WO2023287329A1

WO2023287329A1 - Selection of tdd pattern for an access network node

Info

Publication number: WO2023287329A1
Application number: PCT/SE2021/050724
Authority: WO
Inventors: Sara SANDBERG; Peter De Bruin; Arne Simonsson
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2021-07-13
Filing date: 2021-07-13
Publication date: 2023-01-19

Abstract

There is provided mechanisms for selecting a first TDD pattern for a first access network node. The first TDD pattern comprises first DL slots for DL communication and first UL slots for UL communication. A method comprises obtaining information of a second TDD pattern used by a second access node neighboring the first access network node and comprises second DL slots and second UL slots, each of which is composed of symbols. The method comprises obtaining information of UL/DL traffic distribution of by the first access network node. The method comprises selecting the first TDD pattern so as to match the second TDD pattern in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots. How many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

Description

SELECTION OF TDD PATTERN FOR AN ACCESS NETWORK NODE TECHNICAL FIELD

Embodiments presented herein relate to a method, a network management node, a computer program, and a computer program product for selecting a time-division duplex pattern for an access network node.

BACKGROUND

In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed. For example, one parameter in providing good performance and capacity for a given communications protocol in a communications network is the ability to communicate using time-division duplex (TDD). In TDD, some subframes/slots are allocated for downlink transmissions (i.e., from the network node at the network side towards terminal devices served in the network by the network node) and some subframes/slots are allocated for uplink transmissions (i.e. from the terminal devices towards the network node). The switch between downlink and uplink occurs in so- called special subframes (using Long Term Evolution (LTE), or fourth generation telecommunication systems, terminology) or so-called flexible subframes (using new radio (NR), or fifth generation telecommunication systems, terminology). As illustrated in Table 1, which is identical to Table 4.2-2 in 3GPP TS 36.211 V15.2.0, in LTE, and where “D” denotes downlink subframes, “U” denotes uplink subframes, and “S” denotes flexible subframes, seven different uplink-downlink configurations are provided. 3GPP is short for third generation partnership project and TS is short for technical specification.

The size of the guard period (as defined by the number of uplink and downlink symbols in the flexible slot(s)) and hence the number of symbols for the downlink pilot time slot (DwPTS), and uplink pilot time slot (UwPTS) in the special subframe, can also be configured from a set of possible selections.

NR on the other hand provides many different uplink-downlink configurations. There could be 10 to 320 slots per radio frame (where each radio frame has a duration of 10 ms) depending on subcarrier spacing. Each slot can be configured with a slot format as shown in Table 11.1.1-1 in 3GPP TS 38.212, V16.4.0. As an alternative to this, a semi-static TDD uplink-downlink configuration may be used where the TDD configuration is provided via radio resource control (RRC) configuration using the information element (IE) denoted TDD-UL-DL-ConfigCommon as specified in 3GPP TS 38.331, V15.2.1. The number of uplink and downlink slots, as well as the guard period may be almost arbitrarily configured within the TDD periodicity. This allows for very flexible uplink-downlink configurations.

For example, existing communications networks using TDD are typically dimensioned for services that are DL heavy. A TDD pattern is seen as DL heavy when the fraction of DL TDD slots is higher than the fraction of UL TDD slots for that TDD pattern. One non-limiting example of such a service is mobile broadband (MBB). However, there could be services that are UL heavy, or at least where higher UL throughput than currently available is needed. As a non-limiting and illustrative example, many industrial applications (both massive machine-type-communications (mMTC) and critical MTC (cMTC)) are expected to be UL heavy, in terms of both performance and capacity requirements. For example, streaming of high-quality video (or lidar data or radar data) from a remotely controlled machine, or vehicle, might require higher UL throughput than the DL throughput required for control of the machine, or vehicle. For mMTC applications, sensors might be configured to continuously transmit updates in UL whilst DL transmission occurs only when the operation of the sensor needs adjustment. The UL traffic from a single sensor may be reasonably limited in transferred data size, but might occur with very frequent (periodic or aperiodic) transmissions. There are also examples of sensor platforms, aggregating the information from multiple sensors, yielding large amounts of data to be transmitted in UL from the sensor platforms. It can therefore be desirable to use an UL-heavy TDD pattern in industrial networks or non-public networks (NPNs). Using a UL heavy TDD pattern in a part of a communications network might be cumbersome if the same, or adjacent, frequency band is used for the UL heavy TDD pattern as for a neighboring part of the communications (or even another communications network) where a DL heavy TDD pattern is used, because of possible cross-link interference. Neighboring access network nodes serving different cells should therefore generally be time synchronized with slot border starting at the same time and have the same uplink-downlink configuration in order to avoid severe interference between uplink and downlink transmissions. This could make it difficult in the network to dynamically switch between different uplink-downlink configurations in order to adapt to current uplink and downlink traffic patterns and traffic distributions.

On the other hand, if neighboring access network nodes are allowed to have different uplink-downlink configurations, there maybe cases of severe interference. For example, a first user equipment (UE) on a cell edge of a first access network node receiving downlink transmission from the first access network node might be significantly interfered by a nearby second UE simultaneously transmitting in uplink to a second access network node serving a neighboring cell with a different uplink- downlink configuration. Hence, there is still a need for mechanisms that enable more flexible selection of TDD patterns in a communications network.

SUMMARY

An object of embodiments herein is to provide mechanisms that enable flexible selection of TDD patterns in a communications network, not suffering from the issues noted above or where the issues noted above at least are mitigated or reduced.

