Mobility restriction in wireless communications

Abstract

The present disclosure is related to mobility restriction in wireless communications. According to an embodiment of the present disclosure, a method performed by a communication device adapted to operate in a wireless communication system comprises: receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells; executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

Description

MOBILITY RESTRICTION IN WIRELESS COMMUNICATIONS

[0001] The present disclosure is related to mobility restriction in wireless communications.

[0002] 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

[0003] Work has started in International Telecommunication Union (ITU) and 3GPP to develop requirements and specifications for New Radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU Radio communication sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. 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.

[0004] The 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.

[0005] In wireless communications, a communication device may perform a conditional mobility. For the conditional mobility, the communication device may be configured with one or more candidate cells and corresponding mobility conditions. The communication device may evaluate mobility conditions, and when one or more mobility conditions for a candidate cell is met, the communication device may perform the conditional mobility to the candidate cell as a target cell. However, there may be some cases mobility should be restricted.

[0006] An aspect of the present disclosure is to provide method and apparatus for mobility restriction in a wireless communication system.

[0007] According to an embodiment of the present disclosure, a method performed by a communication device adapted to operate in a wireless communication system comprises: receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells; executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0008] According to an embodiment of the present disclosure, a method performed by a network node configured to operate in a wireless communication system comprises: establishing a connection with a communication device; and transmitting, to the communication device via a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells, wherein the communication device is configured to perform operations comprising: executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0009] According to various embodiments, apparatuses to implement the above methods are provided.

[0010] The present disclosure may have various advantageous effects.

[0011] For example, the communication device can maintain access to the current serving cell and avoid unnecessary mobility. Therefore, communication interruption due to mobility execution can be reduced and network signaling can also be reduced.

[0012] 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.

[0013] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0014] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0015] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0016] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0017] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0018] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0019] FIG. 8 shows an example of a conditional mobility procedure according to an embodiment of the present disclosure.

[0020] FIG. 9 shows an example of a method performed by a communication device according to an embodiment of the present disclosure.

[0021] FIG. 10 shows an example of a signal flow between a communication device and a network node according to an embodiment of the present disclosure.

[0022] FIG. 11 shows an example of a method for restricting unnecessary handover according to an embodiment of the present disclosure.

[0023] 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, and / or 5G New Radio (NR).

[0024] 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.

[0025] 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.

[0026] 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".

[0027] 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".

[0028] 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".

[0029] 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".

[0030] 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".

[0031] Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

[0032] 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.

[0033] 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.

[0034] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0046] 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).

[0047] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0048] 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.FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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).

[0065] 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.

[0066] 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.

[0067] In the implementations of the present disclosure, a UE may operate as a transmitting device in Uplink (UL) and as a receiving device in Downlink (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.

[0068] In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

[0069] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0070] Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG. 2.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0080] 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 (L1, for example PHY layer) and Layer 2 (L2, for example MAC / RLC / PDCP layer). Referring to FIG. 5, the control plane protocol stack may be divided into Layer 1 (L1, for example PHY layer), Layer 2 (L2, for example MAC / RLC / PDCP layer), Layer 3 (L3, for example 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).

[0081] 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.

[0082] 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.

[0083] 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.

[0084] The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (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).

[0085] 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.

[0086] 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.

[0087] 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 5GC or 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.

[0088] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0089] 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., subcarrier spacing (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 CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

[0090] 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 cyclic prefix (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 βf = 2u*15 kHz.

[0091] 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 βf = 2u*15 kHz.

[0092] uNslotsymbNframe,uslotNsubframe,uslot01410111420221440431480841416016

[0093] 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 βf = 2u*15 kHz.

[0094] uNslotsymbNframe,uslotNsubframe,uslot212404

[0095] 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. As shown in FIG. 6, as SCS doubles, the slot length and symbol length are halved. For example, when SCS is 15kHz, the slot length is 1ms, which is the same as the subframe length. When SCS is 30kHz, the slot length is 0.5ms (=500us), and the symbol length is half of that when the SCS is 15kHz. When SCS is 60kHz, the slot length is 0.25ms (=250us), and the symbol length is half of that when the SCS is 30kHz. When SCS is 120kHz, the slot length is 0.125ms (=125us), and the symbol length is half of that when the SCS is 60kHz. When SCS is 240kHz, the slot length is 0.0625ms (=62.5us), and the symbol length is half of that when the SCS is 120kHz.

[0096] 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.

[0097] 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.

[0098] 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 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.

[0099] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0100] 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.

[0101] 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 physical uplink control channel (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.

[0102] Hereinafter, contents regarding mobility are described.

[0103] The mobility may comprise PCell change, PSCell change (or, secondary node (SN) change), and / or PSCell addition (or, SN addition).

[0104] In the present disclosure, the term "handover (HO)" may mean PCell change, or may be a broad concept that includes not only PCell change but also PSCell change / addition.

[0105] In the present disclosure, the terms "handover" and "mobility" can be used interchangeably.

[0106] In the present disclosure, the description regarding handover can also be applied to other mobility procedures (e.g., PSCell change / addition).

[0107] There may be at least two types of mobility: network-controlled mobility (or, legacy mobility) and UE-based mobility (or, conditional mobility).

[0108] The network-controlled mobility (or, legacy mobility) is a mobility where the network determines a target cell for mobility, and configures UE with the target cell. The network may transmit, to the UE, anRRCReconfigurationmessage comprising a configuration for the target cell. The UE may execute a mobility to the target cell and / or apply the configuration for the target cell, upon receiving the cell configuration for the target cell.

