PDCCH handling during SCG activation

Abstract

The present disclosure relates to techniques for physical downlink control channel processing when activating a secondary cell group in a wireless communication system. A wireless device can establish a radio link with a master cell group. A secondary cell group can be configured. The wireless device can receive an indication to activate the secondary cell group without performing a random access channel procedure on the secondary cell group. The wireless device can determine quasi co-location information for a physical downlink control channel of the secondary cell group. The wireless device can perform physical downlink control channel decoding of the physical downlink control channel of the secondary cell group using the determined quasi co-location information.

Description

TECHNICAL FIELD

[0001] This application relates to wireless communication, and more particularly to systems, apparatus and methods for physical downlink control channel processing when activating a secondary cell group in a wireless communication system. BACKGROUND

[0002] The use of wireless communication systems is rapidly increasing. In more recent years, wireless devices such as smart phones and tablet computers have become increasingly sophisticated. In addition to supporting telephone calls, many mobile devices (i.e., user equipment devices or UEs) now provide access to the Internet, email, text messaging, and navigation using the global positioning system (GPS), among other things, and can operate sophisticated, complex applications that utilize these functions. Furthermore, there are numerous different wireless communication technologies and wireless communication standards. Some examples of wireless communication standards include GSM, UMTS (e.g., associated with WCDMA or TD-SCDMA air interfaces), LTE, LTE-Advanced (LTE-A), NR, HSPA, 3GPP2 CDMA2000 (e.g., lxRTT, lxEV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), BLUETOOTH TM , etc.

[0003] The introduction of an ever-increasing number of features and functions in wireless communication devices also requires continued improvements to wireless communication and to wireless communication devices. It is particularly important to ensure the accuracy of signals transmitted and received by user equipment (UE) devices (e.g., by wireless devices such as cellular telephones, base stations, and relay stations used in wireless cellular communications). Moreover, increasing the functionality of UE devices can place significant stress on the battery life of the UE devices. Thus, it is also very important to reduce the power requirements in the design of UE devices while allowing the UE devices to maintain good transmission and reception capabilities to improve communications. Therefore, improvements in this area are highly desirable. SUMMARY

[0004] Embodiments of apparatuses, systems, and methods for physical downlink control channel processing when activating a secondary cell group in a wireless communication system are presented herein.

[0005] According to the techniques described herein, a wireless device can be configured to reactivate a secondary cell group without performing a random access channel procedure as part of the reactivation. To support the ability of a wireless device to receive downlink communications on a recently reactivated secondary cell group without first performing a random access channel procedure, the wireless device is provided with techniques to implicitly or explicitly determine the quasi co-location information of the secondary cell group through configuration information, for example, upon receiving an indication to reactivate the secondary cell group.

[0006] In addition, techniques are provided for quickly determining when a wireless device experiences problems with communications on a reactivated secondary cell group, which can include using radio link monitoring parameters configured for reactivation of the secondary cell group, which can allow for faster radio link failure detection. Moreover, techniques are provided for quickly recovering a link with the secondary cell group when such problems are detected, which can include techniques for performing a random access channel procedure to recover a wireless link with the secondary cell group using dedicated random access channel resources of the random access channel procedure and / or using an identifier of the wireless device configured for the secondary cell group when performing the random access channel procedure.

[0007] Techniques are also provided for configuring a wireless device to provide channel feedback information for a secondary cell group to a master cell group (e.g., in connection with secondary cell group reactivation or otherwise), which can facilitate faster and / or more reliable configuration of various possible communication parameters between the secondary cell group and the wireless device.

[0008] It should be noted that the techniques described herein can be implemented in and / or used with a number of different types of devices, including but not limited to base stations, access points, mobile phones, tablet computers, wearable devices, unmanned aerial vehicles, unmanned aerial vehicle controllers, automobiles and / or motor vehicles, and various other computing devices.

[0009] This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following DETAILED DESCRIPTION, Figures, and Claims. BRIEF DESCRIPTION OF DRAWINGS

[0010] A better understanding of the present subject matter will be had upon consideration of the following detailed description of various embodiments, taken in conjunction with the accompanying drawings, in which:

[0011] Figure 1 An exemplary (and simplified) wireless communication system is shown in accordance with some embodiments;

[0012] Figure 2 An exemplary base station in communication with exemplary wireless user equipment (UE) devices is shown in accordance with some embodiments;

[0013] Figure 3 An exemplary block diagram of a UE is shown in accordance with some embodiments;

[0014] Figure 4 An exemplary block diagram of a base station is shown in accordance with some embodiments;

[0015] Figure 5 is a flow diagram showing aspects of an exemplary possible method for physical downlink control channel handling when activating a secondary cell group in a wireless communication system in accordance with some embodiments;

[0016] Figure 6 Exemplary aspects of a possible 5G NR frame are shown in accordance with some embodiments;

[0017] Figure 7 Exemplary aspects of a possible dual connectivity configuration between a UE and a cellular network are shown in accordance with some embodiments;

[0018] Figures 8-9 Exemplary aspects of possible techniques for deactivation and subsequent reactivation of an SCG in an MR-DC cellular communication system are shown in accordance with some embodiments;

[0019] Figure 10 Exemplary aspects of possible techniques for activating a secondary carrier according to a carrier aggregation framework are shown in accordance with some embodiments;

[0020] Figure 11 Exemplary aspects of possible techniques for activating a PSCell of an SCG without performing a RACH procedure are shown in accordance with some embodiments;

[0021] Figure 12 Exemplary aspects of possible techniques for activating a PSCell of an SCG without performing a RACH procedure on the SCG, the SCG including support for QCL information for determining PDCCH DMRS, are shown in accordance with some embodiments;

[0022] Figure 13 Exemplary aspects of possible techniques for activating a PSCell of an SCG without performing a RACH procedure on the SCG, the SCG including mechanisms for faster recovery from PDCCH failure in case such a scenario occurs, are shown in accordance with some embodiments; and

[0023] Figure 14 Exemplary aspects of possible techniques for activating a PSCell of an SCG without first performing a RACH procedure on the SCG, the SCG including mechanisms for later performing a RACH procedure if necessary to facilitate recovery from PDCCH failure, are shown in accordance with some embodiments.

[0024] While the features described herein are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed but to cover all modifications, equivalents and alternatives falling within the spirit and scope of the subject matter as defined by the appended claims. DETAILED DESCRIPTION

[0025] Acronyms

[0026] Various acronyms are used throughout this disclosure. Definitions of the most prominent acronyms used throughout this disclosure can appear as follows:

[0027] • UE: user equipment

[0028] • RF: radio frequency

[0029] • BS: base station

[0030] • GSM: global system for mobile communications

[0031] • UMTS: universal mobile telecommunications system

[0032] • LTE: long term evolution

[0033] • NR: new radio

[0034] • TX: transmission

[0035] • RX: reception

[0036] • RAT: radio access technology

[0037] • BWP: bandwidth part

[0038] • MCG: master cell group

[0039] • MN: master node

[0040] • SCG: secondary cell group

[0041] • SN: secondary node

[0042] • PCell: primary cell

[0043] • PSCell: primary secondary cell

[0044] • SCell: secondary cell

[0045] • RRC: radio resource control

[0046] • DCI: downlink control information

[0047] • CORESET: Control Resource Set

[0048] •QCL: Quasi-cooperative localization or quasi-cooperative position

[0049] • PDCCH: Physical Downlink Control Channel

[0050] DMRS: Demodulation Reference Signal

[0051] • CSI-RS: Channel State Information Reference Signal

[0052] •SSB: Synchronization Signal Block

[0053] Terms

[0054] The following is a glossary of terms that will appear in this disclosure:

[0055] Memory media—any device of any type of nontransitory memory device or storage device. The term "memory media" is intended to include mounting media such as CD-ROMs, floppy disks, or magnetic tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media, e.g., hard disk drives or optical storage devices; registers or other similar types of memory elements, etc. Memory media may also include other types of nontransitory memory or combinations thereof. Furthermore, memory media may reside in a first computer system executing a program, or may reside in a different second computer system connected to the first computer system via a network such as the Internet. In a later example, the second computer system may provide program instructions to the first computer system for execution. The term "memory media" may include two or more memory media that may reside in different locations on different computer systems connected via a network, for example. Memory media may store program instructions (e.g., representing a computer program) that can be executed by one or more processors.

[0056] Carrier medium—the memory medium as described above, and physical transmission medium, such as buses, networks and / or other physical transmission media for transmitting signals (such as electrical signals, electromagnetic signals or digital signals).

[0057] Computer system (or computer) - any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network appliance, internet appliance, personal digital assistant (PDA), television system, grid

[0058] User equipment (UE) (or "UE device") - any of various types of computer systems or devices that are mobile or portable and that performs wireless communications. Examples of UE devices include mobile telephones or smart phones (for example, iPhone TM , Android TM -based phones), tablets (for example, iPad TM , Samsung Galaxy TM ), portable gaming devices (for example, Nintendo DS TM , PlayStation Portable TM , Gameboy Advance TM , iPhone TM ), wearable devices (for example, smart watches, smart glasses), laptop computers, PDAs, portable Internet devices, music players, data storage devices, other handheld devices, automobiles and / or motor vehicles, unmanned aerial vehicles (UAVs) (for example, drones), UAV controllers (UACs), etc. In general, the term "UE" or "UE device" can be broadly defined to encompass any electronic, computing, and / or telecommunication device (or combination of devices) that a user can readily transport and that is capable of wireless communication.

