CLI-AWARE CELL CONNECTIVITY MANAGEMENT

Technical Field

Various example embodiments relate to computer networking, and more particularly to an apparatus for a CLI-aware cell connectivity management.

Background

The 5 ^th generation wireless networks (5G) refer to a new generation of radio systems and network architecture. 5G is expected to provide higher bitrates and coverage than the current long term evolution (LTE) systems. 5G is also expected to increase network expandability up to hundreds of thousands of connections. However, there is a need to improve the multi cell measurements in such systems.

Summary

Example embodiments provide an apparatus for a communication system. The communication system supports carrier aggregation. The communication system comprises a plurality of cells including a primary cell and at least one secondary cell. The primary cell serves a user equipment. The apparatus comprises means being configured for: connecting the secondary cell to the user equipment or disconnecting the user equipment from the secondary cell, if the user equipment is already connected to the secondary cell, the means being configured to perform the connecting or the disconnecting based on an inter-frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of the secondary cell.

According to further example embodiments, a user equipment is provided. The user equipment is served by a primary cell. The user equipment comprises means configured for performing an inter frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of a secondary cell and reporting the performed measurements to the primary cell.

According to further example embodiments, a system is provided. The system comprises the apparatus and the user equipment of the previous example embodiments.

According to further example embodiments, a method used in a network node serving a primary cell of a communication system is provided. The communication system supports carrier aggregation. The communication system comprises a plurality of cells including a primary cell and at least one secondary cell. The primary cell serves a user equipment. The method comprises: connecting the secondary cell to the user equipment or disconnecting the user equipment from the secondary cell, if the user equipment is already connected to the secondary cell, wherein the connecting or the disconnecting is performed based on an inter-frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of the secondary cell.

According to further example embodiments, a method used in a user equipment is provided. The user equipment is served by a primary cell. The method comprises performing an inter-frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of a secondary cell and reporting the performed measurements to the primary cell.

According to further example embodiments, a computer program product comprises instructions stored thereon for causing an apparatus for performing at least the following: performing an inter-frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of a secondary cell and reporting the performed measurements to a primary cell.

According to further example embodiments, a computer program product comprises instructions stored thereon for causing an apparatus for performing at least the following: connecting a secondary cell to a user equipment or disconnecting the user equipment from the secondary cell, if the user equipment is already connected to the secondary cell, wherein the connecting or the disconnecting is performed based on an inter-frequency cross-link interference, CLI, measurement and a radio resource management, RRM, inter-frequency measurement on a carrier of the secondary cell.

Brief Description of the Drawings

The accompanying figures are included to provide a further understanding of examples, and are incorporated in and constitute part of this specification. In the figures:

FIG.1 illustrates a part of an exemplifying radio access network;

FIG. 2 is a schematic illustration of a wireless communication system and of one CLI scenario;

FIG. 3 shows a radio resource management (RRM) measurement configuration and report signaling process according to the present subject matter;

FIG. 4 is a flowchart of a method of a measurement configuration method used in an gNB according to an example of the present subject matter;

FIG. 5 is a flowchart of a measurement report method used in a UE according to an example of the present subject matter;

FIG. 6 is a block diagram illustrating an RRM procedure for cell management in a primary cell and secondary cells of a FletNet scenario with dual connectivity;

FIG. 7 is a flow diagram for an implementation of the procedure of FIG. 6 using one measurement object in accordance with an example of the present subject matter; FIG. 8 is a flow diagram for an implementation of the procedure of FIG. 6 using two measurement objects in accordance with an example of the present subject matter;

FIG. 9A shows an example content of a CLI information element in accordance with an example of the present subject matter;

FIG. 9B shows an example content of a CLI information element in accordance with an example of the present subject matter;

FIG. 10 shows an example content of a measurement object information element in accordance with an example of the present subject matter;

FIG. 11 is a block diagram showing an example of an apparatus according to an example of the present subject matter.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc., in order to provide a thorough understanding of the examples. However, it will be apparent to those skilled in the art that the disclosed subject matter may be practiced in other illustrative examples that depart from these specific details. In some instances, detailed descriptions of well-known devices and/or methods are omitted so as not to obscure the description with unnecessary detail.

The apparatus may be a base station apparatus such as a nodeB (gNB). The communication system may include the apparatus and the user equipment. The apparatus is configured to perform communications with the UE by carrier aggregation using a plurality of different frequency bands configured by the apparatus. The UE may be a carrier aggregation capable UE. The primary cell (PCell) may be a cell operating on a primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure, or may be the cell indicated as the primary cell in a handover procedure. The primary cell may, for example, be the cell hosting an RRC entity. The secondary cell (SCell) may be a cell operating on a secondary frequency, which may be used to provide additional radio resources to the same UE being served by the primary cell. The carrier aggregation enables one or more secondary cells to be aggregated with the primary cell for increased bandwidth. The carrier aggregation may be a technique to increase the data rate per user equipment, whereby multiple frequency blocks (called component carriers) may be assigned to the same user equipment. For example, the carrier aggregation (CA) may enable communication by simultaneously using a plurality of carriers. The carrier aggregation in accordance with the present subject matter may further comprise an inter-site carrier aggregation enabling the so-called dual connectivity (DC). For example, the inter-site carrier aggregation may be a carrier aggregation of cells hosted by different gNBs.

