EP3954054A1

EP3954054A1 - Beamforming in a radio communication network

Info

Publication number: EP3954054A1
Application number: EP19923993.0A
Authority: EP
Inventors: Anders FURUSKÄR; Niklas JALDÉN
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2019-04-12
Filing date: 2019-04-12
Publication date: 2022-02-16
Also published as: WO2020209769A1

Abstract

A method for beamforming in a radio communication network is presented. The method is performed in a network node (2, 3) of a radio communication network. The method comprises obtaining (S210) a regulatory restriction information conflicting with an effective radiated power in a first direction from a base station, BS, (2) of the radio communication network, and adjusting (S220) a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information, wherein the second direction differs from the first direction. A method, a network node, a user equipment, computer program products, and a computer program product for beamforming in a radio communication network are also presented.

Description

BEAMFORMING IN A RADIO COMMUNICATION NETWORK

TECHNICAL FIELD

[0001] The present disclosure relates to methods, a network node, a user equipment, computer programs, and a computer program product for beamforming in a radio communication network.

BACKGROUND

[0002] In wireless communication system, transmissions between one node and another node are typically subjected to multipath propagation. In other words, signals from transmitter (Tx) to receiver (Rx) do not travel in a single straight path, but are reflected, scattered and diffracted by various objects, and can hence arrive at the Rx from a multitude of directions, each direction with its own power and delay.

[0003] However, signals typically arrive from limited directions in space one channel between one Tx and one Rx, and current and future communication systems can employ multiple antennas at both Tx and Rx to allow for steering of the radiated power towards the intended users. This technique is commonly called beamforming or precoding. Beamforming will allow for increasing received Signal to Interference plus Noise Ratio (SINR) without increasing the overall transmitted power. Transmit beamforming requires knowledge, at the transmit side, of the radio channel between the transmitter and receiver. This can be obtained by transmitting known reference symbols over the channel, and estimating the channel based on how the reference symbols have been affected by the channel when they reach the receiver. This is known as channel feedback. Assuming the channel is reciprocal, i.e. the same channel in both directions, the reference symbols can also be sent by the data receiver to the data transmitter, which then estimates the channel. When the same frequency is used for downlink and uplink, which is typical for Time Division Duplex (TDD), the channel is fully reciprocal, including fast fading. When different frequencies are used for the different directions, which is typical for Frequency Division Duplex (FDD), the channel may still be reciprocal on a higher level, including main directions of arrival or departure.

[0004] For Electro Magnetic Field (EMF) exposure reasons and for Electro Magnetic Compatibility (EMC) reasons, there are in most parts of the world, limits on the maximum effective (or equivalent) isotropic radiated power (EIRP). These limits differ from band to band and between different regions in the world. As an example, in the 5.15-5.25GHZ band for fixed point-to-point access, the maximum power spectral density shall not exceed 17 dBm in any i-megahertz band. Other examples with limited radiated power are the Citizens Broadband Radio Service (CBRS) band in the United States.

SUMMARY

[0005] One objective is to increase maximum radiated power in a radio communication network, still following legal limitations.

[0006] According to a first aspect there is presented a method for beamforming in a radio communication network. The method is performed in a network node of a radio communication network. The method comprises obtaining a regulatory restriction information conflicting with an effective radiated power in a first direction from a base station (BS) of the radio communication network, and adjusting a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information. The second direction differs from the first direction.

[0007] By the presented method system performance in the radio

communication network is increased, while still following the legal limitations. System performance that are increased may be capacity, coverage and user throughput.

[0008] In a single-user case, the received power is increased at the receiver, which in turn improves signal quality (e.g. signal to noise and interference ratio). This directly improves user throughput and coverage in the radio communication network, but also capacity as less radio resources are required to transfer a given amount of data.

[0009] In multi-user transmissions, the total radiation power is utilized, wherein otherwise unutilized power through EIRP back off is used for serving additional users in the radio communication network.

[0010] The adjusting may comprise reducing the effective radiated power in the first direction to meet the regulatory restriction information, and increasing the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power in the first direction.

[oon] The increasing may comprise increasing the effective radiated power in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power in the first direction. The third direction differs from the first and second directions.

[0012] The increasing may comprise increasing the effective radiated power in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power.