[0059] Wireless device - any of various types of computer systems or devices that performs wireless communication. A wireless device can be portable (or mobile) or can be stationary or fixed at a location. A UE is one example of a wireless device.

[0060] Communication device - any of various types of computer systems or devices that performs communication, which can be wired or wireless. A communication device can be portable (or mobile) or can be stationary or fixed at a location. A wireless device is one example of a communication device. A UE is another example of a communication device.

[0061] Base station (BS) - the term "base station" has the full breadth of its ordinary meaning and at least includes a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system.

[0062] processing element (or processor)—refers to various elements or combinations of elements that are capable of performing a function in a device, such as a user equipment device or a cellular network device. Processing elements can include, for example, a processor and associated memory, parts of individual processor cores or circuits, entire processor cores, processor arrays, circuits such as an ASIC (application specific integrated circuit), programmable hardware elements such as an FPGA (field programmable gate array), and any of various combinations thereof.

[0063] Wi-Fi—The term “Wi-Fi” has the full breadth of its ordinary meaning and at least includes a wireless communication network or RAT that provides services using wireless LAN (WLAN) access points and that provides connectivity to the Internet through these access points. Most modern Wi-Fi networks (or WLAN networks) are based on IEEE 802.11 standards and marketed under the name “Wi-Fi.” Wi-Fi (WLAN) networks are distinct from cellular networks.

[0064] automatically—refers to an action or operation being performed by a computer system (e.g., software executed by the computer system) or device (e.g., circuitry, programmable hardware elements, ASIC, etc.), without user input directly specifying or performing the action or operation. Thus the term “automatically” is in contrast to “manually,” where the action or operation is performed by the user, and “automatically” is in contrast to scenarios where a user would have to specifically initiate or directly select each action or operation. An automatic process may

[0065] Configured To - Various components can be described as being "configured to" perform one or more tasks. In such contexts, "configured to" is a broad recitation of structure generally meaning "having structure that" performs the one or more tasks during operation. As such, a component can be configured to perform one or more tasks even when the component is not currently on or performing such tasks (e.g., a group of electrical conductors can be configured to electrically connect a module to another module even when the two modules are not connected). In some contexts, "configured to" can be described as a broad recitation of structure generally meaning "having circuitry that" performs one or more tasks during operation. As such, a component can be configured to perform one or more tasks even when the component is not currently on or performing such tasks. In general, the circuitry forming the structure corresponding to "configured to" can include hardware circuitry.

[0066] For ease of description, various components can be described as performing one or more tasks. Such descriptions should be interpreted as including the phrase "configured to." A component that is configured to perform one or more tasks is expressly intended to invoke the interpretation of that component not invoking the interpretation of Section 112, Paragraph 6 of the U.S. Code Title 35.

[0067] Figure 1 and Figure 2 - Exemplary Communication System

[0068] Figure 1 An example (and simplified) wireless communication system in which aspects of the present disclosure can be implemented is illustrated in accordance with some embodiments. Note that Figure 1 The system of FIG. 1 is merely one example of a possible system, and this embodiment can be implemented in any of various systems as desired.

[0069] As shown, the example wireless communication system includes a base station 102, which communicates over a transmission medium with one or more (e.g., any number) of user devices 106A, 106B, etc., through 106N. Each user device can be referred to herein as a "user equipment" (UE) or UE device. Thus, the user devices 106 are referred to as UEs or UE devices.

[0070] The base stations 102 can be transceiver base stations (BTSs) or cell sites, and can include hardware and / or software that enables wireless communication with the UEs 106A through 106N. If implemented in the context of LTE, the base stations 102 can be referred to as “eNodeBs” or “eNBs.” If implemented in the context of 5G NR, the base stations 102 can alternatively be referred to as “gNodeBs” or “gNBs.” The base stations 102 can also be equipped to communicate with the network 100 (e.g., with a core network of a cellular service provider, with a telecommunications network such as a public switched telephone network (PSTN), and / or with the Internet, among various possible networks). Thus, the base stations 102 can facilitate communications between the user devices and / or between user devices and the network 100. The communication areas (or coverage areas) of the base stations can be referred to as “cells.” Also as used herein, with respect to a UE, a base station can be considered to represent the network where it is considered that both uplink and downlink communications of the UE are with the base station. Thus, a UE in communication with one or more base stations in the network can also be understood to be a UE in communication with the network.

[0071] The base stations 102 and user devices can be configured to communicate over transmission media using any of a variety of radio access technologies (RATs), also referred to as wireless communication technologies or telecommunication standards, such as GSM, UMTS (WCDMA), LTE, LTE-Advanced (LTE-A), LAA / LTE-U, 5G NR, 3GPP2, CDMA2000 (e.g., lxRTT, lxEV-DO, HRPD, eHRPD), Wi-Fi, and so on.

[0072] The base stations 102 and other similar base stations operating according to the same or a different cellular communication standard can thus provide service as one or more cell networks that can provide continuous or approximately continuous overlapping service to UEs 106 and similar devices via one or more cellular communication standards over a certain geographic area.

[0073] Note that the UEs 106 are capable of communicating using multiple wireless communication standards. For example, the UEs 106 can be configured to communicate using either or both of a 3GPP cellular communication standard or a 3GPP2 cellular communication standard. In some embodiments, the UEs 106 can be configured to perform techniques for physical downlink control channel processing when activating a secondary cell group in a wireless communication system, such as according to the various methods described herein. The UEs 106 can also or instead be configured to communicate using WLAN, BLUETOOTH TMone or more global navigation satellite systems (GNSS, e.g., GPS or GLONASS), one and / or more mobile television broadcasting standards (e.g., ATSC-M / H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0074] Figure 2 An exemplary user equipment 106 (e.g., one of devices 106A-106N) is shown in communication with base station 102, in accordance with some embodiments. UE 106 can be a device with wireless network connectivity, such as a mobile phone, a handheld device, a wearable device, a computer or tablet, an unmanned aerial vehicle (UAV), an unmanned aerial controller (UAC), a car, or almost any type of wireless device. UE 106 can include a processor (processing element) configured to execute program instructions stored in memory. The UE 106 can perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or additionally, the UE 106 can include a programmable hardware element such as an FPGA (field programmable gate array), an integrated circuit, and / or any of various other programmable hardware elements, configured to perform any of the method embodiments described herein, or any portion thereof. The UE 106 can be configured to communicate using any of multiple wireless communication protocols. For example, the UE 106 can be configured to communicate using two or more of CDMA2000, LTE, LTE-A, 5G NR, WLAN, or GNSS. Other combinations of wireless communication standards are also possible.

[0075] The UE 106 can include one or more antennas that use one or more wireless communication protocols for communication in accordance with one or more RAT standards. In some embodiments, the UE 106 can share one or more portions of receive chains and / or transmit chains between multiple wireless communication standards. The shared radio can include a single antenna, or can include multiple antennas for performing wireless communication (e.g., for MIMO). In general, the radio can include any combination of baseband processors, analog radio frequency (RF) signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc.), or digital processing circuitry (e.g., for digital modulation and other digital processing). Similarly, the radio can implement one or more receive chains and transmit chains using the aforementioned hardware.

[0076] In some embodiments, the UE 106 can include separate transmit and / or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As another possibility, the UE 106 can include one or more radio components that are shared among multiple wireless communication protocols, as well as one or more radio components that are used exclusively by a single wireless communication protocol. For example, the UE 106 can include shared radio components for communicating using either of LTE or CDMA2000 lxRTT (or LTE or NR, or LTE or GSM), as well as separate radio components for communicating using each of Wi-Fi and BLUETOOTH®. Other configurations are also possible. TM

[0077] Figure 3 Block diagram of an exemplary UE device

[0078] Figure 3 A block diagram illustrating an example UE 106, in accordance with some embodiments, is shown. As shown, the UE 106 can include a system on chip (SOC) 300, which can include portions for various purposes. For example, as shown, the SOC 300 can include a processor 302, which can execute program instructions for the UE 106, and a display circuit 304, which can perform graphics processing and provide display signals to a display 360. The SOC 300 can also include a sensor circuit 370, which can include components to sense or measure any of a variety of possible characteristics or parameters of the UE 106. For example, the sensor circuit 370 can include motion sensing circuitry configured to detect motion of the UE 106, e.g., using any of a gyroscope, an accelerometer, and / or various other motion sensing components. As another possibility, the sensor circuit 370 can include one or more temperature sensing components, e.g., to measure a temperature of each of one or more antenna panels and / or other components of the UE 106. Any of a variety of other possible types of sensor circuitry can also or alternatively be included in the UE 106, as desired. The processor 302 can also be coupled to a memory management unit (MMU) 340, which can be configured to receive addresses from the processor 302 and translate those addresses to locations in memory (e.g., a memory 306, a read only memory (ROM) 350, a NAND flash memory 310), and / or to other circuitry or devices, such as the display circuit 304, the radio 330, the connector I / F 320, and / or the display 360. The MMU 340 can be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU 340 can be included as a part of the processor 302.