Connecting the UE to the secondary cell or connecting the secondary cell to the UE means that the secondary cell is configured or added for the UE. The configured secondary cell may be activated before active data communication takes place with the UE on the secondary cell. Disconnecting the UE from the secondary cell means that the secondary cell is removed or released from the primary cell.

The communication system may, for example, use a dynamic time division duplexing (TDD) technique. Flowever, in a dynamic time division duplexing (TDD) system, the TDD configuration may be changed depending on traffic demands on a cell-by-cell basis. In addition, different transmission directions may exist among neighboring cells at a given time. This may result in a cross-link interference such as a UE-to-UE interference. The inter-frequency CLI may occur when one UE (aka the aggressor) is transmitting uplink (UL) data, while another UE (aka the victim) is trying to receive downlink (DL) data from its serving cell.

If not properly managed, the inter-frequency CLI can be a serious problem for new radio (NR) TDD deployment where different radio frame configurations are applied. In particular, the inter-frequency CLI conditions that a UE will experience depend on multiple factors. Those include, the TDD radio frame configurations at cells, the location and propagation conditions for the UE, carrier frequency, etc. In order to solve this problem, the present subject matter introduces CLI-awareness enhancements for cell management decisions, such that PCell handovers are conducted with tolerable inter-frequency CLI only, and SCells are configured and activated only for cells where inter-frequency CLI is at an acceptable level. The present subject matter provides enhancements for UE RRM measurement configurations and reporting criteria that may help improve the overall system performance for NR TDD deployments where the TDD radio frame configuration is not always fully aligned and identical for all cells. In particular, two measurements are used for cell management decisions. The two measurements comprise the inter-frequency CLI measurement and the RRM inter frequency measurement. The RRM inter-frequency measurement is different from the inter-frequency CLI measurement.

The RRM inter-frequency measurement may, for example, be a measurement of a communication or signal quality of a cell at a predetermined carrier such as reference signal received power (RSRP) and Reference signal received quality (RSRQ) measurements. According to an example, the inter-frequency CLI measurement is a received signal strength indicator RSSI-CLI measurement or sounding reference signals, SRS-CLI measurement. The inter-frequency CLI measurement may, for example, be an SRS-RSRP measurement. The SRS-RSRP measurement may be a linear average of the power contributions of the SRS to be measured over the configured resource elements within the considered measurement frequency bandwidth in the time resources in the configured measurement occasions. The UE may be configured with the SRS configuration(s) that it shall use when performing such SRS-RSRP measurements. The RSSI-CLI measurement may be the linear average of the total received power observed only in certain OFDM symbols of measurement time resource(s), in the measurement bandwidth, over the configured resource elements for measurements by the UE.

In a first inter-frequency measurement example, the two measurements may be performed using a method in which the apparatus configures a measurement gap during which transmission and reception is not performed at the UE. In a second inter frequency measurement example, the UE may be configured to perform the two measurements without the need of a measurement gap. For example, the UE may measure communication quality of a predetermined carrier using an unused receiver of the UE. Therefore, the UE does not need to generate a measurement gap for performing the inter-frequency CLI and RRM inter-frequency measurements.

During the measurements performed in accordance with the first inter-frequency example, the UE may acquire the timing (and base characteristics) of the carrier, where it shall perform such measurements, from synchronization signal block (SSB) transmissions. When the UE performs the inter-frequency CLI measurement on an inter-frequency carrier A, it shall measure the inter-frequency CLI that it would receive if being connected to carrier A, i.e. the inter-frequency CLI coming from UEs operating in the same frequency range as carrier A, while the cell on carrier A is operating in downlink transmission mode.

The present subject matter may enable an efficient cell connectivity management, e.g. for 5G NR systems, with inbuild CLI awareness in cell management decisions. CLI- aware cell management decisions may be enabled for RRC connected mode NR UEs, including cases with single cell connectivity (i.e. UE only having a PCell), cases with intra-site CA where UEs have one PCell and up to multiple SCells, as well as DC cases where the UE is having at least one configured PCell on a master gNB (MgNB) and also cells on a secondary gNB (SgNB). Thus, the cell connectivity management may cover both RRC connected mobility management of a PCell, as well as SCell management for cases with CA and/or DC cases. The cell management decisions may comprise SCell addition, release, and change decisions, and PCell changes. The present subject matter may also offer advantages for UEs that only have a single-cell connectivity by adding increased robustness to PCell mobility decisions.

