System and method for energy efficient operations with ca

Abstract

Devices, methods, and non-transitory computer-readable media are provided. An example method includes receiving, from a base station, a first signaling comprising a first configuration of a first synchronization signal and physical broadcast channel (PBCH) block (SSB) for a secondary serving cell (SCell) on a secondary component carrier, where the first configuration is based on a first identifier (ID) and indicates a first time offset, and wherein the first SSB is quasi co-located (QCLed) with a second SSB. The example method further includes receiving, from the base station, a medium access control (MAC) control element (CE) message, the MAC CE message indicating an activation command for the SCell, and the MAC CE message further indicating the first ID. The example method further includes receiving, from the base station, the first SSB for the SCell in accordance with the first time offset.

Description

SYSTEM AND METHOD FOR ENERGY EFFICIENT OPERATIONS WITH CACROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application Nos. 63 / 554,563, filed onFebruary 16, 2024, 63 / 574,594, filed on April 04, 2024, and 63 / 644,903, filed on May 09, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present invention relates generally to managing the allocation of resources in a network, and in particular embodiments, to techniques and mechanisms for network energy savings via energy efficient operations using on-demand, or otherwise aperiodic, signaling. BACKGROUND

[0003] Wireless communication systems include long term evolution (LTE), LTE-A, LTE-A- beyond systems, 5G LTE, 5G New Radio (NR), and the like. A modern wireless communication system may include a plurality of NodeBs (NBs), which may also be referred to as base stations, network nodes, communications controllers, cells, or enhanced NBs (eNBs), and so on. A NodeB may include one or more network points or network nodes using different radio access technologies (RATs) such as high speed packet access (HSPA) NBs or WiFi access points. A NodeB may be associated with a single network point or multiple network points. A cell may include a single network point or multiple network points, and each network point may have a single antenna or multiple antennas. A network point may correspond to multiple cells operating in multiple component carriers. Generally, each component carrier in carrier aggregation is a serving cell, either a primary cell (PCell) or a secondary cell (SCell).

[0004] A cell or NodeB may serve a number of users (also commonly referred to as User Equipment (UE), mobile stations, terminals, devices, and so forth) over a period of time. A communication channel from a NB to a UE is generally referred to as a downlink (DL) channel, and a transmission from the NB to the UE is a downlink transmission. A communication channel from a UE to a NB is generally referred to an uplink (UL) channel, and a transmission from the UE to the NB is an uplink transmission.

[0005] It is widely observed that SCell activation in the current new radio (NR) systems is too slow7(the SCell activation latency generally in the range of tens to hundreds of milliseconds). In many cases, the SCell activation latency in the current NR systems is even longer than that of the LTE systems. So, it is desirable to improve the SCell activation latency for the NR systems and beyond.

[0006] The downlink (DL) waveform in 5G NR is conventional OFDM using a Cyclic Prefix (CP), while the uplink (UL) is conventional OFDM using a CP with a transform precoding function performing Discrete Fourier Transform (DFT) spreading. Downlink and uplinktransmissions are organized into frames w ith to ms duration, consisting of ten 1 ms subframes. Each frame is divided into two equally sized half-frames of five subframes each. The slot duration is 14 symbols with Normal CP and 12 symbols with Extended CP, and scales in time as a function of the used sub-carrier spacing so that there is always an integer number of slots in a subframe.

[0007] For a receiver in the UE to be able to demodulate a DL transmission, it should be synchronized with the gNB (e.g., a transmitter). Therefore, a UE should synchronize with the gNB numerology (frame, slots, and symbols). The synchronization is achieved in 5G NR via acquiring by a UE of the Synchronization Signal Block (SSB) (e.g., a PBCH block).SUMMARY OF THE INVENTION

[0008] Technical advantages are generally achieved, by embodiments of this disclosure that describe techniques and mechanisms for network energy savings via energy efficient network operations using on-demand, or otherwise aperiodic, signaling.

[0009] In accordance with an embodiment, a method for energy efficient network operation is provided. An example method includes receiving, by a user equipment (UE) from a base station, a first signaling including a first configuration of a first synchronization signal and PBCH block (SSB) for a secondary serving cell (SCell) on a secondary component carrier. The first configuration is based on a first identifier (ID) and indicates a first time offset, and wherein the first SSB is quasi co-located (QCLed) with a second SSB. The example method further includes receiving, by the UE from the base station, a medium access control (MAC) control element (CE) message. The MAC CE message indicating an activation command for the SCell, and the MAC CE message further indicating the first ID. The example method further includes receiving, by the UE from the base station, the first SSB for the SCell in accordance with the first time offset.

[0010] In accordance with another aspect of an embodiment, in some embodiments the example method further includes activating, by the UE, the SCell after the UE transmits a channel state information (CSI) report for the SCell, while the SCell is deactivated for the UE and before the receiving the MAC CE message. The activation command for the SCell is in a field of the MAC CE message, and the activation command initiates a SCell activation procedure. The example method further includes transmitting, by the UE to the base station, a valid CSI report indicating completion of the SCell activation procedure.

[0011] In accordance with another aspect of an embodiment, in some embodiments the example method further includes performing, by the UE, an active period procedure on the SCell upon the receiving of the first SSB, while the SCell for the UE is activated and in cell discontinuous transmission (DTX), and before the receiving of the MAC CE message the activation command initiating an active period. The activate period procedure includes, for theSCell: at least one radio frequency (RF) operation, an automatic gain control (AGC) procedure, a synchronization procedure or re-synchronization procedure, or an SSB-based measurement.

[0012] In accordance w ith another aspect of an embodiment, in some embodiments the first SSB is received before a corresponding aperiodic tracking reference signal (TRS) for the SCell.

[0013] In accordance w ith another aspect of an embodiment, in some embodiments the first SSB corresponds to an on-demand SSB for the SCell.

[0014] In accordance w ith another aspect of an embodiment, in some embodiments the first SSB corresponds to a non-cell defining SSB.

[0015] In accordance with another aspect of an embodiment, in some embodiments the first SSB is placed on a non-synchronization raster associated with the SCell.

[0016] In accordance with another aspect of an embodiment, in some embodiments the example method further includes the second SSB is a cell -defining (CD) SSB and is always on for the SCell, and a transmission of the second SSB is received before receiving the MAC CE message.

[0017] In accordance with another aspect of an embodiment, in some embodiments a signal or channel is configured as being QCLed with the second SSB, and is assumed to be QCLed with the first SSB.

[0018] In accordance with another aspect of an embodiment, in some embodiments, a signal or a channel is configured as being QCLed with the first SSB, and is assumed to be QCLed with the second SSB.

[0019] In accordance with another aspect of an embodiment, in some embodiments the example method further includes receiving, by the UE from the base station, a downlink control information (DCI) message. The DCI message indicates the activation command for the SCell, and the DCI message indicates the first ID.

[0020] In accordance with another aspect of an embodiment, in some embodiments the example method further includes activating, by the UE, the SCell after the UE transmits the valid CSI report for the SCell, while the SCell is deactivated for the UE and before the receiving the DCI message. The activation command for the SCell is in a field of the DCI message.

[0021] In accordance with another aspect of an embodiment, in some embodiments the example method further includes performing, by the UE, the active period procedure on the SCell upon the receiving of the first SSB, while the SCell for the UE is activated and in cell DTX, and before the receiving of the DCI message. The activation command for the SCell is in a DCI field of the DCI message.

[0022] In accordance with another aspect of an embodiment, in some embodiments the first signaling indicates to the UE that N on-demand bursts of the first SSB are transmitted via the SCell. N is greater than or equal to 1.

[0023] In accordance w ith another aspect of an embodiment, in some embodiments the first offset is associated w ith a delay between slot (n+k) and a first on-demand burst of the first SSB, wherein slot n denotes an ending slot of the MAC CE message, and where the slot (n+k) denotes one slot after decoding and processing of the MAC CE message.

[0024] In accordance with another aspect of an embodiment, in some embodiments the first SSB is received between periodic transmissions of a periodic duty cycle associated with a second SSB.

[0025] In accordance with another aspect of an embodiment, in some embodiments the example method further includes, after activation of the SCell, receiving, by the UE, a periodic signal from the SCell.

[0026] In accordance with another aspect of an embodiment, in some embodiments the first SSB includes a primary' synchronization signal (PSS) and a secondary' synchronization signal (SSS).

[0027] In accordance with yet another embodiment, an apparatus for energy efficient network operation is provided. An example apparatus includes at least one processor. The example apparatus further includes at least one non-transitory computer-readable storage medium having programming. The programming includes instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any one of the example methods described herein.

[0028] In accordance with yet another embodiment, a non-transitory' computer-readable medium having instructions stored thereon. The instructions, when executed by a user equipment (UE), cause the UE to perform a method according to any one of the example methods described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0030] FIG. 1A illustrates an example wireless communications system.

[0031] FIG. 1B illustrates a use of carrier aggregation (CA).

[0032] FIG. 2A illustrates channels and / or signals in which SS bursts are multiplexed with PBCH around the SS bursts.

[0033] FIG. 2B illustrates channels and / or signals in which such channels and / or signals are multiplexed for multiple UEs.

[0034] FIG. 3A illustrates a diagram showing QCL assumptions among NR reference signals when wide beams are used for communication.

[0035] FIG. 3B illustrates a diagram showing QCL assumptions among NR reference signals when narrow beams are used for communication.

[0036] FIG. 4 illustrates an example 5G NR Rel-15 and / or Rel-16 SCell activation timeline.

[0037] FIG. 5 illustrates an example flow of UE operations of Rel-15 SCell activation.

[0038] FIG. 6 illustrates an example flow of UE operations of Rel-17 SCell activation based on AP TRS.

[0039] FIG. 7 illustrates an example flow of UE operations of Rel-19 SCell activation based on AP SSB.

[0040] FIG. 8 illustrates a timeline of UE operations in the Rel-19 SCell activation based on AP SSB.

[0041] FI G. 9 illustrates an example flow of UE operations of Rel-19 dormancy and / or cellDTX.

[0042] FIG. 10 illustrates an example flow of UE operations of Rel-19 cell DTX on-demand active period where DL DCI-WUS is used.

[0043] FIG. 11 illustrates an example communication system.

[0044] FIG. 12A illustrates an example edge device that may implement at least some of the methods of the disclosure.

[0045] FIG. 12B illustrates an example base station that may implement at least some of the methods of the disclosure.

[0046] FIG. 13 illustrates an example base station that may implement at least some of the methods of the disclosure.

[0047] FIG. 14 illustrates an example triggering procedure and timeline.

[0048] FIG. 15 illustrates a time-frequency structure of an example SSB.

[0049] FIG. 16 illustrates an example SSB case for an example SCS of 15kHz.

[0050] FIG. 17 illustrates an example SSB time distribution.

[0051] FIG. 18 illustrates a an example flow of UE operations of legacy dormancy and / or cell DTX.

[0052] FIG. 19 illustrates an example SCell status in accordance with embodiments of the present disclosure.

[0053] FIG. 20 illustrates an SCell fast activation with aperiodic SSB for a particular scenario.

[0054] FIG. 21 illustrates an example flow of UE operations of Rel-19 deactivation SCell with AP SSB.

[0055] FIG. 22 illustrates an example flow of other UE operations of Rel-19 deactivation SCell with AP SSB.

[0056] FIG. 23 illustrates an example PRACH resource distribution, including legacy and additional NES-PRACH resources.

[0057] FIG. 24 illustrates a table depicting a summary of elements in various scenarios in accordance with embodiments of the present disclosure.

[0058] FIG. 25 illustrates a flowchart depicting example operations of a method in accordance with some embodiments of the present disclosure.

[0059] FIG. 26 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure.

[0060] FIG. 27 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure.

[0061] FIG. 28 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure.

[0062] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0063] The making and using of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.Overall System Description

[0064] FIG. 1A illustrates an example wireless communication system too. Communication system too includes a base station 110 with coverage area 101. The base station 110 senes a plurality of user equipments (UEs), including UEs 120. Transmissions from the base station 110 to a UE is referred to as a dow nlink (DL) transmission and occurs over a dow nlink channel (shown in FIG. 1A as a solid arrowed line 135), while transmissions from a UE to the base station no is referred to as an uplink (UL) transmission and occurs over an uplink channel (shown in FIG. 1A as a dashed arrowed line 130). Data carried over the uplink and / or downlink connections may include data communicated between the UEs 120, as well as data communicated to / from a remote-end (not shown) by way of a backhaul network 115. Example downlink channels and signals include synchronization signal (SS) blocks, also called SS and / or physical broadcast channel (PBCH) block SS / PBCH block (SSB), physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), channel state information reference signal (CSI-RS) which includes tracking RS (TRS, aka CSI-RS fortracking), and the like. Example uplink channels and signals include physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), an uplink sounding reference signal (SRS), or physical random access channel (PRACH). The transmissions may be periodic, semi-persistent, or aperiodic. For example, P TRS stands for periodic TRS, AP TRS stands for aperiodic TRS, SP CSI-RS stands for semi-persistent CSI-RS, P SSB / SP SSB / AP SSB stand for periodic / semi-persistent / aperiodic SSB, and so on. Services may be provided to the plurality of UEs by service providers connected to the base station 110 through the backhaul network 115, such as the Internet. The wireless communication system too may include multiple distributed access nodes 110.

[0065] In a typical communication system, there are several operating modes. In a cellular operating mode, communications to and from the plurality of UEs go through the base station no, while in device to device communications mode, such as proximity services (ProSe) operating mode, for example, direct communication between UEs is possible. As used herein, the term “base station” refers to any component (or collection of components) configured to provide wireless access to a network. Base stations may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary' gNBs (SgNBs), network controllers, control nodes,access nodes, access points (Aps), transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, relays, customer premises equipment (CPE), the network side, the network, and so on. In the present disclosure, the terms “base station” and “TRP” are used interchangeably unless otherwise specified. As used herein, the term “UE” refers to any component (or collection of components) capable of establishing a wireless connection with a base station. UEs may also be commonly referred to as mobile stations, mobile devices, mobiles, terminals, user terminals, users, subscribers, stations, communication devices, CPEs, relays, Integrated Access and Backhaul (IAB) relays, and the like. When relaying is used (based on relays, picos, CPEs, and so on), especially multi-hop relaying, the boundaiy between a controller and a node controlled by the controller may become bluriy, and a dual node (e.g., either the controller or the node controlled by the controller) deployment where a first node that provides configuration or control information to a second node is considered to be the controller. Likewise, the concept of UL and DL transmissions can be extended as well.

[0066] A cell may include one or more bandwidth parts (BWPs) for UL or DL allocated for a UE. Each BWP may have its own BWP-specific numerology and configuration, such as the BWP’s bandwidth. Not all BWPs need to be active at the same time for the UE. A cell may correspond to one carrier, and in some cases, multiple carriers. Typically, one cell (e.g., a primary cell (Pcell or PCell) or a secondary cell (SCell or SCell), for example) is a component carrier (e.g., a primary7component carrier (PCC) or a secondary CC (SCC), for example). For some cells, each cell may include multiple carriers in UL, one carrier may be referred to as an UL carrier or non- supplementary UL (non-SUL, or simply UL) carrier which has an associated DL, and other carriers are called supplementary UL (SUL) carriers which do not have an associated DL. A cell, or a carrier, may be configured with slot or subframe formats comprising DL and UL symbols, and that cell or carrier may be seen as operating in a time division duplexed (TDD) mode. In general, for unpaired spectrum, the cells or carriers are in TDD mode, and for paired spectrum, the cells or carrier are in a frequency division duplexed (FDD) mode. A transmission time interval (TTI) generally corresponds to a subframe (in LTE) or a slot (in NR). Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., long term evolution (LTE), LTE advanced (LTE-A), 5G, 5G LTE, 5G NR, future 5G NR releases, 6G, High Speed Packet Access (HSPA), Wi-Fi 802.na / b / g / n / ac, and the like. While it is understood that communication systems may employ multiple access nodes (or base stations) capable of communicating with a number of UEs, only one access node, and two UEs are illustrated in FIG. 1 for simplicity.

[0067] A way to increase the network resources is to utilize more usable spectrum resources, which include not only the licensed spectrum resources of the same type as the macro, but also the licensed spectrum resources of different type as the macro (e.g., the macro is an FDD cell but a small cell may use both FDD and TDD carriers), as well as unlicensed spectrum resources andshared-licensed spectrums. Some of the spectrum resources lie in high-frequency bands, such as 6GHz to 6oGHz. The unlicensed spectrums may be used by generally any user, subject to regulatory requirements. The shared-licensed spectrums are also not exclusive for an operator to use. Traditionally, the unlicensed spectrums are not used by cellular networks because it is generally difficult to ensure quality of sendee (QoS) requirements. Operating on the unlicensed spectrums mainly includes wireless local area networks (WLAN), e.g., the Wi-Fi networks. Due to the fact that the licensed spectrum is generally scarce and expensive, utilizing the unlicensed spectrum by the cellular operator may be considered. On high-frequency bands and unlicensed and / or shared-licensed bands, typically TDD is used and hence the channel reciprocity can be exploited for the communications.

[0068] In a realistic deployment, a gNB may control one or more cells. Multiple remote radio units may be connected to the same base band unit of the gNB by fiber cable, and the latency between base band unit and remote radio unit is quite small. Therefore, the same base band unit can process the coordinated transmission and / or reception of multiple cells. For example, the gNB may coordinate the transmissions of multiple cells to a UE, which is called coordinated multiple point (CoMP) or multi-TRP (mTRP, M-TRP) transmission. The gNB may also coordinate the reception of multiple cells from a UE, which is called CoMP / M-TRP reception. In this case, the backhaul link between these cells with the same gNB is fast backhaul and the scheduling of data transmitted in different cells for the UE can be easily coordinated in the same gNB. The backhaul connections may also be ones with longer latency and lower transmission rates.

[0069] FIG. 1B illustrates the use of carrier aggregation (CA), which is another deployment strategy. As shown in FIG. 1B, system 150 is a typical wireless network configured with carrier aggregation (CA) where communications controller 160 communicates to wireless device 165 using wireless link 170 (e.g., the solid line) and to wireless device 166 using wireless link 172 (e.g., the dashed line) and using wireless link 170, respectively. In some example deployments, for wireless device 166, wireless link 170 can be called a primary component carrier (PCC) while wireless link 172 can be called a secondary component carrier (SCC). In some carrier aggregation deployments, the PCC can carry control signaling and data between a UE device and a communications controller while the SCC can mainly carry data traffic. In the 3GPP specifications, a component carrier is called a cell. When multiple cells are controlled by a same eNB, cross scheduling of multiple cells can be implemented because there may be a single scheduler in the same eNB to schedule the multiple cells. With CA, one eNB may operate and control several component carriers forming primary cell (Pcell) and secondary cell (SCell).

[0070] Physical layer channels and signals include PSS / SSS, PBCH and its associated DMRS (see e.g., FIG. 2A, in which the SS bursts are multiplexed with PBCH around the SS bursts), PDSCH and its associated DMRS and phase tracking reference signal (PT-RS), PDCCH and its associated DMRS (see e.g., FIG. 2B for some of these signals and / or channels which aremultiplexed for more than one UE), and CSI-RS which further include those used, for CSI acquisition, for beam management, and for tracking (e.g., in some examples of non-zero power (NZP) CSI-RS used for channel estimation, interference measurement, and so on, which are multiplexed with PDSCH and for one or more UEs). The CSI-RS for tracking is also called TRS.

[0071] The UE receives timing advance (TA) commands associated with the configured TA group (TAG) to adjust its uplink transmission timing to synchronize with the network for uplink transmission so that uplink transmissions from multiple UEs arrive at the base station at about the same time in a transmission time interval (TTI). Likewise, the UE receives DL reference signals (RS) or synchronization signal (SS) blocks, also called SS / physical broadcast channel (PBCH) block SS / PBCH block (SSB) to acquire and maintain the DL synchronization, such as via maintaining a DL timing tracking loop, based on which the UE places the start of its FFT window^ inside the cyclic prefix (CP) for its DL reception. In addition, both UL and DL signals and / or channels are to be associated with some other signals for deriving the signal and / or channel properties, such as delay spread, Doppler shift, and the like.

[0072] In wireless communications operations, tracking functionalities performed by a UE may include fine time tracking, fine frequency tracking, delay spread estimation, and Doppler spread estimation.

[0073] In fine time tracking, a UE may detect the first arriving path, and based thereon, the UE may generally optimally place its Fast Fourier transform (FFT) window to maximize a data signal to noise plus inter-symbol interference ratio. In a continuous operation, an FFT windowposition may drift due to UE mobility and a residual oscillator error betw een a transmitter and a receiver. The UE may adjust its FFT window position based on a detected change of path arriving (or arrival) time.

[0074] In fine frequency tracking, a UE may detect a frequency offset between a transmitter and a receiver, and adjust its oscillator accordingly. A residual frequency error may be estimated and compensated in the demodulation of data symbols. The residual frequency error compensation may be very- critical, especially in the case of high signal-to-noise ratio (SNR) and high code rate data transmissions. Uncompensated frequency error may impose phase error on modulated data symbols and result in decoding performance degradation. Because temperature change affects output precision of an oscillator and Doppler shift caused by UE movement, a UE may periodically track the frequency offset and apply corresponding adjustment and compensation.

[0075] Delay spread determines how dispersive a wireless multi-path channel that a UE experiences is. The longer the delay spread, the more frequency selective the channel is. To generally maximize processing gains along the frequency domain in channel estimation based on received pilot signals, the UE may apply linear filtering with a length as long as possible if within the coherent bandwidth of the channel. Coherent bandwidth is inversely proportion to channelselectiveness. Thus, delay spread estimation plays an important role in forming channel estimation filter coefficients and length, hence affecting the performance of channel estimation and data demodulation.

[0076] Doppler spread is usually proportional to UE movement speeds and multi-path spatial distribution. Larger Doppler spread corresponds to a faster changing wireless multi-path fading channel. Channel estimation usually applies filtering in the time domain with longer filter length to suppress noise plus interference if within the channel coherent time constraint. Doppler spread estimation is thus another factor along the time domain affecting UE channel estimation performance.

[0077] The quasi co-location (QCL) types corresponding to each DL RS (more specifically, the port(s) or antenna port(s) of the DL RS) are given by the higher layer parameter qcl-Type in QCL-Info and may take one of the following values: 1) ‘QCL-TypeA’: {Doppler shift, Doppler spread, average delay, delay spread}; 2) ‘QCL-TypeB’: {Doppler shift, Doppler spread}; 3) ‘QCL- TypeC’: {Doppler shift, average delay}; and 4) ‘QCL-TypeD‘: {Spatial Rx parameter}. The QCL types may be configured and / or indicated in transmission configuration indication (TCI) states for a RS. The QCL assumptions are mainly used for DL RS, but can be generalized for UL RS if the association via pathloss RS and spatial relation are specified. The QCL assumption may be specified as: {RSi: QCL Type C to RS2}, {RSi: QCL Type C to RS2 and QCL Type D to RS3}. Then, RSi (e.g., destination RS) derives the properties specified according to the QCL types from the associated (e.g., source) RSs (e.g., RS2). The source RS may be an SSB. The source RS and destination RS may be on the same carrier or different carriers (e.g., cross-carrier QCL).