According to a first aspect there is presented a method for selecting a first TDD pattern for a first access network node. The first TDD pattern comprises first DL slots for DL communication and first UL slots for UL communication. The method comprises obtaining information of a second TDD pattern used by a second access node neighboring the first access network node and comprises second DL slots and second UL slots, each of which is composed of symbols. The method comprises obtaining information of UL/DL traffic distribution of the first access network node. The method comprises selecting the first TDD pattern so as to match the second TDD pattern in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots. How many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution. According to a second aspect there is presented a network management node for selecting a first TDD pattern for a first access network node. The first TDD pattern comprises first DL slots for DL communication and first UL slots for UL communication. The network management node comprises processing circuitry. The processing circuitry is configured to cause the network management node to obtain information of a second TDD pattern used by a second access node neighboring the first access network node and comprises second DL slots and second UL slots, each of which is composed of symbols. The processing circuitry is configured to cause the network management node to obtain information of UL/DL traffic distribution of the first access network node. The processing circuitry is configured to cause the network management node to select the first TDD pattern so as to match the second TDD pattern in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots. How many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

According to a third aspect there is presented a network management node for selecting a first TDD pattern for a first access network node. The first TDD pattern comprises first DL slots for DL communication and first UL slots for UL communication. The network management node comprises an obtain module configured to obtain information of a second TDD pattern used by a second access node neighboring the first access network node and comprises second DL slots and second UL slots, each of which is composed of symbols. The network management node comprises an obtain module configured to obtain information of UL/DL traffic distribution of the first access network node. The network management node comprises a select module configured to select the first TDD pattern so as to match the second TDD pattern in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots. How many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

According to a fourth aspect there is presented a computer program for selecting a first TDD pattern for a first access network node, the computer program comprising computer program code which, when run on a network management node 200, causes the network management node to perform a method according to the first aspect.

According to a fifth aspect there is presented a computer program product comprising a computer program according to the fourth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

Advantageously, these aspects provide flexible selection of the first TDD pattern. Advantageously, by selecting the first TDD pattern to allow frequent switching between UL and DL, the average round-trip time (RTT) latency can be reduced for the UEs served by the first access network node.

Advantageously, the first TDD pattern can be selected to be suited for short delay ultra-reliable low latency communication (URLLC) and UL heavy traffic.

Advantageously, as the first TDD pattern can be selected to be almost identical to the second TDD pattern, very little additional interference toward neighboring access network nodes where the second TDD pattern is used is caused due to the differences between the first and the second TDD pattern. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram illustrating a communications network according to embodiments presented herein; Figs. 2, 3, 5, 6, 7, and 8 schematically illustrate TDD patterns according to embodiments;

Fig. 4 is a flowchart of methods according to embodiments; Fig. 9 is a schematic diagram showing functional units of a network management node according to an embodiment;

Fig. to is a schematic diagram showing functional modules of a network management node according to an embodiment; Fig. li shows one example of a computer program product comprising computer readable storage medium according to an embodiment;

Fig. 12 is a schematic diagram illustrating a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments; and Fig. 13 is a schematic diagram illustrating host computer communicating via a radio base station with a terminal device over a partially wireless connection in accordance with some embodiments.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

The wording that a certain data item or piece of information, or the like, is obtained by a first device, entity, or the like, should be construed as that data item or piece of information being retrieved, fetched, received, or otherwise made available to the first device. For example, the data item or piece of information might either be pushed to the first device from a second device, entity, or the like, or pulled by the first device from the second device. Further, in order for the first device to obtain the data item or piece of information, the first device might be configured to perform a series of operations, possible including interaction with the second device. Such operations, or interactions, might involve a message exchange comprising any of a request message for the data item or piece of information, a response message comprising the data item or piece of information, and an acknowledge message of the data item or piece of information. The request message might be omitted if the data item or piece of information is neither explicitly nor implicitly requested by the first device.

The wording that a certain data item or piece of information, or the like, is provided by a first device, entity, or the like, to a second device, entity, or the like, should be construed as that data item or piece of information being sent or otherwise made available to the second device by the first device. For example, the data item or piece of information might either be pushed to the second device from the first device or pulled by the second device from the first device. Further, in order for the first device to provide the data item or piece of information to the second device, the first device and the second device might be configured to perform a series of operations in order to interact with each other. Such operations, or interaction, might involve a message exchange comprising any of a request message for the data item or piece of information, a response message comprising the data item or piece of information, and an acknowledge message of the data item or piece of information. The request message might be omitted if the data item or piece of information is neither explicitly nor implicitly requested by the second device.

Fig. 1 is a schematic diagram illustrating a communications network 100 where embodiments presented herein can be applied. The communications network 100 comprises cells 110a, 110b. Each cell 110a, 110b is served by a respective (radio) access network node 120a, 120b. UEs 130a, 130b operatively connected to any of the access network node 120a, 120b are thereby provided network access.

Examples of (radio) access network nodes 120a, 120b are radio base stations, base transceiver stations, Node Bs, evolved Node Bs, g NBs, access points, access nodes, radio dot nodes, and backhaul nodes. The access network nodes 120a, 120b could be placed indoors or outdoors; some access network nodes 120a, 120b could be placed indoors whilst other are placed outdoors, etc. Access network node 120a will hereinafter be denoted a first access network node 120a whereas access network nodes 120b will hereinafter be denoted second access network node(s) 120b. However, this does not imply that there is any hierarchical relation between the access network nodes 120a, 120b. Further, in some examples the first access network node 120a, but not the second access network node 120b, is part of an industrial communication network or a local network, such as a non-public network (NPN). Examples of UEs 130a, 130b are mobile stations, mobile phones, handsets, wireless local loop phones, smartphones, laptop computers, tablet computers, network equipped sensors (such as network equipped cameras, e.g. in terms of surveillance cameras or vehicle-mounted cameras), network equipped vehicles, and so-called Internet of Things devices. UEs 130b will hereinafter represent a typical UE using a DL heavy service such as a mobile broadband service whereas UEs 130a will hereinafter represent a typical UE using a UL heavy service such as an industrial network service.

In some examples the first access network nodes 120a and the second access network nodes 120b are neighbors. This might imply that there are not any other access network nodes placed physically in between the first access network node 120a and the second access network nodes 120b, or at least not any other such other access network nodes operating in the same, or adjacent frequency band as the first access network node 120a. This might further imply that the cells 110a, 110b are adjacent each other, possibly even overlapping at the cell edges. That is, a UE 130a, 130b located at the cell edge between cell 110a and cell 110b might be able to receive signals from both the first access network nodes 120a and the second access network nodes 120b above a signal threshold level.