[0109] The UE-based mobility (or, conditional mobility) is a mobility where the network configures the UE with a plurality of candidate cells, and the UE determines a target cell which satisfies a mobility execution condition among the plurality of candidate cells. The conditional mobility may comprise at least one of a conditional PCell change / conditional handover (CHO) or a conditional PSCell mobility. The conditional PSCell mobility may comprise conditional PSCell addition / change (CPAC), including conditional PSCell addition (CPA) and / or conditional PSCell change (CPC). The network may transmit, to the UE, anRRCReconfigurationmessage comprisingConditionalReconfigurationinformation element (IE), which comprises a list of conditional reconfigurations for the plurality of candidate cells. A conditional reconfiguration for a candidate cell may comprise an identifier of the conditional reconfiguration, a mobility execution condition for the candidate cell, and a configuration for the candidate cell. The UE may evaluate the mobility execution conditions for the plurality of candidate cells, and when a mobility execution condition for a candidate cell is satisfied, the UE may consider the candidate cell as a target cell, and execute a mobility to the target cell and / or apply the configuration for the target cell.

[0110] According to various embodiments, the mobility execution condition may be satisfied / met when an entry condition (or, entering condition) for the mobility execution condition is satisfied / met for at least a time-to-trigger (TTT) for the mobility execution condition. The entry condition / entering condition may mean that the mobility execution condition is initially met. Once the entry condition is met, the mobility execution condition will be considered to be met if the entry condition is met for time duration TTT continuously.

[0111] FIG. 8 shows an example of a conditional mobility procedure according to an embodiment of the present disclosure.

[0112] In FIG. 8:

[0113] - the serving BS may be related to a PCell, which may be a source PCell for CHO;

[0114] - the serving BS may be an MN associated with an SN in DC, where the SN may be related to a source PSCell for CPC; and

[0115] - the target cell may be a target PCell for CHO, or a target PSCell for CPA / CPC.

[0116] Referring to FIG. 8, in step S801, UE may receive, from the serving BS, anRRCReconfiguraitonmessage comprising a conditional reconfiguration information element (IE) (i.e.,CondidtionalReconfiguration). The conditional reconfiguration IE may comprise a list of conditional reconfigurations for candidate cells including the target cell. Each conditional reconfiguration in the list may be related to the corresponding candidate cell, and comprises i) an identifier of the corresponding conditional reconfiguration (i.e.,condReconfigId), ii) one or more execution conditions for the corresponding candidate cell (i.e.,condExecutionCond), and / or iii) RRC reconfiguration for the corresponding candidate cell (i.e.,condRRCReconfig) including a cell configuration (e.g., candidate cell configuration / target cell configuration) for the corresponding candidate cell. The one or more execution conditions may comprise CHO execution condition(s), CPA execution condition(s), and / or CPC execution condition(s).

[0117] In step S803, the UE may start evaluating the one or more execution conditions for the candidate cells.

[0118] In step S805, if the target cell satisfies the corresponding execution condition(s), the UE may execute the conditional mobility towards the target cell and / or apply the RRC reconfiguration for the target cell including a cell configuration for the target cell. When / upon executing the conditional mobility and / or applying the RRC reconfiguration (e.g.,RRCReconfigurationincludingReconfigurationWithSync) for the target cell, the UE may start a timer (e.g., T304 timer). The timer value of the T304 timer (i.e., T304 timer value) for the target cell may be included in theReconfigurationWithSyncinRRCReconfigurationfor the target cell.

[0119] While the timer is running, the UE may perform DL synchronization and / or UL synchronization (e.g., random access) towards the target cell. The UE may skip the random access towards the target cell if timing advance (TA) information for the target cell is available.

[0120] In step S807, the UE, serving BS and / or BS related to the target cell may perform actions related to conditional mobility completion. For example, upon successful completion of the random access on the corresponding target cell, the UE may stop the timer (e.g., T304 timer).

[0121] According to various embodiments, the UE may receive a list of conditional reconfigurations (i.e.,CondReconfigToAddModListIE) from a network. The IECondReconfigToAddModListconcerns a list of conditional reconfigurations to add or modify, with for each entry thecondReconfigIdand the associated fields, as shown in table 5 below:

[0122] CondReconfigToAddModList-r16 ::= SEQUENCE (SIZE (1.. maxNrofCondCells-r16)) OF CondReconfigToAddMod-r16CondReconfigToAddMod-r16 ::= SEQUENCE {condReconfigId-r16 CondReconfigId-r16,condExecutionCond-r16 SEQUENCE (SIZE (1..2)) OF MeasId OPTIONAL, -- Need McondRRCReconfig-r16 OCTET STRING (CONTAINING RRCReconfiguration) OPTIONAL, -- Cond condReconfigAdd...,[[condExecutionCondSCG-r17 OCTET STRING (CONTAINING CondReconfigExecCondSCG-r17) OPTIONAL -- Need M]],[[condExecutionCondPSCell-r18 SEQUENCE (SIZE (1..2)) OF MeasId OPTIONAL, -- Cond condReconfigCHO-WithSCGsubsequentCondReconfig-r18 SubsequentCondReconfig-r18 OPTIONAL, -- Need MsecurityCellSetId-r18 SecurityCellSetId-r18 OPTIONAL, -- Need Mscpac-ConfigComplete-r18 ENUMERATED {true} OPTIONAL -- Cond CPAC]]}CondReconfigExecCondSCG-r17 ::= SEQUENCE (SIZE (1..2)) OF MeasIdSubsequentCondReconfig-r18 ::= SEQUENCE {condExecutionCondToReleaseList-r18 CondExecutionCondToReleaseList-r18 OPTIONAL, -- Need NcondExecutionCondToAddModList-r18 CondExecutionCondToAddModList-r18 OPTIONAL, -- Need N...}CondExecutionCondToAddModList-r18 ::= SEQUENCE (SIZE (1.. maxNrofCondCells-r16)) OF CondExecutionCondToAddMod-r18CondExecutionCondToAddMod-r18 ::= SEQUENCE {condReconfigId-r18 CondReconfigId-r16,condExecutionCond-r18 SEQUENCE (SIZE (1..2)) OF MeasId OPTIONAL, -- Need McondExecutionCondSCG-r18 OCTET STRING (CONTAINING CondReconfigExecCondSCG-r17) OPTIONAL, -- Need M...}CondExecutionCondToReleaseList-r18 ::= SEQUENCE (SIZE (1.. maxNrofCondCells-r16)) OF CondReconfigId-r16

