Multi-cell random access in energy-saving networks

Abstract

A system, method, and means relating to multi-cell random access using an on-demand synchronized signal block (SSB) is described herein. A wireless transceiver unit (WTRU) can receive a pre-sync signal. Based on the properties of the pre-sync signal, the WTRU can determine a first cell that transmits the pre-sync signal and a transmit beam index associated with the pre-sync signal. The WTRU can determine whether a condition is met. If the condition is met, the WTRU can receive a transmission from a second cell. Based on the transmission from the second cell and the pre-sync signal, the WTRU can determine a random access channel (RACH) configuration for the first cell. Based on the pre-sync signal and the RACH configuration for the first cell, the WTRU can determine an RO associated with the first cell and a preamble. The WTRU can transmit the preamble over the determined RO.

Description

[Background Art]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 531,089, filed on August 7, 2023, the contents of which are incorporated herein by reference.

[0002] Mobile communication using wireless communication continues to develop. The fifth generation is sometimes referred to as 5G. Previous (legacy) generations of mobile communication can be, for example, fourth generation (4G) Long Term Evolution (LTE). [Summary of the Invention] [Means for Solving the Problems]

[0003] Systems, methods, and means relating to system access in energy saving networks are described herein. A device such as a wireless transmit / receive unit (WTRU) may (e.g., be configured to) perform one or more of the following actions.

[0004] A WTRU may receive a pre-sync signal. The pre-sync signal may be at least one of or include a discovery signal, a synchronization signal block (SSB), a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or a combination of PSS and SSS. The SSB signal associated with the pre-sync signal may not be a full SSB signal.

[0005] Based on the properties of the presync signal, the WTRU can determine the cell transmitting the presync signal (e.g., the first cell) and / or the transmit beam index associated with the presync signal (e.g., beam index and / or transmit beam). The properties associated with the presync signal include at least one of the following: time, frequency, sequence selection, phase, and sequence identification (ID).

[0006] WTRU can determine whether a condition is met. The condition can be met based on at least one of the following: the received power associated with the presync signal is greater than a threshold; no SSB is received from the first cell; or the first cell is in an energy-saving state.

[0007] Based on the determination that the conditions are met, the WTRU may receive transmissions from the second cell. Transmissions from the second cell may be at least one of the following: an SSB or a System Information Block (SIB), or may include both.

[0008] A transmission can be associated with at least one SSB from a second cell. For example, a WTRU can receive at least one SSB by deciding (for example, further deciding) to receive at least one SSB from (for example, via) a second cell, based on at least one of the following parameters: the same frequency at which a presync signal is detected (for example, received), a different frequency at which a presync signal is detected (for example, received), an indication associated with a presync signal, or at least one of the following parameters: time resources for receiving (for example, detecting) at least one SSB, frequency resources for receiving (for example, detecting) at least one SSB, a carrier frequency associated with at least one SSB, or a cell ID associated with at least one SSB.

[0009] The WTRU can determine the Random Access Channel (RACH) configuration for the first cell based on the transmit and presync signals from the second cell. The RACH configuration may be, or include, the association of the presync signal to at least one physical RACH occasion (RO) associated with the first cell. The presync signal may be associated with the first cell. The RACH configuration may be, or include, at least one of the following: the system timing associated with the first cell, and the first cell ID, the association of the transmit beam (Tx beam) to a physical RO associated with the first cell, or a partition of the RACH preamble with the RO or TX beam associated with accessing the first cell.

[0010] The WTRU can determine the RO associated with the first cell and the preamble based on the presync signal and / or the RACH configuration for the first cell.

[0011] The WTRU can transmit a preamble on the RO associated with the first cell.

[0012] A WTRU can monitor Random Access Responses (RARs) from a first cell. For example, a WTRU can monitor RARs from a first cell during the RAR window. The WTRU determines whether an RAR has been received. Based on the determination that an RAR has been received, the WTRU can determine a resource to send a message to. The WTRU can then send the message on that resource.

[0013] In the example, based on the determination that no RAR was received on the first cell, the WTRU may determine that at least one SSB was received from the first cell. Based on the determination that at least one SSB was received from the first cell, the WTRU may transmit a preamble (e.g., a second preamble) on the RO associated with the first cell. The RO used for transmitting the second preamble may be based on the measured SSB associated with the first cell (e.g., further).

[0014] In the example, based on the determination that the RAR was not received on the first cell, the WTRU can determine whether the number of preamble retransmissions exceeds a threshold. If the number of preamble retransmissions exceeds the threshold, the WTRU can transmit the preamble on the second cell.

[0015] In the example, the WTRU can determine whether a fallback indication was received in the RAR on the first cell. If a fallback indication was received in the RAR, the WTRU can perform the RACH procedure on the second cell.

[0016] In the example, the WTRU can determine the Reference Signal Received Power (RSRP) associated with the second cell. For example, the WTRU can determine that the RSRP associated with the second cell is below a threshold (e.g., a second threshold). If the RSRP is below the threshold (e.g., a second threshold), the WTRU can perform a RACH transmission on the first cell.

[0017] In this example, the WTRU can detect (e.g., receive) a presync signal from a network energy saving (NES) cell and an SSB / SIB (e.g., SIB-1) from a second cell. Based on the detection (e.g., and / or reception), the WTRU can determine the RACH configuration of the first cell from the SSB / SIB (e.g., SIB-1) on the second cell. The WTRU can perform random access by performing a first preamble transmission to the first cell, receiving an SSB (e.g., on demand) from the first cell, and retransmitting a physical random access channel (PRACH) preamble based on the received SSB from the first cell.

[0018] The WTRU may, for example, perform monitoring of presync signals (one or more) of a configured NES cell when it receives a beam fault instance for the current beam. For example, if the detected presync signal is better than a first threshold and the current beam RSRP is below a second threshold, the WTRU may report the detected presync signal and ID to the cell to which it is connected. The WTRU may perform (for example, be configured to perform) RACH on a suitable NES-detected cell (for example, one of them).

[0019] Systems, methods, and means relating to multi-cell random access using on-demand SSB are described herein. A device may perform (for example, be configured to perform) one or more of the following actions: A WTRU may detect (e.g., receive) a presync from a first cell (e.g., the first cell of an NES) and an SSB from a second cell (e.g., a macrocell). The WTRU may, for example, determine the RACH configuration of the first cell from the SSB / SIB (e.g., SIB-1) on the second cell based on the detection. The WTRU may perform random access using both cells by, for example, performing a first preamble transmission with a quasi-colocation (QCL) assumption for the first cell. The WTRU may receive (e.g., on-demand) SSBs. The WTRU may, for example, retransmit a PRACH preamble based on the on-demand SSB. The WTRU may, for example, fall back to the second cell if no RAR is received.

[0020] The WTRU can detect (e.g., receive) a presync (e.g., discover) signal from a first (e.g., small) cell, such as a PSS plus SSS (e.g., with some modification). The WTRU can identify the first cell and the transmit beam (Tx beam) transmitting the presync signal through one or more of the physical properties of the signal (e.g., time, frequency, sequence selection, phase, sequence ID, etc.). The WTRU can receive and decode an SSB / SIB-1 from a second (e.g., macro) cell if, for example, at least one of the following is satisfied: the presync received power from the first cell is greater than a first threshold (e.g., pre-sync-ReceivedPower > threshold 1 from the first cell), no SSB is received from the first cell or it is determined that the first cell is in an NES state, and / or the RSRP from the second cell is less than a second threshold (e.g., threshold 2). The WTRU can determine a PRACH configuration for the first cell based, for example, on the received SIB-1 of the second cell and the detected presync sequence of the first cell, which may include, for example, the system timing and cell ID of the first cell, the association of the first cell Tx beam to the RACH occasion (RO) of the first cell, the partition of the RACH preamble associated with accessing the first cell, and / or, for example, the association of the first cell SSB to the first cell RO for preamble retransmission on the first cell. The WTRU can determine the RO / preamble to be used on the first cell based, for example, on the presync signal of the first cell and / or the (configured) association between the presync and RO received on the second cell. The WTRU can then perform a RACH procedure (for example, 2-step or 4-step) on the first cell using the determined parameters. WTRU can monitor random access (RA) responses on the first cell.The WTRU can, for example, monitor SSB reception from the first cell while the RAR window is active. The WTRU can, for example, send another preamble to the first cell if no RAR has been received on the first cell and the WTRU has received one or more SSBs from the first cell. The WTRU can, for example, determine which RO to use for preamble transmission on the first cell based on the (e.g., best) measured SSB on the first cell. The WTRU can, for example, send a preamble on the second cell after, for example, N attempts (e.g., N≧1) if no RAR has been received on the first cell. The WTRU can, for example, continue the RACH procedure on the second cell if the WTRU has received a fallback indication from the first cell (e.g., in a backoff indicator or a bit in the RAR payload) (e.g., by sending an MSG3 with the grant indicated in the RAR payload, or by retransmitting the preamble on the second cell).

[0021] An exemplary device may include a processor configured to perform one or more actions. For example, the device may detect (e.g., receive) a presync signal. The device may identify a first cell that transmits a presync signal based on at least one property associated with the presync signal. The device may receive an SSB or SIB from a second cell. The device may determine a RACH configuration for the first cell based on the SSB or SIB from the second cell and the presync signal. The device may perform a RACH procedure on the first cell using the RACH configuration. The device may receive an SSB from the first cell. The device may determine a second RACH configuration for the first cell based on the SSB from the first cell. The device may perform a second RACH procedure on the first cell using the second RACH configuration. The device may perform a third RACH procedure on the second cell if no random access response is received from the first cell, or if a fallback indication is received from the first cell. [Brief explanation of the drawing]

[0022] [Figure 1A] This is a system diagram showing an exemplary communication system in which one or more disclosed embodiments are implemented. [Figure 1B] This is a system diagram showing an exemplary wireless transceiver unit (WTRU) used in the communication system shown in Figure 1A, according to one embodiment. [Figure 1C] This is a system diagram showing an exemplary radio access network (RAN) and core network (CN) used in the communication system shown in Figure 1A, according to one embodiment. [Figure 1D] This is a system diagram showing further exemplary RAN and CN that can be used in the communication system of Figure 1A according to one embodiment. [Figure 2] This figure shows an example of the time-frequency structure of a synchronous signal block (SSB). [Figure 3] It is a diagram illustrating an example of SSB beam sweeping within an SSB burst set. [Figure 4] It shows an exemplary flowchart of a WTRU that performs multi-cell random access using an on-demand synchronization signal block (SSB). DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] FIG. 1A is a system diagram illustrating an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, and broadcast, 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 radio bandwidth. For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero-tail (ZT) unique-word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique-word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multicarrier (FBMC).

[0024] As shown in FIG. 1A, a communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. It will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, each of WTRUs 102a, 102b, 102c, 102d may be referred to as a "station" and / or "STA", may be configured to transmit and / or receive wireless signals, and may include (or be) user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, among others. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0025] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks, such as CN 106 / 115, the Internet 110, and / or network 112. As an example, base stations 114a and 114b may be any of the following: base station transceiver station (BTS), node B (NB), e-node B (eNB), home node B (HNB), home e-node B (HeNB), g-node B (gNB), NR node B (NR NB), site controller, access point (AP), wireless router, etc. Although base stations 114a and 114b are shown as single elements, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0026] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be called cells (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for radio services to a particular geographic area that may be relatively fixed or change over time. A cell may be further divided into cell sectors. For example, a 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 for each sector of the cell. In one embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology, which may utilize multiple transceivers for each sector of the cell or any sector. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

[0027] Base stations 114a and 114b can communicate with one or more WTRUs 102a, 102b, 102c, and 102d via an air interface 116, the air interface 116 may be any suitable radio communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0028] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, base stations 114a and WTRU 102a, 102b, and 102c in RAN 104 / 113 may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish an air interface 116 using broadband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Advanced HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0029] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c can implement radio technologies such as Advanced UMTS Terrestrial Radio Access (E-UTRA), which can establish an air interface 116 using Long-Term Evolution (LTE) and / or LTE Advanced (LTE-A) and / or LTE Advanced Pro (LTE-A Pro).

[0030] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c can implement radio technologies such as NR radio access, which can establish an air interface 116 using New Radio (NR).

[0031] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base stations 114a and WTRUs 102a, 102b, and 102c can implement LTE radio access and NR radio access together, for example, using the dual connectivity (DC) principle. Thus, the air interface utilized by WTRUs 102a, 102b, and 102c may be characterized by multiple types of radio access technologies and / or transmissions from / to multiple types of base stations (e.g., eNBs and gNBs).

[0032] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c can implement wireless technologies such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Advanced Data Rate (EDGE), and GSM EDGE (GERAN).

[0033] In Figure 1A, base station 114b may be, for example, a wireless router, home node B, home enode B, or access point, and can utilize any suitable RAT to facilitate wireless connectivity in localized areas such as offices, homes, vehicles, premises, industrial facilities, aerial corridors (for use by drones, for example), and roads. In one embodiment, base station 114b and WTRU 102c, 102d can implement wireless technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, base station 114b and WTRU 102c, 102d can implement wireless technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In one embodiment, base station 114b and WTRU 102c, 102d can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish any small cell, picocell, or femtocell. As shown in Figure 1A, base station 114b may have a direct connection to the internet 110. Therefore, base station 114b may not be required to access the internet 110 via CN 106 / 115.

[0034] RAN104 / 113 may communicate with CN106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU102a, 102b, 102c, and 102d. The data may have various Quality of Service (QoS) requirements, including different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, and mobility requirements. CN106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, internet connectivity, video distribution, and / or implement high-level security functions, such as user authentication. Although not shown in Figure 1A, it will be understood that RAN104 / 113 and / or CN106 / 115 may communicate directly or indirectly with other RANs employing the same or different RATs as RAN104 / 113. For example, in addition to being connected to RAN104 / 113, which may utilize NR radio technology, CN106 / 115 may also communicate with another RAN (not shown) employing one of the following technologies: GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0035] CN106 / 115 can also act as a gateway for WTRU102a, 102b, 102c, and 102d to access PSTN108, the Internet 110, and / or other networks 112. PSTN108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as TCP, User Datagram Protocol (UDP), and / or IP in the Transmission Control Protocol / Internet Protocol (TCP / IP) Internet Protocol Suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may employ the same RAT as RAN104 / 114 or a different RAT.

[0036] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 can include multimode capability (for example, WTRUs 102a, 102b, 102c, and 102d can include multiple transceivers for communicating with different radio networks via different radio links). For example, WTRU 102c shown in Figure 1A may be configured to communicate with base station 114a which can employ cellular-based radio technology and may be configured to communicate with base station 114b which can employ IEEE 802 radio technology.

[0037] Figure 1B is a system diagram showing an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 may include, in particular, a processor 118, a transceiver 120, a transceiver element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other elements / peripherals 138. It will be understood that the WTRU 102 may include any partial combination of the above elements while remaining consistent with one embodiment.

[0038] The processor 118 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transceiver element 122. Although Figure 1B shows 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, for example, in an electronic package or chip.

[0039] The transmitting / receiving element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmitting / receiving element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmitting / receiving element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In one embodiment, the transmitting / receiving element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transmitting / receiving element 122 may be configured to transmit and / or receive any combination of radio signals.

