PDCCH Command for PRACH Transmission in Multi-TRP Operation

Abstract

A WTRU may receive downlink control information (DCI) from a first transmit / receive point (TRP). The DCI may indicate that the WTRU transmits a physical random access channel (PRACH) transmission. The DCI may include an indication of a preamble, an indication of a first PRACH mask, and / or an indication associated with a first synchronization signal block (SSB), and / or an indication of a reference signal (RS). The WTRU may be configured to transmit a preamble within a first PRACH resource to a second TRP. The first TRP and / or the second TRP may be associated with the same physical cell identification information (PCI). The WTRU may receive a first response to the preamble from the second TRP. The first response may include a first timing advance (TA) command for a second timing alignment for transmission to the second TRP, and / or an index indicating the second TRP.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the priority of U.S. Provisional Patent Application No. 63 / 334,976, filed in the United States on April 26, 2022, the entire content of which is incorporated herein by reference.

[0002] (Field of the Invention) This disclosure generally relates to wireless communication systems. Specifically, this disclosure relates to methods and apparatuses for multi - transmission / reception point (mTRP) using multiple timing advance (TA) operations in a wireless communication system.

Background Art

[0003] After the commercialization of 4G communication systems, due to the increasing demand for wireless data traffic, efforts have been made to develop improved 5G communication systems. For this reason, 5G communication systems or pre - 5G communication systems are called communication systems that are systems after 4G networks (Beyond 4G networks) or systems after LTE (Post LTE).

[0004] To achieve high data rates, the implementation of 5G communication systems in very high - frequency (mmWave) bands (e.g., 60 gigahertz (60 GHz) bands, etc.) is being considered. To mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra - high - frequency band, beamforming, massive MIMO, and full - dimensional MIMO (FD - MIMO), array antennas, analog beamforming, and large - scale antenna technologies are being considered in 5G communication systems.

[0005] For the improvement of the system network, the development of evolved small cells, high - altitude small cells, cloud radio access network (cloud RAN), ultra - dense network, Device to Device communication (D2D), wireless backhaul, mobile network, cooperative communication, Coordinated Multi - Point (CoMP), and interference cancellation technology is further advanced in the 5G communication system.

[0006] In addition, in the 5G system, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), as well as advanced access technologies such as Filter Bank Multi Carrier (FBMC), NOMA (non - orthogonal multiple access), and sparse code multiple access (SCMA) are being studied.

Summary of the Invention

[0007] Systems, methods, and apparatuses related to multi-transmit / receive points (mTRPs) using multiple timing advance (TA) operations in a wireless system are described herein. A wireless transmit / receive unit (WTRU) may receive a PDCCH order for triggering Physical Random Access Channel (PRACH) transmission and / or transmit one or more first PRACHs according to the received PDCCH order by using one or more of the indicated preamble index, Synchronization Signal (SS) index / Physical Broadcast Channel (PBCH), and / or PRACH mask when the WTRU is configured with multi-TRP operation in a multi-TRP deployment.

[0008] In an example, an implementation may include determining an uplink TA value for transmission of an uplink signal, the uplink TA value being determined based on a single TA loop, and / or transmitting one or more PRACHs for starting a second TA loop based on receiving an indication for transmitting a second PRACH.

[0009] In an example, an implementation may include operating a timing advance timer (TAT) for one or more TRPs associated with a TRP link and / or determining one or more intended TRPs for one or more TAs indicated based on the received PDCCH.

[0010] The system, method, and apparatus may include receiving one or more timing advance groups (TAGs) for a serving cell, where one or more (e.g., each) TAG is associated with a TRP link, and / or applying a TAG associated with a TRP.

[0011] Systems, methods, and apparatuses related to PDCCH commands for PRACH transmission in mTRP operation are described herein. A WTRU may receive downlink control information (DCI) from a first transmission / reception point (TRP). The DCI may indicate that the WTRU transmits a physical random access channel (PRACH) transmission. The DCI may include an indication of a preamble, an indication of a first PRACH mask, and / or an indication associated with a first synchronization signal block (SSB), and / or an indication of a reference signal (RS). The WTRU may be configured to transmit the preamble to a second TRP in a first PRACH resource. The first PRACH resource may be determined based on, for example, the first PRACH mask and / or the first SSB. The preamble may be transmitted using a spatial filter determined based on, for example, the indicated RS. The first TRP and / or the second TRP may be associated with the same physical cell identity (PCI).

[0012] The WTRU may determine to send a preamble to a second TRP, for example, based on a spatial filter. The WTRU may maintain a first timing alignment for transmission to the first TRP and / or maintain a second timing alignment for transmission to the second TRP. The WTRU may receive a first response to the preamble from the second TRP. The first response may include a first timing advance (TA) command for the second timing alignment for transmission to the second TRP and / or an index indicating the second TRP. The first response may be a Random Access Response (RAR). The WTRU may be configured to transmit an uplink (UL) transmission to the second TRP using the determined spatial filter and / or at a timing based on the first TA command. The WTRU may determine a spatial filter to use for transmitting the preamble to the second TRP using the indicated RS.

[0013] The WTRU may receive DCI in a PDDCH command that triggers a PRACH transmission. The DCI may include an indication of a second PRACH mask and / or an indication associated with a second SSB. The WTRU may transmit a preamble to the first TRP using a second PRACH resource determined, for example, based on the second PRACH mask and / or the second SSB. The WTRU may receive a second response to the preamble transmitted using the second PRACH resource from the first TRP. The second response may include a timing advance command for the first timing alignment for transmission to the first TRP. The second response may include an index of the first TRP. The DCI may include a timing advance (TA) medium access control (MAC) control element (CE). The MAC CE may indicate a TRP index. The TRP may indicate that the TA is associated with the first TRP and / or the second TRP.

Brief Description of the Drawings

[0014]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2

Figure 3

Figure 4

[0015] FIG. 1A is a diagram illustrating an exemplary communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to a plurality of wireless users. The communication system 100 may enable a plurality of wireless users to access such content through sharing of system resources including wireless bandwidth. For example, the communication system 100 may use one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0016] As shown in Figure 1A, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. It will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and / or "STA", can be configured to transmit and / or receive wireless signals and can be a user equipment (UE), a mobile station, a fixed subscriber unit or a mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., for remote surgery), an industrial device and application (e.g., a robot and / or other wireless device operating in an industrial and / or automated processing chain context), a home appliance device, a device operating in a commercial wireless network and / or an industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d can be interchangeably referred to as a UE.

[0017] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks such as CN106 / 115, the Internet 110, and / or other network 112. By way of example, base stations 114a, 114b may be a base transceiver station (BTS), Node B, eNode B, home Node B, home eNode B, gNB, NR Node B, site controller, access point (AP), wireless router, etc. Base stations 114a, 114b are each depicted as a single element, but it will be understood that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0018] Base station 114a may be part of RAN 104 / 113 and may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals at one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage to a specific geographic area that may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, base station 114a may use multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0019] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via 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.). Air interface 116 may be established using any suitable radio access technology (RAT).

[0020] More specifically, as described above, the communication system 100 can be a multiple access system, and can use one or more channel access methods such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a within RAN104 / 113, and WTRUs 102a, 102b, 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use wideband CDMA (WCDMA) to establish air interfaces 115 / 116 / 117. WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0021] In one embodiment, the base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can use Long Term Evolution (LTE), and / or LTE-Advanced (LTE-A), and / or LTE-Advanced Pro (LTE-A Pro) to establish air interface 116.

[0022] In one embodiment, the base station 114a, and WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can use New Radio (NR) to establish air interface 116.

[0023] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for example, using the dual connectivity (DC) principle. Accordingly, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by transmissions sent to / from multiple types of radio access technologies and / or multiple types of base stations (e.g., eNBs and gNBs).

[0024] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), IS-856, Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0025] The base station 114b in Fig. 1A can be, for example, a wireless router, a home node B, a home e-node B, or an access point, and can utilize any suitable RAT to facilitate wireless connection in a local area such as an office, a home, a vehicle, a campus, an industrial facility, an aerial corridor (for use by drones, for example), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a wireless 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 can implement a wireless 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 can utilize a cellular-based RAT (such as WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As shown in Fig. 1A, the base station 114b can have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0026] RAN 104 / 113 can communicate with CN 106 / 115, which can be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of WTRUs 102a, 102b, 102c, 102d. The data can have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 can provide call control, billing services, mobile location-based services, prepaid calls, internet connectivity, video delivery, etc., and / or can implement high-level security functions such as user authentication. Although not shown in Figure 1A, it will be understood that RAN 104 / 113 and / or CN 106 / 115 can communicate directly or indirectly with other RANs that use the same radio access technology (RAT) or a different RAT than RAN 104 / 113. For example, in addition to being connected to a RAN 104 / 113 that can utilize New Radio (NR) radio technology, CN 106 / 115 can also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0027] CN106 / 115 can also serve as a gateway for WTRU102a, 102b, 102c, 102d to access the PSTN108, the Internet 110, and / or other networks 112. The PSTN108 can include a circuit-switched telephone network that provides a plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices, and these networks and devices use common communication protocols such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP internet protocol suite. The network 112 can include a wired communication network and / or a wireless communication network that is owned and / or operated by another service provider. For example, the network 112 can include another CN connected to one or more RANs that can use the same RAT or a different RAT as the RAN104 / 113.

[0028] Some or all of the WTRU102a, 102b, 102c, 102d in the communication system 100 can include a multi-mode function (e.g., the WTRU102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks via different wireless links). For example, the WTRU102c shown in Figure 1A can be configured to communicate with a base station 114a that can use a cellular-based wireless technology and a base station 114b that can use IEEE802 wireless technology.

[0029] Figure 1B is a system diagram illustrating an exemplary WTRU102. As shown in Figure 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, a non-removable memory 130, a removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripheral devices 138. It will be understood that the WTRU 102 may include any partial combination of the foregoing elements while remaining consistent with one embodiment.

[0030] The processor 118 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120 which may be coupled to the transmit / receive element 122. Although Figure 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.

[0031] The transmit / receive element 122 may be configured to transmit or receive signals to / from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0032] Although the transmit / receive element 122 is depicted in FIG. 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may utilize 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 via the air interface 116.

[0033] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have a multimode capability. 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.

[0034] The processor 118 of the WTRU 102 may be coupled to the speaker / microphone 124, keypad 126, and / or display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit), and may receive data input by a user therefrom. The processor 118 may also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. In addition, the processor 118 may access information from any suitable type of memory, such as the non-removable memory 130 and / or the removable memory 132, and may store data in the memory. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown), and may store data in the memory.

