Early channel state information reporting

Abstract

Disclosed is a solution comprising receiving (200) from a network node a configuration message configuring the apparatus to measure and report CSI of one or more candidate cells, said configuration comprising information on a set of measurement reference signals or a set of measurements to be reported for the one or more candidate cells; determining (202) that at least one of the measurements to be reported is invalid or unavailable at a reporting occurrence for one or more of the candidate cells; determining (204) a continuation of measuring and reporting based on the configuration message and the determination that at least one of the measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

Description

[0001] EARLY CHANNEL STATE INFORMATION REPORTING

[0002] FIELD

[0003] The following example embodiments relate to wireless communication.

[0004] BACKGROUND

[0005] In wireless communication systems, terminal devices are usually configured to transmit to network information on the state of the channel used in the communication between the terminal device and a network transmission point or a base station. Based on the channel state information, properties of the communication may be optimised. When the terminal device performs a handover to a new transmission point or base station, early reporting of channel properties between the terminal device and the new transmission point or base station enhances the quality of the new connection.

[0006] SUMMARY

[0007] The scope of protection sought for various example embodiments is set out by the claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the claims are to be interpreted as examples useful for understanding various embodiments.

[0008] According to an aspect, there is provided a method comprising: receiving from a network node a configuration message configuring the apparatus to measure and report channel state information of one or more candidate cells, said configuration comprising information on at least one of a set of measurement reference signals and a set of measurements to be reported for the one or more candidate cells, determining that at least one of the measurements of the set of measurements to be reported is invalid or unavailable at a reporting occurrence for one or more of the candidate cells, determining a continuation of measuring and reporting based on the configuration message and the determination that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

[0009] According to an aspect, there is provided there is provided a method comprising: transmitting a configuration message to a terminal device, the message comprising configuration for the terminal device to measure channel state informationof one or more candidate cells, the configuration comprising a configuration information of a set of measurement reference signals or / and a set of measurements to be made for the one or more of the candidate cells; determine that at least one channel state information measurement is invalid or unavailable at a reporting occurrence for one or more of candidate cells; continue to stop measuring and reporting based on the configuration message and the determination for the one or more candidate cell.

[0010] According to an aspect, there is provided there is provided a method comprising: transmitting a channel state information reference signal, receiving a report from a terminal device, the report comprising status of the channel state information measurement the terminal device is configured to perform.

[0011] According to an aspect, there is provided there is provided a method comprising: receiving from a network node a configuration message configuring the apparatus to measure and report channel state information of one or more candidate cells, the configuration comprising at least one of configuration information of a set of measurement reference signals and a set of measurements to be reported for the one or more of the candidate cells; measuring channel state information for at least one of the candidate cells, said measurement comprising a set of measurements; determining that at least one measurement of the set of measurements to be reported is valid or available at a reporting occurrence for the at least one candidate cell; sending a report to the at least one candidate cell, said report comprising the at least one measurement of the set of measurements determined to be valid or available

[0012] According to an aspect, there is provided there is provided a method comprising: transmitting a measurement reference signal; receiving a channel state information measurement report from a terminal device, the report comprising the at least one measurement of the set of measurements the terminal device determined to be valid or available.

[0013] According to an aspect, there is provided an apparatus comprising means for causing the apparatus to perform the method of any above aspects.

[0014] According to an aspect, there is provided an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least the method of any of the aspects.According to an aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the method of any of the aspects.

[0015] According to an aspect, there is provided a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the method of any of the aspects.

[0016] According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the method of any of the aspects.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in which

[0019] FIG. 1 illustrates an example of a wireless communication network;

[0020] FIGS 2, 3, 4, 5 and 6 a flow charts illustrating some embodiments; FIG. 7 is a signalling chart illustrating some embodiments;

[0021] FIGS. 8A and 8B illustrate examples of a report configuration ID; FIGS. 9, 10 and 11 illustrate example of apparatuses in which some embodiments may be applied.

[0022] DETAILED DESCRIPTION

[0023] The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments within the scope of the claims. Furthermore, the words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned, and such embodiments may also contain features that have not been specifically mentioned. Reference numbers, in the description and / or in the claims, serve to illustrate the embodiments with reference to the drawings, without limiting the embodiments to these examples only.Some example embodiments described herein may be implemented in a wireless communication network comprising a radio access network based on one or more of the following radio access technologies (RATs): fourth generation (4G), fifth generation (5G ), 5G new radio (NR), 5G-Advanced (i.e., 3GPP NR Rel-18 and beyond), sixth generation (6G), or seventh generation (7G). Some examples of radio access networks include the universal mobile telecommunications system (UMTS) radio access network (UTRAN), the evolved universal terrestrial radio access network (E-UTRA), or the next generation radio access network (NG-RAN). The wireless communication network may further comprise a core network, and some example embodiments may also be applied to network functions of the core network.

[0024] It should be noted that the embodiments are not restricted to the wireless communication network given as an example, but a person skilled in the art may also apply the solution to other wireless communication networks or systems provided with necessary properties. For example, some example embodiments may also be applied to a communication system based on IEEE 802.11 specifications, or a communication system based on IEEE 802.15 specifications. IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers.

[0025] FIG. 1 depicts an example of a simplified wireless communication network showing some physical and logical entities. The connections shown in FIG. 1 may be physical connections or logical connections. It is apparent to a person skilled in the art that the wireless communication network may also comprise other physical and logical entities than those shown in FIG. 1.

[0026] The example embodiments described herein are not, however, restricted to the wireless communication network given as an example but a person skilled in the art may apply the example embodiments described herein to other wireless communication networks provided with necessary properties.

[0027] The example wireless communication network shown in FIG. 1 includes a radio access network (RAN) and a core network 110.

[0028] FIG. 1 shows user equipment (UE) 100, 102 configured to be in a wireless connection on one or more communication channels in a radio cell with an access node 104 of a radio access network.

[0029] The access node 104 may comprise a computing device configured to control the radio resources of the access node 104 and to be in a wireless connectionwith one or more UEs 100, 102. The access node 104 may also be referred to as a base station, a base transceiver station (BTS), an access point, a cell site, a network node, a radio access network node, a RAN node, or a network device.

[0030] The access node 104 may be, for example, an evolved NodeB (abbreviated as eNB or eNodeB), or a next generation evolved NodeB (abbreviated as ng-eNB), or a next generation NodeB (abbreviated as gNB or gNodeB), providing the radio cell. The access node 104 may include or be coupled to transceivers. From the transceivers of the access node 104, a connection may be provided to an antenna unit that establishes a bi-directional radio link to one or more UEs 100, 102. The antenna unit may comprise an antenna or antenna element, or a plurality of antennas or antenna elements.

[0031] The wireless connection (e.g., radio link) from a UE 100, 102 to the access node 104 may be called uplink (UL) or reverse link, and the wireless connection (e.g., radio link) from the access node 104 to the UE 100, 102 may be called downlink (DL) or forward link. A UE 100 may also communicate directly with another UE 102, and vice versa, via a wireless connection generally referred to as a sidelink (SL). It should be appreciated that the access node 104 or its functionalities may be implemented by using any node, host, server, access point or other entity suitable for providing such functionalities.

[0032] The radio access network may comprise more than one access node 104, in which case the access nodes may also be configured to communicate with one another over wired or wireless links. These links between access nodes may be used for sending and / or receiving control plane signaling and also for routing data from one access node to another access node.

[0033] The access node 104 may further be connected to a core network (CN) 110. The core network 110 may comprise an evolved packet core (EPC) network and / or a 5thgeneration core network (5GC). The EPC may comprise network entities, such as a serving gateway (S-GW for routing and forwarding data packets), a packet data network gateway (P-GW) for providing connectivity of UEs to external packet data networks, and / or a mobility management entity (MME). The 5GC may comprise one or more network functions, such as at least one of: a user plane function (UPF), an access and mobility management function (AMF), a location management function (LMF), and / or a session management function (SMF).The core network 110 may also be able to communicate with one or more external networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them. For example, in 5G wireless communication networks, the UPF of the core network 110 maybe configured to communicate with an external data network via an N6 interface. In LTE wireless communication networks, the P-GW of the core network 110 may be configured to communicate with an external data network.