According to an example, the means is configured for generating a measurement control message for the user equipment. The measurement control message comprises measurement object information indicating the secondary cell to be measured by the user equipment. The measurement control message further comprises report configuration information defining an event-based report criterion on inter-frequency CLI and RRM inter-frequency measurements for triggering a measurement report of the secondary cell by the user equipment. The generated measurement control message may be transmitted to the user equipment. The inter frequency CLI measurement and RRM inter-frequency measurement, used by the apparatus to perform the connecting or the disconnecting, are received from the user equipment in response to sending the measurement control message.

This may enable cell management decisions that is network controlled and UE assisted. That is, UEs provide measurements to the network, and the network subsequently takes actions such as performing handovers, adding, changing or releasing secondary cells, etc. The measurements from the UE offering such assistance may be RRM measurements that typically include RSRP and RSRQ device measurements in addition to inter-frequency CLI measurements.

The communication between the UE and the apparatus, in this example, may preferably be performed in a Radio Resource Control (RRC) connection reconfiguration process. The apparatus may configure the UE to perform measurements and report them in accordance with a measurement configuration indicated by the measurement control message. The measurement configuration may be provided by means of dedicated signaling e.g. using the RRCReconfiguration. For example, the measurement control message may be the RRCConnectionReconfiguration message. For that, the UE may be in an RRC connected mode (RRC_CONNECTED) having the primary cell as the serving cell. The UE may, for example, reestablish the RRC connection in order to be in the RRC connected mode. Since the UE is in RRC connected mode and configured with carrier aggregation, the cells serving the UE may comprise in addition to the primary cell one or more secondary cells.

The measurement object information may for example comprise a list of objects on which the UE shall perform the two measurements, namely the inter-frequency CLI and RRM inter-frequency measurements. The report configuration information may comprise a list of reporting configurations, wherein one or multiple reporting configurations may be associated with a measurement object of the list of measurement objects. Each reporting configuration may for example indicate the criterion that triggers the UE to send a measurement report. The measurement control message may further include a list of measurement identities, wherein each measurement identity links one measurement object with one or more associated reporting configurations. Using multiple measurement identities may enable to link more than one measurement object to the same reporting configuration, and to link more than one reporting configuration to the same measurement object. The measurement identity may be included in the measurement report of the UE, serving as a reference to the apparatus.

The report configuration information may further comprise measurement gaps which are periods that the UE may use to perform the two measurements. This may particularly be advantageous in case the UE is configured to perform the first inter frequency measurement example.

According to an example, the inter-frequency CLI measurement and the RRM inter frequency measurement fulfil the event-based report criterion. The event-based report criterion comprises conditions of a radio resource management (RRM) event and/or a CLI condition on the inter-frequency CLI measurement. For example, a CLI condition may require that the measured inter-frequency CLI is smaller than a predefined threshold. The RRM event may be one of: event A2, event A4 and event A6 as defined in 3GPP technical specification #: 38.331. This may enable to configure the UE with new combined events. The new combined event may be defined by a combination of an RRM condition of an RRM event and a CLI condition. The combination may for example be obtained by a logical operator such as OR or AND operator.

For example, a combined event A4 may be an AND combination of an RRM condition of RRM event A4 and a CLI condition requiring an inter-frequency CLI below the threshold. That is, the combined event A4 may be used for configuration of the secondary cell if both RRM event A4 and low CLI conditions are fulfilled.

A combined event A2 may be an OR combination of an RRM condition of RRM event A2 and a CLI condition requiring the inter-frequency CLI above the threshold. That is, the combined event A2 may be used to release or disconnect the secondary cell from the UE if RRM event A2 or high CLI conditions are fulfilled. A combined event A6 may be an AND combination of an RRM condition of RRM event A6 and a CLI condition requiring the inter-frequency CLI below the threshold on a new candidate secondary cell. That is, the combined event A6 may be used for changing the secondary cell (SCell change) if both RRM event A6 and low CLI conditions are fulfilled.

According to an example, the means is configured to, after disconnecting the user equipment from the secondary cell, connecting the user equipment to another secondary cell using said RRM inter-frequency measurement on a carrier of the secondary cell and using an inter-frequency CLI measurement and a RRM inter frequency measurement on a carrier of the other secondary cell, thereby changing the user equipment from the secondary cell to the other secondary cell. The inter frequency CLI and RRM inter-frequency measurements may be received from the UE in accordance with the combined event A6. That is, the inter-frequency CLI and RRM inter-frequency measurements fulfill the condition of the combined event A6.

