WO2021002859A1

WO2021002859A1 - Measurement reporting in wireless network

Info

Publication number: WO2021002859A1
Application number: PCT/US2019/040498
Authority: WO
Inventors: Anil M. Rao; Teemu Mikael VEIJALAINEN; Jani Matti Johannes Moilanen
Original assignee: Nokia Technologies Oy; Nokia of America Corp
Current assignee: Nokia Technologies Oy; Nokia of America Corp
Priority date: 2019-07-03
Filing date: 2019-07-03
Publication date: 2021-01-07
Anticipated expiration: 2022-01-03
Also published as: EP3994918A4; EP3994918A1

Abstract

According to an example aspect of the present invention, there is provided a method comprising, receiving, by a wireless device from a network node, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode; storing, in response to the request, measurements performed in at least one of the idle mode and the inactive mode; and transmitting, to the network node, a measurement report comprising said measurements when entering connected mode from the idle mode or the inactive mode.

Description

MEASUREMENT REPORTING IN WIRELESS NETWORK

FIELD

[0001] Various example embodiments relate to measurement reporting in wireless networks.

BACKGROUND

[0002] In a modern mobile communication systems, a wireless access network node, which may be also be referred to as a base station, determines a transmission format, a transmission block size, a modulation and coding scheme, and the like to be used in a downlink (DL) and an uplink (UL). To perform such determination for the DL, the network node needs information about the performance of a current DL channel from a wireless (user) device, and the information is generally referred to as channel state information (CSI).

[0003] Multi-antenna techniques can significantly increase the data rates and reliability of a wireless communication system. The performance is in particular improved if both the transmitter and the receiver are equipped with multiple antennas, which results in a multiple-input multiple-output (MEMO) communication channel.

[0004] Beamforming uses multiple antennas to control the direction of a wave by appropriately weighting the magnitude and phase of individual antenna signals in an array of multiple antennas. In a system with beamformed transmissions, in order for the transmitter to pick the best beams to transmit in, the network needs feedback from the receiver. In some systems, each beam contains a unique reference signal (RS), which may be referred to as a beam-reference signal (BRS). The wireless device performs measurements on the BRSs and reports measured quality to the network.

[0005] Wireless devices operating in extremely high frequency (EHF) spectrum, also referred to as the millimetre wave (mmwave) spectrum, are particularly sensitive to sudden blockages. As mmwave signals do not diffract around objects the way in which cellular band signals do, very sudden loss of signal can occur when the line-of-sight (LoS) link between the base station and mobile becomes obstructed by an object, such as a building. SUMMARY OF THE INVENTION

[0006] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments for some or all of the aspects are defined in the dependent claims.

[0007] According to a first aspect, there is provided a method, comprising: receiving, by a wireless device from a network node, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode; storing, in response to the request, measurements performed in at least one of the idle mode and the inactive mode; and transmitting, to the network node, a measurement report comprising said measurements when entering connected mode from the idle mode or the inactive mode.

[0008] According to a second aspect, there is provided a method, comprising: receiving, from the network node, a message indicating refined measurement information for performing measurements in at least one of the idle mode and the inactive mode; controlling measurements after entering the idle mode or the inactive mode in accordance with the refined information, and storing, in response to the request, measurements performed in at least one of the idle mode and the inactive mode.

[0009] According to a third aspect, there is provided an apparatus, comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to perform the method of the first aspect.

[0010] According to a fourth aspect, there is provided an apparatus, comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to perform the method of the second aspect.

[0011] According to a fifth aspect, there is provided a computer program product, a computer readable medium, or a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform the method according to any one of the above aspects or embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIGURE 1 illustrates a network scenario in accordance with at least some embodiments;

[0013] FIGURE 2 illustrates a first method in accordance with at least some embodiments; [0014] FIGURE 3 illustrates a second method in accordance with at least some embodiments;

[0015] FIGURE 4 illustrates radio resource control modes;

[0016] FIGURES 5 to 7 are signalling diagrams in accordance with at least some embodiments; [0017] FIGURE 8 illustrates a data transfer session timeline example in accordance with at least some embodiments; and

[0018] FIGURE 9 illustrates an example apparatus capable of supporting at least some embodiments.

EMBODIMENTS [0019] FIGURE 1 illustrates a simplified example system in accordance with at least some embodiments. A user equipment (UE) 10 communicates wirelessly with a wireless radio or access network node, hereafter referred to as AN, 20, such as a NodeB, an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a base station, an access point, or other suitable wireless/radio access network device or system. [0020] The UE 10 may be attached to a cell of the AN, 20, 30 for wireless communications. For example, at time instant tl, the AN 20 may be a serving AN or serving cell for the UE 10. The air interface between UE and AN may be configured in accordance with a Radio Access Technology, RAT, which both the UE 10 and AN 20, 30 are configured to support. [0021] Examples of cellular RATs include Long Term Evolution, LTE, New Radio,

NR, which is also known as fifth generation, 5G, and MulteFire. On the other hand, examples of non-cellular RATs include Wireless Local Area Network, WLAN, and Worldwide Interoperability for Microwave Access, WiMAX. Principles of the present disclosure are not limited to a specific RAT though. For example, in the context of LTE, AN 20, 30 may be a nodeB or evolved Node B (eNB), while in the context of NR, AN 20, 30 may be a gNB.

