User equipment, base stations, integrated circuits, and methods

Abstract

The present disclosure relates to a user equipment (UE) including a processing circuit that performs power-related measurements on at least one radio carrier and generates measurement results based on the performed power-related measurements. Reporting of the measurement results is based on a reporting trigger condition. The processing circuit determines whether to adjust the measurement results and / or the reporting trigger condition to trigger reporting of the measurement results earlier than would be the case without the adjustment. If the adjustment is determined, the processing circuit adjusts the measurement results and / or the reporting trigger condition to trigger reporting of the measurement results earlier than would be the case without the adjustment. The processing circuit determines whether the reporting trigger condition is met to report the measurement results after the adjustment. If reporting of the measurement results is triggered, a transmitter transmits a measurement report including the measurement results.

Description

[[TECHNICAL FIELD]]

[0001] The present disclosure relates to methods, devices and products in communication systems such as 3GPP communication systems. [[BACKGROUND ART]]

[0002] Currently, the 3rd Generation Partnership Project (3GPP) is working on technical specifications for next-generation cellular technology, also referred to as the 5th Generation (5G).

[0003] One object is to provide a single technical framework that addresses all usage scenarios, requirements and deployment scenarios, including at least enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC). For example, eMBB deployment scenarios may include indoor hotspots, dense urban areas, suburbs, urban areas, and high-speed scenarios. URLLC deployment scenarios may include industrial control systems, mobile healthcare (remote monitoring, diagnosis and treatment), real-time vehicle control, and wide-area monitoring and control systems for smart grids. mMTC deployment scenarios may include scenarios that use a large number of devices for data transmission with low delay sensitivity, such as smart wearables and sensor networks. eMBB services and URLLC services are similar in that both require a very wide bandwidth, but differ in that URLLC services may preferably require ultra-low latency.

[0004] A second object is to achieve forward compatibility. Backward compatibility for Long Term Evolution (LTE, LTE-A) cellular systems is not required, which facilitates the introduction of completely new system designs and / or new features. [Overview of the Initiative]

[0005] One non-limiting and exemplary embodiment contributes to providing an improved procedure for measurement and handover.

[0006] In one embodiment, the technology disclosed herein features a user device (UE) comprising a processing circuit that, during operation, performs power-related measurements on at least one radio carrier and generates measurement results based on the power-related measurements performed. The reporting of measurement results by the UE is based on at least one reporting trigger condition that must be satisfied. The processing circuit determines whether to adjust the measurement results and at least one of the at least one reporting trigger condition in order to trigger the reporting of the measurement results sooner than if no adjustment were made. If it decides to adjust, the processing circuit adjusts the measurement results and at least one of the at least one reporting trigger condition in order to trigger the reporting of the measurement results sooner than if no adjustment were made. After the adjustment, the processing circuit determines, based on the at least one reporting trigger condition and the measurement results, whether at least one reporting trigger condition is satisfied in order to report the measurement results. If the reporting of measurement results is triggered, the transmitter of the UE transmits a measurement report including the measurement results.

[0007] It should be noted that general or specific embodiments can be implemented as systems, methods, integrated circuits, computer programs, storage media, or any selective combination thereof.

[0008] Further benefits and advantages of the disclosed embodiments and various embodiments will become apparent from this specification and the drawings. These benefits and / or advantages can be obtained individually by the various embodiments and features of this specification and the drawings. However, it is not necessary to provide all of these features in order to obtain one or more of such benefits and / or advantages. [Brief explanation of the drawing]

[0009] In the following, exemplary embodiments will be described in more detail with reference to the accompanying drawings. [Figure 1] Diagram showing a representative architecture of the 3GPP NR system. [Figure 2] Diagram showing exemplary user and control plane architectures for LTE eNB, gNB, and UE. [Figure 3] Diagram showing an exemplary NG RAN architecture based on a transparent satellite. [Figure 4] Diagram showing an exemplary NG RAN architecture based on a regenerative satellite. [Figure 5] Diagram showing a simplified example configuration of UE and gNB. [Figure 6] A diagram showing the configuration of a UE according to an exemplary embodiment of an improved measurement and reporting procedure. [Figure 7] Flowchart of UE behavior according to an exemplary embodiment of improved measurement and reporting procedures [Figure 8] Flowchart of gNB behavior according to an exemplary embodiment of improved measurement and reporting procedures [Figure 9] Signaling diagram of messages between UE, serving gNB, and target gNB, following improved measurement and reporting procedures. [Figure 10] Message signaling diagram between UE, serving gNB, and target gNB following an improved conditional handover procedure. [Figure 11] Flowchart of UE behavior according to an exemplary embodiment of an improved conditional handover procedure. [Figure 12] Flowchart of gNB behavior according to an exemplary embodiment of an improved conditional handover procedure. [Figure 13] Diagram illustrating a 4-step random access procedure. [Figure 14] Diagram illustrating a 3-step random access procedure. [Figure 15]A diagram illustrating DRX operation of a mobile terminal according to a short DRX cycle and a long DRX cycle, particularly DRX opportunities and on-duration periods [Figure 16] A signaling diagram of messages exchanged between a UE, a serving gNB of the UE and a target gNB for an exemplary embodiment of an improved handover communication procedure [Figure 17] A flow diagram of the behavior of a UE according to an exemplary embodiment of an improved handover communication procedure [Figure 18] A flow diagram of the behavior of a serving gNB according to an embodiment of an improved handover communication procedure [Figure 19] A flow diagram of the behavior of a serving gNB according to different embodiments of an improved handover communication procedure [Figure 20] A flow diagram of the behavior of a target gNB according to an embodiment of an improved handover communication procedure [Figure 21] A flow diagram of the behavior of a target gNB according to different embodiments of an improved handover communication procedure [Figure 22] A flow diagram of the behavior of a UE according to an exemplary embodiment of an improved HARQ operation procedure during handover DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0010] (5G NR System Architecture and Protocol Stack) 3GPP is working on the next release of fifth-generation cellular technology, simply referred to as 5G, which includes the development of a new radio access technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, which enables progress to trials compliant with the 5G NR standard and commercial deployment of smartphones.

[0011] In particular, the overall system architecture envisions an NG-RAN (Next Generation Radio Access Network) including gNBs, which provide NG-Radio Access User Plane (SDAP / PDCP / RLC / MAC / PHY) and Control Plane (RRC) protocol terminations to the UE. The gNBs are interconnected with each other by Xn interfaces. The gNBs are also connected to the NGC (Next Generation Core) by Next Generation (NG) interfaces, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity performing the AMF) by NG-C interfaces, and to the UPF (User Plane Function) (e.g., a specific core entity performing the UPF) by NG-U interfaces. The NG-RAN architecture is shown in Figure 1 (see, for example, 3GPP TS38.300 v15.4.0, Section 4).

[0012] A variety of different deployment scenarios may be supported (see, for example, 3GPP TR38.801 v14.0.0). For example, a decentralized deployment scenario is presented there (see, for example, Section 5.2 of TR38.801; a decentralized deployment is shown in Section 5.4), where base stations supporting 5G NR can be deployed. Figure 2 shows an exemplary decentralized deployment scenario (see, for example, Figure 5.2.-1 of TR38.801), additionally showing a user equipment (UE) connected to both a gNB and an LTE eNB, and an LTE eNB. A new eNB for NR 5G is sometimes exemplaryly referred to as a gNB. An LTE eNB is an evolution of the eNB that supports connectivity to the EPC (Advanced Packet Core) and NGC (Next Generation Core).

[0013] A user plane protocol stack for NR (see, for example, 3GPP TS38.300 v15.4.0, Section 4.4.1) includes PDCP (Packet Data Convergence Protocol, see Section 6.4 of TS38.300), RLC (Radio Link Control, see Section 6.3 of TS38.300) and MAC (Medium Access Control, see Section 6.2 of TS38.300) sublayers, which are terminated at the gNB on the network side. Furthermore, a new Access Stratum (AS) sublayer (SDAP (Service Data Adaptation Protocol)) is introduced above PDCP (see, for example, Section 6.5 of 3GPP TS38.300 Version 15.4.0). A control plane protocol stack is also defined for NR (see, for example, TS38.300, Section 4.4.2). An overview of Layer 2 functions is provided in Section 6 of TS38.300. The functions of the PDCP, RLC and MAC sublayers are listed in Sections 6.4, 6.3 and 6.2 of TS38.300, respectively. The functions of the RRC layer are listed in Section 7 of TS38.300.

[0014] For example, the Medium Access Control (MAC) layer handles logical channel multiplexing, and scheduling and scheduling-related functions including processing for various numerologies.

[0015] For the physical layer, the MAC layer uses services in the form of transport channels. A transport channel may be defined by how information is transmitted over the radio interface and the characteristics with which information is transmitted. A Random Access Channel (RACH), which does not carry transport blocks, is also defined as a transport channel processed by the MAC. One of the procedures supported by the MAC layer is the random access procedure.

[0016] The Physical Layer (PHY) is responsible for, for example, coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. The Physical Layer also handles the mapping of transport channels to physical channels. The Physical Layer serves the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a particular transport channel, and each transport channel is mapped to a corresponding physical channel. One physical channel is the PRACH (Physical Random Access Channel) used for random access.

[0017] Use cases / deployment scenarios for NR can include advanced mobile broadband (eMBB), ultra-high reliability, low latency communication (URLLC), and massive machine-type communication (mMTC), which have diverse requirements regarding data rate, latency, and coverage. For example, eMBB is expected to support peak data rates on the order of three times that of IMT-Advanced (20 Gbps downlink and 10 Gbps uplink) and user-perceived data rates. On the other hand, URLLC requires ultra-low latency (0.5 ms each for UL and DL regarding user plane latency) and high reliability (1-10 ms within 1 ms). -5 ) or even stricter requirements are imposed. Finally, mMTC preferably has a high connectivity density (1 km in urban environments). 2 This may require batteries capable of handling up to 1,000,000 devices, providing wide coverage in harsh environments, and offering extremely long battery life (15 years) for low-cost devices.

[0018] Therefore, OFDM neurology suitable for one use case (e.g., subcarrier interval, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) may not work well for another use case. For example, low-latency services may preferably require shorter symbol durations (and thus larger subcarrier intervals) and / or fewer symbols per scheduling interval (also known as TTI) than mMTC services. Furthermore, placement scenarios with large channel delay spread may preferably require longer CP durations than scenarios with short delay spread. To maintain similar CP overhead, the subcarrier interval should be optimized accordingly. NR can support multiple values ​​for the subcarrier interval. In response, subcarrier intervals of 15kHz, 30kHz, 60kHz, ... are currently being considered. The symbol duration Tu and subcarrier interval Δf are directly related through the equation Δf = 1 / Tu. Similar to LTE systems, the term "resource element" may be used to refer to the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0019] In the new 5G-NR wireless system, a resource grid consisting of subcarriers and OFDM symbols is defined for each neural network and carrier, for both the uplink and downlink. Each element in the resource grid is called a resource element and is identified based on its frequency index in the frequency domain and its symbol position in the time domain (see 3GPP TS38.211 v15.4.0).

[0020] (reference signal) Similar to LTE, several different types of reference signals (RS) are used in 5G NR (see 3GPP TS38.211 v15.4.0 Section 7.4.1). At least the following reference signals are available for 5G NR: • CSI-RS (Channel Status Reference Signal) usable for acquiring channel status information and beam management. • PDSCH DMRS (Demodulation Reference Signal) usable for PDSCH demodulation. • PDCCH DMRS (Demodulation Reference Signal) usable for PDCCH demodulation • PBCH DMRS (Demodulation Reference Signal) usable for PBCH demodulation • PTRS (Phase Tracking Reference Signal) usable for phase tracking of PDSCH • Tracking reference signal usable for time tracking

[0021] Furthermore, PBCH DMRS can be exemplary considered as part of the SSB reference signal (see 3GPP TS38.215 v15.3.0 Section 5.1.1 "SS reference signal received power (SS-RSRP)").

[0022] The main differences between the reference signal in 5G NR communication systems and the reference signal in LTE are that in 5G NR, there is no cell-specific reference signal, a new reference signal PTRS has been introduced for time / phase tracking, DMRS has been introduced for both downlink and uplink channels, and in NR, the reference signal is transmitted only when needed.

[0023] As a DL-only signal, the CSI-RS received by the UE is used to estimate the channel and report channel quality information to the gNB. During MIMO operation, the NR can use different antenna techniques based on the carrier frequency. At low frequencies, the system uses a relatively small number of active antennas for MU-MIMO and adds FDD operation. In this case, the UE can use the CSI-RS to calculate the CSI and report the CSI in the UL direction. The CSI-RS can be further characterized according to the following: This is used to obtain DL CSI. • Used for RSRP measurements during mobility and beam management. • Also used for frequency / time tracking, demodulation, and UL reciprocity-based precoding. • CSI-RS is configured specifically for the UE, but multiple users can share the same resources. The 5G NR standard enables a high level of flexibility in CSI-RS configuration, allowing resources to be configured for up to 32 ports. • CSI-RS resources can start with any OFDM symbol in the slot and typically occupy 1 / 2 / 4 OFDM symbols depending on the configured number of ports. CSI-RS can be periodic, semi-persistent, or aperiodic (due to DCI triggers).

