PRACH transmission related to MAC CE and PDCCH orders

Abstract

Systems, methods, and means related to Physical Random Access Channel (PRACH) transmission in MAC CE and Physical Downlink Control Channel (PDCCH) order are described herein. A device (e.g., a wireless transmit / receive unit (WTRU)) may perform (e.g., be configured to perform) one or more actions. The device may receive configuration information indicating two sets of cells and random access information associated with each set of cells. The device may receive an indication to select one of the received sets of cells. The device may determine one or more random access preambles, resources, and / or parameters associated with cells (e.g., each cell) in the selected set of cells based on the configuration information and the indication. The device may (e.g., subsequently) receive an indication to transmit a PRACH transmission to a cell in the selected set of cells. The device may transmit the PRACH transmission to the indicated cell.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 445,364, filed February 14, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Mobile communications using wireless communication continues to evolve. The fifth generation is sometimes called 5G. Previous (legacy) generations of mobile communications may be, for example, the fourth generation (4G) of LTE (Long Term Evolution). Summary of the Invention

[0003] Described herein are systems, methods, and means relating to Physical Random Access Channel (PRACH) transmission in Medium Access Control (MAC) channel element (CE) and Physical Downlink Control Channel (PDCCH) order.

[0004] A device (e.g., a wireless transmit / receive unit (WTRU)) may perform (e.g., be configured to perform) one or more actions. The device may receive configuration information indicating two sets of cells and random access information associated with each set of cells. The device may receive an indication (e.g., via a MAC CE) to select one of the received sets of cells. The device may determine, based on the configuration information and the indication, one or more random access preambles, resources, and / or parameters associated with a cell (e.g., each cell) in the selected set of cells. The device may (e.g., subsequently) receive an indication (e.g., via a PDCCH transmission), for example, to transmit a PRACH transmission to a cell in the selected set of cells. The device may transmit a PRACH transmission to the indicated cell. The device may use the determined one or more random access preambles, resources, and / or parameters associated with that cell when transmitting the PRACH transmission.

[0005] The device can receive a timing advance value, for example, in response to sending a PRACH transmission to the indicated cell. The device can associate the timing advance value with the indicated cell and / or a set of selected cells. The device can transmit another PRACH transmission (e.g., a future PRACH transmission) to that cell based on the timing advance value.

[0006] For example, the WTRU may determine the physical cell identity (PCI) and / or SSB (e.g., beam or spatial filter) to use for transmission to each cell in the set of cells based on the received indication (e.g., an indication received on the MAC CE).

[0007] An example device may include a processor configured to perform one or more actions. For example, a device (e.g., a WTRU) may receive configuration information indicating one or more sets of cells and random access information associated with the one or more sets of cells. The device may receive an indication of the set of cells, where the set of cells is a collection of one or more cell sets. The device may receive an indication to transmit one or more Physical Random Access Channel (PRACH) transmissions to the set of cells, where the indication to transmit one or more PRACH transmissions to the set of cells is received via a Physical Downlink Control Channel (PDCCH) transmission. The device may transmit the PRACH transmissions to the set of cells.

[0008] The configuration information may be received via radio resource control (RRC) signaling. The indication of the set of cells may be received via a medium access control (MAC) control element (CE). The indication of the set of cells may be an index of the set of cells, a set of cell / synchronization signal / PBCH block (SSB) combinations, or an individual cell or cell / SSB combination. The indication to send one or more PRACH transmissions to the set of cells received via a PDCCH transmission may be received in a PDCCH order. The PDCCH order may be received via downlink control information (DCI) included in the PDCCH transmission. The PRACH transmission may be transmitted using a configuration associated with the random access information. The processor may (e.g., further) be configured to receive timing advance information of at least one cell of the set of cells. [Brief explanation of the drawings]

[0009] [Figure 1A] 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B]1B is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used within the communications system shown in FIG. 1A, according to one embodiment. [Figure 1C] 1B is a system diagram illustrating an exemplary radio access network (RAN) and an exemplary core network (CN) that may be used within the communications system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system shown in FIG. 1A according to one embodiment. [Figure 2] FIG. 10 is a diagram illustrating an example of a measurement model. [Figure 3] FIG. 1 is a diagram illustrating an example of L1 / L2 inter-cell mobility using carrier aggregation. [Figure 4] FIG. 10 illustrates an example of selecting a subset of cells by MAC CE. [Figure 5] FIG. 10 illustrates an example of dynamically updating the set of target cells. [Figure 6] FIG. 1 illustrates an example of a configured RO. [Figure 7] FIG. 1 illustrates an example of an authorized RO. [Figure 8] FIG. 10 illustrates an example of assigning authorized ROs to different PCIs and recreating indexes. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, and broadcasts, to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailed (ZT) unique word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DFT-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0011] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, and 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, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, and 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d, which may all be referred to as “stations” and / or “STAs,” may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, notebooks, personal computers, wireless sensors, hotspot or Mi-Fi devices, IoT devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. The WTRUs 102a, 102b, 102c, and 102d may all be referred to interchangeably as UEs.

[0012] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be any of a Base Transceiver Station (BTS), a NodeB (NB), an eNodeB (eNB), a Home NodeB (HNB), a Home eNodeB (HeNB), a gNodeB (gNB), a NR NodeB (NR NB), a site controller, an access point (AP), a wireless router, etc. While the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0013] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell or for any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0014] 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).

[0015] More particularly, as noted above, the communications system 100 may be a multiple-access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104 / 113 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using Wideband CDMA (WCDMA). WCDMA may include communications protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0016] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE Advanced (LTE-A) and / or LTE Advanced Pro (LTE-A Pro).

[0017] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access, which may establish the air interface 116 using NR.

[0018] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE and NR radio access, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to and from multiple types of base stations (e.g., eNBs and gNBs).

[0019] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0020] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a workplace, a home, a vehicle, a premises, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0021] 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, application, and / or VoIP services to one or more of the WTRUs 102a, 102b, 102c, and 102d. The data may have various quality of service (QoS) requirements, such as different throughput, latency, error resilience, reliability, data throughput, and mobility requirements. The CN 106 / 115 may provide call control, billing services, mobile location services, prepaid calling, Internet connectivity, video distribution, and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs employing the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0022] The CNs 106 / 115 may also serve as gateways for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as TCP, UDP, and / or IP in the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RANs 104 / 113 or a different RAT.

[0023] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based wireless technology, and with a base station 114b, which may employ an IEEE 802.2 wireless technology.

[0024] 1B is a system diagram illustrating an example of a WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a GPS chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0025] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, other types of integrated circuits (ICs), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0026] The transmit / receive element 122 may be configured to transmit and receive signals to and from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In another embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In one embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0027] 1B depicts the transmit / receive element 122 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More particularly, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0028] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0029] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include RAM, ROM, a hard disk, or any other type of memory storage device. The removable memory 132 may include a SIM card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0030] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0031] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0032] The processor 118 may also be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The 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.

[0033] 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 a particular subframe for both the uplink (e.g., for transmission) and the downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and / or substantially eliminate self-interference through either hardware (e.g., chokes) or signal processing via a processor (e.g., a separate processor (not shown) or processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the uplink (e.g., for transmission) or the downlink (e.g., for reception)).

[0034] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As noted above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0035] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a.

[0036] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink (UL) and / or downlink (DL), etc. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0037] 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 above elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0038] The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

[0039] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during handovers between eNodeBs, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0040] The SGW 164 may be connected to a PGW 166 that 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.

[0041] 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 fixed communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0042] Although the WTRU is depicted in FIGS. 1A-1D as a wireless terminal, it is contemplated that in some representative embodiments such a terminal may use a wired communication interface with the communication network (e.g., temporarily or permanently).

[0043] In an exemplary embodiment, the other network 112 may be a WLAN.

[0044] A WLAN in infrastructure basic service set (BSS) mode has an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or from the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be sent to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP and delivered to the respective destination. Traffic between STAs within a BSS may be sent through the AP; for example, a source STA may send traffic to the AP, which then delivers the traffic to the destination STA. Traffic between STAs within a BSS may be considered or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent (e.g., directly) between a source STA and a destination STA using direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all STAs) may communicate directly with each other. The IBSS communication mode is sometimes referred to herein as an "ad hoc" communication mode.