[0034] It should also be understood that the distribution of functions between core network operations and access node operations may differ in future wireless communication networks compared to that of the LTE or 5G, or even be non-existent.

[0035] The illustrated UE 100, 102 is one type of an apparatus to which resources on the air interface may be allocated and assigned. The UE 100, 102 may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device, just to mention but a few names. The UE 100, 102 may be a computing device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of computing devices: a mobile phone, a smartphone, a personal digital assistant (PDA), a handset, a computing device comprising a wireless modem (e.g., an alarm or measurement device, etc.), a laptop computer, a desktop computer, a tablet, a game console, a notebook, a multimedia device, a reduced capability (RedCap) device, a wearable device (e.g., a watch, earphones or eyeglasses) with radio parts, a sensor comprising a wireless modem, or a computing device comprising a wireless modem integrated in a vehicle.

[0036] It should be appreciated that the UE 100, 102 may also be a nearly exclusive uplink-only device, of which an example may be a camera or video camera loading images or video clips to a network. The UE 100, 102 may also be a device having capability to operate in an Internet of Things (loT) network, which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction.

[0037] The wireless communication network may also be able to support the usage of cloud services. For example, at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by “cloud” 114). The UE 100, 102 mayalso utilize the cloud 114. In some applications, the computation for a given UE may be carried out in the cloud 114 or in another UE.

[0038] The wireless communication network may also comprise a central control entity, such as a network management system (NMS), or the like. The NMS is a centralized suite of software and hardware used to monitor, control, and administer the network infrastructure. The NMS is responsible for a wide range of tasks such as fault management, configuration management, security management, performance management, and accounting management. The NMS enables network operators to efficiently manage and optimize network resources, ensuring that the network delivers high performance, reliability, and security.

[0039] 5G enables using multiple-input and multiple-output (M1M0) antennas in the access node 104 and / or the UE 100, 102, many more base stations or access nodes than an LTE network (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and / or spectrum available. 5G wireless communication networks may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine-type applications, such as (massive) machinetype communications (mMTC), including vehicular safety, different sensors and realtime control.

[0040] In 5G wireless communication networks, access nodes and / or UEs may have multiple radio interfaces, such as below 6 gigahertz (GHz), centimeter wave (cmWave) and millimeter wave (mmWave), and also being integrable with legacy radio access technologies, such as LTE. Integration with LTE may be implemented, for example, as a system, where macro coverage may be provided by LTE, and 5G radio interface access may come from small cells by aggregation to LTE. In other words, a 5G wireless communication network may support both inter-RAT operability (such as interoperability between LTE and 5G) and inter-Rl operability (inter-radio interface operability, such as between below 6GHz, cmWave, and mmWave).

[0041] 5G wireless communication networks may also apply network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same physical infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.5G may enable analytics and knowledge generation to occur at the source of the data. This approach may involve leveraging resources that may not be continuously connected to a network, such as laptops, smartphones, tablets and sensors. Multi-access edge computing (MEC) may provide a distributed computing environment for application and service hosting. It may also have the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing may cover a wide range of technologies, such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0042] In one embodiment, an access node 104 may comprise: a radio unit (RU) 103 comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105 that may be used for the so-called Layer 1 (LI) processing and real-time Layer 2 (L2) processing; and a central unit (CU) 108 (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU 108 may be connected to the one or more DUs 105 for example via an Fl interface. Such an embodiment of the access node 104 may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites. The CU and DU together may also be referred to as baseband or a baseband unit (BBU). The CU and DU may also be comprised in a radio access point (RAP).

[0043] The CU 108 may be a logical node hosting radio resource control (RRC), service data adaptation protocol (SDAP) and / or packet data convergence protocol (PDCP), of the NR protocol stack for an access node 104. The CU 108 may comprise a control plane (CU-CP), which may be a logical node hosting the RRC and the control plane part of the PDCP protocol of the NR protocol stack for the access node 104. The CU 108 may further comprise a user plane (CU-UP), which may be a logical nodehosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node 104.

[0044] The DU 105 may be a logical node hosting radio link control (RLC), medium access control (MAC) and / or physical (PHY) layers of the NR protocol stack for the access node 104. The operations of the DU 105 may be at least partly controlled by the CU 108. It should also be understood that the distribution of functions between the DU 105 and the CU 108 may vary depending on the implementation.

[0045] Cloud computing systems may also be used to provide the CU 108 and / or DU 105. A CU provided by a cloud computing system may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) provided by a cloud computing system. Furthermore, there may also be a combination, where the DU may be implemented on so-called bare metal solutions, for example applicationspecific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC).

[0046] Edge cloud may be brought into the radio access network by utilizing network function virtualization (NFV) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a computing system operationally coupled to a remote radio head (RRH) or a radio unit (RU) 103 of an access node 104. It is also possible that access node operations may be performed on a distributed computing system or a cloud computing system located at the access node 104. Application of cloud RAN architecture enables RAN real-time functions being carried out at the radio access network (e.g., in a DU 105), and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108).

[0047] 5G (or new radio, NR) wireless communication networks may support multiple hierarchies, where multi-access edge computing (MEC) servers may be placed between the core network 110 and the access node 104. It should be appreciated that MEC may be applied in LTE wireless communication networks as well.

[0048] A 5G wireless communication network (“5G network”) may also comprise a non-terrestrial communication network, such as a satellite communication network, to enhance or complement the coverage of the 5G radio access network. For example, satellite communication may support the transfer of data between the 5G radio access network and the core network 110, enabling more extensive network coverage. Possible use cases may include: providing service continuity for machine-to-machine(M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway, maritime, or aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, or low earth orbit (LEO) satellite systems, such as mega-constellations (i.e., systems in which hundreds of (nano) satellites are deployed). Alternatively, the satellites may be an airborne devices, such as an unmanned aerial vehicle (UAV), or a high-altitude platform system (HAPS). A given satellite 106 may provide communication services on Earth via one or more satellite beams. The one or more satellite beams create one or more cells over a given service area that may be bounded by the field of view of the satellite 106.

[0049] It is obvious for a person skilled in the art that the access node 104 depicted in FIG. 1 is just an example of a part of a radio access network, and in practice the radio access network may comprise a plurality of access nodes 104, the UEs 100, 102 may have access to a plurality of radio cells, and the radio access network may also comprise other apparatuses, such as physical layer relay access nodes or other entities. At least one of the access nodes may be a Home eNodeB or a Home gNodeB. A Home gNodeB or a Home eNodeB is a type of access node that may be used to provide indoor coverage inside a home, office, or other indoor environment.

[0050] Additionally, in a geographical area of a radio access network, a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The access node(s) 104 of FIG. 1 may provide any kind of these cells. A cellular radio network may be implemented as a multilayer access networks including several kinds of radio cells. In multilayer access networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be needed to provide such a multilayer access network.

[0051] For fulfilling the need for improving performance of radio access networks, the concept of “plug-and-play” access nodes may be introduced. A radio access network, which may be able to use “plug-and-play” access nodes, may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway (HNB-GW) (not shown in FIG. 1). An HNB-GW, which may be installed within an operator’s radio access network, may aggregate traffic from a large number of Home eNodeBs or HomegNodeBs back to a core network 110 of the operator.

[0052] 6G wireless communication networks are expected to adopt flexible decentralized and / or distributed computing systems and architecture and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short-packet communication and blockchain technologies. Key features of 6G may include intelligent connected management and control functions, programmability, integrated sensing and communication, reduction of energy footprint, trustworthy infrastructure, scalability and affordability. In addition to these, 6G is also targeting new use cases covering the integration of localization and sensing capabilities into system definition to unifying user experience across physical and digital worlds.

[0053] It is envisaged that 7G, which will succeed the 5G and 6G technologies, will be able to satisfy the requirements of extremely high bandwidth, almost zero latency, and universal integration.

[0054] Some example embodiments are described below using principles and terminology of 5G radio access technology without limiting the example embodiments to 5G radio access technology, however.

[0055] Channel state information (CS1) measured by terminal devices and reported to network is used in communication systems to help to control downlink transmissions. To meet the requirements of users, many transmission schemes such as coding, adaptive modulation and channel-aware scheduling, for example, need accurate CS1 to achieve a significant gain in the downlink or / and uplink direction. Thus, obtaining accurate CS1 is important.