[0035] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components within 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 cells (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0036] The processor 118 may also be coupled to a GPS chipset 136 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 a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or may determine its location based on the timing of signals received from two or more neighboring base stations. It will be understood that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with one embodiment.

[0037] The processor 118 may also be further coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral devices 138 may include one or more sensors, which 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.

[0038] WTRU102 may include a full-duplex radio in which some or all of the transmission and reception of signals (associated with, for example, specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) can be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, WRTU102 may include a half-duplex radio for transmitting and receiving some or all of the signals (associated with, for example, specific subframes for either UL (e.g., for transmission) or downlink (e.g., for reception)).

[0039] Figure 1C is a system diagram illustrating RAN104 and CN106 according to one embodiment. As described above, RAN104 may use E-UTRA radio technology to communicate with WTRU102a, 102b, 102c via air interface 116. RAN104 may also communicate with CN106.

[0040] RAN104 may include eNodeBs 160a, 160b, 160c, although it will be understood that RAN104 may include any number of eNodeBs while remaining consistent with one embodiment. Each of eNodeBs 160a, 160b, 160c may include one or more transceivers for communicating with WTRU102a, 102b, 102c via air interface 116. In one embodiment, eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, eNodeB 160a, for example, may transmit wireless signals to and / or receive wireless signals from WTRU102a using multiple antennas.

[0041] Each of the eNodeBs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, etc. As shown in FIG. 1C, the eNodeBs 160a, 160b, and 160c may communicate with each other via the X2 interface.

[0042] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0043] The MME 162 may be connected to each of the eNodeBs 162a, 162b, and 162c in the RAN 104 via the S1 interface and may function as a control node. For example, the MME 162 may serve roles such as authenticating users of the WTRUs 102a, 102b, and 102c, activating / deactivating bearers, selecting a particular serving gateway during the initial attach of the WTRUs 102a, 102b, and 102c, etc. The MME 162 may provide control plane functions for switching between the RAN 104 and other RANs (not shown) using other radio technologies such as GSM and / or WCDMA.

[0044] SGW164 can be connected to each of the eNodeBs 160a, 160b, and 160c in RAN104 via the S1 interface. SGW164 can generally route and transfer user data packets between the WTRUs 102a, 102b, and 102c. SGW164 can perform other functions such as the function of anchoring the user plane during handover between eNodeBs, the function of triggering paging when DL data is available to the WTRUs 102a, 102b, and 102c, and the function of managing and storing the contexts of the WTRUs 102a, 102b, and 102c.

[0045] SGW164 can be connected to PGW166, but PGW166 can provide the WTRUs 102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, and 102c and IP-enabled devices.

[0046] CN106 can facilitate communication with other networks. For example, CN106 can provide the WTRUs 102a, 102b, and 102c with access to a circuit-switched network such as PSTN108 to facilitate communication between the WTRUs 102a, 102b, and 102c and conventional landline communication devices. For example, CN106 can include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that functions as an interface between CN106 and PSTN108. In addition, CN106 can provide the WTRUs 102a, 102b, and 102c with access to other networks 112 that may include other wired and / or wireless networks owned and / or operated by other service providers.

[0047] The WTRU is described as a wireless terminal in FIGS. 1A - 1D, but in certain representative embodiments, it is contemplated that such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0048] In a representative embodiment, the other network 112 can be a WLAN.

[0049] A WLAN in infrastructure basic service set (BSS) mode can have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP can have an access or interface to another type of wired / wireless network that carries traffic entering and / or exiting the distribution system (DS) or BSS. Traffic destined for an STA that originates outside the BSS can arrive and be sent to the STA through the AP. Traffic originating from an STA and destined for a destination outside the BSS can be sent to the AP so as to be sent to their respective destinations. Traffic between STAs within the BSS can be transmitted through the AP, for example. The source STA can send traffic to the AP, and the AP can send the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between the source STA and the destination STA (e.g., directly between them) using direct link setup (DLS). In certain representative embodiments, DLS can use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all of the STAs) can communicate directly with each other. The IBSS mode of communication can be referred to herein as the "ad hoc" communication mode.

[0050] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may transmit beacons on a fixed channel such as the primary channel. The primary channel can be of a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In certain representative embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented. In the case of CSMA / CA, STAs including the AP (e.g., all STAs) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. Only one STA (e.g., only one station) can transmit at any given time in a given BSS.

[0051] A High Throughput (HT) STA can use a 40 MHz wide channel for communication, and this 40 MHz wide channel can be formed, for example, via a combination of a primary 20 MHz channel and an adjacent or non - adjacent 20 MHz channel.

[0052] A Very High Throughput (VHT) STA can support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. A 40 MHz and / or 80 MHz channel can be formed by combining multiple adjacent 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels or by combining two non-adjacent 80 MHz channels, which can be referred to as an 80+80 configuration. In the case of the 80+80 configuration, after channel encoding, the data can pass through a segment parser that can divide the data into two streams. The Inverse Fast Fourier Transform (IFFT) process and time domain processing can be performed separately for each stream. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC).

[0053] The sub-1 GHz operating mode is supported by 802.11af and 802.11ah. The channel operating bandwidth and carrier frequency are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV White Space (TVWS) spectrum, and 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz using non-TVWS spectrum. According to an exemplary embodiment, 802.11ah may support meter type control / machine type communication, such as MTC devices within a macro communication range area. The MTC device may have limited capabilities, including support for certain capabilities, such as support for a particular and / or limited bandwidth (e.g., supporting only these). The MTC device may include a battery having a battery life above a threshold (e.g., to maintain a very long battery life).

[0054] A WLAN system that supports a plurality of channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah includes channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by an STA from among all STAs operating in a BSS that supports a minimum bandwidth operation mode. In an example of 802.11ah, the primary channel is 1 MHz wide for an STA (e.g., an MTC type device) that supports the 1 MHz mode (e.g., supports only this) even when the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or Network Allocation Vector (NAV) setting may depend on the status of the primary channel. For example, due to an STA transmitting to an AP (supporting only the 1 MHz operation mode), when the primary channel is in operation, most of the frequency band remains in an operation pause and, even if it may be available, the entire available frequency band may be considered to be in operation.

[0055] In the United States, the available frequency band that can be used by 802.11ah is 902 MHz to 928 MHz. In Korea, the available frequency band is 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz depending on the country code.

[0056] FIG. 1D is a system diagram illustrating RAN 113 and CN 115 according to one embodiment. As described above, RAN 113 may use NR radio technology to communicate with WTRUs 102a, 102b, 102c via air interface 116. RAN 113 may also communicate with CN 115.

[0057] RAN 113 may include gNBs 180a, 180b, and 180c, but it will be understood that RAN 113 may include any number of gNBs while remaining consistent with one embodiment. Each of gNBs 180a, 180b, and 180c may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 108b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, and 180c. Thus, gNB 180a, for example, may transmit and / or receive radio signals from WTRU 102a using multiple antennas. In one embodiment, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of such component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one embodiment, gNBs 180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0058] WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using transmissions associated with scalable numerology. For example, the OFDM symbol interval and / or the OFDM sub-carrier interval can vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using sub-frames or transmission time intervals (TTIs) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or having absolute times of various lengths).

[0059] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in a stand-alone configuration and / or a non-stand-alone configuration. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNodeBs 160a, 160b, and 160c, etc.). In a stand-alone configuration, WTRUs 102a, 102b, and 102c can utilize one or more of gNBs 180a, 180b, and 180c as mobility anchor points. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in an unlicensed band. In a non-stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with and connect to gNBs 180a, 180b, and 180c while also communicating with and connecting to another RAN such as eNodeBs 160a, 160b, and 160c. For example, WTRUs 102a, 102b, and 102c can implement a DC principle for communicating with one or more gNBs 180a, 180b, and 180c and one or more eNodeBs 160a, 160b, and 160c substantially simultaneously. In a non-stand-alone configuration, eNodeBs 160a, 160b, and 160c can function as mobility anchors for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, and 102c.

[0060] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in 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, and routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, gNBs 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0061] As shown in FIG. 1D, CN 115 can include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and optionally data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of CN 115, it will be understood that any of these elements can be owned and / or operated by entities other than the CN operator.

[0062] AMF 182a and 182b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can function as control nodes. For example, AMF 182a and 182b can play roles such as user authentication of WTRUs 102a, 102b, and 102c, support for network slicing (e.g., handling different PDU sessions with different requirements), selection of specific SMFs 183a and 183b, registration area management, termination of NAS signaling, and mobility management. Network slices can be used by AMF 182a and 182b to customize the CN support for WTRUs 102a, 102b, and 102c based on the type of service being utilized by WTRUs 102a, 102b, and 102c. For example, different network slices can be established for different use cases such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, and services for machine type communication (MTC) access. AMF 162 can provide control plane functions for exchange between RAN 113 and other RANs (not shown) that use other radio technologies such as non-3GPP access technologies like LTE, LTE-A, LTE-A Pro, and / or WiFi.

[0063] SMF183a and 183b can be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b can also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b can select and control UPF184a and 184b and configure the routing of traffic through UPF184a and 184b. SMF183a and 183b can perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. The PDU session type can be IP-based, non-IP-based, Ethernet-based, etc.

[0064] UPF184a and 184b can be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N3 interface, thereby providing WTRU102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU102a, 102b, and 102c and IP-corresponding devices. UPF184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-home PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0065] CN115 may facilitate communication with other networks. For example, CN115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that functions as an interface between CN115 and PSTN108. In addition, CN115 may provide WTRU102a, 102b, 102c with access to other networks 112 that may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU102a, 102b, 102c may be connected to local data networks (DN) 185a, 185b through UPF184a, 184b via an N3 interface to UPF184a, 184b and an N6 interface between UPF184a, 184b and DN185a, 185b.

[0066] In view of FIGS. 1A - 1D and the corresponding descriptions thereof, one or more of the functions described herein with respect to one or more of WTRU102a - d, base stations 114a and b, e - NodeB 160a - c, MME162, SGW164, PGW166, gNB180a - c, AMF182a - ab, UPF184a and b, SMF183a and b, DN185a and b, and / or any other devices described herein may be implemented by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functionality.

[0067] An emulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more emulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more emulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. An emulation device can be directly coupled to another device for testing purposes and / or can perform tests using terrestrial wireless communication.