[0045] When using 802.11ac infrastructure mode operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a wide 20 MHz bandwidth) or a width dynamically set via signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected by a particular STA and / or determined to be busy, the particular STA may back off. One STA (e.g., only one station) may transmit on a given BSS at any time.

[0046] High-throughput (HT) STAs may use 40 MHz wide channels for communication, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form the 40 MHz wide channel.

[0047] A Very High Throughput (VHT) STA can support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. A 40 MHz and / or 80 MHz channel can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. In the 80+80 configuration, the channel-encoded data passes through a segment parser, which splits the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed separately on each stream. The streams are mapped to two 80 MHz channels, and the data is transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be transmitted to the Medium Access Control (MAC).

[0048] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. The channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah can support meter-type control / machine-type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have limited functionality, including specific features, such as support for (e.g., only support for) specific and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., maintaining a very long battery life).

[0049] A WLAN system may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, and the WLAN system includes a channel that may be designated as a primary channel. The bandwidth of the primary channel may be equal to the largest common operating bandwidth supported by all STAs in a BSS. The bandwidth of the primary channel may be configured and / or limited by the STA from among all STAs operating in the BSS that support the smallest bandwidth operating mode. In an 802.11ah example, the primary channel of a STA (e.g., an MTC-type device) that supports (e.g., only supports) 1 MHz mode may be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) configuration may depend on the status of the primary channel. For example, if the primary channel is busy because a STA (that only supports a 1 MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and available for use.

[0050] In the United States, the available frequency bands available for 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total available bandwidth for 802.11ah is 6MHz to 26MHz depending on the country code.

[0051] 1D is a system diagram illustrating the RAN 113 and the CN 115, according to one embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0052] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may transmit and / or receive signals to and from the WTRUs 102a, 102b, and 102c using beamforming. Thus, for example, the gNB 180a may transmit and / or receive wireless signals to and from the WTRU 102a using multiple antennas. In one embodiment, the gNBs 180a, 180b, and 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 the unlicensed spectrum, and the remaining component carriers may be on the licensed spectrum. In one embodiment, the gNBs 180a, 180b, and 180c may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0053] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or different lengths of absolute time duration).

[0054] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c can utilize one or more gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c at approximately the same time. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0055] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0056] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the above elements is shown as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0057] The AMF 182a, 182b may be connected to one or more gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized by the WTRUs 102a, 102b, 102c. Different network slices may be established for different use cases, for example, services relying on Ultra-Reliable Low-Latency (URLLC) access, services relying on enhanced Massive Mobile Broadband (eMBB) access, services for Machine Type Communications (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that use other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as Wi-Fi.

[0058] The SMFs 183a and 183b may be connected to the AMFs 182a and 182b in the CN 115 via an N11 interface. The SMFs 183a and 183b may also be connected to the UPFs 184a and 184b in the CN 115 via an N4 interface. The SMFs 183a and 183b may select and control the UPFs 184a and 184b and configure the routing of traffic through the UPFs 184a and 184b. The SMFs 183a and 183b may perform other functions such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0059] The UPFs 184a, 184b may be connected to one or more gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which provides the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110 and facilitates communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing a mobility anchor, etc.

[0060] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0061] 1A-1D and the corresponding description thereof, one or more, or all, of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNodeBs 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 other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0062] The emulation device can be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices can be fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to perform one or more, or all, functions for testing other devices in the communication network. One or more emulation devices can be temporarily implemented / deployed as part of a wired and / or wireless communication network to perform one or more, or all, functions. The emulation device can be directly coupled to another device for testing purposes and / or can perform testing using wireless communication.

[0063] One or more emulation devices may also perform one or more functions (including all functions) without being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in test scenarios in non-deployed (e.g., test) wired and / or wireless communication networks to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0064] In the RRC_CONNECTED state, the WTRU may measure multiple beams (e.g., at least one beam) of a cell (e.g., each cell), and the measurement results (power values) may be averaged to derive cell quality. In doing so, the WTRU may be configured to consider a subset of the detected beams. Filtering may be performed at different levels (e.g., two different levels). For example, filtering may be performed at the physical layer (e.g., to derive beam quality) and / or at the radio resource control (RRC) level (e.g., to derive cell quality from multiple beams). Cell quality from beam measurements may be derived similarly for serving and / or non-serving cells.

[0065] 2 shows an example of a measurement model (e.g., a high-level measurement model). As shown in FIG. 2, the WTRU may be configured, e.g., by a gNB, to report measurement results (e.g., provide a measurement report). The measurement report may include measurement results for multiple beams (e.g., one beam). The WTRU may be configured (e.g., by a gNB) to provide a measurement report including measurement results for multiple beams, e.g., X best beams.

[0066] Channel state information (CSI) may be reported (e.g., from the WTRU to the network, e.g., to the gNB). The CSI may be used (e.g., by the network) as an indicator of good or bad channel conditions at a point in time (e.g., any point in time). The CSI may be used by the gNB to make scheduling decisions such as modulation and coding scheme (MCS) selection and to assist in beamforming.

[0067] The time and frequency resources that the WTRU may use to report CSI may be controlled by the gNB. The CSI may include, for example, one or more of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), a synchronization signal (SS) / physical broadcast channel (PBCH) block resource indicator (SSBRI), a layer indicator (LI), a rank indicator (RI), a L1-RSRP, a L1 signal-to-interference-and-noise ratio (L1-SINR), or a Capability[Set]Index.

[0068] For CQI, PMI, CRI, SSBRI, LI, RI, L1-RSRP, L1-SINR, and / or Capability[Set]Index, the WTRU may be configured (e.g., by higher layers) with, for example, N≧1 CSI-ReportConfig reporting configurations, M≧1 CSI-ResourceConfig resource configurations, and / or one or two lists of trigger states (e.g., given by higher layer parameters CSI-AperiodicTriggerStateList and CSI-SemiPersistentOnPUSCH-TriggerStateList). A trigger state (e.g., each trigger state) in CSI-AperiodicTriggerStateList may include a list of associated CSI-ReportConfigs. The list of associated CSI-ReportConfigs may indicate channel and / or interference resource set IDs. A trigger state (e.g., each trigger state) in CSI-SemiPersistentOnPUSCH-TriggerStateList may include one associated CSI-ReportConfig.

[0069] A reporting configuration CSI-ReportConfig (e.g., each reporting configuration CSI-ReportConfig) may be associated with a single downlink BWP (e.g., indicated by the higher layer parameter BWP-Id) given to the associated CSI-ResourceConfig for channel measurements. A reporting configuration CSI-ReportConfig (e.g., each reporting configuration CSI-ReportConfig) may include one or more of the following parameters of the CSI reporting band: codebook configuration including codebook subset restriction, time domain behavior, frequency granularity of CQI and PMI, measurement restriction configuration, or CSI-related quantities reported by the WTRU, such as Layer Indicator (LI), L1-RSRP, L1-SINR, CRI, SSBRI, and / or Capability[Set]Index.

[0070] The time-domain behavior of CSI-ReportConfig is indicated by the higher layer parameter reportConfigType and / or can be set to aperiodic, semiPersistentOnPUCCH, semiPersistentOnPUSCH, or periodic. For periodic, semiPersistentOnPUCCH, and / or semiPersistentOnPUSCH CSI reporting, the configured periodicity and slot offset may apply to the number of uplink (UL) bandwidth portions (BWPs) over which the CSI report is configured to be transmitted. The higher layer parameter reportQuantity may indicate the amount of CSI-related, L1-RSRP-related, L1-SINR-related, and / or Capability[Set]Index-related information to report. The reportFreqConfiguration may indicate the reporting granularity in the frequency domain, including the CSI reporting band and / or whether the PMI / CQI report is wideband or subband. The timeRestrictionForChannelMeasurements parameter of CSI-ReportConfig can be configured to enable time-domain restrictions on channel measurements. The TimeRestrictionForInterferenceMeasurements parameter can be configured to enable time-domain restrictions on interference measurements. The CSI-ReportConfig can (e.g., also) include a CodebookConfig, which can include configuration parameters for Type 1, Type 2, extended Type 2 CSI, or further extended Type 2 port selection (including codebook subset restrictions, and / or group-based reporting configuration, if applicable).

