Directional power back-off in a wireless communication network

Abstract

There is provided techniques for directional power back-off in a wireless communication network. A method is performed by a controller device. The method comprises mapping a normalized gain to at least one spatial segment within a sector served by a transmission point. The mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point. The method comprises estimating normalized EIRP for each spatial segment over a time period by assessing an average power used for each UE and multiplying it by the normalized gain in each spatial segment. The method comprises determining a power reduction level for each spatial segment using an average of the estimated EIRP for each spatial segment. The method comprises performing the directional power back- off by configuring the transmission point with a highest of the determined power reduction levels to be used during transmission from the transmission point to the UEs.

Description

[0001]P111556WO011DIRECTIONAL POWER BACK-OFF IN A WIRELESS COMMUNICATION NETWORK TECHNICAL FIELD Embodiments presented herein relate to a method, a controller device, a computer 5 program, and a computer program product for directional power back-off in a wireless communication network. BACKGROUND When any radio equipment, such as transmission points, is to be deployed, radio frequency (RF) exposure regulations should be accounted for. The electric and 10 magnetic field (EMF) exposure limitations are typically based on the guidelines from the International Commission on Non-Ionizing Radiation Protection (ICNIRP) but may take different forms in different countries and regions. The aim of the RF exposure regulations is to ensure that human exposure to RF energy is kept with the exposure limits, which typically been set with wide safety margin. The RF exposure 15 limits are typically expressed in terms of power density, which in the far field is proportional to the equivalent isotropically radiated power (EIRP). RF exposure limitations are commonly expressed as an average power density over a specified time interval T. This means that the momentary, or instantaneous, power density can be higher than the specified limit, but the time-averaged power density over each 20 time interval T must not exceed the limit. It is well understood that the power density decays with distance from the transmitter. The distance from the transmitter at which the specified limit is met is referred to as the compliance distance. For radio equipment that supports beamforming, multiple-input multiple-output (MIMO) communication, or massive MIMO communication, the antenna beam 25 pattern varies with time, depending on the locations of user equipment (UE) and channel conditions. This means that the time-averaged EIRP is below the momentary or instantaneous EIRP. However, in case the compliance distance is established based on the time-averaged EIRP, time-averaged EIRP control may be required by network operators to ensure 30 that the time-averaged EIRP normalized to the momentary EIRP is below some threshold in percentage.P111556WO012Hence, there is still a need for improved EIRP control of transmission points and other types of radio equipment in a wireless communication network. SUMMARY An object of embodiments herein is to provide efficient time-averaged EIRP control 5 in a wireless communication network. A particular object is to provide implementational-efficient power back-off control based on per-segment EIRP calculation. According to a first aspect there is presented a method for directional power back-off in a wireless communication network. The method is performed by a controller 10 device. The method comprises mapping a normalized gain to at least one spatial segment within a sector served by a transmission point. The normalized gain is based on reported antenna pattern indicators from UEs in the sector. The mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point. The method comprises estimating normalized EIRP for 15 each spatial segment over a time period by assessing an average power used for each UE and multiplying it by the normalized gain in each spatial segment. The method comprises determining a power reduction level for each spatial segment using an average of the estimated EIRP for each spatial segment. The method comprises performing the directional power back-off by configuring the transmission point with 20 a highest of the determined power reduction levels to be used during transmission from the transmission point to the UEs. According to a