METHOD AND DEVICES FOR A MEASUREMENT REPORT AND COMPUTER-READABLE MEDIUM

Description

FIELD OF THE INVENTION

[0001] The present disclosure generally relates to communication networks, and more specifically, to methods and apparatuses for measurement report and a computer-readable medium.BACKGROUND

[0002] This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

[0003] Communication service providers and network operators are continually facing challenges to deliver value and convenience to consumers by, for example, providing compelling network services and performance. With the rapid development of networking and communication technologies, a wireless network, such as a long term evolution (LTE) / fourth generation (4G) network or a new radio (NR) / fifth generation (5G) network, can support a dual connectivity (DC) operation of a terminal device. As such, the terminal device may be configured to utilize radio resources provided by two distinct schedulers, for example, located in different network nodes connected via an interface cross two communication networks. In this case, it may be desirable to achieve performance advantages of the DC while considering different configurations of the network nodes.

[0004] Document WO 2016 / 122255 A1 may be construed to disclose a method for transmitting control information by a base station in a communication system using a plurality of serving cells comprises transmitting is provided. The method includes a terminal, an identifier of a second serving cell identifying where control information regarding a first serving cell is transmitted, transmitting, to the terminal, a predetermined value of a carrier identifier used in the second serving cell, and transmitting the control information regarding the first serving cell including the camera identifier having the predetermined value through the second serving cell.

[0005] Document EP 3 051 916 A1 may be construed to disclose a communication device of handling a communication operation with a first base station and a second base station, which comprises a storage unit for storing instructions and a processing means coupled to the storage unit. The processing means is configured to execute the instructions stored in the storage unit. The instructions comprise performing a communication operation with the second base station via a radio bearer configured as a SCG bearer; detecting a radio link failure on a cell of the second base station or a SCG change failure; suspending the radio bearer and transmitting a SCG failure information message in response to the detection of the radio link failure to the first base station; receiving a radio resource control (RRC) message configuring the radio bearer as a MCG bearer from the first base station; and resuming the second radio bearer in response to the reception of the RRC message.

[0006] Document "Discussion on RRM measurements for SCG in dual connectivity", Huawei et al., 3GPP draft R2-141289 may be construed to disclose an evaluation on RRM measurement in dual connectivity. The following observations and proposals were made. Observation 1: For the change of PScell in the same frequency, current Event A6 can be reused. For the PScell removal, Event A2 can be reused; For the PScell addition, Event A4 can be reused; For the PScell change in the inter frequency: Event A2 / A4 can be reused; Observation 2: no change is needed on B1 and B2 for dual connectivity. Proposal 1: The principle of CA measurement shall be reused for SCells belonging to the SeNB. Proposal 2: There is no need to add any new events or change existing events to perform measurement for PScell in dual connectivity. Proposal 3: The number of measurement id is extended to 64 from 32, i.e. maxMeasId shall be 64. Proposal 4: The cell index shall be unified between the MeNB and the SeNB. Proposal 5: Only UE-specific measurement gap should be supported in dual connectivity. Proposal 6: the MeNB should send its SFN Initialisation Time to the SeNB via X2 interface, as well as the configured gapoffset, which will help the SeNB to calculate the actual time of measurement gaps.

[0007] Document "Consideration on remaining issues of SCG SRB for IWK", CATT, 3GPP draft R2.1704220 may be construed to disclose an evaluation on remaining issues of SCG SRB for LTE and NR interworking. The following proposals were made. Proposal 1: Not allow MN to request establishment of SCG SRB during IWK. Proposal 2: SN can remove SCG SRB when at least one SCG DRB is configured. Proposal 3: Not allow MN to remove SCG SRB when at least one SCG DRB is configured. Proposal 4: All NR RRC complete messages are mapped to the same SRB as the message initiating the procedure. Proposal 5: Measurement configuration from NR but measurement report to be reported to MN should not be allowed except for SCG failure case. Proposal 6: For SCG failure case, the measurement result should be carried in SCG failure message and should be forwarded to SN.

[0008] Document US 2015 / 0296438 A1 may be construed to disclose a communication device for handling a link failure, which comprises a storage unit for storing instructions and a processing means coupled to the storage unit. The processing means is configured to execute instructions stored in the storage unit. The instructions comprises communicating with a master base station via a first uplink (UL) carrier and a first downlink (DL) carrier; communicating with a secondary base station via a second UL carrier and a second DL carrier; detecting a link failure related to the secondary base station while communicating with the master base station; and transmitting information of the link failure and information of a measurement result related to the secondary base station to the master base station to report the link failure.SUMMARY

[0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0010] Communication networks supporting a DC operation of a terminal device may require coordination of a master network node (also called as master node (MN)) and a secondary network node (also called as secondary node (SN)) for the terminal device. For example, the MN may be informed that a connection from the terminal device to the SN is malfunctioning or broken, and accordingly get relevant measurement results from the terminal device. However, the MN may not be able to understand the measurement results collected according to the configuration of the SN. Therefore, there may be a need to provide an effective report mechanism for enabling the MN to interpret the measurement results associated with the SN.

[0011] According to the present disclosure, there are provided methods, apparatuses and a computer-readable medium according to the independent claims. Further developments are set forth in the dependent claims.

[0012] The present disclosure proposes a first solution for report of measurement results in a network supporting DC, which can make measurement results associated with a SN comprehensible to a MN, thereby reducing reconfiguration time of the terminal device and recovering from a failure related to the SN in a more efficient way.

[0013] Alternatively or in addition to the first proposed solution, the present disclosure proposes a second solution for report of measurement results in a network supporting DC, which can make measurement results associated with a MN or an old SN comprehensible to a new SN, thereby reducing reconfiguration time of the terminal device and connecting the terminal device to the new SN in a more efficient way.

[0014] Alternatively or in addition to the first proposed solution and / or the second proposed solution, the present disclosure proposes a third solution for report of measurement results in a network supporting DC, which requires some frequency information of a measurement object to be included in a report (such as a failure report or a measurement report) for the measurement object, thereby reducing configuration time and maintain a communication connection in a more efficient way.

[0015] Based at least in part on any of the first proposed solution, the second proposed solution and the third proposed solution, the present disclosuge proposes a fourth solution for measurement information in a network supporting DC, which requires frequency information of a measurement object to be included in measurement information about the measurement object, thereby reducing configuration time and maintain a communication connection in a more efficient way.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which: Fig.1 is a diagram illustrating an exemplary user plane (UP) architecture; Fig.2 is a diagram illustrating another exemplary UP architecture; Fig.3 is a diagram illustrating an exemplary control plane (CP) architecture; Fig.4 is a diagram illustrating another exemplary CP architecture; Fig.5A is a flowchart illustrating a method; Fig.5B is a flowchart illustrating a method; Fig.5C is a flowchart illustrating a method not encompassed by the wording of the claims; Fig.5D is a block diagram illustrating an apparatus; Fig.5E is a block diagram illustrating an Z apparatus; Fig.5F is a block diagram illustrating an apparatus not encompassed by the wording of the claims; Fig.6A is a flowchart illustrating a method not encompassed by the wording of the claims; Fig.6B is a flowchart illustrating a Z method; Fig.6C is a flowchart illustrating a method not encompassed by the wording of the claims; Fig.6D is a block diagram illustrating an apparatus not encompassed by the wording of the claims; Fig.6E is a block diagram illustrating an apparatus; Fig.6F is a block diagram illustrating an apparatus not encompassed by the wording of the claims; Fig.7A is a diagram illustrating a failure procedure; Fig.7B is a flowchart illustrating a Z method; Fig.7C is a block diagram illustrating an apparatus; and Fig.8 is a block diagram illustrating an apparatus. DETAILED DESCRIPTION

[0017] The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

[0018] As used herein, the term "communication network" refers to a network following any suitable communication standards, such as new radio (NR), long term evolution (LTE), LTE-Advanced, wideband code division multiple access (WCDMA), high-speed packet access (HSPA), and so on. Furthermore, the communications between a terminal device and a network node in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), 4G, 4.5G, 5G communication protocols, and / or any other protocols either currently known or to be developed in the future.

