Adjustment of antenna tilt based on performance data from radio access network

Abstract

Example embodiments may be related to adjustment of antenna tilt in a cellular communication network. A method may comprise: receiving, from a radio access network, performance management data comprising measurement data of a serving cell of a plurality of devices and measurement data of a particular target cell of the plurality of devices; determining a level of interference between the serving cell and the particular target cell based on the measurement data of the serving cell and the measurement data of the particular target cell; and determining to adjust an antenna tilt of the serving cell or the particular target cell, in response to determining that the level of interference meets a condition.

Description

communications. Some example embodiments relate to adjusting antenna tilt in a cellular communication network to reduce interference.BACKGROUND

[0002] Wireless communication may be implemented with a cellular radio network comprising transmission sites that offer communication services via multiple cells corresponding to certain geographical coverage areas. Because of free propagation of radio signals, coverage areas of cells may overlap and therefore signals from different transmission sites may cause interference.SUMMARY

[0003] 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.

[0004] Example embodiments of the present disclosure enable to reduce interference between cells of a cellular communication network. This benefit may be achieved by the features of the independent claims. Further example embodiments are provided in the dependent claims, the description, and the drawings.

[0005] According to a first aspect, method is disclosed. The method may comprise: receiving, from a radio access network, performance management data comprising measurement data of a serving cell of a plurality of devices and measurement data of a particular target cell of the plurality of devices; determining a level of interference between the serving cell and the particular target cell based on the measurement data of the serving cell and the measurement data of theparticular target cell; and determining to adjust an antenna tilt of the serving cell or the particular target cell, in response to determining that the level of interference meets a condition. The method may be computer-implemented.

[0006] According to an example embodiment of the first aspect, the method comprises: the performance management data is received from at least one access node of the radio access network.

[0007] According to an example embodiment of the first aspect, the measurement data of the serving cell comprises received signal strength values associated with one or more timing advance ranges or distance ranges of the serving cell, and / or the measurement data of the particular target cell comprises received signal strength values associated with one or more timing advance ranges or distance ranges of the particular target cell.

[0008] According to an example embodiment of the first aspect, the measurement data of the serving cell comprises measurement report data of signals of the serving cell measured by the plurality of devices and / or by another plurality of devices served by the particular target cell, and the measurement data of the particular target cell comprises measurement report data of signals of the particular cell measured by the plurality of devices and / or by the other plurality of devices.

[0009] According to an example embodiment of the first aspect, the method comprises: determining to adjust the antenna tilt of the serving cell or the particular target cell, further in response to determining that a number of the plurality of devices and / or a number of the other plurality of devices exceeds a first threshold.

[0010] According to an example embodiment of the first aspect, the method comprises: determining to adjust the antenna tilt of the serving cell or the particular target cell, further in response to determining that a share of samples of measurement data associated with both the serving cell and the particular target cell from a total number of samples of measurement data associated with the serving cell and any target cell of the plurality of devices exceeds a second threshold.

[0011] According to an example embodiment of the first aspect, the condition comprises a third threshold for a signal-to-interference-plus-noise ratio between the serving cell and the particular target cell, and / or the condition comprises a fourththreshold for a received signal strength of the serving cell at the particular target cell.

[0012] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the serving cell or the particular target cell, in response to determining that the signal-to-interference-plus-noise ratio is below the third threshold, or determining to uptilt the serving cell or the particular target cell, in response to determining that the signal-to-interference-plus-noise ratio exceeds the third threshold.

[0013] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the serving cell or the particular target cell, in response to determining that a received signal strength of the serving cell exceeds the fourth threshold at the particular target cell, or determining to uptilt the serving cell or the particular target cell, in response to determining that the received signal strength of the serving cell is below the fourth threshold at the particular target cell.

[0014] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is lower than a number of samples of the measurement data of the particular target cell, or determining to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target is lower than the number of samples of the measurement data of the serving cell.

[0015] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the serving cell such that a half-power distance of the serving cell is smaller than an average distance of the plurality of devices from an access node of the serving cell, or determining to downtilt the particular target cell such that a half-power distance of the particular target cell is smaller than an average distance of the other plurality of devices from an access node of the particular target cell.

[0016] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the particular target cell, in response to determining that a number of samples of the measurement data of the serving cellis lower than a number of samples of the measurement data of the particular target cell and that a half-power distance of the serving cell is below a fifth threshold, or determining to downtilt the serving cell, in response to determining that the number of samples of the measurement data of the particular target is lower than the number of samples of the measurement data of the serving cell and that a half-power distance of the particular cell is below the fifth threshold.

[0017] According to an example embodiment of the first aspect, the method comprises: determining not to downtilt the serving cell, in response to determining that a share of samples of measurement data associated with a predetermined range of timing advance values at the serving cell but not including measurement data of any target cells of the plurality of devices from a total number of samples of the measurement data associated with the range of timing advance values at the serving cell exceeds a sixth threshold; determining not to downtilt the serving cell, in response to determining that a share of capacity of the serving cell allocated to a single device or a subset of the plurality of devices exceeds a seventh threshold; and / or determining not to downtilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is higher than a number of samples of the measurement data of the particular target cell and exceeds an eighth threshold, or determining not to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell and exceeds the eighth threshold.

[0018] According to an example embodiment of the first aspect, the method comprises: determining to uptilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is higher than a number of samples of the measurement data of the particular target cell, or determining to uptilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell.

[0019] According to an example embodiment of the first aspect, the method comprises: determining to uptilt the serving cell such that a half-power distance of the serving cell is higher than an average distance of the plurality of devices froman access node of the serving cell, or determining to uptilt the particular target cell such that a half-power distance of the particular target cell is higher than an average distance of the other plurality of devices from an access node of the particular target cell.

[0020] According to an example embodiment of the first aspect, the method comprises: selecting the particular target cell such that antennas of the serving cell and the particular target cell point substantially towards each other.

[0021] According to an example embodiment of the first aspect, the method comprises: selecting the particular target cell, in response to detecting a number of device interactions between the serving cell and the particular target cell exceeding a target.

[0022] According to an example embodiment of the first aspect, the device interactions comprise handover attempts of devices between the serving cell and the particular target cell, measurement reports of the plurality of devices with respect to the particular target cell, or measurement reports of the other plurality of devices with respect to the serving cell.

[0023] According to an example embodiment of the first aspect, the method comprises: selecting a plurality of target cells comprising the particular target cell; determining an average interference level between the serving cell and the plurality of target cells; and determining to adjust the antenna tilt of the serving cell, in response to determining that the average interference level meets the condition.

[0024] According to an example embodiment of the first aspect, the average interference level between the serving cell and the plurality of target cells comprises an average signal-to-interference-plus-noise ratio between the serving cell and the plurality of target cells, and the method further comprises: determining to downtilt the serving cell, in response to determining that the average signal-to -interference- plus-noise ratio between the serving cell and the plurality of target cells is below a ninth threshold and / or that an average received signal strength of the serving cell at the plurality of target cells exceeds a tenth threshold, or determining to uptilt the serving cell, in response to determining that the average signal-to-interference-plus- noise ratio between the serving cell and the plurality of target cells exceeds the ninththreshold and / or that the average received signal strength of the serving cell at the plurality of target cells is below the tenth threshold.

[0025] According to an example embodiment of the first aspect, the method comprises: determining to downtilt the serving cell such that a half-power distance of the serving cell is smaller than a distance between an access node of the serving cell and an access node of a nearest target cell to the serving cell.

[0026] According to an example embodiment of the first aspect, the method comprises: determining to uptilt the serving cell, further in response to determining that a number of samples of measurement data indicative of a received signal strength of the serving cell at the plurality of target cells exceeding an eleventh threshold exceeds a twelfth threshold.

[0027] According to an example embodiment of the first aspect, the method comprises: determining to uptilt the serving cell such that a half-power distance of the serving cell is higher than an average distance of the plurality of devices from an access node of the serving cell.

[0028] According to an example embodiment of the first aspect, the method comprises: outputting a request to adjust the antenna tilt of the serving cell or the particular target cell, or causing adjustment of the antenna tilt of the serving cell or the particular target cell.