[0068] One or more emulation devices can perform one or more functions including all while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device can be utilized in a test scenario in a test laboratory and / or in a non-deployed (e.g., for testing) wired and / or wireless communication network to implement tests of one or more components. One or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via an RF circuit (which can include one or more antennas) can be used by an emulation device to transmit and / or receive data.

[0069] The term aTRP can be used interchangeably with the term secondary transmit / receive point (sTRP) herein.

[0070] In an example, one of the new radio (NR) multiple-input multiple-output (MIMO) functions could have been the mTRP operation where the TRPs share the same physical cell identifier (PCI). As an evolution, in Rel-17, this study may have extended the scope of the mTRP scenario using one or more different functions, including an integrated TCI concept that enables faster and / or more efficient (e.g., much more efficient) management of one or more transmit configuration identification (TCI) states and / or beam management. Reception from one or more TRPs may be determined within the cyclic prefix. This may have enabled complete timing synchronization (e.g., alignment of one or more transmissions among one or more TRPs) determined among one or more TRPs. For example, synchronization may include the WTRU maintaining timing alignment for transmissions with two or more TRPs. For example, the WTRU may maintain (e.g., use) a first timing alignment for transmissions to a first TRP and maintain (e.g., use) a second timing alignment for transmissions to a second TRP.

[0071] In an example, the MIMO evolution work item may have gone a step further by enabling two timing advance (TA) loops, for example, based on two non-collocated TRPs, two WTRU antenna panels, up to four UL MIMO layers, two layers per panel, and / or mDCI (e.g., multi-DCI) reception and / or simultaneous / duplicate physical uplink shared channel (PUSCH) PUSCH+PUSCH and / or physical uplink control channel (PUCCH) PUCCH-PUCCH UL transmissions, and / or may have been intended to diversify one or more deployments.

[0072] FIG. 2 is a diagram illustrating an example of an absolute timing advance command MAC CE 200. In the example, the absolute timing advance command MAC CE 200 can be identified by a MAC sub-header having an extended logical channel ID (eLCID). The MAC indication can have a fixed size and / or can include two (e.g., two or more) octets defined as shown in FIG. 2. In the example, the timing advance command field can indicate an index value TA. In the example, TA can be used to control the amount of timing adjustment that the MAC entity may have to apply. In the example, the size of the TA command field can be 12 bits. In the example, R202 can be a reserved bit that can be set, for example, to 0. The MAC CE 200 can indicate whether TA is associated with the first TRP and / or the second TRP. For example, the MAC CE 200 can indicate a TRP index indicating that TA is associated with the first TRP and / or the second TRP.

[0073] Figure 3 illustrates an example of a relative timing advance command MAC CE 300. In the example, the WTRU may receive a relative TA command format while in the connected mode. In the example, the TA command MAC CE 300 may be identified by a MAC sub-header having an LCID. In the example, the command may have a fixed size and / or may include a single octet as shown in Figure 3. In the example, the timing advance group (TAG) identification information (TAG Identity, TAG ID) field 302 may indicate the TAG identification information of the addressed TAG. In the example, the TAG including the SpCell may have a TAG identification information of 0. In the example, the length of the field may be 2 bits. In the example, the TA command field 304 may indicate an index value TA (e.g., 0, 1, 2, 3, 4, 5,... 63, etc.). The timing advance command field 304 may be used to control the amount of timing adjustment that the MAC entity must apply. In the example, the length of the field may be 6 bits. The MAC CE 300 may indicate whether the TA is associated with the first TRP and / or the second TRP. For example, the MAC CE 300 may indicate a TRP index indicating that the TA is associated with the first TRP and / or the second TRP. For example, the TAG ID field 302 may indicate the TRP index.

[0074] In an example, in a transmission system with a single TA support, the serving cell can be associated with a single TAG, in which case one or more (e.g., each) TAGs can be associated with a single time alignment timer. In an example, if the WTRU does not receive an update within the time window set by the timer, the timer can expire and / or the WTRU can interrupt one or more (e.g., all) UL transmissions to the affected cell, separate from the random access preamble transmission and / or MsgA transmission. In an example, if the timer expires, the WTRU can flush one or more (e.g., all) HARQ buffers. In an example, if the timer expires, the WTRU can release one or more (e.g., all) configured PUCCHs and / or sounding reference signals (SRS). In an example, if the timer expires, the WTRU can clear one or more (e.g., all) configured downlink allocations. In an example, if the timer expires, the WTRU can clear one or more (e.g., all) configured UL grants. In an example, if the timer expires, the WTRU can clear one or more (e.g., any, all) PUSCH resources for semi-persistent CSI for one or more (e.g., all) serving cells at the expiration of the timeAlignementTimer associated with the PTAG, where the PTAG can be, for example, the TAG group to which the SpCell belongs (e.g., otherwise, one or more expiration actions can be performed only on one or more serving cells associated with the TAG). In an example, if the timer expires, the WTRU can clear one or more PUSCH resources for semi-persistent CSI for all serving cells at the expiration of the timeAlignementTimer associated with the PTAG, where the PTAG can be, for example, the TAG group to which the SpCell belongs. In an example, if the timer expires, the WTRU can clear all PUSCH resources for semi-persistent CSI for one or more serving cells at the expiration of the timeAlignementTimer associated with the PTAG, where the PTAG can be, for example, the TAG group to which the SpCell belongs.In an example, when the timer expires, the WTRU may clear all PUSCH resources for semi-persistent CSI for all serving cells upon expiration of the timeAlignmentTimer associated with the PTAG, where the PTAG may be, for example, the TAG group to which the SpCell belongs. In an example, the expiration action may be performed for the serving cell associated with the TAG. In an example, the expiration action may be performed only for the serving cell associated with the TAG.

[0075] In an example, in NR operation, the MAC CE that carries the TA command may be associated with a specific cell. For example, in a multi-TRP (or mTRP) scenario where multiple TRPs can be associated with the same cell, individual TA indications for one or more (e.g., each) transmit / receive points (TRPs) may not be supported. In an example, when individual TA indications for one or more (e.g., each) TRPs are supported, it may be difficult to estimate one or more individual TA values for one or more (e.g., each) TRP links. For example, in an in-cell mTRP scenario, the PCI may include the serving cell. The serving cell may be referred to as the Primary TRP (pTRP). The pTRP may have an SSB configuration. For example, in an in-cell mTRP scenario, the PCI may include additional TRPs (sTRPs) that may not have an SSB configuration. In an example, the sTRP may be measured by the WTRU with Channel State Information-Reference Signal (CSI-RS) and / or one or more tracking RSs. In an example, the MAC CE that carries the TA command may be associated with a MAC entity having a specific cell. For example, the MAC CE TA command may not be associated with the primary TRP. For example, the MAC CE TA command may not be associated with the sTRP as described herein. In an example, the timing advance measurement and / or the association of the TA command may be initiated for individual radio links and / or for one or more simultaneous TA commands and / or their (e.g., respective) applications. The MAC CE may indicate whether the TA command is associated with the primary TRP and / or the secondary TRP. For example, the MAC CE may indicate a TRP index indicating that the TA command is associated with the primary TRP and / or the secondary TRP.

[0076] Systems, methods, and / or apparatuses are provided herein for procedures to initiate one or more (e.g., multiple) TA measurements and / or updates. Systems, methods, and / or apparatuses are provided herein for procedures for the indication and / or association of one or more (e.g., multiple) TAs to a TRP.

[0077] Systems, methods, and / or apparatuses are provided herein for procedures for the initiation and / or maintenance of one or more (e.g., multiple) TA measurements. In multi-DCI multi-TRP transmissions with multiple TA support, the WTRU may receive a PDCCH order for a random access channel (RACH) to update one or more TA values for one or more (e.g., each) TRP link.

[0078] The system, method, and / or apparatus may include PDCCH order PRACH transmissions in a multi-TRP. The gNB may trigger the transmission of a PRACH (e.g., including a set of one or more PRACH resources) to re-establish synchronization for uplink transmissions by the WTRU. Such initiation may occur for one or more different reasons. For example, the gNB may trigger the transmission of a PRACH when the WTRU has not been scheduled for transmission for a particular duration. In NR, the trigger for random access transmission to re-establish synchronization may be implemented through a PDCCH order, whereby the DCI may provide relevant information for the transmission of a PRACH (e.g., such as a preamble index and / or an SSB index) that can be used as a reference point for the determination of an associated RACH occasion. The WTRU may receive DCI from a first TRP. The DCI may indicate that the WTRU is to transmit a PRACH transmission. The DCI may include an indication of a preamble, an indication of a first PRACH mask, an indication associated with a first SSB, and / or an indication of an RS. The WTRU may receive the DCI in a PDCCH order that triggers a PRACH transmission.

[0079] The WTRU may determine a spatial filter based on the indicated RS. The WTRU may determine to transmit a preamble to a second TRP based on the spatial filter. The WTRU may transmit the preamble to the second TRP in a first PRACH resource that may be determined based on, for example, a first PRACH mask and / or a first SSB. The preamble may be transmitted using a spatial filter determined based on the indicated RS. The first TRP and the second TRP may be associated with the same physical cell identification information (PCI). The WTRU may receive a response to the preamble from the second TRP (e.g., a random access response (RAR), etc.). The response may include a timing advance (TA) command for timing alignment for transmission to the second TRP, and / or an index indicating the second TRP.

[0080] In mTRP deployment, the WTRU may maintain its own synchronization with one or more (e.g., two or more) different TRPs. For example, in mTRP deployment, the WTRU may be required to maintain its own synchronization with at least two different TRPs. As an example, the WTRU may be dynamically switched between a single TRP transmission mode and a multi-TRP transmission mode, which may require, for example, always maintaining accurate timing synchronization. For example, the WTRU may use a first timing alignment with a first TRP and a second timing alignment with a second TRP. The WTRU may be configured (e.g., including a set of one or more PRACH resources) to maintain accurate timing synchronization at (e.g., all) times if the WTRU may be dynamically switched between a single TYP transmission mode and a multi-TYP transmission mode. As described herein, a PDCCH command (e.g., sending a PRACH from a pTRP to an sTRP for UL synchronization / timing alignment) may include one or more of the following: a preamble identifier, a TRP indication indicating the sTRP (e.g., a CORESETPOOL index), an SSB index (e.g., associated with the pTRP), a PRACH mask, and / or an RS indicator associated with the sTRP (e.g., CSI-RS and / or tracking RS). If the timing alignment for the pTRP and the sTRP includes one PDCCH command, the PDCCH command may include a second SSB index and / or a second PRACH mask (e.g., associated with the pTRP). As described herein, a PDCCH command may include one or more of the following: a TRP index, a pTRP SSB index for determining a PRACH resource, and / or an sTRP RS for determining a filter for transmission (Tx). As described herein, the WTRU may transmit a preamble based on a preamble identifier using the determined PRACH resource and / or the determined spatial filter.As described herein, a WTRU may transmit a preamble based on a preamble identifier using a determined PRACH resource and / or a determined spatial filter. If the timing alignment for the pTRP and sTRP includes one PDCCH command, the WTRU may transmit the same preamble to the pTRP based on a second SSB index and / or a second PRACH mask. The WTRU may receive a RAR that includes a TRP indication and / or a TA indication. If the timing alignment for the pTRP and sTRP includes one PDCCH command, the RAR may include a second TA. The WTRU may transmit UL transmissions to the sTRP using the determined spatial filter and / or at a timing based on the TA indication.