According to an example, the means is configured to receive from the user equipment a single message report comprising the inter-frequency CLI measurement and the RRM inter-frequency measurement. Using a single message report may save processing resources that would otherwise be required using multiple ones. The processing resources may, for example, comprise uplink transmission resources because a single message report may correspond to a more compact UL transmission format from the UE to its primary cell. For example, a new measurement object (RRM_CLI_MeasObj) may be defined. The new measurement object may combine the RRM event measurements and the inter-frequency CLI measurement. For example, the CLI-RSSI resource timing with reference to SSB or CSI-RS location may be given on the new measurement object. In this case, the CLI-RSSI measurement may be done in every radio frame along with SSB measurements itself. This may make the decision on event-based reporting based on combined event faster than compared to defining separate measurement object for CLI-RSSI with longer periodicity. According to an example, the means is configured to receive from the user equipment two message reports comprising the inter-frequency CLI measurement and RRM inter frequency measurement respectively. This may enable to maintain existing measurement report unchanged while still enabling additional measurement reports of inter-frequency CLI measurements. The transmission of the two report messages is triggered by the fulfillment of the event-based report criterion.

According to an example, the plurality of cells comprises another primary cell. The UE may be served by a single primary cell at a time. The means is configured to receive from the other primary cell a message indicating inter-frequency CLI measurements resources at the other primary cell, receive RRM inter-frequency measurement and inter-frequency CLI measurement performed on a carrier of the other primary cell, wherein the inter-frequency CLI measurement on the carrier of the other primary cell is performed in accordance with the received inter-frequency CLI measurements resources. The means is further configured to hand over the user equipment to the other primary cell based on the received inter-frequency CLI measurement and RRM inter-frequency measurement on the carrier of the other primary cell.

The inter-frequency CLI measurement resources may for example indicate an SRS configuration where CLI-SRS measurements are used.

For example, in case of a measurement of inter-frequency cells, each serving node (of a PCell) informs other nodes, e.g. via a Xn interface, about its configured inter frequency CLI measurement resources. The CLI resources may be provided in an inter node message which provides SSTD (SSB timing related information) to the other nodes. When a source node configures RRM inter-frequency measurements for a cell, it includes the CLI-resource information received from the node. For example, a node gNB1 knows the SSB information of serving cells of a node gNB2 via an Xn Interface message. This information is used to configure the contents of a measurement object NR for inter-frequency measurement. gNB2 also provides its CLI-RSSI resource information which is configured for its own inter-frequency CLI measurement or selected resources within these measurement resources which is having most interfering resources. According to an example, the received inter-frequency CLI measurement and RRM inter-frequency measurement fulfill a predefined handover criterion. The handover criterion comprises conditions of an RRM event A3 and a condition on the CLI measurement. This example may enable to include UE CLI awareness with the A3 RRM events for a PCell change (i.e. traditional mobility events). For example, a combined event A3 may be defined. The combined event A3 may be an AND combination of an RRM condition of RRM event A3 as defined in 3GPP technical specification #: 38.331 and a CLI condition requiring the inter-frequency CLI below the threshold. Hence, this also corresponds to introducing new measurement triggering criteria.

According to an example, the means is configured to report inter-frequency CLI measurement resources at the primary cell to other primary cells of the communication system.

According to an example, the means is configured for reporting a handover message to the UE indicating to the UE to continue CLI measurements after the handover. For example, a handover command or SCell-Addition RRC message to the UE can include an indication to continue with inter-frequency CLI measurements after successful handover completion. This may enable to continue the inter-frequency CLI measurements after successful handover without a need to reconfigure inter-frequency CLI measurements on these resources. This follow-on inter-frequency CLI measurements may be beneficial to avoid another RRC signaling to configure these measurements again. For example, the CLI-RSSI measurements configured along with RRM inter-frequency measurements can be continued after successful handover.

According to an example, the generated measurement control message comprises an information element, named MeasObjectNR, wherein the information element comprises a reference to an information element indicative of inter-frequency CLI measurement resources. This may enable a seamless integration of the present subject matter with existing NR infrastructures. FIG.1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in FIG.1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in FIG.1 .

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

The example of FIG.1 shows a part of an exemplifying radio access network.

FIG.1 shows devices 10 and 12. The devices 10 and 12 may, for example, be user devices. The devices 10 and 12 are configured to be in a wireless connection on one or more communication channels with a node 14. The node 14 is further connected to a core network 20. In one example, the node 14 may be an access node (such as (e/g)NodeB) 14 providing or serving devices in a cell. In one example, the node 14 may be a non-3GPP access node. The physical link from a device to a (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the device is called downlink or forward link. It should be appreciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to the core network 20 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of devices (UEs) to external packet data networks, or mobile management entity (MME), etc.

The device (also called user device, UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station.