It is assumed that TDD is used for DL and UL communication between the access network nodes 120a, 120b and the UEs 130a, 130b. In some aspects it is further assumed that DL and UL communication is performed on component carriers. At 140 is schematically illustrated that a first TDD pattern is used for communication in the cell 110a. At 150 is schematically illustrated that a second TDD pattern is used for communication in the cells 110b. The first TDD pattern 140 is preferably UL heavy (as indicated by the bold arrow from UE 130a towards access network node 120a) whereas the second TDD pattern 150 preferably is DL heavy (as indicated by the bold arrow from access network nodes 120b towards UEs 130b). One reason for using a DL heavy TDD pattern 150 is to serve UEs 130b using a mobile broadband service that is mainly DL heavy with for example video downloads. One reason for using a UL heavy TDD pattern 140 is to serve UEs 130a using an mMTC or cMTC service that is mainly UL heavy with for example sensor uploads. The latter could be the case where the UEs 130a operate in an industrial network, such as remote-controlled vehicles equipped with video cameras that produce video streams that need to be transmitted in UL to a central control room for monitoring of the remote-controlled vehicles.

The operation of at least access network node 120a, and thus at least of cell 110a, is controlled by a network management node 200. As will be further disclosed below, the network management node 200 is configured to select, and thereby control, which TDD pattern that is to be used for DL and UL communication in the cell 110a. In some examples, there is one network management node 200 per cell. Thus, in some aspects, the network management node 200 is integrated with, collocated with, or part of access network node 120a serving cell 110a with a first TDD pattern. In other examples, there is one single network management node 200 for all the cells, or at least for two or more of the cells. Thus, in some aspects, the network management node 200 is integrated with, collocated with, or part of a network-centric node controlling access network node 120a serving the cell 110a as well as at least one other access network node (such as any of access network node 120b).

As noted above there is still a need for mechanisms that enable more flexible selection of TDD patterns 140, 150 in a communications network 100. The herein disclosed embodiments are focused on providing flexible selection of the first TDD pattern 140. In some aspects, this can be regarded as defining a subset of TDD patterns to select from that limits the CLI. This implies that the flexibility is restricted for the benefit of enabling selection of TDD patterns that can be used in practical network deployments. In this respect, in many different network deployments, complete time synchronisation, or even exclusion zones, between cells 110a, 110b, and thus between access network nodes 120a, 120b, is required to avoid large guard bands for filter roll off. Unless the cell 120a (for example serving a local industrial network) is only deployed indoors and the wall loss is very high (so that the local industrial network can be assumed to be almost isolated from the outside), the first TDD pattern 140 should be UL/DL-aligned with the DL-heavy second TDD pattern 150 of the surrounding cells 110b. For the first TDD pattern 140 and the second TDD pattern 150 to be fully UL/DL-aligned, the first TDD pattern 140 needs to comprise DL slots when the second TDD pattern 150 comprises DL slots, and the first TDD pattern 140 needs to comprise UL slots when the second TDD pattern 150 comprises UL slots.

Fig. 2 shows an example where the first TDD pattern 140 is fully UL/DL-aligned with the second TDD pattern 150, although the first TDD pattern 140 is a TDD pattern used for NR and the second TDD pattern 150 is a TDD pattern used for LTE, and hence the sub-carrier spacing (SCS) is different (30 kHz compared to 15 kHz) and the total number of slots is different (10 slots compared to 5 slots).

In general, higher SCS implies that it is possible to switch between UL and DL more often than for a lower SCS, which in turn reduces the RTT latency. For the example in Fig. 2, the resulting latency is identical for the two TDD patterns despite the SCS is different. The capability of using higher SCS is therefore of no use if the TDD patterns need to be fully UL/DL-aligned. As noted above, in the illustrative examples of Fig. 1, the UEs 130a served in the cell 110a are assumed to be UL heavy and hence would benefit from a TDD pattern that offers more UL slots than the example of Fig. 2. One example of a UL heavy first TDD pattern 140 is illustrated in Fig. 3. In addition, the UEs 130a might benefit from a TDD pattern that gives low average RTT latency.

However, it could be cumbersome to combine the first TDD pattern 140 illustrated in Fig. 3 with the second TDD pattern 150 illustrated in Fig. 2. This since the TDD patterns will no longer be UL/DL-aligned, which might cause cross-link interference (CLI), both in co-channel and adjacent channel and especially for frequencies in mid band. Hence, the flexibility offered by the first TDD pattern 140 in Fig. 3 might be difficult to utilize. A consequence of this might be that the first TDD pattern 140 illustrated in Fig. 2 must be used in the cell 110a. As such, this TDD pattern is optimized for DL heavy traffic.

The embodiments disclosed herein therefore relate to mechanisms for selecting a first TDD pattern 140 for a first access network node 120a. In order to obtain such mechanisms there is provided a network management node 200, a method performed by the network management node 200, a computer program product comprising code, for example in the form of a computer program, that when run on a network management node 200, causes the network management node 200 to perform the method. By using flexible slot formats (such as those in NR), the TDD pattern can be selected almost arbitrarily on symbol level. This flexibility can be used to set up the first TDD pattern 140 (e.g. to suit a local industrial network) that is very similar to a DL heavy TDD pattern typically used by the surrounding macro network, but with symbols for UL available within otherwise long periods of DL-only symbols. In this respect, expected shorter delay spread within many confined industry non-public network deployments enables use of higher SCS and shorter symbols, facilitating short UL symbols, in turn increasing the TDD pattern flexibility.

Hereinafter will be disclosed different examples of such first TDD patterns 140 that, for example, can be used in deployments requiring low latency or increased uplink capacity. Generally, the first TDD patterns 140 are selected so that partial UL/DL- alignment (in terms of UL and DL symbols) with the second TDD pattern 140 is achieved.