[0071] A CSI resource configuration CSI-ResourceConfig (e.g., each SI resource configuration CSI-ResourceConfig) may include a configuration of a list of S≧1 CSI resource sets (e.g., given by the higher layer parameter csi-RS-ResourceSetList). The list may include references to either or both of a non-zero power (NZP) CSI-RS resource set and an SS / PBCH block set, or the list may include a reference to a CSI-IM resource set. A CSI resource configuration (e.g., each CSI resource configuration) may be located in a DL BWP (e.g., identified by the higher layer parameter BWP-id). CSI resource configurations linked to a CSI reporting configuration may have the same DL BWP.

[0072] The time domain behavior of the CSI-RS resources within a CSI resource configuration can be indicated by the higher layer parameter resourceType. The time domain behavior of the CSI-RS resources can be configured to be aperiodic, periodic, or semi-persistent. For periodic and semi-persistent CSI resource configurations (e.g., when the WTRU is configured with groupBasedBeamReporting), the number of configured CSI resource sets is S=2. Otherwise, the number of configured CSI-RS resource sets is limited to S=1. For periodic and semi-persistent CSI resource configurations, the configured periodicity and slot offset may be given by the number of associated DL BWPs, for example, specified by the BWP-id. If the WTRU is configured with multiple CSI-ResourceConfigs containing the same NZP CSI-RS resource ID, the same time domain behavior may be configured for the CSI-ResourceConfigs. If the WTRU is configured with multiple CSI-ResourceConfigs containing, for example, the same CSI-IM resource ID, the same time domain behavior may also be configured for the CSI-ResourceConfigs. Some CSI resource configurations (e.g., all CSI resource configurations) linked to a CSI reporting configuration may have the same time domain behavior.

[0073] For one or more CSI resource configurations for channel and interference measurements, one or more of the following may be configured via higher layer signaling: CSI-IM resources for interference measurements, NZP CSI-RS resources for interference measurements, or NZP CSI-RS resources for channel measurements.

[0074] The WTRU may be configured with a list of Transmission Configuration Indicator (TCI) state configurations for the UP direction. A TCI state (e.g., each TCI state) may include parameters for configuring a quasi-co-location relationship between one or more (e.g., two) downlink reference signals and a demodulation reference signal (DM-RS) port of the PDSCH, a DM-RS port of the PDCCH, and / or a CSI-RS port(s) of a CSI-RS resource. The quasi-co-location relationship may be configured (e.g., if configured) by the upper layer parameter qcl-Type1 for the first DL RS and / or qcl-Type2 for the second DL RS. The quasi-co-location type corresponding to each DL RS may be given by the upper layer parameter qcl-Type in the quasi-colocation (QCL) information. The pseudo-collocation type corresponding to each DL RS can take one or more of the following values: Type A: {Doppler shift, Doppler spread, average delay, delay spread}, Type B {Doppler shift, Doppler spread}, Type C {Doppler shift, average delay} or Type D {Spatial Rx parameter}.

[0075] Inter-cell L1 / L2 mobility may be implemented. Inter-cell L1 / L2 mobility may manage beams in carrier aggregation (CA) cases, and cell change / addition may or may not be supported. L1 / L2-based inter-cell mobility mechanisms and / or procedures may be indicated / implemented with the aim of reducing mobility latency.

[0076] L1 / L2-based mobility and / or inter-cell beam management may address intra-DU and / or intra-frequency scenarios. In this case, the serving cell may remain unchanged (e.g., there may be no possibility to change the serving cell using L1 / L2-based mobility). In FR2 deployments, carrier aggregation (CA) may be used to exploit available bandwidth (e.g., to aggregate multiple CCs in one band). These CCs may be transmitted on the same analog beam pair (e.g., gNB beam and WTRU beam). The WTRU may be configured with TCI states (e.g., 64 TCI states) for receiving PDCCH and PDSCH. The TCI states (e.g., each TCI state) may include an RS or SSB that the WTRU can reference to configure the beam. The SSB may be associated with a non-serving PCI. MAC signaling (e.g., "TCI state indication for WTRU-specific PDCCH MAC CE") may activate the TCI state of the CORESET / PDCCH. Reception of PDCCH from non-serving cells may be supported by a MAC CE indicating the TCI state associated with the non-serving PCI. MAC signaling (e.g., "TCI States Activation / Deactivation for WTRU-specific PDSCH") may activate a subset of TCI states (e.g., up to eight TCI states) for PDSCH reception. The DCI may indicate a specific TCI state of the subset of TCI states (e.g., eight TCI states). The "integrated TCI state" may be supported with different update mechanisms (e.g., DCI-based), e.g., with or without multi-TRP.

[0077] L1 / L2 inter-cell mobility can be (used to) improve handover latency, for example, compared to traditional L3 handover and / or conditional handover, where the WTRU may first send a measurement report (e.g., using RRC signaling). In response, the network can provide additional measurement configurations and / or conditional handover configurations. In traditional handover, the network can provide the target cell configuration after the WTRU reports, using RRC signaling, that the cell meets the configured radio quality criteria.

[0078] L1 / L2-based inter-cell mobility enables rapid application of candidate cell configurations, including dynamic switching between secondary cells (SCells) and primary cell (PCell) switching (e.g., switching roles between SCells and PCells) without performing RRC signaling. The inter-CU case may be associated with Packet Data Convergence Protocol (PDCP) anchor relocation. The RRC-based approach may support inter-CU handover.

[0079] In a conventional L3 handover mechanism, currently active SCells (e.g., any currently active SCells) may be released (e.g., may be re-added only after the handover is successful) before the WTRU moves (e.g., completes the handover) to a target cell within the coverage area of ​​the new site, which may result in reduced throughput during the handover. L1 / L2 may enable CA operation (e.g., instantaneously upon serving cell change).

[0080] 3 illustrates an example of L1 / L2 inter-cell mobility operation. The candidate cell group may be configured by RRC (e.g., RRC as used herein may refer to RRC signaling). Dynamic switching between PCell and SCell may be achieved using L1 / L2 signaling.

[0081] FIG. 3 shows an example of L1 / L2 inter-cell mobility with carrier aggregation (CA). The baseline procedure for L1 / L2 triggered mobility (LTM) may include one or more of the following actions: The WTRU may send a measurement report (e.g., a MeasurementReport message) to the gNB. The gNB may decide to use LTM. The gNB may initiate LTM candidate preparation. The gNB may send an RRCReconfiguration message to the WTRU, which may include the configuration of one or more LTM candidate target cells. The WTRU may store the configuration of the LTM candidate cells. The WTRU may send an RRCReconfigurationComplete message to the gNB. The WTRU may, for example, perform DL synchronization and TA acquisition with the candidate cells before receiving the LTM cell switch command. The WTRU may perform L1 measurements on the configured LTM candidate cells. The WTRU may send lower layer measurement reports to the gNB. The lower layer measurement reports may be carried over L1 or MAC. The gNB may decide to perform an LTM cell switch to the target cell. The gNB can send a MAC CE to trigger an LTM cell switch, for example, by including a candidate configuration index for the target cell. The WTRU can switch to the configuration of the LTM candidate target cell. The WTRU can perform a random access procedure toward the target cell, for example, if a TA is not available. The WTRU can indicate that the LTM cell switch to the target cell has been successfully completed.

[0082] The physical random access procedure may be triggered in response to a request for PRACH transmission by higher layers or by a PDCCH order. The configuration by higher layers for PRACH transmission may include one or more of the PRACH transmission configuration, preamble index, preamble SCS, corresponding RA-RNTI, or PRACH resource. The PRACH may be transmitted using a selected PRACH format.

[0083] For a Type 1 random access procedure, the WTRU may be provided with N SS / PBCH block indices associated with one PRACH opportunity and / or R contention-based preambles per SS / PBCH block index per valid PRACH opportunity (e.g., by ssb-perRACH-OccasionAndCB-PreamblesPerSSB).

[0084] The PRACH opportunities may be mapped (e.g., consecutively mapped) for each corresponding SS / PBCH block index. The indexing of the PRACH opportunities indicated by the mask index value may be reset for each mapping cycle of consecutive PRACH opportunities for each SS / PBCH block index. For a PRACH transmission (e.g., each PRACH transmission), the WTRU may select the PRACH opportunity indicated by the PRACH mask index value for the indicated SS / PBCH block index in the first available mapping cycle.

[0085] For a given preamble index, the order of the PRACH opportunities may be, for example, firstly, in ascending order of frequency resource index of frequency-multiplexed PRACH opportunities, secondly, in ascending order of time resource index of time-multiplexed PRACH opportunities within a PRACH slot, and thirdly, in ascending order of PRACH slot index. The random access procedure may be initiated by the PDCCH order, by the MAC entity itself, or by the RRC (e.g., for a specific event).