[0019] The term "network node" refers to a network device in a communication network via which a terminal device accesses to the network and receives services therefrom. The network node may refer to a base station (BS), an access point (AP), a multi-cell / multicast coordination entity (MCE), a controller or any other suitable device in a wireless communication network. The BS may be, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gNodeB or gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth.

[0020] Yet further examples of the network node comprise multi-standard radio (MSR) radio equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, positioning nodes and / or the like. More generally, however, the network node may represent any suitable device (or group of devices) capable, configured, arranged, and / or operable to enable and / or provide a terminal device access to a wireless communication network or to provide some service to a terminal device that has accessed to the wireless communication network.

[0021] The term "terminal device" refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device may refer to a mobile terminal, user equipment (UE), or other suitable devices. The UE may be, for example, a subscriber station, a portable subscriber station, a mobile station (MS) or an access terminal (AT). The terminal device may include, but not limited to, portable computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, a mobile phone, a cellular phone, a smart phone, a tablet, a wearable device, a personal digital assistant (PDA), a vehicle, and the like.

[0022] As used herein, the terms "first", "second" and so forth refer to different elements. The singular forms "a" and "an" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "has", "having", "includes" and / or "including" as used herein, specify the presence of stated features, elements, and / or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. The term "based on" is to be read as "based at least in part on". The term "one embodiment" and "an embodiment" are to be read as "at least one embodiment". The term "another embodiment" is to be read as "at least one other embodiment". Other definitions, explicit and implicit, may be included below.

[0023] Wireless communication networks are widely deployed to provide various telecommunication services such as voice, video, data, messaging and broadcasts. To meet dramatically increasing network requirements on system capacity and data rates, one interesting option for communication technique development is to support DC operations in a wireless communication network.

[0024] For example, an evolved universal mobile telecommunications system (UMTS) terrestrial radio access network (E-UTRAN) can support DC operations, so that a multiple transmitter / receiver (Tx / Rx) UE in a radio resource control connected state (RRC_CONNECTED) may be configured to utilize radio resources provided by two distinct schedulers, for example, located in two eNBs (such as radio base stations) connected via a non-ideal backhaul over the X2 interface. The non-ideal backhaul implies that the transport of messages over the X2 interface between nodes may be subject to both packet delays and losses.

[0025] In general, eNBs involved in DC for a certain UE may assume two different roles: an eNB may either act as a master node (MN), also referred to as master eNB(MeNB), or act as a secondary node (SN), also referred to as secondary eNB(SeNB). According to a LTE DC solution, a UE may be connected to a MN and a SN. Accordingly, an eNB can act both as an MN and an SN at the same time, for different UEs.

[0026] Fig.1 is a diagram illustrating an exemplary UP architecture (an UP architecture as such is not encompassed by the wording of the claims). The exemplary UP architecture shown in Fig.1 may be applicable to a LTE DC scenario. Three types of radio protocol layers are shown for a MN and a SN, comprising a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer and a medium access control (MAC) layer. A radio protocol architecture which is used by a particular bearer may depend on how the bearer is setup.

[0027] As shown in Fig.1, three bearer types may exist: a master cell group (MCG) bearer, a secondary cell group (SCG) bearer and a split bearer. The term "group" is used since a MN and a SN can use carrier aggregation (CA) to configure multiple cells for both the MN and the SN. In the LTE infrastructure, the RRC is located in a MN and signaling radio bearers (SRBs) are always configured as MCG bearer type and therefore only use radio resources of the MN. When an eNB acts as a SN for a UE, the eNB in the LTE DC scenario may not have any RRC context of that UE and all such signaling are handled by a MN for the UE.

[0028] The UE may have a corresponding protocol architecture where the UE is able to send and receive RRC messages over SRBs towards the MN, whereas data traffic over data radio bearers (DRBs) can be carried over the allocated radio resources to the MN / SN or from the MN / SN.

[0029] Fig.2 is a diagram illustrating another exemplary UP architecture (an UP architecture as such is not encompassed by the wording of the claims). The exemplary UP architecture shown in Fig.2 may be applicable to a LTE-NR DC (also referred to as LTE-NR tight interworking) scenario or a NR DC scenario. Compared with the LTE DC scenario, in the scenario shown in Fig.2, the split bearer from a SN is introduced as SCG split bearer, in addition to the split bearer from a MN (which is shown as MCG split bearer in Fig.2). The SN in this particular case may be also referred to as secondary gNB (SgNB).

[0030] Fig.3 is a diagram illustrating an exemplary CP architecture (a CP architecture as such is not encompassed by the wording of the claims). The exemplary CP architecture shown in Fig.3 may be applicable to a NR / 5G DC scenario. Compared with the LTE DC scenario, in the scenario shown in Fig.3, SRB may not always be configured as MCG bearer type and the split bearer for RRC is introduced as split SRB for a MN and a SN. In addition, a direct RRC from the SN is introduced as SCG SRB or direct SRB.

[0031] From Fig.2 and Fig.3, it can be seen that separate SRBs are supported both from the MN and the SN. This means that a UE can receive signaling messages, such as RRC messages both from the MN and the SN. Thus, there may be two RRC instances responsible for controlling the UE, one directed from the MN and another from the SN. In this circumstance, the UE needs to terminate RRC signaling from two instances.

[0032] The motivation for introducing such multiple RRC instances in NR DC, and in particular for LTE-NR DC, is that the MN and the SN may partly be autonomously responsible for the control of radio resources. For example, the MN may allocate resources from some spectrum using LTE, while the SN may be responsible for configuring and allocating resources from some other spectrum which uses NR. As challenges for allocating resources in LTE and NR may differ substantially (for example, since NR might be allocated in a spectrum where beam-forming is highly desirable, while LTE might be allocated in a spectrum with good coverage but with very congested resources), it is important that the SN has some level of autonomy to configure and manage the UE on resources associated with the SN. On the other hand, the overall responsibility for connectivity to the UE would likely be at the MN, so the MN may have the overall responsibility, for example, for mobility, state changes of the UE, and for meeting quality of service demands of the UE, etc.

[0033] The MN and the SN may be network nodes that use LTE (4G) or NR (5G) radio access technologies. They may both support the same technology, or they may support different technologies. In an exemplary scenario, the MN uses LTE and is connected to the evolved packet core (EPC), while the SN uses NR and is not connected directly to the core-network. All traffics to / from the UE are carried via the MN from / to the EPC. This scenario is also known as non-stand-alone NR. It will be appreciated that there may be other scenarios where the MN and the SN may apply or support various radio interface technologies. For example, the MN may support LTE or NR, while the SN may support LTE or NR. Other technologies could also be used over the radio interface.

[0034] Fig.4 is a diagram illustrating another exemplary CP architecture (a CP architecture as such is not encompassed by the wording of the claims). In this embodiment of LTE-NR tight interworking, a UE is connected to multiple network nodes, e.g. a MeNB supporting LTE and a SgNB supporting NR (which are shown as MN and SN respectively in Fig.4). The MeNB and the SgNB may respectively have a level of autonomy for configuring and controlling the UE with regards to its radio resources, which may be reflected by the support of multiple RRC instances. The configuring and controlling can take place using a signaling protocol such as a RRC protocol. Alternatively, the configuring and controlling could be implemented, for example, using a MAC protocol.

[0035] In Fig.4, the protocols of the MeNB and the SgNB both terminate the RRC protocols of LTE and NR, respectively. As can be seen, the UE therefore terminates both an LTE RRC and an NR RRC protocol instance. Other protocol instances such as PDCP, RLC, MAC, physical (PHY) layer protocol instances are also schematically shown in Fig.4. On the other hand, a control signaling mechanism (in addition to the direct SRB and split SRBs) using embedded RRC in the LTE-NR tight interworking is also illustrated in Fig.4. The embedded RRC may be employed when the direct SRB is not available and the SgNB has to configure the UE that affects only the NR leg.

[0036] For example, the SgNB may send the RRC message to the MeNB via the X2 interface, which the MeNB then embeds in its own RRC message and sends via SRB1 (which could be a split SRB or MCG SRB). The UE will then be able to extract the embedded NR RRC message from the container MeNB RRC message and apply the configurations on the NR leg. In the uplink (UL) direction, the UE may embed the NR RRC messages in an LTE RRC message towards the MeNB, and the MeNB can extract the embedded NR RRC message from this LTE RRC message and forward it to the SgNB.