[0079] ​As shown, SOC 300 can be coupled to various other circuitries of the UE 106. For example, the UE 106 can include various types of memory, including NAND flash 310, a connector interface 320 (e.g., for coupling to a computer system, docking station, charging station, etc.), a display 360, and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR, CDMA2000, BLUETOOTH TM , Wi-Fi, GPS, etc.). The UE device 106 can include at least one antenna, such as antenna 335a, and possibly multiple antennas, such as shown by antennas 335a and 335b, for performing wireless communication with base stations and / or other devices. Antennas 335a and 335b are shown by way of example, and the UE device 106 can include fewer or more antennas. Collectively, the antenna or antennas are referred to as antenna 335. For example, the UE device 106 can perform wireless communication using the antenna 335 by way of the radio circuitry 330. As described above, in some embodiments, the UE can be configured to use multiple wireless communication standards for wireless communication.

[0080] The UE 106 can include hardware and software components for implementing methods of the UE 106 to perform techniques for physical downlink control channel processing when activating a secondary cell group in a wireless communication system, such as further described later herein. The processor 302 of the UE device 106 can be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, the processor 302 can be configured as a programmable hardware component(s), such as an FPGA (field-programmable gate array), or as an ASIC (application-specific integrated circuit). Additionally, processor 302 can be coupled to, and / or can interact with, other components as shown in FIG. 3 and / or as described herein, for performing techniques for physical downlink control channel processing when activating a secondary cell group in a wireless communication system in accordance with various embodiments disclosed herein. The processor 302 can also implement various other applications and / or end user applications running on the UE 106. Figure 3

[0081] In some embodiments, the radio 330 can include separate controllers that are dedicated to controlling communication for various respective RAT standards. For example, as shown in FIG. 3, the radio 330 can include a Wi-Fi controller 352, a cellular controller (e.g., an LTE and / or LTE-A controller) 354, and a BLUETOOTH Figure 3 controller 356. In other embodiments, the radio 330 can include one or more universal TM ​Controller 356, and in at least some embodiments, one or more of these controllers may be implemented as corresponding integrated circuits (referred to as ICs or chips), which communicate with each other and with the SOC 300 (more specifically with the processor 302). For example, Wi-Fi controller 352 may communicate with cellular controller 354 via a cell-ISM link or WCI interface, and / or BLUETOOTH TM Controller 356 can communicate with cellular controller 354 via a cell-ISM link or the like. Although three separate controllers are shown within radio component 330, other implementations with fewer or more similar controllers for various different RATs can be implemented in UE device 106.

[0082] Furthermore, implementation schemes in which the controller can perform functions associated with various radio access technologies are envisioned. For example, according to some implementation schemes, in addition to hardware and / or software components for performing cellular communications, the cellular controller 354 may also include hardware and / or software components for performing one or more activities associated with Wi-Fi, such as Wi-Fi preamble detection, and / or the generation and transmission of Wi-Fi physical layer preamble signals.

[0083] Figure 4 Block diagram of an exemplary base station

[0084] Figure 4 A block diagram of an exemplary base station 102 according to some implementation schemes is shown. It should be noted that... Figure 4 The base station shown is merely one example of a possible base station. As illustrated, base station 102 may include a processor 404 capable of executing program instructions specific to base station 102. Processor 404 may also be coupled to a memory management unit (MMU) 440 or other circuitry or device, which may be configured to receive addresses from processor 404 and translate those addresses into locations in memory (e.g., memory 460 and read-only memory (ROM) 450).

[0085] Base station 102 may include at least one network port 470. Network port 470 may be configured to be coupled to a telephone network and provide access rights as described above. Figure 1 and Figure 2The telephone network described in the middle of the multiple devices such as UE device 106. Network port 470 (or additional network ports) can also be configured to or alternatively configured to be coupled to a cellular network, for example, a core network of a cellular service provider. The core network can provide mobility-related services and / or other services to multiple devices such as UE device 106. In some cases, network port 470 can be coupled to the telephone network via the core network, and / or the core network can provide the telephone network (e.g., among other UE devices served by the cellular service provider).

[0086] The base station 102 can include at least one antenna 434, and possibly multiple antennas. The one or more antennas 434 can be configured to operate as a wireless transceiver and can be further configured to communicate with UE devices 106 via radio 430. Antenna 434 communicates with radio 430 via communication chain 432. Communication chain 432 can be a receive chain, a transmit chain, or both. Radio 430 can be designed to communicate via various radio signaling standards including, but not limited to, NR, LTE, LTE-A WCDMA, CDMA2000, etc. Processor 404 of base station 102 can be configured to implement and / or support implementation of a part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, processor 404 can be configured as a programmable hardware element(s), such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. In the case of certain RATs (e.g., Wi-Fi), base station 102 can be designed to be an access point (AP), in which case network port 470 can be implemented to provide access to a wide area network and / or one or more local area networks, e.g., it can include at least one Ethernet port and radio 430 can be designed to communicate according to Wi-Fi standards.

[0087] Reference signal

[0088] Wireless devices, such as user equipment, can be configured to perform various tasks that include using reference signals (RSs) provided by one or more cellular base stations. For example, initial access and beam measurements of a wireless device can be performed based at least in part on synchronization signal blocks (SSBs) provided by one or more cells provided by one or more cellular base stations within a communication range of the wireless device. Another type of reference signal that is commonly provided in cellular communication systems can include channel state information (CSI) RSs. Various types of CSI-RSs can be provided for tracking (e.g., for time and frequency offset tracking), beam management (e.g., CSI-RSs configured with repetitions to help determine one or more beams for uplink and / or downlink communications), and / or channel measurement (e.g., CSI-RSs configured in a resource set for measuring a quality of a downlink channel and reporting information related to the quality measurement to a base station), among various possibilities. For example, in the case of CSI-RSs for CSI acquisition, a UE can periodically perform channel measurements and transmit channel state information (CSI) to a BS. The base station can then receive and use the channel state information to determine adjustments to various parameters during communications with the wireless device. In particular, the BS can use the received channel state information to adjust coding of its downlink transmissions to improve downlink channel quality.

[0089] In many cellular communication systems, a base station can periodically transmit some or all of such reference signals (or pilot signals), such as SSBs and / or CSI-RSs. In some cases, aperiodic reference signals can also or alternatively be provided (e.g., for aperiodic CSI reporting).

[0090] As a detailed example, in accordance with at least some embodiments, in the 3GPP NR cellular communication standard, channel state information that a UE feeds back based on CSI-RSs for CSI acquisition can include one or more of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), a CSI-RS resource indicator (CRI), an SSBRI (SS / PBCH resource block indicator), and a layer indicator (LI).

[0091] Channel quality information can be provided to a base station for link adaptation, e.g., for providing guidance on which modulation and coding scheme (MCS) the base station should use when transmitting data. For example, when the downlink channel communication quality between the base station and the UE is determined to be high, the UE can feed back a high CQI value, which can cause the base station to transmit data using a relatively high modulation order and / or a low channel coding rate. As another example, when the downlink channel communication quality between the base station and the UE is determined to be low, the UE can feed back a low CQI value, which can cause the base station to transmit data using a relatively low modulation order and / or a high channel coding rate.

[0092] PMI feedback can include preferred precoding matrix information and can be provided to the base station to indicate which MIMO precoding scheme the base station should use. In other words, the UE can measure the quality of the downlink MIMO channel between the base station and the UE based on pilot signals received over the channel and can recommend through the PMI feedback which MIMO precoding the base station should apply. In some cellular systems, the PMI is configured in a matrix form that provides linear MIMO precoding. The base station and the UE can share a codebook consisting of a plurality of precoding matrices, where each MIMO precoding matrix in the codebook can have a unique index. Thus, as part of the channel state information fed back by the UE, the PMI can include an index (or possibly multiple indices) corresponding to the most preferred MIMO precoding matrix (or matrices) in the codebook. This can enable the UE to minimize the amount of feedback information. Thus, according to at least some embodiments, the PMI can indicate which precoding matrix from the codebook should be used for transmissions to the UE.

[0093] For example, when the base station and the UE have multiple antennas, rank indicator information (RI feedback) can indicate the number of transmission layers that the UE determines can be supported by the channel, which can enable multi-layer transmission through spatial multiplexing. The RI and the PMI can collectively allow the base station to know which precoding to apply to which layer, for example, depending on the number of transmission layers.

