSI reporting configuration. For example, the WTRU (e.g., UE) may be required to perform and report CSI measurements on one or a subset of LTM candidate cells during the window.

[0211] The WTRU (e.g., UE) may perform LTM cell switch. Conditions or criteria under which the WTRU (e.g., UE) is allowed to trigger LTM cell switch.

[0212] The WTRU (e.g., UE) may monitor physical downlink control channel (PDCCH) on a target cell. The WTRU (e.g., UE) may be configured to monitor on a target cell for a DCI scheduling physical data shared channel (PDSCH) or indicating one or more actions on the target cell, for example to initiate the cell switch procedure.

[0213] The WTRU (e.g., UE) may perform beam failure recovery (BFR) or radio link monitoring (RLM) on a target cell. The WTRU (e.g., UE) may be configured to monitor BFD (beam failure detection) resources on a target cell, or perform RLM (radio link monitoring) on a target cell during the window.

[0214] The WTRU (e.g., UE) may activate or deactivate certain secondary cells (SCells). The WTRU (e.g., UE) may be configured with one or more specific SCells which should be active or not active during the window.

[0215] To enable RACH-less conditional handover, whereby the WTRU (e.g., UE) is not required to send a random access preamble or perform a random access procedure on the target cell following a reconfiguration trigger but rather the WTRU (e.g., UE) performs PDCCH reception and uplink transmission using the TA already provided, the WTRU (e.g., UE) may perform an early TA acquisition procedure with candidate cell(s) before receiving the cell switch command or before triggering a conditional reconfiguration.

[0216] According to embodiments, and early TA acquisition may be performed using contention- free random access (CFRA) triggered by a PDCCH order from the source cell, following which the WTRU (e.g., UE) may send a preamble towards a candidate cell. The information that identifies the allocated CFRA resource may be indicated in the PDCCH order to enable shared preamble resource among multiple WTRUs (e.g., UEs) in the RRC configuration - the source gNB dynamically indicates which WTRU (e.g., UE) uses the resource at any specific time.

[0217] According to embodiments, this may be performed upon receiving a MAC CE indicating to perform a RACH transmission on a target cell.

[0218] According to embodiments, this may be performed by transmitting using a contentionbased random access (CBRA) preamble.

[0219] According to embodiments, and in order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the WTRU (e.g., UE) may not receive RAR at all. Source cell may trigger a preamble retransmission / power ramping using another PDCCH order, e.g. if the preamble was not received. In this case, the TA may be provided from the target cell to the source cell, and provided to the WTRU (e.g., UE) in a MAC CE triggering cell switch or enabling conditional LTM to one or more target cells.

[0220] According to embodiments, the WTRU (e.g., UE) may receive a TA value from the target cell in a RAR. According to embodiments, the WTRU (e.g., UE) may receive a TA value from the source cell in a RAR. If the WTRU (e.g., UE) does not receive a RAR in response to transmitting the preamble (e.g. within a prescribed time), the WTRU (e.g., UE) may retransmit a preamble using a higher transmission power.

[0221] According to embodiments, the WTRU (e.g., UE) may store the received TA value to be used later when a reconfigure trigger occurs. The WTRU (e.g., UE) may store the TA value for a limited period of time (e.g. a validity timer) and may trigger or be triggered to perform a new TA acquisition procedure when the time expires.

[0222] According to embodiments, the WTRU (e.g., UE) may receive and / or stored multiple TA values associated with more than one cell.

[0223] According to embodiments the WTRU (e.g., UE) may obtain the TA value of the target cell by measurement.

[0224] If the WTRU (e.g., UE) has stored a valid TA value of a candidate cell when a cell switch is triggered towards that candidate cell (either triggered by the NW using an explicit cell switch command, or triggered by the WTRU (e.g., UE) upon meeting a trigger condition), then the WTRU (e.g., UE) performs a RACH-less handover. For example, the WTRU (e.g., UE) may execute LTM (e.g. apply a pre-configured RRC configuration to a new special cell (SpCell)) upon determining that a measured radio quality of the target cell is above a threshold.

[0225] The WTRU (e.g., UE) may support and be configured with WTRU (e.g., UE)-based TA measurement, whereby the WTRU (e.g., UE) acquires the TA value(s) of the candidate cell(s) by measurement. If the cell switch command does not contain a TA value, and the WTRU (e.g., UE) has acquired a TA measurement, the WTRU (e.g., UE) performs a RACH-less handover if it has been configured to do so by RRC.

[0226] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon any one of the following parameters.

[0227] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a validity timer pre-configured to be used with TA value.

[0228] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a validity timer received with the TA value.

[0229] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a condition on the DL cell timing of the source cell and the DL cell timing of the candidate cell for which TA is received / stored. In one example, a WTRU (e.g., UE) may consider the TA valid while the difference of the DL cell timing of the source and candidate cell is less than a configured threshold. In one example, a WTRU (e.g., UE) may consider the TA valid while the difference of the DL cell timing of the source and candidate cell is within a configured range.

[0230] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a condition on the DL cell timing of the candidate cell. In one example, a WTRU (e.g., UE) may consider the TA valid if the difference of the DL cell timing of the target cell at the time of the TA reception is not different by more than a certain configured value / range than the current DL cell timing of the same target cell.

[0231] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a condition on the WTRU (e.g., UE) mobility. In one example, a WTRU (e.g., UE) may consider the TA valid if it is static (not moving) or moving below a certain configured speed threshold.

[0232] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a condition on the WTRU (e.g., UE) location. In one example, a WTRU (e.g., UE) may consider the TA valid if it has determined that it has not changed its location by more than a certain configured threshold (e.g., x meters) after the TA acquisition.

[0233] A WTRU (e.g., UE) may determine a received / stored TA to be valid based upon a condition that a WTRU (e.g., UE)-based TA measurement is available and a cell quality or beam quality measurement is above a threshold.

[0234] According to embodiments, the WTRU (e.g., UE) may trigger an event when a WTRU (e.g., UE)-based TA acquisition has been completed, for example may transmit a MAC CR, CSI, or other uplink indication to the source cell or the candidate cell when a TA has been obtained based on WTRU (e.g., UE) measurement.