[0022] The AN 20, 30 may be connected, directly or via at least one intermediate node, with a core network (not shown), such as a Next Generation core network, Evolved Packet Core (EPC), or other network management element.

The core network may comprise a set of network functions. A network function may refer to an operational and/or physical entity. The network function may be a specific network node or element, or a specific function or set of functions carried out by one or more entities, such as virtual network elements. Examples of such network functions include an access control or management function, mobility management or control function, session management or control function, interworking, data management or storage function, authentication function or a combination of one or more of these functions. For example, a 5G core network comprises Access and Mobility Management Function (AMF) which may be configured to terminate RAN control plane (N2) interface and perform registration management, connection management, reachability management, mobility management, access authentication, access authorization, Security Anchor Functionality (SEAF), Security Context Management (SCM), and support for interface for non-3GPP access. The AMF is in charge for managing handovers between gNBs.

[0023] The core network may be, in turn, coupled with another network (not shown), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network. The AN may be connected with at least one other AN as well via an inter-base station interface, particularly for supporting mobility of the UE 10, e.g. by 3GPP X2 or similar NG interface.

[0024] The UE 10 may be referred to as a user device or wireless terminal in general. Hence, without limiting to Third Generation Partnership Project (3GPP) User Equipment, the term user equipment is to be understood broadly to cover various mobile/wireless terminal devices, mobile stations and user devices for user communication and/or machine to machine type communication. The UE 10 may be or be comprised by, for example, a smartphone, a cellular phone, a Machine-to-Machine, M2M, node, machine-type communications node, an Internet of Things, IoT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, another kind of suitable user device or mobile station, i.e., a terminal. [0025] The example system of FIGURE 1 applies a set of beams, including 22, 24, 26 by AN 20 and 32, 34 by AN 30, to provide cell coverage. For example, if the system is a 5G mmwave system, a grid of fixed analog beams is applied and it is known at each instance in time which beam is serving a given user.

[0026] The UE 10 may be configured to report measurements on a number of beams via channel state information (CSI). Based on the reported beam measurements, the AN 20, 30 can determine which is the best beam that should serve the UE 10, and carry out a beam management procedure signaling the UE 10 to receive from the best beam.

[0027] An object 40, such as a building, may block a beam 26 so that when the UE 10 proceeds further at time instant t2 and t3, the UE 10 may suddenly loose connection to the AN 20 and needs to handover to the other AN 30. Handover refers herein generally to change of serving wireless access network node, in cellular systems change of serving cell.

[0028] In some embodiments, the AN 20, or a further network entity connected to the AN, may be configured to apply a machine learning model and store history data of which beam best serves the UE 10 as the UE continues on its trajectory. This history data may comprise a time series of beam index values. When the UE’s signal to the serving AN 20 is suddenly blocked at time instant t2 and a handover request is generated, the machine learning model can be trained to predict when these blockage events happen. The model may be trained to predict to which new cell ID the UE needs to be handed over to, based on the past time series of beam indices.

[0029] In the training stage it can be assumed that test UEs may be configured to continuously transmit and/or receive data (i.e. have“full buffer” traffic) and testing may be performed over parts of the network of interest to gather a large training set in order to train the machine learning model how to predict handover events from a past sequence of connected beam indices. In order to get good predictions, the time history of beam sequences may need to be quite long, comprising 10 seconds or more of connected beam index value, for example.

[0030] After the machine learning model has been sufficiently trained, when it is deployed to make predictions it may use the time series of beam index values being collected by network infrastructure, such as, for example, the AN 20 to make a future prediction if a blockage event is going to occur within a certain future time window (e.g. within the next 100 ms). For example, such deployment stage of the model may also be referred to as online inference phase. A prediction algorithm can be trained and/or deployed based on the collected measurements in a network infrastructure node, such as AN 20, a combination of multiple network infrastructure nodes, or another node in the network.

[0031] If the model predicts with high probability a blockage event is going to occur and that handover to a new AN 30 will take place, the system can proactively issue a handover command to the UE prior to the actual blockage event happening. This enables to achieve better performance as the sudden loss in signal quality can be avoided and a high quality of service (e.g. high data rate and/or low packet loss rate) can be maintained for the UE. It is to be noted that the system may be configured to further train the model also when it is being deployed, to react to changes in the environment.

[0032] However, typical data traffic in a wireless network often consists of very short bursty data sessions in which the volume of data is small enough relative to the available channel bandwidth that data transfer between the AN and the UE may finish exchanging all of the available data in just a few hundred milliseconds. This will be especially true in 5G NR mmwave systems in which several hundred megahertz of bandwidth now becomes available. For example, downloading even a sizable 2 MB web page on a 5G NR mmwave connection that supports 50 Mbps will take only 0.32 seconds. When the webpage is downloaded, the user is typically reading the content and there is no longer any data activity for some period of time, and the UE is transitioned from a connected state to an idle state. This enables to reduce UEs with no data transfer activity consuming network signaling resources, as they are reporting measurements during the connected mode. For example, with reference to radio resource control (RRC) states of 5G NR illustrated in FIGURE 4, the UE transitions from an RRC_CONNECTED state to an RRC_IDLE state on the basis of expiration of an inactivity timer (datalnactivityTimer).