The device typically refers to a device (e.g. a portable or non-portable computing device) that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to- human or human-to-computer interaction, e.g. to be used in smart power grids and connected vehicles. The device may also utilize cloud. In some applications, a device may comprise a user portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation is carried out in the cloud. The device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses. Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in FIG. 1 ) may be implemented. 5G enables using multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, cm Wave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter- Rl operability (inter-radio interface operability, such as below 6GHz - cm Wave, below 6GHz - cmWave - mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility. The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 22, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in FIG.1 by “cloud” 24). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

The technology of Edge cloud may be brought into a radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using the technology of edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 14) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 18).

It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well.

5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). Each satellite 16 in the mega constellation may cover several satellite-enabled network entities that create on ground cells. The on-ground cells may be created via an on-ground relay node 14 or by a gNB located on-ground or in a satellite.

It is understandable for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. One of the (e/g)NodeBs or may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of FIG.1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e/g)NodeBs are required to provide such a network structure.

For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e/g)NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in FIG.1 ). A HNB Gateway (HNB-GW), which is typically installed within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

FIG. 2 is a schematic illustration of a wireless communication system 200 and of one CLI scenario. The communication system 200 may be configured to use the TDD technique for data transmission. The communication system 200 comprises a base station or gNB 210a that serves a UE 250a located within the gNB's geographical area of service or the cell 200a. The gNB 210a may also be connected via an Xn interface to a neighboring gNB 210b serving another UE 250b in cell 200b. The base station 210a transmits a signal 222 in DL to the UE 250a in cell 200a. The other UE 250b in the neighboring cell 200b served by the base station 210b transmits a signal 233 in the UL to the base station 210b.

The UE 250a will, when it receives the signal 222 from the base station 210a, also receive the CLI interfering signal 233 from the UE 250b. This may be referred to as UL-to-DL interference which is expected to impact the victim UE. This may affect the DL transmissions in the victim cell (200a).

The inter-frequency CLI in accordance with the present subject matter may comprise the UL-to-DL interference or UE to UE interference.

FIG. 3 shows an RRM measurement configuration and report signaling process according to the present subject matter. A node gNB provides a measurement configuration applicable for a UE in RRC_CONNECTED mode by means of dedicated signaling using, for example, the RRCConnectionReconfiguration message. The UE is in RRC connected mode with a primary cell of the node gNB.

The measurement configuration may include one or more measurement objects. The measurement objects may, for example, be defined in information elements such as MeasObjectNR. The measurement configuration may further include reporting configurations defined in information elements such as reportConfigNR. The measurement configuration may further include measurement identities defined in information elements such as measldToAddModList.

The information regarding the measurement objects defines on what the UE should perform the measurements — such as a carrier frequency of a secondary cell. The information regarding reporting configurations may comprise periodic or event- triggered criteria which cause the UE to send a measurement report, as well as the details of what information the UE is expected to report. The details may include the inter-frequency CLI and RRM inter-frequency measurements performed at the carrier frequency. The information regarding measurement identities defines a measurement and its applicable measurement object and reporting configuration.

The UE confirms the receipt of the RRCConnectionReconfiguration message by returning an RRM reconfiguration complete message to the gNB. The UE then performs inter-frequency CLI and RRM inter-frequency measurements according to the measurement objects indicated in the RRCConnectionReconfiguration message, particularly in the information regarding measurement objects, and reports its measurements to the gNB at appropriate time defined by the reporting configurations indicated in the RRCConnectionReconfiguration message, particularly in the information regarding reporting configurations. For example, the UE may perform the reporting in response to determining that reported measurements, the inter-frequency CLI and RRM inter-frequency measurements fulfil the event-triggered criteria.

FIG. 4 is a flowchart of a method of a measurement configuration method used in an gNB according to an example of the present subject matter. The method starts at step 401 , where a measurement control message is generated at the gNB. The measurement control message may comprise measurement object information indicating the secondary cell to be measured by the user equipment, and report configuration information defining an event-based report criterion on inter frequency CLI and RRM inter-frequency measurements. The event-based report criterion may be a criterion for triggering a measurement report of the secondary cell by the user equipment. The event-based report criterion may comprise one or more combined events: combined event A2, combined event A3, combined event A4 and combined event A6 as defined herein. The method then proceeds to step 403, where the gNB transmits the generated measurement control message to the UE. The UE may thus be configured in accordance with the measurement control message and the gNB may receive in step 405 from the UE, inter-frequency CLI and RRM inter frequency measurements performed by the UE in accordance with the configuration information indicated in the measurement control message. In particular, the inter frequency CLI and RRM inter-frequency measurements received at the gNB may fulfill one of the combined events defined in accordance with the present subject matter. The method then proceeds to step 407, where the gNB either connect or disconnect the UE from the secondary cell. That is, if the secondary cell indicated in the configuration information is also serving the UE, the gNB may disconnect the UE from the secondary cell if the received inter-frequency CLI and RRM inter-frequency measurements fulfill the combined event A2. However, if the UE is only served by the primary cell at the time of sending the measurement control message, the gNB may connect the UE to the secondary cell if the received inter-frequency CLI and RRM inter frequency measurements fulfill the combined event A4.