Fig. 4 is a flowchart illustrating embodiments of methods for selecting a first TDD pattern 140 for a first access network node 120a. The first TDD pattern 140 comprises first DL slots for DL communication and first UL slots for UL communication. The methods might be performed by the network management node 200. The methods are advantageously provided as computer programs 1120.

At least some of the herein disclosed embodiments are based on that the first TDD pattern 140, as used by the first access network node 120a, is selected to be similar to the second TDD pattern 150 used by a neighbouring second access network node 120b, but with symbol(s) for UL available within long periods of DL-only slots.

S102: The network management node 200 obtains information of a second TDD pattern 150 used by a second access node 120b. The second access node 120b neighbors the first access network node 120a. The second TDD pattern 150 comprises second DL slots and second UL slots, each of which being composed of symbols.

S104: The network management node 200 obtains information of UL/DL traffic distribution of the first access network node 120a.

S110: The network management node 200 selects the first TDD pattern 140 so as to match the second TDD pattern 150 in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of the at least one of the second DL slots. How many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

Embodiments relating to further details of selecting a first TDD pattern 140 for a first access network node 120a as performed by the network management node 200 will now be disclosed.

In S102 the information of the second TDD pattern 150 used by the second access node 120b might be obtained by the network management node 200 directly from the second access network node 120b, possibly via a further entity, node, or device. Alternatively, the information of the second TDD pattern 150 might be obtained by the network management node 200 from a data repository, or other type of storage medium, where such information is collected and stored. The information of the second TDD pattern 150 might be the second TDD pattern 150 itself. Alternatively, the information of the second TDD pattern 150 constitutes information that unambiguously identifies the second TDD pattern 150.

In S104 the information of UL/DL traffic distribution of the first access network node 120a might be obtained by the network management node 200 directly from the first access network node 120a, possibly via a further entity, node, or device. Alternatively, the information of UL/DL traffic distribution of the first access network node 120a might be obtained by the network management node 200 from a data repository, or other type of storage medium, where such information is collected and stored. In turn, the information of UL/DL traffic distribution might be obtained by studying the amount of UL and DL traffic of the first access network node 120a. Such information might be available from a scheduler of the UL and DL traffic of the first access network node 120a.

The first TDD pattern 140 and the second TDD pattern 150 might be used for communication in any of: adjacent frequency bands, adjacent (or at least very close) frequency allocations within same frequency band, or at least partly overlapping frequency bands. The second TDD pattern 150 might be specified by a UL-DL configuration used by a second access node 120b. This UL-DL configuration might be selected from one of the UL-DL configurations listed in table 1.

The first TDD pattern 140 might be time synchronized with the second TDD pattern 150 so that a slot of the first TDD pattern 140 starts simultaneously with a slot in the second TDD pattern 150.

Further aspects of how the first TDD pattern 140 might be selected will now be disclosed.

In some aspects, the first TDD pattern 140 is selected also based on data traffic delay requirements and/or quality of service (QoS) requirements. Therefore, these parameters might be obtained by the network management node 200. Hence, in some embodiments, the method further comprises:

S106: The network management node 200 obtains information of data traffic delay requirement for the user equipment 130a served by the first access network node 120a and/or QoS requirement for the user equipment 130a served by the first access network node 120a.

In S106 the information of data traffic delay requirement might be obtained by the network management node 200 directly from the first access network node 120a, possibly via a further entity, node, or device. Alternatively, the information of data traffic delay requirement might be obtained by the network management node 200 from a data repository, or other type of storage medium, where such information is collected and stored. In turn, the information of data traffic delay requirement might be obtained by the first access network node 120a from the user equipment 130a. In this respect, the information of data traffic delay requirement might either be pushed by the user equipment 130a to the first access network node 120a or be pulled by the first access network node 120a from the user equipment 130a. Yet alternatively, such information is provided by an external entity to the data repository. This external entity might be controlled by the network operator of the first access network node 120a, where the network operator has knowledge of the type of user equipment 130a to be served and also of the data traffic delay requirement of the type of user equipment 130a. Then, how far spaced in time two UL symbol blocks are to be might be determined as a function of the information of data traffic delay requirement and/or QoS requirement. The higher the data traffic delay requirement and/or QoS requirement, the shorter two UL symbol blocks should be separated in time. In some aspects, the first TDD pattern 140 is selected also based on a tolerable CLI level. That is, how many symbols the UL symbol block is composed of might further be determined as a function of a CLI threshold value.

Further, the slots of the first TDD pattern 140 might be transmitted on subcarriers. These subcarriers might have a subcarrier spacing (SCS) determined as a function of the information of data traffic delay requirements. Radio delay spread might be obtained and the SCS might be selected based on a combination of radio delay spread and delay requirements. The radio delay spread generally represents a measure of the multipath profile of a radio propagation channel (in the present case between the first access network node 120a and its served user equipment 130a). It is generally defined as the difference between the time of arrival of the earliest component (e.g., the line- of-sight wave, if there exists) and the time of arrival of the latest multipath component, Particularly, in some embodiments, the method further comprises:

S108: The network management node 200 obtains information of radio delay spread for the first access network node 120a. In S108 the information of radio delay spread for the first access network node 120a might be obtained by the network management node 200 directly from the first access network node 120a, possibly via a further entity, node, or device. Alternatively, the information of radio delay spread of the first access network node 120a might be obtained by the network management node 200 from a data repository, or other type of storage medium, where such information is collected and stored. In turn, the first access network node 120a might obtain an estimate of the radio delay spread from measurements on signals received from the user equipment 130a, where such measurements capture the difference between the time of arrival of the earliest component (e.g., the line-of-sight wave, if there exists) and the time of arrival of the latest multipath component. Then, the subcarrier spacing is further determined as a function of the radio delay spread.