[0037] In a network scenario supporting DC, a SCG failure may be triggered for a number of reasons, for example, when the UE fails to maintain a connection to the SN (such as a connection via the cells of the SN) in which case the UE monitors the link quality for the primary secondary cell (PSCell) of the SCG. Alternatively, a SCG failure may be triggered by a failure of a change of SCG. One or more procedures for initiating and executing SCG failure recovery may be performed in response to a SCG failure.

[0038] Through a SCG failure recovery procedure, the network may be notified that the connection to the SN is malfunctioning or broken. This may be achieved by sending a SCGFailureInformation message to provide SCG radio link failure information from the UE to the MN. Then the MN can try, for example, to recover or re-establish a new SCG via the previous SN, or through a different SN. For example, the MN may need to assign a new PSCell.

[0039] For example, the SCGFailureInformation message may be a LTE RRC message that contains various pieces of information of relevance for controlling the connection to the UE, including measurement results as configured by the MN. The message also may include a cause flag carrying information about the reason for triggering the message.

[0040] According to an exemplary embodiment of LTE RRC, the measurement results included in the SCGFailureInformation message may contain two categories of measurement results: measResultServFreqList, which comprise measurement results of serving frequencies; and measResultNeighCells, which comprise measurement results of non-serving frequencies.

[0041] For measurement results reported in measResultServFreqList, the information which can be reported for each serving frequency may comprise: a UE-specific index of a serving cell (which may be assigned by the network via dedicated signaling), and reference signal receiving power / reference signal receiving quality (RSRP / RSRQ) for the serving cell; and a physical cell identifier (PCI) and RSRP / RSRQ for the best neighbor of the serving cell on the same frequency.

[0042] For measurement results reported in measResultNeighCells, the information which can be reported for each non-serving frequency may comprise: the carrier frequency; and a PCI and RSRP / RSRQ for each cell in the best measured cells on that frequency.

[0043] In accordance with an exemplary embodiment, the best measured cell may comprise a cell which is measured or detected with the best link quality. Alternatively or additionally, the best measured cell may comprise other suitable cell determined according to a predefined measurement evaluation criterion.

[0044] In an exemplary SCG failure case, the UE can maintain the current measurement configurations from both the MN and the SN (for example, the UE would not take autonomous action) and the UE may continue measurements based on the configuration from the MN. The UE includes in the SCGFailureInformation message the measurement results available according to current measurement configurations of both the MN and the SN. It is advantageous that the MN can handle the SCGFailureInformation and then decide to keep, change or release the SN / SCG. Correspondingly, the measurement results according to the SN configuration can be forwarded to the old SN and / or to a new SN. It is also desirable that the new SN can interpret the measurement results based on the configuration from the old SN.

[0045] In the LTE DC scenario, since all configurations (including CA / DC related) are coming from the MN, the MN is able to interpret all reported information including the association between cells, carriers and measurements. In the LTE-NR DC scenario, on the other hand, the SN also has the capability to configure the measurement results by itself. Thus the MN or another new SN may not be able to understand the measurement results according to the configuration from the old SN, especially if some identifiers are only locally unique. For example, a serving cell index of a SCell that was configured by the SN may be the same as that used by the MN. Also, even if there is no serving cell index confusion, the MN may not be able to know which frequency a reported cell in the measResultServFreqList is associated with. In the LTE DC case, since it is the MN that is responsible for configuration, it can keep a mapping of the frequency used by the SCells (whether they belong to the SCG or the MCG) with the serving cell index. However, the PCI included in the best neighbor information of a serving cell could not be used to identify the frequency, because the same PCI may be used by two cells operating on different frequencies.

[0046] Therefore, it is desirable to introduce an effective solution to enable a MN and a new SN to interpret measurement results based on the configuration from the old SN. According to the claimed invention, a UE includes, in a report (such as a SCG failure message) sent to a MN, some information enabling the MN (or a potentially new SN) to interpret / understand measurement results and potentially act upon receiving the report. The information included in the report indicates the association between the SN associated cells and / or frequency (the latter required by the claimed invention) and the measurement results. In this way, it may be identified where the failure has occurred, thereby solving any potential ambiguity.

[0047] The first proposed solution in the present disclosure is applicable to a network context where a UE supporting DC is connected to two network nodes, namely an MN and SN. Thus the UE is configured by two separate control entities (such as RRC termination points) to perform measurements for radio resource managements. Separate reports of measurement results may be sent to the MN and the SN, respectively. In an exemplary embodiment, the MN may use the LTE technology, and the SN may use the NR technology.

[0048] It is noted that some embodiments of the present disclosure are mainly described in relation to LTE or NR specifications being used as examples for certain exemplary network configurations and system deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto.

[0049] According to the claimed invention, the UE undergoes a failure towards the SN (such as a SCG failure). There may be different causes for the failure, such as detected bad radio connectivity to the PSCell towards the SN. Triggered by the failure, and through a recovery procedure, the UE can inform the MN of the SCG failure, for example, by sending a SCG failure message to the MN. The SCG failure message may comprise measurement information. For instance, the measurement information may comprise measurement results configured both by the MN RRC and the SN RRC.

[0050] According to an exemplary embodiment, the measurement results associated with the SN serving frequencies can be either treated as serving frequency or non-serving frequency from the UE perspective when sending the SCG failure message such as a SCGFailureInformation message. In an exemplary embodiment where the SN serving frequencies are treated as non-serving frequencies by the UE, frequency information associated with the measurements results can be naturally included in the SCG failure message, as described with respect to measResultNeighCells in LTE RRC. With the additional frequency information such as frequency position and carrier number, the MN and optionally the new SN can understand the measurement results according to the configuration from the old SN.

[0051] In another exemplary embodiment where the SN serving frequencies are treated as serving frequencies by the UE, there may be three alternative schemes. In scheme I, frequency information also may be reported for measurement results of each serving frequency configured by the SN. In scheme II, measurement results of serving frequencies may be reported in two separate parts or lists, such as a list of measurement results of MN configured serving frequencies, and another list of measurement results of SN configured serving frequencies. In this way, there is no need for the MN and the SN to perform coordination about how to allocate serving cell indexes, since the MN can distinguish the measurement results of SN serving frequencies from the measurement results of MN serving frequencies although no frequency information of SN serving frequencies is reported. In scheme III, the MN and the SN may perform coordination about how to allocate serving cell indexes, so that the same cell index cannot be used by the MN and the SN. As such, measurement results of serving frequencies may be reported as in legacy LTE.

[0052] For schemes II and III, the MN may not be able to interpret the measurement results based on the configuration from the SN, as the MN does not know the frequency information associated with those measurement results. However, the MN could recognize the measurement results based on the configuration from SN, for example, by either the different lists of measurement results as set by the UE in scheme II, or the globally unique serving cell index as coordinated by the MN and SN in scheme III. In this regard, the MN may ask the SN to inform it the mapping from the serving cell index to the SN configured frequency.

[0053] By applying the first proposed solution in the present disclosure, performance of a communication network supporting DC, such as LTE-NR DC, may be significantly improved, as the MN and potentially new SN can understand all the measurement results included in a report such as the SCGFailureInformation message from the UE. Then the MN and / or the new SN can reconfigure the UE to connect to the network appropriately. Otherwise, new measurement configuration and new measurement may be required between the UE and the network, which may delay the procedure to recover from a SCG failure.

[0054] Fig.5A is a flowchart illustrating a method 510 according to some embodiments of the present disclosure (the shown method does not comprise all of the features required by the claimed invention). The method 510 illustrated in Fig.5A is performed by an apparatus implemented at a terminal device or communicatively coupled to a terminal device. In accordance with an exemplary embodiment, the terminal device may be served by a communication system supporting DC, for example, a LTE-NR tight interworking system where a LTE network node is a MN for the UE and a NR network node is a SN for the UE (also referred to as EN-DC), a LTE-NR DC system where a NR network node is a MN for the UE and a LTE network node is a SN for the UE (also referred to as NE-DC; not encompassed by the wording of the claims), a NR-NR DC system where both MN and SN are NR network nodes, or any other suitable system supporting DC.

