CN117280835A

CN117280835A - Method and apparatus for secondary cell (SCell) activation and deactivation

Info

Publication number: CN117280835A
Application number: CN202280033133.1A
Authority: CN
Inventors: 刘嘉陵; 肖维民; 邹加林; 程谦
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-05-07
Filing date: 2022-04-28
Publication date: 2023-12-22

Abstract

According to an embodiment, the UE receives a first signaling, wherein the first signaling comprises a first configuration of a first CSI-RS for tracking the SCell. The first configuration is associated with a first ID. The UE receives a second signaling, wherein the second signaling includes a second configuration of RSs for fast SCell activation of the SCell. The second configuration is associated with a second ID. The second configuration includes the first ID. The UE receives a MAC CE message, wherein the MAC CE message includes an SCell activation command indicating activation of the SCell and the second ID. The UE receives the RS for fast SCell activation of the SCell. The RS includes a first burst of the first CSI-RS for tracking. Upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS. The UE sends a report indicating that the SCell has been activated for the UE.

Description

Method and apparatus for secondary cell (SCell) activation and deactivation

Cross Reference to Related Applications

The present patent application claims the benefit of priority of U.S. provisional application filed on day 5, 2021, application number 63/185,854, entitled "method and apparatus for secondary cell (SCell) activation and deactivation (Methods and Apparatus for Secondary Cell (SCell) Activation and Deactivation)", the benefit of priority of U.S. provisional application filed on day 8, 2021, application number 63/229,902, entitled "method and apparatus for efficient secondary cell (SCell) activation and deactivation (Methods and Apparatus for Efficient Secondary Cell (SCell) Activation and Deactivation)", and the benefit of priority of U.S. provisional application filed on day 9, 2021, application number 63/250,754, entitled "method and apparatus for efficient secondary cell (SCell) activation and reference signal (Methods and Apparatus for Efficient Secondary Cell (SCell) Activation and Reference Signals)", the entire contents of which are hereby incorporated by reference as if fully reproduced herein.

Technical Field

The present disclosure relates generally to wireless communications and, in particular embodiments, to methods and apparatus for secondary cell (SCell) enhancements in wireless communications.

Background

The wireless communication system includes long term evolution (long term evolution, LTE), LTE-a-over-a system, 5G LTE, 5G New Radio (NR), and the like. Modern wireless communication systems may include a plurality of Nodebs (NB), which may also be referred to as base stations, network nodes, communication controllers, cells or enhanced NB (eNB), etc. The NodeB may comprise one or more network points or network nodes using different radio access technologies (radio access technology, RATs), e.g. a high speed packet access (high speed packet access, HSPA) NB or Wi-Fi access point. 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, each of which may have a single antenna or multiple antennas. The network point may correspond to a plurality of cells operating in a plurality of component carriers. In general, each component carrier in carrier aggregation is a serving cell, either a primary cell (PCell) or a secondary cell (SCell).

A cell or NodeB may serve multiple users (also commonly referred to as User Equipment (UE), mobile stations, terminals, devices, etc.) over a period of time. The communication channel from NB to UE is commonly referred to as a Downlink (DL) channel, and the transmission from NB to UE is a downlink transmission. The communication channel from the UE to the NB is generally referred to as an Uplink (UL) channel, and the transmission from the UE to the NB is an uplink transmission.

It is generally found that the SCell activation speed in current New Radio (NR) systems is too slow (SCell activation delay is typically in the range of tens to hundreds of milliseconds). In many cases, the SCell activation delay of the current NR system is even longer than that of the LTE system. Therefore, it is desirable to improve SCell activation delays for NR systems and subsequent systems.

Disclosure of Invention

According to an embodiment, a UE receives first signaling from a base station, wherein the first signaling includes a first configuration of a first channel state information reference signal (channel state information reference signal, CSI-RS) for tracking a secondary cell (SCell). The first configuration is associated with a first Identifier (ID). The UE receives second signaling from the base station, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell. The second configuration is associated with a second ID, the second configuration including the first ID. The UE receives a medium control access control unit (medium control access control element, MAC CE) message from the base station. The MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID. The UE receives the RS for fast SCell activation of the SCell from the base station. The RS includes a first burst of the first CSI-RS for tracking. Upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS. The UE sends a report to the base station indicating that the SCell has been activated for the UE.

In some embodiments, the MAC CE message may further include a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to the plurality of scells. The MAC CE message may not include any ID of RS or RS configuration of each of the one or more scells to be deactivated. In some embodiments, the MAC CE message may include RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands. The bitmap in the MAC CE message may include an activate command bit corresponding to the one or more activate commands. The RS configuration ID may be arranged after a bitmap in the MAC CE message in ascending order of one or more scells to be activated in the bitmap. In some embodiments, the UE may perform SCell activation by at least one of setting automatic gain control (automatic gain control, AGC) from the first burst or performing time-frequency synchronization or tracking on the SCell from the first burst. In some embodiments, the RS may further include a second burst of the first CSI-RS for tracking, subsequent to the first burst. The duration between the first burst and the second burst may be associated with a gap value indicated by the second configuration. In some embodiments, the UE may perform SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst. In some embodiments, the RS may be aperiodic and may be transmitted to the UE in response to transmitting the SCell activation command. In some embodiments, the UE may receive the RS by receiving the RS from the base station on a first bandwidth part (BWP) of the SCell. The first BWP may be associated with a first actionlowlinkbwp-Id. The first actiondownlinkbwp-Id may be configured in an RRC message when configuring the SCell. The first BWP is activated at the same time as the SCell is activated. In some embodiments, the first CSI-RS for tracking may be configured as an aperiodic CSI-RS for tracking on the first BWP. In some embodiments, the second configuration may further indicate an offset value associated with a delay between a time slot (n+k) representing an ending time slot of the MAC CE message and the first burst, the time slot (n+k) representing one time slot after decoding and processing the MAC CE message. In some embodiments, the report may include Downlink (DL) CSI.

According to an embodiment, a base station transmits first signaling to a UE, wherein the first signaling includes a first configuration of a first channel state information reference signal (channel state information reference signal, CSI-RS) for tracking a secondary cell (SCell). The first configuration is associated with a first Identifier (ID). The base station transmits a second signaling to the UE, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell. The second configuration is associated with a second ID, the second configuration including the first ID. The base station sends a medium control access control unit (medium control access control element, MAC CE) message to the UE. The MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID. The base station transmits the RS for fast SCell activation of the SCell to the UE. The RS includes a first burst of the first CSI-RS for tracking. Upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS. The base station receives a report from the UE indicating that the SCell has been activated for the UE.

In some embodiments, the MAC CE message may further include a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to the plurality of scells. The MAC CE message may not include any ID of RS or RS configuration of each of the one or more scells to be deactivated. In some embodiments, the MAC CE message may include RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands. The bitmap in the MAC CE message may include an activate command bit corresponding to the one or more activate commands. The RS configuration ID may be arranged after a bitmap in the MAC CE message in ascending order of one or more scells to be activated in the bitmap. In some embodiments, the UE may perform SCell activation by at least one of setting automatic gain control (automatic gain control, AGC) from the first burst or performing time-frequency synchronization or tracking on the SCell from the first burst. In some embodiments, the RS may further include a second burst of the first CSI-RS for tracking, subsequent to the first burst. The duration between the first burst and the second burst may be associated with a gap value indicated by the second configuration. In some embodiments, the UE may perform SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst. In some embodiments, the RS may be aperiodic and may be transmitted to the UE in response to transmitting the SCell activation command. In some embodiments, the base station may transmit the RS by transmitting the RS to the UE on a first bandwidth part (BWP) of the SCell. The first BWP may be associated with a first actionlowlinkbwp-Id. The first actiondownlinkbwp-Id may be configured in an RRC message when configuring the SCell. The first BWP is activated at the same time as the SCell is activated. In some embodiments, the first CSI-RS for tracking may be configured as an aperiodic CSI-RS for tracking on the first BWP. In some embodiments, the second configuration may further indicate an offset value associated with a delay between a time slot (n+k) representing an ending time slot of the MAC CE message and the first burst, the time slot (n+k) representing one time slot after decoding and processing the MAC CE message. In some embodiments, the report may include Downlink (DL) CSI.

Drawings

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:

FIG. 1A illustrates an exemplary wireless communication system provided by some embodiments;

fig. 1B illustrates the use of carrier aggregation (carrier aggregation, CA) provided by some embodiments;

fig. 2A illustrates that physical layer channels and signals provided by some embodiments include PSS/SSS, PBCH (and their associated DMRS);

fig. 2B illustrates signals/channels multiplexed for use by multiple UEs provided by some embodiments;

fig. 2C illustrates an example of non-zero power (NZP) CSI-RSs provided by some embodiments for channel estimation, interference measurement, etc., wherein these NZP CSI-RSs are multiplexed with PDSCH for use by one or more UEs;

fig. 3A is a schematic diagram of QCL assumption between NR reference signals when a wide beam is used for communication provided by some embodiments;

fig. 3B is a schematic diagram of QCL assumption between NR reference signals when a narrow beam is used for communication provided by some embodiments;

FIG. 4 shows an example of an SCell activation timeline in 5G NR Rel-15/16;

fig. 5 is a schematic diagram supporting SCell activation provided by an example embodiment presented herein;

FIG. 6 is a flow chart of a configuration process provided by an exemplary embodiment presented herein;

fig. 7 is a schematic diagram of a first example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 8 is a schematic diagram of a second exemplary embodiment for SCell activation triggering and activation provided by the exemplary embodiments presented herein;

fig. 9 is a schematic diagram of a third example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 10 is a schematic diagram of a fourth example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 11 is a schematic diagram of a fifth example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 12 is a schematic diagram of a sixth example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 13 is a schematic diagram of a seventh example provided by the exemplary embodiments presented herein for SCell activation triggering and activation;

fig. 14A illustrates minimal components provided by the exemplary embodiments presented herein for L2 signaling based design;

fig. 14B illustrates minimum and optional components for L2 signaling based design provided by the exemplary embodiments presented herein;

Fig. 15 shows an exemplary triggering procedure and time axis (for FR1 known cell at 15kHz SCS) provided by the exemplary embodiments presented herein;

fig. 16 illustrates SCell activation using several L2 signaling designs provided by the exemplary embodiments presented herein;

fig. 17 illustrates SCell activation and triggering provided by the exemplary embodiments presented herein;

fig. 18 illustrates SCell activation and RS triggering provided by the exemplary embodiments presented herein;

fig. 19 illustrates SCell activation and RS triggering provided by an example embodiment presented herein;

fig. 20 illustrates SCell activation triggers and activations provided by exemplary embodiments presented herein;

fig. 21 illustrates SCell activation triggers and activations provided by exemplary embodiments presented herein;

fig. 22A illustrates SCell activation triggers and activations provided by exemplary embodiments presented herein;

fig. 22B illustrates QCL relationships for FR1 provided by the exemplary embodiments presented herein;

fig. 22C illustrates an option provided by the exemplary embodiments presented herein in which the activated QCL source RS is different from the AP TRS as the temporary RS;

fig. 23 illustrates an existing QCL configuration example and a new cross-carrier QCL relationship embodiment for carrier aggregation provided by the exemplary embodiments presented herein;

Fig. 24 illustrates SCell activation/deactivation MAC CE for TRS activation provided by an exemplary embodiment presented herein;

fig. 25 illustrates a new SCell TRS activation MAC CE including TRS selection information provided by an example embodiment presented herein;

fig. 26 illustrates that an alternative new MAC CE provided by the exemplary embodiments presented herein includes only TRS selection bits corresponding to one or more scells to be activated;

fig. 27A is a flow chart of a method for SCell activation provided by an example embodiment presented herein;

fig. 27B is a flowchart of a method for SCell activation provided by an example embodiment presented herein;

FIG. 28 illustrates an exemplary communication system provided by example embodiments presented herein;

29A and 29B illustrate exemplary devices provided by some embodiments that may implement methods and guidelines according to the present disclosure;

FIG. 30 is a block diagram of a computing system that may be used to implement the devices and methods disclosed herein provided by some embodiments.

Detailed Description

Fig. 1A illustrates an exemplary wireless communication system 100. Communication system 100 includes a base station 110 having a coverage area 101. Base station 110 serves a plurality of User Equipments (UEs), including UE 120. The transmission from the base station 110 to the UE is referred to as a Downlink (DL) transmission and is performed through a downlink channel (as indicated by the solid arrow line 135 in fig. 1A), and the transmission from the UE to the base station 110 is referred to as an Uplink (UL) transmission and is performed through an uplink channel (as indicated by the dashed arrow line 130 in fig. 1A). The data carried over the uplink/downlink connection may include data transmitted between UEs 120 and data transmitted to/from a remote terminal (not shown) over backhaul network 115. Exemplary uplink channels and signals include a physical uplink shared channel (physical uplink shared channel, PUSCH), a physical uplink control channel (physical uplink control channel, PUCCH), an uplink sounding reference signal (uplink sounding reference signal, SRS), or a physical random access channel (physical random access channel, PRACH). The service may be provided to a plurality of UEs by a service provider connected to the base station 110 through a backhaul network 115 (e.g., the internet). The wireless communication system 100 may include a plurality of distributed access nodes 110.

In a typical communication system, there are several modes of operation. In cellular mode of operation, communications to and from multiple UEs pass through the base station 110, while in device-to-device communication mode, e.g., in proximity services (proximity service, proSe) mode of operation, direct communication between UEs is possible. The term "base station" as used herein refers to any component (or collection of components) for providing wireless access to a network. A base station may also be generally referred to as a NodeB, an evolved NodeB (eNB), a Next Generation (NG) NodeB (NG NodeB, gNB), a master eNB (MeNB), a secondary eNB (SeNB), a master nb (MgNB), a secondary nb (nb), a network controller, a control node, an Access Point (AP), a transmission point (transmission point, TP), a transmission-reception point (TRP), a cell, a carrier, a macrocell, a femtocell, a picocell, a relay station, a customer premise equipment (customer premises equipment, CPE), a network side, a network, and so on. In the present disclosure, the terms "base station" and "TRP" may be used interchangeably unless otherwise specified. The term "UE" as used herein refers to any component (or collection of components) capable of establishing a wireless connection with a base station. UEs may also be generally referred to as mobile stations, mobile devices, handsets, terminals, user terminals, users, subscribers, sites, communication devices, CPEs, relay stations, integrated access and backhaul (Integrated Access and Backhaul, IAB) relay stations, and so on. It is noted that when using relays (based on relay stations, pico cells, CPEs, etc.), especially when using multi-hop relays, the boundary between a controller and a node controlled by the controller may be obscured, and a dual node (e.g. a controller or a node controlled by the controller) is deployed, wherein the first node providing configuration or control information to the second node is considered to be the controller. Also, the concepts of UL and DL transmissions can be extended.

A cell may include one or more UL or DL bandwidth parts (BWP) allocated for UEs. Each BWP may have its own BWP-specific system parameters and configuration, e.g., the BWP's bandwidth. It should be noted that the UE does not need to have all BWP activated. A cell may correspond to one carrier, and in some cases, may also correspond to multiple carriers. Typically, one cell (e.g., primary cell (PCell) or secondary cell (SCell)) is a component carrier (e.g., primary component carrier (primary component carrier, PCC) or secondary CC (SCC)). For some cells, each cell may include multiple UL carriers, one carrier may be referred to as an UL carrier with associated DL or a non-supplemental UL (UL) carrier, while other carriers are referred to as Supplemental UL (SUL) carriers without associated DL. A cell or carrier may be configured with a slot or subframe format including DL symbols and UL symbols, and may be considered to operate in time division duplex (time division duplex, TDD) mode. In general, for the unpaired spectrum, the cell or carrier is in TDD mode, while for the paired spectrum, the cell or carrier is in frequency division duplex (frequency division duplex, FDD) mode. The transmission time interval (transmission time interval, TTI) generally corresponds to a subframe (in LTE) or a slot (in NR). The access node may provide wireless access according to one or more wireless communication protocols of long term evolution (long term evolution, LTE), LTE advanced (LTE-a), 5G LTE, 5G NR, future 5G NR release, 6G, high speed packet access (High Speed Packet Access, HSPA), wi-Fi 802.11a/b/G/n/ac, and the like. Although it is understood that a communication system may use multiple access nodes (or base stations) capable of communicating with multiple UEs, only one access node and two UEs are shown in fig. 1 for simplicity.

One way to increase network resources is to use more available spectrum resources, including not only licensed spectrum resources of the same type as the macro, but also licensed spectrum resources of a different type than the macro (e.g., the macro is an FDD cell, but a small cell can use both FDD and TDD carriers), and also unlicensed spectrum resources and shared licensed spectrum. Part of the spectrum resources are located in the high frequency band, e.g., 6GHz to 60GHz. Unlicensed spectrum is generally available to any user, but subject to regulatory requirements. Nor is the shared licensed spectrum an operator specific spectrum. Traditionally, cellular networks do not use unlicensed spectrum, as quality of service (quality of service, qoS) requirements are often difficult to guarantee. Operating on unlicensed spectrum mainly includes wireless local area networks (wireless local area networks, WLAN), e.g., wi-Fi networks. Since licensed spectrum is generally scarce and expensive, it is contemplated that unlicensed spectrum may be used by cellular operators. Note that TDD is commonly used in both the high frequency band and the unlicensed/shared licensed band, so that communication can be performed using channel reciprocity.

In an actual deployment, the gNB may control one or more cells. The plurality of remote units may be connected to the same baseband unit of the gNB by fiber optic cables, and the delay between the baseband unit and the remote units is relatively small. Thus, the same baseband unit can handle coordinated transmission/reception of a plurality of cells. For example, the gNB may coordinate transmissions of multiple cells to the UE, referred to as coordinated multipoint (coordinated multiple point, coMP) or multi-TRP (mTRP, M-TRP) transmissions. The gNB may also coordinate the reception of multiple cells from the UE, which is referred to as CoMP/M-TRP reception. In this case, the backhaul links between these cells associated with the same gNB are fast backhaul links, scheduling of data sent in different cells for the UE can be easily coordinated in the same gNB. The backhaul connection may also have a longer delay and a lower transmission rate.

Fig. 1B illustrates the use of carrier aggregation (carrier aggregation, CA), which is another deployment strategy. As shown in fig. 1B, system 150 is a typical wireless network configured with carrier aggregation (carrier aggregation, CA), wherein communication controller 160 communicates with wireless device 165 via wireless link 170 (solid line) and with wireless device 166 via wireless link 172 (dashed line) and wireless link 170, respectively. In some example deployments, for wireless device 166, wireless link 170 may be referred to as a primary component carrier (primary component carrier, PCC), while wireless link 172 may be referred to as a secondary component carrier (secondary component carrier, SCC). In some carrier aggregation deployments, the PCC may carry feedback from the UE device to the communication controller, while the SCC may only carry data traffic. In the 3GPP specifications, the component carriers are referred to as cells. When multiple cells are controlled by the same eNB, cross scheduling of multiple cells may be achieved because there may be a single scheduler in the same eNB to schedule the multiple cells. Through CA, one eNB may operate and control several component carriers forming a primary cell (PCell) and a secondary cell (SCell).

The physical layer channels and signals include PSS/SSS, PBCH and its associated DMRS (see fig. 2A, etc., where SS bursts are embedded, i.e., multiplexed with their surrounding PBCH), PDSCH and its associated DMRS and phase tracking reference signals (phase tracking reference signal, PT-RS), PDCCH and its associated DMRS (see fig. 2B, etc., where some signals/channels are multiplexed for use by multiple UEs), and CSI-RS. CSI-RS also include CSI-RS for CSI acquisition, for beam management, and for tracking (see fig. 2C, which shows some examples of non-zero power (NZP) CSI-RS for channel estimation, interference measurement, etc., multiplexed with PDSCH for use by one or more UEs). CSI-RS used for tracking is also referred to as TRS.

The UE receives a Timing Advance (TA) command associated with a configured TA group (TAG) to adjust its uplink timing for uplink transmissions in synchronization with the network such that uplink transmissions from multiple UEs arrive at the base station substantially simultaneously within a transmission time interval (transmission time interval, TTI). Similarly, the UE needs to receive a DL reference signal (reference signals, RS) or synchronization signal (synchronization signal, SS) block, also referred to as SS/physical broadcast channel (physical broadcast channel, PBCH) block SS/PBCH block (SSB), to acquire and maintain DL synchronization by maintaining a DL timing tracking loop, etc., according to which the UE places the start of its FFT window within its DL received Cyclic Prefix (CP). In addition, both UL and DL signals/channels will be associated with some other signal to obtain signal/channel properties, e.g., delay spread, doppler frequency offset, etc.

In wireless communication operation, tracking functions performed by the UE may include fine time tracking, fine frequency tracking, delay spread estimation, and doppler spread estimation.

In fine time tracking, the UE may detect the first arrival path, based on which the UE may generally optimally place its fast fourier transform (Fast Fourier transform, FFT) window to maximize the data signal to noise and inter-symbol interference ratio. In continuous operation, the FFT window position may drift due to UE movement and residual oscillator error between the transmitter and receiver. The UE may adjust its FFT window position based on the detected change in path arrival (or arrival) time.

In fine frequency tracking, the UE may detect the frequency offset between the transmitter and receiver and adjust its oscillator accordingly. The residual frequency error may be estimated and compensated for when demodulating the data symbols. Residual frequency error compensation can be critical, especially in the case of high signal-to-noise ratio (SNR) and high code rate data transmission. Uncompensated frequency errors may introduce phase errors into the modulated data symbols and result in reduced decoding performance. Since temperature variations affect the output accuracy of the oscillator and the doppler frequency offset caused by the UE motion, the UE can track the frequency offset periodically and perform corresponding adjustments and compensation.

The delay spread determines the degree of dispersion of the radio multipath channel through which the UE passes. The longer the delay spread, the greater the frequency selectivity of the channel. In general, in channel estimation from a received pilot signal, in order to maximize a processing gain in a frequency domain, if within a coherence bandwidth of a channel, a UE may perform linear filtering having a length as long as possible. The coherence bandwidth is inversely proportional to the channel selectivity. Therefore, delay spread estimation plays an important role in forming the channel estimation filter coefficients and length, thereby affecting the performance of channel estimation and data demodulation.

The doppler spread is generally proportional to the UE movement velocity and multipath spatial distribution. The larger the doppler spread, the faster the wireless multipath fading channel will change. If within the channel coherence time constraint, the channel estimate is typically filtered in the time domain using a longer filter length to suppress noise and interference. Thus, doppler spread estimation is another factor affecting UE channel estimation performance in the time domain.

The quasi co-location (QCL) Type corresponding to each DL RS (more specifically, one or more ports or one or more antenna ports of the DL RS) is given by the higher layer parameter QCL-Type in the QCL-Info, and may take one of the following values: (1) 'QCL-TypeA': { Doppler frequency offset, doppler spread, average delay, delay spread }; (2) 'QCL-TypeB': { Doppler frequency offset, doppler spread }; (3) 'QCL-TypeC': { Doppler frequency offset, average delay }; (4) 'QCL-TypeD': { spatial Rx parameters }. The QCL type may be configured/indicated to the RS in a transmit configuration indication (transmission configuration indication, TCI) state. QCL is assumed to be mainly used for DL RS, but can be generalized to UL RS if an association relationship is specified by a path loss RS and a spatial relationship. QCL assumption may be specified as follows: { RS1 and RS2 quasi-co-located according to type C }, { RS1 and RS2 quasi-co-located according to type C and RS3 quasi-co-located according to type D }. At this time, RS1 (destination RS) acquires the attribute specified according to the QCL type from the associated (i.e., source) RS (e.g., RS 2). Note that the source RS may be SSB. Note also that the source RS and the destination RS may be on the same carrier or different carriers (i.e., across carrier QCL).

Fig. 3A is a schematic diagram 300 of QCL assumption between NR reference signals when a wide beam is used for communication. For example, a TRS, SS block, or broadcast DMRS may transmit using a wide beam. Fig. 3A shows QCL configuration between SS block 302, DMRS 304, CSI-RS 306, TRS 308, CSI-RS 310, and DMRS 312. DMRS 304 is used for a broadcast channel. That is, the DMRS 304 is a DMRS for demodulating a system information block (systeminformation block, SIB), radio resource control (radio resource control, RRC) signaling, paging, and the like before configuring the TRS. CSI-RS 306 is transmitted for beamforming. CSI-RS 310 is transmitted for channel estimation. DMRS 312 is used to demodulate signals transmitted in unicast channels. The arrow from the beginning of the first reference signal (e.g., SS block 302) to the end of the second reference signal (e.g., DMRS 304) indicates that the second reference signal has a QCL relationship with the first reference signal according to one or more QCL parameters. One or more QCL parameters (e.g., average delay, doppler bias, delay spread, and spatial RX) are shown on the arrows, indicating that one or more QCL parameters needed for the second reference signal can be obtained using the first reference signal.