[0086] The WTRU may need to establish and maintain timing alignment with the cell, for example, so that the gNB can successfully receive the WTRU transmission. The WTRU may establish and maintain timing alignment by transmitting a random access preamble on the PRACH, which the cell may use to estimate a timing advance that the WTRU can use. The cell may transmit the estimated timing advance value to the WTRU.

[0087] The WTRU may establish timing alignment with a candidate cell before a cell switch occurs (e.g., in L1 mobility), for example, to reduce connection latency. Establishing timing alignment with multiple cells may incur significant overhead and / or delay. The most likely target cell may be determined without increasing latency. The PRACH may be transmitted to the determined cell without increasing latency.

[0088] A candidate cell set may include one or more candidate cells. A candidate cell set may be a group of RRC configurations (e.g., multiple RRC configurations) corresponding to handover configurations of one or more candidate SpCells and / or SCells. A candidate cell set may be modeled and / or received as one or more complete RRC reconfiguration messages, one or more cell group configurations, or one or more cell configurations. A candidate cell configuration (e.g., each candidate cell configuration) may include a candidate configuration identifier. A candidate cell group (e.g., each candidate cell group) may include a candidate cell group identifier. The grouping may be performed by RRC. Switching between different sets of candidate cells may include updating a serving cell index and / or a candidate configuration index, which may be used to reference specific indexes in L1 and MAC signaling. For example, a MAC CE triggering a reconfiguration may include a candidate configuration index that informs the WTRU which cells to perform the reconfiguration on.

[0089] L1 measurements (e.g., as used herein) may include measurements of RSRP, RSRP, RSSI, etc., which may be performed by the WTRU for a cell, a beam, a set of cells, and / or a set of beams. L1 measurements may be performed for CSI-RS resources and / or SSBs. CSI-RS and CSI-RS resources may be used interchangeably herein.

[0090] As described herein, the WTRU can determine a PRACH opportunity (RO) for transmitting a PRACH to one or more candidate cells. The PRACH transmission is performed (e.g., in response to a condition), and the candidate cells can estimate a timing advance that the WTRU can use to communicate to the cell, e.g., after a cell switch.

[0091] The SSB and / or CSI-RS index may be mapped to a valid PRACH opportunity.

[0092] The WTRU may apply independent mapping, for example, when determining random access opportunities for SSB and / or CSI-RS. As an example of independent mapping, the SSB index and the CSI-RS index may be independently mapped to the same valid RO. For example, the WTRU may (e.g., first) map the SSB index to a valid RO and (e.g., second) map the CSI-RS index to a valid RO (e.g., or vice versa, in which case the mapping order may be changed).

[0093] The SSB index and / or CSI-RS resource index may be mapped to valid PRACH opportunities (e.g., in ascending order) based on one of the following: a preamble index within a single PRACH opportunity (e.g., a preamble index may be skipped if / when provided, for example, by configuration or in a PDCCH order), a frequency resource index of a frequency-multiplexed PRACH opportunity, a time resource index of a time-multiplexed PRACH opportunity within a PRACH slot, and / or an index for a PRACH slot.

[0094] The valid ROs may not overlap (e.g., partially) for SSB and CSI-RS, for example, if separate PRACH masks are used. For example, the SSB index may be mapped to a first set of allowed ROs, and the CSI-RS index may be mapped to a second set of ROs.

[0095] The SSB index may be mapped to a valid RO, for example, using the mapping rules as described herein. The CSI-RS index may be mapped to the RO to which the QCL'd SSB in the CSI-RS is mapped. For example, if SSB#5 and CSI-RS resource#3 are QCL'd, both may be mapped to the same RO.

[0096] The SSB index and CSI-RS index may be combined into a common list. The indices in the list may be mapped sequentially to valid POs. For example, from the list [SSB0 SSB1 ... SSBK CSI-RS0 CSI-RS1 ... CSI-RSN], SSB0 may be mapped to the first valid PO, SSB1 may be mapped to the second valid PO, etc.

[0097] The ROs may be divided into multiple (e.g., two) groups of valid ROs, for example, by applying multiple (e.g., two) PRACH masks. For example, the SSB index may be mapped to a valid RO in a first group, and the CSI-RS index may be mapped to a valid RO in a second group.

[0098] Mapping techniques (eg, techniques as described herein) may be applicable to more than one type of signal (eg, SSB, CSI-RS, and / or other types of signals).

[0099] PRACH transmissions can occur in multiple cells.

[0100] In some examples, the WTRU may receive a random access configuration (e.g., via RRC signaling). The WTRU may receive a configuration for one or more sets of candidate cells (e.g., from a serving cell) (e.g., the WTRU may receive the configuration via RRC signaling). The configuration may include measurement and / or reporting configurations associated with (e.g., each of) the set of one or more cells. The WTRU may receive a configuration for one or more SSB and / or CSI-RS resources associated with the cell (e.g., for each set of cells). The WTRU may receive a configuration of random access parameters (e.g., for each set of cells), which may include one or more of the following: a prach-ConfigurationIndex parameter; a msg1-FrequencyStart (e.g., the offset of the lowest PRACH transmission opportunity in the frequency domain relative to physical resource block (PRB) 0) and / or a msg1-FDM (e.g., the number of frequency-division multiplexed PRACH transmission opportunities in one time instance); a number of SSBs per RACH opportunity; a list of CSI-RSs and the set of ROs to which the CSI-RSs are associated; a root sequence index; or a number of preambles.

[0101] The WTRU may be configured with a prach-ConfigurationIndex parameter. The WTRU may determine (e.g., from the configuration index) one or more of the following: a preamble format, a frame number, a number of PRACH slots in a frame, a number of time-domain PRACH opportunities in a PRACH slot, or a duration of a time-domain PRACH opportunity.

[0102] The WTRU may be configured with msg1-FrequencyStart (e.g., the offset of the minimum PRACH transmission opportunity in the frequency domain, each corresponding to a PRB0) and / or msg1-FDM (e.g., the number of frequency division multiplexed PRACH transmission opportunities in one time instance). The time / frequency resource to which the preamble is mapped may be referred to as a PRACH opportunity.

[0103] The WTRU may be configured with a list of CSI-RS and / or a set of ROs with which the CSI-RS are associated, which may be used, for example, if / when random access is triggered from higher layers.

[0104] A random access configuration may be associated with one or more PCIs, e.g., the configuration may provide random access parameters for transmitting a PRACH to one or more cells having corresponding PCIs. A random access configuration associated with multiple PCIs (e.g., a first PCI and a second PCI) may include at least one configuration parameter that differs (e.g., between one or more of the associated PCIs). For example, the first PCI may be associated with a first PRACH configuration index, and the second PCI may be associated with a second PRACH configuration index. In some examples, different time and / or frequency resources may be configured for different PCIs. In some examples, different root sequences may be configured for different PCIs.

[0105] A random access configuration may be associated with multiple PCIs. The LTM ID may be part of the random access configuration. Cells (e.g., all cells) within an LTM ID may be associated with the same random access configuration.

[0106] In some examples, a random access configuration may be associated with a TCI state. The TCI state may include an SSB index and / or a CSI-RS resource index as a QCL source. The SSB / CSI-RS may be associated with a PCI (e.g., by configuration). The WTRU may determine (e.g., from the TCI state) the PCI and / or SSB / CSI-RS index to which the random access configuration may be associated.

[0107] The WTRU may determine the PRACH opportunity.

[0108] In some examples, the WTRU may receive an indication (e.g., via MAC CE), which may include an indication to a set of one or more cells configured by RRC, and the WTRU may determine random access parameters associated with the indicated cells (e.g., using the MAC CE indication and the configured parameters).

[0109] FIG. 4 shows an example of selecting a subset of cells by a MAC CE. As shown in FIG. 4, the WTRU may be configured with random access parameters for cells (e.g., cells 1-6). The MAC CE may indicate cells 1, 3, and 4 to the WTRU. The WTRU may determine the random access parameters for cells 1, 3, and 4 from the received configuration information. As an example, the WTRU may determine that the random access configuration for cells 1, 3, and 4 is common (e.g., applies to all three cells) and / or that the random access configuration for cells 2, 5, and 6 is common (e.g., applies to all three cells). The WTRU may (e.g., further) determine that the frequency resources of the ROs configured for the two sets of cells are different.

