System, Method, and Device for UL Timing Advance Acquisition and Update in a Wireless Communication Network

Abstract

The technology described in this specification includes one or more solutions that enable a UE to obtain initial uplink (UL) timing information (e.g., timing advance (TA) information) in a multi-transmit receive point (TRP) scenario before a handover command and a subsequent random access channel (RACH) procedure. A physical downlink (DL) control channel (PDCCH) command (e.g., downlink control information (DCI)) can be used to initiate a contention-free random access (CFRA) procedure to obtain UL timing information for a non-serving TRP. The PDCCH command can be transmitted in a control resource set (CORESET) having a coresetPoolIndex value associated with the non-serving cell TRP. Some additional technologies and features are also described in this specification.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication network including technologies for facilitating timing and synchronization in a wireless communication network.

Background Art

[0002] As the number of mobile devices and the demand for mobile data traffic within a wireless network continue to increase, system requirements and architectures are being changed to better address current and anticipated demands. For example, some wireless communication networks may be developed to implement fifth generation (5G) or new radio (NR) technologies, sixth generation (6G) technologies, and the like. One aspect of such technologies is to enable base stations and user equipment (UE) to transmit and receive timing and synchronization information to facilitate the execution of wireless network procedures such as enabling further wireless communication, establishing a connection, and participating in a handover procedure.

[0003] The present disclosure will be readily understood and executable by means of a detailed description and the figures in the accompanying drawings. Like reference numerals may indicate like features and structural elements. The figures and corresponding descriptions are provided as non-limiting examples of aspects, implementations, etc. of the present disclosure, and references to "an" or "one" aspect, implementation, etc. do not necessarily refer to the same aspect, implementation, etc., and may mean at least one, one or more, etc.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0022] The following detailed description refers to the accompanying drawings. Like reference numerals in different figures may identify the same or similar features, elements, operations, etc. Additionally, other implementations may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure, so the present disclosure is not limited to the following description.

[0023] A communication network may include a user equipment (UE) capable of communicating with a base station and other network nodes. The UE and the base station may implement various techniques for establishing and maintaining connectivity and for enabling the UE to move across the network by transitioning from one base station to another. The UE and the base station may enable UE mobility by implementing timing and synchronization operations, resource allocation procedures, random access channel (RACH) procedures, handover procedures, etc. These and other functions may enable the UE to communicate efficiently with the network and move around the network.

[0024] The objective of the wireless technology was to enable ultra-reliable low-latency communication (URLLC) between a base station and a UE. Examples of such technologies can include enabling multiple-input multiple-output (MIMO) communication, mechanisms, and procedures for inter-cell mobility based on the physical layer (e.g., layer 1 (L1)) and the media access control (MAC) layer (e.g., layer 2 (L2)), performing handover and RACH procedures towards a target transmission and reception point (TRP). The TRP described herein can include network nodes such as a base station capable of wireless communication with a UE. In some implementations, the base station can include an antenna array, processing capabilities, configuration, etc., such that the base station can operate as a plurality of TRPs with respect to a UE.

[0025] The developed wireless technology may enable the UE and the base station (e.g., TRP) to be involved to some extent in URLLC, MIMO, UE mobility, etc., but such technology includes several drawbacks. For example, the current technology regarding UE mobility may include a long process in which the UE measures the signal strength of one or more base stations (e.g., the serving base station and one or more non-serving base stations) and transmits a report of the measured signal strength to the serving base station. A UE communicating with multiple base stations or measuring signals from multiple base stations may be referred to as a multi-TRP scenario, and based on the measurement report, the serving base station may determine whether to trigger a handover procedure. If so, the serving base station can send a handover command to the UE via radio resource control (RRC) messaging, and in response, the UE can synchronize with the target base station, send a RACH preamble message to the target base station, and receive a random access response (RAR) message, etc., to complete the procedure triggered by the handover command. During this handover, if the UE's uplink (UL) transmission is to be moved to a different (i.e., target) cell, the UE may need to obtain the UL timing advance (TA) information of the target cell via the RACH procedure with the target cell. Such a procedure may fail to optimize UE mobility within the network, for example, by synchronizing the UE with the target base station after receiving a handover command and performing a subsequent RACH procedure with the target base station. Therefore, UE mobility latency involved in the transition from the serving base station to the target base station can be improved by enabling the UE to obtain TA information for non-serving base stations before receiving a handover command, and thus minimizing the mobility latency due to the RACH procedure. The TA described herein may include timing information used to control and / or synchronize UL signal transmission from the UE to the base station.

[0026] The technology described in this specification can include one or more solutions for improving UE mobility in a wireless network, for example, by enabling a UE to receive a handover command and obtain UL TA information regarding a target TRP (also referred to herein as a non-serving cell, target cell, non-serving TRP, target base station, non-serving base station, etc.) before participating in a subsequent RACH procedure with the target TRP. Doing so can enable the UE to transition from a serving base station to a non-serving base station and obtain TA information for the non-serving base station more quickly, thereby increasing the mobility of the UE within the wireless network. Next, extended URLLC, MIMO, etc. can be facilitated.

[0027] One or more of the technologies described in this specification can include using a physical downlink (DL) control channel (PDCCH) command (e.g., downlink control information (DCI)) to start a random access (RA) procedure, including a contention-free RACH (CFRA) procedure, to obtain UL timing information for a target base station or a non-serving base station. The PDCCH command can be transmitted in a control resource set (CORESET) having a coresetPoolIndex value associated with the non-serving base station. One or more other technologies described in this specification can include using the serving base station and various signals / channels to start a CFRA procedure towards a non-serving base station. One or more additional or alternative technologies described in this specification can include a UE explicitly configured by a higher layer using timing and / or other information for a TRP (e.g., a TRP of a non-serving base station) having a physical cell ID (PCI) different from that of the serving base station. The additional or alternative technologies described in this specification can include operations and procedures for receiving a RAR in an inter-cell multi-TRP scenario, operations and procedures for maintaining UL time alignment for an inter-cell multi-TRP scenario, etc. These and other features of the technology described in this specification are described in detail below with reference to the following figures.

[0028] FIG. 1 is an exemplary network 100 according to one or more implementations described herein. The exemplary network 100 may include user equipments (UEs) 110-1, 110-2, etc. (collectively referred to as "UE 110" and individually as "UE 110"), a radio access network (RAN) 120, a core network (CN) 130, an application server 140, an external network 150, and satellites 160-1, 160-2, etc. (collectively referred to as "satellites 160" and individually as "satellite 160"). As shown, the network 100 may include a non-terrestrial network (NTN) having one or more satellites 160 (e.g., of a global navigation satellite system (GNSS)) communicating with the UEs 110 and the RAN 120.

[0029] The systems and devices of the exemplary network 100 may operate according to one or more communication standards, such as the second generation (2G), third generation (3G), fourth generation (4G) (e.g., long term evolution (LTE)), and / or fifth generation (5G) (e.g., new radio (NR)) communication standards of the 3rd Generation Partnership Project (3GPP). Additionally or alternatively, one or more of the systems and devices of the exemplary network 100 may operate according to other communication standards and protocols described herein, including future versions or generations of 3GPP standards (e.g., sixth generation (6G) standards, seventh generation (7G) standards, etc.), Institute of Electrical and Electronics Engineers (IEEE) standards (e.g., wireless metropolitan area network (WMAN), worldwide interoperability for microwave access (WiMAX), etc.).

[0030] Examples of the UE 110 may include a smartphone (e.g., a handheld touchscreen mobile computing device capable of connecting to one or more wireless communication networks). Additionally or alternatively, the UE 110 may include other types of mobile or non-mobile computing devices capable of wireless communication, such as a personal digital assistant (PDA), a pager, a laptop computer, a desktop computer, a wireless headset, etc. In some implementations, the UE 110 may include an Internet of Things (IoT) device (or IoT UE) that can be equipped with a network access layer designed for low-power IoT applications that utilize short-lived UE connections. Additionally or alternatively, the IoT UE can utilize one or more types of technologies such as machine-to-machine (M2M) communication, or machine-type communication (MTC) (e.g., for exchanging data with an MTC server or other devices via a public land mobile network (PLMN)), proximity-based service (ProSe), device-to-device (D2D) communication, or vehicle-to-everything (V2X), sensor networks, IoT networks. Depending on the scenario, the M2M or MTC exchange of data can be an exchange initiated by a machine, and the IoT network can include interconnecting IoT UEs (which can include uniquely identifiable embedded computing devices within the Internet infrastructure) with short-lived connections. In some scenarios, the IoT UE may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate connection to the IoT network.

[0031] UE 110 can communicate with and establish a connection with one or more other UEs 110 via one or more wireless channels 112, each of which may comprise a physical communication interface / layer. The connection may include an M2M connection, an MTC connection, a D2D connection, a V2X connection, etc. In some implementations, UE 110 may be configured to discover each other, negotiate wireless resources between each other, and establish a connection between each other without intervention or communication with an RAN node 122 or another type of network node. In some implementations, discovery, authentication, resource negotiation, registration, etc. may include communication with an RAN node 122 or another type of network node.

[0032] UE 110 can communicate with and establish a connection to RAN 120 (e.g., communicatively coupled), which can include one or more wireless channels 114-1 and 114-2, each of which can comprise a physical communication interface / layer. In some implementations, the UE can be configured using Dual Connectivity (DC) as multi-Radio Access Technology (multi-RAT) or Multi-Radio Dual Connectivity (MR-DC), and multiple Receive and Transmit (Rx / Tx) capable UEs can use resources provided by different network nodes (e.g., 122-1 and 122-2) that can be connected via a non-ideal backhaul (e.g., one network node provides NR access and the other network node provides either LTE's E-UTRA or 5G's NR access). In such scenarios, one network node can function as a Master Node (MN) and the other network node can function as a Secondary Node (SN). The MN and SN can be connected via a network interface, and at least the MN can be connected to CN 130. Further, at least one of the MN or SN can operate using shared spectrum channel access, and the functions designated for UE 110 can be used for an Integrated Access and Backhaul Mobile Terminal (IAB-MT). Similarly to the case of UE 101, the IAB-MT can access the network using either one network node or any of two different nodes having an Enhanced Dual Connectivity (EN-DC) architecture, a New Radio Dual Connectivity (NR-DC) architecture, etc. In some implementations, a base station (described herein) can be an example of network node 122.

[0033] UE 110 and base station 122 may be configured to communicate with each other to perform one or more operations and / or procedures described herein. These communications may be performed via one or more wireless channels 114-1 and 114-2. For example, UE 110 communicates a reference signal received power (RSRP) measurement on a non-serving cell corresponding to non-serving base station 122 to serving base station 122, receives an instruction for executing a CFRA procedure towards the non-serving base station, and in response to the instruction, communicates a random access (RA) preamble message configured for the CFRA procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, and in response to the RA preamble message, may include one or more processors configured to receive a random access response (RAR) message including TA information for communicating on the non-serving cell from the non-serving base station.