second aspect there is presented a controller device for directional power back-off in a wireless communication network. The controller device comprises processing circuitry. The processing circuitry is configured to cause the 25 controller device to map a normalized gain to at least one spatial segment within a sector served by a transmission point. The normalized gain is based on reported antenna pattern indicators from UEs in the sector. The mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point. The processing circuitry is configured to cause the controller 30 device to estimate normalized EIRP for each spatial segment over a time period by assessing an average power used for each UE and multiplying it by the normalizedP111556WO013gain in each spatial segment. The process ng circuitry is configured to cause the controller device to determine a power reduction level for each spatial segment using an average of the estimated EIRP for each spatial segment. The processing circuitry is configured to cause the controller device to perform the directional power back-off by 5 configuring the transmission point with a highest of the determined power reduction levels to be used during transmission from the transmission point to the UEs. According to a third aspect there is presented a controller device for directional power back-off in a wireless communication network. The controller device comprises a map module configured to map a normalized gain to at least one spatial 10 segment within a sector served by a transmission point. The normalized gain is based on reported antenna pattern indicators from UEs in the sector. The mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point. The controller device comprises an estimate module configured to estimate normalized EIRP for each spatial segment over a time period 15 by assessing an average power used for each UE and multiplying it by the normalized gain in each spatial segment. The controller device comprises a determine module configured to determine a power reduction level for each spatial segment using an average of the estimated EIRP for each spatial segment. The controller device comprises a configure module configured to perform the directional power back-off 20 by configuring the transmission point with a highest of the determined power reduction levels to be used during transmission from the transmission point to the UEs. According to a fourth aspect there is presented a computer program for directional power back-off in a wireless communication network. The computer program 25 comprises computer code which, when run on processing circuitry of a controller device, causes the controller device to perform actions. One action comprises the controller device to map a normalized gain to at least one spatial segment within a sector served by a transmission point. The normalized gain is based on reported antenna pattern indicators from UEs in the sector. The mapping is based on 30 downlink transmissions in the sector through different types of antenna patterns at the transmission point. One action comprises the controller device to estimate normalized EIRP for each spatial segment over a time period by assessing an average power used for each UE and multiplying it by the normalized gain in each spatialP111556WO014segment. One action comprises the controller device to determine a power reduction level for each spatial segment using an average of the estimated EIRP for each spatial segment. One action comprises the controller device to perform the directional power back-off by configuring the transmission point with a highest of the determined 5 power reduction levels to be used during transmission from the transmission point to the UEs. According to a fifth aspect there is presented a computer program product comprising a computer program according to the fourth aspect and a computer readable storage medium on which the computer program is stored. The computer 10 readable storage medium could be a non-transitory computer readable storage medium. Advantageously, these aspects provide efficient time-averaged EIRP control in a wireless communication network. Advantageously, these aspects provide implementational-efficient power back-off 15 control based on per-segment EIRP calculation. Advantageously, by considering different beamforming behaviors in the mapping, the power control can be less frequently triggered than a cell-wide power control. Advantageously, these aspects can be implemented with a comparably small memory consumption. 20 Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings. Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All 25 references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.P111556WO015BRIEF DESCRIPTION OF THE DRAWINGS The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which: Fig.1 is a schematic diagram illustrating a wireless communication network 5 according to embodiments; Fig.2 is a flowchart of methods according to embodiments; Fig.3 is a block diagram of individual control loops according to an embodiment; Fig.4 is a flowchart of a method for selecting different options for determining mapping weights according to an embodiment; 10 Fig.5 is a decision tree for different options for determining mapping weights according to embodiments; Fig.6 is a schematic diagram showing structural units of a controller device according to an embodiment; Fig.7 is a schematic diagram showing functional modules of a controller device 15 according to an embodiment; and Fig.8 shows one example of a computer program product comprising computer readable storage medium according to an embodiment. DETAILED DESCRIPTION The inventive concept will now be described more fully hereinafter with reference to 20 the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to 25 those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.P111556WO016Fig. 1 is a schematic diagram illustrating a wireless communication network 100 where embodiments presented herein can be applied. The wireless communication network 100 comprises a transmission point 120 configured to provide network access to UEs 140a:140f in spatial segments 130a:130d that collectively defines a 5 sector. In some non-limiting examples, the transmission point 120 comprises an advanced, or adaptive, antenna system. Operation of the transmission point 120 is controlled by a controller device 110. In some non-limiting examples, the controller device 110 is a node B (NB), an evolved node B (eNB), or a gNB. As illustrated in Fig.1, the spatial coverage of a sector can be divided into different10 angular region, or spatial segments, denoted by {Ω^}, where ^ ൌ 1,… , ୗ^^^. Here, ୗ^^^can be 1. Further, {Ω^} does not necessary cover all angles. in general terms, one control loop is implemented for each spatial segment. The general aim of a method for directional power back-off in the wireless communication network 100 is to control the time-averaged EIRP, such that ^^^ ୟ^^^^^,^^15^^^^^ ^ ^ ^^^,^^^^^^^^^^^,^^ ∈ Ω ^^^^^^^^^^^^^^^^^^^^^୪୮^^ ^^ ^୦ ^ ^^^^^^^^^^^^^^^^^^^^^1^where Ω^ is the ^th pre- g g , ୟ^ ,moving-average time window ^ in the zenith angle ^ and the azimuthal angle ^, where ^^^^^ ^୪୮^^,^^ is the peak EIRP in ^^,^^, and where ^^୦^^^ is the threshold for ^^^^^ ^^,^^ ൌ ^^ଡ଼^^^^୪୮^^,^^, where ^^ଡ଼^ is the configured maximum20 transmit power of the sector ^^^ ^^is the envelope of antenna patterns, referred to as the envelope pattern below, of all possible traffic beams. It is noted that ^^^୪୮^^,^^ can be the envelope pattern of traffic beams for the used configurations (which can be less than all possible configurations). For example, if a method for directional power back-off in the wireless communication network 100 is 25 applied to a transmission point with 64 transmitters whilst only a 8-port channel state information reference signal (CSI-RS) is configured, ^^^୪୮^^,^^ can be the envelope pattern of the 8-port CSI-RS traffic beams in case the network operator uses the 8-port CSI-RS envelope pattern for EMF compliance assessment, etc.P111556WO017The method for directional power back-o f in the wireless communication network 100 can be used to make decisions on power reduction based on the highest of the power reduction levels of all control loops. A number of steps of the method for directional power back-off in the wireless communication network 100 are executed 5before input is provided to each control loop. As ^^^^^ ^୪୮^^,^^ can be different valuesfor different^^,^^in the same spatial segment, it is convenient to use normalized gain and normalized EIRP. Then, the averaged and normalized EIRP can be compared with ^^୦^^^to calculate the power reduction level of each control loop. Fig. 2 is a flowchart illustrating embodiments of methods for directional power back- 10 off in a wireless communication network 100. The methods are performed by the controller device 110. The methods are advantageously provided as computer programs. Parallel reference is here made to the block diagram 300 of Fig.3, in which individual control loops for each discrete time interval ^ ൌ 1,… , େ^ୗ, is shown.S102: The controller device 110 maps a