As shown, DMRS 304 is configured to have a QCL relationship with SS block 302. The average delay, doppler bias, delay spread, and spatial RX of DMRS 304 may be obtained from SS block 302. Similarly, CSI-RS 306 and TRS 308 have QCL relationships with SS block 302, respectively. The average delay, doppler bias, and coarse space RX required for CSI-RS 306 may be obtained from SS block 302. The average delay, doppler bias, and spatial RX required by the TRS 308 may be obtained from the SS block 302. The CSI-RS 310 has QCL relation with CSI-RS 306 and TRS 308, respectively. CSI-RS 310 may receive using spatial RX acquired from CSI-RS 306 and using the average delay, doppler bias, and delay spread acquired from TRS 308. DMRS 312 has a QCL relationship with TRS 308 and CSI-RS 310, respectively. DMRS 312 may receive using spatial RX acquired from CSI-RS 310. The DMRS 312 may also receive using the average delay, doppler bias, doppler spread, and delay spread obtained from the TRS 308.

Fig. 3B is a schematic diagram 350 of QCL assumption between NR reference signals when a narrow beam is used for communication. Fig. 3B shows QCL configuration between SS block 352, DMRS 354, CSI-RS 356, TRS 358, CSI-RS 360, and DMRS 362. Similar to fig. 3a, the dmrs 354 is used to demodulate signals in a broadcast channel such as a physical broadcast channel (physical broadcast channel, PBCH) that is transmitted prior to configuring the TRS. CSI-RS 356 is transmitted for beamforming. CSI-RS 360 is transmitted for channel estimation. DMRS 362 is used to demodulate signals transmitted in a unicast channel. The arrow from the beginning of the first reference signal to the end of the second reference signal indicates that the second reference signal has a QCL relationship with the first reference signal according to one or more QCL parameters. One or more QCL parameters, shown on the arrow, indicate that one or more QCL parameters needed for the second reference signal can be obtained using the first reference signal. Fig. 3B shows that the reference signal has a QCL configuration similar to that shown in fig. 3A, except for the TRS. In fig. 3B, TRS 358 has a QCL relationship with SS block 352 and CSI-RS 356, respectively. TRS 358 may receive using the doppler frequency offset obtained from SS block 352 and may receive using the average delay and spatial RX obtained from CSI-RS 356. Data transmission may employ multiple narrow beams and tracking may require multiple narrow TRS beams. To support both scenarios, the TRS and its QCL assumptions or associations should be flexible to configure.

The sounding reference signal (sounding reference signal, SRS) is a reference signal sent by a User Equipment (UE) in uplink, in order to implement uplink channel estimation over a certain bandwidth. Thus, the network may be able to communicate with the UE based on the uplink channel estimate. In addition, since there is channel reciprocity of uplink and downlink in a time division duplex (time division duplex, TDD) communication system, the network can perform dynamic scheduling using SRS. That is, the network may utilize channel dependent scheduling. In this case, the time-frequency resources are dynamically scheduled in view of different traffic priorities and quality of service requirements. Typically, the UE monitors several physical downlink control channels (Physical Downlink Control Channel, PDCCH) to obtain scheduling decisions, which are signaled to the UE by the network. When a valid PDCCH is detected, the UE follows a scheduling decision, receiving (or transmitting) data.

The configuration of SRS-related parameters (e.g., SRS transmission port, SRS transmission bandwidth, SRS resource set, transmission comb and cyclic shift, etc.) of the SRS to be transmitted in the uplink is semi-static in nature and thus can be provided by high-level signaling such as radio resource control signaling. In addition, the association relationship between the downlink reference signal and the uplink SRS, such as the channel state information reference signal (Channel State Information Reference Signal, CSI-RS) or demodulation reference signal (demodulation reference signal, DMRS), should be transmitted to the UE to accurately reflect the interference situation and perform the optimal beamforming. Accordingly, there is a need for an apparatus and method for signaling control information that accurately indicates a more dynamic configuration (not semi-static) of the above-described parameters (e.g., a portion of the transmission bandwidth (and thus implicitly indicating transmission comb and cyclic shift) required when a subset of the SRS resource set is transmitted using a subset of transmission ports associated with a particular set of downlink reference signals). The signaling indication of the control information may be closely connected to the actual data transmission. The transmission of SRS may be periodic (i.e., periodic SRS, P-SRS, or P SRS) configured by layer 3RRC configuration signaling, semi-static (i.e., semi-static SRS, SP-SRS, or SP SRS) activated/deactivated by layer 2MAC CE, or aperiodic (i.e., aperiodic SRS, a-SRS, or AP-SRS, or a SRS or AP SRS) indicated by layer 1DCI in PDCCH.

3GPP has studied network adaptation or adaptive transmission, e.g., cell on/off, fast SCell activation/deactivation, SCell layer 1 dormancy, etc., to achieve efficient network adaptation for various purposes such as network/UE power saving, interference management, network/UE complexity reduction, etc. It is generally found that the SCell activation delay of NR Rel-15 is typically in the range of tens to hundreds of milliseconds, in many cases even longer than that of LTE. Therefore, it is desirable to reduce SCell activation delay. The large delay in activating the SCell is mainly caused by the time gap associated with SSB measurement timing configuration (SSB measurement timing configuration, SMTC) which is configured for the UE to monitor and process SSBs every tens of milliseconds in the usual case. According to SSB, the UE can obtain necessary information to set its AGC, acquire timing, and perform frequency synchronization. In contrast, in LTE SCell activation, these operations are based on uninterrupted CRS (e.g., periodic CRS with shorter intervals), and thus may be completed faster.

Fig. 4 shows an example of the SCell activation timeline for the current 5G NR Rel-15/16. In fig. 4, referring to the slots for PUCCH transmission, when the UE receives an activate command in PDSCH ending with slot n for the secondary cell, the UE performs the corresponding operation defined in TS 38.321 in a time no later than the minimum requirement defined in TS 38.133 and no earlier than slot n+k, except for the following operations:

-an operation related to CSI reporting on the activated serving cell in time slot n+k;

-an operation performed by the UE in time slot n+k in relation to sCellDeactivationTimer, wherein sCellDeactivationTimer is associated with the secondary cell;

-operations related to CSI reporting on a serving cell that is not active in time slot n+k, wherein the UE performs these operations in the earliest time slot after time slot n+k that the serving cell has been active.

The value of k isWherein k is ₁ Is the number of slots of PUCCH transmission including HARQ-ACK information for PDSCH reception and by PDSCH-to-harq_feedback timing indicator in DCI format for scheduling PDSCH reception as described in section 9.2.3 in TS 38.213Field to indicate +.>Is the number of slots of SCS configuration μ for PUCCH transmission per subframe.

Referring to slots for PUCCH transmission, if the UE receives a deactivation command for the secondary cell ending in slot n (see TS 38.321, etc., the entire contents of which are incorporated herein by reference), the UE performs a corresponding operation (see TS 38.321, etc.) no later than the minimum requirements defined in TS 38.133 (both TS 38.133 and TS 38.321 are incorporated herein by reference), except for the operation performed by the UE in slot n+k that is related to activating CSI reporting on the serving cell.

If sCellDeactivationTimer associated with the secondary cell expires in slot n, the UE performs the corresponding operation in TS 38.321 no later than the minimum required time defined in TS 38.133, but the UE is in slotExcept for the operations performed in the first time slot thereafter related to activating CSI reporting on the serving cell, where μ is the SCS configuration for PDSCH reception on the secondary cell.

Table 1: number of OFDM symbols per slot, number of slots per frame, and number of slots per subframe under normal cyclic prefix

On and after time slot n+k, the following operations are performed:

<1> receiving SCell activation/deactivation MAC CE, activating SCell:

<2> if the SCell is deactivated before receiving the SCell activation/deactivation MAC CE; or alternatively

<2> if the SCell is configured with sCellState set to active at SCell configuration:

<3> if the first actiondownlinkbwp-Id is not set to dormant BWP:

<4> activating scells according to the timing defined for MAC CE activation in TS 38.213 and the timing defined for direct SCell activation in TS 38.133; that is, performing normal SCell operations includes:

<5> SRS transmission on scell;

<5> CSI reporting for SCell;

<5> PDCCH monitoring on scell;

<5> PDCCH monitoring for SCell;

<5> PUCCH transmission on scell, if configured.

<3> otherwise (i.e., first actiondownlinkbwp-Id set to dormant BWP):

<4> stop bwp-InactivityTimer of the serving cell if it is running.

<3> activates DL BWP and UL BWP indicated by firstactioninkbwp-Id and firstactionupinkbwp-Id, respectively.

<2> turning on or restarting sCellDeactivationTimer associated with SCell according to timing defined for MAC CE activation in TS 38.213 and timing defined for direct SCell activation in TS 38.133;

<2> if the activated DL BWP is not the dormant BWP:

<3> initializing (re-initializing) any pending configuration uplink grants of configuration grant type 1 associated with the SCell according to the stored configuration (if any) and starting from the symbol according to the rules in clause 5.8.2.2 of TS 38.321;

<3> PHR was triggered according to clause 5.4.6 of TS 38.321.

Fig. 4 shows part of the reasons for the long SCell activation delay, including: (1) The SSB duty cycle is long, and one or more SSBs (e.g., time F (402)) may be required; (2) AP CSI reporting (and possibly CSI measurements made for this) can only be triggered after time I (404); (3) If SRS is needed, further delays are expected. Note that the first P/SP CQI may be optional; the first AP CQI may be optional and may be co-carrier/cross-carrier triggered/reported.

In order to reduce SCell activation delay, it is critical to reduce or avoid relying on SSBs to obtain the necessary information about these operations during SCell activation. How much delay can be reduced depends on the scenario and mechanism applied. The following aspects are currently being considered. First, if the UE does not know information about the SCell at all, reducing the potential activation delay depends on how the UE is made aware of the SCell, e.g., providing SCell SSB related information. More generally, even though the UE is SCell aware, other functions are required during activation, such as AGC settling, time/frequency tracking, CSI measurement/acquisition, etc. For this purpose, it may generally be considered that one or more transmissions of one or more RSs are made during the activation process, so that the UE/network can acquire the information required for the activation. These RSs may be referred to as temporary RSs. On the other hand, if the UE already knows a lot of information about SCell but has not been fully used in the Rel-15 mechanism, the reduced delay is expected to be more considerable by supporting the new standard. This information may come from the past activation duration, e.g., timing, which is slowly deviated after deactivation, but still available as a reference. Such information may also come from another cell described later. In either case, the necessary information to make the UE unavailable may be made available to the UE to shorten the activation delay, which may be based on network signaling of information sent to the UE or based on network signals (mainly reference signals, RSs, sometimes including PSS/SSS) sent specifically for efficient activation purposes. These RSs may be referred to as temporary RSs (tempRS or temp RSs); if the temporary RS is RS X-based, it may also be referred to as X-based temporary RS; if the temporary RS is AP TRS based, it may also be referred to as temporary AP TRS or temporary TRS; if the temporary RS consists of only TRSs, it may also be referred to as AP TRSs or TRSs, etc.

As mentioned above, there are different scenarios where different functions are required. These scenarios include at least a known SCell and an unknown SCell, which means that the activation process may or may not require SSB. In addition, AGC stabilization typically requires TRS and/or CSI-RS. Time/frequency tracking typically requires TRS. CSI measurement/acquisition typically requires CSI-RS and CSI reporting and/or SRS. However, due to the high RS overhead and processing complexity, forcing all of these RSs to be sent and processed during activation may not be practical. This means that different RSs and different procedures can be employed in different situations. Thus, there is a need to provide a flexible framework to configure and trigger temporary RSs with reasonable overhead and complexity.

The temporary RS is supported at least in case of known cells to accelerate the activation procedure during SCell activation, thereby achieving efficient SCell activation both in frequency range 1 (frequency range 1, fr 1) and in frequency range 2 (frequency range 2, fr 2). The temporary RS may provide at least AGC settling and time/frequency tracking functions during SCell activation. The TRS may also have potential functions for CSI measurement/acquisition and cell search.

The TRS is selected as a temporary RS for SCell activation. Other RS candidates, e.g., aperiodic CSI-RS, P/SP-CSI RS, SRS, and SSS/PSS based RS, are also contemplated. The TRS should be triggered by DCI or MAC-CE. In the SCell activation process, the UE measures the triggered temporary RS in a time not earlier than slot m.

In addition to the TRS as a temporary RS, the following candidate RSs may be considered.

Aperiodic CSI-RS for deactivating scells

CSI acquisition is an essential component of SCell activation, and therefore in LTE and NR, it is always required to send valid CSI reports as part of the SCell activation latency requirement of RAN 4. Reducing CSI acquisition time may reduce SCell activation latency. CSI acquisition may be performed by DL CSI-RS (and CSI-IM resources; to be further discussed) and UE CSI reporting, as well as by UL SRS (to be further discussed). DL-based CSI acquisition may consider aperiodic CSI-RS and periodic/semi-static CSI-RS. However, periodic/semi-static CSI-RS can only be transmitted with a predetermined period and slot offset, which generally does not reduce the activation delay. On the other hand, aperiodic CSI-RS is more flexible and thus can be triggered immediately at the beginning of the activation procedure. Thus, aperiodic CSI-RS may be included as an optional temporary RS.

During SCell activation, it may not be necessary to trigger an aperiodic CSI-RS as a temporary RS every time. If the network wishes to report the DL CSI quickly, the network should be able to trigger an optional aperiodic CSI-RS, otherwise the network may decide not to trigger the aperiodic CSI-RS.

Multiple aperiodic CSI-RSs may be triggered if one transmission of the aperiodic CSI-RS is insufficient (by one trigger if overhead reduction is considered). The total energy consumption associated with receiving the aperiodic CSI-RS is less than the total energy consumption associated with receiving the periodic CSI-RS, especially if the deactivation duration is long and the period is short. Since the MAC CE-based CSI-RS trigger guarantees a sufficient trigger offset (at least 3ms timing offset and additional K0 slot offset), the UE does not need to be ready to receive aperiodic CSI-RS and generate aperiodic CSI-RS reports at any time. The trigger offset may provide the UE with enough time to respond to aperiodic triggers.

Aperiodic CSI-IM and aperiodic CSI

In order for the UE to generate an efficient CSI report, CSI-IM resources are required. Thus, each Aperiodic (AP) CSI-RS may also be configured with one or more AP CSI-IM resources, and one or more AP CSI-IM resources may also be transmitted when transmitting the AP CSI-RS. Thus, one or more AP CSI-IM resources are also considered to be a temporary RS or part of a temporary RS resource. In this sense, the L1 AP CSI-RS trigger currently discussed by RAN1 may be better interpreted as an L1 AP CSI trigger. The AP CSI trigger triggers a combination of one or more AP CSI-RSs and one or more AP CSI-IM resources, and CQI and/or L1 SINR are reported according to the CSI-RS/CSI-IM. The timing relationships and configurations of the AP CSI trigger, the AP CSI-RS, the AP CSI-IM and the AP CSI report are generally the same as conventional.

SRS for deactivating SCell

It is well known that SRS can be used to provide DL full MIMO CSI in TDD systems, UL CSI in TDD/FDD, keep-alive Timing Advance (TA), UL power control and UL/DL beams. Therefore, SRS is important for the SCell to be activated to reacquire CSI, TA, power control and beam. In case the pathloss RS of SRS is on the active cell, the UE may be able to send SRS on the SCell to be activated without waiting for DL AGC to stabilize. In fact, the SCell may not be able to fully function as a "fully activated" SCell until its UL is also ready, which may be achieved by SRS transmission. In addition, using SRS in the activation may transfer part of the processing from the UE to the network, thereby reducing UE processing complexity. Regarding aperiodic SRS and periodic SRS, similar to CSI-RS analysis, aperiodic SRS is better suited to reduce SCell activation latency. Thus, the SRS may also be used as an optional temporary RS.

The aperiodic SRS as a temporary RS may not have to be configured/triggered for each deactivated SCell. The network should be able to configure/trigger an optional aperiodic SRS if the network requires UL CSI under FDD/TDD, DL CSI under TDD, UL TA, UL power control or UL beam management, otherwise the network may decide not to configure/trigger the aperiodic SRS.

SSB

The UE may or may not be aware of the SCell to be activated.

If the UE knows the SCell to be activated, no cell search/cell detection is required. In addition, SSB and associated P/SP TRS as QCL sources of temporary RS may at least provide the UE with functions such as time/frequency coarse tracking during activation; from these functions, the UE may be able to receive the AP TRS and further improve AGC and time/frequency tracking. The existing QCL type between SSB and other RSs can be reused, so no further enhancement of QCL type is required. For example, an AP TRS may be quasi-co-located with a P TRS, which may be further quasi-co-located with an SSB by type C (optionally by type D), an NZP CSI-RS may be quasi-co-located with an SSB by type a (optionally by type D), an AP TRS may be a QCL source for one or more other RSs (including P/SP TRS) after the AP TRS that are present during and after activation, and so on. Embodiments in this disclosure where there is an SP TRS may be interpreted as "if SP TRS is also supported".

However, if the UE does not know the SCell to activate, the SSB may be triggered and sent as a temporary RS for cell search/cell detection. According to the RAN4 reply, in some cases no cell detection is needed, but in other cases cell detection is needed, SSBs may be used as in conventional procedures, and on-demand transmission of aperiodic SSBs may be reduced by more delays than periodic SSBs. Thus, the aperiodic SSB should be considered as a temporary RS of an unknown cell.

For aperiodic triggering of SSBs, the UE may not know the precise timing of the RS-based SSS/PSS due to the uncertainty in the potential timing. Thus, in case of activating an unknown SCell, a search time window of SSS/PSS based RSs may be configured or indicated to the UE.

Cross-carrier RS in cases dependent on activation of in-band cells (e.g., case 2 and case 3)

The AP TRS may rely on a cross-carrier signal, e.g., if the SCell to be activated is unknown, the AP TRS may be considered quasi co-sited with a cross-carrier SSB or a cross-carrier P/SP TRS. The cross-carrier SSB or P/SP TRS should be on an active carrier, which is typically an in-band carrier (even a more powerful in-band contiguous/adjacent carrier), and should be configured/received for the UE before the activation process begins.

Providing the UE with appropriate network assistance information and/or assumptions of the UE's common attributes for multiple serving cells may enable efficient SCell activation, and thus standardization should be considered. According to the network configuration and standard specifications, the UE may assume some common properties among multiple serving cells, so the UE may already have acquired a lot of information about the SCell to be activated, but has not yet been fully used in the Rel-15 mechanism. In practice, one reason for multiple serving cells sharing some common properties is that the cells may be co-located and associated with the same hardware, which may be the same set of antennas, the same RF components, etc. This is especially the case if the carriers of the cells are in the same frequency band (e.g., in-band CA) or in frequency bands close to each other. The 3GPP has defined several quasi co-located (QCL) relationships between antenna ports of different signals so that the properties obtained from one signal can be extended to another signal. The concept can be utilized and generalized to effectively reduce the SCell activation delay in applicable scenarios.

Two quasi co-sited serving cells may share one or more of the following attributes, and the UE may use each attribute to obtain side information about the SCell to be activated to reduce latency.

Path loss, coupling loss or RSRP

If the carriers of the two cells are very close in the frequency domain, e.g. in intra-band CA (continuous or even discontinuous), the path loss values and shadow fading values of the two cells are substantially the same. Furthermore, if the same set of antennas is used, the antenna gain as well as the coupling loss value and RSRP value of both cells are also very close. For cells where the carriers are not so close but not so far apart as to be highly uncorrelated, the difference between the pathloss values may be a predictable value that the UE and/or the gNB may obtain.

The path loss, coupling loss or RSRP side information of the SCell to be activated may be used to set the (initial) AGC, which helps to speed up the activation. Further embodiments are provided below.

Frequency/timing offset

Also, frequency/timing information about scells to be activated may be acquired from other cells. Even if this information is insufficient to enable fine tracking, it still helps to reduce the delay involved in implementing frequency/time tracking. For example, if the symbol boundaries of two cells are approximately aligned, e.g., within the CP length (or have a fixed offset), the UE may be able to set its FFT window for one cell according to the other cell, and may be further refined according to the temporary RS. Note that scells without SSB have utilized this mechanism, as specified in TS 38.213: "for a serving cell where there is no SS/PBCH block transmission, the UE acquires time-frequency synchronization with the serving cell according to reception of SS/PBCH blocks on PCell or PSCell in the cell group of the serving cell. "

However, without network assistance or standardized UE behavior, including UE capability reporting, the UE cannot assume any common attributes between serving cells. Further embodiments are to be provided. The present embodiment techniques may assign network signaling to UEs regarding side information and UE hypotheses with side information. There are some ways (not mutually exclusive) to support this.

Configuring cross-carrier QCL attributes

An RS transmitted by one cell may be configured to be quasi co-located with another RS transmitted by another cell. For example, a TRS on a deactivated SCell may be quasi co-located with an SSB on an activated serving cell, where the activated serving cell may be on a carrier that is in-band and contiguous (adjacent) with the SCell to be activated within FR1 or in-band with the SCell to be activated within FR 2.

Introducing new QCL types for path loss across carriers, RSRP and frequency/time synchronization

Existing QCL types can be generalized to define that the UE can assume the new properties listed above if signaled through the network. The QCL relationship may be signaled by reference to a cell index, SSB or RS. For example, the SSB of cell 1 may be configured to be quasi co-located with the SSB of cell 2. Since this relationship between cell 1 and cell 2 is reciprocal, the UE may assume the opposite direction without configuring the opposite direction. This relationship can be specified in the standard for in-band and in-band carriers within FR1 and in-band carriers within FR2 if no additional signaling is employed.

Introducing cell sets sharing common attributes

More generally, the common attributes described above are shared among multiple cells, e.g., an in-band neighbor cell (e.g., within FR 1), an in-band cell (within FR 2), or a cell sharing the same PA/RF in neighboring frequency bands. Thus, it may be useful to introduce a set of cells with common properties. This may be similar to TAGs, i.e. cells are configured in multiple TAGs, cells within the same TAG sharing the same TA.

Introducing offset values

Even if some properties between two cells are not the same, there may be a fixed offset (or offset with an upper limit) between them that is known to the network or that is available to the UE. The network may signal the offset value to the UE. For example, if the symbol boundary of cell 1 is x ms earlier than the symbol boundary of cell 2, the value of x may be signaled to the UE, which may use the value to acquire coarse timing. As another example, if the path loss of cell 1 is higher than the path loss of cell 2 by y dB, the y value may be signaled to the UE to estimate its initial AGC setting. Alternatively, the UE may acquire the offset value according to separation of cells or the like.

Thus, efficient SCell activation may be supported by enhanced UE assumptions to reduce delays associated with estimating path loss, coupling loss, RSRP, frequency/timing offset, and/or initial UL TA on the SCell to be activated. Examples include at least the following:

-utilizing a cross-carrier QCL assumption (e.g. SCell to be activated relies on active quasi co-sited cells for initial pathloss/RSRP estimation);

using a set of configured cells with common properties (e.g. cells within one or more frequency bands close to each other in frequency are configured in a set of cells with similar path loss/timing);

using a specified cross-carrier offset value (e.g., the network specifies a path loss/timing offset between two cells or between two sets of cells).

However, in some cases, the UE may not be able to obtain all necessary information from the available UE hypotheses. At this time, the temporary RS may be reused to support efficient SCell activation by providing the UE with information that cannot be acquired from the available UE hypotheses.

Different situations may require a certain number of temporary RS bursts. For example:

the SCell to be activated is known and belongs to FR1

If the SCell measurement period is equal to or less than 160ms,

■ The temporary RS may be used for time/frequency tracking.

● According to the RAN1 working assumption about the temporary RS design provided in LS R1-2009798 (3 GPP TSG RAN WG1 conference #103-e electronic conference, 10 months 26 days to 11 months 13 days 2020), 1 burst (2 slots with 4 CSI-RS resources) is required, the entire contents of LS R1-2009798 are incorporated herein by reference, and partial content transfer is as follows.

If the SCell measurement period is greater than 160ms,

■ The temporary RS may be used for AGC.

● 1 burst (2 slots with 4 CSI-RS resources) may be required.

■ The temporary RS may be used for time/frequency tracking.

● In addition to one burst required for AGC, 1 separate burst (2 slots with 4 CSI-RS resources) may be required.

■ The above protocol may be applicable according to the RAN1 working assumption provided in LS R1-2009798 regarding the temporary RS design.

■ A minimum gap between one or more RS symbols for AGC and RS symbols for time/frequency acquisition is required to take into account UE AGC application delay. The minimum gap length may include:

● Option 1: a number of 2 time slots is used,

● Option 2:2ms.

SCell is unknown and belongs to FR1.

When SCell is continuous with activated serving cell in the same frequency band (in-band continuous CA),

■ The UE may perform AGC adjustment according to the temporary RS.

● When the power difference between the serving cell and the SCell to be activated is less than or equal to 6dB, only one temporary RS burst of "2 slots with 4 CSI-RS resources (4 samples)" may be required.

■ If the conditions specified for the in-band continuous CA case in section 8.3.2 of TS 38.133 are met, no cell detection is performed.

■ The UE may perform time-frequency tracking according to the temporary RS.

