Ordered contention based random access for candidate cells

Abstract

Certain aspects of the present disclosure provide techniques for ordered contention based random access for candidate cells. An example method performed at a wireless node includes obtaining a signal indicating that the wireless node is to transmit a physical random access channel (PRACH) to a candidate cell; selecting a synchronization signal (SS) index of the candidate cell; and outputting the PRACH for transmission using a resource associated with the selected SS index.

Description

Background Technology Technical Field

[0001] Various aspects of this disclosure relate to wireless communications, and more specifically to techniques for ordered contention-based random access for candidate cells.

[0002] Related technical descriptions

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunications services, such as telephone, video, data, messaging, broadcasting, or other similar services. These wireless communication systems may employ multiple access technologies that enable communication with multiple users by sharing available wireless communication system resources.

[0004] Despite significant technological advancements in wireless communication systems over the years, challenges remain. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and receivers. Therefore, there is a continuous expectation for improving the technical performance of wireless communication systems, including, for example: improving communication speed and data carrying capacity; improving the efficiency of shared communication media; reducing the power used by transmitters and receivers during communication; improving the reliability of wireless communication; avoiding redundant transmission and / or reception and related processing; improving the coverage area of ​​wireless communication; increasing the number and types of devices that can access the wireless communication system; increasing the ability of different types of devices to communicate with each other; and increasing the number and types of available wireless communication media. Therefore, there is a need for further improvements to wireless communication systems to overcome the aforementioned technical challenges and other obstacles. Summary of the Invention

[0005] One aspect provides a method for wireless communication at a wireless node. The method includes: obtaining a signal indicating that the wireless node intends to transmit a Physical Random Access Channel (PRACH) to a candidate cell; selecting a synchronization signal (SS) index for the candidate cell; and using resources associated with the selected SS index to output the PRACH for transmission.

[0006] On the other hand, a method for wireless communication at a first wireless node is provided. The method includes: outputting a signal instructing a second wireless node to transmit a Physical Random Access Channel (PRACH) to a candidate cell; and obtaining the PRACH using resources associated with a synchronization signal (SS) index of the candidate cell selected by the second wireless node.

[0007] Other aspects provide: an apparatus capable of operating to, being configured to, or otherwise adapted to perform one or more of the foregoing methods and / or those methods described elsewhere herein; a non-transitory computer-readable medium including instructions that, when executed by a processor of the apparatus, cause the apparatus to perform the foregoing methods and those methods described elsewhere herein; a computer program product embodied on a computer-readable storage medium including code for performing the foregoing methods and those methods described elsewhere herein; and / or an apparatus including components for performing the foregoing methods and those methods described elsewhere herein. By way of example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating via one or more networks.

[0008] For illustrative purposes, the following description and figures illustrate certain features. Attached Figure Description

[0009] The accompanying drawings depict certain features of the various aspects described herein and should not be considered as limiting the scope of this disclosure.

[0010] Figure 1 An example wireless communication network is depicted.

[0011] Figure 2 An example decomposed base station architecture is described.

[0012] Figure 3 Various aspects of the example base station and example user equipment are described.

[0013] Figure 4A , Figure 4B , Figure 4C and Figure 4D Various example aspects of data structures used in wireless communication networks are described.

[0014] Figure 5 A call flowchart depicting the four-step Random Access Channel (RACH) process is provided.

[0015] Figure 6 An example of UE mobility is depicted.

[0016] Figure 7 An example scenario with a pre-configured set of candidate cells is depicted.

[0017] Figure 8 An example scenario with a pre-configured set of candidate cells and Physical Downlink Control Channel (PDCCH) commands is depicted.

[0018] Figure 9A call flowchart illustrating ordered contention-based random access for candidate cells according to certain aspects of this disclosure is depicted.

[0019] Figure 10 An example scenario is depicted, based on certain aspects of this disclosure, featuring a pre-configured set of candidate cells and physical downlink control channel (PDCCH) commands.

[0020] Figure 11 A first example of contention-based random access (CBRA) physical random access channel (PRACH) transmission triggered by a PDCCH command according to certain aspects of this disclosure is depicted.

[0021] Figure 12 A second example of contention-based random access (CBRA) physical random access channel (PRACH) transmission triggered by a PDCCH command according to certain aspects of this disclosure is depicted.

[0022] Figure 13 A third example of contention-based random access (CBRA) physical random access channel (PRACH) transmission triggered by a PDCCH command according to certain aspects of this disclosure is described.

[0023] Figure 14 A method for wireless communication is described.

[0024] Figure 15 A method for wireless communication is described.

[0025] Figure 16 Various aspects of the example communication device are described. Detailed Implementation

[0026] This disclosure provides apparatus, methods, processing systems, and computer-readable media for transmitting ordered contention-based random access (CBRA) physical random access channel (PRACH) from a radio node on a candidate cell.

[0027] In advanced wireless systems, when a user equipment (UE) moves between coverage areas of different cells, mobility procedures appropriately help maintain the network connectivity of that UE. Mobility procedures generally refer to mechanisms that allow a UE to switch from service from a source cell to service from a destination cell.

[0028] In some cases, for the physical layer (PHY or Layer 1 / L1) and / or media access control layer (MAC or Layer 2 / L2) (also known as L1 / L2 triggered mobility (LTM)), when the UE moves, a new serving cell (e.g., primary cell (Pcell)) can be selected (e.g., reselected) from a pre-configured set of candidate cells based on the L1 measurements of those cells. To save time for advance timing (TA) acquisition, the UE can transmit a PRACH to the target candidate cell for TA measurement before the target candidate cell is selected as the new serving cell.

[0029] In some systems, PRACH transmissions triggered (commanded) via the Physical Downlink Control Channel (PDCCH) may be permitted only in candidate cells used for LTM. In such cases, PRACH transmissions triggered by the PDCCH command can be contention-free, using the RACH timing (RO) of the SSB index indicated in the PDCCH command. However, in some situations, contention-based random access (CBRA) PRACH transmissions may be useful.

[0030] For example, if the network has limited knowledge of the Synchronization Signal Block (SSB) that will be used for the PRACH, it might be better to send the CBRA PRACH based on the SSB selected by the UE. The CBRA process may encounter multiple UEs transmitting in the same RO. To resolve this contention, the Random Access Response (RAR) transmitted after the PRACH provides contention resolution information. Unfortunately, some systems may not be configured for RAR. Therefore, CBRA PRACH transmission may have unresolved conflict issues between different UEs.

[0031] This disclosure provides various aspects of techniques for supporting CBRA PRACH transmission in LTM scenarios. In some cases, contention resolution information can be provided even in systems without RAR configuration. By utilizing the techniques presented herein, CBRA-based PRACH transmission can be used with UE-selected SSB, which improves LTM mobility and user quality of experience (QoE).

[0032] An introduction to wireless communication networks

[0033] The techniques and methods described herein can be used in a variety of wireless communication networks. While aspects may be described herein using terms commonly associated with 3G, 4G, and / or 5G wireless technologies, aspects of this disclosure are equally applicable to other communication systems and standards not explicitly mentioned herein.

[0034] Figure 1 An example of a wireless communication network 100 in which the aspects described herein can be implemented is depicted.

[0035] Generally, wireless communication network 100 includes various network entities (optionally, network elements or network nodes). Network entities are typically communication devices and / or communication functions performed by communication devices (e.g., user equipment (UE), base station (BS), components of a BS, servers, etc.). For example, various functions of the network and various devices associated with and interacting with the network can be considered network entities. Furthermore, wireless communication network 100 includes terrestrial aspects, such as terrestrial network entities (e.g., BS 102), and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include onboard network entities (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipment.

[0036] In the depicted example, wireless communication network 100 includes BS 102, UE 104, and one or more core networks (such as Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190) that interoperate to provide communication services over various communication links, including wired and wireless links.

[0037] Figure 1 Various example UE 104s are described, which may more generally include: cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players, cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electricity meters, air pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, Internet of Things (IoT) devices, always-on (AON) devices, edge processing devices, or other similar devices. UE 104 may also be more generally referred to as mobile devices, wireless communication devices, stations, mobile stations, subscriber stations, mobile subscriber stations, mobile units, subscriber units, wireless units, remote units, remote devices, access terminals, mobile terminals, wireless terminals, remote terminals, mobile phones, and others.