[0081] In a multi-TRP deployment, a WTRU configured for multi-TRP operation may receive a PDCCH command to trigger a PRACH transmission. In an example, the WTRU may be configured with one or more of the behaviors described herein when the WTRU receives a PDCCH command for a PRACH transmission related to, for example, a single DCI multi-TRP operation or a multi-DCI multi-TRP operation.

[0082] In single DCI multi-TRP operation, PRACH transmission can be performed for the TRP that transmits the PDCCH command for PRACH. In an example, the WTRU can transmit a single PRACH according to the received PDCCH command by using the indicated preamble index (e.g., one or more PRACH resources), synchronization signal (SS) / PBCH index (e.g., SSB index), and / or PRACH mask. In an example (e.g., in this case), the WTRU can use the demodulation reference signal (DMRS) of the received PDCCH as the RS source for spatial information (e.g., a spatial filter based on an RS indicator) for the transmission of the preamble (e.g., based on the determined PRACH resource and / or the preamble identifier using the determined spatial filter). For example, the WTRU can transmit the preamble using a spatial filter based on the indicated RS (e.g., DMRS, etc.). In an example, the WTRU can receive a random access response (RAR) message including a TA and a TRP indication. In an example, the WTRU can apply the indicated TA for one or more (e.g., all) future transmissions to one or more (e.g., both) TRPs until the next TA indication. In an example, the WTRU can receive an implicit and / or explicit indication in, for example, the RAR message that the WTRU may apply the indicated TA to the TRP (e.g., TRP indication) that transmits the PDCCH command for one or more (e.g., all) future transmissions until the next TA indication. For example, the WTRU can receive a response message (e.g., RAR message) in response to the preamble. The response message may include a TA command for timing alignment for transmission to the TRP that transmits the PDCCH command.

[0083] In single DCI multi-TRP operation, PRACH transmission may be performed for a TRP that does not transmit a PDCCH order for PRACH. The WTRU may receive DCI from a first TRP. For example, the DCI may be received in a PDCCH order. The DCI may indicate that the WTRU transmits a PRACH transmission. In the example, based on information elements that may be carried by the same PDCCH (e.g., field), the WTRU may use, according to the received PDCCH order, for example, the indicated preamble index (e.g., one or more PRACH resources), SS / PBCH index (e.g., SSB index associated with the pTRP), TRP index, and / or PRACH mask to transmit a single PRACH to a second TRP (e.g., a TRP that does not transmit a PDCCH order / DCI). For example, the DCI may include an indication of a preamble, an indication of a first PRACH mask, an indication of a second PRACH mask, an indication associated with a first SSB, an indication associated with a second SSB, and / or an indication of an RS. The first TRP and the second TRP may be associated with the same physical cell identification information (PCI). Additionally or alternatively, the WTRU may detect an RS index indicated in the received PDCCH, and the RS index may be used as an RS source for spatial information (e.g., a spatial filter determined based on the RS source) for preamble transmission. For example, the WTRU may determine spatial information (e.g., a spatial filter) to use for transmitting a preamble to a second TRP based on the indicated RS (e.g., RS index or DMRS, etc.). The WTRU may transmit a preamble using a spatial filter determined based on the indicated RS (e.g., DMRS, etc.). For example, the WTRU may determine to transmit a preamble to a second TRP based on spatial information (e.g., a spatial filter). In the example, the indicated RS may be associated with another TRP. For example, the DCI may include an indication of a preamble (e.g., preamble index, etc.), an indication of a PRACH mask, an indication associated with an SSB (e.g., SS / PBCH index, etc.), and / or an indication of a reference signal (RS) (e.g., RS index, etc.).The DCI can be received in information elements that can be carried by the same PDCCH. The WTRU can transmit a preamble to a second TRP within a first PRACH resource determined based on a first PRACH mask and / or a first SSB. The WTRU can receive an RAR message including a TA. For example, the WTRU can receive a response message (e.g., an RAR message) in response to the preamble. The response message can include a TA command for timing alignment for transmission to a second TRP (e.g., a TRP that did not transmit a PDCCH order PRACH). For example, the WTRU can apply the TA indicated (e.g., by the TA command) for one or more (e.g., all) future transmissions to one or more (e.g., both) TRPs (e.g., TRP indication) until the next TA indication. For example, the WTRU can receive an implicit and / or explicit indication in, e.g., an RAR message, that the WTRU may apply the indicated TA to a TRP that did not transmit a PDCCH order PRACH for one or more (e.g., all) future transmissions until the next TA indication for this TRP (e.g., TRP indication). For example, the WTRU can receive an implicit or explicit indication in, e.g., an RAR message, that the WTRU may apply the indicated TA to a TRP that did not transmit a PDCCH order PRACH for future (e.g., all future) transmissions until the next TA indication (e.g., that TRP only). For example, the WTRU can transmit an uplink transmission to the second TRP at a timing based on the TA command using a determined spatial filter.

[0084] In single DCI multi-TRP operation, PRACH transmission for both TRPs can be based on the received PDCCH-ordered PRACH. In an example, the WTRU can transmit one or more PRACHs according to the information conveyed by the received PDCCH. The WTRU can detect one or more indicated values for one or more of a preamble index (e.g., one or more PRACH resources), an SS / PBCH index (e.g., an SSB index), and / or a PRACH mask. Additionally or alternatively, the WTRU can detect an RS index indicated in the received PDCCH, and the RS index can be used as an RS source for spatial information for preamble transmission (e.g., a spatial filter based on an RS indicator). In an example, the WTRU can receive a single PRACH index, one or more (e.g., two) synchronization signal blocks (SSB) / PBCH indexes, one or more (e.g., two) PRACH mask values, and one (e.g., one or more) RS index. The WTRU can transmit one or more (e.g., two) PRACHs using the same preamble index on two different occasions according to the indicated (e.g., two) SSB / PBCH indexes, (e.g., two) PRACH mask values, (e.g., two) DMRSs of the PDCCH, and / or the RSs indicated in the PDCCH for the first and / or second transmission. In an example, the WTRU can receive a RAR message including a single TA and / or a TRP indication. For example, the WTRU can apply the indicated TA for one or more (e.g., all) future transmissions to one or more (e.g., both) TRPs (e.g., the TRP indication) until the next TA indication. For example, the WTRU can receive an implicit and / or explicit indication (e.g., in the RAR message) that the WTRU may apply the indicated TA to a PDCCH-ordered PRACH for one or more (e.g., all) future transmissions to a TRP (e.g., that TRP only) for which the WTRU is transmitting and / or not transmitting the PDCCH-ordered PRACH until the next TA indication. In an example, the WTRU can receive a RAR message including one or more TAs.In accordance with one or more rules and / or received instructions, the WTRU may select and / or apply one or more of the TA values indicated for one or more (e.g., all) future transmissions to one or more (e.g., all) TRPs until the next TA indication. The WTRU may apply one or more of the indicated TA values to one or more corresponding TRPs.

[0085] In an example, in single DCI multi-TRP operation, PRACH transmissions for both TRPs may be based on the received PDCCH order PRACH. In an example, the WTRU may transmit two or more PRACHs in accordance with the information conveyed by the received PDCCH. In an example, the WTRU may detect one or more indicated values for at least one of a preamble index, e.g., an SS / PBCH index, and a PRACH mask. In an example, the WTRU may detect an RS index indicated in the received PDCCH, and the RS index may be used as an RS source for spatial information for preamble transmission. In an example, the WTRU may receive a single PRACH index, two SSB / PBCH indexes, two PRACH mask values, and / or one RS index. In an example, the WTRU may use the same preamble index on two different occasions in accordance with the two indicated SSB / PBCH indexes, two PRACH mask values, and use the two DMRSs of the PDCCH and / or the RS indicated in the PDCCH for the first and / or second transmission to transmit two PRACHs.

[0086] In an example, the WTRU may receive a RAR message that includes a single TA. In an example, the WTRU may apply the TA indicated for one or more (e.g., all) future transmissions to both TRPs until the next TA indication. In an example, the WTRU may receive, in the RAR message, an implicit and / or explicit indication that the WTRU may apply the indicated TA to a TRP for which the WTRU is transmitting and / or not transmitting a PDCCH order PRACH for one or more future transmissions until the next TA indication. In an example, the WTRU may receive, in the RAR message, an implicit and / or explicit indication that the WTRU may apply the indicated TA only to a TRP for which the WTRU is transmitting and / or not transmitting a PDCCH order PRACH for one or more (e.g., all) future transmissions until the next TA indication. In an example, the WTRU may receive a RAR message that includes two or more TAs. In an example, according to rules and / or received indications, the WTRU may select and / or apply one or more of the TA values indicated for one or more future transmissions to both TRPs until the next TA indication. In an example, according to rules or received indications, the WTRU may select and / or apply one of the TA values indicated for one or more (e.g., all) future transmissions to both TRPs until the next TA indication. In an example, the WTRU may apply the indicated TA value to the corresponding TRP. In an example, single DCI multi-TRP operation may include a PRACH transmission according to the last indicated multi-TRP mode. In single DCI multi-TRP transmission, for example, the WTRU may be dynamically scheduled to alternate between single-TRP transmission and multi-TRP transmission. Additionally or alternatively, for example, the WTRU may switch the order of transmissions. In an example, if the last scheduled uplink transmission was targeted at both TRPs (e.g., a multi-TRP operation mode indicated by a SRS Resource Indicator (SRI), e.g., code points 10 and / or 11), the WTRU may transmit a PRACH to one or more (e.g., both) TRPs.Additionally or alternatively, if the last scheduled uplink transmission was targeted at one of the TRPs (e.g., that TRP only) (e.g., single TRP operation mode as indicated by the SRI, e.g., code points 00 and / or 01), the WTRU may transmit a PRACH according to the corresponding TRP.