In some aspects, UL transmissions suffering from surrounding DL interference are identified and transmitted with a more robust transmission format. Particularly, the UL symbol block might be assigned lower coding rate and/or higher transmission power than symbols of first UL slots that do not overlap in time with any of the second DL slots. A lower modulation and coding scheme (MCS) than what would otherwise have been selected can be used for the UL symbol block. This can for example be implemented by subtracting a margin from the estimated SINR before calculating what MCS to use, based on the estimated signal to interference plus noise ratio (SINR).

As disclosed above, the first TDD pattern 140, as used by the first access network node 120a, is selected to be similar to the second TDD pattern 150. The difference between the first TDD pattern 140 and the second TDD pattern 150 is defined by the UL symbol block. Particularly, the first TDD pattern 140 might be identical to the second TDD pattern 150 except for the UL symbol block in the first TDD pattern 140 that overlaps in time with the at least one of the second DL slots in the second TDD pattern 150. Examples of how many symbols there could be in the UL symbol block will be disclosed below. In other words, except for the UL symbol block in the first TDD pattern 140, the first TDD pattern 140 might match the second TDD pattern 150 such that the first TDD pattern 140 is composed of first DL slots when the second TDD pattern 150 is composed of second DL slots and the first TDD pattern 140 is composed of first UL slots when the second TDD pattern 150 is composed of second UL slots. Aspects of how many symbols there could be in the UL symbol block will now be disclosed. In some examples, the UL symbol block is composed of a single symbol. This is the case for the first TDD pattern 140 illustrated in Fig. 7(a) which will be described in more detail below. In some examples, the UL symbol block is composed of less than all symbols in a slot. This is the case for the first TDD pattern 140 illustrated in Fig. 7(b) which will be described in more detail below. In some examples, the UL symbol block is composed of all symbols in a slot. It is here noted that also combinations of the above are possible. That is, the UL symbol block might be composed of all symbols in a slot and one or more adjacent symbols in an adjacent slot. This is the case for the first TDD pattern 140 illustrated in Fig. 7(c) which will be described in more detail below.

Fig. 5 shows a first TDD pattern 140 for 60 kHz SCS that is fully time-synchronized and almost UL/DL-aligned with a second TDD pattern 150 (corresponding to uplink- downlink configuration 2 in Table 1) with 15 kHz SCS. The TDD patterns are UL/DL- aligned, except for additional UL symbols introduced in the first TDD pattern 140 to break up long periods of only DL transmissions. By introducing only as little as one UL symbol within the DL period of the second TDD pattern 150, the average latency can be significantly reduced. In this respect, although the one single UL symbol is added at the end of the slot, one (or more) UL symbol(s) could be added anywhere within the slot. For example, using the second TDD pattern 150, if the UE 130a already at the start of the 5 ms period shown in Fig. 5 has UL data to transmit, it is not possible for the UE 130a to transmit UL data until in the first UL symbol. This means a delay of almost two slots (i.e., around 2 ms). But with the proposed first TDD pattern 140, the delay is only around 1 ms. Even if the UL period is only one symbol, some payload data as well as buffer status reports, HARQ ACK/NACKs, etc., can still be transmitted. For example, on a 90 MHz wide carrier there are 150060 kHz sub carriers. With 256 QAM (8 bits communicated in every symbol) and a code rate of 0.8 this yields 9600 information bits available per every symbol. The single UL symbol might suffer from DL interference caused by the second TDD pattern 150 and hence a more robust coding scheme (than for the other symbols in the first TDD pattern 140) can be applied. With BPSK and a code rate of 0.5, which is a very robust signal, there are still 750 information bits available per every symbol. This should be sufficient for e.g. an HARQ ACK/NACK, shortening the HARQ retransmission round-trip time and improve URLLC service. The average UL latency can be further reduced if even more DL slots are exchanged to non-aligned slots (i.e., slots that are not UL/DL-aligned) with one or more UL symbols. For example, in Fig. 5, the DL slot of the second TDD pattern with a SCS 15 kHz corresponds to four slots in the first TDD pattern and one of them (the last one in Fig. 5) contains at least one UL symbol.

Fig. 6 shows a first TDD pattern 140 for 60 kHz SCS that is fully time-synchronized but less UL/DL-aligned with a second TDD pattern 150 (corresponding to uplink- downlink configuration 2 in Table 1) with 15 kHz SCS than in Fig. 5. In the example of the first TDD pattern 140 of Fig. 6, a larger number of consecutive UL symbols are added into otherwise long DL periods compared to in Fig. 5. By introducing more UL symbols, the total UL capacity of the cell 110a is increased in addition to reducing the average UL latency. How many non-aligned UL symbols (i.e., symbols designated for UL in the first TDD pattern 140 but designated for DL in the second TDD pattern 150) to use might depend on the UL/DL traffic distribution characteristics whilst the frequency of occurrence of the non-aligned UL symbols (i.e., how to time-wise distribute the non-aligned UL symbols) might depend on the required UL latency.