[0038] BS102 communicates wirelessly with UE 104 via communication link 120 (e.g., transmitting or receiving signals to or from UE 104). Communication link 120 between BS102 and UE 104 may include uplink (UL) transmission (also referred to as reverse link) from UE 104 to BS102 and / or downlink (DL) transmission (also referred to as forward link) transmission from BS102 to UE 104. In various aspects, communication link 120 may utilize multiple-input multiple-output (MIMO) antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity.

[0039] BS102 may typically include: NodeB, enhanced NodeB (eNB), next-generation enhanced NodeB (ng-eNB), next-generation NodeB (gNB or gNodeB), access point, transceiver base station, radio base station, radio transceiver, transceiver functionality, transmit / receive point, and / or others. Each BS in BS102 may provide communication coverage for a corresponding geographic coverage area 110, which may sometimes be referred to as a cell, and in some cases may overlap (e.g., a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of a macro cell). For example, a BS may provide communication coverage for macro cells (covering a relatively large geographic area), pico cells (covering a relatively small geographic area, such as a stadium), femtocells (covering a relatively small geographic area (e.g., a home)), and / or other types of cells.

[0040] Although the BS102 is described as a single communication device in various aspects, it can be implemented in a variety of configurations. For example, one or more components of the base station can be decomposed, including a central unit (CU), one or more distributed units (DU), one or more radio units (RU), a near-real-time (near-RT) RAN intelligent controller (RIC), or a non-real-time (non-RT) RIC, to name a few. In another example, various aspects of the base station can be virtualized. More generally, a base station (e.g., the BS102) can include components located at a single physical location or components located at various physical locations. In examples where the base station includes components located at various physical locations, the various components can each perform functions, such that the various components collectively achieve functionality similar to a base station located at a single physical location. In some aspects, a base station including components located at various physical locations can be referred to as a decomposed radio access network architecture (such as an open RAN (O-RAN) or virtualized RAN (VRAN) architecture). Figure 2 An example decomposed base station architecture is depicted and described.

[0041] Different BS102s within the wireless communication network 100 can also be configured to support different radio access technologies (such as 3G, 4G, and / or 5G). For example, a BS102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with EPC 160 via a first backhaul link 132 (e.g., the S1 interface). A BS102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) can interface with 5GC 190 via a second backhaul link 184. BS102s can communicate directly or indirectly with each other (e.g., via EPC 160 or 5GC 190) on a third backhaul link 134 (e.g., the X2 interface), which can be wired or wireless.

[0042] Wireless communication network 100 can subdivide the electromagnetic spectrum into various categories, bands, channels, or other characteristics. In some aspects, subdivision is provided based on wavelength and frequency, where frequency may also be referred to as carrier, subcarrier, channel, tone, or subband. For example, 3GPP currently defines frequency range 1 (FR1) as including 410MHz-7125MHz, which is often (interchangeably) referred to as “sub-6GHz”. Similarly, 3GPP currently defines frequency range 2 (FR2) as including 24250MHz-52600MHz, which is sometimes (interchangeably) referred to as “millimeter wave” (“mmW” or “mmWave”). Base stations configured to communicate using mmWave / near mmWave radio bands (e.g., mmWave base stations such as BS180) can utilize beamforming (e.g., 182) with UEs (e.g., 104) to improve path loss and range.

[0043] The communication link 120 between BS102 and, for example, UE 104 can be via one or more carriers, which may have different bandwidths (e.g., 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, 400MHz and / or other MHz) and may be aggregated in various ways. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL).

[0044] Compared to lower-frequency communication, communication using higher frequency bands may have higher path loss and shorter range. Therefore, some base stations (e.g., Figure 1The beamforming 180 of BS 180 and UE 104 can be used with UE 104 to improve path loss and range. For example, BS 180 and UE 104 may each include multiple antennas, such as antenna elements, antenna panels, and / or antenna arrays, to facilitate beamforming. In some cases, BS 180 may transmit beamformed signals to UE 104 in one or more transmit directions 182'. UE 104 may receive beamformed signals from BS 180 in one or more receive directions 182'. UE 104 may also transmit beamformed signals to BS 180 in one or more transmit directions 182'. BS 180 may also receive beamformed signals from UE 104 in one or more receive directions 182'. BS 180 and UE 104 may then perform beamforming training to determine the optimal receive and transmit directions for each of BS 180 and UE 104. It is worth noting that the transmit and receive directions of BS 180 may be the same or different. Similarly, the sending and receiving directions of UE 104 can be the same or different.

[0045] The wireless communication network 100 also includes a Wi-Fi AP 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in, for example, unlicensed spectrum in 2.4 GHz and / or 5 GHz.

[0046] Some UEs 104 may use device-to-device (D2D) communication link 158 to communicate with each other. The D2D communication link 158 may use one or more sidelink channels, such as physical sidelink broadcast channel (PSBCH), physical sidelink discovery channel (PSDCH), physical sidelink shared channel (PSSCH), physical sidelink control channel (PSCCH), and / or physical sidelink feedback channel (PSFCH).

[0047] EPC 160 may include various functional components, including: Mobility Management Entity (MME) 162, other MMEs 164, Serving Gateway 166, Multimedia Broadcast Multicast Service (MBMS) Gateway 168, Broadcast Multicast Service Center (BM-SC) 170, and / or Packet Data Network (PDN) Gateway 172, as in the illustrated example. MME 162 may communicate with Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connectivity management.

[0048] Generally, user Internet Protocol (IP) packets are transmitted through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP service 176, which may include, for example, the Internet, intranet, IP Multimedia Subsystem (IMS), packet-switched (PS) streaming service, and / or other IP services.

[0049] The BM-SC 170 provides functions for MBMS user service dispatch and delivery. The BM-SC 170 can serve as an entry point for content provider MBMS transmissions, can be used to authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and / or can be used to schedule MBMS transmissions. The MBMS gateway 168 can be used to distribute MBMS services to BS102 within a Broadcast-Specific Service Single Frequency Network (MBSFN) area, and / or can be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0050] 5GC 190 may include various functional components, including: Access and Mobility Management Function (AMF) 192, other AMFs 193, Session Management Function (SMF) 194, and User Plane Function (UPF) 195. AMF 192 can communicate with Unified Data Management (UDM) 196.

[0051] AMF 192 is the control node that handles signaling between UE 104 and 5GC 190. AMF 192 provides services such as Quality of Service (QoS) flow and session management.

[0052] Internet Protocol (IP) packets are transmitted via UPF 195, which connects to IP service 197 and provides the UE with IP address allocation and other functions for 5GC 190. IP service 197 may include, for example, the Internet, intranet, IMS, PS streaming service, and / or other IP services.

[0053] In various aspects, to give a few examples, network entities or network nodes can be implemented as aggregated base stations, decomposed base stations, components of base stations, integrated access and backhaul (IAB) nodes, relay nodes, and sidelink nodes.

[0054] Figure 2An example decomposed base station 200 architecture is depicted. The decomposed base station 200 architecture may include one or more central units (CUs) 210, which may communicate directly with the core network 220 via a backhaul link, or indirectly with the core network 220 through one or more decomposed base station units (such as a near real-time (near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a non-real-time (non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) framework 205, or both). CUs 210 may communicate with one or more distributed units (DUs) 230 via corresponding midhaul links (such as F1 interfaces). DUs 230 may communicate with one or more radio units (RUs) 240 via corresponding fronthaul links. RUs 240 may communicate with a corresponding UE 104 via one or more radio frequency (RF) access links. In some implementations, UE 104 may be served simultaneously by multiple RUs 240.