[0013] The regulatory restriction information may be defined by one or more of the following: EIRP, EMF, EMC, and ICNIRP.

[0014] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

[0015] The method may further comprise receiving beamforming information for a user equipment (UE), for beamforming generation in the first direction. The second direction may be a secondary path to the UE. The second direction may be to a secondary UE (UA_B).

[0016] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

[0017] According to a second aspect there is presented a method for

beamforming in a radio communication network. The method is performed in a UE in a radio communication network. The method comprises obtaining a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE, and adjusting a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction. [0018] The adjusting may comprise reducing the effective radiated power in the first direction to meet the regulatory restriction information, and increasing the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

[0019] The regulatory restriction information may be defined by SAR.

[0020] The the adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

[0021] The method may further comprise measuring a signal quality, for beamforming generation in the first direction.

[0022] The second direction may be a secondary path to a BS.

[0023] The second direction may be to a secondary BS.

[0024] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

[0025] According to a third aspect there is presented a network node for beamforming in a radio communication network. The network node comprises a processing circuitry and a computer program product storing instructions. The stored instructions, when executed by the processing circuitry, causes the network node to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a BS in a radio communication network, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[0026] The relative radiated power may be adjusted and cause the network node to reduce the effective radiated power in the first direction to meet the regulatory restriction information, and to increase the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power. [0027] The effective radiated power may be increased in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power. The third direction differs from the first and second directions.

[0028] The effective radiated power may be increased in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power.

[0029] The regulatory restriction information may be defined by one or more of the following: EIRP, EMF, EMC, and ICNIRP.

[0030] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

[0031] The network node may further be caused to receive beamforming information for a UE for beamforming generation in the first direction.

[0032] The second direction may be a secondary path to the UE.

[0033] The second direction may be to a secondary UE.

[0034] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

[0035] According to a fourth embodiment there is presented a user equipment for beamforming in a radio communication network. The UE comprises a

processing circuitry and a computer program product storing instructions. The stored instructions, when executed by the processing circuitry, causes the UE to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction. [0036] The relative effective radiated power may be adjusted causing the UE to reduce the effective radiated power in the first direction to meet the regulatory restriction information, and to increase the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

[0037] The regulatory restriction information may be defined by SAR.

[0038] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

[0039] The UE may further be caused to measure a signal quality, for beamforming generation in the first direction.

[0040] The second direction may be a secondary path to a BS.

[0041] The second direction may be to a secondary BS.

[0042] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

[0043] According to a fifth aspect there is presented a computer program for beamforming in a radio communication network. The computer program comprises computer program code which, when run in a network node of a radio

communication network, causes the network node to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a BS of the radio communication network, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information, wherein the second direction differs from the first direction.

[0044] According to a sixth aspect there is presented a computer program for beamforming in a radio communication network. The computer program

comprising computer program code which, when run in a UE of a radio

communication network, causes the UE to obtain a regulatory restriction

information conflicting with an effective radiated power in a first direction from the UE, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[0045] A computer program product comprising a computer program and a computer readable storage means on which the computer program is stored is also presented.

[0046] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which:

[0048] Fig. 1 shows a diagram schematically illustrating a setup wherein embodiments presented herein can be applied;

[0049] Figs. 2 and 3 are flowcharts schematically illustrating embodiments of methods as presented herein;

[0050] Fig. 4 is a diagram schematically illustrating a secondary path between a UE and a BS;

[0051] Fig. 5 is a diagram schematically illustrating EIRP aware BF;

[0052] Fig. 6 is a diagram schematically illustrating communication also with a secondary UE;

[0053] Figs. 7 and 8 are diagrams schematically illustrating beamshapes of base stations;

[0054] Figs. 9 and 10 are diagrams schematically illustrating some components of devices presented herein; and [0055] Figs. 11 and 12 are diagrams schematically illustrating functional modules of devices presented herein.

DETAILED DESCRIPTION

[0056] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown.

[0057] These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0058] To comply with legal limitations, such as effective isotropic radiated power (EIRP) limitations, the radiated power is typically backed off to not exceed the legal limits. This back-off is typically set such that the max power in the strongest direction is below the limits, which hence also impacts other directions, not exceeding the legal limitations as well, which is sub-optimal from a

communication perspective.