[0040] Although the transmit / receive element 122 is shown as a single element in Figure 1B, the WTRU 102 can include any number of transmit / receive elements 122. For example, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving radio signals via the air interface 116.

[0041] The transceiver 120 may be configured to modulate the signal to be transmitted by the transmitting / receiving element 122 and to demodulate the signal to be received by the transmitting / receiving element 122. As described above, the WTRU 102 may have multimode capability. Therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0042] The processor 118 of the WTRU102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (for example, a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and may receive user input data from them. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information from any type of suitable memory, such as non-removable memory 130 and / or removable memory 132, and store data therein. 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. Removable memory 132 may include a subscriber identification module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 can access information from memory not physically located on the WTRU 102, such as on a server or home computer (not shown), and store data therein.

[0043] The processor 118 may be configured to receive power from the power supply 134 and distribute and / or control power to other components in the WTRU 102. The power supply 134 can be any suitable device for supplying power to the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0044] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via the air interface 116 and / or determine its location based on the timing of when signals are received from two or more nearby base stations. It will be understood that the WTRU 102 may acquire location information via any preferred location determination method while remaining consistent with one embodiment.

[0045] The processor 118 may further be coupled to other elements / peripherals 138, which may include one or more software and / or hardware modules / units that provide additional features, functionality and / or wired or wireless connectivity. For example, the elements / peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a Universal Serial Bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency-modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The element / peripheral device 138 may include one or more sensors, the sensors being one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, compass sensor, proximity sensor, temperature sensor, time sensor, geolocation sensor, altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor, and / or humidity sensor.

[0046] WTRU102 may include a full-duplex radio where the transmission and reception of some or all of a signal may be parallel and / or simultaneous, associated with a specific subframe for both an uplink (for transmission, for example) and a downlink (for reception, for example). The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing either through hardware (e.g., chokes) or through a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, WTRU102 may include a half-duplex radio, which is for the transmission and reception of some or all of a signal (e.g., associated with a specific subframe for either an uplink (for transmission, for example) or a downlink (for reception, for example).

[0047] Figure 1C is a system diagram showing RAN104 and CN106 according to one embodiment. As described above, RAN104 can employ E-UTRA radio technology to communicate with WTRU102a, 102b, and 102c via the air interface 116. RAN104 may also communicate with CN106.

[0048] RAN104 may include enodes B160a, 160b, and 160c, but it will be understood that RAN104 may include any number of enodes B while remaining consistent with one embodiment. Each of enodes B160a, 160b, and 160c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, enodes B160a, 160b, and 160c can implement MIMO technology. Thus, enode B160a may, for example, use multiple antennas to transmit radio signals to and receive radio signals from WTRU102a.

[0049] Each of the e-nodes B160a, 160b, and 160c may be associated with a specific cell (not shown) and may be configured to handle wireless resource management decisions, handover decisions, user scheduling on uplink (UL) and / or downlink (DL), etc. As shown in Figure 1C, the e-nodes B160a, 160b, and 160c can communicate with each other via the X2 interface.

[0050] The CN106 shown in Figure 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (PGW) 166. Although each of the above elements is shown as part of CN106, it will be understood that any one of these elements may be owned and / or operated by an entity other than the CN operator.

[0051] The MME162 can be connected to each of the e-nodes B160a, 160b, and 160c in RAN104 via the S1 interface and can act as a control node. For example, the MME162 can be responsible for authenticating users of WTRU102a, 102b, and 102c, activating / deactivating bearers, and selecting a specific serving gateway during the initial attachment of WTRU102a, 102b, and 102c. The MME162 can provide control plane functionality for switching between RAN104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0052] The SGW164 can be connected to each of the e-nodes B160a, 160b, and 160c in RAN104 via the S1 interface. The SGW164 can generally route and forward user data packets to and from WTRU102a, 102b, and 102c. The SGW164 can perform other functions, such as anchoring the user plane during e-node B handovers, triggering paging when DL data is available for WTRU102a, 102b, and 102c, and managing and remembering the context of WTRU102a, 102b, and 102c.

[0053] SGW164 may be connected to PGW166, which can provide 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-enabled devices.

[0054] CN106 can facilitate communication with other networks. For example, CN106 can provide WTRU102a, 102b, and 102c with access to circuit-switched networks such as PSTN108, thereby facilitating communication between WTRU102a, 102b, and 102c and legacy landline communication devices. For example, CN106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN106 and PSTN108. Furthermore, CN106 can provide WTRU102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0055] Although the WTRU is described as a wireless terminal in Figures 1A to 1D, in certain representative embodiments, such a terminal is intended to be able to use a wired communication interface with a communication network (for example, temporarily or permanently).

[0056] In a typical embodiment, the other network 112 may be a WLAN.

[0057] In Infrastructure Basic Service Set (BSS) mode, a WLAN may have access points (APs) for the BSS and one or more stations (STAs) associated with the APs. APs may have access to or interfaces with distributed systems (DSs) or other types of wired / wireless networks that carry traffic during and / or from the BSS. Traffic originating outside the BSS to the STAs may arrive through the APs and be delivered to the STAs. Traffic originating from the STAs to destinations outside the BSS may be sent to the APs to be delivered to their respective destinations. Traffic between STAs within the BSS may be sent through the APs; for example, a source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS is considered and / or sometimes referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between a source STA and a destination STA (for example, directly between them) via a direct link setup (DLS). In some typical embodiments, the DLS may be an 802.11e DLS or an 802.11z tunnel DLS (TDLS). A WLAN using Independent BSS (IBSS) mode may not have access points (APs), and STAs within or using IBSS (for example, all STAs) can communicate directly with each other. The IBSS communication mode is sometimes referred to as the “ad-hoc” communication mode in this specification.

[0058] When using the 802.11ac infrastructure operating mode or a similar operating mode, an AP can transmit beacons on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., a 20 MHz bandwidth) or a dynamically set width via signaling. The primary channel can be the operating channel of the BSS, which can be used by STAs to establish a connection with the AP. In some typical embodiments, Carrier sense multiple access with collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. In CSMA / CA, an STA, including the AP (e.g., any STA), can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that STA can backoff. One STA (e.g., only one station) can transmit at any given time within a given BSS.

[0059] A high-throughput (HT) STA can use a 40MHz wide channel for communication, for example, via a combination of a primary 20MHz channel and adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

[0060] Ultra-high throughput (VHT) STAs can support 20MHz, 40MHz, 80MHz, and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining consecutive 20MHz channels. 160MHz channels can be formed by combining eight consecutive 20MHz channels, or by combining two discontinuous 80MHz channels, sometimes referred to as an 80+80 configuration. In the 80+80 configuration, data can be passed through a segment parser that, after channel encoding, can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing can be performed separately for each stream. The streams can be mapped onto two 80MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of a receiving STA, the operation described above for the 80+80 configuration can be reversed, and the combined data can be sent to a media access control (MAC) layer, entities, etc.

[0061] Sub-1GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV white space (TVWS) spectrum, while 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using the non-TVWS spectrum. According to a typical embodiment, 802.11ah can support meter-type control / machine-type communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have limited capabilities, including support for some and / or limited bandwidths (e.g., support only for that). MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0062] A WLAN system that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, includes a channel that can be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the minimum bandwidth operating mode from among all STAs operating in the BSS. In the 802.11ah example, the primary channel may be 1 MHz wide for an STA (e.g., an MTC type device) that supports (e.g., only) 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier detection and / or network allocation vector (NAV) settings may depend on the status of the primary channel. For example, if the primary channel is busy because an STA (which only supports 1MHz operating mode) is transmitting to the AP, the entire available frequency band may be considered busy, even though a large portion of the frequency band remains idle and could be available.

[0063] In the United States, the available frequency band that can be used by 802.11ah is from 902 MHz to 928 MHz. In South Korea, the available frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is from 6 MHz to 26 MHz, depending on the country code.

[0064] Figure 1D is a system diagram showing RAN113 and CN115 according to one embodiment. As described above, RAN113 can employ NR radio technology to communicate with WTRU102a, 102b, and 102c via the air interface 116. RAN113 may also communicate with CN115.

[0065] RAN113 may include gNB180a, 180b, and 180c, but it will be understood that RAN113 may include any number of gNBs while remaining consistent with one embodiment. Each of the gNB180a, 180b, and 180c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, the gNB180a, 180b, and 180c can implement MIMO technology. For example, the gNB180a and 180b can utilize beamforming to transmit signals to and / or receive signals from the WTRU102a, 102b, and 102c. Thus, the gNB180a can, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from the WTRU102a. In one embodiment, gNB180a, 180b, and 180c can implement carrier aggregation technology. For example, gNB180a can transmit multiple component carriers to WTRU102a (not shown). A subset of these component carriers may be on the unlicensed spectrum, while the remaining component carriers may be on the licensed spectrum. In one embodiment, gNB180a, 180b, and 180c can implement coordinated multi-point (CoMP) technology. For example, WTRU102a can receive coordinated transmissions from gNB180a and gNB180b (and / or gNB180c).

[0066] WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using transmissions associated with scalable numerology. For example, OFDM symbol intervals and / or OFDM subcarrier intervals may differ for different transmissions, different cells, and / or different parts of the radio transmission spectrum. WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (including, for example, a varying number of OFDM symbols and / or a varying length of absolute time that persists).

[0067] gNB180a, 180b, and 180c can be configured to communicate with WTRU102a, 102b, and 102c in standalone and / or non-standalone configurations. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c without accessing other RANs (such as e-nodes B160a, 160b, and 160c). In a standalone configuration, WTRU102a, 102b, and 102c can utilize one or more of gNB180a, 180b, and 180c as mobility anchor points. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using signals in unlicensed bands. In a non-standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c while also communicating with other RANs such as enodes B160a, 160b, and 160c. For example, WTRU102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNB180a, 180b, and 180c, and one or more enodes B160a, 160b, and 160c. In a non-standalone configuration, enodes B160a, 160b, and 160c can act as mobility anchors for WTRU102a, 102b, and 102c, and gNB180a, 180b, and 180c can provide additional coverage and / or throughput to service WTRU102a, 102b, and 102c.

[0068] Each of the gNB180a, 180b, and 180c may be associated with a specific cell (not shown) and may 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 (UPF) 184a and 184b, routing of control plane information to access and mobility management functions (AMF) 182a and 182b, etc. As shown in Figure 1D, the gNB180a, 180b, and 180c can communicate with each other via the Xn interface.

[0069] The CN115 shown in Figure 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the above elements is shown as part of the CN115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0070] AMF182a and 182b can be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N2 interface and can act as control nodes. For example, AMF182a and 182b can be responsible for user authentication of WTRU102a, 102b, and 102c, support for network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selection of specific SMF183a and 183b, management of registration areas, termination of NAS signaling, mobility management, etc. Network slicing can be used by AMF182a and 182b to customize CN support for WTRU102a, 102b, and 102c based on the type of service being utilized by WTRU102a, 102b, and 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-high reliability low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and services for MTC access. AMF182a, 182b can provide control plane functionality for switching between RAN113 and other RANs (not shown) employing other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as Wi-Fi.

[0071] 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. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0072] UPF184a and 184b may be connected via the N3 interface to one or more of gNB180a, 180b, and 180c in RAN113, which can provide 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-enabled devices. UPF184a and 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0073] CN115 can facilitate communication with other networks. For example, CN115 may include or be able to communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN115 and PSTN108. Furthermore, CN115 can provide WTRU102a,102b,102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU102a,102b,102c may be connected to DN185a,185b through UPF184a,184b via an N3 interface to UPF184a,184b, and an N6 interface between UPF184a,184b and local data networks (DN) 185a,185b.

[0074] In view of Figures 1A to 1D and their corresponding descriptions, one or more, or all, of the functions described herein with respect to any of the WTRU 102a to d, base stations 114a to b, e-nodes B160a to c, MME 162, SGW 164, PGW 166, gNB 180a to c, AMF 182a to b, UPF 184a to b, SMF 183a to b, DN 185a to b, and / or any other (one or more) elements / devices described herein may be implemented by one or more emulation elements / 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 to simulate network and / or WTRU functions.

[0075] Emulation devices may be designed to implement one or more tests of other devices in a laboratory environment and / or a carrier network environment. For example, one or more emulation devices may perform one or more, or all, of the functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in a communication network. One or more emulation devices may perform one or more, or all, of the functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. Emulation devices may be directly coupled to another device for testing purposes and / or tests may be performed using over-the-air wireless communication.

[0076] One or more emulation devices can perform one or more functions, including all of the above, while not implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device may be used in a test laboratory and / or in a test scenario in a non-deployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., including one or more antennas) may be used by an emulation device to transmit and / or receive data.

[0077] Systems, methods, and means relating to system access in energy conservation networks are described herein.

[0078] A wireless transceiver unit (WTRU) can detect (e.g., receive) pre-sync signals from a first cell (e.g., a network energy saving (NES) cell) and a synchronization signal block (SSB) / system information block (SIB) (e.g., SIB-1) from a second cell. The WTRU can, for example, determine the random access channel (RACH) configuration of the first cell from the SSB / SIB (e.g., SIB-1) on the second cell based on the detection and / or reception. The WTRU can perform random access by performing a first preamble transmission to the first cell, receiving an SSB from the first cell (e.g., on demand), and, for example, retransmitting a physical random access channel (PRACH) preamble based on the received SSB from the first cell.

[0079] A WTRU may perform monitoring of presync signals (one or more) of a configured NES cell, for example, when the WTRU receives a beam fault instance for the current beam. For example, if the detected / received presync signal is better than a first threshold and the current beam reference signal received power (RSRP) is below a second threshold, the WTRU may report the detected / received presync signal and ID to the cell to which the WTRU is connected. The WTRU may perform (for example, be configured to perform) RACH on a preferred NES detected cell.

[0080] A network (e.g., a 3GPP RAN) can minimize its power consumption from transmission and reception (e.g., by enabling the network to minimize its power consumption). Such minimization can be beneficial in reducing operating costs and environmental sustainability.

[0081] Network efficiency can be improved by, for example, minimizing transmissions from the network when there is no data. For instance, an always-on cell-specific reference signal (CRS) may not be used (for example, in NR). Further energy consumption reductions may be possible.

[0082] For example, a network may still consume energy when it is not transmitting, such as from other activities like baseband (e.g., digital) processing for receiving or beamforming. Such idle power consumption cannot be ignored in high-density networks, even when the WTRU is not being serviced for a given period. Energy consumption can be reduced, for example, if the network can turn off these activities when it is not transmitting to the WTRU.

[0083] Networks (e.g., NR, distinct from LTE) may not require the transmission of always-on sink or reference signals and / or can support adaptive bandwidth and multiple-input multiple-output (MIMO) capabilities. This adaptation of network resources can enable greater efficiency when operating newer deployments and / or later generations.