[0029] According to an example embodiment of the first aspect, the performance management data is received from an access node of the serving cell and / or an access node of the particular target cell.

[0030] According to a second aspect, an apparatus may comprise means for performing the method of the first aspect, or any example embodiment thereof.

[0031] According to a third aspect, computer program, a computer program product, or a (non-transitory) computer-readable medium may comprise program code configured to, when executed by a processor, cause an apparatus at least to perform the method of the first aspect, or any example embodiment thereof.

[0032] According to a fourth aspect, an apparatus may comprise at least one processor; and at least one memory including computer program code; the at least one memory and the computer code configured to, with the at least one processor,cause the apparatus at least to perform the method of the first aspect, or any example embodiment thereof.

[0033] Any example embodiment may be combined with one or more other example embodiments. Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings.DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help to understand the example embodiments. In the drawings:

[0035] FIG. 1 illustrates an example of a wireless communication network;

[0036] FIG. 2 illustrates an example of an apparatus configured to practise one or more example embodiments;

[0037] FIG. 3 illustrates an example of a flow chart for adjusting antenna tilt of a cell pair;

[0038] FIG. 4 illustrates an example of a cells of a radio access network;

[0039] FIG. 5 illustrates an example of antenna tilts of two cells before downtilting;

[0040] FIG. 6 illustrates an example of antenna tilts of two cells after downtilting;

[0041] FIG. 7 illustrates an example of antenna tilts of two cells before uptilting;

[0042] FIG. 8 illustrates an example of antenna tilts of two cells after uptilting;

[0043] FIG. 9 illustrates an example of uptilting a cell based on an average user distance of the uptilted cell;

[0044] FIG. 10 illustrates an example of a flow chart for adjusting antenna tilt of a serving cell;

[0045] FIG. 11 illustrates an example of a spectral efficiency of four cells before and after downtilting of one of the cells;

[0046] FIG. 12 illustrates an example of uplink signal-to-interference-plus-noise ratio of four cells before and after downtilting of one of the cells;

[0047] FIG. 13 illustrates an example of call drop rate in four cell before and after downtilting of one of the cells; and

[0048] FIG. 14 illustrates an example of a method for adjusting antenna tilt.

[0049] Like references are used to designate like parts in the accompanying drawings.DETAILED DESCRIPTION

[0050] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0051] FIG. 1 illustrates an example of a wireless communication network. Communication network 100 may comprise one or more devices, which may be also referred to as client nodes, user nodes, or user equipment (UE). An example of a device is UE 110, which may communicate with one or more access nodes 122, 124, 126 of a radio access network (RAN) 120. Signals transmitted by an access node to UE 110 may be referred to as downlink signals. Signals transmitted by UE 110 to an access node may be referred to as uplink signals. An access node may be also referred to as an access point or a base station. Communication network 100 may be configured for example in accordance with the 4thor 5thgeneration (4G, 5G) digital cellular communication networks, as defined by the 3rdGeneration Partnership Project (3 GPP). In one example, communication network 100 may operate according to 3 GPP (4G) LTE (Long-Term Evolution) or 3 GPP 5G NR (New Radio). Communication network 100 may hence comprise a cellular radio network. It is however appreciated that example embodiments presented herein are not limited to these example networks and may be applied in any present or futurewireless communication networks, or combinations thereof, for example other type of cellular networks, short-range wireless networks, multicast networks, broadcast networks, or the like. Access nodes 122, 124, 126 of RAN 120 may for example comprise 5thgeneration access nodes (gNB) or 4thgeneration access nodes (eNodeB).

[0052] An access node may provide communication services within one or more cells, illustrated with dotted circles, which may correspond to geographical area(s) covered by signals transmitted by the access node. For example, access node 122 may be configured to provide communication services within cell 132 and optionally within one or more other cells. Access node 124 may be configured to provide communication services within cell 134 and optionally within one or more other cells. A handover of UE 110 between cells may be performed when UE 110 is at or near the border of the coverage area of the cell. Other interactions between cells include UEs connected to a particular cell measuring signals of other cells and reporting the measurements to an access node of the particular cells, or vice versa.

[0053] Coverage areas of cells may overlap to some extent, for example to facilitate smooth handover for a mobile UE. The serving cell of UE 110 may be changed when another cell has stronger signal level. Even though some overlapping may be useful for handover purposes, it may be generally desired to minimize interference between cells. Excessive overlapping between cells may cause unnecessary interference and hence degrade performance of the network, for example in terms of achievable data rate.

[0054] Interference between cells may occur for example due to non-optimal antenna tilting. For example, insufficient antenna downtilt may be observed in communication network 100 as overshooting, that is, directing a radiation pattern of the antenna unnecessarily high, thereby extending the coverage area of the associated cell. It may be desired to efficiently detect overshooting cells such that corresponding counteraction(s) (e.g., antenna downtilting) may be performed. Also, it may be desired to detect undershooting cells, i.e., cells, where the radiation pattern of the antenna is directed unnecessarily steep towards the ground.

[0055] In the example of FIG. 1, coverage area of cell 132, served by access node 122, extends near access node 124, thereby causing interference deep withinthe coverage area of cell 134. Cell 132 may be considered to be overshooting, because its coverage area extends unnecessarily far. Example embodiments of the present disclosure enable adjustment of antenna tilt, in order to avoid unnecessary interference, but also to optimize network coverage by uptilting cells where possible. Uptilting / downtilting a cell may comprise uptilting / downtilting an antenna of the cell. Tilting an antenna may comprise physically redirecting the antenna or electrically adjusting the direction of the radiation pattern by applying differently delayed version of transmitted / received signals.

[0056] Communication network 100 may be operated based on a protocol stack comprising a plurality of protocol layers. The protocol stack may be arranged based on the open systems interconnection (OSI) model or a layer model of a particular standard. The protocol stack may comprise (e.g., in context of 3GPP systems) a service data adaptation protocol (SDAP) layer, which may receive data from an application layer for transmission. The SDAP layer may be configured to exchange data with the packet data convergence (PDCP) layer. The PDCP layer may be responsible of generation of data bursts comprising one or more data packets, for example based on data obtained from the SDAP layer.

[0057] Furthermore, a radio resource control (RRC) layer may be configured to operate on top of the PDCP layer. The RRC layer may be configured to control connection establishment and release functions for UEs, transmission of system information, establishment, reconfiguration and release of radio bearers, and mobility procedures (e.g. handover). UE 110 may be in various RRC states with respect to communication network 100. When UE 110 is powered up, it may be in a disconnected state or an idle state (e.g., RRC IDLE). UE 110 may move to a connected state (e.g. RRC CONNECTED) for example through connection establishment to the network. A cell, to which UE 110 is in an RRC connected state, may be called a serving cell of UE 110. In the connected state, UE 110 may be configured to perform radio resource management (RRM) measurements, for example in relation to a mobility procedure (e.g., handover). UE 110 may report its measurement results to the access node of the serving cell, for example periodically and / or in response to detecting a reporting triggering criterion to be fulfilled. RRC is provided as an example of a Layer 3 (network layer) protocol.

[0058] The PDCP layer may provide data to one or more instances of the radio link control (RLC) layer. For example, PDCP data may be transmitted on one or more RLC transmission legs. Each RLC instance may be associated with corresponding medium access control (MAC) instances of the MAC layer. The MAC layer may provide a mapping between logical channels of upper layer(s) and transport channels of the physical layer (PHY), handle multiplexing and demultiplexing of MAC service data units (SDU). Furthermore, the MAC layer may provide error correction functionality based on packet retransmissions, for example according to the hybrid automatic repeat request (HARQ) process. PDCP, RLC, and MAC may be considered as Layer 2 protocols. Physically separate transmission legs may be provided by the physical layer, also known as Layer 1 (LI). Corresponding protocol stacks may be applied both at RAN 120 (e.g., access node 122) and UE 110.