[0235] According to embodiments, the WTRU (e.g., UE) may trigger an event based on a measurement criteria (e.g., RSRP or any of the other triggers listed above), and may send the corresponding report (e.g., only) if a TA has additionally been obtained, for example a TA is available due to a prior WTRU (e.g., UE)-based TA acquisition. According to embodiments, a report or an LTM execution trigger caused due to a measurement based event or trigger may be delayed until a WTRU (e.g., UE)-based TA acquisition is completed. That is, a measurement event (e.g., a beam RSRP is above a threshold) may cause the WTRU (e.g., UE) to initiate a WTRU (e.g., UE)-based TA acquisition, then a trigger is executed when both the measurement event is matched / satisfied and the TA has been obtained.

[0236] According to embodiments, in response to receiving a report from the WTRU (e.g., UE) (e.g., UE-based TA acquisition has been performed and a beam or cell measurement is above a threshold), the network may transmit to the WTRU (e.g., UE) a command to enable conditional LTM evaluation, for example in a MAC CE. The WTRU (e.g., UE) may receive the command, and based on the content of the command may enable conditional LTM evaluation based on determination of one or more measurement conditions.

[0237] The WTRU (e.g., UE) may perform beam refinement on a target cell before or during a handover and before the WTRU (e.g., UE) accesses the target cell, such that a WTRU (e.g., UE) first performs measurement of SSB resources, then selects a subset of CSLRS resources to measure based on the SSB measurements (e.g., based on the best SSB measured). Then the WTRU (e.g., UE) may perform measurements on the selected subset of CSLRS resource and determines a bestCSI-RS resource. The selected best CSI-RS resource can be indicated before a handover takes place (e.g., to a source cell), or upon initial access (e.g., to a target cell), rather than performing the beam refinement only after a connection to a target cell is completed.

[0238] The WTRU (e.g., UE) may report the measurements of the subset of CSI-RS resources using CSI reporting on PUCCH to the source cell. The report may alternatively be transmitted using a MAC CE or an RRC measurement report, or any other type of uplink signaling. The report may contain one or more of: RSRP (beam or cell); RSRQ (beam or cell); cri-RI-PMI-CQI; cri-RI- il; cri-RI-il-CQI; cri-RI-CQI; cri-RSRP; ssb-Index-RSRP; cri-RI-LI-PMI-CQI.

[0239] The WTRU (e.g., UE) may determine, based on a trigger a subset of CSI-RS to measure. For example, the WTRU (e.g., UE) may determine based on a pre-configured association (e.g., configured by RRC) between SSB and CSI-RS resources. The WTRU (e.g., UE) may determine based on an indication of an SSB or determining a best SSB from performed SSB measurements.

[0240] The subset of CSI-RS may be indicated explicitly in a random access response (e.g., using a pointer to one of multiple subsets) or may be indicated implicitly (e.g., the WTRU (e.g., UE) enables a subset of CSI-RS depending on a reported or indicated SSB when the RAR is received). The WTRU (e.g., UE) may alternatively enable the subset of CSI-RS measurements when the WTRU (e.g., UE) receives a PDCCH order triggering early TA acquisition, while the RAR or MAC CE containing a TA in response to the PRACH preamble transmission for TA acquisition activates the configured grant.

[0241] The CSI-RS measurements may be configured temporarily. For example, the WTRU (e.g., UE) may activate CSI-RS measurements for a certain time period, or a certain number of reports, which may be configured or predefined. The WTRU (e.g., UE) may deactivate CSI-RS measurements, for example, when a best SSB changes, or when an SSB or CSI-RS measurement goes below a threshold.

[0242] The WTRU (e.g., UE) may receive an indication to activate a grant from either a source or a target cell this may be e.g., a type 2 configured grant, whereby the first cell configures the grant and the second cell activates the grant, an explicit grant (a direct indication of the grant to use), a pointer to one or more preconfigured grants (e.g., previously configured by RRC).

[0243] An indication of the grant may be a pointer to a configured grant corresponding to a reported SSB, or may be a set of configured grants corresponding to multiple CSI-RS associated with a reported SSB.

[0244] The configured grant activation may be received in a PDCCH order (e.g., triggering TA acquisition), in a MAC CE (e.g., triggering LTM), or in a RAR (e.g., received from the source or the target, containing a TA value to use for RACH-less handover).

[0245] The WTRU (e.g., UE) may autonomously activate a configured grant based on a condition. For example, any of the LTM execution triggers listed in this section.

[0246] For the purpose of the description “SRS” refers to Sounding Reference Signal, and may be a reference signal transmitted by the WTRU (e.g., UE) in the uplink. This may be used by the network (e.g., gNB) to estimate the uplink channel quality. SRS may be used to provide information to the network about multipath fading, scattering, Doppler, and power loss of the transmitted signal. Sounding reference signals are uplink physical signals employed by WTRU (e.g., UE) for uplink channel sounding, including channel quality estimation and synchronization. Unlike Demodulation reference signals (DM-RS), SRS is not associated with any physical uplink channels and they support uplink channel-dependent scheduling and link adaptation. SRS may assist with codebook-based closed-loop spatial multiplexing, control uplink transmit timing, reciprocity-based downlink precoding in multi-user MIMO setups, quasi co-location of physical channels and reference signals.

[0247] In 5G NR, the SRS is transmitted by the WTRU (e.g., UE) for uplink channel sounding, which includes channel estimation and synchronization. An NR-SRS is an uplink orthogonal frequency division multiplexing (OFDM) signal filled with a Zadoff-Chu sequence on different subcarriers. For the purposes of communications, the SRS is used for closed-loop spatial multiplexing, uplink transmitting timing control, and reciprocity multi-user downlink precoding. To utilize the channel sounding function, the SRS must be known by both the WTRU (e.g., UE) and the gNB. The WTRU (e.g., UE) act as a mobile transmitter and gNB act as a base station receiver.

[0248] In future radio systems, for example 6G, a new channel design may be used, for example use of a different sequence than NR, however all of the methods described in this disclosure apply also to any type of uplink signal for performing uplink channel sounding.