[0084] The following technical terms may be used in this specification: Channel status information (CSI) may include at least one of the following: Channel quality index (CQI), rank indicator (RI), precoding matrix index (PMI), L1 channel measurement (e.g., reference signal received power (RSRP), e.g., L1-RSRP, or signal-to-interference plus noise ratio (SINR)), channel status indicator reference signal (CSI-RS) resource indicator (CRI), synchronization signal (SS) / PBCH block resource indicator (SSBRI), layer indicator, and / or any other measurement measured by the WTRU from the configured CSI-RS or SS / PBCH block. The WTRU may report a subset of the channel status information (CSI) components. The CSI components may correspond to at least the CSI-RS resource indicator (CRI), SSB resource indicator (SSBRI), panel indications used for reception in WTRU (e.g., panel identification information or group identification information), L1-RSRP, L1-SINR taken from SSB or CSI-RS (e.g., cri-RSRP, cri-SINR, ssb-Index-RSRP, ssb-Index-SINR), and / or other channel status information such as at least the rank indicator (RI), channel quality indicator (CQI), precoding matrix indicator (PMI), and layer index.

[0085] Uplink control information (UCI) may include, for example, one or more of the following: CSI, HARQ feedback for one or more Hybrid Automatic Retransmission Request (HARQ) processes, scheduling requests (SR), link recovery requests (LRR), configured grant or cell group uplink control information (CG-UCI), and / or other control information bits that can be transmitted over a physical uplink control channel (PUCCH) or physical uplink sharing channel (PUSCH).

[0086] One or more channel conditions can be one or more (e.g., arbitrary) conditions relating to the radio / channel state, which can be determined by the WTRU from one or more of the following: WTRU measurements (e.g., L1 / SINR / RSRP, CQI / Modulation and Coding Scheme (MCS), Channel Occupancy, Received Signal Strength Indicator (RSSI), Power Headroom, Exposure Headroom), L3 / Mobility-Based Measurements (e.g., RSRP, RSRQ, s-measure), Radio Link Monitoring (RLM) status, and / or channel availability in the unlicensed spectrum (e.g., whether the channel is occupied based on the listen-before-talk (LBT) procedure determination, or whether the channel is considered to have experienced a consistent LBT failure).

[0087] A PRACH resource can be, for example, a PRACH resource (e.g., in frequency), a PRACH occasion (RO) (e.g., in time), a preamble format (e.g., in terms of total preamble duration, sequence length, guard duration, and / or cyclic prefix length), and / or a preamble sequence (e.g., a specific one) used for sending a preamble in a random access procedure.

[0088] The properties of scheduling information (e.g., uplink grant or downlink allocation) may include at least one of the following: frequency allocation, time allocation mode such as duration, priority, modulation and coding scheme (MCS), transport block size, number of spatial layers, number of transport blocks to be carried, transmit configuration indication (TCI) status or SRS resource indicator (SRI), repetition count, and indication of whether the grant is a configured grant type 1, type 2, or dynamic grant.

[0089] Downlink control information (DCI) indication, or indication, may include at least one of the following: indication by DCI fields, or (e.g., explicit) indication by RNTI used to mask cyclic redundancy checks (CRC) of PDCCH. (e.g., implicit) indication may be provided by properties such as DCI format, DCI size, CORESET or search space, aggregation level, and identification information of a first control channel resource for the DCI (e.g., index of the first CCE). Mapping between properties and values ​​may be signaled, for example, by RRC signaling and / or MAC signaling. (e.g., explicit) indication may be provided by DL MAC control elements (CE).

[0090] The terms network availability state, cell turned off, cell discontinuous transmit (DTX) mode / configuration, or NES state can be used interchangeably. A WTRU can, for example, determine (e.g., implicitly determine) the cell DTX / discontinuous receive (DRX) state from a determined active availability state, and vice versa.

[0091] In this specification, the use of “a” and “an” and similar phrases should be interpreted as “one or more” and “at least one.” Similarly, any term ending in the suffix “(s)” should be interpreted as “one or more” and “at least one.” The term “may” should be interpreted as “may, for example.”

[0092] In this specification, the symbol " / " (for example, a forward slash) may be used to represent "and / or," for example, "A / B" may imply "A and / or B."

[0093] A WTRU can transmit or receive a physical channel or reference signal according to at least one spatial domain filter. The term "beam" is sometimes used to refer to a spatial domain filter.

[0094] A WTRU can transmit a physical channel or signal using the same spatial domain filter used to receive a reference signal (RS), such as CSI-RS, or an SS block. A WTRU transmission is sometimes referred to as the target, and the received RS or SS block is sometimes referred to as the reference or source. A WTRU is sometimes said to transmit a target physical channel or signal according to its spatial relationship to the reference to the RS or SS block (for example, in this case).

[0095] A WTRU may transmit a first physical channel or signal according to the same spatial domain filter used to transmit a second physical channel or signal. The first and second transmits may be referred to as the target and reference (e.g., or source), respectively. In such cases, the WTRU may be said to transmit the first (e.g., target) physical channel or signal according to its spatial relationship with the reference to the second (e.g., reference) physical channel or signal.

[0096] In some cases, spatial relationships can be implicit and may be configured by RRC or signaled by MAC CE or DCI. For example, a WTRU may transmit (e.g., implicitly transmit) a PUSCH and its demodulated reference signal (DM-RS) according to the same spatial domain filter as the sounding reference signal (SRS) indicated by an SRS resource indicator (SRI), which is indicated in DCI or configured by RRC. In some cases, spatial relationships may be configured by RRC for the SRI or signaled by MAC CE for PUCCH. Spatial relationships are sometimes called beam indications.

[0097] A WTRU can receive a first (e.g., target) downlink channel or signal according to the same spatial domain filter or spatial receive parameters as a second (e.g., reference) downlink channel or signal. For example, an association can exist between a physical channel (e.g., PDCCH or PDSCH) and the respective DM-RS of that physical channel. An association can exist when a WTRU is configured using a pseudo-collocation (QCL) assumption type D between corresponding antenna ports, for example, when at least the first and second signals are reference signals. The association can be configured as a transmit configuration indicator (TCI) state. A WTRU can be indicated as an association between a CSI-RS or SS block and a DM-RS by indexing to a set of TCI states configured by the RRC and / or signaled by the MAC CE, for example. The indication is sometimes called a beam indication.

[0098] In this specification, SSB may refer to one or more SSB beams (e.g., spatial relationships) within a collection of SSBs (e.g., an SSB burst). SSB may refer to a beam (e.g., and vice versa), or to a CSI-RS resource related to a beam. SSB, multiple SSBs, and / or SSB burst may refer (e.g., broadly) to one or more beams transmitted from a TRP or from a transmit point (TP).

[0099] A transmit and receive point (TRP) can be used interchangeably with one or more of the transmit point (TP), receive point (RP), radio remote head (RRH), distributed antenna (DA), base station (BS), sector (e.g., of a BS), and / or cell (e.g., a geographic cell area served by a BS). A multi-TRP can be used interchangeably with one or more of the MTRP, M-TRP, and multiple TRPs.

[0100] A base station, such as a gNB, can use reduced downlink transmit / uplink receive activity without (e.g., explicit) cell DTX / DRX (C-DTX / C-DRX) patterns, with limitations by a common channel / signal, for example, WTRU DRX configuration and / or any configured transmit / receive. C-DRX can be configured per WTRU. Alignment of DRX cycles or offsets for different WTRUs can be performed via (e.g., solely via) the RRC. A WTRU may not expect to monitor PDCCH during WTRU DRX off periods, but a WTRU can initiate (e.g., be enabled to initiate) UL transmits (e.g., using PUCCH, RACH, SR, or CG-PUSCH) according to configured resources. Alignment / omission of DRX patterns across multiple WTRUs can be achieved, for example, via a gNB implementation.

[0101] Cell DTX / DRX may provide one or more mechanisms to inform the WTRU whether the cell remains inactive. One or more mechanisms may include extensions to the WTRU DRX configuration, for example, to synchronize / omit DRX cycles or to initiate DRX offsets (e.g., for WTRUs in connected mode or idle / inactive mode), which may allow for longer opportunities for cell inactivity. A cell may, for example, have no transmit / receive during cell DTX / DRX, or maintain limited transmit / receive (e.g., only). For example, a cell may not transmit or receive (e.g., do not need to transmit or receive) one or more (e.g., several) periodic signals / channels, such as common channels / signals and / or WTRU-specific signals / channels.

[0102] Cell DTX / DRX can be applied, for example, to WTRUs that are in the RRC_CONNECTED state. Periodic cell DTX / DRX (i.e., active and inactive periods) can be configured by gNB, for example, via WTRU-specific RRC signaling for each serving cell. Cell DTX / DRX modes can be activated / deactivated, for example, via dynamic L1 / L2 signaling and / or WTRU-specific RRC signaling. WTRU-specific L1 / L2 signaling and common L1 / L2 signaling can be considered / applied to activate / deactivate cell DTX / DRX modes. Cell DTX modes and cell DRX modes can be configured and operated separately (e.g., one RRC configuration set for DL ​​and another RRC configuration set for UL). Cell DTX / DRX can also be configured and / or operated together, for example. One or more of the following parameters, namely periodicity, start slot / offset, and / or on-duration, can be configured, for example, for each cell DTX / DRX configuration. In some examples, cell DTX indication can (for example, also) be part of system information (SI) updates and / or system information block (SIB) signaling. There may be a common time for one or more (for example, all) WTRUs to determine the cell DTX status.

[0103] A WTRU can be configured with multiple cell DRX and / or cell DTX configurations in a given serving cell (for example, simultaneously). A WTRU can be configured with a primary or default cell DTX and / or cell DRX configuration that the WTRU can apply by default. A WTRU can deactivate one or more cell DTX and / or cell DRX configurations based on (for example, upon reception) the reception of a signaling that activates a cell DTX and / or cell DRX configuration (for example, one). A WTRU can activate a cell DTX and / or cell DRX configuration or activate a default cell DTX / DRX configuration based on (for example, upon reception) the reception of a signaling that deactivates a cell DTX and / or cell DRX configuration (for example, one). A WTRU can fall back to (for example, the default) cell DRX and / or cell DTX configuration based on, for example, the expiration of a timer. The WTRU can reset its timer, for example, based on the reception of DL signaling or data and / or indications from the network (NW) in order to remain in a given non-default cell DTX or cell DRX state.

[0104] A network availability state (e.g., NES) or availability state may refer to a cell state in which a cell or transmit / receive point (TRP) has activated at least one NES technique, which may include one or more of the following: cell DTX, cell DRX, spatial domain adaptation (e.g., when a subset of antenna ports and / or elements are turned off), power domain adaptation (e.g., when a subset of channels are transmitted at reduced power or muted), and / or the cell or TRP has been turned off.

[0105] A WTRU can determine whether it can transmit or receive on a resource (e.g., a specific resource) depending on the network availability status, which can imply the power saving status of the gNB. Availability status can correspond to network energy saving status, cell DTX mode, cell DRX mode, and / or gNB activity level. Availability status can be uplink-specific or downlink-specific. Availability status can change per symbol, per slot, per frame, and / or at a longer duration granularity. Availability status can be determined by the WTRU and / or indicated by the network. Availability status can be, for example, "On," "DL and UL Active," "UL Only Active," "Off," "Reduced Tx Power," "Hibernate," "Microsleep," "Light Sleep," or "Deep Sleep." Availability status can be abstracted by one or more NW configuration parameters and / or values. Dynamic indications can point to active availability status (e.g., by DCI or MAC CE signaling). An "off" availability state can imply that the gNB's baseband hardware is completely turned off. A "sleep" availability state can imply that the gNB periodically wakes up to transmit (e.g., certain) signals (e.g., presence signals, synchronization, or reference signals) and / or receive (e.g., certain) UL signals. One or more (e.g., certain) DL or UL resources may be unavailable for one or more (e.g., specific) time periods in one or more availability states, which can allow the network to turn off baseband processing and / or other activities. For example, a WTRU can be configured by the RRC so that each availability has a periodic active and inactive period.Several measurement resources (e.g., SSB or CSI-RS) can be made available in several availability states (e.g., only in those states), which may include one or more of the following: radio link monitoring (RLM), beam fault detection (BFD), radio resource management (RRM) measurements, CSI-RS feedback configuration, and / or different power offsets for CSI feedback.

[0106] (For example, under certain conditions) a WTRU can send requests (e.g., wake-up requests) to the network to correct its availability state to a state where resources that would satisfy the WTRU requirements are available.

[0107] A WTRU can determine its availability status from the reception of availability status indicators, which may be received from, for example, L1 / L2 signaling (e.g., group common DCI or indication), and / or from the reception and / or absence of (e.g., periodic) DL signaling, and / or from its absence, (e.g., implicitly).

[0108] A WTRU can determine whether a resource is available for transmit / receive and / or measure for a determined network availability state, for example, if that resource is applicable in an active availability state. A WTRU can adapt its active connected-mode discontinuous reception (C-DRX) cycle, active spatial elements (e.g., antennas or logical ports), active TRPs, paging occasions, etc., depending on the signaled or determined availability state. A WTRU can be configured with one or more sets of NES transmit and / or receive parameters for each availability state, for example, by broadcast or dedicated configuration signaling. A WTRU can apply NES parameter sets according to the determined or signaled availability state. A WTRU can apply one or more applicable configurations depending on the determined NES state. The set of NES parameters may include, for example, one or more of the following: the number of antenna ports, C-DRX configuration, measurement configuration (for example, RRM, RLM, and / or BFD), CSI feedback, CSI-RS configuration, SSB configuration, conditional handover (CHO) or mobility candidates, and / or a set of active TRPs.

[0109] Availability status can be applicable to at least one transmit resource, receive resource, and / or measure resource. Availability status can be applicable to at least one time period, such as a time slot or time symbol. Availability status can be applicable to serving cells, cell groups, frequency bands, bandwidth parts, TRPs, sets of spatial elements, and / or ranges of frequencies within a bandwidth part. In some examples (for example, when the NES status changes in a cell), the WTRU may receive an availability status change indication that this change is for that cell (for example, only for that cell) but for all cells at the same frequency and / or the same RAT.

[0110] A WTRU may, for example, determine whether an active availability state associated with a cell, carrier, TRP, or frequency band is "off," "deep sleep," or "micro sleep" based on (for example, after) the reception of DL signaling that changes the availability state of a cell or TRP. For example, a WTRU may receive a turn-off command on broadcast signaling, RRC signaling, DCI (e.g., group common DCI), or DL ​​MAC CE (e.g., the indication part of PDSCH). A WTRU may determine the availability state from the reception of an availability state indication, which may be received from L1 / L2 signaling associated with the availability state (e.g., group common DCI or indication) or broadcast signaling.

[0111] In some cases, availability state change indications can be part of SI updates or SIB signaling (for example, in a separate SIB not read by legacy WTRUs). There may be a common time for one or more (for example, all) WTRUs in a cell to determine the availability state status.

[0112] In some cases, a WTRU can determine an NES state change from the reception of group common command L1 signaling (e.g., group common DCI, multistage DCI, a specific DCI format, or DCI scrambled by a configuration or specified NES-specific RNTI). The L1 signaling may indicate a configured set of NES parameters to apply (e.g., one of them), or, for example, a differential configuration from the current set of parameters based on determining an NES state change. The WTRU may send a feedback / acknowledgment to the gNB following the reception of an NES state change indication, which can be multiplexed with UL data (e.g., MAC CE or part of a UL TB as a subheader indication).