[0055] Each unit in a cell (e.g., CU 210, DU 230, RU 240, and near-RT RIC 225, non-RT RIC 215, and SMO frame 205) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each unit in the cell, or an associated processor or controller providing instructions to the unit's communication interface, may be configured to communicate with one or more other units via a transmission medium. For example, these units may include wired interfaces configured to receive signals or transmit signals to one or more other units via a wired transmission medium. Additionally or alternatively, a unit may include a wireless interface that may include a receiver, transmitter, or transceiver (such as a radio frequency (RF) transceiver) configured to receive signals via a wireless transmission medium or transmit signals to one or more other units, or both.

[0056] In some aspects, CU 210 can host one or more higher-level control functions. Such control functions may include Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Serving Data Adaptation Protocol (SDAP), etc. Each control function can be implemented using an interface configured to signal with other control functions hosted by CU 210. CU 210 can be configured to handle user plane functions (e.g., Central Unit-User Plane (CU-UP)), control plane functions (e.g., Central Unit-Control Plane (CU-CP)), or combinations thereof. In some implementations, CU 210 can be logically divided into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, CU-UP units can communicate bidirectionally with CU-CP units via an interface (such as an E1 interface). CU 210 can be implemented to communicate with DU 230 for network control and signaling, as needed.

[0057] DU 230 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RU 240s. In some aspects, DU 230 may host one or more of the Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) at least in part according to functional splits (such as those defined by the 3rd Generation Partnership Project (3GPP). In some aspects, DU 230 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface configured to signal communication with other layers (and modules) hosted by DU 230 or with control functions hosted by CU 210.

[0058] Lower-layer functionality can be implemented by one or more RU 240s. In some deployments, an RU240 controlled by a DU 230 may correspond to a logical node that hosts RF processing functions or low-PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction and filtering, or both, based at least in part on functional decomposition (such as lower-layer functional decomposition). In such architectures, the RU 240 may be implemented to handle over-the-air (OTA) communications with one or more UE 104s. In some specific implementations, the real-time and non-real-time aspects of control plane and user plane communications with the RU 240 may be controlled by the corresponding DU 230. In some scenarios, this configuration enables the implementation of the DU 230 and CU 210 in a cloud-based RAN architecture (such as a vRAN architecture).

[0059] SMO framework 205 can be configured to support RAN deployment and provisioning of both non-virtualized and virtualized network elements. For non-virtualized network elements, SMO framework 205 can be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which can be managed via operation and maintenance interfaces such as the O1 interface. For virtualized network elements, SMO framework 205 can be configured to interact with a cloud computing platform such as Open Cloud (O-Cloud) 290 to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface such as the O2 interface. Such virtualized network elements may include, but are not limited to, CU 210, DU 230, RU 240, and near-RT RIC 225. In some implementations, SMO framework 205 can communicate with the hardware aspects of the 4G RAN (such as Open eNB (O-eNB) 211) via the O1 interface. Additionally, in some implementations, SMO framework 205 can communicate directly with one or more RU 240s via the O1 interface. SMO framework 205 may also include a non-RT RIC 215 configured to support the functionality of SMO framework 205.

[0060] The non-RT RIC 215 can be configured to include logical functions enabling non-real-time control and optimization of RAN elements and resources, including artificial intelligence / machine learning (AI / ML) workflows for model training and updates, or policy-based guidance for applications / features in the near-RT RIC 225. The non-RT RIC 215 can be coupled to or communicate with the near-RT RIC 225 (e.g., via an A1 interface). The near-RT RIC 225 can be configured to include logical functions enabling near real-time control and optimization of RAN elements and resources via an interface (e.g., via an E2 interface) through data collection and action, connecting one or more CU 210s, one or more DU 230s, or both, and O-eNBs to the near-RT RIC 225.

[0061] In some implementations, to generate AI / ML models to be deployed in the near-RT RIC 225, the non-RT RIC 215 may receive parameters or external enrichment information from an external server. This information can be utilized by the near-RT RIC 225 and can be received from non-network data sources or network functions at the SMO framework 205 or the non-RT RIC 215. In some examples, the non-RT RIC 215 or the near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 215 may monitor long-term trends and patterns in performance and employ AI / ML models to perform corrective actions via the SMO framework 205 (such as reconfiguration via O1) or via the creation of RAN management policies (such as A1 policies).

[0062] Figure 3 Various aspects of examples BS102 and UE 104 are described.

[0063] Generally, BS102 includes various processors (e.g., 320, 330, 338, and 340), antennas 334a-334t (collectively referred to as 334), transceivers 332a-332t (collectively referred to as 332) including modulators and demodulators, and other aspects that enable the wireless transmission of data (e.g., data source 312) and the wireless reception of data (e.g., data sink 339). For example, BS102 can transmit and receive data between BS102 and UE 104. BS102 includes a controller / processor 340 that can be configured to implement the various functions described herein related to wireless communication.

[0064] Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380), antennas 352a-352r (collectively referred to as 352), transceivers 354a-354r (collectively referred to as 354) including modulators and demodulators, and other aspects that enable the wireless transmission of data (e.g., retrieved from data source 362) and the wireless reception of data (e.g., provided to data sink 360). UE 104 includes a controller / processor 380 that can be configured to implement the various functions described herein related to wireless communication.

[0065] Regarding example downlink transmission, BS102 includes a transmission processor 320 that can receive data from data source 312 and control information from controller / processor 340. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical HARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Group Shared PDCCH (GC PDCCH), and / or others. In some examples, the data may be for the Physical Downlink Shared Channel (PDSCH).

[0066] The transmitter processor 320 can process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmitter processor 320 can also generate reference symbols (such as those for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS)).

[0067] The transmit (TX) multiple-input multiple-output (MIMO) processor 330 can perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols where applicable, and can provide the output symbol stream to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t can process its corresponding output symbol stream to obtain an output sample stream. Each modulator can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signal from the modulators in transceivers 332a-332t can be transmitted via antennas 334a-334t respectively.

[0068] To receive downlink transmissions, UE 104 includes antennas 352a-352r that receive downlink signals from BS 102 and provide the received signals to demodulators (DEMODs) in transceivers 354a-354r respectively. Each demodulator in transceivers 354a-354r can adjust (e.g., filter, amplify, down-convert, and digitize) the corresponding received signal to obtain an input sample. Each demodulator can further process the input sample to obtain the received symbols.

[0069] The MIMO detector 356 acquires received symbols from all demodulators in transceivers 354a-354r, performs MIMO detection on the received symbols where applicable, and provides the detected symbols. The receive processor 358 processes (e.g., demodulates, deinterleaves, and decodes) the detected symbols, provides the decoded data for UE 104 to data sink 360, and provides the decoded control information to controller / processor 380.

[0070] Regarding example uplink transmission, UE 104 also includes a transmit processor 364 that receives and processes data from data source 362 (e.g., for PUSCH) and control information from controller / processor 380 (e.g., for Physical Uplink Control Channel (PUCCH)). Transmit processor 364 can also generate reference symbols for reference signals (e.g., for Sounding Reference Signal (SRS)). Symbols from transmit processor 364 may be pre-decoded by TX MIMO processor 366, where applicable, further processed by modulators in transceivers 354a-354r (e.g., for SC-FDM), and transmitted to BS 102.

[0071] At BS102, uplink signals from UE 104 can be received by antennas 334a-334t, processed by demodulators in transceivers 332a-332t, detected by MIMO detector 336 where applicable, and further processed by receiver processor 338 to obtain decoded data and control information transmitted by UE 104. Receiver processor 338 can provide the decoded data to data sink 339 and the decoded control information to controller / processor 340.

[0072] Memory 342 and memory 382 can store data and program code for BS102 and UE 104, respectively.

[0073] Scheduler 344 can schedule UE to transmit data on the downlink and / or uplink.

[0074] In various respects, BS102 can be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, "transmitting" can refer to various mechanisms that output data, such as from data source 312, scheduler 344, memory 342, transmit processor 320, controller / processor 340, TX MIMO processor 330, transceiver 332a-332t, antenna 334a-334t, and / or other aspects described herein. Similarly, "receiving" can refer to various mechanisms that acquire data, such as from antenna 334a-334t, transceiver 332a-332t, RX MIMO detector 336, controller / processor 340, receive processor 338, scheduler 344, memory 342, and / or other aspects described herein.