[0055] According to the exemplary method 510 illustrated in Fig.5A, the terminal device is connected to a MN and a SN. The terminal device obtains measurement information based at least in part on configurations of the MN and the SN, as shown in block 512. For example, the measurement information may comprise measurement results associated with serving frequencies configured by the MN and the Z SN (the latter required by the claimed invention).

[0056] Both MN and SN configure the UE, for example, by specifying what to measure, how to measure and how to report. When there is no radio link failure, the measurement results according to the configuration of the MN may be sent to the MN, and the measurement results according to the configuration of the SN may be sent to the SN. However, a failure related to the SN may occur due to various reasons. In response to a failure related to the SN, the terminal device transmits a report including the measurement information to the MN, as shown in block 514. For example, when there is a radio link failure such as a SCG failure, the UE may send to the MN a SCGFailureInformation message which includes the available measurement results according to the configurations of both MN and SN.

[0057] Fig.5B is a flowchart illustrating a method 520 according to some embodiments of the present disclosure (the shown method does not comprise all of the features required by the claimed invention). The method 520 illustrated in Fig.5B is performed by an apparatus implemented at a network node. In accordance with an exemplary embodiment, the network node may comprise a MN supporting LTE, 5G NR or other proper radio technologies, such as a master eNB (MeNB) or a master gNB(MgNB).

[0058] Corresponding to operations of the exemplary method 510 as illustrated in Fig.5A, the MN in the exemplary method 520 receives a report including measurement information from a terminal device, as shown in block 522. The terminal device may be connected to the MN in a first network and a SN in a second network. The measurement information is based at least in part on configurations of the MN and the SN. In an exemplary embodiment, the first network may comprise a LTE network, and the second network comprises a NR network. Alternatively, the first network may comprise a NR network, and the second network may comprise a LTE network (not encompassed by the wording of the claims) or a NR network. It will be appreciated that other suitable radio access technologies also may be applied when performing the exemplary methods.

[0059] In block 524, the MN can Z interprets the measurement information. For example, the MN can extract measurement results associated with serving frequencies configured by the MN and the SN. According to an exemplary embodiment, the measurement information may be interpreted for enabling a reconfiguration procedure for the terminal device. For example, the reconfiguration procedure may comprise: determining another SN for the terminal device, based at least in part on the measurement information, and transmitting at least part of the measurement results associated with the serving frequencies configured by the SN to the another SN.

[0060] In accordance with an exemplary embodiment, the report transmitted from the terminal device to the MN may comprise a failure message (such as a SCGFailureInformation message or other suitable signaling message) for informing the MN of a failure related to the SN.

[0061] According to the claimed invention, the report indicates an association between a serving frequency configured by the SN and a measurement result associated with the serving frequency. For example, the association may be indicated by an indication of the serving frequency configured by the SN. Alternatively, the association may be indicated by an index of a serving cell on the serving frequency configured by the SN, where the index of the serving cell may have a mapping relationship with the serving frequency.

[0062] According to an exemplary embodiment where the association is indicated by the indication of the serving frequency configured by the SN, the UE may treat the serving frequency configured by the SN (for example, all the frequencies used by the SCG cells) as the non-serving frequency. In this way, the UE includes frequency information of the serving frequency or carrier configured by the SN in the report transmitted to the MN. The frequency information comprises an exact frequency position (for example, within a carrier frequency) where one or more resource blocks are transmitted. The frequency position could either be at the center of a carrier or in a different frequency position shifted from the center. The frequency information comprises some carrier information, in particular a carrier number (such as a value of the absolute radio frequency channel number (ARFCN); required by the claimed invention) and an additional frequency shift.

[0063] In the case where the serving frequency configured by the SN is treated as the non-serving frequency, the measurement result associated with the serving frequency configured by the SN may comprise: an identifier (such as PCI) of a best measured cell on the serving frequency, and an indication of reference signal quality (such as RSRP / RSRQ) for the best measured cell. With these information included in the report, the MN may be able to interpret the received measurement results, regardless of whether the measurement results are associated with the MN or the SN. The report of the measurement results may comprise a SCGFailureInformation message of which the structure may not need to be changed.

[0064] It is noted that there may be some loss of information in this case compared with the case where the serving frequency configured by the SN is treated as the serving frequency. For the serving frequency, the UE may include the PSCell and SCell frequencies in the serving frequency part of a measurement report, and also include measurement results of the best neighbor for each cell. However, when treating the PSCell and SCell frequencies as the non-serving frequency part of the measurement report, only the information about the best measured cell on each frequency may be included in the report.

[0065] In view of this, it may be possible to modify the SCGFailureInformation message so that the serving cells of the SCG is included in the non-serving frequency part while the additional neighbor information also may be included just like the way as in the serving frequency part. In addition to the identifier (such as PCI) of a best measured cell on the serving frequency and the indication of reference signal quality (such as RSRP / RSRQ) for the best measured cell, the measurement result associated with the serving frequency configured by the SN may further comprise an identifier (such as PCI) of a best neighbor of the best measured cell, and an indication of reference signal quality (such as RSRP / RSRQ) for the best neighbor.

[0066] Where the association is indicated by the indication of the serving frequency configured by the SN, the UE also may treat the serving frequency configured by the SN as the serving frequency. In this case, the UE may further include some frequency information associated with the serving frequency in the report of measurement results, in order to enable other nodes (such as the MN or a new SN to which the UE may be reconfigured) different from the previously failed SN to interpret these measurement results and / or failure related information (and possible take actions upon the reception of the report).

[0067] For the case where the serving frequency configured by the SN is treated as the serving frequency, the measurement result associated with the serving frequency configured by the SN may comprise: an index of a serving cell on the serving frequency, an indication of reference signal quality (such as RSRP / RSRQ) for the serving cell, an identifier (such as PCI) of a best neighbor of the serving cell, and an indication of reference signal quality (such as RSRP / RSRQ) for the best neighbor.

[0068] In order to make the MN (and optionally the new SN where the measurement results may be later forwarded to) be able to interpret the measurement results even they are based on the configuration from the old SN, the structure of the measurement report such as a SCGFailureInformation message may require enhancements to include the frequency information associated with the serving frequency configured by the SN. For example, a new SCGFailureInformation message may be designed as below by adding a field to indicate the frequency information of the SN configured serving frequency, as shown in the box (the ARFCN-ValueEUTRA according to the box is not encompassed by the wording of the claims).

[0069] It is noted that the frequency information field may be an optional field because the frequency information may not be needed for the serving cells of the MCG as the MN is already aware of it. It will be realized that although the term "ARFCN-ValueEUTRA" is used here, other suitable term also may be used, which may depend on the involved radio techniques. For example, if the SN is associated with the NR, the reported frequency information is related to the NR. Thus, the term such as "ARFCN-ValueNR" is used for the frequency information field, as according to the claimed invention.

[0070] The , frequency information field indicates a frequency position (for example, within a carrier frequency) where one or more radio resource blocks are transmitted. A possible parameter or value of the frequency information field may indicate the center of a carrier or a different frequency position shifted from the center. The NR frequency information comprises the carrier information Z (according to the claimed invention a carrier number represented by ARFCN-ValueNR) and an additional frequency shift. As such, the size of the report may be increased. However, it may not be an issue because, for example, the report is transmitted over the MN, which in principle still has a good link, and failure events are rare and thus may not occur constantly (for example, compared to ordinary measurement reports).

[0071] According to the exemplary embodiment where the association between the SN configured serving frequency and the measurement result is indicated by the index of the serving cell which has a mapping relationship with the serving frequency, the UE may treat the serving frequency configured by the SN as the serving frequency. Thus, there may be no need to report the interference information corresponding to the measurement results associated with the SN configured serving frequency to the MN. In this case, the measurement results associated with the serving frequencies configured by the MN may be separated in the report from the measurement results associated with the serving frequencies configured by the SN. Accordingly, the index of the serving cell may be allocated by the SN without coordination with the MN.

[0072] For example, a new SCGFailureInformation message may be designed as below by dividing the measurement results into two parts: one for the serving frequencies configured by the MN, and another for the serving frequencies configured by the SN, as shown in the box.