[0078] FIG. 3A is a diagram 300 showing QCL assumptions among NR reference signals when wide beams are used for communications. For example, a TRS, a SS block or a broadcast DMRS may be transmitted using a wide beam. FIG. 3A shows QCL configurations among a SS block 302, a DMRS 304, a CSI-RS 306, a TRS 308, a CSI-RS 310 and a DMRS 312. The DMRS 304 is for a broadcast channel. That is, the DMRS 304 is a DMRS used for demodulation of a system information block (SIB), radio resource control (RRC) signaling, paging, and the like, before a TRS is configured. The CSI-RS 306 is transmitted for beam forming. The CSI-RS 310 is transmited for channel estimation. The DMRS 312 is used for demodulation of signals transmited in a unicast channel. An arrow starting from a first reference signal (e.g., the SS block 302) and ending at a second reference signal (e.g., the DMRS 304) indicates that the second reference signal has a QCL relationship with the first reference signal with respect to one or more QCL parameters. The one or more QCL parameters (e.g., an average delay, a Doppler shift, a delay spread, and a spatial RX) are shown on the arrow, indicating that the one or more QCL parameters required by the second reference signal may be derived using the first reference signal.

[0079] As shown, the DMRS 304 is configured to have a QCL relationship with the SS block 302. The average delay, Doppler shift, delay spread, and spatial RX for the DMRS 304 may bederived based on the SS block 302. Similarly, the CSI-RS 306 and the TRS 308 has a QCL relationship with the SS block 302, respectively. An average delay, a Doppler shift, and a coarse spatial RX required by the CSI-RS 306 may be derived based on the SS block 302. An average delay, a Doppler shift, and a spatial RX required by the TRS 308 may be derived from the SS block 302. The CSI-RS 310 has a QCL relationship w ith the CSI-RS 306 and the TRS 308, respectively. The CSI-RS 310 may be received using a spatial RX derived based on the CSI-RS 306, and use an average delay, a Doppler shift, and a delay spread from the TRS 308. The DMRS 312 has a QCL relationship with the TRS 308 and the CSI-RS 310, respectively. The DMRS 312 may be received using a spatial RX derived based on the CSI-RS 310. The DMRS 312 may also be received an average delay, a Doppler shift, a Doppler spread and a delay spread derived based on the TRS 308.

[0080] FIG. 3B is a diagram 350 show ing QCL assumptions among NR reference signals when narrow beams are used for communications. FIG. 3B shows QCL configurations among a SS block 352, a DMRS 354, a CSI-RS 356, a TRS 358, a CSI-RS 360 and a DMRS 362. Similar to FIG. 3A, the DMRS 354 is for demodulation of signals in a broadcast channel, e.g., a physical broadcast channel (PBCH), that is transmitted before a TRS is configured. The CSI-RS 356 is transmitted for beam forming. The CSI-RS 360 is transmitted for channel estimation. The DMRS 362 is used for demodulation of signals transmitted in a unicast channel. An arrow starting from a first reference signal and ending at a second reference signal indicates that the second reference signal has a QCL relationship with the first reference signal with respect to one or more QCL parameters. The one or more QCL parameters shown on the arrow indicate that the one or more QCL parameters required by the second reference signal may be derived using the first reference signal. FIG. 3B shows that the reference signals have QCL configurations similar to those illustrated in FIG. 3A, except for TRSs. In FIG. 3B, the TRS 358 has a QCL relationship with the SS block 352 and the CSI-RS 356, respectively. The TRS 358 may be received using a Doppler shift derived based on the SS block 352, and may be received using an average delay and a spatial RX derived based on the CSI-RS 356. Data transmission may employ multiple narrow beams, and multiple narrow TRS beams may be required for tracking. To support both of the scenarios, configuration of TRSs and their QCL assumptions or associations should be flexible. In some embodiments, TRS (e.g., an AP TRS) is received after a first SSB, for example such that the first SSB is received before the corresponding AP TRS is received.SSB

[0081] The SSB consists of primaiy (PSS) and secondary (SSS) synchronization signals each occupying 1 symbol and 127 subcarriers, and PBCH (Physical Broadcast Channel) spanning across 3 OFDM symbols and 240 subcarriers, but on one symbol leaving an unused part in the middle for SSS, as shown in FIG. 15, for example w here FIG. 15 depicts a time-frequency structure of an example SSB. For the 3 MHz channel bandwidth, the PBCH is further equally puncturedfrom both edges to span 144 subcarriers. The possible time locations of SSBs within a half-frame are determined by sub-carrier spacing and the periodicity of the half-frames where SSBs are transmitted is configured by the network. During a half-frame, different SSBs may be transmitted in different spatial directions (e.g., using different beams, spanning the coverage area of a cell).

[0082] When an SSB is associated w ith a Remaining Minimum System Information (RMSI) signaling, the SSB is referred to as a Cell- Defining SSB (CD-SSB). A Pcell (Primary Cell) is always associated to a CD-SSB located on the sy nchronization raster. When an SSB is not associated with an RMSI, the SSB is referred to as a non-Cell Defining SSB (NCD-SSB), which can be used to perform RLM, BFD, and RRM measurements and measurements for RA resource selection inside the active DL BWP when the active BWP does not contain the CD-SSB.

[0083] The PBCH carries Master Information Block (MIB) information, which provides the UE with parameters (e.g., CORESET#o configuration) for monitoring of PDCCH for scheduling PDSCH that carries the System Information Block 1 (SIB1). PBCH may also indicate that there is no associated SIBt (e.g., via ssb-SubcarrierOffset field), in which case the UE may be pointed to another frequency from where to search for an SSB that is associated with a SIBt as well as a frequency range where the UE may assume no SSB associated with SIBt is present. In addition, the MIB carries cellBarred data field, which is used by UEs to decide whether to select this cell or reselect another cell.

[0084] Upon receiving SIBt a UE obtains some other system information (such as frequency Band List, tracking Ar aCode, tracking AreaList, servingCellConfigCommon, and the like.). Other information like cellBarredNES indicates that cell is allowed for UE supporting NES cell DTX / DRX. ServingCellConfigCommon carries information about the physical Cell ID, downlink configuration common, uplink configuration common, SSB position in a burst, SSB periodicity, and the like).

[0085] SIBt may also include si-Schedulmglnfo containing si-RequestConfig, which may be used to initiate the Random Access procedure on normal uplink in accordance with TS 38.321 using the PRACH preamble(s) and PRACH resource(s) in si-RequestConfig corresponding to the SI message(s) that the UE requires to operate within the cell, and for which si-BroadcastStatus is set to notBroadcastmg. Thus, a UE may request the system information corresponding to SIBx, where x=2, 3 ,..,19.

[0086] The gNB may provide the requested SI corresponding to SIB2-SIB19 in multiple ways depending on the UE RRC state.

[0087] For UE in RRC CONNECTED state, gNB may provide SI using DCI Format i_o with a CRC scrambled with SI-RNTI (e.g., identification of Broadcast and System Information in the downlink). This PDCCH message contains the field System information indicator that indicates whether the system message carried by PDSCH and signaled by this DCI corresponds to SIBt or other SIBx. The DCI t_o scrambled with SI-RNTI also indicates the time, frequency, MCS for thePDSCH that carries SIB information. In addition, it has at least 15 reserved bits.

[0088] For UEs in RRC INACTIVE or IDLE state, the gNB may provide information via paging. A Short Message (8 bits) may be carried in DCI Format 1_O with CRC scrambled by P- RNTI (e.g., identification of paging and system information change notification in the downlink). Repetitions of SI change indication may occur within preceding modification period or within preceding eDRX acquisition period. SI change indication is not applicable for SI messages containing posSIBs.

[0089] Cell Defining SSB (e.g., an SSB with an RMSI associated information) provides or is used for cell selection, and / or re-selection, and initial access with synchronization in time and frequency, frame timing, PCI, SFN, SCS, initial BWP, CORESET# 0 information, SIB1 related information, cell barring status, PRACH occasions, downlink CSI EPRE and RRM measurements (e.g., including signal strength, QCL related information).

[0090] PSS together with SSS provides cell ID, and symbol synchronization. PBCH via MIB’s associated DMRS provides the LSB of the SSB index (e.g., via DMRS sequence and respectively PBCH payload). The SSB index is used for RRM, CSI-RS measurements to assess link quality, and for the link recovery procedures.

[0091] In the case when SSB is not associated with an RMSI, PBCH indicates that there is no associated SIBi, in which case the UE may be pointed to another frequency from where to search for an SSB that is associated with a SIBi as well as a frequency range where the UE may assume no SSB associated with SIBi is present.

[0092] As specified in TS 38.213, Clause 4.1, for a half frame with SS / PBCH blocks, the first symbol indexes for candidate SS / PBCH blocks are determined according to the SCS of SS / PBCH blocks, where index 0 corresponds to the first symbol of the first slot in a half-frame.

[0093] For instance, for 15kHz SCS there are 4 SSB transmissions in a half-frame for carrier frequencies smaller than or equal to 3 GHz (e.g., symbol indexes of {2,8} + 14 • n, n = 0,1), and 8 SSB transmissions (n = 0,1, 2, 3) for carrier frequencies larger than 3GHz, as shown in FIG. 16, for depicting an example SSB time distribution.

[0094] For the initial cell selection, a UE may assume that half frames with SS / PBCH blocks occur with a periodicity of 2 frames. Thus, the SSB burst is confined in a 5ms window with a typical periodicity of 20ms, as shown in FIG. 17, for example depicting an SSB time distribution with a 20ms periodicity and SSB burst within 5ms, which can be increased up to 160ms.

[0095] A UE can be provided a periodicity of the half frames for reception of the SS / PBCH blocks for the serving cell per serving cell by ssb-periodicityServingCell as a part of the IE servingCellConfigCommon. The IE contains parameters which a UE would typically acquire from SSB, MIB or SIBs when accessing the cell from RRC IDLE state.SIBi

[0096] System Information (SI) is the information delivered to the UE and which is necessaryfor the UE to operate. SI can be delivered via broadcast and unicast, and it can be divided into three types of information: MIB, SIB1 and Other SI.

[0097] MIB (Master Information Block) contains basic cell configuration and information necessary to acquire SIB1.

[0098] SIBt (System Information Block 1) contains information about other SI available in the cell (e.g., Remaining Minimum SI— RMSI), information necessaiy for UE to decide whether it may access the cell, and information required to perform mobility procedures in RRC IDLE mode (e.g., cell physical layer configuration), including random access related configuration as well as indication of the transmitted SS / PBCH blocks (SSB). In order to enable UE to monitor for the PDCCH scheduling PDSCH cariying SIBt, MIB provides the necessaiy configuration (pdcch- ConfigSIBi) and the numerology of the broadcast (subCarrierSpacing Common). Search space defining the time domain for PDCCH monitoring is provided by pdcch-ConfigSIBi.

[0099] The search space configuration for PDCCH monitoring occasions for SIBt scheduling provided by MIB is called Typeo-PDCCH Common search space (CSS), the CORESET determining the physical resources of the PDCCH scheduling SIBt is called Typeo-PDCCH CORESET.

[0100] There are additional SIBs (e.g., from SIB2 onwards) can be delivered through broadcast or “on-demand” manner. The procedure “on-demand” triggers the network to initiate the broadcast of requested System Information messages. The UE is configured with a SI window, where UE can monitor the PDCCH scheduling the SI message. For each entry of the SI message list schedulinglnfoLisf), there a time window duration (si-WindowLength) that occurs with a configured periodicity (si-Periodicity).PRACH

[0101] Random access preambles can only be transmitted in the time resources obtained from Tables 6.3-3.2-2 to 6.3-3.2-4 of TS 38.211 and depends on FR1 or FR2 and the spectrum type. The configuration index in these tables is given by the higher layer parameter prach- Configurationlndex, or by msgA-PRACH-Configurationlndex if configured.

[0102] PRACH slots have periodicities from 10ms up to 160 ms, Table 6.3-3.2-3 (FR1) and Table 6.3-3.2-4 (FR2), of TS 38.211.

[0103] The PRACH slots are in the index frame given by the formula nfmod x = y, (see TS 38.211, Clause 6.3.3.2) where x is the configuration period {1,2,4,8,16}. The PRACH slots are in a subframe (e.g., indicated by the Subframe number) while the number of slots is indicated by the Number of PRACH slots within a subframe (e.g., none, one, or two). For instance, in Table 6-3-3-2-3, if PRACH configuration 76 is selected, the period x=2, e.g., 20ms, thus in the odd frames, one PRACH slot will be in each of the subframes 2,34,7,8,9.

[0104] In the above tables for FR2 the column of the subframe number is replaced with the column of slot number, where a slot duration corresponds to 60 kHz SCS.PAGING

[0105] The UE shall monitor the Paging Occasions (Pos) as described in clause 7.1 of TS 38.304 to receive System Information change notifications in RRC_IDLE and RRC_INACTIVE. The changes in the system information are notified by the network using a Short Message as specified in TS 38.331. When the Short Message notifies system information changes, then the UE shall acquire or re-acquire the concerned system information as specified in TS 38.331.

[0106] The paging procedure is used to transmit information to a UE in RRC_IDLE or RRC_INACTIVE state. The UE may use Discontinuous Reception (DRX) in RRC_IDLE and RRC_INACTIVE state to reduce power consumption. The UE monitors one paging occasion (PO) per DRX cycle.

[0107] The network initiates the paging procedure by transmitting the Paging message at the UE’s paging occasion as specified in TS 38.304. The network may address multiple UEs within a Paging message by including one PagingRecord for each UE. The network may also include one or multiple TMGI(s) in the Paging message to page UEs for specific MBS multicast session(s).

[0108] For each SSB there are several paging occasions ( iroJ'PDCCH- MonitoringOccasioiiPerSSB-InPO).

[0109] The number of PDCCH monitoring occasions corresponding to an SSB within a PagingOccasion (PO), specified in TS 38.304, clause 7.1.

[0110] The maximum number of paging occasions per paging frame is 4. One Paging Frame (PF) is one Radio Frame and may contain one or multiple PO(s) or starting point of a PO.

[0111] The PF and PO for paging are determined by the following formulae:

[0112] SFN for the PF is determined by: (SFN + PF_offset) modT = (T div N)*(UE_ID mod N).

[0113] Index (i_s), indicating the index of the PO is determined by: i_s = floor (UE_ID / N) mod Ns, whereT=DRX cycle of UE. If UE does not operate in DRX (eDRX) mode, T is determined by the shortest of the UE specific DRX value (s), if configured by RRC and / or upper layers, and a default DRX value broadcast in system information.

[0114] N: number of total paging frames in T.

[0115] Ns: number of paging occasions for a PF.

[0116] PF_offset: offset used for PF determination.

[0117] UE_1D:

[0118] If the UE operates in eDRX as specified in clause 7.4:

[0119] - 5G-S-TMSI mod 4096

[0120] else:

[0121] - 5G-S-TMSI mod 1024

[0122] Parameters Ns, nAndPagingFrameOffset, nrofPDCCH-MonitoringOccasionPerSSB-InPO, and the length of default DRX Cycle are signaled in SIBi. The values of N and PF_offsetare derived from the parameter nAndPagingFrameOffset as defined in TS 38.331. The parameter firstPDCCH-MonitoringOccasionOfPO is signaled in SIB1 for paging in the BWP configured by initialDownlinkBWP. For paging in a DL BWP other than the BWP configured by initialDownlinkBWP, the parameter first-PDCCH-MonitoringOccasionOfPO is signaled in the corresponding BWP configuration.

[0123] The values for paging cycle period (T) are defined in TS 38.331:

[0124] PagingCycle ::= ENUMERATED {rf32, rf64, rfi28, rf256}

[0125] In Rel-17 more values were added:

[0126] ExtendedPagingCycle-ri ::= ENUMERATED {rf256, rf5i2, rfiO24, sparei}

[0127] Which allows extending the period up to 1024 frames =10.2405 duration.

[0128] The number of paging frames in a paging cycle (N) can have values in {1,2,4,8,16} dependent on the subcarrier spacing (SCS) values, while the number of the PO per paging frame (Ns) has values {4,2,1}.

[0129] In accordance with another observation, the existing paging configuration values allow large paging periods that could accommodate the gNB sleeping patterns.

[0130] In some contexts, potential gains result from reduced paging occasions when the paging load is increased and the number of SSB increases.. For zero loads and low paging loads 0.2% the energy saving gain was minor around 5% when using a reduced density of PF. Notable energy saving may be realized for contexts with zero load and higher paging load (2%).

[0131] In accordance with another observation, changing the existing paging patterns may provide little or negligible energy gain in most scenarios.

[0132] Nevertheless, if larger SSB periodicity values are added to improve the energy gain, some additional paging configurations may be necessary. For instance, the range of nrofPDCCH- MonitoringOccasionPerSSB-InPO, which takes values of (2...4) can be extended to (2...8). Thus, changes in SSB time distribution may require some changes of paging configuration as an implicit consequence. Based on the reported results in the study phase, it is concluded that there is not enough evidence to justify independent adaptation in time of paging. The only justified configuration changes of paging are those resulting from changing of other signals and / or channels such SSB.Cell DTX / DRX

[0133] To facilitate reducing gN B downlink transmission and / or uplink reception active time, UE can be configured with a periodic cell DTX / DRX pattern (e.g., active and non-active periods).

[0134] The pattern configuration for cell DTX / DRX is common for the UEs configured with this feature in the cell. The cell DTX and cell DRX patterns can be configured and activated separately. A maximum of two cell DTX / DRX patterns can be configured per MAC entity for different serving cells. When cell DTX is configured and activated for the concerned cell, the UE may not monitor PDCCH in selected cases or does not monitor SPS occasions during cell DTXnon-active duration.

[0135] When cell DRX is configured and activated for the concerned cell, the UE does not transmit on configured grant (CG) resources or does not transmit a scheduling request (SR) during cell DRX non-active duration. This feature is only applicable to UEs in RRC_CONNECTED state and it does not impact Random Access procedure, SSB transmission, paging, and system information broadcasting. Cell DTX / DRX can be activated and / or deactivated by RRC signaling or Lt group common signaling. Cell DTX / DRX is characterized by the follow ing:

[0136] - Active duration: duration that the UE waits for to receive PDCCHs or SPS occasions, and transmit SR or CG. In this duration, the gNB transmission and / or reception of PDCCH, SPS, SR, CG, periodic and semi-persistent CSI report are not impacted for the purpose of network energy saving;

[0137] - Cycle: specifies the periodic repetition of the active-duration followed by a period of non-active duration.

[0138] Active duration and cycle parameters are common between cell DTX and cell DRX, when both are configured;

[0139] Once the gNB recognizes there is an emergency call or public safety related service (e.g., MPS or MCS), the network should ensure that there is no impact to that service (e.g., it may release or deactivate cell DTX / DRX configuration). The network should also ensure that there is at least partial overlapping between UE’s connected mode DRX on-duration and cell DTX / DRX active duration, e.g., the UE’s connected mode DRX periodicity is a multiple of cell DTX / DRX periodicity or vice versa. The active duration is also known as active period or active time. These terms are used interchangeably. For example, FIG. 18 illustrates a an example flow of UE operations of legacy dormancy and / or cell DTX.SCell Activation

[0140] Network adaptation, or adaptive transmission, has been studied in 3GPP, such as cell on and / or off, fast SCell activation and / or deactivation, SCell layer-1 dormancy, and the like, to achieve efficient network adaptation for various purposes, such as network and / or UE power saving, interference management, network and / or UE complexity reduction, and so on. It is widely observed that NR Rel-15 SCell activation latency is generally in the range of tens to hundreds of milliseconds, which is even longer than LTE for many cases. The large latency in activating an SCell is primarily dominated by the time gap associated with the SSB measurement timing configuration (SMTC), which configures the UE to monitor and process SSB once every typically tens of milliseconds. FIG. 5 illustrates an example flow of UE operations of Rel-15 SCell activation. Based on SSB, the UE can gain necessary information to set its AGC, acquire timing, and perform frequency synchronization. In contrast, in LTE SCell activation, these operations are based on the always-on CRS (e.g., periodic CRSs with short intervals in between) and hence maybe completed faster.

[0141] When the SCell is deactivated, its periodic (P) SSB may be turned off for long. However, this leads to slow activation.

[0142] FIG. 4 shows an example of the current 5G NR Rel-15 and / or 16 SCell activation timeline. In FIG. 4, with reference to slots for PUCCH transmissions, when a UE receives in a PDSCH an activation command for a secondary cell ending in slotn, the UE applies the corresponding actions defined in TS 38.321 no later than the minimum requirement defined in TS 38.133 and no earlier than slotn+^ , except for the following:

[0143] - The actions related to CSI reporting on a serving cell that is active in slotn+k,

[0144] - The actions related to the sCellDeactivationTimer associated with the secondary cell that the UE applies in slotn+^ ,

[0145] - the actions related to CSI reporting on a serving cell which is not active in slotn+kthat the UE applies in the earliest slot aftern+^ in which the serving cell is active.

[0146] The valuenumber of slots for a PUCCH transmission with HARQ-ACK information for the PDSCH reception and is indicated by the PDSCH-to-HARQ_feedback timing indicator field in the DCI format scheduling the PDSCH reception as described in Clause 9.2.3 in TS38.213 andis a number of slots per subframe for the SCS configuration of the PUCCH transmission.

[0147] With reference to slots for PUCCH transmissions, if a UE receives a deactivation command (see e.g., TS 38.321, which is hereby incorporated herein by reference in its entirety) for a secondary' cell ending in slotn, the UE applies the corresponding actions in (see e.g., TS 38.321) no later than the minimum requirement defined in TS 38.133, which are hereby incorporated herein by reference in their entirety, except for the actions related to CSI reporting on an activated serving cell which the UE applies in slotR+'(.

[0148] If the sCellDeactivationTimer associated with the secondary" cell expires in slotn, the UE applies the corresponding actions in TS 38.321 no later than the minimum requirement defined in TS 38.133, except for the actions related to CSI reporting on an activated serving cell which the UE applies in the first slot that is after slotis the SCS configuration for PDSCH reception on the secondary cell.

[0149] On and after slot n+k, the following are performed:

[0150] 1> SCell Activation and / or Deactivation MAC CE is received activating the SCell:

[0151] 2> if the SCell was deactivated prior to receiving this SCell Activation and / orDeactivation MAC CE; or

[0152] 2> if the SCell is configured with sCellState set to activated upon SCellconfiguration:[01531if firstActiveDownlinkB WP-Id is not set to dormant BWP:

[0154] 4> activate the SCell according to the timing defined in TS38.213 for MAC CE activation and according to the timing defined in TS 38.133 for direct SCell activation; e.g., apply normal SCell operation including:

[0155] 5> SRS transmissions on the SCell;

[0156] 5> CSI reporting for the SCell;[01571 CH monitoring on the SCell;

[0158] CH monitoring for the SCell;

[0159] CH transmissions on the SCell, if configured,

[0160] elseeDownlinkBWP -Id is set to dormant BWP):

[0161] 4> stop the bwp-InactivityTimer of this Serving Cell, if running.

[0162] 3> activate the DL BWP and UL BWP indicated by firstActiveDownlinkB WP-Id and first Active UplinkB WP-Id respectively.

[0163] 2> start or restart the sCellDeactivationTimer associated with the SCell according to the timing defined in TS 38.213 for MAC CE activation and according to the timing defined in TS 38.133 for direct SCell activation;

[0164] 2> if the active DL BWP is not the dormant BWP:

[0165] 3> initialize, or re-initialize, any suspended configured uplink grants of configured grant Type 1 associated with this SCell according to the stored configuration, if any, and to start in the symbol according to rules in clause 5.8.2.2 of TS38.321;

[0166] 3> trigger PHR according to clause 5.4.6 of TS38.321.