[0249] According to embodiments, the WTRU (e.g., UE) may be configured with uplink resources for transmission of a measurement reference signal (e.g., SRS) on one or more target cells. Each of the SRS resources may be associated with a downlink measurement resource, such that the WTRU (e.g., UE) may determine an SRS resource to use based on a condition associated with the downlink measurement. For example, the WTRU (e.g., UE) may transmit using a particular SRS resource if the downlink measurement is above a threshold. The WTRU (e.g., UE) may transmit on up to N SRS resources, corresponding to the best N measurements in the downlink (for example, the best N beams based on SSB measurement on candidate cells). The selection of SRS resource implicitly indicates the best beams measured in the downlink. According to embodiments, the SRS resource includes a payload portion which may include additionalinformation, for example a measurement value (e.g., RSRP). According to embodiments, the WTRU (e.g., UE) may transmit to a particular SRS resource only if a valid uplink synchronization has been determined (e.g., a TA value).

[0250] According to embodiments, the WTRU (e.g., UE) may select one from multiple SRS resources, for example a resource corresponding to the best beam or cell. The WTRU (e.g., UE) may transmit, to the selected one resource, an indication including measurements from a best one or more beams or cells. According to embodiments, the WTRU (e.g., UE) transmits measurement information and uplink SRS only to the cell (or beam, or TRP) which is the most likely target for mobility. Additional measurements (e.g., of the second best cell) may be used by the network to determine additional cells to enable (e.g., SCells).

[0251] According to embodiments, the one or more SRS resources are transmitted using a single uplink configuration (e.g., a common uplink channel). That configuration may be possible to receive by more than one potential target cell.

[0252] According to embodiments, the WTRU (e.g., UE) may be identified implicitly by use of WTRU (e.g., UE) dedicated resources, or may include a temporary identifier (e.g., RNTI which is unique within the mobility area) in a payload portion of the uplink signal.

[0253] According to embodiments, the uplink SRS resource is selected based on certain conditions. For example, an absolute radio measurement threshold for a downlink measurement may be used to determine whether to transmit on an associated uplink resource. As another example, there may be a condition employed to change from transmitting on a first SRS to transmitting on a second SRS, for example a downlink resource associated with the second SRS becomes better than a downlink resources associated with the first SRS by a relative threshold.

[0254] According to embodiments, the SRS “resource” may be an SRS resource set. For example, the WTRU (e.g., UE) may perform an uplink beam sweep using the SRS resource set, based on determining an SRS resource set to use from the downlink measurements (e.g., a best one or more SSB). The network may determine, based on the SRS resource set transmissions, a best fine beam. In other words, the uplink SRS transmission can be used to perform beam refinement ahead of switching cell or TRP in order to provide improved throughput during and after a cell switch.

[0255] According to embodiments, the WTRU (e.g., UE) may switch between mobility modes. For example, a first (e.g., downlink based) mobility mode, whereby the WTRU (e.g., UE) reports downlink measurements to one or more network nodes may be used under certain conditions. Once it is determined that, for example, a cell switch will happen soon (e.g., based on serving cell and / or neighbour cell measurements) then the WTRU (e.g., UE) may determine (based on a condition oron an explicit indication) to transmit uplink SRS and may stop reporting downlink measurements. Conditions may for example, include being inside a particular area (e.g., RAN area, list of cells, etc.), when a particular traffic type is used (e.g., an XR service versus a delay tolerant service), RRC state, for example one or more RRC states may be defined whereby the WTRU (e.g., UE) operates in downlink mobility mode in one state, and uplink mobility mode in another state. A WTRU (e.g., UE) may initially use downlink measurements and report to the source until a timing for the target is known, for example when a TA value is determined then the WTRU (e.g., UE) may transmit uplink signals to the cell or TRP for which the TA has been acquired.

[0256] An SRS transmission may be initiated, for example, when the WTRU (e.g., UE) measured discovery signals for “OFF” cells (e.g., cells powered off due to network energy saving).

[0257] An uplink signal may be transmitted when one of the low power beams / cells in an NonTerrestrial Networks (NTN) is determined as best, for example after applying a compensation (e.g., offset) for lower power downlink transmission in criteria determination.

[0258] An uplink mobility mode may be used when a periodicity of SSB transmission changes, for example due to network energy saving.

[0259] The SRS transmission may be combined with a positioning signal (e.g., SRSP) in order to perform uplink based mobility measurements and positioning measurements simultaneously.

[0260] The WTRU (e.g., UE) may receive, in configuration info, one or more of the following parameters associated with SRS configuration or SRS sub-configuration:

[0261] The WTRU (e.g., UE) may receive, in configuration info, Indexes / IDs of one or more SRS resource sets or resources.

[0262] The WTRU (e.g., UE) may receive, in configuration info, SRS resources: (1) Time domain resources: Number of symbols per slot (e.g., 1, 2, 4 symbols per slot), start offset symbol, repetition factor; (2) Frequency domain resources: Number of physical resource blocks (PRBs), start offset PRB, repetition factor. Each SRS sub-config may include resources which may or may not overlap with the resources in other SRS sub-configs, for example. In an example, the resources allocated for one or more SRS sub-configs may correspond to an SRS resource pool. The WTRU (e.g., UE) may be configured to select the SRS resources from the pool for SRS transmission. When selecting the SRS resources, the WTRU (e.g., UE) may transmit an indication to NW (e.g., in UCI, MAC CE), indicating the used / unused SRS resources prior to performing the SRS transmission, for example.

[0263] The WTRU (e.g., UE) may receive, in configuration info, SRS ports: Number of Tx and / or Rx ports.

[0264] The WTRU (e.g., UE) may receive, in configuration info, Resource type: e.g., Corresponds to the time-domain behavior of SRS resource configuration which may be periodic, semi-persistent, or aperiodic.

[0265] The WTRU (e.g., UE) may receive, in configuration info, Usage type: e.g., WTRU (e.g., UE) may be configured with any of beam management, codebook, non-codebook, antenna switching.

[0266] The WTRU (e.g., UE) may receive, in configuration info, Slot level periodicity and slot level offset, e.g., for periodic or semi-persistent SRS

[0267] The WTRU (e.g., UE) may receive, in configuration info, SRS bandwidth

[0268] The WTRU (e.g., UE) may receive, in configuration info, Frequency hopping info. The WTRU (e.g., UE) may be configured with one or more hopping patterns that may be applied over a set of SRS resources in any of the time, frequency, and spatial domains. In a hopping pattern, a partial set of SRS resources in frequency domain (e.g., PRBs) may be used in each time domain resource (e.g., symbol) for transmitting SRS using different spatial relation. Such hopping pattern may correspond to one or more NES adaptation / state, for example.