As the number of non-aligned UL symbols introduced in the first TDD pattern 140 impacts both the amount of interference towards the cell 110b and the uplink capacity, there maybe a trade-off between additional interference and uplink capacity. In this respect, in Fig. 7 is at (a), (b), and (c) shown, for different NR slot formats, how large fraction of the symbols in the neighboring cells 110b using a second TDD pattern 150 that is impacted by CLI due to the additional non-aligned UL symbols. It is hence assumed that for the time period shown in Fig. 7, the second TDD pattern 150 only contains DL symbols. If only 1 UL symbol is added to every fourth slot, as shown in Fig. 7(a) and where the first TDD pattern 140 is used in a cell 110a having four times higher SCS than the cells 110b where the second TDD pattern 150 is used, this means that the cells 110b will be affected by CLI during less than 2% of the transmission time. Further, for the same SCS set-up as in Fig. 7(a) but with 7 UL symbols, as shown in Fig. 7(b), the cells 110b will be affected by CLI during about 12% of the transmission time. Still further, for the same SCS set-up as in Fig. 7(a) but with 15 UL symbols, as shown in Fig. 7(c), the cells 110b will be affected by CLI during about 27% of the transmission time. In further detail, taking the example shown in Fig. 7(a) as an example, a first TDD pattern 140 based on this example will affect cells 120b using the second TDD pattern 150 only in 1 out of 14 symbols, and only in one out of four slots. As the symbol duration for 60 kHz SCS is shorter in time than the symbol duration of the symbol it interferes (with 15 kHz SCS), the interference will only impact the DL symbol during 1/4 of the time. As this generates low additional interference noise, it is most likely still possible to decode the downlink transmission in the cells 110b. When more symbols are interfered, it becomes more probable that DL transmissions in the cells 110b using the second TDD pattern 150 cannot be successfully decoded after the first transmission attempt. However, in case the UEs 130b served in the cells 110b where the second TDD pattern 150 is used typically carries MBB traffic with very relaxed latency bounds, any decoding failures can easily be handled through HARQ retransmissions.

In some aspects, a non-aligned slot is in the first TDD pattern 140 introduced also within the longer period of UL transmission. By introducing a DL symbol in the first TDD pattern 140 within the longer period of UL transmission in the second TDD pattern 150, the average latency is further reduced for UEs 130a in the cell 110a where the first TDD pattern 140 is used. Hence, in some embodiments, at least one of the first DL slots in a DL symbol block is selected to overlap in time with at least one of the second UL slots but to span less than all symbols of the at least one of the second UL slots. This could be advantageous in case retransmissions are needed, as an HARQ ACK or NACK can be transmitted in the thus introduced DL symbol and a retransmission can be scheduled quickly in case of a decoding failure. An example of this is shown in Fig. 8 where in the first TDD pattern 140, one non-aligned UL symbol is introduced in every second DL slot and one non-aligned DL symbol is introduced in one of the UL slots.

The thus far disclosed embodiments, aspects, and examples are equally applicable for outdoor and indoor network deployments, e.g. for local networks along roads or railways supporting foreseen future uplink heavy video or lidar upload to clouds from ordinary cars, trucks and trains. To reduce the CLI introduced by the slots/symbols of the local road-optimized TDD pattern (as defined by the first TDD pattern 140) that have another distribution in terms of UL/DL symbols in the slots than the slots of a surrounding macro network (utilizing the second TDD pattern 150), the isolation between the road-near network (or road-near part of a macro network) and the surrounding macro network may have to be improved in addition to applying the thus far disclosed embodiments, aspects, and examples. Increased isolation between a macro network and a local network outdoors can for example be achieved through beamforming or through the use of an exclusion zone where the carriers used by the local network are not used by the closest surrounding macro network access network nodes 120b.

Fig. 9 schematically illustrates, in terms of a number of functional units, the components of a network management node 200 according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1110 (as in Fig. 11), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry 210 is configured to cause the network management node 200 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the network management node 200 to perform the set of operations. The set of operations may be provided as a set of executable instructions.

Thus the processing circuitry 210 is thereby arranged to execute methods as herein disclosed. The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The network management node 200 may further comprise a communications interface 220 at least configured for communications with the access network nodes 120a, 120b. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components. The processing circuitry 210 controls the general operation of the network management node 200 e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the network management node 200 are omitted in order not to obscure the concepts presented herein.

Fig. 10 schematically illustrates, in terms of a number of functional modules, the components of a network management node 200 according to an embodiment. The network management node 200 of Fig. 10 comprises a number of functional modules; an obtain module 210a configured to perform step S102, an obtain module 210b module configured to perform step S104, and a select module 2ioe configured to perform step Sno. The network management node 200 of Fig. 10 may further comprise a number of optional functional modules, such as any of an obtain module 210c configured to perform step S106, and an obtain module 2iod configured to perform step S108. In general terms, each functional module 210a: 2ioe may in one embodiment be implemented only in hardware and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium 230 which when run on the processing circuitry makes the network management node 200 perform the corresponding steps mentioned above in conjunction with Fig 10. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used. Preferably, one or more or all functional modules 2ioa:2ioe may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and/or the storage medium 230. The processing circuitry 210 may thus be configured to from the storage medium 230 fetch instructions as provided by a functional module 2ioa:2ioe and to execute these instructions, thereby performing any steps as disclosed herein.

The network management node 200 may be provided as a standalone device or as a part of at least one further device. For example, the network management node 200 may be provided in a node of the radio access network or in a node of the core network. Alternatively, functionality of the network management node 200 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the radio access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time. Thus, a first portion of the instructions performed by the network management node 200 may be executed in a first device, and a second portion of the of the instructions performed by the network management node 200 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the network management node 200 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a network management node 200 residing in a cloud computational environment. Therefore, although a single processing circuitry 210 is illustrated in Fig. 9 the processing circuitry 210 may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 2ioa:2ioe of Fig. 10 and the computer program 1120 of Fig. 11.

Fig. 11 shows one example of a computer program product 1110 comprising computer readable storage medium 1130. On this computer readable storage medium 1130, a computer program 1120 can be stored, which computer program 1120 can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 1120 and/or computer program product 1110 may thus provide means for performing any steps as herein disclosed.