[0056] Typically, the channel between a network node and terminal device is estimated by the terminal device from a reference signal, such as a channel state information reference signal (CS1-RS) transmitted by the network node. The reference signal may comprise pilot or reference signals or symbols which may be periodic, semi-persistent or aperiodic.

[0057] In an embodiment, the terminal device performs a set of various measurements from the CS1-RS and reports measurement results to the network node. The terminal device may measure for example the following: channel quality indicator (CQ1), precoding matrix indicator (PM1), rank indicator (Rl), layer indicator (LI),channel impulse or frequency response, measurement, doppler shift and timevariation, delay spread, channel delay, and beam quality, such as reference signal received power (RSRP), interference, signal to interference ratio (S1NR), and beam index or resource indicator, such as CS1-RS resource indicator (CR1), of the cell served by the network node.

[0058] In situations where a terminal device makes a handover or switches from a non-connected or low-power mode / state, such as INACTIVE or IDLE state / mode (or also known as Radio Resource Connection (RRC) 1NAC1VE or RRC IDLE), to a connected state / mode, i.e., when there is no prior knowledge of channel conditions for the terminal device it would be advantageous if CS1 were available as quickly as possible. This applies especially if the terminal device is performing a Layer 1 / 2 triggered mobility (LTM) or cell switch procedure based on Layer 3 (L3) handover or any other cell switch procedure which may be based on procedures performed at one or more layers (LI, L2, L3). LTM refers to a specific cell switch method where information from the lower layers (Layer 1 -Physical Layer- and Layer 2 -Data Link Layer or Medium Access Control Layer) is used to assist and optimize some mobility management procedures, such as handovers. Acquiring CS1 from a target or candidate cell and reporting the measurements to the target or candidate cell would reduce the need of additional measurements for CS1 acquisition in the target or candidate cell for initial transmissions and receptions.

[0059] In prior art, when a terminal device reports CS1 measurements using uplink control information (UC1), the terminal device is typically given a computation time, denoted as CS1 computation time (Z’), between a measurement occasion or measurement RS occasion, which refers to the timing of the measurement RS transmission / reception which can be used for CS1 measurement, and the associated uplink reporting instance. This computation time allows the terminal device to perform the measurement and compute the CS1. If the required computation time is not available, the terminal device is allowed to omit the report. For example, in aperiodic CS1 reporting with aperiodic CS1-RS, the terminal device is not required to report CS1 if the time between the downlink control information (DC1) triggering the aperiodic report and the reporting slot is less than given time Z, or the time between the CS1-RS resource and the reporting slot is less than Z’.

[0060] For Layer 1-based UC1 reporting, it is important for the network to knowwhen a CSI report is expected so that blind detection may be avoided. Typically, with known measurement occasions, CSI computation time, and reporting slots, the network can determine when a report will be sent and when it will be omitted.

[0061] However, in the case of LTM or any cell switch procedure, when the terminal device only starts measurements or measurements to acquire CSI or CSI measurements after receiving or / and applying a cell switch command triggering a cell switch to a target cell, the target cell may not have prior knowledge of the exact timing of the command or may not have knowledge of the timing of the cell switch command with respect to the timing of measurement RS occasion(s) which can be used for CSI measurements. Consequently, it may not be able to determine whether a measurement occasion occurred before or after the cell switch command, making it difficult to predict whether a CSI report will be available in the first uplink transmission. The first uplink transmission in this case of cell switch procedure may refer to the uplink transmission where the terminal device sends a confirmation message to the target cell about the successful cell switch, such as RRC Reconfiguration Complete message. In some scenarios, this may be sent using a configured grant (RRC configured uplink grant(s)) allocated to the UE for cell switch to send this confirmation message, such as RRC Reconfiguration Complete message, especially when the cell switch is a Random Access Channel (RACH)-less cell switch, meaning that there is no RACH procedure performed after the reception of the cell switch command to connect to the target cell. In some scenarios, this may be sent using a dynamic grant (RRC configured uplink grant(s)) allocated to the UE for cell switch to send this confirmation message, such as RRC Reconfiguration Complete message. A dynamic grant may be allocated by the target cell directly, for example using a downlink control message or any other control command such as MAC CE, for a RACH-less cell switch. In some scenarios a dynamic grant may be allocated by the target cell directly, during the RACH procedure, for example in the message 2 (or Random Access Response or MSG2 or a message containing a timing advance (TA) information for the target / candidate cell) when the UE performs a RACH procedure to connect to the target cell. In some scenarios such RACH procedure may be performed before the cell switch command is triggered by the source cell, for early TA acquisition, wherein the TA can be provided to the UE in a message directly sent by the candidate / target cell or a message (e.g., such a MAC Control element (MAC CE)) sent by the source cell. When the UE performs a RACH procedure to connect to thetarget cell during the handover or after receiving the cell switch command, the first uplink transmission may refer to the transmission of message 3. In some scenario the first uplink transmission may refer to the transmission of message sent by the UE after the completion of the RACH procedure, such as message 5.

[0062] FIG. 2 illustrates a flow chart according to an example embodiment of a method for an apparatus. The method may be performed by an apparatus depicted in FIG. 9, for example. In an embodiment, the apparatus may be a terminal device, user equipment or a part of a terminal device, user equipment.

[0063] In step 200, the apparatus is configured to receive from a network node a configuration message, configuring the apparatus to report or measure and report CS1 (or CS1 measurements or CS1 related measurements) of one or more cells or candidate cells, said configuration comprising information on at least one of a set of measurement RSs, such as providing the configuration of RSs which can be used for measurements, and a set of measurements to be reported, such as report quantity or report quantities, for the one or more candidate cells.

[0064] In an embodiment, the configuration message may be a RRC (re-) configuration message. In case of cell switch, it may be a cell switch or handover configuration message where the configuration of one or more candidate cells is provided for the cell switch procedure. In case of when the apparatus is switching from a non-connected mode to a connected mode, it may be RRC Resume or RRC suspension or a message containing a part of the system information. Such configuration may contain the information of RS and associated configuration to be used for CS1 measurements or / and reporting configuration which may provide at least the information about the RSs to be measured to acquire the CS1 or / and reporting quantities (such as CQ1, PM1, Rl, etc.). In some scenarios when the reporting quantity is fixed / predefined, it may not be indicated in the reporting configuration. In some scenarios, the configuration message may contain the indication for which candidate cell(s) the reporting (or measurement and reporting) of CS1 is enabled. This may be needed when only certain candidate cell(s) are configured for early CS1 reporting. In some cases, each candidate cell may indicate whether it allows the early CS1 reporting, during the handover preparation phase when the handover configuration is prepared which then later provided to the terminal device.In step 202, the apparatus is configured to determine that at least one of the measurements of the set of measurements to be reported is invalid or unavailable at a reporting occurrence for one or more of the candidate cells.

[0065] The measurements may be invalid or unavailable when for example the apparatus does not have sufficient / minimum time between the measurements RS occasion and the time when the reporting is performed, where the sufficient / minimum time may be defined based on the CSI computation time the terminal device is expected to take to measure or / and compute the configured CSI or measurement which need to be reported.

[0066] In step 204, the apparatus is configured to determine a continuation of measuring and reporting based on the configuration message or / and the determination that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

[0067] In some scenarios, the apparatus is configured to determine a continuation of computing when the measurements have already been performed but the CSI has not been computed fully yet or measuring and computing, and reporting based on the configuration message or / and the determination that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

[0068] In an embodiment, the apparatus is configured to continue measurements or / and compute as configured and transmit the measurement results to the network in a next available granted transmission resource. The next available granted resource may be a configured grant, for example configured in the RRC configuration, or a grant provided dynamically (e.g., via downlink control message or any other control command) by the target node / cell.

[0069] In an embodiment, the apparatus is configured to stop measurements or / and compute and does not transmit the measurement results to the network.

[0070] In an embodiment, the apparatus is configured to receive (or for control reception) from a source cell of a message to perform a handover from the source cell to a target cell wherein the target cell is one of the candidate cells and perform channel state information measurements of the target cell and reporting to the target cell.

[0071] In an embodiment, the handover is a Layer 1 / 2 triggered handover.In an embodiment, the apparatus is configured to switch from a nonconnected or a low-power state to a connected state in a target cell wherein the target cell is one of the candidate cells and perform channel state information measurements of the target cell and reporting to the target cell.