[0167] FIG. 4 shows that the long latency SCell activation is partially due to: 1) SSB duty cycle is long, and one or more SSBs may be utilized (e.g., time F (402)); 2) AP CSI reporting (and in some implementations the CSI measurement for that reporting) can only be triggered after time I (404). The first P / SP CQI may be optional; the first AP CQI may be optional and may be same, cross-carrier triggering, and / or reporting.

[0168] In Rel-17, enhanced SCell activation may be utilized. For a deactivated SCell under certain circumstances, such as if the SCell has not been deactivated for a long time or the last SCell SSB monitoring and / or reporting was not a long time back, or there is an intra-band activated serving cell, the SCell can rely on AP TRS, which is transmitted after the UE receives the Rel-17 enhanced SCell activation signaling, and the UE performs at least one of AGC, fine tracking, and the like, based on the AP TRS, thus completing the activation procedure. Since the UE does not have to wait for the P SSB, the activation can be much faster. Fig. 6 illustrates an example flow of UE operations of Rel-17 SCell activation based on AP TRS.

[0169] For Rel-17 SCell activation, the P SSB may be turned off after deactivation. However,to enable fast activation via aperiodic (AP) TRS, the SCell has to be remain known to the UE, e.g., it can only be turned off for a short period.

[0170] FIG. 14 illustrates example triggering procedure and timeline (e.g., for FR1 known cell w ith 15 kHz SOS). The first P / SP CQI 1506 may be optional; and first AP CQI 1504 may be optional and may be triggered by new MAC CE 1502 (or legacy DCI in another embodiment). The main difference from Rel-15 procedure includes the following. The enhanced SCell activation includes information about the AP TRS via scellActivationRS-Id, which is associated with the AP TRS configuration information about the triggering time offset of the AP TRS (krRs), the time gap between the 2 AP TRS burst if applicable, and the like.Detailed Descriptions of Embodiment Aperiodic Transmission

[0171] In 3GPP TR 38.864, simulations showed that network energy saving can be achieved when the periodic cell SSB is turned off. Therefore, the embodiment techniques may include turning off SCell SSB periodic transmission, while utilizing on-demand SSB. In this disclosure, several design embodiments are provided to support on-demand SSB SCell operation. Several additional questions are further addressed below, including for example, how to modify UE behavior so that the UE can still use the cell and how to wake up the SCell for normal operations.

[0172] Before describing the details of the design embodiments, an understanding of different SCell status per certain standards, namely, SCell configuration, SCell deactivation and / or activation, dormancy, and cell DTX / DRX is provided. A brief summary7of some of the features and what signals and / or channels the UE are expected to transmit (Tx) or receive (Rx) is provided below. For any cell that has been removed by RRC or has not been added and / or configured, it is a neighbor cell, not a serving cell. For the ease of explanation, an on-demand SSB may be called OD-SSB or AP-SSB (e.g., aperiodic SSB), and always-on SSB may be called AO-SSB in this disclosure.

[0173] In an embodiment the OD-SSB has the same values for the properties as its corresponding AO-SSB, apart from its starting time (e.g., start) or in case of a limited duration between its start time and stop time.

[0174] In another embodiment, OD-SSB property values may be different than its correspondent AO-SSB. For instance, the OD-SSB may be a non-cell defining SSB and placed on a non-synchronization raster while the AO-SSB may be a cell defining SSB. Another example is that OD-SSB may indicate that the cell does not provide S1B1 (for instance when the property values may be provisioned by the PCell) while the OA-SSB indicates that SIB1 is provided by the current cell. Thus, when UE operation is based on the OD-SSB, the UE may use the SIB1 from a different cell. When UE operation is based on AO-SSB, the UE may use the SIBt from the same cell. FIG. 19 depicts an example SCell status in accordance with embodiments of the present disclosure.Table 1 Cell status: configured, deactivated / activated, dormant, and cell DTX / DRX[01751Afew observations can be drawn from the details above:

[0176] - For a UE operating in CA, at least the PCell is always activated and not in dormancy.The PCell could be in cell DTX / DRX.

[0177] - SCell deactivation allows all transmissions and / or receptions to be turned off, which can provide the highest energy saving benefit if applicable. The ‘wake-up’ mechanism is via SCell activation procedure using Rel-15 and / or Rel-17 SCell activation MAC CE signaling.

[0178] - - The only exception is that, if the SCell is configured with measCycleSCell, the UE will still perform measurement according to the configured cycle during deactivation. Then the UE expects the SSB to be transmitted for those measurement instances. This mechanism is can be the same as neighbor cell monitoring, according to some embodiments.

[0179] - With SCell dormancy, the DL synchronization, tracking, and CSI acquisition are still maintained. All UL transmissions on the carrier are off, whereas P / SP CSI report for this SCell can be sent on another carrier. The ‘wake-up’ mechanism is via BWP switching DCI signaling.

[0180] - Cell DTX has a periodical wake-up, e.g., active period for normal operations, and outside the active period, most DL activities are stopped, but the DL synchronization, tracking, and P / SP CSI-RS transmissions not for CSI acquisition are still maintained.

[0181] - Cell DRX has a periodical wake-up, e.g., active period for normal operations, and outside the active period, most UL activities are stopped, but the UE can wake up the cell via RACH if an emergency service is initiated by upper layers and this serving cell is the SpCell.

[0182] Based on the above analysis, generally the UE in any of the above status on a carrier of a serving cell may still monitor the SSB of the SCell based on certain standards, so it is difficult to turn off SCell SSB transmissions even when there is no activity on the SCell for some time. However, the UE behaviors and related procedures as shown above may be enhanced to rely on on-demand SSB, in some cases, so that the network can consume less energy while still maintaining and / or improving the operation efficiency.Example Use Cases and / or Scenarios

[0183] The designs are provided for the general cases where a UE is in connected mode configured w ith a PCell and one or more SCells on one or multiple bands. Then at a certain point in time, the UE utilizes on-demand SSB for a SCell. This setup is further discussed below.

[0184] First, the PCell and SCell(s) are assumed to be co-located and connected via fast backhaul, or they may even share the same equipment. Therefore, most of the decision making and information exchange for the serving cells (e.g., to decide which serving cell is to perform some transmissions with the UE) are internal to the network and do not have standard impact. This understanding applies for typical CA deployments, regardless of whether they are intra-band or inter-band, FR1 and / or FR2.

[0185] The SCell may or may not be a SSB-less SCell. In case the SCell is SSB-less, it implies that there is another serving cell’s SSB configured as the reference so that the UE can derive time and / or frequency synchronization based on the SSB and the RSs on the SCell are directly or indirectly QCLed with the SSB, e.g., a cross-carrier SSB is used for this SCell. To incorporate both cases (e.g., with or without SSB on the SCell), this disclosure adopts the term “SSB for the SCell”. The existing standards do not allow a serving cell to operate without a SSB as the QCL source for its signals, including TRS, CSI-RS for CSI / BM, DMRS, and the like.

[0186] Next, to clarify the various use cases and / or scenarios, this disclosure provides solutions to several questions in the following sections.Functionalities and Availability of SSB for the SCell

[0187] The design goal is to support on-demand SSB SCell operation for network energysaving, which implies that regular SSB for the SCell is not available or insufficient at a certain moment in time. The first question to clarify- is why the regular SSB for the SCell cannot be used. SSB is necessary for functionalities such as time and / or frequency synchronization, L1 / L3 measurements, and QCL source for the SCell.

[0188] 01: Why cannot the UE utilize the regular SSB for the SCell at this moment?

[0189] - If the SSB is periodically transmitted according to a standardized periodicity ranging from 5 ms to 160 ms, the UE does not need to utilize on-demand SSB for the SCell. Time and / or frequency synchronization and L1 / L3 measurements can be maintained without any issue, and no on-demand SSB is needed.

[0190] - If the SSB has not been transmitted for an excessively long time, the UE may become out of sync on the SCell (e.g., not synchronized, or insufficient synchronization accuracy, or only coarse synchronization but no fine timing and / or tracking). The UE will then utilize on-demand SSB for the SCell.

[0191] - - If the SCell is deactivated for a sufficiently long time, this synchronization could be lost.

[0192] - - In this case, if the SCell is to be utilized, the network can activate this SCell, andRel-15 mechanism specifies that the UE has to wait for the next SSB transmission(s) to reacquire AGC, time and / or frequency synchronization, and the like, which could be long.

[0193] - - Rel-17 mechanisms specify that a capable UE can utilize AP TRS to achieve fast activation if the SCell is still known and satisfies certain conditions, e.g., if the SCell has not been deactivated for too long.

[0194] - - However, if the fast activation requirements for Rel-17 mechanism are not met, e.g., the SCell may have become unknown, the UE can benefit from on-demand SSB for the SCell. More details will follow upon the SCell activation command is sent. Regardless of the presence of always-on periodic SSB for the SCell, the on-demand SSB added during the SCell activation can be used for AGC, synchronization, fine timing, tracking, and the like, based on which the SCell activation duration from the SCell activation command to the completion of SCell activation as defined in TS38.133 can be shortened, as illustrated in FIG. 20.

[0195] - - Even if the PCell is always on (or, in some embodiments, another activated serving cell is always transmitting SSB), the synchronization acquired and / or maintained on the activated serving cell may not be useful and / or sufficient for the SCell activation, and additional SSB / TRS acquisition for the deactivated SCell is still required. Detailed requirements depend on certain conditions, e.g., whether the deactivated SCell and another activated serving cell are intra-band contiguous CA, whether their transmission power difference is sufficiently small, and the like.

[0196] - - If the SCell is still activated but the SSB has not been made available to the UE for a sufficiently long time, this synchronization could be lost.

[0197] - - The direct cause for the SSB been unavailable to the UE for a sufficiently long time may be the periodic SSB is stopped and / or suspended (e.g., not transmitted according to the preconfigured schedule), or the periodicity is set to be excessively long. This does not appear to be a typical case based on the existing standardized requirements. However, for energy saving purposes for future releases, stopping, reducing, and / or prolonging periodic SSB transmissions may be considered, except when continuous transmissions and / or receptions are ongoing, in which case stopping the SSB is unlikely to save much energy anyway. For this reason, this disclosure can focus on the cases where the SCell is in dormancy or cell DTX.

[0198] - - According to current mechanisms, if the SCell is in dormancy, e.g., the dormantBWP is active, the UE still reports P / SP CSI and hence, TRS and SSB in some embodiments are still monitored, so the UE will not lose synchronization. Similarly, if the SCell is in DTX, the UE in some embodiments still monitors TRS, CS1-RS not with a RI report, and hence SSB, so it will not lose synchronization, either.

[0199] - - Therefore, stopping and / or prolonging SSB transmission for cell dormancy and / or cell DTX can be considered for energy saving in Rel-19.

[0200] From this analysis, the SCell can be either deactivated for the UE for a sufficiently long time, or the SCell is activated but in cell dormancy and / or cell DTX with a new behavior of stoppedor prolonged SSB cycles for the SCell.

[0201] In short summary7, for the various embodiments of on-demand SSB SCell operation for a UE in connected mode, consider the follow ing cases:

[0202] - Question 1 Case 1: The SCell is deactivated for the UE for a sufficiently long time.

[0203] - Question 1 Case 2: The SCell is activated and is in cell dormancy or cell DTX, and the SSB for the SCell has not been made available to the UE for a sufficiently long time, e.g., stopped or prolonged.Purposes of Using On- Demand SSB for the SCell

[0204] Based on above discussion, the SSB for the SCell has not been made available for the UE for a while. The next question addressed is what motivates the use of on-demand SSB for the SCell at this moment, such as what events lead to the new- demand of the SSB for the SCell.

[0205] O2: What is the purpose for the UE to utilize on-demand SSB for the SCell at this moment?

[0206] - There may be an immediate need for data transmission and / or reception and the network and / or UE decides to use the SCell for the data transmission and / or reception. To support the data transmission and / or reception on the SCell, synchronization has to be acquired, and the SCell signals and / or channels have their QCL source(s), which directly or indirectly rely on the SSB for the SCell. For example, during SCell activation, synchronization based on the SSB.

[0207] - Therefore, the purpose of utilizing on-demand SSB is to support data transmission on the SCell, for which the on-demand SSB is utilized at least for synchronization and the QCL source.

[0208] - Even if there is no immediate data to be transmitted on the SCell at this moment, the UE or the network may determine that the synchronization is about to be lost, and it is preferable to maintain the synchronization so that the SCell can be quickly available for later data transmission (e.g., rather than losing the synchronization and reacquire synchronization later, which increases latency). This would also require on-demand SSB for the SCell. Though this disclosure discusses the purpose of on-demand SSB may include re-synchronization, this purpose does not have to be captured in a standard specification; the standard specification can specify a signaling and the associated on-demand SSB are to be used for the UE to perform on-demand SSB based on operations.

[0209] Thus, the UE can utilize on-demand SSB to reacquire and / or maintain the synchronization for the SCell, so that the SCell can be used for immediate or later data transmission. More specifically, for Case 1 above, on-demand SSB can be used to speed up the SCell activation. For Case 2, on-demand SSB to reacquire and / or maintain the synchronization for the SCell.

[0210] To summarize, for the various enhancements of on-demand SSB SCell operation for a UE in connected mode, two main cases are considered:

[0211] - Question 2 Case 1: The SCell activation can be sped up with on-demand SSB.

[0212] - Question 2 Case 2: The synchronization for SCell in cell dormancy or cell DTX can be reacquired and / or maintained with on-demand SSB.Triggering

[0213] There are three triggering methods described in the WID: UE uplink wake-up-signal (WUS) using an existing signal and / or channel, cell on and / or off indication via backhaul, and SCell activation and / or deactivation signaling. The next question is what the triggering is for, based on which this disclosure can answer which triggering method is to be used.

[0214] Qq: What is the triggering for? Which triggering method is to be used?

[0215] - Triggering may be used for the following purposes:

[0216] - - The network informs the UE about UL and / or DL data transmission, or the UE informs the network about UL data transmission.

[0217] - The PCell is always activated for the UE and never in dormancy. Thus, for these triggering purposes, at least the PCell (or, in some embodiments, another activated non-dormant SCell) can be used to deliver the corresponding signaling. The signal and / or signaling to inform the UE and / or network about the need for data transmission also exists, in general, the PDCCH / PDSCH (e.g., including MAC CE and RRC, e.g., SCell activation signaling) in DL, and PUCCH / PRACH in UL. No new content needs to be introduced for these triggering purposes.

[0218] - - The UE informs the network that synchronization, and / or re-synchronization, for the SCell is to be performed.

[0219] — For this purpose, which cannot be accomplished based on existing standards, new- messaging content in some embodiments is specified using existing signal and / or signaling.

[0220] - UL WUS based triggering:

[0221] - - The UL WUS cannot be sent on the SCell without SSB for a long time. This is because any UL transmission on the SCell would require a certain degree of DL synchronization and DL signal strength measurement (e.g., for pathloss (PL) estimate used for UL power control (PC)), which cannot be reliably obtained on the SCell without SSB for a long time.

[0222] - - On the PCell (or, in some embodiments, any activated, non-dormant serving cell), the UE can send UL signal to the network via configured, periodic UL transmission opportunity, such as a (usually periodic) RACH opportunity or PUCCH occasion, to inform the network that the UE has UL data to transmit. There is no new standard impact for this operation.

[0223] - - If the UE wishes to inform the network about the to-be-performed synchronization, and / or re-synchronization, on the SCell, existing signal such as PUCCH or PRACH may still be used, but a control message is standardized so that the network can understand.

[0224] - - To avoid the case that the UE frequently wakes up the SCell, the UE is not allowed to send WUS with a period of time since the last event, such as the event of entering dormancy and / or DTX / DRX, the event of leaving the last active period, and the like.

[0225] - Cell on and / or off indication via backhaul:

[0226] - - As discussed, backhaul information exchange and decision making are internal to the network and has no RAN1 standard impact.

[0227] - SCell activation and / or deactivation signaling:

[0228] - - Activation may be performed if the network decides to use the deactivated SCell for data transmission. The MAC activation signaling can serve as a trigger from the network to inform the UE to activate the SCell, which restores synchronization for the SCell and prepares the SCell for UL and / or DL data transmission. The MAC CE and its scheduling DCI can be sent on the PCell or other activated non-dormant SCell.

[0229] - - The network can also send a MAC deactivation signaling as a trigger to inform theUE that the SCell will not be used.

[0230] - Cell dormancy and / or DTX / DRX signaling and mechanism:

[0231] - - Existing signaling and mechanism to transition to SCell dormancy and / or DTX can be reused to inform the UE that SSB may be absent, and UL WUS can be sent. The signaling itself may not need any modification, e.g., based on pre-configured protocol, the UE may not expect P SSB after it enters cell dormancy and / or DTX / DRX. Alternatively, a new field may be introduced to explicitly indicate to the UE that the UE may not expect P SSB upon receiving the indication.

[0232] This disclosure thus provides the following embodiments for triggering. For the various enhancements of on-demand SSB SCell operation for a UE in connected mode:

[0233] - The SCell activation signaling sent on an activated non-dormant cell can be used as trigger for on-demand SSB.

[0234] - The UE may send UL WUS on an activated non-dormant cell to inform the network of the need for on-demand SSB for the SCell in dormancy or cell DTX to reacquire and / or maintain synchronization.Example Use Cases, Scenarios, and / or High-Level Designs

[0235] The following clarifies the example use cases and / or scenarios that may be considered:

[0236] - Scenario 1: SCell activation with aperiodic SSB

[0237] - - The SCell is deactivated for a sufficiently long time and has become unknown to the UE. The network decides to activate the SCell and uses it to deliver data. The PCell, or an activated non-dormant serving cell, sends a SCell activation signaling to the UE to activate this SCell. The SCell activation procedure utilizes on-demand (e.g., an aperiodic, alternative, and / or in addition to periodic ones) SSB for the SCell to speed up, so that the UE can utilize the OD-SSB immediately for synchronization and measurement, and the UE does not have to wait and then receive the bursts of periodic SSB which generally takes a much longer time. After the SCell is activated and enters continuous transmission and / or reception, the SSB for the SCell is transmitted periodically according to current mechanism for an activated SCell.

[0238] - Scenario 2: UE UL WUS for re-synchronization with on-demand SSB

[0239] - - The SCell is activated and is in cell dormancy or cell DTX, and the SSB for the SCell has stopped for a sufficiently long time. The UE may send UL WUS on any one of activated nondormant cells to inform the network the need for on-demand SSB for the SCell to reacquire and / or maintain synchronization, and the UL WUS reuses existing PUCCH or RACH but with new messaging content. The network may then send a DL signaling on an activated non-dormant cell to inform the UE about the on-demand SSB to be transmitted. Based on the on-demand SSB, the UE can restore synchronization and the SCell can be utilized for UL and / or DL data transmission.

[0240] - The on-demand SSB can be aperiodic SSB to be transmitted only one time, which may include N SSB transmissions in a burst. For example, one on-demand SSB may be transmitted in one slot; for another example, 4 on-demand SSBs may be transmitted over 20 ms with 5 ms periodicity; or 5 on-demand SSBs may be transmitted in 5 consecutive slots over 2.5 ms (e.g., for FDD SCS 30 kHz case).

[0241] — Alternatively, the on-demand SSB can be periodic SSB to be transmitted according to existing mechanism. The on-demand SSB may also be semi-persistent SSB that the UE will no longer expect to receive upon a timer expiration or a deactivation signaling received.

[0242] - - One of above or both can be supported and which one is to be used is indicated to the UE. If the on-demand SSB is AP SSB, then the current status of the SCell remains (e.g., in dormancy or DTX). If the on-demand SSB is P SSB, then UE may leave dormancy (e.g., the UE indicates which BWP that the UE is to switch to using DL signaling, or the UE switches to the default first active BWP without network indication) or DTX and become active transmitting and / or receiving.

[0243] - The signaling may reuse the Rel-17 enhanced SCell activation signaling for the indication, or a new Lt signaling. The signaling may indicate the SSB number that the UE will expect to receive, e.g., m SSB transmissions, where m may be chosen from {1, 2, 4, semi-persistent, periodic}.

[0244] In summary, for the various enhancements of on-demand SSB SCell operation for a UE in connected mode, detailed embodiments are to be provided for the following design scenarios:

[0245] - Design Scenario 1: SCell fast activation with aperiodic SSB for a deactivated SCell.

[0246] - - SCell is deactivated.

[0247] - - P SSB has stopped after deactivation.

[0248] - - SCell fast activation with AP SSB.

[0249] - - After activation, the SCell can be used for normal operations.

[0250] - Design Scenario 2: UE UL WUS to request re-synchronization with on-demand SSB for an activated SCell in cell dormancy or cell DTX.

[0251] - - SCell is activated but in cell dormancy or cell DTX.

[0252] - - The periodic SSB for the SCell has stopped for a sufficiently long time after the SCell enters dormancy or DTX.

[0253] - - UE UL WUS to request re-synchronization with on-demand SSB.

[0254] - - The SCell transmits on-demand SSB and the UE re-synchronizes based on the SSB.

[0255] - Design Scenario 3: SCell on-demand active period with aperiodic SSB for an activated SCell during cell DTX / DRX.

[0256] - - SCell is activated and in cell DTX / DRX.

[0257] - - P SSB has stopped after entering cell DTX. No periodic active period is expected by the UE.

[0258] - - UE receives (e.g., from a serving cell monitored by the UE) a DCI for on-demand active period with AP SSB for the SCell.

[0259] - - UE enters active period and the SCell can be used for normal operations until the active period ends (e.g., based on an inactivity timer or a Li DCI).

[0260] - - It may be preferred that the UE maintains at least coarse synchronization with theSCell based on another activated cell (e.g., on an intra-band or sometimes even inter-band carrier) so that the transient time (e.g., including AGC, fine tracking, and the like) will be short; otherwise it makes more sense to rely on activation and / or deactivation procedures for the SCell.Detailed Embodiments of SCell Fast Activation with AP SSB

[0261] This use case is illustrated in FIG. 20. FIG. 20 depicts a SCell fast activation with aperiodic SSB for Scenario #3.

[0262] In a set of embodiments of SCell fast activation with AP SSB, a SCell has been deactivated and should be activated. The conditions for fast activation based on AP TRS according to Rel-17 are not satisfied. That is, the SCell may be an unknown cell. The SCell may be configured with measCycleSCell but the cycle may be too long, or there has been no measurement reporting (e.g., no event triggering a measurement reporting) for too long, or not configured with measCycleSCell, and the like, thus the UE has not monitored the SCell SSB for a long time, or has not informed the network about its monitoring of the SCell for a long time. In addition, the SCell may be inter-band with other activated serving cells, or intra-band non-contiguous with another activated serving cell, or intra-band contiguous with another activated serving cell but having more than 6 dB SSB transmission power difference or having Es / Iot lower than -2 dB, and the like, in which cases the time and / or frequency synchronization, AGC, and tracking may not be able to be derived from another cell. Then SCell fast activation with AP SSB can be used. In general, the network can turn off the P SSB on the deactivated SCell for a long for energy saving, and then quickly activate the SCell when it should be utilized.

[0263] The FIG. 7 and FIG. 8 illustrates an embodiment of SCell fast activation with AP SSB. Specifically, FIG. 7 depicts a flowchart of example steps of UE operations in R19 SCell activation based on AP SSB. FIG. 8 depicts a timeline of UE operations in R19 SCell activation based on APSSB.