● Only one temporary RS burst of "2 slots with 4 CSI-RS resources (4 samples)" may be required.

■ The above protocol applies according to the RAN1 working assumption provided in LS R1-2009798 regarding the temporary RS design.

The SCell to be activated belongs to FR2.

If there is at least one activated serving cell on the FR2 band, and a temporary RS is provided for the target SCell, then whether the SCell to be activated is known or unknown,

■ The temporary RS may be used for time/frequency tracking.

● Only 1 burst of "2 slots with 4 CSI-RS resources (4 samples)" may be required.

If there is no activated serving cell on this FR2 band, and the UE knows the SCell to be activated,

■ The temporary RS may be used for fine timing tracking.

If the SCell in activation is unknown, and there is no activated serving cell on the FR2 band,

■ The temporary RS cannot be used for AGC.

■ Whether or not the case of temporal RS-based time/frequency tracking to enhance SCell activation delay is considered is not concluded.

Table 2 below summarizes the number of TRS bursts required in several cases.

Table 2: overview of RAN4 requirements for 2-slot TRS burst numbers

Table 3 below outlines the case with complete RAN4 inputs, which may be an important point for RAN1 design.

Table 3: an overview of all cases with complete RAN4 input (number of valued 2 slots

Proposal 1: prioritizing the following cases with full RAN4 input:

case 1: FR1, known as SCell

o case 1a: the measurement period is less than or equal to 160ms

o case 1b: measurement period >160ms

Case 2: FR1, unknown SCell, with active in-band continuous cells, ΔTxP less than or equal to 6dB

o case 2a:

o case 2b:

-case 3: FR2, known as SCell, has active in-band cells

Exemplary trigger configurations, trigger commands, and trigger procedures are discussed herein. The current activation procedure uses L2 signaling. With the various enhancements proposed in Rel-17, the delay can be significantly reduced, further reducing the delay caused by L2 signaling may be significant. L1 signaling may be used for its low latency. Note that L1 activation does not necessarily represent newly designed L1 signaling or L1 procedures; instead, the existing L1 signaling can be reused like the existing aperiodic RS. Once the UE receives L1 signaling associated with deactivating the SCell, the L2 activation process may begin. Thus, if the activation procedure involves aperiodic CSI-RS resource triggers and/or aperiodic CSI reporting triggers, the network and UE may use one or more of these triggers associated with deactivating the SCell as an activation command for the SCell. This approach not only reduces the delay of L2 signaling and possibly multiple signaling to complete one activation, but also limits control channel overhead. A potential problem with this approach is the reliability of the DCI without ACK/NACK/HARQ, while MAC commands are present. Thus, if the DCI is missed or decoded in error, the network and UE may be temporarily out of sync until the network and/or UE find the problem and correct it. However, the probability of such errors occurring is small (typically < 1%), so DCI-based approaches are still beneficial for most scenarios.

Note that in this case, it may not be necessary to send MAC signaling for activation. For embodiments using MAC signaling, the MAC signaling is also accompanied by L1 signaling, which makes MAC signaling unnecessary.

According to an example embodiment, efficient SCell activation may be supported by existing L1 AP RS (e.g., TRS/CSI-RS/SRS based temporary RS (if agreed)) triggers using an enhanced activation procedure, and SCell activation procedure may be initiated when a UE receives a temporary RS trigger associated with the SCell.

Embodiments of SCell activation trigger (i.e., activation command) configuration and temporary RS configuration are provided. For the configured SCell, the TRS, optionally the AP CSI-RS, optionally the AP SRS is configured. These RSs may be useful in SCell activation procedures. For all possible ways of triggering SCell activation, at least the TRS may always be sent during SCell activation: the trigger is triggered by MAC signaling, by AP TRS L1 of the TRS, by CSI-RS associated with the SCell and AP CSI-RS L1 of the TRS, or by SRS associated with the SCell and AP SRS L1 of the TRS. Thus, there are the following components and possible ways:

the mandatory components for SCell activation may be as follows:

-a MAC activation command (but not necessarily sent) always supporting activation of scells;

the AP TRS is always configured with SCell and thus always sent during SCell activation.

Optional components for SCell activation may be as follows:

AP TRS trigger (sent on another cell) that triggers the AP TRS. Upon receipt, SCell activation begins without a MAC activation command.

The AP CSI-RS may be configured with scells, thus also transmitting the AP CSI-RS if SCell activation starts;

-an AP CSI-RS trigger (transmitted on another cell) triggering the AP CSI-RS. Upon receipt, SCell activation begins without a MAC activation command.

The AP SRS may be configured with scells, so if SCell activation starts, the AP SRS is also transmitted;

AP SRS triggering (transmitted on another cell) triggering AP SRS. Upon receipt, SCell activation begins without a MAC activation command.

Fig. 5 is a schematic diagram 599 supporting SCell activation. As shown in fig. 5, the optional components for SCell activation may include:

a MAC activation command (but not necessarily sent) always supporting activation of scells,

Optional components for SCell activation may include:

Fig. 6 is a flow chart 600 of an exemplary configuration process provided by some embodiments. In operation 602, a TRS is configured for SCell activation. In operation 604, an AP CSI-RS is configured for SCell activation. In operation 606, the AP SRS is configured for SCell activation. In operation 608, the UE may perform SCell activation according to at least the configured TRS, optionally according to at least one of the configured AP CSI-RS or the configured AP SRS. Thus, configuration operations 604 and 606 may be optional. Further, the configuration herein may be to transmit higher layer signaling (e.g., RRC signaling) to the UE to configure the TRS, AP CSI-RS, or AP ARS.

Embodiments of SCell activation triggers and activation procedures are provided. In one embodiment, an Aperiodic (AP) TRS is transmitted during SCell activation. SCell activation may be initiated by a MAC command (L2 signaling) during which an AP TRS is sent. SCell activation may be initiated by DCI (L1 signaling) during which an AP TRS is sent. AP TRS triggering may not be required. Since SCell activation is associated with an AP TRS, the AP TRS may be configured for SCell for activating SCell. The AP TRS may be configured independent of the SCell BWP, that is, the same AP TRS may be transmitted regardless of the BWP into which the SCell is activated, which may simplify the activation design. Alternatively, the AP TRS may be dedicated to SCell BWP, triggering the AP TRS resulting in activating the associated BWP. If explicit signaling of an AP TRS or BWP is not expected to exist, a default BWP and its associated default AP TRS may be transmitted. Four embodiments are shown below.

Fig. 7 is a schematic diagram 700 of a first exemplary embodiment for SCell activation triggering and activation. As shown in fig. 7, the gNB sends a MAC activation command for a deactivated SCell configured with a default AP TRS and optionally a default AP CSI-RS and/or AP SRS. This initiates an SCell activation procedure. The MAC activation command may use an existing design in which the information of the TRS/CSI-RS/SRS is not provided, but the associated default TRS/CSI-RS/SRS configured through RRC signaling is automatically triggered. Multiple AP TRSs (or CSI-RS/SRS) may be configured to or for the SCell activation procedure, but one of them is configured as a default value. The default value may be configured explicitly or implicitly by a BWP configuration, e.g. several AP TRSs are associated with several BWP of the SCell, respectively, one BWP is signaled as a default value for this activation, and then the default AP TRS associated with the default BWP is triggered. This reduces MAC/DCI signaling overhead, avoiding the design of new MAC activation commands. Alternatively, the MAC activation command may be a use enhancement design, for example, further comprising one or more fields to trigger one or more or one of the BWP in the TRS/CSI-RS/SRS. This requires more MAC overhead but provides more flexibility for the network. For example, if two or more TRSs are associated with the SCell, the MAC command may activate/select one (e.g., one TRS is associated to BWP, by selecting TRSs or selecting BWP, the associated BWP/TRSs are also activated/selected) or a plurality thereof. Then, after the AP TRS, the associated RS (CSI-RS/SRS) is also transmitted/received/processed according to the network configuration/activation. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Then, valid DL CSI is reported from the UE to the gNB, which typically includes at least valid CQI values. Some embodiments of this aspect are discussed further below. After that, SCell activation is completed, and SCell is activated.

Fig. 7 also shows that the gNB sends an L1 AP TRS trigger associated with deactivating the SCell. In case no L2 command is received, the UE still understands that this initiates the SCell activation procedure. The AP TRS associated with the trigger may or may not be a default AP TRS, which provides the network with greater flexibility to select an AP TRS to send or a BWP to activate. For example, a default TRS (TRS 1) may be associated with default BWP1, but L1 AP TRS triggers are for TRS2 and BWP2, when the UE understands that SCell activation is to put BWP2 in an active state. Then, after the AP TRS, the associated RS (CSI-RS/SRS) is also transmitted/received/processed according to the network configuration/activation. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Then, valid DL CSI is reported from the UE to the gNB, which typically includes at least valid CQI values. Some embodiments of this aspect are discussed further below in this disclosure. After that, SCell activation is completed, and SCell is activated.

Fig. 7 also shows that the gNB transmits an L1 AP CSI-RS trigger associated with deactivating the SCell. In case no L2 command is received, the UE still understands that this initiates the SCell activation procedure. The AP CSI-RS associated with the trigger may or may not be a default AP CSI-RS. The AP CSI-RS is associated with some default TRS, optionally with default SRS and BWP, which provides the network with more flexibility to select the AP CSI-RS/TRS/SRS to be transmitted or the BWP to be activated. For example, a default TRS (TRS 1) may be associated with default BWP1 and default CSI-RS1, but the L1 AP CSI-RS trigger is for CSI-RS2, CSI-RS2 being associated to BWP2 and TRS2, at which point the UE understands that SCell activation is to put BWP2 in an active state, with TRS2/CSI-RS2 being expected to be present. Then, after the AP TRS2, the AP CSI-RS2 is transmitted and received. Optionally, the AP SRS is transmitted according to configuration/activation, optionally, the UE reports valid DL CSI to the gNB, which generally includes at least a valid CQI value. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Some embodiments of this aspect are discussed further below in this disclosure. After that, SCell activation is completed, and SCell is activated.

Fig. 7 also shows that the gNB transmits an L1 AP SRS trigger associated with deactivating the SCell. In case no L2 command is received, the UE still understands that this initiates the SCell activation procedure. The AP SRS associated with the trigger may or may not be a default AP SRS. The AP SRS is associated with some default TRS, optionally with default CSI-RS and BWP, which provides the network with more flexibility to select the AP CSI-RS/TRS/SRS to be transmitted or the BWP to be activated. For example, a default TRS (TRS 1) may be associated with default BWP1 and default SRS1, but the L1 AP SRS trigger is for SRS2, SRS2 being associated to BWP2 and TRS2, at which point the UE understands that SCell activation is to put BWP2 in an active state, expects to receive TRS2 and transmit SRS2. Then, after the AP TRS2, the AP SRS2 is transmitted. Optionally, the AP CSI-RS is sent according to configuration/activation, optionally, the UE reports valid DL CSI to the gNB, which generally includes at least a valid CQI value. Some embodiments of this aspect are discussed further below in this disclosure. After that, SCell activation is completed, and SCell is activated.

Fig. 8 is a schematic diagram 800 of a second exemplary embodiment for SCell activation triggering and activation. As shown in fig. 8, in operation 802, the gNB transmits a MAC activation command for deactivating the SCell in slot n. The MAC CE may be carried in the PDSCH, which is transmitted on the active serving cell. In operation 804, the UE needs to transmit ACK/NACK for PDSCH with MAC CE. If the PDSCH with the MAC CE is successfully decoded, an ACK can be sent, which initiates an SCell activation process; otherwise, a NACK may be transmitted, the gNB may have to transmit another PDSCH with MAC CE, and the SCell activation procedure may begin in the slot in which the ACK is transmitted. T slots may be required from receiving PDSCH with MAC CE to ACK. In some cases, t=3 (i.e., the time required for the UE to decode MAC signaling). The value t may also be other UE capability related value, which may be before the UE sends an ACK. The value t may also include other delays required for the UE to process the MAC CE and perform operations in L1. In either case, the network and the UE need to have a common reference timing in order to transmit/receive the remaining signals without other signaling, one embodiment of the common reference timing being the slot of the ACK and another embodiment of the common reference timing being the slot after the ACK so that the UE L1 is ready. Then, in operation 806, the gNB may transmit an AP TRS to the UE in a slot n+t+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. This may be related to UE capabilities, after which the gNB configures the AP TRS trigger offset. This allows the UE sufficient time to prepare for receiving the AP TRS. The AP TRS is configured in advance for SCell activation. Triggering of the TRS is not required, which reduces signaling overhead and delay. In case of configuring a plurality of AP TRSs for SCell activation, configuring one of them as default, transmitting the default AP TRS, and not transmitting the other AP TRSs; some embodiments were described previously. The MAC CE may also be enhanced to include a trigger for one of the AP TRSs to be selected. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. At least one of the default AP CSI-RS and the default AP SRS should be configured for SCell activation. Then, if the SCell activation procedure is also configured with a default AP CSI-RS with a trigger offset k_csi-RS, then in operation 808 the AP CSI-RS may also be sent to the UE in time slot n+t+k_csi-RS. The default AP CSI-RS may be identified based on the default AP CSI-RS being a BWP associated with the triggered AP TRS. No triggering of CSI-RS is required, which reduces signaling overhead and delay. The CSI-RS may be received after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, and thus the network should generally ensure k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slots n+t+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in multiple slots, the AP CSI-RS may be transmitted in slots n+t+k_trs+k+k_csi-RS, where k is the number of slots in which the AP TRS transmission is present, and k is specified in the RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the CSI-RS is based on a sufficient number of time domain samples in the TRS. From the CSI-RS, the UE may generate an AP CSI report, which should include at least a valid CQI. Then, in operation 810, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 812) is completed. Note that if the default AP SRS is also configured/identified for SCell activation procedure, the UE should send AP SRS, possibly after TRS, before or after CSI-RS. No triggering of SRS is required, which reduces signaling overhead and delay. Embodiments of AP SRS transmission are further described. In addition, the AP TRSs are generally not independent RSs (i.e., they rely on the P/SP TRSs), and the AP TRSs and the P/SP TRSs are mutually quasi co-located, in particular, the AP TRSs should rely on the P/SP TRSs. However, in some cases, the AP TRS cannot rely on the P/SP TRS on the SCell for deactivation of the SCell. There are several embodiments. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS should be on an active carrier, which is typically an in-band carrier, and the cross-carrier SSB or P/SP TRS should be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive slots following slot n+t+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts in operation 814 after SCell activation is completed if the P/SP TRS is configured with the AP TRS.

Fig. 9 is a schematic diagram 900 of a third exemplary embodiment for SCell activation triggering and activation. As shown in fig. 9, in operation 902, the gNB transmits a MAC activation command for deactivating the SCell in slot n. In step 904, the MAC CE is carried in the PDSCH, which is transmitted on the active serving cell. The UE needs to transmit ACK/NACK for PDSCH with MAC CE. If the PDSCH with the MAC CE is successfully decoded, an ACK can be sent, which initiates an SCell activation process; otherwise, a NACK may be transmitted, the gNB may have to transmit another PDSCH with MAC CE, and the SCell activation procedure may begin in the slot in which the ACK is transmitted. T slots may be required from receiving PDSCH with MAC CE to ACK. The value t may also include other delays required for the UE to process the MAC CE and perform operations in L1. Then, in operation 906, the gNB may transmit an AP TRS to the UE in a slot n+t+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured in advance for SCell activation. Triggering of the TRS is not required, which reduces signaling overhead and delay. In case of configuring a plurality of AP TRSs for SCell activation, configuring one of them as default, transmitting the default AP TRS, and not transmitting the other AP TRSs; some embodiments were described previously. The MAC CE may also be enhanced to include a trigger for one of the AP TRSs to be selected. The AP TRS may repeat within one slot or between different slots. Then, if the SCell activation procedure is also configured with a default AP SRS with a trigger offset k_ SRS, the UE may also transmit the AP SRS in slot n+t+k_ SRS in operation 908. The default AP SRS may be identified based on the default AP SRS being a BWP associated with the triggered AP TRS. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n+t+k_trs+k_ SRS, which ensures that the SRS is later than the TRS. If the TRS is transmitted in multiple slots, the AP SRS may be transmitted in slots n+t+k_trs+k+k_ SRS, where k is the number of slots in which the AP TRS transmission is present, and k is specified in an RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the SRS is based on a sufficient number of time domain samples in the TRS, e.g., for path loss estimation as discussed later. However, in either case, the time gap between receiving the TRS and transmitting the SRS may be shorter than the time gap between receiving the TRS and receiving the AP CSI-RS, because the SRS may be transmitted without waiting for AGC settling (which is typically required for receiving the CSI-RS). The UE is ready to transmit SRS as long as it acquires tracking from the AP TRS. Thus, in one embodiment, the AP SRS slot is n+t+k_trs+t_ SRS, where t_ SRS < k_ SRS is a value specified by the network. For example, t_ SRS may be 1 slot (that is, if the frame structure allows, the SRS may be transmitted in a slot immediately after the TRS (e.g., the slot is an UL slot or a flexible slot including UL symbols)). According to the SRS, gNB can acquire partial DL MIMO CSI of the FDD system, full DL MIMO CSI of the TDD system, full UL MIMO CSI under FDD/TDD and UL power control/timing advance information. If the default AP CSI-RS is not configured for SCell activation, the slot in which the SRS is transmitted may be considered as the time when SCell activation is complete (that is, SCell is activated in operation 910). Note that if the default AP CSI-RS is also configured/identified for the SCell activation procedure, the UE may also receive an AP CSI-RS, possibly after TRS, before or after CSI-RS, but SCell activation is done before sending the AP CSI report, that is, SRS-based CSI acquisition and SCell activation may be faster than CSI-RS-based CSI acquisition and SCell activation. However, in some cases, UL slots/symbols are sparse in time, where SRS-based activation may be slower. Depending on the configuration of the slots/parameters and the time at which the activation command is sent, comparing SRS-based activation with CSI-RS-based activation, one may be faster than the other, which the gNB knows, the gNB can make a selection. In addition, if the gNB needs CQI and/or DL interference information, this information may be provided and used based on activation of the CSI-RS. If the gNB needs DL full MIMO CSI, UL CSI/TA/power control information, and does not need DL interference information, these information may be provided and may be used based on SRS activation; the activation is completed after the SRS is transmitted, but the CSI report can still be transmitted after the activation is completed. The AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) per QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after the time slot n+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. Finally, if the AP TRS is quasi co-located with the P/SP TRS, the P/SP TRS automatically starts after the SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 912.

Fig. 10 is a schematic diagram 1000 of a fourth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 10, in operation 1002, the gNB transmits an AP TRS trigger for deactivating the SCell in slot n. The AP TRS and its trigger information may be configured to the SCell in advance. If multiple AP TRSs are configured for SCell activation and one default AP TRS is configured, the AP TRS trigger may indicate an AP TRS that is different from the default AP TRS. The AP TRS trigger is carried in the PDCCH, which is transmitted on the active serving cell. If the PDCCH decoding with AP TRS trigger is successful, the UE understands that the TRS is on the deactivated SCell, which means that the gNB initiates the SCell activation procedure from slot n. Then, in operation 1004, the gNB may transmit an AP TRS to the UE in a slot n+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. This may be related to UE capabilities, after which the gNB configures the AP TRS trigger offset. This allows the UE sufficient time to prepare for receiving the AP TRS. Although the SCell activation procedure is typically an L2 procedure, the receiving AP TRS trigger, parsing the trigger information, and receiving AP TRS in the SCell activation procedure may be prepared in advance in L1 by the UE, and thus it is not necessary to wait for L2 to be ready. However, the L1 of the UE has to notify the L2, which may take some time, and may be performed in parallel with the AP TRS trigger procedure, that is, the TRS trigger offset may overlap with the L1 to L2 processing, which may not cause any additional delay in the L1 processing of RS transmission/reception/processing. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, if the SCell activation procedure is also configured with a default AP CSI-RS with a trigger offset k_csi-RS, then in operation 1006, the AP CSI-RS may also be sent to the UE in time slot n+k_csi-RS. No triggering of CSI-RS is required, which reduces signaling overhead and delay. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slots n+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in multiple slots, the AP CSI-RS may be transmitted in slots n+t+k_trs+k+k_csi-RS, where k is the number of slots in which the AP TRS transmission is present, and k is specified in the RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the CSI-RS is based on a sufficient number of time domain samples in the TRS. The UE may also transmit an AP SRS in slot n+k SRS if the SCell activation procedure is also configured with a default AP SRS with trigger offset k SRS. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n+k_trs+k_ SRS, which ensures that the SRS is later than the TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. Then, in operation 1008, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 1010) is completed. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after the time slot n+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1012.

Fig. 11 is a schematic diagram 1100 of a fifth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 11, in operation 1102, the gNB transmits an AP CSI-RS trigger for deactivating the SCell in slot n. The AP CSI-RS and its trigger information may be configured to the SCell in advance. If multiple AP CSI-RSs are configured for SCell activation and one default AP CSI-RS is configured, the AP CSI-RS trigger may indicate one AP CSI-RS that is different from the default AP CSI-RS. The AP CSI-RS trigger is carried in the PDCCH, which is transmitted on the active serving cell. If the PDCCH decoding with AP CSI-RS trigger is successful, the UE understands that the CSI-RS is on the deactivated SCell, which means that gNB initiates the SCell activation procedure from time slot n. Then, in operation 1104, the gNB may transmit an AP TRS to the UE in a slot n+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured to the SCell in advance. Triggering of the TRS is not required, which reduces signaling overhead and delay. There may be some L1 to L2 processing but this may be done in parallel with the L1 step and may not create any additional delay in the L1 processing of RS transmit/receive/processing. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, in operation 1106, the AP CSI-RS can be transmitted to the UE in the slot n+k_csi-RS. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slot n+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in multiple slots, the AP CSI-RS may be transmitted in slots n+t+k_trs+k+k_csi-RS, where k is the number of slots in which the AP TRS transmission is present, and k is specified in the RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the CSI-RS is based on a sufficient number of time domain samples in the TRS. If the SCell activation procedure is also configured with a default AP SRS with a trigger offset k_ SRS, the UE may also transmit the AP SRS in slot n+k_ SRS in operation 1108. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n+k_trs+k_ SRS, which ensures that the SRS is later than the TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. Then, in operation 1110, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 1112) is completed. Note that even though SRS is transmitted before CSI-RS, in case SCell activation is initiated by AP CSI-RS trigger, activation is completed only after CSI report is transmitted. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after the time slot n+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1114.

Fig. 12 is a schematic diagram 1200 of a sixth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 12, in operation 1202, the gNB transmits an AP SRS trigger for deactivating the SCell in slot n. The AP SRS and its trigger information may be configured to the SCell in advance. If multiple AP SRS are configured for SCell activation and one default AP SRS is configured, the AP SRS trigger may indicate one AP SRS that is different from the default AP SRS. The AP SRS triggers are carried in the PDCCH, which is transmitted on the active serving cell. If the PDCCH decoding with AP SRS trigger is successful, the UE understands that the SRS is on the deactivated SCell, which means that gNB initiates the SCell activation procedure from slot n. Then, in operation 1204, the gNB may transmit an AP TRS to the UE in a slot n+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured to the SCell in advance. Triggering of the TRS is not required, which reduces signaling overhead and delay. There may be some L1 to L2 processing but this may be done in parallel with the L1 step and may not create any additional delay in the L1 processing of RS transmit/receive/processing. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, in operation 1206, the UE may transmit an AP SRS in slot n+k_ SRS. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n+k_trs+k_ SRS, which ensures that the SRS is later than the TRS. If the TRS is transmitted in multiple slots, the AP SRS may be transmitted in slots n+t+k_trs+k+k_ SRS, where k is the number of slots in which the AP TRS transmission is present, and k is specified in an RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the SRS is based on a sufficient number of time domain samples in the TRS, e.g., for path loss estimation as discussed later. Then, if the SCell activation procedure is further configured with a default AP CSI-RS with trigger offset k_csi-RS, the AP CSI-RS may also be sent to the UE in slot n+k_csi-RS. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slots n+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. The UE may then send a report to the gNB. The slot in which the AP SRS is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 1208) is completed. Note that even though SRS is transmitted after CSI-RS, in case SCell activation is initiated by AP SRS trigger, activation is completed only after SRS is transmitted. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after the time slot n+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1210.

Fig. 13 is a schematic diagram of a seventh exemplary embodiment for SCell activation triggering and activation. As shown in fig. 13, the gNB transmits an AP CSI report trigger for deactivating the SCell in slot n. The AP CSI report and the associated CSI-RS/CSI-IM and trigger information thereof are configured to the SCell in advance. Operations 1302 through 1312 on the time axis in fig. 13 are similar to the AP CSI-RS triggered embodiment of operations 1002 through 1012 in fig. 10, but in operation 1306 in fig. 13, CSI-IM is added to be transmitted in the same time slot as the CSI-RS. Since CSI-RS and CSI-IM are jointly triggered, the trigger is no longer referred to as an AP CSI-RS trigger, but rather as an AP CSI reporting trigger. In an embodiment, the CSI-IM may be in a different time slot than the CSI-RS.