[0033] It may be problematic to obtain sufficiently long time series of measurements to achieve reliable proactive mobility on the basis of a trained machine learning model in deployment (i.e. in the inference stage). Unless the UE has a lengthy data session lasting many seconds or tens of seconds, often there will not be a long enough sequence of beam index values collected in order to predict the user trajectory to make a good prediction of when a blockage or handover event will occur in the future to proactively trigger a handover for the user. [0034] There are now provided improvements facilitating to selectively obtain more comprehensive measurement data, which in some embodiments is applied for proactive mobility management. FIGURE 2 is a flow graph of a first method in accordance with at least some embodiments. The illustrated first method may be performed by a user equipment, such as the UE 10, or by a control device configured to control the functioning thereof, possibly when installed therein. It is to be noted that an action, such as transmitting, in a given block may refer to controlling or causing such action in another apparatus or unit.

[0035] The method comprises receiving 200 from a network node, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode. In response to the request, measurements performed in at least one of the idle mode and the inactive mode are stored 210. A measurement report comprising said measurements is transmitted 220 to the network node when entering a connected mode from the idle mode or the inactive mode. Thus, measurement result data of at least some of the measurements performed during the idle and/or inactive mode may be stored 210 and at least some of the stored measurement result data may be reported in block 220.

[0036] Thus, the wireless device may be instructed to store and report measurements performed when in the mode of non-active data transfer, in addition to measurements performed and reported during the connected mode. It is noted that instead of the term ‘mode’, the term‘state’ may be used. The modes are not limited to currently applied or known (radio resource control) modes, such as the 5G RRC modes of FIGURE 4. For example, the term idle mode may refer generally to a mode or state in which there are no radio resources reserved for active data transfer for the wireless device. The connected mode generally may refer to a mode or state in which radio resources are reserved for active data transfer for the wireless device. The inactive mode generally may refer to a mode or state in which radio resources are not reserved, or more resources than in the idle mode but less than in the connected mode are reserved for active data transfer for the wireless device, but an RRC context or other UE information may be maintained in the network to facilitate faster mode change to the connected mode. Idle, inactive and connected modes may also refer more generally to three modes, where the inactive mode is an intermediate mode between the idle mode, which is the least active among the three modes, and the connected mode which is the most active among the three modes. There can be nevertheless also other activity modes in the system. [0037] FIGURE 3 is a flow graph of a second method in accordance with at least some embodiments. The illustrated method may be performed by a network node, such as the AN 20, 30, or by a control device configured to control the functioning thereof, possibly when installed therein. The network node may be configured to communicate with a wireless device performing the method of FIGURE 2. It is to be noted that an action, such as transmitting, in a given block may refer to controlling or causing such action in another apparatus or unit.

[0038] The method comprises transmitting 300, to a wireless device, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode. A measurement report comprising measurements stored by the wireless device in the idle mode and/or the inactive mode is received 310 from the wireless device. The measurement report is received when the wireless device is entering a connected mode from the idle mode or the inactive mode.

[0039] A network may thus selectively control wireless devices e.g. in a certain cell to perform and/or store measurements during an idle and/or inactive mode and report the measurements upon transitioning to an active mode. In some embodiments, the AN 20 may control UEs in its cell to perform and/or store measurements of at least some of the beams during the idle mode or the inactive mode. A measurement report comprising quality indicators of measured beams may thus be transmitted 220 to the network node in accordance with the control information received in the broadcast message. The report 220, 310 thus at least comprises information on beam measurements performed in the idle and/or inactive mode. Such beam measurement report may be specific to the idle and/or inactive mode. Some further embodiments are illustrated below, with references to the UE (10) and AN (20) as the wireless device and the network node, respectively. The message/request of block 200, 300 may be further selective in the cell. In an embodiment, the request is directed to a subset of wireless devices within a set, e.g. a subset of UEs in a cell. The subset can be selected based on some characteristics, such as type of device, location within the cell, etc.

[0040] In some embodiments, the broadcast message of block 200, 300 is transmitted/received upon cell selection or reselection for the UE 10. Thus, the broadcast message may be transferred when the wireless device is attaching or registering to the cell. The broadcast message may be a system information message, for example. The broadcast message may comprise a specific information element indicative of measurements to be performed and stored during the idle mode. The broadcast message may comprise a specific information element indicative of measurements to be performed and stored during the inactive mode. Such information element may be an extension of a current broadcast message, such as a system information message comprising a list of connected mode measurements.

[0041] The request to store measurements may indicate requesting to perform new measurements and/or requesting to store existing measurements. Thus, in the latter case the UE 10 may be configured to, in response to the request, store and report measurements performed during the idle mode and/or inactive mode. The request may define which measurements the UE needs to store.

[0042] The broadcast message may comprise dedicated radio resource information for measurements performed in the idle mode and/or the inactive mode. The UE 10 may thus configure the measurements in the respective mode in accordance with the received dedicated radio resource information.

[0043] The broadcast message may comprise measurement (control or configuration) information, on the basis of which the UE 10 adapts measurements, storing of measurement results, and/or reporting of measurement results. The configuration information may specify dedicated radio signals to be used for UE measurements, such as a specially designed radio signal, beams, MIMO modes, and/or even ML exploration specific data transmissions.

[0044] The broadcast message may indicate a number of time-ordered measurements to be performed and stored in at least one of the idle mode and the inactive mode. The request may define how many (most recent) measurements should be stored (and reported). The broadcast message may indicate a number of time-ordered measurements to be performed and stored in at least one of the idle mode and the inactive mode.

