WO2022177483A1

WO2022177483A1 - Network node and method in for coordinating reference signals in a wireless communications network

Info

Publication number: WO2022177483A1
Application number: PCT/SE2021/050148
Authority: WO
Inventors: Magnus Hurd; Rikke Apelfrojd; Sven PETERSON
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2022-08-25

Abstract

A method performed by a first network node for coordinating reference signals, of at least one neighbouring network node for upcoming communications with UEs in a wireless communications network is provided. When a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node, is an offset better than a quality value of a reference signal transmitted by the first network node, the first network node receives (501) one or more measurement reports from one or more UEs served in the first network node. The respective one or more measurement reports from the respective one or more UEs comprises: The quality value of the reference signal transmitted by that neighbouring network node and the index assigned to that reference signal for each of the at least one neighbouring network nodes, and a quality value of a reference signal transmitted by the first network node and the index assigned to that reference signal. Based on the one or more measurement reports, the first network node identifies (502) two network nodes among the at least one neighbouring network node and the first network node, that are assigned the same index to their respective transmitted reference signals. The first network node coordinates (503) the reference signals by configuring at least one of the two identified network nodes to switch any one out of: The index for its reference signals, or the direction of its reference signals. Publ.

Description

NETWORK NODE AND METHOD IN FOR COORDINATING REFERENCE SIGNALS IN A WIRELESS COMMUNICATIONS NETWORK

TECHNICAL FIELD Embodiments herein relate to a network node and a method therein. In some aspects, they relate to coordinating reference signals of at least one neighbouring network node for upcoming communications with User Equipments (UEs) in a wireless communications network. BACKGROUND

In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or User Equipments (UE), communicate via a Local Area Network such as a Wi-Fi network or a Radio Access Network (RAN) to one or more Core Network (CN)s. The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a W-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a NodeB, eNodeB (eNB), or gNB as denoted in Fifth Generation (5G) telecommunications. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.

Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a 5G network also referred to as 5G New Radio (NR). The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access network wherein the radio network nodes are directly connected to the EPC core network rather than to RNCs used in 3G networks. In general, in E- UTRAN/LTE the functions of a 3G RNC are distributed between the radio network nodes, e.g. eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially “flat” architecture comprising radio network nodes connected directly to one or more core networks, i.e. they are not connected to RNCs. To compensate for that, the E- UTRAN specification defines a direct interface between the radio network nodes, this interface being denoted the X2 interface.

Multi-antenna techniques may significantly increase the data rates and reliability of a wireless communication system. The performance is in particular improved if both the transmitter and the receiver are equipped with multiple antennas, which results in a Multiple-Input Multiple-Output (MIMO) communication channel. Such systems and/or related techniques are commonly referred to as MIMO.

High band deployment of wireless communications systems is in 3GPP referred to as deployment on frequency range 2 (FR2) meaning frequencies higher than 6 GHz. To cope with coverage challenges at higher frequencies more antenna elements are needed at the base station side and the UE side for communication over the air interface. In NR the notion of massive antenna arrays has been introduced to achieve both increased coverage and increased level of throughput. These antenna arrays are sometimes referred to as Advanced Antenna Systems (AAS), which is simply a panel of antenna elements allowing to steer a beam by means of complex weights. To reduce the cost of AAS, the complex weights are typically applied to the antenna elements by means of time-domain beamforming. Beamforming when used herein e.g. means to enable communication with a UE using beams that maximize the energy received at the UE.

Time-domain beamforming means that one beamform applies to all frequency resources being part of a transmission as shown in Figure 1.

Figure 2 depicts a cell covered by a set of SSBs transmitted in different directions Typically, a set of predefined beamforms Ai are designed to cover a certain spatial area such as seen in Figure 2, a so-called Grid of Beams (GOB). Each such beamform would transmit a specific Synchronization Signal Block (SSB) labeled by an SSB index. For FR2, there can be at most M of these SSBs which means the index ranges from 0 to M-1. For NR Release 15 M is 64 for FR2. The SSBs provides the UEs with an opportunity to synchronize to and in general access the network. It will measure on a Primary Synchronization Sequence (PSS) and Secondary Synchronization Sequence (SSS) to determine a Physical Cell identity (PCI).

A PSS when used herein means a Binary Phase-Shift Keying (BPSK) modulated m- sequence of length 127 as explained in 38.211. The PSS is located in the first symbol of the SSB. There are three different m-sequences, each representing one out of three physical-layer identities.

An SSS when used herein means a combination of BPSK modulated m-sequences of length 127 as explained in 38.211 , The SSS sequences come in 1008 different variants, divided into three groups of 336 sequences, each mapped to one PSS sequence.

An SSB covers 4 symbols; the first symbol contains PSS and the third symbol contains SSS. The remaining resource elements covered by the 4 symbols may be allocated to Physical Broadcast Channel (PBCH).

First the UE determines which one out of three different PSS sequences that is transmitted. Then the UE investigates which of 336 SSS sequences is transmitted. The two sequences combine to form one out of 1008 PCIs.

The SSBs are transmitted during an SSB burst, which is repeated by a certain periodicity. The configuration parameter relating to the position of an SSB in an SSB Burst, referred to as ssb-PositionslnBurst, see 3GPP 38.331, is transmitted in SIB1, applicable for standalone deployment, or is transmitted in ServingCellConfigCommon as part of RRC configuration on an LTE leg, applicable for non-standalone deployment. The configuration parameter is a bitmap signifying what indices, also referred to as indexes, are actually provided in the cell. (It should be noted that both words "indexes" and "indices" are plural forms of the word "index" or to refer to more than one index.) Each SSB and each index of an SSB, is associated to a Physical Random Access Channel (PRACH) occasion as described in 3GPP 38.213, section 8.1. The PRACH occasion obviously occurs in an uplink slot. This means that a base station such as a gNB may prepare its spatial filter, beamforming weights, to receive a random access preamble according to a beamform that was previously used for the associated SSB index.