[0073] Similarly, the frequency information field may be an optional field because the frequency information may be not needed for the serving cells of the MCG as the MN is already aware of it. For the measurement results associated with the serving frequency configured by the SN, the MN (and optionally a new SN) may be able to distinguish them from the measurement results associated with the serving frequency configured by the MN, since the two types of measurement results are separable in the report.

[0074] Although the MN can recognize the measurement results associated with the SN, it may not be able to interpret them because these measurement results are based on the configuration from the SN. In this regard, the MN may request the SN, for example, through an existing and / or newly designed signaling, to inform it about information indicating the mapping from a serving cell index to a serving frequency. In this case, the size of the SCGFailureInformation message may not be increased, but a signaling communication between the MN and the SN may be needed to facilitate the mapping from the serving cell index to the serving frequency.

[0075] Alternatively or additionally, the MN may get from the SN some information indicating the mapping from a serving cell index to a serving frequency through other processes, without requesting it from the SN purposely. For example, the addition and removal of SCells of the SCG, though to be decided by the SN, may have still to be coordinated with the MN because of the limitation of the total number of carriers that the UE can support. In addition, the UE may not support all possible band combinations between LTE and NR carriers. Thus the cell index to frequency mapping for the SCG cells can be implicitly gathered as part of such coordination process.

[0076] Where the association between the SN configured serving frequency and the measurement result is indicated by the index of the serving cell which has a mapping relationship with the serving frequency, the index of the serving cell may be allocated by coordination of the MN and the SN. For example, the MN and the SN may coordinate the allocation of serving cell indexes to make sure the same serving cell index would not be used by both the MN and the SN. In this case, the index of the serving cell may be the globally unique index, and thus there may be no need to divide the measurement results into different parts in the report, even though no relevant frequency information is reported to the MN. In other words, the UE may treat the serving frequency configured by the SN as the serving frequency and report the measurement results just as in legacy LTE.

[0077] Through the globally unique cell index, the MN can recognize the measurement results associated with the SN, although it may not be able to interpret them because these measurement results are based on the configuration from the SN. In this case, the mapping relationship between the index of the serving cell and the serving frequency configured by the SN may be gathered by the MN from the SN. For example, the MN may request the SN to inform it about information indicating the mapping from a serving cell index to a serving frequency. Alternatively or additionally, the cell index to frequency mapping for the SCG cells can be implicitly gathered as part of one or more previous coordination processes between the MN and the SN.

[0078] The measurement information obtained by the terminal device may further comprise measurement results associated with beams used by the MN and the SN. For example, the SCGFailureInformation message may be extended to include beam measurement results even though the high level structure of the SCGFailureInformation message may not be changed.

[0079] Fig.5C is a flowchart illustrating a method 530 according to some embodiments not encompassed by the wording of the claims. The method 530 illustrated in Fig.5C may be performed by an apparatus implemented at a network node or communicatively coupled to a network node. In accordance with an exemplary embodiment, the network node may comprise a SN supporting LTE, 5G NR or other proper radio technologies, such as a secondary eNB (SeNB) or a secondary gNB(SgNB).

[0080] Corresponding to operations of the exemplary method 520 as illustrated in Fig.5B, the SN in the exemplary method 530 determines an association between a serving frequency configured by the SN and a measurement result associated with the serving frequency, as shown in block 532. For example, the association may comprise a mapping relationship between the serving frequency configured by the SN and an index of a serving cell on the serving frequency. The serving frequency may be configured for a terminal device such as a UE which is connected to a MN and the SN.

[0081] In block 534, the SN provides the association to the MN for interpreting measurement information related to the terminal device. For example, the association may be provided as requested by the MN, or in a coordination process between the MN and the SN. As described previously, the measurement information may be based at least in part on configurations of the MN and the SN. Accordingly, the measurement information may comprise at least the measurement result associated with the serving frequency configured by the SN. Thus, the MN may be able to interpret the measurement information, for example, by utilizing the association between the SN configured serving frequency and the measurement result associated with the serving frequency.

[0082] The first proposed solution according to one or more exemplary embodiments can enable a MN to be able to understand the content of measurement information in a report from a UE. Taking the advantage of the first proposed solution makes it possible to use measurement results by the MN to determine another node, if any, as a new SN. If it is determined to designate another node as a new SN for the UE, the MN can then forward some relevant information extracted from the measurement information related to the old SN carriers / frequencies towards the new SN, so that the new SN could use it to choose the PSCell as well as the SCG SCells for the UE.

[0083] Fig.5D is a block diagram illustrating an apparatus 540 (in the shown form not encompassed by the wording of the claims). As shown in Fig.5D, the apparatus 540 may comprise an obtaining unit 541 and a transmitting unit 542. In an exemplary embodiment, the apparatus 540 may be implemented at a terminal device such as a UE. The obtaining unit 541 may be operable to carry out the operation in block 512, and the transmitting unit 542 may be operable to carry out the operation in block 514. Optionally, the obtaining unit 541 and / or the transmitting unit 542 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0084] Fig.5E is a block diagram illustrating an apparatus 550 Z (in the shown form not encompassed by the wording of the claims). As shown in Fig.5E, the apparatus 550 may comprise a receiving unit 551 and an interpreting unit 552. In an exemplary embodiment, the apparatus 550 may be implemented at a network node such as a MN. The receiving unit 551 may be operable to carry out the operation in block 522, and the interpreting unit 552 may be operable to carry out the operation in block 524. Optionally, the receiving unit 551 and / or the interpreting unit 552 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0085] Fig.5F is a block diagram illustrating an apparatus 560 (not encompassed by the wording of the claims). As shown in Fig.5F, the apparatus 560 may comprise a determining unit 561 and a providing unit 562. In an exemplary embodiment, the apparatus 560 may be implemented at a network node such as a SN. The determining unit 561 may be operable to carry out the operation in block 532, and the providing unit 562 may be operable to carry out the operation in block 534. Optionally, the determining unit 561 and / or the providing unit 562 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0086] In a network scenario supporting DC, a MN may initiate a SN addition or SN change procedure for a UE. Thus, the UE may send to the MN some measurement information according to a measurement configuration based on the MN. When the MN gets the measurement information, it can decide which target SN to add in the case of SN addition or to change to in the case of SN change, and then forward relevant measurement information to the chosen target SN, so that the target SN can use the relevant measurement information to decide which cell would be the primary cell and which cells (if any) would be the secondary cells.

[0087] Similarly, a SN also may initiate a SN change procedure for a UE. Thus, the UE may send to the SN some measurement information according to a measurement configuration based on the SN. When the SN gets the measurement information, it can decide which new SN to change to, and then forward relevant measurement information to the chosen new SN via the MN, so that the new SN can use the relevant measurement information to decide which cell would be the primary cell and which cells (if any) would be the secondary cells.

[0088] In LTE DC, the communication of the measurement information may be performed via the SCG configuration information during a SN addition procedure. Some information such as ScellToAddModListSCG containing cell identifications of the secondary cells, for example, an index of a serving cell to frequency / physical cell identifier (PCI) mapping, also may be included in the SN addition procedure.

[0089] For the case of LTE-NR interworking, it may not be necessary to have ScellToAddModListSCG because it is up to the SN to decide the secondary cells to add. Thus the new SN may not be able to understand the measurement results according to the configuration from the MN or the old SN, especially if some identifiers are only locally unique. For example, a serving cell index of a SCell that was configured by the MN may be the same as that used by the new SN. Also, even if there is no serving cell index confusion, the new SN may not be able to know which frequency is associated with the measurement result. In the LTE DC case, since it is the MN that is responsible for configuration, it can keep a mapping of the frequency used by the SCells (whether they belong to the SCG or the MCG) with the serving cell index.

[0090] Therefore, it may be desirable to introduce an effective solution to enable the new SN to interpret measurement information based on the configuration from the MN or the old SN. In the second proposed solution according to some exemplary embodiments (partly not encompassed by the wording of the claims), a report including measurement information associated with the UE is transmitted to the new SN. The report indicates an association between the frequency / PCI information (the latter is not encompassed by the wording of the claims) and the measurement results to enable the new SN to interpret / understand the reported measurement information. The report indicates additional frequency information such as frequency position and carrier number, thus the new SN can understand the measurement results according to the configuration from the MN and / or the old SN.