[0269] The WTRU (e.g., UE) may receive, in configuration info, Guard period: Number of symbols / slots / ms. The WTRU (e.g., UE) may apply the guard period when switching between different SRS sub-configs or when switching between different Rx ports for SRS transmission.

[0270] The WTRU (e.g., UE) may receive, in configuration info, SRS transmission comb pattern info. A parameter may include transmission comb value, which may be associated with the gap in terms of the number of PRBs or number of symbols / slots between two SRS resources in the frequency and / or time domains. Each SRS sub-config may include one or more SRS comb patterns, where each pattern may be associated different set of parameters (e.g., offset value, cyclic shift) and / or SRS resources in time / frequency / spatial domains. A comb pattern may include SRS resource in different symbols (within one slot or across multiple slots) or slots, where the SRS in different symbols / slots may be transmitted with different UL Tx spatial filter. When SRS is configured with periodic or semi-persistent SRS resources, the SRS comb pattern (e.g., using resources in time, frequency, spatial domains) may be repeated in each period. When SRS is configured with aperiodic SRS resources, the SRS transmission burst may consist of SRS resources in time, frequency, spatial domains.

[0271] The WTRU (e.g., UE) may receive, in configuration info, Comb offset hopping pattern with repetition

[0272] The WTRU (e.g., UE) may receive, in configuration info, SRS sequence ID

[0273] The WTRU (e.g., UE) may receive, in configuration info, Power control (PC) parameters. PC parameters may include alpha, pO, pathloss reference RS, SRS power control adjustment states (e.g., closed loop factor). The WTRU (e.g., UE) may transmit SRS upon applying the set of power control parameters associated with the indicated SRS sub-configs. For example, the SRS sub- configs and the associated set of power control parameters to apply may be determined based on certain conditions (e.g., measurements of pathloss DL).

[0274] The WTRU (e.g., UE) may receive, in configuration info, Reference resource ID for spatial relation (e.g., SS / PBCH block, CSI-RS, SRS); e.g., WTRU (e.g., UE) may use the configured or indicated reference resource determining UL TX spatial filter; e.g., Reference resource for spatial relation may or may not be configured when the WTRU (e.g., UE) is configured with unifiedTCI-StateType or signaled with TCI state.

[0275] The WTRU (e.g., UE) may receive, in configuration info, TCI state info. The WTRU (e.g., UE) may be configured with parameters SRS-UL-TCI state or SRS-DL-or-joint-TCI state. SRS-UL-TCI state may refer to a TCI state in the parameter UL-TCI-StateList when the parameter unifiedTCI-StateType is configured as ‘separate’. SRS-DL-or-joint-TCI state may refer to a TCI state in the parameter dl-ORJointTCI-State-List when the parameter unifiedTCI-StateType is configured as ‘joint’. The WTRU (e.g., UE) may or may not be configured with SRS TCI state info when configured with the parameter followUnifiedTCI-StateSRS.

[0276] The WTRU (e.g., UE) may be configured with any of the following properties associated with TCI states: (1) property associated with quantity; (2) property associated with SRS config / sub-config; and (3) property associated with triggering.

[0277] In the property associated with quantity one or more TCI states (e.g., indicated by index / ID) may be associated with a set or pool (e.g., indicated by a pool ID). Each TCI state may be associated with one or more reference signals (e.g., SSB, CSI-RS, TRS, SRS) as a QCL source.

[0278] In the property associated with SRS config / sub-config, each SRS config / sub-config may be associated with one or more TCI states. One or more SRS configs / sub-configs be associated with a common pool of TCI states. TCI states in different SRS sub-configs may be nonoverlapping, e.g., SRS subconfigl may be configured with TCI states {TCI1, TCI2} and SRS sub- config2 may be configured with TCI states {TCI3, TCI4}.

[0279] In the property associated with triggering the one or more TCI states may be activated / deactivated upon configuration (e.g., viaRRC signaling) or with dynamic signaling (e.g., MAC CE and / or DCI). The granularity of TCI state (de)activation may be done on the basis of per TCI state, per-TCI state pool, per SRS-config, per SRS-sub-config

[0280] The parameters associated with TCI states may include any of the following: (1) QCL sources; (2) QCL types; and (3) validity conditions

[0281] QCL sources may include any of: (1) IDs / indexes (e.g., SSB index, CS RS resource ID, SRS resource ID); (2) Type of resource / signal (e.g., periodic, semi -persistent, aperiodic, on- demand, slim / lean). E.g., each TCI state may be associated with a DL RS resource / beam as a QCL source or reference signal / beam for determining the spatial relation for SRS

[0282] QCL types may include e.g. Type A (doppler shift, doppler spread, average delay, delay spread), Type B (doppler shift, doppler spread), Type C (average delay, doppler shift), Type D (spatial Rx)

[0283] The validity conditions associated with one or more TCI states may include time validity, location / spatial validity, or (de)activation signaling. E.g., Time validity may indicate the validity duration from the reception of the configuration or triggering indication (e.g., start of a timer) to the end of the duration (e.g., end of a timer) during which the WTRU (e.g., UE) may assume the configured / indicated TCI state(s) are valid. E.g., Location / spatial validity may indicate the ID list of the cells / TRPs / NW nodes whose coverage in which the WTRU (e.g., UE) may assume the configured / indicated TCI state(s) are valid. E.g., The WTRU (e.g., UE) may assume a TCI state as valid when receiving signaling indicating TCI state activation, and as invalid when receiving signaling indicating TCI state deactivation. Any of the validity conditions above may be applicable for determining the validity of the SRS sub-configs, for example. When any of the validity conditions are not met, the WTRU (e.g., UE) may release the TCI states and / or send a request indication for new / updated TCI states.

[0284] The WTRU (e.g., UE) may receive, in configuration info, any of the following events, conditions and / or threshold values for selecting or using any of the SRS sub-configs, SRS resources, and TCI states for SRS transmission: (1) measurement threshold values; (2) timing info; (3) transmission power; (4) priority; and (2) events.