Connecting the UE to the secondary cell is referred to as a SCell addition and disconnecting the UE from the secondary cell is referred to as a SCell release.

In one example a method may comprise steps 405 to 407, wherein the two measurements may be received from the UE in response to submitting by the apparatus a measurement control message or may be received on a periodic basis from the UE. FIG. 5 is a flowchart of a measurement report method used in a UE according to an example of the present subject matter. The method starts at step 501 , where the UE receives a measurement control message from an gNB. The measurement control message may comprise measurement object information indicating the secondary cell to be measured by the user equipment, and report configuration information defining an event-based report criterion on inter-frequency CLI and RRM inter-frequency measurements. The event-based report criterion may be a criterion for triggering a measurement report of the secondary cell by the user equipment. The event-based report criterion may comprise one or more combined events defined herein.

The UE then performs both inter-frequency CLI and RRM inter-frequency measurements on the cell indicated by the measurement object information at step 503. The method proceeds to step 505, where the UE determines whether the event- based report criterion is fulfilled by the two measurements e.g. the UE may determine if any one of the combined events indicated in the report configuration information is fulfilled by the two measurements. If it is determined that the two measurements fulfill the event-based report criterion, the method proceeds to step 507, where the UE reports the two measurements to the gNB. The method then turns to step 503, where the UE continuously performs the measurements. If it is determined that the two measurements do not fulfill the event-based report criterion, the method then turns to step 503, where the UE continuously performs measurement.

FIG. 6 is a block diagram illustrating an RRM procedure for cell management in a primary cell (also referred to as a macro (M) cell) M1 and secondary cells (SC1 and SC2) of a HetNet scenario with dual connectivity. In this example, the primary cell M1 may comprise the master node for the UE, and secondary cells SC1 and SC2 are acting as secondary nodes. In this particular example, the UE is moving from the left to the right. Initially, it is only connected to the primary cell M1. As the UE reaches reference point A, the new combined event A4 defined by the traditional RRM event A4 for SC1 and the inter-frequency CLI for SC1 , is fulfilled, and hence the secondary cell SC1 is configured for the UE. As the UE reaches reference point B, the combined event A2 for SC1 release is triggered as the inter-frequency CLI is measured to be above the threshold. The secondary cell SC1 is thereby released. Only when the UE comes to reference point C, the secondary cell SC2 is configured for the UE, as this is the point where both A4 AND the inter-frequency CLI is below a threshold, is fulfilled. Thereby, the enhanced cell management scheme in accordance with the present subject matter incorporates CLI-awareness, avoiding configuration (and activation) of cells for a UE that are suffering from severe inter-frequency CLI. The performance may therefore be improved for UEs in the CLI deadzone shown in FIG. 6, and thus having the UE configured to the secondary cell layer further improves the communication bandwidth compared to case where inter-frequency CLI is present. The procedure of FIG. 6 introduces mechanisms to avoid having a UE configured to a cell where inter frequency CLI is at a level where it results in poor performance.

FIG. 7 is a flow diagram of a signaling method using the DC example depicted in FIG. 6 for an implementation using one new measurement object (RRM_CLI_MeasObj) combining the RRM event measurements and the inter-frequency CLI measurement.

In an initial state, a UE 702 may be in RRC connected state in a PCell having a node gNB_M1 701 which is the primary node. At step 705, gNB_M1 701 may configure the UE for A4 event (threshold, th1) and inter-frequency CLI measurements (threshold, th2). The thresholds th1 and th2 may be compared against the RRM inter-frequency measurement and the inter-frequency CLI measurement respectively. At reference point A the combined event A4 event (referred to as CA4 event) is triggered (707), because the RRM inter-frequency measurement at a carrier of the secondary cell SC1 is higher than the threshold th1 and the inter-frequency CLI measured at that carrier is smaller than the threshold th2. At step 709, the UE 702 may send a measurement report to gNB_M1 to indicate that the secondary cell SC1 is available without inter frequency CLI problems. At step 711 , gNB_M1 may request a secondary node gNB_SC1 703 of the secondary cell SC1 and the UE 702 to establish a SCell connection, thereby connecting the UE to SC1. The SCell connection may then be established (713) on gNB_SC1.

At step 715, gNB_M1 may configure the UE 702 for A2 event (threshold, th1) and inter frequency CLI measurements (threshold, th2). At reference point B the combined event A2 event (referred to as CA2 event) may be triggered (717) because the inter- frequency CLI measurement is higher than the threshold th2. At step 719, the UE 702 may send a measurement report to gNB_M1 701 to indicate that the secondary cell SC1 now has serious inter-frequency CLI problems. At step 721 , gNB_M1 701 may request gNB_SC1 703 and the UE 702 to terminate the SCell connection, thereby disconnecting the UE from SC1. The SCell connection may then be terminated.