[0113] In some examples, a WTRU can determine an NES state change from the reception of broadcast signaling associated with an NES state indication or change, including signaling in (one or more) SIBs, or part of a broadcast or multicast PDSCH. A WTRU can be explicitly indicated in an NES state, for example, in an SIB. A WTRU can be configured with one or more SIBs that can be associated (for example, exclusively) with the configuration of NES parameters. A WTRU can be configured to periodically receive broadcast or multicast indications. A WTRU can determine that an indication is a false positive if, for example, it is not received on an expected periodic occasion, a number of false positives is counted, and / or a timer has elapsed since the last reception of the NES state indication. Based on (for example, subsequently) the determination of a false positive of an NES state indication, a WTRU can initiate inter-cell measurements, inter-frequency measurements, and / or inter-RAT measurements, initiate mobility procedures, and / or evaluate configured CHO candidates.

[0114] WTRU can (implicitly, for example) assume / determine the availability state (e.g., "off", "deep sleep", "microsleep", or "hibernate") associated with a cell, carrier, TRP, and / or frequency band from at least one of the following: namely, the reception of a command or signal indicating a change in availability state; the reception of paging messages, paging DCIs, paging PDSCHs, or paging-related signals (e.g., PEIs) on a subset of POs (e.g., those aligned with the NES DRX cycle, or a configured subset of PDCCH resources); gNB DTX status (e.g., whether the gNB is in active time or whether the associated activity timer is running); lack of presence indication detection; time of day; availability state of the associated cell (e.g., another carrier in the same MAC entity, another carrier in the same cell group, another carrier in the same gNB, another sector in the same gNB, or a configured associated cell or capacity-boosting cell); PSS-only signals or simplified / minimal (stripped) signals. (down) Detection of SSB signals; detection or absence of RS signals (e.g., CSI-RS, PRS, TRS); RRC status of WTRU (e.g., idle, inactive, or connected mode); whether paging was received, for example, within a configured time window; whether system information (e.g., a subset of periodic SI or SIB) was received, for example, within a configured time window; and / or whether the measured (one or more) channel conditions are below or above a threshold.

[0115] A WTRU can (implicitly, for example) assume / determine an availability state (e.g., "off," "deep sleep," "micro sleep," or "hibernate") associated with a cell, carrier, TRP, and / or frequency band from the reception of commands or signals indicating a change in availability state, such as group common DCI or RRC signaling or presence signals in connected mode. A WTRU can (implicitly, for example) determine an availability state from the reception of periodic DL signaling. A WTRU can be configured or specified to associate an availability state with one or more DL signal types (e.g., SSB, partial SSB, and / or one or more periodicities).

[0116] The WTRU can (e.g., implicitly) assume / determine the availability state (e.g., "off", "deep sleep", "micro sleep", or "hibernate") associated with the cell, carrier, TRP, and / or frequency band from the reception of paging messages, paging DCI, paging PDSCH, or paging-related signals (e.g., PEI) on a subset of POs (e.g., one aligned with the NES DRX cycle, or a configured subset of PDCCH resources). A WTRU can assume / determine the availability state after receiving the indication part of DCI or PDCCH scheduling paging, for example, based on receiving an indication (e.g., an explicit indication such as on a reserved bit). A WTRU can assume / determine the availability state after receiving a paging message with a specific P-RNTI, a separately configured NES P-RNTI, or an NES group RNTI. A WTRU can assume / determine the availability state after receiving a paging message with a specific P-RNTI. A WTRU can assume / determine the availability state after receiving a paging message with a specific P-RNTI. A WTRU can assume / determine the availability state after receiving one or more paging early indications (PEI) for the NES. An indication can be configured using subgroups, and a subgroup can be associated with one or more availability states. A WTRU can, for example, assume an availability state after receiving a PEI with an NES subgroup if a subgroup is configured and / or associated with an availability state. An indication of an availability state or availability state switch can be indicated in the paging payload, for example, as a flag part of a paging message or short message. A paging indication can (for example, further) indicate an alternative cell to monitor paging on while the cell from which the signaling was received is off, sleeping, or in the NES state.Paging indications can also indicate or signal applicable reconfiguration parameters (for example, for initial access, applicable PRACH resources, applicable SSB / RS occasions, applicable SI cycles, and / or applicable (one or more) cells and associated availability states).

[0117] A WTRU can (e.g., implicitly) assume / determine an availability state (e.g., "off", "deep sleep", "micro sleep", or "hibernate") associated with a cell, carrier, TRP, and / or frequency band based on the absence of presence indication detection. For example, a WTRU can determine an availability state (e.g., "off" or "deep sleep") associated with a cell if presence indication is not detected on one or more presence indication occasions. For example, a WTRU can assume or change the availability state of a cell after several consecutive false positives or after a timer expires following no presence signal detection. A WTRU can determine that an availability state is active or inactive after the expiration of a timer associated with that availability state. Timers can be configured and / or maintained only in connected mode or in other states (e.g., idle and inactive states) (e.g., even in other states). For example, a WTRU can (e.g., implicitly) determine an availability state from the absence of receiving periodic DL signaling. For example, a WTRU can be configured using a signal quality threshold (e.g., an RSRP threshold). WTRU can assume that an availability state is inactive and / or assume a different availability state if it does not detect a signal associated with the availability state (e.g., a presence signal or SSB) with a signal intensity above a threshold. This criterion can be combined with the lack of detection of the presence signal identification sequence (e.g., detection of a PSS sequence).

[0118] A WTRU can (e.g., implicitly) assume / determine the availability state (e.g., "off", "deep sleep", "microsleep", or "hibernate") associated with cells, carriers, TRPs, and / or frequency bands based on the time of day. For example, a WTRU can be configured to (e.g., automatically) assume / determine the availability state (e.g., "off", "sleep", or "hibernate") for a configured subset of cells (e.g., capacity-enhancing cells) depending on the time of day. For example, a WTRU can determine that a capacity-enhancing cell has an availability state of "on" for certain hours during the day, "deep sleep" for other configured hours, and "off" for a third set of configured hours during the day or night.

[0119] A WTRU can (implicitly, for example) assume / determine an availability state (e.g., "off," "deep sleep," "microsleep," or "hibernate") associated with a cell, carrier, TRP, and / or frequency band based on whether one or more measured channel conditions fall below or above a threshold. For example, a WTRU can assume a change in the NES state based on a change in measured channel conditions or on channel measurements falling below or above a threshold. For example, a WTRU can determine the NES state using a drop in an SSB or CSI-RS measurement, for example, in combination with other signaling. For example, a configured window following a DCI reception can be used to measure SSB and / or CSI-RS for a drop. A WTRU can determine that the NES state has changed and assume / determine an associated action for the NES state (e.g., a trigger for CHO candidate selection, or a trigger for group scheduling for mobility commands) if, for example, a difference in SSB-RSRP drop is measured.

[0120] A WTRU can be configured to monitor indications that can characterize a level of network activity (e.g., availability state). Network activity can be associated with a gNB and / or cell. A WTRU can assume the same availability state for multiple (e.g., all) cell parts of the same gNB, e.g., cells of the same MAC entity. Network activity indications (e.g., presence indications) can include channels (e.g., PDCCHs) and / or signals (e.g., sequences). Activity indications or NES state change indications / commands can indicate a level of activity that a WTRU can expect from the associated gNB and / or cell, e.g., reduced activity. Activity indications can include activity information from other gNBs / cells. Activity indications can be PDCCHs containing group common signaling. For example, a network can send a group common DCI to a group of WTRUs (e.g., WTRUs in a serving cell) indicating a change in activity state or activity level in UL and / or DL. The CRC of the PDCCH can be scrambled with a dedicated "activity indication RNTI or NES-RNTI". The WTRU can be configured using at least one search space associated with the monitoring occasion of the activity indication PDCCH. The indication may include a go-to-sleep signal, e.g., a predefined sequence. The WTRU can predict / determine a reduced activity level over a specific duration, for example, when the WTRU detects a sequence. The WTRU can activate the C-DRX for the indicated time period. Multiple (e.g., two) sequences can be used (e.g., as alternatives) to indicate normal activity and reduced activity.

[0121] Signaling within a PDCCH or activity indication may include at least one of the following: the expected activity level of an associated gNB / cell over a time interval (e.g., availability state), (e.g., defined) send and / or receive attributes for each activity level (e.g., availability state), a set of configurations associated with the activity level for use / application when / when the activity level is indicated (e.g., NES parameter set), a time interval in which the activity level is assumed, which may be signaled in part of the PDCCH or activity indication, and / or a time interval in which the activity level is assumed, which may be predetermined.

[0122] Signaling within PDCCH or activity indication may include the expected activity level (e.g., availability status) of an associated gNB / cell over a specific time interval. Activity levels can be predetermined and / or configured. Activity levels may include, for example, normal activity and reduced activity. Signaling may indicate activity levels. For example, bit "1" may indicate normal activity and bit "0" may indicate reduced activity.

[0123] Signaling within a PDCCH or activity indication may include transmit and receive attributes that can be defined for each activity level (e.g., availability state). For example, during reduced activity, a WTRU may not perform (e.g., not be expected to perform) one or more (e.g., several) PDCCH search spaces (e.g., including all SSs), one or more (e.g., all) types of PDSCHs, transmit PUCCH / PUSCHs, and / or perform one or more (e.g., several) measurements. A WTRU may start or stop monitoring PDCCH and / or TCI states associated with determined NES states, including PDCCH resources or TCI states associated with (de)activated TRPs or spatial elements.

[0124] A set of configurations can be associated with an activity level and used / applied when that activity level is indicated (e.g., NES parameter set). For example, a set of configurations could include SS configurations, CSI reporting configurations, and an index of submitted SSBs. Each set of configurations may have an attribute associated with an activity level, such as a tag that can be set to "reduced activity".

[0125] The time intervals over which activity levels are assumed can be signaled in PDCCH or as part of the activity indication. These time intervals can be represented, for example, using a bitmap. In the bitmap, each bit, for example, can be associated with a specific duration, such as a slot or frame. For example, a bit "1" might indicate normal activity, while a bit "0" might indicate reduced activity for the associated frame.

[0126] Time intervals can be indicated by a start time and / or the length of the interval. The start time can be defined; for example, it can be determined by adding a fixed offset to the time the indication is received. The length of the interval can be configured or signaled in the indication PDCCH.

[0127] The time intervals over which the activity level is assumed can be predetermined. WTRU can assume, for example, the time after receiving an NES state change command (e.g., after the last symbol or slot in which the command was received), or a break delay (e.g., more generally, the time until the NES state is changed). The break time can be in absolute time, in a certain number of symbols, and / or in a certain number of slots.

[0128] A WTRU may determine that an uplink or downlink resource or signal is available for transmission / reception and / or measurement for a determined network availability state, for example, if that resource is applicable in an active availability state. A WTRU may determine that a subset of measurement resources and / or signals (e.g., SSB, CSI-RS, TRS, PRS, etc.) is not applicable in one or more (e.g., several) availability states. A WTRU may determine that a subset of uplink or downlink resources (e.g., PRACH, PUSCH, PUCCH, etc.) is not applicable in one or more (e.g., several) availability states. A WTRU may transmit one or more (e.g., several) uplink signals (e.g., SRS, pSRS, PRACH, UCI, etc.) in a subset of network availability states (e.g., only in that subset).

[0129] Synchronization signals and procedures can be implemented in a network (e.g., 5G NR). Downlink synchronization can be the process by which a WTRU detects radio frame boundaries (e.g., the exact timing of when a radio frame begins) and OFDM symbol boundaries (e.g., the exact timing of when an OFDM symbol begins). Downlink synchronization can be performed, for example, by detecting and analyzing a synchronization signal block (SSB).

[0130] The synchronization signal and PBCH block (e.g., SSB) may include, for example, primary and secondary synchronization signals (e.g., PSS and SSS), each occupying one symbol and 127 subcarriers, as shown in the example in Figure 2, and a PBCH (e.g., spanning three OFDM symbols and 240 subcarriers), but leaving an unused portion in the middle for the secondary synchronization signal (SSS) on one OFDM symbol. The possible time location of an SSB within a half-frame can be determined, for example, by the subcarrier spacing and / or periodicity of the half-frame on which the SSB is transmitted, which can be configured by the network. During a half-frame, different SSBs may be transmitted in different spatial directions (e.g., using different beams across the coverage area of ​​a cell).

[0131] Multiple SSBs can be transmitted within the carrier's frequency span. The PCIs of SSBs transmitted at different frequency locations may not be unique; for example, different SSBs in the frequency domain may have different PCIs. An SSB associated with an RMSI is sometimes called a cell-defined SSB (CD-SSB). A PCell can be associated with a CD-SSB located (for example, always) on a synchronous raster.

[0132] Figure 2 shows an example of the time-frequency structure of SSB.

[0133] Polar coding can be used for PBCH. WTRU can assume band-specific subcarrier spacing for SSB, for example, unless the network is configured to assume a different subcarrier spacing. PBCH symbols can carry their own frequency-multiplexed DMRS. QPSK modulation can be used for PBCH.

[0134] Cell search can be a procedure that a WTRU can use to acquire time and frequency synchronization with a cell and to detect the cell ID of that cell. NR cell search can be based on primary and secondary synchronization signals located on a synchronization raster, such as PBCH DMRS.

[0135] System information (SI) can be divided into a master information block (MIB) and several system information blocks (SIB). MIB can be transmitted over the BCH (for example, always) (for example, with a periodicity of 80ms and repetitions occurring within 80ms). MIB can include one or more parameters that can be used to capture SIB1 from the cell. SIB1 can be transmitted over the DL-SCH (for example, with a periodicity of 160ms and / or a variable transmission repetition period within 160ms). A default transmission repetition periodicity for SIB1 can be configured (for example, 20ms). The transmission repetition periodicity may depend on the network implementation. Minimum system information (MSI) for operation on a cell may include MIB and SIB1.

[0136] The SIB1 repetition period can be 20ms, for example, for SSB and CORESET multiplexing pattern 1. The SIB1 repetition period can be the same as the SSB period, for example, for SSB and CORESET multiplexing patterns 2 / 3. SIB1 may contain information about the availability and scheduling of other SIBs (e.g., SIB mapping to SI messages, periodicity, SI window size, etc.), which may include an indication of whether one or more SIBs are provided on demand (e.g., by themselves), and / or other information. For example, if SIB1 indicates that one or more SIBs are provided on demand, it may (e.g., additionally) indicate the configuration required / used by the WTRU to fulfill the SI request. SIB1 can be a cell-specific SIB.

[0137] The Master Information Block (MIB) on the PBCH can provide the WTRU with one or more parameters (e.g., CORESET#0 configuration) for monitoring the PDCCH to schedule the PDSCH carrying System Information Block 1 (SIB1). The PBCH may indicate that no associated SIB1 exists, in which case the WTRU may be directed to a different frequency and / or a frequency range from which the WTRU can assume that no SSB associated with SIB1 exists. The indicated frequency range may be limited to consecutive spectral allocations of the same operator from which the SSB was found.