normalized gain to at least one spatial 15 segment 130a:130d within a sector served by a transmission point 120. The normalized gain is based on reported antenna pattern indicators from UEs 140a:140f in the sector. The mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point 120. In this way, the normalized gain (or a conservative estimate of the normalized gain) is mapped to one 20 or more spatial segments 130a:130d. Different normalized gain mapping techniques that can be used will be disclosed below. Step S102 can be implemented by the map blocks 310a, 310i, 310N in Fig.3. S104: The controller device 110 estimates the normalized EIRP for each spatial segment 130a:130d over a time period. This is achieved by assessing an average 25 power used for each UE 140a:140f and multiplying it by the normalized gain in each spatial segment 130a:130d. This can be achieved by summing up the normalized EIRP for traffic beams, the normalized EIRP for broadcast beams, and the normalized EIRP used for transmission of reference signals, such as CSI-RS. The normalized EIRP for traffic beams can be obtained by assessing an average power 30 used for each traffic beam and multiplying it by the normalized gain in each spatial segment 130a:130d. The normalized EIRP for broadcast beams can be obtained by assessing an average power used for each broadcast beam and multiplying it by theP111556WO018normalized gain in each spatial segment 30a:130d. The normalized EIRP for transmission of reference signals can be obtained by assessing an average power used downlink reference signals and multiplying it by the normalized gain in each spatial segment 130a:130d. In step S104, the EIRP can thus be estimated per short period ∆^ 5 per direction (i.e., per spatial segment 130a:130d). One discrete time intervals can contain one short period ∆^ or numerous short period ∆^, thus the normalized EIRP per short period ∆^ is averaged over the discrete time intervals as the output of Step S104. Step S104 can be implemented by the estimate blocks 320a, 320i, 320N in Fig. 3. 10 S108: The controller device 110 determines a power reduction level for each spatial segment 130a:130d using an average of the estimated EIRP for each spatial segment 130a:130d. Step S108 can be implemented by the power reduction blocks 340a, 340i, 340N in Fig.3. S110: The controller device 110 performs directional power back-off by configuring 15 the transmission point 120 with a highest of the determined power reduction to be used during transmission from the transmission point 120 to the UEs 140a:140f. The rationale behind this is that, in general terms, the worst-case control loop is the control loop requiring the highest power-backoff. The transmission point 120 can thus be configured according to the worst-case control loop output. The transmission 20 point 120 has then the freedom to allocate the available power (as given by the determined power reduction) to its different UEs 140a:140f. The transmission point 120 can then allocate the rest of the power during the next discrete time interval. Step S110 can be implemented by the power back-off block 350 in Fig.3. Embodiments relating to further details of directional power back-off in a wireless 25 communication network 100 as performed by the controller device 110 will now be disclosed with continued reference to Fig.2. Further aspects of step S102 will be disclosed next. There could be different types of antenna pattern indicators. In some non-limiting examples, the antenna pattern indicators are Precoding Matrix Indicators (PMIs) 30 and / or Rank Indicators (RIs).P111556WO019In some aspects, the mapping considers factors such as coverage shape, radio type, codebook configuration, antenna weights from the codebook, and interactions with other network features. That is, in some non-limiting examples, the mapping is based on the downlink transmissions with respect to at least one of: coverage shape, radio 5 type, codebook configuration, antenna weights, Radio Access Network parameters. Here, the coverage shape might pertain to port-to-antenna (P2A) matrices for traffic beam and broadcast beams. The radio type might pertain to the number of transmitters, such as 4T, 8T, 16T, 32T, 64T, etc., antenna port separation distance, the number of ports per subarray, etc. The codebook configuration might pertain to a10 ( ^^, ଶ^) configuration, see below. The antenna weights might pertain to antennaweights from codebook, e.g., the codebook defined in the technical specification 3GPP TS38.214 entitled “NR; Physical layer procedures for data”, version 