The meaning of the ssb-PositionslnBurst defines what frequency-time resources that are used for a specific beamformed version of the SSB. Each of the predefined beamforms Ai in Figure 2 associates to a certain position in the ssb-PositionslnBurst, this is referred to that each beamform Ai corresponds to a certain SSB index.

Generally, cellular wireless technologies are exposed to the problem of transmissions from different base stations interfering with each other. An example of this may be SSBs from cell neighbors. On the other hand, SSB transmissions from cell neighbors are important for presenting mobility options for a connected UE.

For the sake of mobility, a UE may be configured with a so-called A3 event, see 3GPP 38.331, that requests the UE to report a measurement whenever a neighbour SSB becomes offset better than a serving cell. Technically the serving cell would be an SpCell, which means Primary cell (PCell) or Primary SCG Cell (PSCell). It is the SpCell that offers preamble resources to the UE in uplink.

The base station may then organize a handover to the target cell indicated in the A3 measurement report.

SUMMARY

As a part of developing embodiments herein a problem was identified by the inventors and will first be discussed.

SSBs that are transmitted concurrently, in other words SSBs corresponding to the same index in the ssb-PositionslnBurst, but from different base stations may collide to cover the same area. As a result, a UE attaching to the network from this area now sees many versions of an SSB index, each version from a different base station or in other words, SSB index versions with different PCIs. Just by probability the UE may select an SSB version associated to a less favorable base station and connect to a less favorable cell.

The probability for a faulty selection of SSB version associated to a less favorable base station, increases as a Reference Signal Received Power (RSRP) for the different index versions become comparable. The probability also increases if more than one neighboring interfering base stations share the same PSS sequence. This PSS aspect is to some degree possible to counter-act using cell planning. The cell planning may be performed such that the neighbor base stations are allocated different PSS sequences: However, since there are only three different PSS sequences, clearly the next-nearest neighbors are subject to PSS collisions. Again, the underlying reason for the collision is that SSB beamforms from different cells partially cover the same area at the same frequency/time.

Accordingly, the base station would serve such a UE less favorably until, e.g. by means of handover, a new better base station has been identified.

A beam and a signal when used herein means a train of modulation symbols allocated to a range of frequency resources at each time instant. A beam when used herein may mean a set of complex antenna weights such that the power of the beforementioned signal fed into the AAS is directed towards a spatial region

Figure 3 depicts a plot of a scenario simulated with three gNBs providing radio coverage such as beamforms that are transmitting reference signals in an area where a UE is located. At the UE, the received signal power, i.e. RSRP from SSBs, over a beam from one gNB is stronger than the received signal power from the other gNBs. The gNB providing the strong reference signal power at the UE is denoted the main gNB. All three gNBs have the strongest RSRP in a beam within the same time-frequency resource, i.e. the same reference signal index. The short term fading of the gNBs are independent meaning that the combination of beam and gNB that is strongest on average may momentarily be weaker than a different combination of beam and gNB. The reference signals from each of the interfering gNBs are on average 3 dB weaker at the UE than the reference signal from the main gNB, so the total Signal-to-lnterference ratio (SIR) at the strongest beam of the main gNB is 0 dB, for the two interfering scenarios. The SNR on the x-axis in Figure 3 shows the SNR in the strongest beam from the main gNB.

The graph in Figure 3 shows the probability for the UE of selecting a different gNB than the main in three different scenarios in relation to Signal-to-Noise Ratio (SNR). One scenario when all gNBs have different PSS sequences, marked with stars, and one scenario when the two interfering gNBs share the same PSS sequence but the main gNB has a different PSS sequence from the interferes, marked with rhombs. As a comparison, a case with no interfering gNBs is added, marked with triangles.

Figure 3 illustrates the problem that a UE may select wrong gNB, also referred to as base station, when close-by base stations transmit SSBs with same indices. The problem is worse when close-by base stations share a PSS that is different from the PSS at the main gNB. A problem addressed herein is thus interference that occurs between cells, when beams of close-by cells happen to cover same area. An object of embodiments herein is to mitigate interference of reference signals in a wireless communications network.

According to an aspect of embodiments herein, the object is achieved by a method performed by a first network node for coordinating reference signals of at least one neighbouring network node for upcoming communications with User Equipments, UEs, in a wireless communications network.

The first network node receives one or more measurement reports from one or more UEs served in the first network node. The one or more measurement reports are received when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node, is an offset better than a quality value of a reference signal transmitted by the first network node.

The respective one or more measurement reports from the respective one or more UEs comprises: The quality value of the reference signal transmitted by that neighbouring network node and the index assigned to that reference signal for each of the at least one neighbouring network nodes, and a quality value of a reference signal transmitted by the first network node and the index assigned to that reference signal.

Based on the one or more measurement reports, the first network node identifies two network nodes among the at least one neighbouring network node and the first network node, that are assigned the same index to their respective transmitted reference signals.

The first network node coordinates the reference signals by configuring at least one of the two identified network nodes to switch any one out of: The index for its reference signals, or the direction of its reference signals. According to another aspect of embodiments herein, the object is achieved by a first network node configured to coordinate reference signals of at least one neighbouring network node for upcoming communications with User Equipments, UEs, in a wireless communications network. The first network node is further configured to:

Receive one or more measurement reports from one or more UEs served in the first network node, when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node is an offset better than a quality value of a reference signal transmitted by the first network node,

The respective one or more measurement reports from the respective one or more UEs are adapted to comprise:

- for each of the at least one neighbouring network nodes, the quality value of the reference signal transmitted by that neighbouring network node, and the index assigned to that reference signal, and

- a quality value of a reference signal transmitted by the first network node, and the index assigned to that reference signal, based on the one or more measurement reports, identify two network nodes among the at least one neighbouring network node and the first network node, that are assigned the same index to their respective transmitted reference signals, and coordinate the reference signals by configuring at least one of the two identified network nodes to switch any one out of: The index for its reference signals, or the direction of its reference signals.

Since at least two network nodes that are assigned the same index to their respective transmitted reference signals are identified, and at least one of these two identified network nodes are configured to switch the index for its reference signals or the direction of its reference signals, the interference of these reference signals in the wireless communications network is mitigated.