[0034] As shown in the figure, UE110 may further or alternatively be connected to AP116 via a connection interface 118 that may include an air interface that enables UE110 to be communicatively coupled to an access point (AP) 116. AP116 may comprise a wireless local area network (WLAN), a WLAN node, a WLAN endpoint, etc. The connection 1207 may comprise a local wireless connection such as a connection that conforms to any IEEE 702.11 protocol, and AP116 may comprise a Wi-Fi (registered trademark) router or other AP. Although not explicitly shown in FIG. 1, AP116 may be connected to another network (e.g., the Internet) without being connected to RAN120 or CN130. In some scenarios, UE110, RAN120, and AP116 may be configured to utilize LTE-WLAN aggregation (LWA) technology or LTE-WLAN radio level integration (LWIP) operation with an IPsec tunnel. LWA may involve UE110 in RRC_CONNECTED as set by RAN120 to utilize the radio resources of LTE and WLAN. LWIP may involve using WLAN radio resources (e.g., connection interface 118) via IPsec protocol tunneling to authenticate and encrypt packets (e.g., Internet Protocol (IP) packets) transmitted by UE110 via connection interface 118. IPsec tunneling may include encapsulating the entire original IP packet, adding a new packet header, thereby protecting the original header of the IP packet.

[0035] The RAN 120 can include one or more RAN nodes 122-1 and 122-2 (collectively referred to as RAN nodes 122 and individually as RAN node 122) that enable channels 114-1 and 114-2 to be established between the UE 110 and the RAN 120. The RAN nodes 122 can include network access points configured to provide a radio baseband function for data and / or voice connectivity between a user and a network based on one or more of the communication technologies described herein (e.g., 2G, 3G, 4G, 5G, WiFi, etc.). Thus, by way of example, the RAN node can be an E-UTRAN Node B (e.g., an enhanced Node B, eNode B, eNB, 4G base station, etc.), a next-generation base station (e.g., a 5G base station, an NR base station, a next-generation eNB (gNB), etc.). The RAN nodes 122 can include roadside units (RSUs), transmit-receive points (TRxP or TRP), and one or more other types of terrestrial stations (e.g., terrestrial access points). In some scenarios, the RAN nodes 122 can be dedicated physical devices such as macrocell base stations and / or low-power (LP) base stations for providing femtocells, picocells, etc. having a coverage area smaller, user capacity smaller, or bandwidth wider compared to a macrocell. As described below, in some implementations, the satellite 160 can operate as a base station (e.g., RAN node 122) with respect to the UE 110. Thus, references herein to base stations, RAN nodes 122, etc. can include implementations where the base stations, RAN nodes 122, etc. are terrestrial network nodes and implementations where the base stations, RAN nodes 122, etc. are non-terrestrial network nodes (e.g., satellite 160).

[0036] Some or all of the RAN nodes 122, or portions thereof, can be implemented as one or more software entities that are executed on a server computer as part of a virtual network, and this software entity may be referred to as a Centralized RAN (CRAN) and / or Virtualized Baseband Unit Pool (vBBUP). In these implementation forms, the CRAN or vBBUP can perform RAN function splitting such as Packet Data Convergence Protocol (PDCP) splitting where the Radio Resource Control (RRC) and PDCP layers are operated by the CRAN / vBBUP and other Layer 2 (L2) protocol entities can be operated by the individual RAN nodes 122, RRC, PDCP, Radio Link Control (RLC), and Media Access Control (MAC) / Physical (PHY) layer splitting where the MAC and PHY layers are operated by the CRAN / vBBUP and the PHY layer can be operated by the individual RAN nodes 122, or "lower PHY" splitting where the upper portions of the RRC, PDCP, RLC, MAC layers, and PHY layer are operated by the CRAN / vBBUP and the lower portion of the PHY layer can be operated by the individual RAN nodes 122. This virtualized framework can free up the processor cores of the RAN nodes 122 and enable the execution of other virtualized applications.

[0037] In some implementations, each RAN node 122 can represent an individual gNB distributed unit (DU) connected to a gNB control unit (CU) via an individual F1 or other interface. In such an implementation, the gNB-DU can include one or more remote radio heads or radio frequency (RF) front end modules (RFEMs), and the gNB-CU can operate by a server (not shown) located in the RAN 120 or by a server pool (e.g., a group of servers configured to share resources) in a manner similar to CRAN / vBBUP. Additionally or alternatively, one or more of the RAN nodes 122 may be a next-generation eNB (i.e., gNB), which can provide evolved universal terrestrial radio access (E-UTRA) user plane and control plane protocol terminations for the UE 110 and can be connected to the 5G core network (5GC) 130 via the NG interface.

[0038] Any of the RAN nodes 122 can terminate the air interface protocol and can serve as the first contact for the UE 110. In some implementations, any of the RAN nodes 122 may perform various logical functions for the RAN 120, which functions may include, but are not limited to, radio bearer management, uplink and downlink dynamic radio resource management, and data packet scheduling, and radio network controller (RNC) functions such as mobility management. The UE 110 may be configured to communicate with each other or with any of the RAN nodes 122 using orthogonal frequency-division multiplexing (OFDM) communication signals via a multi-carrier communication channel according to various communication technologies, such as, but not limited to, OFDMA communication technology (e.g., for downlink communication) or single carrier frequency-division multiple access (SC-FDMA) communication technology (e.g., for uplink and ProSe or sidelink (SL) communication). However, the scope of such embodiments is not necessarily limited thereto. The OFDM signal may include a plurality of orthogonal sub-carriers.

[0039] In some implementations, the downlink resource grid may be used for downlink transmission from any of the RAN nodes 122 to the UE 110, and uplink transmission may utilize similar techniques. The grid can be a time-frequency grid (e.g., a resource grid or a time-frequency resource grid) representing the physical resources of the downlink within each slot. Such a time-frequency plane representation is a common way in OFDM systems, which makes the allocation of radio resources intuitive. Each column and each row of the resource grid correspond to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot within a radio frame. The minimum time-frequency unit of the resource grid is denoted as a resource element. Each resource grid includes resource blocks, which represent the mapping of a specific physical channel to resource elements. Each resource block can include a set of resource elements (REs), and in the frequency domain, this can represent the minimum amount of resources that can currently be allocated. There are several different physical downlink channels transmitted using such resource blocks.

[0040] Furthermore, RAN node 122 may be configured to wirelessly communicate with UE 110 and / or with each other via an authorized medium (also referred to as "authorized spectrum" and / or "authorized band"), an unlicensed shared medium (also referred to as "unlicensed spectrum" and / or "unlicensed band"), and / or a combination thereof. In one example, the licensed spectrum may include channels operating in a frequency range of approximately 400 MHz to approximately 3.8 GHz, and the unlicensed spectrum may include the 5 GHz band. The licensed spectrum can correspond to channels or frequency bands that are selected, reserved, regulated, etc. for some types of wireless activities (e.g., wireless long-distance communication network activities), and the unlicensed spectrum can correspond to one or more frequency bands that are not restricted for a particular type of wireless activity. Whether a particular frequency band corresponds to a licensed medium or an unlicensed medium can depend on one or more factors such as a frequency allocation determined by a public-sector organization (e.g., a government agency, a regulatory agency, etc.) or a frequency allocation determined by a private-sector organization involved in the development of wireless communication standards and protocols.

[0041] To operate in the unlicensed spectrum, UE 110 and RAN node 122 can operate using a licensed assisted access (LAA), eLAA, or feLAA mechanism. In these implementations, UE 110 and RAN node 122 may perform one or more known medium sensing operations or carrier sensing operations before transmitting in the unlicensed spectrum to determine whether one or more channels in the unlicensed spectrum are unavailable or otherwise occupied. The medium / carrier sensing operations may be performed according to a listen before talk (LBT) protocol.

[0042] The LAA mechanism can be constructed based on the Carrier Aggregation (CA) technology of the LTE Advanced system. In CA, each aggregated carrier is called a Component Carrier (CC). In some cases, individual CCs can have different bandwidths from other CCs. In a Time Division Duplex (TDD) system, the number of CCs and the bandwidth of each CC may be the same for DL and UL. CA also includes the individual serving cells that provide the individual CCs. For example, since CCs in different frequency bands are expected to experience different path losses, the coverage of the serving cells can be different. The Primary Service Cell or PCell can provide a Primary Component Carrier (PCC) for both UL and DL and can handle RRC and non-access stratum (NAS) related activities. Other serving cells are called SCell, and each SCell can provide an individual Secondary Component Carrier (SCC) for both UL and DL. While SCCs can be added and removed as needed, to change the PCC, UE110 may need to receive a handover. In LAA, eLAA, and feLAA, some or all of the SCells can operate in an unlicensed band (referred to as "LAA SCell"), and the LAA SCell is assisted by the PCell operating in a licensed band. If the UE is composed of two or more LAA SCells, the UE can receive UL grants on the configured LAA SCells indicating different PUSCH start positions within the same subframe. To operate in the unlicensed spectrum, UE110 and RAN node 122 can also operate using stand-alone unlicensed operation, where the UE can be configured using the PCell in addition to any SCell in the unlicensed spectrum.

[0043] The PDSCH can carry user data and upper layer signaling to the UE 110. The Physical Downlink Control Channel (PDCCH) can carry, among other things, information regarding the transport format and resource allocation for the PDSCH channel. The PDCCH can notify the UE 110 about the transport format, resource allocation, and Hybrid Automatic Repeat reQuest (HARQ) information regarding the uplink shared channel. Typically, downlink scheduling (e.g., allocating control and shared channel resource blocks to UE110-2 within a cell) may be performed at any of the RAN nodes 122 based on channel quality information fed back from any of the UEs 110. Downlink resource allocation information can be transmitted on the PDCCH used (e.g., allocated) for each of the UEs 110.

[0044] The PDCCH uses Control Channel Elements (CCEs) to carry control information, and the number of CCEs (e.g., 6, etc.) can be set in Resource Element Groups (REGs), where a REG is defined as a Physical Resource Block (PRB) within an OFDM symbol. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be scrambled, for example, with a quadruplet, and then interleaved using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, and each CCE can correspond to nine sets of four physical resource elements known as a REG. Four Quadrature Phase Shift Keying (QPSK) symbols can be mapped to each REG. The PDCCH can be transmitted using one or more CCEs depending on the size of the Downlink Control Information (DCI) and the channel state. There can be four or more different PDCCH formats defined for LTE with different numbers of CCEs (e.g., aggregation levels, L = 1, 2, 4, 8, or 16).

[0045] Some implementations may use the concept of resource allocation for control channel information, which is an extension of the above concept. For example, some implementations can utilize an Extended (E) PDCCH that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more ECCEs. Similar to the above, each ECCE may correspond to a set of nine physical resource elements known as EREGs. In some situations, the ECCE may have other numbers of EREGs.