[0045] The measurement report of block 220, 310 may be included in a RRC setup complete message, in a RRC reconfiguration complete message, or in a RRC resume complete message.

[0046] The measurement report may comprise a time-ordered list of measurements performed by the UE 10 at a paging cycle applied in the idle and/or the inactive mode. Time stamps of respective measurements may be included in the stored measurement data and the measurement report. [0047] In some embodiments, beam measurements are performed, and the measurement report may comprise connected beam indices. At least cell identification and strongest beam index information as time-ordered list may be stored 210 and included in the measurement report 220. However, the request of block 200, 300 may indicate measurements to be performed of one or more neighbouring cells. The UE 10 may thus be configured on the basis of the request to store and include in the measurement report measurements of the one or more neighbouring cells. The measurement report may comprise reference signal received power (RSRP) and/or other quality indicators of the cells or beams being reported.

[0048] In some embodiments, the measurements configured to the UE 10 by the broadcast message may be modified or updated by a further broadcast message or a device specific message. In a further embodiment, when the UE has entered the connected mode, a message indicating refined measurement information for performing measurements in the idle mode and/or the inactive mode is received from the network node. Measurements are performed after transitioning from the connected mode to the idle mode or the inactive mode in accordance with the refined information. The measurements performed in the idle mode and/or the inactive mode are stored in accordance with the refined measurement information. The stored measurement results may be reported upon returning to the active mode. The message indicating refined measurement information may be a device- specific message during the connected mode.

[0049] In some embodiments, the received measurement information of the measurements stored during the idle and/or inactive mode is provided after block 310 to a mobility management module. The module may be configured to, on the basis of processing the measurements, predict a blockage event or a handover event for the wireless device and determine a new cell for proactively handing over the wireless device. The module may comprise the machine learning model trained, on the basis of historical measurement submitted by wireless devices, to predict trajectory of the wireless device, and predict the blockage event, a handover event, or a beam switching event.

[0050] The mobility management module, or another control module, in the network node or another controlling network entity, may be configured to decide proactively on the basis of the prediction to which beam to switch to in the same cell or whether to proactively handover the UE to another cell to avoid a blockage event. [0051] In an embodiment, movement of the UE 10 is detected. The UE may be configured to include in the measurement report an indication of its detected movement, and possible further characterizing information on the movement, such as speed. This information may be applied by the proactive mobility management module.

[0052] In some embodiments, at least some of the presently disclosed features are applied for 5G NR systems, further such embodiments being illustrated below. FIGURE 4 illustrates 3GPP 5G RRC modes, or states as also referred to below. The RRC_INACTIVE state was introduced in 3 GPP 5G NR, as compared to only the RRC_CONNECTED and RRC_IDLE states present in 3GPP 4G LTE, in order to allow faster state transitions from a low power inactive state to a fully connected state, as the mobile context is still stored in the base station in the RRC_INACTIVE state and so when the mobile resumes from RRC_INACTIVE to RRC_CONNECTED the core network does not need to be contacted by the base station to retrieve information about the mobile to establish a new mobile context. The transition from RRC_CONNECTED to RRC_INACTIVE is completely controlled by the network and not dependent on data inactivity timers such as the transition to RRC_IDLE. As such, the network can choose to transition the user to the RRC_INACTIVE state from RRC_CONNECTED state after a very short period of data inactivity to try and optimize mobile battery life, knowing that it can quickly bring it back into RRC_CONNECTED state when it needs to. This provides an intermediate state between RRC_CONNECTED and RRCJDLE.

[0053] Presently disclosed features may be particularly beneficial for 5G Ultra Reliable Low Latency Communications (URLLC), for which it is particularly important to ensure that the UE does not have its transmission interrupted by a blocking event.

[0054] The gNB may broadcast via system information blocks (SIBs) an indicator informing UEs which either initially camp in this part of the network or UEs that perform cell reselection to this part of the network that the network requests that UEs start storing in a time sequential manner measurements during the RRC_INACTIVE OR RRC_IDLE mode.

[0055] While in RRC_IN ACTIVE or RRC_IDLE state, the UE is in a low power “sleep” mode to reduce battery consumption. It wakes up periodically based on a configured paging cycle value. Parameter ran-PagingCycle in SuspendConfig information element controls the paging cycle while the UE is in the RRC_INACTIVE state and the parameter defaultPagingCycle in the PCCH-Config information element controls the paging cycle while the mobile is in RRC_IDLE state. The paging cycle can be {320ms, 640ms, 1280ms, 2560ms] according to 3GPP 38.331. A typical value that is configured is 640ms. [0056] When the UE transitions from RRCJNACTIVE or RRC_IDLE to RRC_CONNECTED state, it may report these stored measurements as part of the RRC connection establishment/re-establishment procedure, so that they are available immediately at the start of the data session in the RRC_CONNECTED state.

[0057] When waking up based on the paging cycle (e.g. every 640ms), the UE performs measurements to determine the best cell and the best beam index on the cell via measuring the synchronization signal block (SSB). For mmwave carrier frequencies, there can be up to 64 beams per cell, and hence 64 different SSBs. The SSB comprises of the physical broadcast channel (PBCH) and a primary synchronization signal (PSS) and secondary synchronization signal (SSS). On the basis of the PBCH and PSS/SSS, the UE determines the physical cell identity (PhysCellld), which can take a value from 0 to 1007 and hence can be represented with 10 bits. The UE also determines the best beam index represented as SSB-Index, which takes on a value between 0 and 63 and hence can be represented with 6 bits.