[0059] Communication network 100 may further comprise a core network 130, which may comprise various network functions (NF) for establishing, configuring, and controlling data communication sessions of users, for example UE 110. The data communication sessions may carry data traffic, for example application data associated with one or more applications running on UE 110. Communication network 100 may further comprise a network controller 140, which may be responsible of configuring various operations of RAN 120 and / or core network 130. Network controller 140 may be external to core network 130. Even though some operations have been described as being performed by network controller 140, it is understood that similar functions may be performed alternatively by other network device(s) or network function(s) of communication network 100. One task of network controller 140 may be to determine a level of interference between selected cells and cause adjustment of antenna tilt(s) of cells such that overshooting is avoided, or coverage of RAN 120 optimized in general. Network controller 140 may be also configured to remotely control antenna tilts of access node, for example to downtilt antenna(s) of overshooting cells. Network controller 140 may be configured to directly communicate with access nodes 122, 124, 126 of RAN 120. Direct transmission or reception of data may comprise transmitting data to the access nodes without routing the transmitted data via core network 130, or receivingthe data from the access nodes without the data being routed via core network 130. Network controller 140 may be for example configured to directly receive performance management (PM) data (e.g., measurement reports or data of the measurement reports) from the access nodes or directly transmit a request for adjusting antenna tilt to the access nodes.

[0060] Some communication networks may comprise a network management system (NMS) configured to process and store PM data of communication network 100. The PM data may comprise various types of information collected from different network elements, for example access nodes 122, 124, 126 of RAN 120. The NMS may be configured to operate as a centralized data management system (e.g., a server), which processes the collected data and provides it for network management functions, for example for antenna tilting applications. Alternatively, similar functionality may be provided at an operations support system (OSS) of communication network 100.

[0061] Examples of the PM data include timing advance (TA) values and received signal strength data (e.g., reference signal received power, RSRP) of different UEs at different cells. Timing advance may be used in communication network 100 to synchronize transmission and reception between UE 110 and the serving access node such that the propagation time of the signal over a particular distance between UE 110 and the access node is compensated. Timing advance values may therefore correlate with distances of UEs from the access node and the same applies also to received signal strength due to propagation loss.

[0062] Use of a centralized PM data management system (e.g., NMS) may come with the drawback of not being able to obtain the PM data at sufficient accuracy. For example, even if distance data (e.g., by means timing advance) were available, the distance data may be binned such that different instances of timing advance values are rounded to representative values of the respective bin. In raw measurement report data, the distance may be available at a more accurate level, for example with 78 m resolution. Binning the raw data to predefined bins (e.g., 0- 2 km, 2-4 km, etc.) may reduce the distance resolution significantly. The same applies to received signal strength (e.g., RSRP) data, which may not be available at all, or available only as binned data. Furthermore, the timing advance data may notbe correlated with the received signal strength data in NMS / OSS datasets, meaning that it may not be possible to determine the received signal strength at given distances. For example, timing advance distributions and RSRP distributions may be provided separately in the NMS / OSS data.

[0063] An example of raw measurement report data acquired from a single cell for multiple UEs is provided in the following table:Different rows of the table relate to measurements of different UEs. The first column indicates the source cell identifier (ID), i.e., the serving cell of the UE. Thesecond column indicates the downlink frequency of the cell by means of the evolved universal terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN). The third column indicates the timing advance value of the UE by means of the adjusted final TA value. The fourth column indicates the received signal strength of the serving cell by means of RSRP of the serving cell. The fifth column indicates the received signal strength of another cell by means of RSRP of the other cell. In this example, the other cell comprises a target cell of handover of the UE from the source cell to the target cell. It is noted that a UE may be configured to measure more than one target cell, for example in order to facilitate handover to the best available target cell. For simplicity, measurements related to one target cell are provided in the table. The sixth column indicates the signal-to-interference-plus- noise ratio (SINR) between the source and target cells determined based on the information in the fourth and fifth columns. It is therefore possible to correlate the timing advance (distance) of the second column with the received signal strength of the sixth column. For example, an average RSRP of the source or target cell, or their average SINR, may be calculated, optionally for different timing advance bins. Also, the number of UEs associated with a particular TA bin may be determined.

[0064] Example embodiments of the present disclosure therefore enable utilization of measurement reports of UEs directly (e.g., as provided in Layer 3 messages). This enables the input data for antenna tilting applications to be enriched significantly. For example, timing advance data may be obtained at the level of measurements (e.g., as defined by 3GPP), for example at the level of 39 m or 78 m. Correlation between timing advance data and received signal strength data may be preserved. Measurement report data of a cell may for example comprise measurement samples, e.g., received signal strength values, that are associated with particular values of timing advance or distance values, or range(s) thereof. For example, if cell 132 has N samples of UE measurements in 0-78 m timing advance bin, it is possible to obtain the received signal strength distribution in that timing advance bin.

[0065] These above benefits are associated with data of the serving cell. Furthermore, data from other cells may be obtained at a similar level of accuracy as UEs of a particular cell may be configured to measure and report received signalstrength of other (e.g., neighbouring) cells. This provides the benefit of enabling calculation of the level of interference between cells, and optionally within different bins of timing advance values. The level of interference may be provided as signal- to-interference-plus-noise ratio (SINR), or carrier-to-interference ratio (C / I).

[0066] Other possible methods for obtaining location with greater accuracy include MDT (minimization of drive test) functionality, which enables GPS (global positioning system) level accuracy. However, using MDT with GPS has the disadvantage that only some (e.g., 1-2 %) UEs support it and therefore the data obtained that way may not be applicable. Also, some device manufactures may not support sending GPS coordinates of UEs to the network. The methods disclosed herein do not have the above-mentioned limitations and hence PM data may be obtained from any UE with sufficient accuracy. Furthermore, example embodiments of the present disclosure enable mapping the measurement data (e.g., Layer 3) data to an identifier of the UE, for example the international mobile subscribed identity (IMSI). This provides the benefit of enabling user level optimization and analysis. For example, so called heavy users having relatively high data rate may be given a higher weight in network optimization.

[0067] FIG. 2 illustrates an example embodiment of an apparatus 200 configured to perform one or more example embodiments. Apparatus 200 may be for example used to implement network controller 140. Apparatus 200 may comprise at least one processor 202. The at least one processor 202 may comprise, for example, one or more of various processing devices or processor circuitry, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0068] Apparatus 200 may further comprise at least one memory 204. The at least one memory 204 may be configured to store, for example, computer program code 206 or the like, for example operating system software and application software. The at least one memory 204 may comprise one or more volatile memorydevices, one or more non-volatile memory devices, and / or a combination thereof. For example, the at least one memory 204 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0069] Apparatus 200 may further comprise a communication interface 208 configured to enable apparatus 200 to transmit and / or receive information to / from other devices, functions, or entities, for example to / from access nodes of RAN 120 or network functions of core network 130. In one example, apparatus 200 may use communication interface 208 to receive (raw) measurement report data from access nodes of RAN 120 or to provide network configuration instructions (e.g., for remote antenna tilting) to RAN 120 to prevent or reduce overshooting in one or more cells by antenna downtilting or to cause uptilting of particular cell(s) to improve network coverage. Such network configuration instructions may be for example provided as an automated service ticket to a human operator or as control instructions to antenna tilting equipment. Apparatus 200 may further comprise a user interface 210, for example for configuring apparatus 200 or for providing user output by apparatus 200, such as for example visual and / or audible signal(s), for example by speaker(s), display(s), light(s), or the like. In one example, network controller 140 may be configured to provide a request to a human user for adjusting the antenna tilt of cell(s).

[0070] When apparatus 200 is configured to implement some functionality, some component and / or components of apparatus 200, such as for example the at least one processor 202 and / or the at least one memory 204, may be configured to implement this functionality. Furthermore, when the at least one processor 202 is configured to implement some functionality, this functionality may be implemented using program code 206 comprised, for example, in the at least one memory 204.

[0071] The functionality described herein may be performed, at least in part, by one or more computer program product components such as for example software components. According to an embodiment, the apparatus comprises a processor or processor circuitry, such as for example a microcontroller, configuredby the program code when executed to execute the embodiments of the operations and functionality described. A computer program, a computer program product, or a non-transitory computer-readable medium may therefore comprise instructions for causing, when executed, apparatus 200 to perform the method(s) described herein. Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), applicationspecific Integrated Circuits (ASICs), application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs).