[0087] In multi-DCI multi-TRP operation, the WTRU may transmit a single PRACH per TRP according to received received PDCCH commands from one or more (e.g., each) TRPs. For example, for one or more (e.g., each) transmissions, the WTRU may use the indicated preamble index, SS / PBCH index, and / or PRACH mask. In an example, the WTRU may use the DMRS of one or more (e.g., each) received PDCCHs as the RS source for spatial information (e.g., a spatial filter based on an RS indicator) for transmission of one or more (e.g., each) preambles. In an example, the WTRU may receive a single RAR message that includes a single TA and / or TRP indication. For example, the WTRU may apply the indicated TA for one or more (e.g., all) future transmissions to one or more (e.g., both) TRPs (e.g., TRP indication) until the next TA indication. For example, the WTRU may receive in the RAR message, for example, an implicit and / or explicit indication that the WTRU may apply the indicated TA to one of the TRPs (e.g., only that one) associated with one of the CORSETPoolIndex. In an example, the WTRU may receive a single RAR message that includes one or more (e.g., two) TA values. In an example, the WTRU may apply the indicated TA value to the corresponding TRP. In an example, the WTRU may transmit one or more RAR messages. One or more (e.g., each) RAR messages may correspond to one or more PRACH transmissions. One or more (e.g., each) RAR messages may include one or more TAs. The WTRU may receive one or more (e.g., multiple) TA commands in one or more RAR messages. In an example, according to rules and / or received indications, the WTRU may select and / or apply one or more of the indicated TA values for one or more (e.g., all) future transmissions to one or more (e.g., both) TRPs until the next TA indication. In an example, according to rules or received indications, the WTRU may select and / or apply one of the indicated TA values for future transmissions (e.g., all future transmissions) to both TRPs until the next TA indication.In an example, the WTRU may apply one or more of the indicated TA values to one or more corresponding TRPs.

[0088] In an example, in NR, the PDCCH order PRACH may be carried by DCI format 1_0 and / or scrambled by a C-RNTI. In an example, if the field corresponding to "frequency domain resource allocation" is 1, the one or more remaining fields may be interpreted as follows. For example, the random access preamble index may be 6 bits. For example, the reserved bits may be 10 to 12 bits. In an example, if the value of the "random access preamble index" is not zero (e.g., all), the UL / SUL indicator may be 1 bit, the SS / PBCH index may be 6 bits, and / or the PRACH mask index may be 4 bits.

[0089] One or more of the following examples of instructions may be used to support the implementation of the examples and / or embodiments described herein. In one embodiment, one or more of the following embodiments of instructions may support the implementation of the examples and embodiments described above. One may include an RS used as a source for an indication of spatial information (e.g., a spatial filter based on an RS indicator) included for the transmission of a preamble associated with a second TRP. Additionally or alternatively, by way of example, an additional preamble that may be associated with a second TRP may be mentioned. Additionally or alternatively, by way of example, an additional SS / PBCH index may be mentioned. Additionally or alternatively, by way of example, an additional PRACH mask index may be mentioned.

[0090] In an example, the remaining reserved bits can be 10. The instructions of one or more examples described herein may be associated with overhead. The overhead can be reduced, for example, using one or more of the following examples. By way of example, a WTRU that can use the SSB associated with the shown SS / PBCH index as an RS source for spatial information (e.g., a spatial filter based on an RS indicator) included for transmission of a second preamble can be mentioned. Additionally or alternatively, by way of example, a WTRU that can use the same (e.g., the same) preamble for PRACH transmission to the first and second TRPs can be mentioned. Additionally or alternatively, by way of example, a WTRU that can use the same SS / PBCH and / or PRACH mask index for transmission of one or more (e.g., both) preambles if supported by the capabilities reported by the WTRU can be mentioned. Additionally or alternatively, by way of example, a WTRU that can use the same SS / PBCH index but different PRACH masks for one or more transmissions of the first and / or second PRACH can be mentioned. Additionally or alternatively, by way of example, a WTRU that can use the same PRACH mask but different SS / PBCH indices for one or more transmissions of the first and / or second PRACH can be mentioned.

[0091] Systems, methods, and apparatuses for subsequent RACH transmissions for a second TA loop are provided herein. In an example, a WTRU can determine (e.g., and / or use) an uplink TA value for transmission of an uplink signal based on a single TA support (e.g., a single TA loop maintained by an accumulated TA control mechanism). For example, the single TA support can be applied based on a first PRACH transmitted by the WTRU. For example, the single TA support can be applied based on a first PRACH transmitted by the WTRU during an initial access procedure. For example, the single TA support can be applied based on a first PRACH transmitted by the WTRU after receiving a PDCCH command based on a single TA (e.g., and / or TAG) support and / or for communication with a first TRP (e.g., a primary TRP, one single TRP, a cell, etc.).

[0092] In an example, the WTRU may be signaled (e.g., from the gNB) to transmit a second PRACH (e.g., via a PDCCH order, such as an indication to start a second TA loop via a "second TA start" PDCCH order). In that case, the second PRACH transmission may be for starting (e.g., creating, updating, adding, newly starting, maintaining, etc.) a second TA loop in addition to the first TA loop (e.g., an ongoing single TA loop). In an example, the WTRU may determine that the PRACH (e.g., based on a PDCCH order) is for a general (e.g., existing) PRACH transmission based on a single TA support (e.g., up to that point) and / or for a special (e.g., PDCCH-ordered) PRACH for starting (e.g., and / or updating) a second TA loop. For example, the WTRU target determination may be based on an explicit indicator associated with (e.g., included in) DCI indicating a special (e.g., PDCCH-ordered) PRACH for starting and / or updating a second TA loop. For example, the WTRU target determination may be based on an implicit indication including one or more configuration parameters (e.g., preamble index, SSB index, SS / PBCH index, PRACH mask, one or more PRACH resources, etc.) associated with the special (e.g., PDCCH-ordered) PRACH.

[0093] In response to receiving a special (e.g., PDCCH - commanded) PRACH to initiate (e.g., and / or update) a second TA loop, the WTRU may transmit a special PRACH towards a second TRP. For example, transmitting a special PRACH towards a second TRP may be based on one or more of the following. Transmitting a special PRACH towards a second TRP may be based on beam / TCI - related parameters that may be associated with the special PRACH. Transmitting a special PRACH towards a second TRP may be based on a unified TCI (e.g., its source RS) associated with the second TRP. Transmitting a special PRACH towards a second TRP may be based on a source quasi - co - location (e.g., QCL) RS associated with the special PRACH. Transmitting a special PRACH towards a second TRP may be based on additional and / or separate timing references (e.g., RS indicators, point - based spatial filters) obtained and / or measured from DL RS (e.g., TRS associated with the second TRP, SSB associated with the second TRP, DL RS associated with the second TRP, etc.) associated with the special PRACH.

[0094] In response to transmitting a special PRACH, the WTRU may receive a RAR. In an example, the RAR may include an indication of a second TA value (e.g., applied for a second TA loop). In an example, the RAR may be a second RAR transmitted from the second TRP. In an example, the RAR may be a first RAR transmitted from a first TRP (e.g., a primary TRP) based on a pre - configuration being delivered to the WTRU. In an example, the beam / TCI for the first RAR transmitted from the first TRP may be pre - configured in the WTRU.

[0095] In response to receiving an RAR, the WTRU may create (e.g., be configured to create) a second TA loop for accumulation (e.g., if configured), in which case the second TA loop may include a second TA value as an initial value for the second TA loop. In response to receiving an RAR, the WTRU may apply the second TA value for one or more subsequent uplink transmissions towards the second TRP (e.g., associated with the second TRP) until the next RAR associated with the second TRP is received, e.g., if the cumulative TA mode is not configured.

[0096] In an example, the WTRU may maintain a first TA loop based on a first timing reference point that may be obtained and / or measured from a first DL RS (e.g., that may be associated with a first TRP), and / or one or more first TA values that may be accumulated based on receiving one or more TA commands that may be associated with the first TA loop. In an example, the WTRU may maintain a second TA loop based on a second timing reference point that may be obtained and / or measured from a second DL RS (e.g., that may be associated with a second TRP), and / or one or more second TA values that may be accumulated based on receiving one or more TA commands that may be associated with the second TA loop. The increased reliability and / or flexibility in managing one or more (e.g., two) separate TA values and / or loops may each result in a directed response towards the first TRP and / or the second TRP. The increased reliability and / or flexibility may be based on creating a separate second TA loop in response to receiving DCI including a special (e.g., PDCCH commanded) PRACH.

[0097] In an example, the WTRU may apply one or more second TA values (e.g., accumulated based on receiving one or more TA commands that may be associated with a second TA loop) based on a first timing reference point (e.g., obtained and / or measured from a first DL RS that may be associated with a first TRP). In an example, applying one or more second TA values based on the first timing reference point (e.g., to a second TA loop) may imply that the timing reference (e.g., point) may be shared for the first TRP and / or the second TRP. In an example, the TA accumulation loop may be separated between the first TRP and the second TRP. In an example, applying one or more second TA values based on the first timing reference point (e.g., to a second TA loop) may imply that the timing reference (e.g., point) may be shared for the first TRP and / or the second TRP, but the TA accumulation loop is separated between the first TRP and the second TRP.

[0098] In an example, the WTRU may maintain a first TA loop based on a first timing reference point (e.g., obtained and / or measured from a first DL RS associated with a first TRP) and / or one or more first TA values accumulated based on receiving one or more TA commands associated with a first TA loop. In an example, the WTRU may maintain a second TA loop based on the same first timing reference point (e.g., shared between a first TRP and a second TRP) and / or one or more second TA values that may be accumulated based on receiving one or more TA commands that may be associated with a second TA loop. The complexity of the WTRU implementation may be reduced when managing two separate TA values and / or loops, each going to a first TRP and / or a second TRP, which may be based on an obtained shared timing reference point that may be based on the DL RS.

[0099] In an example, the WTRU may apply successive RACH transmissions (e.g., may be configured to apply) after a first RACH transmission. In an example, the WTRU may have one or more RACH transmissions after a known and / or preconfigured time interval. The time interval between one or more (e.g., each) PRACH transmissions may be fixed, semi-statically and / or dynamically indicated, and / or configured. In an example, the time interval may be configured and / or indicated based on the reported WTRU capabilities. In an example, the WTRU may determine the time interval based on other system parameters and / or operating modes (e.g., cell index, TDD / FDD, BWP index, multiple TA loop configurations, multiple TRP-related configurations, etc.).