[0059] However, given information of spatial directions intended for a user together with information of directions to avoid, due to regulatory restrictions, it is possible to create a precoder that fulfils certain criterions. One way to do this with knowledge of the spatial information of a channel between a base station (BS), such as a next generation NodeB (gNB), and a user equipment (UE), for example the covariance information at the transmitter in the gNB, is to use beamforming (i.e. precoding vector) corresponding to the eigenvector corresponding to the strongest or largest eigenvalue of the covariance matrix R. On the other hand, to maximize the received power s = w^HRw at the UE while minimizing the transmissions q = w^HQw in EIRP limited directions (assuming that the spatial information (direction) of the EIRP is represented by the interference covariance matrix Q = a₀I + å_n a_nQ_n, where / is the identity matrix and a_n for n = 0,2,1, ..., N are scaling factors, if certain direction require higher or lower level of suppression) the signal can be

beamformed using a weight vector v corresponding to the eigenvector w (for corresponding eigenvalue l ) maximizing the generalized eigenvalue problem [0060] Rw = AQw

[0061] The eigenvector w_t corresponding to the largest eigenvalue A_t will be a beam that maximizes the ratio s/q.

[0062] Fig. 1 illustrates an environment wherein embodiments presented herein can be implemented. A user equipment (UE) 1, is in connectivity with a base station (BS) 2, in turn connected to a core network (CN) 3, all being part of a radio communication network. The CN 3 may in turn be connected to Internet 4.

[0063] According to an aspect, an embodiment of a method for beamforming in a radio communication network is presented with reference to Fig. 3. The method is performed in a network node 2, 3 of a radio communication network. In processing block S210 a regulatory restriction information is obtained conflicting with an effective radiated power in a first direction from a BS 2 of the radio communication network. In processing block S220 a relative effective radiated power is adjusted between the effective radiated power in the first direction and an effective radiated power in second direction from the BS, to meet the obtained regulatory restriction information. The second direction differs from the first direction. The network node may by a BS 2 or a CN 3 of the radio communication network.

[0064] Processing block S220 may comprise sub processing blocks S22oa and S22ob. In processing block S22oa the effective radiated power is reduced in the first direction to meet the regulatory restriction information. In processing block S22ob the effective radiated power is increased in the second direction with an effective radiated power of up to the reduced effective radiated power in the first direction. In processing block S22ob the effective radiated power may in an embodiment be increased in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power in the first direction, wherein the third direction differs from the first and second directions. In

processing block S22ob the effective radiated power may in another embodiment be increased in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power. The regulatory restriction information may be considered also for the second direction.

[0065] The regulatory restriction information may be defined by one or more of the following: EIRP, Electro Magnetic Field (EMF), Electro Magnetic Compatibility (EMC), and International Commission on Non-Ionizing Radiation Protection (ICNIRP).

[0066] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

[0067] The method may further comprise processing block S200 before processing block S210. In processing block S200 beamforming information for a user equipment UEA is received, for beamforming generation in the first direction. The second direction may in an embodiment be a secondary path to the user equipment UEA. The second direction may in another embodiment be a secondary user equipment UEB.

[0068] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

[0069] A certain effective radiated power may be an instantaneous power (at any time) or an average transmitted power over a certain period, over a certain frequency range, or a combination of thereof.

[0070] According to an aspect, a method for beamforming in a radio

communication network is presented with reference to Fig. 2. The method is performed in a UE 1 in a radio communication network. In processing block S110 a regulatory restriction information is obtained conflicting with an effective radiated power in a first direction from the UE. In processing block S120 a relative effective radiated power is adjusted between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[oo7i]Processing block S120 may comprise processing blocks Si2oa and Si2ob. In processing block Si2oa the effective radiated power in the first direction is decreased to meet the regulatory restriction information. In processing block Si2ob the effective radiated power in the second direction is increased with an effective radiated power of up to the reduced effective radiated power.

[0072] The regulatory restriction information may be defined by Specific Absorption Rate (SAR).

[0073] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

[0074] The method may further comprise processing block S100 before process block S110. In processing block S100 a signal quality is measured, for beamforming generation in the first direction.

[0075] The second direction may be a secondary path to a BS 2.

[0076] The second direction may be to a secondary BS (not illustrated).

[0077] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

[0078] A certain effective radiated power may be an instantaneous power (at any time) or an average transmitted power over a certain period, over a certain frequency range, or a combination of thereof.