[0024] For time / frequency tracking, CSI-RS can be either periodic or aperiodic. It is transmitted in bursts of 2 or 4 symbols that spread across one or two slots.

[0025] (UE measurement in 5G NR) NR devices may be configured to perform multiple different measurements and, in some cases, subsequently report the corresponding results to the network.

[0026] In short, to provide a basic overview of the measurement, the UE (NR device) can perform measurements based on reference signals (CSI-RS, SS block, etc.) and obtain measurement results from them. The measurement results may be used internally by the UE, or they may be used by other entities such as base stations for mobility control after receiving some or all of the measurement results in the corresponding measurement report.

[0027] Exemplary detailed embodiments are presented below. The measurements may be performed by the UE for connected mode mobility and may be classified into at least three types of measurements, as follows: ·Intra-frequency NR measurement • Inter-frequency NR measurement • Inter-RAT measurement for E-UTRA

[0028] In general, measurements may be configured by defining, for example, one or more measurement targets. A measurement target defines, for example, the carrier frequency to be monitored. For each measurement target, one or more reporting settings can be defined, including reporting criteria such as event-triggered reporting, periodic reporting, and event-triggered periodic reporting (see 3GPP TS38.300 v15.3.1 Section 9.1).

[0029] Reporting settings represent quantities or sets of quantities, such as various combinations of Channel Quality Indicators (CQI), Rank Indicators (RI), and Precoder Matrix Indicators (PMI), collectively referred to as Channel Status Information (CSI). Furthermore, reporting settings can represent reports of received signal strength, more formally referred to as Reference Signal Received Power (RSRP). Historically, RSRP has been an important quantity to measure and report as part of Higher Layer Radio Resource Management (RRM), and it remains an important quantity in 5G NR. NR supports Layer 1 reporting of RSRP, for example, as part of its support for beam management, thereby deriving beam quality. What is reported may be more specifically referred to as L1-RSRP, reflecting that the report does not include the longer-term ("Layer 3") filtering applied to higher-layer RSRP reporting. L3 filtering at the RRC level allows for the deriving of cell quality from multiple beams and thus mitigates abrupt changes by considering both the current input from the L1 filter and the previous output from the L3 filter.

[0030] A set of downlink resources on which measurements need to be performed is also defined. Therefore, for example, L1-RSRP for beam management can be based on measurements on either a set of SS (Synchronization Signal) blocks or a set of CSI-RS.

[0031] Furthermore, there are situations where a device performs measurements without corresponding reporting to the network. One exemplary such situation is when a UE performs measurements for receiver-side downlink beamforming. The UE uses the measurement results internally to select the appropriate receiver beam. The network can configure the UE accordingly, for example, by specifying the reference signal to measure but indicating that reporting is not required.

[0032] The UE can measure multiple beams (at least one) of a cell, and the measurement results (e.g., power values) are averaged to derive cell quality. In doing so, the UE may be configured to consider a subset of the detected beams. Filtering is performed at two different levels: first at the physical layer (layer 1) to derive beam quality, and then at the RRC layer (layer 3) to derive cell quality from multiple beams. Cell quality from beam measurements is derived similarly for serving and non-serving cells.

[0033] The measurement report is characterized exemplarily by one or more of the following: - The measurement report includes measurement identification information for the relevant measurement settings that triggered the report. - The number of cell and beam measurements to be included in the measurement report is determined by the network. - The number of non-serving cells reported can be limited through network settings. -Cells belonging to a network-defined blacklist are not used in event evaluation and reporting. Conversely, if a network-defined whitelist exists, only cells belonging to the whitelist are used in event evaluation and reporting. - The beam measurements included in the measurement report are determined by the network (beam identifier only, measurement results and beam identifier, or no beam report).

[0034] Adjacent (cell) measurements within the same frequency and adjacent (cell) measurements across different frequencies are defined exemplified as follows: -SSB-based in-frequency measurement: A measurement is defined as an SSB-based in-frequency measurement when the center frequency of the SSB of a serving cell is the same as the center frequency of the SSB of an adjacent cell, and the subcarrier spacing between these two SSBs is also the same. -SSB-based inter-frequency measurement: If the center frequency of the SSB of a serving cell is different from the center frequency of the SSB of an adjacent cell, or if the subcarrier spacing of these two SSBs is different, the measurement is defined as an SSB-based inter-frequency measurement. Note: For SSB-based measurements, one measurement corresponds to one SSB, and the UE considers different SSBs to be different cells. -CSI-RS based in-frequency measurement: A measurement is defined as a CSI-RS based in-frequency measurement if the bandwidth of the CSI-RS resource in the adjacent cell configured for the measurement is within the bandwidth of the CSI-RS resource in the serving cell configured for the measurement, and the subcarrier spacing between these two CSI-RS resources is the same. -CSI-RS-based inter-frequency measurement: A measurement is defined as a CSI-RS-based inter-frequency measurement if the bandwidth of the CSI-RS resource in the adjacent cell configured for the measurement is not within the bandwidth of the CSI-RS resource in the serving cell configured for the measurement, or if the subcarrier spacing of these two CSI-RS resources is different.

[0035] Whether a measurement is non-gap-assisted or gap-assisted depends on the capabilities of the UE, the UE's active BWP, and the current operating frequency. In a non-gap-assisted scenario, the UE can perform such a measurement without a measurement gap. In a gap-assisted scenario, it cannot be assumed that the UE can perform such a measurement without a measurement gap.

[0036] Measurement reporting is defined in Section 5.5.3 of 3GPP TS38.331 v15.3.0. The network can be configured to derive RSRP, RSRQ, and SINR measurement results for each cell. Measurement reporting triggers, including different trigger events (see summary below), are defined in Section 5.5.4 of 3GPP TS38.331 v15.4.0. Further details regarding measurement reporting are provided in Section 5.5.5 of 3GPP TS38.331 v15.4.0.

[0037] Different events A1-A6, B1, and B2 are defined, each containing a Leaving condition and an Entering condition, and associated with a time-to-trigger condition. This allows the UE to perform measurements and report results according to the defined criteria for the events. An overview is provided below. • Event A1 (Serving cell performs better than the threshold) ·Inequality A1-1 (Entering condition): Ms - Hys > Thresh ·Inequality A1-2 (Leaving condition): Ms + Hys < Thresh • Event A2 (Serving cell performance falls below threshold) ·Inequality A2-1 (Entering condition): Ms + Hys < Thresh ·Inequality A2-2 (Leaving condition): Ms - Hys > Thresh • Event A3 (Adjacent cells have a better offset than SpCell) ·Inequality A3-1 (Entering condition): Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off • Inequality A3-2 (Leaving condition): Mn + Ofn + Ocn + Hys < Mp + Ofp + Ocp + Off • Event A4 (Adjacent cells are better than the threshold) • Inequality A4-1 (Entering condition): Mn + Ofn + Ocn - Hys > Thresh ·Inequality A4-2 (Leaving condition): Mn + Ofn + Ocn + Hys <Thresh • Event A5 (SpCell worsens below threshold 1, while adjacent cells / SCells improve to threshold 2) ·Inequality A5-1 (Entering condition 1): Mp + Hys < Thresh1 ·Inequality A5-2 (Entering condition 2): Mn + Ofn + Ocn - Hys > Thresh2 ·Inequality A5-3 (Leaving condition 1): Mp - Hys > Thresh1 ·Inequality A5-4 (Leaving condition 2): Mn + Ofn + Ocn + Hys < Thresh2 • Event A6 (The adjacent cell has a better offset than SCell) ·Inequality A6-1 (Entering condition): Mn + Ocn - Hys > Ms + Ocs + Off • Inequality A6-2 (Leaving condition): Mn + Ocn + Hys < Ms + Ocs + Off • Event B1 (Adjacent cells between different RATs are better than the threshold) • Inequality B1-1 (Entering condition): Mn + Ofn + Ocn - Hys > Thresh ·Inequality B1-2 (Leaving condition): Mn + Ofn + Ocn + Hys < Thresh • Event B2 (PCell worsens below threshold 1, and inter-RAT adjacent cells improve beyond threshold 2) ·Inequality B2-1 (Entering condition 1): Mp + Hys < Thresh1 ·Inequality B2-2 (Entering condition 2): Mn + Ofn + Ocn - Hys > Thresh2 ·Inequality B2-3 (Leaving condition 1): Mp - Hys > Thresh1 ·Inequality B2-4 (Leaving condition 2): Mn + Ofn + Ocn + Hys < Thresh2

[0038] The parameters shown above are generally as follows: • Ms is the measurement result of the serving cell, without considering any offsets. • Mn is the measurement result for adjacent cells, without considering any offsets. Ofn is the measurement-specific offset of the reference signal of the adjacent cell (i.e., offsetMO as defined in measObjectNR corresponding to the adjacent cell). Ocn is the cell-specific offset of the adjacent cell (i.e., the cellIndividualOffset defined in measObjectNR corresponding to the frequency of the adjacent cell), and is set to zero if it is not set for the adjacent cell. • Mp is the SpCell measurement result, without considering any offsets. Ofp is the measurement-specific offset of the SpCell (i.e., offsetMO defined in the measObjectNR corresponding to the SpCell). Ocp is the cell-specific offset of the SpCell (i.e., the cellIndividualOffset defined in the measObjectNR corresponding to the SpCell), and is set to zero if it is not set for the SpCell. • Off is the offset parameter for this event (i.e., a3-Offset as defined in reportConfigNR for this event). • Hys is the hysteresis parameter for this event (i.e., the hysteresis defined in reportConfigNR for this event). • Thresh is the threshold parameter for this event (i.e., a1-Threshold as defined in reportConfigNR for this event). Thresh1 is the threshold parameter for this event (i.e., a5-Threshold1 defined in reportConfigNR for this event). Thresh2 is the threshold parameter for this event (i.e., a5-Threshold2 defined in reportConfigNR for this event). Mn, Mp, and Ms are expressed in dBm for RSRP and in dB for RSRQ and RS-SINR. Ofn, Ocn, Ofp, Ocp, Hys, and Off are expressed in dB.

[0039] At least the following mechanism is based on the measurement results obtained by UE. • Handover decision by gNB based on measurement results (received via measurement report). • Trigger for measurement report • Wireless link failure indicator

[0040] (Non-terrestrial network (NTN)) Satellites will continue to be the most effective means of reaching areas beyond ground coverage, and also reaching passengers on trains, aircraft, and ships. Therefore, including satellites as an integral part of the 5G ecosystem adds resilience. The satellite industry has participated in various committees, including those in 3GPP, EC, and ITU-T, to ensure that satellite systems are integrated as an essential part of the 5G ecosystem. The goals are: 1) to support highly available and reliable connectivity using satellites for use cases such as ubiquitous coverage, disaster relief, public safety requirements, emergency response, remote sensor connectivity, and broadcasting services; 2) to support air interfaces with unidirectional latency of up to 275 milliseconds when satellite connectivity is involved; and 3) to support seamless mobility between terrestrial networks and satellite-based networks with widely varying latency. The role and benefits of satellites in 5G are discussed in 3GPP Release 14, which leads to specific requirements for supporting satellite access.

[0041] Figure 3 shows an exemplary NG RAN architecture based on a transparent satellite. According to one exemplary embodiment (see Section 5.1 of TR38.821 v0.3.0), the satellite payload implements frequency conversion and radio frequency amplifiers in both uplink and downlink directions. This corresponds to an analog RF repeater. Thus, the satellite relays an NR-Uu radio interface from the feeder link (between the NTN gateway and the satellite) to the service link (between the satellite and the UE), and vice versa. The satellite radio interface (SRI) on the feeder link is NR-Uu. In other words, the satellite does not terminate the NR-Uu. Figure 4 shows an exemplary NG RAN architecture based on a regenerative satellite. According to one exemplary embodiment (see Section 5.2 of TR38.321 v0.3.0), the NG-RAN logic architecture described in TS38.401 is used as a baseline for the NTN scenario. The satellite payload implements the regeneration of signals received from Earth. The NR-Uu radio interface is on the service link between the UE and the satellite. The satellite radio interface (SRI) is on the feeder link between the NTN gateway and the satellite. The SRI (satellite radio interface) is the transport link between the NTN GW and the satellite.

[0042] Satellite payloads also provide inter-satellite links (ISLs) between satellites. An ISL (inter-satellite link) is a transport link between satellites.