[0138] Each SSB within an SSB burst set (e.g., each SSB within a (5ms) period of an SSB transmission) can be assigned a unique number, for example, starting from 0 and increasing by 1. The unique number can be reset to 0, for example, in the next SSB burst set (e.g., after an SSB transmission cycle, for example, after a 20ms default cycle, in the next 5ms span). The unique number (e.g., SSB index) can be indicated in the WTRU, for example, via PBCH DMRS and / or via the PBCH payload. Candidate SSBs in a half-frame can be indexed in ascending order of time from 0 to L-1. From a one-to-one mapping with the index of the DMRS sequence transmitted in the PBCH, the WTRU can determine the least significant bits (LSB) of the SSB index per half-frame, for example, if L=4, or if L>4, for example, the three LSB bits. For example (for example, when L=64), the WTRU can determine the three MSB bits of the SS / PBCH block index for each half-frame by the PBCH payload bits. Figure 3 shows an example of an SSB burst with periodicity (for example, 20ms).

[0139] Figure 3 shows an example of SSB beam sweeping within an SSB burst set. One or more beam fault detection and recovery procedures may be implemented, for example, to support reliable and uninterrupted communication between the WTRU and the base station. Beam fault detection may include monitoring of a beam-specific reference signal. The WTRU may receive a beam-specific reference signal from the base station (for example, continuously), which allows the WTRU to track beamforming performance. The WTRU may trigger a beam fault event, for example, if the quality of the received signal degrades below a threshold, indicating a potential beam fault. The WTRU may initiate a beam fault recovery procedure, for example, when a beam fault event is detected. The WTRU may attempt to restore connectivity with the base station (for example, initially) by using the last known beamforming configuration. The WTRU may search for an alternative beam and / or perform a beam sweep (for example, if the attempt to restore connectivity fails), scanning one or more different beamforming configurations in search of a stronger, more reliable beam.

[0140] A WTRU (for example, in a beamformed NR system) can be configured to maintain one or more (e.g., multiple) beam pairs. The WTRU can monitor one or more (e.g., several) periodic SSBs and / or CSI-RSs on a serving DL beam to estimate beam quality and / or calculate corresponding quality metrics. The WTRU's PHY entity can report a beam fault instance (BFI) to the MAC sublayer if, for example, the beam quality during an RS period falls below a configured threshold.

[0141] Lost beam pairs can be re-established (in a faster manner compared to, for example, the RLM / RLF procedure) by employing a BFR procedure (e.g., at the MAC layer of the WTRU) in which a beam fault recovery request is reported to the network when a beam fault is detected. BFR can be configured for beam maintenance on PCells and / or SCells.

[0142] A MAC entity can maintain a beam fault instance counter (BFI_counter) for the purpose of beam fault detection. The MAC entity can count the number of beam fault instance indications received from the PHY entity. A BFR request can be triggered, for example, to notify the serving gNB that a beam fault has been detected if the BFI counter exceeds a certain maximum number of BFIs.

[0143] A MAC entity can reset the BFI counter after the Beam Fault Detection Timer (BFD_timer) has expired (for example, only after that). The reset can help provide some hysteresis to the detection function. A WTRU can reset the BFD timer whenever a BFI is indicated by the PHY layer (for example, in such cases). For example, a MAC entity can reset the BFI counter (for example, only) after not observing any BFI indications from the PHY layer for three consecutive CSI-RS periods (for example, three CSI-RS periods).

[0144] A WTRU can report a BFR request by, for example, initiating a random access procedure with (for example, several) parameter values ​​(e.g., PreambleTransMax, power ramping step, and / or target receive preamble power). For example, a WTRU can use a random access procedure for beam re-establishment, since it can select (for example, an appropriate) PRACH preamble and / or PRACH resource depending on the best measured downlink beam (e.g., DL SSB). A WTRU can re-establish a beam pair if / when it can determine the association between the DL beam and the UL preamble and / or PRACH occasion. The downlink beam selected by the WTRU can be tested, for example, by receiving a Random Access Response (RAR) on the DL beam. The re-establishment RA procedure can be performed faster if, for example, a gNB constitutes (for example, a specific) set of contention-free PRACH preambles / resources that can be prioritized for selection by the WTRU when initiating the RA procedure. Beam fault recovery for PCell can be considered complete, for example, upon completion of a random access procedure.

[0145] Beam fault and detection procedures can (for example, also) address one or more secondary cells. The WTRU can trigger beam fault recovery by transmitting a BFR MAC CE for a secondary cell (SCell) when a beam fault is detected on the SCell. The WTRU can (for example, also) select a suitable beam for the affected SCell if there are available alternatives that include this information (for example, along with details about the beam fault) in the BFR MAC CE. Beam fault recovery for the SCell can be considered complete based on (for example, at the time of) the receipt of a PDCCH indicating an uplink grant for a new transmission for the HARQ process used for transmitting the BFR MAC CE.

[0146] One or more operators may (for example, often) deploy several small cells and overlaid macrocells. Macrocells may transmit SSBs and / or SIBs. One or more small cells do not always have traffic. The network may (for example, therefore) consume unnecessary energy by transmitting SSBs that may not be necessary, for example, especially in low-load scenarios where the network could be able to save some energy if the network does not transmit one or more SSBs according to a fixed pattern and periodicity. A set of small cells may not transmit SSBs (for example for this reason) but may transmit presync signals or discovery signals (for example, only those). The signals may be, for example, a combination of PSS and SSS (for example, PSS+SSS).

[0147] A WTRU performing initial access can discover (e.g., receive) a presync signal from a first cell (e.g., an NES cell) and / or an SSB / SIB-1 from a second cell (e.g., a macrocell). Macro coverage may overlap with one or more different small cells in one or more different areas. The network can (e.g., may want) camp on one or more WTRUs performing initial access to one or more suitable small cells.

[0148] The WTRU can perform initial access procedures and determine the RACH configuration for one or more small cells to send discovery and / or presync signals (e.g., only that).

[0149] Network Energy Saving (NES) terminology may be explained herein. The cell DTX active period may be the duration for which a configured cell DTX pattern is active (e.g., a period of time during the on-duration period of the cell DTX pattern). The WTRU may, for example, monitor the PDCCH and / or one or more other DL signals and channels during the cell DTX active time period (e.g., may be predefined to monitor). Monitoring may be applicable only after (e.g., only after) the cell DTX configuration has been indicated by the NW to be activated.

[0150] The cell DTX inactivity period is the duration during which a configured cell DTX pattern is inactive / inactive (e.g., a period of time outside the periodic on-duration period of the cell DTX pattern). The cell DTX inactivity period may be applicable only after (e.g., only after) the cell DTX configuration has been indicated by the network to be activated.

[0151] The cell DRX active period is the duration for which the configured cell DRX pattern is active (e.g., the time period during which the cell DRX pattern is on-duration). During the cell DRX active time period, the WTRU may transmit one or more UL signals and / or on one or more UL channels (e.g., they may be predefined to enable transmission). The cell DRX active period may be applicable only after the cell DRX configuration has been indicated by the network to be activated (e.g., only thereafter).

[0152] The Cell DRX inactivity period can be the duration during which a configured Cell DRX pattern is inactive / inactive (e.g., a period of time outside the periodic on-duration period of the Cell DRX pattern). The Cell DRX inactivity period can be applicable only after (e.g., only after) the Cell DRX configuration has been indicated by the NW to be activated.

[0153] An activated cell DRX / DTX can be in the state of a configured cell DRX or cell DTX pattern, for example, that state is activated by L1 / L2 DL signaling, RRC (re)configuration, and / or cell common configuration, and is not deactivated.

[0154] A deactivated cell DRX / DTX can be in the state of a configured cell DRX or cell DTX pattern, for example, that state is deactivated by L1 / L2 DL signaling, RRC (re)configuration, and / or cell common configuration.

[0155] The links between availability status, NES status, and / or cell DTX / DRX. These terms may be used interchangeably in this specification. A WTRU can determine the cell DTX status from a determined active availability status (e.g., implicitly) and vice versa. A WTRU can determine the cell RTX status from a determined active availability status (e.g., implicitly) and vice versa.

[0156] The terms “alternate cell” and “stable cell” may be used interchangeably herein. A WTRU may be configured with a list of stable cells (e.g., one or more macrocells, or other alternative cells that do not turn off). The list may be a list of alternative cells per serving cell / camped cell, or a general list of PCIs for the entire network, tracking area, etc. A WTRU may be configured with a measurable configuration for alternative cells. A WTRU may be configured or predefined with one or more stable cells to perform initial access, mobility, and / or cell reselection when the current serving cell (e.g., an NES cell) is turned off or the NES state is activated. A WTRU may be configured with a list of stable cells for each broadcast signaling or dedicated signaling, for example, per serving cell, per gNB, per PLMN, and / or per network identification information. Stable cells may correspond to cells that do not apply and / or are not configured to apply NES techniques (e.g., non-NES cells).

[0157] An NES cell can be a cell configured using at least one NES technique or method (e.g., cell DRX / DTX, spatial domain adaptation, power domain adaptation, cell turn-off, sleep, etc.). A cell can be designated as an NES cell if, for example, the cell activates an NES technique (for example, only if it does). The terms "non-NES cell" and "stable cell" can be used interchangeably. The terms "NES cell" and "unstable cell" can be used interchangeably.

[0158] A Ref-PCell or anchor cell can be a reference primary cell on which a WTRU can rely for initial access, RLM, BFD, and / or paging procedures. A Ref-PCell can be associated with one or more other PCells or SCells, which may be NES cells. System information broadcast from a Ref-PCell may advertise / indicate the presence of other cells associated with the Ref-PCell, including, for example, configurations associated with the NES (e.g., presync signals, transmit occasions, PRACH configurations, and / or NES state cycle length and information / configurations). The terms "ref-PCell" and "anchor cell" can be used interchangeably.

[0159] System information transmission and capture terminology are described herein. Synchronization signal transmission can use low-power transmission (Tx) and power amplifiers. gNB may be equipped with a low-power transmitter and / or power amplifier (PA). For example, a synchronization sequence, including one or more legacy SSBs described herein, can be transmitted by a gNB using lower-power Tx and / or PA.

[0160] gNB transmission of sink signals using low-power Tx and PA can be associated with the cell NES state. Sink signals can be transmitted using low-power Tx and PA when, for example, the associated cell is in an NES inactive state. Sink signals can also be transmitted using normal Tx and PA when, for example, the associated cell is in an NES active state.

[0161] Figure 4 shows an exemplary flowchart of a WTRU performing / implementing multi-cell random access using on-demand SSB. As shown in Figure 4, the WTRU can detect / receive a presync signal from a first cell, e.g., an NES cell. The WTRU may be configured to detect / receive one or more presync signals as part of the initial access procedure. The presync signals may be, or include, a discovery signal, an SSB signal, a slimmed-down version of an SSB signal, e.g., PSS, SSS, or PSS+SSS. The SSB signals associated with the presync signals described herein may not be full SSB signals.

[0162] For example, a WTRU can determine the cell ID and / or transmit beam index (e.g., beam index and / or transmit beam) from a presync signal. For instance, based on the properties of the presync signal, a WTRU can determine the cell transmitting the presync signal (e.g., the first cell) and / or the transmit beam index associated with the presync signal. The properties associated with the presync signal can be, or include, at least one of the following: time, frequency, sequence selection, phase, and sequence identification (ID).

[0163] In the example, the WTRU may process (for example, decide to process) a presync signal received from a first cell if, for example, pre-sync-ReceivedPower is greater than a first threshold. The threshold can be known to the WTRU, for example, through preconfiguration. The WTRU can be predefined using the threshold. In some examples, the WTRU may receive the threshold from the network during network connectivity (for example, during one of the WTRU's last connections to the network).

[0164] In some examples, the WTRU can determine the cell identification information of a first cell, such as PCI, from the received presync signal of the first cell. The WTRU can determine the transmit beam index (e.g., beam index and / or transmit beam) associated with the received presync signal of the first cell. The WTRU can determine the cell ID and / or the transmit beam index (e.g., beam index and / or transmit beam) associated with the presync signal, for example, based on the properties of the presync signal. For example, the properties associated with the presync signal (e.g., physical properties) can be one or more of the following, or may include: time, frequency, sequence selection, phase, sequence ID, etc. In some examples, the received sequence can provide cell identification information through the network configuration (for example, as in 5G NR).

[0165] The WTRU can determine whether a condition is met. For example, the condition to be met may be at least one of the following: the received power associated with the presync signal is greater than a threshold; no SSB is being received from the first cell; or the first cell is in an energy-saving state. If the condition is met (for example, based on the determination that the condition is met), the WTRU can receive transmissions from the second cell.

[0166] A WTRU can receive one or more full SSBs from a second cell. A WTRU can search for (for example, decide to search for) one or more SSBs from a second cell. A WTRU can search for (for example, decide to search for) one or more SSBs from a second cell if at least one of the following conditions is satisfied: namely, the presync received power from the first cell is greater than a first threshold (threshold 1), no full SSBs are received from the first cell, the first cell is determined to be in the NES state, and / or the RSRP from the second cell is greater than a second threshold (for example, RSRP_from_second cell < threshold 2). A WTRU can be preconfigured or predefined using a first threshold (threshold 1) and / or a second threshold (threshold 2).

[0167] In the example, the WTRU may receive a transmission from the second cell if the WTRU determines that the conditions described herein are met. For example, the WTRU may receive a transmission from the second cell if it determines that at least one of the following is met: the received power associated with the presync signal is greater than a threshold; no full synchronous signal block (SSB) is received from the first cell; or the first cell is in an energy-saving state. The transmission from the second cell may be, or include, at least one of SSB or SIB.

[0168] In some examples, a WTRU may search for (or decide to search for) one or more SSBs from a second cell on the same carrier frequency on which the WTRU detects (or receives) the presync signal. In some examples, a WTRU may search for (or decide to search for) one or more SSBs from a second cell on different carrier frequencies on which the WTRU detects (or receives) the presync signal.

[0169] In some examples, a WTRU may search for (for example, decide to search for) one or more SSBs from a second cell based on indications in a presync signal received from a first cell. Indications can be transmitted through any of the physical properties of the presync signal received from the first cell, such as time resources, frequency resources, sequence selection, sequence phase, etc. The indications can be for the WTRU to find SSBs and / or one or more SIBs from different cells. The indications may provide one or more parameters related to one or more of the following for searching for SSBs in the second cell: time resources for detecting SSBs, frequency resources for detecting SSBs, carrier frequency, and / or cell IDs, such as PCI and / or a set of cell IDs for the second cell.

[0170] In some examples, the WTRU may search for (for example, decide to search for) one or more SSBs from a second cell, where the WTRU determines the timing for the second cell SSBs based on a presync signal received from the first cell.

[0171] In some examples, the WTRU may search for (for example, decide to search for) one or more SSBs from a second cell, where the WTRU determines the cell ID of the second cell based on the presync signal received from the first cell.

[0172] As described herein, a WTRU can receive transmissions from a second cell. For example, a transmission from a second cell may be or include an SSB and / or SIB-1. A WTRU can decode a transmission from a second cell (e.g., an SSB and / or SIB-1). In some examples, a WTRU can receive a system information block (e.g., an additional system information block) from a second cell.