[0079] The operations shown in Figs. 2 and 3 will now be illustrated and described in more detail in conjunction with Figs. 4-8.

[0080] During beamforming, both cell- and UE-specific considerations may be taken. A base station may be supplied with information of regulatory restrictions. Further, in cases where there is an average EIRP limitation over a certain time period, and over a certain band, the base station logs previously used beamforming weights, for a period of at least the same length as the average limitation (or other representation of spatially radiated power).

[0081] In an embodiment, presented with reference to Fig. 4, EIRP limitations are such that the average transmitted power over a certain period of time in a certain direction may not exceeded a certain threshold. Previous transmissions are such that this threshold has already been reached (or being close to be reached) for a direction which coincided with the direction to UEA. Given knowledge of this limitation, the beamforming is done for UEA such that alternative paths are used. Hence, UEA is served over other (potentially suboptimal) paths, allowing data transmissions, when still following regulatory limitations. This is also illustrated in Fig. 5, wherein two propagation paths reach the BS. The left path is the direct path and the right is the secondary path. Fig. 5 shows the beam shapes that may be used without the presented beamforming (Baseline) and when taking the EIRP limitations into account (EIRP aware beamforming (BF)). As noted, the baseline beamforming would direct the most energy in the direction where EIRP limitations exist, whereas the presented beamforming redirects most of the signal power over the secondary path.

[0082] In an embodiment, presented with reference to Fig. 6, a BS intends to transmit data to UE_A. Due to an existing instantaneous EIRP limitation, the BS is not allowed to transmit at full power in the direction towards UE_A. Hence, the remainder of the power is used to send data to UE_B, which is served in a second direction, not impacting radiations in the limited direction. The resulting total radiated power thus may be similar to the plot shown in Fig. 5. The scheduling of UEs may here be based on a proportional fair metric.

[0083] In another embodiment, a BS stores information of information of spatial averages used for beamforming. Further information is stored if the EIRP limitations are exceeded (risk of exceeding) during certain periods of time during the day. If a UE enters the system, requesting transmissions, where one of the main directions for BF to that UE coincides with a direction that is typically subject to power reductions due to EIRP limitations, the BS utilized a secondary path (when available and deemed sufficient), in preventive cause, to save the energy for a possible later transmission that does not have a possible secondary path.

[0084] In yet another embodiment, with several UEs competing for power in the same EIRP limited direction, a subset of UEs that are transmitted to in this best direction is selected, and the other UEs are transmitted to in suboptimal directions. The subsets are selected based on quality of service (QoS) requirements.

[0085] In a further embodiment, the situation illustrated in Fig. 4 has occurred due to that the best signal path to the user equipment UEA has been used for long enough to risk breaking the EIRP restrictions. The base station BS can continue to transmit to UE_A, but on a secondary, second best path. This can be continued for several paths.

[0086] Figs. 7 and 8 illustrate two examples wherein the effective radiated power is reduced from a first direction between a BS and a UE UE_A. The dashed area is the pattern that the BS may generate, not considering EIRP restrictions. The dashed semi-circle illustrates the EIRP limitation for the BS.

[0087] Fig. 7 illustrates, in a solid beamshape, how an overall power back off would be (per frequency resource),

[0088] Fig. 8 illustrate, in a solid beamshape, how the reduced effective radiated power towards UE_A is instead used to increase the effective radiated power towards UE_B. Also, no part of the beamshape violates the EIRP restriction.

[0089] According to an aspect a user equipment for beamforming in a radio communication network is presented with reference to Fig. 9. The UE 1 comprises a processing circuitry 10 and a computer program product 12, 13 storing instructions 14, 15 that, when executed by the processing circuitry, causes the UE to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[0090] The relative effective radiated power may be adjusted causing the UE to reduce the effective radiated power in the first direction to meet the regulatory restriction information, and to increase the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

[0091] The regulatory restriction information may be defined by SAR.

[0092] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

[0093] The UE may further be caused to measure a signal quality, for beamforming generation in the first direction. [0094] The second direction may a secondary path to a BS 2.

[0095] The second direction may in another embodiment be to a secondary BS (not illustrated).