18.2.0, Section 5.2.2.2, for different PMI and RI. Radio Access Network parameters might pertain to dynamic EIRP restrictions, massive MIMO sleep mode, beamformed 15 downlink control channel transmission, etc. In some aspects, the mapping depends on the downlink transmission through different types of antenna patterns. In particular, in some embodiments, the types of antenna patterns pertain to at least one of: antenna pattern for traffic beams, antenna pattern for broadcast signals, antenna pattern for reference signals, antenna pattern20 for multiple-input and multiple-output transmission, antenna pattern for grid-of- beams beamformed transmission, antenna pattern for reciprocity assisted transmission. In general terms, for each used beam during a short period ∆^ (e.g., per TTI), the output of step S102 is a mapping vector ^ ൌ ^^^1^,^^2^, … ,^൫ ^^^^൯^, in which ^^^^ is25 a mapping weight for the ^th spatial segment. Hence, in some embodiments, the normalized gain is a mapping weight for each spatial segment 130a:130d. Further details of how the mapping weights can be determined will be disclosed below. Further aspects of step S104 will be disclosed next. In general terms, in step S104, the normalized EIRP can be estimated based on the 30 number of resource elements (REs), power boost, de-boost information, etc. to assess the average power used for each UE, broadcast beam, or transmission of referenceP111556WO0110signals, such as CSI-RS in each spatial segment per ∆^, as made available by an information block 360. A multiplication with the vector ^ obtained in step S102 can be performed to assess the average normalized EIRP per spatial segment per ∆^. As in step S104, the EIRP can be estimated per short period ∆^ per spatial segment 5 130a:130d. There can be different such short periods ∆^. In some aspects, ∆^ equals one transmission time interval (TTI). That is, in some embodiments, the normalized EIRP for each spatial segment 130a:130d is estimated over a time period of one TTI. One discrete time intervals can contain one short period ∆^ or numerous short periods ∆^, and thus the normalized EIRP per short period ∆^ as averaged over the 10 discrete time intervals can be the output of Step S104. As disclosed above, in step S108, an average of the estimated EIRP for each spatial segment 130a:130d (over a moving-average time-window ^) is used for determining the power reduction level for each spatial segment 130a:130d. Therefore, in some embodiments, the controller device 110 is configured to perform (optional) step S106. 15 S106: The controller device 110 obtains the average of the estimated normalized EIRP for each spatial segment 130a:130d by averaging the output from step S104 (i.e., the normalized EIRP for each spatial segment 130a:130d) over a series of discrete time intervals within a time window. Step S106 can be implemented by the (optional) average blocks 330a, 330i, 330N in Fig.3. 20 In this way, the normalized EIRP as averaged over a series of discrete time intervals, େ^ୗ, within the present moving-average time window ^, can be calculated. The time-averaged value can be stored in a bin. The time-averaged bins over the last ୗ^େsteps, or the original normalized EIRP bins over the lastେ^ୗsteps, can be used for each control loop. Therefore, in some embodiments, the power reduction level for 25 each spatial segment 130a:130d is determined using time-averaged bins of the normalized EIRP over the lastୗ^େdiscrete time intervals. Further aspects of step S108 will be disclosed next. In some aspects, the power reduction level for each spatial segment is determined by running all control loops in parallel to calculate the required back-off using the time-P111556WO0111averaged bins over the lastୗ^େdiscrete time intervals. In particular, in some embodiments, determining the power reduction levels comprises running one control loop for each spatial segment 130a:130d to calculate the power reduction level for each spatial segment 130a:130d using the time-averaged bins. 5 In some aspects, the power reduction level is determined based on comparing the averaged assessed EIRP for each spatial segment with a reference EIRP level. Hence, in some embodiments, determining the power reduction levels comprises comparing the average of the estimated EIRP for each spatial segment 130a:130d to a reference EIRP level 370a, 370i, 370N. 10 Further aspects of step S110 will be disclosed next. In some aspects, the directional power back-off is only applied to traffic beams and grid-of-beam transmission, and / or traffic beams and reciprocity assisted transmission, whereas the directional power back-off is not applied to broadcast beams, control channels, or reference signals. 