[0100] In an example, in successive RACH transmissions, the WTRU may use the same or different RACH resources. For example, the RACH resources for each transmission may be selected and / or indicated from the same pool and / or a TRP-based configured pool. In an example, when the WTRU receives a DCI including a PDCCH order RACH for starting RACH transmissions for one or more (e.g., all) TRP links from one of the TRPs, the WTRU may follow one or more of the following rules to determine the order of RACH transmissions for one or more (e.g., each) TRP. In an example, the WTRU may start successive RACH transmissions (e.g., always) using the TRP that sent the PDCCH order RACH. Additionally or alternatively, the WTRU may start successive RACH transmissions (e.g., always) using a fixed TRP link (e.g., a link associated with a primary TRP, a link associated with CORESETPoolIndex = 0, etc.). In an example, the WTRU may start successive RACH transmissions using the TRP that may have the closest RACH occasion.

[0101] In an example, when a WTRU receives DCI including a PDCCH order RACH from one of the TRPs, the WTRU may resolve a collision with a previously scheduled uplink transmission for another TRP link based on one or more of the following. In an example, the WTRU may ignore the received grant and / or drop the scheduled uplink transmission. Additionally or alternatively, instead of dropping the scheduled transmission, the WTRU may delay the RACH until the next RACH transmission occasion. Alternatively or additionally, if the scheduled uplink transmission targets a PUCCH and / or a PUSCH including HARQ feedback, the WTRU may ignore the PDCCH order RACH and / or proceed with the scheduled transmission.

[0102] Multi-TA operation may be performed within a TAG. By way of example, timing alignment expiration may be mentioned. In an example, the configuration and / or operation of a timing advance timer (TAT) may be performed per TRP. The WTRU may be configured with a timing advance timer (TAT) per TRP. The TAT may be configured independently per TRP link, for example, as part of a TRP-specific TAG configuration. The TAT configuration may include one or more of the following. The TAT configuration may include a TRP identifier (e.g., the TRP to which the TAT applies). The TAT configuration may include a TAG identifier. The TAT configuration may include a TAT duration (e.g., a duration in ms). The TAT configuration may include one or more WTRU actions to be performed upon expiration of the TAT. The TAT configuration may include one or more TRP links to which one or more expiration actions are to apply. The TAT configuration may include one or more serving cells to which one or more expiration actions are to apply.

[0103] Additionally or alternatively, the TAT configuration for a TRP may include a delta configuration from a reference TRP and / or TAG and / or TAT configuration (e.g., the TAT configuration for pTRP, and / or a common TAT configuration provided in system information). Additionally or alternatively, the delta TAT configuration may include one or more of a reference TRP and / or TAG and / or TAT configuration identifier, and / or a delta configuration from a reference TRP and / or TAT and / or TAG configuration. For example, the delta configuration from a reference TRP and / or TAT and / or TAG configuration may consist of one or more of an offset time, and / or an offset timer duration.

[0104] The timing alignment timer for each TRP may include one or more start and / or stop conditions. The WTRU may start and / or resume the TAT timer associated with a TRP link, for example, upon receipt of one or more of the following. The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of a timing advance command MAC CE. The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of an absolute timing advance command (e.g., in response to an MSGA(PRACH) transmission including a C-RNTI MAC CE). The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of a DCI. The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of a TAG configuration and / or reconfiguration. The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of a TAT configuration and / or reconfiguration. The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of system information (e.g., SIB1). The WTRU may start and / or resume the TAT timer associated with a TRP link upon receipt of an RRC message (e.g., RRCSetup).

[0105] The WTRU may stop the TAT timer associated with the TRP link, for example, under one or more conditions. The WTRU may stop the TAT timer associated with the TRP link, for example, when contention resolution is considered to have failed. The WTRU may stop the TAT timer associated with the TRP link, for example, after transmitting HARQ feedback for a MAC protocol data unit (PDU) that may include WTRU contention resolution identification information MAC CE, for example, when contention resolution is considered to have been successful for a system information (SI) request.

[0106] The WTRU may start, resume, and / or stop the TAT based on which TRP link and / or serving cell receives and / or transmits a message (e.g., a timing advance command MAC CE). For example, the WTRU may perform one or more TAT actions associated with the TRP in response to a message transmitted / received on the TRP link. For example, the WTRU may perform one or more TAT actions (e.g., only that action) associated with the TRP in response to one or more messages transmitted and / or received on the TRP link. For example, the WTRU may perform one or more TAT actions (e.g., only that action) associated with the TRP in response to one or more messages transmitted and / or received on the pTRP link. For example, the WTRU may perform one or more TAT actions (e.g., only that action) associated with the TRP in response to one or more messages transmitted and / or received on one or more TRP links associated with the same serving cell. For example, the WTRU may perform one or more TAT actions (e.g., only that action) associated with the TRP in response to one or more messages transmitted and / or received on one or more TRP links associated with the SpCell.

[0107] The timing alignment timer for each TRP may include one or more TAT expiration conditions. The WTRU may perform one or more actions when the TAT associated with the TRP expires. Additionally or alternatively, the WTRU may perform the TAT expiration action at a fixed offset before timer expiration and / or for a fixed time after TAT expiration. The WTRU may perform one or more expiration actions. The WTRU may perform an expiration action to initiate a RACH. The WTRU may perform an expiration action to flush one or more (e.g., all) HARQ buffers. The WTRU may perform an expiration action to notify the network. The WTRU may perform an expiration action to release one or more (e.g., all) configured PUCCHs. The WTRU may perform an expiration action to release one or more (e.g., all) configured SRSs. The WTRU may perform an expiration action to clear one or more configured downlink allocations. The WTRU may perform an expiration action to clear one or more configured uplink grants. The WTRU may perform an expiration action to clear one or more PUSCH resources for semi-persistent CSI reporting. The WTRU may perform an expiration action to maintain the current N TA until a subsequent value is updated by the network (e.g., via a TA command).

[0108] The WTRU may configure and / or perform different sets of one or more expiration actions according to one or more of the following conditions: which TRP link is associated with the expired TAT (e.g., whether the expired TAT is associated with a pTRP and / or an sTRP, whether the expired TAT is associated with which serving cell (e.g., whether the expired TAT is associated with a TRP belonging to a SpCell, a PsCell, and / or an SCell)), and / or the number of TRPs having the expired TAT (e.g., the WTRU may perform different sets of one or more actions when one or more (multiple) TRPs have an expired TAT).

[0109] For a TRP link associated with an expired TAT timer (e.g., only for), one or more expiration actions may be configured for and / or performed by the WTRU. Additionally or alternatively, for one or more additional links (e.g., different by configuration) of the WTRU, one or more expiration actions may be configured for and / or performed by the WTRU. For example, the WTRU may perform one or more of the expiration actions as described herein for a TRP link associated with an expired timer. For example, the WTRU may perform one or more of the expiration actions as described herein for one or more (e.g., all) TRP links associated with a serving cell. For example, the WTRU may perform one or more of the expiration actions as described herein for one or more TRP links associated with one or more (e.g., all) serving cells.

[0110] In an example, upon expiration of TAT for one TRP, the WTRU may interrupt UL transmission to the affected TRP and / or may maintain one or more HARQ buffers. The WTRU may transmit data (e.g., pending) on the interrupted TRP to an active TRP. In an example, the WTRU transmission of data (e.g., pending) on the interrupted TRP may vary depending on data priority, one or more available resources, and / or configuration.

[0111] The WTRU may be configured with respect to notification of TAT expiration. Upon expiration of the TAT for one or more TRP links, the WTRU may notify the network of the TAT expiration via one or more of the following methods. The WTRU may notify the network of the TAT expiration by initiating a RACH transmission on the affected TRP link. For example, the WTRU may receive a single PDCCH order RACH to initiate a RACH transmission to obtain an updated TA on the affected link. For example, additionally or alternatively, the single received PDCCH order RACH may initiate a RACH transmission on one or more (e.g., all) TRP links. For example, the WTRU may receive separate PDCCH order RACHs for one or more (e.g., each) TRP link, in which case the first PDCCH may be associated with the TRP link associated with the timer being affected. Additionally or alternatively, the WTRU may notify the network of the TAT expiration by sending an implicit and / or explicit notification to the gNB through the link whose link timer has not expired. For example, the notification may indicate to the gNB the expiration of the timer of other links so that the gNB can send a PDCCH order RACH for the affected link. For example, if one or more (e.g., each) TAGs are associated with different subsets of RACH resources, the WTRU may perform an implicit indication by using one or more PRACH resources of the affected TAG for the TRP associated with the TAG that still has valid TA information.

[0112] The WTRU may be configured with respect to exceeding a maximum receive time difference and / or a maximum transmit time difference. The deployment of a multi-TRP configuration that can be supported beyond a cyclic prefix (CP) receive time difference may pose challenges to the WTRU architecture. If the receive time difference exceeds a certain level, for example, one or more (e.g., two) baseband units may be included. Including one or more additional baseband units may result in a more expensive device. The receive time difference limit may be beneficial for maintaining one or more goals of this feature from the perspective of data transmission throughput and / or robustness (e.g., due to the non-collocated nature of the TRPs and / or one or more propagation characteristics in one or more different frequency ranges).

[0113] The maximum receive time difference (MRTD) and / or the maximum transmit time difference (MTTD) may represent one or more thresholds expressed in units of time, symbols, and / or one or more portions of symbols that may be specific to the WTRU hardware architecture. For example, a WTRU that may have this capability may be designed with a single baseband unit. For example, communication with one or more (e.g., both) TRPs in the downlink and / or uplink may be processed simultaneously while the MRTD and / or MTTD is below a certain time threshold. In an example, one or more (e.g., two) baseband units may be included for this feature.

[0114] In a multi-TRP deployment, one or more TRPs may not have the same distance from the WTRU. In an example, one or more TA values indicated in one or more timing advance commands for one or more (e.g., each) TRP may result in a relative time difference that may exceed the WTRU's maximum transmit time difference (MTTD) capability.