[0123] In table 5:-condExecutionCond(e.g., execution condition of second type for target PSCell) is the execution condition that needs to be fulfilled in order to trigger the execution of a conditional reconfiguration for CHO, CPA, intra-SN CPC without MN involvement, MN initiated inter-SN CPC, or SN initiated intra-SN subsequent CPAC without MN involvement. When configuring 2 triggering events (Meas Ids) for a candidate cell, the network ensures that both refer to the samemeasObject.For CHO, if the network configurescondEventD1orcondEventT1for a candidate cell, the network configures a second triggering eventcondEventA3, condEventA4orcondEventA5for the same candidate cell. The network does not configure bothcondEventD1andcondEventT1for the same candidate cell. For CHO in terrestrial networks, the network does not indicate aMeasIdassociated withcondEventA4. For CPA and for MN-initiated inter-SN CPC, the network only indicatesMeasId(s) associated withcondEventA4. For intra-SN CPC and intra-SN subsequent CPAC, the network only indicatesMeasId(s) associated withcondEventA3orcondEventA5;

[0124] -condExecutionCondPSCell(i.e., execution condition of first type for target PSCell) is the execution condition that needs to be fulfilled for the associated PSCell in order to trigger the execution of a conditional reconfiguration for CHO with candidate SCG(s). The Meas Ids refer to themeasConfigassociated with the MCG. When configuring 2 triggering events (Meas Ids) for a candidate cell, network ensures that both refer to the samemeasObject. The network only indicatesMeasId(s)associated with condEventA4;

[0125] -condExecutionCondSCGcontains execution condition that needs to be fulfilled in order to trigger the execution of a conditional reconfiguration for SN initiated inter-SN CPC, SN initiated inter-SN subsequent CPAC, SN initiated intra-SN subsequent CPAC with MN involvement, or MN initiated inter-SN subsequent CPAC. The Meas Ids refer to themeasConfigassociated with the SCG. When configuring 2 triggering events (Meas Ids) for a candidate cell, network ensures that both refer to the samemeasObject. For eachcondReconfigId, the network always configures eithercondExecutionCondorcondExecutionCondSCG(not both). The network only indicatesMeasId(s) associated withcondEventA3orcondEventA5;

[0126] -condRRCReconfigis theRRCReconfigurationmessage comprising a cell configuration for the corresponding target cell to be applied when the condition(s) are fulfilled. TheRRCReconfigurationmessage contained incondRRCReconfigcannot contain the fieldconditionalReconfigurationor the fielddaps-Config;

[0127] -scpac-ConfigCompleteindicates whether the configuration contained incondRRCReconfigfor subsequent CPAC is a complete configuration; and

[0128] -subsequentCondReconfigcontains the execution conditions (e.g., execution condition of second type for target PSCell) that need to be fulfilled in order to trigger the execution of a subsequent CPAC. If the field is configured, the configuration of candidate PSCells for subsequent CPAC is supported. The subsequent execution condition is used for conditional reconfiguration evaluation for other candidate cells when theRRCReconfigurationmessage contained incondRRCReconfighas been applied.

[0129] After receiving the list of conditional reconfigurations, the UE may perform conditional reconfiguration evaluation. The UE shall:

[0130] 1> for eachcondReconfigIdwithin theVarConditionalReconfig:

[0131] 2> if theRRCReconfigurationwithincondRRCReconfigincludes themasterCellGroupincluding thereconfigurationWithSync:

[0132] 3> if the associatedcondExecutionCondPSCellis configured:

[0133] 4> consider the cell which has a physical cell identity matching the value indicated in theServingCellConfigCommonincluded in thereconfigurationWithSyncwithin themasterCellGroupin the receivedcondRRCReconfigto be applicable cell; and

[0134] 4> consider the cell which has a physical cell identity matching the value indicated in theServingCellConfigCommonincluded in thereconfigurationWithSyncwithin thesecondaryCellGroupwithin thenr-SCGwithin the receivedcondRRCReconfigto be applicable cell;

[0135] 3> else:

[0136] 4> consider the cell which has a physical cell identity matching the value indicated in theServingCellConfigCommonincluded in thereconfigurationWithSyncwithin themasterCellGroupin the receivedcondRRCReconfigto be applicable cell;

[0137] 2> else if theRRCReconfigurationwithincondRRCReconfigincludes thesecondaryCellGroupincluding thereconfigurationWithSync:

[0138] 3> if the cell which has a physical cell identity matching the value indicated in theServingCellConfigCommonincluded in thereconfigurationWithSyncwithin thesecondaryCellGroupwithin the receivedcondRRCReconfigis not the PSCell:

[0139] 4> consider the cell to be applicable cell;

[0140] 2> ifcondExecutionCondSCGis configured:

[0141] 3> in the remainder of the procedure, consider eachmeasIdindicated in thecondExecutionCondSCGas ameasIdin theVarMeasConfigassociated with the SCGmeasConfig;