[0264] The SSB may be periodic, semi-persistent, or aperiodic triggered by MAC CE. In an embodiment, one or more (=M) bursts of AP SSBs may be pre-configured for the activation and triggered. For each burst of SSBs, one or more (=m) SSB transmissions may be included. It could be in the order of (m AP SSB) for one AP burst, (mi AP SSB, m2 AP SSB) for two AP bursts, or (mi AP SSB, m2 P SSB) for one AP burst following by a number of P SSB transmissions, but the one with the shortest delay in general is (m AP SSB) or (mi AP SSB, m2 AP SSB). A gap (e.g., 2 slots) may exist between any 2 consecutive SSB bursts, which may allow some time for the UE to perform actions based on the SSB. Within an AP SSB burst, each of the m SSB transmissions generally occupies one slot, and the SSB slots are consecutive in time except for the non-DL slot(s) in TDD. Each of these ways of transmitting the on-demand SSB are pre-configured for the SCell. Within each SSB transmission slot, the time-frequency' domain resources used for SSB are the same as existing SSB design and / or configuration. The on-demand SSB bursts are aperiodic and in addition to periodic ones. The on-demand SSB bursts in some embodiments are of the first SSB.

[0265] In an embodiment, a new SCell activation AP SSB configuration is provided to the UE in RRC signaling. The configuration includes at least a configuration ID which may be non-zero, a reference to a configured SSB so that the existing SSB configuration is reused, and new- timedomain transmission parameters for the AP SSB. The time-domain transmission parameters may include a triggering offset in a number of slots, e.g., kssB (or 1<AP-SSB), which is the slot offset from the slot n+k in FIG. 8 to the starting slot of the first AP SSB transmission. If one burst is to be transmitted, no gap between the bursts will be configured, and the number of SSB transmissions m or the number of slots m that the UE expects the SSB will be configured. For example, m=5 may be configured, and 5 SSB transmissions may be provided on 5 consecutive DL slots, or 4 SSB transmissions may be actually provided on 5 consecutive slots but no SSB on one of them which is an UL slot, or 5 SSB transmissions may be actually provided on 6 consecutive slots but no SSB on one of them which is an UL slot, and the like. The network may optionally configure slot gap between consecutive SSB transmissions in a burst. When multiple SSB bursts are to be transmitted, a gap between consecutive bursts will be configured. If multiple SSB-indexes exist for the SSB, an SSB-index may also be included in the configuration. One or more new SCell activation AP SSB configurations may be configured for each SCell, and different configurations may be used for different SSB-indexes (e.g., different beams), different numbers of SSB bursts, and the like. For FR1, in some embodiments, only one configuration may be assigned for simplicity.

[0266] In an embodiment, a new SCell activation signaling is provided. The signaling may be a MAC CE, or in some cases if even faster response is desired, a DCI. The signaling includes a field for the SCell, w hich indicates whether the SCell is to be activated or deactivated. If the SCell is tobe activated, another field includes a SCell activation AP SSB configuration ID if multiple such configurations are provided. In an embodiment, if the field is set to o, then AP SSB is not transmitted and the UE does not expect AP SSB. In an embodiment, the AP SSB indication may not be included in the SCell activation signaling but carried in a separate signaling. The AP SSB indication still includes information such as the slot offset until the AP SSB is transmitted by the network or monitored by the UE. The causes that the SCell becomes unknown can include excessively long periods of the SSB or even unavailable always-on SSB for the SCell due to energy efficiency consideration. The indication of the OD-SSB is sent when the UE receives the SCell activation command; however, that does not imply the OD-SSB is transmitted by the SCell or monitored by the UE immediately after the OD-SSB indication and / or SCell activation command are sent. A time offset can exist between the time receiving the indication and the time UE expects the OD-SSB. The time offset may include several time durations, e.g., UE processing the indication, additional slot and / or symbol offset indicated in the OD-SSB indication, and the like. The reference point of the time offset can be relative to PCell timing or timing of the serving cell on which the UE receives the OD-SSB indication. In case that the SCell is unknown or the UE does not assume always-on SSB for the SCell so that the SCell timing is largely unknown to the UE, the UE may need to perform a search in a time window, and the search time window7may be indicated in the signaling. The time window may include a duration from the timing corresponding to the indicated offset, e.g., the start timing of the search window, or may include another offset corresponding to the ending of the time window. There may be differences in the numerologies of the to-be-activated SCell and the other serving cell, and the offset(s) may be based on either numerology, generally based on the SCell’s numerology, but in case of a search window is provided, it may be based on the other serving cell’s numerology. When there is transmission timing difference between the other serving cell and the SCell and it is known to the gNB, the timing difference may also be provided in the indication.

[0267] In some embodiments, an AP SSB includes both PSS / SSS and PBCH if the UE intends to read the PBCH. In some embodiments, an AP SSB includes only PSS / SSS but no PBCH or its DMRS if the UE does not need to read the PBCH or the information carried in the PBCH is sent via RRC signaling from another serving cell to the UE. A flag of whether PBCH / DMRS may also be present in the activation MAC CE or in the SCell activation AP SSB configuration.

[0268] In some embodiments, AP TRS are also triggered. This could be useful for the SCell to be quickly used for data transmission since typically CS1-RS / DMRS are QCLed to TRS. SCellActivationRS can be configured, and may be referenced within the new SCell activation AP SSB configuration. The SCell activation signaling optionally provides the SCellActivationRS configuration ID. After the UE receives the AP SSB, the UE receives the AP TRS according to the configuration.

[0269] In some embodiments, the AP SSB may be a cross-carrier SSB configured for theSCell. The SCell may be a SSB-less SCell. The SCell activation AP SSB configuration provides the cross-carrier SSB information.Detailed Embodiments of On- Demand SSB During Cell Dormancy and / or Cell DTX

[0270] In a set of embodiment, on-demand SSB during cell dormancy and / or cell DTX is provided. FIG. 9 is an example of the procedure from UE perspective and UE UL WUS is used. FIG. 10 is an example of the procedure from UE perspective where DL DCI WUS is used. This allows the P SSB, and hence the cell, to be turned off for longer periods of time.

[0271] In an embodiment, a UE enters cell DTX, or dormancy, for the SCell and no active period is configured, e.g., there is no DTX cycle configuration; alternatively, the DTX cycle is configured but the period is long, e.g., more than 10.240 seconds. The UE does not assume P SSB, P TRS, CSI-RS, and the like, be transmitted regularly during the DTX duration (or during dormancy ), except when triggered by some events such as WUS or sy nchronization requirements.

[0272] In an embodiment, the UE receives a DCI (or generally, a DL WUS) on an activated serving that the UE is monitoring. The DCI indicates that on-demand SSB on the SCell is to be transmitted and the UE will monitor the SSB. The DCI field design may be similar to above SCell fast activation signaling design if the on-demand SSB includes AP SSB, that is, the DCI may indicate the pre-configured AP SSB or one of the pre-configured AP SSB configurations is expected by the UE, and the AP SSB will be transmitted and / or monitored after a slot offset from the DCI. Alternatively, the slot offset may be included in the DCI. AP TRS may also be indicated. In some embodiments, the on-demand SSB does not include AP SSB, but the regular SSB (e.g., as in normal operating conditions) is to be transmitted and / or monitored according to the SSB’s configuration (e.g., periodicity, offset, and the like). In an embodiment, the SCell is in dormancy, (e.g., the current BWP is the dormant BWP) then the BWP switching DCI may be used, and the UE switches to the indicated non-dormant BWP. The UE starts receiving the SSB, TRS, CSI-RS, and the like, and monitors PDCCH for this SCell and / or on this SCell after the reception of on- demand SSB and TRS. In some embodiments, the TRS (e.g., an AP TRS) is received after a first SSB, for example such that the first SSB is received before the TRS is received. Then the UE may be able to receive and / or transmit data on the SCell. The UE starts a timer (e.g., an inactivity timer or on-duration timer) and resets the timer every time it successfully decodes a PDCCH. When the timer expires, the UE re-enters non-active period, or dormancy, and stops monitoring SSB / PDCCH.

[0273] In an embodiment, the UE is configured with UL WUS, which may be PRACH or a PUCCH on a serving that the UE is currently monitoring. The WUS indicates that on-demand SSB is requested. The network may confirm the request by sending an acknowledgement or starting the on-demand SSB transmission. The configuration and procedure for the on-demand SSB transmission is similar to above embodiments. The on-demand SSB may be transmitted one time to help maintain sufficient synchronization accuracy with the SCell, or transmitted as innormal non-dormant duration or active period.

[0274] In an embodiment, the UE maintains coarse synchronization with the SCell, which may be required for operating w ith the DCI-triggered on-demand SSB. The SCell may be interband with other activated serving cells but the network has signaled that the cells are synchronous up to certain accuracy, or intra-band non-contiguous with another activated serving cell but the network has signaled that the cells are synchronous up to certain accuracy, or intra-band contiguous with another activated serving cell but having more than 6 dB SSB transmission pow er difference or having Es / Iot lower than -2 dB, and the like. The coarse timing may be roughly aligned so that the UE knows a narrow timing window to search for the on-demand SSB. In general, the network’s signaling information on cell synchrony, difference between SSB transmission powers, and Es / Iot criterion, may be used for the UE to determine if coarse synchronization with the SCell can be assumed.

[0275] SCell is activated and is in cell DTX or cell dormancy, and the SSB for the SCell has stopped for a sufficiently long time. The SSB may still be always-on but with excessively long periodicity, or there is no always-on SSB, e.g., the network can make SSB much less often or even completely on-demand to save energy if the SCell is in DTX or cell dormancy. Then UE loses synchronization accuracy overtime without receiving SSB. The network may decide to utilize the SCell in cell DTX or cell dormancy, and the network send a DL signaling on an activated non- dormant non-DTX serving cell to inform the UE about the on-demand SSB for the SCell, so that the UE can reacquire and / or maintain synchronization on the SCell. After receiving the on- demand SSB, the SCell can be utilized for UL and / or DL data transmission.

[0276] - In the case of cell DTX for the SCell, a DCI sent on the other serving cell informs theUE about an on -demand SSB for the SCell associated with an on-demand Active Period; see FIGs. 21 and 22 for an example. The UE receives the DCI, acquires the on-demand SSB, based on which it regains high synchronization accuracy, and starts Active Period and monitors PDCCH on the SCell.

[0277] - In the case of cell dormancy for the SCell, a DCI sent on the other serving cell informs the UE about switching to a non-dormant BWP. The UE receives the DCI, acquires the on- demand SSB, based on which it regains high synchronization accuracy, and starts normal operations on the non-dormant BWP of the SCell.

[0278] Detailed embodiments for Deactivated SCell re-synchronization and / or RRM measurement with on-demand SSB

[0279] This use case is illustrated in FIG. 21, as well as FIG. 22 depicting UE operations of at least some embodiments of a R19 deactivated SCell with AP SSB.

[0280] Overall, the UE is configured with SSB-based RRM measurement, the SSB-based RRM measurement’s triggering mechanism (e.g., a trigger to be sent on another carrier), and optionally the SSB-based RRM measurement’s reporting mechanism (e.g., reporting on anothercarrier). The UE may not assume that periodic SSB is sent during deactivation. The trigger may indicate on-demand SSB (e.g., w ith a certain slot offset from the triggering DCI and SSB timedomain parameters) or periodic SSB (e.g., UE to perform search). The UE may monitor periodic SSB since then. The trigger may be a MAC CE or a DCI. It can be sent to a group of UEs. The triggering and measurement mechanisms can be used for an unknow n or known SCell, and may or may not be directly tied to SCell activation. In some embodiments, the offset is associated with a delay between a slot (e.g., n+k) and a first on-demand burst of the SSB, for example a first SSB. The slot n denotes an ending slot for a message, such as a MAC CE message, and the slot (n+k) denotes one slot after decoding and processing of the message, such as the MAC CE message. The slots n and (n+k) are also illustrated in other figures, e.g., FIG. 8. The time offset between the triggering indication and the on-demand SSB may be designed similarly to the embodiments described for the scenario illustrated in FIG.20.

[0281] In some embodiments, the SCell is deactivated for a sufficiently long time and may have become unknown to the UE. For the deactivated SCell, before a SCell activation command, the network can inform the UE about the on-demand SSB via a DL signaling, which is called “on- demand SSB based measurement trigger” signaling in FIGs. 21 and 22, so that the UE can perform RF operations, AGC, (synchronization, and / or re-synchronization, and SSB-based RRM / L1 / L3 measurement for the SCell. As mentioned before, the measurement may be optional. The SCell can be unknown and may require a long time for activation without the on-demand SSB, but with this pre-activation on-demand triggering mechanism, it can become known to the UE, and hence the SCell can be activated using the fast SCell activation procedure from Rel-17 when needed, which is generally much faster. This would require a new DL signaling sent on an activated serving cell to inform the UE about the on-demand SSB for the deactivated SCell. The on-demand SSB for the deactivated SCell may be transmitted according to existing SSB transmission schedule and no additional SSB needs to be transmitted, that is, the triggering signaling can serve as an activation signaling for the UE to start monitoring the SSB for the SCell, which is the SSB defining this SCell, or an additional SSB (such as the NCD SSB) that may be transmitted according to configuration of the additional SSB and the parameters indicated in the new signaling.

[0282] In some sense, this use case is a bit similar to SCell fast activation based on on-demand AP SSB, but the on-demand SSB is moved before the activation SCell signaling. The triggering signaling and the synchronization and / or measurement procedures may not be directly tied to SCell activation, as the UE only needs to follow the network’s instruction and when and / or whether the network will activate the SCell is a network decision, but nevertheless this enhancement can significantly reduce SCell activation latency. From the UE perspective, it receives the triggering signaling, performs RF procedures, AGC, and / or synchronization based on the on-demand SSB, and in some embodiments sends a RRM / L1 / L3 measurement report for the deactivated SCell, all during the time when the SCell is still deactivated. The UE may assumeonly on-demand SSB, if triggered, will be transmitted during the SCell deactivation time, and otherwise (e.g., if on-demand SSB is not triggered) the UE does not assume the always-on SSB is transmitted for the deactivated SCell, thus enabling circumstances for network energy saving. Alternatively, there may still be an always-on SSB for the SCell but the periodicity is long. The on- demand SSB may be transmitted periodically since then, or for only a certain number of bursts or amount of time.Detailed Embodiments of On-demand SSB Designs Cases for SSB Transmissions

[0283] The WID describes on-demand SSB SCell operation, which implies that regular always-on SSB for the SCell is not available or insufficient at a certain moment in time. Thus, a question to clarify is why regular SSB for the SCell is insufficient. SSB is necessary for functionalities such as time and / or frequency synchronization, L1 / L3 measurements, and QCL source for the SCell. This is also related to the previous agreement to further clarify the availability of always-on SSB for the SCell.

[0284] - If the SSB is always on and periodically transmitted according to a standardized periodicity ranging from 5 ms to 160 ms, and if the UE monitors the always-on SSB whenever it deems necessary to maintain high synchronization accuracy and so on, the UE does not need to utilize on-demand SSB for the SCell. Time and / or frequency synchronization and Lt / L3 measurements can be maintained without any issue, and no on-demand SSB is needed.

[0285] - Therefore, on-demand SSB can be useful in the following cases:

[0286] — Excessively long always-on SSB periodicity for a SCell:

[0287] — Rel-tq may specify excessively long SSB periodicity for a SCell for NES purposes, such as w hen the SCell is deactivated, or the SCell is activated but in cell DTX or cell dormancy. The long period of SSB can still ensure the link on the SCell is maintained, but the synchronization accuracy may degrade to some degree at a certain time before the UE receives the next SSB transmission. If there is a need to utilize the SCell at this time, on-demand SSB can be useful.

[0288] — In this case, both the always-on SSB and the OD-SSB for the SCell are transmitted.

[0289] — To avoid significant standard impact, the always-on SSB for the SCell may be a CD-SSB, so that the SCell can operate as a commonly defined “cell.” However, the gNB may still configure the always-on SSB as an NCD SSB, in which case this SCell is not a commonly defined “cell” and does not support all cell functionalities, such as initial access, and the like. The standard impact for the always-on SSB being the NCD SSB can be more significant than that for the always- on SSB being a CD SSB, and the network and UE may need to implement more non-backward compatible operations, which may increase complexity. The CD always-on SSB can be configured as barred for legacy UEs since legacy UEs cannot access this cell anyway (e.g., due to the change of the CD SSB periodicity from the legacy values).

[0290] — The OD-SSB can be CD or NCD in principle. Either can work, and there is no backward compatibility issue. If the on-demand SSB is CD, which means it has the sameconfiguration, except for time-domain behavior, as the legacy periodic SSB for the SCell, it may reduce complexity in gNB and / or UE implementation and simplify specification effort. The CD on-demand SSB can be configured as barred for legacy UEs since legacy UEs cannot access this cell anyway (for example, due to the change of the always-on SSB). If the OD-SSB is NCD, it may be transmitted on the synchronization raster or off the synchronization raster, may include the PBCH or remove the PBCH. However, the DMRS may still be transmitted for measurement purposes, and may need to be configured as an alternative QCL source for TRS and other DL and / or UL transmissions. Though it can work, it leads to higher complexity in gNB and / or UE implementation and significant specification effort.

[0291] —No always-on SSB for a SCell:

[0292] — This case is similar to but generally worse than the above case. On-demand SSB is necessary' for such a SCell. This cell cannot be used by any legacy UE.

[0293] — The OD-SSB can be a CD SSB or an NCD SSB. Either can work, but the standard impact can be different. If the OD-SSB is the CD SSB, which means it has the same configuration, except for the time-domain behavior, as the legacy periodic SSB for the SCell, it can be configured as barred for legacy UEs. When the OD-SSB is transmitted periodically, most of the cell operations defined according to legacy standards can still be reused, which can help reduce network and UE complexity. When the SCell is configured for a UE or the SCell MIB and / or SIB parameters are updated, the configuration parameters may be sent in UE-specific RRC configuration signaling on another serving cell, or may be acquired by the UE using MIB and / or SIB on the SCell. Adopting CD on-demand SSB may be preferred. If the on-demand SSB is the NCD SSB, it may be transmitted on the synchronization raster or off the synchronization raster, may include the PBCH or remove the PBCH. However, the DMRS may still be transmitted for measurement purposes, and may need to be configured as an alternative QCL source for TRS and other DL and / or UL transmissions. All the configuration parameters needed for the UE to access this SCell and the NCD-SSB can be configured to the UE using RRC signaling sent on another serving cell.

[0294] — Even in legacy specifications, UE does not have to monitor every SSB transmission, though a UE assumes and / or expects that the SSB is transmitted according to the configured period and offset. For example, for a deactivated SCell without a configured measurement object, the UE does not monitor the SSB even though it knows the SSB is always-on and always there according to the schedule, and thus the cell may gradually become unknown.

[0295] It seems that “no always-on SSB for a SCell” is more suitable as a new UE assumption or a new UE behavior. For example, the new UE assumption may be that UE does not assume the availability of always-on SSB, or does not assume SSB is transmitted when the SCell is deactivated, or in cell DTX non-active period, or in cell dormancy, under certain network specified conditions. When the UE assumption is that the UE assumes SSB (e.g., regardless of periodic per MIB and / orSIB configuration or on-demand) is transmitted, the network has to transmit the SSB; if the SSB is periodic per MIB and / or SIB configuration, the UE behavior can be the same as legacy, such as leaving exactly when the SSB is monitored to UE implementation, but whenever the UE monitors the SSB, the SSB is indeed transmitted; if the SSB is on-demand, the UE is expected to monitor the SSB at least for the specified and / or indicated N burst(s) or T duration. When the UE assumption is that the UE may not, or does not, assume always-on SSB is transmitted or always- on SSB may be, or may not be, transmitted, the network can decide whether or not to transmit SSB, and the UE is not expected to monitor the SSB, though the UE can still attempt so. For another example, the new UE behavior on the monitoring of SSB may be that UE is not expected to monitor SSB when the SCell is deactivated, or in cell DTX non-active period, or in cell dormancy', under certain network specified conditions.

[0296] The cell with the OD-SSB may also need to support idle and / or inactive UEs that are camped under the cell. If the legacy AO-SSB is still available, legacy UEs and Rel-19 UEs can be supported in the cell. If the AO-SSB is modified in Rel-19 to have excessively long periodicity, to support the idle and / or inactive UEs, the OD-SSB with the same parameters as the AO-SSB can be transmitted at least in the slots on which the idle and / or inactive UEs are expected to monitor the cell based on their DRX and / or paging configurations. This works at least for Rel-19 UEs supporting NES features, but may also work for legacy UEs; for example, if all the time durations (e.g., which are configured for the idle and / or inactive UEs to monitor) contain OD-SSB, and the OD-SSB has the same parameters as legacy CD AO-SSB. For example, the SSBs in the slots for the paging occasions configured for a UE are still transmitted, though they are actually OD-SSB but appear identical as AO-SSB to the UE. Outside the paging occasions, generally the UE may not monitor the SSB, so the OD-SSB may not be transmitted, except for, e.g., AO-SSB with excessively long periodicity.

[0297] The following embodiments are therefore presented. Regarding the UE assumption on SSB transmission on a cell supporting on-demand SSB SCell operation, consider the following:

[0298] - Case #1: No always-on SSB on the cell.

[0299] - Case #2: Always-on SSB is periodically transmitted on the cell.

[0300] - Case #2A: Always-on SSB with excessively long periodicity.

[0301] - Case #2B: Always-on SSB is transmitted but UE is not expected to always monitor.Cell-defining (CD) or Non-Cell-defining (NCD)

[0302] For always-on SSB, CD SSB should be utilized, since otherwise, to be backward compatible and to avoid significant standards effort, another CD SSB (for example, which must be always-on) for the SCell has to be transmitted, diminishing the energy saving gain and increasing the complexity. For on-demand SSB, it can be CD or non-CD (NCD) as either can work and there is no backward compatibility issue. In an embodiment, the on-demand SSB is CD, which means it has the same configuration, except for time-domain behavior, as the legacyperiodic SSB for the SCell, it may need to be configured as barred for legacy UEs. The CD on- demand SSB can be a QCL source for TRS and other DL and / or UL transmissions, in addition to the CD always-on SSB (if any) as QCL source. When the CD on-demand SSB is not periodic or semi-persistent per activation, it may be configured with always-on CD SSB which is the QCL source for the on-demand SSB. In an embodiment, the on-demand SSB is NCD, it may need to be configured as an alternative QCL source for TRS and other DL and / or UL transmissions. It can include no PBCH but only PSS and SSS. It can be configured with CD SSB which is the QCL source for the NCD SSB.Triggering and Associated Signaling, Indication, and / or Configuration

[0303] There are several possible triggering methods in accordance w ith embodiments of the present disclosure. These methods and associated signaling and / or indication and / or configuration are discussed in the following.

[0304] -SCell activation signaling:

[0305] -Activation may be needed if the network decides to use the deactivated SCell for data transmission. The MAC activation signaling can serve as a trigger from the network to inform the UE to activate the SCell, which restores synchronization for the SCell and prepares the SCell for UL and / or DL data transmission. The MAC CE and its scheduling DCI can be sent on the Pcell or other activated non-dormant SCell. Different from legacy SCell activation MAC CE, a new SCell activation MAC CE is needed to include information about on-demand SSB transmissions so that the UE can receive and process the SSB properly. The information in some embodiments includes at least the availability of on-demand SSB, the time offset after the trigger, the number or duration of the SSB transmissions, beam (SSB-index) information if for FR2, and the like. The MAC CE may be an enhancement of Rel-17 SCell activation and / or deactivation MAC CE, by adding information about mi ( >0) AP SSB burst(s) transmitted before the m2 (>o) AP TRS burst(s) and their timing offset, or replacing the m2 (> 0) AP TRS burst(s) by mi (>o) AP SSB burst(s). For example, a set of parameter tuples are configured in the RRC, and each tuple indicates information about (e.g., tuple configuration ID, slot offset before SSB bursts, mi AP SSB, slot gap ti between the AP SSB bursts, slot gap ti2 between the end of SSB bursts and beginning of AP TRS bursts, m2 AP TRS, slot gap t2 between AP TRS bursts), where mi>o and m2>o. A tuple configuration ID may be carried in the MAC CE to indicate the associated on-demand SSB and / or TRS transmissions.