[0075] In various respects, UE 104 can also be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” can refer to various mechanisms that output data, such as from data source 362, memory 382, ​​transmit processor 364, controller / processor 380, TX MIMO processor 366, transceiver 354a-354t, antenna 352a-352t, and / or other aspects described herein. Similarly, “receiving” can refer to various mechanisms that acquire data, such as from antenna 352a-352t, transceiver 354a-354t, RX MIMO detector 356, controller / processor 380, receive processor 358, memory 382, ​​and / or other aspects described herein.

[0076] In some respects, the processor can be configured to perform various operations (such as those associated with the methods described herein) and to send (output) data to or receive data from another interface configured to send or receive data, respectively.

[0077] Figure 4A , Figure 4B , Figure 4C and Figure 4D Describes the use of wireless communication networks (such as Figure 1 All aspects of the data structure of the wireless communication network 100.

[0078] Specifically, Figure 4A Figure 400 illustrates an example of the first subframe within a 5G (e.g., 5G NR) frame structure. Figure 4B Figure 430 illustrates an example of a DL channel within a 5G subframe. Figure 4C Figure 450 illustrates an example of the second subframe within a 5G frame structure, and Figure 4D Figure 480 illustrates an example of a UL channel within a 5G subframe.

[0079] Wireless communication systems can utilize Orthogonal Frequency Division Multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink. Such systems can also support half-duplex operation using Time Division Duplex (TDD). OFDM and Single-Carrier Frequency Division Multiplexing (SC-FDM) will (e.g., as...) Figure 4B and Figure 4D The system bandwidth described herein is divided into multiple orthogonal subcarriers. Each subcarrier can be modulated with data. Modulation symbols can be transmitted in the frequency domain using OFDM and / or in the time domain using SC-FDM.

[0080] Wireless communication frame structures can be frequency division duplex (FDD), where for a specific set of subcarriers, subframes within that set are dedicated to either deep (DL) or ultra-low (UL). Wireless communication frame structures can also be time division duplex (TDD), where for a specific set of subcarriers, subframes within that set are dedicated to both DL and UL.

[0081] exist Figure 4A and Figure 4C In this example, the wireless communication frame structure is TDD, where D stands for DL, U for UL, and X is flexibly used between DL and UL. The UE can configure the time slot format via the received Slot Format Indicator (SFI) (dynamically configured via DL Control Information (DCI) or semi-statically / statically configured via Radio Resource Control (RRC) signaling). In the depicted example, a 10ms frame is divided into 10 equal-sized 1ms subframes. Each subframe may include one or more time slots. In some examples, each time slot may include 7 or 14 symbols, depending on the time slot format. Subframes may also include micro-slots, which typically have fewer symbols than the entire time slot. Other wireless communication technologies may have different frame structures and / or different channels.

[0082] In some respects, the number of slots within a subframe is based on the slot configuration and parameter set. For example, for slot configuration 0, different parameter sets (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow for 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and parameter set μ, there are 14 symbols / slots and 2μ slots / subframes. Subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2μ × 15kHz, where μ is parameter set 0 to 5. Therefore, parameter set μ = 0 has a subcarrier spacing of 15kHz, and parameter set μ = 5 has a subcarrier spacing of 480kHz. Symbol length / duration is negatively correlated with subcarrier spacing. Figure 4A , Figure 4B , Figure 4C and Figure 4D Examples are provided for slot configuration 0 with 14 symbols per slot and parameter set μ=2 with 4 slots per subframe. The slot duration is 0.25ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67μs.

[0083] like Figure 4A , Figure 4B , Figure 4C and Figure 4DAs depicted, the resource grid can be used to represent the frame structure. Each time slot includes a resource block (RB) (also known as a physical RB (PRB)) extending for, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0084] like Figure 4A As illustrated in the example, some REs in the RE carry information for the UE (e.g., Figure 1 and Figure 3 The reference (pilot) signal (RS) for the UE (104) may include a demodulation RS (DMRS) and / or a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and / or a phase tracking RS (PT-RS).

[0085] Figure 4B Examples of various DL channels within a subframe of a frame are illustrated. The Physical Downlink Control Channel (PDCCH) carries the DCI within one or more Control Channel Elements (CCEs), each CCE comprising, for example, nine RE groups (REGs), each REG comprising, for example, four consecutive REs in an OFDM symbol.

[0086] The Primary Synchronization Signal (PSS) can be located within symbol 2 of a specific subframe of the frame. The PSS is generated by the UE (e.g., Figure 1 and Figure 3 104) is used to determine subframe / symbol timing and physical layer identifier.

[0087] The Secondary Synchronization Signal (SSS) can be located in symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identifier group number and radio frame timing.

[0088] Based on the Physical Layer Identifier and Physical Layer Cell Identifier Group Number, the UE can determine the Physical Cell Identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DMRS. The Physical Broadcast Channel (PBCH), carrying the Master Information Block (MIB), can be logically grouped with the PSS and SSS to form a Synchronization Signal (SS) / PBCH block. The MIB provides the System Frame Number (SFN) and the number of Restricted Blocks (RBs) in the system bandwidth. The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information (such as System Information Blocks (SIBs)) not transmitted via the PBCH, and / or paging messages.

[0089] like Figure 4CAs illustrated, some REs in the REs carry DMRS for channel estimation at the base station (indicated as R for a particular configuration, but other DMRS configurations are possible). The UE can transmit DMRS for PUCCH and DMRS for PUSCH. PUSCH DMRS can be transmitted, for example, in the first or second symbol before the PUSCH. PUCCH DMRS can be transmitted in different configurations depending on whether a short or long PUCCH is being transmitted and depending on the specific PUCCH format used. UE104 can transmit a Sounding Reference Signal (SRS). SRS can be transmitted, for example, in the last symbol of a subframe. SRS can have a comb structure, and the UE can transmit SRS on one of the comb teeth. SRS can be used by the base station for channel quality estimation to enable frequency-dependent scheduling of the UL.

[0090] Figure 4D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH can be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), pre-decoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry buffer status reports (BSR), power clearance reports (PHR), and / or UCI.

[0091] Example RACH procedure

[0092] The Random Access Channel (RACH) is so named because it refers to a radio channel (medium) that can be shared by multiple UEs and used by these UEs to (randomly) access the network for communication. For example, RACH can be used for call setup and network access for data transmission. In some situations, RACH can be used for initial network access when a UE switches from Radio Resource Control (RRC) connection idle mode to active mode, or when switching within RRC connection mode. Furthermore, RACH can be used for downlink (DL) and / or uplink (UL) data arrival when a UE is in RRC idle or RRC inactive mode, and when re-establishing a connection with the network.

[0093] Figure 5Figure 500 illustrates a timing (or “call flow”) diagram of an example four-step RACH procedure according to certain aspects of this disclosure. A first message (MSG1) may be transmitted from the UE to a network entity (e.g., a BS such as a gNB) on the Physical Random Access Channel (PRACH). In this case, MSG1 may consist only of the RACH preamble. The network entity may respond with a Random Access Response (RAR) message (MSG2), which may include an identifier (ID) of the RACH preamble, timing advance (TA), uplink grant, cell radio network temporary identifier (C-RNTI), and fallback indicator. MSG2 may include PDCCH communication, which includes control information regarding subsequent communication on the PDSCH, as illustrated. In response to MSG2, MSG3 is sent from the UE to the network entity on the PUSCH. MSG3 may include one or more of the following: an RRC connection request, a tracking area update request, a system information request, a location lock or location signal request, or a scheduling request. The network entity then responds with MSG4, which may include a contention resolution message.

[0094] In some cases, a two-step RACH process can be supported to speed up access. As the name suggests, a two-step RACH process can effectively "break down" the four messages of a four-step RACH process into two messages.

[0095] Overview of Mobility Based on Dynamic Signaling

[0096] As noted above, dynamic mobility signaling (e.g., L1 and / or L2-centric mobility or LTM) enables more efficient intra-cell and inter-cell mobility and reduces latency.