[0096] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

[0097] Fig. 9 is a schematic diagram showing some components of the UE 1. The processing circuitry 10 may be provided using any combination of one or more of a suitable central processing unit, CPU, multiprocessing circuitry,

microcontroller, digital signal processing circuitry, DSP, application specific integrated circuit etc., capable of executing software instructions of a computer program 14 stored in a memory. The memory can thus be considered to be or form part of the computer program product 12. The processing circuitry 10 maybe configured to execute methods described herein with reference to Fig. 2.

[0098] The memory may be any combination of read and write memory, RAM, and read only memory, ROM. The memory may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0099] A second computer program product 13 in the form of a data memory may also be provided, e.g. for reading and/or storing data during execution of software instructions in the processing circuitry 10. The data memory can be any combination of read and write memory, RAM, and read only memory, ROM, and may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The data memory may e.g. hold other software instructions 15, to improve functionality for the UE 1.

[00100] The UE 1 may further comprise an input/ output (1/ O) interface 11 including e.g. a user interface. The UE 1 may further comprise a receiver configured to receive signalling from other nodes, and a transmitter configured to transmit signalling to other nodes (not illustrated). Other components of the UE 1 are omitted in order not to obscure the concepts presented herein.

[00101] According to an aspect, an embodiment of a UE 1 for beamforming in a radio communication network is presented with reference to Fig. 11. The UE 1 comprises an obtaining manager 80 for obtaining a regulatory restriction

information conflicting with an effective radiated power in a first direction from the UE. The UE 1 also comprises a determination manager 81 for adjusting a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[00102] Fig. 11 is a schematic diagram showing functional blocks of the UE 1. The modules may be implemented as only software instructions such as a computer program executing in the cache server or only hardware, such as application specific integrated circuits, field programmable gate arrays, discrete logical components, transceivers, etc. or as a combination thereof. In an alternative embodiment, some of the functional blocks maybe implemented by software and other by hardware. The modules correspond to the steps in the method illustrated in Fig. 2, comprising an obtaining manager unit 80 and a determination manger unit 81. In the embodiments where one or more of the modules are implemented by a computer program, it shall be understood that these modules do not necessarily correspond to process modules, but can be written as instructions according to a programming language in which they would be implemented, since some programming languages do not typically contain process modules.

[00103] The obtaining manager 80 is for beamforming in the radio

communication network. This module corresponds to the processing block S110 of Fig. 2. This module can e.g. be implemented by the processing circuitry 10 of Fig. 9, when running the computer program.

[00104] The determining manger 81 is for beamforming in the radio

communication network. This module corresponds to the processing blocks S100, S120, Si2oa, and Si2ob of Fig. 2. This module can e.g. be implemented by the processing circuitry 10 of Fig. 9, when running the computer program. [00105] According to an aspect, an embodiment of a computer program 14, 15 for beamforming in a radio communication network is presented with reference to Fig. 9. The computer program comprises computer program code which, when run in a UE 1 of a radio communication network, causes the UE to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[00106] According to an aspect, a network node for beamforming in a radio communication network is presented with reference to Fig. 10. The network node 3 comprises a processing circuitry 30 and a computer program product 32, 33 storing instructions 34, 35 that, when executed by the processing circuitry, causes the network node to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a BS 2 in a radio communication network, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[00107] The network node has been illustrated as being part of CN 3, but may in another embodiment be part of BS 2.

[00108] The relative radiated power may be adjusted and cause the network node to reduce the effective radiated power in the first direction to meet the regulatory restriction information, and to increase the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

[00109] The effective radiated power may be increased in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power, wherein the third direction differs from the first and second directions. [00110] The effective radiated power may in another embodiment be increased in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power.

[00111] The regulatory restriction information may be defined by one or more of the following: EIRP, EMF, EMC, and ICNIRP.

[00112] The adjusted effective radiated power may be determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

[00113] The network node 2, 3 may further be caused to receive beamforming information for a UE 1 for beamforming generation in the first direction. The second direction may be a secondary path to the UE. The second direction may in another embodiment be to a secondary UE UE_B.

[00114] The regulatory restriction information may indicate an average effective radiated power over a period of time, and the effective radiated power may be reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

[00115] According to an aspect, an embodiment of a network node 2, 3 for beamforming in a radio communication network is presented with reference to Fig. 12. The network node 2, 3 comprises an obtaining manager 90 for obtaining a regulatory restriction information conflicting with an effective radiated power in a first direction from a BS 2. The network node 2, 3 also comprises a determination manager 91 for adjusting a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the regulatory restriction information, wherein the second direction differs from the first direction.

[00116] Fig. 12 is a schematic diagram showing functional blocks of the network node 2, 3. The modules maybe implemented as only software instructions such as a computer program executing in the cache server or only hardware, such as application specific integrated circuits, field programmable gate arrays, discrete logical components, transceivers, etc. or as a combination thereof. In an alternative embodiment, some of the functional blocks may be implemented by software and other by hardware. The modules correspond to the steps in the method illustrated in Fig. 3, comprising an obtaining manager unit 90 and a determination manger unit 91. In the embodiments where one or more of the modules are implemented by a computer program, it shall be understood that these modules do not necessarily correspond to process modules, but can be written as instructions according to a programming language in which they would be implemented, since some

programming languages do not typically contain process modules.

[00117] The obtaining manager 90 is for beamforming in the radio

communication network. This module corresponds to the processing block S210 of Fig. 3. This module can e.g. be implemented by the processing circuitry 30 of Fig.

10, when running the computer program.

[00118] The determining manger 91 is for beamforming in the radio

communication network. This module corresponds to the processing blocks S200, S220, S22oa, and S22ob of Fig. 3. This module can e.g. be implemented by the processing circuitry 30 of Fig. 10, when running the computer program.

[00119] According to an aspect, an embodiment of a computer program 34, 35 for beamforming in a radio communication network is presented with reference to Fig. 10. The computer program comprises computer program code which, when run in a network node 2, 3 of a radio communication network, causes the network node to obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a BS 2 of the radio communication network, and to adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information, wherein the second direction differs from the first direction.

[00120] A computer program product 12, 13, 32, 33 comprising a computer program 14, 15, 34, 35 and a computer readable storage means on which the computer program is stored is also presented.

[00121] The aspects of the present disclosure have mainly been described above with reference to a few embodiments thereof. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims

1. A method for beamforming in a radio communication network, the method being performed in a network node (2, 3) of a radio communication network, and the method comprising:

- obtaining (S210) a regulatory restriction information conflicting with an effective radiated power in a first direction from a base station, BS, (2) of the radio

communication network; and

- adjusting (S220) a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information, wherein the second direction differs from the first direction.

2. The method according to claim 1, wherein the adjusting (S220) comprises:

- reducing (S22oa) the effective radiated power in the first direction to meet the regulatory restriction information; and

- increasing (S22ob) the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power in the first direction.

3. The method according to claim 2, wherein the increasing (S22ob) comprises increasing the effective radiated power in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power in the first direction, wherein the third direction differs from the first and second directions.

4. The method according to claim 2, wherein the increasing (S22ob) comprises increasing the effective radiated power in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power.

5. The method according to anyone of claims 1 to 4, wherein the regulatory restriction information is defined by one or more of the following: EIRP, EMF, EMC, and ICNIRP.

6. The method according to anyone of claims 1 to 5, wherein the adjusted effective radiated power is determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

7. The method according to anyone of claims 1 to 6, further comprising: - receiving (S200) beamforming information for a user equipment, UE, (1), for beamforming generation in the first direction.

8. The method according to claim 7, wherein the second direction is a secondary path to the UE.

9. The method according to claim 7, wherein the second direction is to a secondary UE (UAB).

10. The method according to anyone of claims 1 to 9, wherein the regulatory restriction information indicates an average effective radiated power over a period of time, and the effective radiated power is reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

11. A method for beamforming in a radio communication network, the method being performed in a user equipment, UE, (1) in a radio communication network, and the method comprising:

- obtaining (S110) a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE; and

- adjusting (S120) a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

12. The method according to claim 11, wherein the adjusting (S120) comprises:

- reducing (Si2oa) the effective radiated power in the first direction to meet the regulatory restriction information; and

- increasing (Si2ob) the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

13. The method according to claim 11 or 12, wherein the regulatory restriction information is defined by SAR.

14. The method according to any one of claims 11 to 13, wherein the adjusted effective radiated power is determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

15. The method according to anyone of claims 11 to 14, further comprising:

- measuring (S100) a signal quality, for beamforming generation in the first direction.