[0072] Apparatus 200 comprises means for performing at least one method described herein. In one example, the means comprises the at least one processor 202, the at least one memory 204 including program code 206 configured to, when executed by the at least one processor 202, cause apparatus 200 to perform the method. Apparatus 200 may comprise a computing device such as for example an access point, a base station, a server, a network device, a network function device, or the like. Although apparatus 200 is illustrated as a single device it is appreciated that, wherever applicable, functions of apparatus 200 may be distributed to a plurality of devices, for example to implement example embodiments as a cloud computing service.

[0073] FIG. 3 illustrates an example of a flow chart for adjusting antenna tilt. Even though operations of the flow chart have been described to be performed by network controller 140, they may be in general performed by any suitable device or function external to or within core network 130.

[0074] At operation 301, network controller 140 may be configured to receive performance management (PM) data. The PM data may be associated with one or more cells of communication network 100. PM data may be also referred to as performance data. PM data may comprise key performance indicators (KPI), such as for example SINR, RSRP, call drop rate, or the like, which may be also referred to as features.

[0075] Network controller 140 may be configured to receive the PM data (directly) from access node(s) of RAN 120. Directly receiving the PM data from an access node may comprise receiving the PM data from the access node without any intermediary devices configured to process the data, e.g., change format or content of the PM data. PM data received from one access node may comprise PM data of the cell served by that access node, measured by UEs connected to that cell as their serving cell. The PM data of the serving cell may comprise PM data of other cells measured by UE(s) connected to the serving cell. The PM data may comprise measurement data of target cell(s) of devices connected to the serving cell. A UE connected to a cell may have established a connection with communication network 100 via the cell at a particular level of the protocol stack, for example at Layer 3 (e.g., the RRC layer). A target cell may be a cell that is measured by a UE for a potential mobility procedure (e.g., handover). Receiving data concerning both the serving cell and other cell(s) from a single access node enables to compare the measurement data for different cell pairs of communication network 100.

[0076] For example, with reference to FIG. 4, UEs connected to cell 132 as their serving cell may be configured to measure signals (e.g., reference signals) of cell 132 received from access node 122. The UEs connected to cell 132 may be further configured to measure signals of their target cell 134 received from access node 124, and optionally also signals from other (target) cell(s) of RAN 120. UEs connected to cell 132 may be configured to report both types of measurements to access node 122. UEs connected to cell 134 as their serving cell may be configured to measure signals of cell 134 received from access node 124. The UEs connected to cell 134 may be further configured to measure signals of their target cell 132 received from access node 122, and optionally also signals from other (target) cell(s) of RAN 120. UEs connected to cell 134 may be configured to report the measurements to access node 124. Network controller 140 may be configured to receive the measurement data of the different cells from access node 122, access node 124, and optionally any other access node of RAN 120.

[0077] The measurement data received by network controller 140 may therefore comprise measurement data of signals of cell 132 measured by a (first) plurality of UEs connected to cell 132 as their serving cell and / or by another (second) pluralityof UEs connected to the target cell(s), for example cell 134 as the particular target cell. The measurement data received by network controller 140 may comprise measurement data of signals of cell 134 measured by the (first) plurality of UEs connected to cell 132 as their serving cell and / or by the other (second) plurality of UEs connected to cell 134 (the particular target cell). The measurement data may comprise a copy of the measurement data reported to access node 122 by the UEs connected to cell 132. In one example, the measurement data comprises a copy of the measurement report transmitted to access node 122 by the UEs connected to cell 132. Since the measurement data comprises raw measurement data received from RAN 120, the accuracy of the measurement data is better compared to obtaining the data from an NMS / OSS.

[0078] Network controller 140 may be configured to process the PM data before determining whether to adjust antenna tilt in one or more cells of RAN 120. Network controller 140 may be for example configured to disambiguate the PM data with respect to cell identity. The received measurement data may be associated with the physical cell identifier (PCI) and frequency (e.g., EARFCN). The PCI may not however uniquely identify the cell within RAN 120. Therefore, network controller 140 may be configured to assign unique cell identifiers for the purpose of optimizing antenna tilts at the cells.

[0079] Network controller 140 may be further configured to determine the received signal strength (e.g., RSRP) values for each cell, and optionally associate them with different timing advance values or bins of the respective cell. This information may be used for determining the level of interference between cells. For example, network controller 140 may be configured to calculate the SINR for each cell and / or timing advance value / bin. Network controller 140 may be configured to calculate the average, the median, or any other suitable statistical measure of the received signal strength, the level of interference, or timing advance for different cell pairs. The above calculations enable to determine the level of interference for any pair of cells, for example between the serving cell and a particular target cell of the UEs connected to the serving cell.

[0080] Network controller 140 may be configured to calculate a single server share of measurement samples. Measurement samples associated with a singleserver may comprise measurement samples with measurement data for the serving cell but no measurement data for other cells. The single server share may comprise the share of such measurement samples from the total number of measurement samples. The single server share may be calculated for a cell or a predetermined range of timing advance values (distance region) of the cell. In one example, the predetermined TA value range comprises an average TA bin, i.e., measurement samples of UEs located near an average distance from the access node of the serving cell. A high single server share may indicate that the serving cell is a predominant serving cell in the area of UEs, because the most UEs do not even measure the other cells.

[0081] Network controller 140 may be configured to determine any or all of the above parameters, e.g., received signal strength or interference level between cells, for different UEs separately. This enables user-level consideration of whether antenna tilt of cell(s) should be adjusted. For example, negative user impact of antenna downtilting to particular users may be avoided, as will be further described below.

[0082] At operation 302, network controller 140 may select a cell pair for determining whether one of the cells is to be downtilted or uptilted. A first cell of the cell pair may be a serving cell for a (first) plurality of UEs. A second cell of the cell pair may be a particular target cell for the plurality of UEs. The particular target cell may be a serving cell for another (second) plurality of UEs. The particular target cell may be one of the target cells of the UEs connected to the first cell (serving cell). For example, with reference to FIG. 4, cell 132 may be the serving cell for first plurality of UEs and cell 134 may be a serving cell for a second plurality of UEs. Cell 134 may be also one of the target cells for the first plurality of UEs. The serving cell may be also referred to as a source cell.

[0083] Network controller 140 may be configured to select cells that operate on same frequency range, for example cells with identical EARFCN. In general, network controller 140 may be configured to select the cell pair such that the serving cell and the particular target cell operate on overlapping frequency ranges. This provides the benefit of simplifying the interference analysis by considering cellsthat potentially interfere each other due to the partially of fully overlapping (downlink) frequency range.

[0084] Network controller 140 may be configured to select the cell pair such that antennas of the serving cell and the particular target cell point substantially towards each other. For example, a particular cell pair may be selected if angular deviations of the (horizontal) directions (01 ?02) of the antennas of the cell pair form a straight line between the access nodes of the cells is below a threshold (e.g., 10° or 20°). A direction of an antenna may be the direction of the centre of the main lobe of the radiation pattern of the antenna. Considering the antenna directions provides the benefit of improving efficiency of the antenna tilt optimization because cells pointing towards each other have a relatively high probability of interfering each other. It is however noted that it is possible to select the cell pair without considering their antenna directions or locations. For example, cell pairs could be selected arbitrarily, for example from a set of cells located within a particular geographical region.

[0085] At operation 303, network controller 140 may be configured to determine whether a condition on a number of UE interactions between the cell pair is met. Network controller 140 may be therefore configured to select, or to confirm selection of the cell pair based on the number of UE interactions between the cells. For example, network controller 140 may be configured to select the serving cell, in response to determining that the number of UE interactions between the serving cell and the particular target cell of the UEs of the serving cell exceeds a threshold.

