WO2023063858A1

WO2023063858A1 - A node and method therein for enabling communication link establishment towards wireless devices of a wireless communications network

Info

Publication number: WO2023063858A1
Application number: PCT/SE2021/051017
Authority: WO
Inventors: Muris Sarajlic; Robert Baldemair; Sina MALEKI; Joao VIEIRA
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2023-04-20

Abstract

A first node (110) of a wireless communications network (100) for enabling communication link establishment towards wireless devices (121, 122, 123) of the wireless communications network (100) is presented. The first node (110) determines a subset (B) of beamforming directions (4, 5) from a set (A) of beamforming directions (1-12). The first node (110) also performs discovery transmissions (SB) in each of the beamforming directions of the set (A) based on a first time interval (t₁). Further, the first node (110) performs discovery transmissions (PB) in each of the beamforming directions of the determined subset (B) based on a second time interval (t₂). Here, the second timing interval (t2) is shorter than the first timing interval (t₁). A method performed by the first node (110), a computer program product and a carrier are also provided.

Description

A NODE AND METHOD THEREIN FOR ENABLING COMMUNICATION LINK

ESTABLISHMENT TOWARDS WIRELESS DEVICES OF A WIRELESS

COMMUNICATIONS NETWORK

TECHNICAL FIELD

Embodiments herein relate to establishment of communication links in a wireless communications network. In particular, embodiments herein relate to a node and method therein for enabling communication link establishment towards wireless devices of a wireless communications network. Also, the embodiments herein also relate to a computer program product and a carrier.

BACKGROUND

In wireless communications networks, a number of different technologies for enabling next generation of wireless communications networks is being implemented. Naturally, these next generation wireless communications networks, sometimes referred to as 6G, are based upon and evolved from existing telecom technologies, such as, New Radio (NR), Long Term Evolution (LTE), etc.

A wireless communications network conventionally comprises different nodes. For example, network nodes, such as, eNB/gNBs, radio base stations, wireless access points, etc., provide radio coverage over at least one respective geographical area forming a cell. This may in some cases jointly be referred to as a Radio Access Network, RAN or WLAN. Here, it should be noted that the definition of a “cell” may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. The wireless communications network may further comprise user nodes, also commonly referred to as wireless device, User Equipments, UEs, mobile stations, and/or wireless terminals, that are served in the cells by the respective network node and communicating via its serving network node in the RAN. Commonly, the wireless devices transmit data over an air or radio interface to the network nodes in uplink, UL, transmissions and the network nodes transmit data over an air or radio interface to the wireless devices in downlink, DL, transmissions.

Some wireless communications networks are capable of operation at frequencies in the so-called millimetre-waves (mmWave) range, such as, for example, NR and IEEE 802.11ad. These currently rely on spatial filtering, also known as beamforming, for successful transmission and reception of signalling related to initial access procedures. Beamforming in these wireless communications networks is advantageous since it improves the transmission link budget, i.e. coverage, needed for initial access. Here, it should be noted that proper coverage becomes more challenging to maintain at high frequencies due to path-loss increasing with the carrier frequency; this, assuming that the physical antenna aperture scales down with increasing the carrier frequency.

For wireless devices that have not yet established a connection in the wireless communications network, the communication link towards a network node in the wireless communications network is commonly established as follows. Initially, the network node and/or wireless device will perform an exhaustive blind search of the entire angular space using a set of predetermined spatial filters, also commonly referred to as a codebook. Simultaneously with this blind search, one of the network node and/or wireless device will perform transmissions of predefined reference signals, while the other network node and/or wireless device will perform channel quality measurements based on those reference signals. More specifically, each transmission of a predefined reference signal will be associated with the use of one predefined spatial filter covering a subset of the angular space, i.e. a beamforming direction. For example, in the 3GPP Rel-15 standard known as NR, the transmitting node may be the network node, e.g. a gNB, and receiving or measuring node is the wireless device, e.g. a UE. By operating in this way, both the network node and wireless device will be able to determine a set of spatial filters that may successfully support further communication, i.e. enable initial access to the wireless communications network, or alternatively declare failure to establish a connection in case of excessively adverse propagation conditions.

However, searching the entire angular space in a blind manner to find appropriate transmission directions as described above is not particularly efficient. For example, in wireless communications networks where the directions towards wireless devices and their expected received signal quality are not a priori known, e.g. there is no information regarding whether the wireless devices are close or distant from the network node, it is preferred that the transmitting node transmits with high Effective Isotropic Radiated Power, EIRP, in order to satisfy the worst-case propagation conditions, that is, to maximize the energy measured at the receiving nodes. One issue with this approach is that it may result in increased inter-cell interference, since such high power blind transmissions by a network node are likely to be heard in other cells. Also, transmitting with full power in the directions where no wireless devices are likely to receive the transmission is a waste of energy.

Furthermore, in wireless communications networks, the entire angular space of a cell is typically needed to be covered in order to make sure all the wireless devices will find the network. Using spatial filters with narrow beamwidth implies that a large number of such filters is needed for exhaustive scanning of the entire angular space. This together with time-sequential character of the directional search implies that the consumption of time resources needed for initial access may become high. This will result in increased signalling overhead or connection latency. Moreover, the energy consumption of a full angular search with high EIRP may contribute to an increase of total energy consumption of the wireless communications network. It will further also increase the power consumption of the wireless devices, since the wireless devices are also expected to perform an exhaustive search over a set of narrow beams whose number increases with higher frequency range. Overall, there are significant drawbacks of employing exhaustive blind beam scanning techniques during link establishment, such as, power and transmission resource waste, inter-cell interference, etc.

SUMMARY

It is an object of embodiments herein to improve the establishment of communication links in a wireless communications network.

According to a first aspect of embodiments herein, the object is achieved by a method performed by a first node of a wireless communications network for enabling communication link establishment towards wireless devices of the wireless communications network. The method comprises determining a subset of beamforming directions from a set of beamforming directions. The method also comprises performing discovery transmissions in each of the beamforming directions of the set based on a first time interval. Further, the method comprises performing discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval. Here, the second time interval is shorter than the first time interval.

According to a second aspect of embodiments herein, the object is achieved by a first node configured to operate in a wireless communications network and to enable establishment of communication links towards wireless devices of the wireless communications network. The first node is further configured to determine a subset of beamforming directions from a set of beamforming directions. Also, the first node is configured to perform discovery transmissions in each of the beamforming directions of the set based on a first time interval. Furthermore, the first node is configured to perform discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval, wherein the second timing interval is shorter than the first timing interval.

According to a third aspect of the embodiments herein, a computer program product is also provided configured to perform the method described above. Further, according to a fourth aspect of the embodiments herein, carriers are also provided configured to carry the computer program product configured for performing the method described above.

By dividing a set of beamforming directions into two disjoint subsets, wherein reference signal transmissions over the beamforming directions in one subset will result in a higher likelihood of successful link establishment than reference signal transmissions over at least some of the beamforming directions in the other subset, and then performing discovery transmissions more frequently on the first subset of beamforming directions, the consumption of power and transmission resources for communication link establishment during initial access may be reduced. This may be performed while ensuring a certain Quality of Service, QoS, level during initial access for a majority of user nodes in the wireless communication network, and also result in a reduction of inter-cell interference as compared to exhaustive blind searches in all beamforming directions. Hence, the establishment of communication links in a wireless communications network is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the embodiments will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the accompanying drawings, wherein:

Fig. 1 is a schematic block diagram of a wireless communications network comprising nodes according to some embodiments,

Fig. 2 is a schematic block diagram illustrating spatial filtering or beamforming,

Fig. 3 is a flowchart depicting embodiments of a method in a first node,

Fig. 4 illustrates embodiments of a signalling framework in the time domain,

Fig. 5 also illustrates embodiments of a signalling framework in the time domain,

Fig. 6 is a block diagram depicting embodiments of a first node,

Fig. 7 schematically illustrates a telecommunication network connected via an intermediate network to a host computer, Fig. 8 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection, and

Figs. 9-12 are flowcharts illustrating methods implemented in a communication system including a host computer, a base station and a user equipment.

DETAILED DESCRIPTION

The figures are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the embodiments presented herein, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts or steps.

Fig. 1 depicts a wireless communications network 100 in which embodiments herein may operate. In some embodiments, the wireless communications network 100 may be a radio communications network, such as, 6G, NR or NR+ telecommunications network. However, the wireless communications network 100 may also employ technology of any one of 3/4/5G, LTE, LTE-Advanced, WCDMA, GSM/EDGE, WiMax, UMB, GSM, or any other similar network or system. The wireless communications network 100 may also employ technology transmitting on millimetre-waves (mmW), such as, an Ultra Dense Network, UDN. In some embodiments, the wireless communications network 100 may also employ transmission supporting WiFi transmissions, e.g. the wireless communications standard IEEE 802.11 ad or similar.

The wireless communications network 100 comprises a first and a second network node 110, 111. The first and second network nodes 110, 111 may be configured to serve wireless devices in at least one cell or coverage area 115. Also, the first and second network nodes 110, 111 may correspond to any type of network node or radio network node capable of communicating with wireless devices in the wireless communications network 100, such as, a base station (BS), a radio base station, gNB, eNB, eNodeB, a Home NodeB, a Home eNodeB, a femto Base Station (BS), or a pico BS in the wireless communications network 100. Further examples of the first network node 110 are repeaters, multi-standard radio (MSR) radio nodes such as MSR BSs, network controllers, radio network controllers (RNCs), base station controllers (BSCs), relays, donor node controlling relays, base transceiver stations (BTSs), access points (APs), transmission points, transmission nodes, Remote Radio Units (RRUs), Remote Radio Heads (RRHs) or nodes in distributed antenna system (DAS). According to some embodiments, the first network node 110 may be capable of operation at frequencies in the so-called millimetre- waves (mmW) range, e.g. support mmW-transmissions according to NR and IEEE 802.11ad, while the second network node 111 may be configured to support legacy communication technologies, such as, 3/4/5G, LTE, LTE-Advanced, WCDMA, GSM/EDGE, WiMax, UMB, GSM. In other words, the first and second network node 110, 111 may support different types of wireless communications technology. The first and second network node 110, 111 may also be colocated at the same physical site or both form part of a single network node.

In the scenario shown in Fig. 1 , a first, second and third wireless device 121, 122, 123 are located within range of the first and second network node 110, 111. The first, second and third wireless device 121 , 122, 123 are configured to communicate within the wireless communications network 100 via the first and/or second network node

110, 111 over a radio link 131 , 132 served by the first and/or second network node 110,

111. In other words, the first, second and third wireless device 121 , 122, 123 may be configured to transmit data over an air or radio interface to the first and/or second network node 110, 111 in uplink, UL, transmissions, and the first and/or second network node 110, 111 may transmit data over an air or radio interface to the first, second and third wireless device 121 , 122, 123 in downlink, DL, transmissions. The first, second and third wireless device 121 , 122, 123 may be any type of wireless devices, mobile terminals or user equipments (UEs) capable of communicating with a network node and/or with another wireless device in a cellular, mobile or radio communication network or system, such as, the wireless communications network 100. Examples of such wireless devices are mobile phones, cellular phones, Personal Digital Assistants (PDAs), smart phones, tablets, Laptop Mounted Equipment (LME) (e.g. USB), Laptop Embedded Equipments (LEEs), etc. Further examples of such wireless device are loT devices, sensors equipped with wireless communication capabilities, Machine Type Communication (MTC) devices, Machine to Machine (M2M) devices, Customer Premises Equipment (CPE), target devices, device-to-device (D2D) enabled wireless devices, wireless devices capable of machine to machine (M2M) communication, etc.

In reference to the embodiments described hereinafter, since one or more of the wireless device 121 , 122, 123 also may be configured to serve or operate as a network node for other wireless devices in the wireless communications network 100, the term “node” is used to denoted any one of the first and/or second network node 110, 111 or the first, second and third wireless device 121 , 122, 123. In other words, the methods and apparatuses described by the embodiments below may be implemented and performed in any one of the first and/or second network node 110, 111 and/or the first, second and third wireless device 121 , 122, 123. It should here be noted that, for the sake of simplicity, the embodiments below are described with reference to an example wherein the first node is the first network node 110. Further, in this example, the second network node 111 may have a coverage area that partially or fully overlaps with the coverage area of the first network node 110 and operate using a different type of wireless communications technology than the first network node 110, as described above. This example should, however, not be construed as limiting, but only to serve a general example by which the different embodiments herein may be best described.

Fig. 2 depicts a scenario which illustrates conventional spatial filtering, also known as beamforming, for initial access. In this scenario, angular directions around the first node 110 are divided into different angular ranges, i.e. beamforming directions 1-12. The beamforming directions 1-12 are conventionally generated by the first node 110 using predetermined spatial filters, i.e. a codebook. Prior to initial access, the first node 110 may initiate communication link establishment by performing a time-sequential scan of the set of beamforming directions 1-12 with a reference signal transmission in the form of a synchronization block, SynB, being transmitted in each of the beamforming directions 1- 12. This may also be referred to as performing a discovery transmission. Here, a time- sequential scan of the beamforming directions with matching SynB-transmissions may be referred to as a Synchronization Signal, SS, burst. These bursts are generally periodic in time, i.e. occur according to a set time interval.

Such SS bursts, commonly referred to as SS burst sets, may in a wireless communications network such as NR, comprise a maximum of 8 time-sequential SynB transmissions, i.e. for systems operating in a frequency range of 3-6 GHz, or a maximum of 64 transmissions, i.e. for systems operating in a frequency range above 24 GHz. Here, the duration of one SS burst may be 5 ms. Also, the SS bursts are repeated periodically with the periodicity attaining any of the following values: 5 ms, 10 ms, 20 ms, 40 ms, 80 ms or 160 ms. In practice, each SynB transmission in a SS burst is transmitted using a spatial filter differing from spatial filters associated with other SynB transmissions in the SS burst; however, it should be noted that this association is not explicitly prescribed in the NR standard.

As part of the developing of the embodiments described herein, it has been realized that the current signalling framework supporting adaptive beamforming for initial access may be improved in order to overcome drawbacks such as power and transmission resource waste and inter-cell interference due to employing exhaustive blind beam scanning techniques during link establishment.

According to the embodiments described herein, a signalling framework supporting adaptive beamforming for initial access is presented which exploits a priori knowledge of the cell environment with the goal of reducing the signalling overhead needed for initial access. In other words, embodiments may use information in the wireless communications network which indicates which spatial filters that will maximize the probability of successful link establishment. This signalling framework proposes a timedomain structure comprising two types of periodic synchronization block, SynB, transmission bursts, namely a primary and a secondary burst. The Primary Burst, PB, may cover a subset of beamforming directions that may be dynamically changed. The beamforming directions in the PB are chosen based on auxiliary information about the user nodes in the wireless communications network, such as user location, directional information, etc., such that transmitting is performed in those beamforming directions which will yield higher likelihoods of successful link establishments. The Secondary Burst, SB, may comprise a wider range of beamforming directions and may also include the beamforming directions covered in PB. Here, the periodicity of SB is different than the periodicity of PB. One preferred configuration is that the periodicity of PB is smaller or shorter than the periodicity of SB, i.e. the time interval between PBs are shorter that the time interval between SBs.

It should be noted that the purpose with the SB is to explore the beamforming directions that are ignored in the PB. Thus, the SB offers a possibility of link establishment to user nodes which happen to be using the beamforming directions ignored in the PB and the SB thus enables an update of the knowledge of the cell environment. In other words, this PB/SB signalling framework may be viewed as exploration versus exploitation framework in the sense that the SB may be used for exploration, i.e. learning about the cell environment, while the PB is used for exploitation, i.e. performing the beam search based on a limited beam set determined using the obtained knowledge about the cell environment. Here, one important feature of the proposed signalling framework is also that the transmission resources assigned to exploration and exploitation, i.e. to SB and PB, are controlled and also may be dynamic.

Hence, in accordance with the embodiments described herein, by performing discovery transmissions more frequently on a reduced subset of beamforming directions comprised in the PB, for which successful link establishment is more likely than for at least some of the beamforming directions in the set of beamforming directions comprised in the SB, the consumption of power and transmission resources for communication link establishment during initial access is able to be reduced; for example, in comparison to previous signalling frameworks comprising only one type of periodic SynB transmission burst with an exhaustive blind angular direction search. Here, the reduction in transmission resources is a consequence of the PB comprising a reduced subset of likely beamforming directions for link establishment. Furthermore, this signalling framework will still ensure that all beamforming directions are periodically tested, since the SB may comprise a wider set, or the entire range, of beamforming directions. Hence, by employing one or more of the embodiments described herein, the process of establishing communication links for initial access is improved by reducing power and transmission resource waste and inter-cell interference, while maintaining a proper level of QoS.

According to some embodiments, information regarding whether the periodic SynB belongs to a PB or SB may also be communicated to the wireless devices. This may, for example, be performed by embedding this information in the payload of the SynB or by associating the PB and/or SB with a certain carrier frequency. Here, the periodicities or time intervals of the PB and the SB may also be communicated to the wireless devices. This may, for example, be performed as part of general system information broadcasted to the wireless devices or via information communicated on an auxiliary channel. The advantage of providing the wireless devices with information regarding whether the beam belongs to PB or SB, and the periodicity of the PB and SB, is that it enables the wireless devices to, for example, schedule its response to the network node, schedule future receptions and measurements of SynB, etc.

Examples of embodiments of a method performed by a first node 110 of a wireless communications network 100 for enabling communication link establishment towards wireless devices 121 , 122, 123 of the wireless communications network 100, will now be described with reference to the flowchart depicted in Fig. 3. Fig. 3 is an illustrated example of actions or operations which may be taken by the first node 110 in the wireless communication network 100. Here, it should be noted that the first node 110 may, according to some embodiments, perform conventional blind exhaustive beam search for a determined period of time before the initiation of the method described below. This may be performed in order to obtain knowledge and information regarding the cell environment in the cell 115 served by the network node 110. The method may comprise the following actions. Action 301

The first node 110 determines a subset B of beamforming directions from a set A of beamforming directions. This means, for example, that a set of angular directions corresponding to a set of spatial filters, i.e. one or more beamforming directions, determined to be comprised in set B may be a subset of the angular directions corresponding to a set of spatial filters used by the set A. Optionally, at least one beamforming direction in the subset B may be different from beamforming directions in set A either in terms of beamwidth, direction, transmit power, polarization, etc. It should also be noted that the set of beamforming directions determined to be comprised in, and scanned for, in the set A may be a part, or the full set, of the beamforming directions covered by the antenna array of the first node 110. For example, the set A may span a 360-degree angular sector with 12 different spatial filters covering 12 different beamforming directions that are scanned sequentially, and the subset B may scan only 2 of the 12 directions, e.g. beamforming directions 4 and 5, from the set A. This example is illustrated in Fig. 4.

In some embodiments, the first node 110 may identify that one or more beamforming directions in the set A have a higher likelihood of providing a successful communication link establishment than one or more of the other beamforming directions in the set A. Then, the first node 110 may select the one or more beamforming directions in the set A that have a higher likelihood of providing a successful communication link establishment to be comprised in the subset B. This means, for example, that the choice of which beamforming directions determined to be comprised in, and scanned for, in the subset B may be taken based on the first node 110 estimating that discovery transmission in those beamforming directions will give a higher likelihood of successfully establishing a communication link towards a wireless device 121, 122, 123; compared, of course, to the beamforming directions not chosen for the subset B.

According to some embodiments, the likelihood of providing a successful communication link establishment for each beamforming direction in the set A may be determined based on statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices 121, 122, 123 towards the first node 110. These directional measurements may, for example, be obtained by the first node 110 from previous initial access attempts by wireless devices 121 , 122, 123 in the cell 115 using one particular type of wireless communications technology, for example, wireless communications technology supporting transmission in the millimetre-waves (mmW) range, such as, NR, NR+, or IEEE 802.11ad. In other words, the first node 110 may be able to determine over which beam(s) these wireless devices

121 , 122, 123 transmitted their Physical Random Access Channel, PRACH, signal after finding a beam generated by the first node 110. Thus, the first node 110 may form a register of the beam access of the wireless devices 121 , 122, 123; assuming e.g. that the PRACH and SynB beams are related. This beam access register of wireless devices in the cell 115 may, for example, be part of the radio access network, RAN, or core network, CN, of the wireless communications network 100. Additionally, the first node 110 may also take into account, when determining the likelihood of providing a successful communication link establishment for each beamforming direction in the set A, the behaviour of the wireless devices 121 , 122, 123 which have already obtained access to the wireless communications network 100 in the cell 115 of the first node 110 and are currently operating either in an RRC_Connected or RRCJdle/lnactive state.

Optionally, the likelihood of providing a successful communication link establishment for each beamforming direction in the set A may also be determined based on statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices 121, 122, 123 towards a second node 111 in the wireless communications network 100. This means, for example, that the first node 110 may obtain radio access information associated with the wireless devices 121,

122, 123 towards an auxiliary system, e.g. the second network node 111 in the wireless communications network 100 supporting a different type of wireless communications technology. The radio access information may comprise information regarding the radio communication link and radio channels of the wireless devices 121 , 122, 123 towards the auxiliary system, such as, angular characteristics, positions, etc.

For example, the wireless devices may have accessed the wireless communications network 100 via another type of wireless communications technology than the one employed by the first node 110, e.g. via an auxiliary system employing another generation of mobile communications standard or using a lower frequency layer of the same generation of mobile communications standard as the first node 110. Hence, the first node 110 may obtain and use information and knowledge in the auxiliary system about in which directions and/or at which positions the wireless devices 121 , 122, 123 may have been found by the auxiliary system. This may, for example, be performed using an antenna array to obtain directional information on user channels of the wireless devices 121, 122, 123. In this case, the first node 110 may be required to interconnect, or be able to communicate, with the auxiliary system, e.g. the second network node 111 , in such a way that the statistical directional or positional information regarding where the wireless devices 121, 122, 123 may have been found in the cell 115 with higher probability of success may be exchanged. In some embodiments, the auxiliary system may be co-located with the first node 110, e.g. in the same network node or in the same gNB mast.

While the options mentioned above mainly focus on information collected for wireless devices through measurements over longer periods of time and across many different wireless devices, the likelihood of providing a successful communication link establishment for each beamforming direction in the set A may also be determined based on directional measurements and/or positioning information obtained from currently established communication links between wireless devices 121, 122, 123 and a second node 111 in the wireless communications network 100. This option focuses more on the initial access of particular wireless devices and on current or instantaneous Channel State Information, CSI, thereof. For example, in case a communication link establishment is made between the first node 110 and a wireless device 121 , 122, 123 in the cell 115 through an auxiliary system, such as the second network node 111 , the auxiliary system may comprise an antenna array enabling a determination of the direction in which the channel to/from the wireless device 121 , 122, 123 is the strongest. This information may then be obtained by the first node 110, e.g. this information may be made instantly available by the second network node 111 to the first network node 110. Furthermore, in case a communication link establishment is made between the first node 110 and a wireless device in the cell 115 through the auxiliary system, such as, the second network node 111 , a wireless device 121 , 122, 123 may also report its location. Simultaneously with obtaining the aforementioned information from an auxiliary system, through a PRACH signal received by the first node 110, the first node 110 may discover the preferred beamforming direction of a wireless devices 121, 122, 123. Information about directional measurements/positions of wireless devices 121, 122, 123 obtained from the auxiliary system, such as, the second network node 111, and information about preferred beamforming directions to wireless devices 121 , 122, 123 from the first node 110 may be used to determine or formulate a mapping from the information from the auxiliary system to preferred beamforming directions to wireless devices 121 , 122, 123 from first node 110.

In view of the above, in some embodiments, a machine learning model may be trained to estimate which beamforming directions that have the highest likelihood of providing a successful communication link establishment based on the statistical information and/or the directional/positional information associated with the second node 111. This means, for example, that the information regarding the location and the preferred beamforming direction of a wireless devices 121, 122, 123 may be used to train an Al/Machine Learning, AI/ML, algorithm. Hence, in subsequent operation, the position information obtained via the auxiliary system may, for example, be used as input to the AI/ML algorithm, whereby the output of the AI/ML algorithm may be an estimate of the preferred beam to use for reaching a wireless devices 121, 122, 123 by the first node 110.

It should be noted that, according to some embodiments, a beamforming direction may be determined as a range of angular directions around the first node 110.

Action 302

The first node 110 performs discovery transmissions in each of the beamforming directions of the set A based on a first time interval ti. This is illustrated in Figs. 4-5 by the transmission block SB. Within SB, the first node 110 performs a time-sequential scanning of the set of beamforming directions 1-12, i.e. the set A, and transmits a synchronization block, SynB, in each beamforming direction 1-12. This is then repeated with a periodicity of the first time interval ti .

Action 303

After the transmission in Action 302, the first node 110 perform discovery transmissions in each of the beamforming directions of the determined subset B based on a second time interval t2, wherein the second time interval t2 is shorter than the first time interval ti. This is illustrated in Figs. 4-5 by the transmission block PB. Within PB, the first node 110 performs a time-sequential scanning of the set of beamforming directions 4-5, i.e. the subset B, and transmits a synchronization block, SynB, in each beamforming direction 4-5. This is then repeated with a periodicity of the second time interval t2. Here, the second time interval t2 is different from the first time interval ti , for example, t2 < ti. According to the latter, the PB is transmitted more frequently than the SB. For example, in Fig. 4, the time interval ratio between PB and SB is 5:1.

It should be noted that, according to some embodiments, the discovery transmissions may comprise transmission bursts generated by using a set of spatial filters in a time-sequential manner, wherein the set of spatial filters match the different beamforming directions in the set A and the determined subset B, respectively, and have a periodicity corresponding to the first and second timing interval ti and t2, respectively. This is illustrated in Figs. 4-5 by the transmission bursts in the transmission blocks SB and PB. In other words, the codebooks, i.e. the set of predetermined spatial filters, may be associated with corresponding sets of reference signals, e.g. SynB, and time- and frequency domain transmission resources. Here, the codebook, the reference signals, and the time and frequency resources together may be said to constitute the transmission bursts. Accordingly, in some embodiments, the transmission burst SB corresponding to the longer time interval, e.g. ti, is repeated periodically with time period ti , whereas the transmission burst PB corresponding to the shorter time interval, e.g. t2, is transmitted at time t2 after the start of the transmission burst SB and then repeated with time period t2 until the next transmission of the transmission burst SB. This time structure is illustrated in Fig. 4.

Furthermore, according to some embodiments, the time offset, Toffset, from the start of a discovery transmission in a determined beamforming direction is the same within a transmission burst for the determined subset B as within a transmission burst for the set A. This means, for example, that for beamforming directions that are scanned both in PB and SB, i.e. that are part of both the set A and subset B, a particular beamforming direction will be associated with the same time slot within both transmission bursts. This advantageously ensures that the periodicity of the beamforming directions scanned in PB is preserved with the introduction of SB. This is illustrated in Fig. 5, wherein the beamforming directions scanned at the time positions 4 and 5 in the PB are scanned at the same time positions in the SB.

In some embodiments, the discovery transmissions associated with the set A may comprise a first information indicating to the wireless device 121 , 122, 123 that the discovery transmissions are associated with the set A. Optionally, the discovery transmissions associated with the determined subset B may comprise a second information indicating to the wireless device 121 , 122, 123 that the discovery transmissions are associated with the determined subset B. This means, for example, that the first node 110 may explicitly communicate the association of a SynB with a SB or PB to the wireless device 121 , 122, 123 by inserting this information in the SynB, such as, in a bit or bit-field in a Master Information Block, MIB, in a Physical Broadcast Channel, PBCH. Optionally, the information indicating the association of a SynB with a SB or PB may also be comprised in a System Information Block, e.g. SIB1. Here, the wireless device 121 , 122, 123 may, upon successful decoding of the SynB, read out the contents of the bit or bit-field and thus determine whether the SynB was transmitted in a PB or SB.

Alternatively, the first node 110 may also implicitly communicate the association of a SynB with a SB, for example, by scrambling all or part of SynB; that is, by e.g. using one scrambling pattern associated with a beam belonging to SB, and using another scrambling pattern associated with a beam belonging to PB. According to another option, the implicit communication may also be performed by dedicating a subset of System Frame Numbers, SFNs, to SB or PB in a standard. Further options for the implicit communication may be to: associate the SB or PB with specific carrier frequencies in the synchronization frequency raster, , or encode PB versus SB in another information element or property of SynB. Yet another example of the implicit communication is that the first node 110 may transmit the PB and SB such that they are different in at least one characteristic. Here, the differing at least one characteristic may be pre-configured, e.g. in a standard as part of standardization specifications. Here, the wireless device 121, 122, 123 may, after a successful decoding of SynB, determine whether the SynB was transmitted in a PB or SB; that is, by using the SFN of the decoded block, the carrier frequency on which the SynB was detected, the scrambling code, or any other differing characteristic that was determined following the successful decoding of the SynB.

In some embodiments, the first and/or second information may further comprise a third information indicating at least one of the first and second timing intervals ti , t2. This means, for example, that the first node 110 may communicate or indicate the time periods, or intervals, of the PB and SB to the wireless device 121, 122, 123. Optionally, the first node 110 may communicate or indicate the time period, or interval, of the PB and its relation to the time period, or interval, of SB (or vice versa) to the wireless device 121, 122, 123. This may, for example, be performed via a dedicated field in the payload data of SynB, e.g. MIB in NR+. Alternatively, this may also be performed either as part of the system configuration broadcasted to the wireless device 121, 122, 123 on a scheduled transmission, e.g. SIB1 or any other SIBs in NR+; as part of information exchanged between first node 110 and the wireless device 121, 122, 123 via an auxiliary system, e.g. via the second network node 111 ; or as part of information about adjacent cells broadcasted to the wireless device 121 , 122, 123 in the serving cell 115.

Action 304

Optionally, the first node 110 may establish a communication link between the first node 110 and a wireless device 121 , 122, 123 upon receiving an initial access transmission from the wireless device 121 , 122, 123 in response to one or more of the discovery transmissions. This advantageously allows an improved to set up a communication link over the air interface between the first node 110 and wireless devices 121 , 122, 123, thus enabling a faster initial access for the wireless devices 121, 122, 123 in the wireless communications network 100. As indicated in Fig. 3, according to some embodiment, the first node 110 may continuously perform the determination of the subset B based on updated likelihoods of providing a successful communication link establishment for the beamforming directions in the set A. This means that the subset B may be dynamically re-determined based on updated information regarding the cell environment of cell 115 served by the first node 110. According to some embodiments, the first node 110 may be configured to reevaluate the selection of beamforming directions for the PB or SB periodically. Optionally, a re-evaluation may be triggered by a change in the positions or directional channel state of the wireless devices 121 , 122, 123.

In some embodiments, the first node 110 may configure the wireless devices 121,

122, 123 with a signalling mechanism such that the wireless devices 121 , 122, 123 may provide feedback information regarding an existing or updated PB/SB configuration. Such a signalling mechanism may cause the wireless devices 121 , 122, 123 to report feedback information indicating, for example, whether a PB/SB configuration using the SB and PB current used by the first node 110 is beneficial or not to the wireless devices 121, 122,

123, e.g. a level of perceived beam quality or a general initial access review. This signalling may, for example, be comprised in Physical Random Access Channel, PRACH, signalling. In this case, for example, the wireless devices 121 , 122, 123 may access the PRACH channel via the communication link established following a successful beam search. Here, that data payload may comprise an additional or modified bit or bit-field indicating the feedback information. Alternatively, in case the wireless devices 121 , 122, 123 is in the RRC_Connected mode, the wireless devices 121 , 122, 123 may indicate the feedback information over UL control channel, such as, the Physical Uplink Control Channel, PUCCH, or UL shared channel, such as, the Physical Uplink Shared Channel, PUSCH. For any of the above alternatives, the wireless devices 121 , 122, 123 may also provide additional information, such as, information indicating whether or not the wireless device 121 , 122, 123 estimates it will be stationary or moving, or remain in the cell 115, etc. Furthermore, the wireless device 121 , 122, 123 may also be configured to provide such information regarding a specific beam, or specific to a PB and/or SB, etc.

Hence, according to a further aspect of the embodiments herein, a wireless device 121 , 122, 123, and a method therein, for enabling establishments of communication links in a wireless communications network 100 is also provided. The wireless device 121, 122, 123 may be configured to receive a discovery transmission from a first node 110. Also, the wireless device 121 , 122, 123 may be configured to transmit or signal, in response to the received discovery transmission from a first node 110, information indicating a perceived level of quality associated with the establishment of its communication link towards the first node 110 in the wireless communications network 100. Here, the information may refer to the beam used in the discovery transmission and/or to the current PB/SB configuration used and signalled to the wireless device 121, 122, 123 by the first node 110 in the discovery transmission.

In this case, the first node 110 may use the reported feedback information to score the existing or updated PB/SB configuration. For example, in case a total score of a current PB/SB configuration by the wireless devices 121 , 122, 123 is equal to or above a first threshold value, the first node 110 may maintain the PB/SB configuration. Optionally, in case a total score of a current PB/SB configuration by the wireless devices 121 , 122, 123 is below a second threshold value, the first node 110 may switch to a default or previous PB/SB configuration, or update the current PB/SB configuration until the total score is above the first threshold value. Here, it should be noted that the first and second threshold value may be, the same or different values. Furthermore, the feedback information from the wireless devices 121, 122, 123 may also be used to train an Al/Machine Learning, AI/ML, algorithm to determine the score of PB/SB configurations. Hence, in subsequent operation, the feedback information obtained from the wireless devices 121 , 122, 123 may be used as input to the AI/ML algorithm, whereby the output of the AI/ML algorithm may be a score of the current PB/SB configuration used by the first node 110.

It should be noted that, according to some embodiments, the first node may be a network node 110 or a wireless device 121, 122, 123 configured to operate as a network node 110 in the wireless communications network 100. This means, for example, that the first node 110 may, besides e.g. being a gNB in a NR or NR+ wireless communications network 100, also be a wireless device serving as a network node in a cell 115 of a wireless communications network 100.

As a consequence of the embodiments described herein, it should be noted that some or all of the time-frequency transmission resources in the wireless communications network 100 that are no longer used for SynB, or other Synchronization Signal Block, SSB, transmissions as compared to in a legacy wireless communications network may instead advantageously be configured to support, for example, physical DL channels and/or reference signal transmissions/receptions. According to one example, these new available resources may advantageously be configured as PDCCH/PDSCH and thus be used for DL data transmission. Optionally, these new available resources may advantageously be configured for Channel State Information Reference Signals/Sounding Reference Signal, CSI-RS/SRS, transmissions. This is further exemplified and illustrated in Fig. 5, wherein the time-frequency transmission resources or beamforming time slots 1- 3 and 6-12 are not being used for SynB/SSB transmission according to the PB/SB configuration. Hence, these time-frequency transmission resources or beamforming time slots may be configured by the first node 110 for other types of transmissions. Here, the first node 110 may use standard DL control signalling techniques, such as DCI transmissions, to inform the wireless device 121, 122, 123 about which physical channels and/or reference signal transmissions will take place at these new available resources.

Additionally, it should also be noted that even though the embodiments described above are described in reference to a set A and a subset B, any number of sets or subsets may be used in a similar manner for the different beamforming directions. The number of sets or subsets may also be assigned different priorities, such as, a primary set or subset, a secondary set or subset, a third set or subset, etc.

To perform the method actions in a first node 110 configured to operate in a wireless communications network 100 and enable establishment of communication links towards wireless devices 121 , 122, 123 of the wireless communications network 100, the first node 110 may comprise the following arrangement depicted in Fig 6. Fig 6 shows a schematic block diagram of embodiments of a first node 110. The embodiments of the first node 110 described herein may be considered as independent embodiments or may be considered in any combination with each other to describe non-limiting examples of the example embodiments described herein. It should also be noted that, although not shown in Fig. 6, it should be noted that known conventional features of a first node 110, such as, for example, at least one antenna and a power source, e.g. a battery or main connection, may be assumed to be comprised in the first node 110 but is not shown or described any further in regards to Fig. 6.

The first node 110 may comprise processing circuitry 610 and a memory 620. The processing circuitry 610 may also comprise a receiving module 611 and a transmitting module 612. The receiving module 611 and the transmitting module 612 may comprise Radio Frequency, RF, circuitry and baseband processing circuitry capable of transmitting and receiving a radio signal in the wireless communications network 100. The receiving module 611 and the transmitting module 612 may also form part of a single transceiver. It should also be noted that some or all of the functionality described in the embodiments above as being performed by the first node 110 may be provided by the processing circuitry 610 executing instructions stored on a computer-readable medium, such as, the memory 620 shown in Fig. 6. Alternative embodiments of the first node 110 may comprise additional components, such as, for example, a determining module 613, performing module 614, and establishing module 615 responsible for providing its functionality to support the embodiments described herein.

The first node 110 or processing circuitry 610 is configured to, or may comprise the determining module 613 configured to, determine a subset B of beamforming directions from a set A of beamforming directions. Also, the first node 110 or processing circuitry 610 is configured to, or may comprise the performing module 614 configured to, perform discovery transmissions SB in each of the beamforming directions of the set A based on a first time interval ti. Furthermore, the first node 110 or processing circuitry 610 is configured to, or may comprise the performing module 614 configured to, perform discovery transmissions PB in each of the beamforming directions of the determined subset A based on a second time interval t2, wherein the second timing interval t2 is shorter than the first timing interval ti.

In some embodiments, the first node 110 or processing circuitry 610 may be configured to, or may comprise the determining module 613 configured to, identify that one or more beamforming directions in the set A have a higher likelihood of providing a successful communication link establishment than one or more of the other beamforming directions in the set A. Here, the first node 110 or processing circuitry 610 may also be configured to, or may comprise the determining module 613 configured to, select the one or more beamforming directions in the set A that have a higher likelihood of providing a successful communication link establishment to be comprised in the subset B. Furthermore, in some embodiments, the first node 110 or processing circuitry 610 may be configured to, or may comprise the determining module 613 configured to, determine the likelihood of providing a successful communication link establishment for each beamforming direction in the set A based on one or more of: statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices 121 , 122, 123 towards the first node 110; statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices 121, 122, 123 towards a second node 111 in the wireless communications network 100; and directional measurements and/or positioning information obtained from previously established communication links between the wireless devices 121 , 122, 123 and a second node 111 in the wireless communications network 100. Also, in some embodiments, the first node 110 may be configured with a machine learning model that is trained to estimate which beamforming directions that have the highest likelihood of providing a successful communication link establishment based on the statistical information and/or the directional/positional information associated with the second node 111. In some embodiments, the first node 110 or processing circuitry 610 may be configured to, or may comprise the determining module 613 configured to, continuously perform the determination of the subset B based on updated likelihoods of providing a successful communication link establishment for the beamforming directions in the set A.

In some embodiments, the discovery transmissions may comprise transmission bursts generated by using a set of spatial filters in a time-sequential manner, wherein the set of spatial filters match the different beamforming directions in the set A and determined subset B, respectively, and have a periodicity corresponding to the first and second timing interval ti, t2, respectively. Also, in some embodiments, the time offset Toffset from the start of a discovery transmission in a determined beamforming direction may be the same within a transmission burst for the determined subset B as within a transmission burst for the set A. Further, in some embodiments, the discovery transmissions associated with the set A may comprise a first information indicating to the wireless device 121 , 122, 123 that the discovery transmissions are associated with the set A and/or the determined subset B may comprise a second information indicating to the wireless device

121 , 122, 123 that the discovery transmissions are associated with the determined subset B discovery transmissions associated with the determined subset B. In this case, in some embodiments, the first and/or second information further comprises a third information indicating at least one of the first and second timing intervals ti , t2.

According to some embodiments, the first node 110 or processing circuitry 610 may be configured to, or may comprise the establishing module 614 configured to, establish a communication link between the first node 110 and a wireless device 121,

122, 123 upon receiving an initial access transmission from the wireless device 121, 122, 123 in response to one or more of the discovery transmissions.

Furthermore, the embodiments for enabling establishment of communication links towards wireless devices 121, 122, 123 of the wireless communications network 100 described above may be implemented through one or more processors, such as the processing circuitry 610 in the first node 110 depicted in Fig. 6, together with 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 or code means for performing the embodiments herein when being loaded into the processing circuitry 610 in the first node 110. The computer program code may e.g. be provided as pure program code in the first node 110 or on a server and downloaded to the first node 110. Thus, it should be noted that the modules of the first node 110 may in some embodiments be implemented as computer programs stored in memory, e.g. in the memory modules 620 in Fig. 6, for execution by processors or processing modules, e.g. the processing circuitry 610 of Fig. 6.

Those skilled in the art will also appreciate that the processing circuitry 610 and the memory 620 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 a memory, that when executed by the one or more processors such as the processing circuitry 610 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (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).

The description of the example embodiments provided herein have been presented for purposes of illustration. The description is not intended to be exhaustive or to limit example embodiments to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various alternatives to the provided embodiments. The examples discussed herein were chosen and described in order to explain the principles and the nature of various example embodiments and its practical application to enable one skilled in the art to utilize the example embodiments in various manners and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be appreciated that the example embodiments presented herein may be practiced in any combination with each other.

It should be noted that the word “comprising” does not necessarily exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example embodiments may be implemented at least in part by means of both hardware and software, and that several “means”, “units” or “devices” may be represented by the same item of hardware. It should also be noted that the various example embodiments described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer- readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

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

Additional aspects

According to a first additional aspect of the embodiments described herein, it is also presented a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising: at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE determines a subset of beamforming directions from a set of beamforming directions, performs discovery transmissions in each of the beamforming directions of the set based on a first time interval, and performs discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval, wherein the second time interval is shorter than the first time interval. The method may further comprise: at the UE, providing the user data to the base station. The method may further comprise: at the UE, executing a client application, thereby providing the user data to be transmitted; and at the host computer, executing a host application associated with the client application. The method may further comprise: at the UE, executing a client application; and at the UE, receiving input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application, wherein the user data to be transmitted is provided by the client application in response to the input data.

According to a second additional aspect of the embodiments described herein, it is also presented a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising: at the host computer, providing user data; and at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the base station determines a subset of beamforming directions from a set of beamforming directions, performs discovery transmissions in each of the beamforming directions of the set based on a first time interval, and performs discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval, wherein the second time interval is shorter than the first time interval. The method may further comprise: at the base station, transmitting the user data. A method as described above, wherein the user data is provided at the host computer by executing a host application, and the method further comprises: at the UE, executing a client application associated with the host application, may also be provided.

According to a third additional aspect of the embodiments described herein, it is also presented a communication system including a host computer comprising: a communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station, wherein the UE comprises a radio interface and processing circuitry, the UE’s processing circuitry configured to: determine a subset of beamforming directions from a set of beamforming directions, perform discovery transmissions in each of the beamforming directions of the set based on a first time interval, and perform discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval, wherein the second time interval is shorter than the first time interval. The communication system may further include the UE. The communication system may further include the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station. A communication system described above, wherein: the processing circuitry of the host computer is configured to execute a host application; and the UE’s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data may also be provided. A communication system described above, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing request data; and the UE s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data in response to the request data may also be provided.

According to a fourth additional aspect of the embodiments described herein, it is also presented a communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station’s processing circuitry configured to determine a subset of beamforming directions from a set of beamforming directions, perform discovery transmissions in each of the beamforming directions of the set based on a first time interval, and perform discovery transmissions in each of the beamforming directions of the determined subset based on a second time interval, wherein the second time interval is shorter than the first time interval. The communication system may further include the base station. The communication system may further include the UE, wherein the UE is configured to communicate with the base station. A communication system described above, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application may also be provided.

With reference to Fig. 7, in accordance with an embodiment, a communication system includes a telecommunication network 3210, such as a 3GPP-type cellular network, 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 NBs, eNBs, gNBs 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 user equipment (UE) 3291 located in coverage area 3213c is configured to wirelessly connect to, or be paged by, the corresponding base station 3212c. A second UE 3292 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 Fig. 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 Fig. 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 Fig. 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 Fig. 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, applicationspecific 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 Fig. 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 Fig. 7, respectively. This is to say, the inner workings of these entities may be as shown in Fig. 8 and independently, the surrounding network topology may be that of Fig. 7.

In Fig. 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 ability to set up of a communication link over the airinterface, and thereby provide benefits such as a faster initial access procedure.

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 QQ550 between host computer QQ510 and UE QQ530, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring OTT connection QQ550 may be implemented in software QQ511 and hardware QQ515 of host computer QQ510 or in software QQ531 and hardware QQ535 of UE QQ530, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which OTT connection QQ550 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 QQ511 , QQ531 may compute or estimate the monitored quantities.

The reconfiguring of OTT connection QQ550 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect base station QQ520, and it may be unknown or imperceptible to base station QQ520. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating host computer QQ510’s measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that software QQ511 and QQ531 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using OTT connection QQ550 while it monitors propagation times, errors etc.

Fig. 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 and a UE which may be those described with reference to Fig. 13 and 10. For simplicity of the present disclosure, only drawing references to Fig. 15 will be included in this section. In step QQ610, the host computer provides user data. In substep QQ611 (which may be optional) of step QQ610, the host computer provides the user data by executing a host application. In step QQ620, the host computer initiates a transmission carrying the user data to the UE. In step QQ630 (which may be optional), 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 step QQ640 (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

Fig. 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 and a UE which may be those described with reference to Fig. 13 and 10. For simplicity of the present disclosure, only drawing references to Fig. 16 will be included in this section. In step QQ710 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 step QQ720, 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 step QQ730 (which may be optional), the UE receives the user data carried in the transmission.

Fig. 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 and a UE which may be those described with reference to Fig. 13 and 10. For simplicity of the present disclosure, only drawing references to Fig. 19 will be included in this section. In step QQ810 (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step QQ820, the UE provides user data. In substep QQ821 (which may be optional) of step QQ820, the UE provides the user data by executing a client application. In substep QQ811 (which may be optional) of step QQ810, 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 substep QQ830 (which may be optional), transmission of the user data to the host computer. In step QQ840 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.

Fig. 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 and a UE which may be those described with reference to Fig. 13 and 10. For simplicity of the present disclosure, only drawing references to Fig. 20 will be included in this section. In step QQ910 (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step QQ920 (which may be optional), the base station initiates transmission of the received user data to the host computer. In step QQ930 (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

Claims

1. A method performed by a first node (110) of a wireless communications network (100) for enabling communication link establishment towards wireless devices (121 , 122, 123) of the wireless communications network (100), the method comprising determining (301) a subset (B) of beamforming directions (4, 5) from a set (A) of beamforming directions (1-12); performing (302) discovery transmissions (SB) in each of the beamforming directions of the set (A) based on a first time interval (ti); and performing (303) discovery transmissions (PB) in each of the beamforming directions of the determined subset (B) based on a second time interval (t₂), wherein the second time interval (t₂) is shorter than the first time interval (ti).

2. The method according to claim 1, wherein the determining (301) further comprises identifying that one or more beamforming directions (4, 5) in the set (A) have a higher likelihood of providing a successful communication link establishment than one or more of the other beamforming directions (1-3, 6-12) in the set (A), and selecting the one or more beamforming directions (4, 5) in the set (A) that have a higher likelihood of providing a successful communication link establishment to be comprised in the subset (B).

3. The method according to claim 2, wherein the likelihood of providing a successful communication link establishment for each beamforming direction in the set (A) is determined based on one or more of:

- statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices (121 , 122, 123) towards the first node (110);

- statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices (121 , 122, 123) towards a second node (111) in the wireless communications network (100); and

- directional measurements and/or positioning information obtained from currently established communication links between wireless devices (121, 122, 123) and a second node (111) in the wireless communications network (100).

4. The method according to claim 3, wherein a machine learning model is trained to estimate which beamforming directions that have the highest likelihood of providing a successful communication link establishment based on the statistical information and/or the directional/positional information associated with the second node (111).

5. The method according to any of claims 1-4, wherein the determination of the subset (B) is performed continuously based on updated likelihoods of providing a successful communication link establishment for the beamforming directions in the set (A).

6. The method according to any of the claims 1-5, wherein the discovery transmissions comprise transmission bursts (SB, PB) generated by using a set of spatial filters in a time-sequential manner, wherein the set of spatial filters match the different beamforming directions in the set (A) and the determined subset (B), respectively, and have a periodicity corresponding to the first and second timing intervals (ti , t2), respectively.

7. The method according to claim 6, wherein the time offset (Toffset) from the start of a discovery transmission in a determined beamforming direction is the same within a transmission burst for the determined subset (B) as within a transmission burst for the set (A).

8. The method according to any of claims 1-7, wherein the discovery transmissions associated with the set (A) comprise a first information indicating to the wireless device (121, 122, 123) that the discovery transmissions are associated with the set (A) and/or the determined subset (B) comprise a second information indicating to the wireless device (121 , 122, 123) that the discovery transmissions are associated with the determined subset (B).

9. The method according to claim 8, wherein the first and/or second information further comprises a third information indicating at least one of the first and second timing intervals (ti , t2).

10. The method according to any of claims 1-9, further comprising establishing (304) a communication link between the first node (110) and the wireless device (121 , 122, 123) upon receiving an initial access transmission from the wireless device (121 , 122, 123) in response to one or more of the discovery transmissions. The method according to any of claims 1-10, wherein a beamforming direction is determined as a range of angular directions around the first node (110). The method according to any of claims 1-11, wherein the first node is a network node (110) or a wireless device (121 , 122, 123) configured to operate as a network node (110) in the wireless communications network (100). A first node (110) configured to operate in a wireless communications network (100) and enable establishment of communication links towards wireless devices (121 , 122, 123) of the wireless communications network (100), the first node (110) being further configured to determine a subset (B) of beamforming directions (4, 5) from a set (A) of beamforming directions (1-12), perform discovery transmissions (SB) in each of the beamforming directions of the set (A) based on a first time interval (ti), and perform discovery transmissions (PB) in each of the beamforming directions of the determined subset (A) based on a second time interval (t₂), wherein the second timing interval (t₂) is shorter than the first timing interval (ti). The first node (110) according to claim 13, further configured to identify that one or more beamforming directions (4, 5) in the set (A) have a higher likelihood of providing a successful communication link establishment than one or more of the other beamforming directions (1-3, 6-12) in the set (A), and selecting the one or more beamforming directions (4, 5) in the set (A) that have a higher likelihood of providing a successful communication link establishment to be comprised in the subset (B). The first node (110) according to claim 14, further configured to determine the likelihood of providing a successful communication link establishment for each beamforming direction in the set (A) based on one or more of: - statistical information associated with directional measurements obtained based on previous initial access attempts by wireless devices (121 , 122, 123) towards the first node (110);

- directional measurements and/or positioning information obtained from previously established communication links between the wireless devices (121 , 122, 123) and a second node (111) in the wireless communications network (100).

16. The first node (110) according to claim 15, further configured with a machine learning model that is trained to estimate which beamforming directions that have the highest likelihood of providing a successful communication link establishment based on the statistical information and/or the directional/positional information associated with the second node (111).

17. The first node (110) according to any of claims 13-16, further configured to continuously perform the determination of the subset (B) based on updated likelihoods of providing a successful communication link establishment for the beamforming directions in the set (A).

18. The first node (110) according to any of the claims 13-17, wherein the discovery transmissions comprise transmission bursts (SB, PB) generated by using a set of spatial filters in a time-sequential manner, wherein the set of spatial filters match the different beamforming directions in the set (A) and the determined subset (B), respectively, and have a periodicity corresponding to the first and second timing interval (ti, t2), respectively.

19. The first node (110) according to claim 18, wherein the time offset (Toffset) from the start of a discovery transmission in a determined beamforming direction is the same within a transmission burst for the determined subset (B) as within a transmission burst for the set (A). The first node (110) according to any of claims 13-19, wherein the discovery transmissions associated with the set (A) comprise a first information indicating to the wireless device (121 , 122, 123) that the discovery transmissions are associated with the set (A) and/or the determined subset (B) comprise a second information indicating to the wireless device (121 , 122, 123) that the discovery transmissions are associated with the determined subset (B) discovery transmissions associated with the determined subset (B). The first node (110) according to claim 20, wherein the first and/or second information further comprises a third information indicating at least one of the first and second timing intervals (ti , t2). The first node (110) according to any of claims 13-21, further configured to establish a communication link between the first node (110) and the wireless device (121, 122, 123) upon receiving an initial access transmission from the wireless device (121, 122, 123) in response to one or more of the discovery transmissions. The first node (110) according to any of claims 13-22, wherein each beamforming direction comprises a range of angular directions around the first node (110). The first node (110) according to any of claims 13-23, wherein the first node is a network node (110) in the wireless communications network (100), or a wireless device (121 , 122, 123) configured to operate as a network node (110) in the wireless communications network (100). A first node (110) configured to operate in a wireless communications network (100) and enable establishment of communication links towards wireless devices (121 , 122, 123) of the wireless communications network (100), wherein the first node (110) comprise a processing circuitry (610) and a memory (620), the processing circuitry (610) being configured to: determine a subset (B) of beamforming directions (4, 5) from a set (A) of beamforming directions (1-12), perform discovery transmissions (SB) in each of the beamforming directions of the set (A) based on a first time interval (ti), and perform discovery transmissions (PB) in each of the beamforming directions of the determined subset (A) based on a second time interval (t₂), wherein the second timing interval (t₂) is shorter than the first timing interval (ti). The first node (110) according to claim 25, wherein the processing circuitry (610) is further configured to carry out the method according to any of claims 2-12. A computer program product, comprising instructions which, when executed in a processing circuitry (610), cause the processing circuitry (610) to carry out the method according to any of claims 1-12. A carrier containing the computer program product according to claim 27, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer- readable storage medium.