[0142] 2> if thecondExecutionCondPSCellis configured:

[0143] 3> in the remainder of the procedure, consider eachmeasIdindicated in thecondExecutionCondPSCellas ameasIdin theVarMeasConfigassociated with the MCGmeasConfig;

[0144] 2> ifcondExecutionCondis configured:

[0145] 3> if it is configured via SRB3 or configured withinnr-SCGor withinnr-SecondaryCellGroupConfigvia SRB1:

[0146] 4> in the remainder of the procedure, consider eachmeasIdindicated in thecondExecutionCondas ameasIdin theVarMeasConfigassociated with the SCGmeasConfig;

[0147] 3> else:

[0148] 4> in the remainder of the procedure, consider eachmeasIdindicated in thecondExecutionCondas ameasIdin theVarMeasConfigassociated with the MCGmeasConfig;

[0149] 2> for eachmeasIdincluded in themeasIdListwithinVarMeasConfigindicated in thecondExecutionCond,condExecutionCondSCG,orcondExecutionCondPSCellassociated tocondReconfigId:

[0150] 3> if thecondEventIdis associated withcondEventT1, and if the entry condition applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cell; or

[0151] 3> if thecondEventIdis associated withcondEventD1, and if the entry conditions applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cell during the correspondingtimeToTriggerdefined for this event within theVarConditionalReconfig; or

[0152] 3> if thecondEventIdis associated withcondEventA3,condEventA4orcondEventA5, and if the entry condition(s) applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cells for all measurements after layer 3 filtering taken during the correspondingtimeToTriggerdefined for this event within theVarConditionalReconfig:

[0153] 4> consider the event associated to thatmeasIdto be fulfilled;

[0154] 3> if themeasIdfor this event associated with thecondReconfigIdhas been modified; or

[0155] 3> if thecondEventIdis associated withcondEventT1, and if the leaving condition applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cell; or

[0156] 3> if thecondEventIdis associated withcondEventD1, and if the leaving condition(s) applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cell during the correspondingtimeToTriggerdefined for this event within theVarConditionalReconfig; or

[0157] 3> if thecondEventIdis associated withcondEventA3,condEventA4orcondEventA5, and if the leaving condition(s) applicable for this event associated with thecondReconfigId, i.e. the event corresponding with thecondEventId(s)of the correspondingcondTriggerConfigwithinVarConditionalReconfig, is fulfilled for the applicable cells for all measurements after layer 3 filtering taken during the correspondingtimeToTriggerdefined for this event within theVarConditionalReconfig:

[0158] 4> consider the event associated to thatmeasIdto be not fulfilled;

[0159] 2> ifcondExecutionCondPSCellis not configured:

[0160] 3> if event(s) associated to allmeasId(s) withincondTriggerConfigfor the applicable cell are fulfilled:

[0161] 4> consider the applicable cell, associated to thatcondReconfigId, as a triggered cell;

[0162] 4> initiate the conditional reconfiguration execution;

[0163] 2> else:

[0164] 3> if event(s) associated to allmeasId(s), as indicated in thecondExecutionCondandcondExecutionCondPSCell,withincondTriggerConfigfor a target candidate cell within the storedcondRRCReconfigare fulfilled:

[0165] 4> consider the target candidate PCell within the storedcondRRCReconfig, associated to thatcondReconfigId, as a triggered PCell;

[0166] 4> consider the target candidate PSCell within the storedcondRRCReconfig, associated to thatcondReconfigId, as a triggered PSCell;

[0167] 4> initiate the conditional reconfiguration execution.

[0168] Up to 2MeasIdcan be configured for eachcondReconfigId, ifcondExecutionCondPSCellis not configured.The conditional reconfiguration event of the 2MeasIdmay have the same or different event conditions, triggering quantity, time to trigger, and triggering threshold.

[0169] For CHO with candidate SCGs, up to 2MeasIdcan be configured forcondExecutionCondandup to 2MeasIdcan be configured forcondExecutionCondPSCellfor eachcondReconfigId.

[0170] Upon the conditional reconfiguration execution, the UE shall:

[0171] 1> if more than one pair of triggered PCell and associated triggered PSCell exist:

[0172] 2> select one of the triggered PCell(s) and the associated triggered PSCell(s) as the selected cells for conditional reconfiguration execution;

[0173] 1> else if only one pair of triggered PCell and associated triggered PSCell exists:

[0174] 2> consider the triggered PCell and the associated triggered PSCell as the selected cells for conditional reconfiguration execution;

[0175] 1> else if more than one triggered cell exists:

[0176] 2> select one of the triggered cells as the selected cell for conditional reconfiguration execution;

[0177] 1> else:

[0178] 2> consider the triggered cell as the selected cell for conditional reconfiguration execution;

[0179] 1> for the selected cell(s) of conditional reconfiguration execution:

[0180] 2> if thesubsequentCondReconfigis included in the entry inVarConditionalReconfigcontaining theRRCReconfigurationmessage for the selected cell:

[0181] 3> perform the subsequent CPAC execution;

[0182] 2> else:

[0183] 3> apply the storedcondRRCReconfigof the selected cell and applyRRCReconfigurationin thecondRRCReconfig.

[0184] If multiple NR cells are triggered in conditional reconfiguration execution, the UE may select one of them. For example, the UE may consider beams and / or beam quality to select one of the triggered cells for execution.

[0185] Meanwhile, mobility needs to be triggered when serving cell quality is not sufficiently good and / or neighbour cell quality is sufficiently good or relatively better.

[0186] UE may be configured with multiple conditional mobility candidates. When channel quality changes dynamically, conditional mobility may occur frequently. Such frequent mobility events may include ping-pong mobility (for example, mobility through cell A -> B -> A) or subsequent / successive mobility events with a short dwelling / service time.