16. The method according to anyone of claims 11 to 15, wherein the second direction is a secondary path to a base station, BS, (2).

17. The method according to anyone of claims 11 to 15, wherein the second direction is to a secondary BS.

18. The method according to anyone of claims 11 to 17, wherein the regulatory restriction information indicates an average effective radiated power over a period of time, and the effective radiated power is adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

19. A network node for beamforming in a radio communication network, the network node (2, 3) comprising:

a processing circuitry (30); and

a computer program product (32, 33) storing instructions (34, 35) that, when executed by the processing circuitry, causes the network node to:

- obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a base station, BS, (2) in a radio communication network; and

- adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the regulatory restriction information, wherein the second direction differs from the first direction.

20. The network node according to claim 19, wherein the relative radiated power is adjusted and cause the network node to:

- reduce the effective radiated power in the first direction to meet the regulatory restriction information; and

- increase the effective radiated power in the second direction with an effective radiated power of up to the reduced effective radiated power.

21. The network node according to claim 20, wherein the effective radiated power is increased in the second direction and a third direction with an effective radiated power corresponding to the reduced effective radiated power, wherein the third direction differs from the first and second directions.

22. The network node according to claim 20, wherein the effective radiated power is increased in all directions of the BS, but the first direction, with an effective radiated power corresponding to the reduced effective radiated power.

23. The network node according to anyone of claims 19 to 22, wherein the regulatory restriction information is defined by one or more of the following: EIRP, EMF, EMC, and ICNIRP.

24. The network node according to anyone of claims 19 to 23, wherein the adjusted effective radiated power is determined based on one or more of the following: time average, momentary, spatial average, and multiple users.

25. The network node according to anyone of claims 19 to 24, wherein the network node further is caused to:

- receive beamforming information for a user equipment, UE, (1), for beamforming generation in the first direction.

26. The network node according to claim 25, wherein the second direction is a secondary path to the UE.

27. The network node according to claim 25, wherein the second direction is to a secondary UE (UE_B).

28. The network node according to anyone of claims 19 to 27, wherein the regulatory restriction information indicates an average effective radiated power over a period of time, and the effective radiated power is reduced more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the generated beam.

29. A user equipment for beamforming in a radio communication network, the user equipment, UE, (1) comprising:

a processing circuitry (10); and

a computer program product (12, 13) storing instructions (14, 15) that, when executed by the processing circuitry, causes the UE to: - obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE; and

- adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the UE to meet the regulatory restriction information, wherein the second direction differs from the first direction.

30. The UE according to claim 29, wherein the relative effective radiated power is adjusted causing the UE to:

31. The UE according to claim 29 or 30, wherein the regulatory restriction information is defined by SAR.

32. The UE according to any one of claims 29 to 31, wherein the adjusted effective radiated power is determined based on one or more of the following: time average, momentary, spatial average, and multiple base stations.

33. The UE according to anyone of claims 29 to 31, further caused to:

- measure a signal quality, for beamforming generation in the first direction.

34. The UE according to anyone of claims 29 to 33, wherein the second direction is a secondary path to a base station, BS, (2).

35. The UE according to anyone of claims 29 to 33, wherein the second direction is to a secondary BS.

36. The UE according to anyone of claims 29 to 35, wherein the regulatory restriction information indicates an average effective radiated power over a period of time, and the effective radiated power is adjusted more than required by the indicated average effective radiated power over the period of time preventively to save restricted effective radiated power capacity for the first direction.

37. A computer program (34, 35) for beamforming in a radio communication network, the computer program comprising computer program code which, when run in a network node (2, 3) of a radio communication network, causes the network node to:

- obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from a base station, BS, (2) of the radio communication network; and

- adjust a relative effective radiated power between the effective radiated power in the first direction and an effective radiated power in second direction from the BS to meet the obtained regulatory restriction information, wherein the second direction differs from the first direction.

38. A computer program (14, 15) for beamforming in a radio communication network, the computer program comprising computer program code which, when run in a user equipment, UE, (1) of a radio communication network, causes the UE to:

- obtain a regulatory restriction information conflicting with an effective radiated power in a first direction from the UE; and

39. A computer program product (12, 13; 32, 33) comprising a computer program (14, 15; 34, 35) according to claim 36 or 37 and a computer readable storage means on which the computer program is stored.