[0086] Examples of device interactions include the number of handover attempts between the cells, the number of measurement reports of the UEs of the serving cell with respect to their target cells (e.g., the particular target cell), and the number of measurement reports of the UEs connected the target cell(s) with respect to the serving cell. Selecting the cell pair based on the number of UE interactions between the cells provides the benefit of improving accuracy of antenna tilt optimization because of antenna tilts of cells having sufficient amount of interactions and therefore mutual measurement reports. Furthermore, cells having a relatively high number of device interactions are likely to be interfering each other because the coverage areas are likely to have significant overlap.

[0087] Network controller 140 may move back to execution of operation 302 to select another cell pair, in response to determining that the condition on the number of UE interaction is not met. Network controller 140 may proceed to execution of operation 304, in response to determining that the condition on the number of UE interaction is met. It is however noted that execution of operation 303 may be optional. For example, in some example embodiments network controller 140 may proceed directly from execution of operation 302 to operation 304 without considering the number of UE interactions between the selected cell pair.

[0088] At operation 304, network controller 140 may be configured to determine whether a condition for uptilting or downtilting, or in general for adjusting antenna tilt, is met for the selected cell pair. Network controller 140 may be configured to determine a level of interference between the cell pair. Network controller 140 may be configured to determine the level of interference between the cell pair based on the measurement data of the serving cell and the measurement data of the particular target cell. The level of interference may comprise the SINR level between the cells calculated at operation 301 and / or the received signal strength of the serving cell at the particular target cell, e.g., as measured by the UEs connected to the particular target cell. The interference level may comprise an average or median interference level among UEs of the relevant cell, for example average or median SINR or average or median received signal strength.

[0089] The condition for adjusting the antenna tilt may comprise a threshold for the SINR (SINR threshold) between the serving cell and the particular target cell. Alternatively, or additionally, the condition may comprise a threshold for the received signal strength of the serving cell at the particular target cell. Network controller 140 may be configured to apply one or both of these conditions to determine whether to adjust antenna tilt for the selected cell pair. Network controller 140 may be configured to adjust the antenna tilt of the serving cell or the particular target cell, in response to determining that the level of interference meets the condition.

[0090] For example, network controller 140 may be configured to determine to downtilt either the serving cell or the particular target cell, in response to determining that the SINR between the cells is below the SINR threshold. Value ofthe SINR threshold may be for example 5 dB for downtilting and / or uptilting. Network controller 140 may be configured to determine to uptilt the serving cell or the particular target cell, in response to determining that the SINR exceeds the SINR threshold. Network controller 140 may be configured to determine to downtilt the serving cell or the particular target cell, in response to determining that the received signal strength of the serving cell exceeds the received signal strength threshold at the particular target cell (e.g., as measured by UEs of the particular target cell). Network controller 140 may be configured to determine to uptilt the serving cell or the particular target cell, in response to determining that the received signal strength of the serving cell is below the received signal strength threshold at the particular target cell. It is noted that values of the threshold for triggering downtilting or uptilting may be different such that between the threshold values for downtilting and uptilting network controller 140 is configured to determine not to adjust the antenna tilt of either cell.

[0091] Network controller 140 may be configured to apply the number of UEs connected to the serving cell and / or the number of UEs connected to the particular target cell as a further condition for determining to downtilt or uptilt a cell of the cell pair. For example, network controller 140 may be configured to determine to adjust the antenna tilt of the serving cell or the particular target cell, in response to determining that the number of the (first) plurality of UEs of the serving cell and / or the number of the other (second) plurality of UEs of the particular target cells exceeds a threshold (e.g., a minimum UE count). Network controller 140 may be configured to determine the number of UEs, at each cell, for example as a distinct UE identifier count, i.e., the number of different UE identifiers (e.g., IMSI) connected to the respective cell. This provides the benefit of avoiding antenna tilt adjustment, if the measurement data is not reliable enough due to a low number of UEs generating the measurement reports. Note that the number of samples of measurement data may be high even if the number of UEs were low. Therefore, considering the number of UEs as a condition for adjusting antenna tilt improves reliability.

[0092] Network controller 140 may be configured to apply, as a further condition for determining to downtilt or uptilt a cell of the cell pair, information onthe distribution of the samples of measurement data among the target cells of the UEs of the serving cell. For example, network controller 140 may be configured to determine to adjust the antenna tilt of the serving cell or the particular target cell, in response to determining that a share of samples of measurement data associated with both the serving cell and the particular target cell from a total number of samples of measurement data associated with the serving cell and any target cell of the plurality of devices exceeds a threshold. The threshold for the share of samples of measurement data may be for example in the range of 20-30 %. For example, network controller 140 may be configured to compare the number of samples of measurement data of cell 132 (serving cell), which relate to cell 134 (particular target cell), to the total number of samples of measurement data of serving cell with respect to any target cell of the UEs connected to cell 132 (serving cell). Additionally, network controller 140 may be configured to count the samples of measurement data originating from cell 134 (particular target cell) and relating to cell 132 as measurement samples associated with both the serving cell and the particular target cell. This provides the benefit of ensuring that the measurement data for the cell pair is reliable enough, when compared to measurement data associated with the other target cells.

[0093] Network controller 140 may be configured to proceed to execution of operation 305, in response to determining to downtilt one of the cells of the cell pair. Network controller 140 may be configured to proceed to execution of operation 309, in response to determining to uptilt one of the cells of the cell pair. Network controller 140 may be configured to move back to execution of operation 302 to select a new cell pair, in response to determining that the condition for adjusting antenna tilt was not met for the currently selected cell pair. At operations 305 to 307, network controller 140 may be configured to determine which cell of the cell pair is to be downtilted. At operation 309, network controller 140 may be configured to determine which cell of the cell pair is to be uptilted.

[0094] At operation 305, network controller 140 may be configured to select, from the cell pair, the cell with least measurement samples for downtilting. In other words, network controller 140 may be configured to determine to downtilt the serving cell, in response to determining that the number of samples of themeasurement data of the serving cell is lower than the number of samples of the measurement data of the particular target cell. Similarly, network controller 140 may be configured to determine to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is lower than the number of samples of the measurement data of the serving cell. The cell with least measurement samples is generally the interfering cell and therefore selecting the cell with least measurement samples for downtilting provides the benefit of efficiently reducing interference between the cell pair.

[0095] At operation 306, network controller 140 may be configured to determine whether the cell selected at operation 305 for downtilting is already heavily downtilted. This may be done based on comparing the half-power distance (3 dB distance) of the serving cell to a threshold (half-power distance threshold). The threshold may be equal to a calculated cell range of the serving cell. The cell range may be calculated based on the distance to the nearest cell operating on the same frequency range, for example by scaling the distance by a scaling factor such as for example 0.5. The scaling factor may be dependent on antenna height(s) of the selected cell and the nearest cell operating on the same frequency range. If the halfpower distance is already below the calculated cell range, network controller 140 may be configured to determine not to downtilt the selected cell. Alternatively, a threshold for an angle of downtilt (e.g., with respect to a horizontal plane) may be used. Network controller 140 may be configured to maintain the selection of the cell to be downtilted (cf. operation 305), if the selected cell is not already heavily downtilted, for example in response to determining that a condition for the current downtilting of the selected cell is not violated.

[0096] For example, considering the combination of operations 305 and 306, network controller 140 may be configured to determine to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the serving cell is lower than the number of samples of the measurement data of the particular target cell (cf. operation 305) and that a halfpower distance of the serving cell is below the threshold (half-power distance threshold), or in general that the condition for the current downtilting of the particular target cell is not violated (cf. operation 306). Similarly, networkcontroller 140 may be configured to determine to downtilt the serving cell, in response to determining that the number of samples of the measurement data of the particular target cell is lower than the number of samples of the measurement data of the serving cell and that a half-power distance of the particular cell is below the threshold (half-power distance threshold), or in general that the condition for the current downtilting of the serving cell is not violated. This provides the benefit of enabling to avoid excessive downtilting of cells, which might cause coverage holes between cells of RAN 120.