In the example of Fig. 11, the computer program product 1110 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 1110 could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1120 is here schematically shown as a track on the depicted optical disk, the computer program 1120 can be stored in any way which is suitable for the computer program product 1110. Fig. 12 is a schematic diagram illustrating a telecommunication network connected via an intermediate network 420 to a host computer 430 in accordance with some embodiments. In accordance with an embodiment, a communication system includes telecommunication network 410, such as a 3GPP-type cellular network, which comprises access network 411, and core network 414. Access network 411 comprises a plurality of radio access network nodes 412a, 412b, 412c, such as NBs, eNBs, gNBs (each corresponding to one of the access network nodes 120a, 120b of Fig. 1) or other types of wireless access points, each defining a corresponding coverage area, or cell, 413a, 413b, 413c. Each radio access network nodes 412a, 412b, 412c is connectable to core network 414 over a wired or wireless connection 415. A first UE 491 located in coverage area 413c is configured to wirelessly connect to, or be paged by, the corresponding network node 412c. A second UE 492 in coverage area 413a is wirelessly connectable to the corresponding network node 412a. While a plurality of UE 491, 492 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 terminal device is connecting to the corresponding network node 412. The UEs 491, 492 correspond to the UEs 130a, 130b of Fig. 1. Telecommunication network 410 is itself connected to host computer 430, 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. Host computer 430 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. Connections 421 and 422 between telecommunication network 410 and host computer 430 may extend directly from core network 414 to host computer 430 or may go via an optional intermediate network 420. Intermediate network 420 may be one of, or a combination of more than one of, a public, private or hosted network; intermediate network 420, if any, may be a backbone network or the Internet; in particular, intermediate network 420 may comprise two or more sub-networks (not shown).

The communication system of Fig. 12 as a whole enables connectivity between the connected UEs 491, 492 and host computer 430. The connectivity may be described as an over-the-top (OTT) connection 450. Host computer 430 and the connected UEs 491, 492 are configured to communicate data and/or signalling via OTT connection

450, using access network 411, core network 414, any intermediate network 420 and possible further infrastructure (not shown) as intermediaries. OTT connection 450 may be transparent in the sense that the participating communication devices through which OTT connection 450 passes are unaware of routing of uplink and downlink communications. For example, network node 412 may not or need not be informed about the past routing of an incoming downlink communication with data originating from host computer 430 to be forwarded (e.g., handed over) to a connected UE 491. Similarly, network node 412 need not be aware of the future routing of an outgoing uplink communication originating from the UE 491 towards the host computer 430.

Fig. 13 is a schematic diagram illustrating host computer communicating via a radio access network node with a UE over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with an embodiment, of the UE, radio access network node and host computer discussed in the preceding paragraphs will now be described with reference to Fig. 13. In communication system 500, host computer 510 comprises hardware 515 including communication interface 516 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of communication system 500. Host computer 510 further comprises processing circuitry 518, which may have storage and/or processing capabilities. In particular, processing circuitry 518 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. Host computer 510 further comprises software 511, which is stored in or accessible by host computer 510 and executable by processing circuitry 518. Software 511 includes host application 512. Host application 512 may be operable to provide a service to a remote user, such as UE 530 connecting via OTT connection 550 terminating at UE 530 and host computer 510. The UE 530 corresponds to the UEs 130a, 130b of Fig. 1. In providing the service to the remote user, host application 512 may provide user data which is transmitted using OTT connection 550.

Communication system 500 further includes radio access network node 520 provided in a telecommunication system and comprising hardware 525 enabling it to communicate with host computer 510 and with UE 530. The radio access network node 520 corresponds to the access network nodes 120a, 120b of Fig. 1. Hardware 525 may include communication interface 526 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of communication system 500, as well as radio interface 527 for setting up and maintaining at least wireless connection 570 with UE 530 located in a coverage area (not shown in Fig. 13) served by radio access network node 520. Communication interface 526 may be configured to facilitate connection 560 to host computer 510. Connection 560 may be direct or it may pass through a core network (not shown in Fig. 13) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, hardware 525 of radio access network node 520 further includes processing circuitry 528, 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. Radio access network node 520 further has software 521 stored internally or accessible via an external connection.

Communication system 500 further includes UE 530 already referred to. Its hardware 535 may include radio interface 537 configured to set up and maintain wireless connection 570 with a radio access network node serving a coverage area in which UE 530 is currently located. Hardware 535 of UE 530 further includes processing circuitry 538, 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. UE 530 further comprises software 531, which is stored in or accessible by UE 530 and executable by processing circuitry 538. Software 531 includes client application 532. Client application 532 may be operable to provide a service to a human or non-human user via UE 530, with the support of host computer 510. In host computer 510, an executing host application 512 may communicate with the executing client application 532 via OTT connection 550 terminating at UE 530 and host computer 510. In providing the service to the user, client application 532 may receive request data from host application 512 and provide user data in response to the request data. OTT connection 550 may transfer both the request data and the user data. Client application 532 may interact with the user to generate the user data that it provides. It is noted that host computer 510, radio access network node 520 and UE 530 illustrated in Fig. 13 may be similar or identical to host computer 430, one of network nodes 412a, 412b, 412c and one of UEs 491, 492 of Fig. 12, respectively. This is to say, the inner workings of these entities may be as shown in Fig. 13 and independently, the surrounding network topology may be that of Fig. 12. In Fig. 13, OTT connection 550 has been drawn abstractly to illustrate the communication between host computer 510 and UE 530 via network node 520, 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 UE 530 or from the service provider operating host computer 510, or both. While OTT connection 550 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).

Wireless connection 570 between UE 530 and radio access network node 520 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 UE 530 using OTT connection 550, in which wireless connection 570 forms the last segment. More precisely, the teachings of these embodiments may reduce interference, due to improved classification ability of airborne UEs which can generate significant interference.

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 OTT connection 550 between host computer 510 and UE 530, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring OTT connection 550 may be implemented in software 511 and hardware 515 of host computer 510 or in software 531 and hardware 535 of UE 530, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which OTT connection 550 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 511, 531 may compute or estimate the monitored quantities. The reconfiguring of OTT connection 550 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect network node 520, and it may be unknown or imperceptible to radio access network node 520. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signalling facilitating host computer’s 510 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that software 511 and 531 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using OTT connection 550 while it monitors propagation times, errors etc. The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

1. A method for selecting a first time-division duplex, TDD, pattern (140) for a first access network node (120a), wherein the first TDD pattern (140) comprises first downlink, DL, slots for DL communication and first uplink, UL, slots for UL communication, the method comprising: obtaining (S102) information of a second TDD pattern (150) used by a second access node (120b) neighboring the first access network node (120a) and comprising second DL slots and second UL slots, each of which being composed of symbols; obtaining (S104) information of UL/DL traffic distribution of the first access network node (120a); and selecting (S110) the first TDD pattern (140) so as to match the second TDD pattern (150) in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots, wherein how many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

2. The method according to claim 1, wherein the method further comprises: obtaining (S106) information of data traffic delay requirement for user equipment (130a) served by the first access network node (120a) and/or QoS requirement for the user equipment (130a) served by the first access network node (120a), and wherein how far spaced in time two UL symbol block are is determined as a function of the information of data traffic delay requirement and/or QoS requirement.