[0285] The Measurement threshold values may correspond to RSRP, RSRQ, SINR, CQI, etc. For example, the WTRU (e.g., UE) may select an SRS sub-config, when the measurements made on an associated DL RS / TCI state is higher than a RSRP threshold.

[0286] The timing info my include a start time threshold: For example, an SRS resource may be used if it begins no later than a start time T1 symbol s / slots / ms after the WTRU (e.g., UE) receives an indication associated with activation of the SRS sub-config to which the SRS resource belongs. The timing info my include an end time threshold: For example, an SRS resource may be used if it ends no earlier than an end time T2 symbols / slots / ms after the WTRU (e.g., UE) receives an indication associated with activation of the SRS sub-config to which the SRS resource belongs.The timing info my include a time window (e.g., start offset time, length): For example, the WTRU (e.g., UE) may use one or more SRS sub-configs that may be accommodated within the time window for SRS transmission.

[0287] The transmission power may include a Tx power threshold: For example, the WTRU (e.g., UE) may use one or more SRS resources (e.g., in time domain and / or frequency domain) for SRS transmission if the transmit power (e.g., total power in SRS resources in a transmission instance) is less than a first Tx power threshold value and / or greater than a second Tx power threshold value. The transmission power may include a power spectral density (PSD) threshold: For example, the WTRU (e.g., UE) may use one or more SRS resources (e.g., in time domain and / or frequency domain) for SRS transmission if the PSD over the SRS resources is less than a first PSD threshold value and / or greater than a second PSD threshold value.

[0288] One or more priority values may be associated with any of SRS sub-configs, SRS resources, SRS parameters (e.g., antenna switching, codebook type) and TCI states. For example, the WTRU (e.g., UE) may use certain SRS sub-configs, when the priority associated with the SRS sub-configs is higher than a priority threshold value and / or lower than another priority threshold value.

[0289] The events may include any of a: change of RSRP measurements of DL RS (e.g., when NW does spatial domain (SD) adaptation; or due to mobility); indication of TCI state(s) changes; and detection of RRM / beam management (BM) / mobility events (e.g., HO, RLM, RLF events)

[0290] In some potential designs, the presence of a “cell” may be hidden from the WTRU (e.g., UE) - for example, the network may adapt all of part of its configuration to the configuration the WTRU (e.g., UE) may have been provided with, or individual beams are configured to the WTRU (e.g., UE) without the WTRU (e.g., UE) needing to have visibility of the physical location of those beams. By enabling large scale coordination of TRPs a WTRU (e.g., UE) may experience cell center-like data transmission and reception across the network. For moving WTRUs (e.g., UEs), the serving TRPs may be dynamically selected and may be enabled without indicating a cell switch to the WTRU (e.g., UE) (e.g., the network may adapt to the WTRU (e.g., UE) configuration). In some cases, the different TRPs within a “hyper-cell” may transmit identical downlink synchronization signals, or transmit using a single resource configuration. The WTRU (e.g., UE) may be configured to measure “resources” in the downlink or transmit using “resources” in the uplink, which are common to more than one TRP and which the WTRU (e.g., UE) does not need to know the physical location of the signals. In this case, an uplink SRS may be needed for the network to determine the best uplink (for example, some scenarios such as uplink-only TRP may require this).

[0291] The network may perform measurements on the WTRUs (e.g., UEs) transmitted SRS on one or multiple TRPs. According to embodiments, the WTRU (e.g., UE) selects SRS resources for the TRPs which provide the best measured downlink beams. The WTRU (e.g., UE) may transmit using more than one SRS resource representing multiple potential target TRPs. The WTRU (e.g., UE) may include an indication of a downlink measurement value (e.g., RSRP). The WTRU (e.g., UE) may include an indication of only the downlink measurement associated with the SRS resource selection, or may include an indication of multiple downlink measurements (e.g., the best N beams).

[0292] The network may perform uplink measurements on one or more TRPs. The network may co-ordinate measurements, for example by exchanging measurement information between network node or with a central node. The network may determine, based on the measurement coordination, to select a new TRP or cell for the WTRU (e.g., UE). According to embodiments, the WTRU (e.g., UE) may transmit uplink SRS to only one TRP and includes downlink measurements, and the network may need to coordinate (e.g., only) between the target and source TRP, rather than the multiple potential targets.

[0293] According to embodiments, the network may determine, based on measuring SRS resource set transmissions (e.g., uplink beam sweep) using resources determined by the WTRU (e.g., UE) based on downlink measurements, a best fine beam to configure the WTRU (e.g., UE) with upon cell or TRP change.

[0294] According to embodiments, an intermediate node (e.g., a relay) may be employed to act as a network node. The intermediate node may perform measurements of the WTRU (e.g., UE) transmitted uplink SRS and convey measurements to a traditional (e.g., fixed TRP) network node.

[0295] According to embodiments, a network node may be configured to operate as an uplink only TRP.

[0296] According to embodiments, the network node may be deployed on an arial vehicle (e.g., drone) or on a satellite (e.g., NTN cell)

[0297] A cell switch command may be received in a downlink signal such as DCI, MAC CE. This cell switch command may be receive from a source cell (e.g., like NR) or from a target cell (e.g., a cell determined to be the best cell). According to embodiments, for example when “hyper cell” is used, the cell may be switch without notifying the WTRU (e.g., UE), but rather the network configures, based on uplink measurements, to use a new TRP with the same configuration as the previous one.

[0298] According to embodiments, an uplink and a downlink connection may be separately managed. For example, mobility based on reported downlink measurements may be used tomanage downlink channels and TRPs, while the network selects uplink channels and TRPs based on uplink measurement signals.

[0299] The WTRU can transmit uplink reference signals for network-based measurement mobility decision. Rather than performing DL measurements and reporting to the source or determining a conditional handover trigger based on the DL measurements, the WTRU (e.g., UE) may be configured to transmit uplink reference signal (e.g. SRS) towards one or more target cells with an indication to the target of DL measurements. The network may co-ordinate the uplink measurements taken at the gNB / TRP side, and may make the handover decision based on this.