[0046] RAN node 122 may be configured to communicate with each other via interface 123. In an implementation where the system is an LTE system, interface 123 may be an X2 interface. In an NR system, interface 123 may be an Xn interface. The X2 interface may be defined between two or more RAN nodes 122 (e.g., two or more eNBs / gNBs or a combination thereof) connected to an evolved packet core (EPC) or CN130, and / or between two eNBs connected to the EPC. In some implementations, the X2 interface may include an X2 user plane interface (X2 User, X2-U) and an X2 control plane interface (X2 Control, X2-C). X2-U may provide a flow control mechanism for user data packets transferred via the X2 interface and may be used to communicate information regarding the delivery of user data between eNBs or gNBs. For example, X2-U may provide information such as the specific sequence number information of user data transferred from a Master eNB (MeNB) to a Secondary eNB (SeNB), information regarding the success of the sequence delivery of PDCP packet data units (PDUs) from the SeNB to the UE110 for the user data, information on PDCP PDUs not provided to the UE110, and information regarding the current minimum desired buffer size at the SeNB for transmitting user data to the UE. X2-C can provide LTE intra-access mobility functionality (e.g., including context transfer from a source eNB to a destination eNB, user plane transport control, etc.), load management functionality, and inter-cell interference coordination functionality.

[0047] As shown in the figure, RAN120 may be connected (e.g., communicatively coupled) to CN130. CN130 may include a plurality of network elements 132 configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UE110) connected to CN130 via RAN120. In some implementations, CN130 may include an evolved packet core (EPC), a 5G CN, and / or one or more additional or alternative types of CN. The components of CN130 may be implemented on a single physical node or separate physical nodes, including components for reading and executing instructions from a machine-readable medium or computer-readable medium (e.g., a non-transitory machine-readable storage medium). In some implementations, network function virtualization (NFV) may be utilized to virtualize any or all of the roles or functions of the above-described network nodes via executable instructions stored on one or more computer-readable storage media (described in more detail below). The logical instantiation of CN130 may be referred to as a network slice, and some logical instantiations of CN130 may be referred to as network sub-slices. The network function virtualization (NFV) architecture and infrastructure can be used to virtualize one or more network functions that are instead performed by dedicated hardware on physical resources including industry-standard server hardware, storage hardware, or a combination of switches. In other words, an NFV system can be used to execute virtual or reconfigurable implementations of one or more EPC components / functions.

[0048] As shown in the figure, CN130, application server 140, and external network 150 can be connected to each other via interfaces 134, 136, and 138, which can include IP network interfaces. The application server 140 can include one or more server devices or network elements (e.g., virtual network functions (VNFs)) that provide applications (e.g., Universal Mobile Telecommunications System Packet Service (UMTS PS) domain, LTE PS data services, etc.) that use IP bearer resources at CM130. The application server 140 can similarly or alternatively be configured to support one or more communication services (e.g., Voice over IP (VoIP sessions, Push-to-Talk (PTT) sessions, group communication sessions, social networking services, etc.) for UE110 via CN130. Similarly, the external network 150 can include one or more of various networks including the Internet, thereby providing the mobile communication network and the network's UE110 with access to various additional services, information, interconnectivity, and other network functions.

[0049] As shown in the illustration, an exemplary network 100 may include a NTN that may include one or more satellites 160-1 and 160-2 (collectively referred to as "satellites 160"). The satellites 160 can communicate with the UE 110 via a service link or wireless interface 162 and / or with the RAN 120 via a feeder link or wireless interface 164 (shown individually as 164-1 and 164). In some implementations, the satellites 160 may operate as passive or transparent network relay nodes with respect to communication between the UE 110 and a terrestrial network (e.g., the RAN 120). In some implementations, the satellites 160 may operate as active or regenerative network nodes such that the satellites 160 can operate as a base station for the UE 110 (e.g., as a gNB of the RAN 120) with respect to communication between the UE 110 and the RAN 120. In some implementations, the satellites 160 may communicate with each other directly via a wireless interface (e.g., 166) or indirectly via a wireless interface (e.g., using interfaces 164-1 and 164-2 via the RAN120).

[0050] Additionally or alternatively, the satellites 160 may include GEO satellites, LEO satellites, or another type of satellite. The satellites 160 may similarly or alternatively be related to one or more satellite systems or architectures such as the Global Navigation Satellite System (GNSS), the Global Positioning System (GPS), the Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS), the BeiDou Navigation Satellite System (BDS), etc. In some implementations, the satellites 160 may operate as a base station (e.g., RAN node 122) for the UE 110. Thus, references herein to base stations, RAN node 122, etc. may include implementations where the base stations, RAN node 122, etc. are terrestrial network nodes and implementations where the base stations, RAN node 122, etc. are non-terrestrial network nodes (e.g., satellites 160). As described herein, the UE 110 and the base station 122 can communicate with each other via the interface 114 to enable extended power saving techniques.

[0051] Figure 2 is a diagram of example 200 for UL TA acquisition and update according to one or more implementations described herein. As shown, Figure 2 can include serving base station 122-1 having a coverage area of serving cell 210, UE 110 located within the coverage area of cell 210, and target base station 122-2 having a coverage area of non-serving cell 220. UE 110 may be moving in the direction of target base station 122-2. Base station 122-1 can have a PCI of 1 and can correspond to one COREST (e.g., having a coresetPoolInex parameter value of 0). Base station 122-2 can have a PCI of 2 and can correspond to a second COREST (e.g., having a coresetPoolInex parameter value of 1). Such a scenario can include a multi-TRP scenario where base station 122-1 corresponds to a first TRP (e.g., TRP 1) for UE 110 and the base station corresponds to a second TRP (e.g., TRP 2) for UE 110.

[0052] The techniques described herein can include various methods for obtaining an initial UL timing for a multi-TRP scenario. For example, UE 110 can be configured by upper layer communication with a set of CORESETs having different coresetPoolIndex values (e.g., a coresetPoolIndex value of 0 for base station 122-1 and a coresetPoolIndex value of 1 for base station 122-2). Thus, Figure 2 provides an example of a CORESET configured for inter-cell mTRP. In some implementations, UE capability information can be used to report the maximum number (X) of additional RRC-configured PCIs per frequency for obtaining and maintaining UL timing.

[0053] FIG. 3 is a diagram of an example 300 of a search space associated with CORESETs of different TRPs according to one or more implementations described herein. Example 300 may correspond to example 200 of FIG. 2, where serving base station 122-1 corresponds to TRP 1 and target base station 122-2 corresponds to TRP 2. As shown, the TRP 1 search space (SS) having a CORESET (including a coresetPoolIndex value of 0) may include search spaces SS_1.1 in the first slot, SS_1.2 in the second slot, etc., up to SS 1.N (where N is 3 or more). The second slot may also include SS_2.1 having a CORESET of TRP 2 (including a coresetPoolIndex value of 1). Thus, a random access procedure for obtaining UL timing for a TRP may be initiated by a PDCCH order (e.g., DCI format 1_0) transmitted in a CORESET having a coresetPoolIndex value associated with a non-serving cell TRP (e.g., coresetPoolIndex of 1 for TRP 2). For example, a PDCCH order for triggering a CFRA procedure for TRP 2 may be transmitted by TRP 2 in a search space (SS) associated with a CORESET having a coresetPoolIndex of 1. Thus, UE 110 may receive a DCI including an order for UE 110 to monitor the SS of a non-serving cell (e.g., base station 122-2).

[0054] FIG. 4 is a diagram of an exemplary process 400 of a CFRA procedure initiated by a non-serving cell TRP according to one or more implementations described herein. Process 400 may be implemented by UE 110, base station 122-1, and base station 122-2. In some implementations, some or all of process 400 may be executed by one or more other systems or devices including one or more of the devices of FIG. 1. Additionally, process 400 may include one or more fewer, additional, different order and / or arrangement of operations than those shown in FIG. 4. In some implementations, some or all of the operations of process 400 may be executed independently of, sequentially, simultaneously, etc., with one or more of any other operations of process 400.

[0055] As described above, UE 110 may receive a configuration for measuring an SSB corresponding to a non-serving cell (e.g., base station 122-2). As shown, UE 110 may communicate (at 410) a report of an L1 reference signal received power (RSRP) measurement based on the SSB to base station 122-1 (e.g., TRP 1). Further, the RSRP measurement value and / or the RSRP measurement report may be based on RRC configuration information and / or channel state information (CSI) reference signal (RS) (CSI-RS) that UE 110 may have previously received from base station 122-1 or base station 122-2. Base station 122-1 may transmit (at 420) an L1-RSRP measurement report associated with TRP 2 to base station 122-2.

[0056] The base station 122-2 can respond to the report by sending DCI to the UE110 to trigger the CFRA procedure (at 430). The DCI may be DCI format 1_0 and may be sent in a CORESET having a coresetPoolIndex value of 1 which may be a coresetPoolIndex value corresponding to TRP 2. The UE110 can respond by sending a CFRA message 1 (MSG1) to the base station 122-2 based on the DCI (at 440). The base station 122-2 can receive the MSG1 (at 450) and respond with a PDSCH RAR message, and the UE110 can respond by sending a CFRA completion message to the base station 122-1 (at 460) to notify the completion of the CFRA procedure to TRP 2. As shown, the CFRA completion message can include a valid TA of the base station 122-2 that can help facilitate a subsequent L1 / L2-based handover to the base station 122-2.

[0057] FIG. 5 is a diagram of an exemplary process 500 of a CFRA procedure initiated by a serving cell TRP according to one or more implementations described herein. The process 500 can be implemented by the UE110, the base station 122-1, and the base station 122-2. In some implementations, some or all of the process 500 can be executed by one or more other systems or devices including one or more of the devices of FIG. 1. Additionally, the process 500 may include one or more fewer, additional, different order and / or sequence of operations than those shown in FIG. 5. In some implementations, some or all of the operations of the process 500 can be executed independently of, continuously with, simultaneously with, etc., one or more of any other operations of the process 500.

[0058] As described above, the UE 110 may receive a configuration for measuring an SSB corresponding to the non-serving cell TRP 2 (e.g., base station 122-2). The UE 110 may communicate a report of the L1 RSRP measurement value to the base station 122-1 (e.g., TRP 1) based on the SSB (at 510). Additionally, the RSRP measurement value and / or the RSRP measurement report may be based on RRC configuration information and / or channel state information (CSI) reference signal (RS) (CSI-RS) that the UE 110 may have previously received from the base station 122-1 or the base station 122-2.

[0059] The base station 122-1 may respond to the RSRP measurement value by transmitting DCI to the UE 110 to trigger a CFRA procedure towards the base station 122-2 (at 520). The DCI may be DCI format 1_0 transmitted in a CORESET (e.g., coresetPoolIndex 0) and may include information identifying the base station 122-2, such as the target cell ID (TCI) of the base station 122-2. The UE 110 may respond by transmitting a CFRA MSG1 to the base station 122-2 based on the DCI (at 530). The base station 122-2 may receive the MSG1 and respond with a PDSCH RAR message (at 540), and the UE 110 may respond by transmitting a CFRA completion message to the base station 122-1 (at 550). As shown, the CFRA completion message may include a valid TA of the base station 122-2 that can help facilitate a subsequent L1 / L2-based handover to the base station 122-2.