Table 4 shows criteria for deactivating scells as activated in the above embodiment. There are 4 possibilities for each column, with the columns being sub-columns and N/A representing an invalid configuration. Note that the AP temporary RS trigger may or may not indicate a default AP temporary RS trigger.

Table 4: deactivating scells is considered the standard for activation

Examples of the first subcolumn ("yes", "CQI") indicate that if the activation signaling is: "MAC CE", and if a default AP CSI-RS is configured for SCell activation: yes, and if a default AP SRS is configured for SCell activation: yes, SCell is activated when CQI is transmitted.

Other subcolumns can be equally understood.

Some embodiments of CSI reporting associated with SCell activation are described below. In one embodiment, the CSI report includes at least a valid CQI report, which is the same as the legacy design. In one embodiment, the CSI report includes at least a valid L1SINR report, but not necessarily a CQI. The acquisition of the L1SINR is efficient and fast compared to the acquisition of the CQI value, so the activation delay can be shortened. Both CQI reporting and L1SINR reporting must rely on CSI-RS (and one or more CSI-IM resources), as described below. Activation is done when the L1SINR is transmitted. To distinguish between the case of transmitting CQI and transmitting L1SINR, one embodiment is that all Rel-17 enhanced activations require L1SINR but no CQI, or alternatively, for L2 command initiated activations, CQI is to be transmitted, but for L1RS trigger initiated activations, L1SINR is to be transmitted. In another embodiment, the CSI report includes a valid L1RSRP report, but does not necessarily include SINR or CQI. This is particularly useful for FR2 beam based operation. Acquiring the L1RSRP is efficient and fast compared to acquiring the L1SINR value, so the activation delay can be further shortened. The L1RSRP report is dependent on CSI-RS and not on one or more CSI-IM resources. Thus, if the default CSI-IM is not configured or is not signaled in the AP RS trigger, the UE may assume that L1RSRP is to be reported and the activation is completed when L1RSRP is sent. Also, for L2 command initiated activation, CQI is sent, but for L1RS trigger initiated activation, L1RSRP is sent if CSI-IM is not available, and L1SINR is sent if CSI-IM is also available.

In some embodiments, SRS transmission may need to have a suitable TA offset. If the TA is valid for the TAG where the SCell is located, the TA offset may be based on the TAG. If no valid TA is available for the TAG, the initial TA offset can be obtained from another TAG, possibly signaling from the network the offset for the timing difference between the TAGs estimated for the network. In some embodiments, SRS transmission needs to have a suitable transmission power. The pathloss RS of the SRS may be configured as SSB, CSI-RS, or TRS. If the SSB is available and configured as the path loss RS of the SRS, the path loss can be estimated from the SSB. If the CSI-RS can be used as an AP CSI-RS and configured as a path loss RS for SRS, the path loss can be estimated from the AP CSI-RS. The network may configure the path loss (or associated RSRP measurements) based on at least k transmission occasions of the AP CSI-RS, which may be on k OFDM symbols, on k slots, or shorter or longer than k slots depending on its configuration and slot configuration, the AP SRS trigger offset starting from the slot where the kth transmission is located. If the AP TRS is configured as a path loss RS of the SRS, the path loss can be estimated from the AP TRS. The network may configure the path loss (or associated RSRP measurement) based on at least k transmission occasions of the AP TRS, which may be on k OFDM symbols, on k slots, or shorter or longer than k slots depending on its configuration and slot configuration, the AP SRS trigger offset starting from the slot where the kth transmission is located. In one embodiment, the AP TRS is the default pathloss RS for SRS during activation even if the SRS is configured with another pathloss RS; this is because the AP TRS is positively to transmit, while the CSI-RS may be optional, and the AP TRS provides better wideband information for path loss estimation than SSB. Alternatively, information from other carriers may be used to set the SRS transmission power, e.g., the pathloss of SCell1 is obtained from the pathloss of another cell and the offset is signaled to or obtained by the UE. If SCell1 is in a TAG with an active serving cell, the UE may be able to acquire the initial pathloss/RSRP value from that cell through appropriate signaling from the network in addition to the TA information from that cell. For example, if an offset of path loss/RSRP is signaled for a cell, the UE may use the offset of path loss/RSRP for initial SRS power control. As another example, the network signaling has no offset, but only allows the path loss/RSRP to be acquired from the active cell (offset is estimated by the UE, if possible).

In some embodiments, fast SCell activation is achieved through existing L2 signaling and enhanced activation procedures, which may be variants of, or may be combined with, some of the embodiments described above.

-initiating an SCell activation procedure when the UE receives L2 signaling;

the temporary RS is triggered by L2 signaling, wherein the trigger offset starts in the slot according to the required MAC decoding time (typically n+3), or the trigger offset starts in the slot where an ACK to the PDSCH carrying the MAC command is sent. The temporary RS includes at least an AP TRS configured for SCell activation, and includes at least one (or both) of an AP CSI-RS and an AP SRS.

In some embodiments, the fast SCell activation is by L1 signaling or L2 signaling. In either case, the AP TRS is triggered:

in one embodiment, the gNB sends a MAC activation command for SCell activation configured with a default AP TRS and a default AP CSI-RS and/or a default AP SRS. The trigger offset of the AP RS may start in a slot according to the required MAC decoding time (typically n+3); or trigger offset starts in the slot when the UE sends an ACK associated with the MAC activation command.

-the network transmitting an L1 AP TRS trigger for deactivating the SCell, the L1 AP TRS trigger being jointly configured with a default AP CSI-RS and/or a default AP SRS. The triggered AP TRS may or may not be a default AP TRS configured for SCell activation.

The network sends an L1 AP CSI-RS trigger for deactivating the SCell, which L1 AP CSI-RS trigger is jointly configured with a default AP TRS, which triggered AP CSI-RS may be different from the default AP CSI-RS configured for SCell activation. SCell may also be configured with a default SRS and also transmit the default SRS; or alternatively

The network sends an L1 AP SRS trigger for deactivating the SCell, which L1 AP SRS trigger is jointly configured with a default AP TRS, the triggered AP CSI-RS may be different from the default AP CSI-RS configured for SCell activation. The SCell may also be configured with a default CSI-RS and also transmit a default SRS.

In some embodiments where there is an L1 AP trigger that activates the deactivated SCell, to prevent the UE and the network from being out of sync, an ACK to the L1 trigger PDCCH may be sent from the UE if the PDCCH decodes correctly. The ACK may be carried in the PUCCH in the immediately next slot with UL symbols to accommodate the PUCCH. In this case, the trigger offset start time may be a slot of the PUCCH. However, the disadvantage of this embodiment is that the L1 trigger procedure may be prolonged, since the flexible/UL slots under TDD have to be waited for.

In addition to the above-described negotiation of the TRS used as the temporary RS and the aperiodic CSI-RS/SRS/SSB used as the optional temporary RS, the following candidate RSs may be considered.

Periodic CSI-RS deactivating SCell

Essentially, the periodic CSI-RS (or similarly, the SP CSI-RS) acts like LTE CRS, and thus the activation delay can be shortened. Advantages include the occurrence of periodic CSI-RS being fully predictable, which helps reduce PDCCH monitoring and PDCCH overhead, simplifying UE design. Disadvantages include the difficulty in setting the period: if the period is too long, the delay reduction is not significant, but if the period is too short, the overhead and energy consumption are too high. Long-period CSI-RS (also including long-period TRSs) with a period of at least 100 TTIs may be configured to deactivate scells to reduce power consumption. The P/SP TRS configured to deactivate the SCell may also be used as a source RS of the AP TRS during activation. If a plurality of AP TRSs are configured for SCell activation, the AP TRS associated with the P/SP TRS transmitted before the activation begins are assumed to be default AP TRSs and may be transmitted during activation.

Combination of P/SP/AP CSI-RS deactivating SCell

This provides the greatest flexibility/capability for the network, but the complexity may be high.

Comparing the CSI-RS with the TRS, it should be noted that CSI-RS is required for CSI measurement and TRS is required for tracking. Since CSI measurement and reporting is required for almost all SCell activations, CSI-RS is still required even though TRS is used as a temporary RS for activation. Thus, at least one of the AP CSI-RS and the P/SP CSI-RS may be supported for use as a temporary RS, and the combination of the long-period P/SP CSI-RS and the AP CSI-RS may enable an optimal tradeoff between fast activation and reduced UE power consumption.

Periodic SRS to deactivate SCell during activation

SRS may be used to provide DL full MIMO CSI, UL CSI under TDD/FDD, hold UL TA, UL power control, and UL/DL beams in a TDD system. Therefore, SRS is important for the SCell to be activated to reacquire CSI, TA, power control and beam. In case the pathloss RS of SRS is on the active cell, the UE may be able to send SRS on the SCell to be activated without waiting for DL AGC to stabilize. In fact, the SCell may not be able to fully function as a "fully activated" SCell until its UL is also ready, which may be achieved by SRS transmission. In addition, using SRS in the activation may transfer part of the processing from the UE to the network, thereby reducing UE processing complexity. Thus, embodiments in this disclosure support SRS to also be considered for use as a temporary RS.

Periodic/aperiodic RS based on SSS/PSS (e.g., P/AP SSB) during activation

For case 2b (there are active in-band continuous cells, Δtxp 6dB,) And other unknown cell conditions

The UE may or may not be aware of the SCell to be activated. The TRS as a temporary RS may provide the UE with functions such as time/frequency tracking at least during activation, if known. However, if the SCell is unknown, the TRS may not be sufficient, requiring SSS/PSS based RSs. Thus, SSS/PSS-based RSs may be considered to be used as temporary RSs for unknown cells.

To prevent the SCell from becoming unknown to the UE, a periodic RS based on SSS/PSS may be configured for deactivating the SCell. In addition, if it is desired to reduce power consumption, a long period RS of at least 100 TTIs based on the period of SSS/PSS may be configured for deactivating scells. The periodic RS may help to maintain a connection between the UE and the deactivated SCell, which in turn may help to SCell activation. It may be further discussed whether periodic RSs may be included as "temporary RSs", but (only) long-period RSs may be considered for deactivating scells to avoid frequency monitoring of RSs, while avoiding scells becoming unknown.

In some embodiments where deactivating the SCell becomes unknown to the UE, an aperiodic trigger for SSS/PSS-based RSs may be sent. However, due to timing uncertainty, the UE may not know the precise timing of the RS-based SSS/PSS. Thus, in case of activating an unknown SCell, the search time window of SSS/PSS based RSs may be configured or signaled to the UE. For example, if the search time window is x OFDM symbols or x slots or x microseconds, and the trigger offset of the RS is k slots, the UE may perform a search for the RS after receiving the RS trigger, starting after k slots and ending before k slots plus x. Depending on the configuration for the UE, the RS may be repeated multiple times in one slot or multiple times in multiple slots. After transmitting the SSS/PSS based RS k times, where k is the value configured to the UE, the rest of the activation procedure starts, similar to the embodiment described for the known cell.

Accordingly, the AP CSI-RS, the P/SP CSI-RS, the SRS, and the SSS/PSS-based RS may be configured as temporary RSs. Note that the temporary RS is not always required for activation, and whether or not a particular temporary RS is supported/used depends on the network configuration/UE capabilities.

In an embodiment of transmitting the AP CSI-RSs, each AP CSI-RS may also be configured with one or more AP CSI-IM resources, and one or more AP CSI-IM resources are also transmitted when the AP CSI-RS is transmitted. Thus, one or more AP CSI-IM resources are also considered to be a temporary RS or part of a temporary RS resource. In some embodiments, the L1 AP CSI-RS trigger described elsewhere is replaced with an L1 AP CSI trigger. The AP CSI trigger triggers a combination of one or more AP CSI-RSs and one or more AP CSI-IM resources, so that CQI and/or L1 SINR will be reported according to the CSI-RS/CSI-IM. The timing relationship between the AP CSI trigger, the AP CSI-RS, the AP CSI-IM, and the AP CSI report is generally the same as conventional, but in some embodiments, to ensure that the AP CSI-RS/CSI-IM follows the AP TRS, one or more trigger offsets of the AP CSI-RS/CSI-IM begin with the first or last AP TRS slot. Fig. 13 above is a schematic diagram 1300 of a seventh exemplary embodiment for SCell activation triggering and activation.

The TRS has been selected as a temporary RS for SCell activation. The design of the TRS structure and configuration in Rel-15/16 is generally sufficient and can therefore be reused as much as possible in Rel-17. When using a TRS for SCell activation, the network may ensure that a TRS quasi-co-located RS/SSB (i.e., the source RS of the TRS) may be present and active to the UE. For example, if the source RS of the TRS is an SSS/PSS and the UE is not aware of the SCell, the network may ensure that the SSS/PSS is transmitted to the UE prior to transmitting the TRS. With appropriate network implementation/configuration, existing TRS designs may be well used for SCell activation. As previously described, the TRS trigger may also be used as an SCell activation command, which does not seem to require a new design of the trigger command. Some embodiments of AP TRSs were previously provided. In addition, the AP TRS may also be a cross-carrier TRS of the SCell to be activated. In this case, the P/SP/AP TRS is on the active serving cell, which is continuously monitored by the UE. The period may be long (e.g., greater than 100 TTIs) to reduce overhead, the AP TRS is on the active cell according to the MAC command for activation or the L1 RS trigger for activation. The previous example procedure may still be implemented, except that the L1 AP TRS trigger may need to provide additional information to the UE to determine whether it is for cross-carrier SCell activation, which may be accompanied by an additional indication of SCell ID if the AP TRS is also for cross-carrier SCell activation. Advantages of cross-carrier TRSs include that since the P/SP TRSs are monitored by the UE, the number of times that the cross-carrier TRSs are repeated to obtain enough information about tracking and/or path loss estimation for the UE can be reduced, which reduces the delay between the TRSs and CSI-RS/SRS in the next steps. However, AGC information may not be available from the cross carrier TRS. Thus, the following CSI-RS may require more repetition or cross-carrier TRS is mainly used with AP SRS that do not require AGC. That is, an AP SRS trigger is sent to the UE for SCell activation, the SRS is associated to activating an AP TRS on the SCell, and the AP TRS is sent with a TRS trigger offset after the AP SRS trigger without additional repetition, the UE updates the pathloss estimate accordingly, and the AP SRS is sent on the SCell to be activated. At this point, the SCell is considered active.

Some of the embodiments described above may use L1 signaling and/or L2 signaling. In the following embodiments, emphasis is placed on the design and procedure based on L2 signaling.

The generic L2 trigger signaling design and its associated trigger mechanisms may provide this flexibility with low trigger overhead and complexity, as will be described below.

SCell activation trigger (i.e., activation command) configuration and temporary RS configuration are supported. For the configured SCell, the TRS is always configured as a default temporary RS, optionally the AP CSI-RS (and CSI-IM resources), optionally the AP SRS. These RSs may be useful in SCell activation procedures. During SCell activation, at least the TRS, optionally other RSs, may be sent all the time. Thus, there are the following components and possible ways:

-the lowest standardized component of SCell activation:

legacy MAC CE activation commands supporting activation of scells.

The (default) AP TRS is configured with scells and may transmit during SCell activation (i.e., triggered by the same legacy MAC CE used for activation).

-additional components that can be optionally configured and used for SCell activation:

one or more non-default AP TRSs may be additionally configured to the SCell. The new MAC CE may select the AP TRS that triggered during SCell activation (depending on the design, the MAC CE or another MAC CE initiates SCell activation). In one embodiment, a default AP TRS is configured, triggering the default AP TRS does not require a MAC CE payload, and the new MAC CE selects only non-default AP TRSs. In an embodiment, the default AP TRS is not configured, so a new MACCE is always required to select and trigger the AP TRS for activation.

One or more AP CSI-RSs may be configured to the SCell. The MAC CE may select an APCSI-RS to trigger during SCell activation. One CSI-RS may be default, so if SCell activation starts without additional indication, a default AP CSI-RS is also sent.

One or more AP SRS may be configured to SCell. The MAC CE may select an APSRS to trigger during SCell activation. One SRS may be default, so if SCell activation starts without additional indication, default AP SRS is also sent.

Fig. 14A and 14B illustrate a framework for SCell activation.

The SCell supports minimal standardized components and mechanisms for SCell activation, including always supporting legacy MAC activation commands for activating scells, the default AP TRS is always configured with scells, so regardless of how activation starts, the default AP TRS is always sent during SCell activation.

The minimum assembly may be self-contained. Referring to fig. 14A, a minimum component for an L2 signaling based design is shown.

Additional components that may be optionally configured for SCell activation include AP TRS L2 triggers, AP CSI-RS L2 triggers, AP SRS L2 triggers.

If an AP TRS L2 trigger is received, wherein the TRS trigger selected TRS may be different from the default TRS configured for the SCell, the TRS trigger selected TRS is sent instead of the default TRS.

If an AP CSI-RS L2 trigger is received, the selected AP CSI-RS may be transmitted during SCell activation, and a default AP TRS may also be transmitted.

If the AP SRS L2 trigger is received, the selected AP SRS may be transmitted during SCell activation, and a default AP TRS may also be transmitted.

Similarly, if an AP RS supporting an SSS/PSS, the framework described above may also incorporate the AP RS of the SSS/PSS and its associated triggers.

The minimum component and the optional component may be combined. Referring to fig. 14B, minimum and optional components for L2 signaling based design are shown.

Regarding the details of the L2 activation and trigger design, several possibilities may be considered, e.g. one new MAC CE for activation and temporary RS selection/trigger, one or more new MAC CEs for temporary RS selection/trigger only, etc. The following embodiments may be considered.

Example 1: a legacy MAC CE for activation and default temporary RS triggering

No new MAC CE is introduced, but the legacy MAC CE for SCell activation also triggers a default temporary RS (e.g., AP TRS). To avoid ambiguity of legacy behavior without temporary RS triggers and new behavior with temporary RS triggers, RRC configuration and/or side information may be used so that the UE/network has a common understanding of the behavior. In an embodiment, legacy behavior is expected when no default temporary RS is configured to or used for SCell activation, otherwise new behavior is expected. In one embodiment, the RRC field/cell is used to specify which behavior is expected to exist.

Example 2: one legacy MAC CE for activation + one new MAC CE for temporary RS triggering (b bits per SCell)

The new MAC CE may be used to:

TRS trigger; and/or

The CSI-RS trigger; and/or

SRS trigger.

Obviously, there are several embodiments for each RS trigger and joint RS trigger. One or more new MAC CEs for RS triggers are expected to be accompanied only by SCell-activated MAC CEs in the same PDSCH, since no new MAC CEs are needed in inactive scenarios (in these scenarios, L1 DCI triggers are more efficient).

Example 3: a legacy MAC CE for activation and temporary RS triggering

The new joint MAC CE may be just the MAC CE in cascade embodiment 2.

Note that the MAC CE for the temporary RS trigger is different from the MAC CE activation of the temporary RS. The former is a one-time trigger and the latter activates periodic/semi-static transmission of the RS by multiple triggers.

As with the embodiment, in order to trigger the temporary RS, the MAC-CE may provide at least the following information. For M scells configured by the UE, 0, 1 or more temporary RS information may be provided/configured for each configured SCell. Suppose that N (M.gtoreq.N) SCells are currently deactivated. Of the N deactivated scells, it is assumed that Y (N. Gtoreq.Y) scells are to be activated. The MAC CE may then be sent to activate Y scells. The same or different MAC CEs may indicate that the temporary RS is to be triggered on X out of Y (y≡x) scells to be activated, respectively, while no temporary RS is to be triggered on other Y-X scells to be activated.

Parameters for temporary RS triggering that may be included in the MAC CE are analyzed as follows.

Whether or not to trigger a temporary RS or which resources are to be used for the triggered temporary RS

These two problems are related. If n different temporary RSs are to be configured to the SCell, then a training (log (n+1)) bit is needed in the MAC CE to indicate which to trigger or indicate no trigger. However, if 0 temporary RSs are configured, the temporary RSs (i.e., the legacy activation procedure) are not triggered. Furthermore, if only 1 temporary RS is configured, or a default temporary RS is to be configured, this field is optional in the MAC CE if the temporary RS-based activation procedure in new Rel-17 is to be used, or if the activation procedure in legacy and new Rel-17 is to be used, a bit may be used to indicate whether or not to trigger a temporary RS. The default temporary RS may be the first temporary RS in the configuration list.

Trigger time offset

The candidate values for the one or more trigger offsets may be RRC configurable. If one or more c values are configured, then a rising (log (c)) number of bits may be required in the MAC CE. If c=1 or a configurable default value, then 0 bits are required (i.e., this field may be optional). An upper limit for c needs to be determined, for example, up to 4 or 8 offset values.

-QCL source

The QCL source may be configured to each temporary RS through RRC and may not need to be present in the MAC CE. However, if desired, multiple TCI states may be configured and one selected by the MAC CE.

The following description analyzes MAC CE design options/alternatives.

Although in general some parameters may be included in the MAC CE for temporary RS triggers, none of these parameters need to be always present in the MAC CE. In at least some cases, all parameters may be configured by RRC, and the default values may be triggered by legacy MAC CEs without requiring any new MAC CE design. Therefore, in this case, when only the legacy MAC CE is transmitted, if the default temporary RS and parameters are configured, it may indicate that the default temporary RS and its default parameters are triggered. If the default temporary RS is not configured, the temporary RS is not triggered.

If a new MAC CE is supported that triggers only temporary RSs, but it is not in the PDSCH carrying the legacy SCell activated MAC CE, the new MAC CE will not be sent. The temporary RS trigger may be used only for SCell activation, so the UE would not expect the presence of the temporary RS trigger MAC CE without SCell activation MAC CE.

New MAC CE designs can balance between high flexibility (too many parameters) and high overhead. For this, the RRC configuration may limit temporary RS parameters (resources, time offsets, etc.) in the MAC CE to several combinations, one of which is selected by the MAC CE, which will be described in detail below.

The activation and triggering procedure using L2 signaling, time axis and UE behavior may be enhanced. There may be many situations, not all of which have to be explicitly handled in the RAN1 standard (they will be explicitly handled in the RAN4 TS 38.133). RAN1 provides an overall time axis for RAN2 TS 38.321 activation timing, with activation latency requirements referencing RAN4 TS 38.133.

Fig. 15 shows an exemplary triggering procedure and time axis (e.g., for FR1 known cell at 15kHz SCS);

the first P/SP CQI 1506 may be optional; the first AP CQI 1504 may be optional and may be triggered by a new MAC CE 1502 (or legacy DCI in another embodiment).

The new procedure greatly reduces the activation delay for the following reasons: (1) One or more temporary RSs (AP TRSs) may be immediately available after slot n+k; (2) AP CSI measurement and reporting may immediately follow time I (triggered by MAC CE 1502); (3) The AP SRS may immediately follow slot n+k (triggered by MAC CE 1502 without waiting for AGC in the case of in-band CA, etc.).

The details of some of the components are as follows.

MAC CE trigger time: ending in time slot n

This is the slot at the end of the PDSCH carrying one or more MAC CEs for activation and temporary RS selection/triggering. Note that there is DCI reception before PDSCH reception.

HARQ, initial MAC processing and RF latency: ending in time slot n+k

Time slot n+k is still defined as one time slot after the required MAC decoding and processing time, which is the same as time slot n+k (i.e. instant n+k in current TS 38.213 ₁ +3N _{slot,subframe,μ} +1) are identical. The initial MAC processing refers to MAC CE decoding and other MAC related operations, rather than operations specified in clause 5.9 of TS 38.321 for CSI/PDCCH/SRS/PUCCH/etc.

At this time, the temporary RS is not transmitted.

AGC after slot n+k, gap, time/frequency tracking, fine timing, cell search, etc

The temporary RS needs to be transmitted after the slot n+k. RAN1 has earlier protocol "during SCell activation, UE measures triggered temporary RS in a time not earlier than slot m: FFS is performed on the time axis value m that may need to be negotiated with RAN 4. Thus, m should be equal to n+k (i.e., m=n+k).

For FR1 known cells, AGC is not needed if the measurement period does not exceed 160ms, otherwise 1 AP TRS burst is needed. After setting the AGC, a minimum gap of 2 slots is also required.

Then, time/frequency tracking based on another AP TRS burst may be required.

In some cases fine timing may be required, cell search for unknown cells is required, and some uncertainty (for MAC, RRC, etc.) is also required, as defined in TS 38.133.

Some details of these operations are not specified in RAN 1. The role of RAN1 here may be to ensure one or more AP TRS bursts using the desired design provided. RAN1 may inform RAN2/RAN4 about X AP TRS bursts, where there are some gaps, X may be 1, 2 or more, and the TRS bursts may be for the same BWP, but not for different BWP. Details of MAC signaling and details of timing may be left to RAN2/RAN4 processing.

The gap between bursts may be defined as the time duration between the starting time slots of a burst, or the time duration of the last time slot of a first burst up to the starting time slot of a second burst. If a burst lasts 2 slots, these two definitions may create a time difference of 2 slots. Unless otherwise specified, embodiments of the present disclosure assume the latter definition.