[0097] For general concepts of LTM signaling, please refer to [link / reference]. Figure 6 To understand this, refer to the example scenario 600 shown in the figure. As illustrated, the network can (e.g., via RRC signaling) configure a set of cells for L1 / L2 mobility (referred to herein as the L1 / L2 mobility configuration cell set). At any given time, the network can also (via L1 / L2 signaling) configure an L1 / L2 mobility active cell set, which refers to the group of cells in the configuration set that are active and readily available for data and control transfer. The network can also configure (signal) an L1 / L2 mobility deactivation cell set, which refers to the group of cells in the configuration set that are deactivated and readily available for activation by L1 / L2 signaling.

[0098] L1 / L2 signaling can be used to activate mobility management within a set. For example, L1 / L2 signaling can be used to activate / deactivate cells in the set, select beams within the active cell, and update / handover the primary cell (PCell). This dynamic signaling helps provide seamless mobility within the active cells of the set. In other words, when the UE moves, cells from the set are deactivated and activated via L1 / L2 signaling. Cells to be activated and deactivated can be based on various factors, such as signal quality (measurements) and load.

[0099] As in Figure 6 In the examples illustrated, in some cases, all cells in the L1 / L2 mobility configuration cell set may belong to the same DU 630 of CU 610. This can be similar to carrier aggregation (CA), but the cells may be on the same carrier frequency. The size of the cell set configured for L1 / L2 mobility signaling can vary. Generally, the cell set size can be chosen to be large enough to cover meaningful mobility areas.

[0100] In some cases, the UE may be provided with a subgroup of deactivated cells as a candidate cell group, from which the UE can autonomously select cells to add to the active cell group. The decision to add cells from the candidate cell set to the active cell set can be based on various factors, such as measured channel quality and load information. In some cases, when configured for Conditional Handover (CHO) to quickly and efficiently add ready cells, the UE's ability to autonomously select cells to add to the active cell set can be similar to a UE decision.

[0101] like Figure 6 As illustrated, each cell can be served by an RU. Each RU within an RU can have multiple carriers (N CCs) supporting it. In this case, each CC can be a cell (e.g., cell 2 and cell 2' can be different CCs of the same RU). In this case, activation / deactivation can be performed within the carrier group (cell).

[0102] For PCell management, L1 / L2 signaling can be used to set (select) a PCell from pre-configured options within the active cell set. In some cases, when the new PCell does not come from the active cell set used for L1 / L2 mobility, L3 mobility can be used for PCell change (L3 handover). In this case, during L3 handover, RRC signaling can update the cell set used for L1 / L2 mobility.

[0103] In some cases, measurements can be taken at the L1 / L2 mobility enhancement physical layer (Layer 1 or L1), where the serving cell can be changed via L1 / L2 signaling based on L1 measurements, and both synchronous and asynchronous source and target cells can be considered.

[0104] Various mechanisms and procedures for L1 / L2-based inter-cell mobility can be specified to reduce mobility latency. These may include the configuration and maintenance of multiple candidate cells to allow for rapid application of candidate cell configurations. For potential application scenarios based on L1 / L2 signaling, dynamic handover mechanisms between candidate serving cells (including SpCell and SCell) can be supported.

[0105] L1 enhancements for inter-cell beam management may include L1 measurement and reporting, as well as beam indication. Timing advance (TA) management and CU-DU interface signaling may also be provided to support L1 / L2 mobility.

[0106] L1 / L2-based inter-cell mobility procedures can be applied to a variety of scenarios. These scenarios may include independent, CA, and new radio dual connectivity (NR-DC) scenarios with changes in serving cell within a cell group (CG), intra-distributed cell (DU) scenarios and inter-DU scenarios within a central cell (CU), intra-frequency and inter-frequency scenarios, FR1 and FR2 scenarios, and scenarios where the source cell and target cell can be synchronized or desynchronized.

[0107] Overview of DCI PRACH Triggering

[0108] like Figure 7 As illustrated in scenario 700, UE 104 can move between a pre-configured set of 710 candidate cells. In the illustrated example, the UE moves from a first cell (e.g., the old serving / primary cell) to a new serving candidate cell. In this case, the UE may not receive data or control information in the candidate cells, but may send PRACH to facilitate timing adjustments for the new candidate cells before the cell change.

[0109] PRACH triggering from network entities can be based on higher-layer signaling (e.g., RRC), or in some cases, on lower-layer signaling such as the Physical Downlink Control Channel (PDCCH).

[0110] Figure 8 Scenario 800 illustrates an example in which a PRACH transmission from UE 104 for uplink (UL) timing in a candidate cell can be triggered via a PDDCH that delivers downlink control information (DCI) from the serving cell.

[0111] In some cases, RACH can be triggered via PDCCH. This can be referred to as PRACH transmission of a PDCCH command. The PDCCH command can be transmitted from the source cell (currently serving) to trigger RACH transmission in the target candidate cell.

[0112] The PDCCH command can indicate a target candidate (e.g., candidate cell 2 in the illustrated example). As illustrated, the PDCCH command can also indicate the SSB (index) that the UE can use as a reference for PRACH transmission. In other words, the UE can transmit PRACH on the Random Access Channel (RACH) timing (RO) (time and frequency resources) associated with the SSB index indicated in the PDCCH command.

[0113] Various aspects related to ordered contention-based random access for candidate cells

[0114] As noted above, in systems that only allow PRACH transmissions triggered via PDCCH commands, contention-free PRACH transmissions are typically triggered. However, there may be some situations where contention-based random access (CBRA) PRACH transmissions would be useful. For example, if the network has limited knowledge of the SSB that will be used for PRACH transmissions, allowing CBRACH based on the SSB selected by the UE may be beneficial.

[0115] Unfortunately, some systems may not be configured for a Random Access Response (RAR), which provides information for contention resolution (e.g., in the case of another UE transmitting in the same RO). Therefore, CBRAPRACH transmission may experience conflict issues between different UEs. This disclosure provides aspects of techniques for supporting CBRAPRACH transmission in LTM scenarios. In some cases, contention resolution information can be provided even in systems without RAR configuration.

[0116] In some cases, the UE may receive a signal (e.g., a PDCCH command) instructing the radio node to transmit a Physical Random Access Channel (PRACH) to a candidate cell. The UE may use resources (e.g., time / frequency resources of the RO) associated with the SS index selected by the UE to output the PRACH for transmission.

[0117] The techniques presented herein provide CBRA PRACH transmissions to or from radio nodes in candidate cells. As used herein, the term radio node generally refers to any type of device capable of wireless communication, such as a UE or network entity, such as a base station (e.g., gNB) or a fragmented base station entity (e.g., RU, CU, or DU). The terms radio node and radio device are used interchangeably.

[0118] For reference Figure 9 Use the example call flowchart 900 to understand the mechanism presented in this article for triggering CBRAPRACH transmission in candidate cells.

[0119] In some respects, Figure 9 The UE shown in the figure can be relative to Figure 1 and Figure 3 An example of UE 104 depicted and described. In some respects, it can be controlled via network entities. Figure 9 The candidate cells and / or serving cells shown in the diagram, the network entity can be relative to Figure 1 and Figure 3 Examples of BS102 depicted and described (e.g., gNB) or relative to Figure 2 Decomposed base stations are depicted and described. For example, candidate cells and serving cells can be controlled by DU and / or CU (e.g., Figure 6 exemplified).

[0120] As illustrated at 902, the serving cell can transmit a PDCCH command instructing the UE to send a CBRAPRACH to the candidate cell. As illustrated at 904, the UE can select the SSB to use instead of using the SSB indicated in the PDCCH command (to determine the RO) to transmit the CBRAPRACH.

[0121] As illustrated at 906, the UE can then transmit PRACH in the RO associated with the SSB selected by the UE. The candidate cell can receive the PRACH on the time and frequency resources of the RO. In some cases, the network can determine the timing advance (TA) value based on the PRACH. Providing this information to the UE can help facilitate mobility to the target candidate cell.

[0122] In this way, when no legacy RAR is configured, the UE can be triggered by the DCI (delivered via the PDCCH command) to send the CBRA PRACH of the candidate cell in LTM.