[0060] FIG. 6 is a diagram of an example 600 of the current version of DCI format 1_0 and an extended version of DCI format 1_0 according to one or more implementations described herein. As shown, the current version of DCI format 1_0 can be used for PDCCH orders of CFRA for the serving cell only, and includes a cyclic redundancy check (CRC) field (which can be scrambled by a cell radio network temporary identifier (C-RNTI)), 12 reserved bits, and other DCI format 1_0 fields. The extended version of DCI format 1_0 can be for the inter-cell multi-TRP (mTRP) procedure and can include a CRC field and other DCI format 1_0 fields. In contrast to the current version, the extended DCI format 1_0 can also include a TCI field by reusing a portion of the reserved bits and the smaller remaining portion of the reserved bits for a larger portion of the reserved bits of the current DCI format 1_0. The extended DCI format 1_0 can be used by a serving cell TRP (e.g., base station 122-1) to trigger the UE 110 to perform a CFRA procedure towards a target or non-serving cell TRP (e.g., base station 122-2). In some implementations, the PCI of the target non-serving cell can be explicitly indicated by the TCI field. In such implementations, since the PCI can be up to 1008, the TCI field size can be larger than that shown in FIG. 6 (e.g., up to 12 bits).

[0061] In some implementations, an additional or alternative signaling mechanism may be used by the serving cell TRP (e.g., base station 122-1) to trigger the UE110 to perform the CFRA procedure towards a target or non-serving cell TRP (e.g., base station 122-2). For example, a combination of RRC signaling and DCI may be used. In such an implementation, a new RRC message may be used to provide the dedicated TCI field value for a given non-serving cell in the list. Such an RRC message may include an ASN.1 (abstract syntax notation.1) structure that follows or is similar to the following.

Table 1

[0062] In such an implementation, the TCI-InSchedulingCell field may indicate the TCI value used at the serving cell TRP (e.g., base station 122-1) to trigger a CFRA procedure involving the non-serving cell TRP (e.g., base station 122-2) indicated by the TargetCellId field. The corresponding TCI field value associated with the non-serving cell TRP may be included in the extended DCI format 1_0. In some implementations, the TCI field size may be 3 bits. Alternatively, the TCI field size may depend on the total number of non-serving cell TRPs configured using the CFRA capability. In some implementations, certain field values (e.g., all 0s or all 1s) may be reserved for triggering CFRA for the serving cell itself.

[0063] FIG. 7 is a diagram of an exemplary table 700 of the association between TCI field values and the PCI of a non-serving cell TRP according to one or more implementations described herein. As shown, 8 non-serving cell PCIs can be associated with 1 TCI field value. 36 non-serving cell PCIs can be associated with 2 TCI field values. 68 non-serving cell PCIs can be associated with 3 TCI field values. Also, 480 non-serving cell PCIs can be associated with 4 TCI field values. Thus, a serving cell TRP (e.g., base station 122-1) can transmit information associated with a TCI field value along with the PCI of a non-serving cell TRP (e.g., base station 122-2). The serving cell can also transmit an RRC message (e.g., using an ASN.1 structure) to indicate a TCI value that the UE 110 can use to identify the PCI of the non-serving cell TRP for which the CFRA should be initiated.

[0064] FIG. 8 is a diagram of an exemplary process 800 for CFRA initiated by a serving cell according to one of the multiple implementations described herein. Process 800 can be implemented by UE 110, base station 122-1, and base station 122-2. In some implementations, some or all of process 800 can be executed by one or more other systems or devices including one or more of the devices of FIG. 1. Additionally, process 800 may include one or more fewer, additional, different order and / or arrangement of operations than those shown in FIG. 8. In some implementations, some or all of the operations of process 800 can be executed independently of, continuously with, simultaneously with, etc., one or more of any other operations of process 800.

[0065] As shown in the figure, the base station 122-1 may transmit a transmission configuration indicator state activation MAC control element (CE) message to the UE 110 (at 810). The transmission configuration indicator state activation MAC CE message may identify a non-serving cell via an identifier (i) in the message and / or may be configured to indicate resources of a PRACH occasion that the UE 110 may use to contact a non-serving cell (e.g., the base station 122-2). The PRACH occasion may be at least a specified number of symbols (N) after the last symbol of the PDCCH order reception. The specified number of symbols may be configured by a communication standard such that the number of symbols is common among all or similarly capable and / or located UEs 110. Thus, the UE 110 may proceed by transmitting a PRACH transmission to a non-serving cell (e.g., the base station 122-2) (at 820). The UE 110 may transmit a PRACH transmission using the PRACH occasion resources indicated in the TCI state activation MAC CE message. The base station 122-2 may receive the PRACH transmission (at 830) and may respond by transmitting a PDSCH RAR message to the UE 110. The PDSCH RAR message may include TA information that the UE 110 may use in subsequent communication, for example, to help reduce mobility latency.

[0066] Figure 9 is a diagram of an exemplary MAC CE 900 for extended TCI state activation / deactivation for a non-serving cell CFRA procedure according to one or more implementations described herein. As shown, the MAC CE 900 may include information with bit octets (e.g., OCT 1, OCT 2, OCT 3, ..., OCT N) arranged horizontally, where each octet is vertically adjacent to one or two other octets. The MAC CE may include a first octet (e.g., OCT 1) having a 2-bit BWP ID field, a 6-bit serving cell ID field, and a 1-bit CPI (coresetPoolIndex) field, and may include a TCI state for the DL portion. OCT 2 and OCT 3 may each include TCI index fields T0~T7 and TCI T8~T15, respectively. The MAC CE 900 may also include a CFRA RACH resource portion for UL timing, which may include fields for physical random access channel (PRACH) mask indices 0~3 and fields for preamble indices 0~3. TCI index 0 may correspond to PRACH mask index 0 and preamble index 0, TCI index 1 may correspond to PRACH mask index 0 and preamble index 1, and so on.

[0067] According to MAC CE 900, the PRACH resource can be used for CFRA operation when explicitly indicated by an extended TCI state activation MAC-CE such as MAC-CE 900. A pair of preamble index (i) and PRACH mask index (i) can exist only when the TCI state activation MAC CE is applied to a non-serving cell TRP (e.g., base station 122-2). That is, the pair can be mapped based on the order position between TCI states with a value set to 1 in order to minimize overhead. In other words, for example, the pair (preamble index #0 and PRACH mask index #(0) can be mapped to the first TCI state with a value set to 1, the second (preamble index #1, PRACH mask index #1) can be mapped to the second TCI state with a value set to 1, and so on.

[0068] FIG. 10 is a diagram of an example of a CFRA resource configuration 1000 for each non-serving cell according to one of the multiple implementations described herein. As shown, in some implementations, there can be one or more CFRA resource configurations 1000 (up to 8 in some cases). The CFRA resource configuration 1000 can include a PCI-ID field, a contention-free PRACH resource field, a selection field, an SSB field, an SSB resource list field having a sequence {1 to M} field, an SSB index field, and a preamble index field, a CSI-RS field, and a CSI-RS resource list field having a sequence {1 to M} field, a CS-RS index field, and a preamble index field. The CFRA resource configuration 1000 can also include an RSRP threshold SSB field (which can be optional) and an RSRP threshold CS-RS field (which can be optional).

[0069] The technology described in this specification may include an RRC-MAC-CE signaling method for random access (e.g., CFRA) initialization for inter-cell multi-TRP. The PRACH resources used for CFRA operation may be provided by RRC signaling associated with the SSB index or CSI-RS index of each non-serving cell. The CFRA resource configuration 1000 may be an example of such a data structure.

[0070] Upon receiving a TCI state activation MAC-CE that activates at least one TCI state for the PDSCH of a non-serving cell (i), the UE 110 may transmit a PRACH by using the corresponding RACH resources associated with an SSB or CSI-RS (such as represented by the CFRA resource configuration 1000). In some implementations, when two or more TCI states of a non-serving cell are activated by a single TCI state MAC CE, the UE 110 may select the SSB or CSI-RS with the maximum L1-RSRP to execute the CFRA procedure. Alternatively, the UE 110 may execute CFRA for all activated TCI states in a time-division multiplexing (TDM) manner, and the order of CFRA for different TCI states may depend on the configuration of the UE 110.

[0071] FIG. 11 is a diagram of an exemplary process 1100 for a UE autonomous conditional CFRA procedure using network assistance information according to one of the multiple implementations described in this specification. The process 1100 may be implemented by the UE 110, the base station 122-1, and the base station 122-2. In some implementations, some or all of the process 1100 may be executed by one or more other systems or devices including one or more of the devices in FIG. 1. Additionally, the process 1100 may include one or more fewer, additional, different orders and / or sequences of operations than those shown in FIG. 11. In some implementations, some or all of the operations of the process 1100 may be executed independently of, continuously with, simultaneously with, etc., one or more of any other operations of the process 1100.

[0072] In some implementations, UE 110 may be explicitly configured (e.g., by a higher layer) using information about each TRP having a PCI different from that of the serving cell (e.g., base station 122-1). As shown, UE 110 may transmit an L1-RSRP measurement report based on an RRC-configured SSB or CSI-RS transmission (at 1110). Base station 122-1 may receive the measurement value (at 1120) and transmit an L1 / L2-based mobility request to base station 122-2 based on the measurement value. Base station 122-2 may respond by transmitting a dedicated PRACH resource list for different SSBs / CSI-RSs to base station 122-1 (at 1130), and base station 122-1 may transmit it to UE 110 (at 1140). The dedicated PRACH resources for inter-cell mTRP may be provided in a way that enables UE 110 to associate the dedicated PRACH resources with an SSB index or a CSI-RS index. Additionally or alternatively, an RSRP threshold SSB or an RSRP threshold CSI-RS that may be used by UE 110 to determine whether to initiate a UE autonomous RACH procedure based on SSB or CSI-RS RSRP measurement values may also be provided.

[0073] UE 110 may use the resource list to monitor one or more conditions that may trigger a CFRA procedure to a target cell or TRP, such as base station 122-2 (at 1150). Such conditions may be, for example, whether the SSB or CSI-RS RSRP measurement value exceeds a threshold indicated by information received from base station 122-2 (e.g., RSRP threshold SSB or RSRP threshold CSI-RS).

[0074] In some implementations, UE110 may be explicitly configured via upper layer signaling, which may include configuring a set of type 1-PDCCH common search spaces (CSSs) for RAR reception that includes DL BWP information. In some implementations, if the same type 1-PDCCH CSS set and DL BWP configuration as the serving cell (e.g., base station 122-1) are not provided for non-serving cells, they may be assumed by UE110. Using pre-configured information (e.g., received via a higher layer), UE110 may have dedicated PRACH resources stored for the mTRP of multiple cells, which may reduce handover time when a failure is detected (e.g., because UE110 may transition to another target cell more quickly due to information stored for multiple cells). As shown in FIG. 5, UE110 may start evaluating CFRA trigger conditions based on the measured L1-RSRP for RRC-configured SSB or CSI-RS (at 1150), and may trigger CFRA using RRC-configured RACH resources (at 1160) if the conditions are met. For the purpose of explaining the exemplary process 1100, assume that UE110 detects one or more of the conditions and responds by triggering CFRA (at 1160). UE110 may proceed by transmitting a RACH MSG1 to base station 122-2 based on the strongest SSB. Base station 122-2 may respond to MSG1 by transmitting a RAR message to UE110 (at 1180).