At step 723, gNB_M1 701 may configure the UE for A4 event (threshold, th1) and CLI measurements (threshold, th2). At reference point C, the combined event A4 event may be triggered (725) because the RRM inter-frequency measurement on a carrier of the secondary cell SC2 measured is higher than the threshold th1 and the inter frequency CLI measurement on that carrier is smaller than the threshold th2. At step 727, the UE 702 may send a measurement report to gNB_M1 701 to indicate that the secondary cell SC2 is available without inter-frequency CLI problems. At step 729, gNB_M1 701 may request a secondary node gNB_SC2 704 of the secondary cell SC2 and the UE 702 to establish a SCell connection, thereby connecting the UE to SC2. The SCell connection may then be established (731) on gNB_SC1.

At step 733, gNB_M1 may configure the UE 702 for A2 event (threshold, th1) and CLI measurements (threshold, th2). At reference point D the combined event A2 event may be triggered (735) because the RRM inter-frequency measurement is smaller than the threshold th1. At step 737, the UE 702 may send a measurement report to gNB_M1 701 to indicate that the secondary cell SC2 now too low for reliable connection. At step 739, gNB_M1 701 may request gNB_SC2 704 and the UE 702 to terminate the SCell connection, thereby disconnecting the UE from SC2. The SCell connection may then be terminated.

FIG. 8 is a flow diagram for the DC example depicted in FIG. 6 for an implementation using RRM event measurement object in addition to a separate new inter-frequency CLI measurement object (lnter_CLI_MeasObj).

In an initial state, a UE 802 may be in RRC connected mode in a PCell having a node gNB_M1 801 which is the primary node. At step 805A, gNB_M1 801 may configure the UE for an RRM A4 event with a threshold thresholdl . At step 805B, gNB_M1 801 may configure the UE for inter-frequency CLI measurements with another threshold threshold2.

At reference point A an RRM A4 event may be triggered because the RRM inter frequency measurement on a carrier of the secondary cell SC1 is higher than thresholdl . At reference point A, the inter-frequency CLI measurement at that carrier is smaller than threshold2. That is, the RRM event A4 and the CLI condition are fulfilled (807).

At step 809A, the UE 802 may send an RRM measurement report to gNB_M1 801 to indicate that the secondary cell SC1 is available. At step 809B, the UE 802 may send an inter-frequency CLI measurement report to gNB_M1 801 to indicate that SC1 has no inter-frequency CLI problems.

At step 811 , gNB_M1 802 may request a secondary node gNB_SC1 803 of the secondary cell SC1 and the UE 802 to establish a SCell connection, thereby connecting the UE to SC1. The SCell connection may then be established (813) on gNB_SC1 .

At step 815A, gNB_M1 801 may configure the UE 802 for an RRM A2 event (thresholdl ). At step 815B, gNB_M1 801 may configure the UE 802 for inter-frequency CLI measurements (threshold2). At reference point B an event may be triggered (817) by inter-frequency CLI measurements being higher than threshold2.

At step 819, the UE 802 may send an inter-frequency CLI measurement report to gNB_M1 801 to indicate that the secondary cell SC1 now has serious inter-frequency CLI problems. At step 821 , gNB_M1 801 may request gNB_SC1 803 and the UE 802 to terminate the SCell connection, thereby disconnecting the UE from SC1 . The SCell connection may then be terminated.

At step 823A, gNB_M1 801 may configure the UE for an RRM A4 event with a threshold thresholdl At step 823B, gNB_M1 801 may configure the UE for inter frequency CLI measurements with another threshold threshold2. At reference point C, an RRM A4 event may be triggered because the RRM inter frequency measurement on a carrier of the secondary cell SC2 is higher than thresholdl . At reference point C, the inter-frequency CLI measurement at that carrier may be smaller than threshold2. That is, the RRM event A4 and the CLI condition are fulfilled (825).

At step 827A, the UE 802 may send an RRM measurement report to gNB_M1 801 to indicate that the secondary cell SC2 is available. At step 827B, the UE 802 may send an inter-frequency CLI measurement report to gNB_M1 801 to indicate that SC2 has no inter-frequency CLI problems.

At step 829, gNB_M1 802 may request a secondary node gNB_SC2 804 of the secondary cell SC2 and the UE 802 to establish a SCell connection, thereby connecting the UE to SC2. The SCell connection may then be established (831) on gNB_SC2.

At step 833A, gNB_M1 801 may configure the UE 802 for an RRM A2 event (thresholdl ). At step 833B, gNB_M1 801 may configure the UE 802 for inter-frequency CLI measurements (threshold2). At reference point D an event may be triggered (835) because the RRM inter-frequency measurement on SC2 is smaller than thresholdl .