[0300] Methods and apparatus for uplink measurement-based mobility are provided. In one embodiment, the WTRU (e.g., UE) may be configured to receive a configuration of one or more LTM candidate cells, including downlink measurement resources (SSB, CSLRS, etc.) and including uplink SRS resources. Uplink SRS resources may include SRS portion and payload portion (payload portion to indicate DL measurement). Uplink SRS resource set (SRS resources to use to perform an uplink beam sweep) may be associated with different DL measurement conditions (e.g. specific resource to use when DL measurement is above / below threshold; specific resource to indicate a best beam in DL). Uplink SRS resources may be defined for each target cell and / or beam, (an alternative may be uplink resources that are common to more than one cell)

[0301] In one embodiment, the WTRU (e.g., UE) may be configured to perform and / or evaluate measurements of the downlink beams on one or more configured LTM candidates. The WTRU (e.g., UE) may be configured to determine TA values for one or more target cells (needed if e.g. SRS resources are similar to NR, and defined per cell, may not be needed if UL channel is common between cells)

[0302] In one embodiment, the WTRU (e.g., UE) may be configured to activate SRS transmission to the one or more targets.

[0303] In one embodiment, the WTRU (e.g., UE) may be configured to report DL measurements to source. The WTRU (e.g., UE) may receive an indication to activate SRS transmission on target cell resources (e.g. MAC CE, PDCCH order) so that handover decision can finally be made based on DL reported and UL measurements at target.

[0304] In one embodiment, the WTRU (e.g., UE) may be configured to determine, based on a condition, to initiate uplink SRS transmission to one or more candidate cells. Condition may be all cells with a beam above threshold, etc. The WTRU may determine the SRS resources to use, based on the condition (e.g. use SRS resources on each cell corresponding to the best DL beam on that cell).

[0305] In one embodiment, the WTRU (e.g., UE) may be configured to transmit, to the one or more candidate target cells, using the determined resources, an indication of DL measurements of one or more cells / beams, and an SRS, and an indication identifying the WTRU (e.g., UE). The WTRU (e.g., UE) may be identified implicitly by use of WTRU (e.g., UE) dedicated resources, or may include a temporary identifier (e.g. RNTI which is unique within the mobility area) in a payload portion of the uplink signal. Some part of DL measurement may be implied by resource selection (e.g. best beam is implied by resource selection). The reporting of other beams than the best one, and explicit measurement values for beams or cells may be sent in the payload portion.

[0306] In one embodiment, the WTRU (e.g., UE) may be configured to Receive (from source or target cell) an indication to perform cell switch towards a target cell (may be part of candidate cell list).

[0307] In one embodiment, the WTRU (e.g., UE) may be configured to Perform reconfiguration and transmit a handover complete on the target cell.

[0308] The proposed procedure may improve mobility latency, interruption and robustness while providing high level of network control, because measurements can be indicated to a target cell, and a target cell can determine the best uplink beam then even in case of failure at the source, a handover can be successfully completed because the need to report measurements to the source or to configure WTRU (e.g., UE)-based decision is eliminated.

[0309] The proposed procedure may allow a reduction of signalling exchange during handover, mobility decision made based on reference signal transmission and measurements.

[0310] The proposed procedure may enable new deployment scenarios such as uplink only TRP / cell, large DL-UL imbalance, different bands in UL and DL, difference cells providing DL and UL coverage.

[0311] The proposed procedure may enable faster beam refinement on a target cell, enabling high throughput upon change of serving cell - since the TRP / NW node receives uplink SRS ahead of cell switch, it can determine the best fine beam to use for the WTRU (e.g., UE).

[0312] FIG. 3 illustrates an example scenario of SRS transmission in which a UE in a UE in a serving cell finds candidate DL in other cells, where one candidate DL is too low, another DL meets a threshold and is the best candidate, while a third DL meets a threshold and is the second best candidate.

[0313] FIG. 4 shows an example signaling exchange 400 to support mobility.

[0314] In the first step, the WTRU (e.g., UE) may be pre-configured with the configurations corresponding to target / candidate cells. Depending on the system design, this may be one or more configurations to apply when performing a cell switch to those cells (e.g., similar to NR), or thismay be one or more reference signal configurations, channel, or resource configurations. According to embodiments, the WTRU (e.g., UE) may receive a single configuration applicable to more than one cell or TRP, while the change of physical cell or TRP is transparent to the WTRU (e.g., UE). In any case, the received configurations may apply to one or more candidate physical cells. The WTRU (e.g., UE) may receive downlink measurement resource configurations (e.g., resources corresponding to beams on the one or more candidate cells or TRPs, such as SSB, CSI- RS, etc.) and a configuration of uplink resources (e.g., SRS resources) with an association to the one or more candidate cells or TRPs, and an association with the configured downlink measurement resources. Measurement parameters may be configured, for example measurement filtering, periodicity, beam averaging, and so on. Conditions may also be configured, for example a threshold radio quality to compare the measured radio quality of the one or more measurement resources.

[0315] In the second step, the WTRU (e.g., UE) may perform the measurements on the configured downlink measurement resources. The measurement may, for example, correspond to any of the measurement types described above. For example, in NR or in an example system similar to that of NR, the WTRU (e.g., UE) may perform measurements of downlink reference signals (e.g., SSB, CSI-RS) corresponding to one or more target cells.

[0316] In the third step, for example based on evaluation of the downlink measurements, the WTRU (e.g., UE) may initiate transmission of one or more uplink reference signals. If the WTRU (e.g., UE) determines that a cell or beam quality is above the corresponding threshold, then the WTRU (e.g., UE) may initiate SRS transmission on one or more associated resources (e.g., associated with the downlink resource, beam or cell). The WTRU (e.g., UE) may initiate SRS transmission to multiple target cells (or e.g., target beams, TRPs, etc.). By transmitting using one or more uplink resources associated with the determined one or more downlink resources with the best radio quality, the network (e.g., a target cell) can implicitly know the best beam or cell in the downlink. A payload portion may be transmitted with the reference signal, for example to indicate explicit radio quality measurements of the best beam and / or non-best beams (for example, RSRP of the best N downlink beams).