[0187] Such frequent mobility event may increase mobility interruption that may be caused by L1 / L2 / L3 reset or reestablishment or by path switching of data transport involving RAN(e.g., base station) and core network. To avoid such increased interruption, too frequent handover needs to be restricted. But at the same time, if mobility is restricted inappropriately, it may severely degrade UE connection performance.

[0188] So, a balanced control method to restrict unnecessary handover while avoiding restriction of necessary handover is needed.

[0189] FIG. 9 shows an example of a method performed by a communication device according to an embodiment of the present disclosure. The method may also be performed by UE and / or wireless device.

[0190] Referring to FIG. 9, in step S901, the communication device may receive, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells.

[0191] In step S903, the communication device may execute a conditional mobility to a second cell among the one or more candidate cells.

[0192] In step S905, upon successful completion of the conditional mobility to the second cell, the communication device may start a timer (e.g., mobility restriction timer).

[0193] In step S907, while the timer is running, the communication device may: skip executing a subsequent conditional mobility; and determine whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0194] According to various embodiments, while the timer is running, the communication device may: evaluate mobility conditions for the subsequent conditional mobility; and skip executing the subsequent conditional mobility based on at least one of the mobility conditions being fulfilled.

[0195] According to various embodiments, while the timer is running, the communication device may stop evaluating mobility conditions for the subsequent conditional mobility.

[0196] According to various embodiments, the communication device may receive, from the network, a configuration of whether to evaluate mobility conditions for the subsequent conditional mobility or stop evaluating mobility conditions for the subsequent conditional mobility while the timer is running.

[0197] According to various embodiments, while the timer is running, the communication device may perform measurements on one or more candidate cells for the subsequent conditional mobility regardless of whether mobility conditions for the subsequent conditional mobility are evaluated or not.

[0198] According to various embodiments, the connection status of the second cell may comprise a quality of the second cell. The communication device may stop the timer based on the quality of the second cell being lower than a threshold configured by the network.

[0199] According to various embodiments, the connection status of the second cell may comprise whether a radio link failure or connection failure is detected or expected to be detected within a time period on the second cell. The communication device may stop the timer based on a radio link failure or connection failure being detected on the second cell.

[0200] According to various embodiments, the connection status of the second cell may comprise whether a recovery from a radio link failure or connection failure on the second cell is initiated. The communication device may stop the timer based on a recovery from a radio link failure or connection failure on the second cell being not initiated.

[0201] According to various embodiments, upon receiving the network command for the mobility to the target cell, the communication device may: stop the timer; and perform the mobility to the target cell.

[0202] According to various embodiments, after the timer is stopped or expires, the communication device may: evaluating mobility conditions for the subsequent conditional mobility; and performing the subsequent conditional mobility to a third cell for which one or more mobility conditions are satisfied.

[0203] According to various embodiments, the network command comprises a timer value. Upon receiving the network command for the mobility to the target cell, the communication device may: restart the timer with the timer value; and perform the mobility to the target cell.

[0204] According to various embodiments, upon receiving the network command for the mobility to the target cell, the communication device may perform the mobility to the target cell while keeping the timer running.

[0205] According to various embodiments, the communication device may receive a configuration for one or more candidates of conditional mobility. One or more mobility conditions may be configured for each candidate. The communication device may receive a configuration including a timer value of a timer (e.g., mobility restriction timer) related to the candidates. Based on the mobility condition being met or based on a network command for immediate handover, the communication device may perform a mobility to the candidate, as a new serving cell, related to the mobility condition being met. Based on the successful mobility to the candidates related to the timer, the communication device may start a timer to the timer value. The communication device may determine whether to stop the timer, based on the connection status of the new serving cell or network command. While the timer is running, the communication device may skip execution of the mobility to any of the candidates related to the timer.

[0206] FIG. 10 shows an example of a signal flow between a communication device and a network node according to an embodiment of the present disclosure. The network node may comprise a base station (BS).

[0207] Referring to FIG. 10, in step S1001, the network node may establish a connection with the communication device.

[0208] In step S1003, the network node may transmit, to the communication device through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells.

[0209] In step S1005, the communication device may execute a conditional mobility to a second cell among the one or more candidate cells.

[0210] In step S1007, upon successful completion of the conditional mobility to the second cell, the communication device may start a timer (e.g., mobility restriction timer).

[0211] In step S1009, while the timer is running, the communication device may: skip executing a subsequent conditional mobility; and determine whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0212] Hereinafter, detailed implementations regarding restricting unnecessary handover are described.

[0213] FIG. 11 shows an example of a method for restricting unnecessary handover according to an embodiment of the present disclosure.

[0214] Referring to FIG. 11, in step S1101, UE may receive a conditional mobility configuration (e.g.,ConditionalReconfiguration) comprising one or more mobility conditions to perform conditional mobility.

[0215] UE may be configured with one or more candidates (e.g., candidate cells) of conditional mobility.

[0216] For each of the candidates of the conditional mobility, UE may be configured with one or more mobility execution conditions.

[0217] For each of the candidates of the conditional mobility, UE may be configured with candidate cell configuration to apply upon execution of the condition mobility to the candidate cell.

[0218] The mobility may comprise a change of a special cell (SpCell) e.g., PCell or PSCell.

[0219] In step S1103, the UE may receive a configuration for one or more conditions to stop a mobility restriction timer.

[0220] In some implementations, the condition may be related to radio quality of a cell. For example, the condition may be related to radio quality of a serving cell, and / or radio quality of a neighbour cell.