[0173] As described herein, a transmission can be associated with at least one SSB from a second cell. The WTRU can determine (for example, it can be further configured to determine) that the second cell receives at least one SSB based on at least one of the following parameters: the same frequency at which a presync signal is detected, a different frequency at which a presync signal is detected, an indication associated with a presync signal, or at least one of the following parameters: time resources for detecting at least one SSB, frequency resources for detecting at least one SSB, a carrier frequency associated with at least one SSB, or a cell ID associated with at least one SSB.

[0174] The WTRU can determine the RACH configuration for a first cell. For example, the WTRU can determine the RACH configuration based on the transmit and presync signals from a second cell. The RACH configuration is or may include the association of the presync signal to at least one physical RACH occasion (RO) associated with the first cell. The presync signal may be associated with the first cell. The RACH configuration is at least one (for example, more) of the following: the system timing associated with the first cell, and the first cell ID, the association of the transmit beam (Tx beam) to a physical RO associated with the first cell, or a partition of the RACH preamble with the RO or TX beam associated with accessing the first cell.

[0175] The WTRU can determine the PRACH configuration for the first cell based, for example, on one or more of the presync signals received from the first cell and / or the SSB / SIB-1 received from the second cell.

[0176] The WTRU can determine one or more of the following configuration parameters for the first cell: namely, the system timing and cell ID of the first cell, the association of the first cell Tx beam to the RO of the first cell, the partition of the RACH preamble associated with accessing the first cell, and / or, for example, the association of the first cell SSB to the first cell RO for preamble retransmission on the first cell.

[0177] In some examples, the WTRU can determine the system timing of the first cell based on the presync signal of the first cell and the SSB and / or SIB-1 of the second cell. In some examples, the WTRU can derive (for example, be pre-configured to do so) the system timing of the first cell from the presync timing and system frame number (SFN) of the second cell. The WTRU can derive the SFN of the second cell from the SSB of the second cell. In some examples, the WTRU can determine the system timing of the first cell, e.g., the SFN of the first cell, which is equal to the system timing of the second cell, e.g., the SFN of the second cell, if configured. In some examples, the WTRU can determine the SFN of the first cell, which is equal to the SFN of the second cell, e.g., the SFN of the second cell, with an offset. The offset can be pre-defined for the WTRU. In some examples, the offset can be indicated by the second cell, e.g., through the SIB-1. In some cases, the WTRU can determine the offset for the first cell through its presync signal or determined identification information.

[0178] In some examples, the WTRU can determine the beam index for the first cell, for example, the pre-sync beam index or SSB beam index, based on the detected beam of the second cell. The terms transmit beam index, beam index, or transmit beam can be used interchangeably. The WTRU can be (pre)configured to map the detected beam index of the second cell to the beam index of the first cell.

[0179] In some examples, the WTRU can determine the beam index of the first cell based, for example, the detected beam index of the second cell from the second cell's SSB and information received in the second cell's SIB-1. The second cell's SIB-1 can provide, for example, a mapping for determining the beam index of the first cell based on the detected beam index of the second cell. The second cell's SIB-1 can provide beam mapping information for several NES cells.

[0180] The WTRU can evaluate one or more conditions for sending a PRACH on the first cell. For example, the WTRU may send a RACH on the first cell (e.g., decide to send one) if at least one of the following is satisfied: no SSBs have been received from the first cell, the first cell is determined to be in the NES state, RSRP_from_first cell > threshold 1, and / or RSRP_from_second cell < threshold 2.

[0181] For example, if the WTRU decides to send RACH on a first cell, it can determine a suitable RACH preamble, RO, and / or other RACH transmission parameters for the first cell.

[0182] If the WTRU decides not to send a RACH on the first cell, it can, for example, decide to send a RACH on the second cell.

[0183] The WTRU can determine the RO associated with a first cell and / or the RACH preamble for the first cell. For example, the WTRU can determine the RO associated with a first cell and the preamble based on the presync signal and / or the RACH configuration for the first cell. The WTRU can determine a suitable RO and / or a suitable RACH preamble for transmitting RACH on the first cell. The WTRU's determination of the RO and / or RACH preamble for the first cell may be based on one or more of the following: the presync signal of the first cell; the Tx beam of the first cell as determined by the WTRU; the measured SSB index of the second cell (e.g., one), e.g., the SSB index with the highest RSRP; the system timing of the first cell as determined by the WTRU; the system timing of the second cell, e.g., as received in the SSB / SIB-1 of the second cell; and / or, e.g., the RACH configuration determined / selected by the WTRU, received from the second cell in SIB-1.

[0184] A WTRU can send a preamble on the RO associated with the first cell. For example, a WTRU can send the first RACH preamble on the first cell. On the first cell, the WTRU can perform the RACH procedure using the determined parameters. In some examples, a WTRU can send the RACH preamble Msg1 on the first cell.

[0185] The WTRU can transmit a RACH preamble to a first cell using transmit power. The transmit power can be determined, for example, based on the use of a presync signal from the first cell as a pathloss reference. The WTRU can be configured to apply an offset to the pathloss reference and / or the determined transmit power. In the example, the offset can be based on the energy-saving state of the first cell. In the example, the offset can be determined by the WTRU based on the energy-saving state of the first cell and / or based on the presync signal. In the example, the WTRU can receive an offset from a second cell, for example, as part of the RACH configuration and / or a separate indication.

[0186] In some examples, a WTRU can transmit a RACH MsgA to a first cell. In some examples, a WTRU can transmit a RACH on the first cell using its transmit beam. The WTRU can determine the transmit beam using one or more of the following: a WTRU transmit beam corresponding to a WTRU receive beam used to determine the Tx beam of a presync signal from the first cell; a transmit beam corresponding to one or more of the WTRU receive beams used to detect one or more Tx beams of the presync signal from the first cell, for example, if the WTRU receives two or more beamformed instances of the presync signal (for example, the WTRU can select the best / strongest presync signal to determine the transmit beam); a transmit beam corresponding to a WTRU receive beam through which the WTRU detects the presync signal from the first cell; a transmit beam corresponding to a WTRU receive beam through which the WTRU detects the SSB of a second cell; and / or a transmit beam corresponding to a WTRU receive beam through which the WTRU detects the SSB used to determine the SSB index of the second cell SSB.

[0187] The WTRU can monitor RA responses and / or SSBs from the first cell. The WTRU can monitor RACH responses from the first cell based on sending a first RACH message, e.g., Msg1 or Msg A, to the first cell (for example, when it is sent).

[0188] In some examples, a WTRU can monitor the SSB from a first cell while the RAR window is active for the WTRU's transmitted RACH preamble. For example, a processor can be configured to monitor the RAR from a first cell during the RAR window. The RAR window can be pre-configured and / or received from a base station (e.g., a gNB).

[0189] In the example, the WTRU can monitor RARs from the first cell during the RAR window. The WTRU can determine whether a RAR has been received. If a RAR has been received (for example, based on the determination that a RAR has been received), the WTRU can determine the resource to send the message to. The WTRU can then send the message on that resource.

[0190] In the example, the WTRU can determine whether a RAR has been received. If no RAR has been received (for example, based on the determination that no RAR has been received on the first cell), the WTRU can determine that at least one SSB has been received from the first cell. Based on the determination that at least one SSB has been received from the first cell, the WTRU can transmit a preamble (for example, a second preamble) on the RO associated with the first cell. The RO used for transmitting the second preamble may be based on the measured SSB associated with the first cell (for example, based on a further measured SSB).

[0191] In the example, the WTRU can determine whether the RAR has been received. If the RAR has not been received (for example, based on the determination that the RAR was not received on the first cell), the WTRU can determine whether the number of preamble retransmissions exceeds a threshold. If the number of retransmissions exceeds a threshold (for example, based on the determination that the number of preamble retransmissions exceeds a threshold), the WTRU can transmit the preamble on the second cell.

[0192] In the example, the WTRU can determine whether a RAR was received. The WTRU can determine whether a fallback indication was received during the RAR on the first cell. If a fallback indication was received (for example, based on the determination that a fallback indication was received), the WTRU can perform the RACH procedure on the second cell.

[0193] In the example, the WTRU may determine that the reference signal received power (RSRP) associated with the second cell is below a threshold (e.g., a second threshold). If the RSRP is below the threshold (e.g., based on the determination that the RSRP is below the second threshold), the WTRU may perform a RACH transmission on the first cell.

[0194] In some examples, a WTRU can monitor RACH responses and / or SSBs after transmitting its RACH preamble on a first cell. A WTRU can receive SSBs from the first cell. A WTRU can receive one or more SSBs from the first cell. A WTRU can determine a beam index for the first cell, e.g., an SSB beam index, (for example, based on having received (one or more) SSBs from the first cell). The beam index can correspond to (e.g., one) measured / detected SSB from the first cell. In some examples, the beam index can correspond to an SSB received with the highest RSRP.

[0195] In some examples, the WTRU may receive SIB-1 from the first cell. The WTRU may then determine (for example, based on the SSB and / or SIB-1 received from the first cell) one or more of the following: the beam index of the first cell; the system timing of the first cell, e.g., SFN; and / or the RACH configuration for the first cell, which may include the SSB-to-RO mapping for the first cell, RACH preamble divisions, power ramping parameters, and / or contention-free RACH resources and configurations.

[0196] Based on / after receiving SSB from the first cell, the WTRU can transmit a second RACH preamble. The WTRU can transmit a RACH preamble, for example, a second RACH preamble, on the first cell.

[0197] In some examples, a WTRU may decide to send a RACH preamble on the first cell, for example, a second RACH preamble, if the WTRU does not receive a RACH response from the first cell in response to the WTRU's first RACH transmission within the configured duration.

[0198] In some examples, a WTRU may decide to send a RACH preamble on the first cell, for example, a second RACH preamble, if the WTRU does not receive an SSB or RACH response from the first cell in response to the WTRU's first RACH transmission within the configured duration.

[0199] The WTRU (for example, not receiving / detecting SSB from the first cell) can determine the RACH configuration and parameters for a RACH transmission (e.g., a second RACH preamble / transmission) in the same manner as the first RACH transmission on the first cell. The WTRU can apply (e.g., decide to apply) a power ramping counter for a RACH preamble transmission, such as a second RACH transmission, on the first cell. The WTRU can use the default power ramping configuration or the power ramping configuration received from the second cell.

[0200] In some examples, a WTRU may decide to send a RACH preamble, for example, a second RACH preamble, on the first cell if it has received one or more SSBs from the first cell. Based on the SSBs received from the first cell, the WTRU may determine the RACH configuration and parameters for the RACH transmission on the first cell. The WTRU may receive an SSB from the first cell after its first RACH transmission on the first cell.

[0201] The WTRU can determine, for example, a (preferred) RACH preamble and RO for a second RACH transmission on the first cell, based on the detected SSB index of the first cell and the SSB-to-RO mapping received from the second cell.

[0202] The detected SSB index of the first cell can be the SSB index of (e.g., one) measured SSB from the first cell. In some examples, WTRU can select the SSB index of the best measured SSB, e.g., the SSB with the highest RSRP value. In some examples, WTRU can select (e.g., any) SSB index from among the measured SSBs with an RSRP of PBCH greater than (e.g., a configured) threshold.

[0203] The WTRU may, for example, receive an SSB and at least one SIB, e.g., SIB-1, from the first cell after the WTRU's first RACH transmission on the first cell.

[0204] The WTRU can determine, for example, a (preferred) RACH preamble and RO for a second RACH transmission on the first cell, based on the detected SSB index of the first cell and the SSB-to-RO mapping received from the first cell.

[0205] A WTRU can perform a RACH transmission on the second cell. A WTRU can transmit a RACH on the second cell (for example, decide to transmit one).

[0206] For example, if the WTRU does not receive a RACH response (e.g., no RACH response) from the first cell after N transmissions of the RACH preamble on the first cell (e.g., where N can be a configuration parameter), it may send (decide to send) a RACH on the second cell. The N transmissions may be retransmissions of the preamble.

[0207] A WTRU may, for example, decide to send a RACH on a second cell if it receives a RACH response from a first cell along with a fallback indication. The WTRU may receive a fallback indication from the first cell in a backoff indicator and / or another indication, such as a (e.g., special) bit in the RACH response. The WTRU may be configured / defined to interpret the (e.g., special) bit as a fallback indicator to the second cell.

[0208] In some examples, a WTRU may receive a UL grant for sending an MSG3 to a second cell in a RACH response from a first cell. The WTRU can then (for example) send the MSG3 on the second cell in accordance with its received grant from the first cell.

[0209] In some examples, the WTRU can determine the RACH configuration and parameters for RACH transmission on the second cell based on the SSB and SIB-1 received from the second cell. In some examples, if the WTRU has already transmitted at least one RACH transmission on the first cell, the WTRU can transmit a RACH on the second cell with higher initial power. For example, the WTRU can use a higher power ramping counter for RACH transmission on the second cell. The use of a higher or more aggressive power ramping counter may be conditional on the WTRU having transmitted at least one or more RACH transmissions on the first cell through the configuration received from the second cell.

[0210] As described herein and shown in Figure 4, a WTRU can perform multi-cell random access using on-demand SSB. The WTRU can detect (e.g., receive) a presync signal from a first cell (e.g., an NES cell) and an SSB from a second cell. Based on the detection / reception, the WTRU can determine the RACH configuration of the first cell from the SSB / SIB (e.g., SIB-1) on the second cell. The WTRU can perform random access using both cells by, for example, performing a first preamble transmission with suboptimal pseudo-collocation (QCL) assumptions for the first cell. The WTRU can receive (e.g., on-demand) SSB. The WTRU can retransmit a physical random access (PRACH) preamble based on the on-demand SSB. The WTRU can fall back to the second cell if, for example, RAR is not received.

[0211] The WTRU can detect (e.g., receive) a presync (e.g., discover) signal from a first (e.g., small) cell, such as a combination of PSS and SSS (e.g., PSS plus SSS) (e.g., PSS plus SSS) (e.g., with some modification), as shown in Figure 4. The WTRU can identify the first cell and the transmit beam index (e.g., beam index and / or Tx beam) that transmits the presync signal through one or more of the physical properties of the signal (e.g., time, frequency, sequence selection, phase, sequence ID, etc.). WTRU can receive and decode SSB / SIB-1 from a second (e.g., macro) cell if, for example, at least one of the following is satisfied: namely, the pre-sync received power from the first cell is greater than a first threshold (e.g., pre-sync-ReceivedPower > threshold 1 from the first cell), no SSBs are received from the first cell or the first cell is determined to be in an NES state, and / or the RSRP from the second cell is less than a second threshold (e.g., threshold 2).