[0123] like Figure 10 As illustrated in Example Scenario 1000, in some cases, the PDCCH command for the CBRA PRACH in the candidate cell can be indicated by setting the value of the random access preamble index field of the candidate cell to a certain value (e.g., a value reserved to trigger CBRA PRACH transmission). For example, in the illustrated example, the random access preamble index field of the candidate cell is set to zero in the PDCCH command.

[0124] In some cases, CBRA PRACH transmission can be triggered by a group common DCI. For example, such a group common DCI may include a dedicated field for the candidate cell that indicates to the UE that it wants to transmit the CBRA PRACH for the candidate cell.

[0125] According to some aspects, when a UE is triggered by a DCI sent by a CBRA PRACH of a candidate cell in LTM, the UE can still receive a response for contention resolution if no RAR is configured for the candidate cell.

[0126] For example, such as Figure 11 As illustrated in Example Scenario 1100, a response (with contention resolution information) can be received in the serving cell. Alternatively, or otherwise, as... Figure 12 As illustrated in example scenario 1200, a response (with contention resolution information) can be received in a candidate cell.

[0127] Contention resolution responses may be sent via at least one of the following: a Media Access Control (MAC) control element (CE) or control information. The response may indicate various types of information used for contention resolution. For example, the response may indicate at least one of the following: UEID, Timing Advance (TA) command, or SSB index.

[0128] like Figure 13 As illustrated in Example Scenario 1300, in some cases, contention resolution information can be transmitted in a second PDCCH command that triggers a retransmission of the received CBRA PRACH. Contention resolution information can be helpful when two UEs (UE1 and UE2) are transmitting CBRA PRACH in the RO based on the same selected SSB.

[0129] For example, the first PDCCH command can trigger a CBRA PRACH for UE1 in the candidate cell. In response, UE1 can send a CBRA PRACH with the UE's selected SSB and RO. UE2 may sometimes send a CBRA PRACH in the same RO and SSB, which conflicts with the CBRA PRACH transmission from UE1.

[0130] like Figure 13 As illustrated, a second PDCCH command can trigger a retransmission of the same PRACH, where the same SSB is selected for the initial PRACH transmission.

[0131] In some cases, a contention resolution response can be sent without UE2 receiving it. For example, a second PDCCH command can be scrambled by UE1's cell-specific radio network temporary identifier (C-RNTI).

[0132] Following the retransmission of the PRACH, in response to the second PDCCH, UE 1 can receive a timing adjustment (TA) indication. By utilizing the techniques proposed herein, CBRA-based PRACH transmission can be used with UE-selected SSBs, which improves LTM mobility and user quality of experience (QoE).

[0133] Example Operation

[0134] Figure 14 This shows a wireless node (such as...) Figure 1 and Figure 3 An example of a method 1400 for wireless communication at UE 104.

[0135] Method 1400 begins at step 1405, where a signal instructing the radio node to transmit the Physical Random Access Channel (PRACH) to the candidate cell is obtained. In some cases, this step refers to the operation as described in reference... Figure 16 The circuit and / or code described for obtaining, or that can be executed by the circuit and / or the code.

[0136] Then, method 1400 proceeds to step 1410, where the synchronization signal (SS) index of the candidate cell is selected. In some cases, this step refers to the operation as described in reference... Figure 16 The circuitry and / or code described for selection, or that can be executed by the circuitry and / or the code.

[0137] Then, method 1400 proceeds to step 1415, where the resource associated with the selected SS index is used to output a PRACH for transmission. In some cases, this step refers to the operation as described in the reference... Figure 16 The circuitry and / or code described for the output, or the code that can be executed by the circuitry and / or the code.

[0138] In some respects, resources include time and frequency resources for the Random Access Channel (RACH) timing (RO) associated with the selected SS index.

[0139] In some respects, candidate cells belong to a group of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

[0140] In some respects, the signaling includes the Physical Downlink Control Channel (PDCCH), which contains indications of candidate cells.

[0141] In some respects, the PDCCH also includes a random access preamble index field, which is set to indicate to the radio node the value of the PRACH to be transmitted in the RO associated with the SSB selected by the UE.

[0142] In some respects, the PDCCH transmits group common control information that instructs the radio node to use resources associated with the SS index selected by the radio node to send the PRACH.

[0143] In some aspects, method 1400 further includes: obtaining a response to PRACH, wherein the response indicates information for contention resolution. In some cases, this step refers to operations as described in reference... Figure 16The circuit and / or code described for obtaining, or that can be executed by the circuit and / or the code.

[0144] In some respects, the response is obtained from at least one of the following: the serving cell or the candidate cell.

[0145] In some respects, the response is obtained via at least one of the following: a Media Access Control (MAC) control element (CE) or control information.

[0146] In some respects, the response indicates at least one of the following: UE ID, timing advance (TA) command, or SS index.

[0147] In some aspects, method 1400 also includes: using a resource associated with the SS index indicated in the response to output another PRACH for transmission. In some cases, this step refers to the operation as described in the reference... Figure 16 The circuitry and / or code described for the output, or the code that can be executed by the circuitry and / or the code.

[0148] In some respects, the SS index indicated in the response is the same as the SS index selected by the wireless node.

[0149] In one aspect, method 1400 or any aspect thereof may be made by means of a device (such as...) Figure 16 The communication device 1600 performs the execution, and the device includes various components capable of operating, being configured, or adapted to perform the method 1400. The communication device 1600 is described in more detail below.

[0150] It should be noted that Figure 14 This is merely one example of a method, and other methods that include fewer, additional, or alternative steps may also be consistent with this disclosure.

[0151] Figure 15 It is shown in the first wireless node (such as Figure 1 and Figure 3 At BS102) or as relative to Figure 2 An example of the method 1500 for wireless communication at the decomposed base station discussed.

[0152] Method 1500 begins at step 1505, where an output instructs the second radio node to transmit a Physical Random Access Channel (PRACH) signal to the candidate cell. In some cases, this step refers to the operation as described in reference... Figure 16 The circuitry and / or code described for the output, or the code that can be executed by the circuitry and / or the code.

[0153] Then, method 1500 proceeds to step 1510, where a PRACH is obtained using resources associated with the synchronization signal (SS) index of the candidate cell selected by the second radio node. In some cases, this step refers to the operation as described in reference... Figure 16 The circuit and / or code described for obtaining, or that can be executed by the circuit and / or the code.

[0154] In some respects, resources include time and frequency resources for the Random Access Channel (RACH) timing (RO) associated with the selected SS index.

[0155] In some respects, candidate cells belong to a group of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

[0156] In some respects, the signaling includes the Physical Downlink Control Channel (PDCCH), which contains indications of candidate cells.

[0157] In some respects, the PDCCH also includes a random access preamble index field, which is set to indicate to the radio node the value of the PRACH to be transmitted in the RO associated with the SSB selected by the UE.

[0158] In some respects, the PDCCH transmits group common control information that instructs the radio node to use resources associated with the SS index selected by the radio node to send the PRACH.

[0159] In some aspects, method 1500 further includes: outputting a response to PRACH to a second wireless node, wherein the response indicates information for contention resolution. In some cases, this step refers to the operation as described in reference... Figure 16 The circuitry and / or code described for the output, or the code that can be executed by the circuitry and / or the code.

[0160] In some respects, the response is output from at least one of the following: the serving cell or the candidate cell.

[0161] In some respects, the response is output via at least one of the following: a Media Access Control (MAC) control element (CE) or control information.

[0162] In some respects, the response indicates at least one of the following: UE ID, timing advance (TA) command, or SS index.

[0163] In some aspects, method 1500 also includes: using resources associated with the SS index indicated in the response to obtain another PRACH from the second wireless node. In some cases, this step refers to the operation as described in reference... Figure 16 The circuit and / or code described for obtaining, or that can be executed by the circuit and / or the code.

[0164] In some respects, the SS index indicated in the response is the same as the SS index selected by the wireless node.

[0165] In one aspect, method 1500 or any aspect thereof may be made by means of a device (such as...) Figure 16 The communication device 1600 performs the execution, and the device includes various components capable of operating, being configured, or adapted to perform the method 1500. The communication device 1600 is described in more detail below.