15 The power-backoff can be realized in different ways in the transmission point, for example by reducing the number of available resource blocks and / or the power spectral density (PSD) of the transmission and / or turning-off some antenna ports. In particular, in some embodiments, performing the directional power back-off comprises at least one of: reducing number of available resource blocks for the 20 transmission, reducing transmission power per resource block in the transmission, reducing the PSD of the transmission, turning-off some antenna ports for the transmission. In step S110, the controller device determines the power reduction level based on the highest of the power reduction levels of all control loops. If there is only one spatial 25 segment, i.e., one control loop, the instructed power reduction level is the final decision. Yet further aspects, embodiments, and examples of step S102 will be disclosed next. In general terms, for each small period Δ^, e.g., one TTI, the average EIRP normalized to the peak EIRP can be expressed as:P111556WO01122^ For signals with ort g q y p g waveforms, such as used over the Long-Term Evolution (LTE) air interface and the New Radio (NR) air interface, Equation (2) can be calculated based on the antenna 5 gain per RE, power per RE, and the number of subcarriers (SCs), as in Equation (3): ∑ ே^ు,౫౩^^,ీై^ୀ^^^^,^, ^^^ୖ ^^^^ത ^തത^ത^തത^ത^௧^^,^^ ൌ^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^3^ where ^^^,^, ^ s e a e a ga o e , ^ s e powe use o e hRE. further, ୗ^େ,^ଡ଼^ ൌ ^^ଡ଼^ / ^^ୡ where ^^ୡ is the number of SCs of the entire sectorwithout any RB reduction. Further,ୖ^^,ୟ୪୪is the total number of REs in Δ^, including 10 REs for downlink, guard period, and uplink periods, and assuming no RB reduction. ୖ^^,^^^^,ୈ^is the number of used REs in downlink during Δ^. For REs transmitted with traffic beams, the antenna gains for different REs in the same Δ^ can be different for different UEs, for different RE, and / or for different physical channels or reference signals. The number of grid-of-beams (GoB) traffic 15 beams is finite, while the number of reciprocity assisted transmission traffic beams can be infinite. There can be one or a few broadcast beams used by the transmission point. One or a few ( ^^, ଶ^) configurations can be set in the transmission point anddifferent CSI-RS can be transmitted. The normalized EIRP contributions equation (3) in each angle can be expressed including the contributions from traffic beams, 20 broadcast beam(s), and beams in which CSI-RS is transmitted, as expressed in Equation (4): ത^തത^ത^തത^ത^௧^^,^^ ൌ ത ^തത^ത^തത^ത^௧,^^^,^^ ^ ത ^തത^ത^തത^ത^௧,ଶ^^,^^ ^ ത ^തത^ത^തത^ത^௧,ଷ^^,^^^^^^^^^^^^^^^4^where the subscripts 1, 2, and 3 denote traffic beam, broadcast beam, and beams in which CSI-RS is transmitted, respectively. Thus: ∑ ே^ు,ೖ ^ ^^,^,^ ^^ୖ ^^ ^25 ത ^തത^ത^തത^ത ^ ^^ೖୀ^^ ^ ^,^ ^^௧,^ ^,^ ൌ^ ^^ ^^ , ^ ൌ 1,2,3^^^^^^^^^^^^^^^^^^^^^^^^^^5^ P111556WO0113whereୖ^^,^is the number of REs used for traffic beam, broadcast beam, and CSI-RS transmission in the downlink during Δ^ for ^ ൌ 1, 2, 3, respectively. Note that ୖ^^,^ ^ୖ^^,ଶ ^ ୖ^^,ଷ ൌ ୖ^^,^^^^,ୈ^. ^^^^,^,^^^ is the antenna gain of the ^^th RE using thetraffic beam, broadcast beam, and CSI-RS, for ^ ൌ 1, 2, 3, respectively.5 To be more specific, for traffic beams: ∑ ே^ుே^,భ^^^ు^ ே^ు,భ൫^ ,^ ൯ ^^ుୀ^∑^^,ୀ^^^^൫^,^, ^^^, ^ୠ,^൯∑ ^ు ^,భ^^ు,౪౨ୀ^^ୖ ^,^൫^^^, ^ୠ,^, ^ୖ^,^൯^ ത^തത^ത^തത^ത ^^ ^^ భ^௧^ ൌ^ 6^ w ee^^^s e u e o s sc e ue o ow a s sso us g afic beams,ୠ^,^^^^^^ is the number of different traffic beams used by the ^^^th UE,10 ^^൫^,^, ^^^, ^ୠ,^൯ is the antenna pattern for the ^^^th UE using the ^ୠ,^th traffic beam.ୖ^^,^൫^^^, ^ୠ,^൯ is the number of REs used by the ^^^th UE using the ^ୠ,^th traffic beam.^ୖ ^,^൫^^^, ^ୠ,^, ^ୖ^,^൯ is the power used for the ^ୖ^,^th RE for the ^^^th UE using the^ୠ,^th traffic beam. If Δ^ is small enough that each UE only uses one traffic beam during Δ^, Equation (6) 15 becomes: ே^ు ∑ ே^ు,భ^^^ు^^ୖ ^,^൫^^^, ^ୖ^,^൯ത ^തത^ത^തത^ത^௧^^^,^^ ൌ ^ ^^ ^ ^^^,^, ^^^^^ ൈ^ు,భୀ^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^7^ ^ ^ The f ^^^^,^, ^^^^^^^୪୮^^,^^ is used for directional gain mapping .e., or the ^^^th UE, and the second term ∑ே^ు,భ^^^ు^^^ుୀ^^ୖ ^,^൫^^^, ^ୖ^,^൯20,భ P111556WO0114is a weighted power used for the ^^^th U . The second term is used in step S104. To be more specific, for broadcast beams: ത^തത^ത^തത^ത^௧,ଶ^^,^^ே^,మே ^^ ^ ^^ ൫^,^, ^ ൯ ∑ ^ు,మ ^,మ^^ ୀ^ୖ ^,ଶ൫^ୠ,ଶ, ^ୖ^,ଶ൯ൌ ଶ ