Random access triggering based on cell group common random access resource set

Abstract

A method and apparatus for a random access triggering based on a cell group common random access resource set is provided. The wireless device receives a random access resource set related to a cell group from a serving cell, selects a random access resource for the cell group from the random access resource set, and transmits one or more preambles to multiple cells included in the cell group based on the selected random access resource.

Description

RANDOM ACCESS TRIGGERING BASED ON CELL GROUP COMMON RANDOM ACCESS RESOURCE SET

[0001] The present disclosure relates to random access triggering based on a cell group common random access resource set.

[0002] 3rd Generation Partnership Project (3GPP) New Radio (NR) targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), Ultra-Reliable and Low Latency Communications (URLLC), etc. The NR shall be inherently forward compatible. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

[0003] 6G is the successor to 5G cellular technology. 6G networks will be able to use higher frequencies than 5G networks and provide substantially higher capacity and much lower latency. The 6G technology market is expected to facilitate large improvements in the areas of imaging, presence technology and location awareness. Working in conjunction with Artificial Intelligence (AI), the 6G computational infrastructure will be able to identify the best place for computing to occur. This includes decisions about data storage, processing and sharing.

[0004] Layer 3 based mobility has evolved over several releases. Conditional Handover (CHO) and other conditional mobility procedures (Conditional PSCell Addition and Change (CPAC), Subsequent CPAC (SCPAC)) were developed to achieve high robustness by enabling the procedure to be executed without necessitating a signaling exchange with source cell beforehand. L1 / L2 Triggered Mobility (LTM) as introduced in Rel-18 offers short interruption time but not with the same level of robustness as the conditional L3 mobility procedures. In Rel-19, enhancements should be specified so that the system can benefit from both the high robustness and short interruption.

[0005] In an aspect, a method is provided. The method comprises receiving a random access resource set related to a cell group from a serving cell, selecting a random access resource for the cell group from the random access resource set, and transmitting one or more preambles to multiple cells included in the cell group based on the selected random access resource.

[0006] In another aspect, an apparatus for implementing the above method is provided.

[0007] FIG. 1 shows an example of a communication system to which implementations of the present disclosure are applied.

[0008] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure are applied.

[0009] FIG. 3 shows an example of UE to which implementations of the present disclosure are applied.

[0010] FIGS. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure are applied.

[0011] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure are applied.

[0012] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure are applied.

[0013] FIG. 8 shows an example of a method to which implementations of the present disclosure are applied.

[0014] FIG. 9 shows an example of another method to which implementations of the present disclosure are applied.

[0015] FIG. 10 shows an example of preamble transmission to which the implementation 1 of the present disclosure is applied.

[0016] FIG. 11 shows an example of a group common random access occasion to which the implementation 1 of the present disclosure is applied.

[0017] FIG. 12 shows an example of TA calculation to which the implementation 1 of the present disclosure is applied.

[0018] FIG. 13 shows an example of preamble transmission to which the implementation 2 of the present disclosure is applied.

[0019] FIG. 14 shows an example of multiple occasions to which the implementation 2 of the present disclosure is applied.

[0020] The following techniques, apparatuses, and systems may be applied to a variety of wireless multiple access systems. Examples of the multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, and a Multi Carrier Frequency Division Multiple Access (MC-FDMA) system. CDMA may be embodied through radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA may be embodied through radio technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is a part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in Downlink (DL) and SC-FDMA in Uplink (UL). Evolution of 3GPP LTE includes LTE-Advanced (LTE-A), LTE-A Pro, 5G New Radio (NR) and / or 6G.

[0021] For convenience of description, implementations of the present disclosure are mainly described in regards to a 3GPP based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP based wireless communication system, aspects of the present disclosure that are not limited to 3GPP based wireless communication system are applicable to other mobile communication systems.

[0022] For terms and technologies which are not specifically described among the terms of and technologies employed in the present disclosure, the wireless communication standard documents published before the present disclosure may be referenced.

[0023] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure may be interpreted as "A and / or B". For example, "A, B or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B and C".

[0024] In the present disclosure, slash ( / ) or comma (,) may mean "and / or". For example, "A / B" may mean "A and / or B". Accordingly, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B or C".

[0025] In the present disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and / or B" in the present disclosure may be interpreted as same as "at least one of A and B".

[0026] In addition, in the present disclosure, "at least one of A, B and C" may mean "only A", "only B", "only C", or "any combination of A, B and C". In addition, "at least one of A, B or C" or "at least one of A, B and / or C" may mean "at least one of A, B and C".

[0027] Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

[0028] Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

[0029] Although not limited thereto, various descriptions, functions, procedures, suggestions, methods and / or operational flowcharts of the present disclosure disclosed herein can be applied to various fields requiring wireless communication and / or connection (e.g., 5G) between devices.

[0030] Hereinafter, the present disclosure will be described in more detail with reference to drawings. The same reference numerals in the following drawings and / or descriptions may refer to the same and / or corresponding hardware blocks, software blocks, and / or functional blocks unless otherwise indicated.

[0031] FIG. 1 shows an example of a communication system to which implementations of the present disclosure are applied.

[0032] The 5G usage scenarios shown in FIG. 1 are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in FIG. 1.

[0033] Three main requirement categories for 5G include (1) a category of enhanced Mobile BroadBand (eMBB), (2) a category of massive Machine Type Communication (mMTC), and (3) a category of Ultra-Reliable and Low Latency Communications (URLLC).

[0034] Referring to FIG. 1, the communication system 1 includes wireless devices 100a to 100f, Base Stations (BSs) 200, and a network 300. Although FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the implementations of the present disclosure are not limited to the 5G system, and can be applied to the future communication system beyond the 5G system.

[0035] The BSs 200 and the network 300 may be implemented as wireless devices and a specific wireless device may operate as a BS / network node with respect to other wireless devices.

[0036] The wireless devices 100a to 100f represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G NR or LTE) and may be referred to as communication / radio / 5G devices. The wireless devices 100a to 100f may include, without being limited to, a robot 100a, vehicles 100b-1 and 100b-2, an eXtended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet-of-Things (IoT) device 100f, and an Artificial Intelligence (AI) device / server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. The vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR) / Virtual Reality (VR) / Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter.

[0037] In the present disclosure, the wireless devices 100a to 100f may be called User Equipments (UEs). A UE may include, for example, a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a navigation system, a slate Personal Computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather / environment device, a device related to a 5G service, or a device related to a fourth industrial revolution field.

[0038] The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a beyond-5G network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs 200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., Vehicle-to-Vehicle (V2V) / Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0039] Wireless communication / connections 150a, 150b and 150c may be established between the wireless devices 100a to 100f and / or between wireless device 100a to 100f and BS 200 and / or between BSs 200. Herein, the wireless communication / connections may be established through various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or Device-to-Device (D2D) communication) 150b, inter-base station communication 150c (e.g., relay, Integrated Access and Backhaul (IAB)), etc. The wireless devices 100a to 100f and the BSs 200 / the wireless devices 100a to 100f may transmit / receive radio signals to / from each other through the wireless communication / connections 150a, 150b and 150c. For example, the wireless communication / connections 150a, 150b and 150c may transmit / receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, and resource mapping / de-mapping), and resource allocating processes, for transmitting / receiving radio signals, may be performed based on the various proposals of the present disclosure.

[0040] NR supports multiples numerologies (and / or multiple Sub-Carrier Spacings (SCS)) to support various 5G services. For example, if SCS is 15 kHz, wide area can be supported in traditional cellular bands, and if SCS is 30 kHz / 60 kHz, dense-urban, lower latency, and wider carrier bandwidth can be supported. If SCS is 60 kHz or higher, bandwidths greater than 24.25 GHz can be supported to overcome phase noise.

[0041] The NR frequency band may be defined as two types of frequency range, i.e., Frequency Range 1 (FR1) and Frequency Range 2 (FR2). The numerical value of the frequency range may be changed. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 may mean "sub 6 GHz range", FR2 may mean "above 6 GHz range," and may be referred to as millimeter Wave (mmW).

[0042] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0043] As mentioned above, the numerical value of the frequency range of the NR system may be changed. For example, FR1 may include a frequency band of 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6GHz (or 5850, 5900, 5925 MHz, etc.) or more. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more included in FR1 may include an unlicensed band. Unlicensed bands may be used for a variety of purposes, for example for communication for vehicles (e.g., autonomous driving).

[0044] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0045] Here, the radio communication technologies implemented in the wireless devices in the present disclosure may include NarrowBand IoT (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and be called by various names such as enhanced MTC (eMTC). For example, LTE-M technology may be implemented in at least one of the various specifications, such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN which take into account low-power communication, and may not be limited to the above-mentioned names. For example, ZigBee technology may generate Personal Area Networks (PANs) associated with small / low-power digital communication based on various specifications such as IEEE 802.15.4 and may be called various names.

[0046] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure are applied.

[0047] In FIG. 2, The first wireless device 100 and / or the second wireless device 200 may be implemented in various forms according to use cases / services. For example, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless device 100a to 100f and the BS 200}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and / or {the BS 200 and the BS 200} of FIG. 1. The first wireless device 100 and / or the second wireless device 200 may be configured by various elements, devices / parts, and / or modules.

[0048] The first wireless device 100 may include at least one transceiver, such as a transceiver 106, at least one processing chip, such as a processing chip 101, and / or one or more antennas 108.

[0049] The processing chip 101 may include at least one processor, such a processor 102, and at least one memory, such as a memory 104. Additional and / or alternatively, the memory 104 may be placed outside of the processing chip 101.

[0050] The processor 102 may control the memory 104 and / or the transceiver 106 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 102 may process information within the memory 104 to generate first information / signals and then transmit radio signals including the first information / signals through the transceiver 106. The processor 102 may receive radio signals including second information / signals through the transceiver 106 and then store information obtained by processing the second information / signals in the memory 104.

[0051] The memory 104 may be operably connectable to the processor 102. The memory 104 may store various types of information and / or instructions. The memory 104 may store a firmware and / or a software code 105 which implements codes, commands, and / or a set of commands that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more protocols. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more layers of the radio interface protocol.

[0052] Herein, the processor 102 and the memory 104 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals through one or more antennas 108. Each of the transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0053] The second wireless device 200 may include at least one transceiver, such as a transceiver 206, at least one processing chip, such as a processing chip 201, and / or one or more antennas 208.

[0054] The processing chip 201 may include at least one processor, such a processor 202, and at least one memory, such as a memory 204. Additional and / or alternatively, the memory 204 may be placed outside of the processing chip 201.

[0055] The processor 202 may control the memory 204 and / or the transceiver 206 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 202 may process information within the memory 204 to generate third information / signals and then transmit radio signals including the third information / signals through the transceiver 206. The processor 202 may receive radio signals including fourth information / signals through the transceiver 106 and then store information obtained by processing the fourth information / signals in the memory 204.

[0056] The memory 204 may be operably connectable to the processor 202. The memory 204 may store various types of information and / or instructions. The memory 204 may store a firmware and / or a software code 205 which implements codes, commands, and / or a set of commands that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more protocols. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more layers of the radio interface protocol.

[0057] Herein, the processor 202 and the memory 204 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through one or more antennas 208. Each of the transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be interchangeably used with RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0058] Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs), one or more Service Data Unit (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure.

[0059] The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. For example, the one or more processors 102 and 202 may be configured by a set of a communication control processor, an Application Processor (AP), an Electronic Control Unit (ECU), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), and a memory control processor.

[0060] The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and / or commands. The one or more memories 104 and 204 may be configured by Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), electrically Erasable Programmable Read-Only Memory (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cash memory, computer-readable storage medium, and / or combinations thereof. The one or more memories 104 and 204 may be located at the interior and / or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

[0061] The one or more transceivers 106 and 206 may transmit user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices.

[0062] The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208. Additionally and / or alternatively, the one or more transceivers 106 and 206 may include one or more antennas 108 and 208. The one or more transceivers 106 and 206 may be adapted to transmit and receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, through the one or more antennas 108 and 208. In the present disclosure, the one or more antennas 108 and 208 may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

[0063] The one or more transceivers 106 and 206 may convert received user data, control information, radio signals / channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals / channels, etc., using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals / channels, etc., processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, the one or more transceivers 106 and 206 can up-convert OFDM baseband signals to OFDM signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202 and transmit the up-converted OFDM signals at the carrier frequency. The one or more transceivers 106 and 206 may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202.

[0064] Although not shown in FIG. 2, the wireless devices 100 and 200 may further include additional components. The additional components 140 may be variously configured according to types of the wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power unit / battery, an Input / Output (I / O) device (e.g., audio I / O port, video I / O port), a driving device, and a computing device. The additional components 140 may be coupled to the one or more processors 102 and 202 via various technologies, such as a wired or wireless connection.

[0065] In the implementations of the present disclosure, a UE may operate as a transmitting device in UL and as a receiving device in DL. In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as the UE, and the second wireless device 200 acts as the BS. For example, the processor(s) 102 connected to, mounted on or launched in the first wireless device 100 may be adapted to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) 106 to perform the UE behavior according to an implementation of the present disclosure. The processor(s) 202 connected to, mounted on or launched in the second wireless device 200 may be adapted to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) 206 to perform the BS behavior according to an implementation of the present disclosure.

[0066] In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

[0067] FIG. 3 shows an example of UE to which implementations of the present disclosure are applied.

[0068] Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG. 2.

[0069] A UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keypad 144, a Subscriber Identification Module (SIM) card 145, a speaker 146, and a microphone 147.

[0070] The processor 102 may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The processor 102 may be adapted to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include ASIC, other chipset, logic circuit and / or data processing device. The processor 102 may be an application processor. The processor 102 may include at least one of DSP, CPU, GPU, a modem (modulator and demodulator). An example of the processor 102 may be found in SNAPDRAGONTMseries of processors made by QUALCOMM®, EXYNOSTMseries of processors made by SAMSUNG®, A series of processors made by APPLE®, HELIOTMseries of processors made by MEDIATEK®, ATOMTMseries of processors made by INTEL®or a corresponding next generation processor.

[0071] The memory 104 is operatively coupled with the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium and / or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The modules can be stored in the memory 104 and executed by the processor 102. The memory 104 can be implemented within the processor 102 or external to the processor 102 in which case those can be communicatively coupled to the processor 102 via various means as is known in the art.

[0072] The transceiver 106 is operatively coupled with the processor 102, and transmits and / or receives a radio signal. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry to process radio frequency signals. The transceiver 106 controls the one or more antennas 108 to transmit and / or receive a radio signal.

[0073] The power management module 141 manages power for the processor 102 and / or the transceiver 106. The battery 142 supplies power to the power management module 141.

[0074] The display 143 outputs results processed by the processor 102. The keypad 144 receives inputs to be used by the processor 102. The keypad 144 may be shown on the display 143.

[0075] The SIM card 145 is an　integrated circuit　that is intended to　securely store the　International Mobile Subscriber Identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

[0076] The speaker 146 outputs sound-related results processed by the processor 102. The microphone 147 receives sound-related inputs to be used by the processor 102.

[0077] FIGS. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure are applied.

[0078] In particular, FIG. 4 illustrates an example of a radio interface user plane protocol stack between a UE and a BS and FIG. 5 illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to FIG. 4, the user plane protocol stack may be divided into Layer 1 (i.e., a PHY layer) and Layer 2. Referring to FIG. 5, the control plane protocol stack may be divided into Layer 1 (i.e., a PHY layer), Layer 2, Layer 3 (e.g., an RRC layer), and a Non-Access Stratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an Access Stratum (AS).

[0079] In the 3GPP LTE system, the Layer 2 is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to 5G core network Quality of Service (QoS) flows.

[0080] In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing / de-multiplexing of MAC SDUs belonging to one or different logical channels into / from Transport Blocks (TB) delivered to / from the physical layer on transport channels; scheduling information reporting; error correction through Hybrid Automatic Repeat reQuest (HARQ) (one HARQ entity per cell in case of Carrier Aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

[0081] Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast Control Channel (BCCH) is a downlink logical channel for broadcasting system control information, Paging Control Channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing Public Warning Service (PWS) broadcasts, Common Control Channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and Dedicated Control Channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated Traffic Channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to Broadcast Channel (BCH); BCCH can be mapped to Downlink Shared Channel (DL-SCH); PCCH can be mapped to Paging Channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to Uplink Shared Channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0082] The RLC sublayer supports three transmission modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). The RLC configuration is per logical channel with no dependency on numerologies and / or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

[0083] In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using Robust Header Compression (ROHC); transfer of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering and integrity protection; transfer of control plane data; reordering and duplicate detection; in-order delivery; duplication of PDCP PDUs and duplicate discard indication to lower layers.

[0084] In the 3GPP NR system, the main services and functions of SDAP include: mapping between a QoS flow and a data radio bearer; marking QoS Flow ID (QFI) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

[0085] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5G Core network (5GC) or Next-Generation Radio Access Network (NG-RAN); establishment, maintenance and release of an RRC connection between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs); mobility functions (including: handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting; detection of and recovery from radio link failure; NAS message transfer to / from NAS from / to UE.

[0086] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure are applied.

[0087] The frame structure shown in FIG. 6 is purely exemplary and the number of subframes, the number of slots, and / or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., SCS, Transmission Time Interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or Cyclic Prefix (CP)-OFDM symbols), SC-FDMA symbols (or Discrete Fourier Transform-spread-OFDM (DFT-s-OFDM) symbols).

[0088] Referring to FIG. 6, downlink and uplink transmissions are organized into frames. Each frame has Tf= 10ms duration. Each frame is divided into two half-frames, where each of the half-frames has 5ms duration. Each half-frame consists of 5 subframes, where the duration Tsfper subframe is 1ms. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on a CP. In a normal CP, each slot includes 14 OFDM symbols and, in an extended CP, each slot includes 12 OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing Δf = 2u*15 kHz.

[0089] Table 3 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the normal CP, according to the subcarrier spacing Δf = 2u*15 kHz.

[0090] uNslotsymbNframe,uslotNsubframe,uslot01410111420221440431480841416016

[0091] Table 4 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the extended CP, according to the subcarrier spacing Δf = 2u*15 kHz.

[0092] uNslotsymbNframe,uslotNsubframe,uslot212404

[0093] A slot includes plural symbols (e.g., 14 or 12 symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid ofNsize,ugrid,x*NRBscsubcarriers andNsubframe,usymbOFDM symbols is defined, starting at Common Resource Block (CRB)Nstart,ugridindicated by higher-layer signaling (e.g., RRC signaling), whereNsize,ugrid,xis the number of Resource Blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink.NRBscis the number of subcarriers per RB. In the 3GPP based wireless communication system,NRBscis 12 generally. There is one resource grid for a given antenna portp, subcarrier spacing configurationu, and transmission direction (DL or UL). The carrier bandwidthNsize,ugridfor subcarrier spacing configurationuis given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna portpand the subcarrier spacing configurationuis referred to as a Resource Element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an indexkin the frequency domain and an indexlrepresenting a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain.

[0094] In the 3GPP NR system, RBs are classified into CRBs and Physical Resource Blocks (PRBs). CRBs are numbered from 0 and upwards in the frequency domain for subcarrier spacing configurationu. The center of subcarrier 0 of CRB 0 for subcarrier spacing configurationucoincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a BandWidth Part (BWP) and numbered from 0 toNsizeBWP,i-1, where i is the number of the bandwidth part. The relation between the physical resource block nPRBin the bandwidth part i and the common resource block nCRBis as follows: nPRB= nCRB+NsizeBWP,i, whereNsizeBWP,iis the common resource block where bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

[0095] In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL Component Carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

[0096] In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment / re-establishment / handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment / handover, one serving cell provides the security input. This cell is referred to as the Primary Cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, Secondary Cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of Special Cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For Dual Connectivity (DC) operation, the term SpCell refers to the PCell of the Master Cell Group (MCG) or the Primary SCell (PSCell) of the Secondary Cell Group (SCG). An SpCell supports Physical Uplink Control Channel (PUCCH) transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA / DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA / DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

[0097] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure are applied.

[0098] Referring to FIG. 7, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted / received using radio resources through the PHY layer to / from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

[0099] In the PHY layer, the uplink transport channels UL-SCH and Random Access Channel (RACH) are mapped to their physical channels Physical Uplink Shared Channel (PUSCH) and Physical Random Access Channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to Physical Downlink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH) and PDSCH, respectively. In the PHY layer, Uplink Control Information (UCI) is mapped to PUCCH, and Downlink Control Information (DCI) is mapped to Physical Downlink Control Channel (PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

[0100] L1 / L2 Triggered Mobility (LTM) is a procedure in which a gNB receives L1 measurement report(s) from a UE, and on their basis the gNB changes UE serving cell by a cell switch command signaled via a MAC Control Element (CE). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signaling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency

[0101] When configured by the network, it is possible to activate Transmission Configuration Index (TCI) states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

[0102] When configured by the network, it is possible to initiate UL TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTAas the current serving cells or NTA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by PDCCH order or realized through UE-based TA measurement as configured by RRC. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0103] Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE applies the TA value by itself if available. Meanwhile, the UE performs RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

[0104] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes requesting a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

[0105] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UE shall not trigger random access procedure if it does not have a valid PUCCH resource for triggered Scheduling Requests (SRs).

[0106] The following principles apply to LTM:

[0107] - Security key is maintained upon an LTM cell switch;

[0108] - Subsequent LTM is supported.

[0109] LTM supports both intra-gNB-Distributed Unit (DU) and intra-gNB-Centralized Unit (CU) inter-gNB-DU mobility. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. The following scenarios are supported:

[0110] - PCell change in non-CA scenario and non-DC scenario;

[0111] - PCell and SCell(s) change in CA scenario;

[0112] - Dual connectivity scenario, PCell and MCG SCell(s) change and intra-SN PSCell and SCG SCell(s) change without MN involvement. LTM for simultaneous PCell and PSCell change is not supported.

[0113] While the UE has stored LTM candidate configurations the UE can also execute any L3 handover command sent by the network.

[0114] To enable RACH-less mobility, the UE may be required to perform random access (or simplified random access) to potential candidate cells for an early synchronization before initiating a mobility. Currently, the random access resource may be provided cell-specifically via e.g., system information.

[0115] In case multiple candidate cells are considered for the RACH-less mobility, the UE may need to perform random access to each candidate cell for the RACH-less mobility. This would increase signaling overhead for random access and / or would cause interference to neighbor cells. In addition, the execution of random access to candidate cells may introduce interruption of serving cell communication, if UE capability is limited. Furthermore, if the UE is configured with multiple candidate cells, the UE may need to perform random access for early synchronization toward each candidate cell one by one. Since RACH Occasion (RO) of the different cells may not be closely occurring in time domain, random accesses to all of the candidate cells may require non-trivial time to be completed. To avoid or reduce the above-mentioned problems, more efficient method for random access towards a group of cells would be beneficial.

[0116] In the present disclosure, a method for triggering a random access based on a random access resource set associated with a group of cells (or cell group) is proposed.

[0117] According to implementations of the present disclosure, cells included in the cell group may share the random access resource set. The cells included in the cell group may be on the same frequency. The random access resource set associated with the cell group may be denoted and / or referred to as cell group common random access resource set and / or group common random access resource set. The network may coordinate a set of random access resources applicable for the cell group as the group common random access resource set. Then, the UE may be configured by the network with the group common random access resource set.

[0118] According to implementations of the present disclosure, the UE may determine to trigger random access to the cells include in the cell group. The UE may trigger random access to the cells include in the cell group based on a random access triggering condition. The random access triggering condition may include one of the following conditions and / or a joint condition comprising more than one of the following conditions.

[0119] (1) Explicit network indication

[0120] The UE may receive an indication to trigger a random access based on the group common random access resources from the serving cell.

[0121] For example, the network (e.g., serving cell) may indicate a cell group ID of the cell group as a target of the random access. For example, the network may indicate a configuration ID of a configuration related to the group common random access resources. For example, the network may indicate a list of cells as a target of the random access.

[0122] (2) Upon satisfaction of pre-configured condition

[0123] Based on the satisfaction of a pre-configured condition, the UE may trigger a random access based on the group common random access resources. For example, the UE may detect that beam and / or beam set of one or more cells among the cell group satisfies a radio condition that may be pre-configured by network. For example, the UE may detect that quality of one or more cells among the cell group satisfies a radio condition that may be pre-configured by the network.

[0124] According to implementations of the present disclosure, upon triggering the group common random access (i.e., random access to cells included in the cell group based on the group common random access resources), the UE may select a random access resource from the group common random access resource set.

[0125] There are two possible implementations for selecting a random access resource from the group common random access resource set. Detailed UE behaviors related to these two possible approaches will be described below in the present disclosure.

[0126] The random access to cells included in the cell group may comprise transmission of random access preambles without reception of random access response.

[0127] Alternatively, the random access to cells included in the cell group may comprise transmission of random access preambles and reception of random access response. For the random access response to the group common random access preamble transmission, a dedicated RA-RNTI (e.g., G-RA-RNTI) may be introduced. The random access response may be received on the serving cell. Or, the random access response may be received on one more target cell to which random access preamble was transmitted.

[0128] The random access response may include UL timing information (e.g., Timing Advance (TA) value). After the UE receives the random access response including the UL timing information, the UE may consider that the UL timing information is applicable for all of the cells included in the cell group. The UE may apply the UL timing information when transmitting uplink message to a cell included in the cell group over e.g., PUCCH or PUSCH of the cell. For example, the UE may perform (RACH-less) cell switch to the cell and transmit mobility complete message (e.g., RRC reconfiguration complete message) to the cell. The mobility complete message may be transmitted based on UL timing determined based on DL timing of the cell and the UL timing information. The received UL timing information may be considered valid for a period of time, where the period of time may be configured by the network.

[0129] After completing the random access preamble transmission to one or more target cells included in the cell group, the UE may indicate to the serving cell that the random access preamble transmission is completed via, e.g., control signaling (e.g., L1 signaling (UCI) / L2 signaling (MAC CE)).

[0130] The following drawings are created to explain specific embodiments of the present disclosure. The names of the specific devices or the names of the specific signals / messages / fields shown in the drawings are provided by way of example, and thus the technical features of the present disclosure are not limited to the specific names used in the following drawings.

[0131] An embodiment of the present disclosure related to a specific drawing described below may be combined with various embodiments of the present disclosure related to other drawings, and some descriptions, functions, procedures, proposals, methods and / or operations of the embodiment may be omitted.

[0132] FIG. 8 shows an example of a method to which implementations of the present disclosure are applied.

[0133] In step S800, the method comprises receiving a random access resource set related to a cell group from a serving cell.

[0134] In some implementations, the random access resource set may include at least one of one or more occasions, one or more preambles, and / or one or more configuration parameters for a group common random access.

[0135] In step S810, the method comprises selecting a random access resource for the cell group from the random access resource set.

[0136] In some implementations, the random access resource may be selected based on triggering of a random access to the multiple cells. For example, the random access to the multiple cells may be triggered based on a network indication. The network indication may include at least one of a cell group ID, a configuration ID of a configuration related to the random access resource set, and / or a list of the multiple cells. For example, the random access to the multiple cells may be triggered based on a satisfaction of a radio condition.

[0137] In step S820, the method comprises transmitting one or more preambles to multiple cells included in the cell group based on the selected random access resource.

[0138] In some implementations, the multiple cells may share the random access resource set. the multiple cells may be on a same frequency.

[0139] In some implementations, transmission of the one or more preambles to multiple cells may not be followed by reception of a random access response.

[0140] In some implementations, transmission of the one or more preambles to multiple cells may be followed by reception of a response. The reception of the response may be related to a dedicated RA-RNTI. The response may be received on a serving cell and / or one or more cells among the multiple cells. The response includes UL timing information, and the uplink timing information may be applied to transmission of an uplink message on one or more cells among the multiple cells.

[0141] In some implementations, the method may further comprise indicating to a serving cell that transmission of the one or more preambles to the multiple cells is completed.

[0142] In some implementations, one preamble may be transmitted to the multiple cells, and the one preamble may be monitored by the multiple cells. A transmission power for the one preamble may be derived based on a transmission power for each of the multiple cells. A timing reference for transmission of the one preamble may be configured by the network and / or selected by a wireless device.

[0143] In some implementations, each of multiple preambles may be transmitted to each of the multiple cells in each occasion, respectively. Transmission of the multiple preambles to the multiple cells may be completed within a time window.

[0144] In some implementations, the method may be performed by a wireless device in communication with at least one of a mobile device, a network, and / or autonomous vehicles other than the wireless device.

[0145] Furthermore, the wireless device may be implemented by the first wireless device 100 shown in FIG. 2 and / or the UE 100 shown in FIG. 3.

[0146] The wireless device comprises at least one transceiver, at least one processor, and at least one memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, cause the wireless device to perform the method described in FIG. 8.

[0147] More specifically, the wireless device receives a random access resource set related to a cell group from a serving cell.

[0148] In some implementations, the random access resource set may include at least one of one or more occasions, one or more preambles, and / or one or more configuration parameters for a group common random access.

[0149] The wireless device selects a random access resource for the cell group from the random access resource set.

[0150] In some implementations, the random access resource may be selected based on triggering of a random access to the multiple cells. For example, the random access to the multiple cells may be triggered based on a network indication. The network indication may include at least one of a cell group ID, a configuration ID of a configuration related to the random access resource set, and / or a list of the multiple cells. For example, the random access to the multiple cells may be triggered based on a satisfaction of a radio condition.

[0151] The wireless device transmits one or more preambles to multiple cells included in the cell group based on the selected random access resource.

[0152] In some implementations, the multiple cells may share the random access resource set. the multiple cells may be on a same frequency.

[0153] In some implementations, transmission of the one or more preambles to multiple cells may not be followed by reception of a random access response.

[0154] In some implementations, transmission of the one or more preambles to multiple cells may be followed by reception of a response. The reception of the response may be related to a dedicated RA-RNTI. The response may be received on a serving cell and / or one or more cells among the multiple cells. The response includes UL timing information, and the uplink timing information may be applied to transmission of an uplink message on one or more cells among the multiple cells.

[0155] In some implementations, the wireless device may indicate to a serving cell that transmission of the one or more preambles to the multiple cells is completed.

[0156] In some implementations, one preamble may be transmitted to the multiple cells, and the one preamble may be monitored by the multiple cells. A transmission power for the one preamble may be derived based on a transmission power for each of the multiple cells. A timing reference for transmission of the one preamble may be configured by the network and / or selected by a wireless device.

[0157] In some implementations, each of multiple preambles may be transmitted to each of the multiple cells in each occasion, respectively. Transmission of the multiple preambles to the multiple cells may be completed within a time window.

[0158] Furthermore, the method described above in FIG. 8 may be performed by control of a processing apparatus. The processing apparatus may be implemented by the processor 102 included in the first wireless device 100 shown in FIG. 2 and / or the processor 102 included in the UE 100 shown in FIG. 3.

[0159] The processing apparatus comprises at least one processor that is integrated with a wireless device, and at least one memory comprising processor-executable instructions stored thereon that are configured to cause the at least one processor to perform the method described in FIG. 8.

[0160] Furthermore, the method described above in FIG. 8 may be performed by a software code 105 stored in the memory 104 included in the first wireless device 100 shown in FIG. 2.

[0161] The technical features of the present disclosure may be embodied directly in hardware, in a software executed by a processor, or in a combination of the two. For example, a method performed by a wireless device in a wireless communication may be implemented in hardware, software, firmware, or any combination thereof. For example, a software may reside in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, a removable disk, a CD-ROM, or any other storage medium.

[0162] Some example of storage medium may be coupled to the processor such that the processor can read information from the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. For other example, the processor and the storage medium may reside as discrete components.

[0163] The computer-readable medium may include a tangible and non-transitory computer-readable storage medium.

[0164] For example, non-transitory computer-readable media may include RAM such as Synchronous DRAM (SDRAM), ROM, Non-Volatile RAM (NVRAM), EEPROM, flash memory, magnetic or optical data storage media, or any other medium that can be used to store instructions or data structures. Non-transitory computer-readable media may also include combinations of the above.

[0165] In addition, the method described herein may be realized at least in part by a computer-readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0166] According to some implementations of the present disclosure, a non-transitory Computer-Readable Medium (CRM) stores instructions that, based on being executed by at least one processor, perform the method described in FIG. 8.

[0167] FIG. 9 shows an example of another method to which implementations of the present disclosure are applied.

[0168] In step S900, the method comprises transmitting a random access resource set related to a cell group to a wireless device. A random access resource for the cell group is selected from the random access resource set. One or more preambles are transmitted to multiple cells included in the cell group based on the selected random access resource.

[0169] Furthermore, the method described above in FIG. 9 may be performed by a base station. The base station may be implemented by the second wireless device 200 shown in FIG. 2.

[0170] The base station comprises at least one transceiver, at least one processor, and at least one memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, cause the base station to perform the method described in FIG. 9.

[0171] More specifically, the base station transmits a random access resource set related to a cell group to a wireless device. A random access resource for the cell group is selected from the random access resource set. One or more preambles are transmitted to multiple cells included in the cell group based on the selected random access resource.

[0172] Two implementations for selecting a random access resource from the group common random access resource set according to the present disclosure are described.

[0173] 1. Implementation 1

[0174] The implementation 1 of the present may be related to 1:N preamble transmission (e.g., Omni-beam group common preamble transmission).

[0175] FIG. 10 shows an example of preamble transmission to which the implementation 1 of the present disclosure is applied.

[0176] In the implementation 1 of the present disclosure, the UE may transmit one preamble to the cells in the cell group. Surrounding cells included in the cell group may concurrently monitor the transmitted preamble. Then, each surrounding cell may calculate timing advance for the UE, and provide the TA value to the UE.

[0177] (1) The UE may be configured with group common random access resource set for cell1, cell2, and cell3. The group common random access resource set may comprise one or more occasions, one or more preambles, and one or more random access configuration parameters for the group common random access.

[0178] The group common random access resource set may be configured by semi-static signaling (e.g., RRC signaling). Additionally and / or alternatively, the group common random access resource set may be dynamically indicated to the UE via L1 / L2 or RRC signaling.

[0179] FIG. 11 shows an example of a group common random access occasion to which the implementation 1 of the present disclosure is applied.

[0180] Referring to FIG. 11, the group common random access occasion may be configured for cell1, cell2, and cell3.

[0181] (2) The UE may determine preamble target cells. In FIG. 10, cell1, cell2 and cell3 are preamble target cells (e.g., pending mobility candidates). The network may indicate the preamble target cells. Additionally and / or alternatively, the UE may derive preamble target cells based on evaluating pre-configured conditions.

[0182] (3) The UE may determine preamble transmission power for each preamble target cell. For example, P_TX_cell1 = a, P_TX_cell1 = b, P_TX_cell1 = c.

[0183] (4) The UE may derive the preamble transmission power for group common preamble, based on the determined preamble transmission power for each preamble target cell.

[0184] - For example, the preamble transmission power for group common preamble may be calculated by taking maximum of preamble transmission powers for all preamble target cells (i.e., P_TX_group = max (a,b,c)). This approach is intended for group common preamble transmission to reach the weakest preamble target cell and thus all preamble target cells.

[0185] - For example, the preamble transmission power for group common preamble may be calculated by taking minimum of preamble transmission powers for all preamble target cells (i.e., P_TX_group = min (a,b,c)). This approach is intended for group common preamble transmission to reach the strongest preamble target cell at least.

[0186] - example, the preamble transmission power for group common preamble may be calculated by (weighted) averaging preamble transmission powers for all preamble target cells (i.e., P_TX_group = average (a,b,c)). This approach is intended for group common preamble transmission to reach the strongest preamble target cell and other preamble target cell opportunistically.

[0187] - For example, the preamble transmission power for group common preamble may be set as the N-th lowest value of preamble transmission power among all preamble target cells. This approach is intended for group common preamble transmission to reach the N-strongest preamble target cells.

[0188] (5) The UE may determine a timing reference for transmission of group common preamble.

[0189] - For example, the network may configure one cell among cell1, cell2 and cell3 as timing reference cell.

[0190] - For example, the network may configure the UE to use the current serving cell as a timing reference cell for cell1, cell2 and cell3.

[0191] - For example, the UE may select a reference cell for timing reference. The UE may select the reference cell based on measurement. At least one of the following options may be considered.

[0192] The network may configure reference cell selection conditions and the UE may evaluate the conditions to select the reference cell. The UE may select a cell as a reference cell if beam / beam set of the cell satisfies a radio-related condition that may be pre-configured by the network. If multiple beams satisfy the condition, the UE may select one beam whose quality is better, and select a cell transmitting the selected beam accordingly. Or, the UE may select a cell as a reference cell if quality of the cell satisfies a radio-related condition that may be pre-configured by the network. If multiple cells satisfy the condition, the UE may choose one cell whose quality is better.

[0193] The UE may measure quality of beams / cells of the cells included in the cell group and select a cell whose beam / cell quality is best. The UE may select a cell as a reference cell if quality of the beam / beam set of the cell is better than that of any other cells included in the cell group. That is, the cell whose beam / beam set is the best may be selected as reference cell. Or, the UE may select a cell as a reference cell if quality of the cell is better than that of any other cells. That is, the cell whose quality is the best within the cell group may be selected as reference cell.

[0194] The UE may select a current serving cell as a reference cell if cell / beam quality of the current serving cell is higher than a threshold (intention is to minimize interference to the serving cell, caused by random access based on the group common random access resources). The UE may select a non-serving cell as a reference cell if cell / beam quality of the current serving cell is not higher than a threshold (intention is to minimize interference to the serving cell). In this case, the one of methods mentioned above may be applied for selecting the reference cell.

[0195] - For example, the UE may use the determined reference cell based on synchronization signals (e.g., synchronization signal blocks (SSBs)) transmitted by the reference cell to perform time / frequency synchronization for the random access to the cell group. If the UE selects a reference cell, the UE may indicate to the network the selected reference cell such that the network can determine which cell is used as timing reference for preamble transmission.

[0196] For this purpose, the UE may be configured with different preambles corresponding to different timing reference cells. For example, preamble1 may be used in case cell1 is used as timing reference cell, and preamble2 may be used in case cell2 is used as timing reference cell.

[0197] For this purpose, the UE may be configured with different ROs corresponding to different timing reference cells. For example, RO1 may be used in case cell1 is used as timing reference cell, and RO2 may be used in case cell2 is used as timing reference cell.

[0198] (6) The UE may transmit the group common preamble based on at least one of i) the derived transmission power, ii) random access occasion configured for the group common random access, and / or iii) the timing of the determined timing reference cell.

[0199] (7) Each cell may calculate its TA for the UE based on the DL timing offset between the cell and the timing reference cell, as well as reception timing of preamble.

[0200] FIG. 12 shows an example of TA calculation to which the implementation 1 of the present disclosure is applied.

[0201] Referring to FIG. 12, if cell2 is used as timing reference cell for group common preamble, cell3 may consider the time offset t2-t3 for calculating TA for the UE.

[0202] According to the implementation 1 of the present disclosure, the network can learn UL timing towards multiple cells for the UE based on a single preamble transmission. Since the number of preamble transmissions is reduced, preamble signaling overhead, corresponding interference and / or serving cell interruption can be reduced.

[0203] 2. Implementation 2

[0204] The implementation 2 of the present may be related to N number of 1:1 preamble transmission (e.g., UL beam-sweeping across cells for group preamble transmissions).

[0205] (1) The UE may be configured with random access resource for cell. For each cell, one or more beams may be configured. For each beam, associated preamble set may also be configured.

[0206] FIG. 13 shows an example of preamble transmission to which the implementation 2 of the present disclosure is applied.

[0207] Referring to FIG. 13, beams 1 and 2 are configured for cell1, beams 4 and 5 are configured for cell2, and beams 7 and 8 are configured for cell3.

[0208] (2) The UE may be configured with group common random access resource set.

[0209] The group common random access resource set may include cell1, cell2, cell3 as a member of group common preamble transmission.