[0043] Discussions are underway to address mobility for NTN. While satellite beams, satellites, or satellite cells do not need to be visible from an UE perspective within NTN, it is assumed that this type of network (e.g., NTN versus ground systems) does not need to be excluded from distinction at the PLMN (public land mobile network) level. Furthermore, it has been agreed that the Rel-15 design / definition will be used as a baseline for NTN, which means that the NR RRM measurement model used in Rel-15 will also be a baseline for the NTN RRM measurement model.

[0044] The inventors have recognized that in the case of non-terrestrial communications, the round-trip delay (RTD) can be much larger than in the case of terrestrial communications. For example, the maximum RTD at NTN is 541.1 ms for GEO (geostationary earth orbiting, e.g., altitude 35786 km) and 25.76 / 41.76 ms for LEO (low earth orbiting, e.g., altitude 600 / 1200 km). In terrestrial communications, the RTD can be as low as, for example, 5 ms.

[0045] Long RTDs can lead to a high handover failure rate because the network makes handover decisions based on measurements that may already be outdated and therefore inaccurate. For example, handover failures may include cases where the handover is too slow (other cases, such as handing over to the wrong cell). Furthermore, long RTDs in message exchange can also lead to longer NTN handover times, potentially resulting in longer service interruptions for UEs during handovers from one NTN network to another.

[0046] Therefore, the inventors identified the possibility of improving the measurement reporting and / or handover procedure to facilitate avoiding one or more of the aforementioned drawbacks. The improved measurement reporting and handover procedure may be applied to scenarios such as NTN scenarios where high latency exists. However, NTN scenarios are not the only scenarios in which the improved procedure can be implemented; other communication scenarios with high RTD and / or rapid channel variation environments, such as NR unlicensed scenarios where channel quality changes rapidly, can also benefit from the improved procedure.

[0047] In the following, UEs, base stations, and procedures that meet these needs are described with respect to new radio access technologies envisioned for 5G mobile communication systems, although these may also be used in LTE mobile communication systems. Various embodiments and modifications are also described. The following disclosures are facilitated by and may be based, for example, on the above descriptions and findings, at least in part therein.

[0048] In general, it should be noted that many assumptions are made herein so that the principles underlying this disclosure can be explained clearly and understandably. However, these assumptions should be understood as merely examples made herein for illustrative purposes and not to limit the scope of this disclosure. Those skilled in the art will recognize that the principles of the following disclosures, as set forth in the claims, may also be applied to different scenarios not expressly described herein, in ways not expressly described herein.

[0049] Furthermore, some of the terms used below, such as procedures, entities, and layers, are closely related to the terms used in the context of new radio access technologies for the next 3GPP 5G communication systems, even though the specific terminology used in the context of new radio access technologies for the next 3GPP 5G communication systems may not yet be fully determined or may ultimately change. Therefore, the terminology may change in the future without affecting the functionality of the embodiments. As a result, those skilled in the art will recognize that embodiments and their scope of protection should not be limited to the specific terms used exemplary herein due to the lack of newer or ultimately agreed-upon terminology, but should be understood more broadly with respect to the functions and ideas that form the basis of the functionality and principles of this disclosure.

[0050] For example, a mobile station or mobile node or user terminal or user equipment (UE) is a physical entity (physical node) in a communication network. A single node may have multiple functional entities. A functional entity refers to a software or hardware module that performs a predetermined set of functions and / or provides a predetermined set of functions to the same node, another node, or other functional entities in the network. A node may have one or more interfaces that connect it to communication equipment or media with which it can communicate. Similarly, a network entity may have logical interfaces that connect functional entities to communication equipment or media with which it can communicate to other functional entities or corresponding nodes.

[0051] Here, the term "base station" or "radio base station" refers to a physical entity within a communication network. Similar to a mobile station, a base station can have multiple functional entities. A functional entity refers to a software or hardware module that performs a predetermined set of functions and / or provides a predetermined set of functions to the same node, another node, or other functional entities in the network. A physical entity performs several control tasks for communication devices, including one or more of scheduling and configuration. It should be noted that the functions of a base station and a communication device may be integrated within a single device. For example, a mobile terminal may also implement base station functions for other terminals. The term used in LTE is eNB (or eNodeB), while the term currently used in 5G NR is gNB.

[0052] Figure 5 shows a general, simplified, illustrative block diagram of user equipment (also referred to as communication devices) and scheduling devices (which are illustratively assumed to be located within a base station (e.g., an eLTE eNB (or ng-eNB) or gNB in ​​5G NR)). The UE and eNB / gNB communicate with each other via (radio) physical channels using their respective transceivers.

[0053] A communication device may comprise a transceiver and a processing circuit. The transceiver may include a receiver and a transmitter, and / or function as both. The processing circuit may be one or more processors or one or more hardware components such as any LSI. An input / output point (or input / output node) exists between the transceiver and the processing circuit, and the processing circuit can control the transceiver via the input / output point (or input / output node) during operation, i.e., it can control the receiver and / or transmitter and exchange received / transmitted data. The transceiver may include an RF (radio frequency) front end, including one or more antennas, amplifiers, RF modulators / demodulators, etc., as both transmitter and receiver. The processing circuit can perform control tasks such as controlling the transceiver to transmit user data and control data provided by the processing circuit, and / or to receive user data and control data that is further processed by the processing circuit. The processing circuit may also be responsible for performing other processes such as judgment, discrimination, determination, calculation, measurement, etc. The transmitter may be responsible for performing the transmission process and other processes related to the transmission process. The receiver may be responsible for performing the receiving process and other processes related to the receiving process, such as monitoring the channel.

[0054] The improved measurement and reporting procedures are described in relation to Figures 6 to 9. Furthermore, the improved conditional handover procedure is described in relation to Figures 10 to 12. Furthermore, the improved handover communication procedure is described in relation to Figures 16 to 21. Finally, the improved HARQ procedure is described in relation to Figure 22.

[0055] The solutions provided below are primarily described in relation to the 5G NR NTN scenario. As mentioned above, the NTN (non-terrestrial network) environment involves the UE communicating with the gNB via satellite, where the gNB may be located, for example, on a satellite (see Figure 4) or an NTN gateway (see Figure 3), or in other locations such as outside the NTN gateway. Nevertheless, the scope of the embodiments should not be limited solely to such NTN scenarios, but also encompass other scenarios such as NR unlicensed.

[0056] UE mobility in such scenarios includes the UE moving between coverages of various satellites (e.g., a UE in flight). UE mobility is typically controlled by a serving gNB, but supported by the UE providing the serving gNB with results of power-related measurements. The serving gNB then determines whether it is necessary or advantageous to hand over the UE to another radio cell, and if so, can initiate the appropriate handover procedure.

[0057] More specifically, it is assumed that the UE will perform power-related measurements periodically, for example. Power-related measurements may include RSRP (received reference signal power), RSRQ (received reference signal quality), RSSI (received signal strength), SINR (signal-to-interference noise ratio), or other appropriate types of measurements that the UE may use in the above regard. Typically, power-related measurements may be performed on a reference signal such as the CSI-RS or SSB mentioned above.

[0058] Whether and how a UE performs power-related measurements may be configured, at least in part, by the UE's serving gNB. This may further involve configurations regarding whether, how, and when the UE reports the measurement results to its serving base station (for example, to assist in handover decisions).

[0059] An exemplary embodiment of how measurement and reporting functions in a UE are configured is described above (see the description of UE measurement in 5G), and includes, for example, the definition of one or more measurement targets, reporting settings, and reporting criteria. For example, event-triggered reporting of measurement results may be defined to include reporting trigger events similar to or the same as those described above (e.g., A1-A6, B1, B2). Trigger events, and in particular conditions for trigger events, may be handover-related, for example, in that the reporting trigger condition is met when the serving gNB can determine that the UE is handing over from its current serving radio cell to another radio cell (e.g., Event A2: "Serving cell is worse than threshold", Event A3: "Adjacent cell has a better offset than SpCell", Event A4: "Adjacent cell is better than threshold").

[0060] Furthermore, it is assumed that the UE can perform measurements on various radio carriers (or access links or frequency bands) having the same or different radio frequencies. For example, UE measurements are performed on the UE's serving radio carrier (of the UE's serving radio cell, controlled by the serving gNB) and on one or more adjacent radio carriers (of other radio cells, controlled by adjacent gNBs).

[0061] The measurement and reporting settings are intended for use by UEs for mobility between non-terrestrial networks and mobility between terrestrial networks. According to this solution, the measurement and reporting settings are differentiated depending on whether the mobility is between terrestrial networks or between non-terrestrial networks (explained in more detail below).

[0062] In the following, we illustratively assume that a UE is connected to its serving gNB via a satellite and performs measurements on its radio carrier to the satellite and on one or more radio carriers to other neighboring satellites. These UE measurement results may then be used by the serving gNB to control the UE's mobility. Controlling the UE's mobility includes deciding whether to hand over the UE from the serving satellite to another satellite. The handover procedure initiated by the serving gNB may be, for example, a handover procedure already known from the prior art, or it may be an improved conditional handover procedure in which the final decision on whether or not to hand over is left to the UE. The improved conditional handover procedure will be described in more detail later (see Figures 10-12).

[0063] Figure 6 shows a simplified exemplary UE configuration according to this solution for improved measurement and reporting procedures, which may be implemented based on the general UE configuration described in relation to Figure 5 above. The various components of the UE shown in this figure may be interconnected with each other, for example, using corresponding input / output nodes (not shown) to exchange control data, user data, and other signals. Although not illustrated for illustrative purposes, the UE may include further components.

[0064] As is evident from this figure, the UE may include a measurement circuit, a measurement result generation circuit, a report adjustment circuit, and a measurement report transmission unit, as described below.

[0065] In this case, as will become apparent from the following disclosure, the processing circuit may be exemplary configured to perform at least one or more of the following: performing a measurement; generating a measurement result from the performed measurement; determining whether to adjust the measurement result and at least one of the reporting trigger conditions; adjusting the measurement result and at least one of the reporting trigger conditions; and determining whether the reporting trigger condition is met.

[0066] The transmitter may be configured to at least partially transmit a measurement report, including the measurement results.

[0067] Figure 7 is a sequence diagram of exemplary UE behavior following this improved measurement and reporting procedure. As is evident from this figure, the UE performs power-related measurements on at least one radio carrier and generates measurement results from the power-related measurements performed. Power-related measurements are performed on one or more of the following: the UE's serving radio carrier (in this particular exemplary scenario, the radio carrier connecting the UE to a satellite), the radio carrier connecting the UE to an adjacent satellite, and the radio carrier connecting the UE to a terrestrial network (such as a 5G or LTE antenna).

[0068] As described above, the UE reports the measurement results to its serving base station, for example, depending on whether certain reporting trigger conditions are met. If one or more of the reporting trigger conditions are met, the UE generates a measurement report containing the obtained measurement results and sends the measurement report to the UE's serving gNB.

[0069] According to this improved measurement and reporting procedure, before determining whether the reporting trigger conditions are met, the UE first decides whether to adjust the measurement reporting procedure so as to trigger the transmission of the measurement report earlier than if there were no adjustment. This additional step of adjusting the measurement reporting procedure is done to take into account that inter-satellite mobility differs from, for example, inter-terrestrial network mobility due to the long round-trip delays associated with communication between the UE and the satellite. As previously stated, the inventors have identified drawbacks of the measurement procedure, and therefore of the handover procedure, related to long round-trip delays. Triggering the measurement report earlier can sometimes avoid or mitigate handover failure events that occur too late. Accordingly, the UE may decide to further adjust the measurement reporting procedure if the radio carrier to be measured and the measurement results to be reported involves long round-trip delays, such as those exceeding 10 ms, as in the case of a non-terrestrial network. Alternatively, the UE decides whether to adjust the measurement reporting procedure according to instructions given by the serving gNB. One option is that the instructions are given to the UE by the serving gNB through the measurement object (MO) setting for the UE measurement.

[0070] Continuing with the sequence of UE behavior shown in Figure 7, we assume that additional adjustments are made by the UE. As previously mentioned, the adjustments are made so that the measurement report is triggered earlier than the corresponding measurement report that would be triggered without the adjustments. In other words, the report trigger condition is met sooner, and as a result, the measurement report is sent to the serving base station sooner.

[0071] This acceleration of measurement reporting can be achieved in several ways, for example, by adjusting the measurement results and / or reporting trigger conditions, as will be explained and illustrated in more detail below.

[0072] After adjustment, the UE monitors whether the measurement results meet one of the reporting trigger conditions (the measurement results and / or reporting trigger conditions are adjusted). If a measurement report is triggered, the UE then proceeds to generate a measurement report containing some or all of the generated measurement results and send it to the serving gNB. The measurement report may include, for example, unadjusted measurement results, thereby providing the gNB with accurate measurement results. Alternatively, the UE may include adjusted measurement results in the measurement report sent to the serving gNB, either in place of or in addition to the unadjusted measurement results. This allows the serving gNB to derive previous measurement results that were not sent to the serving gNB, and as a result, the serving gNB has further information to decide whether or not to initiate the handover procedure.

[0073] Figure 8 shows exemplary gNB behavior related to the improved measurement and reporting procedure described above. In this exemplary gNB behavior, the gNB is responsible not only for setting the measurement and reporting settings for the UE, but also for determining whether and how the UE needs to adjust the measurement reporting trigger in order to achieve faster reporting of measurement results, as already mentioned above in relation to Figure 7.

[0074] The gNB receives a measurement report from the UE, including the measurement results, and based on this, can decide whether or not to initiate a handover procedure for the UE to hand over the UE to another radio cell (e.g., another satellite). If the gNB decides to initiate a handover procedure, it sends a corresponding handover command to the UE.

[0075] The additional adjustments to the measurement report have the advantage of accelerating the trigger, resulting in the measurement report being sent earlier by the serving gNB, which in turn allows the serving gNB to decide on a handover sooner. Therefore, the procedure described above has the advantage of avoiding or mitigating handover failure events that occur too late. Furthermore, the adjustment solution is simple because it relies on other information such as the UE position or satellite position (satellite ephemeris).

[0076] An exemplary, simplified sequence of the improved measurement and reporting procedure is shown in Figure 9. As illustrated, the UE's serving gNB provides the measurement setup to the UE, and the UE performs the measurement on its serving radio carrier and other neighboring radio carriers (in Figure 9, only one neighboring gNB is shown for illustrative purposes). Additional adjustments to the measurement reporting procedure are illustrated to be performed after the power measurement, but may be performed in parallel or before. The sequence in Figure 9 concludes with the transmission of the measurement report to the serving gNB.

[0077] The following describes several different exemplary embodiments of how to adjust measurement reports to trigger earlier than without adjustment. The adjustment may be applied to the measurement result itself, and then the adjusted measurement result may be used to determine whether the report trigger condition is met, or the adjustment may be applied to the report trigger condition. Depending on the measurement result and / or report trigger condition, the adjustment may differ to achieve earlier triggering.

[0078] According to one exemplary embodiment, one or more appropriate power offsets may be introduced to ensure that the reporting trigger condition is met more quickly. The power offset may be applied, for example, to the measurement result itself, or it may be applied to the reporting trigger condition. In this case as well, the amount of the offset and whether the offset is negative or positive may depend on the measurement result and / or the reporting trigger condition.

[0079] For illustrative purposes, we will exemplify the assumption that some or all of the reporting trigger conditions already defined for 5G (see the explanation above) are used by the UE to determine whether or not to send measurement results to the UE's serving gNB.

[0080] The Entering condition for event A1 (serving cell improves above threshold) to initiate sending measurement results to the serving gNB is: Ms - Hys > Thresh That is the case.

[0081] If adjustments are to be applied to this reporting trigger condition, this may be achieved by incorporating an offset (exemplarily referred to as the NTN-offset) as follows: Ms + NTN-offset - Hys > Thresh

[0082] As is clear from the above, introducing a positive offset allows the threshold ("Thresh") to be reached more quickly.

[0083] The Entering condition for event A2 (serving cell worsens below the threshold) is: Ms + Hys < Thresh That is the case.

[0084] If you want to apply adjustments to this reporting trigger condition, this can be achieved by incorporating an offset as follows: Ms - NTN-offset + Hys > Thresh

[0085] As is evident from the adjusted trigger conditions above, introducing a negative offset allows the threshold to be reached (<) sooner than if it were not present.

[0086] The Entering condition for event A3 (where the adjacent cell has a better offset than SpCell) is: Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off That is the case.

[0087] If adjustments are to be applied to this reporting trigger condition, this may be achieved by incorporating one or two offsets as follows: Mn + NTN-neighbour-offset + Ofn + Ocn - Hys > Mp - NTN-serving-offset + Ofp + Ocp + Off

[0088] In one particular embodiment, an offset (here, an exemplary NTN-serving-offset) is defined for the trigger condition portion related to the serving cell, and another offset (here, an exemplary NTN-neighbour-offset) is defined for the trigger condition portion related to the neighboring cell. As a result, when determining the same trigger condition for the serving cell and other neighboring cells, the same NTN-serving-offset and the same NTN-neighbour-offset can be reused. This simplifies the adjustment because, for each reporting trigger condition, at most two different offsets are defined: one offset related to the serving cell and one offset related to the neighboring cell.

[0089] The Entering condition for event A4 (adjacent cells perform better than the threshold) is: Mn + Ofn + Ocn - Hys > Thresh That is the case.

[0090] If you want to apply adjustments to this reporting trigger condition, this can be achieved by incorporating an offset as follows: Mn + NTN-offset + Ofn + Ocn - Hys > Thresh

[0091] As is clear from the above, the threshold is reached more quickly by forcing an increase in the measurement result on the left side for adjacent cells.

[0092] In summary, adjusting the measurement reporting trigger depends on specific trigger conditions and follows the premise that the conditions will be reached sooner.

[0093] Specific values ​​may be set by a network (e.g., gNB) along with other settings for the UE measurement (e.g., measurement target, reporting criteria, etc.).

[0094] If the NTN-specific offset is set to 0, the reporting trigger condition is equally applicable to other scenarios.

[0095] Different offset values ​​may be determined by the gNB in ​​different ways to balance the effect of the offset on each trigger condition, for example, so that other handover failures (e.g., premature handovers) are avoided or minimized. According to one exemplary embodiment, the gNB determines the offset value in relation to the round-trip delay experienced by the UE with respect to the serving gNB.

[0096] Furthermore, if it is determined that too many handover failures are occurring or too many measurement reports are being triggered, for example, the gNB may also modify adjustments (e.g., offsets) during operation to adapt an improved measurement reporting procedure. For example, resetting or canceling measurement reporting adjustments may be done using messages from the RRC protocol (e.g., RRC reset messages).

[0097] According to another exemplary embodiment of how measurement report adjustments are performed, instead of using adjustments set by the network, the adjustments are determined by the UE itself. The offsets mentioned above (e.g., NTN-offset, NTN-serving-offset, NTN-neighbour-offset) are determined by the UE. For example, the offset is determined for each measurement result by determining, for example, the difference between the current measurement result and a previously determined measurement result (the difference is referred to as exemplary Δmeas). In other words, the change in the measurement result is doubled, and therefore leads to an earlier trigger for measurement reporting than if there were no offset.

[0098] For example, let's take the aforementioned 5G measurement events A1, A2, and A3 again as illustrations.

[0099] The Entering condition for event A1 (serving cell improves above threshold) to initiate sending measurement results to the serving gNB is: Ms - Hys > Thresh That is the case.

[0100] If adjustments are to be applied to this reporting trigger condition, this can be achieved by incorporating the measurement difference Δmeas as follows: Ms + Δmeas - Hys > Thresh

[0101] As is clear from the above, the threshold ("Thresh") is reached more quickly by amplifying the increase in the measurement result.

[0102] The Entering condition for event A2 (serving cell worsens below the threshold) is: Ms + Hys < Thresh That is the case.

[0103] If adjustments are to be applied to this reporting trigger condition, this can be achieved by incorporating the measurement difference Δmeas as follows: Ms + Δmeas + Hys < Thresh

[0104] As is evident from the adjusted trigger conditions above, the threshold is reached (<) faster than if it were not present by increasing the decrease in the measurement result.

[0105] The Entering condition for event A3 (where the adjacent cell has a better offset than SpCell) is: Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off That is the case.

[0106] If adjustments are to be applied to this reporting trigger condition, this can be achieved by incorporating the measurement difference Δmeas as follows: Mn + Δmeas_n + Ofn + Ocn - Hys > Mp - Δmeas_p + Ofp + Ocp + Off

[0107] As is clear from the above, the change (a decrease or increase in measured power) is artificially amplified by introducing an offset Δmeas to the measurement results of the serving cell and the adjacent cell, respectively. As a result, the trigger condition is met faster than if there were no offset.

[0108] Calculating the measurement difference as the offset, rather than following an offset value set by the network, avoids the need for the gNB to set an offset for the UE and continuously adjust it as needed to maintain good handover performance. Furthermore, the adjustment may be more accurate because it is based on previous measurements of the UE rather than an artificial value set by the serving gNB. On the other hand, the network has less control over how the measurement report is adjusted.

[0109] As described above, the gNB will ultimately decide to initiate the handover procedure with the UE after receiving the measurement report, which will include the measurement results. One option is that the handover procedure may be a standard handover procedure, such as one already defined in the 3GPP standard (see TS38.331 v15.4.0).

[0110] On the other hand, an improved conditional handover procedure that may be used instead by the gNB and UE is described below with reference to Figures 10-12. Conditional handover generally shifts the final decision on whether or not to perform a handover from the serving gNB to the UE. This is achieved, for example, by providing the UE with additional conditions (e.g., along with the handover command message) that the UE can use to decide whether and when to perform a directed handover. Conditional handover has the effect of reducing handover delays because the serving gNB can prepare the handover, and the UE can then perform the handover in time when needed. At the time of performing the handover, the need to resend further measurement reports to the serving gNB to trigger the handover procedure is avoided. However, handovers are prepared in potential target cells so that the target gNB needs to reserve resources for the UE (e.g., dedicated PRACH resources for random access, C-RNT) for extended periods, even if they are ultimately not used (e.g., when the UE does not perform a handover).

[0111] The improved conditional handover procedure, described in relation to Figures 10-12, attempts to mitigate these problems by providing the UE with one or more additional handover rejection conditions that the UE monitors, causing it to abort possible handovers early, for example, rather than waiting for a timeout. This will be explained in more detail below. Figure 10 shows an exemplary message exchange between the UE, the serving gNB, and the neighboring gNB as a possible handover target. Figure 11 is an exemplary sequence diagram of the UE behavior, while Figure 12 shows an exemplary sequence diagram of the gNB's behavior in the role of the UE's serving gNB.

[0112] As mentioned above, the handover decision is typically made by the serving gNB and assisted by the UE by providing measurement reports on the serving radio carrier and, if necessary, other neighboring radio carriers. Correspondingly, the first message shown in the message exchange diagram of Figure 10 is a measurement report sent by the UE to the UE's serving gNB. The measurement report may be generated using an improved measurement reporting procedure as described above with reference to Figures 6-9 (for example, the measurement report may be triggered earlier due to additional adjustments to the measurement reporting trigger). On the other hand, the measurement report may also be a "normal" measurement report that is triggered without the UE adjusting the trigger for the measurement reporting function.

[0113] Based on the received measurement report (and the measurement results contained in the measurement report), the serving gNB may determine that a handover to another radio cell (e.g., another satellite) may be beneficial to the UE, and therefore initiate the appropriate handover procedure with the target gNB (adjacent gNB) and the UE.

[0114] Here, we assume that the serving gNB decides to perform a conditional handover to the UE. The gNB's decision to select a conditional handover can be based on a variety of different criteria. For example, the serving gNB may decide on a conditional handover if it has configured the UE before performing the improved measurement and reporting procedure, as described above in relation to Figures 6-10. More specifically, the serving gNB may configure the UE in terms of how it performs power-related measurements in addition to reporting measurement results, which may include whether and how the UE adjusts measurement reporting triggers (e.g., NTN-related offset values). However, the early reporting of measurement results achieved by the improved measurement and reporting procedure described above could theoretically lead to an increase in cases where the handover is performed too early. This drawback can be mitigated by performing a conditional handover decision, because the UE can perform the directed handover to the target cell when the handover acceptance conditions are met and it is not too early.

[0115] Additionally or alternatively, the serving gNB may decide to perform a conditional handover instead of a normal handover based on the round-trip delay it receives when communicating with the UE. For example, if the round-trip delay exceeds a certain threshold (e.g., 10ms), it may be beneficial to leave the final handover decision to the UE to avoid incorrect handover decisions resulting from the long round-trip delay.

[0116] A further additional or alternative criterion for deciding whether to make a handover conditional is the handover failure rate. For example, suppose an unconditional handover procedure has been performed so far by the serving gNB with the UE in the serving gNB's radio cell. However, if the handover failure rate (e.g., the failure rate of premature handovers) is too high, the serving gNB may determine that it would be beneficial to condition the handover on conditions that are suitable for the UE to ultimately decide, and that this could reduce the handover failure rate.

[0117] Further additional or alternative criteria for determining whether a handover is conditional are based on the satellite and / or UE positions. For example, even if the serving gNB determines from the measurement report that a conditional handover is not necessary, the gNB may trigger a conditional handover if the satellite and / or UE positions indicate that the UE is located near the cell edge.

[0118] Referring again to Figure 10, suppose the serving gNB determines a conditional handover according to, for example, one or more of the criteria described above. The serving gNB prepares for the handover in the target cell (see the handover request and handover acknowledgment in Figure 10) and sends a handover command message to the UE. As illustrated exemplarily in Figure 10, the handover procedure may begin, for example, by requesting a handover and waiting for a handover acknowledgment from the neighboring cell, so as to ensure that the neighboring gNB has the capacity to accommodate the additional UE and that the neighboring gNB can reserve resources for the UE to be handed over. After receiving the handover acknowledgment from the neighboring gNB, the serving gNB proceeds with the handover procedure and sends the corresponding handover command message to the UE.

[0119] As is typical, a handover command message may include an ID and additional information to identify and connect to the target cell. Furthermore, a handover command message may include one or more handover acceptance and rejection conditions. Handover acceptance conditions are checked by the UE to determine whether and when to perform a handover. If the handover acceptance conditions are met, the UE performs the handover. On the other hand, handover rejection conditions are checked by the UE to determine whether to reject the handover instruction. If the handover rejection conditions are met, the UE may immediately reject the handover and provide corresponding information regarding the rejection to the UE's serving gNB (this information may be used by the serving gNB to instruct the target gNB to release resources previously reserved for the UE handover). Figure 10 shows both handover acceptance and handover rejection cases.

[0120] The handover acceptance and rejection conditions may be determined by the serving gNB depending on the specific handover scenario. According to one optional embodiment, the handover acceptance and rejection conditions may be related to each other, for example, being mutually exclusive, allowing the UE to clearly decide whether to accept or reject the handover. This is beneficial for enforcing an immediate decision regarding the handover and thus minimizing resource allocation time in the target cell. Furthermore, assuming that the UE and serving gNB interrupt communication during the handover, enforcing an immediate decision by the UE regarding the instructed handover can also facilitate minimizing communication interruption time, because the UE and serving gNB can immediately resume UL / DL communication. On the other hand, the handover acceptance and rejection conditions do not need to be perfectly complementary to each other. Therefore, for example, there may be measurement cases where neither the handover acceptance nor rejection conditions are met simultaneously. There is a gap between the acceptance and rejection conditions.

[0121] For example, a possible handover rejection condition is "if the serving cell is better than the target cell by more than x dB for at least y ms," where the parameter values ​​x and y may be appropriately set by the gNB (e.g., x may be 5 dB and y may be 50 ms). A handover acceptance condition may be, for example, "if the target cell is better than the serving cell by more than x dB for at least y ms," where the parameter values ​​x and y may be appropriately set by the gNB (e.g., x may be 8 dB and y may be 30 ms).

[0122] Information regarding the rejection of the handover may be sent to the UE's serving gNB in ​​several different ways, for example, depending on whether uplink data is still being transmitted.

[0123] According to one exemplary solution, if no UL traffic exists, handover denial information may be transmitted as part of an RRC message, such as an RRCReconfigurationComplete message or another, possibly new RRC (Radio Resource Control Protocol) message. Additionally or alternatively, handover denial information may be implicitly provided to the serving gNB in ​​response to a conditional handover command message, for example, by sending a measurement report to the serving gNB. The serving gNB can then implicitly derive that the UE has denied the handover.

[0124] Following other exemplary solutions, if UL traffic exists, handover denial information may be included in the MAC (Media Access Control) control element (CE) along with the UL traffic data.

[0125] In any case, information that the handover was rejected by the UE is provided to the serving gNB.

[0126] In one optional embodiment, when a handover is rejected, the UE may be configured not to send further measurement reports to the serving gNB for a certain period of time. This has the advantage that a further (conditional) handover is not triggered immediately after the handover is rejected. For example, the UE may use a prohibit timer that starts when a handover is rejected. The timer may be set by the network (e.g., by the serving gNB) when setting up the measurement and reporting functions in the UE.

[0127] In an optional further embodiment, for example, a mechanism is incorporated to extend resource allocation in a target radio cell to avoid the resource allocation in the target radio cell being canceled too early. More specifically, resource allocation in a target cell may be maintained solely by the target gNB for a certain period (e.g., controlled by an appropriate timer such as T304 in some 5G implementations) but may expire before the UE makes a decision on whether to accept or reject the handover. This problem can be exacerbated if handover acceptance and rejection conditions are defined in a way that involves long round-trip delays and prevents the UE from immediately deciding whether to accept or reject the handover.

[0128] In such a scenario, it is beneficial for the UE to instruct the serving gNB to extend resource allocation in the target cell when neither the handover acceptance conditions nor the handover rejection conditions are met. As shown in Figure 11, the UE may optionally check whether the corresponding resource allocation timer has already expired. If it has already expired, the handover to the target gNB is no longer possible as intended, and the UE connects to either the UE's old serving gNB or another gNB (this involves, for example, performing RRC connection re-establishment). The instruction may be sent in a manner similar to or in the same way as previously described regarding how rejection information is communicated to the serving gNB (see the corresponding description for further details). The serving gNB then, upon receiving such a resource allocation extension request, may contact the target gNB to extend the resource allocation. If the serving gNB does not receive such a resource allocation extension request, it may optionally assume that the handover is being performed as intended (see Figure 12).

[0129] Further solutions would improve the handover procedure by allowing the UE to continue communicating with its serving gNB while simultaneously performing the handover procedure with the target cell. In the conventional solution, UL / DL communication is interrupted when the UE initiates a random access procedure with the target cell as part of the handover execution. However, this leads to service interruption because UL / DL communication is interrupted until the UE connects to a new target cell (UL / DL communication continues with the target gNB) or until the UE reconnects with its serving gNB (if the handover is unsuccessful). While service interruption may not be a major issue for mobility between networks with low round-trip latency (such as terrestrial networks), it is problematic for mobility with high round-trip latency (e.g., for UEs moving between different NTN networks, such as satellites). In response, it is important to mitigate the service interruption caused by the UE ceasing UL / DL communication until the UE connects to its target gNB or, if the handover fails, until the UE reconnects with its serving gNB again.

[0130] This can be achieved by the UE continuing to communicate with the serving gNB even after participating in a (conditional) handover and after initiating a random access procedure with the target cell. More specifically, the UE receives a handover command and initiates a random access procedure to connect to the target gNB, but still continues DL / UL communication with the serving gNB. Correspondingly, this also applies to the serving gNB, which continues to send DL data and receive UL data as it did before deciding to hand over the UE. However, in this case, the UE needs to perform UL / DL communication in parallel with the random access procedure, and it is beneficial to coordinate the uplink and downlink transmissions to and from the serving gNB with the uplink and downlink transmissions for random access to and from the target gNB. This can be achieved by the following solution, which is explained with reference to Figures 16-21.

[0131] In short, the UE defines a DRX active period during which it can actively communicate, and further operates a DRX (intermittent reception) function (more details below) that provides the UE with power-saving opportunities during the so-called DRX off period. Following one exemplary solution, the UE continues to communicate with the serving base station during the DRX active period while using the DRX off period to perform random access procedures with the target cell. In this way, the UE can communicate with the serving base station and the target base station in parallel. Therefore, once the UE establishes a connection with the target gNB, it can interrupt communication with the serving base station. As a result, a make-before-break handover is achieved, minimizing service interruptions caused by the handover.

[0132] The following provides further details regarding the random access procedure and DRX functionality with reference to Figures 13-15, and different embodiments of the improved handover communication procedure are described in more detail with reference to Figures 16-21. The following describes one specific exemplary random access procedure that can be used in this solution. Similar to LTE, 5G NR provides a RACH (Random Access Channel) procedure (or simply a random access procedure) (see 3GPP TS38.321, v15.3.0 Section 5.1). For example, the RACH procedure may be used by a UE to access a cell discovered by the UE. The RACH procedure may also be used in other contexts within NR, such as: • In the case of a handover, when synchronization to the new cell should be established. • To re-establish uplink synchronization to the current cell in the event of loss of synchronization due to a prolonged period without uplink transmission from the device. - To request uplink scheduling when a dedicated scheduling request resource is not configured for the device.

[0133] The RACH procedure is described in more detail below with reference to Figures 13 and 14. A mobile terminal may be scheduled for uplink transmissions if its uplink transmissions are time-synchronized. The Random Access Channel (RACH) procedure serves as an interface between asynchronous mobile terminals (UEs) and orthogonal transmissions of uplink radio access. For example, random access is used to achieve uplink time synchronization for user equipment that has not yet achieved or has lost uplink synchronization. Once the user equipment achieves uplink synchronization, the base station can schedule uplink transmission resources for the user equipment. One scenario related to random access is when user equipment in the RRC_CONNECTED state, handing over from its current serving cell to a new target cell, executes the random access procedure to achieve uplink time synchronization in the target cell.

[0134] There can be two types of random access procedures that allow access to be either competition-based (i.e., implying an inherent risk of conflict) or non-competition-based (non-competition-based).

[0135] The conflict-based random access procedure is described in more detail below in relation to Figure 13. This procedure consists of four "steps". First, the user device sends a random access preamble (i.e., message 1 of the RACH procedure) on the physical random access channel (PRACH) to the base station. After the base station detects the RACH preamble, it sends a random access response (RAR) message (message 2 of the RACH procedure) on the PDSCH (physical downlink shared channel) addressed on the PDCCH, using the RA (random access)-RNTI which identifies the time-frequency and slot in which the preamble was detected. If multiple user devices send the same RACH preamble on the same PRACH resource (this is also called a collision), those multiple user devices receive the same random access response message. A RAR message can carry the detected RACH preamble, a timing alignment command (TA command) for synchronizing subsequent uplink transmissions based on the timing of the received preamble, an initial uplink resource allocation (grant) for the first scheduled transmission, and a T-CRNTI (Temporary Cell Radio Network Temporary Identifier). This T-CRNTI is used by the base station to address the mobile terminal where the RACH preamble was detected until the RACH procedure is complete, because the base station has not yet recognized the "actual" identification information of the mobile terminal at this point.

[0136] The user equipment monitors the PDCCH to receive Random Access Response messages within a given time window (e.g., referred to as the RAR reception window) that may be set by the base station. In response to the RAR message received from the base station, the user equipment sends its first scheduled uplink transmission on the radio resource allocated by the grant in the Random Access Response. This scheduled uplink transmission carries the actual Random Access Procedure message, such as an RRC connection request, an RRC restart request, or a buffer status report.

[0137] If a preamble collision occurs in the first message of the RACH procedure, that is, if multiple user devices transmit the same preamble on the same PRACH resource, the colliding user devices will receive the same T-CRNTI in the random access response and will collide on the same uplink resource when they transmit their scheduled transmissions in the third step of the RACH procedure. If the scheduled transmission from one user device is successfully decoded by the base station, the conflict remains unresolved for one or more other user devices. To resolve this type of conflict, the base station transmits a conflict resolution message (fourth message) addressed to a C-RNTI or Temporary C-RNTI. The procedure then ends.

[0138] Figure 14 shows a simplified, non-conflict random access procedure compared to a conflict-based random access procedure. In the first step, the base station provides the user equipment with a preamble for use in random access, ensuring there is no risk of collision, i.e., multiple user equipment does not transmit the same preamble. The user equipment then transmits the preamble signaled by the base station on the uplink with the PRACH resource. Since the case where multiple UEs transmit the same preamble is avoided in non-conflict random access, the non-conflict random access procedure effectively terminates after the UEs successfully receive a random access response.

[0139] 3GPP is also considering a two-step RACH procedure for 5G NR, in which message 1, corresponding to messages 1 and 3 in the four-step RACH procedure, is sent first. Then, the gNB responds with message 2, corresponding to messages 2 and 4 in the LTE RACH procedure. Due to the reduction in message exchange, the delay in the two-step RACH procedure may be reduced compared to the four-step RACH procedure. Radio resources for messaging are optionally set by the network.

[0140] After introducing an exemplary random access procedure, the following describes one specific exemplary DRX function that can be envisioned for this solution. Battery saving is a critical issue in mobile communications. To reduce battery consumption in the UE, a mechanism is used that minimizes the time the UE spends monitoring the PDCCH, which is referred to as the intermittent receive (DRX) function.

[0141] The DRX function may be set for RRC_IDLE. Since the DRX function may also be set for UEs in the "RRC_CONNECTED" state, the UE does not necessarily need to monitor the downlink channel for downlink control information (the expression "the UE monitors the downlink channel for downlink control information" can also be expressed as "the UE monitors the PDCCH"). (See Technical Standard TS36.321, Version 15.2.0, Section 5.7.)