At step 837A, the UE 802 may send an RRM measurement report to gNB_M1 801 to indicate that SC2 now is too low for reliable connection. At step 837B, the UE 802 may send an inter-frequency CLI measurement report to gNB_M1 801 to indicate that SC2 has no inter-frequency CLI problems.

At step 839, gNB_M1 801 may request gNB_SC2 804 and the UE 802 to terminate the SCell connection, thereby disconnecting the UE from SC2. The SCell connection may then be terminated.

For the implementation depicted in FIG. 8 the inter-frequency CLI measurement reporting may be conducted whenever an RRM measurement event is triggered. In an alternative example, the inter frequency CLI measurement reporting may only be conducted when the measured inter-frequency CLI is above threshold2.

FIGs. 9A and 9B show an example content of a CLI information element named RSSI- ResourceConfigCLI-r16. The information element comprises parameters indicative of inter-frequency CLI measurement resources. The information element 901 A of FIG. 9A has an additional parameter named NR-measu-object-ID. The information element 901 B of FIG. 9B has an additional parameter named scell-frequency. The additional parameters have values that indicate to the UE to perform the inter-frequency CLI measurement on a carrier on which the RRM inter-frequency measurement is also performed by the UE.

FIG. 10 shows an example content of a measurement object information element MeasObjectNR 1000 in accordance with an example of the present subject matter. The information element 1000 has an additional parameter named RSSI-CLI- Resource-lnfo. The value of this additional parameter refers to a CLI information element such as information element 901 A and 901 B. The additional parameter indicates to the UE to perform the measurement of both the inter-frequency CLI and RRM inter-frequency measurement.

An example method for scenarios with CA and DC may be provided as follows. An RRC connected mode UE is first having one PCell. 2. The UE is configured with RRM measurements for at least one other carrier (inter-frequency measurements) to potentially also have an SCell configured. 3. While the UE is performing inter-frequency RRM measurements, it is also configured to perform UE inter-frequency CLI measurement on the same carrier. This may correspond to introducing an inter frequency UE CLI measObj option. For that, the UE may be configured with the combined events described herein e.g. combined event A2, combined event A4 and combined event A6. Moreover, a UE CLI awareness with the A3 RRM event may be used for a PCell change (i.e. traditional mobility events). This may be done by introducing the new combined event A3, that is only triggered if A3 is fulfilled AND inter-frequency CLI on the target cell is below a certain threshold. Thus, the present subject matter may enable the following: (i) introducing new inter frequency UE CLI measurement options, (ii) providing additional information within inter-frequency measurement object on the CLI-RSSI resources within a radio frame, which is defined as a time offset from an SSB location (iii) new UE reporting events based on a combination of UE RRM and UE inter-frequency CLI measurements (iv) a method to include CLI-RSSI measurements associated with the measurement NR object whenever inter-frequency measurement is reported (v) fully time-synchronized inter-frequency RRM and inter-frequency CLI measurements for UEs that are configured with inter-frequency measurement gaps (vi) the CLI-RSSI measurements configured along with inter-frequency measurements can be continued after a successful handover.

In FIG. 11 , a block circuit diagram illustrating a configuration of an apparatus 1070 is shown, which is configured to implement at least part of the present subject matter. It is to be noted that the apparatus 1070 shown in FIG. 11 may comprise several further elements or functions besides those described herein below, which are omitted herein for the sake of simplicity as they are not essential for the understanding. Furthermore, the apparatus may be also another device having a similar function, such as a chipset, a chip, a module etc., which can also be part of an apparatus or attached as a separate element to the apparatus 1070, or the like. The apparatus 1070 may comprise a processing function or processor 1071 , such as a central processing unit (CPU) or the like, which executes instructions given by programs or the like related to a flow control mechanism. The processor 1071 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference sign 1072 denotes transceiver or input/output (I/O) units (interfaces) connected to the processor 1071. The I/O units 1072 may be used for communicating with one or more other network elements, entities, terminals or the like. The I/O units 1072 may be a combined unit comprising communication equipment towards several network elements, or may comprise a distributed structure with a plurality of different interfaces for different network elements. Reference sign 1073 denotes a memory usable, for example, for storing data and programs to be executed by the processor 1071 and/or as a working storage of the processor 1071 .

The processor 1071 is configured to execute processing related to the above described subject matter. In particular, the apparatus 1070 may be configured to perform at least part of the method as described in connection with FIGs 4, 5, 7 and 8.

The processor 1071 is configured to perform connect a secondary cell to a user equipment or disconnect the user equipment from the secondary cell, if the user equipment is already connected to the secondary cell, based on an inter-frequency cross-link interference, CLI, measurement and RRM inter-frequency measurement on a carrier of the secondary cell.

The processor 1071 is configured to perform an inter-frequency cross-link interference, CLI, measurement and RRM inter-frequency measurement on a carrier of a secondary cell and report the performed measurements to a primary cell.