[0110] In some examples, the MAC CE may include an indication to at least one combination of a PCI and an SSB index or a CSI-RS. This combination may correspond to a TCI state. The WTRU may determine the associated PCI and / or SSB / CSI-RS (e.g., from the indicated TCI state). The WTRU may (e.g., further) determine a corresponding random access configuration.

[0111] The WTRU may receive an indication (e.g., in a PDCCH order such as the enhanced PDCCH order used as an example) of a PRACH transmission to at least one cell, e.g., one of the cells indicated by the MAC CE (e.g., one or more cells in the set of indicated cells). The enhanced PDCCH order is applicable to the cell (e.g., each cell) that was received (e.g., successfully) in the most recent MAC CE. For example, referring again to the example shown in FIG. 4, the WTRU may receive an enhanced PDCCH order applicable to cells 1, 3, and 4 (e.g., as received in the MAC CE). The enhanced PDCCH order may include one or more of the PCI or an indication to the PCI, an SSB and / or CSI / RS index associated with the PCI, a preamble index, or a PRACH mask.

[0112] The enhanced PDCCH order may include a PCI or an indication to a PCI. The PCI (e.g., each PCI) indicated in the MAC CE may be assigned an index. For example, the PDCCH order may have a bit field indicating the index assigned to the PCI (e.g., using the previous example of FIG. 4, bits 00, 10, and 11 may indicate PCIs 1, 3, and 4, respectively).

[0113] The enhanced PDCCH order may include an SSB and / or CSI / RS index associated with the PCI. The WTRU may use the SSB and / or CSI-RS index to determine the RO from among the valid ROs. The WTRU may determine the RO using one or more of configuring or applying mapping rules (e.g., as described herein). For example, an RO or list of ROs that may be associated with an SSB and / or CSI / RS may be configured (e.g., as part of a random access configuration).

[0114] The enhanced PDCCH order may include a preamble index from which the WTRU may determine the preamble to transmit on the PRACH.

[0115] The enhanced PDCCH order may include a PRACH mask from which the WTRU may determine the allowed PRACH opportunities.

[0116] In some examples, the PDCCH order may include a TCI state. The TCI state may be associated with a combination (e.g., PCI, SSB, or PCI, CSI-RS). For example, a WTRU may be configured with one or more TCI states (e.g., eight TCI states). The TCI state may include an SSB index (e.g., as a QCL source). The SSB may be associated with a PCI. The TCI state may include a CSI-RS resource index (e.g., as a QCL source). The CSI-RS may be associated with a PCI. The PDCCH order may not include the PCI index and SSB / CSI-RS index fields, for example, if / when a TCI state is used.

[0117] In some examples, the WTRU may transmit (e.g., be instructed to) PRACH (e.g., transmit PRACH transmissions) to multiple cells (e.g., two or more cells), which may be indicated by a MAC CE. Assuming there are k (e.g., k=2) ROs for PRACH transmissions to k target cells, the PDCCH order may include, for example, k PCI indices and k SSB / CSI-RS indices, or (e.g., alternatively) k TCI status indications. In some examples, the same preamble may be used for the PRACH transmissions to the k cells, or the PDCCH order may include multiple (e.g., k) preamble indices corresponding to each cell.

[0118] For example, if / when a WTRU is instructed to transmit PRACH to multiple target cells, the WTRU may determine the RO of each cell to which the corresponding PRACH may be transmitted. For example, the WTRU may determine the RO of a first SSB associated with a first PCI and the RO of a second SSB associated with a second PCI.

[0119] In some examples, the PDCCH order may indicate a target cell among cells configured by RRC (e.g., the PDCCH order may not indicate the cell indicated in the MAC CE). For example, the PDCCH order may indicate one of the TCI states configured by RRC. The PDCCH order may (e.g., alternatively) indicate a (PCI and SSB / CSI-RS) combination configured by RRC. The WTRU may determine (e.g., from the indication) the corresponding random access configuration.

[0120] The WTRU may perform measurements, e.g., L1 RSRP measurements, on SSB and / or CSI-RS resources configured by RRC. One or more (e.g., a set) of SSB and CSI-RS resources may be associated with a candidate cell. The WTRU may report the measurements to the serving cell, e.g., in MAC CE and / or in uplink control information in PUSCH and PUCCH.

[0121] In some examples, the WTRU may report one or more measurements, for example, on the MAC CE, to the serving cell (e.g., upon receiving the MAC CE from the serving cell). The measurements may correspond to PCI / SSB / CSI-RS received on the downlink MAC CE. The reported measurements may be filtered measurements (e.g., filtered L1 RSRP measurements). Reception (e.g., successful reception) of the MAC CE by the serving cell (e.g., indicated by an acknowledgment to the serving cell or not receiving a retransmission grant) may trigger (e.g., implicitly) the WTRU to acquire and / or update timing alignment with one or more target cells.

[0122] The WTRU may determine an SSB / CSI-RS associated with the target cell from the measurements. The SSB / CSI-RS (e.g., for the target cell) may be an RS reported to the serving cell. For example, the RS may be an RS with the highest RSRP among (e.g., all) RSs associated with the target cell. The WTRU may determine a cell for PRACH transmission from the target cell, for example, based on some criteria. In some examples, the cell selected for PRACH transmission may be the best k target cells, where k may be configured (e.g., k=1).

[0123] The WTRU may determine an RO from among the valid ROs using the SSB and / or CSI-RS index. The WTRU may determine the RO using one or more of the configuration or application of mapping rules (e.g., as described herein). For example, an RO or list of ROs that may be associated with an SSB and / or CSI / RS may be configured (e.g., as part of a random access configuration).

[0124] The WTRU may transmit the PRACH (e.g., may send a PRACH transmission to cells in the indicated set of cells). The WTRU may transmit the PRACH, e.g., after a valid RO and other PRACH parameters have been determined. In some examples, the WTRU may transmit the PRACH once. The WTRU may retransmit the PRACH after receiving another PDCCH order. The single transmission and / or retransmission may occur, e.g., if / when timing alignment with the target cell is established. In some examples, the extended PDCCH order may indicate (e.g., using a one-bit field) whether the WTRU transmits the PRACH once or follows other behavior, such as applying the parameter preambleTransMax. In some examples, the same indication (e.g., one-bit field) may (e.g., also) indicate to the WTRU not to monitor the random access response to the PRACH (e.g., because timing advance information may be sent to the WTRU by the serving cell). A field (e.g., a 1-bit field) may indicate to the WTRU whether the PDCCH order is for triggering a RACH for timing alignment or whether the PDCCH order is for another purpose. For example, bit 1 may indicate no repetition, no RAR monitoring, etc., and / or bit 0 may indicate another type of RACH (e.g., legacy RACH).

[0125] In some examples, the enhanced PDCCH order may include a transmit power control field for the RACH, for example, if the WTRU does not perform a full RACH procedure with retransmissions (e.g., to allow the network to send another PDCCH order requesting a PRACH at higher power if the network did not receive the first PRACH).

[0126] A device (e.g., a wireless transmit / receive unit (WTRU)) may perform (e.g., be configured to perform) one or more of the following actions: receiving configuration information (e.g., via radio resource control (RRC) signaling) indicating a set of one or more cells (e.g., candidate cells) and / or (e.g., respective) random access information (e.g., preamble, resources, parameters) for use by the set of one or more cells (e.g., each cell or each set of cells); receiving an indication (e.g., via a MAC CE) to select a set of configured cells (e.g., an index of a set of cells or a set of cell / synchronization signal block (SSB) combinations, or an indication of an individual cell or cell / SSB combination); receiving an indication such as a PDCCH order (e.g., a PDCCH carrying downlink control information (DCI)) indicating to transmit one or more PRACH transmissions to the set of cells, where the set of cells is selected from the set of selected cells (e.g., a MAC CE); determining a random access preamble, resources, or parameters based on the received random access configuration information for the selected cells (e.g., each cell in the set of selected cells and / or the set of selected cells); transmitting a PRACH transmission (e.g., a PRACH preamble) to the selected cells (e.g., each cell in the set of selected cells) using the determined random access configuration information; or receiving timing advance information (e.g., from a cell, such as the WTRU's serving cell) for at least one cell (e.g., all cells) in the selected set. In an example, the WTRU may determine a physical cell identifier (PCI) and / or SSB (e.g., beam or spatial filter) to use for transmission to each cell in the set of cells based on, for example, a received indication (e.g., received at a MAC CE).