[0306] -DL signaling for on-demand SSB triggering:

[0307] -For a deactivated SCell, before (and in some contexts unrelated to) a SCell activation command, the network can inform the UE about the on-demand SSB via a DL signaling, so that the UE can perform synchronization, and / or re-synchronization, and / or SSB-based RRM measurement for the SCell. For example, the SCell may have been an unknown cell and require a long time for activation, but with this triggering mechanism, it can become known to the UE, andhence the SCell can be activated using the fast SCell activation procedure from Rel-17 when needed. This would require a new DL signaling, and since the SCell is still deactivated, the signaling and the procedure do not have to fast, so MAC CE can be used for this purpose. The MAC CE and its scheduling DCI can be sent on the Pcell or other activated non-dormant non- DTX SCell. The UE will start to search and / or monitor the SSB which is assumed as periodic after processing the MAC CE. The MAC CE may optionally request RRM measurement for the SCell report from the UE. The MAC CE may have a similar design as above SCell activation MAC CE, but a bitfield indicates that the SCell remains deactivated, and a set of tuples are configured in the form of tuple configuration ID, mi SSB, periodicity of SSB if different from the SSB periodicity when SCell is activated, and / or flag for RRM measurement reporting, where mt>o and could indicate no termination (e.g., the UE can monitor SSB for any indefinitely long time until otherwise signaled by the network). A tuple configuration ID may be carried in the MAC CE to indicate the associated on-demand SSB transmissions. The UE would then monitor mt on- demand SSB transmissions according to the indicated or configured periodicity .

[0308] -DCI for on-demand SSB triggering associated with on-demand Active Period in cell DTX or switching to non-dormant BWP:

[0309] —For an activated SCell in cell DTX, if the cell DTX cycle is configured as excessively long and the UE does not monitor SSB outside active period, or if the cell DTX cycle is not configured, the network can inform the UE about an on-demand SSB and on-demand active period. The UE can then reacquire and / or maintain synchronization based on the SSB, and then receive data during the on-demand active period. This is generally a faster process, so DCI can be used, and the DCI can be sent on the PCell or other activated non-dormant non-DTX SCell. The DCI may include information such as the availability of on-demand SSB, the time offset after the trigger, the number or duration of the SSB transmissions, beam (SSB-index) information if for FR2, the start of on-demand Active Period, and the like. Similarly, for an activated SCell in cell dormancy where the UE does not monitor SSB, a BWP switching DCI can be used to inform the UE about the availability of on-demand SSB (e.g., time offset, number of bursts, beam, and the like) and switching to a non-dormant BWP. Generally, the network may configure a set of tuples, each including at least one field of tuple configuration ID, slot offset before SSB bursts, mi AP SSB, slot gap ti between the AP SSB bursts, slot gap ti2 between the end of SSB bursts and beginning of AP TRS bursts, m2 AP TRS, slot gap t2 between AP TRS bursts, and / or slot offset t3 before Active Period starts, where mi>o and m2>o. In some embodiments, both mi and m2 are zero, in which case the DCI indicates an on-demand Active Period without preceding on-demand SSB, and regular SSB / TRS and other transmissions are expected during the Active Period.

[0310] For the above triggering methods, similar to Rel-17 SCell activation MAC CE design, relevant information can be configured via RRC, and then the MAC CE or DCI can use only a few bits to indicate and / or select from the configured options.

[0311] To summarize, for at least some of the embodiments, for the example enhancements of triggering mechanisms:

[0312] -For SCell fast activation based on on-demand SSB: A new SCell activation MAC CE may be utilized.

[0313] -For deactivated SCell operation based on on-demand SSB : A new MAC CE to activate on-demand SSB on a deactivated SCell maybe utilized.

[0314] -For on-demand SSB for activated SCell in cell DTX or dormancy: A new DCI to trigger on-demand SSB for on-demand active period (e.g., for SCell in cell DTX) or switching to a nondormant BWP (e.g., for SCell in cell dormancy).

[0315] -The MAC CE or DCI is sent on an activated non-dormant non-DTX cell, which selects options configured in RRC for at least the availability of on-demand SSB (e.g., time offset, number of bursts, beam, and the like).Embodiments for On-Demand SSB Transmission

[0316] A few embodiments for the on-demand SSB transmission can be considered, but for different use cases, different embodiments can be adopted.

[0317] -For use case of SCell fast activation: UE expects that on-demand SSB burst(s) is transmitted N times after time instance A (for example, which may be the slot k = kt + 3 Nsiot, subframe, u + 1 from the slot with the MAC CE), and regular periodic SSB is transmitted after the N on-demand SSB bursts are transmitted. Here N can be configurable, and the on-demand SSB bursts can have higher time-domain densities so that the UE can complete the on-demand SSB based SCell activation faster. For example, the SSBs can be sent on DL or flexible slots with indicated gap durations. When the gap duration is, e.g., 2 ms, the SSBs will be every 2 ms apart from each other, which has much higher time-domain density than any legacy SSB transmissions. The gap duration may be alternatively specified as a number of slots. When a SSB transmission according to the gap and the immediate previous SSB transmission is on a slot that the SSB cannot be accommodated, the SSB may be delayed for one cycle (e.g., delayed for 2 ms) and the same N is maintained, or the SSB may be delayed to the next immediately available slot for the SSB and the same N is maintained. In order for the UE to know the most up-to-date information of the slot format (e.g., DL, UL, or flexible, and the like), the slot format indicator (SFI) may also be included in the MAC CE for activation.

[0318] -For use case of on-demand SSB for a deactivated SCell: UE expects that on-demand SSB burst(s) is periodically transmitted from time instance A (for example, which is generally the slot k = kt + 3 Nsiot, subframe, u + 1 from the slot with the MAC CE), until gNB turns OFF the on- demand SSB via a DL signaling or a timer expires or N SSBs have been received. The DL signaling for triggering the on-demand SSB can include the SCell index, SSB periodicity (for example, which can be longer than the SSB periodicity configured for the SCell when activated), the number N (for example, which can be finite or indefinite) or the duration T (for example, which can befinite or indefinite). If N or T is zero or the signaling indicating “no monitoring of SSB”, and if the UE is monitoring the SSB, then the UE starts assuming that the SSB may not be transmitted since then, and the UE is not expected to perform SSB-based operations. If N or T is indefinite or the signaling indicating “monitoring of SSB”, the UE assumes that SSB is periodically transmitted since then (e.g., as a semi-persistent SSB per activation), and the UE is expected to perform SSB- based operations, until the UE is signaled with information to indicate otherw ise. In other words, the UE can be signaled by the network to monitor or not monitor SSB on a deactivated SCell, and when monitoring, the SSB may be sent in a different periodicity as the SSB when the SCell is activated.

[0319] -For use case of on-demand SSB for an activated SCell: UE expects that on-demand SSB burst(s) is transmitted N times after the DCI, and regular periodic SSB is transmitted after the N on-demand SSB bursts are transmitted. Here N can be configurable, and the on-demand SSB bursts can have higher time-domain densities so that the UE can complete the on-demand SSB based operations faster. For example, the SSBs can be sent on DL or flexible slots with indicated gap durations. When the gap duration is, e.g., 2 ms, the SSBs will be every 2 ms apart from each other, which has much higher time-domain density than any legacy SSB transmissions. The gap duration may be alternatively specified as a number of slots. When a SSB transmission according to the gap and the immediate previous SSB transmission is on a slot that the SSB cannot be accommodated, the SSB may be delayed for one cy cle (e.g., delayed for 2 ms) and the same N is maintained, or the SSB may be delayed to the next immediately available slot for the SSB and the same N is maintained. In order for the UE to know the most up-to-date information of the slot format (e.g., DL, UL, or flexible, and the like), the slot format indicator (SFI) may7also be included in the DCI. The DCI can include the SCell index, SSB periodicity (for example, which can be shorter than the SSB periodicity configured for the SCell when the SCell is in continuous transmission and / or reception or within Active Period or is non-dormant), the number N (for example, which can be finite or indefinite) or the duration T (for example, which can be finite or indefinite). If N or T is zero or the signaling indicating “no monitoring of SSB” or cell DTX nonActive Period or a dormant BWP or an inactivity timer expires, and if the UE is monitoring the SSB, then the UE starts assuming that the SSB may not be transmitted since then, and the UE is not expected to perform SSB-based operations. If N or T is indefinite or the signaling indicating “monitoring of SSB” or cell DTX Active Period or a non-dormant BWP or leaving cell DTX to become continuously transmitting and / or receiving, the UE assumes that SSB is periodically transmitted since then (e.g., as a semi-persistent SSB per activation), and the UE is expected to perform SSB-based operations, until the UE is signaled with information to indicate otherwise. In other words, the UE can be signaled and / or configured by the network to monitor or not monitor SSB on an activated SCell.

[0320] In the above embodiments of OD-SSB indication, signaling, and / or configuration, thetime offset may be a slot offset and / or symbol offsets, e.g., 2 slots, 7 symbols, 2 slots + 7 symbols, and the like. The offset may be configured in the OD-SSB RRC configuration, e.g., the RRC configuration may configure {OD-SSB configuration parameters, OD-SSB configuration ID, offset = 2 slots}. Then, in the MAC CE or DCI indicating the OD-SSB, only the OD-SSB configuration ID needs to be indicated in some embodiments, reducing the signaling overhead. Alternatively , a set of offsets may be configured and / or allowed in the OD-SSB RRC configuration, e.g., the RRC configuration may configure {OD-SSB configuration parameters, OD-SSB configuration ID, offsets = {0, 1, 2, 4} slots}. Then, in the MAC CE or DCI indicating the OD-SSB, the OD-SSB configuration ID and an index (e.g., from 0 to 3) of an offset need to be indicated in some embodiments, so that the corresponding offset is selected for the OD-SSB configuration, which has a bit higher signaling overhead but more flexibility. Alternatively, no offset may be configured in the OD-SSB RRC configuration, e.g., the RRC configuration may configure {OD- SSB configuration parameters, OD-SSB configuration ID}. Then in the MAC CE or DCI indicating the OD-SSB, the OD-SSB configuration ID and an index of an offset as pre-defined in the standards or an absolute slot offset value (e.g., 2 slots) can be indicated, which has even higher signaling overhead but highest flexibility. Likewise, for the number of OD-SSB transmissions, time gap in between, and the like, can be configured explicitly in the RRC configuration, or a set of candidate values can be configured and one of them is indicated via the MAC CE or DCI, or are not configured in the RRC configuration but indicated via the MAC CE or DCI based on standardized values or via their absolute value.

[0321] To summarize the embodiments, for on-demand SSB transmission, at least support UE expects that on-demand SSB burst(s) is transmitted N (>o) times after the MAC CE or DCI, followed by periodic SSB transmission.

[0322] An issue to be addressed is the relation between the always-on SSB and the OD-SSB. In the legacy specs, many signals, channels, and operations rely on SSB, which is now referred to as the always-on SSB in this disclosure. Now, if on a cell, only the OD-SSB is present, then all the reliance on the always-on SSB can be updated to rely on the OD-SSB, which could lead to significant standards impact if the OD-SSB design and functionalities differ considerably from the always-on SSB. If, however, on a cell, both the OD-SSB and the always-on SSB are present, which one to be used for which operation may need to be decided. This can again lead to significant standards impact.

[0323] An embodiment technique that can simplify standards effort and gNB and / or UE designs is to establish a certain equivalent and / or consistent relation between the always-on SSB and the OD-SSB. For example, in most typical cases, the design of the OD-SSB can ensure that the OD-SSB is generally interchangeable with the always-on SSB. The OD-SSB has the same time and / or frequency-domain synchronization as the always-on SSB, so either one or both can be used for time and / or frequency synchronization. The OD-SSB can be QCLed with the always-onSSB for the same cell, and all signals and channels QCLed w ith the always-on SSB are also QCLed w ith the OD-SSB. For legacy measurement and measurement reporting designed for the always- on SSB, when the OD-SSB is available, the UE can also utilize the OD-SSB but account for example time-domain differences (if any) accordingly.

[0324] In some cases, an OD-SSB cannot provide the complete cell-level functionalities as the always-on SSB, e.g., when the OD-SSB is an NCD SSB and / or off the synchronization raster so that it cannot be used for initial access or UE camping procedure. In some other cases, the new OD-SSB can support new functionalities and operations not introduced for the always-on SSB, e.g., in OD-SSB based SCell activation, or when a new measurement reporting is defined only for the OD-SSB, and the like.

[0325] Overall, the relation between the always-on SSB and the OD-SSB can be clarifies. For a connected UE, all the functionalities and operations defined for always-on SSB can be fulfilled using the on-demand SSB, e.g., generally on-demand SSB can be an interchangeable QCL source as always-on SSB.

[0326] In an embodiment, the OD-SSB has the same transmission power as the always-on SSB, and the UE can derive the same L1 / L3 measurement, the same pathloss estimate, and other signals’ transmission powers based on either one or both SSBs. There is no need for the network to signal the transmission power of the OD-SSB in this case. In another embodiment, the OD- SSB can have a different transmission power as the always-on SSB, and the power offset is signaled to the UE when configuring or indicating the OD-SSB. Allowing a power offset can provide the network with the capability to boost the OD-SSB power whenever needed. The UE can account for the power offset when deriving L1 / L3 measurement, pathloss estimate, and other signals’ transmission powers based on the OD-SSB.

[0327] To establish certain equivalent relation between the always-on SSB and the OD-SSB for the same cell, the following embodiments can be implemented. If a UE configured with an OD-SSB for a serving cell, the UE operating in this serving cell uses this OD-SSB for the purposes for which it would otherwise have used the AO-SSB of the serving cell (e.g. obtaining sync, measurements, RLM, BFD, beam management). Furthermore, other signals, channels, operations, and / or procedures that depend on and / or refer to an SSB in legacy standards or an AO-SSB (e.g. the "SSB" configured in the QCL-Info IE; the "ssb-Index" configured in the RadioLinkMonitoringRS; CFRA-SSB-Resource; PRACH-ResourceDedicatedBFR) depend on and / or refer to this OD-SSB. When both the AO-SSB and the OD-SSB are present, either or both can be used for above purposes unless certain new properties and / or functionalities are introduced in Rel-19 for one of them. The OD-SSB has the same values for the properties (e.g., ssb-PositionsInBurst, PCI, ssb-PBCH-BlockPower) of the corresponding CD-SSB apart from the values of the properties newly introduced in Rel-19. In the MIB associated with this OD-SSB, the systemFrameNumber field indicates the frame boundary and frame number of the OD-SSB. ThesubCarrierSpacingCommon and dmrs-TypeA-Position field in the MIBs associated w ith AO-SSB and OD-SSB in the same cell are configured with the same values, respectively.

[0328] An AO-SSB may be a CD SSB or an NCD SSB. An OD-SSB may be a CD SSB or an NCD SSB. A CD-SSB may be AO or OD. A NCD-SSB may be AO or OD. In addition, they can be on or off the synchronization raster, they can include the PBCH and / or MIB transmission or omit it (except for CD-SSB). They may allow the legacy UE to access or be barred from legacy UE access. There are a number of combinations, and they may be utilized in different cases. A summary of some examples is shown in the table in FIG. 24.

[0329] Reduced capability (RedCap) UEs and some non-RedCap UEs may support BWP operation without a CD-SSB within its active BWP. For those UEs, they may perform Beam Management (BM), Radio Link Monitoring (RLM), and Beam Failure Detection (BFD) operations based on SSB outside active BWP with or without interruptions, or perform BM, RLM, and / or BFD based on NCD-SSB within active BWP. OD-SSB may be supported for those UEs. For example, the UE may perform BM, RLM, and / or BFD operations based on OD-SSB outside active BWP with or without interruptions, and the OD-SSB may be CD or NCD; or the UE may perform BM, RLM, and / or BFD based on oD-SSB within active BWP, and the OD-SSB may be NCD.

[0330] FIG. 11 illustrates an example communication system 1100. In general, the system 1100 enables multiple wireless or wired users to transmit and receive data and other content. The system 1100 may implement 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), or non-orthogonal multiple access (NOMA).

[0331] In this example, the communication system 1100 includes electronic devices (ED) inoa-inoc, radio access networks (RANs) H2oa-ii2ob, a core network 1130, a public switched telephone network (PSTN) 1140, the Internet 1150, and other networks 1160. While certain numbers of these components or elements are shown in FIG. 11, any number of these components or elements may be included in the system 1100.

[0332] The EDs inoa-inoc are configured to operate or communicate in the system 1100. For example, the EDs inoa-inoc are configured to transmit or receive via wireless or wired communication channels. Each ED inoa-inoc represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, or consumer electronics device.

[0333] The RANs H2oa-ii2ob here include base stations ti oa-iiyob, respectively. Each base station li oa-ti ob is configured to wirelessly interface with one or more of the EDs 1110a- 1110c to enable access to the core network 1130, the PSTN 1140, the Internet 1150, or the othernetworks 1160. For example, the base stations ti / oa-ii ob may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a gNB centralized unit (gNB-CU), a gNB distributed unit (gNB-DU), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs liioa-iitoc are configured to interface and communicate w ith the Internet 1150 and may access the core network 1130, the PSTN 1140, or the other networks 1160.

[0334] In the embodiment show n in FIG. 11, the base station 1170a forms part of the RAN 1120a, which may include other base stations, elements, or devices. Also, the base station 1170b forms part of the RAN 1120b, which may include other base stations, elements, or devices. Each base station H7oa-H7ob operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multipleinput multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

[0335] The base stations nyoa-nyob communicate with one or more of the EDs iiioa-moc over one or more air interfaces 1190 using wireless communication links. The air interfaces 1190 may utilize any suitable radio access technology.

[0336] It is contemplated that the system 1100 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New7Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

[0337] The RANs H2oa-H2ob are in communication with the core network 1130 to provide the EDs iiioa-moc with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs H2oa-H2ob or the core network 1130 may be in direct or indirect communication with one or more other RANs (not shown). The core network 1130 may also serve as a gateway access for other networks (such as the PSTN 1140, the Internet 1150, and the other networks 1160). In addition, some or all of the EDs liioa-inoc may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 1150.

[0338] Although FIG. 11 illustrates one example of a communication system, various changes may be made to FIG. 11. For example, the communication system 1100 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0339] FIGs. 12A and 12B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, FIG. 12A illustrates an example ED 1210, and FIG. 12B illustrates an example base station 1270. These components could be used in the system1100 or in any other suitable system.

[0340] As shown in FIG. 12A, the ED 1210 includes at least one processing unit 1200. The processing unit 1200 implements various processing operations of the ED 1210. For example, the processing unit 1200 could perform signal coding, data processing, power control, input / output processing, or any other functionality enabling the ED 1210 to operate in the system 1100. The processing unit 1200 also supports the methods and teachings described in more detail above. Each processing unit 1200 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1200 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0341] The ED 1210 also includes at least one transceiver 1202. The transceiver 1202 is configured to modulate data or other content for transmission by at least one antenna or Network Interface Controller (NIC) 1204. The transceiver 1202 is also configured to demodulate data or other content received by the at least one antenna 1204. Each transceiver 1202 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 1204 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 1202 could be used in the ED 1210, and one or multiple antennas 1204 could be used in the ED 1210. Although shown as a single functional unit, a transceiver 1202 could also be implemented using at least one transmitter and at least one separate receiver.

[0342] The ED 1210 further includes one or more input / output devices 1206 or interfaces (such as a wired interface to the Internet 1150). The input / output devices 1206 facilitate interaction with a user or other devices (e.g., network communications) in the network. Each input / output device 1206 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

[0343] In addition, the ED 1210 includes at least one memory 1208. The memory 1208 stores instructions and data used, generated, or collected by the ED 1210. For example, the memory 1208 could store software or firmware instructions executed by the processing unit(s) 1200 and data used to reduce or eliminate interference in incoming signals. Each memory 1208 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.

[0344] As shown in FIG. 12B, the base station 1270 includes at least one processing unit 1250, at least one transceiver 1252, which includes functionality’ for a transmitter and a receiver, one or more antennas 1256, at least one memory 1258, and one or more input / output devices orinterfaces 1266. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 1250. The scheduler could be included within or operated separately from the base station 1270. The processing unit 1250 implements various processing operations of the base station 1270, such as signal coding, data processing, power control, input / output processing, or any other functionality. The processing unit 1250 can also support the methods and teachings described in more detail above. Each processing unit 1250 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1250 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0345] Each transceiver 1252 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1252 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 1252, a transmitter and a receiver could be separate components. Each antenna 1256 includes any suitable structure for transmitting or receiving wireless or w ired signals. While a common antenna 1256 is shown here as being coupled to the transceiver 1252, one or more antennas 1256 could be coupled to the transceiver(s) 1252, allowing separate antennas 1256 to be coupled to the transmitter and the receiver if equipped as separate components. Each memory 1258 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input / output device 1266 facilitates interaction with a user or other devices (network communications) in the network. Each input / output device 1266 includes any suitable structure for providing information to or receiving and / or providing information from a user, including network interface communications.

[0346] FIG. 13 is a block diagram of a computing system 1300 that may be used for implementing the devices and methods disclosed herein. For example, the computing system in some embodiments is any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, and the like. The computing system 1300 includes a processing unit 1302. The processing unit includes a central processing unit (CPU) 1314, memoiy 1308, and may further include a mass storage device 1304, a video adapter 1310, and an I / O interface 1312 connected to a bus 1320.

[0347] The bus 1320 may be one or more of any type of several bus architectures including a memoiy bus or memory controller, a peripheral bus, or a video bus. The CPU 1314 may comprise any type of electronic data processor. The memoiy 1308 may comprise any type of non-transitoiy system memoiy such as static random access memory7(SRAM), dynamic random access memoiy (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. Inan embodiment, the memory 1308 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

[0348] The mass storage 1304 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1320. The mass storage 1304 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0349] The video adapter 1310 and the I / O interface 1312 provide interfaces to couple external input and output devices to the processing unit 1302. As illustrated, examples of input and output devices include a display 1318 coupled to the video adapter 1310 and a mouse, keyboard, or printer 1316 coupled to the I / O interface 1312. Other devices may be coupled to the processing unit 1302, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

[0350] The processing unit 1302 also includes one or more network interfaces 1306, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1306 allow the processing unit 1302 to communicate with remote units via the networks. For example, the network interfaces 1306 may provide wireless communication via one or more transmitters and / or transmit antennas and one or more receivers and / or receive antennas. In an embodiment, the processing unit 1302 is coupled to a local-area network 1322 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0351] It will be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a performing unit or module, a generating unit or module, an obtaining unit or module, a setting unit or module, an adjusting unit or module, an increasing unit or module, a decreasing unit or module, a determining unit or module, a modifying unit or module, a reducing unit or module, a removing unit or module, or a selecting unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application -specific integrated circuits (ASICs).