[0166] It should be noted that Figure 15 This is merely one example of a method, and other methods that include fewer, additional, or alternative steps may also be consistent with this disclosure.

[0167] Example communication device

[0168] Figure 16 Various aspects of the example communication device 1600 are described. In some aspects, the communication device 1600 is user equipment, such as those described above relative to... Figure 1 and Figure 3 The UE 104 is described. In some respects, the communication device 1600 is a network entity, such as... Figure 1 and Figure 3 BS102 or as relative to Figure 2 The decomposed base station under discussion.

[0169] Communication device 1600 includes a processing system 1605 coupled to a transceiver 1655 (e.g., a transmitter and / or receiver). In some aspects (e.g., when communication device 1600 is a network entity), the processing system 1605 may be coupled to a network interface 1665, which is configured to communicate via a communication link (such as, as described herein, relative to...). Figure 2 The described backhaul link, midhaul link, and / or fronthaul link receive and transmit signals for communication device 1600. Transceiver 1655 is configured to transmit and receive signals for communication device 1600 via antenna 1660, such as the various signals described herein. Processing system 1605 may be configured to perform processing functions of communication device 1600, including processing signals received by communication device 1600 and / or to be transmitted by the communication device.

[0170] Processing system 1605 includes one or more processors 1610. In various aspects, the one or more processors 1610 may represent one or more of a receive processor 358, a transmit processor 364, a TX MIMO processor 366, and / or a controller / processor 380, as relative to... Figure 3 As described. In various respects, one or more processors 1610 may represent one or more of the following: receive processor 338, transmit processor 320, TX MIMO processor 330, and / or controller / processor 340, as relative to Figure 3 As described. One or more processors 1610 are coupled to a computer-readable medium / memory 1630 via a bus 1650. In some aspects, the computer-readable medium / memory 1630 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 1610, cause the one or more processors 1610 to perform relative to Figure 14 The described method 1400 or any aspect thereof; and relative to Figure 15 The described method 1500 or any aspect thereof. It should be noted that references to processors performing the functions of communication device 1600 may include one or more processors 1610 performing those functions of communication device 1600.

[0171] In the depicted example, computer-readable medium / memory 1630 stores code (e.g., executable instructions), such as code 1635 for acquiring, code 1640 for selecting, and code 1645 for outputting. Processing the code 1635 for acquiring, the code 1640 for selecting, and the code 1645 for outputting enables the communication device 1600 to perform operations relative to... Figure 14 The method described in 1400 or any aspect thereof; and relative to Figure 15 The described method 1500 or any aspect related to that method.

[0172] One or more processors 1610 include circuitry configured to implement (e.g., execute) code stored in computer-readable medium / memory 1630, the circuitry including circuitry 1615 for acquisition, circuitry 1620 for selection, and circuitry 1625 for output. Processing using the acquisition circuitry 1615, the selection circuitry 1620, and the output circuitry 1625 enables the communication device 1600 to perform operations relative to... Figure 14 The method described in 1400 or any aspect thereof; and relative to Figure 15 The described method 1500 or any aspect related to that method.

[0173] The various components of the communication device 1600 can provide parts for performing relative to Figure 14 The described method 1400 or any aspect thereof; and relative to Figure 15 The described method 1500 or any aspect thereof. For example, components for transmitting, conveying, or outputting for transmission may include... Figure 3 The transceiver 354 and / or antenna 352 of the illustrated UE 104 Figure 3 The transceiver 332 and / or antenna 334 of the illustrated BS102 Figure 16 The illustrated communication device 1600 includes a transceiver 1655 and an antenna 1660. Components for receiving or acquiring data may include... Figure 3 The transceiver 354 and / or antenna 352 of the illustrated UE 104 Figure 3 The transceiver 332 and / or antenna 334 of the illustrated BS102 Figure 16 The illustrated communication device 1600 includes a transceiver 1655 and an antenna 1660. Components for selection may include... Figure 3 or Figure 16 Any of the various processors and / or transceivers shown.

[0174] Example Terms

[0175] Specific implementation examples are described in the following numbered clauses:

[0176] Clause 1: A method for wireless communication at a wireless node, the method comprising: obtaining a signal instructing the wireless node to transmit a Physical Random Access Channel (PRACH) to a candidate cell; selecting a synchronization signal (SS) index for the candidate cell; and using resources associated with the selected SS index to output the PRACH for transmission.

[0177] Clause 2: The method described in Clause 1, wherein the resources include time and frequency resources of the random access channel (RACH) timing (RO) associated with the selected SS index.

[0178] Clause 3: The method according to any one of Clauses 1 to 2, wherein the candidate cell belongs to a set of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

[0179] Clause 4: The method according to any one of Clauses 1 to 3, wherein the signal includes a physical downlink control channel (PDCCH) containing an indication of the candidate cell.

[0180] Clause 5: The method according to Clause 4, wherein the PDCCH further includes a random access preamble index field, the random access preamble index field being configured to indicate that the radio node is to transmit the value of the PRACH in the resource associated with the SS index.

[0181] Clause 6: The method according to Clause 4, wherein the PDCCH transmits group common control information, the group common control information instructing the radio node to use the resource associated with the SS index selected by the radio node to send the PRACH.

[0182] Clause 7: The method according to any one of Clauses 1 to 6, the method further comprising: obtaining a response to the PRACH, wherein the response indicates information for contention resolution.

[0183] Clause 8: The method described in Clause 7, wherein the response is obtained from at least one of the following: the serving cell or the candidate cell.

[0184] Clause 9: The method of Clause 7, wherein the response is obtained via at least one of: a Media Access Control (MAC) control element (CE) or control information.

[0185] Clause 10: The method described in Clause 7, wherein the response indicates at least one of the following: UE ID, timing advance (TA) command, or SS index.

[0186] Clause 11: The method according to Clause 10 further includes: using a resource associated with the SS index indicated in the response to output another PRACH for transmission.

[0187] Clause 12: The method according to Clause 10, wherein the SS index indicated in the response is the same as the SS index selected by the wireless node.

[0188] Clause 13: A method for wireless communication at a first wireless node, the method comprising: outputting a signal instructing a second wireless node to transmit a Physical Random Access Channel (PRACH) to a candidate cell; and obtaining the PRACH using resources associated with a synchronization signal (SS) index of the candidate cell selected by the second wireless node.

[0189] Clause 14: The method according to Clause 13, wherein the resources include time resources and frequency resources of the random access channel (RACH) timing (RO) associated with the selected SS index.

[0190] Clause 15: The method according to any one of Clauses 13 to 14, wherein the candidate cell belongs to a set of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

[0191] Clause 16: The method according to any one of Clauses 13 to 15, wherein the signal includes a physical downlink control channel (PDCCH) containing an indication of the candidate cell.

[0192] Clause 17: The method according to Clause 16, wherein the PDCCH further includes a random access preamble index field, the random access preamble index field being configured to indicate to the radio node to transmit the value of the PRACH in the resource associated with the SS index.

[0193] Clause 18: The method according to Clause 16, wherein the PDCCH transmits group common control information, the group common control information instructing the radio node to use the resource associated with the SS index to transmit the PRACH.

[0194] Clause 19: The method according to any one of Clauses 13 to 18, the method further comprising: outputting a response to the PRACH to the second wireless node, wherein the response indicates information for contention resolution.

[0195] Clause 20: The method according to Clause 19, wherein the response is output from at least one of the following: the serving cell or the candidate cell.

[0196] Clause 21: The method according to Clause 19, wherein the response is output via at least one of: a Media Access Control (MAC) control element (CE) or control information.

[0197] Clause 22: The method described in Clause 19, wherein the response indicates at least one of the following: UE ID, timing advance (TA) command, or SS index.

[0198] Clause 23: The method according to Clause 22 further includes: using resources associated with the SS index indicated in the response to obtain another PRACH from the second radio node.

[0199] Clause 24: The method according to Clause 22, wherein the SS index indicated in the response is the same as the SS index selected by the wireless node.