[0091] The second proposed solution in the present disclosure is applicable to a network context where a UE is connected to two network nodes, namely MN and a SN. The UE is configured by two separate control entities (such as RRC termination points) to perform measurements for radio resource managements. Separate reports of measurement results may be sent to the MN and the SN, respectively. In an exemplary embodiment, the MN may use the LTE technology, and the SN uses the NR technology.

[0092] By applying the second proposed solution in the present disclosure, performance of a communication network such as LTE-NR interworking network may be significantly improved, as the new SN can understand all the measurement results from the UE. Then the UE may be connected to the new SN appropriately.

[0093] Fig.6A is a flowchart illustrating a method 610 according to some embodiments (in this form of a method performed by an MN not encompassed by the wording of the claims). The method 610 illustrated in Fig.6A may be performed by an apparatus implemented at a network node or communicatively coupled to a network node. In accordance with an exemplary embodiment, the network node may comprise a MN supporting LTE, 5G NR or other proper radio technologies, such as a master eNB (MeNB) or a master gNB(MgNB).

[0094] According to the exemplary method 610 illustrated in Fig.6A, the MN can obtain measurement information associated with a terminal device which is connected at least to the MN, as shown in block 612. For example, the terminal device may be served by a communication system supporting DC, such as a LTE-NR tight interworking system where a LTE network node is a MN for the UE and optionally a NR network node is a SN for the UE (also referred to as EN-DC), a LTE-NR DC system where a NR network node is a MN for the UE and optionally a LTE network node is a SN for the UE (also referred to as NE-DC), a NR-NR DC system where the MN and optionally the SN are NR network nodes, or any other suitable system supporting DC.

[0095] In accordance with an exemplary embodiment, the MN can transmit a report including the measurement information to a first SN, as shown in block 614. The report may indicate frequency information associated with the measurement information.

[0096] In accordance with an exemplary embodiment, the transmission of the report may be in response to a determination of the first SN. In an exemplary embodiment, the MN may initiate the determination of the first SN. For example, the MN may initiate a SN addition procedure for the terminal device, so that the terminal device may be connected to the first SN determined by the MN.

[0097] In accordance with an exemplary embodiment, the terminal device may be connected to the MN and a second SN. The MN may initiate a SN change procedure for the terminal device, so that the terminal device may change to be connected to the first SN determined by the MN from the second SN.

[0098] In accordance with an exemplary embodiment where the determination of the first SN is initiated by the MN, the measurement information may be obtained from the terminal device. The measurement information may comprise a measurement result associated with a serving frequency configured by the MN.

[0099] Optionally, in the case that the terminal device is connected to the MN and the second SN, the second SN may initiate the determination of the first SN. For example, the second SN may initiate a SN change procedure for the terminal device, so that the terminal device may change to be connected to the first SN from the second SN.

[0100] In accordance with an exemplary embodiment where the determination of the first SN is initiated by the second SN, the measurement information may be obtained by the MN from the second SN. For example, the second SN can get the measurement information from the terminal device. Thus, the measurement information may comprise a measurement result associated with a serving frequency configured by the second SN. In this case, the operation of obtaining the measurement information associated with the terminal device as shown in block 612 may further comprise obtaining the frequency information associated with the measurement information from the second SN.

[0101] In accordance with an exemplary embodiment, the frequency information may comprise at least one of: an indication of a serving frequency and a physical cell identifier (PCI).

[0102] Fig.6B is a flowchart illustrating a method 620 according to some embodiments of the present disclosure. The method 620 illustrated in Fig.6B may be performed by an apparatus implemented in a network node. In accordance with an exemplary embodiment, the network node may comprise a SN supporting LTE, 5G NR (the latter is required by the claimed invention) or other proper radio technologies, such as a secondary eNB (SeNB) or a secondary gNB(SgNB)..

[0103] Corresponding to operations of the exemplary method 610 as illustrated in Fig.6A, the SN in the exemplary method 620 may refer to the first SN which is determined by the MN or the second SN. As shown in block 622, the first SN receives a report including measurement information from a MN. The measurement information is associated with a terminal device which is connected at least to the MN. The report indicates frequency information (for example, an indication of a serving frequency and / or a PCI) associated with the measurement information. Thus, the first SN can interpret the measurement information, as shown in block 624.

[0104] In accordance with an exemplary embodiment, the reception of the report may be in response to a determination of the first SN. Considering that the terminal device is connected to the MN and a second SN, the measurement information may comprise a measurement result associated with at least one of serving frequencies configured by the MN and the second SN (according to the claimed invention the measurement information comprises a measurement result associated with a serving frequency configured by the second SN). On the other hand, the determination of the first SN may be initiated by the MN or the second SN.

[0105] The frequency information comprises an exact frequency position (for example, within a carrier frequency) where one or more resource blocks are transmitted. The frequency position could either be at the center of a carrier or in a different frequency position shifted from the center. Z According to the claimed invention, the frequency information comprises carrier information, in particular a carrier number (according to the wording of the claims a value of the absolute radio frequency channel number (ARFCN)) and for example an additional frequency shift.

[0106] Fig.6C is a flowchart illustrating a method 630 according to some embodiments not encompassed by the wording of the claims. The method 630 illustrated in Fig.6C may be performed by an apparatus implemented at a network node or communicatively coupled to a network node. In accordance with an exemplary embodiment, the network node may comprise a SN supporting LTE, 5G NR or other proper radio technologies, such as a secondary eNB (SeNB) or a secondary gNB(SgNB).

[0107] Corresponding to operations of the exemplary method 620 as illustrated in Fig.6B, the SN in the exemplary method 630 may refer to the second SN to which the terminal device is connected. As shown in block 632, the second SN can obtain measurement information associated with a terminal device which is connected to a MN and the second SN. For example, the measurement information may be obtained from the terminal device and comprise a measurement result associated with a serving frequency configured by the second SN.

[0108] In accordance with an exemplary embodiment, the second SN may transmit a report including the measurement information to the MN, as shown in block 634. For example, the report may indicate frequency information associated with the measurement information.

[0109] In accordance with an exemplary embodiment, the transmission of the report may be in response to a determination of a first SN. For example, the determination of the first SN may be initiated by the second SN.

[0110] The second proposed solution according to one or more exemplary embodiments can enable a new SN to be able to understand the content of measurement information from a UE. Taking the advantage of the second proposed solution makes it possible to use measurement results by the new SN properly. If it is determined to designate a new SN for the UE, the MN can forward some relevant measurement information towards the new SN, so that the new SN could use it to choose the PSCell as well as the SCG SCells for the UE.

[0111] Fig.6D is a block diagram illustrating an apparatus 640 according to another embodiment not encompassed by the wording of the claims. As shown in Fig.6D, the apparatus 640 may comprise an obtaining unit 641 and a transmitting unit 642. In an exemplary embodiment, the apparatus 640 may be implemented at a network node such as a MN. The obtaining unit 641 may be operable to carry out the operation in block 612, and the transmitting unit 642 may be operable to carry out the operation in block 614. Optionally, the obtaining unit 641 and / or the transmitting unit 642 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0112] Fig.6E is a block diagram illustrating an apparatus 650 according to some embodiments (in the shown form not encompassed by the wording of the claims). As shown in Fig.6E, the apparatus 650 may comprise a receiving unit 651 and an interpreting unit 652. In an exemplary embodiment, the apparatus 650 may be implemented at a network node such as a first SN. The receiving unit 651 may be operable to carry out the operation in block 622, and the interpreting unit 652 may be operable to carry out the operation in block 624. Optionally, the receiving unit 651 and / or the interpreting unit 652 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0113] Fig.6F is a block diagram illustrating an apparatus 660 according to some embodiments not encompassed by the wording of the claims. As shown in Fig.6F, the apparatus 660 may comprise an obtaining unit 661 and a transmitting unit 662. In an exemplary embodiment, the apparatus 660 may be implemented at a network node such as a second SN. The obtaining unit 661 may be operable to carry out the operation in block 632, and the transmitting unit 662 may be operable to carry out the operation in block 634. Optionally, the obtaining unit 661 and / or the transmitting unit 662 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0114] In accordance with the claimed invention, the enhancement to the frequency information in a report (such as a failure report or a measurement report) is implemented by adding some information about Option I and Option II. The information about Option I comprises a frequency location where the synchronization signal / physical broadcast channel (SS / PBCH) block is transmitted. The information about Option II comprises a reference location from which the channel state information-reference signal (CSI-RS) frequency location can be derived.