[0072] FIG. 3 illustrates a flow chart according to an example embodiment of a method for an apparatus. The method may be performed by an apparatus depicted in FIG. 9, for example. In an embodiment, the apparatus may be a terminal device, user equipment or a part of a terminal device, user equipment.

[0073] In step 300, the apparatus is configured to receive from a network node a configuration message configuring the apparatus to report or measure and report CSI (or CSI measurements or CSI related measurements) of one or more cells or candidate cells, the configuration comprising at least one of configuration information of a set of measurement reference signals and a set of measurements to be reported for the one or more of the candidate cells.

[0074] In an embodiment, the configuration message may be a RRC (re-) configuration message. In case of cell switch, it may be a cell switch or handover configuration message where the configuration of one or more candidate cells is provided for the cell switch procedure. In case of when the apparatus is switching from a non-connected mode to a connected mode, it may be RRC Resume or RRC suspension or a message containing a part of the system information. Such configuration may contain the information of RS and associated configuration to be used for CSI measurements or / and reporting configuration which may provide at least the information about the RSs to be measured to acquire the CSI or / and reporting quantities (such as CQI, PMI, RI, etc.).

[0075] In some scenarios when the reporting quantity is fixed / predefined, it may not be indicated in the reporting configuration. In some scenarios, the configuration message may contain the indication for which candidate cell(s) the reporting (or measurement and reporting) of CSI is enabled. This may be needed when only certain candidate cell(s) are configured for early CSI reporting. In some cases, each candidate cell may indicate whether it allows the early CSI reporting, during the handover preparation phase when the handover configuration is prepared which then later provided to the terminal device.

[0076] In step 302, the apparatus is configured to measure channel stateinformation for at least one of the candidate cells; said measurement comprising a set of measurements. The apparatus is configured to measure channel state information for reporting or based on the reporting configuration.

[0077] In step 304, the apparatus is configured to determine that at least one measurement of the set of measurements to be reported is valid or available at a reporting occurrence for the at least one candidate cell.

[0078] The measurements may be valid or available when for example the apparatus has sufficient / minimum time between the measurements RS occasion and the time when the reporting is performed, where the sufficient / minimum time may be defined based on the CS1 computation time the terminal device is expected to take to measure or / and compute the configured CS1 or measurement which need to be reported. In other words, the measurements may be valid or available when for example the apparatus has successfully measured or / and computed the configured / predefined CS1 for reporting.

[0079] In step 306, the apparatus is configured to send a report to the at least one candidate cell, said report comprising the at least one measurement of the set of measurements determined to be valid or available.

[0080] In an embodiment, the apparatus is configured to determine that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence. The measurements may be invalid or unavailable when for example the apparatus does not have sufficient / minimum time between the measurements RS occasion and the time when the reporting is performed, where the sufficient / minimum time may be defined based on the CS1 computation time the terminal device is expected to take to measure or / and compute the configured CS1 or measurement which need to be reported.

[0081] In an embodiment, the report comprises information on the at least one of the measurements of the set of measurements that are invalid or unavailable at the reporting occurrence. In some scenarios, the apparatus may send the status information indicating validity or availability of at least one of the measurements of the set of measurements. In some scenarios, the apparatus may send the status information indicating validity or availability of at least one of the measurements of the set of measurements at the reporting occurrence. In some scenarios, the apparatus may send the information that the at least one of the measurements of the set ofmeasurements is invalid or unavailable may be sent separately from the report.

[0082] In an embodiment, the report comprises an indication indicating at least one of: existence of at least one valid measurement of the set of measurements that is determined to be valid, the measurements of the set of measurements that are valid or available and included in the report, or status of the set of measurements wherein the status may indicate the information about the validity or availability of the measurements.

[0083] FIG. 4 illustrates a flow chart according to an example embodiment of a method for an apparatus. The method may be performed by an apparatus depicted in FIG. 10, for example. In an embodiment, the apparatus may be a base station, a transmission point or a part of a base station or a transmission point. The apparatus may also be another network element.

[0084] In step 400, the apparatus is configured to transmit a configuration message to a terminal device, the message comprising configuration for the terminal device to measure channel state information of one or more candidate cells, the configuration comprising a configuration information of a set of measurement reference signals or / and a set of measurements to be made for the one or more of the candidate cells ; determine that at least one channel state information measurement is invalid or unavailable at a reporting occurrence for one or more of candidate cells; continue to stop measuring and reporting based on the configuration message and the determination for the one or more candidate cell.

[0085] In an embodiment, the apparatus is configured to control transmission of a cell change message to perform a handover from the cell served by the apparatus to a target cell.

[0086] FIG. 5 illustrates a flow chart according to an example embodiment of a method for an apparatus. The method may be performed by an apparatus depicted in FIG. 10, for example. In an embodiment, the apparatus may be a base station, a transmission point or a part of a base station or a transmission point. The apparatus may also be another network element.

[0087] In step 500, the apparatus is configured to transmit a channel state information reference signal.In step 502, the apparatus is configured to receive a report from a terminal device, the report comprising status of the channel state information measurement the terminal device is configured to perform.

[0088] In an embodiment, the apparatus is configured to receive the report in the first uplink transmission from the terminal device after the terminal device has made a handover to the cell served by the apparatus or after the terminal device has switched from a non-connected or a low-power state to a connect state.

[0089] FIG. 6 illustrates a flow chart according to an example embodiment of a method for an apparatus. The method may be performed by an apparatus depicted in FIG. 10, for example. In an embodiment, the apparatus may be a base station, a transmission point or a part of a base station or a transmission point. The apparatus may also be another network element.

[0090] In step 600, the apparatus is configured to transmit a measurement reference signal.

[0091] In step 602, the apparatus is configured to receive a channel state information measurement report from a terminal device, the report comprising the at least one measurement of the set of measurements the terminal device determined to be valid or available.

[0092] In an embodiment, the apparatus is configured to receive status of channel state information measurement as an uplink control information, in a Medium Access Control Control Element or encoded in Radio Resource Configuration information, the status indicating whether measurement is at least in part valid or invalid. In an embodiment, the apparatus is configured to receive status of channel state information measurement as part of the CSI report (or report containing at least one measurement) as an uplink control information, in a Medium Access Control Control Element or encoded in Radio Resource Configuration information, the status indicating whether measurement is at least in part valid or invalid

[0093] A terminal device is typically provided with RRC configurations for periodic CSI-RS resource(s) and CSI report(s) for one or more candidate cells for a target cell of the cell switch. The configuration message may be a separate message from the source cell, the configuration message may be a cell switch configuration, or it may be transmitted by the source cell in connection with the cell switch command, in which case the target cell is known. After the terminal device has received the informationregarding CSI-RS configuration it may start measurements. The measurements take a given computation time. To speed up the process in the target cell, it would be advantageous if the terminal device could send the measurement results in the first uplink message to the target cell, for example by multiplexing the measurement data in the first physical uplink shared channel (PUSCH) occasion. However, as mentioned above, depending on the time instant when the terminal device obtained information enabling it to perform measurements, it is not always guaranteed that a measurements report could be made in time before the first uplink transmission and the target cell is unaware of the situation.

[0094] In an embodiment, the terminal device may provide the target cell information or a status message whether the measurements are valid or invalid, or available or unavailable. In an embodiment, the status message may be sent in the first uplink message to the target cell with the measurement report. The measurement report may comprise valid results or not. The status message may indicate which measurements are valid and which invalid, for example.

[0095] FIG. 7 is a signaling chart illustrating some example embodiments for a cell switch scenario. The chart illustrates examples of signaling between a terminal device 700, a source distributed unit (DU) 702 serving the source cell, a source a central unit (CU) 702 and target distributed unit 706 serving the target cell.

[0096] The terminal device 700 transmits a Measurement Report message 708 to the Source DU 702.

[0097] The source DU 702 transmits an RRC message 710 with the measurement report to the Source CU 704.

[0098] The source CU decides to configure LTM and initiates LTM preparation 712, including determining the LTM candidate configurations, configuration of CSI-RS signals.