An advantage is that the method above improves an initial configuration with beamforms transmitting reference signals planned in beforehand such that reference signals provided by neighbour network nodes appear to not interfere. E.g. such an initial strategy may simply be to have beamforms pointing in directions such they do not intersect with neighbour beamforms.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail with reference to attached drawings in which: Figure 1 is a schematic block diagram illustrating prior art. Figure 2 is a schematic block diagram illustrating prior art. Figure 3 is a schematic diagram illustrating prior art. Figure 4 is a schematic block diagram illustrating embodiments of a wireless communications network. Figure 5 is a flowchart depicting embodiments of a method in a first network node Figure 6a-b are schematic block diagrams illustrating embodiments of a first network node.

Figure 7 schematically illustrates a telecommunication network connected via an intermediate network to a host computer. Figure 8 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection. Figures 9-12 are flowcharts illustrating methods implemented in a communication system including a host computer, a base station and a user equipment.

DETAILED DESCRIPTION

According to an example of some embodiments herein, a UE sends measurement reports to its serving network node e.g. gNB, when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node, is an offset better than a quality value of a reference signal transmitted by the serving network node. E.g. the UE sends the measurement report when RSRP for neighbouring SSBs approaches the RSRP of a serving cell for a specific SSB index.

Periodically the network node then configures at least one of two identified colliding network nodes to switch index for its reference signals, or direction, e.g. by means of beamforming weights, of its reference signals. E.g. the network node configures gNBs to reshuffle beamforms among its SSBs with indexes for which RSRP are considered too close to corresponding neighbours.

This reduces the risk of the UEs selecting wrong cell when SSBs of same index from different cells cover the same area.

An advantage of embodiments herein is that they provide mitigation of effects from reference signals such as SSB collisions between neighbouring network nodes without manual operation. This will enable more accurate attachment procedure such that the UE selects the most appropriate cell. Figure 4 is a schematic overview depicting a wireless communications network 100 wherein embodiments herein may be implemented. The wireless communications network 100 comprises one or more RANs, and one or more CNs. The wireless communications network 100, the RAN and the CN may use a number of different technologies, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, 5G, NR, Wdeband Code Division Multiple Access (WCDMA), Global System for Mobile communications/enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. Embodiments herein relate to recent technology trends that are of particular interest in a 5G context, however, embodiments are also applicable in further development of the existing wireless communication systems such as e.g. WCDMA and LTE.

A number of network nodes operate in the wireless communications network 100 such as e g. a first network node 111, and at least one neighbouring network node 112, 113. A neighbouring network node when used herein means a network node that is neighbour to the first network node, in terms of radio coverage. More specifically, a neighboring network node in this context may mean the quality value reported for an index of that node (or cell) is close enough compared to the corresponding index of the first network node.

The first network node 111 provides radio coverage in cell 115. The neighbouring network node 112 provides radio coverage in cell 116, and the neighbouring network node 113 provides radio coverage in cell 117.

The network nodes 111, 112, 113, may each be any of a radio network node, NG- RAN node, a transmission and reception point e.g. a base station, a TRP, a radio access network node, a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, an evolved Node B (eNB, eNode B), a gNB, a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a UE such as a UE 120, within a service area served by the respective network node 111, 112, 113, depending e.g. on the first radio access technology and terminology used. The first network node 111 may be referred to as a serving radio network node. The respective network node 111, 112, 113 communicates with the UE 120 with Downlink (DL) transmissions to the UE 120 and Uplink (UL) transmissions from the UE 120.

Beamforming when used herein e.g. means to enable a network node such as the respective network node 111, 112, 113, communication with a UE such as the UE 120, that is using beams being directed towards the UE. A network node, such as the network nodes 111, 112, 113, is normally able to transmit beams in different directions, and each such beam may transmit reference signals assigned with, also referred to as labeled with, an index. The index is used for representing what frequency-time resources are used for SSB transmission.

The beams transmitted by a network node, such as any of the network nodes 111, 112, 113, will define a cell provided by that network node.

One or more UEs such as e.g. the UE 120, operate in the wireless communications network 100. The UE 120 may also be referred to as a device, an loT device, a mobile station, a non-access point (non-AP) STA, a STA, a user equipment and/or a wireless terminals, communicate via one or more Access Networks (AN), e.g. RAN, to one or more CNs. It should be understood by the skilled in the art that “wireless device” is a non limiting term which means any terminal, wireless communication terminal, user equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell. The UE 120 is in some example scenarios served by the first network node 111 in the cell 115.

Methods herein may be performed by the first network node 111. As an alternative, a Distributed Node (DN) and functionality, e.g. comprised in a cloud 130 as shown in Figure 4, may be used for performing or partly performing the methods herein.

The above described problem is addressed in a number of embodiments, some of which may be seen as alternatives, while some may be used in combination.

Embodiments of a method will first be described in a more general way together with Figure 5. Embodiments of the method will then be exemplified and described more in detail later on in the document. Figure 5 shows example embodiments of a method performed by the first network node 111 for coordinating reference signals, of at least one neighbouring network node

112, 113 for upcoming communications with UEs in the wireless communications network 100.

Coordinating reference signals, such as e g. SSBs, e g. means to coordinate coverage of the reference signals transmitted from the first network node with the at least one neighbouring network node 112, 113, such beams comprising reference signals assigned with identical indices of neighbouring network nodes 112, 113 may maximize the probability that one of them, and one of them only, cover the area of a potential UE served by the system.

Regarding the “upcoming communications with UEs” it may e g. mean that the method is performed with assistance of at least one of the UEs 121, 122, 123, and the result of the coordination will be used later on for upcoming communications with any UEs served by the first network node 111.

The method comprises the following actions, which actions may be taken in any suitable order. Optional actions are referred to as dashed boxes in Figure 5.