[0221] In some implementations, the condition may be related to quality of the current connection.

[0222] In some implementations, the condition may be related to whether the radio link failure has been detected.

[0223] In some implementations, the condition may be related to whether connection failure has been detected.

[0224] In some implementations, the condition may be related to whether recovery from the radio link failure / connection failure has been initiated.

[0225] In some implementations, the condition may be defined such that reception of mobility command is considered as a condition to stop the mobility restriction timer.

[0226] In some implementations, the condition may be defined such that the mobility restriction timer stops if UE receives a network command instructing to stop the mobility restriction timer.

[0227] In step S1105, UE may execute a conditional mobility from a first cell to a second cell based on a mobility condition for the second cell being fulfilled.

[0228] In step S1107, upon a successful execution of the conditional mobility from the first cell to the second cell, UE may start the mobility restriction timer.

[0229] In step S1109, while the mobility restriction timer is running, UE may stop / skip executing a conditional mobility from the second cell to another cell. That is, while the mobility restriction timer is running, UE does not execute a conditional mobility from the second cell to another cell.

[0230] In some implementations, while the mobility restriction timer is running, UE may keep performing evaluation of mobility condition(s) for candidate cells. However, even if a mobility condition for a candidate cell is met, UE does not execute a condition mobility towards the candidate cell for which the mobility condition is fulfilled.

[0231] In some implementations, while the mobility restriction timer is running, UE may consider the mobility candidates as invalid candidates.

[0232] In some implementations, while the mobility restriction timer is running, UE may stop / skip performing evaluation of mobility condition(s), and as a result, UE does not execute a conditional mobility related to the mobility condition(s).

[0233] In some implementations, network may configure UE with a configuration of whether to keep evaluating or stop / skip evaluating the mobility condition(s) while the mobility restriction timer is running.

[0234] For example, the configuration may be configured and applied per mobility candidate.

[0235] For example, the configuration may be configured and applied per mobility condition,

[0236] For example, the configuration may be commonly configured and applied for all candidates related to the mobility condition(s).

[0237] In step S1111, UE may determine whether to stop the mobility restriction timer. For example, while the mobility restriction timer is running, if the condition to stop the mobility restriction timer is met, UE may stop the mobility restriction timer.

[0238] In some implementations, while the mobility restriction timer is not running (e.g., due to the stop of the mobility restriction timer), UE may evaluate the mobility condition(s). If the mobility condition(s) is met, UE may execute the conditional mobility related to the mobility condition(s) being met.

[0239] In some implementations, UE may be configured with a configuration of whether to re-start the mobility restriction timer upon a successful execution of a non-conditional mobility from a first cell to a second cell (i.e., immediate (legacy) mobility / handover triggered by network command such as (legacy) mobility / handover command). The (legacy) mobility / handover command may indicate whether to (re-)start the mobility restriction timer.

[0240] In some implementations, UE may be configured with a configuration of whether to keep the mobility restriction timer running, upon a successful execution of a non-conditional mobility from a first cell to a second cell (i.e., immediate (legacy) mobility / handover triggered by network command such as (legacy) mobility / handover command). The (legacy) mobility / handover command may indicate whether to keep the mobility restriction timer running.

[0241] Hereinafter, various examples regarding mobility restriction are provided.

[0242] Example 1 - ping-pong restriction

[0243] In this example, it is assumed that:

[0244] - UE is connected to cell1 serving as a PCell;

[0245] - UE is configured with cell1, cell2 and cell3 as candidates of conditional mobility;

[0246] - UE is configured with a timer value for a mobility restriction timer related to the cell 1, cell2 and / or cell3. The mobility restriction timer is effective for mobility to cell1, cell2 and / or cell3; and

[0247] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0248] UE may evaluate mobility conditions related to the cell2 and cell3 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon a successful completion of the conditional mobility to the cell 2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell 1 and / or cell 3). UE may evaluate the mobility conditions related to the cell1 and cell3 as mobility target respectively. While the mobility restriction timer is running, the mobility condition related to the cell1 is met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell1. /

[0249] After the mobility restriction timer expires (or, while the mobility restriction timer is not running), UE may identify that the mobility condition related to the cell1 is met. Then, UE may execute conditional mobility to the cell1.

[0250] Example 2 - ping-pong restriction with early timer stopping

[0251] In this example, it is assumed that:

[0252] - UE is connected to cell1 serving as a PCell;

[0253] - UE is configured with cell1, cell2 and cell3 as candidates of conditional mobility;

[0254] - UE is configured with a timer value for a mobility restriction timer related to the cell1, cell2 and / or cell3. The mobility restriction timer is effective for mobility to cell1, cell2 and / or cell3; and

[0255] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0256] UE may evaluate mobility conditions related to the cell2 and cell3 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon a successful execution of the conditional mobility to the cell2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell1 and / or cell3). UE may identify that the quality of the cell2 which is the current serving cell is higher than the serving cell quality threshold. Hence UE may keep the mobility restriction timer running.

[0257] UE may evaluate the mobility conditions related to the cell1 and cell3 as mobility target, respectively. While the mobility restriction timer is running, the mobility condition related to the cell1 is met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell1.

[0258] UE may identify that the quality of the cell2 which is the current serving cell becomes lower than the serving cell quality threshold. Then, UE may stop the mobility restriction timer. UE may identify that the mobility condition related to the cell1 is met after the mobility restriction timer is stopped (or, while the mobility restriction timer is not running). Then, UE may execute conditional mobility to the cell1.