[0058] The quantities could include items such as the 10-bit physical cell ID (PhysCellld) and the 6-bit best beam of that cell (SSB-Index), together with the RSRP on the best beam. It could also include measurements pertaining to dominant neighboring cells, such as the PhysCellld and SSB-Index corresponding to the strongest beam along with the RSRP value for one more neighboring cells. In addition, information on one or more weaker cells can also be specified to be reported, such as PhysCellld, strongest beam SSB-Index, RSRP value on 2^nd, 3^rd, etc. strongest cells.

[0059] Rather than individually sending RRC messages to each UE that is already in the connected mode to instruct them to perform idle mode measurements the next time they go into idle mode, the SIB broadcast message may thus be applied to efficiently notify all UEs camped on cells for which the idle mode measurements are desired. This means even the first time the UE enters into RRC_CONNECTED state on this part of the network, it already has stored measurements ready to report.

[0060] The present features enable very fast transfer of relatively short sequence of logged measurements, immediately available upon entering the connected mode. This is one substantial advantage over a technique referred to as minimization of drive test (MDT) designed for non-real time offline of collection of measurements, with complex sequence of messages involved to for network to obtain measurements. According to the MDT, when the UE connects for the first time, it will not have any stored measurements as it has not yet been instructed to make such measurements. [0061] By applying presently disclosed features, proactive mobility algorithms which depend on having a time series of recent historical measurements to be able to track and then predict a mobile’s trajectory can now have such information right at the start of the data session for all mobiles connecting to the network, without having to configure each mobile individually as in the MDT and without having to have specific messages sequences to request and then retrieve stored information as MDT (which adds latency). Hence, right at the start of the RRC connection when the UE is ready to exchange user plane data with the network, proactive mobility algorithms can use the stored sequence of measurements allowing for higher accuracy blockage/handover predictions even for the very short data sessions which make up a high percentage of the total data sessions in the network.

[0062] FIGURE 5 illustrates a signaling example for a 3GPP 5G NR system, starting from UE being powered on 50E After a Master Information Block 502, the SIB message 503 may now comprise the request to store measurements in the idle state. In an embodiment, the message may comprise an optional field specifying how many of the most recent PhysCellld and SSB-Index measurements the UE needs to store when it is in the RRC_IDLE state. In 504 the UE behavior in the RRC_IDLE state is adapted in accordance with the received request, and it may store the PhysCellld and SSB-Index it determines at every paging cycle. In response to detecting need to transition to the RRC_CONNECTED state, RRC setup request message 505 is transmitted, responded by RRC setup message 506.

[0063] The UE may be configured to include the new measurement sequence as part of the RRC Setup Complete message 507, so the idle mode measurements are readily available at the gNB at the beginning of the data session 509 for the UE in RRC- CONNECTED state 508. After end of the data session, RRC release message 510 is transmitted.

[0064] A field may be added in the SIB message, such as the message 502, that may be referred e.g. as IdleModeMeasurementList, which specifies the list of idle mode measurements the network would like UEs to collect while in RRC_IDLE state. This list can include items such as the PhysCellld, SSB-Index, RSRP of the strongest measured cell and possibly also of a number of additional next strongest cells. In an embodiment, the list may comprise a request that the RSRP and SSB-Index of the strongest beam(s) be reported on a specific set of neighboring PhysCell Id’s.

[0065] Additionally, a parameter, called for example NumldleModeMeasurements, may specify the number of time ordered, sequential measurements that the UE should store while in the RRC_IDLE mode 504. This parameter could take on specific integer values, as an example {nlO, n20, n30, n40, n50, n60, n70, n80} where nlO corresponds to the integer 10, n20 the integer 20, etc. In a further embodiment, there may a NumldleModeMeasurements specified per measured KPI, e.g. one value for PhysCellld/SSB and another higher value for RSRPs.

[0066] To handle the RRC_IDLE to RRC_CONNECTED state transition, a field may be added in the RRCSetupComplete Information Element which is part of the RRCSetupComplete message. Such field may be e.g. referred to as idleModeBeamMeasurementList, and may be defined as data structures, for example:

- idleModeMeasurementList ::= SEQUENCE (SIZE (1..

NumldleModeMeasurements ) OF idleOrlnactiveModeMeasurements

[0067] where we for example may define idleOrlnactiveModeMeasurements ::= SEQUENCE {

physCellld INTEGER (0 .. 1007) ssb-Index INTEGER (0 .. 63)

RSRP INTEGER (0 .. 127) and any other quantities we want the UE to store such as measurements on the“N” strongest cells or on specific neighboring cell PhysCellld’ s

}

[0068] A message for transitioning from the connected mode, such as the RRC release message 510, may comprise parameters for controlling idle and/or inactive mode measurements. The parameters may override the parameters stored on the basis of the SIB 503. The parameters may be UE-specific and may indicate which measurements and how many measurements should be stored (and reported), for example.

[0069] FIGURE 6 illustrates example signalling in the case of the UE in RRC_IN ACTIVE state, in which the UE is first in the RRC_CONNECTED state 601. After receiving RRC release message 602 (which may comprise suspend configuration), the UE transitions to the RRC_IN ACTIVE state 603. The UE now stores the measurements in the RRC_INACTIVE state in accordance with the request in an earlier received broadcast message, such as the SIB 503. The UE may thus be configured to store the PhysCellld and SSB-Index it determines at every RAN paging cycle. Upon need to return to RRC_CONNECTED state, RRC resume message 604, 605 are transferred. The UE may be configured to include the new measurement sequence as part of the RRC ResumeComplete message 606 so the measurements are readily available at the gNB at the beginning of the data session for the UE in the RRC-CONNECTED state.