[0099] The source CU transmits an RRCReconfiguration message 714 to the terminal device 700 including the LTM candidate configurations and configuration of CSI-RS signals for CS1 measurements which may include configuration information of measurement RSs or / and one or more reporting configuration, each associated with a set of measurement RSs, and also to indicate what to report based on the measurements.

[0100] The terminal device 700 stores the LTM candidate configurations andtransmits an RRCReconfigurationComplete message 716 to the source CU 704.

[0101] The terminal device is configured to perform Layerl measurements on the configured candidate cell(s) and transmit the LI measurement reports 718 to the source DU 702.

[0102] The source DU decides to execute cell switch to a target cell and transmits a cell switch command MAC Control Element (MAC CE) 720 triggering cell switch by including the candidate configuration index of the target cell. The terminal device switches to the target cell and applies the configuration indicated by candidate configuration index.

[0103] The terminal device receives CS1-RS signal 722 transmitted by the target DU 706 as configured. In another example, such CS1-RS may also be transmitted before the cell change 720 and the terminal device may measure them before.

[0104] In an embodiment, when the time gap between the cell switch and the first reporting occurrence, i.e. the first PUSCH transmission to the target cell is greater than a given or predefined duration, or / and the time gap between the CS1-RS signal 722 and the and the first reporting occurrence is greater than a given or predefined duration, the terminal device has enough time to perform measurements and compute the CS1 724 before the first PUSCH transmission (using configured grant (CG) in CG based RACH-less cell switch or MSG3 in RACH-based cell switch, for example). In this scenario the terminal device 700 sends a CS1 report 726 with the proposed format with status indication indicating that a valid CS1 report is multiplexed.

[0105] In an embodiment, the time gap between the cell switch and the first reporting occurrence, i.e., the first PUSCH transmission to the target cell may be smaller than the given or predefined duration or / and the time gap between the CS1-RS signal 722 and the and the first reporting occurrence is smaller than a given or predefined duration. The terminal device may perform some measurements 724 as time permits and transmit 726 CS1 report with the proposed format with status indication indicating that no valid CS1 report is multiplexed or at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence. After that, the terminal device may keep computing the CS1 and send it in next available granted transmission resource if this is a CG based RACH-less cell switch), keep computing the CS1, and monitor for a downlink control information providing an uplink grant to send the CS1 report, or stop measuring or / and computing the CS1.The proposed solution has many advantages. For example, it allows efficient early CS1 reporting to the target cell based on the status of the CS1 measurements. The procedures applied at the terminal device are based on the CS1 status indication. Further, it provides simple rules to determine CS1 status indication.

[0106] Let us next study some embodiments where different CS1 status indications are utilized. As mentioned above, when the UE is configured with an early CS1 reporting configuration to perform early CS1 measurements for a cell or when the UE is configured with the information of measurement RSs (CSl-RSs) or / and indication to perform CS1 measurements for a cell, it may be configured to indicate the status the CS1 measurement report associated with the CS1 reporting to the cell. The cell may be a candidate / target cell for mobility (in connection with LTM, for example) or the target cell for the CS1 measurement report such as the serving cell or any other cells UE connects to (in connection with other scenarios such as when the UE performs measurements during inactive / idle mode or before the UE switches to the connected mode). In some cases, the UE may be configured with CS1 reporting quantities (e.g., one or more of CR1, CQ1 Rl, PM1, LI, etc.) to be reported. In some cases, what CS1 needs to be computed or / and reported may be predefined.

[0107] In an embodiment, the CS1 measurement status indication may be encoded as part of the CS1 report or measurement report (e.g., layer 1 or layer 3 measurement report) sent to the target cell.

[0108] In an embodiment, the CS1 measurement status indication may be encoded as part of the CS1 report sent to the target cell using uplink control information (UC1) format or sent in the UC1 container or sent in the LI control container or encoded as the UC1 or encoded as the UC1 format or encoded as the layer 1 measurement reporting.

[0109] In an embodiment, the status indication may specify whether the CS1 measurement report contains at least one measurement or at least one valid measurement. The status indication may be represented as a bit field. If the bit field is set to 0, it indicates that no valid measurement is available for at least one of the reported measurement quantities. If the bit field is set to 1, it indicates that all reported measurement quantities are valid. In this case, the network may decode and utilize one or more reported measurement quantities.In an embodiment, if the bit field is set to 1, it indicates that at least one reported measurement quantity is valid. For the quantities that are included in the report but are not valid, the measured value may be set to predefined value(s), for example. For example, when to indicated that CQI is invalid it is set to a value with all zeros.

[0110] In an embodiment, the status indication may be a field of multiple bits. The field may indicate the CSI report configuration identification (ID) for which status of CSI measurements is associated. This may be used when one or more CSI report configurations, each with a unique ID, are configured for the cell (or candidate or target cell) or for all configured cells (or candidate cells). The field may indicate reporting configuration Identifier referring to the RRC configured identifier. A codepoint may be used which can be mapped to the list of reporting configuration IDs, e.g. in ascending order of the IDs (codepoint value 00 = reporting ID#1, codepoint value 01 = reporting ID#2 etc.). In an embodiment, the reporting configuration bit fields may refer to reporting configurations specific to the cell, e.g., configured for the cell.

[0111] In an embodiment, the length of the bit field may be based on the total number of report configurations associated with the cell or the candidate cell or the target cell associated with the report.

[0112] In an embodiment, the length of the bit field may be based on the total number of report configurations associated with all the configured cells or candidate cells. This option may be used when the report configurations are configured as a common configuration across all candidate cells. For example, for LTM, this may be provided in LTM-Config (outside of or not within any specific candidate related configuration), applicable for all LTM candidates

[0113] In an embodiment, the status indication may be conveyed by setting one or more of the measurement quantities to a predefined value(s). For example, when one or more from RI or CQI or PMI or CRI can be set to specific values to indicate the status of the measurements. For example, when the CQI is set all zeros, then it may indicate the invalid or unavailability related status.An example of encoding of the one bit bitfield in UCI format:

[0114] CSI report number CSI fields

[0115] Bit field = 0 or 1

[0116] CSI report # CRI if reported

[0117] Rank Indicator if reported

[0118] Layer indicator if reported

[0119] Zero padding bits if needed

[0120] PMI if reported

[0121] Wideband CQI if reported

[0122]

[0123] In an example embodiment, the status information indication may be an UCI format (e.g., a new UCI) comprising of one bit or multi-bit bit CSI indication. The one bit UCI format may be a part of a two stage UCI reporting where the one bit UCI format is separately encoded from the CSI report, for example. If it indicates a of one (value =1), the terminal device will multiplex the CSI report on the same PUSCH message, which may indicate that report is available or valid. The CSI report is separately channel coded. If the value indicates zero (value =0), the UCI report (or CSI report using the UCI format) is not multiplexed in the same grant. Which may indicate that report is not available or not valid. The resource can be assumed then to be used for data (other data) when decoding. The above numerical values and actions are merely an illustrative example.

[0124] In an example embodiment, the status information indication may be an UCI format (e.g., a new UCI) comprising of one bit or multi-bit bit CSI indication, and the CSI report comprising the one or more measurement results may be sent in UCI, MAC CE or RRC format / container. If it indicates a of one (value =1), the terminal device will multiplex / send the CSI report on the same PUSCH message. Which may indicate that report is available or valid. If the value indicates zero (value =0), the CSI report is not multiplexed / send in the same grant.

[0125] Above CSI indication may be independently encoded (channel coded) and multiplexed to the PUSCH with highest priority when it is multiplexed to the firstPUSCH. In an embodiment, the CSI indication has dedicated resource element location in the allocated PUSCH resources when it is multiplexed to the first PUSCH.

[0126] In an embodiment, the status information indication is encoded in a L2 control command such as a MAC CE. The status information may be indicated in the MAC CE together with the report (CSI report comprising the measurement results) or alone without the report (CSI report comprising the measurement results). The report may be conditional to whether the measurements are valid or available. When the report is available or valid or when the status indication indicates that report is available or valid, the CSI report comprising one or measurement results may be sent in UCI or MAC CE or RRC format.

[0127] In an embodiment, when the status indication of the CSI measurement report is indicated by the MAC CE, the CSI indication MAC CE may comprise a header field, a logical channel (LCID) or extended LCID (eLCID) field, set to a specific / predefined / specified value. In an embodiment, when the terminal device determines to indicate that it has measurements to be reported or available, it multiplexes the CSI indication MAC CE (comprising LCID or extended LCID (e)LCID).

[0128] In an embodiment, this MAC CE may comprise only LCID and has fixed length (of zero octets). The MAC CE header may be an LCID or eLCID.

[0129] In an example embodiment, if the terminal device determines that is has no CSI measurements available or the measurements are not valid, it does not multiplex / include the CSI indication MAC CE to the uplink grant.

[0130] In an embodiment, separate values for LCID or eLCID may be used to indicate when the measurements are available / reported / valid (LCID / eLCID set to a first value) and when the when the measurements are unavailable / not reported / in valid (LCID / eLCID setto a second value). In an embodiment, when the terminal device determines to indicate that it has measurements to be reported or available, it multiplexes the CSI indication MAC CE (comprising LCID or extended LCID (e)LCID) using the first value. In an embodiment, when the terminal device determines to indicate that it does not have measurements to be reported or available, it multiplexes the CSI indication MAC CE (comprising LCID or extended LCID (e)LCID) using the second value.

[0131] FIG. 8A illustrates an example of a report configuration ID.

[0132] In an embodiment, the CSI indication MAC CE may further comprise a fieldsuch as an octet indicating the at least reporting configuration ID for which the measurements are available. The report config ID field may indicate the CS1 report config ID for which the CS1 measurements are available. The field may have N bits, where N= 1,2, 3, 4, ...m for example. The value of N may also be fixed. This may be used when one or more CS1 report configurations, each with a unique ID, are configured for the cell or for all configured cells.

[0133] The report config ID field may indicate reporting configuration Identifier referring to the RRC configured identifier. The report config ID field may also indicate a codepoint mapping to the list of reporting configuration IDs, for example in ascending of the IDs. (codepoint value 00 = reporting 1D#1, codepoint value 01 = reporting 1D#2 etc.). In an embodiment, the reporting configurations may refer to the reporting configurations configured per candidate cell and the length of the bit field may be based on the total number of report configurations associated with the candidate cell / target cell associated with the report. In another embodiment, the reporting configurations may refer to the reporting configurations configured for all candidate cells, and the length of the bit field may be based on the total number of report configurations associated with all the configured cells or candidate cells. This option may be used when the report configurations are configured as a common configuration across all candidate cells. For example, for LTM, this may be provided in LTM-Config (outside of or not within any specific candidate related configuration), applicable for all LTM candidates

[0134] FIG. 8B illustrates an example of a report configuration IDs in a bitmap. In an embodiment, the CS1 availability for one or more report config IDs may be indicated in the MAC CE and the indication may be in a form of a bitmap. Each bit field may map to the CS1 reporting configuration ID (for example in an ascending order of the configuration ID to the bit positions). The bit fields may be labelled in this example as RIDI, RID2 ... RiDn as illustrated in FIG. 8B.

[0135] In an embodiment, when the bit for the certain bit position is set to the first value (RID=0, for example), it indicates that the terminal device does not have CS1 measurements available for the reporting configuration ID associated with the bitfield. When the bit for the certain bit position is set to the second value (RID=1, for example), it indicates that the terminal device has CS1 measurements available for the reporting configuration ID associated with the bitfield. If the number of reporting configurationsare less than the length of the bitmap, the unmapped bit positions are set to pre-defined value, such as 1 / 0 or ignored. The bit map may have length of N bits, N= 1,2, 3, 4..., for example.

[0136] In an embodiment, the status information indication maybe encoded in RRC or as the RRC format or in the RRC container. The status information may comprise a status indication only, or status indication together with reporting. It may be encoded as a RRC information or as a Abstract Syntax Notation One (ASN.l) message. The status information may be associated with the report configuration identifier. One bit indication may be used as part of the RRC message, for instance RRCReconfiguration message to indicate whether a CS1 report or valid CS1 report is available. An alternative is is that the status information is indicated as ENUM indicating the status of the CS1 measurement. The status may be indicated from the last CS1-RS or the status at the time of RRC / ASN.l message transmission. For example, measurement may be AVAILABLE, VALID, UNAVAILABLE, ONGOING, COMPUTING. When the status indication is not encoded as part of the CS1 report, the CS1 report comprising one or measurement results may be sent in UC1 or MAC CE or RRC format when the report is available or valid or when the status indication indicates that report is available or valid.

[0137] In an embodiment, the reporting occurrence for the status indication, with or without a report, may be the first uplink transmission to the target cell. The first UL transmission may be a first PUSCH transmission sent to the target cell, e.g., a configured grant or a dynamic grant. The first uplink transmission may be for an LTM / cell switch, in a configured grant, or a dynamic grant based PUSCH in RACH-less cell switch or a MSGA or MSG3 in RACH-based cell switch.

[0138] When the status indication is sent using a UC1 format, the first uplink transmission may also be a PUCCH transmission sent to the target cell - the configuration of PUCCH may be given to the terminal device in RRC as a part of the candidate cell configuration or cell switch configuration, for example.

[0139] In an embodiment, the status indication may be configured based on network configuration. For example, in the RRC configuration (such as cell switch or LTM configuration), it may be specified whether status indication is required or allowed. The configuration may be defined per report configuration, applied to a specific early CS1 measurement reporting configuration. In an embodiment, the configuration may be defined per candidate cell (e.g., configured in LTM-Candidateinformation element (IE)), applied to all early CS1 measurement reports associated with a given candidate cell.

[0140] In an embodiment, the configuration may be defined for all candidate cells (e.g., configured in LTM-Config IE), applied to all early CS1 measurement reports for all candidate cells.

[0141] When the configuration is defined for a candidate cell, it may be indicated that a reporting is not allowed to be sent in the first uplink transmission (e.g., configured grant for RACH-less cell switch), but the terminal device may be configured to send an indication in the first uplink whether a CS1 report or a CS1 report with one or more valid measurement results is available or not.

[0142] The CS1 status indication may also be dependent on terminal device capabilities. For example, the status indication may only be allowed or configured if the terminal device does not support CS1 measurements before the cell switch. In other words, the status indication may only be required if the terminal device only supports CS1 measurements after receiving the cell switch command. In other words, the status indication may only be required if the terminal device only performs CS1 measurements only for the target cell. In other words, the status indication may only be required if the terminal device only performs CS1 measurements only for the target cell after receiving the cell switch command.

[0143] In an embodiment, the CS1 status indication may also be dependent on terminal device capabilities. For example, the terminal device may indicate a capability whether it supports sending a CS1 status indication. Additionally, or optionally, the terminal device may indicate whether it supports a certain format (UC1, MAC CE, RRC) for sending a status indication. Additionally, or optionally, the terminal device may indicate whether it supports sending a status indication along with a measurement report.

[0144] In an embodiment, when the terminal device is configured with the abovedescribed CS1 reporting configuration to perform CS1 measurements for a cell, it may be required to determine the status of a CS1 report associated with the CS1 reporting configuration based on the following conditions or rules or specified procedures.

[0145] In an embodiment, if there is at least one measurement CS1-RS occasion or RS occasion or measurement occasion associated with the CS1 reporting configuration or associated with the configured CS1 measurements for a CS1 reporting after a certainpoint in time, such that the time gap between the measurement occasion and the reporting occurrence / slotis greater than a predefined or configured first duration, the terminal device shall report a valid measurement report or determines that a measurement report is available or valid. Otherwise, the terminal device may determine that a valid measurement is not available to report, or a valid measurement report is not available or the terminal device shall not report a measurement report. The status indication (as described above) may be used to indicate the presence of a valid measurement report. The first duration may be defined or configured based on the capability, of the terminal device, such as CS1 computation processing time, for example. In other words, if the reporting occurrence for the channel state information measurement reporting is located at a given time gap after the measurement time of the channel state information, the time gap being greater than a predefined or given first duration, the terminal device shall report a valid measurement report or determines that a measurement report is available or valid. Otherwise, the terminal device may determine that a valid measurement is not available to report, or a valid measurement report is not available or the terminal device shall not report a measurement report

[0146] The reporting occurrence / slot may refer to a first uplink transmission (first PUSCH or PUCCH) to the target cell or one of the symbols (first or last symbol) of the slot or the slot of PUSCH / PUCCH carrying the first uplink message (such as RRC Reconfiguration complete message in case of a cell switch scenario) or one of the symbols (firstor last symbol) ofthe slotor the slot of PUSCH / PUCCH defined / specified to carry the report. For example in connection with cell switch / LTM or a first uplink transmission after receiving the cell switch command MAC CE, which could be a configured grant or a dynamic grant in RACH-less cell switch or MSGA / MSG 3 when a RACH-based cell switch is performed. In some scenarios, a separate configured grant may be configured for sending (early) CS1 reporting, e.g., after the cell switch or when the UE is in the 1NACT1VE / 1DLE mode. The UE may use such configured grant to send the status indication or / and CS1 report.

[0147] The certain point in time may be defined as based on the timing of the application ofthe RRC configuration containing the CS1 reporting configuration and / or the CS1 measurement configuration associated with CS1 measurements. Alternatively, it may be based on the application of an activation command that activates CS1measurements, the transmission of RSs, or CSI reporting associated with CSI measurements. An activation command could be a Physical Downlink Control Channel (PDCCH) order triggering a RACH procedure associated with the cell for which the measurements are performed for CSI reporting, a TCI state activation / deactivation command associated with the cell for which the measurements are performed for CSI reporting, a MAC CE activating one or more semi-persistent CSl-RSs associated with the CSI reporting or associated with the cell for which the measurements are performed for CSI reporting. Further, it may also be based on the reception or the application of the cell switch command. This last option is applicable for example when the terminal device does not or may not support measurements before receiving the cell switch command.

[0148] In an embodiment, if there is no measurement RS occasion associated with the CSI reporting configuration after a certain point in time such that the time gap between the RS occasion and the reporting slot is greater than the first duration, the terminal device may omit the measurement report. However, the status indication may be sent to indicate that there is no valid measurement report.

[0149] In an embodiment, a second duration, which may be denoted as a maximum duration, may additionally or optionally be predefined or configured to control the age of the measurement. For example, if there is at least one measurement RS occasion associated with the CSI reporting configuration or associated with the configured CSI measurements for a CSI reporting after a certain point in time such that the time gap between the RS occasion and the reporting occurrence / slot is greater than the first duration but does not exceed the second duration, the terminal device may be configured to report a valid measurement report or determines that a measurement report is available or valid. Otherwise, the terminal device may be configured to omit the measurement report or the terminal device may determine that a valid measurement is not available to report or a valid measurement report is not available or the terminal device shall not report a measurement report. In other words, when the reporting occurrence for the channel state information measurement reporting is located a given time gap after the measurement time of channel state information, the time gap being greater than a predefined or given first duration but shorter than a predefined or given second duration, the terminal device may be configured to report a valid measurement report or determines that a measurement report is available orvalid. Otherwise, the terminal device may be configured to omit the measurement report or the terminal device may determine that a valid measurement is not available to report or a valid measurement report is not available or the terminal device shall not report a measurement report

[0150] In an embodiment, a third duration, which may be denoted as a minimum duration, may additionally or optionally be predefined or configured for the time gap between the CS1 triggering command and the reporting occurrence / slot. For example, if the time between the CS1 triggering command or after the reception or the application of the CS1 triggering command (e.g., RRC configuration containing, activation command activating CS1 measurements / transmission of CSl-RSs / CSl reporting, or, cell switch command) and the reporting slot is greater than a predefined or configured third duration, the terminal device may be configured to report a valid measurement report. Otherwise, the terminal device may be configured to omit the measurement report. The use of third duration may be combined with the condition based on the first duration. In an embodiment, the use of third duration may be combined with both the conditions based on the first duration and second duration.

[0151] For example, if there is at least one measurement RS occasion associated with the CS1 reporting configuration or associated with the configured CS1 measurements for a CS1 reporting after a certain point in time such that the time gap between the RS occasion and the reporting occurrence / slot is greater than the first duration but does not exceed the second duration, and if the time between the CS1 triggering command or after the reception or the application of the CS1 triggering command (e.g., RRC configuration containing, activation command activating CS1 measurements / transmission of CSl-RSs / CSl reporting, or, cell switch command) and the reporting occurrence / slot is greater than a predefined or configured third duration, the terminal device may be configured to report a valid measurement report or determines that a measurement report is available or valid. Another example, if there is at least one measurement RS occasion associated with the CS1 reporting configuration or associated with the configured CS1 measurements for a CS1 reporting after a certain point in time such that the time gap between the RS occasion and the reporting occurrence / slot is greater than the first duration, and if the time between the CS1 triggering command or after the reception or the application of the CS1 triggering command (e.g., RRC configuration containing, activation command activating CS1measurements / transmission of CSI-RSs / CSI reporting, or, cell switch command) and the reporting occurrence / slot is greater than a predefined or configured third duration, the terminal device may be configured to report a valid measurement report or determines that a measurement report is available or valid.

[0152] Let us discuss a situation, where the terminal device is configured with the above described CS1 reporting configuration to perform CS1 measurements for a cell (the target cell) and either omits the report or transmits the report with a status indication indicating no valid measurements or indicating unavailability of the measurements.

[0153] In an embodiment, the terminal device may monitor downlink control information from the target cell for an uplink grant to send a CS1 measurement report associated with the CS1 reporting configuration or associated with the configured CS1 measurements for a CS1 reporting. The terminal device may monitor downlink control information from the target cell for an uplink grant to send a CS1 measurement report associated with the CS1 reporting configuration or associated with the configured CS1 measurements for a CS1 reporting after sending the status indication indicating no valid measurements or indicating unavailability of the measurements.

[0154] In an embodiment, if configured, the terminal device may send the report in the next available configured grant (for example in the case of RACH-less LTM, where configured grants may be configured and used). Configured grant may be configured for RACH-less cell switches to send the first uplink message such as the RRC Reconfiguration Complete message. In some scenarios, a separate configured grant may be configured for sending (early) CS1 reporting, e.g., after the cell switch or when the UE is in the 1NACT1VE / 1DLE mode. The UE may use such configured grant to send the status indication or / and CS1 report.

[0155] Alternatively, the terminal device may stop performing measurements and / or stop processing or computing any measurement for a potential CS1 report associated with the CS1 reporting configuration. Thus, no further report is expected.

[0156] In an embodiment, the terminal device may be configured which option of the above to use. For example, this selection may be specified in the cell switch configuration and may apply commonly for all candidate cells, per candidate cell, or at the report configuration level.

[0157] FIGS.9, 10 and 11 illustrate embodiments. The figures illustrate a simplifiedexamples of apparatuses applying embodiments of the invention. It should be understood that the apparatus is depicted herein as an example illustrating some embodiments. It is apparent to a person skilled in the art that the apparatus may also comprise other functions and / or structures and not all described functions and structures are required. Although the apparatus has been depicted as one entity, different modules and memory may be implemented in one or more physical or logical entities.

[0158] Fig. 9 illustrates an example of an apparatus which may be a network element, a base station, (e / g)NodeB or a part of base station or (e / g)NodeB. The apparatus may serve a cell.

[0159] The apparatus may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above.

[0160] The apparatus of the example includes a control circuitry 900 configured to control at least part of the operation of the apparatus.

[0161] The apparatus may comprise a memory 902 for storing data. Furthermore, the memory may store software 904 executable by the control circuitry 000. The memory may be integrated in the control circuitry.

[0162] The apparatus may comprise one or more interface circuitries 906, 908. The interface circuitries are operationally connected to the control circuitry 900. An interface circuitry 906 may be a set of transceivers configured to communicate wirelessly with terminal devices or user equipment of a wireless communication network. The interface circuitry may be connected to an antenna arrangement (not shown). The apparatus may also comprise a connection to a transmitter instead of a transceiver. The apparatus may further comprise an interface 908 configured to communicate with other network elements such a core network or other corresponding apparatuses, for example a user interface.

[0163] In an embodiment, the software 904 may comprise a computer program comprising program code means adapted to cause the control circuitry 900 of the apparatus to realise at least some of the embodiments described above.

[0164] FIG.10 illustrates an example of an apparatus comprising means for causing the apparatus to perform one or more of the example embodiments described above. For example, the apparatus may be an apparatus such as, or comprising, or comprised in, a terminal device, a user equipment. The terminal device or user equipment mayalso be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, or a user device.

[0165] The apparatus may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above.

[0166] The apparatus of the example includes a control circuitry 1000 configured to control at least part of the operation of the apparatus.

[0167] The apparatus may comprise a memory 1002 for storing data. Furthermore, the memory may store software 1004 executable by the control circuitry 1000. The memory may be integrated in the control circuitry.

[0168] The apparatus may comprise one or more interface circuitries 1006, 1008. The interface circuitries are operationally connected to the control circuitry 1000. An interface circuitry 1006 may be a set of transceivers configured to communicate with a RAN node such as an (e / g)NodeB of a wireless communication network. The interface circuitry may be connected to an antenna arrangement (not shown). The apparatus may also comprise a connection to a transmitter instead of a transceiver. The apparatus may further comprise a user interface 1008.

[0169] In an embodiment, the software 1004 may comprise a computer program comprising program code means adapted to cause the control circuitry 1000 of the apparatus to realise at least some of the embodiments described above.

[0170] In an embodiment, as shown in Fig. 11, at least some of the functionalities of the apparatus of Fig. 9 may be shared between two physically separate devices, forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes. Thus, the apparatus of Fig. 11, utilizing such shared architecture, may comprise a remote control unit RCU 1100, such as a host computer or a server computer, operatively coupled (e.g. via a wireless or wired network) to a remote distributed unit RDU 1102 located in the (e / g)NodeB. In an embodiment, at least some of the described processes may be performed by the RCU 1100. In an embodiment, the execution of at least some of the described processes may be shared among the RDU 1102 and the RCU 1100.

[0171] In an embodiment, the RCU 1100 may generate a virtual network through which the RCU 1100 communicates with the RDU 1102. In general, virtual networking may involve a process of combining hardware and software network resources andnetwork functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization may be categorized as external virtual networking which combines many networks, or parts of networks, into the server computer or the host computer (e.g. to the RCU). External network virtualization is targeted to optimized network sharing. Another category is internal virtual networking which provides network-like functionality to the software containers on a single system. Virtual networking may also be used for testing the terminal device.

[0172] In an embodiment, the virtual network may provide flexible distribution of operations between the RDU and the RCU. In practice, any digital signal processing task may be performed in either the RDU or the RCU and the boundary where the responsibility is shifted between the RDU and the RCU may be selected according to implementation.

[0173] The blocks, related functions, and information exchanges (messages) described above by means of FIGS. 2 to 7 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other functions can also be executed between them or within them, and other information may be sent, and / or other rules applied. Some of the blocks or part of the blocks or one or more pieces of information can also be left out or replaced by a corresponding block or part of the block or one or more pieces of information.

[0174] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements. As used herein, the terms “the at least one” and “the one or more” mean “any one of the at least one” and “any one of the one or more”, respectively.

[0175] As used in this application, the term “circuitry” may refer to one or more or all of the following: a) hardware-only circuit implementations (such as implementations in analog, digital and / or quantum circuitry); and b) combinations of hardware circuit(s) and software, such as (as applicable): i) a combination of analog, digital and / or quantum hardware circuit(s) with software / firmware and ii) any or all portions of hardware processor(s) (including digital and / or quantum processor(s))with software, and memory(ies) that work together to cause an apparatus, such as a mobile device, computing device, or server, to perform various functions; and c) any or all portions of hardware circuit(s), such as microprocessor(s), processor(s) and / or quantum processor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0176] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0177] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and / or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.It will be understandable to a person skilled in the art that, as technology advances, the proposed concept may be implemented in various ways within the scope of the claims. The embodiments are not limited to the example embodiments described above but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiments.

Claims

38CLAIMS1. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:receive from a network node a configuration message configuring the apparatus to measure and report channel state information of one or more candidate cells, said configuration comprising information on at least one of a set of measurement reference signals and a set of measurements to be reported for the one or more candidate cells;determine that at least one of the measurements of the set of measurements to be reported is invalid or unavailable at a reporting occurrence for one or more of the candidate cells;determine a continuation of measuring and reporting based on the configuration message and the determination that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

2. The apparatus according to claim 1, further being caused to: continue measurements as configured and transmit the measurement results to the network in next available granted transmission resource.

3. The apparatus according to claim 1, further being caused to: receive from a source cell of a message to perform a handover from the source cell to a target cell wherein the target cell is one of the candidate cells;perform channel state information measurements of the target cell and reporting to the target cell.

4. The apparatus according to claim 3, wherein the handover is a Layer 1 / 2 triggered handover.

395. The apparatus according to claim 1, further being caused to: switch from a non-connected or a low-power state to a connected state in a target cell wherein the target cell is one of the candidate cells;perform channel state information measurements of the target cell and reporting to the target cell.

6. The apparatus according to any preceding claim 3 to 5, wherein the reporting occurrence is first uplink transmission to the target cell wherein the first uplink transmission is either a transmission using an uplink shared channel or an uplink control channel.

7. The apparatus according to claim 1, further being caused to: encode status of channel state information measurement as a part of channel state information measurement report, the status indicating the validity or availability of at least part of the measurements of the set of measurements.

8. The apparatus according to claim 1, further being caused to: transmit status of channel state information measurement, the status indicating the validity or availability of measurements of the set of measurements.

9. The apparatus according to claim 1, further being caused to: after determining that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence, transmission of a status report to the network indicating that the channel state information measurement is at least in part invalid or unavailable.

10. The apparatus according to claim 3 to 5, further being caused to at least one of:monitor a downlink control information from the target cell for an uplink grant for transmission of channel state information measurement report;transmit channel state information measurement report to the target cell in next available configured grant transmission resource wherein the configured grant resources are configured in the configuration message;40stop measuring and reporting the configured measurements for the target cell.

11. The apparatus according to claim 1, further being caused to: determine that at least one of the measurements of the set of measurements is valid or available at a reporting occurrence to at least one of the candidate cells;transmit a channel state information measurement report to the at least one candidate cell;stop measuring and reporting the configured measurements for the at least one candidate cell.

12. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:transmit a configuration message to a terminal device, the message comprising configuration for the terminal device tomeasure channel state information of one or more candidate cells, the configuration comprising a configuration information of a set of measurement reference signals or / and a set of measurements to be made for the one or more of the candidate cells;determine that at least one channel state information measurement is invalid or unavailable at a reporting occurrence for one or more of candidate cells;continue to stop measuring and reporting based on the configuration message and the determination for the one or more candidate cell.

13. The apparatus according to claim 12, further being caused to: transmit a cell change message to perform a handover from the cell served by the apparatus to a target cell.

14. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:transmit a channel state information reference signal;receive a report from a terminal device, the report comprising status of the channel state information measurement the terminal device is configured to perform.

15. The apparatus according to claim 14, further being caused to: receive the report in the first uplink transmission from the terminal device after the terminal device has made a handover to the cell served by the apparatus or after the terminal device has switched from a non-connected or a low-power state to a connect state.

16. The apparatus according to claim 14 or 15, wherein the report comprises channel state information measurement results.

17. A method comprising:receiving from a network node a configuration message configuring the apparatus to measure and report channel state information of one or more candidate cells, said configuration comprising information on at least one of a set of measurement reference signals and a set of measurements to be reported for the one or more candidate cells;determining that at least one of the measurements of the set of measurements to be reported is invalid or unavailable at a reporting occurrence for one or more of the candidate cells;determining a continuation of measuring and reporting based on the configuration message and the determination that at least one of the measurements of the set of measurements is invalid or unavailable at the reporting occurrence for one or more of the candidate cells.

18. A method comprising:transmitting a configuration message to a terminal device, the message comprising configuration for the terminal device tomeasure channel state information of one or more candidate cells, the configuration comprising a configuration information of a set of measurementreference signals or / and a set of measurements to be made for the one or more of the candidate cells ;determine that at least one channel state information measurement is invalid or unavailable at a reporting occurrence for one or more of candidate cells;continue to stop measuring and reporting based on the configuration message and the determination for the one or more candidate cell.

19. A method comprising:transmitting a channel state information reference signal;receiving a report from a terminal device, the report comprising status of the channel state information measurement the terminal device is configured to perform.

20. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the method steps of claim 17 to 19.

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