[0094] In some cellular systems, the PMI codebook is defined according to the number of transmission layers. In other words, for R-layer transmission, N t ×R matrices can be defined (e.g., where R represents the number of layers, N t represents the number of transmitter antenna ports, and N represents the size of the codebook). In such a scenario, the number of transmission layers (R) can conform to the rank value of the precoding matrix (N t ×R matrix), and thus R can be referred to as a "rank indicator (RI)" in this context.

[0095] Accordingly, channel state information can include an assigned rank (e.g., a rank indicator or RI). For example, a MIMO-capable UE in communication with a BS can include four receiver chains, e.g., can include four antennas. The BS can also include four or more antennas to enable MIMO communication (e.g., 4x4 MIMO). Accordingly, the UE can be capable of simultaneously receiving up to four (or more) signals (e.g., layers) from the BS. A layer-to-antenna mapping can be applied, e.g., each layer can be mapped to any number of antenna ports (e.g., antennas). Each antenna port can transmit and / or receive information associated with one or more layers. A rank can include a number of bits and can indicate a number of signals that the BS can transmit to the UE in an upcoming time period (e.g., during an upcoming transmission time interval or TTI). For example, an indication of rank 4 can indicate that the BS will transmit 4 signals to the UE. As one possibility, the length of the RI can be two bits (e.g., since two bits are sufficient to distinguish between 4 different rank values). Note that other numbers and / or configurations of antennas (e.g., at either or both of the UE or the BS) and / or other numbers of data layers are also possible according to various embodiments.

[0096] Figure 5 - Physical downlink control channel processing when activating a secondary cell group

[0097] Cellular communication technology has been developed to include the possibility of carrier aggregation (e.g., where multiple carriers are provided to a wireless device by a cellular base station, typically as a primary cell and one or more secondary cells), and further to include the possibility of dual connectivity (e.g., where a wireless device can form wireless links with base stations operating according to multiple different RATs and / or multiple base stations, typically as a primary cell group and one or more secondary cell groups). As part of the development of such technology, it can be an important consideration to provide a flexible and efficient framework for activating and deactivating secondary cell groups.

[0098] At least according to some embodiments, one possible aspect of such a framework can include how to handle the initial setup of a secondary cell group that is being activated, e.g., including how to acquire channel estimation information to facilitate successful reception of an initial downlink control communication, e.g., a physical downlink control channel reception, on the secondary cell group.

[0099] Accordingly, it can be beneficial to specify techniques for physical downlink control channel processing when activating a secondary cell group. To illustrate one set of such possible techniques, Figure 5 is a flow diagram illustrating aspects of a method for physical downlink control channel processing when activating a secondary cell group in a wireless communication system, at least according to some embodiments.

[0100] Figure 5Aspects of the methods of FIG. 1 can be implemented by a wireless device, e.g., in connection with one or more cellular base stations such as the UEs 106 and BSs 102 shown and described with respect to the various figures herein, or more generally in connection with any of the computer circuitry, systems, devices, elements, or components, etc. shown in the above-referenced figures, as desired. For example, a processor (and / or other hardware) of such a device can be configured to cause the device to perform any combination of the method elements shown and / or other method elements.

[0101] Note that while at least some elements of the methods of FIG. 1 are described using terminology related to the use of communication techniques and / or features associated with 3GPP and / or NR specification documents, such description is not intended to limit the present disclosure, and aspects of the methods of FIG. 1 can be used in any suitable wireless communication system, as desired. In various embodiments, some of the elements of the methods shown can be performed concurrently, in different orders that are not shown, can be substituted for other method elements, or can be omitted entirely depending on the design of the method in question. Additional method elements can also be performed as desired. As shown, the methods of FIG. 1 can operate as follows. Figure 5 Figure 5 Note that while at least some elements of the methods of FIG. 1 are described using terminology related to the use of communication techniques and / or features associated with 3GPP and / or NR specification documents, such description is not intended to limit the present disclosure, and aspects of the methods of FIG. 1 can be used in any suitable wireless communication system, as desired. In various embodiments, some of the elements of the methods shown can be performed concurrently, in different orders that are not shown, can be substituted for other method elements, or can be omitted entirely depending on the design of the method in question. Additional method elements can also be performed as desired. As shown, the methods of FIG. 1 can operate as follows. Figure 5

[0102] A wireless device can establish a wireless link with a cellular base station. According to some embodiments, the wireless link can comprise a cellular link according to 5G NR. For example, the wireless device can establish a session with an AMF entity of a cellular network through one or more gNBs that provide radio access to the cellular network. As another possibility, the wireless link can comprise a cellular link according to LTE. For example, the wireless device can establish a session with a mobility management entity of a cellular network through an eNB that provides radio access to the cellular network. According to various embodiments, other types of cellular links are also possible, and the cellular network can also or alternatively operate according to another cellular communication technology (e.g., UMTS, CDMA2000, GSM, etc.).

[0103] ​​Establishing the wireless link can include establishing, in accordance with some embodiments, a radio resource control (RRC) connection with the serving cellular base station. Establishing the first RRC connection can include configuring various parameters for communication between the wireless device and the cellular base station, establishing context information for the wireless device, and / or any of various other possible features, e.g., related to establishing an air interface for the wireless device to communicate in cellular communications with a cellular network associated with the cellular base station. After establishing the RRC connection, the wireless device can operate in an RRC connected state. In some instances, the RRC connection can also be released (e.g., after a certain period of inactivity with respect to data communications), in which case the wireless device can operate in an RRC idle state or an RRC inactive state. In some cases, the wireless device can perform a handover (e.g., when in an RRC connected mode) or a cell reselection (e.g., when in an RRC idle mode or an RRC inactive mode) to a new serving cell, e.g., due to wireless device mobility, changes in wireless medium conditions, and / or any of various other possible reasons.

[0104] The cellular base station can provide a master cell group (MCG) for the wireless device. The MCG can also configure a secondary cell group (SCG), which can be provided by a different cellular base station, and which can operate as the MCG according to the same RAT or a different RAT. For example, the MCG can operate according to LTE, while the SCG can operate according to NR, or vice versa, or both the MCG and the SCG can operate according to NR, among various possibilities. The SCG can be configured in a deactivated state, or can be configured in an activated state, and can be later deactivated and possibly reactivated, such as according to techniques described later herein.

[0105] While the SCG is in the deactivated state, the wireless device can perform radio resource management (RRM) on the SCG, e.g., including receiving one or more RRM reference signals, and performing one or more measurements on the RRM reference signals to manage the deactivated link with the SCG. At least in some cases, activity on the deactivated SCG can be limited to such RRM activity; in other words, it can be the case that no downlink or uplink control signaling or data transmissions are performed on the SCG while the SCG is in the deactivated state. In some cases, the wireless device can be configured to perform monitoring and measurements on radio link monitoring (RLM) reference signals and / or beam failure detection (BFD) reference signals as part of the RRM performed while the SCG is in the deactivated state.

[0106] At 502, the wireless device can receive an indication (e.g., from a cellular base station providing the MCG, which can also be referred to herein as a master node or MN) to reactivate the SCG without performing a random access channel (RACH) procedure on the SCG. The indication to reactivate the SCG can be provided by a RRC message or possibly via a medium access control (MAC) control element (CE) or downlink control information (DCI). When the SCG is reactivated, performing a RACH procedure on the SCG can provide a mechanism for configuring various communication parameters for communications between the wireless device and the SCG, but can incur signaling burden and setup delay caused by the RACH procedure. Accordingly, at least according to some embodiments, techniques for reactivating the SCG without performing a random access channel (RACH) procedure can provide the possibility for faster SCG activation and / or less network signaling burden, such as according to Figure 5 the method.

[0107] In some embodiments, additional information related to the reactivation of the SCG can be provided by the MN as part of the message including the indication to reactivate the SCG and / or in one or more other messages. For example, in some cases, an indication of a bandwidth part (BWP) on which to reactivate the SCG can be provided to the wireless device by the MN.

[0108] As another possibility, an indication of quasi co-location (QCL) information for a PDCCH of the SCG can be provided to the wireless device by the MN. The indication of the QCL information for the PDCCH of the SCG can include a list of reference signals for the SCG and an indication of which of the listed reference signals is QCLed with the PDCCH of the SCG (e.g., an index value pointing to one of the listed reference signals), as one option. Such information can be provided together (e.g., all in a single RRC message, which also indicates to reactivate the SCG, as one possibility) or can be provided separately (e.g., the list of reference signals can be provided via RRC signaling, while the index value pointing to one of the listed reference signals to be used as QCL for the PDCCH of the SCG can be provided in a MAC CE, which also indicates to reactivate the SCG, as one possibility). As another possibility, the RRC message including the indication to reactivate the SCG can also explicitly include the reference signal to be used as QCL for the PDCCH of the SCG.