[0070] Similarly as for the idle mode measurements, new elements or parameters InactiveModeMeasurementList and NumlnactiveModeMeasurements can be specified. These lists may determine the list of measurements to be collected and the number of measurements to store for UEs in the RRC_INACTIVE state, respectively. In general it may be desirable to have different measurements stored in the RRC_INACTIVE state as compared to the RRC_IDLE state. It may also be desirable to have the number of measurements stored to be different in these states.

[0071] Similarly, to handle the RRC_IN ACTIVE to RRC_CONNECTED mode transition, an optional field may be added in the RRCResumeComplete Information Element which is part of the RRCResumeComplete message 606, for example:

InactiveModeMeasurementList ::= SEQUENCE (SIZE (1..

NumlnactiveModeMeasurements ) OF idleOrlnactiveModeMeasurements

[0072] It should be noted that various optimizations are possible to reduce the overhead of measurement storage and reporting. For example, as soon as the UE 10 reports the stored idle/inactive mode measurements after transitioning to the RRC_CONNECTED state, it may delete these stored measurements as they do not need to be reported again. In another example embodiment, various compression techniques exist that may be utilized for the case the UE’s are relatively stationary and the same measurement values (i.e. PhysCellld and ssb-Index) are not changing over many paging cycle idle mode measurement intervals. In this case the run-length lossless data compression technique can be utilized, for example. For reported RSRP values, a differential RSRP value between paging cycle measurements may be utilized to reduce the number of bits needed to indicate the sequence of RSRP values.

[0073] With reference to FIGURE 7, as another embodiment to handle the case of RRC_IDLE to RRC_CONNECTED transition, the measurements are transmitted (220) after establishment of security keys. The logged measurement information from the UE may be included in the RRCReconfigurationComplete message 705 transmitted after DL/UL InformationTransfer messages 701, 702 and security mode messages 703, 704.

[0074] This option may be applied if it is seen as problematic to transfer the UE’s idle mode measurement history on the RRCSetupComplete message as the security keys have not yet been established with the network. The additional delay in getting the logged measurements is not a significant issue as the RRCReconfigurationComplete must be completed before the start of user plane data traffic anyway.

This is not an issue for the RRC_INACTIVE to RRC_CONNECTED transition because the security context is already established for mobiles in the RRC_INACTIVE state.

[0075] Figure 8 illustrates an example how beam tracking can now be done in the RRC_IDLE (or RRC_INACTIVE) state on the basis of presently disclosed features. The darkened beams, such as beams 800 and 802, may illustrate beams that are (at least) stored and reported as strongest. For example, during the RRC_IDLE state the beams (e.g. beam 802) of three different cells are stored in response to the earlier received request in the broadcast message, such as the SIB 503.

[0076] Information on which cell and which beam a mobile found to be the strongest in the RRC_IDLE state is now made available to the network upon transition back to the RRC_CONNECTED state. This allows for blockage/proactive handover prediction to take place immediately upon the RRC_CONNECTED state transition rather than starting from scratch and having to collect sufficient measurements in time before a prediction can be made, at which time the data session may have ended already. Although the measurements collected in the RRC_IDLE or the RRC_INACTIVE state may be less frequent than in the RRC_CONNECTED state, they are still valuable in order to have historical information on the mobile’s trajectory in order to be able to make better predictions on its future position for proactive handover purposes.

[0077] As an example, we can consider the following scenario:

IdleModeMeasurementList = {PhysCehld (10 bits), SSB-Index (6 bits) } NumldleModeMeasurements = n20 (20 measurements)

[0078] If the paging cycle for the UE in RRC_IDLE mode is e.g. 640 ms, 20 measurements would correspond to a list of idle mode measurements spanning the last 20*640ms = 12.8 seconds. The total number of bits stored would be 20 measurements ^ 10 bits PhysCehld + 6 bits SSB-Index) = 320 bits, which is a very reasonably sized message.

[0079] As explained above, more items may optionally be added to the IdleModeMeasurementList based on the particular use case at hand, for example having the RSRP measurement available, or having some neighboring cell measurements available could support additional use cases beyond the proactive mobility problem. [0080] Although above embodiments related to proactive mobility management were disclosed, at least some of the presently disclosed measurement control features may be applied for other purposes or in other situations where comprehensive measurement result reporting is of advantage.

[0081] An electronic device comprising electronic circuitries may be an apparatus for realizing at least some embodiments of the present invention. The apparatus may be or may be comprised in a computer, a laptop, a tablet computer, a cellular phone, a machine to machine (M2M) device (e.g. an IoT sensor device), a wearable device, a base station, access point device, a network function element or node, or any other apparatus provided with radio communication capability. In another embodiment, the apparatus carrying out the above- described functionalities is comprised in such a device, e.g. the apparatus may comprise a circuitry, such as a chip, a chipset, a microcontroller, or a combination of such circuitries in any one of the above-described devices.