[0115] For the information about Option I, one possibility is to encode that with the synchronization raster channel numbering, which is also known as global synchronization channel number (GSCN). Another possibility is to encode that with the channel raster channel numbering, which is also known as absolute radio frequency channel number (ARFCN; required by the claimed invention). A further possibility is to encode that with one or multiple offsets from a reference frequency, which can be the GSCN or the ARFCN. Compared with the information about Option I, the information about Option II is the so-called frequency location of point A.

[0116] In accordance with an exemplary embodiment, the information about at least one of Option I and Option II may be included as frequency information in a failure / measurement report, regardless of which type of measurements are to be included in the failure / measurement report.

[0117] The information about Option I is included as frequency information in a failure / measurement report, if a terminal device such as a UE is intended to include SS / PBCH block based measurements in the failure / measurement report.

[0118] The information about Option II is included as frequency information in a failure / measurement report, if a terminal device such as a UE is intended to include CSI-RS based measurements in the failure / measurement report. In this case, additional CSI-RS frequency information may also be included, for example, exact frequency resources with which the CSI-RS resources are being transmitted.

[0119] Fig.7A is a diagram illustrating a failure procedure which can be used in embodiments of the present disclosure. The purpose of this procedure is to inform an Evolved Universal Terrestrial Radio Access Network (EUTRAN) or NR MN about a SCG failure a UE has experienced, for example, a SCG radio link failure, a SCG change failure, a SCG configuration failure for RRC message on SRB3, a SCG integrity check failure and exceeding the maximum uplink transmission timing difference.

[0120] In accordance with the exemplary embodiment, the UE may initiate the procedure to report SCG failures to a radio access network (RAN) when SCG transmission is not suspended and when one of the following conditions is met: upon detecting radio link failure for the SCG; upon reconfiguration with synchronization failure of the SCG; upon stopping uplink transmission towards the SCG's SpCell due to exceeding the maximum uplink transmission timing difference; upon SCG configuration failure; and upon integrity check failure indication from SCG lower layers.

[0121] According to an exemplary embodiment, in response to initiating the procedure, the UE may: suspend SCG transmission for all SRBs and DRBs; reset SCG-MAC; stop T304, if running; and if the UE is operating in EN-DC: initiate transmission of the SCGFailureInformation message, for example, as specified in 3GPP TS 36.331.

[0122] In accordance with an exemplary embodiment, the UE may set the SCG failure type as follows: if the UE initiates transmission of the SCGFailureInformation message to provide SCG radio link failure information: set the failure Type as the trigger for detecting SCG radio link failure; else if the UE initiates transmission of the SCGFailureInformation message to provide reconfiguration with sync failure information for an SCG: set the failureType as scg-ChangeFailure; else if the UE initiates transmission of the SCGFailureInformation message due to exceeding maximum uplink transmission timing difference: set the failureType as maxUL-TimingDiff; else if the UE initiates transmission of the SCGFailureInformation message due to SRB3 IP check failure: set the failureType as srb3-IntegrityFailure; and else if the UE initiates transmission of the SCGFailureInformation message due to Reconfiguration failure of NR RRC reconfiguration message: set the failureType as scg-reconfigFailure.

[0123] In accordance with an exemplary embodiment, the UE may set the contents of the MeasResultSCG-Failure as follows: - set the measResultServFreqList to include for each SCG cell that is configured by the SN to be measured, if any, within measResultServingCell the quantities of the concerned SCell, if available, according to specific performance requirements; - set the measResultServFreqList to include the SS / PBCH block frequency location for each SCG cell that is configured by the SN to be measured, if any, within measResultServingCell, if SS / PBCH block measurements are available to be included. - set the measResultServFreqList to include the SS / PBCH block frequency location for each SCG cell that is configured by the SN to be measured, if any, within measResultServingCell, if SS / PBCH block measurements are available to be included. - for each SCG serving frequency included in measResultServFreqList, include within measResultBestNeighCell the physCellId and the quantities of the best non-serving cell, based on reference signal receiving power (RSRP), on the concerned serving frequency; - set the measResultNeighCells to include the best measured cells on non-serving NR frequencies, ordered such that the best cell is listed first, and based on measurements collected up to the moment the UE detected the failure, and set its fields as follows: (a) if the UE was configured to perform measurements by the SN for one or more non-serving NR frequencies and measurement results are available, include the measResultListNR; and (b) for each neighbour cell included, include the optional fields that are available.

[0124] The measured quantities may be filtered by the L3 filter as configured in the mobility measurement configuration. The measurements are based on the time domain measurement resource restriction, if configured. Blacklisted cells are not required to be reported.

[0125] In accordance with the claimed invention, an ARFCN-ValueNR information element (IE) is used to indicate the ARFCN applicable for a downlink, uplink or bi-directional (such as time division duplex (TDD)) NR global frequency raster, as defined in 3GPP TS 38.101. The following is an example of the ARFCN-ValueNR IE.

[0126] In accordance with an exemplary embodiment not encompassed by the wording of the claims, a GSCN-ValueNR IE may be used to indicate the frequency positions of the SS / PBCH blocks, as defined in 3GPP TS 38.101. An example of the GSCN-ValueNR IE is provided as below, where a field of FrequencyOffsetSSB may be optional.

[0127] In accordance with an exemplary embodiment, a MeasResultSCG-Failure IE may be used to provide information regarding failures detected by the UE in case of EN-DC. The following is an example of the MeasResultSCG-Failure IE, where some field such as refFreqCSI-RS, measResultBestNeighCell, and MeasResultNR may be optional, but ARFCN-ValueNR is required by the claimed invention.

[0128] The third proposed solution according to some exemplary embodiments enables a network node to identify that SS / PBCH block measurements are associated with a particular frequency location, and CSI-RS measurements are associated with a particular frequency location, instead of having the generic carrier information. In accordance with an exemplary embodiment, the network node may comprise network entity supporting LTE, NR, 5G or other proper radio technologies, such as a eNB or a gNB.

[0129] Fig.7B is a flowchart illustrating a method 720 according to some embodiments of the present disclosure (the shown method does not comprise all of the features required by the claimed invention). The method 720 illustrated in Fig.7B is performed by an apparatus implemented in a network node operating as an SN. According to the exemplary method 720 illustrated in Fig.7B, the SN receives a report including measurement information for a terminal device from a network node operating as an MN, as shown in block 722. The terminal device is connected at least to the MN. The report indicates frequency information for the measurement information. As shown in block 724, the SN obtains the frequency information from the report. The frequency information comprises a frequency location of a synchronization signal and a frequency location of a reference signal.

[0130] In accordance with an exemplary embodiment, the frequency information may further comprise an offset of a synchronization signal block (SSB). The frequency location of the synchronization signal comprises a frequency location where the synchronization signal / physical broadcast channel (SS / PBCH) block is transmitted. The frequency location of the reference signal comprises a reference location from which the channel state information-reference signal (CSI-RS) frequency location can be derived.

[0131] Fig.7C is a block diagram illustrating an apparatus 730 (in the shown form not encompaased by the wording of the claims). As shown in Fig.7C, the apparatus 730 may comprise a receiving unit 731 and an obtaining unit 732. In an exemplary embodiment, the apparatus 730 may be implemented in a network node operating as an SN. The receiving unit 731 may be operable to carry out the operation in block 722, and the obtaining unit 732 may be operable to carry out the operation in block 724. Optionally, the receiving unit 731 and / or the obtaining unit 732 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[0132] The various blocks shown in Figs.5A-5C, Figs.6A-6C and Fig.7B may be viewed as method steps, and / or as operations that result from operation of computer program code, and / or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods.

[0133] Fig.8 is a block diagram illustrating an apparatus 800 according to various embodiments (either encompassed or not encompassed by the wording of the claims). As shown in Fig.8, the apparatus 800 comprises one or more processors such as processor 801 and one or more memories such as memory 802 storing computer program codes 803. The memory 802 may be non-transitory machine / processor / computer readable storage medium. In accordance with some exemplary embodiments, the apparatus 800 may be implemented as an integrated circuit chip or module that can be plugged or installed into a network node or a terminal device.