[0109] As yet another possibility, in some cases, the wireless device can be provided, e.g., by the MN, with an indication of one or more RLM parameters configured for reactivating the SCG. Such RLM parameters can include, at least in accordance with some embodiments, one or more timer and / or parameter values that affect how or when to declare a radio link failure (RLF). For example, the RLM parameters can include any of a number of consecutive out-of-sync instances configured to trigger the start of an RLF timer (e.g., the 3GPP N310 parameter), a number of consecutive in-sync instances configured to stop such an RLF timer (e.g., the 3GPP N311 parameter), a length of such an RLF timer (e.g., the 3GPP T310 parameter), and / or various other possible parameters. Such parameters can override any previously configured parameters, and can be used until further reconfiguration, as one possibility. As another possibility, such parameters can be used temporarily (e.g., during SCG reactivation), and the wireless device can be configured to resume use of previously configured RLM parameter values under certain configured or specified conditions. Such “exit conditions” for use of RLM parameters configured for reactivating the SCG can also be configured by the MN (e.g., when providing the indication to reactivate the SCG or in another time / in another message), or can be pre-agreed. Such exit conditions can include any of a configured amount of time and / or number of communication slots elapsing, one or more events occurring, and / or various other possible exit conditions.

[0110] As yet another possibility, in some cases, the wireless device can receive, from the MN, an indication of dedicated SCG RACH resources for use by the wireless device, e.g., with the indication to reactivate the SCG. Such information can be provided, at least in accordance with some embodiments, in cases where PDCCH decoding on the SCG is difficult (e.g., where PDCCH decoding on the SCG is unsuccessful to the extent that RLF is triggered on the SCG), even though SCG reactivation can be configured to be performed without performing a RACH procedure. For example, providing a mechanism for quickly detecting and recovering from potential PDCCH decoding problems under SCG activation can be useful, even though such a mechanism can not be usable during SCG reactivation under normal conditions. If desired, the RACH resources can include beam failure recovery RACH resources.

[0111] At 504, the wireless device can determine quasi co-location (QCL) information for the secondary cell group. The QCL information for the SCG can be determined in any of a variety of possible ways. As one possibility, as previously described, the MN can provide an indication of the QCL information for the SCG, e.g., an indication of a reference signal that is QCL’ed with the PDCCH of a primary secondary cell (PSCell) of the SCG. As another possibility, the wireless device can determine the QCL information for the SCG implicitly. For example, in some embodiments, the MN can not provide an indication of the QCL information for the SCG, in which case the wireless device can determine the QCL information for the SCG implicitly using a configured or specified method. In this case, it can be that the RRM reference signal provided by / for the SCG and monitored by the wireless device upon deactivation of the SCG can be determined implicitly to be QCL’ed with the PDCCH of the PSCell of the SCG. In some cases, the wireless device can determine the QCL information for the SCG based at least in part on the BWP on which the SCG is reactivated. For example, different QCL information can be associated (implicitly or explicitly) with different BWP configurations of the SCG, if desired. Note that the reference signal determined to be QCL’ed with the PDCCH of the SCG can include any of a variety of types of reference signals, e.g., SSB RS or CSI-RS, according to various embodiments. Further, the reference signal determined to be QCL’ed with the PDCCH of the SCG can include RS configured for any of a variety of purposes, e.g., RLM RS, BFD RS, etc.

[0112] At 506, the wireless device can receive downlink communications on the SCG using the determined QCL information for the SCG. The downlink communications received on the SCG can include the PDCCH of the PSCell of the SCG, which can be decoded using a PDCCH demodulation reference signal (DMRS). For example, the PDCCH DMRS can be used in conjunction with the QCL information for the PDCCH to form a channel estimate, which in turn can be used to demodulate and decode the PDCCH. At least in some cases, the QCL information can also be used to determine beam characteristics (e.g., precoding matrix) used to receive the PDCCH DMRS and the PDCCH.

[0113] Note that, if provided, RLM parameters configured for use during SCG activation can be used in connection with reception of downlink communications on the SCG. In particular, the configured RLM parameters can be used to determine whether / when an RLF has occurred. For example, if the wireless device is unable to successfully receive and decode a PDCCH of the SCG, the wireless device can determine, in accordance with the configured RLM parameters, that an RLF has occurred, and can perform a RACH procedure with the SCG, e.g., to attempt to restore the radio link with the SCG. The RACH procedure can include a contention-free RACH procedure, e.g., using dedicated RACH resources configured for the wireless device during SCG reactivation, as previously described herein. Alternatively, the RACH procedure can include a contention-based RACH procedure. In either case, at least according to some embodiments, the wireless device can perform the RACH procedure using wireless device identity information configured for the wireless device by the MN for the SCG, e.g., a cell radio network temporary identifier (C-RNTI) configured for the wireless device by the network with the SCG.

[0114] According to at least some embodiments, if RLM parameters configured for use during SCG activation are provided and those RLM parameters are configured to be temporary, and an exit condition for those RLM parameters is satisfied (e.g., if reception of downlink communications on the SCG is successful and a configured amount of time has elapsed, as one possibility), the wireless device can discard those temporary RLM parameters and resume use of a previously configured or default set of RLM parameters. Note that, if RLM parameters configured for use during SCG activation are provided and those RLM parameters are not configured to be temporary, the wireless device can continue to use those RLM parameters during RLM, e.g., until otherwise configured.

[0115] In some embodiments, it can be possible for the MN to provide the wireless device for configuration with channel feedback for the SCG, e.g., using a physical uplink shared channel (PUSCH) of a primary cell (PCell) (or another cell) of the MCG. For example, the MN can provide an indication to the wireless device to provide channel feedback for the SCG via the MCG. In this case, the wireless device can perform any channel measurements needed to provide the requested channel feedback for the SCG, and can provide the resulting channel feedback for the SCG to the MCG, e.g., via the PUSCH of the MCG. Such information can be provided to a secondary node (SN) that provides the SCG, and can be used for beam configuration (e.g., transmission configuration indicator selection), uplink spatial relation determination, and / or for other communication characteristics of the SCG and the wireless device.

[0116] Thus, according to at least some embodiments, Figure 5The methods of the present disclosure can be used to provide a framework according to which a wireless device can handle PDCCH reception during SCG activation without performing a RACH procedure as part of the SCG activation. Among other possible benefits, at least in some cases, such techniques can reduce SCG activation time, network signaling overhead compared to RACH-based SCG activation techniques.

[0117] Figures 6-14 and additional information

[0118] Figures 6-14 Other aspects that can be used in connection with the methods of the present disclosure are shown if desired. Figure 5 However, it should be noted that the exemplary details shown in Figures 6-14 and described with respect to these figures are not intended to be limiting as a whole to the present disclosure: many variations and alternatives to the details provided below are possible and should be considered within the scope of the present disclosure.

[0119] In many cellular communication systems, a physical downlink control channel (PDCCH) is used to provide control information from a cellular base station to a UE served by the cellular base station. The UE can use search spaces and control resource set (CORESET) configurations, which can be provided in bandwidth part (BWP) configuration information, to decode the PDCCH. The PDCCH can contain demodulation reference signal (DMRS) resources, which can be used by the UE to estimate channel conditions (fading, phase rotation, etc.) based on a known sequence in the DMRS. The UE can then apply the derived channel estimates on the PDCCH physical resource blocks (PRBs) to derive channel (demodulation) modulation symbols, which can then be used to test hypotheses for downlink control information (DCI) carried by the PDCCH.

[0120] To effectively perform channel estimation using the DMRS, it can be the case that the UE also needs the timing / frequency, channel fading, and long-term channel properties of the DMRS, and in the case of a beamformed PDCCH, the precoding matrix properties (e.g., beamforming parameters of the DMRS). Such information can be provided by quasi co-location (QCL) information. For example, another reference signal can be provided that has excellent time and frequency auto-correlation properties (e.g., a synchronization signal), and this signal can be configured to be QCLed with the DMRS. This can allow the UE to obtain the timing / frequency, channel fading, long-term channel properties, and / or precoding matrix properties of the DMRS. Thus, the UE can be able to apply these derived estimates to the DMRS, for example, when the UE can assume that the DMRS is transmitted using the same antenna ports as the reference channel, such that the channel properties (e.g., including fading) are the same between the reference signal and the DMRS.

[0121] At least in some cases, the QCL for the PDCCH DMRS can be provided by a synchronization signal block (SSB) of the serving cell (e.g., a primary synchronization signal (PSS) / secondary synchronization signal (SSS) can provide the necessary synchronization information for reference as well as beam precoding information). As another possibility, in some cases, the QCL can be a dedicated channel state information reference signal (CSI-RS) configured for the UE, in which case the QCL information can be provided to the UE in a CORESET configuration.

[0122] Figure 6 Exemplary aspects of one possible 5G NR frame that can include such signals are shown in accordance with some embodiments. As shown, in the illustrated example, a 5G NR frame can contain 10 1ms subframes. Each subframe (or slot) can include 14 orthogonal frequency division multiplexing (OFDM) symbols and a number of subcarriers that can depend on the total cell bandwidth of the cell and the configured subcarrier spacing. Signals included in the illustrated example slots (i.e., slots 1 and 8) can include at least a PDCCH and a PDCCH DMRS (the PDCCH and PDCCH DMRS can be distributed in an interleaved manner over PDCCH resources in the frequency domain). Each slot can also include time-frequency resources over which a physical downlink shared channel (PDSCH) and a PDSCH DMRS are provided, as well as CSI-RS resources. For certain slots (e.g., for slot 1, in the illustrated scenario), resources for additional signals can also be provided, such as a PSS, a SSS, a physical broadcast channel (PBCH), and a PBCH DMRS. Certain resources can also be set to 0 (e.g., configured as zero-power resources).