[0082] FIGURE 9 illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is a device 900, which may comprise a communications device arranged to operate as the AN 20, 30, or the UE 10, for example. The device may include one or more controllers configured to carry out operations in accordance with at least some of the embodiments illustrated above, such as some or more of the features illustrated above in connection with FIGURES 2 to 8. The device may be configured to operate as the apparatus configured to perform the method of FIGURE 2 or 3, for example.

[0083] Comprised in the device 900 is a processor 902, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. The processor 902 may comprise more than one processor. The processor may comprise at least one application-specific integrated circuit, ASIC. The processor may comprise at least one field-programmable gate array, FPGA. The processor may be means for performing method steps in the device. The processor may be configured, at least in part by computer instructions, to perform actions.

[0084] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with embodiments described herein. 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 only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0085] 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.

[0086] The device 900 may comprise memory 904. The memory may comprise random-access memory and/or permanent memory. The memory may comprise at least one RAM chip. The memory may comprise solid-state, magnetic, optical and/or holographic memory, for example. The memory may be at least in part accessible to the processor 902. The memory may be at least in part comprised in the processor 902. The memory 904 may be means for storing information. The memory may comprise computer instructions that the processor is configured to execute. When computer instructions configured to cause the processor to perform certain actions are stored in the memory, and the device in overall is configured to run under the direction of the processor using computer instructions from the memory, the processor and/or its at least one processing core may be considered to be configured to perform said certain actions. The memory may be at least in part comprised in the processor. The memory may be at least in part external to the device 900 but accessible to the device. For example, control parameters affecting controlling operations illustrated in connection with Figures 2 and/or 3 may be stored in one or more portions of the memory and used to control operation of the apparatus. Further, the memory may comprise other control parameters and device-specific cryptographic information. [0087] The device 900 may comprise a transmitter 906. The device may comprise a receiver 908. The transmitter and the receiver may be configured to transmit and receive, respectively, information in accordance with at least one wired or wireless, cellular or non- cellular standard. The transmitter may comprise more than one transmitter. The receiver may comprise more than one receiver. The transmitter and/or receiver may be configured to operate in accordance with global system for mobile communication, GSM, wideband code division multiple access, WCDMA, long term evolution, LTE, 5G or other cellular communications systems, WLAN, and/or Ethernet standards, for example. The device 900 may comprise a near- field communication, NFC, transceiver 910. The NFC transceiver may support at least one NFC technology, such as NFC, Bluetooth, Wibree or similar technologies.

[0088] The device 900 may comprise user interface, UI, 912. The UI may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing the device to vibrate, a speaker and a microphone. A user may be able to operate the device via the UI, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in the memory 904 or on a cloud accessible via the transmitter 906 and the receiver 908, or via the NFC transceiver 910, and/or to play games.

[0089] The device 900 may comprise or be arranged to accept a user identity module or other type of memory module 914. The user identity module may comprise, for example, a subscriber identity module, SIM, and/or a personal identification IC card installable in the device 900. The user identity module 914 may comprise information identifying a subscription of a user of device 900. The user identity module 914 may comprise cryptographic information usable to verify the identity of a user of device 900 and/or to facilitate encryption and decryption of communication effected via the device 900.

[0090] The processor 902 may be furnished with a transmitter arranged to output information from the processor, via electrical leads internal to the device 900, to other devices comprised in the device. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 904 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise the processor may comprise a receiver arranged to receive information in the processor, via electrical leads internal to the device 900, from other devices comprised in the device 900. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from the receiver 908 for processing in the processor. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

[0091] The device 900 may comprise further devices not illustrated in FIGURE 9. For example, the device may comprise at least one digital camera. Some devices may comprise a back-facing camera and a front-facing camera. The device may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of the device. In some embodiments, the device lacks at least one device described above. For example, some devices may lack the NFC transceiver 910 and/or the user identity module 914.

[0092] The processor 902, the memory 904, the transmitter 906, the receiver 908, the NFC transceiver 910, the UI 912 and/or the user identity module 914 may be interconnected by electrical leads internal to the device 900 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to the device, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0093] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0094] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or“in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed. [0095] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0096] In an exemplary embodiment, an apparatus, such as, for example, a user equipment or terminal or a network node, may comprise means for carrying out the embodiments described above and any combination thereof.

[0097] In an exemplary embodiment, a computer program may be configured to cause a method in accordance with the embodiments described above and any combination thereof. In an exemplary embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a process comprising the embodiments described above and any combination thereof.

[0098] In an exemplary embodiment, an apparatus, such as, for example, a terminal or a network node, may comprise at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform the embodiments described above and any combination thereof.

[0099] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. [00100] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[00101] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

Claims

CLAIMS:

1. An apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to perform:

- receiving from a network node, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode;

- storing, in response to the request, measurements performed in at least one of the idle mode and the inactive mode; and

- transmitting, to the network node, a measurement report comprising said measurements when entering a connected mode from the idle mode or the inactive mode.

2. The apparatus of claim 1, wherein the apparatus is further configured for controlling beam measurements of at least one cell during at least one of the idle mode and the inactive mode in accordance with measurement information in the broadcast message.

3. The apparatus of any preceding claim, wherein the request to store measurements comprises at least one of requesting to perform new measurements or requesting to store existing measurements.

4. The apparatus of any preceding claim, wherein the apparatus is configured for receiving the broadcast message upon cell selection or reselection.

5. The apparatus of any preceding claim, wherein the apparatus is configured for storing in response to the broadcast message in at least one of the idle mode and the inactive mode, and including in the measurement report, at least cell identification and strongest beam index information as time-ordered list.