[0075] FIG. 12 is a diagram illustrating an example of an extended MAC RAR 1200 for indicating a non-serving cell TA value according to one or more implementations described herein. The extended MAC RAR 1200 may include 7 rows of bit octets (OCT 1, OCT, OCT, 3, etc.). The first octet (OCT 1) may include one reused bit (R) and 7 bits for TA command information. The bit R may indicate a coresetPoolIndex value (e.g., 0 or 1). As described herein, a coresetPoolIndex value of 0 may correspond to a serving cell TRP (e.g., base station 110-1), and a coresetPoolIndex value of 1 may correspond to a serving cell TRP (e.g., base station 110-2). Octet 2 may include 6 more bits for TA command information and 2 bits for UL grant information. Octets 3-5 may also be used for UL grant information, and octets 6 and 7 may be for temporary C-RNTI information.

[0076] UE 110 may monitor a type 1-PDCCH CSS set of a non-serving cell TRP (e.g., base station 122-2) for a DCI format 1_0 that may include a CRC scrambled with a C-RNTI or RA RNTI (RA-RNTI) in the RAR window. In some implementations, the serving cell (e.g., base station 122-1) may provide UE 110 with an explicit indication of the configuration of the type 1-PDCCH CSS set associated with the non-serving cell (e.g., base station 122-2). The explicit indication may be performed through RRC messaging before CFRA is triggered. In some implementations, the serving cell (e.g., base station 122-1) may implicitly provide the configuration to UE 110 (e.g., since UE 110 may be configured to apply the type 1-PDCCH CSS set associated with the serving cell to the non-serving cell).

[0077] UE110 may also or alternatively include a type 1-PDCCH CSS set for the serving cell TRP (e.g., base station 122-1) for DCI format 1_0 that may include a CRC scrambled with a C-RNTI or RA-RNTI in the RAR window. In some implementations, this may be facilitated by a backhaul network that enables base stations 122-1 and 122-2 to communicate such that, for example, base station 122-1 can provide UE110 with an RAR message that would otherwise come from base station 122-2. In such an implementation, the extended MAC RAR 1200 of FIG. 12 can be used as the reused bits (R) can be modified to indicate an appropriate coresetPoolIndex value (e.g., a value of 1 for base station 122-2).

[0078] FIG. 13 is a diagram of an example 1300 of multi-TRP communication and corresponding differential TA values according to one or more implementations described herein. As shown, example 1300 may include a DL transmission period 1310 and a UL transmission period 1320 for a serving cell (e.g., base station 122-1) and a DL transmission period 1330 and a UL transmission period 1340 for a non-serving cell (e.g., base station 122-1). As shown, UE110 may implement that a time difference (e.g., differential TA value) may be implemented between UL communications 1320 and 1340. In some implementations, the differential timing value may be provided to UE110 via a MAC RAR message for a non-serving cell. As described above, depending on the implementation or scenario, the MAC RAR message may be provided by a serving cell or a non-serving cell. The differential TA value may be indicated by TA command (TAC) information within the MAC RAR message. In some implementations, the differential TA value may be indicated relative to the TA value of the serving cell or as a differential TA value relative to the TA value of the serving cell. Providing the differential TA value as a relative value instead of the complete TA value may help minimize signaling overhead as, for example, a relative TA value may use fewer bits.

[0079] In some implementations, the network may explicitly indicate to UE 110 one of the following TA values via RRC signaling (e.g., without the involvement of the CFRA procedure or MAC RAR). TA = 0 (e.g., no TA) may be used for initial UL transmission to a non-serving cell (which may be used for scenarios with small cells). Additionally or alternatively, RRC signaling may explicitly indicate that UE 110 should use the same TA that is being used for the serving cell for the non-serving cell. This TA command may be used for scenarios when UE 110 is located at or near the cell boundary between the serving cell and the non-serving cell. Additionally or alternatively, RRC signaling may explicitly indicate that UE 110 should obtain UL timing information from the non-serving cell using the DL timing difference between the serving cell and the non-serving cell. The DL timing difference may be determined as follows: T 2 = T 1 + Δ DL where T 1 and T 2 may be the respective UL TA values of the serving cell (e.g., base station 122-1) and the non-serving cell (e.g., base station 122-2), and where Δ DL may be the DL timing difference between the serving cell and the non-serving cell, may be measured at the UE side, and may or may not be reported to the network.

[0080] FIG. 14 is a diagram of an example 1400 of extended MAC CEs 1410 and 1420 according to one or more of the implementation forms described in this specification. The extended MAC CEs 1410 and 1420 may be configured to indicate the TA value of a non-serving cell TRP (e.g., base station 122-2). As shown in the figure, the extended MAC CEs 1410 and 1420 may each include a first and a second octet (OCT 1 and OCT 2). Octet 1 may include 2 bits for timing advance group (TAG) ID information and 6 bits for TAC information, and octet 2 may include 7 reserved bits (R). Octet 2 of the extended MAC CE 1410 may include a 1-bit extension (a total of 3 bits) to the TAG ID information in octet 1 to indicate the TAG ID for the in-frequency serving cell, and octet 2 of the extended MAC CE 1420 may include a 1-bit indicator (a total of 3 bits) to indicate the TAG ID for either the in-frequency serving cell or the in-frequency non-serving cell.

[0081] One or more of the techniques described in this specification may include one or more of various methods or solutions for maintaining multiple UL timings for a plurality of cell-inter TRPs having different PCIs. This may include scenarios where a single base station includes an antenna array capable of operating as a plurality of TRPs having different PCIs, and / or scenarios where a plurality of base stations provide services to a specific cell or coverage area, and each base station functions as one or more TRPs having different PCIs. In such scenarios, separate TAGs (e.g., TAG IDs) may be assigned to serving cells and non-serving cells.

[0082] In some implementations, the TAG ID associated with an intra-frequency non-serving cell (e.g., base station 122-2) can be explicitly configured by the serving cell (e.g., base station 122-1) via RRC signaling. The TAG ID of the non-serving cell can be provided after the UE110 executes the CFRA procedure and obtains an initial TA value for the non-serving cell (e.g., via the RAR message). In other implementations, the TAG ID associated with an intra-frequency non-serving cell (e.g., base station 122-2) can be implicitly determined by the UE110 based on the TAG ID of the intra-frequency serving cell (e.g., base station 122-1). The TAG IDs for the intra-frequency serving cell and non-serving cell can be represented by the TAG nonServing parameter. The TAG ID for the intra-frequency serving cell can be identified as the TAG Serving parameter. The total number of TAGs for the serving cells across the frequency(S) can be determined as follows (TAG nonServing =TAG Serving +S). For example, assume that two TAGs are configured for the serving cells of the serving base station using TAG 0 and TAG 1. Then, the TAG ID "X" for the intra-frequency non-serving cell on the same frequency as the serving cell in TAG 0 is calculated as X = 0 + 2 = 2. Thus, TAG 2 can be used for these non-serving cells for TA updates. Similarly, the TAG ID "Y" for the intra-frequency non-serving cell on the same frequency as the serving cell of TAG 1 is calculated as Y = 1 + 2 = 3. Thus, TAG 2 can be used for these non-serving cells for TA updates.

[0083] In other implementations, one to four (or more) TAGs can be used for both the intra-frequency component carrier (CC) and the inter-frequency component carrier (CC) for a given UE110 so that the existing TAC MAC CE can be reused to update the TA value. In other implementations, the extended TAC MAC CE can be used to extend the maximum number of TAGs from 4 to 8 (e.g., by adding additional TAG ID bits as shown in the extended MAC CE 1410 of FIG. 14). In such an implementation, the extended TAC MAC CE can be identified by a MAC sub-header having a dedicated logical channel ID. In other implementations, the associated TAG can be implicitly indicated by a CORESET that includes scheduling the DCI of the TAC MAC CE. An example of this will be described below with reference to the following figures.

[0084] FIG. 15 is a diagram of an example 1500 of a search space associated with CORESETs of different TRPs according to one or more implementations described herein. TRP 1 may correspond to base station 122-1, and TRP 2 may correspond to base station 122-2. As shown, the TRP 1 search space (SS) having a CORESET (including a coresetPoolIndex value of 0) may include the search space SS_1.3 in the first slot, SS_1.4 in the second slot, etc., up to SS 1.M (where M is 5 or more). The second slot may also include SS_2.2 having a CORESET (including a coresetPoolIndex value of 1) of TRP 2. SS 1.3, 1.4, and 1.M may indicate a TA or TAG for the serving cell TRP. SS 2.2 can indicate a TA or TAG for a non-serving cell. Thus, when the UE110 receives DCI in a CORESET having a coresetPoolIndex value of 0, the UE110 may apply the TA and / or TAG to the serving cell. In contrast, when the UE110 receives DCI in a CORESET having a coresetPoolIndex value of 1, the UE110 may apply the TA and / or TAG to the non-serving cell.

[0085] Referring to FIG. 14, a single TAG can be applied for both in - frequency serving cells and non - serving cells. In such an implementation, for a serving cell and a non - serving cell operating at a given frequency, two TA values can be separately indicated for each TAG. The extended MAC CE 1420 in FIG. 14 includes an example of a MAC CE configured to indicate a single TAG ID and TA information (in octet 1) and to indicate whether the TAG ID and TA information are applied to a serving cell or a non - serving cell (in octet 2). Thus, the extended MAC CE 1420 in FIG. 14 can enable the indication of two TA values for each TAG (e.g., with respect to whether the MAC CE corresponds to a serving cell or a non - serving cell). In some implementations, for serving cells and non - serving cells, two TA values can be separately and implicitly indicated for each TAG. For example, when UE110 receives DCI in a CORESET with a coresetPoolIndex value of 0, UE110 can apply the TA and / or TAG to the serving cell. In contrast, when UE110 receives DCI in a CORESET with a coresetPoolIndex value of 1, UE110 can apply the TA and / or TAG to the non - serving cell. Thus, the techniques described herein include various methods and solutions for maintaining UL timing (e.g., TA information) for inter - TRP between multiple cells with different PCIs through the use of TAGs.

[0086] FIG. 16 is a diagram of an example of components of a device according to one or more implementations described herein. In some implementations, device 1600 may include at least an integrated application circuit configuration 1602, a baseband circuit configuration 1604, an RF circuit configuration 1606, a front-end module (FEM) circuit configuration 1608, one or more antennas 1610, and a power management circuitry (PMC) 1612, as at least shown. The illustrated components of device 1600 may be included in a UE or a RAN node. In some implementations, device 1600 may include fewer elements (e.g., a RAN node may not utilize application circuit configuration 1602 and instead may include a processor / controller that processes IP data received from a CN such as 5GC 130 or an evolved packet core (EPC)). In some implementations, device 1600 may include additional elements such as, for example, memory / storage, a display, a camera, a sensor (including one or more temperature sensors such as a single temperature sensor, multiple temperature sensors at different locations within device 1600), or an input / output (I / O) interface. In other implementations, the components described below may be included in two or more devices (e.g., the above-described circuit configurations may be separately included in two or more devices in a cloud-RAN (C-RAN) implementation).