[0142] The following parameters are available to define the behavior of the DRX UE: the on-duration period during which the mobile node is active (e.g., during DRX active time) and the period during which the mobile node is in DRX (e.g., not during DRX active time and in DRX off time). -On-duration: The duration of the downlink subframe during which the user device receives and monitors the PDCCH after waking up from the DRX, i.e., more specifically, the duration of the subframe containing the PDCCH (also referred to as the PDCCH subframe). Here, it should be noted that throughout this invention, the term "PDCCH" refers to the PDCCH, EPDCCH (of the subframe if configured), or, in the case of a relay node where R-PDCCH is configured and not suspended, the R-PDCCH. If the user device successfully decodes the PDCCH, the user device remains awake / active and starts the inactivity timer. [1-200 subframes; 16 steps: 1-6, 10-60, 80, 100, 200] -DRX Inactivity Timer: The period of downlink subframes during which the user device waits to successfully decode the PDCCH after the last successful decode of the PDCCH. If the UE fails to decode the PDCCH during this period, it re-enters the DRX. The user device restarts the inactivity timer following a single successful decode of the PDCCH for the initial transmission only (i.e., not for retransmission). [1-2560 subframes; 22 steps, 10 spares: 1-6, 8, 10-60, 80, 100-300, 500, 750, 1280, 1920, 2560] -DRX Retransmission timer: Specifies the number of consecutive PDCCH subframes that the UE expects to perform a downlink retransmission after the first available retransmission time. [1-33 subframes, 8 steps: 1, 2, 4, 6, 8, 16, 24, 33] -DRX short cycle: Specifies the periodic repetition of the on-duration period followed by possible inactivity for the short DRX cycle. This parameter is optional. [2-640 subframes; 16 steps: 2, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640] -DRX short cycle timer: Specifies the number of consecutive subframes during which the UE follows a short DRX cycle after the DRX inactivity timer expires. This parameter is optional. [1-16 subframes] -Long DRX Cycle Start offset: Specifies the subframe offset at which the periodic repetition of the on-duration, followed by a possible inactivity period, begins for the long DRX cycle (determined by the formula defined in TS36.321 Section 5.7). [Cycle length 10-2560 subframes; 16 steps: 10, 20, 30, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640, 1024, 1280, 2048, 2560; offset is an integer between [0-the subframe length of the selected cycle]]

[0143] The total duration during which a UE is awake is referred to as "active time" or DRX active time. Active time includes, for example, the on duration of a DRX cycle, the time during which the UE is performing continuous reception while the inactivity timer has not expired, and the time during which the UE is performing continuous reception while waiting for a downlink retransmission after 1 HARQ RTT. Similarly, on the uplink, the UE is awake (i.e., DRX active time) in subframes every 8ms after the initial uplink transmit until the maximum number of retransmissions is reached, i.e., the UE can receive uplink retransmission grants.

[0144] A "DRX period" or "DRX off period" is the duration of a downlink subframe during which the UE can skip receiving the downlink channel for battery-saving purposes, i.e., does not need to monitor the downlink channel. The operation of DRX gives the mobile terminal the opportunity to repeatedly deactivate the radio circuit (according to the currently active DRX cycle) to conserve power. Whether the UE actually remains in DRX (i.e., inactive) during a DRX period may be decided by the UE. For example, the UE may perform cross-frequency measurements that cannot normally be done during the on-duration and therefore need to be performed at some other time (e.g., during a DRX off period).

[0145] Parameterizing the DRX cycle involves a trade-off between battery saving and delay. To satisfy these conflicting requirements, two DRX cycles (short cycle and long cycle) may be set for each UE. The short DRX cycle is optional; i.e., only the long DRX cycle may be used. Transitions between the short DRX cycle, long DRX cycle, and continuous reception are controlled by a timer or by explicit commands from the eNodeB.

[0146] Figure 15 discloses an example of DRX operation. The UE checks for scheduling messages (also referred to as downlink / uplink assignments; for example, indicated by C-RNTI in the PDCCH) during an "on-duration" period, which is the same for both long and short DRX cycles. When a scheduling message is received during the "on-duration" period, the UE starts an "in-activity timer" and continues to monitor the PDCCH in all subframes while the in-activity timer is running. During this period, the UE may be considered to be in "continuous receive mode". Whenever a scheduling message is received while the in-activity timer is running, the UE restarts the in-activity timer, and when the in-activity period ends, the UE transitions to a short DRX cycle and starts a "short DRX cycle timer" (assuming a short DRX cycle is set). When the short DRX cycle timer expires, the UE transitions to a long DRX cycle. A short DRX cycle can also be initiated by a DRX MAC control element that the eNB can send at any time to immediately enter a DRX cycle, i.e., a short DRX cycle (if configured as such) or a long DRX cycle (if no short DRX cycle is configured).

[0147] The basic DRX concepts described above for LTE also apply to the new 5G NR, but there are some differences (see Section 5.7 of 3GPP TS38.321 v15.2.1).

[0148] As is evident from this, the DRX for 5G NR is based on long DRX cycles and short DRX cycles, and the transition between long and short DRX cycles, based on a short DRX cycle timer, defines the on duration at the beginning of the DRX cycle, and the DRX inactivity timer defines the duration of continuous reception after receiving a PDCCH, after which the UE enters a sleep state. Thus, conceptually, the 5G-NR DRX mechanism functions as shown in Figure 15.

[0149] Referring to Figure 16, an improved handover communication solution is presented that allows the UE to access the target cell and continue communicating with the serving cell in parallel. The corresponding UE behavior according to a simplified exemplary embodiment is shown in Figure 17.

[0150] The UE is assumed to eventually be handed over from its serving gNB to another neighboring gNB. Correspondingly, as is evident from Figure 16, the UE is exemplary assumed to be communicating with the serving gNB in ​​UL / DL. The UE is further assumed to send a measurement report to the serving base station. The measurement report may be sent, for example, according to the improved measurement and reporting solutions described above in relation to Figures 6-9, but may also be sent by the UE as is generally known in the prior art. In other words, the following improved handover solutions may be used independently, or optionally in combination with the improved measurement and reporting procedures described above.

[0151] Although not illustrated, assume that the UE continues to communicate with the serving gNB during the handover process (for example, sending a handover request and receiving a handover acknowledgment while the serving gNB makes a handover decision).

[0152] The serving gNB is deemed to have decided to opt for a handover and therefore initiates the handover procedure with the neighboring gNB that is the target of the UE handover by sending a handover request message and receiving a handover acknowledgment message in return. The serving gNB then sends a handover command message to the UE. The handover command may be an unconditional handover command that compels the UE to perform the handover. According to a different solution, the handover command message may instead be conditional and include, for example, at least a handover acceptance condition for the UE to finally decide whether and when to perform the handover based on the handover acceptance condition. Furthermore, the handover command message may optionally include a handover rejection condition in line with the improved conditional handover solution described above in relation to Figures 10-12. In other words, the improved handover communication solution presented herein may, but does not necessarily, be combined with the improved conditional handover solution.

[0153] Furthermore, we assume that after receiving a (conditional) handover command, the UE initiates a connection to the target gNB by performing a random access procedure between the UE and the target neighbor gNB. In parallel, the UE will continue to communicate with the serving gNB. This parallel operation is shown in Figure 16 as separate boxes containing arrows indicating specific messages exchanged between entities.

[0154] The UE and serving gNB are operating DRX functions similar to or the same as those illustrated above in relation to Figure 15, for example. To keep Figure 16 clear, the DRX off period and DRX active period are shown only for parallel communication between the UE and the serving gNB and target gNB, but it should be understood that the DRX function is also followed by the UE and serving gNB when communicating with each other.

[0155] The DRX function alternates between a DRX active period during which the UE may communicate with the gNB (in UL and / or DL) and a DRX off period during which the UE has the opportunity to conserve power by, for example, not transmitting or monitoring channels for receiving data. According to this improved handover communication solution, as also shown in Figure 16, the UE communicates with the serving base station during the DRX active period and with the target gNB during the DRX off period. This includes sending random access procedure messages 1 and 3 to the neighboring gNB during the DRX off period, while receiving random access procedure messages 2 and 4 from the neighboring gNB during the DRX off period. Thus, the serving gNB and UE can still continue DL / UL transmissions without conflicting with the random access procedures performed between the UE and the target gNB.

[0156] There are several embodiments of how a UE can perform a random access procedure during a DRX off period. Briefly, the DRX function performed in the serving radio cell is coordinated with the PRACH resources used by the UE in the target radio cell. For example, the target gNB may have uplink resources reserved for the random access procedure and reserve dedicated resources among these PRACH resources for the UE being handed over. These dedicated PRACH resources may then be used by the UE and the target gNB to exchange messages for the random access procedure.

[0157] According to one exemplary embodiment (shown in Figures 18 and 20), the serving gNB transmits information about the UE's DRX settings to the target gNB. The target gNB can then adapt the PRACH resources used by the UE for random access procedures to the DRX settings received from the serving gNB, so that the PRACH resources used by the UE belong to the DRX-off period. This information about the UE's DRX settings may be transmitted, for example, with a handover request message (see Figure 16) or in a separate message. Figure 20 is shown to cover both of these variations. Furthermore, information about the adapted PRACH resources is provided to the UE. According to one embodiment, the PRACH resource information is first transmitted to the serving gNB (for example, with a handover acknowledgment message, as illustrated in Figure 20) and then transmitted to the UE, for example, with a handover command message (or separately from a handover command message).

[0158] In any case, the UE receives information about the PRACH resources it will use for the random access procedure (already adapted by the target gNB) and uses the PRACH resources that belong to the DRX function off period as configured by the target gNB. Similarly, the target gNB uses coordinated timing when sending random access messages 2 and 4 to the UE. Random access messages 2 and 4 may be received by the UE during the DRX off period when it is not communicating with the serving gNB. Correspondingly, the UE monitors whether random access messages are received during the DRX off period (e.g., by PDCCH from the target gNB).

[0159] Information regarding the round-trip delay experienced by the UE when communicating with the serving gNB (e.g., timing advance value or reference signal time difference measurement) may also be transmitted to the target gNB, for example, together with or separately from the DRX settings. This information may then be used by the target gNB to more accurately align the PRACH resources with the DRX off-periods, so as to avoid delays in communication causing the PRACH resources to belong to the DRX active period instead of the DRX off-period.

[0160] Additionally or alternatively, round-trip delays experienced by other UEs when communicating with the target gNB (e.g., timing advance values ​​or reference signal time difference measurements) may be used by the target gNB to improve coordination of dedicated PRACH resources with DRX off periods. In other words, the round-trip delay for another UE is used as an estimate of the round-trip delay experienced by the UE when performing a random access procedure with the target gNB. This is advantageous because the round-trip delays for other UEs are known by the target gNB, and therefore no exchange of information regarding round-trip delays is required. Furthermore, the round-trip delay estimate may be more accurate because it is estimated with reference to the same target gNB on which the UE performs random access.

[0161] In the previous embodiment, the PRACH resource was adapted while maintaining the initially configured DRX functionality. However, instead, according to the second exemplary embodiment described in relation to Figures 19 and 21, the DRX settings used by the UE at the serving base station are adapted to coordinate with the PRACH resource at the target gNB. More specifically, the serving gNB learns about the PRACH resource at the target gNB, which is used by the UE for random access, and then adapts its DRX settings so that the DRX off period for the serving radio cell matches the PRACH resource used at the target radio cell. The serving gNB can obtain information about the PRACH resource at the target radio cell from, for example, the target gNB. In one exemplary embodiment, when the target gNB receives a handover request, it provides the serving gNB with information about the PRACH resource along with a handover acknowledgment message.

[0162] Alternatively, the serving gNB may obtain information about PRACH resources based on the physical cell identification information of adjacent radio cells. The physical cell identification information (PCI) is obtained by the serving gNB, for example, from measurement reports received from the UE. Here, we assume that the PRACH resources are associated with the physical cell identification information so that the serving gNB can derive the PRACH resources from the PCI. For example, there may be multiple different PRACH resource settings, such as a total of three, which can be derived based on, for example, the formula (PCI mod3). In the above, any PCI that satisfies PCI mod3=0 is associated with PRACH resource setting 0, any PCI that satisfies PCI mod3=1 is associated with PRACH resource setting 1, and any PCI that satisfies PCI mod3=2 is associated with PRACH resource setting 2.

[0163] In any case, the DRX settings used by the UE in the serving gNB will be adapted accordingly. The adapted DRX settings will be notified to the UE, and the UE will adhere to those settings. For example, the adapted DRX settings may be sent to the UE with the handover command message or separately from the handover command message (for example, using the RRCReconfiguration message).

[0164] As already described in relation to the first exemplary embodiment above (adapting PRACH resources to DRX settings), information regarding the round-trip delay experienced by the UE when communicating with the serving gNB may be used by the serving gNB to more accurately align the PRACH resources with the duration of the DRX function. Information regarding the RTD in the serving radio cell is already available to the serving gNB. Additionally or alternatively, information regarding the round-trip delay experienced by another UE when communicating with the target gNB may be transmitted by the target gNB to the serving gNB, and the serving gNB then uses this round-trip delay related to the target gNB to set the DRX off period for dedicated PRACH resources in the target cell.

[0165] Following the improved handover communication solution described above, communication between the UE and the serving gNB can continue even while the UE is performing random access to the target radio cell, thus minimizing communication interruptions caused by handover. In effect, a make-before-break handover is achieved.

[0166] One important mechanism commonly used in LTE and 5G to improve communication between UE and gNB is the Hybrid Automatic Retransmission Request (HARQ) mechanism (see 3GPP TS36.321 v15.4.0 Section 5.4.2 and TS38.321 v15.4.0 Section 5.4.2). According to one exemplary embodiment, the following improved retransmission functionality can be based on this.

[0167] To provide reliability, there are two levels of retransmission: HARQ at the MAC layer and outer ARQ at the RLC layer. HARQ is a common technique for error detection and correction in packet transmission systems over unreliable channels. Hybrid ARQ is a combination of forward error correction (FEC) and ARQ. If an FEC-encoded packet is transmitted and the receiver cannot correctly decode it (errors are usually checked by CRC (Cyclic Redundancy Check)), the receiver requests retransmission of the packet.

[0168] The MAC layer includes HARQ entities responsible for transmit and receive HARQ operations. Transmit HARQ operations include transmitting and retransmitting transport blocks and receiving and processing ACK / NACK signaling. Receive HARQ operations include receiving transport blocks, synthesizing received data, and generating ACK / NACK signaling. Up to 16 parallel HARQ processes are used to support multi-process "Stop-And-Wait" (SAW) HARQ operations, enabling continuous transmission while previous transport blocks are being decoded. Each HARQ process is responsible for a separate SAW operation and manages a separate buffer.

[0169] The feedback provided by the HARQ protocol is either an acknowledgment (ACK) or a negative acknowledgment (NACK). ACKs and NACKs are generated depending on whether the transmission was received correctly (e.g., whether decoding was successful). Furthermore, in HARQ operation, the eNB can transmit a different encoded version of the original transport block in retransmission, and as a result, the UE can obtain additional encoding gain via composite gain using incremental-redundancy (IR) synthesis.

[0170] If an FEC-encoded packet is sent and the receiver is unable to decode it correctly (errors are usually checked by CRC (Cyclic Redundancy Check)), the receiver requests retransmission of the packet. Generally (and throughout this document), the transmission of additional information is referred to as “retransmission (of the packet),” and this retransmission may, but does not necessarily, mean the transmission of the same encoded information. Retransmission may also mean the transmission of any information belonging to the packet (e.g., additional redundant information), for example, by using a different redundant version.

[0171] Therefore, as described above, HARQ is used between the UE and the gNB. This also applies to the scenario described above where the UE and the serving gNB communicate with each other. Furthermore, HARQ may also be used in random access procedures between the UE and the target gNB. This also applies to the situation described above where the UE communicates in parallel with the serving base station (UL / DL communication) and the target gNB (random access) during handover (see, for example, Figure 16). For example, if eight HARQ processes are available in total at the UE, these eight HARQ processes may be shared to communicate with the serving gNB and the target gNB. However, the serving cell and the target cell do not need to coordinate their HARQ process IDs.

[0172] When a UE initiates a random access procedure, all HARQ processes may already be in use for communication with the serving cell. To ensure that HARQ remains available for random access to the target cell, the UE can reallocate one of the HARQ processes currently used for communication with the serving cell to the random access procedure. This overwrites the memory associated with that HARQ process with data from the random access message. In effect, the UE cancels one of the HARQ processes and then uses that one for the random access procedure.

[0173] The UE may select a HARQ process based on, for example, the priority of the data included in the HARQ process, or based on the data rate of the HARQ process, or simply randomly select a HARQ process from all of them.

[0174] A simplified, exemplary UE behavior in accordance with the above is shown in Figure 22.

[0175] This single reassigned HARQ process can no longer be used to communicate with the serving gNB. However, the serving gNB continues to use the reassigned HARQ process because it is unaware that the UE is now using that HARQ process for a different purpose. In response, the serving gNB may retransmit data about the reassigned HARQ process. However, in this case, the data from the HARQ process is no longer available (HARQ synthesis is not possible), and the UE attempts to decode the data only from the newly received transmission. If decryption is unsuccessful, the UE may send a NACK to the serving gNB.

[0176] On the other hand, if the UE is planning to send a new uplink transmission to the serving gNB and the HARQ process is unavailable, the UE will perform the UL transmission without the HARQ process and, for example, will not hold the UL transmission in the HARQ buffer. If the serving gNB requests a retransmission of that UL data, the UE must encode the same data and retransmit the encoded data to the serving gNB.

[0177] Alternatively, the serving gNB may attempt to avoid using all HARQ processes during handover. For example, if the serving gNB is aware (via measurement reporting) that the UE is approaching a cell edge, the serving gNB may reduce the DL transmission or UL grant of the serving gNB to the UE so that at least one HARQ process is free for the UE to perform random access with the target gNB.

[0178] (Further aspects) According to a first embodiment, a user device (UE) is provided which, during operation, performs power-related measurements on at least one radio carrier and generates measurement results based on the power-related measurements performed. The reporting of measurement results by the UE is based on at least one reporting trigger condition that must be satisfied. The processing circuit decides whether to adjust the measurement results and at least one of the at least one reporting trigger condition in order to trigger the reporting of the measurement results sooner than if there were no adjustment. If it decides to adjust, the processing circuit adjusts the measurement results and at least one of the at least one reporting trigger condition in order to trigger the reporting of the measurement results sooner than if there were no adjustment. After the adjustment, the processing circuit determines, based on the at least one reporting trigger condition and the generated measurement results, whether at least one reporting trigger condition is satisfied in order to report the measurement results. If the reporting of measurement results is triggered, the transmitter of the UE transmits a measurement report containing the measurement results.

[0179] According to a second embodiment provided in addition to the first embodiment, the adjustment of at least one report trigger condition includes a processing circuit applying at least one positive or negative power offset to at least one report trigger condition during operation. In an optional embodiment, the processing circuit determines the power offset from configuration information received from a serving base station to which the UE is connected, or determines the power offset based on the difference between a generated measurement result and a previously generated measurement result. In another optional embodiment, one offset is determined for each measurement result among the generated measurement results and used in the adjustment, and optionally, for each report trigger condition, one offset is determined for the serving radio carrier or the adjacent radio carrier. In another optional embodiment, one offset is determined for the serving radio carrier and another offset is determined for the adjacent radio carrier. In another optional embodiment, one offset is determined for each report trigger condition and used in the adjustment.

[0180] According to a third aspect provided in addition to the first or second aspect, the adjustment of the measurement result includes a processing circuit determining the difference between a generated measurement result and a previously generated measurement result, and applying the determined difference to the generated measurement result to generate an adjusted measurement result. The processing circuit determines whether or not to report the measurement result based on at least one reporting trigger condition and the adjusted measurement result.

[0181] In addition to any of the first to third embodiments, according to a fourth embodiment provided, the performance of power-related measurements by the processing circuit includes performing measurements on at least one non-terrestrial radio carrier. In one optional embodiment, the decision of whether or not to perform adjustments by the processing circuit is based on whether the radio carrier is a non-terrestrial radio carrier or a terrestrial radio carrier. In one optional embodiment, the adjustment is performed if the reporting trigger condition is based on the measurement results of measurements performed on the non-terrestrial radio carrier.

[0182] In addition to one of the first to fourth embodiments, a fifth embodiment is provided, the measurement results can be used by the serving base station to which the UE is connected to determine whether to initiate a procedure for handing over the UE from the current serving radio cell to another radio cell controlled by the serving base station. At least one reporting trigger condition is set to be met when the serving base station can decide to initiate a procedure for handing over the UE from the current serving radio cell to another cell.

[0183] According to a sixth aspect provided in addition to one of the first to fifth aspects, the UE further comprises a receiver that, in operation, receives a conditional handover command, the conditional handover command message includes at least one handover acceptance condition that the UE must satisfy in order to perform a handover, and / or at least one handover rejection condition that the UE must satisfy in order to reject a handover. The processing circuit determines whether the handover acceptance condition is met, and if it is met, performs a handover in accordance with the received conditional handover command, and optionally transmits information regarding a handover rejection if the handover acceptance condition is not met. In an optional other embodiment, the processing circuit determines whether the handover rejection condition is met, and if it is met, transmits information regarding a handover rejection.

[0184] In addition to the sixth aspect, according to the seventh aspect provided, information regarding a handover refusal is transmitted in a radio resource control (RRC) message or as a separate measurement report. Alternatively, information regarding a handover refusal is transmitted with uplink data, and optionally, information regarding a handover refusal is transmitted as a control element (CE) of the medium access control (MAC) protocol. In one optional embodiment, a processing circuit determines whether uplink data is transmitted to the serving base station; if uplink data is not transmitted, the handover refusal is transmitted in an RRC message or as a separate measurement report; if uplink data is transmitted, the handover refusal is transmitted with the uplink data.

[0185] According to the seventh aspect, provided in addition to one of the sixth to seventh aspects, if the processing circuit determines that a handover refusal condition is met, the processing circuit sends information regarding the handover refusal to the serving base station and then decides not to send measurement reports for a certain period of time. In one optional embodiment, the period is set by the serving base station.

[0186] In accordance with the ninth aspect provided in addition to one of the first to eighth aspects, if neither the handover acceptance condition nor the handover rejection condition is met, the transmitter sends a resource allocation extension request to the serving base station to extend the resource allocation time in the adjacent radio cell during operation.

[0187] According to a tenth aspect provided in addition to one of the first to ninth aspects, the UE performs a handover from the current serving radio cell to another radio cell, and performing a handover includes the UE performing a random access procedure with the other radio cell. After initiating the handover to another radio cell, the UE continues to communicate with the serving base station on the uplink and / or downlink during the communication period of an intermittent receive (DRX) function operated by the UE for communication with the serving base station. The UE sends random access procedure messages during the sleep period of the intermittent receive (DRX) function operated by the UE for communication with the serving radio cell, and optionally the communication period does not overlap with the sleep period. In one optional embodiment, the UE receives random access procedure messages during the sleep period of the DRX function.

[0188] According to an eleventh aspect provided in addition to one of the first to tenth aspects, the UE performs a handover from the current serving radio cell to another radio cell, and performing the handover includes performing a random access procedure with the other radio cell. After initiating the handover to another radio cell, the UE continues to communicate with the serving base station on the uplink and / or downlink using multiple hybrid automatic retransmission request (HARQ) processes. The UE uses multiple HARQ processes for the random access procedure, and if all of the multiple HARQ processes are already being used to communicate with the serving base station, the processing circuitry determines, during operation, one of the multiple HARQ processes to be reused instead for the random access procedure.

[0189] According to a twelfth aspect provided in addition to the eleventh aspect, each HARQ process is used to store previously transmitted data in its associated memory for possible later retransmission, or to store previously received data in its associated memory for possible later synthesis with later received data. Reusing a HARQ process for a random access procedure involves overwriting the memory associated with the reused HARQ process with data buffered for the random access procedure. In one optional embodiment, if all HARQ processes are used and one of the HARQ processes is reused for a random access procedure, the processing circuit does not use the reused HARQ process to store new uplink transmissions during operation. In another optional embodiment, if all HARQ processes are used and one of the HARQ processes is reused for a random access procedure, the processing circuit does not use the reused HARQ process to store received downlink transmissions.

[0190] According to the 13th aspect, the following steps are performed by the user equipment (UE), namely: A step of performing power-related measurements on at least one wireless carrier and generating measurement results based on the power-related measurements performed, wherein the reporting of the measurement results by the UE is based on at least one reporting trigger condition that must be met. A step of deciding whether or not to adjust the measurement results and at least one of the at least one reporting trigger conditions, so as to trigger the reporting of the measurement results earlier than if no adjustment were made. If adjustment is decided upon, the steps include adjusting the measurement results and at least one of the reporting trigger conditions so that the reporting of the measurement results is triggered earlier than if no adjustment were made, After adjustment, the process involves determining whether at least one reporting trigger condition is met based on at least one reporting trigger condition and the measurement result, in order to report the measurement result. If the reporting of measurement results is triggered, the step is to send a measurement report containing the measurement results, A method including this is provided.

[0191] In a 14th aspect, a base station is provided having a processing circuit that determines whether to instruct a user equipment (UE) to adjust the measurement results and at least one of at least one report trigger condition, in order to trigger the reporting of the measurement results sooner than if there were no adjustment. If the decision by the processing circuit is to instruct the UE, the base station transmitter sets the UE to adjust the measurement results and at least one of at least one report trigger condition in order to trigger the reporting of the measurement results sooner than if there were no adjustment. The base station receiver receives a measurement report from the UE. The measurement report includes the measurement results of measurements performed by the UE on at least one radio carrier, and the reporting of the measurement results by the UE is based on at least one report trigger condition that is to be satisfied.

[0192] In addition to the 14th embodiment, according to a 15th embodiment provided, the processing circuit determines at least one positive or negative power offset for at least one reporting trigger condition. The transmitter transmits configuration information to the UE indicating the determined positive or negative power offset. In one optional embodiment, one offset is determined for each measurement result among the generated measurement results. In one optional embodiment, for each reporting trigger condition, one offset is determined for the serving radio carrier or the adjacent radio carrier. In one optional embodiment, one offset is determined for the serving radio carrier and another offset is determined for the adjacent radio carrier.

[0193] According to the 14th or 15th aspect, plus the 16th aspect provided, the processing circuit's decision on whether to instruct the UE to adjust the measurement results and at least one of the at least one reporting trigger conditions so as to trigger the reporting of the measurement results earlier than if there were no adjustment is based on whether the radio carrier is a non-terrestrial radio carrier or a terrestrial radio carrier. In one optional embodiment, if the UE is performing the measurement on a non-terrestrial radio carrier, the processing circuit decides to instruct the UE to adjust.

[0194] In accordance with a 17th aspect provided in addition to any of the 14th to 16th aspects, the transmitter transmits a conditional handover command to the UE, the conditional handover command message including at least one handover acceptance condition that the UE must satisfy in order to perform a handover, and / or at least one handover rejection condition that the UE must satisfy in order to reject a handover. In an optional embodiment, the receiver receives information regarding the UE's rejection of the handover, and the transmitter transmits a request to the adjacent target base station, which is the target of the handover, to release resources in the adjacent radio cell that were reserved for the UE's handover. In an optional embodiment, the receiver receives a first resource reservation extension request from the UE to extend the resource reservation time in the adjacent radio cell. The transmitter transmits a second resource reservation extension request to the adjacent target base station, which is the target of the handover, to extend the resource reservation time in the adjacent radio cell.

[0195] In addition to any of the 14th to 17th embodiments, according to an 18th embodiment, the processing circuit adapts the sleep period of the intermittent receive (DRX) function operated by the UE for communication with the base station to match the random access resources used by the UE to perform random access procedures with the adjacent target base station. In an optional embodiment, the processing circuit obtains information about the random access resources of the adjacent target base station based on information received from the adjacent target base station or based on the cell identification information of the adjacent target base station.

[0196] According to a 19th aspect provided in addition to any of the 14th to 18th aspects, another UE is handed over to the base station as a handover target from another base station, and the transmitter sends a random access procedure message to the other UE during the sleep period of the intermittent receive (DRX) function operated by the other UE for communication with the other base station, and the receiver receives the random access procedure message from the other UE during the sleep period of the DRX function. In an optional embodiment, the receiver receives configuration information regarding the DRX function of the other UE. Processing circuitry adapts the random access resources used by the other UE to perform the random access procedure with the base station to coincide with the sleep period of the DRX function. The transmitter transmits information about the adapted random access resources to the other base station.

[0197] (Implementation by hardware and software of this disclosure) This disclosure can be implemented by software, by hardware, or by software working in conjunction with hardware. Each functional block used in the description of each embodiment above can be implemented in part or in whole by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled in part or in whole by the same LSI or combination of LSIs. An LSI can be formed individually as a chip, or a single chip can be formed to include some or all of the functional blocks. An LSI can include data input / output units coupled to itself. An LSI may be referred to here as an IC (integrated circuit), system LSI, super LSI, or ultra LSI depending on the degree of integration. However, the technology for realizing integrated circuits is not limited to LSIs and can be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, an FPGA (field-programmable gate array) that can be programmed after the manufacture of the LSI, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells located inside the LSI can also be used. This disclosure can be implemented as digital or analog processing. If LSIs are replaced by future integrated circuit technologies as a result of advances in semiconductor technology or other derivative technologies, functional blocks can be integrated using those future integrated circuit technologies. Biotechnology can also be applied.

[0198] This disclosure can be implemented by any type of device or system having communication capabilities (collectively referred to as communication devices).

[0199] Non-exclusive examples of communication devices include telephones (mobile phones, smartphones, etc.), tablets, personal computers (PCs) (laptops, desktops, netbooks, etc.), cameras (digital still / video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine devices, vehicles with communication capabilities (cars, airplanes, ships, etc.), and combinations of the above-mentioned devices.

[0200] Communication devices are not limited to portable or mobile devices, but also include all kinds of non-portable or fixed devices, devices, or systems, such as smart home devices (appliances, lighting fixtures, smart meters, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0201] Communication includes data communication via cellular systems, wireless LAN systems, and communication satellite systems, as well as data communication using combinations of these.

[0202] Furthermore, the communication device also includes devices such as controllers and sensors that are connected to or linked to a communication device that performs the communication functions described in this disclosure. For example, the communication device includes controllers and sensors that generate control signals and data signals used by the communication device that performs the communication functions of the communication device.

[0203] Furthermore, communication equipment includes infrastructure facilities such as base stations, access points, and any other devices, devices, or systems that communicate with or control the aforementioned non-limited types of equipment.

[0204] Furthermore, various embodiments may be implemented by software modules executed by a processor or directly in hardware. Alternatively, software modules and hardware implementations can be combined. Software modules can be stored in any type of computer-readable storage medium, such as RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROMs, and DVDs. It should also be noted that individual features of different embodiments, individually or in any combination, may be the subject of other embodiments.

[0205] Those skilled in the art will understand that numerous modifications and / or changes can be made to the present disclosure, as shown in the specific embodiments. Therefore, these embodiments should be considered illustrative and not restrictive in all respects.

Claims

1. A communication device, A processing circuit that performs power-related measurements in a wireless carrier to generate measurement results, and reports the measurement results by the communication device based on a reporting trigger condition that compares the measurement results of a serving cell or adjacent cell with a threshold, A transmitter that transmits a measurement report including the measurement result when the measurement result satisfies the report trigger condition, A receiver that receives a conditional handover command, wherein the conditional handover command includes at least one handover acceptance condition that is satisfied for the communication device to perform a handover, Equipped with, The aforementioned processing circuit is Whether or not to adjust the threshold is determined according to whether the wireless carrier is associated with a non-terrestrial network. If an adjustment is decided upon, the processing circuit adjusts the threshold so as to trigger the reporting of the measurement result earlier than if no adjustment were made. The aforementioned reporting trigger conditions before adjustment are used whether the wireless carrier is a terrestrial network or a non-terrestrial network. The adjusted reporting trigger condition is used when the wireless carrier is the non-terrestrial network. The threshold in the reporting trigger condition before adjustment and the threshold in the reporting trigger condition after adjustment are set by the serving base station. The aforementioned transmitter is If the adjusted report trigger conditions are met, the measurement report including the measurement results is transmitted. The communication device determines whether the handover acceptance conditions are met, and if the handover acceptance conditions are met, it performs a handover in accordance with the received conditional handover command. Communication device.

2. The adjustment is an adjustment by at least one positive or negative power offset, The processing circuit determines the power offset from the configuration information received from the serving base station to which the communication device is connected, or determines the power offset based on the difference between the generated measurement result and a previously generated measurement result. The aforementioned reporting trigger condition includes at least one of a plurality of trigger conditions, The power offset is defined for each trigger condition, with respect to the serving cell or to the adjacent cell. The communication device according to claim 1.

3. The adjustment of the measurement result includes the processing circuit determining the difference between the generated measurement result and a previously generated measurement result, and applying the determined difference to the generated measurement result to generate an adjusted measurement result. The communication device according to claim 1 or 2.

4. A communication device performs power-related measurements in a wireless carrier to generate measurement results, and reports the measurement results by the communication device based on a reporting trigger condition that compares the measurement results of the serving cell or adjacent cell with a threshold; The communication device transmits a measurement report including the measurement result when the measurement result satisfies the report trigger condition. A step of receiving a conditional handover command, wherein the conditional handover command includes at least one handover acceptance condition that is satisfied for the communication device to perform a handover; Includes, The reporting trigger condition is a comparison of the power-related measurement and the threshold, using a first value used when the radio carrier is on a terrestrial network or a non-terrestrial network, and a second value used when the radio carrier is on a non-terrestrial network, wherein the first and second values ​​are set by the serving base station. The aforementioned communication device is Whether or not to adjust the threshold is determined according to whether the wireless carrier is associated with a non-terrestrial network. If an adjustment is decided upon, the threshold is adjusted so as to trigger the reporting of the measurement results earlier than if no adjustment were made. The aforementioned reporting trigger conditions before adjustment are used whether the wireless carrier is a terrestrial network or a non-terrestrial network. The adjusted reporting trigger condition is used when the wireless carrier is the non-terrestrial network. After the adjustment, in order to report the measurement results, it is determined whether the reporting trigger conditions are met. The threshold in the reporting trigger condition before adjustment and the threshold in the reporting trigger condition after adjustment are set by the serving base station. If the adjusted report trigger conditions are met, the measurement report including the measurement results is transmitted. The communication device determines whether the handover acceptance conditions are met, and if the handover acceptance conditions are met, it performs a handover in accordance with the received conditional handover command. method.

5. A transmitter that determines and sets in the communication terminal whether to instruct the communication device to adjust the reporting trigger conditions for comparing measurement results with thresholds, in accordance with the wireless carrier to the terminal device being associated with a non-terrestrial network, so as to trigger the reporting of the measurement results earlier than if there were no adjustment, Based on the reporting trigger conditions, a receiver receives the measurement results of power measurements performed by the communication device on the wireless carrier from the communication device. Equipped with, The pre-adjustment report trigger condition is used whether the wireless carrier is a terrestrial network or a non-terrestrial network, and the adjusted report trigger condition is used when the wireless carrier is a non-terrestrial network. The pre-adjustment report trigger condition and the adjusted report trigger condition are set in the terminal device. A conditional handover command is transmitted to the communication device, which will execute a handover if the handover acceptance conditions are met. Base station.

6. The adjustment is an adjustment by at least one positive or negative power offset, The transmitter transmits the setting information indicating the power offset to the communication device. The aforementioned reporting trigger condition includes at least one of a plurality of trigger conditions, The power offset is defined for each trigger condition, with respect to the serving cell or to the adjacent cell. The base station according to claim 5.

7. The steps include determining and setting for the communication device whether the base station instructs the communication device to adjust the reporting trigger conditions for comparing measurement results with thresholds, according to whether the radio carrier to the communication device is related to a non-terrestrial network, so as to trigger the reporting of the measurement results earlier than if there were no adjustment, Based on the reporting trigger conditions, the communication device receives the measurement results of a power measurement performed by the communication device on the wireless carrier. Includes, The aforementioned reporting trigger conditions before adjustment are used whether the wireless carrier is a terrestrial network or a non-terrestrial network. The adjusted reporting trigger condition is used when the wireless carrier is the non-terrestrial network. The report trigger conditions before adjustment and the report trigger conditions after adjustment are set by the serving base station. A conditional handover command is transmitted to the communication device, which will execute a handover if the handover acceptance conditions are met. method.

8. An integrated circuit that controls the processing of a communication device, wherein the processing is The communication device performs power-related measurements in the wireless carrier to generate measurement results, and reports the measurement results based on a reporting trigger condition that compares the measurement results of a serving cell or adjacent cell with a threshold. If the measurement result satisfies the reporting trigger condition, the process involves sending a measurement report including the measurement result. A process for receiving a conditional handover command, wherein the conditional handover command includes at least one handover acceptance condition that is satisfied for the communication device to perform a handover; Includes, The process to be reported above is: Whether or not to adjust the threshold is determined according to whether the wireless carrier is associated with a non-terrestrial network. If an adjustment is decided upon, the processing circuit adjusts the threshold so as to trigger the reporting of the measurement result earlier than if no adjustment were made. The aforementioned reporting trigger conditions before adjustment are used whether the wireless carrier is a terrestrial network or a non-terrestrial network. The adjusted reporting trigger condition is used when the wireless carrier is the non-terrestrial network. The threshold in the reporting trigger condition before adjustment and the threshold in the reporting trigger condition after adjustment are set by the serving base station. After the adjustment, in order to report the measurement results, it is determined whether the reporting trigger conditions are met. The aforementioned transmission process is: If the adjusted report trigger conditions are met, the measurement report including the measurement results is transmitted. Determine whether the handover acceptance conditions are met, and if the handover acceptance conditions are met, perform the handover according to the received conditional handover command. Integrated circuit.

9. An integrated circuit that controls the processing of a base station, wherein the processing is The process of determining and setting in the communication terminal whether to instruct the communication device to adjust the reporting trigger conditions for comparing measurement results with thresholds, in accordance with the wireless carrier to the terminal device being related to a non-terrestrial network, so as to trigger the reporting of the measurement results earlier than if there were no adjustment, Based on the aforementioned reporting trigger conditions, the process involves receiving the measurement results of the power measurement performed by the communication device on the wireless carrier from the communication device, Includes, The aforementioned reporting trigger conditions before adjustment are used whether the wireless carrier is a terrestrial network or a non-terrestrial network. The adjusted reporting trigger condition is used when the wireless carrier is the non-terrestrial network. The report trigger conditions before adjustment and the report trigger conditions after adjustment are set by the serving base station. A conditional handover command is transmitted to the communication device, which will execute a handover if the handover acceptance conditions are met. Integrated circuit.

Images