[0123] In some cases, dual connectivity for UEs in a cellular communications system can be implemented. This can include establishing wireless links with multiple cell groups, which can include cell groups operating according to different RATs. For example, in various possibilities, a multi-radio dual connectivity (MR-DC) scenario can include E-UTRA-NR dual connectivity (EN-DC), in which one cell group operates according to LTE and the other cell group operates according to NR, or NR-DC operation, in which both cell groups operate according to NR. For such dual connectivity cases, it can be the case that one cell group is considered a master cell group (MCG) and the other cell group is considered a secondary cell group (SCG).

[0124] Figure 7Exemplary aspects of one such possible dual connectivity configuration between a UE and a cellular network are shown in accordance with some embodiments. As shown, in the illustrated example, the UE 702 can have a link with both the MCG 704 and the SCG 706. While such dual connectivity is active, the UE can maintain a control plane connection with both the MCG and the SCG. In the MCG, a primary cell (PCell) can always be activated. In the SCG, a primary secondary cell (PSCell) can always be activated. The UE can always support simultaneous reception and transmission in the MCG and the SCG. For the user plane, for split bearer communication, it can be possible to use transmission via only the primary leg (e.g., the MCG) (e.g., for small data amounts), or to use transmission via both legs (e.g., by both the MCG and the SCG) (e.g., for larger data amounts).

[0125] At least in some cases, it can be possible to configure a SCG but not activate it. For example, a SCG can be configured for a UE initially in a deactivated state, and / or can be activated at one time and later deactivated. When deactivated, in the control plane, it can be the case that there is no uplink on the PSCell, and all secondary cells (Scells) in the SCG are deactivated. There can be no RRC signaling to the UE on the SCG. The UE can still perform radio resource management (RRM), e.g., according to network configuration, and the UE can still be considered to be in an RRC connected state. In the user plane, the UE can not monitor the PDCCH on the PSCell, and can accordingly not receive any uplink assignment or downlink grant on the SCG when the SCG is deactivated.

[0126] At least according to some embodiments, the SCG can be deactivated and activated by RRC messages provided via the MCG. Figures 8-9 Exemplary aspects of possible techniques for such deactivation and subsequent reactivation are shown in accordance with some embodiments. In particular, Figure 8 Aspects of scenarios in which reactivation of the SCG includes use of a random access channel (RACH) procedure are shown, while Figure 9 Aspects of scenarios in which reactivation of the SCG does not include use of a RACH procedure are shown.

[0127] As shown, in Figure 8In an example, in 806, the UE 802 and the MCG 804 can establish an RRC connection with NR-DC, e.g., such that the SCG is also activated. In 808, the MCG 804 can indicate to the UE 802 to deactivate the SCG. In 810, the SCG can be deactivated; upon deactivation, the UE 802 can continue to perform RRM on the deactivated SCG. In 812, the network can move the UE 802 to the SCG activated state. The indication to move the UE 802 to the SCG activated state can indicate to perform a RACH procedure with the SCG, or can implicitly configure that the UE 802 should perform a RACH procedure with the SCG upon reactivation of the SCG. In 814, the UE 802 can perform a RACH procedure on the PSCell of the SCG. In 816, the SCG can be reactivated, and the UE 802 can start monitoring PDCCH on the PSCell.

[0128] In an example, Figure 9 In an example, in 906, the UE 902 and the MCG 904 can establish an RRC connection with NR-DC, e.g., such that the SCG is also activated. In 908, the MCG 904 can indicate to the UE 902 to deactivate the SCG. In 910, the SCG can be deactivated; upon deactivation, the UE 902 can continue to perform RRM on the deactivated SCG. In 912, the network can move the UE 902 to the SCG activated state. The indication to move the UE 902 to the SCG activated state can indicate to skip performing a RACH procedure with the SCG, or can simply not indicate to perform a RACH procedure with the SCG. In 914, the SCG can be reactivated, and the UE 902 can start monitoring PDCCH on the PSCell.

[0129] Figure 10Exemplary aspects showing possible techniques for activating a secondary carrier according to a carrier aggregation framework, e.g., for activating an SCell in addition to a PCell in the same cell group, are shown in accordance with some embodiments. According to the shown framework, the SCell can be activated using the PCell, and once the activation is complete, the UE can be expected to start receiving PDCCH on the SCell to facilitate providing uplink grants and downlink allocations on the PUSCH and PDSCH, respectively. The PCell can still be used by the master cell to control the UE uplink feedback for the SCell using DCI on the PCell. Thus, since the PDCCH on the PCell can still be active when the SCell is deactivated, the PCell can provide an anchoring role in setting up the SCell. This can include the UE reporting SCell channel feedback on the PCell, e.g., based on DCI provided on the PCell PDCCH, which can avoid the possibility that any potential issues with decoding the PDCCH on the SCell can negatively impact the UE’s ability to set up the SCell.

[0130] Figure 11 Exemplary aspects showing possible techniques for activating a PSCell of an SCG without performing a RACH procedure are shown in accordance with some embodiments. Such SCG reactivation, e.g., after a previous deactivation of the SCG, can use similar methods between the PCell of the MCG and the PSCell of the SCG as used between the PCell and SCell in Figure 10 the MCG’s PCell can need very low inter-node coordination for anchoring of the SCG’s PSCell, e.g., for the SCG to be able to request the MCG to trigger DCI for PSCell operation, and for the MCG to relay channel feedback information (etc.) to the SCG with slot timing delay, which can not always be practical, e.g., in case the MCG and SCG are not co-located, and / or for any of various other possible reasons. In addition, such coordination can require: an inter-node interface to communicate control activation as well as support passing feedback information across MCG / SCG annotations; and / or an interface at the MCG / UE in the DCI to interpret PSCell activity via PCell DCI. In case such coordination is not possible and / or to avoid the need for such degree of coordination, another method for configuring appropriate QCL information for the DMRS of the PDCCH, e.g., to support successful decoding of the PSCell PDCCH by the UE, and / or another method for supporting the UE to timely inform the network of any issues encountered by the UE in successfully decoding the PSCell PDCCH can be useful.

[0131] As such a possibility for configuring the QCL information for the DMRS of the PDCCH for the PSCell, the reference signal for the QCL information can be explicitly indicated, or it can be determined by implicit assumption (e.g., can be specified in one or more 3GPP technical specifications or otherwise mutually agreed by the network and the UE).

[0132] In the implicit case, the RRM reference signal measured by the UE at the time of deactivation of the SCG can be used as the QCL reference signal for the DMRS of the PDCCH at the time of activation of the SCG, at least as one possibility.

[0133] If the network wants the UE to use a different reference signal (e.g., other than the RRM RS), the network can explicitly provide this reference signal configuration to the UE, e.g., in the RRC message reactivating the SCG. The RRC message can contain the explicit reference signal, or the RRC message can contain a list of reference signals and an index to the specific reference signal on the list that the UE should use. As another possibility, if the SCG activation is performed based on a MAC CE or DCI, the MAC CE or DCI can indicate the index of the reference signal that the UE should use (e.g., the list or possible reference signals to use can be previously provided to the UE in an RRC message).

[0134] In some cases, it can be possible that the UE is configured to receive a radio link monitoring (RLM) and / or beam failure detection (BFD) reference signal and perform RLM and / or BFD on the SCG, e.g., when the SCG is deactivated, and / or when the SCG is reactivated, as part of the RRM. Thus, in such cases, the RLM or BFD RS can also be configured to the UE as the reference signal to be used as the QCL for the PDCCH DMRS.

[0135] When reactivating the SCG via an RRC message, it can be possible that a bandwidth part (BWP) identifier of the BWP on which the PSCell should be activated is indicated. Similarly, if a MAC CE is used for reactivation, this can also point to a BWP for the PSCell. In some cases, the reference signal configuration for the QCL of the PDCCH DMRS can be BWP-specific, e.g., such that depending on the BWP on which the PSCell reactivation occurs, the reference signal corresponding to the indicated BWP can be used for the QCL reference of the PDCCH DMRS.

[0136] Figure 12Exemplary aspects of possible techniques for activating a PSCell of an SCG without performing a RACH procedure on the SCG, including support for determining QCL information for PDCCH DMRS, are shown in accordance with some embodiments. As shown, a UE 1202 and a master node (MN) 1204 can configure a deactivated SCG. The UE can perform RRM measurements only on the SCG when the SCG is deactivated. In 1208, the MN 1204 can provide RRC reconfiguration information to re-activate the SCG on a secondary node (SN) 1206. The RRC reconfiguration information can configure a QCL reference signal configuration for PDCCH DMRS for the SCG, or if such information is not present, the UE 1202 can determine that the absence of this information implies that the UE 1202 uses an RRM reference signal that is QCL with the PDCCH DMRS. When performing PDCCH channel estimation using the PDCCH DMRS, the UE 1202 can accordingly use the indicated QCL reference signal (explicitly or implicitly). In 1210, the UE 1202 can provide an RRC reconfiguration complete indication to the MN 1204, and can consider the SCG re-activated. In 1212, the UE 1202 and the SN 1206 can perform communications via the SCG.