[0127] The WTRU may receive configuration information, e.g., via RRC. The configuration may indicate a set of cells (e.g., a set of candidate cells). The WTRU may receive random access information, e.g., via RRC (e.g., in conjunction with the configuration information). The random access information may be associated with each of the set of cells. For example, the random access information may include a preamble, resources, and / or parameters for use with one or more sets of cells (e.g., each cell or each set of cells).

[0128] The WTRU may receive an indication of a set of cells (e.g., a set of received cells), an index to the set of cells, a set of cell / SSB combinations, an individual cell, or an index to an individual cell / SSB combination. The indication may be received via a MAC CE.

[0129] The WTRU may determine random access configuration information for the selected cells (e.g., for each cell in the selected cell set or for the entire set of selected cells). The random access configuration information may include one or more of a random access preamble, resources, or parameters associated with the cells in the first set of cells. The random access configuration information may be determined based on the configuration information and an indication (e.g., a received MAC CE indication).

[0130] The WTRU may receive a PDCCH order indicating to transmit one or more PRACH transmissions (e.g., to a cell or a set of cells). In an example, the PDCCH order may not explicitly indicate a cell or a set of cells. In an example, the WTRU may determine to transmit a PRACH transmission to a set of cells indicated by a MAC CE based on the PDCCH order. The PDCCH order may be a PDCCH order carrying DCI. The PDCCH order may be received via a PDCCH transmission.

[0131] The WTRU may send a PRACH transmission to the cell using, for example, a random access preamble, resources, or parameters.

[0132] The WTRU may receive a timing advance value based on the PRACH transmission (e.g., in response to the transmitted PRACH transmission). The WTRU may associate the timing advance value with a cell and / or a set of cells. The WTRU may transmit another PRACH transmission to the cell based on the timing advance value.

[0133] The PRACH transmission may be triggered by the WTRU Measurement Report ACK.

[0134] The WTRU may receive an RRC configuration. The WTRU may receive (e.g., from a serving cell) a configuration of one or more sets of candidate cells in the RRC. The configuration may include measurement and reporting configurations associated with one or more sets of cells. The WTRU may receive (e.g., for each set of cells) a configuration of one or more SSB and / or CSI-RS resources associated with the cells. The WTRU may receive (e.g., for each set of cells) a configuration of random access parameters, which may include one or more of the following: a prach-ConfigurationIndex parameter; a msg1-FrequencyStart parameter (e.g., an offset of the lowest PRACH transmission opportunity in the frequency domain relative to PRB0) and / or a msg1-FDM parameter (e.g., the number of frequency division multiplexed PRACH transmission opportunities in one time instance); the number of SSBs per RACH opportunity; a list of CSI-RSs and the set of ROs to which the CSI-RSs are associated; a root sequence index; and / or the number of preambles.

[0135] The WTRU may be configured with a prach-ConfigurationIndex parameter. The WTRU may determine (e.g., from the configuration index) one or more of the following: a preamble format, a frame number, a number of PRACH slots in a frame, a number of time-domain PRACH opportunities in a PRACH slot, or a duration of a time-domain PRACH opportunity.

[0136] The WTRU may be configured with msg1-FrequencyStart (e.g., the offset of the minimum PRACH transmission opportunity in the frequency domain, each corresponding to a PRB0) and / or msg1-FDM (e.g., the number of frequency division multiplexed PRACH transmission opportunities in one time instance). The time / frequency resource to which the preamble is mapped may be referred to as a PRACH opportunity.

[0137] The WTRU may be configured with a list of CSI-RS and / or a set of ROs with which the CSI-RS are associated, which may be used, for example, if / when random access is triggered from higher layers.

[0138] A random access configuration may be associated with one or more PCIs, e.g., the configuration may provide random access parameters for transmitting a PRACH to one or more cells having the corresponding PCIs. The random access configurations associated with a first PCI and a second PCI may include at least one different configuration parameter. For example, the first PCI may be associated with a first PRACH configuration index, and the second PCI may be associated with a second PRACH configuration index. In some examples, different time and / or frequency resources may be configured for different PCIs. In some examples, different root sequences may be configured for different PCIs.

[0139] A random access configuration may be associated with multiple PCIs. The LTM ID may be part of the random access configuration. Cells (e.g., all cells) within an LTM ID may be associated with the same random access configuration.

[0140] In some examples, a random access configuration may be associated with a TCI state. The TCI state may include, for example, an SSB index and / or a CSI-RS resource index as a QCL source. The SSB / CSI-RS may be associated with a PCI (e.g., by configuration). The WTRU may determine (e.g., from the TCI state) the PCI and / or SSB / CSI-RS index to which the random access configuration may be associated.

[0141] The WTRU may perform measurements and recommendations. The WTRU may perform measurements (e.g., L1 RSRP measurements on SSB and / or CSI-RS resources configured by RRC). One or more (e.g., a set) SSB and / or CSI-RS resources may be associated with a candidate cell. The WTRU may report the measurements to the serving cell, for example, in MAC CE or in uplink control information in PUSCH and PUCCH.

[0142] In some examples, the subset of cells may be determined by the WTRU (e.g., from reported measurements) or may be indicated by the serving cell. This subset may be referred to as "target cells." FIG. 5 shows an example of dynamically updating the set of target cells. For example, as shown in FIG. 5, a WTRU may be configured with measurement objects for cells 1-6. The subset of target cells may be dynamically updated, for example, depending on the measurements. Target cells may be considered a set of cells to which the WTRU may be handed over if certain conditions are met, for example, if the RSRP of the RS associated with the target cell is at a better offset than the RSRP of the serving cell. In the example shown in FIG. 5, cell 3 is the serving cell for WTRU A, cell 4 is the serving cell for WTRU B, and cell 6 is the serving cell for WTRU C. Cells 1 and 4 are target cells for WTRU A, cells 1, 2, and 5 are target cells for WTRU B, and cells 2 and 5 are target cells for WTRU C. The reported measurements may be filtered measurements (eg, filtered L1 RSRP measurements).

[0143] In some examples, the WTRU may report measurements to the serving cell in the MAC CE. Successful reception of the MAC CE (e.g., indicated by not receiving an acknowledgment or retransmission grant from the serving cell) may (e.g., implicitly) trigger the WTRU to acquire and / or update timing alignment with one or more target cells. The WTRU may determine an SSB / CSI-RS associated with the target cell from the measurements. The SSB / CSI-RS (e.g., for the target cell) may be an RS reported to the serving cell. For example, the RS may be an RS with the highest RSRP among (e.g., all) RSs associated with the target cell. The WTRU may determine a cell for PRACH transmission from the target cell based, for example, on one or more conditions and / or criteria. In some examples, the cell selected for PRACH transmission may be the best k target cells, where k may be configured (e.g., k=1).

[0144] The WTRU may determine an RO from among the valid ROs using the SSB and / or CSI-RS index. The WTRU may determine an RO using either: a configuration (e.g., an RO or list of ROs that may be associated with an SSB and / or CSI / RS may be configured, for example, as part of a random access configuration), and / or by applying a mapping rule (e.g., as disclosed herein).

[0145] In some examples, the WTRU may transmit the PRACH using a random access configuration associated with the target cell. In some examples, the random access configuration may not be associated with a specific cell. The WTRU (can) transmit the PRACH within the LTM area using random access resources. For example, as the WTRU moves, the set of target cells may be dynamically determined (e.g., based on WTRU measurements and / or signaling from the serving cell). The WTRU transmits (e.g., can transmit) the PRACH to one or more target cells, for example, using a common random access configuration.

[0146] The WTRU may trigger a PRACH transmission to the target cell, for example, if the cell timing advance information is not up-to-date. For example, the difference between the current time and the last time the cell timing advance was received and / or applied may exceed a threshold. In some examples, a time (e.g., a timer) that started when the cell timing advance was last received and / or applied may expire.

[0147] The WTRU may trigger a PRACH transmission to one of the target cells, for example, the target cell may be the cell with the highest RSRP.

[0148] Example procedures may include one or more of the following: the WTRU may perform measurements on the candidate cells; the WTRU may transmit a measurement report (e.g., the measurement report may include filtered measurements); the WTRU may update the set of target cells, e.g., based on the reported measurements (e.g., after the report is acknowledged); the WTRU may select one or more of the target cells, e.g., if certain conditions persist (e.g., if the RSRP of the target cell is above a threshold and / or if the timing alignment of the target cell is not up-to-date); the WTRU may determine the RO of the selected target cell and associated SSB / CSI-RS; and / or the WTRU may transmit a PRACH on the determined RO.