[0352] Although the description has been described in detail, it should be understood that various changes, substitutions, and / or alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to bedeveloped, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.ADDITIONAL NETWORK ENERGY SAVINGS WORK ITEM

[0353] Further discussion of procedures and signaling method(s) to support on-demand SIBt for UEs in idle and / or inactive mode is further addressed below. This includes:

[0354] Triggering method by uplink wake-up-signal using an existing signal and / or channel.

[0355] Wake-up-signal configuration provisioning to UE. Note: No modification of SSB will be discussed under this objective.

[0356] Information exchange between gNBs at least for the configuration of wake-up signal, if necessary'.

[0357] Further herein this disclosure, details of on-demand SIB1 for idle and / or inactive mode UEs is analyzed and discussed

[0358] Herein the disclosure discusses a basic setup of the deployment scenarios, analyses the feasibility of some of the operations, and summarizes certain enhancements. Some of the existing specifications, mainly for PBCH / MIB / idle / inactive design, are provided for information herein.Deployment scenarios

[0359] The first stage clarifies and aligns the deployment scenarios for example enhancements. Consider at least two cells in the network, called Cell A and Cell B (also known as NES Cell). For Cell A: Cell A periodically transmits at least its own legacy SSB and SIBs (for example, including SIBt), and operates according to legacy specifications without the NES feature of turning off its SSB and SIBs. Therefore, Cell A can be used for initial access for legacy and / or new UEs. Cell A may provide wake-up signal (WUS) configuration or assistance (such as timing) to UEs for accessing other cells (e.g., Cell B).

[0360] For Cell B: Cell B may transmit SIBt transmission in response to UL WUS from a UE. It does not transmit at least the legacy periodic SIBs, including SIBt. In other words, Cell B can turn off its SIBs, for, e.g., NES purposes. Cell B cannot be used for initial access for legacy UEs.

[0361] With respect to the relationship between Cell A and Cell B: Cell A and Cell B can be collocated and share certain components, and they may be intra-band CA carriers or inter-band CA carriers, or they can be non-collocated as neighbor cells. They may share certain properties, such as the same timing, same large-scale fading, and the like, or not share common properties. The example enhancements in some circumstances are different based on different relationships between Cell A and Cell B.SSB transmission on Cell B

[0362] An initial question is whether and / or how SSB is transmitted on Cell B.

[0363] 01: Whether and / or how SSB is transmitted on Cell B?

[0364] There are a couple of cases, and it should be considered whether such cases pose any backward compatibility issue.

[0365] In a first option, Cell B SSB is still transmitted periodically when its SIB1 is turned off. In a second option, Cell B SSB is always-on, regardless of Cell B SIB1 on and / or off status. For legacy UE in idle and / or inactive mode, if it monitors Cell B SSB but it will not be able to find associated SIBi, to avoid backward compatibility issue, Cell B has to be properly configured.

[0366] For most legacy UEs, when finding the cell is ‘barred’, they will perform cell reselection.For legacy RedCap UEs, when finding the cell is ‘barred’, they will check the field ssb- SubcarrierOffset. If the field indicates no SIBi, it will continue to read the field pdcch-ConfigSIBt, based on which it may find information for a cell defining (CD) SSB, implying that the current SSB is a non-cell defining (NCD) SSB, or it may not find information for CD SSB, implying that the current frequency range does not provide SIBi for the SSB. No issue will be encountered. For Rel-18 UEs capable of NES cell DTX / DRX, when finding the cell is ‘barred’, they will apply the information from the fields ssb-SubcarrierOffset and pdcch-ConfigSIBt to acquire SIBi. If the fields indicate the presence of SIBi but they cannot find SIBi, this could be an issue. To prevent the issue, the field ssb-SubcarrierOffset in some embodiments indicates the absence of SIBi.

[0367] Thus, Cell B can be configured as a barred cell with the field ssb-SubcarrierOffset indicating the absence of SIBi, so that legacy UEs will not experience issues due to the missing SIB for the SSB. There could be other configurations to prevent backward compatibility issue.

[0368] For Rel-19 UE supporting on-demand SIBi feature in idle, inactive, and / or connected mode, they can ignore the field cellBarred and the absence of SIBi indication from the field ssb- SubcarrierOffset. There is no issue with only receiving SSB, and new designs can be provided for on-demand SIB transmission.

[0369] In a third option, Cell B SSB is not transmitted when its SIBi is turned off. For example, Cell B SSB is turned on or off at the same time and in the same way as Cell B SIBi is turned on or off. In other words, Cell B SSB and SIBi are not always on, and they can be transmitted in an on- demand fashion. In some embodiments, Cell B may have no always-on SSB, and that affects not only connected UEs but also inactive and / or idle UEs, unless such a cell allows no UEs to camp under it or preform initial access with it, which seems a bit too restrictive. It does not seem very reasonable that a UE expects always-on SSB during inactive and / or idle state from a NES Cell but may not have always-on SSB during connected state.

[0370] The turning-off can be done when the network determines all connected UEs (if any) are compatible with this feature. There will not be backward compatibility issue for such UEs. Inactive UEs and idle UEs not supporting this feature may wake up to look for the SSB for synchronization and subsequent operations such as paging, but they could not find the SSB. This prevents them from paging or performing RACH. These UE will perform a cell reselection whichis an existing behavior. This may cause some delay and complexity, but it seems there will not be critical issues for such UEs.

[0371] Inactive UEs and idle UEs camped under this cell and supporting this feature may be relying on Cell B SSB for its synchronization, paging, and the like. These UEs may be informed, or otherwise know, that Cell B SSB can be turned off, and they can use the new designs from this WI (e.g., using WUS to request on-demand SSB and SIB from Cell B) to ensure proper operations. Though legacy UEs may camp under Cell B and may also be connected to Cell B when the SSB / SIB are transmitted, it may limit Cell B’s flexibility to turn off its SSB / SIB. For this reason, Cell B may prevent legacy UEs from camping or connecting to it, via its MIB by configuring the cell as barred or SIB1 absent using MIB fields cellBarred and / or ssb-SubcarrierOffset. However, this may not be strictly necessary and in some embodiments can be left for network implementation.

[0372] Thus, both cases are feasible and will not lead to backward compatibility issue with proper configuration and / or enhancements.

[0373] For example enhancements of on-demand SIB1 of a cell for UEs in idle and / or inactive mode, consider at least the following two scenarios for the cell’s SSB: The cell’s SSB is always on (e.g., transmitted periodically regardless of its SIB1 on and / or off status). This cell’s MIB may be configured to indicate the cell as barred and / or SIBi absent to avoid backward compatibility issue. The cell does not transmit always-on SSB and transmits on-demand SSB and SIBi, and one of SSB / SIB1 is transmitted only when the other is transmitted.WUS configuration for Cell B

[0374] The next question to address is which cell, Cell A or Cell B, provides the WUS configuration for Cell B.

[0375] O2: Which cell can provide WUS configuration to UEs for Cell B?

[0376] Both cases are analyzed herein.

[0377] A first case for question two is a WUS configuration is provided by Cell B. If the UE is inactive and stores information received from Cell B when it was connected to Cell B, the WUS configuration information for Cell B maybe included in some configuration information, and Cell B may or may not need to use its SIB (e.g., when SIB is transmitted) to broadcast the WUS configuration information for Cell B. Otherwise, the UE is inactive or idle, it may read Cell B’s SIB when it is transmitted (e.g., which can be intermittent). The SIB may include the WUS configuration information for Cell B. However, the WUS configuration information transmission cannot be purely on-demand based, otherwise the UE may not be able to receive the WUS configuration information and hence cannot be camped under this cell at all. Thus, the WUS configuration information transmission in some embodiments is also at least periodic. To enable more energy saving, Cell B can configure long periodicity for SIB as well as on-demand SIB, and SIB carries WUS configuration information.

[0378] A second case for question two is a WUS configuration is provided by Cell A. Forexample, if the UE is idle and camped under Cell A, it may read Cell A’s SIB broadcast to all UEs which may include WUS configuration information for Cell B. If the UE is inactive and stores information received from Cell A when it was connected to Cell A, the WUS configuration information for Cell B may be included in some configuration information, and in this case, the UE does not have to monitor Cell A SIB for the WUS configuration information for Cell B, though in other circumstances it may be beneficial to do so. If the UE is inactive and does not store WUS configuration information for Cell B, it may read Cell A’s SIB broadcast to all UEs which may include WUS configuration information for Cell B. Consequently, Cell B does not have to periodically broadcast WUS configuration information for itself. Hence, Cell B SIB can operate on a purely on-demand basis, and when Cell B SIB is transmitted, it can also carrier WUS configuration information for itself. Cell B can also send and / or update its connected UEs with WUS configuration information for itself.

[0379] For example enhancements of on-demand SIB1 of a cell for UEs in idle and / or inactive mode, consider at least the following two scenarios for the WUS configuration for the cell. In some embodiments, a WUS configuration for the cell may be provided by an assisting cell: In the assisting cell’s broadcast SIB (e.g., with long periodicity) or other configuration signaling when the UE was connected to the assisting cell. In some embodiments, a WUS configuration for the cell may be provided by the same cell: In this cell’s broadcast SIB or other configuration signaling when the UE was connected to the cell.WUS transmission reference and target cell

[0380] WUS transmission is discussed further below. There are two key and related aspects: WUS transmission reference: WUS transmission reference refers to the DL synchronization, time and / or frequency reference points for WUS resources, DL RS for PL estimate used in WUS power control, and the like. Generally, the reference is based on SSB, at least for idle and / or inactive UEs. Then it should be considered which cell’s SSB, Cell B’s SSB or Cell A’s SSB, should be used as the WUS transmission reference.

[0381] WUS transmission target cell: The discussion below clarifies to which cell, Cell A or Cell B, the WUS from the UE for Cell B is transmitted.

[0382] Qq: Which cell’s SSB provides the reference for the WUS transmission, and to which cell the WUS for Cell B is transmitted?

[0383] In some embodiments, the WUS transmission reference is Cell B SSB, and target is also Cell B. If the WUS is transmitted to Cell B and Cell B SSB is always on, the UE can acquire DL synchronization and PL estimate from Cell B SSB, and the WUS transmission opportunities are relative to Cell B SSB location in time-frequency domain. It is infeasible to use Cell B SSB as WUS transmission reference if Cell B SSB operates only as on-demand SSB. The UE may not be able to find the on-demand SSB and may not be able to acquire sufficiently accurate synchronization for its WUS transmission. Thus, Cell B SSB should, in some embodiments, bealways on to be the WUS transmission reference. The WUS transmission to Cell B is only needed when Cell B SIB is not being transmitted. Thus, if Cell B SIB operates purely as on-demand SIB, or Cell B SIB transmission is configured w ith long periodicity, WUS transmission can be allowed.

[0384] In some embodiments, the WUS transmission reference is Cell A SSB, and target is also Cell A. Cell A SSB is always on, so if needed, it can act as WUS transmission reference. If the WUS is to be transmitted to Cell A, the UE can acquire DL synchronization and PL estimate from Cell A SSB, and the WUS transmission opportunities are relative to Cell A SSB location in timefrequency domain. In this case, Cell B SSB should, in some embodiments, not be always on (e.g., to save energy, as it is not used in WUS transmission), otherwise it makes more sense to utilize Cell B SSB. Cell B SSB should, in some embodiments, be transmitted only in an on-demand fashion to reduce energy consumption.

[0385] In some embodiments, the WUS transmission reference is Cell A SSB, and target is Cell B. If the WUS is to be transmitted to Cell B and Cell B SSB is not always on (e.g., supporting only on-demand transmission), the UE cannot acquire DL synchronization and PL estimate directly from Cell B. It may acquire DL synchronization and time and / or frequency reference points from Cell A SSB, if both cells are synchronized and / or coordinated. The PL estimate based on Cell A SSB may not be exact for WUS transmission toward Cell B. However, this can still be overcome via network implementation or some standards support, such as starting the WUS transmission with relatively low power but ramping up the power if needed. In this case, WUS transmission toward Cell B may still be feasible, though it is more involved than other cases.

[0386] For example enhancements of on-demand SIBi for UEs in idle and / or inactive mode, consider at least the following scenarios for the WUS transmission reference and target cell. In some embodiments, the WUS transmission target cell is the cell supporting on-demand SIBi. The WUS transmission reference is this cell’s SSB, if this cell’s SSB is always on. The WUS transmission reference is an assisting cell’s SSB, if the cells are synchronized and the target cell SSB is only on-demand and not always on. In some embodiments, the WUS transmission target cell is an assisting cell. The WUS transmission reference is the assisting cell’s SSB.

[0387] In some contexts, the SSB of the cell supporting on-demand SIBi is not always on.Summary of scenarios and enhancements

[0388] There can be a variety of scenarios for various example on-demand SIBi enhancements. These scenarios and associated operations are summarized in Table 2 below.Table 2 Example scenarios with on-demand SIBi

[0389] More detailed descriptions with respect to such scenarios follow. In a first scenario: Single-cell scenario (standalone; without an assisting cell, or optionally with an assisting cell). Cell B is a standalone cell for Rel-19 UEs and can provide all essential functions, including transmitting WUS configuration and receiving WUS transmission. Cell B always transmits SSB, e.g., SSB is always on, such as with the legacy periodicity of 20 ms. Cell B does not always transmit SIBi or WUS configuration when SSB is transmitted; instead, SIBi can be transmitted with much longer periodicity than SSB and can also be triggered by WUS. For example, SIBi and WUS configuration are broadcast with 1280 ms periodicity to reduce energy consumption, and in addition, SIBi can be sent on-demand per request from UE WUS. When SIBi and other SIBs are transmitted, WUS configuration for Cell B is included. Cell B always monitors potential WUS transmissions on its configured WUS transmission opportunities. WUS transmission opportunity is only configured on the time-domain resources when Cell B SIB is not transmitting, e.g., within a duration between consecutive periodic SIBi bursts occurring with long periodicity.

[0390] Continuing the first scenario, a Rel-19 UE receives and stores Cell B’s SI and WUS configuration information acquired from SIBs (for example, for idle, inactive, and / or connected UEs), and optionally from other RRC configuration signaling (for example, only for connected UEs). When needed, the UE transmits WUS to this cell based on this cell’s SSB. Cell B receives the WUS and then performs on-demand SIBi transmission. In general, the WUS configuration validity duration in some embodiments is longer than SIBi validity duration. Optionally, an assisting cell, Cell A, provides WUS configuration information for Cell B, in Cell A’s SIBs or other configuration information. Cell B is configured as inaccessible by legacy UE, by configuring the cell’s MIB as barred and / or SIBi absent.

[0391] In a second scenario: Multi-cell scenario with limited essential assistance from an assisting cell. Cell B is a non-standalone cell for Rel-19 UEs and relies on Cell A to broadcast WUS configuration for Cell B. Cell B transmits always-on SSB, and also transmits SIBi / SIBs / WUS configuration on an on-demand basis, but does not configure periodic SIBi / SIBs / WUS configuration transmission. Cell B monitors WUS, and when detected, it transmits SIBi / SIBs / WUS configuration.

[0392] Continuing the second scenario, when SIBi and other SIBs are transmitted, WUS configuration for Cell B is included, but since the transmission is on-demand, most UEs may not receive it. Hence an assisting cell, Cell A is needed to periodically broadcast WUS configuration information for Cell B. WUS is configured to be based on Cell B SSB and is monitored by Cell B.[03931 Continuing the second scenario, a Rel-19 UE receives and stores WUS configuration information for Cell B from Cell A. The UE monitors Cell B SSB. When needed, the UE transmits WUS to Cell B based on Cell B SSB. Cell B then performs on-demand SIB1 and other SIBs transmissions and UE receives the transmissions. Cell B is configured as inaccessible by legacy UE, by configuring the cell’s MIB as barred or SIB1 absent.

[0394] In a third scenario: Multi-cell scenario w ith full assistance from an assisting cell. Cell B is a non-standalone cell for Rel-19 UEs and its SSB / SIB1 transmissions are only on an on- demand basis. It relies on Cell A for all, or almost all, WUS-related operations. Cell B can save more energy in this scenario than in the other scenarios. When SSB, SIB1, and other SIBs are transmitted by Cell B, WUS configuration for Cell B is included; however, as these transmissions are only on an on-demand basis, most UEs cannot receive them. For this reason, Cell B SSB cannot be used as WUS reference.

[0395] Continuing the third scenario, WUS configuration for Cell B is broadcast by an assisting cell, Cell A, which does not turn off its SSB / SIBt / SIBs transmission, and the WUS configuration can be included in SIB1 or other SIBs. WUS transmission reference and target are also Cell A. Cell A monitors potential WUS transmissions for Cell B on the configured WUS transmission opportunities. Rel-19 UE receives and stores SI and WUS configuration information for Cell B from Cell A. When needed, the UE transmits WUS based on Cell A SSB. Cell A then receives the WUS for Cell B and informs Cell B. Cell B then performs on-demand SSB and SIBt transmission. Alternatively, if Cell A and Cell B are synchronized and coordinated, Cell B can monitor and receive WUS transmission. This way, Cell B can start on-demand SSB and SIBt transmission without waiting for backhaul signaling from Cell A. The cell may be configured as inaccessible by legacy UE.

[0396] The following example scenarios and enhancements of a cell with on-demand SIBt for UEs in idle and / or inactive mode may also be considered: Scenario 1: The cell can be standalone, by transmitting always-on SSB and long-periodicity SIB1 / WUS configuration and monitoring the configured WUS transmission opportunities. WUS transmission is based on this cell’s SSB. This cell transmits on-demand SIBt if it detects WUS. Scenario 2: The cell transmits always-on SSB and transmits on-demand SIBt if it detects WUS. WUS transmission is based on this cell’s SSB. WUS configuration is transmitted by an assisting cell in the assisting cell’s SIBs. Scenario 3: The cell transmits on-demand SSB / S1B1 if a UE transmits WUS for this cell. WUS configuration is transmitted by an assisting cell in the assisting cell’s SIBs, and WUS transmission is based on the assisting cell’s SSB. WUS is monitored by the assisting cell only or by both cells if both cells are synchronized.WUS design

[0397] Regarding UL WUS design, since the UE may be in idle and / or inactive mode, it is reasonable to use PRACH preamble as the starting point, and WUS should be allowed only onspecific time and / or frequency-domain resources and with specific sequences, since the network has to monitor all possible WUS transmission occasions, e.g., all possible WUS time and / or frequency-domain resources and sequences. A subsequent question is whether and / or how the WUS resources are multiplexed with other resources, especially regular PRACH resources used for initial access and other activities. That is, the question remains as to should a WUS transmission be distinguished from a non-WUS, regular PRACH transmission? There are different options for embodiments:

[0398] In a first option, a WUS is indistinguishable from non-WUS PRACH transmissions. In this case, generally the network will reply with RAR (e.g., Message 2) to allocate UL assignments for follow -up transmissions by the UE. However, this seems unnecessary for WUS to trigger SIBt transmission, and the UE may not be able to receive RAR since it has not received all necessary' system information.

[0399] In a second option, a WUS is distinguishable from non-WUS PRACH transmissions. In this case, rather than the network replying with RAR, the network responds with either on- demand SIBt or a confirmation plus on-demand SIBt. The UE does not have to monitor RAR and does not have to send another UL, and the entire WUS-based procedure is done after the UE receives SIBt. Therefore, this is the preferred option.

[0400] To separate WUS from non-WUS PRACH transmissions, WUS can be assigned with dedicated time-domain resources, frequency-domain resources, and / or with specific sequences (such as based on a partition of PRACH preambles).

[0401] In some contexts, a WUS design may be based on PRACH preamble with dedicated time, frequency, and / or sequence resources.WUS triggering conditions

[0402] Many of idle and / or inactive UE behaviors are generally specified by higher layers, such as cell reselection, camping, establishing RRC connections, and the like. For this reason, RAN1 may not have to specify the details of WUS triggering conditions other than setting a criterion to prevent a UE sending WUS too often to keep waking up NES Cell. Thus, the WUS in some embodiments is triggered only once during the process to camp under NES Cell, or to establish RRC connection to NES Cell, or to monitor NES Cell as a neighbor cell and / or candidate cell, or to complete the cell selection, and / or re-selection, involving NES Cell. A timer may also be introduced so that no more than N WUS can be sent during a time period of M seconds.

[0403] In some contexts, WUS transmission should be triggered only once during each of the following: To camp under NES Cell, to establish RRC connection to NES Cell, to monitor NES Cell as a neighbor cell and / or candidate cell, to complete the cell selection, and / or re-selection, involving NES Cell, or a certain time duration.WUS response

[0404] After gNB receives a WUS transmission from a UE, there are a couple of alternativesthat it may respond to the WUS transmission. For one, the gNB may send a feedback message to confirm that SIB1 will be transmitted, and some information about the SIB1 resources can be provided, such as information about PDCCH and PDSCH carrying the SIB1, based on which the UE can find the SIB1. Alternatively, the gNB may not send a feedback message for confirmation, but just starts to transmit SIB1 according to predetermined schedule, such as sending the PDCCH for SIB1 within a certain time window starting from the WUS transmission, or turning on the SIB1 transmission based on existing legacy SIB1 transmission schedule based on the NES Cell’s SSB. It seems that the WUS response is not strictly necessary or useful. If the WUS transmission does not get through and the UE does not receive either the WUS response or the SIB1, the UE will perform a retransmission of WUS anyway. Thus, it is preferable not to send any WUS response other than the requested SIB1 transmission.

[0405] In some contexts, NES Cell responds to a WUS transmission with one of the following: SIB1 transmission according to legacy SIBt transmission schedule based on NES Cell SSB, or SIBt transmission within a time window of the WUS transmission.WUS configuration validity area

[0406] Several options have been considered for WUS configuration validity area, with different pros and cons. In a first option, pre-defined UL WUS configuration. This option would reduce the signaling overhead and latency, but it significantly lacks flexibility and is not preferred.

[0407] In a second option, UL WUS configuration that applies to multiple NES cells. This option can provide a good tradeoff between signaling overhead, latency, complexity, and flexibility. Cell A can cariy one WUS configuration applicable to multiple NES Cells in a WUS configuration validity area, and different areas can have different WUS configurations.

[0408] In a third option, UL WUS configuration that applies to a single NES cell. This option may result in higher complexity than other options. For example, if in an area there are several NES Cells, then each Cell A in this area may have to provide several different WUS configurations associated with the several NES Cells. UE will need to receive several WUS configurations and then select one, or will need to send more specific request for a particular NES Cell’s WUS configuration.

[0409] In some embodiments, a UL WUS configuration is utilized that applies to multiple NES Cells.PBCH / MIB / Idle / Inactive designs in the specifications

[0410] To meet certain specifications, for example that no modification of SSB occurs, as may be desired, the existing M1B cannot be modified and hence it is useful to understand the restrictions imposed on existing MIB contents and related behaviors, mostly idle and inactive mode UE behaviors. For example, TS 38.331 specifies:

[0411] TS 38.331:

[0412] 5.2.2.4.1 Actions upon reception of the MIB

[0413] Upon receiving the MIB the UE shall:

[0414] 1> store the acquired MIB;

[0415] 1> if the UE is in RRC_IDLE or in RRC_INACTIVE, or if the UE is inRRC_CONNECTED while T311 is running:

[0416] 2 > if the access is not for NTN or the UE is not capable of NTN or the UE is not capable of NES cell DTX / DRX; and

[0417] 2> if the access is not for ATG or the UE is not capable of ATG; and

[0418] 2> if the cellBarred in the acquired MIB is set to barred:

[0419] 3> if the UE is an (e)RedCap UE and ssb-SubcarrierOffset indicates SIBi is transmitted in the cell (see TS 38.213):

[0420] 4> acquire the SIBi, which is scheduled as specified in TS 38.213;

[0421] 3> consider the cell as barred in accordance w ith TS 38.304;

[0422] 3> perform cell re-selection to other cells on the same frequency as the barred cell as specified in TS 38.304;

[0423] 2> else:

[0424] 3> apply the received systeniFranieNumber, pdcch-ConfigSIBi, subCarrierSpacingCommon, ssb-SubcarrierOffset and dmrs-TypeA-Position.