[0097] Network controller 140 may be configured with further conditions for downtilting the cell selected at operation 305 (cell with least samples). The measurement data of a cell (e.g., the serving cell, the particular target cell, or in general any target cell) may comprise measurement samples, for example received signal strength values, which may be associated with particular timing advance range(s)or distance range(s) of the cell. Network controller 140 may be configured to exploit the correlation between timing advance / distance and the received signal strength, when determining whether, how much, and / or in which direction to adjust the antenna tilt. Based on the correlation between the measurement data and timing advance / distance network controller 140 may be configured to determine the received signal strength and / or SINR at particular distance to the access node of the cell. For example, network controller 140 maybe configured to determine a number of samples of measurement data associated with a predetermined range of timing advance values at the serving cell but not including measurement data of any target cells of the (first) plurality of devices connected to the serving cell. Network controller 140 may be configured to compare this number to the total number of samples of the measurement data associated with the predetermined range of timing advance values at the serving cell, in order to determine a share of the samples associated with the predetermined range of timing advance values at the serving cell but not including measurement data of any target cells from the total number of samples. Network controller 140 may be configured to determine not to downtilt the serving cell (as the cell selected at operation 305), if the share is below a threshold (e.g., a threshold percentage, n %). The predetermined range of timing advance values may for example comprise the average timing advance bin, e.g.,timing advance values withing a certain range from the average timing advance of the serving cell. In other words, network controller 140 may be configured to determine not to downtilt the serving cell, if the single server share of the samples of measurement data at the serving cell is lower than the threshold. This provides the benefit of avoiding downtilting of a cell, if the UEs of the serving cell (at the selected TA range) are predominantly served by the cell subject to downtilting. Negatively affecting performance of communication network 100 by downtilting such a cell may be therefore avoided.

[0098] Network controller 140 may be configured to consider the capacity allocated to individual device(s) of a subset of devices of the serving cell when determining whether to downtilt the serving cell. For example, network controller 140 may be configured to not to downtilt the serving cell, in response to determining that a share of capacity of the serving cell allocated to a single device or a subset of the (first) plurality of devices connected to the serving cell exceeds a threshold (a capacity allocation threshold). This provides the benefit of avoiding downtilting of a cell, if there are UE(s) that consume a significant portion of the total capacity of the cell. Therefore, negatively affecting quality-of-service for such heavy users may be avoided.

[0099] If network controller 140 determines at operation 306 to keep the selection of the cell to be downtilted (cf. operation 305), network controller 140 may be configured to proceed to execution of operation 308 to cause downtilting of the selected cell. However, if the cell selected at operation 305 is already heavily downtilted, or network controller 140 otherwise determines not the downtilt the selected cell, network controller 140 may be configured to proceed to execution of operation 307 to select the cell with most samples of measurement data for downtilting.

[0100] Network controller 140 may be configured with further conditions for downtilting the cell selected at operation 307 (cell with most samples). For example, network controller 140 be configured to apply an upper limit for the number of samples of measurement data of the cell, for example relative to the cell with least samples of measurement data. The upper limit may be applied either when theserving cell is the cell with most samples of measurement data or when the particular target cell is the cell with most samples of measurement data.

[0101] Network controller 140 may be therefore configured to determine not to downtilt the serving cell, in response to determining that the number of samples of the measurement data of the serving cell is higher than a number of samples of the measurement data of the particular target cell (i.e., serving cell selected at operation 307) and exceeds a threshold (an upper limit for number of samples of the serving cell). Similarly, network controller 140 may be configured to determine not to downtilt the particular cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell (i.e., particular target cell selected at operation 307) and exceeds a threshold (an upper limit for number of samples of the particular target cell). In other words, if network controller 140 determines to downtilt the cell with most samples of measurement data, the count of samples of that cell would not be too high. The threshold may be provided as a percentage of the number of samples of the cell with most samples (subject to downtilting) and the number of samples of the cell with least samples, for example 150 %. This provides the benefit of avoiding downtilting of a cell, which predominantly serves the UEs. Negatively affecting performance of communication network 100 by downtilting such a cell may be therefore avoided.

[0102] Network controller 140 may move from execution of operation 307 to execution of operation 308. However, if any condition prevents downtilting the cell selected at operation 307, network controller 140 may move back to execution of operation 302 without causing downtilting of the cell at operation 308.

[0103] At operation 308, network controller 140 may be configured to cause downtilting of the selected cell. As described below, the selected cell may be either the serving cell or the particular target cell and the selected cell may have either the most or least samples of measurement data within the cell pair.

[0104] As illustrated in FIG. 5 and FIG. 6, network controller 140 may be configured to determine to downtilt the selected cell such that a half-power distance of the selected cell becomes smaller than an average distance between the access node of the downtilted cell and the UEs that measured the cell pair, e.g., the (first)plurality of UEs connected to the serving cell and the other (second) plurality of UEs connected to the particular target cell. The average distance may be also referred to as a minimum tilt distance (min tilt distance). The minimum tilt distance may be determined as the average distance, from the cell to be downtilted, where the cell with most samples of measurement data has been the serving cell (stronger) and the cell with least samples of measurement data has been measured. In the example of FIG. 5, the 3 dB distance of the cell with least samples of measurement data exceeds the average distance of UEs that measured both cells of the cell pair. Network controller 140 may determine to downtilt the cell with least samples such that its 3 dB distance becomes smaller than the average distance of the UEs from the access node of that cell (cf. FIG. 6). Note that the cell with least samples can be either the serving cell or the particular target cell. Same criterion for downtilting may be also applied when downtilting the cell with most samples of measurement data.

[0105] Referring back to FIG. 3, at operation 309 network controller 140 may be configured to select the cell with most samples of measurement data for uptilting. Note that this operation may be performed subject to determining that the condition for uptilting one of the cells of the cell pair is met at operation 304. Network controller 140 may be therefore configured to determine to uptilt the serving cell, in response to determining that the number of samples of the measurement data of the serving cell is higher than the number of samples of the measurement data of the particular target cell. Similarly, network controller 140 may be configured to determine to uptilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell. Selecting the cell with most samples for uptilting provides the benefit of improving signal strength of the cell that predominantly serves UEs in the area. This improves capacity of RAN 120, e.g., compared to uptilting the cell with least samples.

[0106] At operation 310, network controller 140 may be configured to cause uptilting of the selected cell. As described below, the selected cell may be either the serving cell or the particular target cell and the selected cell may have either the most or least samples of measurement data within the cell pair.

[0107] As illustrated in FIG. 7 and FIG. 8, network controller 140 may be configured to determine to uptilt the selected cell such that the half-power distance of the selected cell becomes higher than the average distance between the access node of the uptilted cell and the UEs that measured the cell pair, e.g., the (first) plurality of UEs connected to the serving cell and the other (second) plurality of UEs connected to the particular target cell. In the example of FIG. 7, the 3 dB distance of the cell with most samples of measurement data is lower than the average distance of UEs that measured both cells of the cell pair. Therefore, network controller 140 may determine to uptilt the cell with most samples such that its 3 dB distance becomes higher than the average distance of the UEs from the access node of that cell (cf. FIG. 8). The cell with most samples of measurement data may be either the serving cell or the particular target cell. Uptilting the cell with most samples of measurement data based on the 3 dB distance and average UE distance provides the benefit of improving signal strength at the uptilted cell for most of its UEs while not causing excessive interference to the cell with least samples.

[0108] At operations 308 or 310, network controller 140 may be configured to cause adjustment of the antenna tilt of the selected cell by outputting a request to adjust (downtilt or uptilt) the antenna tilt of the serving cell or the particular target cell. The request may be provided to a human user, for example as an automated service ticket. Alternatively, network controller 140 may cause the adjustment of the antenna tilt of the selected cell by outputting control instructions to a remote antenna tilting application. The request or the control instructions may comprise an identifier of the cell to be downtilted or uptilted, the amount of antenna tilt (e.g., an absolute tilting angle or a relative tilting angle with respect to the current tilting angle), or a desired half-power distance for the selected cell.