Action 501

The first network node 111 receives one or more measurement reports from one or more UEs 121 , 122, 123 served in the first network node 111. The one or more measurement reports are received when a quality value, of a reference signal such as e.g. RSRP, assigned a specific index transmitted by a neighbouring network node 112,

113, is an offset better than a quality value of a reference signal transmitted by the first network node 111. This is e.g. since the UEs 121, 122, 123 should send a report only when it may be assumed that a neighbouring network node 112, 113 provide stronger signals than the serving network node 111 and which e.g. would require a handover to such neighbouring network node 112, 113.

It should be noted that the offset may be negative. This means the first network node 111 receives the one or more measurement reports when a neighbouring network node 112, 113, approaches quality value levels, e.g. RSRP levels, comparable to the quality value, e.g. RSRP, of the serving first network node 111 , as measured by the UE 120.

This e.g. means that the first network node 111 registers a quality value A and the neighbouring network node 112, 113 registers a quality B. Whenever (B + offset) exceeds A this means the condition of measurement is fulfilled. The parameter offset , as defined here, being positive means that the measurement condition is fulfilled for relatively smaller values B compared to A; offset being negative means that that the measurement condition is fulfilled for relatively larger values B compared to A. At any rate, this defines when the measurement happens. In the actual measurement the quality values would be reported.

The respective one or more measurement reports received from the respective one or more UEs 121 , 122, 123 e.g. means that one or more measurement report may be received from the UE 121, one or more measurement report may be received from the UE 122, and one or more measurement report may be received from the UE 123.

The respective one or more measurement report from the respective one or more UEs 121, 122, 123 comprises:

- for each of the at least one neighbouring network nodes 112, 113, the quality value of the reference signal transmitted by that neighbouring network node 112, 113, and the index assigned to that reference signal, and

- a quality value of a reference signal transmitted by the first network node 111, and the index assigned to that reference signal.

The reference signal being assigned an index may e.g. be referred to as the reference signal being labeled with an index. For example, a reference signal such as an SSB labeled by an index such as an SSB index.

E.g. see the following example scenario wherein the first network node 111 receives measurement reports from three different UEs 121, 122, 123, e.g. located at three different places.

First UE 121 :

According to an example scenario, this e.g. means that a first UE, the UE 121 measures reference signals transmitted by the neighbouring network node 112, and reference signals transmitted by the neighbouring network node 113, and other possibly other neighbouring network nodes. In this case, the one or more measurement report received from the UE 121, comprises the quality value of the reference signal transmitted by the neighbouring network node 112 and the index assigned to that reference signal, and the quality value of the reference signal transmitted by the neighbouring network node 113 and the index assigned to that reference signal.

According to an example scenario, the first UE 121 further measures reference signals transmitted by the first network node 111. The one or more measurement report received from the UE 121, thus further comprises a quality value of a reference signal transmitted by the first network node 111, and the index assigned to that reference signal.

Second UE 122:

According to the example scenario, this may further mean that a second UE, the UE

122 e.g. located in another place than the UE 121, measures reference signals transmitted by the neighbouring network node 112, and reference signals transmitted by the neighbouring network node 113, and other possibly other neighbouring network nodes. In this case, the one or more measurement report received from the second UE 122, comprises the quality value of the reference signal transmitted by the neighbouring network node 112 and the index assigned to that reference signal, and the quality value of the reference signal transmitted by the neighbouring network node 113 and the index assigned to that reference signal.

According to an example scenario, the second UE, the UE 122 further measures reference signals transmitted by the first network node 111. The one or more measurement reports received from the UE 122, thus further comprises a quality value of a reference signal transmitted by the first network node 111, and the index assigned to that reference signal.

Third UE 123:

According to the example scenario, this may further mean that a third UE, the UE

123 e.g. located in another place than the UE 121 and the UE 122, measures reference signals transmitted by the neighbouring network node 112, and reference signals transmitted by the neighbouring network node 113, and other possibly other neighbouring network nodes. In this case, the one or more measurement report received from the third UE 123, comprises the quality value of the reference signal transmitted by the neighbouring network node 112 and the index assigned to that reference signal, and the quality value of the reference signal transmitted by the neighbouring network node 113 and the index assigned to that reference signal.

According to an example scenario, the first UE, the third UE 123 further measures reference signals transmitted by the first network node 111. The one or more measurement report received from the third UE 123, thus further comprises a quality value of a reference signal transmitted by the first network node 111, and the index assigned to that reference signal.

In some embodiments the index assigned to a reference signal is associated with time and frequency resources of that reference signal. This may mean that the index is mapped to, e.g. indicates, time and frequency resources of that reference signal. Mapped in this context may both refer to assigning an implementation parameter e.g., a beamform, and an assignment to resources as defined in 3GPP.

In some embodiments the index assigned to a reference signal is further associated with a direction of that reference signal. This may mean that the index is mapped to, e.g. indicates, the direction of that reference signal.

In some embodiments an offset better than a quality value relates to a signal quality value adjusted for being measured with a spatial filter tuned for the first network node 111. This may mean that that the UE121 , 122, 123 has had time to analyze what antenna elements together with beam weights associated with the elements, to select for receiving the SSBs of the first network node. This may be performed in these embodiments to compensate for that the UE 121 , 122, 123 has had time to tune its spatial filters for the reference signals of the serving first network node 111 but not the neighbouring network nodes 112, 113. To compare the neighbouring network nodes 112, 113 with the with the serving first network node 111 would otherwise be unfair.

Action 502

Based on the one or more measurement reports, the first network node 111 obtains two identified network nodes two network nodes 111, 112, 113 that are assigned the same index to their respective transmitted reference signals. The two network nodes 111, 112, 113 are identified among the at least one neighbouring network node 112, 113 and the first network node 111. This is e.g. to find colliding network nodes whose reference signals need to be coordinated. The identifying may be performed by the first network node 111, typical case, but may also be made by any other node able to receive the relevant information. Thus the two identified two network nodes 111, 112, 113 may be obtained by receiving information about two identified two network nodes 111, 112, 113, or the first network node 111 may itself identify the two identified two network nodes 111, 112, 113.

The identification may be based on comparing quality values of first network node 111 and neighboring node 112, 113. When neighboring node 112, 113 quality value is close enough to the first network node 111 quality value, e.g. by an offset, it does not need to be same as the one for measurement condition, it corresponds to an identification. In other words, a colliding node with a colliding index.

The two identified network nodes 111, 112, 113 may e.g. either comprise two neighbouring network nodes 112, 113 or one neighbouring network node 112 and the first network node 111. This, in some embodiments the identified two network nodes 111, 112, 113 comprise at least two neighbouring network nodes 112, 113.

Action 503

The first network node 111 coordinates the reference signals by configuring at least one of the two identified network nodes 111, 112, 113 to switch any one out of: The index for its reference signals, or the direction of its reference signals. This e.g. means configuring at least one of the two identified network nodes 111, 112, 113 to switch the index for its reference signals, or to switch the direction of its reference signals. When switched, the identified network nodes with identified colliding indices are allowed to operate with new SSB configuration. If this corresponds to an improvement the UEs would report less frequently on indices with neighboring quality values too close to the quality values of the first network node.

The first network node 111 may perform the coordinating several times a day when a network first is deployed. But in some embodiments, first network node 111 may eventually have trained itself based on the data measurement reports so that it knows which direction and/or index mapping cause as few collisions as possible. Then it would not need to reconfigure very often, but rather when something changes the environment or traffic settings, e.g. seasonal changes or a popular cafe opening in a place where no UEs used to be. Preferably it will be performed when it would improve for more UEs than it would cause problems based on the measurement reports so far, and when there is no to low load.

Thus, in some embodiments the coordinating of the reference signals by configuring at least one of the two identified network nodes 111, 112, 113, is performed at times of low or no traffic load in the wireless communications network 100. This is an advantage since service of currently connected and active UEs would be affected by a sudden reconfiguration of SSB transmissions of the serving node. This may e.g. be during nights or when the traffic load is below a threshold.

The configuring of the at least one of the two identified network nodes 111, 112, 113 to switch any one out of the index for its reference signals, or the direction of its reference signals such as e.g. change beamforms for SSBs in the SSB burst, is most conveniently performed at times of low or no load in order not to affect traffic too much. It is an advantage to avoid compromising measurements for the UEs 121, 122, 123 currently served by the first network node 111. In some embodiments coordinating the reference signals by configuring at least one of the two identified network nodes 111, 112, 113 further comprises adjusting the index assigned to a reference signal to be associated with another direction not currently used. This is an advantage since this may avoid beams from different nodes covering a common area.

In another embodiment, coordinating the reference signals by configuring at least one of the two identified network nodes 111, 112, 113 further comprises to change the colliding index to another index not currently used.

In some embodiments coordinating the reference signals is performed by configuring the at least two identified neighbouring network nodes 112, 113 one by one according to a schedule such that adjustments are not done concurrently in two neighbouring network nodes 112, 113. In this way according to some embodiments, the first network node 111 triggers the switching behavior described above for a subset of the neighbouring network nodes 112, 113 in a round-robin fashion to ensure the neighbouring network nodes 112, 113 do not concurrently optimize their reference signals, such as e.g. SSBs. After some time, the optimization has been executed for all neighbouring network nodes 112, 113. Then the procedure may start all over again. The above embodiments will now be further explained and exemplified below. The embodiments below may be combined with any suitable embodiment above.

By the configuration of at least one of the identified network nodes 111, 112, 113 according to embodiments herein, the transmitting reference signals, such as e.g. beamforms for transmitting reference signals, may be planned in beforehand such that reference signals provided by neighbour network nodes appear to not interfere. The strategy may e.g. simply be to have reference signals, e.g. beamforms comprising reference signals, pointing in directions such they do not intersect with neighbour reference signals, e.g. beamforms comprising reference signals.

However, in some scenarios, e.g. with spatial irregularities of the environment causing scattering, it is not obvious that collisions may be avoided. Therefore, in some embodiments a more dynamic procedure as described below may be useful and improve the initial deployment of a network. An initial deployment of a network means that beamforms and indices are assigned in a simplistic manner without considering scattering of the radio environment.

The UE 120 may in these embodiments, e.g. based on A3 events, be configured to report to the first network node 111, whenever a specific reference signal index of a neighbour network node 112, 113 is offset better than the first network node 111, in terms of measured quality value of a reference signal, e.g. RSRP.

As mentioned above, the offset may be negative. This means the first network node 111 is notified when a neighbouring network node 112, 113, e.g. a neighbouring beam of a neighbouring network node 112, 113, approaches quality value levels, e.g. RSRP levels, comparable to the quality value, e.g. RSRP, of the serving first network node 111, as measured by the UE 120.

It should be noted that A3 measurements are being made in connected mode. This means that the UE 120 has had time to tune its spatial filters for the reference signals, such as SSBs, of the serving first network node 111. As mentioned above, comparing neighbouring network nodes 112,113 with the serving first network node 111, e.g. the neighbouring cells 116, 117 with the serving cell 115, may therefore be unfair and the selected offset needs to compensate for this. Also note that for initial attachment the UE 120 likely would not yet have tuned its filters when measuring SSB candidates.

Since the index e.g. the SSB index and the quality value of the reference signal, e.g. RSRP, is part of the measurement report, the first network node 111 may maintain a record of quality values of the reference signals, e.g. RSRP, for neighbouring network nodes 112,113 per index, in addition to the corresponding reference signals, e.g. RSRP, of its own. Indices, e.g. SSB indices, for which neighbouring network nodes 112,113 such as neighbour cells, exceed a threshold, e.g. an RSRP threshold, relative to its own indices, are considered candidates for coordination of reference signals by configuring at least one of the two identified network nodes 111, 112, 113 to switch the index for its reference signals, or the direction of its reference signals, e.g. to be allocated different beamforms. A convenient way to coordinate the reference signals such as e.g. by switching the index for the reference signals, or the direction of the reference signals, e.g. by changing the allocation of beamforms is to simply switch the index or the direction of the reference signals, e.g. switch the beamforms between a pair of candidates.