[0425] N GTE 1 : A UE capable of NTN access should acquire S I B 1 to determine whether the cell is an NTN cell.

[0426] NOTE 2: A UE capable of ATG access should acquire SIBi to determine whether the cell is an ATG cell.

[0427] NOTE 3: A UE capable of NES cell DTX / DRX should acquire SIBi to determine the cell barring status when the cellBarred in MIB is set to barred.MIB

[0428] The MIB includes the system information transmitted on BCH.

[0429] Signaling radio bearer: N / A

[0430] RLC-SAP: TM

[0431] Logical channel: BCCH

[0432] Direction: Network to UE

[0433] Example MIB:ASN1STARTTAG-MIB-STARTMIB ::= SEQUENCE { systemFrameNumber BIT STRING (SIZE (6)), subCarrierSpacingCommon ENUMERATED {scsisor6o, scs3oori2o}, ssb-SubcarrierOffset INTEGER (O..15),dmrs-TypcA-Position ENUMERATED {pos2, pos3}, pdcch-ConfigSI B 1 PDCCH-ConfigSIBi, cellBarred ENUMERATED {barred, notBarred}, intraF reqReselection ENUMERATED {allowed, notAllowed}, spare BIT STRING (SIZE (1))}TAG-MIB-STOP— ASN1STOP

[0434] A table of the MIB field descriptions is as follows in Table 3:Table 3: Example MIB Field Descriptions

[0435] SIB1 contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information. It also contains radio resource configuration information that is common for all UEs and barring information applied to the unified access control. Such information includes: Signaling radio bearer: N / A, RLC-SAP: TM, Logical channels: BCCH, and / or Direction: Network to UE.

[0436] An example SIB1 message includes:SIBi-vi8oo-IEs SEQUENCE { ncr-Support-ri8 ENUMERATED {true} OPTIONAL, - Need S mt-SDT-ConfigCommonSIB-ri8 MT-SDT-ConfigCommonSIB-ri8 OPTIONAL, - Need R musim-CapRestrictionAllowed-ri8 ENUMERATED {true} OPTIONAL, — Need R feature Priorities-vi8oo SEQUENCE { msgi-Repetitions-Priority-ri8 FeaturePriority-ri7 OPTIONAL, - Need R eRedCapPriority-ri8 FeaturePriority-ri7 OPTIONAL - Need ROPTIONAL, - Need R si-SchedulingInfo-vi8oo SI-SchedulingInfo-vi8oo OPTIONAL, - Need R cellBarredATG-ri8 ENUMERATED {barred, notBarred} OPTIONAL, - Need S cellBarredNES-n8 ENUMERATED {notBarred} OPTIONAL, - Need R mobilel AB-Cell -ri 8 ENUMERATED {true} OPTIONAL, - Need R eDRX-AllowedInactive-ri8 ENUMERATED {true} OPTIONAL, - Cond EDRX-RC intraFreqReselection-eRedCap-ri8 ENUMERATED {allowed, notAllowed} OPTIONAL, —Need s nonServingCellMII-ri8 ENUMERATED {true} OPTIONAL, - Need R nonCriticalExtension SEQUENCE {} OPTIONAL}

[0437] Example SIB1 field descriptions include:

[0438] Additional objectives satisfied by at least some embodiments of the present disclosure are discussed below7. Specifically, the following objectives are analyzed herein:

[0439] Objective 1: Procedures and Signaling method(s) to support on-demand SSB SCell operation for UEs in connected mode configured with CA, for both intra-band and / or inter-band CA. Specify triggering method(s) (select from UE uplink wake-up-signal using an existing signaland / or channel, cell on and / or off indication via backhaul, SCell activation and / or deactivation signaling). On-demand SSB transmission can be used by UE for at least SCell time and / or frequency synchronization, L1 / L3 measurements and SCell activation, and is supported for FRt and FR2 in non-shared spectrum.

[0440] Objective 2: Procedures and Signaling method(s) to support on-demand SIB1 for UEs in idle and / or inactive mode, including: Triggering method by uplink wake-up-signal using an existing signal and / or channel. Wake-up-signal configuration provisioning to UE. Note: No modification of SSB will be discussed under this objective. Information exchange between gNBs at least for the configuration of wake-up signal, if necessary. Checkpoint for normative work in RAN#1O5

[0441] Objective 3: Specify adaptation of common signal and / or channel transmissions. Adaptation of SSB in time domain, e.g. adapting periodicity. Adaptation of PRACH in time domain. Study adaptation of PRACH in spatial domain, e.g. non-uniform PRACH resources per SSB, and specify if found beneficial. Adaptation of paging occasions including confining the paging occasions in the time domain, where there shall be no paging latency increase. Note: there shall be no negative impact to legacy UEs, unless significant benefits are shown

[0442] This disclosure, including the analysis below, reviews the third objective and several enhancements.On the time adaptation and signaling

[0443] The third objective addresses procedures and solutions for the adaptation of common signal and / or channel transmissions (e.g., SSB, PRACH, paging channel) for the purpose of network energy savings. Specifically, this refers to the time domain adaptation.

[0444] The technique A-l adapts the transmission pattern (when applicable) of downlink common and broadcast signals, such as SSB / SIB / RACH / paging / cell common PDCCH. Technique A-1-3, e.g., configuration and / or adaptation of longer periodicity of common signals and / or uplink random access opportunities, is a match for the third objective.

[0445] Simulations results showed that that together with longer SIB / RACH / RO monitoring periodicities, depending on the traffic load, the BS energy saving gain can be 53.6%~7.1% and 83.6%~3-4%, respectively, compared to a baseline with 20ms SSB periodicity. In the same simulations, the latency and / or access delay and / or UE power consumption increases proportionally as the periodicity of SSB / SIB increases compared to a corresponding baseline.

[0446] Time Adaptation and Signaling Observation 1: Energy saving gain generally increases as the SSB / SIB periodicity becomes larger and decreases as the traffic load increases or the number of SSBs increases. The results imply that one independent factor that impacts energy savings is the traffic load in a cell. To minimize the impact on the latency and / or access delay and UE power consumption is preferable that SSB periodicity is shorter for medium and high traffic, and longer for zero or light traffic when cells can benefit for longer sleep periods.

[0447] Time Adaptation and Signaling Observation 2: Traffic load seems to be an independent variable that could trigger time adaptation of common signal periodicity to achieve energy gains at gNB. Therefore, the traffic change may influence how fast in time the time adaptation is necessary.

[0448] Another observation concerns the potential impact on the legacy UEs, which is one of a restriction from objective 3. For example, this includes that the scheme does not affect the UPT for empty load case. When traffic occurs and load increases, the UPT also significantly decreases. The latency, access delay, and / or UE power consumption increases proportionally as the periodicity of SSB / SIB increases compared to a corresponding baseline.

[0449] Time Adaptation and Signaling Observ ation 3: Only for the empty load case the configuration and / or adaptation of longer periodicity of common signals and / or uplink random access opportunities does not affect the UPT, the latency or the UE power consumption. In Rel-8 NES one solution to minimize the impact on the legacy device is to allow Rel-18 UE capable of NES cell DTX / DRX to select a cell, which is barred for legacy UEs non NES cell DTX / DRX capable. The procedure is defined in TS 38.331, Clause 5.2.2.4. More precisely, if cellBarred in MIB is set to barred, the legacy UEs (<R18) in some circumstances consider cell barred and reselect a different cell. UE capable of NES cell DTX / DRX in some circumstances acquires SIB1 to determine the cell barring status when the cellBarred in MIB is set to barred and only if cellBarredNES is absent in the acquired SIBt considers the cell barred in accordance with TS 38.304.

[0450] Time Adaptation and Signaling Observation 4: Rel-18 UEs capable of NES cell DTX / DRX may select a cell which is barred for legacy UEs. Such operation may allow a cell to enter deep sleep or implement NES methods without affecting legacy UEs, when legacy UEs have the possibility to reselect a neighbor cell. From this aspect it is expected that Rel-19 UEs capable of NES cell DTX / DRX to be backward compatible with Rel-18 UEs capable of NES cell DTX / DRX

[0451] Some contexts support or extend Rel-18 cell barring initial access approach for Rel-19 UEs capable of NES cell DTX / DRX. For the third objective of the WID, it is important to understand whether the existing configurations of common signal transmissions would require static, semi-static or dynamic time adaptation. In the study phase of TR 38.864, the companies reported results based on statically adapting SSB periodicity, Paging periodicity, RACH occasion periodicity and static skipping one or more SSB / SIB1 transmissions.

[0452] Time Adaptation and Signaling Observation 5: During the study phase, the simulations and results were provided only for the static adaptation of time periodicity of SSB, RACH occasions and Paging periodicity. Therefore, priority in some circumstances should be given to static and semi-static time adaptation solutions until new evidence is provided on the NES gain and feasibility of the dynamic time adaptation solutions.

[0453] Some implementations, in accordance with a second proposal, prioritize the static andthe semi-static solutions for the time adaptation of signals and channels. As specified in TS 38.331, the UE in RRC_IDLE and RRC_INACTIVE shall ensure having a valid version of (at least) the MIB, SIB1 and other SIBs depending on the configuration and capability. When system information changes occur, gNB informs the UEs about the SI modification.

[0454] The UE receives indications about SI modifications and / or PWS notifications using Short Message transmitted w ith P-RNTI over DCI. Repetitions of SI change indication may occur within preceding modification period or within preceding eDRX acquisition period. UEs in RRC_IDLE or in RRC_INACTIVE while SDT procedure is not ongoing shall monitor for SI change in its own paging occasion(s) that the UE monitors.

[0455] Once a UE is aware of the SI change, in some embodiments it reacquires SIBi and apply the SI acquisition procedure by sending a SI request (e.g., a MSGi repetition) on dedicated PRACH resources signaled in SIBi. If in RRC_IDLE or in RRC_INACTIVE or in RRC_CONNECTED while T311 is running if the UE is unable to acquire MIB or SIBi the UE shall perform cell reselection.

[0456] For SI message acquisition PDCCH monitoring occasion(s) are determined according to searchSpaceOtherSystemlnforniation. The UE assumes that, in the SI window, PDCCH for an SI message is transmitted in at least one PDCCH monitoring occasion corresponding to each transmitted SSB and thus the selection of SSB for the reception SI messages is up to UE implementation.

[0457] A UE monitors PDCCH with CRC scrambled by SI-RNTI. The System information indicator field (e.g., 1 bit) of the PDCCH signals whether the message concerns SIBi or SI message (e.g., carrying other SIB information including posSIB). The SIBi information may be provided to UE via DedicatedSIBi during the reconfiguration process.

[0458] Time Adaptation and Signaling Observation 6: SIB other than SIBi may be provided to UEs via SI request procedure. SIBi information may be provided only during the reconfiguration process. From the scope of objective 3 of the WID, gNB should be able to implement an adaptive transmission of the SSB, PRACH occasions and Paging occasions. Such an adaptation may provide energy savings.

[0459] If gNB is adapting its transmission periods of system signals and / or channels in some contexts it is able to inform UEs about the modifications. Such changes may impact SIBi for instance Schedulinginfo related fields. It also may require the adaptation of SIBi transmissions as well. If the existing solutions are reused, gNB using paging informs UEs in RRC IDLE or RRC INACTIVE states of the changes. The changes in the system information may be notified by the network using a Short Message. When such message about the system information changes is received, the UE in some embodiments should be able to acquire or re-acquire the concerned system information like the existing procedures.

[0460] Implementations in some contexts reuse or extend the existing signaling to informUEs about the time adaptation of SSB, SIB1, PRACH and Paging transmissions.SSB

[0461] Cell Defining SSB (e.g., an SSB with an RMSI associated information) provides or is used for cell selection, and / or re-selection, and initial access with synchronization in time and frequency, frame timing, PCI, SFN, SCS, initial BWP, CORESET# 0 information, SIB1 related information, cell baring status, PRACH occasions, downlink CSI EPRE and RRM measurements (e.g., including signal strength, and / or QCL related information). PSS together with SSS provides cell ID, and symbol synchronization. PBCH via MIB’s associated DMRS provides the LSB of the SSB index (e.g., via DMRS sequence and respectively PBCH payload). The SSB index is used for RRM, CSI-RS measurements to assess link quality, and for the link recovery procedures.

[0462] In the case when SSB is not associated with an RMSI, PBCH indicates that there is no associated SIBi, in which case the UE may be pointed to another frequency from where to search for an SSB that is associated with a SIBi as well as a frequency range where the UE may assume no SSB associated with SIBi is present. As specified, for a half frame with SS / PBCH blocks, the first symbol indexes for candidate SS / PBCH blocks are determined according to the SCS of SS / PBCH blocks, where index o corresponds to the first symbol of the first slot in a half-frame. For instance, for 15kHz SCS there are 4 SSB transmissions in a half-frame for carrier frequencies smaller than or equal to 3 GHz (e.g., symbol indexes of {2,8} + 14 • n, n = 0,1) , and 8 SSB transmissions (n = 0,1, 2, 3) for carrier frequencies larger than 3GHz. For example, see FIG. 16 depicting an example SCS of 15kHz, a SSB Case A for carrier frequencies less than or equal to 3GHz.

[0463] For the initial cell selection, a UE may assume that half frames with SS / PBCH blocks occur with a periodicity of 2 frames. Thus, the SSB burst is confined in a 5ms window with a typical periodicity of 20ms, which can be increased up to 160ms. For example, see FIG. 17 depicting an example SSB time distribution, specifically having a 20 ms periodicity and a SSB burst within 5 ms.

[0464] A UE can be provided a periodicity of the half frames for reception of the SS / PBCH blocks for the serving cell per serving cell by ssb-periodicityServingCell as a part of the IE servingCellConfigCommon. The IE contains parameters which a UE would typically acquire from SSB, MIB or SIBs when accessing the cell from RRC IDLE state.

[0465] Certain gains in energy savings may be realized with respect to the reference of 20ms SSB period for transmissions of SSB with increased periodicity values in the set of {40ms, 80ms, 160ms}. Small saving gain (e.g., around 5% or less) for medium traffic load with the most gain for zero traffic or low traffic load. These results indicate that one way to increase the energy saving for a cell is to increase SSB periodicity.

[0466] Thus, for the very low' traffic scenarios or during the sleep periods the SSB transmissions can be less frequent at the price of increased latency.

[0467] An R19 cell may have the option to change SSB periodicity when the legacy devices are little or no impacted, for instance, in the cell overlapping scenarios or the CA when a SCell could provide services for UE capable of cell NES DTX / DRX.

[0468] Implementations in some contexts support the static or semi-static change of SSB’s transmission periodicity and the corresponding signaling of the change to UEs.

[0469] The indication of the new SSB transmission occasions may be achieved via RRC signaling in SIB1 for instance or via a modified DCI Format 2-9, which now is used for activating or de-activating the cell DTX and / or DRX configuration of one or multiple serving cells for one or more UEs, and / or for providing NES-mode indication of the primaiy cell for one or more UEs. Another embodiment may use a modified DCI Format i_o with CRC scrambled by SI-RNTI.PRACH

[0470] By cutting down the receiving occasions at gNB additional energy saving can be achieved at the expense of increased latency. The simulations provided the gain for empty load scenarios with respect to 10 ms RACH periodicity. The gain generally increases as PRACH periodicity increases for the same number of SSBs.

[0471] Random access preambles can only be transmitted in the time resources obtained from Tables 6.3-3.2-2 to 6.3-3.2-4 of TS 38.211 and depends on FR1 or FR2 and the spectrum type. The configuration index in these tables is given by the higher layer parameter prach- Configurationlndex, or by msgA-PRACH-Configurationlndex if configured.

[0472] PRACH slots have periodicities from 10ms up to 160 ms, Table 6.3-3.2-3 (FRi) and Table 6.3-3.2-4 (FR2).

[0473] The PRACH slots are in the index frame given by the formula nfmod x = y, where x is the configuration period {1,2,4,8,16}. The PRACH slots are in a subframe (e.g., indicated by the Subframe number) while the number of slots is indicated by the Number of PRACH slots within a subframe (e.g., none, one, or two). For instance, in Table 6.3-3.2-3, if PRACH configuration 76 is selected, the period x=2, e.g., 20ms, thus in the odd frames, one PRACH slot will be in each of the subframes 2, 3, 4, 7, 8, 9. In the above tables for FR2 the column of the subframe number is replaced with the column of slot number, where a slot duration corresponds to 60 kHz SCS.

[0474] To reduce receiving time (or occasions) at gNB, a simple approach can be adding to the PRACH table new PRACH occasions, where a new single PRACH occasion would correspond to a larger number of consecutive subframes (increased period x) for instance {2,34,5,6} subframes, where all the PRACH occasions are in the first subframe of this sequence of subframes. Grouping the PRACH occasions closer in time would allow gNB longer sleep periods.

[0475] Implementations in some contexts, in accordance with some proposals, if SS / PBCH blocks periodicities are increased beyond the Rel-18 specs consider PRACH configurations with larger periods.

[0476] As specified in TS 38.213, for Type-1 random access procedure and Type-2 randomaccess procedure, a UE is provided a number N of SS / PBCH block indexes associated with one PRACH occasion. If N<1, one SS / PBCH block index is mapped to i / N consecutive valid PRACH occasions. For example, ssb-perRACH -Occasion ENUMERATED {oneEighth, oneFourth, oneHalf, one, two, four, eight, sixteen}

[0477] This implied association is such that the index of SS / PBCH blocks are mapped at least once to the PRACH occasions within the association period, where a UE obtains the index of SS / PBCH blocks from the value of higher layer parameter ssb-PositionsInBurst in SystemlnformationBlockTypet and / or in ServingCell ConfigCommon. Further, an association pattern period includes one or more association periods and is determined so that a pattern between PRACH occasions and SS / PBCH blocks repeats at most eveiy 160 msec. PRACH occasions not associated with SS / PBCH blocks after an integer number of association periods, if any, are not used for PRACH transmissions.

[0478] A pattern between PRACH occasions and SS / PBCH blocks repeats at most every 160 millisecond, which corresponds to the present largest SSB period and PRACH slots periodicity. As observed, increasing SSB periodicity may be beneficial for the gNB energy sensing. Therefore, for larger SSB periodicity and PRACH slot periodicity the pattern of the association between SS / PBCH and PRACH occasions may also be increased.

[0479] Implementations in some contexts in accordance with a second proposal consider larger periods of association pattern between PRACH occasions and SS / PBCH blocks if their periodicities are increased beyond the Rel-18 specs.SSB Adaptation Discussion

[0480] A first issue is to clarify the meaning of time adaptation for a specific signal.

[0481] When considering solutions for time adaptation, it may be desired that there shall be no negative impact to legacy UEs, unless significant benefits are shown. Thus, this “do no harm” condition may be considered behind any choice of time adaptation solution.

[0482] A straightforward way to avoid and / or minimize the impact on the legacy UEs is to preserve the legacy configurations of the SSB transmissions defined in TS 38.213, Clause 4.1 as much as possible. Legacy configurations are recognized and used by the legacy devices to perform synchronization and acquire SI of MIB or for RRM, RLM purposes.

[0483] During the study phase, SSB periodicities up to 160ms were used to show energy saving for zero or low cell load scenarios when SSB periodicity were investigated. The SSB transmission formats defined in TS 38.213 allow a period of the SSB transmission burst up to 160ms. Thus, the study phase did not offer strong evidence that larger periodicity values than those already supported are necessary.

[0484] Given the reported results and the goal of no impact on the existing UEs, the existing SSB time formats may be used for some implementations.

[0485] Some implementations in accordance with a first proposal support the SSB timeadaptation based on the existing SSB transmission formats as defined in TS 38.213, Clause 4.1.

[0486] One approach to the SSB time adaptation is to reduce the number of transmissions of SSBs (e.g., legacy SSBs) to a minimum when the cell load conditions allow it, and to increase the number of SSB (e.g., legacy SSBs) transmissions when the cell load increases.

[0487] This approach would not introduce new SSB transmission configurations, and may be obtained by switching between two or more legacy SSB transmission configurations based on the cell load.

[0488] Below, this disclosure analyses details for embodiments within existing specifications.

[0489] A piece of information provided in the IE servingCellConfigCommon is ssb- PositionsInBurst. For operation in licensed spectrum, ssb-PositionsInBurst indicates the time domain positions of the transmitted SS-blocks in a half frame. The first / leftmost bit corresponds to SS / PBCH block index 0, the second bit corresponds to SS / PBCH block index 1, and so on. Value 0 in the bitmap indicates that the corresponding SS / PBCH block is not transmitted while value 1 indicates that the corresponding SS / PBCH block is transmitted. The network configures the same pattern in this field as in the corresponding field in ServingCellConfigConunoiiSIB.

[0490] Thus, different numbers of SSB transmissions in a half frame may be indicated by changing the ssb-PositionsInBurst. This solution requires no change to the time distribution of SSB transmission formats defined in TS 38.213.

[0491] For instance, for 30kHz SCS, Case B (for example, TS 38.213, Clause 4.1), out of 8 maximum SSB transmissions in half frame only 1 may be indicated via the ssb-PositionsInBurst and transmitted.

[0492] In accordance with an observation, a simple solution to reduce the period of SSB transmissions to achieve NES is to reduce the number of transmissions in half frame period using ssb-PositionsInBurst mask.

[0493] Low cell load may also offer conditions for initiating cell DTX / DRX configurations for energy saving. To facilitate cell energy saving the specs support cell Discontinuous Transmission (DTX) (for example, in TS 38.300, Clause 15.4.2.3). To reduce gNB downlink transmission and / or uplink reception active time, UE can be configured with a periodic cell DTX / DRX pattern (e.g., active and non-active periods). The pattern configuration for cell DTX / DRX is common for the UEs configured with this feature in the cell. The cell DTX and cell DRX patterns can be configured and activated separately. When cell DTX is configured and activated for the concerned cell, the UE may not monitor PDCCH in selected cases or does not monitor SPS occasions during cell DTX non-active duration. When cell DRX is configured and activated for the concerned cell, the UE does not transmit on CG resources or does not transmit a SR during cell DRX non-active duration. This feature is only applicable to UEs in RRC_ CONNECTED state and it does not impact Random Access procedure, SSB transmission, paging, and system information broadcasting.

[0494] When configured DTX / DRX non-active durations overlap, the cell load is presumablylower as the DL and UL activity is reduced. Such scenario may justify further energy saving through a reduction in other signals transmissions such as SSB, SI broadcasting, or paging.

[0495] Thus, at least two configurations for SSB periodicity can be considered to achieve further energy savings when configured with DTX / DRX while limiting the impact on the legacy UEs: one SSB transmission pattern during the DTX / DRX active period and one during DTX / DRX non-active periods.

[0496] In accordance with another proposal, some implementations support at least two distinct SSB transmission patterns for cell DTX / DRX active and non-active periods.