Time offset of first AP TRS

In order for the UE to receive the AP TRS, the TRS should not be transmitted until the initial MAC processing and RF delay are completed. Thus, the earliest possible timing may be on or immediately after time slot n+k (e.g., time slot n+k+1). However, it may be useful to allow some flexibility here, e.g., the UE may need some time to prepare the AP TRS, which may be related to UE capabilities and power saving considerations. This is somewhat similar to the L1 AP TRS trigger offset, the larger the offset, the more time the UE will respond. Thus, the AP TRS can be in time slot n+k+k _TRS Wherein k is _TRS Is an extra slot offset of the AP TRS (also referred to as K0 or apeeriodictriggeringoffset of the CSI-RS/TRS) and may be configured by RRC signaling or specified by MAC signaling. k (k) _TRS It may also be a fixed value specified by the standard or may take one of several values specified by the standard, the selection being made by RRC signaling or MAC signaling. Due to the need for fast activation, the offset may be set to the minimum scheduling offset of the CSI-RS (e.g., the minimum value of minscheduling offsetk0-Values or the first value of minscheduling offsetk 0-Values). This value may be used as a default AP TRS offset without signaling to the UE in the MAC CE. The earliest slot in which the UE receives the triggered temporary RS may be slot n+k.

k _TRS The slot offset may also be modified to consider only "available slots" or "acceptable slots" or "effective slots", e.g., by TDD-UL-DL-ConfigCommon or TDD-UL-DL-ConfigDedimated MIB/SIB/RRC are configured as downlink slots instead of those flexible slots. These slots may also be limited to DL slots that the AP TRS may accommodate. In addition, these slots may be limited to DL slots that are no earlier than slot n+k+minisculeschdulingoffsetk 0.

In more detail, the current mechanism for TRS trigger offset can be largely re-used. In the current mechanism, the maximum possible trigger slot offset of the CSI-RS is 24 or 31, and the minscheduling offsetk0-Values may take one or two Values, maximum 16, where each minimum K0 parameter represents one or more minimum applicable Values in the TDRA table of PDSCH and one or more a-CSI RS trigger offsets. When multiple minimum K0 parameters are configured, one of the parameters is indicated in the trigger DCI. When the minimum K0 parameter is not configured, either a default offset specified by the standard specification is used, or a 0 offset is used. At this time, for the AP TRP trigger by the MAC CE, 0, 1 or more minimum K0 parameters may be configured to the configured TRS, and the MAC CE may select one, which may be K as described above _TRS . If only "available slots" are calculated in determining the AP TRS offset, it is sufficient to support only a few candidate offset values, even only one offset value, corresponding to the first DL slot that can accommodate the AP TRS and is no earlier than slot n+k+minisculeschdulingoffsetk 0. In some cases, the minimumschedule offsetk0 may be 0, at which time a temporary RS may be sent in slot n+k to obtain the minimum activation delay.

SRS, CSI, PDCCH, PUCCH, etc

According to TS 38.133, operations associated with SRS, CSI, PDCCH, PUCCH, etc., may begin during the last phase of activation on or after time slot n+k. Note that CSI reporting related operations may start as early as possible from time slot n+k.

Other temporary RSs such as AP CSI-RS/SRS may be transmitted, even more AP TRSs may be transmitted, and AP CSI reporting with effective CQI may be performed.

Time offset for AP CSI-RS

Similar to the time offset design of the AP TRS described above, the AP CSI-RS can be in slot n+k+k _CSI-RS Is transmitted in the middle of the transmission,wherein k is _CSI-RS Is the extra slot offset of the AP TRS, and the AP SRS is in the slot n+k+k _SRS Wherein k is _SRS Is the extra slot offset of the AP SRS. These offsets may be configured by RRC signaling or may be specified by MAC signaling. These offsets may also be fixed values specified by the standard or may take one of several values specified by the standard, the selection being made by RRC signaling or MAC signaling.

In general, the offset of the CSI-RS may be greater than the offset of the TRS and ensure that the CSI-RS is transmitted only after any one or more preconditions TRS bursts are completed. For example, if a 2-slot AGC with TRS is required, then another TRS burst of 2 slots and 2 slots is required for tracking, then the CSI-RS offset may be after the TRS burst used for tracking, e.g., k _CSI-RS ≥k _TRS +6 slots. In general, since the network controls the activation process and the temporary RS transmission under various conditions (e.g., the conditions specified in TS 38.133), the network can ensure that the offset of the signal can meet the appropriate signal transmission/reception requirements.

The CSI-RS trigger offset mechanism may be similar to the TRS trigger offset mechanism described above. To achieve greater flexibility, the configured AP CSI-RS may be allowed to have an offset that is different from the AP TRS trigger offset. In general, different TRS/CSI-RS resources in RRC may configure different offsets, and different TRS/CSI-RS resources in MAC CE may indicate different/separate offsets.

Time offset of AP SRS

The offset of the SRS may generally be greater than the offset of the TRS, but the SRS may be transmitted as early as the TRS if a precondition is already available/valid for the SRS. For example, for SRS that use "anticonswitching" or "codebook" within FR1, the SRS may be transmitted without waiting for AGC or tracking to complete if path loss RS and other preconditions (e.g., timing advance) for the SRS are available/valid; note that RSRP/pathloss estimation is still available/valid for SRS, especially if long-period SSB/CSI-RS is still transmitted during deactivation or pathloss RS can be configured on different serving cells that are activated; the TA may be valid if the SCell is in a TAG that includes an active serving cell. However, for "non codebook", a prerequisite is that the associated CSI-RS (on the same carrier as SRS) to be transmitted, so the SRS with "non codebook" can only follow the associated CSI-RS. Also, the network can guarantee the correct time sequence with sufficient flexibility in selecting offsets.

The AP SRS trigger offset may be based on one or more configured slot offset values, one of which is to be selected by the MAC CE. However, since SRS can only be transmitted on UL slots under TDD or UL symbols in flexible slots, trigger slot offset can only be applied to UL slots and flexible slots including enough OFDM symbols to accommodate AP SRS transmission.

CSI reporting

CSI reporting based on AP/P/SP CSI-RS and associated CSI-IM may occur after one or more additional delays in CSI-RS transmission and UE processing. The time relationship between CSI-RS transmission and CSI reporting defined in the current standard can be reused.

The CSI reporting may be on a different carrier or on an active carrier. For P/SP CSI reporting, the current standardization process may be followed. For AP CSI reporting triggered by MAC CE, the reporting parameters may be configured mainly by RRC, the rest (if any) by MAC CE. One simple design is to add a CSI request field in the MAC CE, which is similar in design to that in DCI.

BWP

By default, when SCell is activated, UL BWP and DL BWP in activation are based on firstactiondownlinkbwp-Id and firstactionuplinkbwp-Id. Thus, the configured TRS and its transmissions, etc. may be on the first activated BWP. If the gNB needs to activate a different DL BWP or UL BWP, it may also be indicated in the MAC CE, and the signals and operations may be for the indicated one or more BWPs. Alternatively, since the configured TRS is associated with a BWP ID, when the MAC CE selects a specific TRS, the BWP associated with the TRS is selected as the activated BWP.

Regarding embodiments in which measurement is performed within the BWP bandwidth of the BWP indicated by the first actiondownlinkbwp-Id if the UE measures the temporary RS triggered by the MAC-CE during SCell activation, these embodiments do not specify that the temporary RS must be on the BWP with the first actiondownlinkbwp-Id; it is only said that the measurement of the temporary RS (e.g., TRS) is within the bandwidth of the BWP with the firstActiveDownlinkBWP-Id. Thus, it may happen that, for example, BWP with first actiondownlinkbwp-Id is BWP 1, but TRS is configured on BWP 2, and UE performs TRS measurement only on the overlapping bandwidths of BWP 1 and BWP 2. This may create some of the following problems.

The TRS may not be a useful TRS if BWP 1 and BWP 2 do not overlap.

If BWP 1 and BWP 2 overlap, but the overlap bandwidth is small, the measurement result may not be reliable.

If BWP 1 and BWP 2 overlap but have different system parameters, it may not be clear how the UE performs the measurements on the TRS or a BWP handover is required. A BWP handover may be required during activation at least before CSI-RS for CSI measurement and reporting. In an embodiment, the TRS-based operation may be performed before the BWP handover, and the CSI-RS-based operation for CSI measurement and reporting, etc., may be performed after the BWP handover. It may be desirable to signal the BWP to switch to and it may be desirable to signal the time offset of the BWP switch.

This embodiment may add restrictions, for example, only the TRS configured for BWP with firstactiondownlinkbwp-Id may be configured as a temporary RS. Alternatively, the embodiment techniques may allow for activation into other BWP. Flexible activation into other BWP is also advantageous, e.g. the network may use different BWP for different traffic demands or spectrum utilization considerations. Then, if the gNB wishes to use BWP 2, but BWP 1 and BWP 2 may have different bandwidths and system parameters, activating only to BWP 1 and measuring/reporting the CSI of BWP 1 may not help much; worse yet, BWP may be on the orthogonal frequency in the carrier.

For purposes of summarizing the embodiments with the additional limitations described above:

all TRSs as temporary RSs can only be configured on BWP with firstactiondownlinkbwp-Id;

the SCell always activates into the BWP with the firstActiveDownlinkBWP-Id.

Thus, the following points may need to be supported: for an SCell to be activated, if any BWP ID is configured as part of the temporary RS configuration, the value of the expected BWP ID may be equal to the firstactivationbwp-ID.

For SCell activation, embodiments support:

in time slot n+k (according to current TS 38.213) +k _TRS And thereafter, transmitting X AP TRS bursts with gaps between bursts, the value of X comprising at least 1 and 2; the additional value may come from RAN4;

○k _TRS may correspond to a first DL slot that may accommodate the AP TRS and not earlier than slot n+k+minisculeschdulingoffsetk 0.

-in time slot n+k+k _SRS If the configuration or triggering is carried out through the MAC CE, the AP SRS is sent;

-in time slot n+k+k _CSI-RS And after a plurality of AP TRS bursts, if the AP TRS bursts are configured or triggered through the MAC CE, transmitting the AP CSI-RS/CSI-IM, and reporting the effective CQI according to the existing reporting mechanism.

k _TRS 、k _SRS And k _CSI-RS The value of (c) may be determined by the network and provided to the UE through RRC signaling or MAC signaling.

Fig. 16 shows an embodiment of SCell activation using several L2 signaling designs. Fig. 16 is a schematic diagram of a first exemplary embodiment for SCell activation triggering and activation. As shown in fig. 16, the gNB sends a MAC activation command for a deactivated SCell configured with a default AP TRS and optionally a default AP CSI-RS and/or AP SRS. This initiates an SCell activation procedure. The MAC activation command may use an existing design in which the information of the TRS/CSI-RS/SRS is not provided, but the associated default TRS/CSI-RS/SRS configured through RRC signaling is automatically triggered. More than one AP TRS (or CSI-RS/SRS) may be configured to or for the SCell activation procedure, but one of them is configured as a default value. The default value may be configured explicitly or implicitly by a BWP configuration, e.g. several AP TRSs are associated with several BWP of the SCell, respectively, one BWP is signaled as the default value for activation, and then the default AP TRS associated with the default BWP is triggered. This reduces MAC/DCI signaling overhead, avoiding the design of new MAC activation commands. Alternatively, the MAC activation command may be a use enhancement design, for example, further comprising one or more fields to trigger one or more or one of the BWP in the TRS/CSI-RS/SRS. This requires more MAC overhead but provides more flexibility for the network. For example, if two or more TRSs are associated with the SCell, the MAC command may activate/select one (e.g., one TRS is associated to BWP, by selecting TRSs or selecting BWP, the associated BWP/TRSs are also activated/selected) or a plurality thereof. Then, after the AP TRS, the associated RS (CSI-RS/SRS) also performs transmission/reception/processing according to network configuration/activation. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Then, valid DL CSI is reported from the UE to the gNB, which typically includes at least valid CQI values. Some embodiments of this aspect are discussed further below. After that, SCell activation is completed, and SCell is activated.

Fig. 16 also shows that the gNB sends an L2AP TRS trigger associated with deactivating the SCell. The UE understands that this initiates the SCell activation procedure. The AP TRS associated with the trigger may or may not be a default AP TRS, which provides the network with greater flexibility to select an AP TRS to send or a BWP to activate. For example, a default TRS (TRS 1) may be associated with a default BWP1, but the L2AP TRS trigger is for TRS2 and BWP2, when the UE understands that SCell activation is to put BWP2 in an active state. Then, after the AP TRS, the associated RS (CSI-RS/SRS) also performs transmission/reception/processing according to network configuration/activation. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Then, valid DL CSI is reported from the UE to the gNB, which typically includes at least valid CQI values. Some embodiments of this aspect are discussed further below. After that, SCell activation is completed, and SCell is activated.

Fig. 16 also shows that the gNB transmits an L2AP CSI-RS trigger associated with deactivating the SCell. The UE understands that this initiates the SCell activation procedure. The AP CSI-RS associated with the trigger may or may not be a default AP CSI-RS. The AP CSI-RS is associated with some default TRS, optionally with default SRS and BWP, which provides the network with more flexibility to select the AP CSI-RS/TRS/SRS to be transmitted or the BWP to be activated. For example, a default TRS (TRS 1) may be associated with default BWP1 and default CSI-RS1, but the L2AP CSI-RS trigger is for CSI-RS2, CSI-RS2 being associated to BWP2 and TRS2, at which point the UE understands that SCell activation is to put BWP2 in an active state, with TRS2/CSI-RS2 being expected to be present. Then, after the AP TRS2, the AP CSI-RS2 is transmitted and received. Optionally, the AP SRS is transmitted according to configuration/activation, optionally, the UE reports valid DL CSI to the gNB, which generally includes at least a valid CQI value. The CSI-RS, SRS and TRS are associated with the same BWP, one quasi co-located with the other. For example, the CSI-RS may be quasi co-located with the TRS in accordance with QCL type a, with the SRS using the TRS and/or CSI-RS for its path loss RS. Some embodiments of this aspect are discussed further below. After that, SCell activation is completed, and SCell is activated.

Fig. 16 also shows that the gNB transmits an L2AP SRS trigger associated with deactivating the SCell. The UE understands that this initiates the SCell activation procedure. The AP SRS associated with the trigger may or may not be a default AP SRS. The AP SRS is associated with some default TRS, optionally with default CSI-RS and BWP, which provides the network with more flexibility to select the AP CSI-RS/TRS/SRS to be transmitted or the BWP to be activated. For example, a default TRS (TRS 1) may be associated with default BWP1 and default SRS1, but the L2AP SRS trigger is for SRS2, SRS2 being associated to BWP2 and TRS2, at which point the UE understands that SCell activation is to put BWP2 in an active state, expects to receive TRS2 and transmit SRS2. Then, after the AP TRS2, the AP SRS2 is transmitted. Optionally, the AP CSI-RS is sent according to configuration/activation, optionally, the UE reports valid DL CSI to the gNB, which generally includes at least a valid CQI value. Some embodiments of this aspect are discussed further below. After that, SCell activation is completed, and SCell is activated.

Fig. 17 shows an embodiment of activation and triggering. Fig. 17 is a schematic diagram of a second exemplary embodiment for SCell activation triggering and activation. As shown in fig. 17, in operation 1702, the gNB transmits a MAC activation command for deactivating the SCell in slot n. The MAC CE is carried in the PDSCH, which is transmitted on the active serving cell. In operation 1704, the UE needs to transmit ACK/NACK for PDSCH with MAC CE. If the PDSCH with the MAC CE is successfully decoded, an ACK can be sent, which initiates an SCell activation process; otherwise, a NACK may be transmitted, the gNB may have to transmit another PDSCH with MAC CE, and the SCell activation procedure may begin in the slot in which the ACK is transmitted. T slots may be required from receiving PDSCH with MAC CE to ACK. In some cases, k=3 ms (or equivalent number of slots) (i.e., the time required for the UE to decode MAC signaling). The value t may also be other UE capability related value, which may be before the UE sends an ACK. The value t may also include other delays required for the UE to process the MAC CE and perform operations in L1. In either case, the network and the UE need to have a common reference timing, one embodiment of which is a slot of the ACK, and another embodiment of which is a slot after the ACK, in order for the UE L1 to be ready, in order to transmit/receive the remaining signals without other signaling. Then, in operation 1706, the gNB may transmit an AP TRS to the UE in a slot n+k+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. This may be related to UE capabilities, after which the gNB configures the AP TRS trigger offset. This allows the UE sufficient time to prepare for receiving the AP TRS. The AP TRS is configured in advance for SCell activation. Triggering of the TRS is not required, which reduces signaling overhead and delay. In case of configuring a plurality of AP TRSs for SCell activation, configuring one of them as default, transmitting the default AP TRS, and not transmitting the other AP TRSs; some embodiments were described previously. The MAC CE may also be enhanced to include a trigger for one of the AP TRSs to be selected. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. At least one of the default AP CSI-RS and the default AP SRS may be configured for SCell activation. Then, if the SCell activation procedure is also configured with a default AP CSI-RS with a trigger offset k_csi-RS, then in operation 1708 the AP CSI-RS may also be sent to the UE in time slot n+k+k_csi-RS. The default AP CSI-RS may be identified based on the default AP CSI-RS being a BWP associated with the triggered AP TRS. No triggering of CSI-RS is required, which reduces signaling overhead and delay. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slots n+t+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in a plurality of slots, the AP CSI-RS may be transmitted in slots n + k + k _ TRS + k _ TRS _ length + k _ CSI-RS, where k _ TRS _ length is the number of slots in which the AP TRS transmission is present, k is specified in the RRC configuration or standard, e.g., k_trs_length=2, 4, etc., which ensures that the CSI-RS is based on a sufficient number of time domain samples in the TRS. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. Then, in operation 1710, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 1712) is completed. Note that if the default AP SRS is also configured/identified for SCell activation procedure, the UE may send an AP SRS, possibly after TRS, before or after CSI-RS. No triggering of SRS is required, which reduces signaling overhead and delay. Embodiments of AP SRS transmission may be further described. In addition, the AP TRSs are generally not independent RSs (i.e., they rely on the P/SP TRSs), and the AP TRSs and the P/SP TRSs are mutually quasi co-located, in particular, the AP TRSs may rely on the P/SP TRSs. However, in some cases, the AP TRS cannot rely on the P/SP TRS on the SCell for deactivation of the SCell. There are several embodiments. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after time slot n+k+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1714.

Fig. 18 illustrates an embodiment of SCell activation and RS triggering. Fig. 18 is a schematic diagram of a third exemplary embodiment for SCell activation triggering and activation. As shown in fig. 18, in operation 1802, the gNB transmits a MAC activation command for deactivating the SCell in slot n. The MAC CE is carried in the PDSCH, which is transmitted on the active serving cell. In operation 1804, the UE needs to transmit ACK/NACK for PDSCH with MAC CE. If the PDSCH with the MAC CE is successfully decoded, an ACK can be sent, which initiates an SCell activation process; otherwise, a NACK may be transmitted, the gNB may have to transmit another PDSCH with MAC CE, and the SCell activation procedure may begin in the slot in which the ACK is transmitted. T slots may be required from receiving PDSCH with MAC CE to ACK. The value t may also include other delays required for the UE to process the MAC CE and perform operations in L1. Then, in operation 1806, the gNB may transmit an AP TRS to the UE in a slot n+k+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured in advance for SCell activation. No trigger on the TRS is required, which reduces signaling overhead and delay. In case of configuring a plurality of AP TRSs for SCell activation, configuring one of them as default, transmitting the default AP TRS, and not transmitting the other AP TRSs; some embodiments were described previously. The MAC CE may also be enhanced to include a trigger for one of the AP TRSs to be selected. The AP TRS may repeat within one slot or between different slots. Then, if the SCell activation procedure is also configured with a default AP SRS with a trigger offset k_ SRS, the UE may also transmit the AP SRS in slot n+k+k_ SRS in operation 1808. The default AP SRS may be identified based on the default AP SRS being a BWP associated with the triggered AP TRS. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n + k + k _ TRS + k _ SRS, this ensures that SRS is later than TRS. If the TRS is transmitted in multiple slots, the AP SRS may be transmitted in slots n + k + k _ TRS + k _ TRS _ length + k _ SRS, where k is the number of slots in which the AP TRS transmission is present, k_trs_length is specified in the RRC configuration or standard, e.g., k_trs_length=2, 4, etc., which ensures that SRS is based on enough time domain samples in the TRS, e.g., for path loss estimation discussed later. However, in either case, the time gap between receiving the TRS and transmitting the SRS may be shorter than the time gap between receiving the TRS and receiving the AP CSI-RS, because the SRS may be transmitted without waiting for AGC settling (which is typically required for receiving the CSI-RS). The UE is ready to transmit SRS as long as it acquires tracking from the AP TRS. Thus, in one embodiment, the AP SRS slot is n+k+k_trs+t_ SRS, where t_ SRS < k_ SRS is a value specified by the network. For example, t_ SRS may be 1 slot (that is, if the frame structure allows, the SRS may be transmitted in a slot immediately after the TRS (e.g., the slot is an UL slot or a flexible slot including UL symbols)). According to the SRS, gNB can acquire partial DL MIMO CSI of the FDD system, full DL MIMO CSI of the TDD system, full UL MIMO CSI under FDD/TDD and UL power control/timing advance information. If the default AP CSI-RS is not configured for SCell activation, the slot in which the SRS is transmitted may be considered the time when SCell activation is completed (that is, SCell is activated in operation 1810). Note that if the default AP CSI-RS is also configured/identified for the SCell activation procedure, the UE may also receive an AP CSI-RS, possibly after TRS, before or after CSI-RS, but SCell activation is done before sending the AP CSI report, that is, SRS-based CSI acquisition and SCell activation may be faster than CSI-RS-based CSI acquisition and SCell activation. However, in some cases, UL slots/symbols are sparse in time, where SRS-based activation may be slower. Depending on the configuration of the slots/parameters and the time at which the activation command is sent, comparing SRS-based activation with CSI-RS-based activation, one may be faster than the other, which the gNB knows, the gNB can make a selection. In addition, if the gNB needs CQI and/or DL interference information, this information may be provided and used based on activation of the CSI-RS. If the gNB needs DL full MIMO CSI, UL CSI/TA/power control information, and does not need DL interference information, these information may be provided and may be used based on SRS activation; the activation is completed after the SRS is transmitted, but the CSI report can still be transmitted after the activation is completed. The AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) per QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat in consecutive time slots on or after the time slot n+k_trs so that the UE may obtain sufficient tracking information from the AP TRS. Finally, if the AP TRS is quasi co-located with the P/SP TRS, the P/SP TRS automatically starts after the SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1812.

Fig. 19 illustrates an embodiment of activation and RS triggering. Fig. 19 is a schematic diagram of a fourth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 19, in operation 1902, the gNB transmits an L1 activation and AP TRS trigger for deactivating the SCell in slot n. The AP TRS and its trigger information may be configured to the SCell in advance. If multiple AP TRSs are configured for SCell activation and one default AP TRS is configured, the AP TRS trigger may indicate an AP TRS that is different from the default AP TRS. The AP TRS trigger is carried in the MAC CE in the PDSCH, which is transmitted on the active serving cell in slot n. Then, in operation 1904, the gNB may transmit an AP TRS to the UE in a slot n+k+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. This may be related to UE capabilities, after which the gNB configures the AP TRS trigger offset. This allows the UE sufficient time to prepare for receiving the AP TRS. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, if the SCell activation procedure is also configured with a default AP CSI-RS with a trigger offset k_csi-RS, then in operation 1906 the AP CSI-RS may also be sent to the UE in time slot n++ k+k_csi-RS. No triggering of CSI-RS is required, which reduces signaling overhead and delay. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Alternatively, the AP CSI-RS is transmitted in time slot n+k_trs+k_csi-RS, which ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in a plurality of slots, the AP CSI-RS may be transmitted in slots n + k + k _ TRS + k _ TRS _ length + k _ CSI-RS, where k _ TRS _ length is the number of slots in which the AP TRS transmission is present, k_trs_length is specified in the RRC configuration or standard, e.g., k=2, 4, etc., which ensures that the CSI-RS is based on a sufficient number of time domain samples in the TRS. If the SCell activation procedure is also configured with a default AP SRS with a trigger offset k_ SRS, the UE may also transmit the AP SRS in slot n+k+k_ SRS in operation 1908. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable to transmit the SRS after the TRS so that tracking implemented from the TRS can be applied to SRS transmission, so the network can generally ensure that k_ SRS > k_trs. Alternatively, the AP SRS is transmitted in slot n+k_trs+k_ SRS, which ensures that the SRS is later than the TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. Then, in operation 1910, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as the time when SCell activation (that is, SCell activation in operation 1912) is completed. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat (with gaps in between if needed) in consecutive slots on or after slot n+k+k_trs so that the UE can obtain enough tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 1914.