[0134] In some implementations, the one or more memories 802 and the computer program codes 803 may be configured to, with the one or more processors 801, cause the apparatus 800 at least to perform any operation of the method as described in connection with any of Figs.5A-5C. In other implementations, the one or more memories 802 and the computer program codes 803 may be configured to, with the one or more processors 801, cause the apparatus 800 at least to perform any operation of the method as described in connection with any of Figs.6A-6C. In further implementations, the one or more memories 802 and the computer program codes 803 may be configured to, with the one or more processors 801, cause the apparatus 800 at least to perform any operation of the method as described in connection with Fig.7B. In accordance with some exemplary embodiments, the one or more memories 802 and the computer program codes 803 may be configured to, with the one or more processors 801, cause the apparatus 800 at least to perform any operation of any method according to the fourth proposed solution.

[0135] In accordance with some exemplary embodiments of the fourth proposed solution, there is provided a method implemented at a terminal device (not all of the features required by the claimed invention are mentioned in the following). The method comprises obtaining measurement information based at least in part on configurations of a MN and a SN. The terminal device is connected to the MN and the SN. The method further comprises transmitting a report including the measurement information that comprises frequency information to the MN, in response to a failure related to the SN.

[0136] In accordance with some exemplary embodiments of the fourth proposed solution, there is provided a method implemented at a network node (not all of the features required by the claimed invention are mentioned in the following). The method comprises receiving a report including measurement information that comprises frequency information from a terminal device which is connected at least to the network node, in response to a failure related to another network node. The network node is configured to operate as a MN for the terminal device, and the another network node is configured to operate as a SN for the terminal device. The measurement information is based at least in part on configurations of the MN and the SN. The method further comprises interpreting the measurement information. Optionally, the method may further comprise determining another SN for the terminal device, based at least in part on the measurement information, and transmitting at least part of the measurement information to the another SN.

[0137] In accordance with some exemplary embodiments of the fourth proposed solution, there is provided a method implemented at a network node (not all of the features required by the claimed invention are mentioned in the following). The method comprises receiving a report including measurement information that comprises frequency information for a terminal device from another network node which is connected to the terminal device. The network node is configured to operate as a SN for the terminal device, and the another network node is configured to operate as a MN for the terminal device. The measurement information is based at least in part on configurations of the MN and another SN for the terminal device. The method further comprises interpreting the measurement information.

[0138] The frequency information comprises information about at least one of a frequency location of a synchronization signal and a frequency location of a reference signal.

[0139] The frequency location of the synchronization signal comprises a frequency location where a synchronization signal block is transmitted.

[0140] In accordance with some exemplary embodiments, the frequency information may further comprise an offset of the synchronization signal block.

[0141] The information about the frequency location of the reference signal comprises a reference location from which a channel state information-reference signal (CSI-RS) frequency location is derivable.

[0142] According to the claimed invention, the frequency information may comprise at least one absolute radio frequency channel number.

[0143] In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0144] As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

[0145] It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM), etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

Claims

1. A method (510) implemented at a terminal device connected to a master network node and a secondary network node, wherein both the master network node and the secondary network node configure the terminal device to obtain respective measurement results, comprising: obtaining (512) measurement information based at least in part on the configurations of the master network node and the secondary network node; and transmitting (514) a report including the measurement information that comprises frequency information to the master network node, in response to a failure related to the secondary network node, wherein the frequency information comprises information about a frequency location of a synchronization signal and a frequency location of a reference signal, wherein the report indicates an association between a serving frequency configured by the secondary network node and a measurement result associated with the serving frequency, and wherein the frequency location of the synchronization signal comprises at least one new radio, NR, absolute radio frequency channel number, ARFCN, ARFCN-ValueNR and the frequency location of the reference signal comprises at least one NR ARFCN-ValueNR.

2. The method according to claim 1, wherein the frequency location of the synchronization signal comprises a frequency location where a synchronization signal block is transmitted, and, optionally, wherein the frequency information further comprises an offset of the synchronization signal block.

3. The method according to claim 1 or 2, wherein the information about the frequency location of the reference signal comprises a reference location from which a channel state information-reference signal, CSI-RS, frequency location is derivable.

4. A terminal device connected to a master network node and a secondary network node, the terminal device comprising an apparatus (800), comprising: one or more processors (801); and one or more memories (802) comprising computer program codes (803), the one or more memories (802) and the computer program codes (803) configured to, with the one or more processors (801), cause the apparatus (800) at least to perform the method according to any one of claims 1 to 3.

5. A method (520) implemented at a network node configured to operate as a master network node for a terminal device, comprising: receiving (522) a report including measurement information that comprises frequency information from the terminal device which is connected at least to the network node, in response to a failure related to another network node configured to operate as a secondary network node for the terminal device, wherein both the master network node and the secondary network node configure the terminal device to obtain respective measurement results, and wherein the measurement information is based at least in part on the configurations of the master network node and the secondary network node; and interpreting (524) the measurement information, wherein the frequency information comprises information about a frequency location of a synchronization signal and a frequency location of a reference signal, wherein the report indicates an association between a serving frequency configured by the secondary network node and a measurement result associated with the serving frequency, and wherein the frequency location of the synchronization signal comprises at least one new radio, NR, absolute radio frequency channel number, ARFCN, ARFCN-ValueNR and the frequency location of the reference signal comprises at least one NR ARFCN-ValueNR.

6. The method according to claim 5, wherein the frequency location of the synchronization signal comprises a frequency location where a synchronization signal block is transmitted, and, optionally, wherein the frequency information further comprises an offset of the synchronization signal block.

7. The method according to claim 5 or 6, wherein the information about the frequency location of the reference signal comprises a reference location from which a channel state information-reference signal frequency location is derivable.

8. The method according to any of claims 5 to7, the method further comprising: determining another secondary network node for the terminal device, based at least in part on the measurement information, and transmitting at least part of the measurement information to the another secondary network node.

9. A network node configured to operate as a master network node for a terminal device, the network node comprising an apparatus (800), comprising: one or more processors (801); and one or more memories (802) comprising computer program codes (803), the one or more memories (802) and the computer program codes (803) configured to, with the one or more processors (801), cause the apparatus (800) at least to perform the method according to any one of claims 5 to 8.

10. A method (620) implemented at a network node configured to operate as a secondary network node for a terminal device, comprising: receiving (622) a report including measurement information that comprises frequency information for the terminal device from another network node which is connected to the terminal device, wherein the another network node is configured to operate as a master network node for the terminal device, wherein both the master network node and another secondary network node configure the terminal device to obtain respective measurement results, and wherein the measurement information is based at least in part on the configurations of the master network node and the another secondary network node for the terminal device; and interpreting (624) the measurement information, wherein the frequency information comprises information about a frequency location of a synchronization signal and a frequency location of a reference signal, wherein the report indicates an association between a serving frequency configured by the secondary network node and a measurement result associated with the serving frequency, and wherein the frequency location of the synchronization signal comprises at least one new radio, NR, absolute radio frequency channel number, ARFCN, ARFCN-ValueNR and the frequency location of the reference signal comprises at least one NR ARFCN-ValueNR.

11. The method according to claim 10, wherein the frequency location of the synchronization signal comprises a frequency location where a synchronization signal block is transmitted, and, optionally, wherein the frequency information further comprises an offset of the synchronization signal block.

12. The method according to claim 10 or 11, wherein the information about the frequency location of the reference signal comprises a reference location from which a channel state information-reference signal frequency location is derivable.

13. A network node configured to operate as a secondary network node for a terminal device, the network node comprising an apparatus (800), comprising: one or more processors (801); and one or more memories (802) comprising computer program codes (803), the one or more memories (802) and the computer program codes (803) configured to, with the one or more processors (801), cause the apparatus (800) at least to perform the method according to any one of claims 10 to 12.

14. A computer-readable medium having computer program codes (803) embodied thereon for use with a computer, wherein the computer program codes (803) comprise codes for performing the method according to any of claims 1 to 3, 5 to 8 and 10 to 12.