[0137] As previously described herein, in at least some cases, it can also be important to provide techniques for fast recovery from PDCCH decoding problems in the case of RACH-less SCG activation. As one possibility, such techniques can include mechanisms to accelerate RLM and / or BFD, e.g., so that the UE can report any detected problems using a RACH procedure, and accordingly resolve detected problems more quickly. Figure 13 Exemplary aspects of possible techniques for activating a PSCell of an SCG without performing a RACH procedure on the SCG, including mechanisms for faster recovery from PDCCH failure in the event such a scenario occurs, are shown in accordance with some embodiments.

[0138] As shown, in the illustrated scenario, UE 1302 and MN 1304 can configure a deactivated SCG. The UE can perform RRM measurements only on the SCG when the SCG is deactivated. RLM / BFD measurements can be configured as part of the RRM measurements. In 1308, MN 1304 can provide RRC reconfiguration information to re-activate the SCG on SN 1306. The RRC reconfiguration information provided as part of the SCG re-activation can contain RLM configuration information. UE 1302 can use the provided RLM configuration accordingly to detect PDCCH decoding on the SCG. In 1310, UE 1302 can provide an RRC reconfiguration complete indication to MN 1304 and can consider the SCG re-activated. In 1312, UE 1302 and SN 1306 can perform communications via the SCG.

[0139] RLM parameters indicated for use as part of SCG re-activation can contain parameters such as T310, N310, N311, etc. (e.g., as can be defined in 3GPP technical specifications) and various possibilities. For example, the parameters can include one or more timer values and / or threshold numbers of synchronization and out-of-sync instances for determining whether / when a radio link failure (RLF) occurs. The configured RLM parameters can override any previously configured such parameter values, or can be used only temporarily (e.g., for the SCG re-activation time), with an exit condition specified or configured for cases where the UE considers the temporary parameters no longer valid, or the UE implicitly discards the temporary parameters after a pre-agreed amount of time (e.g., amount of time in ms, number of slots, etc.). At least in some cases, the RLM parameters configured for SCG re-activation can be selected to trigger a failure more quickly in cases where the UE has issues decoding PDCCH of the SCG (e.g., lower timer values, lower threshold numbers of out-of-sync instances configured to trigger a timer start, etc.).

[0140] It can also or alternatively be useful, at least according to some embodiments, to provide the UE, if needed, support to perform a RACH procedure on the SCG (e.g., in cases where PDCCH on the PSCell is difficult to decode), even if the SCG re-activation does not initially include a RACH procedure on the SCG. Figure 14 An example aspect is shown illustrating possible techniques for activating a PSCell of an SCG without first performing a RACH procedure on the SCG, the SCG including a mechanism for later performing a RACH procedure if necessary to facilitate recovery from PDCCH failure, according to some embodiments.

[0141] As shown, in the illustrated scenario, the UE 1402 and the MN 1404 can configure a deactivated SCG. The UE can perform RRM measurements on the SCG only when the SCG is deactivated. RLM / BFD measurements can be configured as part of the RRM measurements. In 1408, the MN 1404 can provide RRC reconfiguration information to re-activate the SCG on the SN 1406. The RRC reconfiguration information provided as part of the SCG re-activation can contain RLM configuration information. The UE 1402 can use the provided RLM configuration accordingly to detect PDCCH decoding on the SCG. SCG re-activation specific timers / parameters can be used for RLM. In 1410, the UE 1402 can provide an RRC reconfiguration complete indication to the MN 1304 and can consider the SCG re-activation. However, an RLF can occur during the SCG re-activation, e.g., according to the SCG re-activation specific RLM parameters. Accordingly, in 1412, the UE 1402 and the SN 1406 can perform a RACH procedure on the SCG using a C-RNTI of the UE 1402 configured by the network for the SCG. In some embodiments, the RACH procedure can be performed on dedicated RACH resources provided to the UE 1402 as part of the RRC message re-activating the SCG, such that the UE 1402 can use a contention-free RACH procedure. If desired, the RACH resources can be beam failure recovery RACH resources provided for the UE 1402. As another possibility, the UE 1402 can perform the RACH procedure using a contention-based procedure. In such a scenario, the UE 1402 can still use the C-RNTI configured by the network for the SCG.

[0142] According to some embodiments, it can be useful to support PUSCH-based channel state information (CSI) reporting for a PSCell on a PCell in connection with SCG activation. For example, during PSCell activation, a UE can perform layer 1 (L1) measurements to obtain beam information about the target PSCell. The L1 measurements of CSI or L1-RSRP can be based on SSBs or CSI-RSs of the target activated PSCell. The L1 measurements can be aperiodic or semi-persistent or periodic. The UE can report the L1 measurement results on the PCell PUSCH or a PUSCH of another active serving cell. The L1 measurement reporting can also be aperiodic or semi-persistent or periodic. The L1 measurements and reporting can be triggered by the network. At least according to some embodiments, such measurements and reporting can be useful in order to convey beam information from the UE to the network for TCI and uplink spatial relation determination for the PSCell of the SCG.

[0143] In the following, further exemplary embodiments are provided.

[0144] One set of embodiments can include an apparatus comprising: a processor configured to cause a wireless device to establish a wireless link with a cellular base station, the cellular base station providing a master cell group (MCG) for the wireless device; receive information configuring a secondary cell group (SCG); receive an indication to activate the SCG without performing a random access channel (RACH) procedure on the SCG; determine quasi co-location (QCL) information for a physical downlink control channel (PDCCH) of the SCG; and perform PDCCH decoding of the PDCCH of the SCG based at least in part on the determined QCL information for the PDCCH of the SCG.

[0145] According to some embodiments, the processor is further configured to cause the wireless device to: perform radio resource management (RRM) using an RRM reference signal provided by the SCG when the SCG is in a deactivated state; and determine that the RRM reference signal is QCLed with the PDCCH of the SCG.

[0146] According to some embodiments, the processor is further configured to cause the wireless device to: receive an indication of QCL information for the PDCCH of the SCG from a cellular base station, the cellular base station providing the MCG for the wireless device.

[0147] According to some embodiments, the indication of the QCL information for the PDCCH of the SCG is included in a radio resource control message, the radio resource control message further including the indication to activate the SCG without performing a RACH procedure on the SCG.

[0148] According to some embodiments, the indication of the QCL information for the PDCCH of the SCG includes a list of reference signals and an index to a reference signal from the list of reference signals that is QCLed with the PDCCH of the SCG.

[0149] According to some embodiments, a radio link monitoring (RLM) reference signal provided for the SCG is determined to be QCLed with the PDCCH of the SCG.

[0150] According to some embodiments, a beam failure detection (BFD) reference signal provided for the SCG is determined to be QCLed with the PDCCH of the SCG.

[0151] Another set of embodiments can include a wireless device comprising: an antenna; a radio operably coupled to the antenna; and a processor operably coupled to the radio; wherein the wireless device is configured to: establish a wireless link with a cellular base station that provides a master cell group (MCG) for the wireless device; receive information configuring a secondary cell group (SCG) in a deactivated state; receive an indication to reactivate the SCG without performing a random access channel (RACH) procedure on the SCG; determine quasi co-location (QCL) information for a physical downlink control channel (PDCCH) of the SCG; and perform PDCCH decoding of the PDCCH of the SCG based at least in part on the determined QCL information for the PDCCH of the SCG.

[0152] According to some embodiments, the wireless device is further configured to: receive an indication of a bandwidth part (BWP) on which to reactivate the SCG.

[0153] According to some embodiments, the QCL information for the PDCCH of the SCG is determined based at least in part on the indication of the BWP on which to reactivate the SCG.

[0154] According to some embodiments, the wireless device is further configured to: receive an indication configuring one or more radio link monitoring (RLM) parameters for reactivating the SCG.

[0155] According to some embodiments, the wireless device is further configured to: receive an indication of one or more exit conditions for using the one or more RLM parameters configured for reactivating the SCG.

[0156] According to some embodiments, the wireless device is further configured to: determine that the PDCCH decoding of the PDCCH of the SCG is unsuccessful; and perform a RACH procedure on the SCG based at least in part on determining that the PDCCH decoding of the PDCCH of the SCG is unsuccessful, wherein the RACH procedure is performed on the SCG using a cell radio network temporary identifier (C-RNTI) configured for the SCG.

[0157] According to some embodiments, the indication to reactivate the SCG configures dedicated RACH resources, wherein the RACH procedure is a contention-free RACH procedure performed using the dedicated RACH resources configured by the indication to reactivate the SCG.