[0115] The WTRU may be configured with respect to multi-TRP. The multi-TRP may include one or more additional TRP candidate measurement setups and / or reports. One or more additional TRPs may be added to the primary TRP by the network before and / or after (e.g., only after) one or more measurements are reported by the WTRU. Procedurally, the network may configure the WTRU to measure one or more additional TRP candidates within the area served by the primary TRP. The WTRU may report one or more of its capabilities for multi-TRP deployment, e.g., at registration and / or upon network request. The WTRU may report its supported MRTD and / or MTTD as thresholds. The network may configure the WTRU for one or more additional TRP candidate measurements and / or reports, e.g., taking into account the WTRU multi-TRP operation timing capabilities. In an example, the WTRU may measure one or more additional candidates and / or their relative reception time differences with respect to the primary TRP (pTRP), and / or report, e.g., one or more candidates having an RSRP and / or RSRQ level exceeding a reporting quality threshold, and / or a relative time difference less than the capabilities reported by the WTRU with respect to MRTD. Additionally or alternatively, the WTRU may be configured to report one or more additional TRP candidate RSRP and / or RSRQ, and / or their relative reception time differences with respect to the primary TRP (pTRP), e.g., without limitations regarding the supported MRTD capabilities (e.g., without any limitations).

[0116] When receiving a measurement report that may have one or more additional TRP candidates within one or more reporting conditions, for example, the network may configure the WTRU with an additional TRP (e.g., sTRP). For example, upon receiving a reconfiguration message that may have an sTRP addition, the WTRU may measure (e.g., re-measure) the relative reception time difference. For example, at the most recent measurement of the sTRP relative reception time difference, the WTRU may acknowledge the reconfiguration message to the network when the reception time difference is within its reported capabilities and / or, for example, may report a reconfiguration failure if the last measured relative reception time difference exceeds the supported MRTD. In an example, there may be a reconfiguration failure reason field that may indicate "MRTD exceeded". The reconfiguration failure may be transmitted as a beam failure, for example, along with the reasons shown herein. If the last measured relative reception time difference of the configured candidate has one or more WTRU capabilities, for example, the WTRU may initiate an uplink time synchronization procedure using the configured sTRP.

[0117] Additionally or alternatively, the WTRU may be composed of one or more additional sTRPs that comply with (e.g., may be compliant with) the MRTD and / or RSRP and / or RSRQ thresholds. The WTRU may be configured with one or more TCI states for one or more (e.g., each) combinations of pTRP-sTRP, and / or may activate one or more TCI combinations (e.g., selected and / or best TCI combinations) based on, for example, one or more latest measurements reported by the WTRU. When activating a TCI combination, for example, the WTRU may initiate one or more UL synchronization procedures using the most recently (e.g., newly) activated sTRP (e.g., based on a determined spatial filter and / or at a timing based on a TA indication). If UL synchronization leads to an exceedance of the MTTD supported by the WTRU, for example, a beam failure report with a cause of "exceeding MTTD" may be sent to the network. For example, upon receiving a failure message with a cause of "exceeding MTTD", the network may activate a different combination of TCI states and / or may reconfigure the WTRU (e.g., completely) using one or more other combinations of TCI states with one or more other sTRP candidates and / or pTRPs. Additionally or alternatively, the network may remove multi-TRP related operations from the WTRU configuration.

[0118] The WTRU may be configured with respect to one or more timing advance operations for multi-TRP in relation to MRTD and / or MTTD. The WTRU, which may be mobile in the environment, may receive, for example, one or more (e.g., both) timing advance commands for one or more (e.g., both) TRPs after adding an sTRP and / or after successfully synchronizing with the sTRP. TRP deployment and / or WTRU mobility may lead to one or more situations where MRTD and / or MTTD may be exceeded. Exceeding MRTD and / or MTTD may lead to a radio link failure of the active sTRP. In an example, the WTRU may report the problem.

[0119] In an example, if the relative difference between TA advance values exceeds the MRTD and / or MTTD threshold, the WTRU may perform one or more of the following. In an example, if the relative difference between TA advance values exceeds the MRTD or MTTD threshold, the WTRU may send an indication of an error and / or problem to the gNB. This indication may be sent via the pTRP. The pTRP may remain an anchor via an RRC message, MAC CE, and / or UCI on the physical layer. Additionally or alternatively, this indication may be a Radio Link Failure (RLF) indication for the sTRP.

[0120] Upon receiving a notification from the WTRU, the network may perform one or more of the actions herein and / or any (e.g., arbitrary) combination of the actions herein. For example, upon receiving a notification from the WTRU, the network may reconfigure the WTRU in one or more other TCI states having one or more other combined pTRP-sTRP candidates, which may be based on one or more most recent measurement reports received from the WTRU, and / or TCI activation for different combinations may follow, and / or operation in multi-DCI mode may continue. For example, upon receiving a notification from the WTRU, if there are no other combinations having a configured TCI pool with a multi-TRP combination, the WTRU may fallback to single-DCI mode and / or continue mTRP operation in TDM mode. For example, upon receiving a notification from the WTRU, the WTRU may declare a beam failure on the sTRP while indicating the strongest (e.g., best) TCI combination from the configured TCI pool based on one or more of the (e.g., last) measurement values. The indication of the (e.g., best) target TCI combination may be based on the (e.g., minimum) measured MRTD. Following the beam failure indication, for example, the WTRU may continue to monitor the CORESET associated with the sTRP (e.g., within CORESETPOOLIndex1) for beam indications within the DCI from one or more active TCIs.

[0121] The WTRU may be configured with respect to the application timing of one or more TA commands. In multi-TRP transmission, the WTRU (e.g., having simultaneous uplink transmission capabilities) may receive TA commands for one or more of the TRP links. Overlap between UL TRP transmissions for a TRP may occur, for example, when the TA is applied for one or more consecutive slots. One or more TA commands may be applied at the start of a slot (e.g., always applied), and / or one or more rules may be applicable to one or more symbols of a slot (e.g., the last symbol and / or the first symbol of the slot), which may be applied in a closed range (e.g., several symbols) of the slot boundary.

[0122] One or more may occur as described herein, depending on the relative timeline of the second transmission associated with the ongoing transmission of the first transmission and / or the updated TA. When the updated TA may perform the associated UL transmission after the ongoing first transmission, the ongoing transmission may proceed as scheduled. Additionally or alternatively, the transmission associated with the link having the updated TA may be shortened towards the end by the number of overlapping samples, e.g., when one or more overlapping UL transmissions between TRPs are not permitted. When the updated TA slot performs the associated transmission earlier than the ongoing first transmission, e.g., the ongoing transmission may proceed as scheduled. Additionally or alternatively, the transmission associated with the link having the updated TA may be shortened at the start by the number of overlapping samples, e.g., when one or more overlapping UL transmissions between TRPs are not permitted. In an example, the shortening for transmission alignment may be made by considering the priority rules. In an example, the shortened alignment of one or more transmissions may be made by considering the priority rules. If the PUCCH overlaps with the PUSCH and / or the TA application may imply shortening the PUCCH (e.g., using the normal overlapping shortening rules by which the ongoing transmission may be protected), e.g., the WTRU may shorten the PUSCH slot (e.g., instead of the PUCCH). In an example, a PUSCH having CSI and / or (e.g., any) UCI may be protected via the (e.g., normal) PUSCH, and thus, e.g., the (e.g., normal) PUSCH may be shortened.

[0123] The WTRU may be configured with respect to one or more (e.g., multiple) procedures for the indication and / or association of one or more TAs to one or more TRPs. In an example, a (e.g., specific) flag within the MAC CE may indicate whether the indicated TA may be targeted for the first and / or second TRP link. For example, this flag may be indicated in one or more of (e.g., two) fields reserved for the TAG ID. In an example, the CORESETPoolIndex bit may be added to the MAC CE to indicate, for example, the targeted TRP link. Additionally or alternatively, the CORESETPoolIndex may be associated with one or more of the TAG IDs to provide, for example, a linkage. In an example, the WTRU may determine the TRP targeted by the TA indication, for example, based on the scheduling PDCCH. For example, if the PDCCH scheduling the PDSCH including the MAC CE TA command comes in with CORESETPoolIndex = 0, the indicated TA may be applied to the TRP link associated with CORESETPoolIndex = 0. In an example, the indicated TA may be applied to the TRP link associated with the CORESET (e.g., CORESETPoolIndex = 1). For example, if the PDCCH scheduling the PDSCH including the MAC CE TA command comes in with CORESETPoolIndex = 0, the indicated TA may be applied to the TRP link associated with CORESETPoolIndex = 0, otherwise it may be applied to the TRP link associated with the CORESET, e.g., CORESETPoolIndex = 1. In an example, the MAC CE may include TA information for one or more TRP links. In an example, the WTRU may update (e.g., simultaneously) the TA information for one or more TRP links. In an example, the WTRU may update (e.g., simultaneously) the TA information for one or more (e.g., multiple) TRP links. The association to the first and / or second TRP link may be based on the order of the values indicated in the MAC CE and / or CORESETPoolIndex, etc. For example, the indicated TA information may be in the form of the absolute TA value of one or more (e.g., each) TRP and / or their relative differences.The WTRU may receive a TA value (e.g., TA1) for a first TRP link and / or a relative difference (e.g., TA_delta) of a second TRP link to determine a TA for the second link (e.g., TA2 = TA1 + TA_delta). For example, if the WTRU may receive one or more TA indications for one or more TRPs, the WTRU may apply one or more rules to determine the priority of an application for one or more (e.g., each) TRPs as described herein. The WTRU may apply a TA for one or more (e.g., each) TRP link according to the timing of the scheduled transmission. For example, if the WTRU receives one or more TA indications for two or more TRPs, the WTRU may apply the TA for the TRP link having the earlier scheduled transmission (e.g., first). In an example, if the WTRU receives one or more TA indications for two or more TRPs, the WTRU may apply the TA for the TRP link associated with the primary TRP and / or associated with CORESETPoolIndex = 0 (e.g., first).

[0124] The WTRU may be configured with one or more (e.g., multiple) TAGs per serving cell. One or more timing advance groups (TAGs) may be provided to the WTRU per serving cell. One or more (e.g., each) TAG configuration may be associated with one or more different (e.g., a different) TRP links. The WTRU may apply the TAG configuration associated with the secondary and / or additional sTRP (e.g., only that) if the WTRU supports multi-TRP and / or multi-TA operation, for example.