Fig. 20 is a schematic diagram of a fifth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 20, in operation 2002, the gNB transmits an L2 activation and AP CSI-RS trigger for deactivating the SCell in slot n. The AP CSI-RS and its trigger information may be configured to the SCell in advance. If multiple AP CSI-RS are configured for SCell activation and one default AP CSI-RS is configured, the AP CSI-RS trigger may indicate one AP CSI-RS that is different from the default AP CSI-RS. The AP CSI-RS trigger is carried in PDSCH, which is transmitted on the active serving cell in slot n. Then, in operation 2004, the gNB may send an AP TRS to the UE in a slot n+k+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured to the SCell in advance. Triggering of the TRS is not required, which reduces signaling overhead and delay. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, in operation 2006, the AP CSI-RS can be transmitted to the UE in time slots n+k+k_csi-RS. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Another option is that of providing a plurality of channels, the AP CSI-RS is transmitted in slot n + k + k _ TRS + k _ CSI-RS, this ensures that the CSI-RS is later than the TRS. If the TRS is transmitted in a plurality of slots, the AP CSI-RS may be transmitted in slots n + k + k _ TRS + k _ TRS _ length + k _ CSI-RS, where k _ TRS _ length is the number of slots in which the AP TRS transmission is present, k_trs_length is specified in the RRC configuration or standard, e.g., k_trs_length=2, 4, etc., which ensures that CSI-RS is based on a sufficient number of time domain samples in the TRS. The UE may also transmit an AP SRS in slot n+k+k_ SRS if the SCell activation procedure is also configured with a default AP SRS with trigger offset k_ SRS. No triggering of SRS is required, which reduces signaling overhead and delay. It may be preferable in some embodiments to send the SRS after the TRS so that tracking implemented from the TRS may be applied to SRS transmissions, so the network may generally ensure that k SRS > k TRS. Alternatively, the AP SRS is transmitted in slot n + k + k _ TRS + k _ SRS, this ensures that SRS is later than TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. Then, in operation 2008, the UE may send a report to the gNB. The time slot in which the report including the valid CQI is transmitted may be regarded as a time when SCell activation (that is, SCell activation in operation 2010) is completed. Note that even though SRS is transmitted before CSI-RS, in case SCell activation is initiated by AP CSI-RS trigger, activation is completed only after CSI report is transmitted. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat (with gaps in between if needed) in consecutive slots on or after slot n+k+k_trs so that the UE can obtain enough tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, which automatically starts after SCell activation is completed if the P/SP TRS is configured with the AP TRS in operation 2012.

Fig. 21 is a schematic diagram of a sixth exemplary embodiment for SCell activation triggering and activation. As shown in fig. 21, in operation 2102, the gNB transmits an L2 activation and AP SRS trigger for deactivating the SCell in slot n. The AP SRS and its trigger information are configured to the SCell in advance. If multiple AP SRS are configured for SCell activation and one default AP SRS is configured, the AP SRS trigger may indicate one AP SRS that is different from the default AP SRS. The AP SRS triggers are carried in MAC CEs in PDSCH, which is transmitted on the active serving cell in slot n. Then, in operation 2104, the gNB may transmit an AP TRS to the UE in a slot n+k+k_trs, where k_trs is a trigger offset associated with the UE receiving the AP TRS in terms of the number of slots. The AP TRS is configured to the SCell in advance. Explicit triggering of the TRS is not required, which reduces signaling overhead and delay. Based on the received AP TRS, the UE may perform AGC settling, time/frequency tracking, etc. The AP TRS may repeat within one slot or between different slots. Then, in operation 2106, the UE may transmit an AP SRS in slot n+k+k_ SRS. It may be preferable in some embodiments to send the SRS after the TRS so that tracking implemented from the TRS may be applied to SRS transmissions, so the network may generally ensure that k SRS > k TRS. Alternatively, the AP SRS is transmitted in slot n + k + k _ TRS + k _ SRS, this ensures that SRS is later than TRS. If the TRS is transmitted in a plurality of slots, the AP SRS may be transmitted in slots n + k + k _ TRS + k _ TRS _ length + k _ SRS, where k _ TRS _ length is the number of slots in which the AP TRS transmission is present, k_trs_length is specified in the RRC configuration or standard, e.g., k_trs_length=2, 4, etc., which ensures that SRS is based on a sufficient number of time domain samples in the TRS, e.g., for path loss estimation discussed later. Then, if the SCell activation procedure is also configured with a default AP CSI-RS with trigger offset k_csi-RS, the AP CSI-RS may also be sent to the UE in time slot n+k+k_csi-RS. It may be preferable to receive the CSI-RS after the TRS so that AGC/tracking implemented from the TRS may be applied to CSI-RS reception and processing, so the network may generally ensure that k_csi-RS > k_trs. Another option is that of providing a plurality of channels, the AP CSI-RS is transmitted in slot n + k + k _ TRS + k _ CSI-RS, this ensures that the CSI-RS is later than the TRS. If both the CSI-RS and the SRS are configured, the CSI-RS may be before the SRS or after the SRS, depending on the parameters. From the CSI-RS, the UE may generate an AP CSI report, which may include at least a valid CQI. The UE may then send a report to the gNB. The slot in which the AP SRS is transmitted may be regarded as a time when SCell activation is completed (that is, SCell is activated in operation 2108). Note that even though SRS is transmitted after CSI-RS, in case SCell activation is initiated by AP SRS trigger, activation is completed only after SRS is transmitted. One embodiment is that the AP TRS relies on a cross-carrier signal, e.g., the AP TRS is quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS (within FR 2) in accordance with QCL type a and QCL type D. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another embodiment, if the cross carrier SSB or P/SP TRS is not configured or transmitted because the carrier is also deactivated, the AP TRS may repeat (with gaps in between if needed) in consecutive slots on or after slot n+k_trs so that the UE can obtain enough tracking information from the AP TRS. The AP TRS is still quasi co-located with the P/SP TRS, and in operation 2110, if the P/SP TRS is configured together with the AP TRS, the P/SP TRS automatically starts after SCell activation is completed.

Fig. 22A is a schematic diagram of a seventh exemplary embodiment for SCell activation triggering and activation. As shown in fig. 22A, in operation 2202, the gNB transmits an L2 activation and AP CSI report trigger for deactivating the SCell in slot n. The AP CSI report and the associated CSI-RS/CSI-IM and trigger information thereof are configured to the SCell in advance. Operations 2202 through 2212 of the time axis in fig. 22 are similar to the embodiments of L2 activation and AP CSI-RS triggering of operations 2002 through 2212 in fig. 20, but in operation 2206 in fig. 22, CSI-IM is added to transmit in the same time slot as CSI-RS. Since CSI-RS and CSI-IM are jointly triggered, the trigger is no longer referred to as an AP CSI-RS trigger, but as an AP CSI reporting trigger. In an embodiment, the CSI-IM may be in a different time slot than the CSI-RS.

The AP TRS is generally not a stand-alone RS (i.e., it relies on a P/SP TRS). Specifically, the AP TRS is quasi co-located with the P/SP TRS. When the AP TRS is a temporary RS for facilitating activation, the dependency on deactivation of the SCell is checked. In TS 38.214, the TRSs are designated as "periodic CSI-RS resources in one set and aperiodic CSI-RS resources in the second set, where the aperiodic CSI-RS and periodic CSI-RS resources have the same bandwidth (have the same RB location), and where applicable, the aperiodic CSI-RS are configured with qcl-Type set to 'Type-a' and 'Type' with the periodic CSI-RS resources. That is, existing standards do not allow the use of AP TRSs without associated P/SP TRSs. In addition, RSs quasi co-located with the TRSs depend on both the P/SP TRSs and the AP TRSs, and not on the AP TRSs alone. The QCL relationship involving AP/P/SP TRS is shown in the following figures as the "legacy" section. In some embodiments, the AP TRS is the same RS as its QCL source, P/SP TRS, or multiple transmission occasions/resources of the same TRS; that is, for the NZP-CSI-RS-resource set configured with the higher layer parameter trs-Info, the UE should assume that antenna ports configured in the NZP-CSI-RS-resource set with the same port index of the NZP CSI-RS resource may be the same.

Fig. 22B illustrates QCL relationships for FR1 provided by some embodiments. QCL type D may be included in FR 2. In an illustrative example, the SP TRS is not included, but the P TRS in fig. 22B may be replaced with the SP TRS.

The present disclosure checks the dependency on deactivating scells when AP TRS is a temporary RS for facilitating activation. The QCL relationship is shown in the "WA-based" section of fig. 22B. Two differences are shown compared to the "legacy" and "WA-based" parts, but there is one possible problem:

-difference 1: the temporary RS based on the AP TRS is no longer quasi co-located with any RS according to type a. The UE must acquire delay spread and doppler spread from the AP TRS instead of from another RS (e.g., P/SP TRS).

-difference 2: without an associated P/SP TRS, the CSI-RS of the first CQI report that completes SCell activation must be quasi co-located with the temporary RS based on the AP TRS.

Possible problems: after SCell activation, how DMRS of data and CSI-RS of CSI are associated with temporary RS based on AP TRS without associated P/SP TRS.

First, even if DMRS of data and CSI-RS of CSI are after SCell activation, SCell activation procedure design should not negatively affect operation after activation. For example, if additional time is required after a "fast" activation without an associated P/SP TRS using a temporary RS based on the AP TRS, the UE may not be able to receive high-speed data for a significant period of time after the activation, which may not be for the purpose of the "fast" activation. Efficient SCell activation allows the UE to perform high speed communications on the SCell earlier than conventional procedures, rather than just sending an earlier indication that activation is complete.

In one option, the activated QCL source RS (P/SP TRS) may be different (i.e., not quasi co-located) from the AP TRS that is the temporary RS. The disadvantage of this option is that the UE must acquire the P/SP TRS after activation and then receive the data, which creates additional delay. In addition, to acquire the P/SP TRS, since the P/SP TRS is quasi co-located with the SSB, the UE still has to acquire the SSB periodically but with possibly not short period first, and then acquire the P/SP TRS again. Efficient data transfer is then performed, but with longer delays.

In another option, an AP TRS that is a temporary RS is used as a QCL source RS for the DMRS/CSI-RS after activation, the AP TRS being bi-directionally co-sited with the P/SP TRS. After transmitting the P/SP TRS, the AP/P/SP TRS acts together as a QCL source for the DMRS/CSI-RS. This may require additional specification support, e.g., DMRS/CSI-RS is quasi-co-located with AP TRSs without associated P/SP TRSs, which are quasi-co-located with AP TRSs by type a (i.e., AP TRSs and P/SP TRSs are bi-directionally quasi-co-located with each other by type a). An example of this option is shown in fig. 22C.

More details of this embodiment are provided below.

QCL source of temp RS: in case of a known SCell, the SSB before deactivation is a QCL source of type C of temporary AP TRS.

-RS using temp RS as QCL source: the temporary AP TRS acts as a QCL source for other RSs following it until the first P/SP TRS burst is transmitted. The first P/SP TRS burst following the temporary AP TRS also temporarily uses the temporary AP TRS as a QCL source. After the first P/SP TRS burst, the first P/SP TRS becomes the QCL source for the DMRS and CSI-RS.

After these temporary RS-based activated temporary operations (marked by the reception of the first P-TRS burst), the UE resumes legacy operation. As in the conventional system, the P/SP TRS following the first P/SP TRS burst is quasi co-located with the SSB, but does not have to wait for the SSB to transmit because it is the same RS as the AP TRS in the temporary RS.

Note that the TRSs in the diagram are the same TRSs (except for P/SP/AP time domain behavior in terms of RS RE locations, bandwidth, etc. in the slot). Beam switching and other delays are expected to occur if another TRS is used, e.g., with a different beam. In general, for two different TRSs, each TRS is quasi-co-located with SSB by type C (in FR2, also quasi-co-located by type D), but no QCL relationship is defined between the two different TRSs. Therefore, even after the UE acquires TRS1 during activation using the TRS 1-based temporary RS, the UE must acquire SSB first and then acquire TRS2. That is, the attributes obtained from TRS 1-based activation may not be helpful to the receiving TRS2. In other words, the existing QCL defines not only the QCL relationship between the source RS and the target RS, but also the timing order in which they are received at least during activation, that is, the UE must first receive/process the source RS and then receive/process the target RS.

In either case, therefore, it may be desirable that the AP TRS and the activated P/SP TRS in the temporary RS are the same TRS, so that the activated P/SP TRS may use the temporary RS, since no QCL relationship is defined between the different TRSs. If another TRS is to be used, the TRS can only be used after the UE acquires the SSB.

Thus, the working assumption may require the UE to perform some backward incompatible operations.

Alternatively, embodiments of the present disclosure may align the P/SP TRS with an existing design, as shown in the "proposal" section in fig. 22B.

First, for the known SCell, time/frequency synchronization still remains sufficiently high accuracy, and channel properties obtained from SSBs and/or associated P/SP TRSs remain valid for AP TRSs. Then the QCL of the AP TRS has no problem. This has been demonstrated for FR1/FR2 by RAN 4. For FR1, if the SCell measurement period is known to be no greater than 160ms, then 1 burst of 2 slots and 4 AP CSI-RS resources as TRSs are sufficient for time/frequency tracking, and if the SCell measurement period is known to be greater than 160ms, then 2 AP CSI-RS resource bursts as TRSs are sufficient for AGC and time/frequency tracking. For FR2, 1 burst of 2-slot AP CSI-RS resources is sufficient as TRS for fine timing tracking. Thus, in case of a known SCell, the SSB and/or associated P/SP TRS of the SCell to be activated is the QCL source of the temporary AP TRS. RAN1 may now focus these cases on the temporary RS design and QCL discussion.

If the above assumption is not true in some cases, other schemes need to be provided for QCL of AP TRS. One solution is that the AP TRS may rely on a cross-carrier signal as previously described, e.g., the AP TRS may be quasi co-located with a cross-carrier SSB or a cross-carrier P/SP TRS, and QCL types may be discussed further. The cross-carrier SSB or P/SP TRS may be on an active carrier, which is typically an in-band carrier, and may be configured/received for the UE before the activation process begins. In another approach, if cross-carrier SSB or P/SP TRS is not available, the AP TRS may transmit in consecutive time slots according to the design of the associated P/SP TRS so that the UE may obtain enough tracking information from the TRS.

After transmitting the AP TRS during activation, the AP TRS may serve as a QCL source for one or more other RSs thereafter, including P/SP TRS, P/SP/AP CSI-RS, P/SP/AP SRS. However, after transmitting the P/SP TRS, the P/SP TRS or the P/SP and AP TRS may collectively serve as a QCL source for one or more RSs thereafter.

For an unknown SCell, it is likely that an SSB (or SSS/PSS based RS) would need to be sent upon triggering on the periodic SSB, and then the P/SP/AP TRS could be sent. The activation delay may be long and thus it may be desirable to avoid situations where the SCell becomes unknown through a long period RS.

Thus, the P/SP TRS associated with the temporary AP TRS may be a QCL source of type a of the temporary AP TRS, given the SCell. The temporary AP TRS and quasi-co-sited P/SP TRS may be used as QCL sources for other RSs following it, including the P/SP TRS sent after the AP TRS, which serves as QCL sources for other RSs following the P/SP TRS. The exemplary options presented are summarized below.

QCL source of temporary RS: the pre-deactivation P/SP TRS associated with the temporary AP TRS may be a QCL source of type a of the temporary AP TRS, given the SCell. The AP TRS and quasi-co-sited P/SP TRS may be a joint QCL source of temporary RSs. This may also apply to other embodiments herein. Based on this understanding, the gNB can trigger the AP TRS burst before the SCell is deactivated to help the UE to best maintain the attributes obtained from the TRS, thereby facilitating temporary RS-based activation.

-RS using temporary RS as QCL source: the temporary AP TRS and quasi-co-located P/SP TRS may serve (jointly) as QCL sources for other RSs following it, including the P/SP TRS sent after the temporary AP TRS, and the AP/P/SP TRS may serve (jointly) as QCL sources for other RSs following the P/SP TRS. In other words, TRSs of the same parameters may be co-located with each other and one occasion may use the previous occasion or occasions as the QCL source.

-restriction in activation based on temporary RS: for SCell quick activation in R17, the P/SP TRS associated with one of the temporary RSs may need to be sent/activated before and after deactivation. Otherwise, it is necessary to provide a more complex design. That is, the pre-deactivation P/SP TRS, temporary AP TRS, and post-activation P/SP/AP TRS may be the same TRS to achieve rapid activation. This may be a hypothesis/expectation of the UE.

The MAC CE trigger can only select a temporary RS with a P/SP TRS that was sent/activated prior to deactivation. If only m such P/SP TRSs are sent/activated, the UE may expect one of the associated temporary RSs to trigger a MAC CE trigger through the temporary RS. In some embodiments, the SP TRSs are not supported, so all configured TRSs are sent periodically, which may be temporary RSs; in other words, in some embodiments, the temporary RS configuration can only be selected from those configured TRSs.

In the above embodiment, the P/SP TRSs used after activation may want to be the same as the AP TRSs used in the temporary RS (except for the P/SP/AP time domain behavior in terms of RS RE position, bandwidth, etc. in the slot), even though they may be given different names, e.g., CSI-RS for tracking and temporary RS. Otherwise, the P/SP TRS cannot directly use the time/frequency tracking and other attributes obtained from the temporary RS, since the P/SP TRS may need to be quasi co-located with the SSB. If the P/SP TRS is the same as the AP TRS, the P/SP TRS may be received by the UE and used as a QCL source for the RS thereafter. In an embodiment, when the temporary RS based on the AP TRS is triggered by the MAC CE, the associated SP TRS having the same TRS configuration may also be activated and become an activated state. The P/SP TRS may or may not be used by the UE for SCell activation; further embodiments of handling the UE behavior of the P/SP TRS associated with the AP TRS-based temporary RS are provided below. In an embodiment, the AP TRS used in the temporary RS may be configured periodically as well for the SCell, or (if supported) may be configured semi-static for the SCell and may only be triggered as temporary RS, provided that the SP TRS activation MAC CE is sent during SCell activation, e.g. in the same time slot as the SCell activation MAC CE. Otherwise, the TRS may not be allowed to configure or trigger as part of the temporary RS. In an embodiment, if the AP TRS used in the temporary RS may be a TRS that is not configured to be periodic for the SCell but is configured to be semi-static, the SP TRS is activated (no SP TRS activates the MAC CE) when the temporary RS based on the AP TRS is triggered. That is, the UE may receive the P/SP TRS associated with the temporary RS based on the AP TRS, and the tracking attribute obtained by the UE using the temporary RS during SCell activation may be directly used by the UE for activated RS/data transmission/reception without waiting for SSB. In an embodiment, for temporary RS-based SCell activation, the UE may not want to receive data whose DMRS is quasi co-located with the TRS (as opposed to in the temporary RS) until the UE receives one burst of at least one SSB and TRS (source of DMRS). The UE may not report CSI from the CSI-RS quasi co-located with the TRS (as opposed to the temporary RS) until the UE receives one burst of at least one SSB and TRS (source of CSI-RS).

As described above, the RS transmissions (including the number of one or more TRS bursts and the number of one or more SSB bursts) may be different in different situations where there are different requirements for AGC/cell detection/tracking. Table 5 below provides an overview.

Table 5: summary of 2-slot TRS burst number and SSB number of transmissions (unless otherwise specified, the numbers in the tables are for 2-slot TRS burst)

Note that in line 6, when AGC is required, 1 TRS burst or m1 SSB bursts may be transmitted, then m2 SSB bursts are transmitted, then 1 TRS burst is transmitted. When cell detection is required, the cell detection typically requires SSB (and thus m2 SSB bursts in the table), and the AGC before cell detection may be based on TRS or SSB.

Table 5 shows that at least one or more 2-slot TRS bursts can be supported, and m1 and/or m2 SSB bursts can be supported, where m1=1 or 2 or more, and m2=1 or 2 or more. SSBs may be periodic or aperiodic (triggered by MAC CE). The order may be (m 1 SSBs, m2 SSBs), or (m 1 SSBs, m2 SSBs), which is a scheme in Rel-15/16, or (m 1 SSBs, m2 SSBs), but typically the shortest delay is (m 1 SSBs, m2 SSBs). There may be a gap (e.g., 2 slots) between any 2 consecutive SSB bursts.

The case (i.e., row) in the table may be assigned an ID, and the ID may be selected by the MAC CE to reduce MAC signaling overhead. In each row, the RS is sent in a left to right order, e.g., for row 3 with 1 TRS burst for AGC and 1 TRS burst for tracking, 2 TRS bursts are sent in that order with a gap (e.g., 2 slots or 2 ms) in between. For row 6, where 1 TRS burst is used for AGC, m2 SSB bursts are used for cell detection, and 1 TRS burst is used for tracking, the RSs are sent in the order (1 TRS burst, gap, m2 SSB bursts with gap in between, gap, 1 TRS burst). The network may signal only row 6 (e.g., ID 6) in the MAC CE to trigger the RS transmission. In one embodiment, a portion of a row, e.g., (m 1 SSBs, gap, m2 SSBs) is assigned an ID, and one or more IDs need to be signaled to the UE to complete the activation process.

Table 6 below provides an overview of the case with a complete RAN4 input.

Table 6: summary of 2-slot TRS burst number and SSB number of transmissions (unless otherwise specified, the numbers in the tables are for 2-slot TRS burst)

Table 6 shows that some cases (e.g., case 1b and case 2 a) can be supported using the same temporary RS design. As described above, the trigger offset may typically be set to a minimum scheduling offset K0 (except for some embodiments of processing P/SP TRS and SSB shown below), and the gap between bursts should be set according to a minimum required value decided by the RAN4 (except for some embodiments of processing P/SP TRS and SSB shown below) to speed up the activation speed. Furthermore, for FR1, typically one TRS configuration on BWP with ID first active downlink BWP-ID may be sufficient, and for FR2 one TRS configuration per beam may be sufficient. Thus, for FR1 SCell, it may be necessary to support the 3 temporary RS configurations listed in the table to cover all cases, while for FR2 one temporary RS configuration per beam is sufficient. Each row in the table may form a temporary RS configuration and may be associated with an ID for triggering purposes. Note that if the temporary RS reuse is an NZP CSI-RS resource set cell that may have been configured with an apersidiotriggeringoffset, then the configured offset may be ignored for any burst in the temporary RS transmission, and the UE follows the offset/gap indicated in the MAC.

Thus, an embodiment may provide a temporary RS configuration to support all cases where RAN4 enters full coverage, and each configuration is assigned a unique ID.

Most embodiments in the present disclosure describe the acquisition of AGC/tracking functions according to a temporary RS, a temporary RS configuration, a temporary RS resource configuration, an AP TRS-based temporary RS configuration, or a temporary AP TRS transmission, etc. In some embodiments, the AP TRS used in the temporary RS may be replaced with the following signal/RS resource sets: (1) A P TRS burst, wherein the P TRS burst may be the same RS as the AP TRS; (2) SSBs, which may be either conventional periodic SSBs or new aperiodic SSBs, the TRSs may be quasi-co-located with the SSBs. The purpose of these embodiments is that during the new activation procedure, possibly only the P TRS burst and/or SSB is sent, which the gNB/UE can use. If the pstrs burst and/or SSB is sent (e.g., for another UE), but not used by the UE, one or more transmissions may be wasted, with the expected generation of additional delay. Furthermore, SSBs can be transmitted anyway, if they are transmitted, UEs following the legacy standard have to monitor the SSBs and need to define the UE behavior for activation to receive temporary RSs and SSBs.

If the psrs or SSB is quite far from the expected activation start time, the activation should be based entirely on the temporary RS. If the SSB is close to the expected activation start time and only one burst of SSB is needed for activation, the activation should be based entirely on SSB (i.e. using a conventional activation procedure), even though it may result in a slightly longer activation time compared to using a temporary RS. If the psrs or SSB is close to the expected activation start time and the activation requires multiple bursts of psrs/SSB/temporary RS, the activation may be based on psrs or SSB in addition to temporary RS.

In one embodiment, if the temporary RS includes multiple bursts, one of the bursts may be replaced by a psrs or SSB if the burst starts in the same time slot as the psrs or SSB. When this occurs, the UE may not expect a temporary RS burst to start from the slot, but may expect a psrs or SSB and receive/measure the psrs or SSB. QCL relationships involving the temporary RS may need to be changed accordingly, e.g., if an SSB is received, the RSs following the temporary RS may only be quasi co-located with the SSB as per type C. In one embodiment, if the temporary RS includes multiple bursts, the first burst (or a burst other than the last burst) may be replaced by the SSB if the burst starts in the same time slot as the SSB; this is to allow the UE to acquire SSB before AP TRS, since SSB is the QCL source of TRS. In an embodiment, if a gap of x slots is configured between a temporary RS burst and a next temporary RS burst, the next temporary RS burst may be transmitted one slot in advance if the temporary RS burst of 2 slots is replaced by SSB of 1 slot. In other words, the x slot gap now begins after the SSB slot ends. This may even shorten the activation process, but may be seen as an exception to the added complexity, and thus may not support the present embodiment in some systems. The psrs or SSB seems unlikely to align with the temporary RS burst, but the gNB knows the transmission timing of the psrs or SSB in advance and has the ability to signal the temporary RS offset and gap, which can be achieved by the appropriate MAC signaling parameters if the psrs or SSB is not far from the activation start time.

In one embodiment, the UE may not desire to transmit any psrs or SSB during the temporary RS-based activation. In another embodiment, during the temporary RS-based activation, the UE does not monitor or use any psrs or SSB for activation, except for operations related to CSI reporting. In another embodiment, during activation based on multiple temporary RS bursts, the UE does not expect any psrs or SSBs that are not aligned with the temporary RS bursts. In another embodiment, during the temporary RS-based activation, the UE does not monitor or activate using any psrs or SSB that is not aligned with the temporary RS burst, except for operations related to CSI reporting. In another embodiment, during activation based on multiple temporary RS bursts, the UE does not expect any SSBs that are not aligned with the first temporary RS burst. In another embodiment, during the temporary RS-based activation, the UE does not monitor or use any SSBs that are not aligned with the first temporary RS burst for activation, except for operations related to CSI reporting. The aim of these embodiments is to reduce the UE implementation complexity so that the UE does not need to handle two different activation procedures simultaneously. Note that even if the psrs or SSBs are not used during activation, the UE may still monitor the psrs or SSBs for purposes not directly related to activation. Note, however, that the UE may always use the P/SP TRS for CSI reporting related operations during activation, e.g., the P/SP TRS may be used as QCL source for CSI-RS for CSI reporting, but not for AGC/tracking intended on temporary RS. In one embodiment, the UE behavior is not standardized, the UE may decide on its own whether to use P/SP TRS or SSB to accelerate the activation speed, but may specify minimum performance requirements under the assumption that no P/SP TRS or SSB is present. Thus, a capable UE may use P/SP TRS or SSB to speed up activation, but does not require any UE to do so.

In one embodiment, if the SSB follows slot n+k and is at least x slots earlier than the first burst of the temporary RS, the UE may monitor and use the SSB for temporary RS-based activation, where x corresponds to the minimum gap between bursts. In one embodiment, if the psrs is after slot n+k and is at least x slots apart from any burst of the temporary RS, the UE monitors and uses the psrs for temporary RS-based activation, where x corresponds to the minimum gap between bursts. Essentially, in these embodiments, the gNB/UE uses the P TRS or SSB to replace the potential temporary RS burst, the gNB indicating one less burst to the UE.

In the above-described embodiment involving the pstrs, the pstrs may be changed to the SP TRS, and the SP TRS may become active when the MAC CE triggers the temporary RS based on the AP TRS without an additional MAC semi-static TRS activation command, or only when the MAC semi-static TRS activation command of the SP TRS is transmitted.

In one embodiment, the UE and the gNB may not be able to understand the unknown/known SCell status in the same way. Whether or not there is a different understanding, there are at least the following cases: (1) If the UE has communicated with the SCell within the last x ms (e.g., x=400), then the SCell is known and the UE/gNB may have the same understanding; (2) If the UE has not communicated with the SCell within the last y ms (e.g., y=2000), the SCell is unknown and the UE/gNB may have the same understanding. For these specific cases, the above-described embodiments may be used. For the case in between (e.g., the UE has communicated with the SCell between x ms and y ms, and no longer thereafter), in an embodiment, a somewhat conservative design may be provided to ensure that fast activation is always valid (e.g., by sending one AP SSB as part of the temporary RS). Thus, the gNB may assume that the SCell is known only if the deactivation time is shorter than x ms and/or the measurement period is shorter than y ms or the last communication with the SCell is within x ms, since no SCell is unknown in these cases. When the condition is not met, the gNB may assume that the SCell is unknown, and in an embodiment, the gNB signals a row ID (or equivalently an RS and its timing) if the SCell is assumed to be unknown from the UE's perspective, and sends the RS accordingly. In some embodiments, the UE may follow signaling and should not assume that the RS has been sent based on the UE's understanding of the SCell status. In an embodiment, the gNB may trigger the UE to report the known/unknown SCell status so that activation may be updated based on the correct status, which may shorten the activation process.

For rows with active in-band cells or active in-band continuous cells, cross-carrier QCL, etc. may be introduced. Examples are provided below.

Fig. 23 illustrates an example of an existing QCL configuration and a new cross-carrier QCL relationship for carrier aggregation provided by some embodiments. In the existing manner, the UE aggregates multiple carriers and configures serving cells, e.g., cell 1 and cell 2, on the carriers. Then, QCL relationships are configured for each cell, e.g., for cell 1, TRS1 and SSB 1 are quasi-co-located according to QCL type C (in FR2, also quasi-co-located according to type D), CSI-RS1 and/or DMRS1 are quasi-co-located according to QCL type a with TRS1, and so on. No cross-carrier QCL relationship is configured. In some embodiments, a cross-carrier QCL relationship is configured/assumed. The cross-carrier QCL relationship may be used for the RS across cells/carriers.

In an embodiment, the RS with cross-carrier QCL relationship may be SSB. That is, SSB 1 in cell 1 is quasi co-located with SSB 2 in cell 2, and/or vice versa. The UE may not need to use one SSB to receive another SSB according to a cross-carrier QCL relationship because SSBs are generally self-sufficient, but the QCL relationship may inform the UE that a cross-carrier QCL may be assumed. In this example, TRS1 is quasi-co-located by type C with SSB 1 (in FR2, also quasi-co-located by type D), TRS2 is quasi-co-located by type C with SSB 2 (in FR2, also quasi-co-located by type D), there is an additional cross-carrier QCL between SSBs, then during SCell activation, TRS1 of cell 1 to be activated can be assumed to be quasi-co-located by type C with SSB 2 of active cell 2 (in FR2, also quasi-co-located by type D), and vice versa.

In an embodiment, the RS for which a cross-carrier QCL relationship exists may be a TRS. That is, TRS1 in cell 1 is quasi co-located with TRS2 in cell 2, and/or vice versa. When SSB may be the QCL source of TRSs, the UE may not need to use one TRS to receive another TRS according to a cross-carrier QCL relationship, but the QCL relationship may inform the UE that a cross-carrier QCL may be assumed. In this example, TRS1 is quasi-co-located with SSB 1 and TRS2 by type C (in FR2, also quasi-co-located by type D), TRS2 is quasi-co-located with SSB2 and TRS1 by type C (in FR2, also quasi-co-located by type D), then during SCell activation, TRS1 of cell 1 to be activated may assume quasi-co-located by type C with SSB2 and/or TRS2 of cell 2 to be activated (in FR2, also quasi-co-located by type D), and vice versa.

In general, if RS1-1 (e.g., SSB 1) in cell 1 is quasi-co-located with RS2-1 (e.g., SSB 2) in cell 2, RS1-2 (e.g., TRS 1) in cell 1 is quasi-co-located with RS1-1 by type X, RS2-2 (e.g., TRS 2) in cell 2 is quasi-co-located with RS2-1 by type X, then the UE may assume that RS1-2 and RS2-1 in cell 1 are quasi-co-located by type X to activate cell 1, and the UE may assume that RS2-2 and RS1-1 in cell 2 are quasi-co-located by type X to activate cell 2.

The cross-carrier QCL between RS1-1 (e.g., SSB 1) in cell 1 and RS2-1 (e.g., SSB 2) in cell 2 may be of an existing QCL type, e.g., type C, type c+d, etc., but may be interpreted as bi-directional (i.e., the source and destination in the RS pair may be flipped). This may be defined as a new QCL type. For example, the SSB of cell 1 may be configured to be quasi co-located with the SSB of cell 2. Since this relationship between cell 1 and cell 2 is reciprocal, the UE may assume the opposite direction without configuring the opposite direction. In an embodiment, the cross-carrier bi-directional QCL may be a new QCL type.

The cross-carrier QCL between RS1-1 (e.g., SSB 1) in cell 1 and RS2-1 (e.g., SSB 2) in cell 2 may be configured explicitly by RRC signaling or implicitly under some conditions (i.e., assuming). For example, cell 1 and cell 2 may be serving cells in an in-band CA, cell 1 and cell 2 may be serving cells in a continuous carrier in an in-band continuous CA, cell 1 and cell 2 may have shared PA/RF (e.g., in-band, in the same TAG, same system parameters, aligned slot boundaries/numbers), cell 1 and cell 2 may be within a serving cell set configured with one or more common attributes, and so on. This may require UE reporting (e.g., band-combined UE capability reporting, CA capability, etc., reflecting whether the UE uses the same PA/RF/filter for the carriers) and gNB information about its operation (e.g., whether the gNB uses the same PA/RF/filter for the carriers, power differences between the carriers, etc.).

When configuring or assuming a cross-carrier QCL between RS1-1 (e.g., SSB 1) in cell 1 and RS2-1 (e.g., SSB 2) in cell 2, other signals quasi-co-located with them on the respective carriers may inherit the implicit QCL relationship without requiring the QCL relationship to be configured one by one. For example, TRS2 may have an implicit cross-carrier relationship with SSB 1 and/or TRS1 in fig. L, resulting from a cross-carrier QCL between SSB 1 and SSB 2 and a configured co-carrier QCL.

During initial SCell addition or SCell reconfiguration by RRC reconfiguration message, the UE may be used to detect TRS when the SCell is activated. In one embodiment, the SCell sends a TRS transmission and the UE receives a trigger through the MAC CE. A default TRS may be configured for the UE. In addition, several alternative TRSs may also be preconfigured. As described above, triggering the SCell to send TRS and the UE to receive is to activate the SCell.

As an example, activating the default TRS activates MAC CE triggers only through the existing SCell. Figure M shows an existing SCell activation/deactivation MAC CE:

fig. 24 illustrates an exemplary SCell activation/deactivation MAC CE for TRS activation provided by some embodiments. The MAC CE may include the following fields.

-C _i : if the MAC entity is configured with scells with SCellIndex i as specified in TS 38.331, this field indicates the activation/deactivation status of scells with SCellIndex i, otherwise the MAC entity should ignore C _i A field. C (C) _i A field set to 1 indicates that SCell with SCellIndex i should be activated. C (C) _i A field set to 0 indicates that SCell with SCellIndex i should be deactivated.

-R: the reserved bit is set to 0.

In this example, when C _i When set to '1', the default TRS of the SCell with index I is also activated. If the UE passes one or more TRS configurations, if the UE receives only SCell activated MAC CEs (without other TRS information), the UE performs TRS detection using a default TRS configuration.

Another example is to design a new SCell activation MAC CE. In the new MAC CE, fig. 25 shows an alternative TRS selection bit in addition to SCell activation/deactivation bits.

Fig. 25 illustrates a new SCell TRS activation MAC CE including TRS selection information provided by some embodiments. In the MAC CE, the definition of Ci and R is the same as in the existing SCell activation/deactivation MAC CE. Ti1, ti2 are select bits of the alternative TRS (if configured). A new Logical Channel ID (LCID) may be assigned to the new MAC CE.

-Ti1, ti2: if Ci is set to '1' to activate the SCell with index 1, (Ti 1, ti 2) is validated and is the index of the alternative TRS selected to be activated when SCell i is activated.

In this example, the UE procedure is: when C _i When set to '1'. If the UE is configured with one or more TRSs, the UE performs TRS detection using the configuration of TRSs indexed (Ti 1, ti 2). In an embodiment, ti1 may be a temporary RS resource configuration for a first temporary RS burst of an SCell with index i, and Ti2 may be a temporary RS resource configuration for a second temporary RS burst of the SCell. If only one burst is transmitted, the corresponding Tij field may be set to 0. In another embodiment, a temporary RS resource configuration for a first temporary RS burst and a temporary RS resource configuration for a second temporary RS burstThe combination of temporary RS resource configurations may be indexed and form one field in the MAC CE. In another embodiment, the time offset of the first burst relative to slot n+k may be included as a separate field in the MAC CE for each SCell. In another embodiment, the time offset of the first burst relative to slot n+k may be included as a separate field in the MAC CE for all scells. In another embodiment, the time slots of the first burst and the second burst may be included as separate fields in the MAC CE for each SCell. In another embodiment, the time slots of the first burst and the second burst are included as separate fields for all scells in the MAC CE. In another embodiment, for each SCell, parameters including time offset, first burst RS resource configuration, gap, and second burst RS resource configuration constitute one temporary RS resource configuration for each SCell, assigned a unique ID, which may be included in a field of the MAC CE of the SCell. The bit width of each SCell may be the same (e.g., Z bits for SCell). However, there may be a different number of temporary RS parameters per SCell to be signaled, so the equal number of bits for all scells may not be the most efficient design. In an embodiment, the bit width of the temporary trigger field for each SCell may be determined by the total number of parameter combinations (e.g., M) for that field, which may be ceil (log 2 (M)). If the SCell does not configure the temporary RS, the SCell does not use any field. In one embodiment, bursts may be configured using an NZP CSI-RS resource set ID, and the resource set associated with the ID must be configured with trs-info. That is, it must be a TRS. Such a TRS may be further configured with a TRS ID or a CSI-RS for tracking ID as a candidate for a temporary RS (2 slots with 4 samples) on BWP with a first activebwp-ID, because other CSI-RS cannot be configured as one or more bursts of temporary RS for AGC/tracking/etc. In one embodiment, the first burst and the second burst (if configured) may always use the same TRS, so the second burst may not need to be explicitly configured as a field in RRC signaling, but may be implicitly acquired based on the number of bursts or a valid gap value, etc. If the burst number field is configured with only 1 burst The gap field may be optional, ignored by the UE, or filled with an invalid value. If the gap field is supported and the configuration of invalid values is allowed, the burst count field may not be needed; thus, if the gap field is configured with a valid value, e.g., 2ms, the UE may assume 2 bursts with a gap of 2ms in between. However, if the gap field is configured with an invalid value, the UE may assume that 1 burst is configured.

To reduce some signaling overhead, a new MAC CE may be designed to include only the TRSs that choose to activate the SCell.

Fig. 26 illustrates an alternative new MAC CE provided by some embodiments that includes only TRS selection bits corresponding to one or more scells to be activated. In the example shown in fig. 26, scells with indices 1, 3, 6 are activated by C1, C3, and C6, and the corresponding TRS selection bits are carried in the MAC CE of the next octet: (T11, T12), (T31, T32) and (T61, T62) in the same order as C1, C3, C6. Upon receiving the MAC CE, the UE decodes only the SCell activation bits set to '1' (activated) TRS selection bits and decodes the TRS selection bits of the corresponding groups in the same order as the asserted SCell activation bits. The above examples illustrate the principle of one or more MAC CEs for SCell/TRS activation without loss of generality. The extended MAC CE for more SCell activations may be designed according to the same principle. The TRS activation selection may also be separated into TRS activation/selection MAC CEs. This example also applies to the embodiment designed for fig. 25.

Further alternatives for temporary RS triggering are provided below, one based on a bitmap per SCell, and another is to reuse the L1 AP-TRS trigger framework.

For triggering the temporary RS, a selection is made according to the following alternatives, or the RAN2 is made aware of the status of this discussion.

Alternative 1: bitmap method in MAC-CE

■ Each Z bit block in the bitmap corresponds to one SCell, and Z is more than or equal to 0.

■ The Z-bit block indicates a temporary RS configuration index, and a value of zero indicated by the bit block indicates that no RS resource is transmitted.

■ The SCell to be activated is indicated by a C value in a legacy SCell activation/deactivation MAC CE or a new MAC-CE.

Alternative 2: reuse A-TRS trigger framework

■ The trigger state is indicated explicitly by the MAC-CE.

■ The association relation between the triggering states of one or more scells and the temporary RS is configured through RRC according to the Rel-16A-TRS triggering framework.

■ FFS (FFS): a value of zero for the MAC-CE indication indicates that no temporary RS is triggered by the MAC-CE for all scells to be activated.

Note that the goal of the selection is the RAN1 consensus on the MAC-CE function, and the RRC parameter list of this feature. Any of the above MAC-CE signaling designs is a reference concept, the final MAC-CE signaling design of which depends on RAN2.

Both alternatives are analyzed below.

-bitmap method

For the bitmap approach, each Z-bit block in the bitmap corresponds to one SCell, with each block indicating an index of the associated temporary RS. While this requires a new design that differs from the existing CSI triggering framework, the design and use of this approach is very simple, especially in cases where it is not necessary to jointly encode the temporary RS triggering information on multiple carriers. On the other hand, it is questionable why joint multi-carrier coding is required, since the current SCell activation/deactivation design does not require multi-carrier joint activation/deactivation on a per cell basis.

Reuse of existing CSI trigger frameworks

The existing CSI trigger framework can support AP TRS/CSI-RS/CSI-IM measurement and AP CSI reporting. The trigger state list is provided to each serving cell through RRC configuration, and if the list is too large to be put in the CSI request field, the MAC CE selects one sub-list for the CSI request field sub-list. Then, the DCI CSI request field triggers only one of the trigger states.

In addition, since the existing CSI-trigger framework is applicable to each cell (aperiodic CSI-trigger state sub-selection MAC CE includes a serving cell ID and a BWP ID), this design may not be used for joint multicarrier triggering.

If a separate trigger state list (separate from the trigger state list of CSI on BWP of the cell) is to be provided for the temporary RS based on AP TRS, this approach may not have any advantage compared to the simple bitmap approach, especially because the multi-carrier joint triggering has no motivation and cannot be supported.

If the trigger state list of CSI is increased by the temporary RS (i.e., CSI trigger and temporary RS trigger use the same trigger state list), the bit widths of both the CSI request field and the temporary RS trigger field are increased, resulting in an increase in control signaling overhead.

This approach is only possible if the MAC CE also supports temporary RS-based CSI acquisition (CSI-RS/CSI-IM for CSI) to trigger the AP TRS. Some additional designs below may also be required.

■ For each cell, 2 MAC CE fields may be required, one for the AP TRS-based temporary RS and one for the AP CSI trigger. Combining these two fields for joint triggering may not be reasonable because this may limit flexibility.

■ A trigger status list is provided for each field and the current CSI trigger framework is reused for each field/list. The AP TRS trigger status list may include only temporary RSs based on the AP TRS (e.g., NZP CSI-RS on BWP with ID first activedownlinkbwp-ID and BWP including TRS-info). The AP CSI trigger status list may reuse the list of DCI format 0_1 or the list of DCI format 0_2 entirely, but is limited to BWP with ID first activedownlinkbwp-ID. Alternatively, the same mechanism may be used to provide the new list, but only including the CSI-RS/CSI-IM on BWP with ID first ActiveDownlink BWP-Id.

In summary, a simple bitmap approach may be sufficient for the AP TRS-based temporary RS trigger by MAC CE, but the current AP CSI trigger frame may be reused to a large extent for the AP CSI trigger by MAC CE.

For triggering the temporary RS through the MAC CE, if the acquisition of the AP CSI through the MAC CE is also supported, the reuse of the current AP CSI triggering framework can be supported; otherwise, the bitmap approach may be supported.

In another embodiment, based on the RAN2 protocol, RRC messages may be used for SCG activation, and activating the SCell while activating the SCG/PSCell may reduce the latency of the SCell activation. The RRC SCG activation message may be used to activate the PSCell plus some or all of the scells in the SCG. In this case, the state (active or keep inactive) of each SCG SCell is indicated in an RRC message.

The bit indication of activation (1)/deactivation (0) of each SCell index may be included in the RRC SCG activation message.

For each SCell index with an activation indication, a corresponding TRS index is specified/listed in the message, and corresponding CSI-RS and SRS may also be included for activation with the SCell. If the TRS index associated with the activated SCell does not exist, a default TRS is activated.

For each SCell still remaining in the deactivated state, only the deactivation indication is under each SCell index of the deactivated SCell.

If RRC SCG activation activates only PSCell (primary cell in SCG), SCell activation state information is not included in the SCG activation message.

Upon receiving the RRC SCG activation message, the UE performs the following procedure.

-if the RRC SCG activation message activates only the PSCell of the SCG, the UE performs an activation procedure only on the PSCell. Further activation of one or more scells and TRSs is then triggered by the MAC CE, as previously described.

-if the SCell status is included in the SCG activation message:

the UE first performs PSCell activation procedures (including synchronization and random access if necessary);

if under the SCell index, assert an activate indication:

● The UE also performs an SCell activation procedure;

● If there is a TRS index:

● The UE detects the TRS according to an index pointing to an alternative TRS configuration for detection;

● If there is no TRS index:

● The UE detects TRS according to the configuration of the default TRS;

if under the SCell index, assert a deactivate indication:

● The UE keeps the SCell in a deactivated state. The SCell may be activated by the MAC CE, with the associated TRS then also activated.

Regarding the AP SSB, other UEs receiving DL SSB/RS/control/data from the cell may need to perform rate matching/puncturing around the AP SSB when transmitting. In some embodiments of the present invention, in some embodiments,

one or more of the following parameters may need to be signaled to the UE aperiodically.

O-carrier Freq or ssb-Freq

○halfFrameIndex

○ssbSubcarrierSpacing

○SSB-SMTC

Starting slot position of starting SSB, e.g. as sfn-SSB-offset

One or more slot offsets of other SSBs, also representing the number of AP SSB samples

PRB position. The PRB location may or may not be the same as the SSB currently configured by the UE. If not, the PRB position needs to be signaled.

SSB index

Flag indicating whether PBCH/DMRS is also present

● In some embodiments, if the UE needs to read the PBCH, the AP SSB includes PSS/SSS and PBCH.

● In some embodiments, if the UE needs to read the PBCH, or if information carried in the PBCH is sent from another serving cell to the UE through RRC signaling, the AP SSB includes only PSS/SSS, and does not include the PBCH and its DMRS.

In some embodiments, the following parameters of the conventional rate matching mode may not be required: period, ssb-period, CORSET information, etc.

In some embodiments, if the AP SSB has the same design as the periodic SSB monitored by the UE, only SSB location parameters and SSB-index in the time domain (e.g., starting slot, one or more slot offsets) and frequency domain (if different from the current SSB PRB location) may be needed, as well as the flags for the existence of the PBCH.

In some embodiments, the signaling may be in DCI (e.g., GC DCI or UE-specific DCI). Or may be a MAC CE transmitted simultaneously with the SCell activated MAC CE. To reduce signaling overhead, some of the parameters listed above may be combined together and preconfigured by RRC configuration signaling, the DCI/MAC CE may carry only dynamic information, e.g., starting slot position, one of a plurality of sets of configuration parameters, etc. If the AP SSB does not completely overlap with the periodic SSB, only the signaling is sent. The UE may or may not know that the signaling is for sending the AP SSB (e.g., may be transparent to the UE). In the non-transparent case, existing SSB region designs may be used to specify the region for rate matching/non-reception by the UE. In the case of transparency, the number of OFDM symbols and PRBs for the region may need to be specified.

In some embodiments, PDSCH may be rate matched around AP SSB as indicated by signaling.

In some embodiments, the UE may not monitor the PDCCH candidates if they overlap with the AP SSBs on any resource elements. That is, the monitoring timing overlapping with the AP SSB is not a valid monitoring timing.

In some embodiments, for RS transmissions, the UE does not use REs to make measurements if any RE falls within the signaled region. In some embodiments, the UE does not monitor for RS transmissions if at least one RE falls within the signaled region.

Fig. 27A is a flow chart of a method 2700 for SCell activation provided by some embodiments. Method 2700 begins with operation 2702. In operation 2702, the UE receives first signaling from a base station, wherein the first signaling includes a first configuration of a first channel state information reference signal (channel state information reference signal, CSI-RS) for tracking a secondary cell (SCell). The first configuration is associated with a first Identifier (ID). In operation 2704, the UE receives second signaling from the base station, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell. The second configuration is associated with a second ID, the second configuration including the first ID. In operation 2706, the UE receives a media control access control unit (medium control access control element, MAC CE) message from the base station. The MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID. In operation 2708, the UE receives the RS for fast SCell activation of the SCell from the base station. The RS includes a first burst of the first CSI-RS for tracking. In operation 2710, upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS. In operation 2712, the UE sends a report to the base station indicating that the SCell has been activated for the UE.

In some embodiments, the MAC CE message may further include a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to the plurality of scells. The MAC CE message may not include any ID of RS or RS configuration of each of the one or more scells to be deactivated. In some embodiments, the MAC CE message may include RS configuration IDs of the one or more scells to be activated corresponding to the one or more activation commands. The bitmap in the MAC CE message may include an activate command bit corresponding to the one or more activate commands. The RS configuration ID may be arranged after a bitmap in the MAC CE message in ascending order of one or more scells to be activated in the bitmap. In some embodiments, the UE may perform SCell activation by at least one of setting automatic gain control (automatic gain control, AGC) from the first burst or performing time-frequency synchronization or tracking on the SCell from the first burst. In some embodiments, the RS may further include a second burst of the first CSI-RS for tracking, subsequent to the first burst. The duration between the first burst and the second burst may be associated with a gap value indicated by the second configuration. In some embodiments, the UE may perform SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst. In some embodiments, the RS may be aperiodic and may be transmitted to the UE in response to transmitting the SCell activation command. In some embodiments, the UE may receive the RS by receiving the RS from the base station on a first bandwidth part (BWP) of the SCell. The first BWP may be associated with a first actionlowlinkbwp-Id. The first actiondownlinkbwp-Id may be configured in an RRC message when configuring the SCell. The first BWP is activated at the same time as the SCell is activated. In some embodiments, the first CSI-RS for tracking may be configured as an aperiodic CSI-RS for tracking on the first BWP. In some embodiments, the second configuration may further indicate an offset value associated with a delay between a time slot (n+k) representing an ending time slot of the MAC CE message and the first burst, the time slot (n+k) representing one time slot after decoding and processing the MAC CE message. In some embodiments, the report may include Downlink (DL) CSI.

Fig. 27B is a flow chart of a method 2750 for SCell activation provided by some embodiments. Method 2750 begins with operation 2752. In operation 2752, the base station transmits first signaling to the UE, wherein the first signaling includes a first configuration of a first channel state information reference signal (channel state information reference signal, CSI-RS) for tracking a secondary cell (SCell). The first configuration is associated with a first Identifier (ID). In operation 2754, the base station transmits second signaling to the UE, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell. The second configuration is associated with a second ID, the second configuration including the first ID. In operation 2756, the base station transmits a media control access control unit (medium control access control element, MAC CE) message to the UE. The MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID. In operation 2758, the base station transmits the RS for fast SCell activation of the SCell to the UE. The RS includes a first burst of the first CSI-RS for tracking. Upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS. In operation 2760, the base station receives a report from the UE indicating that the SCell has been activated for the UE.

In some embodiments, the MAC CE message may further include a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to the plurality of scells. The MAC CE message may not include any ID of RS or RS configuration of each of the one or more scells to be deactivated. In some embodiments, the MAC CE message may include RS configuration IDs of the one or more scells to be activated corresponding to the one or more activation commands. The bitmap in the MAC CE message may include an activate command bit corresponding to the one or more activate commands. The RS configuration ID may be arranged after a bitmap in the MAC CE message in ascending order of one or more scells to be activated in the bitmap. In some embodiments, the UE may perform SCell activation by at least one of setting automatic gain control (automatic gain control, AGC) from the first burst or performing time-frequency synchronization or tracking on the SCell from the first burst. In some embodiments, the RS may further include a second burst of the first CSI-RS for tracking, subsequent to the first burst. The duration between the first burst and the second burst may be associated with a gap value indicated by the second configuration. In some embodiments, the UE may perform SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst. In some embodiments, the RS may be aperiodic and may be transmitted to the UE in response to transmitting the SCell activation command. In some embodiments, the base station may transmit the RS by transmitting the RS to the UE on a first bandwidth part (BWP) of the SCell. The first BWP may be associated with a first actionlowlinkbwp-Id. The first actiondownlinkbwp-Id may be configured in an RRC message when configuring the SCell. The first BWP is activated at the same time as the SCell is activated. In some embodiments, the first CSI-RS for tracking may be configured as an aperiodic CSI-RS for tracking on the first BWP. In some embodiments, the second configuration may further indicate an offset value associated with a delay between a time slot (n+k) representing an ending time slot of the MAC CE message and the first burst, the time slot (n+k) representing one time slot after decoding and processing the MAC CE message. In some embodiments, the report may include Downlink (DL) CSI.

Fig. 28 illustrates an exemplary communication system 2800. In general, the system 2800 enables a plurality of wireless or wired users to send and receive data and other content. System 2800 can implement one or more channel access methods, such as code division multiple access (code division multiple access, CDMA), time division multiple access (time division multiple access, TDMA), frequency division multiple access (frequency division multiple access, FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).

In this example, communication system 2800 includes electronic devices (electronic device, ED) 2810a to 2810c, radio access networks (radio access network, RAN) 2820a to 2820b, core network 2830, public switched telephone network (public switched telephone network, PSTN) 2840, internet 2850, and other networks 2860. Although fig. 28 illustrates a number of these components or units, any number of these components or units may be included in system 2800.

ED 2810a through 2810c are for operation or communication in system 2800. For example, EDs 2810a to 2810c are used for transmission or reception through a wireless communication channel or a wired communication channel. Each ED 2810a to 2810c represents any suitable end user device and may include the following devices (or may be referred to as): a User Equipment (UE), a wireless transmit or receive unit (wireless transmit or receive unit, WTRU), a mobile station, a fixed or mobile subscriber unit, a cellular telephone, a personal digital assistant (personal digital assistant, PDA), a smart phone, a notebook computer, a touch pad, a wireless sensor, or a consumer electronic device.

The RANs 2820a to 2820b here include base stations 2870a to 2870b, respectively. Base stations 2870 a-2870 b are each configured to wirelessly connect to one or more of EDs 2810 a-2810 c to enable access to core network 2830, PSTN 2840, internet 2850, or other network 2860. For example, the base stations 2870 a-2870 b may include (or may be) one or more of several well-known devices, such as a base transceiver station (base transceiver station, BTS), a NodeB (NodeB), an evolved NodeB (eNodeB), a Next Generation (NG) NodeB (NG NodeB, gNB), a home NodeB (Home NodeB), a home eNodeB, a site controller, an Access Point (AP), or a wireless router. ED 2810a to 2810c are for connection and communication with the Internet 2850 and may access the core network 2830, PSTN 2840, or other networks 2860.

In the embodiment illustrated in fig. 28, base station 2870a is part of RAN 2820a, and RAN 2820a may include other base stations, units, and/or devices. Likewise, base station 2870b is part of RAN 2820b, and RAN 2820b may include other base stations, units, or devices. The base stations 2870 a-2870 b each transmit and/or receive wireless signals within a particular geographic region or area (sometimes referred to as a "cell"). In some embodiments, multiple-input multiple-output (MIMO) technology may be employed such that multiple transceivers are used for each cell.

Base stations 2870 a-2870 b communicate with one or more EDs 2810 a-2810 c over one or more air interfaces 2890 using a wireless communication link. Air interface 2890 may utilize any suitable radio access technology.

It is contemplated that system 2800 may use multi-channel access functionality, including the schemes described above. In a specific embodiment, the base station and ED implement a 5G New Radio (NR), LTE-A or LTE-B. Of course, other multiple access schemes and wireless protocols may be used.

RANs 2820a through 2820b communicate with core network 2830 to provide voice, data, applications, voice over IP (Voice over Internet Protocol, voIP) or other services to EDs 2810a through 2810 c. It is to be appreciated that the RANs 2820 a-2820 b or the core network 2830 may communicate directly or indirectly with one or more other RANs (not shown). The core network 2830 may also be accessed as a gateway to other networks (e.g., PSTN 2840, internet 2850, and other networks 2860). In addition, some or all of EDs 2810 a-2810 c may include functionality to communicate with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of (or in addition to) wireless communication, the ED may communicate with a service provider or switch (not shown) and with the Internet 2850 via a wired communication channel.

Although fig. 28 shows one example of a communication system, various modifications may be made to fig. 28. For example, communication system 2800 may include any number of EDs, base stations, networks, or other components in any suitable configuration.

Fig. 29A and 29B illustrate exemplary devices that may implement methods and guidelines according to the present disclosure. Specifically, fig. 29A illustrates an exemplary ED 2910, and fig. 29B illustrates an exemplary base station 2970. These components may be used in system 2800 or any other suitable system.

As shown in fig. 29A, ED 2910 includes at least one processing unit 2900. The processing unit 2900 implements various processing operations of the ED 2910. For example, processing unit 2900 may perform signal encoding, data processing, power control, input/output processing, or any other function that enables ED 2910 to operate in system 2900. The processing unit 2900 also supports the methods and guidelines detailed above. Each processing unit 2900 includes any suitable processing device or computing device for performing one or more operations. For example, each processing unit 2900 may include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

ED 2910 also includes at least one transceiver 2902. The transceiver 2902 is used to modulate data or other content for transmission through at least one antenna or network interface controller (Network Interface Controller, NIC) 2904. The transceiver 2902 is also configured to demodulate data or other content received via the at least one antenna 2904. Each transceiver 2902 includes any suitable structure for generating signals for wireless transmission or wired transmission or for processing signals received wirelessly or by wired means. Each antenna 2904 includes any suitable structure for transmitting or receiving wireless signals or wired signals. One or more transceivers 2902 may be used in ED 2910, and one or more antennas 2904 may be used in ED 2910. Although transceiver 2902 is shown as a single functional unit, transceiver 2902 may also be implemented using at least one transmitter and at least one separate receiver.

ED 2910 also includes one or more input/output devices 2906 or interfaces (e.g., a wired interface to the Internet 2850). The input/output devices 2906 support interaction with users or other devices in the network (network communications). Each input/output device 2906 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.

In addition, ED 2910 includes at least one memory 2908. The memory 2908 stores instructions and data used, generated, or collected by the ED 2910. For example, memory 2908 may store software instructions or firmware instructions that are executed by one or more processing units 2900 and data for reducing or eliminating interference in input signals. Each memory 2908 includes any suitable volatile or nonvolatile storage and retrieval device or devices. Any suitable type of memory may be used, such as random access memory (random access memory, RAM), read Only Memory (ROM), hard disk, optical disk, subscriber identity module (subscriber identity module, SIM) card, memory stick, secure Digital (SD) memory card, etc.

As shown in fig. 29B, the base station 2970 includes at least one processing unit 2950, at least one transceiver 2952 including functions of a transmitter and a receiver, one or more antennas 2956, at least one memory 2958, and one or more input/output devices or interfaces 2966. The scheduler is coupled to the processing unit 2950 as will be appreciated by those skilled in the art. The scheduler may be included in the base station 2970 or may operate separately from the base station 2970. The processing unit 2950 implements various processing operations of the base station 2970, such as signal encoding, data processing, power control, input/output processing, or any other function. The processing unit 2950 may also support the methods and guidelines detailed above. Each processing unit 2950 includes any suitable processing device or computing device for performing one or more operations. For example, each processing unit 2950 may include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

Each transceiver 2952 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 2952 also includes any suitable structure for processing signals received from one or more EDs or other devices, either wirelessly or by wire. While the transmitter and the receiver are shown combined into transceiver 2952, the transmitter and the receiver may be separate components. Each antenna 2956 includes any suitable structure for transmitting or receiving wireless signals or wired signals. Although a common antenna 2956 is shown coupled to the transceivers 2952, one or more antennas 2956 may be coupled to one or more transceivers 2952, allowing separate antennas 2956 to be coupled to the transmitters and receivers when the transmitters and receivers are configured as separate components. Each memory 2958 includes any suitable volatile or nonvolatile storage and retrieval device or devices. Each input/output device 2966 supports interactions with users or other devices in the network (network communications). Each input/output device 2966 includes any suitable structure for providing information to or receiving/providing information from a user, including network interface communications.

Fig. 30 is a block diagram of a computing system 3000 that may be used to implement the devices and methods disclosed herein. For example, the computing system may be any entity in a UE, access Network (AN), mobility management (mobility management, MM), session management (session management, SM), user plane gateway (user plane gateway, UPGW), or Access Stratum (AS). A particular device may use all or only a subset of the components shown, and the level of integration may vary from device to device. Moreover, an apparatus may include multiple instances of components, e.g., multiple processing units, multiple processors, multiple memories, multiple transmitters, multiple receivers, and so forth. The computing system 3000 includes a processing unit 3002. The processing unit includes a central processing unit (central processing unit, CPU) 3014, memory 3008, and may also include a mass storage device 3004, video adapter 3010, and I/O interface 3012 connected to bus 3020.

Bus 3020 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 3014 may comprise any type of electronic data processor. Memory 3008 may include any type of non-transitory system memory, such as static random access memory (static random access memory, SRAM), dynamic random access memory (dynamic random access memory, DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In one embodiment, memory 3008 may include ROM for use in booting and DRAM for storing programs and data for use in executing programs.

The mass memory 3004 may include any type of non-transitory storage device for storing and making accessible via the bus 3020 data, programs, and other information. For example, mass storage 3004 may include one or more of a solid state disk, a hard disk drive, a magnetic disk drive, or an optical disk drive.

The video adapter 3010 and the I/O interface 3012 provide an interface to couple external input and output devices to the processing unit 3002. As shown, examples of input and output devices include a display 3018 coupled to the video adapter 3010 and a mouse, keyboard, or printer 3016 coupled to the I/O interface 3012. Other devices may be coupled to the processing unit 3002 and additional or fewer interface cards may be used. For example, a serial interface such as a universal serial bus (universal serial bus, USB) (not shown) may be used to provide an interface for external devices.

The processing unit 3002 also includes one or more network interfaces 3006, which may include wired links, such as ethernet cables, or wireless links to access nodes or different networks. The network interface 3006 allows the processing unit 3002 to communicate with remote units over a network. For example, the network interface 3006 may provide wireless communications via one or more transmitter/transmit antennas and one or more receiver/receive antennas. In one embodiment, the processing unit 3002 is coupled to a local area network 3022 or wide area network for data processing and communication with other processing units, the internet, or remote storage facilities, among other remote devices.

It should be understood that one or more steps of the embodiment methods provided herein may be performed by the corresponding units or modules. For example, the signal may be transmitted by a transmitting unit or a transmitting module. The signal may be received by a receiving unit or a receiving module. The signals may be processed by a processing unit or processing module. The corresponding units or modules may be hardware, software or a combination thereof. For example, one or more of the units or modules may be an integrated circuit, such as a field programmable gate array (field programmable gate array, FPGA) or an application-specific integrated circuit (ASIC).

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the disclosure as defined by the appended claims.

Claims

1. A method, comprising:

a User Equipment (UE) receiving first signaling from a base station, wherein the first signaling includes a first configuration for tracking a first channel state information reference signal (CSI-RS) of a secondary cell (SCell), the first configuration being associated with a first Identifier (ID);

the UE receiving second signaling from the base station, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell, the second configuration being associated with a second ID, the second configuration including the first ID;

The UE receiving a media control access control element (MAC CE) message from the base station, wherein the MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID;

the UE receives the fast SCell-activated RS for the SCell from the base station, wherein the RS comprises a first burst of the first CSI-RS for tracking;

upon receiving the SCell activation command, the UE performs SCell activation to activate the SCell according to at least the RS;

the UE sends a report to the base station indicating that the SCell has been activated for the UE.

2. The method of claim 1, wherein the MAC CE message further comprises a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to a plurality of scells, the MAC CE message excluding any IDs of RS or RS configurations of each of the one or more scells to be deactivated.

3. The method of any one of claims 1-2, wherein the MAC CE message includes RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands, a bitmap in the MAC CE message includes activation command bits corresponding to the one or more activation commands, the RS configuration IDs being arranged after a bitmap in the MAC CE message in ascending order of the one or more scells to be activated in the bitmap.

4. A method according to any of claims 1 to 3, wherein the performing SCell activation comprises at least one of:

the UE setting an Automatic Gain Control (AGC) according to the first burst; or alternatively

The UE performs time-frequency synchronization or tracking on the SCell according to the first burst.

5. The method of any of claims 1-4, wherein the RS further comprises a second burst of the first CSI-RS for tracking subsequent to the first burst, a duration between the first burst and the second burst being associated with a gap value indicated by the second configuration.

6. The method according to any one of claims 1 to 5, wherein the performing SCell activation comprises:

the UE sets AGC according to the first burst; and

and the UE performs time-frequency synchronization or tracking on the SCell according to the second burst.

7. The method of any one of claims 1 to 6, wherein the RS is aperiodic and is transmitted to the UE in response to transmitting the SCell activation command.

8. The method of any of claims 1-7, wherein the receiving the RS comprises:

the UE receives the RS from the base station on a first one of one or more bandwidth parts (BWP) of the SCell, wherein the first BWP is associated with a first activedownlinkbwp-Id that is configured in an RRC message when the SCell is configured, and wherein the first BWP is activated simultaneously with activation of the SCell.

9. The method of any of claims 1-8, wherein the first CSI-RS for tracking is configured as an aperiodic CSI-RS for tracking on the first BWP.

10. The method of any of claims 1-9, wherein the second configuration further indicates an offset value associated with a delay between a time slot (n+k) and the first burst, wherein time slot n represents an ending time slot of the MAC CE message and time slot (n+k) represents one time slot after decoding and processing the MAC CE message.

11. The method of any of claims 1-10, wherein the report comprises Downlink (DL) CSI.

12. A method, comprising:

a base station transmitting first signaling to a User Equipment (UE), wherein the first signaling includes a first configuration for tracking a first channel state information reference signal (CSI-RS) of a secondary cell (SCell), the first configuration being associated with a first Identifier (ID);

the base station transmitting second signaling to the UE, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell, the second configuration being associated with a second ID, the second configuration including the first ID;

The base station transmitting a media control access control element (MAC CE) message to the UE, wherein the MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID;

the base station sends the RS for the rapid SCell activation of the SCell to the UE, wherein the RS comprises a first burst of the first CSI-RS for tracking;

wherein the UE performs SCell activation when receiving the SCell activation command, to activate the SCell according to at least the RS;

the base station receives a report from the UE indicating that the SCell has been activated for the UE.

13. The method of claim 12, wherein the MAC CE message further includes a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to a plurality of scells, the MAC CE message excluding any IDs of RS or RS configurations of each of the one or more scells to be deactivated.

14. The method of any one of claims 12 to 13, wherein the MAC CE message includes RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands, a bitmap in the MAC CE message includes activation command bits corresponding to the one or more activation commands, the RS configuration IDs being arranged after a bitmap in the MAC CE message in ascending order of the one or more scells to be activated in the bitmap.

15. The method of any of claims 12-14, wherein the UE performs SCell activation by at least one of setting Automatic Gain Control (AGC) according to the first burst or performing time-frequency synchronization or tracking on the SCell according to the first burst.

16. The method of any of claims 12-15, wherein the RS further comprises a second burst of the first CSI-RS for tracking subsequent to the first burst, a duration between the first burst and the second burst being associated with a gap value indicated by the second configuration.

17. A method according to any of claims 12 to 16, wherein the UE performs SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst.

18. The method of any one of claims 12 to 17, wherein the RS is aperiodic and is transmitted to the UE in response to transmitting the SCell activation command.

19. The method of any of claims 12-18, wherein the transmitting the RS comprises:

the base station transmits the RS to the UE on a first one of one or more bandwidth parts (BWP) of the SCell, wherein the first BWP is associated with a first activedownlinkbwp-Id that is configured in an RRC message when the SCell is configured, and wherein the first BWP is activated simultaneously with activation of the SCell.

20. The method of any of claims 12-19, wherein the first CSI-RS for tracking is configured as an aperiodic CSI-RS for tracking on the first BWP.

21. The method of any of claims 12 to 20, wherein the second configuration further indicates an offset value associated with a delay between a time slot (n+k) and the first burst, wherein time slot n represents an ending time slot of the MAC CE message and time slot (n+k) represents one time slot after decoding and processing the MAC CE message.

22. The method of any of claims 12-21, wherein the report comprises Downlink (DL) CSI.

23. A User Equipment (UE), wherein the UE comprises:

at least one processor;

a non-transitory computer-readable storage medium storing a program, wherein the program comprises instructions that, when executed by the at least one processor, cause the UE to perform operations comprising:

receiving first signaling from a base station, wherein the first signaling includes a first configuration for tracking a first channel state information reference signal (CSI-RS) of a secondary cell (SCell), the first configuration being associated with a first Identifier (ID);

Receiving second signaling from the base station, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell, the second configuration being associated with a second ID, the second configuration including the first ID;

receiving a media control access control element (MAC CE) message from the base station, wherein the MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID;

receiving the fast SCell-activated RS for the SCell from the base station, wherein the RS comprises a first burst of the first CSI-RS for tracking;

when receiving the SCell activation command, performing SCell activation to activate the SCell according to at least the RS;

a report is sent to the base station indicating that the SCell has been activated for the UE.

24. The UE of claim 23, wherein the MAC CE message further comprises a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to a plurality of scells, the MAC CE message excluding any IDs of RS or RS configurations of each of the one or more scells to be deactivated.

25. The UE of any of claims 23-24, wherein the MAC CE message includes RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands, a bitmap in the MAC CE message includes activation command bits corresponding to the one or more activation commands, the RS configuration IDs being arranged after a bitmap in the MAC CE message in ascending order of the one or more scells to be activated in the bitmap.

26. The UE of any of claims 23-25, wherein the performing SCell activation comprises at least one of:

setting an Automatic Gain Control (AGC) based on the first burst; or alternatively

And performing time-frequency synchronization or tracking on the SCell according to the first burst.

27. The UE of any of claims 23-26, wherein the RS further comprises a second burst of the first CSI-RS for tracking subsequent to the first burst, a duration between the first burst and the second burst being associated with a gap value indicated by the second configuration.

28. The UE of any of claims 23-27, wherein the performing SCell activation comprises:

setting an AGC according to the first burst; and

and performing time-frequency synchronization or tracking on the SCell according to the second burst.

29. The UE of any of claims 23 to 28, wherein the RS is aperiodic and the RS is transmitted to the UE in response to transmitting the SCell activation command.

30. The UE of any of claims 23-29, wherein the receiving the RS comprises:

the RS is received from the base station on a first of one or more bandwidth parts (BWP) of the SCell, wherein the first BWP is associated with a first activedownlinkbwp-Id that is configured in an RRC message when configuring the SCell, the first BWP being activated at the same time as the SCell is activated.

31. The UE of any of claims 23-30, wherein the first CSI-RS for tracking is configured as an aperiodic CSI-RS for tracking on the first BWP.

32. The UE of any of claims 23-31, wherein the second configuration further indicates an offset value associated with a delay between a time slot (n+k) and the first burst, wherein time slot n represents an ending time slot of the MAC CE message and time slot (n+k) represents one time slot after decoding and processing the MAC CE message.

33. The UE of any of claims 23 to 32, wherein the report includes Downlink (DL) CSI.

34. A base station, wherein the base station comprises:

at least one processor;

a non-transitory computer readable storage medium storing a program, wherein the program comprises instructions that when executed by the at least one processor cause the base station to perform operations comprising:

transmitting first signaling to a User Equipment (UE), wherein the first signaling includes a first configuration for tracking a first channel state information reference signal (CSI-RS) of a secondary cell (SCell), the first configuration being associated with a first Identifier (ID);

Transmitting second signaling to the UE, wherein the second signaling includes a second configuration of Reference Signals (RSs) for fast SCell activation of the SCell, the second configuration being associated with a second ID, the second configuration including the first ID;

transmitting a media control access control element (MAC CE) message to the UE, wherein the MAC CE message includes an SCell activation command instructing the UE to activate the SCell and the second ID;

transmitting the fast SCell-activated RS for the SCell to the UE, wherein the RS comprises a first burst of the first CSI-RS for tracking,

a report is received from the UE indicating that the SCell has been activated for the UE.

35. The base station of claim 34, wherein the MAC CE message further comprises a bitmap of at least one of one or more activation commands or one or more deactivation commands corresponding to a plurality of scells, the MAC CE message excluding any IDs of RS or RS configurations of each of the one or more scells to be deactivated.

36. The base station of any of claims 34-35, wherein the MAC CE message includes RS configuration IDs of one or more scells to be activated corresponding to the one or more activation commands, a bitmap in the MAC CE message includes activation command bits corresponding to the one or more activation commands, the RS configuration IDs being arranged after a bitmap in the MAC CE message in ascending order of the one or more scells to be activated in the bitmap.

37. The base station of any of claims 34 to 36, wherein the UE performs SCell activation by at least one of setting Automatic Gain Control (AGC) according to the first burst or performing time-frequency synchronization or tracking on the SCell according to the first burst.

38. The base station of any of claims 34 to 37, wherein the RS further comprises a second burst of the first CSI-RS for tracking subsequent to the first burst, a duration between the first burst and the second burst being associated with a gap value indicated by the second configuration.

39. The base station according to any of claims 34 to 38, wherein the UE performs SCell activation by setting AGC according to the first burst and performing time-frequency synchronization or tracking on the SCell according to the second burst.

40. The base station of any of claims 34 to 39, wherein the RS is aperiodic and is transmitted to the UE in response to transmitting the SCell activation command.

41. The base station of any of claims 34 to 40, wherein the transmitting the RS comprises:

the RS is transmitted to the UE on a first of one or more bandwidth parts (BWP) of the SCell, wherein the first BWP is associated with a first actiondownlinkbwp-Id that is configured in an RRC message when configuring the SCell, the first BWP being activated at the same time as the SCell is activated.

42. The base station of any of claims 34-41, wherein the first CSI-RS for tracking is configured as an aperiodic CSI-RS for tracking on the first BWP.

43. The base station of any of claims 34 to 42, wherein the second configuration further indicates an offset value associated with a delay between a time slot (n+k) and the first burst, wherein time slot n represents an ending time slot of the MAC CE message and time slot (n+k) represents one time slot after decoding and processing the MAC CE message.

44. The base station of any of claims 34 to 43, wherein the report comprises Downlink (DL) CSI.