[0087] The components of the device of FIG. 16 may be configured and used to enable the UE 110 to execute one or more operations and / or procedures described herein. For example, the components of the device of FIG. 11 (e.g., a processor, a memory, and an interface) enable the UE 110 to communicate a reference signal received power (RSRP) measurement on a non-serving cell corresponding to the non-serving base station 122 to the serving base station 122, receive an instruction to execute a CFRA procedure towards the non-serving base station, and in response to the instruction, communicate a random access (RA) preamble message configured for the CFRA procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, and receive from the non-serving base station a random access response (RAR) message including TA information for communicating on the non-serving cell in response to the RA preamble message.

[0088] The application circuit configuration 1602 may include one or more application processors. For example, the application circuit configuration 1602 may include, but is not limited to, circuit configurations such as one or more single-core processors or multi-core processors. The processor(s) may include any combination of a general-purpose processor and a dedicated processor (e.g., a graphics processor, an application processor, etc.). The processor may be coupled to the memory / storage or may include the memory / storage device, and may be configured to execute instructions stored in the memory / storage to enable various applications or operating systems to be executed on the device 1600. In some implementations, the processor of the application circuit 1602 may be able to process IP data packets received from the EPC.

[0089] The baseband circuit configuration 1604 may include, but is not limited to, circuit configurations such as one or more single-core processors or multi-core processors. The baseband circuit configuration 1604 can include one or more baseband processors or control logics that process the baseband signals received from the reception signal path of the RF circuit configuration 1606 and generate baseband signals for the transmission signal path of the RF circuit configuration 1606. The baseband circuit configuration 1604 can be interfaced with the application circuit configuration 1602 for generating and processing baseband signals and controlling the operation of the RF circuit configuration 1606. For example, in some implementations, the baseband circuit configuration 1604 can include a 3G baseband processor 1604A, a 4G baseband processor 1604B, a 5G baseband processor 1604C, or another baseband processor(s) 1604D for other existing, under-development, or future-developed generations (e.g., 2G, 6G, etc.). The baseband circuit configuration 1604 (e.g., one or more of the baseband processors 1604A - D) can handle various radio control functions that enable communication with one or more wireless networks via the RF circuit configuration 1606. In other implementations, some or all of the functions of the baseband processors 1604A - D may be included in modules stored in the memory 1604G and executed via the Central Processing Unit (CPU) 1604E. The radio control functions can include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some implementations, the modulation / demodulation circuit configuration of the baseband circuit configuration 1604 can include Fast-Fourier Transform (FFT), precoding, or constellation mapping / demapping functionality. In some implementations, the encoding / decoding circuit configuration of the baseband circuit configuration 1604 can include convolution, tail-biting convolution, turbo, Viterbi, or Low-Density Parity Check (LDPC) encoder / decoder functionality.The implementation forms of modulation / demodulation and encoder / decoder functionality are not limited to these examples, and other implementation forms may include other suitable functionality.

[0090] In some implementation forms, the baseband circuit configuration 1604 may include one or more audio digital signal processors (Digital Signal Processor, DSP) 1604F. The audio DSP(s) 1604F may include elements for compression / decompression and echo cancellation, and in other implementation forms, may include other suitable processing elements. The components of the baseband circuit configuration may be suitably combined within a single chip, a single chipset, or, in some implementation forms, may be arranged on the same circuit board. In some implementation forms, some or all of the components of the composition of the baseband circuit configuration 1604 and the application circuit configuration 1602 may be integrally implemented, for example, on a System On a Chip (SOC).

[0091] In some implementation forms, the baseband circuit configuration 1604 can provide communication compatible with one or more wireless technologies. For example, in some implementation forms, the baseband circuit configuration 1604 can support communication with NG-RAN, Evolved Universal Terrestrial Radio Access Network (EUTRAN), or other wireless metropolitan area network (WMAN), Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN), etc. Implementation forms in which the baseband circuit configuration 1604 is configured to support wireless communication of two or more wireless protocols can be called multi-mode baseband circuit configurations.

[0092] The RF circuit configuration 1606 can enable communication with a wireless network using modulated electromagnetic radiation via a non-solid medium. In various implementation forms, the RF circuit configuration 1606 can include switches, filters, amplifiers, etc. to facilitate communication with the wireless network. The RF circuit configuration 1606 can include a received signal path that may include a circuit configuration for down-converting an RF signal received from the FEM circuit configuration 1608 and providing a baseband signal to the baseband circuit configuration 1604. The RF circuit configuration 1606 can also include a transmitted signal path that may include a circuit configuration for up-converting a baseband signal provided by the baseband circuit configuration 1604 and providing an RF output signal for transmission to the FEM circuit configuration 1608.

[0093] In some implementations, the receive signal path of the RF circuit configuration 1606 can include a mixer circuit configuration 1606A, an amplifier circuit configuration 1606B, and a filter circuit configuration 1606C. In some implementations, the transmit signal path of the RF circuit configuration 1606 can include a filter circuit configuration 1606C and a mixer circuit configuration 1606A. The RF circuit configuration 1606 can also include a synthesizer circuit configuration 1606D that synthesizes the frequencies used by the mixer circuit configuration 1606A of the receive and transmit signal paths. In some implementations, the mixer circuit configuration 1606A of the receive signal path can be configured to down-convert the RF signal received from the FEM circuit configuration 1608 based on the synthesized frequency provided by the synthesizer circuit configuration 1606D. The amplifier circuit configuration 1606B can be configured to amplify the down-converted signal, and the filter circuit configuration 1606C can be a low-pass filter (LPF) or a band-pass filter (BPF) configured to remove unwanted signals from the down-converted signal and generate an output baseband signal. The output baseband signal can be provided to the baseband circuit configuration 1604 for further processing. In some implementations, the output baseband signal can be a zero-frequency baseband signal, but this is not a requirement. In some implementations, the mixer circuit configuration 1606A of the receive signal path can include a passive mixer, but the scope of the implementations is not limited in this regard.

[0094] In some implementations, the mixer circuit configuration 1606A of the transmit signal path can be configured to up-convert an input baseband signal based on the synthesized frequency provided by the synthesizer circuit configuration 1606D and generate an RF output signal for the FEM circuit configuration 1608. The baseband signal can be provided by the baseband circuit configuration 1604 and can also be filtered by the filter circuit configuration 1606C.

[0095] In some implementations, the mixer circuit configuration 1606A of the receive signal path and the mixer circuit configuration 1606A of the transmit signal path may include two or more mixers, and may be arranged for quadrature downconversion and quadrature upconversion respectively. In some implementations, the mixer circuit configuration 1606A of the receive signal path and the mixer circuit configuration 1606A of the transmit signal path may include two or more mixers, and may be arranged for image rejection (e.g., Hartley image rejection). In some implementations, the mixer circuits 1606A and 906A of the receive signal path may be arranged for direct downconversion and direct upconversion respectively. In some implementations, the mixer circuit configuration 1606A of the receive signal path and the mixer circuit configuration 1606A of the transmit signal path can be configured for superheterodyne operation.

[0096] In some implementations, the output baseband signal and the input baseband signal may be analog baseband signals, but the scope of the implementations is not limited to this point. In some alternative implementations, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative implementations, the RF circuit configuration 1606 may include an Analog-to-Digital Converter (ADC) and a Digital-to-Analog Converter (DAC) circuit configuration, and the baseband circuit configuration 1604 can include a digital baseband interface for communicating with the RF circuit configuration 1606.

[0097] In some dual-mode implementations, separate radio IC circuit configurations may be provided to process the signals of each spectrum, but the scope of the implementations is not limited to this point.

[0098] In some implementations, the synthesizer circuit configuration 1606D may be a fractional-N synthesizer or a fractional-N / N+1 synthesizer, and other types of frequency synthesizers may also be suitable, so the scope of the implementation is not limited in this regard. For example, the synthesizer circuit configuration 1606D may be a synthesizer with a phase-locked loop having a delta-sigma synthesizer, a frequency multiplier, or a frequency divider.

[0099] The synthesizer circuit configuration 1606D can be configured to synthesize the output frequency used by the mixer circuit configuration 1606A of the RF circuit configuration 1606 based on a frequency input and a divider control input. In some implementations, the synthesizer circuit configuration 1606D may be a fractional-N / N+1 synthesizer.

[0100] In some implementations, the frequency input may be provided by a voltage controlled oscillator (VCO), but this is not a requirement. The divider control input can be provided by either the baseband circuit configuration 1604 or the application circuit configuration 1602 according to the desired output frequency. In some implementations, the divider control input (e.g., N) can be determined from a look-up table based on the channel indicated by the application circuit configuration 1602.

[0101] The synthesizer circuit configuration 1606D of the RF circuit configuration 1606 can include a frequency divider, a delay-locked loop (DLL), a multiplexer, and a phase accumulator. In some implementations, the frequency divider may be a dual modulus divider (DMD), and the phase accumulator may be a digital phase accumulator (DPA). In some implementations, the DMD can be configured to divide an input signal by either N or N+1 (e.g., based on execution) to provide a fractional division ratio. In some exemplary implementations, the DLL can include a set of cascaded tunable delay elements, a phase detector, a charge pump, and D-type flip-flops. In these implementations, the delay elements can be configured to divide the VCO period into Nd equal-phase packets, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0102] In some implementations, the synthesizer circuit configuration 1606D can be configured to generate a carrier frequency as the output frequency. In other implementations, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency), and can be used in conjunction with a quadrature generator and a frequency divider circuit configuration to generate multiple signals with carrier frequencies having multiple different phases relative to each other. In some implementations, the output frequency may be the LO frequency (fLO). In some implementations, the RF circuit configuration 1606 can include an IQ / polarity converter.

[0103] The FEM circuit configuration 1608 can include a receive signal path that operates on RF signals received from one or more antennas 1610, amplifies the received signals, and provides an amplified version of the received signals to the RF circuit configuration 1606 for further processing. The FEM circuit configuration 1608 can also include a transmit signal path that includes a circuit configuration configured to amplify signals for transmission provided by the RF circuit configuration 1606 and transmitted by one or more of the one or more antennas 1610. In various implementations, amplification through the transmit or receive signal path may be performed only in the RF circuit configuration 1606, only in the FEM circuit configuration 1608, or in both the RF circuit configuration 1606 and the FEM circuit configuration 1608.

[0104] In some implementations, the FEM circuit 1608 can include a Tx / Rx switch for switching between transmit mode and receive mode operation. The FEM circuit configuration can include a receive signal path and a transmit signal path. The receive signal path of the FEM circuit configuration can include a low noise amplifier (LNA) that amplifies the received RF signal and provides the amplified received RF signal as an output (e.g., to the RF circuit configuration 1606). The transmit signal path of the FEM circuit configuration 1608 can include a power amplifier (PA) that amplifies an input RF signal (e.g., provided by the RF circuit configuration 1606), and one or more filters that generate an RF signal for subsequent transmission (e.g., by one or more of the one or more antennas 1610).

[0105] In some implementations, the PMC 1612 can manage the power supplied to the baseband circuit configuration 1604. Specifically, the PMC 1612 can control power selection, voltage scaling, battery charging, or DC-DC conversion. When the device 1600 is powered by a battery, for example, when this device is included in a UE, the PMC 1612 can often be included. The PMC 1612 can enhance the power conversion efficiency while imparting desirable implementation size and heat dissipation characteristics.