[0200] Clause 25: An apparatus comprising: a memory including executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform a method according to any one of Clauses 1 to 24.

[0201] Clause 26: An apparatus comprising: a component for performing the method according to any one of Clauses 1 to 24.

[0202] Clause 27: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of a device, cause the device to perform a method according to any one of Clauses 1 to 24.

[0203] Clause 28: A computer program product embodied on a computer-readable storage medium, the computer-readable storage medium including code for performing the method according to any one of Clauses 1 to 24.

[0204] Clause 29: A user equipment (UE) comprising: at least one transceiver; a memory including executable instructions; and a processor configured to execute the executable instructions and cause the UE to perform a method according to any one of Clauses 1 to 12, wherein the at least one transceiver is configured to perform at least one of: receiving the signal or transmitting the PRACH.

[0205] Clause 30: A network entity comprising: at least one transceiver; a memory including executable instructions; and a processor configured to execute the executable instructions and cause the network entity to perform a method according to any one of Clauses 13 to 24, wherein the at least one transceiver is configured to perform at least one of: transmitting the signal or receiving the PRACH.

[0206] Additional Notes

[0207] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein do not limit the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, the function and arrangement of the elements discussed may be changed without departing from the scope of this disclosure. Various processes or components may be omitted, substituted, or added as appropriate in various examples. For example, the described methods may be performed in a different order than described, and various actions may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement an apparatus or practice. Additionally, the scope of this disclosure is intended to cover such apparatuses or methods practiced using other structures, functionalities, or structures and functionalities that complement or replace the various aspects of this disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be embodied by one or more elements of these claims.

[0208] The various exemplary logic blocks, modules, and circuits described in this disclosure can be implemented or executed using a general-purpose processor, digital signal processor (DSP), ASIC, field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic device, discrete hardware component, or any combination thereof designed to perform the functions described herein. While the general-purpose processor may be a microprocessor, in alternative embodiments, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, a system-on-a-chip (SoC), or any other such configuration.

[0209] As used in this article, the phrase “at least one of” in a list of items refers to any combination of those items (including single members). For example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0210] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" can include operations, calculations, processing, deduction, investigation, searching (e.g., looking in a table, database, or other data structure), assertions, and so on. Additionally, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and so on. Furthermore, "determine" can include parsing, selecting, picking, building, and so on.

[0211] The methods disclosed herein include one or more actions for implementing the methods. These actions may be interchanged without departing from the scope of the claims. In other words, unless a specified order of actions is given, the order and / or use of a particular action may be modified without departing from the scope of the claims. Furthermore, the various operations of the methods described above may be performed by any suitable component capable of performing the corresponding function. This component may include various hardware and / or software components and / or modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors.

[0212] The following claims are not intended to be limited to the aspects shown herein, but should be given the full scope consistent with the language of the claims. Within the claims, unless specifically stated otherwise, reference to the singular form of an element is not intended to mean “one and only one,” but rather “one or more.” Unless specifically stated otherwise, the term “some” means one or more. No element of any claim shall be interpreted in accordance with the provisions of 35 U.S.SC §112(f) unless that element is explicitly stated using the phrase “for a component of.” All structural and functional equivalents of the elements throughout the various aspects described herein that are known to a person skilled in the art or will later be known are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be offered to the public, whether or not such disclosure is explicitly recited in the claims.

Claims

1. An apparatus for wireless communication, the apparatus comprising: The memory includes executable instructions; and One or more processors, the one or more processors being configured to execute the executable instructions and cause the device to: Obtain a signal instructing the device to send a Physical Random Access Channel (PRACH) to the candidate cell; Select the synchronization signal (SS) index of the candidate cell; and Use the resources associated with the selected SS index to output the PRACH for transmission.

2. The apparatus of claim 1, wherein the resources include time resources and frequency resources of the random access channel (RACH) timing (RO) associated with the selected SS index.

3. The apparatus of claim 1, wherein the candidate cell belongs to a set of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

4. The apparatus of claim 1, wherein the signal includes a physical downlink control channel (PDCCH) that contains an indication of the candidate cell.

5. The apparatus of claim 4, wherein the PDCCH further comprises a random access preamble index field, the random access preamble index field being configured to indicate that the apparatus shall transmit the value of the PRACH in the resource associated with the SS index selected by the apparatus.

6. The apparatus of claim 4, wherein the PDCCH transmits group common control information, the group common control information instructing the apparatus to use the resource associated with the SS index selected by the apparatus to send the PRACH.

7. The apparatus of claim 1, wherein the one or more processors are further configured to execute the executable instructions and cause the apparatus to: Obtain a response to the PRACH, wherein the response indicates information for contention resolution.

8. The apparatus of claim 7, wherein the response is obtained from at least one of: the serving cell or the candidate cell.

9. The apparatus of claim 7, wherein the response is obtained via at least one of: a Media Access Control (MAC) control element (CE) or control information.

10. The apparatus of claim 7, wherein the response indicates at least one of the following: User Equipment (UE) ID; A scheduled advance (TA) command; or SS Index.

11. The apparatus of claim 10, wherein the one or more processors are further configured to execute the executable instructions and cause the apparatus to use resources associated with the SS index indicated in the response to output another PRACH for transmission.

12. The apparatus of claim 10, wherein the SS index indicated in the response is the same as the SS index selected by the apparatus.

13. The apparatus of claim 1, further comprising at least one transceiver, wherein the at least one transceiver is configured to perform at least one of: receiving the signal or transmitting the PRACH, and the apparatus is configured as a network entity.

14. An apparatus for wireless communication, the apparatus comprising: The memory includes executable instructions; and One or more processors, the one or more processors being configured to execute the executable instructions and cause the device to: The output indicates that the wireless node should send a signal to the candidate cell via the Physical Random Access Channel (PRACH); as well as The PRACH is obtained using resources associated with the synchronization signal (SS) index of the candidate cell selected by the radio node.

15. The apparatus of claim 14, wherein the resources include time resources and frequency resources of the random access channel (RACH) timing (RO) associated with the SS index.

16. The apparatus of claim 14, wherein the candidate cell belongs to a set of candidate cells that support mobility signaling via the physical (PHY) layer or media access control (MAC) layer signaling.

17. The apparatus of claim 14, wherein the signal includes a physical downlink control channel (PDCCH) that contains an indication of the candidate cell.

18. The apparatus of claim 17, wherein the PDCCH further comprises a random access preamble index field, the random access preamble index field being configured to indicate that the radio node is to transmit the value of the PRACH in the resource associated with the SS index.

19. The apparatus of claim 17, wherein the PDCCH transmits group common control information, the group common control information instructing the radio node to use the resources associated with the SS index selected by the radio node to transmit the PRACH.

20. The apparatus of claim 14, wherein the one or more processors are further configured to execute the executable instructions and cause the apparatus to: The response to the PRACH is output to the wireless node, wherein the response indicates information for contention resolution.

21. The apparatus of claim 20, wherein the response is output from at least one of: the serving cell or the candidate cell.

22. The apparatus of claim 20, wherein the response is output via at least one of: a Media Access Control (MAC) control element (CE) or control information.

23. The apparatus of claim 20, wherein the response indicates at least one of the following: User Equipment (UE) ID; A scheduled advance (TA) command; or SS Index.

24. The apparatus of claim 23, wherein the one or more processors are further configured to execute the executable instructions and cause the apparatus to use resources associated with the SS index indicated in the response to obtain another PRACH from the wireless node.

25. The apparatus of claim 23, wherein the SS index indicated in the response is the same as the SS index selected by the wireless node.

26. The apparatus of claim 14, further comprising: At least one transceiver, wherein the at least one transceiver is configured to perform at least one of the following: transmitting the signal or receiving the PRACH, and the means is configured as a network entity.

27. A method for wireless communication at a wireless node, the method comprising: Obtain a signal instructing the wireless node to send a Physical Random Access Channel (PRACH) signal to the candidate cell; Select the synchronization signal (SS) index of the candidate cell; as well as Use the resources associated with the selected SS index to output the PRACH for transmission.

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