[0317] Measurements of the transmitted uplink reference signals may be performed at the network. For example, one or more uplink SRS transmissions may be received at the network on one or more cells or TRPs, as described above. Upon evaluating the uplink and / or reported downlink signal quality measurements, the network may determine to perform a cell switch (e.g., reconfiguration of the WTRU (e.g., UE) to connect to a new one or more cells or TRPs). For example, following the network determining to perform a cell switch, an indication may be sentto the WTRU (e.g., UE), for example via the source cell, for example in a MAC CE, indicating the new cell. The WTRU (e.g., UE) may receive this indication, and performs reconfiguration to the new cell (or cells). The WTRU (e.g., UE) may transmit an indication in the uplink to the new cell in order to confirm completion of the procedure.

[0318] FIG. 5 is a flowchart illustrating a representative method 500 implemented by a WTRU 102. Referring to FIG. 5, the representative method 500 may include, at block 510, receiving, for example from the NW, first information indicating any of: (1) one or more candidate target cells, (2) downlink measurement resources and (3) uplink resources.

[0319] At block 520, the representative method 500 may include performing downlink measurements on the downlink measurement resources.

[0320] At block 530, the representative method 500 may include based on the downlink measurements, transmitting, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources.

[0321] According to certain embodiments, the representative method 500 may include any of the following steps: receiving an indication to perform cell switch towards a target cell; and transmitting second information indicating a handover completion on the target cell.

[0322] According to certain embodiments, the target cell is from the one or more candidate target cells.

[0323] According to certain embodiments, the uplink resources include sounding reference signal (SRS) portion and payload portion.

[0324] According to certain embodiments, the uplink resources are associated with one or more downlink measurement conditions.

[0325] According to certain embodiments, the uplink resources are associated with one or more candidate target cells.

[0326] According to certain embodiments, the one or more uplink reference signals include third information identifying the WTRU.

[0327] According to certain embodiments, the one or more uplink reference signals include the downlink measurements.

[0328] According to certain embodiments, the payload portion include the downlink measurements.

[0329] REFERENCES

[0330] The following references are incorporated herein by reference in their entireties.

[0331] [1] RP -234036 New WID: NR mobility enhancements Phase 4.

[0332] [2] 3GPP TS 38.300 v!8.0.0 section 9.2.3.5.

[0333] Although features and elements are provided above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations may be made without departing from its spirit and scope, as will be apparent to those skilled in the art. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly provided as such. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods or systems.

[0334] The foregoing embodiments are discussed, for simplicity, with regard to the terminology and structure of infrared capable devices, i.e., infrared emitters and receivers. However, the embodiments discussed are not limited to these systems but may be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves such as acoustic waves.

[0335] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used herein, the term "video" or the term "imagery" may mean any of a snapshot, single image and / or multiple images displayed over a time basis. As another example, when referred to herein, the terms "user equipment" and its abbreviation "UE", the term "remote" and / or the terms "head mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of a number of embodiments of a WTRU; (iii) a wireless-capable and / or wired-capable (e.g., tetherable) device configured with, inter alia, some or all structures and functionality of a WTRU; (iii) a wireless-capable and / or wired-capable device configured with less than all structures and functionality of a WTRU; or (iv) the like. Details of an example WTRU, which may be representative of any WTRU recited herein, are provided herein with respect to FIGs. 1 A-1D. As another example, various disclosed embodiments herein supra and infra are described as utilizing a head mounted display. Those skilled in the art will recognize that a device other than the head mounted display may be utilized and some or all of the disclosure and various disclosed embodiments can be modified accordingly without undue experimentation. Examples of suchother device may include a drone or other device configured to stream information for providing the adapted reality experience.

[0336] In addition, the methods provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer- readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0337] Variations of the method, apparatus and system provided above are possible without departing from the scope of the invention. In view of the wide variety of embodiments that can be applied, it should be understood that the illustrated embodiments are examples only, and should not be taken as limiting the scope of the following claims. For instance, the embodiments provided herein include handheld devices, which may include or be utilized with any appropriate voltage source, such as a battery and the like, providing any appropriate voltage.

[0338] Moreover, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices that include processors are noted. These devices may include at least one Central Processing Unit ("CPU") and memory. In accordance with the practices of persons skilled in the art of computer programming, reference to acts and symbolic representations of operations or instructions may be performed by the various CPUs and memories. Such acts and operations or instructions may be referred to as being "executed," "computer executed" or "CPU executed."

[0339] One of ordinary skill in the art will appreciate that the acts and symbolically represented operations or instructions include the manipulation of electrical signals by the CPU. An electrical system represents data bits that can cause a resulting transformation or reduction of the electrical signals and the maintenance of data bits at memory locations in a memory system to thereby reconfigure or otherwise alter the CPU's operation, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to or representative of the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs and that other platforms and CPUs may support the provided methods.

[0340] The data bits may also be maintained on a computer readable medium including magnetic disks, optical disks, and any other volatile (e.g., Random Access Memory (RAM)) or non-volatile (e.g., Read-Only Memory (ROM)) mass storage system readable by the CPU. The computer readable medium may include cooperating or interconnected computer readable medium, which exist exclusively on the processing system or are distributed among multiple interconnected processing systems that may be local or remote to the processing system. It should be understood that the embodiments are not limited to the above-mentioned memories and that other platforms and memories may support the provided methods.

[0341] In an illustrative embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0342] There is little distinction left between hardware and software implementations of aspects of systems. The use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software may become significant) a design choice representing cost versus efficiency tradeoffs. There may be various vehicles by which processes and / or systems and / or other technologies described herein may be effected (e.g., hardware, software, and / or firmware), and the preferred vehicle may vary with the context in which the processes and / or systems and / or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and / or firmware vehicle. If flexibility is paramount, the implementer may opt for a mainly software implementation. Alternatively, the implementer may opt for some combination of hardware, software, and / or firmware.

[0343] The foregoing detailed description has set forth various embodiments of the devices and / or processes via the use of block diagrams, flowcharts, and / or examples. Insofar as such block diagrams, flowcharts, and / or examples include one or more functions and / or operations, it will be understood by those within the art that each function and / or operation within such block diagrams, flowcharts, or examples may be implemented, individually and / or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In an embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, may be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g.,as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and / or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein may be distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, a computer memory, etc., and a transmission type medium such as a digital and / or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.).