In some embodiments, the first network node 111 monitors the frequency of said A3 events. If this frequency is higher than a threshold then the first network node 111 may change beamforms for candidates. The first network node 111 may trigger the switching behaviour described above for a subset of the neighbouring network nodes 112,113 in a round-robin fashion to ensure that the neighbouring network nodes 112,113 do not concurrently optimize their reference signals such as e.g. SSBs. After some time, the optimization has been executed for all base stations. Then the procedure starts all over again.

Embodiments herein aims to reducing the number of handovers that does not represent true mobility, which is seen as overhead. In general, a UE served by a weaker network node such as gNB would come out with lower key performance indicators, including e.g. throughput, latency, energy savings. These two aspects are addressed according to embodiments herein, reduced handover frequency and generally improved level of service. For FR1 there is less freedom to adjust since 3GPP allows maximum 4 frequency-time resources for frequencies up to 3 GHz and maximum 8 frequency-time resources for frequencies between 3 GHz and 6 GHz, indices, to choose from for SSB. However, the adaptive procedure, with similar measurement reports, may in some embodiments be applied also for FR1. In these embodiments, the frequency-time resource is changed whenever the algorithm senses collision or a very small number of wider beams could be reshuffled. As a result, this means automatic network planning also for FR1. The same way, it would be possible for FR2 to use all 64 potential SSB resources to mitigate interference on those.

To perform the method actions above, the first network node 111 is configured to coordinate reference signals of at least one neighbouring network node 112, 113 for upcoming communications with UEs 121, 122, 123 in the wireless communications network 100. The first network node 111 may comprise an arrangement depicted in Figures 6a and 6b.

The first network node 111 may comprise an input and output interface 600 configured to communicate with UEs such as the UEs 121, 122, 123. The input and output interface 600 may comprise a wireless receiver (not shown) and a wireless transmitter (not shown).

The first network node 111 may further be configured to, e.g. by means of an receiving unit 610 in the first network node 111, receive one or more measurement reports from one or more UEs 121, 122, 123 served in the first network node 111, when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node 112, 113, is an offset better than a quality value of a reference signal transmitted by the first network node 111, which respective one or more measurement report from the respective one or more UEs 121, 122, 123 are adapted to comprise:

The first network node 111 may further be configured to, e.g. by means of an identifying unit 620 in the first network node 111, based on the one or more measurement reports, obtain two identified network nodes 111, 112, 113 among the at least one neighbouring network node 112, 113 and the first network node 111, that are assigned the same index to their respective transmitted reference signals.

The first network node 111 may further be configured to, e.g. by means of an coordinating unit 630 in the first network node 111, coordinate the reference signals by configuring at least one of the two identified network nodes 111, 112, 113 to switch any one out of: The index for its reference signals, or the direction of its reference signals.

The first network node 111 may further be configured to, e.g. by means of the coordinating unit 630 in the first network node 111, coordinate the reference signals by performing the configuring of at least one of the two identified network nodes 111, 112,

113 at times of low or no traffic load in the wireless communications network 100.

The first network node 111 may further be configured to, e.g. by means of the coordinating unit 630 in the first network node 111, coordinate the reference signals by configuring at least one of the two identified network nodes 111, 112, 113 and by further adjusting the index assigned to a reference signal to be associated with another direction not currently used.

The first network node 111 may further be configured to, e.g. by means of the coordinating unit 630 in the first network node 111, coordinate the reference signals by configuring the at least two identified neighbouring network nodes 112, 113 one by one according to a schedule such that adjustments are adapted to not be done concurrently in two neighbouring network nodes 112, 113. In some embodiments the index adapted to be assigned to a reference signal is further adapted to be associated with time and frequency resources of that reference signal.

In some embodiments the index adapted to be assigned to a reference signal is further adapted to be associated with a direction of that reference signal.

In some embodiments the identified two network nodes 111, 112, 113 are adapted to comprise at least two neighbouring network nodes 112, 113.

In some embodiments an offset better than a quality value relates to a signal quality value adjusted for being measured with a spatial filter adapted to be tuned for the first network node 111.

The embodiments herein may be implemented through a respective processor or one or more processors, such as the processor 660 of a processing circuitry in the first network node 111 depicted in Figure 6a, together with respective computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the first network node 111. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the first network node 111.

The first network node 111 may further comprise a memory 670 comprising one or more memory units. The memory 670 comprises instructions executable by the processor in first network node 111. The memory 670 is arranged to be used to store e.g. information, indices, directions, indications, data, configurations, and applications to perform the methods herein when being executed in the first network node 111.

In some embodiments, a computer program 680 comprises instructions, which when executed by the respective at least one processor 660, cause the at least one processor of the first network node 111 to perform the actions above.

In some embodiments, a respective carrier 690 comprises the respective computer program 680, wherein the carrier 690 is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium. Those skilled in the art will appreciate that the units in the first network node 111 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in the first network node 111, that when executed by the respective one or more processors such as the processors described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a- chip (SoC).

With reference to Figure 7, in accordance with an embodiment, a communication system includes a telecommunication network 3210, such as a 3GPP-type cellular network, e.g. radio network 102, which comprises an access network 3211, such as a radio access network, and a core network 3214. The access network 3211 comprises a plurality of base stations 3212a, 3212b, 3212c, such as AP STAs NBs, eNBs, gNBs, e.g. the first network node 111 , or other types of wireless access points, each defining a corresponding coverage area 3213a, 3213b, 3213c. Each base station 3212a, 3212b, 3212c is connectable to the core network 3214 over a wired or wireless connection 3215. A first UE such as a Non-AP STA 3291, e.g. the UE 121, 122, 123, located in coverage area 3213c is configured to wirelessly connect to, or be paged by, the corresponding base station 3212c. A second UE 3292 such as a Non-AP STA in coverage area 3213a is wirelessly connectable to the corresponding base station 3212a. While a plurality of UEs 3291, 3292 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 3212.