[0109] FIG. 9 illustrates an example of uptilting a cell based on an average user distance of the uptilted cell. In this example, network controller 140 may be configured to determine the average UE distance based on timing advance values of the selected cell, which is subject to uptilting. Hence, uptilting may be based on locations of UEs connected to the uptilted cell. The selected cell may be again the cell with most samples of measurement data in the cell pair. The selected cell maybe however either the serving cell or the particular target cell. Network controller 140 may be configured to determine to uptilt the selected cell such that the halfpower distance becomes higher than the average distance of UEs connected to the selected cell.[001 10] The examples of FIG. 7 and FIG. 8 are based on measured received signal strengths (e.g., RSRP) of a cell pair, while the example of FIG. 9 is based on the average received signal strength level measured for cell 132 in other cells (e.g., cells of access nodes 124, 126, 128 within angular range 142 of FIG. 4). Network controller 140 may be configured to uptilt cell 132, if the average received signal strength level of cell 132 at the other cells is below a threshold (e.g., -107 dBm) and / or if the SINR exceeds the SINR threshold (e.g., 5 dB). This provides the benefit of obtaining more measurement results compared to using cell pair based tilting. On the other hand, more specific antenna tilt adjustment may be achieved with cell pair based tilting.[001 1 1 ] FIG. 10 illustrates an example of a flow chart for adjusting antenna tilt of a serving cell. Even though operations of the flow chart have been described to be performed by network controller 140, they may be in general performed by any suitable device or function external to or within core network 130.[001 1 2] At operation 1001, network controller 140 may be to receive and / or process performance management (PM) data, similar to operation 301.[001 1 3] At operation 1002, network controller 140 may be configured to select a cell, referred in this example as the serving cell, for analysing whether antenna tilt of the selected cell should be adjusted. Network controller 140 may be configured to select the serving cell randomly or based on certain condition(s), such as for example the number of device interactions (e.g., handover attempts or measurement reports) between the serving cell and other cells. For example, network controller 140 may be configured to select the cells in the order of decreasing number of device interactions. This provides the benefit of considering adjustment of antenna tilt first for the cells that are likely to interfere other cells, which improves efficiency of optimising antenna tilts in RAN 120.[001 14] At operation 1003, network controller 140 may be configured to determine interference levels between the selected serving cell and target cells ofthe UEs connected to the serving cell. Network controller 140 may be configured to select the target cells by determining a plurality of affected cells affected by the serving cell. Network controller 140 may be configured to determine the affected cells based on topology of RAN 120, for example by finding cells located within a particular angular range 142 from the serving cell, as illustrated in FIG. 4. The selected target cells may include the particular target cell.[001 1 5] To determine the interference levels, network controller 140 may be configured to calculate the average received signal strengths (e.g., RSRP) of signal(s) of the serving cell at the target cells (as reported by UEs connected to the target cells via their respective access nodes). Network controller 140 may be configured to determine the average SINR values between the serving cell and the target cells.[001 1 6] At operation 1004, network controller 140 may be configured to determine whether a condition for uptilting or downtilting the serving cell is met. The condition may comprise the (average) SINR between the serving cell and the target cells or the (average) received signal strength of the serving cell at the target cells. Network controller 140 may be configured to determine to adjust the antenna tilt of the serving cell, in response to determining that the average interference level meets the condition.[001 1 7] For example, network controller 140 may be configured to determine to downtilt the serving cell, in response to determining that the average SINR between the serving cell and the target cells is below a threshold (average SINR threshold of affected cells). Alternatively, or additionally, network controller 140 may be configured to determine to downtilt the serving cell, in response to determining that the average received signal strength of the serving cell at the target cells exceeds a threshold (average received signal strength threshold of affected cells).[001 1 8] Determining to uptilt the serving cell may be further conditioned on the number of received signal strength samples exceeding a certain level (received signal strength threshold, e.g., -102 dBm) being high enough, for example the number of such samples exceeding another threshold (e.g., a high RSRP count threshold). Network controller 140 may be therefore configured to determine to uptilt the serving cell, further in response to determining that the number of samplesof measurement data that are indicative of the received signal strength (e.g., RSRP) of the serving cell at the of target cells exceeding the threshold (received signal strength threshold) exceeds the other threshold (high RSRP count threshold).[001 1 9] At operation 1005, network controller 140 may be configured to determine whether the serving cell is already heavily downtilted. Network controller 140 may be configured to determine not to downtilt the serving cell, if the serving cell is already heavily downtilted, for example as described above with reference to operation 306. Operation 1005 may be however optional. It is further noted that any of the conditions for determining not to downtilt the selected cell, as described with reference to FIG. 3, may be applied in context of the flow chart of FIG. 10 for the serving cell.[001 20] At operations 1006 and 1007, network controller 140 may be configured to cause downtilting or uptilting of the serving cell, for example as described with reference to operations 308 and 310, respectively.[001 21 ] FIG. 11 illustrates an example of a spectral efficiency of four cells before and after downtilting of one of the cells. Spectral efficiency is a performance indicator that can be used for monitoring performance of communication network 100. Spectral efficiency indicates the data rate of the data traffic, normalized by the bandwidth used for communicating the data traffic (bit / s / Hz). Spectral efficiency provides a measure of how efficiently the bandwidth is utilized in physical layer data transmission. The spectral efficiencies of the cells have been plotted with respect to time (days). In this example, antenna tilt of Cell 3 has been adjusted. The vertical dashed line indicates the time of the adjustment. It is noted that while the performance of Cell 3 itself has not improved, it can be seen that performance in Cells 1 , 2 and 4 in the surrounding network have improved significantly.[001 22] FIG. 12 illustrates an example of uplink SINR of four cells before and after downtilting of one of the cells. In this example, the SINR (dB) has been plotted with respect to time (days) and the time of adjusting antenna tilt of Cell 3 is again illustrated with the dashed line. Positive impact can be also seen in uplink performance. Adjusting the antenna tilt improves the SINR of Cell 3 (tilted cell) from less than 4 dB to approximately 7-8 dB.[001 23] FIG. 13 illustrates an example of call drop rate in three cells before and after downtilting of one of the cells. In this example, the call drop rate has been plotted with respect to time (days) and the time of adjusting antenna tilt of Cell 3 is again illustrated with the dashed line. It can be seen that the call drop rate has improved significantly due to the reduced interference level.[001 24] FIG. 14 illustrates an example of a method for adjusting antenna tilt. The method may be at least partially computer implemented.[001 25] At 1401, the method may comprise receiving, from a radio access network, performance management data comprising measurement data of a serving cell of a plurality of devices and measurement data of a particular target cell of the plurality of devices.[001 26] At 1402, the method may comprise determining a level of interference between the serving cell and the particular target cell based on the measurement data of the serving cell and the measurement data of the particular target cell.[001 27] At 1403, the method may comprise determining to adjust an antenna tilt of the serving cell or the particular target cell, in response to determining that the level of interference meets a condition.[001 28] Further features of the method directly result for example from the functionalities of network controller 140 or in general apparatus 200, as described throughout the specification and in the appended claims, and are therefore not repeated here. Different variations of the method may be also applied, as described in connection with the various example embodiments.

[0001] An apparatus, such as for example a network device configured to implement one or more network functions or entities, may be configured to perform or cause performance of any aspect of the method(s) described herein. Further, a computer program or a computer program product may comprise instructions for causing, when executed, an apparatus to perform any aspect of the method(s) described herein. Further, an apparatus may comprise means for performing any aspect of the method(s) described herein. According to an example embodiment, the means comprises at least one processor, and memory including program code, the at least one processor, and program code configured to, when executed by the at least one processor, cause performance of any aspect of the method(s). In general,computer program instructions may be executed on means providing generic processing functions. Such means may be embedded for example in a computer, a server, or the like. The method(s) may be thus computer-implemented, for example based algorithm(s) executable by the generic processing functions, an example of which is the at least one processor 202.[001 29] Any range or device value given herein may be extended or altered without losing the effect sought. Also, any embodiment may be combined with another embodiment unless explicitly disallowed.[001 30] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.[001 31 ] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items.[001 32] The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the example embodiments described above may be combined with aspects of any of the other example embodiments described to form further example embodiments without losing the effect sought.[001 33] The term 'comprising' is used herein to mean including the method, blocks, or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements. [001 34] Although subjects may be referred to as ‘first’ or ‘second’ subjects, this does not necessarily indicate any order or importance of the subjects. Instead, suchattributes may be used solely for the purpose of making a difference between subjects.[001 35] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification.