[0344] Those skilled in the art will recognize that it is common within the art to describe devices and / or processes in the fashion set forth herein, and thereafter use engineering practices to integrate such described devices and / or processes into data processing systems. That is, at least a portion of the devices and / or processes described herein may be integrated into a data processing system via a reasonable amount of experimentation. Those having skill in the art will recognize that a typical data processing system may generally include one or more of a system unit housing, a video display device, a memory such as volatile and non-volatile memory, processors such as microprocessors and digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices, such as a touch pad or screen, and / or control systems including feedback loops and control motors (e.g., feedback for sensing position and / or velocity, control motors for moving and / or adjusting components and / or quantities). A typical data processing system may be implemented utilizing any suitable commercially available components, such as those typically found in data computing / communication and / or network computing / communication systems.

[0345] The herein described subject matter sometimes illustrates different components included within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality may be achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved,irrespective of architectures or intermedial components. Likewise, any two components so associated may also be viewed as being "operably connected", or "operably coupled", to each other to achieve the desired functionality, and any two components capable of being so associated may also be viewed as being "operably couplable" to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and / or physically interacting components and / or wirelessly interactable and / or wirelessly interacting components and / or logically interacting and / or logically interactable components.

[0346] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0347] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, where only one item is intended, the term "single" or similar language may be used. As an aid to understanding, the following appended claims and / or the descriptions herein may include usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim including such introduced claim recitation to embodiments including only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." Further, the terms "any of' followed by a listing of a plurality of items and / or a plurality of categories of items, as used herein, are intended to include "any of," "any combination of," "any multiple of," and / or "any combination of multiples of the items and / or the categories of items, individually or in conjunction with other items and / or other categories of items. Moreover, as used herein, the term "set" is intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero. And the term "multiple", as used herein, is intended to be synonymous with "a plurality".

[0348] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0349] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein may be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," "greater than," "less than," and the like includes the number recited and refers to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

[0350] Moreover, the claims should not be read as limited to the provided order or elements unless stated to that effect. In addition, use of the terms "means for" in any claim is intended toinvoke 35 U.S.C. § 112, 6 or means-plus-function claim format, and any claim without the terms "means for" is not so intended.

Claims

CLAIMSWhat is claimed is:

1. A method implemented in a wireless transmit / receive unit, WTRU, the method comprising: receiving first information indicative of one or more candidate target cells, downlink measurement resources and uplink resources; performing downlink measurements on the downlink measurement resources to obtain measurement results; and transmitting, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources, the one or more uplink reference signals comprising information indicative of the measurement results.

2. The method of claim 1, comprising: receiving an indication to perform cell switch towards a target cell; and transmitting second information indicating a handover completion on the target cell.

3. The method of claim 2, wherein the target cell is from the one or more candidate target cells.

4. The method of any of claims 1-3, wherein the uplink resources include a sounding reference signal (SRS) portion and a payload portion.

5. The method of any of claims 1-4, wherein the uplink resources are respectively associated with one or more downlink measurement conditions.

6. The method of any of claims 1-5, wherein the uplink resources are respectively associated with one or more candidate target cells.

7. The method of any of claims 4-6, wherein the payload portion comprises the downlink measurements.

8. The method of any of claims 1-7, wherein the one or more uplink reference signals comprises information identifying the WTRU.

9. The method of claim 8, wherein the information identifying the WTRU is a temporary identifier.

10. The method of claim 8, wherein the information identifying the WTRU is implied by use of the uplink resources.

11. The method of any of claims 1-10, wherein the information indicative of the measurement results is implied by a selection of the one or more uplink resources.

12. The method of any of claims 1-11, wherein transmitting the one or more uplink reference signals is activated by reception of an indication to transmit the one or more uplink reference signals.

13. The method of any of claims 1-12, wherein transmitting the one or more uplink reference signals is activated by fulfilment of a condition.

14. The method of claim 13, wherein the one or more uplink reference signals are transmitted to candidate target cells that fulfil the condition, the condition being that the measurement results for a respective beam of a candidate target cell are above a given value.

15. A wireless transmit / receive unit, WTRU, comprising at least one processor configured to: receive first information indicative of one or more candidate target cells, downlink measurement resources and uplink resources; perform downlink measurements on the downlink measurement resources to obtain measurement results; and transmit, to the one or more candidate target cells, one or more uplink reference signals on the uplink resources, the one or more uplink reference signals comprising information indicative of the measurement results.

16. The WTRU of claim 15, wherein the at least one processor is configured to: receive an indication to perform cell switch towards a target cell; and transmit second information indicating a handover completion on the target cell.

17. The WTRU of claim 16, wherein the target cell is from the one or more candidate target cells.

18. The WTRU of any of claims 15-17, wherein the uplink resources include a sounding reference signal (SRS) portion and a payload portion.

19. The WTRU of any of claims 15-18, wherein the uplink resources are respectively associated with one or more downlink measurement conditions.

20. The WTRU of any of claims 15-19, wherein the uplink resources are respectively associated with one or more candidate target cells.

21. The WTRU of any of claims 18-20, wherein the payload portion comprises the downlink measurements.

22. The WTRU of any of claims 15-21, wherein the one or more uplink reference signals comprises information identifying the WTRU.

23. The WTRU of claim 22, wherein the information identifying the WTRU is a temporary identifier.

24. The WTRU of claim 22, wherein the information identifying the WTRU is implied by use of the uplink resources.

25. The WTRU of any of claims 15-24, wherein the information indicative of the measurement results is implied by a selection of the one or more uplink resources.

26. The WTRU of any of claims 15-25, wherein the at least one processor is configured to: transmit the one or more uplink reference signals upon reception of an indication to transmit the one or more uplink reference signals.

27. The WTRU of any of claims 15-26, wherein the at least one processor is configured to: transmit the one or more uplink reference signals upon fulfilment of a condition.

28. The WTRU of claim 27, wherein the at least one processor is configured to: transmit the one or more uplink reference signals to candidate target cells that fulfil the condition, the condition being that the measurement results for a respective beam of a candidate target cell are above a given value.

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