The telecommunication network 3210 is itself connected to a host computer 3230, which may be embodied in the hardware and/or software of a standalone server, a cloud- implemented server, a distributed server or as processing resources in a server farm. The host computer 3230 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 3221, 3222 between the telecommunication network 3210 and the host computer 3230 may extend directly from the core network 3214 to the host computer 3230 or may go via an optional intermediate network 3220. The intermediate network 3220 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 3220, if any, may be a backbone network or the Internet; in particular, the intermediate network 3220 may comprise two or more sub-networks (not shown).

The communication system of Figure 7 as a whole enables connectivity between one of the connected UEs 3291, 3292 and the host computer 3230. The connectivity may be described as an over-the-top (OTT) connection 3250. The host computer 3230 and the connected UEs 3291, 3292 are configured to communicate data and/or signaling via the OTT connection 3250, using the access network 3211, the core network 3214, any intermediate network 3220 and possible further infrastructure (not shown) as intermediaries. The OTT connection 3250 may be transparent in the sense that the participating communication devices through which the OTT connection 3250 passes are unaware of routing of uplink and downlink communications. For example, a base station 3212 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 3230 to be forwarded (e.g., handed over) to a connected UE 3291. Similarly, the base station 3212 need not be aware of the future routing of an outgoing uplink communication originating from the UE 3291 towards the host computer 3230.

Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to Figure 8. In a communication system 3300, a host computer 3310 comprises hardware 3315 including a communication interface 3316 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 3300. The host computer 3310 further comprises processing circuitry 3318, which may have storage and/or processing capabilities. In particular, the processing circuitry 3318 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The host computer 3310 further comprises software 3311 , which is stored in or accessible by the host computer 3310 and executable by the processing circuitry 3318. The software 3311 includes a host application 3312. The host application 3312 may be operable to provide a service to a remote user, such as a UE 3330 connecting via an OTT connection 3350 terminating at the UE 3330 and the host computer 3310. In providing the service to the remote user, the host application 3312 may provide user data which is transmitted using the OTT connection 3350. The communication system 3300 further includes a base station 3320 provided in a telecommunication system and comprising hardware 3325 enabling it to communicate with the host computer 3310 and with the UE 3330. The hardware 3325 may include a communication interface 3326 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 3300, as well as a radio interface 3327 for setting up and maintaining at least a wireless connection 3370 with a UE 3330 located in a coverage area (not shown in Figure 8) served by the base station 3320. The communication interface 3326 may be configured to facilitate a connection 3360 to the host computer 3310. The connection 3360 may be direct or it may pass through a core network (not shown in Figure 8) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 3325 of the base station 3320 further includes processing circuitry 3328, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The base station 3320 further has software 3321 stored internally or accessible via an external connection.

The communication system 3300 further includes the UE 3330 already referred to.

Its hardware 3335 may include a radio interface 3337 configured to set up and maintain a wireless connection 3370 with a base station serving a coverage area in which the UE 3330 is currently located. The hardware 3335 of the UE 3330 further includes processing circuitry 3338, which may comprise one or more programmable processors, application- specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The UE 3330 further comprises software 3331, which is stored in or accessible by the UE 3330 and executable by the processing circuitry 3338. The software 3331 includes a client application 3332. The client application 3332 may be operable to provide a service to a human or non-human user via the UE 3330, with the support of the host computer 3310. In the host computer 3310, an executing host application 3312 may communicate with the executing client application 3332 via the OTT connection 3350 terminating at the UE 3330 and the host computer 3310. In providing the service to the user, the client application 3332 may receive request data from the host application 3312 and provide user data in response to the request data. The OTT connection 3350 may transfer both the request data and the user data. The client application 3332 may interact with the user to generate the user data that it provides. It is noted that the host computer 3310, base station 3320 and UE 3330 illustrated in Figure 8 may be identical to the host computer 3230, one of the base stations 3212a, 3212b, 3212c and one of the UEs 3291, 3292 of Figure 7, respectively. This is to say, the inner workings of these entities may be as shown in Figure 8 and independently, the surrounding network topology may be that of Figure 7.

In Figure 8, the OTT connection 3350 has been drawn abstractly to illustrate the communication between the host computer 3310 and the use equipment 3330 via the base station 3320, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the UE 3330 or from the service provider operating the host computer 3310, or both. While the OTT connection 3350 is active, the network infrastructure may further take decisions by which it dynamically changes the routing, e.g., on the basis of load balancing consideration or reconfiguration of the network.

The wireless connection 3370 between the UE 3330 and the base station 3320 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 3330 using the OTT connection 3350, in which the wireless connection 3370 forms the last segment. More precisely, the teachings of these embodiments may improve the RAN effect: data rate, latency, power consumption and thereby provide benefits such as corresponding effect on the OTT service: reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime.

A measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 3350 between the host computer 3310 and UE 3330, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 3350 may be implemented in the software 3311 of the host computer 3310 or in the software 3331 of the UE 3330, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 3350 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 3311, 3331 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 3350 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 3320, and it may be unknown or imperceptible to the base station 3320. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer’s 3310 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 3311, 3331 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 3350 while it monitors propagation times, errors etc.

Figure 9 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station such as a AP STA, and a UE such as a Non-AP STA which may be those described with reference to Figure 7 and Figure 8. For simplicity of the present disclosure, only drawing references to Figure 9 will be included in this section. In a first step 3410 of the method, the host computer provides user data. In an optional substep 3411 of the first step 3410, the host computer provides the user data by executing a host application. In a second step 3420, the host computer initiates a transmission carrying the user data to the UE. In an optional third step 3430, the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure.

In an optional fourth step 3440, the UE executes a client application associated with the host application executed by the host computer.