[0212] As shown in Figure 4, the WTRU can determine a PRACH configuration for the first cell based, for example, on the received SIB-1 of the second cell and the detected (e.g., received) presync sequence of the first cell, which may include, for example, the system timing and cell ID of the first cell, the association of the first cell Tx beam to the RACH occasion (RO) of the first cell, the partition of the RACH preamble associated with accessing the first cell, and / or the association of the first cell SSB to the first cell RO for preamble retransmission on the first cell. The WTRU can determine the RO / preamble to be used on the first cell based, for example, on the presync signal of the first cell and / or the (e.g., configured) association between the presync and RO received on the second cell. The WTRU can then perform the RACH procedure described herein on the first cell using, for example, the determined parameters. The WTRU can monitor the RA response on the first cell. The WTRU can monitor SSB reception from the first cell, for example, while the RAR window is active. The WTRU can send another preamble to the first cell, for example, if no RAR has been received on the first cell and the WTRU has received one or more SSBs from the first cell. The WTRU can determine which RO to use for preamble transmission on the first cell, for example, based on the (e.g., best) measured SSB on the first cell. The WTRU can send a preamble on the second cell, for example, after N attempts (e.g., N≧1), if no RAR has been received on the first cell.If the WTRU receives a fallback indication from the first cell (for example, in a backoff indicator or a bit in the RAR payload), it can continue the RACH procedure on the second cell (for example, by sending an MSG3 with the grant indicated in the RAR payload, or by retransmitting the preamble on the second cell).

[0213] The WTRU can perform initial access using multiple (e.g., two) random access procedures. The WTRU can perform initial access in multiple steps, with the intended result of connecting to a cell in the NES state, which may be the cell measured under the best channel conditions (e.g., based on one or more find signal measurements). The WTRU can perform RA to a less-than-best measured cell (e.g., the second-best measured cell) (e.g., in the first step). The WTRU can indicate the best-measured cell portion of the PUSCH payload in msg3 or msgA. The WTRU can initiate measuring the SSB (e.g., upon successful completion of RA on the less-than-best measured cell) and / or receive the SSB on the indicated cell (e.g., the best-measured cell) in the PUSCH payload.

[0214] For example, one or more WTRU actions, such as those described herein and / or shown in Figure 4, may be used in any order, one or more (e.g., any or all) of the actions described herein (e.g., previously). A WTRU can detect (e.g., receive) a presync (e.g., discover) signal (e.g., a PSS+SSS signal) from a first cell. A WTRU can identify the first cell transmitting the presync signal through one or more of the physical properties of the signal, such as time, frequency, sequence selection, phase, or sequence ID. A WTRU can receive and decode an SSB / SIB-1 from a second cell.

[0215] The WTRU can determine PRACH parameters, for example, based on SIB-1 received from a second cell. The WTRU can perform (e.g., decide to perform) the RACH procedure on the second cell if at least one of the following is satisfied: presync received power from the first cell > threshold 1, no SSBs are received from the first cell, the first cell is determined to be in an NES state, and RSRP_from_second cell > threshold 2. Thresholds 1 and 2 can be configuration parameters received from the network, or otherwise indicated to the WTRU, or determined by the WTRU (e.g., (pre)defined for the WTRU).

[0216] The WTRU can perform the RACH procedure (as described herein, for example) on the second cell using determined parameters. The WTRU can provide indications of the detected first cell, for example, through (MsgA / Msg3). The indications may include, for example, cell identification information, beam index, and / or information related to the presync detected by the WTRU of the first cell.

[0217] The WTRU may receive a cell index from the second cell response to the transmitted RACH, for example in MsgB / Msg4 or in a PDSCH after the RACH, along with the RACH configuration for the first cell (e.g., SI or new SIB). The configuration may include, for example, one or more dedicated preambles, a mapping from the second cell SSB to the RO on the first cell, one or more SSBs, and / or ROs to be used for transmitting the PRACH on the first cell.

[0218] The WTRU can, for example, monitor an SSB (e.g., an on-demand SSB) on the first cell based on / at the successful completion of RACH on the second cell, and if the WTRU has not received a RACH configuration for the first cell.

[0219] The WTRU can perform a second RACH procedure by sending a RACH preamble (e.g., Msg1 or MsgA) using the determined parameters on the first cell, for example by selecting the indicated RO / SSB.

[0220] Beam obstruction avoidance and detection can be performed in an energy conservation network (ESN). A WTRU can receive configurations for monitoring one or more NES cells. The WTRU can be configured with a set of NES cells to monitor, for example, when an indication such as a beam obstruction avoidance flag is configured on the serving cell, when the serving cell is associated with at least one NES / astable cell, and / or when a BFD is configured on the serving cell. The WTRU can measure one or more channel conditions associated with discovery or presync signals associated with an NES cell (for example, when a non-serving NES cell is monitored). The BFD configuration of a serving cell may include a list of candidate cells to monitor (e.g., an NES cell, or a cell associated with a RefPCell) based on / when satisfying at least one condition used to determine whether / when the WTRU monitors an NES cell (e.g., as described herein).

[0221] In some examples, the WTRU can be connected to a serving cell (e.g., a stable cell), sometimes referred to as the “second cell.” The WTRU can monitor one or more additional NES cells, sometimes referred to as the “first cell.” The WTRU can be connected to the second cell. The WTRU may already be receiving other system information, such as the SSB, and / or SIB-1 and / or other SIBs. The WTRU can be configured with a set of NES cells to be monitored (e.g., by the second cell). The WTRU may receive configurations to monitor one or more NES cells, for example, as part of a beam fault avoidance procedure on the second cell. The WTRU can be configured with (e.g., a preferred) RS to monitor at least one of the beams on the second cell.

[0222] A WTRU can be configured with one or more conditions indicating whether / when it is expected that the WTRU will monitor the NES cell. The configured conditions (one or more) can be based on measurements of the reference signal of the second cell. In some examples, the conditions can be based on beam fault instances of the beam connected to the second cell.

[0223] A WTRU may monitor (for example, decide to monitor) one or more NES cells. A WTRU may decide to monitor configured NES cells. NES cells may be configured, for example, as part of beam fault avoidance or BFD procedures on a second cell.

[0224] A WTRU may monitor (e.g., decide to monitor) a configured NES cell based on one or more monitoring conditions that can be specified using a configuration. One or more conditions may include one or more of the following: the WTRU receiving N BFIs for a second cell within time T; the WTRU's BFD_counter > threshold 3A on the second cell; a measured channel condition (e.g., RSRP) < threshold 2 on the second cell; receiving DL indications from the network (e.g., MAC CE, DCI indications, broadcast signaling, and / or RRC(re)configuration); receiving a CHO configuration or command (e.g., a CHO configuration associated with a serving cell entering the NES state), the reception of a CHO configuration or command may be conditional on the NES cell being listed as a CHO candidate in the CHO configuration.

[0225] A WTRU may monitor (or decide to monitor) a configured NES cell based, for example, on the WTRU receiving N BFIs for a second cell within time T. T can be configured or determined based on a BFD timer value. N can be configured to be greater than or equal to 1. T can be configured arbitrarily. If T is not configured, it may not apply.

[0226] A WTRU may monitor (for example, decide to monitor) a configured NES cell based on the reception of DL indications from the network (e.g., MAC CE, DCI indications, broadcast signaling, and / or RRC(re)configuration). In some examples, a WTRU may initiate monitoring of an NES cell based on / at the reception of an RRC(re)configuration that includes the cell (e.g., part of a BFD cell to be monitored), or upon the reception of an indication from a second cell indicating the NES status of the NES cell. In some examples, a WTRU may initiate monitoring of an NES cell if it is indicated in (e.g., as part of) an L1 / 2 mobility command.

[0227] A WTRU may, for example, monitor (e.g., decide to monitor) a configured NES cell based on the reception of a CHO configuration or command (e.g., a CHO configuration associated with a serving cell entering the NES state), which may be conditional on the NES cell being listed as a CHO candidate in the CHO configuration. A CHO configuration may include separate measurement conditions (e.g., different things to measure or signals) associated with a given cell when the cell is in the active NES state. For example, a CHO configuration may provide / indicate a presync signal to measure for (one or more) associated CHO conditions.

[0228] As described herein, N, T, threshold 2, threshold 3A, etc., can be configuration parameters. The WTRU can receive and / or determine NES cell parameters from a presync signal. The WTRU can detect (e.g., receive) a presync signal from a first cell, e.g., an NES cell. The WTRU can be configured to detect (e.g., receive) one or more presync signals as part of an initial access procedure. The presync signal can be, for example, a discovery signal, an SSB signal, or a slimmed-down version of an SSB signal (e.g., PSS, SSS, or PSS+SSS). The periodicity of the presync signal can be (pre)defined or (pre)configured, for example, per frequency band, carrier, and / or BWP. The WTRU can capture the presync signal configuration (e.g., including periodicity) from, for example, an associated Ref-PCell, anchor carrier, and / or stable cell. The associated cell can provide a configuration part of its broadcast or dedicated signaling.

[0229] The WTRU may, for example, decide to process / monitor the pre-sync signal received from a first cell (for example, further) if, based on the measured channel conditions associated with the cell's pre-sync signal, pre-sync-ReceivedPower is greater than a first threshold. The WTRU may be configured or predefined with a measurement filtering window to apply to determine the channel measurement associated with the first cell. Thresholds may be known to the WTRU through preconfiguration. The WTRU may be (pre)defined with thresholds. In some examples, the WTRU may receive thresholds from the network (for example, in one of its last connections to the network) and / or from the configuration provided by the associated Ref-PCell.

[0230] The WTRU can determine the cell identification information of the first cell, such as PCI, from the received presync signal of the first cell. The WTRU can determine the beam index associated with the received presync signal of the first cell. The WTRU can determine the cell ID and / or beam index associated with the presync signal, for example, through one or more physical properties of the signal (e.g., time, frequency, sequence selection, phase, sequence ID, etc.).

[0231] WTRU may report (for example, decide to report) NES cell measurements. WTRU may, for example, one or more of the following conditions, namely pre-sync-ReceivedPower or discovery from the measured channel conditions of a first cell (e.g., a candidate non-serving NES cell) If the following conditions are met, the measurements made across the signals of the configured NES cell may be reported and / or the serving cell (e.g., the second cell) may report (e.g., decide to report) beam fault avoidance to the serving cell (e.g., the second cell): signal-ReceivedPower is greater than the first threshold (threshold 1); no SSBs are detected / received from the first cell and / or the first cell is determined to be in an NES state; one or more measured channel conditions (e.g., RSRP) of the second cell are greater than the threshold (e.g., threshold 2a) and / or less than the threshold (e.g., threshold 2B); the BFD counter on the second cell is greater than the threshold (e.g., threshold 3B); a beam fault is detected on the second cell; and / or one or more beams (e.g., all beams in the set) configured as part of the BFR_candidate_set are measured to be less than the threshold (e.g., threshold 4).

[0232] As described herein, threshold 1, threshold 2A, threshold 2B, threshold 3B, and threshold 4 may be configuration parameters.

[0233] In some cases, WTRU can perform measurements across other detected cells (e.g., NES cells) even if it is not configured as part of the beam obstruction avoidance procedure or the list of NES cells in the BFD configuration of the second cell.

[0234] A WTRU can report an NES cell. The WTRU can report to a second cell the identification information of the detected configured NES cell and the measurements related to the detected cell. The WTRU can trigger a report, for example, by multiplexing a beam obstruction avoidance MAC CE if an uplink grant is available (for example, if at least one of the triggers for reporting an NES cell, as described herein, is met). The WTRU can send the report as part of a beam obstruction avoidance MAC or RRC message (for example, if it decides to send it) if it has an UL grant available for the WTRU to send on the second cell. The WTRU can report a MAC CE (for example, only) after measuring at least one cell other than the second cell (for example, an NES cell or an astigmatic cell) that has a channel condition measurement above a configured threshold.

[0235] The beam fault avoidance MAC CE (for example, or RRC report as used interchangeably herein) may include at least one of the following: the cell index of the cell in which the channel measurement was performed above a threshold or in which a discovery or presync signal was detected; the logical channel (LCH) index corresponding to the fault report or the LCH associated with the fault report; the BWP index of the BWP in which the beam fault was detected; channel condition measurements of other detected cells (e.g., astable cells or NES cells), which may include RSRP, SINR, RSSI, etc.; and / or indices of one or more preferred beams, for example, beams that best satisfy (pre)configured or (pre)defined criteria, which may include RSRP, SINR, RSSI, and / or channel occupancy.

[0236] Measurements related to the detected cell may include, for example, the signal strength of the presync signal. In some examples, the measurement may include the RSRP of the RS transmitted as part of the presync signal.

[0237] A WTRU can transmit an SR or RA on a second cell to report beam fault avoidance. A WTRU can transmit an SR corresponding to an SR configuration configured to report beam fault avoidance. A WTRU can trigger a new SR or RA-SR when it does not have available (e.g., suitable) UL resources for transmitting a fault avoidance MAC CE. The suitability of available grants (e.g., for an SR triggered by fault avoidance) can be determined, for example, based on the RRC configuration that determines grant suitability, or based on the LCH assigned to the SR triggered by fault reporting. For example, a WTRU can be configured by an RRC with one or more (e.g., several) grant characteristics that consider (e.g., a particular) grant to be suitable for transmitting a fault avoidance MAC for (e.g., a particular) serving cell.

[0238] In some examples, a WTRU can be statically or semi-statically configured with priority, LCH, (one or more) SR configurations, and / or PUCCH resources for SRs triggered by fault avoidance reporting procedures. In some examples, an RRC can configure a WTRU with (e.g., several) (one or more) SR configurations (e.g., or more generally, a set of PUCCH resources) to be used for SRs triggered by fault reporting procedures. In some examples, a WTRU can be configured by an RRC with SR configurations per cell, BWP, or subband. In some examples, a WTRU can use (e.g., any) PUCCH resources configured on a cell to report SRs triggered by fault avoidance reporting. In some examples (e.g., in such cases), SRs triggered by fault reporting may have (e.g., a specific) priority (e.g., highest priority) compared to other SRs, HARQ / ACK feedback, and / or CSI reports that may be included in the PUCCH resources. In some examples, the priority of SRs triggered by fault reporting may be configurable.

[0239] A WTRU can be configured with static priorities or (for example, a specific) LCH, which the WTRU can use, for example, to determine which SR configuration to use among other possible uses, and / or to determine the priority of an SR. For example, an RRC can configure a WTRU with (for example, a specific) LCH to be associated with an SR triggered by a fault report, and / or the cell where a beam fault was detected. A WTRU can associate a priority with (for example, a specific) recovery SR, for example, when the priority overlaps with other UCIs, PUSCHs, or other transmissions, and / or when an action related to prioritization within the WTRU can be (for example, needs to be) taken.

[0240] A WTRU may, for example, monitor the PDCCH on a second cell following an SR or MAC CE fault avoidance transmission. A WTRU may, for example, monitor the PDCCH on a second cell index or another cell (for example, the indicated cell in the MAC CE) after receiving all SSBs from the indicated cell (for example, the first cell). A WTRU may consider a fault avoidance procedure to have been successfully completed after canceling an SR triggered by a fault avoidance report, and / or more generally, after sending a fault reporting MAC CE, receiving a response from a gNB from the second or first cell (for example, a PDCCH), receiving an uplink grant, receiving SSBs (for example, all SSBs) from the indicated cell (for example, the first cell), and / or receiving a network reconfiguration of parameters associated with the indicated cell or the second cell (for example, an RRC message).