[0259] Example 3 - restriction of too frequent handover

[0260] In this example, it is assumed that:

[0261] - UE is connected to cell1 serving as a PCell;

[0262] - UE is configured with cell1, cell2 and cell3 as candidates of conditional mobility;

[0263] - UE is configured with a timer value for a mobility restriction timer related to the cell1, cell2 and / or cell3. The timer is effective for mobility to cell1, cell2 and / or cell3; and

[0264] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0265] UE may evaluate mobility conditions related to the cell2 and cell3 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon a successful execution of the conditional mobility to the cell2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell1 and / or cell3). UE may evaluate the mobility conditions related to the cell1 and cell3 as mobility target, respectively. While the mobility restriction timer is running, the mobility condition related to the cell3 is met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell3.

[0266] After the timer expires (or, while the mobility restriction timer is not running), UE may identify that the mobility condition related to the cell3 is met. Then, UE may execute conditional mobility to the cell3.

[0267] Example 4 - restriction of too frequent handover with early timer stopping

[0268] In this example, it is assumed that:

[0269] - UE is connected to cell1 serving as a PCell;

[0270] - UE is configured with cell1, cell2 and cell3 as candidates of conditional mobility;

[0271] - UE is configured with a timer value for a mobility restriction timer related to the cell1, cell2 and / or cell3. The timer is effective for mobility to cell1, cell2 and / or cell3; and

[0272] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0273] UE may evaluate mobility conditions related to the cell2 and cell3 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon successful execution of conditional mobility to the cell2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell1 and / or cell3). UE may identify that the quality of the cell2 which is the current serving cell is higher than the serving cell quality threshold. Hence UE may keep the mobility restriction timer running.

[0274] UE may evaluate the mobility conditions related to the cell1 and cell3 as mobility target, respectively. While the mobility restriction timer is running, the mobility condition related to the cell3 may be met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell3.

[0275] UE may identify that the quality of the cell2 which is the current serving cell becomes lower than the serving cell quality threshold. Then, UE may stop the mobility restriction timer.

[0276] After the mobility restriction timer is stopped (or, while the mobility restriction timer is not running), UE may identify that the mobility condition related to the cell3 is met. Then, UE may execute conditional mobility to the cell3.

[0277] Example 5 - timer restart upon handover

[0278] In this example, it is assumed that:

[0279] - UE is connected to cell1 serving as a PCell;

[0280] - UE is configured with cell1, cell2, cell3 and cell4 as candidates of conditional mobility;

[0281] - UE is configured with a timer value for a mobility restriction timer related to the cell1, cell2, cell3 and / or cell4. The mobility restriction timer is effective for mobility to cell1, cell2, cell3 and / or cell4; and

[0282] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0283] UE may evaluate mobility conditions related to the cell2, cell3 and cell4 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon a successful execution of conditional mobility to the cell2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell1, cell3 and / or cell4). UE may evaluate the mobility conditions related to the cell1, cell3 and cell4 as mobility target, respectively. While the mobility restriction timer is running, the mobility condition related to the cell3 may be met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell3.

[0284] UE may receive a network command (e.g., (legacy) mobility / handover command) triggering a mobility to the cell3. Upon receiving the network command triggering a mobility to the cell3, UE may perform a mobility to the cell3. The network command may include a timer value. UE may re-start the mobility restriction timer set to the timer value indicated by the network command. While the mobility restriction timer is running, the mobility condition related to the cell4 may be met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell4.

[0285] After the mobility restriction timer expires (or, while the mobility restriction timer is not running), UE may identify that the mobility condition related to the cell4 is met. Then, UE may execute conditional mobility to the cell4.

[0286] Example 6 - timer continuation upon handover

[0287] In this example, it is assumed that:

[0288] - UE is connected to cell1 serving as a PCell;

[0289] - UE is configured with cell1, cell2, cell3 and cell4 as candidates of conditional mobility;

[0290] - UE is configured with a timer value for a mobility restriction timer related to the cell1, cell2, cell3 and / or cell4. The mobility restriction timer is effective for mobility to cell1, cell2, cell3 and / or cell4; and

[0291] - UE is configured with a serving cell quality threshold related to the mobility restriction timer.

[0292] UE may evaluate mobility conditions related to the cell2, cell3 and cell4 as mobility target, respectively. When the mobility condition for cell2 is met, UE may perform conditional mobility to the cell2 related to the mobility condition being met. UE may access the cell2 as a new PCell. UE may start a mobility restriction timer set to the configured timer value upon a successful execution of conditional mobility to the cell2. UE may perform measurements of cells including the cell2 and possibly other mobility candidates (e.g., cell1, cell2 and / or cell4). UE may evaluate the mobility conditions related to the cell1, cell3 and cell4 as mobility target, respectively. While the mobility restriction timer is running, the mobility condition related to the cell3 may be met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell3.

[0293] UE may receive a network command (e.g., (legacy) mobility / handover command) triggering a mobility to the cell3. Upon receiving the network command, UE may perform a mobility to the cell3. UE may keep the mobility restriction timer running. While the mobility restriction timer is running, the mobility condition related to the cell4 may be met. Since the mobility restriction timer is running, UE does not execute conditional mobility to the cell4.

[0294] After the mobility restriction timer expires (or, while the mobility restriction timer is not running), UE identify that the mobility condition related to the cell4 (or cell1 / 2) is met. Then, UE may execute conditional mobility to the cell4 (or cell1 / cell2).

[0295] Furthermore, the method in perspective of the communication device described in the present disclosure (e.g., in FIG. 9) may be performed by the first wireless device 100 shown in FIG. 2 and / or the UE 100 shown in FIG. 3.

[0296] More specifically, the communication device comprises at least one transceiver comprising a first receiver and a second receiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0297] The operations comprise: receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells; executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0298] Furthermore, the method in perspective of the communication device described in the present disclosure (e.g., in FIG. 9) may be performed by a software code 105 stored in the memory 104 included in the first wireless device 100 shown in FIG. 2.