[0106] FIG. 16 shows PMC 1612 coupled only to baseband circuit configuration 1604. However, in other implementations, PMC 1612 can be additionally or alternatively coupled to other components including, but not limited to, application circuit configuration 1602, RF circuit configuration 1606, or FEM circuit configuration 1608 to perform similar power management operations.

[0107] In some implementations, PMC 1612 can control or otherwise be part of various power saving mechanisms of device 1600. For example, if device 1600 is in the RRC_Connected state and is still connected to the RAN node as it is expected to receive traffic soon, after a certain inactive period, the device can enter a state known as discontinuous reception mode (DRX). During this state, device 1600 can save power by powering off at short intervals.

[0108] If there is no data traffic activity for a long period of time, device 1600 can transition to the RRC_Idle state where it disconnects from the network and does not perform operations such as channel quality feedback and handover. Device 1600 enters a very low power state and periodically wakes up to perform paging to listen for the network and then power down again. Device 1600 cannot receive data in this state. To receive data, it can transition back to the RRC_Connected state.

[0109] In an additional power saving mode, the device can be allowed to be unavailable from the network for a period longer than the paging interval (ranging from seconds to hours). During this time, the device cannot reach the network at all and can be completely powered off. Although there will be a significant delay if there is data transmitted during this time, the delay is considered acceptable.

[0110] Using the processors of the application circuit configuration 1602 and the processors of the baseband circuit configuration 1604, elements of one or more instances of the protocol stack can be executed. For example, the processors of the baseband circuit configuration 1604 can be used alone or in combination to execute the functionality of layer 3, layer 2, or layer 1, and the processors of the application circuit configuration 1604 can utilize the data (e.g., packet data) received from these layers to further execute the functionality of layer 4 (e.g., the Transmission Communication Protocol (TCP) layer and the User Datagram Protocol (UDP) layer). As described above in this specification, layer 3 can include the RRC layer, which will be described in more detail below. As described above in this specification, layer 2 can include the medium access control (MAC) layer, the radio link control (RLC) layer, and the packet data convergence protocol (PDCP) layer, which will be described in more detail below. As described above in this specification, layer 1 can include the Physical (PHY) layer of the UE / RAN node, which will be described in more detail below.

[0111] FIG. 17 is a diagram showing an exemplary interface of a baseband circuit configuration according to one or more implementations described herein. As described above, the baseband circuit configuration 1604 of FIG. 16 can include processors 1604A to 1604E and a memory 1604G utilized by these processors. Each of the processors 1604A to 1604E can include a memory interface 1704A to 1704E for transmitting and receiving data to and from the memory 1604G, respectively.

[0112] UE110 may use one or more components of FIG. 17 to perform one or more operations for the processes described herein. For example, UE110 may use one or more processors 1604A - 1604E, memory interfaces 1704A - 1704E, and memory 1604G to communicate a reference signal received power (RSRP) measurement on a non - serving cell corresponding to non - serving base station 122 to serving base station 122, receive an instruction to execute a CFRA procedure towards the non - serving base station, and in response to the instruction, communicate a random access (RA) preamble message configured for the CFRA procedure associated with the non - serving cell of the non - serving base station to the non - serving base station, and receive from the non - serving base station a random access response (RAR) message including TA information for communicating on the non - serving cell in response to the RA preamble message.

[0113] The baseband circuit 1604 may further include one or more interfaces for communicatively coupling to other circuits / devices, such as a memory interface 1712 (e.g., an interface for transmitting / receiving data between the baseband circuit 1604 and an external memory), an application circuit interface 1714 (e.g., an interface for transmitting / receiving data between the application circuit 1602 of FIG. 16), an RF circuit interface 1716 (e.g., an interface for transmitting / receiving data between the RF circuit 1606 of FIG. 16), a wireless hardware connection interface 1718 (e.g., an interface for transmitting / receiving data between near - field communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi - Fi® components, and other communication components), and a power management interface 1709 (e.g., an interface for transmitting / receiving power or control signals between PMC 1612).

[0114] FIG. 18 is a block diagram showing components that can read instructions from a machine-readable medium or a computer-readable medium (e.g., a non-transitory machine-readable storage medium) and execute any one or more of the methodologies described herein. Specifically, FIG. 18 includes one or more processors (or processor cores) 1810, one or more memory / storage devices 1820, and one or more communication resources 1830, each of which may be communicatively coupled via a bus 1840, showing a schematic representation of hardware resources 1800. In embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 1802 may be executed to provide an execution environment for one or more network slices / sub-slices for utilizing the hardware resources 1800.

[0115] UE 110 and base station 122 may use one or more components of FIG. 18 to perform one or more operations for the processes described herein. For example, the processor 1810, instructions 1850, memory / storage device 1820, and communication resource 1830 may communicate a reference signal received power (RSRP) measurement on a non-serving cell corresponding to the non-serving base station 122 by the UE to the serving base station 122, receive instructions for executing a CFRA procedure towards the non-serving base station, and in response to the instructions, communicate a random access (RA) preamble message configured for the CFRA procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, and in response to the RA preamble message, receive from the non-serving base station a random access response (RAR) message including TA information for communicating on the non-serving cell.

[0116] The processor 1810 (e.g., a digital signal processor (DSP) such as a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a baseband processor, an application specific integrated circuit (ASIC), a radio frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, processor 1812 and processor 1814.

[0117] The memory / storage device 1820 may include main memory, disk storage, or any suitable combination thereof. The memory / storage device 1820 may include any type of volatile or non-volatile memory, including but not limited to dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid state storage, and the like.

[0118] The communication resource 1830 may include an interconnect or network interface component or other suitable device for communicating with one or more peripheral devices 1804 or one or more databases 1806 via the network 1808. For example, the communication resource 1830 may include a wired communication component (for coupling via, e.g., a universal serial bus (USB)), a cellular communication component, an NFC component, a Bluetooth® component (e.g., Bluetooth® Low Energy), a Wi-Fi® component, and other communication components.

[0119] Instruction 1850 may include software, a program, an application, an applet, an app, or other executable code for causing at least any one of processors 1810 to execute any one or more of the methodologies described herein. Instruction 1850 may be wholly or partially present within at least one of processors 1810 (e.g., within the cache memory of the processor), within memory / storage device 1820, or within any suitable combination thereof. Further, any portion of Instruction 1850 may be transferred from any combination of peripheral devices 1804 or database 1806 to hardware resource 1800. Accordingly, the memory of processor 1810, memory / storage device 1820, peripheral devices 1804, and database 1806 are examples of computer-readable media and machine-readable media.

[0120] Examples herein can include subject matter such as a method, means for performing actions or blocks of the method, at least one machine-readable medium including executable instructions that, when executed by a machine (e.g., a processor with memory such as a processor, an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), etc.), cause the machine to perform actions of a method or apparatus or system for simultaneous communication using multiple communication techniques according to the described implementations and examples.

[0121] In Example 1, which may also include one or more of the examples described herein, the baseband processor of a user equipment (UE) communicates a reference signal received power (RSRP) measurement on a non-serving cell corresponding to a non-serving base station to the serving base station, receives an instruction to perform a contention-free random access (CFRA) procedure towards the non-serving base station, and in response to the instruction, communicates a random access (RA) preamble message configured for the CFRA procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, and in response to the RA preamble message, may include one or more processors configured to receive a random access response (RAR) message including timing advance (TA) information for communication on the non-serving cell from the non-serving base station.

[0122] In Example 2, which may also include one or more of the examples described herein, the instruction is received via a search space (SS) associated with the non-serving cell. In Example 3, which may also include one or more of the examples described herein, the one or more processors are further configured to communicate an indication of successful completion of the CFRA procedure to the non-serving cell to the serving base station in response to the RAR message. In Example 4, which may also include one or more of the examples described herein, the instruction includes downlink (DL) control information (DCI) received from the non-serving base station. In Example 5, which may also include one or more of the examples described herein, the DCI is received in response to the RSRP measurement being transferred by the serving base station to the non-serving base station.

[0123] In Example 6, which may also include one or more of the examples described herein, the instruction includes DCI received from a serving base station. In Example 7, which may also include one or more of the examples described herein, the DCI is transmitted in a control resource set (CORESET) configured with a coresetPoolIndex value associated with a non-serving cell of a non-serving base station. In Example 8, which may also include one or more of the examples described herein, the DCI includes a target cell ID (TCI) of a non-serving cell of a non-serving base station. In Example 9, which may also include one or more of the examples described herein, the DCI includes a physical cell ID (PCI) of a non-serving cell.

[0124] In Example 10, which may also include one or more of the examples described herein, radio resource control (RRC) signaling is used to provide a dedicated target cell ID (TCI) value for a non-serving cell having a physical cell ID (PCI), and the DCI is used to indicate the TCI value to the UE to perform a CFRA procedure for a non-serving cell of a non-serving base station associated with the TCI value. In Example 11, which may also include one or more of the examples described herein, the instruction includes a media access control (MAC) control element (CE) that activates at least one transmission configuration indicator state for a PDSCH of a non-serving cell. In Example 12, which may also include one or more of the examples described herein, the instruction includes radio resource control (RRC) signaling to provide dedicated physical random access channel (PRACH) resources for each SSB of a non-serving cell, and the media access control (MAC) control element (CE) is used to trigger a CFRA procedure and a corresponding PRACH transmission to a non-serving cell.

[0125] In Example 13, which may also include one or more of the examples described herein, a baseband processor of a user equipment (UE) communicates a reference signal received power (RSRP) measurement on a non-serving cell corresponding to a non-serving base station to a serving base station, receives a dedicated random access channel (RACH) resource corresponding to the non-serving cell of the non-serving base station from the serving base station in response to the RSRP measurement, monitors at least one condition for performing a contention-free random access (CFRA) procedure towards the non-serving base station, and when at least one condition is satisfied, communicates a random access (RA) preamble message configured for the CFRA procedure on the non-serving cell of the non-serving base station, and in response to the RA preamble message, is configured to receive from the non-serving base station a random access response (RAR) message including timing advance (TA) information for communicating on the non-serving cell of the non-serving base station, and may include one or more processors.

[0126] In Example 14, which may also include one or more of the examples described herein, the dedicated RACH resource is provided to be associated with a system synchronization block (SSB) of a channel state information (CSI) reference signal (RS) (CSI-RS) of a non-serving cell of a non-serving base station. In Example 15, which may also include one or more of the examples described herein, an RSRP threshold SSB or an RSRP threshold CSI-RS for a non-serving cell is configured and used to determine whether at least one condition of the CFRA procedure is satisfied. In Example 16, which may also include one or more of the examples described herein, an RSRP measurement based on an SSB or a CSI-RS transmitted on a non-serving cell is used to determine whether a condition is satisfied by comparing the RSRP measurement with the RSRP threshold SSB or the RSRP threshold CSI-RS.