[0125] The TAG configuration for a TRP may include one or more of the parameters of TAG ID, TRP identifier (e.g., which TRP the TAG configuration applies to, etc.), whether the TAG applies to pTRP and / or sTRP, and / or timeAlignmentTimer (TAT) value and / or TimeAlignmentTimerCommon value, as described herein. The WTRU may receive one or more additional TRPs (e.g., sTRP) via TAG configuration information regarding the primary TRP (pTRP), and / or system information (e.g., within SIB1 and / or UplinkConfigCommonSIB), and / or via dedicated signaling (e.g., via RRC signaling, DCI, and / or MAC CE). For example, one or more TimeAlignmentTimerCommon parameters associated with one or more TRPs may be provided to the WTRU within system information (e.g., within SIB1 via UplinkConfigCommonSIB). One or more (e.g., multiple) TAG configurations may be provided to the WTRU (e.g., via RRC) within MAC-CellGroupConfig, for example, via TAG-Config, in which case the TAG information may be provided to one or more (e.g., each) TRPs. For example, TAG-Config may include tag-ID and / or timeAlignmentTimer configuration for the primary TRP (pTRP) and / or one or more additional TRPs (sTRP). For example, one or more (e.g., multiple) TAG-Config information elements may exist within MAC-CellGroupConfig, in which case one or more of them (e.g., each of them) may correspond to the TRP of the cell.

[0126] The WTRU may override the TAG configuration for one or more TRPs provided via broadcast signaling (e.g., within SIB1 via UplinkConfigCommonSIB), for example, when the WTRU receives a dedicated TAG configuration (e.g., via RRC signaling and / or MAC CE).

[0127] For a WTRU, a TAG configuration for a set X of TRPs may be provided, for example, via broadcast signaling (e.g., within system information), and / or a TAG configuration for a set Y of TRPs may be provided, for example, via dedicated signaling (e.g., RRC configuration and / or MAC CE). For example, if set X and set Y include the same TRP, the WTRU may overwrite one or more (e.g., or all) of the TAG configurations (and / or one or more associated parameters) provided in set X (e.g., via broadcast signaling) with those provided in set Y. For example, if set X and set Y include one or more different TRPs and set Y includes a TAG configuration for a pTRP, the WTRU may apply this TAG configuration to one or more (e.g., all) of the TRPs within set X that are not included in set Y. For example, if set X and set Y include one or more different TRPs, the WTRU may update the TAG configuration for the TRPs provided in both set X and set Y (e.g., only those). For example, the configuration for one or more (e.g., or all) of the TRPs within set X that are not provided in set Y may be, for example, maintained or removed. One or more actions taken by the WTRU may be explicitly indicated, for example, via configuration and / or within system information.

[0128] If a WTRU and / or cell can support multi-TRP multi-TA operation and (for example, only) one TAG configuration, one or more of the following may be included. The WTRU may apply the TAG information to one or more (for example, or all) TRPs (for example, pTRP and / or one or more sTRPs) associated with the serving cell. The WTRU may (for example, explicitly) indicate whether the TAG configuration applies to the pTRP and / or one or more sTRPs. For example, this indication may be provided in MAC-CellGroupConfig, TAG-Config, SIB1, and / or one or more (for example, any, some) other broadcast (for example, system information), RRC, and / or MAC (for example, MAC CE) signaling. The WTRU may apply one or more previously stored TAG configurations (for example, via a flag) upon transition of the RRC state to, for example, RRC_INACTIVE and / or RRC_IDLE. This flag may be included, for example, in the (for example, TAG) configuration. For example, the default TAG configuration may include one or more parameters (for example, TAT value) included in the TAG configuration. The default TAG configuration may be provided, for example, via system information (for example, SIB1). In an example, this (for example, system) information may be provided via a dedicated configuration (for example, via RRC) upon transition of the RRC state (for example, upon reception of an RRC Setup and / or RRC Release with suspend config message).

[0129] FIG. 4 depicts a system diagram illustrating an exemplary timing alignment 400 for an sTRP. The WTRU 406 may be composed of a primary TRP (pTRP) 402, and / or a secondary TRP (sTRP) 404, and / or a set of one or more PRACH resources.

[0130] At 408, pTRP402 may send PDCCH commands for the PRACH to sTRP404 to WTRU406. The PDDCH commands may include a preamble identifier, a TRP indication associated with sTRP404 (e.g., a CORESETPOOL index, etc.), a first SSB index (e.g., associated with pTRP402), a second SSB index, a first PRACH mask, a second PRACH mask, a TRP index, and / or an RS indicator associated with sTRP404 (e.g., CSI-RS and / or tracking RS). WTRU406 may use the RS indicator to determine a spatial filter for transmission (Tx). If the timing alignment for pTRP402 and sTRP404 includes (e.g., only) one PDCCH command, the PDDCH command may include a second SSB index (e.g., associated with pTRP402) and / or a second PRACH mask.

[0131] At 410, WTRU406 may send a PRACH (e.g., a preamble) transmission to sTRP404. The preamble may be based on the preamble identifier (e.g., at 408) using the determined PRACH resource and / or a (e.g., determined) spatial filter. For example, WTRU406 may determine a spatial filter based on an RS indicator (e.g., the RS indicator shown at 408). WTRU406 may determine to send the preamble to sTRP404 at 410 based on the spatial filter. WTRU406 may use the determined spatial filter to send the PRACH to sTRP404. WTRU406 may determine a PRACH resource for transmission to sTRP404 based on an SSB index (e.g., associated with a pTRP), one or more PRACH resources, and / or a PRACH mask. If the timing alignment for pTRP402 and sTRP404 includes (e.g., only) one PDCCH command, WTRU406 may send the same preamble to pTRP402 based on the second SSB index and / or the second PRACH mask.

[0132] At 412, sTRP404 may send a (e.g., first) response message to WTRU406. The (e.g., first) response may be a RAR message. The RAR message may include a TRP index, a TA (e.g., TA indication), and / or an sTRP UL grant. WTRU406 may receive a first response to the preamble. The first response may include a first timing advance (TA) command for a second timing alignment for transmission to sTRP404 and / or an index indicating sTRP404. If the timing alignment for pTRP402 and sTRP404 includes (e.g., only) one PDCCH command, the RAR message may include a second TA.

[0133] At 414, WTRU406 may send UL Tx (e.g., Msg3) to sTRP404. WTRU406 may use a spatial filter and / or timing determined based on a (e.g., first) TA indication / command to send UL Tx to sTRP404 at 414.

Claims

1. A wireless transmit / receive unit (WTRU) comprising a processor, the processor being configured to: receive, from a first transmit / receive point (TRP), downlink control information (DCI) indicating that the WTRU transmits a physical random access channel (PRACH) transmission, the DCI including an indication of a preamble, an indication of a first PRACH mask, an indication associated with a first synchronization signal block (SSB), and an indication of a reference signal (RS); transmit the preamble to a second TRP in a first PRACH resource determined based on the first PRACH mask and the first SSB, the preamble being transmitted using a spatial filter determined based on the indicated RS, wherein the first TRP and the second TRP are associated with the same physical cell identification information (PCI).

2. The WTRU of claim 1, wherein the processor is further configured to determine to transmit the preamble to the second TRP based on the spatial filter.

3. The WTRU of claim 1, wherein the processor is further configured to maintain a first timing alignment for transmission to the first TRP and maintain a second timing alignment for transmission to the second TRP.

4. The WTRU of claim 3, wherein the processor is further configured to receive, from the second TRP, a first response to the preamble, the first response including a first timing advance (TA) command for the second timing alignment for transmission to the second TRP and an index indicating the second TRP.

5. The WTRU of claim 4, wherein the first response is a random access response (RAR).

6. The WTRU of claim 4, wherein the processor is further configured to transmit an uplink (UL) transmission to the second TRP at a timing based on the first TA command using the spatial filter.

7. ​ ​ ​ ​ The WTRU according to claim 1, further configured such that the processor determines the spatial filter to be used to transmit the preamble to the second TRP using the indicated RS.

8. The WTRU according to claim 1, wherein the DCI is received in a PDCCH order that triggers the PRACH transmission.

9. The DCI includes an indication of a second PRACH mask and an indication associated with a second SSB, and the processor transmits the preamble to the first TRP using a second PRACH resource determined based on the second PRACH mask and the second SSB, and further configured to receive, from the first TRP, a second response to the preamble transmitted using the second PRACH resource, the second response including a timing advance command for the first timing alignment for transmission to the first TRP, and the second response including an index of the first TRP, the WTRU according to claim 1.

10. The DCI includes a timing advance (TA) medium access control (MAC) control element, and the TA MAC control element indicates a TRP index indicating that the TA is associated with the first TRP or the second TRP, the WTRU according to claim 1.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving, from a first transmit / receive point (TRP), downlink control information (DCI) indicating that the WTRU transmits a physical random access channel (PRACH) transmission, the DCI including an indication of a preamble, an indication of a first PRACH mask, an indication associated with a first synchronization signal block (SSB), and an indication of a reference signal (RS); transmitting the preamble to a second TRP in a first PRACH resource determined based on the first PRACH mask and the first SSB, wherein the preamble is transmitted using a spatial filter determined based on the indicated RS, and the first TRP and the second TRP are associated with the same physical cell identification information (PCI).

12. The method comprises The method according to claim 11, further comprising determining to transmit the preamble to the second TRP based on the spatial filter.

13. The method comprises maintaining a first timing alignment for transmission to the first TRP; and maintaining a second timing alignment for transmission to the second TRP. The method according to claim 11.

14. The method comprises further receiving, from the second TRP, a first response to the preamble, the first response including a first timing advance (TA) command for the second timing alignment for transmission to the second TRP and an index indicating the second TRP. The method according to claim 13.

15. The method according to claim 14, wherein the first response is a random access response (RAR).

16. The method according to claim 11, further comprising transmitting, using the spatial filter, an uplink (UL) transmission to the second TRP at a timing based on the first TA command.

17. The method according to claim 11, further comprising determining the spatial filter to be used to transmit the preamble to the second TRP using the indicated RS.

18. The method according to claim 11, wherein the DCI is received in a PDCCH command that triggers the PRACH transmission.

19. The DCI includes an indication of a second PRACH mask and an indication associated with a second SSB, and the method transmits the preamble to the first TRP using a second PRACH resource determined based on the second PRACH mask and the second SSB; and further receives, from the first TRP, a second response to the preamble transmitted using the second PRACH resource, the second response including a timing advance command for the first timing alignment for transmission to the first TRP and an index of the first TRP. The method according to claim 11.

20. The method according to claim 11, wherein the DCI includes a timing advance (TA) media access control (MAC) control element, and the TA MAC control element indicates a TRP index indicating that the TA is associated with the first TRP or the second TRP.

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