3. The method according to claim 1 or 2, wherein how many symbols the UL symbol block is composed of further is determined as a function of a CLI threshold value.

4. The method according to any preceding claim, wherein the slots of the first TDD pattern (140) are to be transmitted on subcarriers, and wherein the subcarriers have a subcarrier spacing determined as a function of the information of data traffic delay requirements.

5. The method according to claim 4, wherein the method further comprises: obtaining (S108) information of radio delay spread for the first access network node (120a), and wherein the subcarrier spacing further is determined as a function of the radio delay spread.

6. The method according to any preceding claim, wherein the first TDD pattern (140) is identical to the second TDD pattern (150) except for the UL symbol block in the first TDD pattern (140) that overlaps in time with said at least one of the second DL slots in the second TDD pattern (150).

7. The method according any preceding claim, wherein the first TDD pattern (140) matches the second TDD pattern (150) such that the first TDD pattern (140) is composed of first DL slots when the second TDD pattern (150) is composed of second DL slots and the first TDD pattern (140) is composed of first UL slots when the second TDD pattern (150) is composed of second UL slots.

8. The method according to any preceding claim, wherein the UL symbol block is composed of a single symbol.

9. The method according to any preceding claim, wherein UL symbol block is composed of less than all symbols in a slot.

10. The method according to any preceding claim, wherein the UL symbol block is composed of all symbols in a slot.

11. The method according to any preceding claim, wherein the UL symbol block is assigned lower coding rate and/or higher transmission power than symbols of first UL slots that do not overlap in time with any of the second DL slots.

12. The method according to any preceding claim, wherein the the first TDD pattern (140) is time synchronized with the second TDD pattern (150) so that a slot of the first TDD pattern (140) starts simultaneously with a slot in the second TDD pattern (150).

13. The method according to any preceding claim, wherein in at least one of the first DL slots in a DL symbol block is selected to overlap in time with at least one of the second UL slots but to span less than all symbols of the at least one of the second UL slots, and wherein how many symbols the DL symbol block is composed of is determined as a function of the information of data traffic delay requirements.

14. The method according to any preceding claim, wherein the first TDD pattern (140) and the second TDD pattern (150) are to be used for communication in any of: adjacent frequency bands, adjacent frequency allocations within same frequency band, or at least partly overlapping frequency bands.

15. The method according to any preceding claim, wherein the first access network node (120a), but not the second access network node (120b), is part of an industrial communication network, a non-public network, or a local network.

16. The method according to any preceding claim, wherein the second TDD pattern (150) is specified by a UL-DL configuration used by a second access node (120b).

17. The method according to any preceding claim, wherein the method is performed by a network management node (200) in the first access network node (120a) or operatively connected to the first access network node (120a) and the second access network node (120b).

18. A network management node (200) for selecting a first time-division duplex, TDD, pattern (140) for a first access network node (120a), wherein the first TDD pattern (140) comprises first downlink, DL, slots for DL communication and first uplink, UL, slots for UL communication, the network management node (200) comprising processing circuitry (210), the processing circuitry being configured to cause the network management node (200) to: obtain information of a second TDD pattern (150) used by a second access node (120b) neighboring the first access network node (120a) and comprising second DL slots and second UL slots, each of which being composed of symbols; obtain information of UL/DL traffic distribution of the first access network node (120a); and select the first TDD pattern (140) so as to match the second TDD pattern (150) in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots, wherein how many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

19. A network management node (200) for selecting a first time-division duplex, TDD, pattern (140) for a first access network node (120a), wherein the first TDD pattern (140) comprises first downlink, DL, slots for DL communication and first uplink, UL, slots for UL communication, the network management node (200) comprising: an obtain module (210a) configured to obtain information of a second TDD pattern (150) used by a second access node (120b) neighboring the first access network node (120a) and comprising second DL slots and second UL slots, each of which being composed of symbols; an obtain module (210b) configured to obtain information of UL/DL traffic distribution of by the first access network node (120a); and a select module (2ioe) configured to select the first TDD pattern (140) so as to match the second TDD pattern (150) in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots, wherein how many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

20. The network management node (200) according to claim 18 or 19, further being configured to perform the method according to any of claims 2 to 19.

21. A computer program (1120) for selecting a first time-division duplex, TDD, pattern (140) for a first access network node (120a), wherein the first TDD pattern (140) comprises first downlink, DL, slots for DL communication and first uplink, UL, slots for UL communication, the computer program comprising computer code which, when run on processing circuitry (210) of a network management node (200), causes the network management node (200) to: obtain (S102) information of a second TDD pattern (150) used by a second access node (120b) neighboring the first access network node (120a) and comprising second DL slots and second UL slots, each of which being composed of symbols; obtain (S104) information of UL/DL traffic distribution of the first access network node (120a); and select (S110) the first TDD pattern (140) so as to match the second TDD pattern (150) in terms of DL and UL, except that in at least one of the first UL slots, a UL symbol block, composed of at least one UL symbol, overlaps in time with at least one of the second DL slots but spans less than all symbols of said at least one of the second DL slots, wherein how many symbols the UL symbol block is composed of is determined as a function of the information of UL/DL traffic distribution.

22. A computer program product (1110) comprising a computer program (1120) according to claim 21, and a computer readable storage medium (1130) on which the computer program is stored.