[0210] FIG. 14 shows an example of multiple occasions to which the implementation 2 of the present disclosure is applied.

[0211] Referring to FIG. 14, each occasion for group common preamble transmission comprises first occasion corresponding to preamble target cell1, a second occasion corresponding to preamble target cell2, and a third occasion corresponding to preamble target cell3. Since occasion for each cell included in the cell group may occur closely in time domain, preamble transmissions to multiple cells included in the cell group may be completed within an expected time (e.g., time window). The occasion for each preamble target cell within group occasions may be separate from the normal cell specific random occasion for each cell.

[0212] (3) The UE may determine preamble target cells.

[0213] In FIG. 13, it is assumed that cell1 and cell2 are preamble target cells (e.g., pending mobility candidates).

[0214] For example, the network may indicate the preamble target cells. For example, the UE may derive preamble target cells based on evaluating pre-configured conditions.

[0215] (4) The UE may determine a beam for each preamble target cell.

[0216] If the network indicates a particular beam in triggering the group common random access, the UE may conside the indicated beam as determined beam. If the network does not indicate a particular beam, the UE may select a best beam as determined beam for each cell.

[0217] In FIG. 13, it is assumed that determined beams are beam1 for cell1 and beam5 for cell2.

[0218] (5) The UE may select a preamble associated with the determined beam for each preamble target cell.

[0219] In FIG. 13, the UE selects a preamble associated with the beam1 for preamble target cell1, and selects a preamble associated with the beam5 for preamble target cell2.

[0220] (6) The UE may determine preamble transmission power for each preamble target cell.

[0221] For example, P_TX_cell1 = a, P_TX_cell1 = b.

[0222] (7) The UE may transmit the selected preambles across cells.

[0223] In FIG. 13, the UE transmits the selected preamble for preamble target cell1 in the first occasion within the group common occasion, with transmission power of P_TX_cell1, and transmits the selected preamble for preamble target cell2 in the second occasion within the group common occasion, with transmission power of P_TX_cell2.

[0224] (8) Each cell may calculate its TA for the UE based on its own timing and / or reception timing of the preamble transmitted in the corresponding occasion within the group common occasion.

[0225] In FIG. 13, cell1 monitors preamble transmitted by the UE in the first occasion, and cell2 monitors preamble transmitted by the UE in the second occasion.

[0226] According to the implementation 2 of the present disclosure, random access to multiple cells included in the cell group can be completed within an expected time.

[0227] The present disclosure may have various advantageous effects.

[0228] Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

[0229] Claims in the present disclosure can be combined in a various way. For instance, technical features in method claims of the present disclosure can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.

Claims

A method comprising:receiving a random access resource set related to a cell group from a serving cell;selecting a random access resource for the cell group from the random access resource set; andtransmitting one or more preambles to multiple cells included in the cell group based on the selected random access resource.The method of claim 1, wherein the random access resource set includes at least one of one or more occasions, one or more preambles, and / or one or more configuration parameters for a group common random access.The method of claim 1 or 2, wherein the multiple cells share the random access resource set.The method of any claims 1 to 3, wherein the multiple cells are on a same frequency.The method of any claims 1 to 4, wherein the random access resource is selected based on triggering of a random access to the multiple cells.The method of claim 5, wherein the random access to the multiple cells is triggered based on a network indication.The method of claim 6, wherein the network indication includes at least one of a cell group identifier (ID), a configuration ID of a configuration related to the random access resource set, and / or a list of the multiple cells.The method of any claims 5 to 7, wherein the random access to the multiple cells is triggered based on a satisfaction of a radio condition.The method of any claims 1 to 8, wherein transmission of the one or more preambles to multiple cells is not followed by reception of a random access response.The method of any claims 1 to 8, wherein transmission of the one or more preambles to multiple cells is followed by reception of a response.The method of claim 10, wherein the reception of the response is related to a dedicated random access radio network temporary identity (RA-RNTI).The method of claim 10 or 11, wherein the response is received on a serving cell and / or one or more cells among the multiple cells.The method of any claims 10 to 12, wherein the response includes uplink (UL) timing information, andwherein the uplink timing information is applied to transmission of an uplink message on one or more cells among the multiple cells.The method of any claims 1 to 13, wherein the method further comprises indicating to a serving cell that transmission of the one or more preambles to the multiple cells is completed.The method of any claims 1 to 14, wherein one preamble is transmitted to the multiple cells, andwherein the one preamble is monitored by the multiple cells.The method of claim 15, wherein a transmission power for the one preamble is derived based on a transmission power for each of the multiple cells.The method of claim 15 or 16, wherein a timing reference for transmission of the one preamble is configured by the network and / or selected by a wireless device.The method of any claims 1 to 14, wherein each of multiple preambles is transmitted to each of the multiple cells in each occasion, respectively.The method of claim 18, wherein transmission of the multiple preambles to the multiple cells is completed within a time window.The method of any claims 1 to 19, wherein the method is performed by a wireless device in communication with at least one of a mobile device, a network, and / or autonomous vehicles other than the wireless device.A wireless device comprising:at least one transceiver;at least one processor; andat least one memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, cause the wireless device to perform the method of any claims 1 to 20.A processing apparatus comprising:at least one processor that is integrated with a wireless device; andat least one memory comprising processor-executable instructions stored thereon that are configured to cause the at least one processor to perform the method of any claims 1 to 20.A non-transitory Computer Readable Medium (CRM) storing instructions that, based on being executed by at least one processor, perform the method of any claims 1 to 20.A method comprising:transmitting a random access resource set related to a cell group to a wireless device,wherein a random access resource for the cell group is selected from the random access resource set, andwherein one or more preambles are transmitted to multiple cells included in the cell group based on the selected random access resource.A base station comprising:at least one transceiver;at least one processor; andat least one memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, cause the base station to perform the method of claim 24.

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