Figure 10 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station such as a AP STA, and a UE such as a Non-AP STA which may be those described with reference to Figure 7 and Figure 8. For simplicity of the present disclosure, only drawing references to Figure 10 will be included in this section. In a first step 3510 of the method, the host computer provides user data. In an optional substep (not shown) the host computer provides the user data by executing a host application. In a second step 3520, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step 3530, the UE receives the user data carried in the transmission. Figure 11 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station such as a AP STA, and a UE such as a Non-AP STA which may be those described with reference to Figure 7 and Figure 8. For simplicity of the present disclosure, only drawing references to Figure 11 will be included in this section. In an optional first step 3610 of the method, the UE receives input data provided by the host computer. Additionally, or alternatively, in an optional second step 3620, the UE provides user data. In an optional substep 3621 of the second step 3620, the UE provides the user data by executing a client application. In a further optional substep 3611 of the first step 3610, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in an optional third substep 3630, transmission of the user data to the host computer. In a fourth step 3640 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

Figure 12 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station such as an AP STA, and a UE such as a Non-AP STA which may be those described with reference to Figure 7 and Figure 8. For simplicity of the present disclosure, only drawing references to Figure 12 will be included in this section. In an optional first step 3710 of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In an optional second step 3720, the base station initiates transmission of the received user data to the host computer. In a third step 3730, the host computer receives the user data carried in the transmission initiated by the base station.

When using the word "comprise" or “comprising” it shall be interpreted as non limiting, i.e. meaning "consist at least of".

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used.

Claims

1. A method performed by a first network node (111) for coordinating reference signals, of at least one neighbouring network node (112, 113) for upcoming communications with User Equipments, UEs, in a wireless communications network (100), the method comprising: receiving (501) one or more measurement reports from one or more UEs (121, 122, 123) served in the first network node (111), when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node (112, 113), is an offset better than a quality value of a reference signal transmitted by the first network node (111), which respective one or more measurement report from the respective one or more UEs (121, 122, 123) comprises:

- for each of the at least one neighbouring network nodes (112, 113), the quality value of the reference signal transmitted by that neighbouring network node (112, 113), and the index assigned to that reference signal, and

- a quality value of a reference signal transmitted by the first network node (111), and the index assigned to that reference signal, based on the one or more measurement reports, obtaining (502) two identified network nodes (111, 112, 113) among the at least one neighbouring network node (112, 113) and the first network node (111), that are assigned the same index to their respective transmitted reference signals, coordinating (503) the reference signals by configuring at least one of the wo identified network nodes (111, 112, 113) to switch any one out of: the index for its reference signals, or the direction of its reference signals.

2. The method according to claim 1 , wherein the coordinating (503) of the reference signals by configuring at least one of the two identified network nodes (111, 112, 113), is performed at times of low or no traffic load in the part of the wireless communications network (100) affected by the coordination.

3. The method according to any of the claims 1-2, wherein the index assigned to a reference signal represents time and frequency resources of that reference signal.

4. The method according to any of the claims 1-3, wherein the index assigned to a reference signal is further associated with a direction of that reference signal.

5. The method according to any of the claims 1-4, wherein coordinating (503) the reference signals by configuring at least one of the two identified network nodes (111, 112, 113) further comprises any one out of: adjusting the index which is colliding assigned to a reference signal to be associated with another direction not currently used for this index, or switching the index which is colliding to an index not currently used.

6. The method according to any of claims 1-5, wherein the identified two network nodes (111, 112, 113) comprise at least one of the two neighbouring network nodes (112, 113), and wherein coordinating (503) the reference signals is performed by configuring the at least one of the identified network nodes (111, 112, 113) one by one according to a schedule such that adjustments are not done concurrently in two neighbouring network nodes (111, 112, 113).

7. The method according to any of claims 1-6, wherein an offset better than a quality value relates to a signal quality value adjusted for being measured with a spatial filter tuned for the first network node (111).

8. A computer program (680) comprising instructions, which when executed by a processor (660), causes the processor (660) to perform actions according to any of the claims 1-7.

9. A carrier (690) comprising the computer program (680) of claim 8, wherein the carrier (690) is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.

10. A first network node (111) configured to coordinate reference signals of at least one neighbouring network node (112, 113) for upcoming communications with User Equipments, UEs, in a wireless communications network (100), the first network node (111) further being configured to: receive one or more measurement reports from one or more UEs (121, 122, 123) served in the first network node (111), when a quality value of a reference signal assigned a specific index transmitted by a neighbouring network node (112, 113), is an offset better than a quality value of a reference signal transmitted by the first network node (111), which respective one or more measurement report from the respective one or more UEs (121, 122, 123) are adapted to comprise:

- a quality value of a reference signal transmitted by the first network node (111), and the index assigned to that reference signal, based on the one or more measurement reports, obtain two identified network nodes (111, 112, 113) among the at least one neighbouring network node (112, 113) and the first network node (111), that are assigned the same index to their respective transmitted reference signals, and coordinate the reference signals by configuring at least one of the_two identified network nodes (111, 112, 113) to switch any one out of: the index for its reference signals, or the direction of its reference signals.

11. The first network node (111) according to claim 10, further configured to coordinate the reference signals by performing the configuring of at least one of the two identified network nodes (111, 112, 113) at times of low or no traffic load in the wireless communications network (100).

12. The first network node (111) according to any of the claims 10-11, wherein the index adapted to be assigned to a reference signal is further adapted to represent time and frequency resources of that reference signal.

13. The first network node (111) according to any of the claims 10-12, wherein the index adapted to be assigned to a reference signal is further adapted to be associated with a direction of that reference signal.

14. The first network node (111) according to any of the claims 10-13, further configured to coordinate the reference signals by configuring at least one of the two identified network nodes (111, 112, 113) and by further any one out of: adjust the index which is colliding assigned to a reference signal to be associated with another direction not currently used for this index, or switch the index which is colliding to an index not currently used.

15. The first network node (111) according to any of the claims 10-14, wherein the identified two network nodes (111, 112, 113) are adapted to comprise at least one neighbouring network nodes (111, 112, 113), and wherein the first network node (111) is further configured to coordinate the reference signals by configuring the at least one of the identified network nodes (111, 112, 113) one by one according to a schedule such that adjustments are adapted to not be done concurrently in two neighbouring network nodes (111, 112, 113).

16. The first network node (111) according to any of the claims 10-15, wherein an offset better than a quality value relates to a signal quality value adjusted for being measured with a spatial filter adapted to be tuned for the first network node (111).