Claims

CLAIMS1. A computer-implemented method, comprising: receiving, from a radio access network, performance management data comprising measurement data of a serving cell of a plurality of devices and measurement data of a particular target cell of the plurality of devices; determining a level of interference between the serving cell and the particular target cell based on the measurement data of the serving cell and the measurement data of the particular target cell, wherein the measurement data of the serving cell comprises received signal strength values associated with one or more timing advance ranges or distance ranges of the serving cell, and / or in that the measurement data of the particular target cell comprises received signal strength values associated with one or more timing advance ranges or distance ranges of the particular target cell; and determining to adjust an antenna tilt of the serving cell or an antenna tilt of the particular target cell, in response to determining that the level of interference meets a condition.

2. The method according to claim 1, wherein the performance management data is received from at least one access node of the radio access network.

3. The method according to claim 1 or 2, wherein the measurement data of the serving cell comprises measurement report data of signals of the serving cell measured by the plurality of devices and / or by another plurality of devices served by the particular target cell, and wherein the measurement data of the particular target cell comprises measurement report data of signals of the particular cell measured by the plurality of devices and / or by the another plurality of devices.

4. The method according to claim 3, further comprising: determining to adjust the antenna tilt of the serving cell or the antenna tilt of the particular target cell, further in response to determining that a number of theplurality of devices and / or a number of the another plurality of devices exceeds a first threshold.

5. The method according to claim any of claims 1 to 4 further comprising: determining to adjust the antenna tilt of the serving cell or the antenna tilt of the particular target cell, further in response to determining that a share of samples of measurement data associated with both the serving cell and the particular target cell from a total number of samples of measurement data associated with the serving cell and any target cell of the plurality of devices exceeds a second threshold.

6. The method according to any of claims 1 to 5, wherein the condition comprises a third threshold for a signal-to-interference-plus-noise ratio between the serving cell and the particular target cell, and / or wherein the condition comprises a fourth threshold for a received signal strength of the serving cell at the particular target cell.

7. The method according to claim 6, further comprising: determining to downtilt the serving cell or the particular target cell, in response to determining that the signal-to-interference-plus-noise ratio is below the third threshold, or determining to uptilt the serving cell or the particular target cell, in response to determining that the signal-to-interference-plus-noise ratio exceeds the third threshold.

8. The method according to claim 6 or 7, further comprising: determining to downtilt the serving cell or the particular target cell, in response to determining that a received signal strength of the serving cell exceeds the fourth threshold at the particular target cell, or determining to uptilt the serving cell or the particular target cell, in response to determining that the received signal strength of the serving cell is below the fourth threshold at the particular target cell.

9. The method according to any of claims 1 to 8, further comprising: determining to downtilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is lower than a number of samples of the measurement data of the particular target cell, or determining to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target is lower than the number of samples of the measurement data of the serving cell.

10. The method according to claim 9, further comprising: determining to downtilt the serving cell such that a half-power distance of the serving cell is smaller than an average distance of the plurality of devices from an access node of the serving cell, or determining to downtilt the particular target cell such that a half-power distance of the particular target cell is smaller than an average distance of the another plurality of devices from an access node of the particular target cell.

11. The method according to any of claims 1 to 6, further comprising: determining to downtilt the particular target cell, in response to determining that a number of samples of the measurement data of the serving cell is lower than a number of samples of the measurement data of the particular target cell and that a half-power distance of the serving cell is below a fifth threshold, or determining to downtilt the serving cell, in response to determining that the number of samples of the measurement data of the particular target is lower than the number of samples of the measurement data of the serving cell and that a halfpower distance of the particular cell is below the fifth threshold.

12. The method according to any of claims 1 to 6, further comprising: determining not to downtilt the serving cell, in response to determining that a share of samples of measurement data associated with a predetermined range of timing advance values at the serving cell but not including measurement data of any target cells of the plurality of devices from a total number of samples of themeasurement data associated with the range of timing advance values at the serving cell exceeds a sixth threshold, determining not to downtilt the serving cell, in response to determining that a share of capacity of the serving cell allocated to a single device or a subset of the plurality of devices exceeds a seventh threshold, and / or determining not to downtilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is higher than a number of samples of the measurement data of the particular target cell and exceeds an eighth threshold, or determining not to downtilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell and exceeds the eighth threshold.

13. The method according to any of claims 1 to 6, further comprising: determining to uptilt the serving cell, in response to determining that a number of samples of the measurement data of the serving cell is higher than a number of samples of the measurement data of the particular target cell, or determining to uptilt the particular target cell, in response to determining that the number of samples of the measurement data of the particular target cell is higher than the number of samples of the measurement data of the serving cell.

14. The method according to claim 13, further comprising: determining to uptilt the serving cell such that a half-power distance of the serving cell is higher than an average distance of the plurality of devices from an access node of the serving cell, or determining to uptilt the particular target cell such that a half-power distance of the particular target cell is higher than an average distance of the another plurality of devices from an access node of the particular target cell.

15. The method according to any of claims 1 to 14, further comprising:selecting the particular target cell such that antennas of the serving cell and the particular target cell point substantially towards each other.

16. The method according to any of claims 1 to 15, further comprising: selecting the particular target cell, in response to detecting a number of device interactions between the serving cell and the particular target cell exceeding a target.

17. The method according to claim 16, wherein the device interactions comprise handover attempts of devices between the serving cell and the particular target cell, measurement reports of the plurality of devices with respect to the particular target cell, or measurement reports of the another plurality of devices with respect to the serving cell.

18. The method according to any of claims 1 to 5, further comprising: selecting a plurality of target cells comprising the particular target cell; determining an average interference level between the serving cell and the plurality of target cells; and determining to adjust the antenna tilt of the serving cell, in response to determining that the average interference level meets the condition.

19. The method according to claim 18, wherein the average interference level between the serving cell and the plurality of target cells comprises an average signal-to-interference-plus-noise ratio between the serving cell and the plurality of target cells, and wherein the method further comprises: determining to downtilt the serving cell, in response to determining that the average signal-to-interference-plus-noise ratio between the serving cell and the plurality of target cells is below a ninth threshold and / or that an average received signal strength of the serving cell at the plurality of target cells exceeds a tenth threshold, or determining to uptilt the serving cell, in response to determining that the average signal-to-interference-plus-noise ratio between the serving cell and theplurality of target cells exceeds the ninth threshold and / or that the average received signal strength of the serving cell at the plurality of target cells is below the tenth threshold.

20. The method according to claim 19, further comprising: determining to downtilt the serving cell such that a half-power distance of the serving cell is smaller than a distance between an access node of the serving cell and an access node of a nearest target cell to the serving cell.

21. The method according to claim 19, further comprising: determining to uptilt the serving cell, further in response to determining that a number of samples of measurement data indicative of a received signal strength of the serving cell at the plurality of target cells exceeding an eleventh threshold exceeds a twelfth threshold.

22. The method according to claim 19 or 21, further comprising: determining to uptilt the serving cell such that a half-power distance of the serving cell is higher than an average distance of the plurality of devices from an access node of the serving cell.

23. The method according to any of claims 1 to 22, further comprising: outputting a request to adjust the antenna tilt of the serving cell or the antenna tilt of the particular target cell, or causing adjustment of the antenna tilt of the serving cell or the antenna tilt of the particular target cell.

24. The method according to any of claims 1 to 23, wherein the performance management data is received from an access node of the serving cell and / or an access node of the particular target cell.

25. An apparatus comprising means for performing the method according to any of claims 1 to 24.

26. The apparatus according to claim 25, wherein the means comprises at least one processor, and memory including program code, the at least one processor, and program code configured to, when executed by the at least one processor, cause performance of the method according to any of claims 1 to 24.

27. A computer program comprising program code configured to, when executed by a processor, cause an apparatus at least to perform the method according to any of claims 1 to 24.

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