[0497] As mentioned above, to limit the impact on the legacy devices these distinct SSB transmission patterns may be implemented using the ssb-PositionsInBurst mask on the existing SSB transmissions format specified in TS 38.213.

[0498] Rel-19 UEs may benefit from knowing the SSB or SI broadcasting patterns in advance, thus saving additional energy on monitoring these signals.

[0499] For the case above, when DTX / DRX is configured, these patterns may be communicated at the configuration or during the activation or de-activation of the cell DTX and / or DRX cell configuration.

[0500] In accordance with another proposal, a gNB may inform Rel-19 UEs on the distinct time patterns of SSB transmission for cell DTX / DRX active and non-active periods.

[0501] For the adaptation mechanisms of SSB in time-domain, further analysis of applicable scenarios and associated legacy UE impact and / or handling (if any) based on the following is discussed: Applicability to UE in idle and / or inactive and / or connected mode, and / or Applicability to PCell and / or SCell(s).

[0502] The UE behaviour in RRC_IDLE or RRC_INACTIVE is described in TS 38.304. The UE shall monitor the Paging Occasions (POs) as described in TS 38.304, clause 7.1 to receive System Information (SI) change notifications. The changes in the system information are notified by the network using a Short Message as specified in TS 38.331. When the Short Message notifies system information changes, then the UE shall acquire or re-acquire the concerned system information as specified in TS 38.331. When the UE uses Discontinuous Reception (DRX) in RRC_IDLE and RRC_INACTIVE state to reduce power consumption, the UE monitors one paging occasion (PO) per DRX cycle.

[0503] For the legacy UEs, the system information change is indicated in PDCCH Format i_o, via 1 bit field, where the SI change indication is only for SIB related information.

[0504] There is no indication of SSB transmission occasions or SSB schedule changes. If SSB time schedule is adapted for NES such indication may be useful to UEs for UE energy savings and for keeping up with the latest SI, in some contexts.

[0505] For reduced specs impact the existing specs may be considered as the starting point when defining new SSB signaling. Thus, the indication of new SSB transmission occasions maybe achieved via RRC SIB signaling or via a modified DCI Format 2-9, which now is used for activating or de-activating the cell DTX and / or DRX configuration of one or multiple serving cells for one or more UEs, and / or for providing NES-mode indication of the primary7cell for one or more UEs. Another possibility may be to use a modified DCI Format 1_O with CRC scrambled by a new7SI-RNTI.

[0506] In accordance with one proposal, for the SSB adaptation mechanism indication consider as design starting points for signaling new7SIB, DCI Format 2-9 and respectively DCI Format i_o with CRC scrambled by a new7SI-RNTI.

[0507] SSB changes could have a deep impact on the legacy UEs as Cell Defining SSB (e.g., an SSB with an RMSI associated information) is used for cell selection, and / or re-selection, and initial access. The potential impact of changing SSB schedule cannot be assessed by any single UE; it needs to be considered at gNB level as it may impact multiple UEs. gNB may holistically consider the cell traffic load, RRC UE states and cell access rates (e.g., initial access and reselection) prior to changing SSB schedule. Therefore, a single UE trigger cannot be sufficient to moth ate an adaptation of SSB in time-domain in some contexts.

[0508] In accordance with a one proposal, Rel-19 NES consider only adaptation mechanism indicated or configured by gNB without UE trigger.PRACH Adaptation Discussion Details

[0509] Several adaptation mechanisms may be considered for adaptation of PRACH in timedomain. Several options include:

[0510] Adaptation based on configuration of additional, and / or different, PRACH resources for NES-capable UEs in addition to PRACH resources for legacy UEs (if any), maybe considered. Note: NES-capable UEs can use both additional PRACH resources and PRACH resources for legacy UEs.For the additional PRACH resources: Adaptation of PRACH resource periodicity or PRACH occasion, Adaptation at PRACH configuration, association period, or association pattern period level and SSB to RO mapping cycle, Adaptation based on extending cell DRX operation for PRACH, and / or Concentrating ROs in time domain. It will be appreciated that other options are not precluded.

[0511] For the adaptation mechanisms of PRACH in time-domain, several options may also be considered. These options may be considered to support PRACH adaptation mechanisms without a UE trigger. Options include:

[0512] Support at least PRACH adaptation provided by gNB without UE trigger. FFS: PRACH adaptation with UE trigger. UE trigger means UE requests adaptation of PRACH. Dynamic signaling and / or semi-static signaling of PRACH adaptation, adaptation of PRACH transmission according to certain condition, the applicability to idle and / or inactive, and / or connected mode UEs, and / or of which scenarios the adaptation mechanism is applicable to (e.g., cell with bothlegacy and Rel-19 UE, cell with only Rel-19 UEs).

[0513] With respect to the first set of options, an assumption is that the PRACH adaptation may be obtained by adding additional (e.g., different) PRACH resources that can be used by the NES UEs in addition to the existing legacy resources. This type of solution may be implemented, for instance, by extending cell DRX operation. This disclosure further discusses the meaning of extending cell DRX for PRACH.

[0514] When the cell DRX is configured and activated for a concerned cell, the feature does not impact the Random Access procedure.

[0515] A straightforward extension of the NES PRACH time adaptation approach can be considered for a cell DRX. In this approach, during the DRX active and non-active duration a basic legacy PRACH time distribution may be supported and available to legacy and non-legacy devices. The legacy PRACH resources would limit the impact on the legacy UEs. During the active duration, additional resources may or may not be enabled only for NES capable UEs. In addition, NES UEs may be configured to select with higher priority these additional PRACH resources to reduce potential access collisions. For example, FIG. 23 shows an example of such PRACH resource distribution, including legacy and additional NES PRACH resources.

[0516] In accordance with one proposal, for cell DRX active and non-active durations consider a legacy PRACH resource configuration accessible to all UEs, while for the active DRX duration support additional PRACH configurations that can be accessed only by the NES capable UEs.

[0517] Additional PRACH resources may be distributed at a larger periodicity. To minimize the impact on the existing specs as well as the complexity of new solutions, the existing mechanisms may be considered as the starting point of this investigation.

[0518] Random access preambles can only be transmitted in the time resources obtained from Tables 6.3.3.2-2 to 6.3-3.2-4 of TS 38.211, for example see Annex 3.1, and depends on FR1 or FR2 and the spectrum type. The configuration index in these tables is given by the higher layer parameter prach-Configurationlndex, or by msgA-PRACH-Configurationlndex if configured.

[0519] The PRACH slots are in the index frame given by the formula nfmod x = y, where x is the configuration period {1,2,4,8,16}. The PRACH slots are in a subframe (e.g., indicated by the Subframe number) while the number of slots is indicated by the Number of PRACH slots within a subframe (e.g., none, one, or two). For instance, in Table 6.3-3.2-3, if PRACH configuration 76 is selected, the period x=2, e.g., 20ms, thus in the odd frames, one PRACH slot will be in each of the subframes 2, 3, 4, 7, 8, 9. An increased PRACH period corresponds to an increased corresponding “x” value in the configuration table.

[0520] In accordance with at least some implementations, additional PRACH resources for the NES capable UEs, where this resource can be enabled or disabled based on the necessity and energy saving goals. In such implementations, the legacy PRACH resources can be accessed bythe legacy UEs and by the NES capable UEs, while the additional resources are dedicated only for NES capable UEs.

[0521] In addition to an increased period, grouping the PRACH occasions closer in time would allow gNB longer sleep periods while maintaining the same PRACH occasions in the long run. One way to group PRACH occasions together is to allow more than 2 consecutive PRACH slots in a PRACH subframe or in several consecutive PRACH subframes.

[0522] In accordance w ith another proposal, if new PRACH occasions for NES UEs are added, support increased periodicities and more than 2 consecutive slots in a PRACH subframe.

[0523] A mapping pattern between PRACH occasions and SS / PBCH blocks repeats at most every 160 milliseconds, as specified in TS 38.213, which corresponds to the present largest SSB period and PRACH slots periodicity. As discussed above, increasing SSB periodicity may be beneficial for gNB energy savings. Therefore, for larger SSB periodicity and PRACH slot periodicity, the pattern of the association between SS / PBCH and PRACH occasions may also be changed.

[0524] In accordance with another proposal, some implementations support larger periods of association pattern between PRACH occasions and SS / PBCH blocks if their periodicities are increased beyond the Rel-18 specs.PRACH Spatial adaptation

[0525] Several pros and cons are considered when adopting non-uniform SSB to PRACH occasions mappings. A benefit of havi ng different PARCH occasions associated with different SSB directions may be achieved only if gNB has information on the spatial distribution of UEs. UEs spatial distribution estimation may be used for RRC_CONNECTED UEs (for instance from measuring reports or from received SRS transmissions). In this case, a gNB, in principle, may configure more occasions for those SSB directions associated with higher UEs density.

[0526] However, gNB may not know the spatial distribution of devices in RRC_IDLE or RRC_INACTIVE states, therefore, a minimum number of PRACH occasions must be configured for each SSB transmission to minimize the impact on the legacy devices.

[0527] The energy spent to monitor a PRACH occasion is much lower than a transmission. Therefore, reducing the number of receive occasions will lead to lower energy saving than reducing the same number the SSB transmissions.

[0528] In addition, for a uniform, or almost uniform), spatial distribution of UEs, there may be little or no gain in having different numbers of PRACH occasions for different directions. Only a substantial difference in the spatial distribution of UEs could justify non-uniform PRACH occasions distribution.

[0529] Following PRACH time adaptation NES solution, a minimum number of PRACH occasions in some embodiments is configured, therefore, having further reduction with non- uniform PRACH occasions mapping to each SSB transmission may bring little or no benefits.Table 4: Random access configurations for FR1 and unpaired spectrum.Table 4 (continued):SSB to PRACH Mapping

[0530] As specified in TS 38.213, for Type-1 random access procedure and Type-2 random access procedure, a UE is provided a number N of SS / PBCH block indexes associated with one PRACH occasion. If N<1, one SS / PBCH block index is mapped to i / N consecutive valid PRACH occasions.

[0531] This implied association is discussed in TS 38.213 “such that the index of SS / PBCH blocks are mapped at least once to the PRACH occasions within the association period, where aUE obtains the index of SS / PBCH blocks from the value of higher layer parameter ssb- PositionsInBurst in SystemlnformationBlockTypei and / or in ServingCellConfigCommon.”

[0532] The PRACH time resources are specified in Table 6.3-3.2-3 (FR1) and Table 6.3-3.2-4 (FR2) in TS 38.213. The resources are the same for each SSB index and they may be used for initial cell access.

[0533] There is a uniform mapping between SSB indices and their associated PRACH timeresources, used for contention based random access.

[0534] Not all SSB indices are necessarily transmitted. For operation in licensed spectrum, ssb-PositionsInBurst indicates the time domain positions of the transmitted SS-blocks in a half frame with SS / PBCH blocks as defined in TS 38.213, clause 4.1. The field ssb-PositionsInBurst is part of the ServingCellConfigCommon. The network configures the same pattern in this field as in the corresponding field in the IE ServingCellConfigCommonSIB The IE ServingCellConfigCommonSIB is used to configure cell specific parameters of a UE's serving cell in SIB1.[05.35] For UE in RRC_CONNECTED state, an explicit association between a SSB index and a subset of RACH occasions may be provided via PRACH Mask index field of the DCI format i_o, which used for scheduling PDSCH in one DL cell when the random access procedure is initiated by a PDCCH order.

[0536] The initial spatial filter to be used by UE to transmit its RACH preamble is left for the implementation. However, the specs require that for a retransmit the same spatial filter is reused, for example as discussed in TS 38.213, Clause 8.1.

[0537] “A UE transmits a PRACH on a cell using the selected PRACH format with transmission power PpRACH.b.f.c (0,asdescribed in clause 7.4, on the indicated PRACH resource or on a determined set of Np^ambleresources using a same spatial filter in case of Np^amblepreamble repetitions.”Relative Power Values

[0538] The relative power used by the gNB during DL and UL activity from the study phase is presented below.Table 5: Relative power values P for reference configuration Set 1, Set 2 and Set 3.EXAMPLE PROCESS FLOWCHARTS

[0539] FIG. 25 illustrates a flowchart depicting example operations of a method in accordance with some embodiments of the present disclosure. Specifically, FIG. 25 depicts a process 2500 including operations for efficient receiving of an SSB in accordance with some embodiments of the present disclosure. The example process may be performed by one or more device(s) in accordance with embodiments of the present disclosure, for example a wirelessdevice, terminal, UE, or the like, as depicted and described herein. Optional steps may be depicted in broken (e.g., dashed) lines. The dcvice(s) may include computer-readable code or instructions executing on one or more processors of the device(s). Coding of the software for carrying out or performing the process 2500 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The process 2500 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on a non-transitory computer-readable medium, such as for example, the memory of the device(s). In some embodiments, the process 2500 may be performed by one or more of units or modules (e.g., an integrated circuit) of the device(s), such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0540] The process 2500 includes a step 2502 of receiving, by a user equipment from a base station, a first signaling comprising a first configuration of a first synchronization signal and PBCH block (SSB) for a secondary cell (SCell) on a secondary component carrier. In some embodiments, the first configuration is based on a first identifier (ID). Additionally or alternatively, in some embodiments the first configuration indicates a first time offset. Additionally or alternatively still, in some embodiments, the first SSB is quasi co-located (QCLed) with a second SSB. For example, a signal or channel may be configured as being QCLed with a first SSB, and is assumed to be QCLed with the second SSB. Alternatively or additionally, in some embodiments, a signal or channel may be configured as being QCLed with a second SSB, as is assumed to be QCLed with a first SSB. No additional configuration signaling is needed to configure a signal or channel configured as being QCLed with a second SSB to be also QCLed with a first SSB (and vice versa), thus reducing signaling overhead, given that the first and second SSB play interchangeable roles in QCL relationships.

[0541] The process 2500 includes a step 2504 of receiving, by the UE from the base station, a MAC CE message. The MAC CE message indicates an activation command for the SCell and the MAC CE message further indicating the first ID.

[0542] The process 2500 includes a step 2506 of receiving, by the UE from the base station, the first SSB for the SCell in accordance with the first time offset.

[0543] The process 2500 includes an optional step 2508 of performing, by the UE, an active period procedure on the SCell upon receiving of the first SSB. The active period procedure on the SCell is performed while the SCell for the UE is activated. Additionally the active period procedure on the SCell is performed while the SCell for the UE in DTX. Further, in some embodiments, the active period procedure is performed before the receiving of the MAC CE message. Additionally the active command initiates an active period.

[0544] The process 2500 includes an optional step 2510 of, after activation of the SCell, receiving, by the UE, a periodic signal from the SCell. The periodic signal may be received in addition to the first signaling.

[0545] FIG- 26 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure. Specifically, FIG. 26 depicts a process 2600 including operations for activating a SCell in accordance with some embodiments of the present disclosure. The example process may be performed by one or more device(s) in accordance with embodiments of the present disclosure, for example a wireless device, terminal, UE, or the like, as depicted and described herein. Optional steps may be depicted in broken (e.g., dashed) lines. The device(s) may include computer-readable code or instructions executing on one or more processors of the device(s). Coding of the software for carrying out or performing the process 2600 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The process 2600 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on a non-transitoiy computer-readable medium, such as for example, the memory of the device(s). In some embodiments, the process 2600 may be performed by one or more of units or modules (e.g., an integrated circuit) of the device(s), such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0546] The process 2600 includes a step 2602 of activating, by the UE, the SCell after the UE transmits a CSI report for the SCell, while the SCell is deactivated for the UE. Additionally, in some embodiments, the SCell is activated after the UE transmits the CSI report and before the receiving the MAC CE message.

[0547] The process 2600 includes a step 2604 of transmitting, by the UE to the base station, a valid CSI report. In some embodiments, the valid CSI report indicates completion of the SCell activation procedure.

[0548] FIG. 27 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure. Specifically, FIG. 27 depicts a process 2700 including other operations for activating an SCell in accordance with some embodiments of the present disclosure. FIG. 27 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure. Specifically, FIG. 27 depicts a process 2700 including operations for activating a SCell in accordance with some embodiments of the present disclosure. The example process may be performed by one or more device(s) in accordance with embodiments of the present disclosure, for example a wireless device, terminal, UE, or the like, as depicted and described herein. Optional steps may be depicted in broken (e.g., dashed) lines. The device(s) may include computer-readable code or instructions executing on one or more processors of the device(s).Coding of the software for cariying out or performing the process 2700 is well within the scope of a person of ordinary’ skill in the art having regard to the present disclosure. The process 2700 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the softw are executable by the one or more processors may be stored on a non-t ran si ton computer-readable medium, such as for example, the memory’ of the device(s). In some embodiments, the process 2700 may be performed by one or more of units or modules (e.g., an integrated circuit) of the device(s), such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0549] The process 2700 includes a step 2702 of receiving, by the UE from the base station, a DO message. In some embodiments, the DCI message is received in place of the MAC CE message described herein, for example with respect to FIG. 25. Additionally or alternatively, in some embodiments, the DCI message is received in addition to the MAC CE message described herein, For example with respect to FIG. 25.

[0550] The process 2700 includes a step 2704 of activating, by the UE, the SCell after the UE transmits the valid CSI report for the SCell, while the SCell is deactivated for the UE. Additionally, in some embodiments, the SCell is activated after the UE transmits the valid CSI report for the SCell and before the receiving the DCI message.

[0551] FIG. 28 illustrates a flowchart depicting additional example operations of a method in accordance with some embodiments of the present disclosure. Specifically, FIG. 28 depicts a process 2800 including operations for performing an active period procedure in accordance with some embodiments of the present disclosure. The example process may be performed by one or more device(s) in accordance with embodiments of the present disclosure, for example a wireless device, terminal, UE, or the like, as depicted and described herein. Optional steps may be depicted in broken (e.g., dashed) lines. The device(s) may include computer-readable code or instructions executing on one or more processors of the device(s). Coding of the software for carrying out or performing the process 2800 is well within the scope of a person of ordinary skill in the art having regard to the present disclosure. The process 2800 may include additional or fewer operations than those shown and described and may be carried out or performed in a different order. Computer-readable code or instructions of the software executable by the one or more processors may be stored on a non-transitory computer-readable medium, such as for example, the memory of the device(s). In some embodiments, the process 2800 may be performed by one or more of units or modules (e.g., an integrated circuit) of the device(s), such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0552] The process 2800 includes a step 2802 of performing, by the UE, the active period procedure on the SCell upon the receiving of the first SSB. The active period procedure on the SCell is performed while the SCell for the UE is activated. Further, the active period procedureon the SCell is performed while the SCell for the UE is in cell DTX. Additionally, the active period procedure on the SCell is performed before the receiving of the DCI message.

[0553] One or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a first signal receiving and / or transceiving unit / module, a MAC CE signal receiving and / or transceiving unit / module, a DCI signal receiving and / or transceiving unit / module, a SSB receiving and / or transceiving unit / module, a SCell activating unit / module, a CSI reporting unit / module, an active period procedure performance unit / module, and / or a periodic signal receiving and / or transceiving unit / module, and / or the like. The respective units / modules may be hardware, software, or a combination thereof. For instance, one or more of the units / modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or applicationspecific integrated circuits (ASICs).

[0554] Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinaiy skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

CLAIMSWhat is Claimed:

1. A method performed by a user equipment (UE) or a chip system of the UE, comprising: receiving, from a base station, a first signaling comprising a first configuration of a first synchronization signal and physical broadcast channel (PBCH) block (SSB) for a secondary serving cell (SCell) on a secondary component carrier, wherein the first configuration is based on a first identifier (ID) and indicates a first time offset, and wherein the first SSB is quasi colocated (QCLed) with a second SSB; receiving, from the base station, a medium access control (MAC) control element (CE) message, the MAC CE message indicating an activation command for the SCell, and the MAC CE message further indicating the first ID; and receiving, from the base station, the first SSB for the SCell in accordance with the first time offset.

2. The method according to claim 1, further comprising: activating the SCell after the UE transmits a channel state information (CSI) report for the SCell, while the SCell is deactivated for the UE and before the receiving the MAC CE message, wherein the activation command for the SCell is in a field of the MAC CE message, and wherein the activation command initiates a SCell activation procedure; and transmitting, to the base station, a valid CSI report indicating completion of the SCell activation procedure.

3. The method according to any one of claims 1-2, wherein the first SSB corresponds to a non-cell defining SSB.

4. The method according to any one of claims 1-3, wherein the first SSB is on a nonsynchronization raster associated with the SCell.

5. The method according to any one of claims 1-4, wherein the first SSB is received before a corresponding aperiodic tracking reference signal (TRS) for the SCell.

6. The method according to any one of claims 1-4, wherein the first SSB corresponds to an on-demand SSB for the SCell.

7. The method according to any one of claims 1-6, wherein the second SSB is a celldefining SSB and is always on for the SCell, and a transmission of the second SSB is received before receiving the MAC CE message.

8. The method according to any one of claims 1-7, wherein a signal or a channel is configured as being QCLed with the second SSB, and is assumed to be QCLed with the first SSB.

9. The method according to any one of claims 1-8, wherein a signal or a channel is configured as being QCLed with the first SSB, and is assumed to be QCLed with the second SSB.

10. The method according to any one of claims 1-9, wherein the first signaling indicates to the UE that N on-demand bursts of the first SSB are transmitted via the SCell, wherein N is greater than or equal to 1.

11. The method according to any one of claims 1-10, wherein the first offset is associated with a delay between slot (n+k) and a first on-demand burst of the first SSB, wherein slot n denotes an ending slot for the MAC CE message, and wherein the slot (n+k) denotes one slot after decoding and processing of the MAC CE message.

12. The method according to any one of claims 1-11, wherein the first SSB is received between periodic transmissions of a periodic duty cycle associated with the second SSB.

13. The method according to any one of claims 1-12, further comprising: after activation of the SCell, receiving a periodic signal from the SCell.

14. The method according to any one of claims 1-13, wherein the first SSB comprises a primaiy synchronization signal (PSS) and a secondary' synchronization signal (SSS).

15. The method according to any one of claims 1-14, further comprising: performing an active period procedure on the SCell upon the receiving of the first SSB, while the SCell for the UE is activated and in cell discontinuous transmission (DTX), and before the receiving of the MAC CE message, the activation command initiating an active period, wherein the activate period procedure comprises, for the SCell: at least one radio frequency (RF) operation, an automatic gain control (AGC) procedure, a synchronization procedure or re-synchronization procedure, or a SSB-based measurement.

16. The method according to any one of claims 1-15, further comprising: receiving, from the base station, a downlink control information (DCI) message, wherein the DCI message indicates the activation command for the SCell, and the DCI message indicates the first ID.

17. The method according to claim 16, further comprising: activating the SCell after the UE transmits the valid CSI report for the SCell, while the SCell is deactivated for the UE and before the receiving the DCI message, wherein the activation command for the SCell is in a field of the DCI message.

18. The method according to any one of claims 16-17, further comprising: performing an active period procedure on the SCell upon the receiving of the firstSSB, while the SCell for the UE is activated and in cell DTX, and before the receiving of the DCI message, wherein the activation command for the SCell is in a DCI field of the DCI message.

19. An apparatus, comprising: at least one processor; and at least one non-transitoiy computer-readable storage medium havingprogramming, the programming comprising instructions that, when executed by the at least one processor, cause the apparatus to perform the method according to any one of claims 1-18.

20. A non-transitoiy computer-readable medium having instructions stored thereon that, when executed by a user equipment (UE), cause the UE to perform the method according to any one of claims 1-18.

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