[0149] In some examples, the WTRU may send a WTRU assistance message (e.g., in MAC CE) to the serving cell. The message may include the index of the target cell. An acknowledgment of the message may trigger the WTRU to initiate a PRACH to the target cell.

[0150] In some examples, the WTRU may send a timing alignment request to a cell (e.g., a serving cell) in a MAC CE or a RACH request MAC CE. The cell (e.g., serving cell) receiving the MAC CE may send a PDCCH order to the WTRU for a RACH transmission.

[0151] In some examples, the WTRU may maintain a set of active TCI states. A TCI state may be associated with one or more signals as PCI and QCL sources (e.g., SSB and / or CSI-RS). The WTRU may report measurements of the TCI states, e.g., RSRP of the SSB and / or CSI-RS associated with the TCI state, to the serving cell. The WTRU may estimate QCL properties of the SSB and / or CSI-RS associated with the active TCI state. In some examples, the WTRU may perform (e.g., decide to perform) random access to a cell (e.g., transmitting a PRACH on a valid RO). The cell may be one of the cells with which the active TCI state is associated. One or more of the following may apply:

[0152] The WTRU may decide and / or be instructed (e.g., by the serving cell) to update the QCL properties of the TCI state. The WTRU may (e.g., decide to) initiate random access (e.g., select a valid RO and transmit a PRACH) to the cell associated with the TCI state. An update QCL message from the serving cell may trigger the WTRU to initiate a timing alignment procedure to the cell associated with the TCI state, e.g., to prepare and transmit a RACH. The timing alignment procedure may be performed, for example, if (e.g., only if) the timing advance information of the cell is not up-to-date (e.g., as described herein).

[0153] The WTRU may trigger a timing alignment procedure for a cell indicated in the MAC CE, e.g., if / when the WTRU receives a MAC CE for activating one or more TCI states. The timing alignment procedure may be performed, e.g., if (e.g., only if) the timing advance information for the cell is not up-to-date (e.g., as described herein).

[0154] A timing alignment request (e.g., by a PDCCH order) may trigger the WTRU to update and / or estimate the QCL properties of the same cell. The WTRU may receive (e.g., expect to receive) an RS (e.g., aperiodic RS) that the WTRU may use for QCL estimation, for example, if / when the WTRU receives a PDCCH order for RACH transmission. The RS may be associated with a cell from which the WTRU may initiate RACH transmission. The RS may be an RS (e.g., SSB and / or CSI-RS) indicated in the PDCCH order.

[0155] The PDCCH order that triggers the RACH transmission may include a field for a TCI state update request. For example, the field may be a 1-bit field. The field may indicate whether the WTRU should estimate the QCL properties of the PCI and SSB / CSI-RS combination indicated in the PDCCH order. The 1-bit field may trigger aperiodic RS transmissions that the WTRU may use to estimate the QCL properties.

[0156] The PDCCH order may include a bit field that triggers one or more of RACH transmission and / or QCL property estimation and / or DL ​​synchronization. In an example, the bit field may be given as follows: The WTRU may trigger a RACH transmission to the indicated cell and SSB / CSI-RS index, for example, based on a bit field value of 00. The WTRU may trigger a RACH transmission and receive (e.g., expect to receive) a reference signal (e.g., an aperiodic reference signal) that the WTRU may use for QCL purposes, for example, based on a bit field value of 01. The RS may be an RS associated with the target cell. The WTRU may trigger a RACH and expect an RS for QCL and another RS ​​(e.g., a tracking reference signal) from the target cell for DL ​​synchronization, for example, based on a bit field value of 10.

[0157] For example, a device (e.g., a WTRU) may perform (e.g., be configured to perform) one or more of the following actions: receiving (e.g., via RRC) configuration information indicating a set of one or more cells (e.g., candidate cells) and / or random access information (e.g., preamble, resources, parameters) to use for the set of one or more cells (e.g., each cell or set of cells); performing measurements (e.g., Layer 1 (L1) measurements, Reference Signal Received Power (RSRP) measurements) on the one or more candidate cells, where, for example, each cell may be associated with a PCI and / or each measurement may be associated with an SSB; selecting a set of cells from the set of one or more cells based on the measurements (e.g., a set with RSRP measurements above a threshold); transmitting (e.g., via a MAC CE) a first indication indicating at least one of the selected set of cells, one or more SSBs associated with each cell in the selected set, and / or one or more measurements associated with the cells and / or SSBs; receive a trigger indicating to transmit one or more PRACH transmissions to a set of cells indicated by the WTRU (e.g., by the WTRU's serving cell) (e.g., the trigger may be an ACK received in response to transmitting a first indication indicating that the first indication (e.g., a PDSCH carrying the first indication) has been successfully received, or the trigger may be a DCI or MAC CE that implicitly or explicitly indicates to transmit a PRACH to the set of cells indicated by the WTRU by the first indication); determine random access configuration information for the selected cells (e.g., for each cell in the selected set of cells, or for the entire selected set of cells); transmit a PRACH (e.g., a PRACH preamble) to the selected cells (e.g., each cell in the selected set of cells) using the determined random access configuration information (e.g., transmit based on receipt of the trigger); and / or receive timing advance information for at least one cell (e.g., all cells) in the selected set (e.g., from a cell, such as the WTRU's serving cell).In an example, the WTRU may determine the PCI and / or SSB (e.g., beam or spatial filter) to use for transmission to each cell in the set of cells based on, for example, a received indication (e.g., received at the MAC CE).

[0158] PRACH transmissions may occur based on RACH occasions (ROs).

[0159] There may be multiple PRACH mask index values.

[0160] In some examples, the WTRU may determine and / or be instructed to transmit a signal to more than one cell. The signal may be a random access preamble. The following methods may be applicable, for example, when the signal is a random access preamble or a different type of signal / sequence (e.g., the signal may be a sequence such as a Zadoff-Chu sequence or another type of sequence).

[0161] The WTRU may transmit (e.g., may be instructed to transmit) a signal in a PDCCH order. In some examples, the PDCCH order may include an index into a set of configured preambles. The WTRU may transmit (e.g., may be expected to transmit) an indicated preamble (e.g., in a PRACH). In some examples, the PDCCH order may include multiple indices for the preamble. A first index may indicate a first preamble from a first set of configured preambles, a second index may indicate a second preamble from a second set of configured preambles, etc. The WTRU may transmit (e.g., may be expected to transmit) a preamble, for example, in the PRACH.

[0162] The PDCCH order may include a PRACH mask index. The mask index may indicate the PRACH opportunities on which the WTRU is allowed to transmit the random access preamble. The mask index may point to an entry in a (pre-)configured or specified table. The entry in the table may include a list of allowed PRACH opportunities. In some examples, the PDCCH order may include two or more PRACH mask indices. The WTRU can determine the allowed ROs for transmitting PRACH to two or more cells from the two or more mask indices. The PRACH mask indices may point to the same table or different tables.

[0163] Tables 1 and 2 are example PRACH mask index values. As an example, the WTRU may determine the allowed PRACH opportunities from Table 1 using a first PRACH mask and from Table 2 using a second PRACH mask.

[0164] In a first example (e.g., Example 1), the WTRU may receive mask indices 1 and 3. The WTRU may determine (e.g., using Table 1) that the allowed RO is RO#1, an even-numbered RO, which may be used to transmit a preamble to the first cell.

[0165] In a second example (e.g., Example 2), the WTRU may receive mask indices 1 and 3. The WTRU may determine (e.g., using index 1 in Table 1 and index 3 in Table 2) that the allowed RO is RO#1, an odd-numbered RO, which may be used to transmit a preamble to the second cell.

[0166] [Table 1]

[0167] [Table 2]

[0168] In some examples, a (e.g., one) PRACH mask index may indicate more than one value, e.g., by pointing to an entry in a table where the entry may include more than one set of PRACH opportunities. Table 3 is an example of such a PRACH mask index value. The WTRU may determine that a first set of ROs indicated by the table entry may be associated with a first cell (e.g., the WTRU may transmit a PRACH to the first cell using an RO from that set), that a second set of ROs indicated by the table entry may be associated with a second cell (e.g., the WTRU may transmit a PRACH to the second cell using an RO from that set), etc.