6. The apparatus of any preceding claim, wherein the apparatus is further configured for detecting movement of the apparatus, and including in the measurement report an indication of the movement of the apparatus.

7. The apparatus of any preceding claim, wherein the apparatus is further configured for

- receiving, from the network node, a message indicating refined measurement information for performing measurements in at least one of the idle mode and the inactive mode;

- controlling measurements after entering the idle mode or the inactive mode in

accordance with the refined information, and

- storing, in response to the request, measurements performed in at least one of the idle mode and the inactive mode.

8. The apparatus of claim 7, wherein the apparatus is configured for receiving the message indicating refined measurement information as a device- specific message during the connected mode.

9. The apparatus of any preceeding claim, wherein the apparatus is further configured to perform and/or store measurements during the connected mode.

10. The apparatus of any preceding claim, wherein the apparatus is or is comprised by a cellular user equipment.

11. An apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to perform:

- transmitting, to a wireless device, a broadcast message indicating a request to store measurements in at least one of an idle mode and inactive mode; and

- receiving from the wireless device a measurement report comprising measurements stored by the wireless device in at least one of the idle mode and the inactive mode, the measurement report being received when the wireless device is entering a connected mode from the idle mode or the inactive mode.

12. The apparatus of claim 11, wherein the apparatus is configured for providing the measurements to a mobility management module configured to, on the basis of processing the measurements, predict a blockage event or a handover event for the wireless device and determine a new cell for proactively handing over the wireless device.

13. The apparatus of any preceding claim, wherein the broadcast message is a system information message.

14. The apparatus of any preceding claim, wherein the broadcast message comprises an information element indicative of measurements to be performed and/or stored during the idle mode.

15. The apparatus of any preceding claim, wherein the broadcast message comprises an information element indicative of measurements to be performed and/or stored during the inactive mode.

16. The apparatus of any preceding claim, wherein the broadcast message indicates a number of measurements to be performed and/or stored in at least one of the idle mode and the inactive mode.

17. The apparatus of any preceding claim, wherein the broadcast message indicates cells to be measured in at least one of the idle mode and the inactive mode.

18. The apparatus of any preceding claim, wherein the measurement report is included in a radio resource control connection establishment or re-establishment message.

19. The apparatus of any preceding claim, wherein the measurement report comprises connected beam indices.

20. The apparatus of any preceding claim, wherein the measurement report is included in a radio resource control setup complete message, in a radio resource control reconfiguration complete message, or in a radio resource control resume complete message.

21. An apparatus comprising means for performing:

22. A method, comprising:

- receiving, by a wireless device from a network node, a broadcast message indicating a request to store measurements in at least one of an idle mode and an inactive mode;

- transmitting, to the network node, a measurement report comprising said measurements when entering connected mode from the idle mode or the inactive mode.

23. The method of claim 22, further comprising: controlling beam measurements of at least one cell during at least one of the idle mode and the inactive mode in accordance with measurement information in the broadcast message.

24. The method of claim 22 or 23, wherein the request to store measurements comprises at least one of requesting to perform new measurements or requesting to store existing measurements.

25. The method of any preceding claim 22 to 24, wherein the broadcast message is received upon cell selection or reselection.

26. The method of any preceding claim 22 to 25, further comprising: storing in response to the broadcast message in at least one of the idle mode and the inactive mode, and including in the measurement report, at least cell identification and strongest beam index information as time-ordered list.

27. The method of any preceding claim 22 to 26, further comprising: detecting movement of the apparatus, and including in the measurement report an indication of the movement of the apparatus.

28. The method of any preceding claim 22 to 27, further comprising:

- controlling measurements after entering the idle mode or the inactive mode in

accordance with the refined information, and

29. The method of claim 28, wherein the message indicating refined measurement information is received as a device- specific message during the connected mode.

30. The method of any preceding claim 22 to 29, further comprising: performing and/or storing measurements during the connected mode.

31. A method, comprising:

32. The method of claim 31, further comprising: providing the measurements to a

mobility management module configured to, on the basis of processing the measurements, predict a blockage event or a handover event for the wireless device and determine a new cell for proactively handing over the wireless device.

33. The method of any preceding claim 22 to 32, wherein the broadcast message is a system information message.

34. The method of any preceding claim 22 to 33, wherein the broadcast message

comprises an information element indicative of measurements to be performed and/or stored during the idle mode and/or inactive mode.

35. The method of any preceding claim 22 to 34, wherein the broadcast message indicates a number of measurements to be performed and/or stored in at least one of the idle mode and the inactive mode.

36. The method of any preceding claim 22 to 35, wherein the broadcast message indicates cells to be measured in at least one of the idle mode and the inactive mode.

37. The method of any preceding claim 22 to 36, wherein the measurement report is included in a radio resource control connection establishment or re-establishment message.

38. The method of any preceding claim 22 to 37, wherein the measurement report comprises connected beam indices.

39. The method of any preceding claim 22 to 38, wherein the measurement report is included in a radio resource control setup complete message, in a radio resource control reconfiguration complete message, or in a radio resource control resume complete message.

40. A computer program, comprising instructions for causing an apparatus to perform the method of any one of claims 22 to 39.

41. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform the method of any one of claims 22 to 39.

42. An apparatus, comprising means for performing the method of any one of claims 22 to 39.