Patent Description:
For example, for future generations of mobile communications networks, frequency bands at many different carrier frequencies could be needed. For example, low such frequency bands could be needed to achieve sufficient network coverage for wireless devices and higher frequency bands (e.g. at millimeter wavelengths (mmW), i.e. near and above <NUM>) could be needed to reach required network capacity. In general terms, at high frequencies the propagation properties of the radio channel are more challenging and beamforming both at the network node of the network and at the wireless devices might be required to reach a sufficient link budget.

Narrow beam transmission and reception schemes might be needed at such high frequencies to compensate the expected high propagation loss. For a given communication link, a respective beam can be applied at both the network-end (as represented by a network node or its transmission and reception point, TRP) and at the terminal-end (as represented by a terminal device), which typically is referred to as a beam pair link (BPL). One task of the beam management procedure is to discover and maintain beam pair links. A BPL (i.e. both the beam used by the network node and the beam used by the terminal device) is expected to be discovered and monitored by the network using measurements on downlink reference signals, such as channel state information reference signals (CSI-RS), used for beam management.

The reference signals for beam management can be transmitted periodically, semi-persistently or aperiodically (event triggered) and they can be either shared between multiple terminal devices or be device-specific. In order for the terminal device to find a suitable network node beam, the network node transmits the reference signal in different transmission (TX) beams on which the terminal device performs measurements, such as reference signal received power (RSRP), and reports back the N best TX beams (where N can be configured by the network). It is expected that different TX beams are transmitted in different reference signal resources (where each resource is defined in a time/frequency-grid, and that the terminal device reports back N resource indicators, such as CSI-RS resource indicators (CRIs), to inform the network node which TX beams are best. Furthermore, the transmission of the reference signal on a given TX beam can be repeated to allow the terminal device to evaluate a suitable reception (RX) beam.

Further, the beam management might be divided into two phases. For example, a periodic TX beam sweep in which reference signals are transmitted utilizing wider beam can be used to determine a first approximate direction towards each respective terminal device. Then a second (typically aperiodic/or semi-persistent) TX beam sweep in which reference signals are transmitted utilizing narrower beams can be performed based on the determined approximate direction to determine narrower TX beams that later can be used for data and/or control signalling.

<FIG> illustrates one example of a beam space 400a with one set of narrow beams <NUM> (all circles with solid lines) and one set of wide beams <NUM> (all ellipses with dotted lines). The beams <NUM>, <NUM> collectively cover a network coverage region <NUM> (dash-dotted line). In this respect, the illustration in <FIG> is somewhat simplified since the narrow beams <NUM> as well as the wider beams <NUM> in reality should have a slight overlap in order to avoid network coverage holes in the network coverage region <NUM>. The wide beams <NUM> could be used in the first phase of the beam management to find approximate direction towards each respective terminal device. The narrow beams <NUM> within the selected wide beams could be used in a second phase of the beam management in order to find a narrow TX beam to each of the terminal devices. This will reduce the average number of beams resources needed for transmitting the reference signal from <NUM> (i.e., <NUM> occurrence of the reference signal in each of the <NUM> narrow beams) to <NUM> + ((<NUM>/<NUM>)·<NUM>) ·<NUM> = <NUM> beam resources (i.e., <NUM> occurrence of the reference signal in each of the <NUM> wide beams plus <NUM> occurrence of the reference signal in each of the <NUM> narrow beams within each of the <NUM> wide beams, where the terminal device has an equal probability of being within network coverage of each of the <NUM> wide beams).

However, although dividing the beam management into two phases might reduce the number of beams which the terminal devices needs to evaluate, the overhead signalling (e.g. as defined by the number of needed beams resources) might still be too large for some network configurations.

<CIT> relates to an apparatus and method for selecting the best beam in a wireless communication system. An operation of a Base Station (BS) includes repeatedly transmitting reference signals beamformed with a first width, receiving a feedback signal indicating at least one preferred-beam having the first width from at least one terminal, determining a direction range within which reference signals beamformed with a second width are to be transmitted and a transmission pattern, based on the at least one preferred-beam having the first width, repeatedly transmitting the reference signals beamformed with the second width within the determined direction range according to the transmission pattern, and receiving a feedback signal indicating at least one preferred-beam having the second width from the at least one terminal.

<CIT> discloses how transmit and/or receive beamforming can be applied to the control channel transmission/reception, e.g., in mmW access link system design. Techniques to identify candidate control channel beams and/or their location in the subframe structure may provide for efficient WTRU operation. A framework for beam formed control channel design may support varying capabilities of mBs and/or WTRUs, and/or may support time and/or spatial domain multiplexing of control channel beams. For a multi-beam system, modifications to reference signal design may discover, identify, measure, and/or decode a control channel beam.

Techniques may mitigate inter-beam interference. WTRU monitoring may consider beam search space, perhaps in addition to time and/or frequency search space. Enhancements to downlink control channel may support scheduling narrow data beams. Scheduling techniques may achieve high resource utilization, e.g., perhaps when large bandwidths are available and/or WTRUs may be spatially distributed.

<NPL> provides an overview of key features pertaining to CSI reporting an beam management for the <NUM> New Radio (NR) standardized in 3GPP.

<CIT> relates to methods for efficient beam training, and more particularly to methods for hierarchical beam training.

<CIT> discloses calculation of one or more parameters of one or more vertical sectors of a base station based on the distribution of elevation angles of one or more User Equipment served by the base station.

There is still a need for improved beam management procedures.

An object of embodiments herein is to provide determining of beam settings that can be used for efficient beam management.

According to a first aspect there is presented a method for determining beam settings for beam management according to claim <NUM>.

According to a second aspect there is a radio transceiver device for determining beam settings for beam management according to claim <NUM>.

Advantageously this provides efficient determining of beam settings. Advantageously the determined beam settings can be used for efficient beam management.

Advantageously this enables the overhead signaling for beam management procedures to be reduced.

Advantageously, the reduction in overhead signaling may in turn increase the capacity of payload in the network, or be used for idle time and hence energy saving.

According to a third aspect there is presented a computer program for determining beam settings for beam management according to claim <NUM>.

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

<FIG> is a schematic diagram illustrating a communications network <NUM> where embodiments presented herein can be applied. The communications network <NUM> could be a third generation (<NUM>) telecommunications network, a fourth generation (<NUM>) telecommunications network, or a fifth (<NUM>) telecommunications network and support any 3GPP telecommunications standard, where applicable.

The communications network <NUM> comprises a radio transceiver device 200a configured to, via TRP 300a, provide network access to radio transceiver devices 200b, comprising TRP 300b, in a radio access network <NUM>. In some embodiments each radio transceiver device 200b is part of, integrated with, or collocated with, a terminal device and radio transceiver device 200a is part of, integrated with, or collocated with, a network node.

Examples of network nodes are radio access network nodes, radio base stations, base transceiver stations, Node Bs, evolved Node Bs, g Node Bs, access points, access nodes, and backhaul nodes. Examples of terminal devices are wireless devices, mobile stations, mobile phones, handsets, wireless local loop phones, user equipment (UE), smartphones, laptop computers, tablet computers, network equipped sensors, network equipped vehicles, and so-called Internet of Things devices.

Radio access network <NUM> is operatively connected to a core network <NUM>. The core network <NUM> is in turn operatively connected to a service network <NUM>, such as the Internet. Radio transceiver device 200b is thereby, via radio transceiver device 200a, enabled to access services of, and exchange data with, the service network <NUM>.

The herein disclosed embodiments can be applied at a radio transceiver device implemented both as a radio access network node and a terminal device, or even as a radio transceiver device implemented as a backhauling node or a sidelink node. Thus, although radio transceiver device 200a in at least some of the herein disclosed embodiments is described as being a network node and radio transceiver device 200b is described as being a terminal device, the functionality of the herein disclosed radio transceiver device 200a could equally be implemented in a terminal device, and vice versa for radio transceiver device 200b. For ease of notation, radio transceiver device 200a will hereinafter be denoted first radio transceiver device, and radio transceiver devices 200b will hereinafter be denoted second radio transceiver device 200b.

The first radio transceiver device 200a is, via TRP 300a, configured to communicate with radio transceiver device 200b in beams <NUM>, <NUM>. The beams collectively cover a network coverage region <NUM> of the first radio transceiver device 200a. The first radio transceiver device 200a could be configured to communicate using a variety of beams having different shapes and widths, herein generally referred to as having different beam patterns. It is envisioned that also the second radio transceiver device 200b might, via TRP 300b, be configured to communicate with radio transceiver device 200a in beams.

As disclosed above a beam management procedure might be performed in order to find a BPL for radio transceiver device 200a and radio transceiver device 200b. As further disclosed above, the beam management procedure disclosed above might result in some issues.

In further detail, with reference to <FIG>, as the distribution of served second radio transceiver devices 200b is typically not homogenously spread within the network coverage region <NUM> of the first radio transceiver device 200a, using the same beam widths for all wide beams of the first phase of the beam management procedure might not be optimal with respect to the total overhead required for the entire beam management procedure. For example, if one area of the network coverage region <NUM> is more densely populated with served second radio transceiver devices 200b compared to other areas of the network coverage region <NUM>, it could be beneficial to, in such directions, apply narrower beams during the first phase of the beam management procedure. In this way, fewer beams on average need to be evaluated during the second phase of the beam management procedure.

The embodiments disclosed herein therefore relate to mechanisms for determining beam settings for beam management. In order to obtain such mechanisms there is provided a radio transceiver device 200a, a method performed by the radio transceiver device 200a, a computer program product comprising code, for example in the form of a computer program, that when run on a radio transceiver device 200a, causes the radio transceiver device 200a to perform the method.

<FIG> is a flowchart illustrating embodiments of methods for determining beam settings for beam management. The methods are performed by the radio transceiver device 200a. The methods are advantageously provided as computer programs <NUM>. Continued reference is made to <FIG>.

The beam settings for at least some of the beams that are to be used during the actual beam management are based on information obtained by the first radio transceiver device 200a. Hence, the first radio transceiver device 200a is configured to perform step S102:
S102: The first radio transceiver device 200a obtains information about expected distribution of the second radio transceiver devices 200b in the network coverage region <NUM> of the first radio transceiver device 200a in which the beam management is to be performed.

The first radio transceiver device 200a then determines beam settings. Hence, the first radio transceiver device 200a is configured to perform step S104:
S104: The first radio transceiver device 200a determines beam settings for a first set of beams <NUM> and a second set of beams <NUM>. The first set of beams <NUM> and the second set of beams <NUM> are to be used for the beam management.

The beam settings are determined such that there are fewer beams in the first set of beams <NUM> than in the second set of beams <NUM>. This implies that there are at least some beams in the first set of beams <NUM> that are wider than the beams in the second set of beams <NUM>.

Further, the beam settings are determined such that the beams in the first set of beams <NUM> collectively cover all beams in the second set of beams <NUM>.

This does not exclude the possibility that there are additional beams that are not used during the beam management and that such additional beams thus are not collectively covered by the beams in the first set of beams <NUM>.

Further, the beam settings for the beams in the first set of beams <NUM> are determined according to the obtained information.

Embodiments relating to further details of determining beam settings for beam management as performed by the radio transceiver device 200a will now be disclosed.

In some aspects the first radio transceiver device 200a obtains information regarding the possible beam widths that can be generated. This information might include all from the widest possible beam width to the narrowest possible beam width that can be generated. In general terms, this information is fundamentally determined by the configuration and hardware limitations of the TRP 300a.

In some aspects the first radio transceiver device 200a obtains information regarding the angular area (sector size, horizontal and azimuth) that should be covered by the first radio transceiver device 200a. The angular area thus corresponds to the network coverage region <NUM> of the first radio transceiver device 200a in which the beam management is to be performed. This information is typically defined at deployment through cell planning or similar practice. The network coverage region <NUM> might, for example, be changed at certain occasions when, for example, densifying the network <NUM>, or if the network coverage region <NUM> for any other reason should be altered. Hence, according to an embodiment the beam settings for the beams in the first set of beams <NUM> are determined such that the beams in the second set of beams <NUM> collectively cover the network coverage region <NUM>. Further, according to an embodiment, the beam settings for the beams in the first set of beams <NUM> are determined based on the angular extension of the network coverage region <NUM>.

In some aspects the first radio transceiver device 200a obtains information regarding expected user density and traffic density in different parts of the network coverage region <NUM>. That is, according to an embodiment the obtained information further comprises information about expected traffic distribution of the second radio transceiver devices 200b in the network coverage region <NUM>.

There could be different ways to determine the beam widths of the beams in the first set of beams <NUM>.

In some aspects the parts of the network coverage region <NUM> with a comparatively high number of second radio transceiver devices 200b are covered by beams in the first set of beams <NUM> having narrower beam widths than those beams in the first set of beams <NUM> covering those parts of the network coverage region <NUM> with a comparatively low number of second radio transceiver devices 200b. Particularly, according to an embodiment the beam settings for the beams in the first set of beams <NUM> are determined such that the beams in the first set of beams <NUM> are more narrow in those parts of the network coverage region <NUM> having higher expected distribution of second radio transceiver devices 200b than in those parts of the network coverage region <NUM> having lower expected distribution of second radio transceiver devices 200b.

In some aspects the beam settings for the beams in the first set of beams <NUM> are determined with an aim to minimize the overhead signalling needed for the beam management. Particularly, according to an embodiment the beam settings for the beams in the first set of beams <NUM> are determined according to an optimization criterion. The optimization criterion pertains to minimal overhead signalling for the beam management.

In some aspects the beam settings for the first set of beams <NUM> are determined such that the probability that a second radio transceiver device 200b has its optimal narrow beam (i.e., a beam taken from the second set of beams <NUM>) in either one of them is equal. That is, according to an embodiment the beam settings for the beams in the first set of beams <NUM> are determined such that, according to the expected distribution of the second radio transceiver devices 200b, all beams in the first set of beams <NUM> have equal expected distribution of the second radio transceiver devices 200b. This means that beams from the first set of beams <NUM> covering parts of the network coverage region <NUM> with high expected user density and traffic density will be associated with as many beams from the second set of beams <NUM> as those beams from the first set of beams <NUM> covering parts of the network coverage region <NUM> with low expected user density and traffic density.

In some aspects the path gain is also considered when determining the beam settings for the first set of beams <NUM>. Hence, according to an embodiment the beam settings for the beams in the first set of beams <NUM> are determined based on path gain information of the second radio transceiver devices 200b. By taking the path gain into account the setting for the first set of beams <NUM> can be determined to avoid network coverage loss.

One way to obtain the information regarding expected user density and traffic density is to gather statistics over a period of time, and evaluate which parts of the the network coverage region <NUM> that has low expected user density and traffic density and which parts have high expected user density and traffic density. The statistics can be stored in a database to which the first radio transceiver device 200a has access. Hence, according to an embodiment the expected distribution of the second radio transceiver devices 200b in the network coverage region <NUM> is determined according to collected statistics.

There could be different ways to collect the statistics. According to an embodiment the statistics have been collected during previous beam management as performed by the first radio transceiver device 200a. According to another embodiment the statistics have been collected during previous communications of data and/or control signal between the first radio transceiver device 200a and the second radio transceiver devices 200b.

There could be different types of statistics that are collected in order to obtain the information regarding expected user density and traffic density. According to an embodiment the statistics pertain to location information of the second radio transceiver devices 200b in the network coverage region <NUM>. The location information might be defined by those beams having been used for communicating at least one of data and control signals with the second radio transceiver devices 200b in the network coverage region <NUM>.

One way to obtain the statistics is to log the average time each of the narrow beams (i.e., the beams in the second set of beams <NUM>) are used for data transmission. Particularly, according to an embodiment the statistics are collected by logging information about with how many second radio transceiver devices 200b each of the beams in the second set of beams <NUM> have been used for communicating at least one of data and control signalling.

Another way to obtain the information regarding expected user density and traffic density is to consider the scenario and the deployment. Particularly, according to an embodiment the information about expected distribution of the second radio transceiver devices 200b (and, optionally, the information about expected traffic distribution of the second radio transceiver devices 200b) is based on at least one of deployment information of the first radio transceiver device 200a and infrastructure information of the infrastructure in which the first radio transceiver device 200a is deployed. For example, in the illustrative example of <FIG>, if the upper half of the beam space points towards the sky whereas the lower half of the beam space points towards the ground, the expected user density and traffic density is most likely lower in the upper part than in the lower part. It could also be that a building is covering a certain part of the beam space and most of the traffic in the network coverage region <NUM> is expected to come from second radio transceiver devices 200b inside that building. In such scenarios the first set of beams <NUM> should be determined such as beams with narrower beam widths can be used in those directions with high expected user density and traffic density. Information of building databases can be obtained by supplying map information when deploying (possibly updating sometimes) or using cameras or other tools for assessing the view of structures in front of the TRP 300a of the first radio transceiver device 200a.

During the beam management, the first set of beams <NUM> should be used prior to the second set of beams <NUM>. That is, the first set of beams <NUM> might be used during the first phase of a beam management procedure whereas the second set of beams <NUM> might be used during a second (optional) phase of the beam management procedure (when needed).

There could be different types of beam management procedures. According to an embodiment, the first set of beams <NUM> are to be used for periodic beam management and the second set of beams <NUM> are to be used for aperiodic beam management. That is, the periodic beam management is achieved by performing the first phase of a beam management procedure and the aperiodic beam management is achieved by performing the second phase of a beam management procedure (when needed). The periodic beam management might be associated with long-term beam management and the aperiodic beam management might be associated with short-term beam management. In this respect, the aperiodic beam management might be performed more often (i.e., within shorter time intervals) than the periodic beam management.

Further, the first set of beams <NUM> can be used to determine a first approximate direction towards each respective second radio transceiver device 200b and the second set of beams <NUM> can be used to find a more exact direction towards each respective second radio transceiver device 200b and thus be used for data and/or control signalling.

Parallel reference will now be made to <FIG>, <FIG> illustrating examples of beams spaces.

<FIG> illustrates one example of a beam space 400b with a first set of beams <NUM> (all ellipses and circles with dotted lines) and one second set of beams <NUM> (all circles with solid lines). The beams <NUM>, <NUM> collectively cover a network coverage region <NUM> (dash-dotted line). In this example, low average traffic load (for example low average number of served second radio transceiver devices 200b per day) has been determined in the upper half of the beam space 400a, and hence the beam settings for the first set of beams <NUM> have been determined such that only one single wide beam is used to cover this part of the network coverage region <NUM>. Meanwhile, very high traffic load is determined in the lower left part of the beam space 400b, and hence the beam settings for the first set of beams <NUM> have been determined such that beams with comparably narrow beam width are used in this part of the network coverage region <NUM>.

When a second radio transceiver device 200b is detected in the large upper wide beam <NUM>, a total of <NUM> narrow beams <NUM> need to be evaluated during the second phase of the beam management procedure in order for the best narrow beam to be found. Further, if the second radio transceiver device 200b instead is located in one of the narrow beams <NUM> in the lower left corner only a total of <NUM> narrow beams <NUM> need to be evaluated during the second phase of the beam management procedure. Further, if the second radio transceiver device 200b instead is located in the medium wide beam <NUM> in the right lower corner, a total of <NUM> narrow beams <NUM> need to be evaluated during the second phase of the beam management procedure.

Thus, if the majority of the second radio transceiver devices 200b will be located in the lower left corner of the beam space 400b, while very few second radio transceiver devices 200b are located in the upper half of the beam space 400b, less overhead signaling during the second phase of the beam management procedure is required compared to the example in <FIG> (and hence also reduce the combined overhead for both beam management procedures). Assume for illustrative purposes that the signaling overhead cost of transmitting one beam is defined by one "beam resource". Assume further for illustrative purposes that the probability of a given second radio transceiver devices 200b being located in the upper wide beam <NUM> is <NUM>/<NUM>, that the probability of the given second radio transceiver devices 200b being located in each of the narrow lower left beams <NUM> is <NUM>/<NUM> each, and that the probability of the given second radio transceiver devices 200b being located in the middle lower right beam <NUM> is <NUM>/<NUM>. Then, in order to find the best narrow beam <NUM>, <NUM> beam resources are needed for the first phase of the beam management procedure (one for each wide beam <NUM>), and on average <NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM> beam resources are needed for the second phase of the beam management procedure. Hence, the total average number of beam resources needed in order for the best narrow beam <NUM> to be found is <NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM> = <NUM>. In comparison, if equal sized coarse beams would be used in the first set of beams, as indicated in <FIG>, an average of <NUM> beam resources would have been needed.

<FIG> illustrates another example of a beam space 400c with a first set of beams <NUM> (all ellipses and circles with dotted lines) and one second set of beams <NUM> (all circles with solid lines). The beams <NUM>, <NUM> collectively cover a network coverage region <NUM> (dash-dotted line). In this example the first set of beams <NUM> has <NUM> beams. <FIG> is an example of an embodiment where at least one, but less than all, of the beams in the first set of beams <NUM> covers only a single beam in the second set of beams <NUM>. In this example most of the traffic is expected be located in the lower left corner of the beam space 400c, whereas least amount of traffic is expected in the upper half of the beam space 400c. In the lower left corner the beam width of <NUM> beams of the first set of beams <NUM> is just slightly larger (or even of the same size) as the beams of the second set of beams <NUM>. That is, in the lower left corner there is a one-to-one correspondence between the beams of the first set of beams <NUM> and the beams of the second set of beams <NUM>. Hence, whenever one of these <NUM> beams of the first set of beams <NUM> is determined to be the best during the first phase of the beam management procedure, there is no need to perform the second phase of the beam management procedure to find the best beam in the second set of beams <NUM>. In case most of the traffic will be located in those directions, this will reduce the overhead signaling for the overall beam management.

<FIG> illustrates yet another example of a beam space 400d with a first set of beams <NUM> (all ellipses and circles with dotted lines) and one second set of beams <NUM> (all circles with solid lines). The beams <NUM>, <NUM> collectively cover a network coverage region <NUM> (dash-dotted line). <FIG> is an example of an embodiment where two beams in the first set of beams <NUM> having same beam width each covers a respective subset of the beams in the second set of beams <NUM>, and where the respective subsets have mutually different number of beams. In this example the first set of beams <NUM> are distributed as in the beam space 400b of <FIG>, but the second set of beams <NUM> are distributed differently. In more detail, in the wide beam <NUM> in the lower left corner there are <NUM> narrow beams <NUM>, whereas in the wide beam <NUM> next to the lower left corner (of same beam width as the wide beam <NUM> in the lower left corner) there are <NUM> narrow beams <NUM>. Thus, the narrow beams are distributed in a finer granularity, which allows for oversampling. Such oversampling may increase the received beamforming gain, and hence the individual link budget between the first radio transceiver device 200a and the second radio transceiver device 200b. In this case, there is a tradeoff between the number of beam resources spent and the resulting link budget (antenna gain) used for data and/or control signalling. Using the same probabilities as in the calculation example in <FIG>, the average beam resource utilization is <NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM>+<NUM>/<NUM>·<NUM> = <NUM>, which is still less than the example in <FIG> and results in a better link performance (with the assumed distribution of second radio transceiver devices 200b in <FIG>).

<FIG> illustrates yet another example of a beam space 400e with a first set of beams <NUM> (all ellipses and circles with dotted lines) and one second set of beams <NUM> (all circles with solid lines). The beams <NUM>, <NUM> collectively cover a network coverage region <NUM> (dash-dotted line). <FIG> is an example of an embodiment where at least two of the beams in the first set of beams <NUM> cover one common beam in the second set of beams <NUM>. In this example also the distribution of the beams in the angular domain depends on the distribution of the second radio transceiver devices 200b. For example in angular directions with many second radio transceiver devices 200b the wide beams <NUM> are more densely spaced compared to angular directions with lower density of second radio transceiver devices 200b. In the beam space 400e of <FIG> there are <NUM> wide beams <NUM> of equal size in the lower left that partly overlap with each other and thus some of the narrow beams <NUM> are covered by two wide beams <NUM>.

In some aspects the first radio transceiver device 200a performs the actual beam management procedure. Particularly, according to an embodiment the first radio transceiver device 200a is configured to perform (optional) step S106:
S106: The first radio transceiver device 200a performs the beam management.

Embodiments relating to different ways for the first radio transceiver device 200a to perform the beam management will now be disclosed.

In some aspects the beam management is for determining a transmit beam. The first radio transceiver device 200a is then configured to perform (optional) step S106aa:
S106aa: The first radio transceiver device 200a transmits, towards the second radio transceiver devices 200b, at least one occurrence of a reference signal in each of the beams in the first set of beams <NUM>.

It is assumed that the second radio transceiver device 200b reports back to the first radio transceiver device 200a at least the beam having been received with highest received power. Hence in this embodiment the first radio transceiver device 200a is then further configured to perform (optional) step S106ab:.

In scenarios where the identified beam in the first set of beams <NUM> covers at least two beams in the second set of beams <NUM> also a second phase of the beam management is performed. Hence, according to this embodiment the first radio transceiver device 200a is configured to perform (optional) step S106ac:
S106ac: The first radio transceiver device 200a transmits, towards at least some of the second radio transceiver devices 200b, at least one occurrence of the reference signal in each of those beams in the second set of beams <NUM> that are covered by the beam in the first set of beams <NUM> being identified in the respective first reports.

It is assumed that the second radio transceiver device 200b reports back to the first radio transceiver device 200a at least the beam having been received with highest received power. Hence in this embodiment the first radio transceiver device 200a is then further configured to perform (optional) step S106ad:
S106ad: The first radio transceiver device 200a receives, from the at least some of the second radio transceiver devices 200b, a respective second report identifying at least that beam in the second set of beams <NUM> having been received with highest received power at that second radio transceiver device. That beam in the second set of beams <NUM> then defines the transmit beam.

In scenarios where the identified beam in the first set of beams <NUM> covers only a single beam in the second set of beams <NUM> the second phase of the beam management (as defined by steps S106ac and S106ad) needs not to be performed. Particularly, according to an embodiment, when the identified beam in the first set of beams <NUM> having been received with highest received power at at least one of the second radio transceiver devices 200b covers only a single beam in the second set of beams <NUM>, the identified beam defines the transmit beam.

The first radio transceiver device 200a can then use the transmit beam during subsequent transmission of data and/or control signalling towards the second radio transceiver device 200b.

In some aspects the beam management is for determining a receive beam. The first radio transceiver device 200a might then be configured to perform (optional) step S106ba:.

The first radio transceiver device 200a then determines in which of the beams in the first set of beams <NUM> the reference signal was received with highest received power.

In scenarios where the identified beam in the first set of beams <NUM> covers at least two beams in the second set of beams <NUM> also a second phase of the beam management is performed. Hence, according to this embodiment the first radio transceiver device 200a is configured to perform (optional) step S106bb:
S106bb: The first radio transceiver device 200a receives from this one of the second radio transceiver devices 200b (i.e., the same second radio transceiver device 200b as in step S106ba), at least one occurrence of the reference signal in each of those beams in the second set of beams <NUM> that are covered by the beam in the first set of beams <NUM> being identified in the first report.

In scenarios where the identified beam in the first set of beams <NUM> covers only a single beam in the second set of beams <NUM> the second phase of the beam management (as defined by step S106bb) needs not to be performed. Particularly, according to an embodiment, when the identified beam in the first set of beams <NUM> having been received with highest received power covers only a single beam in the second set of beams <NUM>. The identified beam then defines the receive beam.

The first radio transceiver device 200a can then use the receive beam during subsequent reception of data and/or control signalling from the second radio transceiver device 200b.

Further, in some aspects, regardless if the beam management is for determining a transmit beam or a receive beam, the thus defined transmit beam or receive beam might then be used for both transmission of signals to the second radio transceiver device 200b and reception of signals from the second radio transceiver device 200b.

One particular embodiment of a method for determining beam settings for beam management (and performing the beam management) based on at least some of the above disclosed embodiment will now be disclosed with reference to the signalling diagram of <FIG>.

S201: The first radio transceiver device 200a obtains information of possible beam widths that can be generated at the TRP 300a.

S202: The first radio transceiver device 200a obtains information regarding expected user density and traffic density in different parts of the beam space, where the beam space is defined by the network coverage region <NUM> of the first radio transceiver device 200a in which the beam management is to be performed.

S203: The first radio transceiver device 200a determines settings for the second (narrow) set of beams <NUM> intended for use in the second phase of the beam management procedure, and for later data and/or control signalling. The settings are determined such that the second set of beams <NUM> are distributed in such a fashion (in angular domain) to cover the whole network coverage region <NUM> intended to be served. This is similar to generation a codebook of all possible transmit beams that may be needed when serving users.

S204: The first radio transceiver device 200a determines beam settings for the first set of beams <NUM> to be used for the first phase of the beam management procedure, for example during a periodic TX beam sweep, based on the information gathered in step S202.

S205: The first radio transceiver device 200a transmits reference signals (such as CSI-RS or SSB) in the first phase of the beam management procedure using the first set of beams <NUM>.

S206: The second radio transceiver device 200b measures power on the received reference signals.

S207: The second radio transceiver device 200b signals back to the first radio transceiver device 200a at least the beam in the first set of beams <NUM> having been received with highest received power.

S208: The first radio transceiver device 200a selects which beams in the second set of beams <NUM> to use during the second phase of the beam management procedure based on the report received from the second radio transceiver device 200b.

S209: The first radio transceiver device 200a transmits reference signals in the second phase of the beam management procedure using the second set of beams <NUM>. The reference signal is only transmitted in those beams in the second set of beams that correspond to the reported beam in the first set of beams <NUM> (i.e. the beam having been received with highest received power) in order to find the best narrow beam for the second radio transceiver device 200b.

S210: The second radio transceiver device 200b measures power on the received reference signals.

S110: The second radio transceiver device 200b signals back to the first radio transceiver device 200a at least the beam in the second set of beams <NUM> having been received with highest received power.

The reported beam in the second set of beams <NUM> can then be used by the first radio transceiver device 200a for subsequent data and/or control signalling towards the second radio transceiver device 200b.

It is noted that although the beam management has been described as comprising a first phase and an optional second phase (wherein whether or not to perform the second phase depends on the amount of beams in the second set of beams <NUM> covered by the beam in the first set of beams <NUM> selected during the first phase) the beam management can be extended to comprise also a third phase where even more narrow beams than in the second set of beams <NUM> are evaluated for the beam in the second set of beams <NUM> selected during the second phase, and so on.

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

Particularly, the processing circuitry <NUM> is configured to cause the radio transceiver device 200a to perform a set of operations, or steps, as disclosed above. For example, the storage medium <NUM> may store the set of operations, and the processing circuitry <NUM> may be configured to retrieve the set of operations from the storage medium <NUM> to cause the radio transceiver device 200a to perform the set of operations.

Thus the processing circuitry <NUM> is thereby arranged to execute methods as herein disclosed. The radio transceiver device 200a may further comprise a communications interface <NUM> at least configured for communications with other radio transceiver devices 200b. As such the communications interface <NUM> may comprise one or more transmitters and receivers, comprising analogue and digital components.

Signals, such as reference signals as well as data and control signals, could be transmitted from, and received by, a TRP 300a of the radio transceiver device 200a. The TRP 300a could form an integral part of the radio transceiver device 200a or be physically separated from the radio transceiver device 200a. The communications interface <NUM> might thus optionally comprise the TRP 300a.

The processing circuitry <NUM> controls the general operation of the radio transceiver device 200a e.g. by sending data and control signals to the communications interface <NUM> and the storage medium <NUM>, by receiving data and reports from the communications interface <NUM>, and by retrieving data and instructions from the storage medium <NUM>. Other components, as well as the related functionality, of the radio transceiver device 200a are omitted in order not to obscure the concepts presented herein.

<FIG> schematically illustrates, in terms of a number of functional modules, the components of a radio transceiver device 200a according to an embodiment. The radio transceiver device 200a of <FIG> comprises a number of functional modules; an obtain module 210a configured to perform step S102, and a determine module 210b configured to perform step S104.

The radio transceiver device 200a of <FIG> may further comprise a number of optional functional module <NUM>, such as any of a beam management module 210c configured to perform step S106, a transmit module 210d configured to perform step S106aa, a receive module 210e configured to perform step S106ab, a transmit module 210f configured to perform step S106ac, a receive module <NUM> configured to perform step S106ad, a receive module <NUM> configured to perform step S106ba, and a receive module 210i configured to perform step S106bb.

In general terms, each functional module 210a-210i may in one embodiment be implemented only in hardware and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium <NUM> which when run on the processing circuitry makes the radio transceiver device 200a perform the corresponding steps mentioned above in conjunction with <FIG>. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used. Preferably, one or more or all functional modules 210a-210i may be implemented by the processing circuitry <NUM>, possibly in cooperation with the communications interface <NUM> and/or the storage medium <NUM>. The processing circuitry <NUM> may thus be configured to from the storage medium <NUM> fetch instructions as provided by a functional module 210a-210i and to execute these instructions, thereby performing any steps as disclosed herein.

The radio transceiver device 200a may be provided as a standalone device or as a part of at least one further device. For example, the radio transceiver device 200a may be provided in a node of the radio access network or in a node of the core network. Alternatively, functionality of the radio transceiver device 200a may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the radio access network or the core network) or may be spread between at least two such network parts.

Thus, a first portion of the instructions performed by the radio transceiver device 200a may be executed in a first device, and a second portion of the of the instructions performed by the radio transceiver device 200a may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the radio transceiver device 200a may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a radio transceiver device 200a residing in a cloud computational environment. Therefore, although a single processing circuitry <NUM> is illustrated in <FIG> the processing circuitry <NUM> may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 210a-210i of <FIG> and the computer program <NUM> of <FIG> (see below).

Claim 1:
A method for determining beam settings for beam management, the method being performed by a first radio transceiver device (200a), the method comprising:
obtaining (S102) information about expected distribution of second radio transceiver devices (200b) in a network coverage region (<NUM>) of the first radio transceiver device (200a) in which the beam management is to be performed; and
determining (S104) beam settings for a first set of beams (<NUM>) and a second set of beams (<NUM>), wherein the first set of beams (<NUM>) and the second set of beams (<NUM>) are to be used for the beam management,
wherein there are fewer beams in the first set of beams (<NUM>) than in the second set of beams (<NUM>),
wherein the beams in the first set of beams (<NUM>) collectively cover all beams in the second set of beams (<NUM>),
wherein for at least two of the beams in the first set of beams (<NUM>) the respective numbers of beams in the second set of beams (<NUM>) covered by each of the at least two beams in the first set of beams are unequal, and
wherein the beam settings for the beams in the first set of beams (<NUM>) are determined according to the obtained information.