[0299] More specifically, at least one computer readable medium (CRM) stores instructions that, based on being executed by at least one processor, perform operations comprising: receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells; executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0300] Furthermore, the method in perspective of the communication device described in the present disclosure (e.g., in FIG. 9) may be performed by control of the processor 102 included in the first wireless device 100 shown in FIG. 2 and / or by control of the processor 102 included in the UE 100 shown in FIG. 3.

[0301] More specifically, an apparatus configured to / adapted to operate in a wireless communication system (e.g., communication device / UE) comprises at least processor, and at least one computer memory operably connectable to the at least one processor. The at least one processor is configured to / adapted to perform operations comprising: receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells; executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0302] Furthermore, the method in perspective of a network node described in the present disclosure (e.g., in FIG. 10) may be performed by the second wireless device 200 shown in FIG. 2. The network node may be related to a serving cell.

[0303] More specifically, the network node comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0304] The operations comprise: establishing a connection with a communication device; and transmitting, to the communication device via a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells, wherein the communication device is configured to perform operations comprising: executing a conditional mobility to a second cell among the one or more candidate cells; upon successful completion of the conditional mobility to the second cell, starting a timer; and while the timer is running: skipping executing a subsequent conditional mobility; and determining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

[0305] The present disclosure may have various advantageous effects.

[0306] For example, the communication device can maintain access to the current serving cell and avoid unnecessary mobility. Therefore, communication interruption due to mobility execution can be reduced and network signaling can also be reduced.

[0307] 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.

[0308] 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

1.A method performed by a communication device adapted to operate in a wireless communication system, the method comprising:receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells;executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.2.The method of claim 1, wherein, while the timer is running, the skipping of executing the subsequent conditional mobility comprises:evaluating mobility conditions for the subsequent conditional mobility; andskipping executing the subsequent conditional mobility based on at least one of the mobility conditions being fulfilled.3.The method of claim 1, wherein, while the timer is running, the skipping of executing the subsequent conditional mobility comprises:stop evaluating mobility conditions for the subsequent conditional mobility.4.The method of claim 1, further comprising receiving, from the network, a configuration of whether to evaluate mobility conditions for the subsequent conditional mobility or stop evaluating mobility conditions for the subsequent conditional mobility while the timer is running.5.The method of claim 1, further comprising while the timer is running, performing measurements on one or more candidate cells for the subsequent conditional mobility regardless of whether mobility conditions for the subsequent conditional mobility are evaluated or not.6.The method of claim 1, wherein the connection status of the second cell comprises a quality of the second cell, andwherein the method further comprises stopping the timer based on the quality of the second cell being lower than a threshold configured by the network.7.The method of claim 1, wherein the connection status of the second cell comprises whether a radio link failure or connection failure is detected or expected to be detected within a time period on the second cell, andwherein the method further comprises stopping the timer based on a radio link failure or connection failure being detected on the second cell.8.The method of claim 1, wherein the connection status of the second cell comprises whether a recovery from a radio link failure or connection failure on the second cell is initiated, andwherein the method further comprises stopping the timer based on a recovery from a radio link failure or connection failure on the second cell being not initiated.9.The method of claim 1, further comprising upon receiving the network command for the mobility to the target cell:stopping the timer; andperforming the mobility to the target cell.10.The method of claim 1, further comprising after the timer is stopped or expires:evaluating mobility conditions for the subsequent conditional mobility; andperforming the subsequent conditional mobility to a third cell for which one or more mobility conditions are satisfied.11.The method of claim 1, wherein the network command comprises a timer value, andwherein the method further comprises, upon receiving the network command for the mobility to the target cell:restarting the timer with the timer value; andperforming the mobility to the target cell.12.The method of claim 1, further comprising upon receiving the network command for the mobility to the target cell:performing the mobility to the target cell while keeping the timer running.13.The method of claims 1, wherein the communication device is in communication with at least one of a user equipment (UE), a mobile device, a network, or autonomous vehicles.14.A communication device configured to operate in a wireless communication system, the UE comprising:at least one transceiver comprising a first receiver and a second receiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells;executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer with a timer value received from the network; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.15.The communication device of claim 14, wherein the communication device is adapted to implement a method of one of claims 2 to 13.16.A network node configured to operate in a wireless communication system, the network node comprising:at least one transceiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:establishing a connection with a communication device; andtransmitting, to the communication device via a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells,wherein the communication device is configured to perform operations comprising:executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.17.A method performed by a network node configured to operate in a wireless communication system, the method comprising:establishing a connection with a communication device; andtransmitting, to the communication device via a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells,wherein the communication device is configured to perform operations comprising:executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.18.The method of claim 17, wherein the communication device is adapted to implement a method of one of claims 1 to 13.19.An apparatus adapted to operate in a wireless communication system, the apparatus comprising:at least processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells;executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer with a timer value received from the network; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.20.A non-transitory computer readable medium (CRM) having stored thereon a program code implementing instructions that, based on being executed by at least one processor, perform operations comprising:receiving, from a network through a first cell, a conditional mobility configuration comprising corresponding one or more mobility conditions for each of one or more candidate cells;executing a conditional mobility to a second cell among the one or more candidate cells;upon successful completion of the conditional mobility to the second cell, starting a timer with a timer value received from the network; andwhile the timer is running:skipping executing a subsequent conditional mobility; anddetermining whether to stop the timer based on at least one of i) a connection status of the second cell, or ii) receiving a network command for a mobility to a target cell.

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