[0127] In Example 17, which may also include one or more of the examples described herein, a baseband processor of a user equipment (UE) communicates a reference signal received power (RSRP) measurement on a non-serving cell corresponding to a non-serving base station to a serving base station, communicates a random access (RA) preamble message configured for a contention-free random access (CFRA) procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, and, in response to the RA preamble message, is configured to receive from the non-serving base station a random access response (RAR) message including timing advance (TA) information for communicating on the non-serving cell of the non-serving base station, and may include one or more processors.

[0128] In Example 18, which may also include one or more of the examples described herein, a type 1 physical downlink control channel (PDCCH) common search space (CSS) (type 1-PDCCH CSS) on a non-serving cell of a non-serving base station is monitored to receive an RAR message from the non-serving base station. In Example 19, which may also include one or more of the examples described herein, the configuration of the type 1-PDCCH CSS of the non-serving cell is received from a serving cell of a serving base station before the UE communicates an RA preamble message. In Example 20, which may also include one or more of the examples described herein, the configuration of the type 1-PDCCH CSS of the non-serving cell is determined based on the configuration of the type 1-PDCCH CSS of the serving cell.

[0129] In Example 21, which may also include one or more of the examples described herein, the serving cell's type 1-PDCCH CSS is monitored to receive a RAR message associated with a RA preamble message transmitted towards a non-serving cell. In Example 22, which may also include one or more of the examples described herein, the TA information includes the differential TA value of the non-serving cell with respect to the TA value of the serving cell of the serving base station. In Example 23, which may also include one or more of the examples described herein, the serving cell of the serving base station and the non-serving cell of the non-serving base station correspond to different Timing Advance Groups (TAGs).

[0130] In Example 24, which may also include one or more of the examples described herein, the TAG ID of the non-serving cell of the non-serving base station is explicitly configured by the serving base station via Radio Resource Control (RRC) signaling. In Example 25, which may also include one or more of the examples described herein, the TAG ID of the non-serving cell of the non-serving base station is implicitly determined by the UE based on the TAG ID of the serving cell of the serving base station and the total number of TAGs of the serving cell of the serving base station over a specific frequency. In Example 26, which may also include one or more of the examples described herein, the number of TAGs configured for the non-serving cell and the serving cell is limited to a maximum of 4. In Example 27, which may also include one or more of the examples described herein, the TA information is provided via a Timing Advance Command (TAC) Media Access Control (MAC) Control Element (CE) with a 3-bit TAG ID field. In Example 28, which may also include one or more of the examples described herein, the cell between the serving cell to which the TA information is applied and the corresponding non-serving cell is explicitly indicated by a 1-bit field within the MAC-CE.

[0131] The above description of the illustrated embodiments, implementations, aspects, etc. of the disclosed subject matter, including the content described in the abstract, is not intended to be exhaustive or to limit the disclosed aspects to the exact form disclosed. Specific examples, implementations, aspects, etc. are described herein for illustrative purposes, but one of ordinary skill in the art will recognize that various modifications within the scope of such examples, implementations, aspects, etc. are possible.

[0132] In this regard, although the disclosed subject matter has been described in connection with various examples, implementations, aspects, etc. and corresponding drawings, it should be understood that other similar aspects can be used or modifications and additions can be made to the disclosed subject matter without departing from the disclosed subject matter, in order to perform the same, similar, alternative, or substitute functions. Accordingly, the disclosed subject matter should not be limited to any single example, implementation, aspect described herein, but rather should be construed in accordance with the breadth and scope of the following appended claims.

[0133] Specifically, with respect to the various functions performed by the above-described components or structures (assemblies, devices, circuits, systems, etc.), the terms used to describe such components (including descriptions related to "means") are intended to correspond to any component or structure that performs the specific function of the described component, even if not structurally equivalent to the disclosed structure that performs the functions of the exemplary implementations of the invention illustrated herein (e.g., functionally equivalent), unless otherwise specified. Further, although a particular feature may be disclosed with respect to only one of several implementations, such a feature may be combined with one or more other features of one or more other implementations so as to be desirable and advantageous for any given or particular application.

[0134] As used herein, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X uses A or B" is intended to mean any of all possible permutations. That is, in the case where "X uses A", in the case where "X uses B", or in the case where "X uses both A and B", each of the foregoing cases satisfies "X uses A or B". In addition, the articles "a" and "an" used in this application and the appended claims should generally be construed to mean "one or more" unless otherwise specified or it is clear from the context that they refer to the singular form. Further, when "including", "includes", "having", "has", "with", or variations thereof are used in either the embodiments of the invention or the claims, these terms are intended to be as inclusive as the term "comprising". Further, in situations where one or more numbered items (e.g., "first X", "second X", etc.) are described, generally, these one or more numbered items may be distinct or the same, but in some situations, the context may indicate whether the one or more numbered items are distinct or the same.

[0135] It should be well understood that the use of personally identifiable information should comply with privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled to minimize the risk of unintended or unauthorized access or use, and the nature of the permitted use should be clearly shown to the user.

Claims

1. A baseband processor of a user equipment (UE), comprising: one or more processors, wherein the one or more processors: communicate a reference signal received power (RSRP) measurement value on a non-serving cell corresponding to a non-serving base station to a serving base station; receive an instruction to execute a contention-free random access (CFRA) procedure towards the non-serving base station; in response to the instruction, communicate a random access (RA) preamble message configured for the CFRA procedure associated with the non-serving cell of the non-serving base station to the non-serving base station; and are configured to receive, from the non-serving base station, a random access response (RAR) message including timing advance (TA) information for communication on the non-serving cell in response to the RA preamble message.

2. The baseband processor according to claim 1, wherein the instruction is received via a search space (SS) associated with the non-serving cell.

3. The baseband processor according to claim 1, wherein the one or more processors are further configured to: in response to the RAR message, communicate an indication of normal completion of the CFRA procedure to the serving base station for the non-serving cell.

4. The baseband processor according to claim 1, wherein the instruction includes downlink (DL) control information (DCI) received from the non-serving base station.

5. The baseband processor according to claim 4, wherein the DCI is received in response to the RSRP measurement value being transferred by the serving base station to the non-serving base station.

6. The baseband processor according to claim 1, wherein the instruction includes DCI received from the serving base station.

7. The baseband processor according to claim 6, wherein the DCI is transmitted in a control resource set (CORESET) configured with a core set Pool Index value associated with the non-serving cell of the non-serving base station.

8. The baseband processor according to claim 6, wherein the DCI includes a target cell ID (TCI) of the non-serving cell of the non-serving base station.

9. The baseband processor according to claim 6, wherein the DCI includes a physical cell ID (PCI) of the non-serving cell.

10. Radio resource control (RRC) signaling is used to provide a dedicated target cell ID (TCI) value for a non-serving cell having a physical cell ID (PCI), and the DCI is used to indicate the TCI value to the UE for executing the CFRA procedure towards the non-serving cell of the non-serving base station associated with the TCI value. The baseband processor according to claim 6.

11. The baseband processor according to claim 1, wherein the command includes a media access control (MAC) control element (CE) that activates at least one transmission configuration indicator state for a physical downlink shared channel (PDSCH) of a non-serving cell.

12. The command includes radio resource control (RRC) signaling for providing dedicated physical random access channel (PRACH) resources for each SSB of the non-serving cell, and a media access control (MAC) control element (CE) is used to trigger the CFRA procedure and the corresponding PRACH transmission to the non-serving cell. The baseband processor according to claim 1.

13. A baseband processor of a user equipment (UE), Comprising one or more processors, the one or more processors Communicate a reference signal received power (RSRP) measurement value on a non-serving cell corresponding to a non-serving base station to a serving base station, Receive dedicated random access channel (RACH) resources corresponding to the non-serving cell of the non-serving base station from the serving base station in response to the RSRP measurement value, Monitor at least one condition for executing a contention-free random access (CFRA) procedure towards the non-serving base station, When the at least one condition is satisfied, communicate a random access (RA) preamble message configured for the CFRA procedure on the non-serving cell of the non-serving base station. A baseband processor configured to receive, from the non-serving base station, a random access response (RAR) message including timing advance (TA) information for communicating on the non-serving cell of the non-serving base station in response to the RA preamble message.

14. The baseband processor according to claim 13, wherein the dedicated RACH resource is provided to be associated with a system synchronization block (SSB) of a channel state information (CSI) reference signal (RS) (CSI-RS) of the non-serving cell of the non-serving base station.

15. The baseband processor according to claim 14, wherein an RSRP threshold SSB or an RSRP threshold CSI-RS for the non-serving cell is configured and used to determine whether the at least one condition of the CFR A procedure is satisfied.

16. The baseband processor according to claim 15, wherein the RSRP measurement value based on the SSB or CSI-RS transmitted on the non-serving cell is used to determine whether the condition is satisfied by comparing the RSRP measurement value with the RSRP threshold SSB or the RSRP threshold CSI-RS.

17. A baseband processor of a user equipment (UE), comprising one or more processors, the one or more processors communicate a reference signal received power (RSRP) measurement value on a non-serving cell corresponding to a non-serving base station to a serving base station, communicate a random access (RA) preamble message configured for a contention-free random access (CFRA) procedure associated with the non-serving cell of the non-serving base station to the non-serving base station, A baseband processor configured to receive, from the non-serving base station, a random access response (RAR) message including timing advance (TA) information for communicating on the non-serving cell of the non-serving base station in response to the RA preamble message.

18. To receive the RAR message from the non-serving base station, a Type 1 (Type1) physical downlink control channel (PDCCH) common search space (CSS) (Type 1-PDCCH CSS) on the non-serving cell of the non-serving base station is monitored. The baseband processor according to claim 17.

19. The configuration of the Type 1-PDCCH CSS of the non-serving cell is received from the serving cell of the serving base station before the UE communicates the RA preamble message. The baseband processor according to claim 17.

20. The configuration of the Type 1-PDCCH CSS of the non-serving cell is determined based on the configuration of the Type 1-PDCCH CSS of the serving cell. The baseband processor according to claim 17.

21. The Type 1-PDCCH CSS of the serving cell is monitored to receive the RAR message associated with the RA preamble message transmitted to the non-serving cell. The baseband processor according to claim 17.

22. The TA information includes a differential TA value of the non-serving cell with respect to the TA value of the serving cell of the serving base station. The baseband processor according to claim 17.

23. The serving cell of the serving base station and the non-serving cell of the non-serving base station correspond to different timing advance groups (TAGs). The baseband processor according to claim 22.

24. The TAG ID of the non-serving cell of the non-serving base station is explicitly configured by the serving base station via radio resource control (RRC) signaling. The baseband processor according to claim 23.

25. The TAG ID of the non-serving cell of the non-serving base station is implicitly determined by the UE based on the TAG ID of the serving cell of the serving base station and the total number of TAGs of the serving cell of the serving base station over a specific frequency. The baseband processor according to claim 23.

26. The number of TAGs configured for the non-serving cell and the serving cell is limited to a maximum of 4. The baseband processor according to claim 23.

27. The baseband processor according to claim 23, wherein the TA information is provided via a timing advance command (TAC) media access control (MAC) control element (CE) having a 3-bit TAG ID field.

28. The baseband processor according to claim 23, wherein a cell between a serving cell to which the TA information is applied and a corresponding non-serving cell is explicitly indicated by a 1-bit field in the MAC-CE.

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