[0158] According to some embodiments, the wireless device is further configured to: receive, from the MCG, an indication to provide channel feedback for the SCG to the MCG; perform one or more channel measurements for the SCG; and provide channel feedback for the SCG to the MCG, wherein the channel feedback is determined based at least in part on the one or more channel measurements for the SCG, wherein the channel feedback for the SCG is provided to the MCG using a physical uplink shared channel (PUSCH) for the MCG.

[0159] Yet another set of embodiments can include a cellular base station comprising: an antenna; a radio operably coupled to the antenna; and a processor operably coupled to the radio; wherein the first cellular base station is configured to: establish a wireless link with a wireless device, wherein the cellular base station provides a master cell group (MCG) for the wireless device; provide information to the wireless device to configure a secondary cell group (SCG) in a deactivated state; and provide an indication to the wireless device to reactivate the SCG without performing a random access channel (RACH) procedure on the SCG, wherein the indication to reactivate the SCG comprises an indication of quasi co-location (QCL) information for a physical downlink control channel (PDCCH) for the SCG.

[0160] According to some embodiments, the cellular base station is further configured to: provide an indication to the wireless device of a bandwidth part (BWP) on which to reactivate the SCG.

[0161] According to some embodiments, the cellular base station is further configured to: provide an indication to configure one or more radio link monitoring (RLM) parameters for reactivating the SCG.

[0162] According to some embodiments, the cellular base station is further configured to: configure a dedicated RACH resource for the wireless device of the SCG, wherein the dedicated RACH resource is configured to be used if PDCCH decoding for the SCG is unsuccessful.

[0163] According to some embodiments, the cellular base station is further configured to: provide an indication to the wireless device to provide channel feedback for the SCG; receive channel feedback for the SCG from the wireless device, wherein the channel feedback for the SCG is received using a physical uplink shared channel (PUSCH); and provide the channel feedback for the SCG received from the wireless device to the SCG.

[0164] Yet another example embodiment can include a method comprising: performing, by a wireless device, any or all parts of the preceding examples.

[0165] Another example implementation can include an apparatus comprising: an antenna; a radio coupled to the antenna; and a processing element operably coupled to the radio, wherein the apparatus is configured to implement any or all portions of any of the preceding examples.

[0166] Another set of example implementations can include a non-transitory computer- accessible memory medium comprising program instructions that, when executed at an apparatus, cause the apparatus to implement any or all portions of any of the preceding examples.

[0167] Another set of example implementations can include a computer program comprising instructions for performing any or all portions of any of the preceding examples.

[0168] Another set of example implementations can include an apparatus comprising means for performing any or all portions of any of the preceding examples.

[0169] Another set of example implementations can include an apparatus comprising a processing element configured to cause a wireless device to perform any or all portions of any of the preceding examples.

[0170] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled in a way to minimize risk of unintentional or unauthorized access or use of data, and every individual interacting with the system should be clearly made aware of the nature of the data being collected and the uses expected.

[0171] Any of the methods described herein for operating a user equipment (UE) can be the basis for a corresponding method for operating a base station by interpreting each message / signal X received by the UE in the downlink as a message / signal X transmitted by the base station, and interpreting each message / signal Y transmitted by the UE in the uplink as a message / signal Y received by the base station.

[0172] Embodiments of the disclosure can be implemented in any of various forms. For example, in some embodiments, the subject matter can be implemented as a computer-implemented method, a computer-readable memory medium, or a computer system. In other embodiments, the subject matter can be implemented using one or more custom-designed hardware devices such as ASICs. In other embodiments, the subject matter can be implemented using one or more programmable hardware elements such as FPGAs.

[0173] In some embodiments, a non-transitory computer-readable storage medium (e.g., a non-transitory memory element) can be configured to have stored thereon program instructions and / or data, wherein if the program instructions are executed by a computer system, the computer system is caused to perform a method, such as any of the method embodiments described herein, or any combination of method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets.

[0174] In some embodiments, a device (e.g., a UE) can be configured to include a processor (or a set of processors) and a memory medium (or memory element), where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or any combination of method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets). The device can be implemented in any of a variety of forms.

[0175] Although the above embodiments have been described in considerable detail, variations and modifications are possible to those skilled in the art once they fully understand the basic principles under lying the above disclosure. The disclosure is intended to cover any and all such variations and modifications.

Claims

1. A method for wireless communication, comprising: By wireless devices: A wireless link is established with a cellular base station, which provides the wireless device with a primary cell group (MCG). An additional radio link is established with a second cellular base station, which provides a secondary cell group (SCG) for the radio device, wherein the SCG includes primary and secondary cells (PSCells). Receive instruction to deactivate SCG; Receive radio link monitoring (RLM) or beam fault detection (BFD) reference signals to perform RLM or BFD on the SCG when the SCG is deactivated; Receive additional instructions to activate the SCG without performing the Random Access Channel (RACH) procedure on the SCG; The quasi-co-address QCL information for the Physical Downlink Control Channel (PDCCH) of the SCG is determined using at least one of the RLM or BFD reference signals. as well as PDCCH decoding of the PDCCH for the SCG is performed at least in part based on the determined QCL information of the PDCCH for the SCG.

2. The method according to claim 1, further comprising: Supplemental instructions to receive the QCL information of the PDCCH for the SCG from the cellular base station providing the MCG for the wireless device.

3. The method according to claim 2, The supplementary indication for the QCL information of the PDCCH of the SCG is included in the radio resource control message, which also includes the additional indication to activate the SCG without performing the RACH procedure on the SCG.

4. The method according to claim 2, The supplementary indication for the QCL information of the PDCCH of the SCG includes a reference signal list and an index of the reference signal in the reference signal list that is a QCL of the PDCCH of the SCG.

5. The method according to claim 1, The RLM reference signal provided for the SCG is determined to be QCL with the PDCCH of the SCG.

6. The method according to claim 1, The BFD reference signal provided for the SCG is determined to be QCL with the PDCCH of the SCG.

7. A method for wireless communication, comprising: By cellular base stations: A wireless link is established with a wireless device, wherein the cellular base station provides a primary cell group (MCG) for the wireless device, wherein the wireless device has an additional wireless link established with a second cellular base station, the second cellular base station providing a secondary cell group (SCG) for the wireless device, wherein the SCG includes primary and secondary cells (PSCells). Provide the wireless device with an instruction to deactivate the SCG; Provide the wireless device with a Radio Link Monitoring (RLM) or Beam Failure Detection (BFD) reference signal to perform RLM or BFD on the SCG when the SCG is deactivated; as well as The wireless device is provided with additional indication for activating the SCG without performing a random access channel (RACH) procedure on the SCG, wherein the additional indication for activating the SCG includes subsequent indication of quasi-co-address QCL information for the physical downlink control channel (PDCCH) of the SCG.

8. The method according to claim 7, further comprising: Provide the wireless device with different instructions for reactivating the bandwidth portion (BWP) of the SCG thereon.

9. The method according to claim 7, further comprising: A dedicated RACH resource for the wireless device is configured for use with the SCG, wherein the dedicated RACH resource is configured for use if the PDCCH decoding of the SCG fails.

10. The method of claim 7, further comprising: Provide the wireless device with additional, different instructions for providing channel feedback for the SCG; The channel feedback for the SCG is received from the wireless device, wherein the channel feedback for the SCG is received using the Physical Uplink Shared Channel (PUSCH). as well as The SCG is provided with the channel feedback received from the wireless device for the SCG.

11. The method of claim 7, further comprising: Provide another indication for configuring one or more RLM parameters for activating the SCG, wherein the one or more RLM parameters include one or more timer or parameter values ​​associated with a radio link failure (RLF).

12. The method of claim 11, further comprising: Additional follow-up indications are provided for one or more exit conditions configured to reactivate the SCG using one or more RLM parameters, wherein the one or more exit conditions are associated with successful downlink communication reception on the SCG and a configured amount of time has elapsed.

13. The method according to claim 7, wherein, The RLM reference signal provided for the SCG is determined to be QCL with the PDCCH of the SCG.

14. The method according to claim 7, wherein, The BFD reference signal provided for the SCG is determined to be QCL with the PDCCH of the SCG.

15. The method of claim 7, further comprising: Provide the wireless device with supplementary indication of QCL information for the PDCCH of the SCG, including a reference signal list and an index of the reference signal in the reference signal list that is a QCL for the PDCCH of the SCG.

16. An apparatus for wireless communication, comprising: A processor configured to perform the operation of any one of claims 1-6 when executing instructions stored in memory.

17. The apparatus of claim 16, further comprising: A radio device capable of being operatively coupled to the processor.

18. An apparatus for wireless communication, comprising: A processor configured to perform the operation of the method according to any one of claims 7-15 when executing instructions stored in memory.

19. A non-transitory computer-readable storage medium storing program instructions that, when executed by one or more processors, cause a wireless device to perform the operation of the method according to any one of claims 1-6.

20. A non-transitory computer-readable storage medium storing program instructions that, when executed by one or more processors, cause a cellular base station (BS) to perform the operation of the method according to any one of claims 7-15.

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