[0169] [Table 3]

[0170] The WTRU may be indicated with two or more SSB / CSI-RS indices. The SSB / CSI-RS indices may be used by the WTRU to determine the RO on which the preamble may be transmitted. The SSB / CSI-RS may be associated with different cells. The WTRU may use rules that specify how the SSB / CSI-RS are mapped to the RO, for example, if / when determining the RO opportunity from the SSB / CSI-RS index.

[0171] The WTRU may, for example, transmit (e.g., decide to transmit) a preamble on an RO selected from one of the allowed ROs when one preamble index is indicated. The WTRU may, for example, transmit (e.g., decide to transmit) a preamble on a first RO selected from a first set of allowed ROs and on a second RO selected from a second set of allowed ROs when / if the WTRU is indicated two or more sets of allowed ROs. The WTRU may, for example, transmit (e.g., decide to transmit) a first preamble on a first RO selected from the first set of allowed ROs, a second preamble on a second RO selected from the second set of allowed ROs, etc. when / if two or more preambles are indicated.

[0172] In some examples, the WTRU procedure may implement one or more of the following, for example, if / when two separate sets of ROs are provided: the WTRU may receive a PDCCH order; the WTRU may determine a preamble index from the PDCCH order; the WTRU may determine a first PRACH mask index value and a second PRACH mask index value from the PDCCH order (e.g., the WTRU may determine a first set of ROs from the first PRACH mask index value and / or the WTRU may determine a second PRACH mask index value). the WTRU may determine a second set of ROs from the ACH mask index value; the WTRU may determine a first RO within the first set of ROs from the first SSB / CSI-RS index (e.g., after mapping the SSB / CSI-RS index to the first RO set); the WTRU may determine a second RO within the second RO set from the second SSB / CSI-RS index (e.g., after mapping the SSB / CSI-RS to the second RO set); or the WTRU may transmit a preamble on the first RO and the second RO.

[0173] ROs may be shared between cells. In some examples, the WTRU may be indicated a single PRACH mask index value. The WTRU may determine the set of allowed RO opportunities from a combination of the SSB / CSI-RS index and the PCI index, which may be achieved, for example, using one or more of the following: The WTRU may (e.g., first) assign subgroups of ROs to different cells. The WTRU may determine the ROs for PRACH transmissions from SSB / CSI-RS associated with a cell (e.g., within the subgroup assigned to the cell). Examples are shown in Figures 6-8. Figure 6 shows an example of configured ROs. Figure 7 shows an example of allowed ROs, for example, after applying a PRACH mask (e.g., as indicated by the dashed outline applied to RO#2, RO#6, RO#4, RO#8, RO#10, and RO#12). Figure 8 shows an example of assigning allowed ROs to different PCIs and re-indexing.

[0174] The WTRU may (e.g., first) determine the RO from configuration parameters (e.g., as shown in FIG. 6). The WTRU may determine the allowed RO, for example, by applying a PRACH mask (e.g., as shown in FIG. 7). The allowed RO may be assigned to a PCI and possibly re-indexed (e.g., as shown in FIG. 8). The corresponding SSB / CSI-RS may be mapped to an RO from multiple ROs assigned to the PCI (e.g., per PCI). The WTRU may assign an index to each (PCI) / (SSB / CSI-RS) combination. The WTRU may (e.g., then) map the combination to the allowed RO first by frequency, then by time, then by PRACH slot, and so on.

[0175] The WTRU may generate a beam if / when transmitting a PRACH, e.g., if / when the WTRU is equipped with multiple transmit antennas. The WTRU may (e.g., also) generate multiple beams, e.g., if / when the WTRU is equipped with multiple transmit / receive units.

[0176] For example, if a WTRU is indicated to transmit a preamble using beamforming, the WTRU may use k (e.g., k=2) TXRUs to generate multiple (e.g., two) beams in multiple (e.g., two) directions associated with multiple (e.g., two) SSB / CSI-RSs. A WTRU (e.g., a WTRU having this capability) may transmit (e.g., be capable of transmitting) a preamble in multiple (e.g., two) different directions on the same time resource. A WTRU (e.g., a WTRU equipped with a single TXRU) may transmit a preamble on multiple (e.g., two) non-overlapping time opportunities. Whether a WTRU can transmit on the same time resource may be based on WTRU capability and / or configuration. For example, if a WTRU has multiple (e.g., two) RF chains and is capable of implementing MU-MIMO, the WTRU may transmit (e.g., be permitted to transmit) a preamble on the same overlapping time resource.

[0177] For example, if a WTRU transmits PRACHs associated with different cells on different beams but is equipped with a single transmit chain, the WTRU may not be allowed RO to different PCIs in the same time resource.

[0178] Although the above-described features and elements are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or may be used in various combinations with or without the other features and elements.

[0179] While the implementations described herein may take into account 3GPP-specific protocols, it is understood that the implementations described herein are not limited to this scenario and are applicable to other wireless systems. For example, while the solutions described herein take into account LTE, LTE-A, New Radio (NR), or 5G-specific protocols, it is understood that the solutions described herein are not limited to this scenario and are applicable to other wireless systems.

[0180] The above processes may be implemented in a computer program, software, and / or firmware embodied in a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and / or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as, but not limited to, internal hard disks and removable disks), magneto-optical media, and / or optical media (such as, but not limited to, compact disc (CD)-ROM disks and / or digital versatile discs (DVDs)). A processor in combination 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.

Claims

1. 1. A wireless transmit / receive unit (WTRU), comprising: receiving configuration information indicating a first set of cells, a second set of cells, random access information associated with the first set of cells, and random access information associated with the second set of cells; receiving a first indication, the first indication indicating the first set of cells; determining a random access preamble, resource, or parameter associated with a cell in the first set of cells, the random access preamble, resource, or parameter being determined based on the configuration information and the first indication; receiving a second indication, the second indication indicating to send a Physical Random Access Channel (PRACH) transmission to a cell, the cell being in the first set of cells; transmitting the PRACH transmission to at least the cell, wherein the PRACH transmission uses the random access preamble, resources, or parameters; 10. A WTRU comprising: a processor configured to execute:

2. The WTRU of claim 1 , wherein the first indication is received via a medium access control (MAC) control element (CE).

3. 10. The WTRU of claim 1, wherein the second indication is received via a physical downlink control channel (PDCCH) transmission.

4. The WTRU of claim 1 , wherein the processor is further configured to receive a timing advance value based on the PRACH transmission.

5. The WTRU of claim 4 , wherein the processor is further configured to transmit another PRACH transmission to the cell based on the timing advance value.

6. The WTRU of claim 1 , wherein the configuration information is received via radio resource control (RRC) signaling.

7. The WTRU of claim 1 , wherein the second indication includes at least one of an index associated with the first set of cells or a set of cell / SSB combinations.

8. 2. The WTRU of claim 1, wherein the first indication is included in a first transmission, the second indication is included in a second transmission, and the first transmission is received prior to the second transmission.

9. 2. The WTRU of claim 1, wherein the processor being configured to transmit the PRACH transmission to at least the cell comprises the processor being configured to transmit the PRACH transmission to a subset of cells in the first set of cells, the first set of cells including the cell.

10. 1. A method performed by a wireless transmit / receive unit (WTRU), comprising: receiving configuration information indicating a first set of cells, a second set of cells, random access information associated with the first set of cells, and random access information associated with the second set of cells; receiving a first indication, the first indication indicating the first set of cells; receiving a second indication, the second indication indicating to transmit a Physical Random Access Channel (PRACH) transmission to a cell; and transmitting the PRACH transmission to a subset of cells in the first set of cells based on the second indication; A method comprising:

11. 11. The method of claim 10, wherein the first indication is received via a Medium Access Control (MAC) Control Element (CE).

12. 11. The method of claim 10, wherein the second indication is received via a Physical Downlink Control Channel (PDCCH) transmission.

13. The method of claim 10 , further comprising receiving a timing advance value based on the PRACH transmission.

14. The method of claim 10 , wherein the second indication indicates the first set of cells.

15. The method of claim 10 , wherein the second indication does not indicate the first set of cells.

16. 11. The method of claim 10, determining a random access preamble, resource, or parameter associated with a cell in the first set of cells, the random access preamble, resource, or parameter being determined based on the configuration information and the first indication, and the PRACH transmission using the random access preamble, resource, or parameter.

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