[0241] A WTRU can receive an indication to perform RACH on an NES cell. For example, a WTRU may receive an indication from a second cell to perform RACH on an NES cell after sending a fault avoidance report. In some examples, a WTRU may receive an indication to perform RACH on an NES cell that it has reported identification information and / or configured measurements to a second cell, and / or the WTRU may receive an indication to start monitoring an SSB on a different cell (e.g., a first cell) indicated, along with synchronization timing parameters.

[0242] In some cases, a WTRU may receive an indication to perform RACH on a different NES cell than the one reported by the WTRU (for example, another NES cell selected by the network).

[0243] A WTRU may receive an indication to perform RACH on an NES cell via a PDCCH instruction, MAC signaling, or RRC message. The WTRU may have a dedicated preamble and / or RACH configuration associated with the indicated NES cell. Information (e.g., an indication to perform RACH, a dedicated preamble, and one or more RACH configurations) may be received from a second cell.

[0244] A WTRU can perform a RACH transmission on an NES cell. For example, when a WTRU receives an indication from a second cell to perform a RACH on a first cell, it can perform a RACH on the first cell or another indicated cell (for example, in response to a fault avoidance report).

[0245] The WTRU may, for example, monitor one or more SSBs on the first cell and / or another indicated cell (for example, in response to a fault avoidance report) if the WTRU receives an indication from a second cell (for example, in MAC CE or DCI, or in HARQ feedback for a MAC CE multiplexed transport block (TB)).

[0246] The WTRU may determine the RACH configuration and / or initial access parameters for the first cell based on, for example, one or more of the following: The WTRU may monitor one or more SSBs on the first cell if it receives an indication from the second cell (for example, in MAC CE or DCI, or in HARQ feedback for TB with multiplexed MAC CE). The WTRU may perform an RA on the first cell (for example, by sending a preamble using the received SIB1 configuration parameters) if an SSB and / or SIB-1 (for example, all SSBs with PBCH) is received on the first cell. The WTRU may perform an RA on the first cell (for example, by sending a preamble using the association from the SSB to the RO received from the second cell SIB-1) if an SSB is received on the first cell without SIB-1. A response to a fault avoidance report from the second cell may include an association between the SSB and the RO applicable to the first cell. The SSB may be of the first cell and / or the second cell. The WTRU may perform a handover to the first cell (e.g., a reconfiguration with synchronization) based on / upon receiving an indication from the first cell (e.g., in MsgB or Msg2 / 4) and / or satisfying one or more CHO conditions (e.g., a CHO condition based on channel measurements associated with the first cell and / or the second cell, based on the first cell changing its NES state, and / or based on receiving an NES-related CHO configuration associated with the first cell and / or the second cell).

[0247] A cross-cell BFD / RLM procedure can combine BFD / RLM signals (such as SSB and / or CSI-RS) from two or more cells, for example, a reference P-cell and another auxiliary NES cell or astable cell. The WTRU can be constructed using inter-cell associations (e.g., associations between stable and astable cells, NES cells and non-NES cells, and / or associations between a reference P-cell and a secondary cell). These associations can be used to perform the cross-cell BFD measurement.

[0248] WTRU can maintain separate or joint BFD / RLM parameters (e.g., counters and timers) (e.g., in cross-cell BFD). BFI can be generated, for example, if either cell generates a BFI, or if both cells generate a BFI. WTRU can increment BFI counters differently, for example, depending on the cell from which the BFI was received. WTRU can be composed of multiple (e.g., two) BFD counters / thresholds, such as a first counter for cell-referenced Pcells and a second counter for non-anchor NES cells. Different counters and thresholds can be used to determine the BFD procedure.

[0249] The WTRU can monitor BFD reference signals and / or SSBs from different cells (e.g., anchor cells or reference PCells) for a given non-anchored NES cell.

[0250] A WTRU can be configured or predefined with one or more (e.g., several) preconditions for when a WTRU combines BFD measurements for an NES cell with another cell (e.g., a Ref-PCell or anchor cell), the preconditions include at least one of the following: the cell is geolocated; the cell is correlated in terms of RF (e.g., so that measurement offsets can be added to be applicable to non-Ref-PCells); the cell is configured with common beam management; and / or the cell belongs to the same CU node or scheduler.

[0251] A presync or discovery signal transmitted from an NES cell (e.g., an astigmatic cell, a non-anchor cell, and / or a cell associated with a P-Ref cell) can be combined with other signals received from another associated cell (e.g., a BFD RS or SSB signal) and used for BFD measurements about the cell. In some examples, the WTRU may reset the BFD counter and / or stop the BFD timer for a given NES cell if the received discovery signal channel condition measurement exceeds a threshold (e.g., a threshold associated with Qin BFD, measured SINR, measured RSRP, or measured BLER), and the WTRU may increment the BFD counter in larger steps compared to other reference signals configured for BFD (e.g., those received from an anchor cell or associated P-Ref cell or associated stable cell) if the discovery signal is measured below a threshold, for example.

[0252] As described herein, a WTRU can perform beam fault avoidance by activating an NES cell. A WTRU can be connected to a second cell. A WTRU can monitor configured BFD signals (e.g., RA already successfully completed on the second cell). A WTRU can be configured with a set of NES cells to monitor, for example, whether / when beam fault avoidance is configured on the second cell. A WTRU can initiate monitoring of the NES cells for beam fault avoidance on the second cell if, for example, the BFD_counter on the second cell is greater than a third threshold (threshold 3A) and / or the RSRP of the second cell is less than a second threshold (threshold 2A). A WTRU can detect / receive presync (e.g., discovery) signals, such as a PSS+SSS signal from a first cell (e.g., an NES cell). A WTRU can identify the first cell transmitting this presync signal through one or more of the physical properties of the presync signal (e.g., time, frequency, sequence, phase, etc.). The WTRU may decide to send a beam hazard avoidance report (e.g., to the second cell) if at least one of the following is satisfied: pre-sync-ReceivedPower from the first cell is greater than the first threshold (threshold 1); no SSB is received from the first cell or the first cell is determined to be in an NES state; RSRP from the second cell (RSRP_from_second cell) is greater than the second threshold (threshold 2B); the beam hazard detection (BFD) counter on the second cell is greater than the third threshold (threshold 3B); and / or (one or more) BFR candidates in the BFR_candidate_set on the second cell are measured to be (e.g., all) below the threshold. The WTRU may send a beam hazard avoidance report (e.g., MAC CE) on the second cell if an uplink (UL) grant is available.The WTRU may, for example, transmit an SR on the second cell to report beam obstruction avoidance if it is not otherwise available (e.g., if a UL grant is not available). The beam obstruction avoidance report (e.g., MAC CE) may provide an indication of the physical cell identification information (PCI) of the first cell, along with the measured presync signal intensity. The WTRU may be configured with an SR configuration for reporting beam obstruction avoidance. The WTRU may receive an indication from the second cell that an RA should be performed on a different cell (e.g., on the first cell). If the WTRU receives an indication to perform an RA on the first cell, for example, it may perform one or more of the following: If the WTRU receives an indication from the second cell that the first cell is activated or will be activated, it may monitor one or more SSBs on the first cell. A WTRU can perform an RA on a first cell if, for example, an SSB and SIB-1 are received on the first cell (for example, by sending a preamble using the received SIB1 configuration). A WTRU can also perform an RA on a first cell if, for example, an SSB is received on the first cell without an SIB-1 (for example, by sending a preamble using the association from the SSB to the RO received from a second cell SIB-1).

[0253] Although the features and elements described above are described in specific combinations, each feature or element can be used alone or in various combinations with or without other features and elements in the preferred embodiment.

[0254] The implementation described here takes into account 3GPP-specific protocols, but it is not limited to this scenario and is applicable to other wireless systems. For example, the solutions described here take into account LTE, LTE-A, New Radio (NR), and 5G-specific protocols, but they are not limited to these scenarios and are similarly applicable to other wireless systems.

[0255] The processes described above are implemented in computer programs, software, and firmware embedded in computer-readable media for implementation by computers and / or processors. Examples of computer-readable media include, but are not limited to, electrical signals (transmitted over wired or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital multipurpose disks (DVDs). Software-related processors may be used to implement radio frequency transceivers for use in WTRUs, UEs, terminals, base stations, RNCs, or any host computer.

Claims

1. A wireless transceiver unit (WTRU), Receive a pre-synchronization signal (pre-sync signal), Based on the properties of the presync signal, a first cell that transmits the presync signal and a transmit beam index associated with the presync signal are determined. Determine whether a condition is met, and the condition is met based on at least one of the following: the received power associated with the presync signal is greater than a threshold; the full synchronous signal block (SSB) is not received from the first cell; or the first cell is in an energy-saving state. Based on the determination that the above conditions are met, the transmission from the second cell is received. Based on the transmission from the second cell and the presync signal, a random access channel configuration (RACH configuration) for the first cell is determined, the RACH configuration includes associating the presync signal with at least one physical RACH occasion (RO) associated with the first cell, the presync signal is associated with the first cell, Based on the presync signal and the RACH configuration for the first cell, the RO associated with the first cell and the preamble are determined. The preamble is transmitted on the RO associated with the first cell. Processor configured in such a way WTRU equipped with.

2. The WTRU of claim 1, wherein the presync signal includes at least one of a discovery signal, an SSB signal, a primary sync signal (PSS), a secondary sync signal (SSS), or a combination of a PSS and an SSS, and the SSB signal is not an all-SSB signal.

3. The WTRU of claim 1, wherein the property associated with the presync signal includes at least one of time, frequency, sequence selection, phase, and sequence identification (ID) associated with the presync signal.

4. The transmission from the second cell comprises at least one of an SSB or a System Information Block (SIB) in the WTRU of claim 1.

5. The transmission is associated with at least one SSB from the second cell, and the processor, The decision to receive the at least one SSB via the second cell is based on at least one of the following parameters: the same frequency at which the presync signal and the at least one SSB are received; different frequencies at which the presync signal and the at least one SSB are received; an indication associated with the presync signal; or parameters including at least one of time resources for receiving the at least one SSB, frequency resources for receiving the at least one SSB, a carrier frequency associated with the at least one SSB, or a cell ID associated with the at least one SSB. A further configured WTRU according to claim 1.

6. The WTRU of claim 1, wherein the RACH configuration includes at least one of the following: a system timing and a first cell ID associated with the first cell; an association of a transmit beam (TX beam) to the RO associated with the first cell; or a partition of the RACH preamble with the RO or the TX beam associated with accessing the first cell.

7. The aforementioned processor, The random access response (RAR) from the first cell is monitored during the RAR window. Determine whether the RAR mentioned above has been received. Based on the determination that the RAR has been received, the resources for sending the message are determined. Send the message on the resource. A further configured WTRU according to claim 1.

8. The aforementioned processor, Determine whether a fallback indication was received on the first cell during the RAR. Based on the decision that the fallback indication has been received, the RACH procedure is performed on the second cell. A WTRU according to claim 7, configured as follows.

9. The aforementioned preamble is a first preamble, and the processor is The RAR from the first cell is monitored during the RAR window. Determine whether the RAR mentioned above has been received. Based on the determination that the RAR was not received on the first cell, it is determined that at least one SSB was received from the first cell. Based on the determination that at least one SSB has been received from the first cell, a second preamble is transmitted on the RO associated with the first cell, and the RO used for transmitting the second preamble is further determined based on the measured SSB associated with the first cell. A WTRU according to claim 1, configured as follows.

10. The threshold is a first threshold, and the processor, Based on the determination that the RAR has not been received on the first cell, it is determined whether the number of retransmissions of the preamble exceeds a second threshold. Based on the determination that the number of retransmissions of the preamble exceeds the second threshold, the preamble is transmitted on the second cell. A WTRU according to claim 9, configured as follows.

11. The threshold is a first threshold, and the processor, It is determined that the reference signal received power (RSRP) associated with the second cell falls below a second threshold. Based on the determination that the RSRP falls below the second threshold, RACH transmission is performed on the first cell. A WTRU according to claim 1, configured as follows.

12. The steps include receiving a pre-synchronization signal (pre-sync signal) and A step of determining a first cell that transmits the presync signal and a transmit beam index associated with the presync signal, based on the properties of the presync signal. A step of determining whether a condition is met, wherein the condition is met based on at least one of the following: the received power associated with the presync signal is greater than a threshold; the full synchronous signal block (SSB) is not received from the first cell; or the first cell is in an energy-saving state. Based on the determination that the above conditions are met, the steps include receiving a transmission from the second cell, A step of determining a random access channel configuration (RACH configuration) for the first cell based on the transmission from the second cell and the presync signal, wherein the RACH configuration includes associating the presync signal with at least one physical RACH occasion (RO) associated with the first cell, and the presync signal is associated with the first cell. A step of determining the RO associated with the first cell and the preamble based on the presync signal and the RACH configuration for the first cell, The steps of transmitting the preamble on the RO associated with the first cell and A method for providing this.

13. The method of claim 12, wherein the presync signal includes at least one of a discovery signal, an SSB signal, a primary sync signal (PSS), a secondary sync signal (SSS), or a combination of a PSS and an SSS, and the SSB signal is not an all-SSB signal.

14. The method of claim 12, wherein the property associated with the presync signal includes at least one of time, frequency, sequence selection, phase, and sequence identification (ID) associated with the presync signal, and the transmission from the second cell includes at least one of an SSB or a system information block (SIB).

15. The transmission is associated with at least one SSB from the second cell, Steps to determine to receive the at least one SSB via the second cell based on at least one of the following parameters: the same frequency at which the presync signal and the at least one SSB are received; different frequencies at which the presync signal and the at least one SSB are received; an indication associated with the presync signal; or parameters including at least one of time resources for receiving the at least one SSB, frequency resources for receiving the at least one SSB, a carrier frequency associated with the at least one SSB, or a cell ID associated with the at least one SSB. The method of claim 12, further comprising the above.

16. The method of claim 12, wherein the RACH configuration comprises at least one of a system timing associated with the first cell, a first cell ID, an association of a transmit beam (TX beam) to the RO associated with the first cell, or a partition of the RACH preamble with the RO or the TX beam associated with accessing the first cell.

17. The steps include monitoring the random access response (RAR) from the first cell during the RAR window, The steps include determining whether the RAR has been received, Based on the decision that the RAR has been received, the steps include determining the resources for sending the message, The steps of sending the message on the resource and The method of claim 12, further comprising the above.

18. A step of determining whether a fallback indication was received on the first cell during the RAR, The steps include: performing the RACH procedure on the second cell based on the decision that the fallback indication has been received; The method of claim 17, comprising:

19. The aforementioned preamble is the first preamble, The steps include monitoring the RAR from the first cell during the RAR window, The steps include determining whether the RAR has been received, Based on the determination that the RAR was not received on the first cell, the step of determining that at least one SSB was received from the first cell, A step of transmitting a second preamble on the RO associated with the first cell, based on the determination that the SSB has been received from the first cell, wherein the RO used for transmitting the second preamble is determined further based on the measured SSB associated with the first cell. The method of claim 12, comprising:

20. The threshold is the first threshold, A step of determining whether the number of retransmissions of the preamble exceeds a second threshold, based on the determination that the RAR has not been received on the first cell, A step of transmitting the preamble on the second cell based on the determination that the number of retransmissions of the preamble exceeds the second threshold, The method of claim 19, comprising:

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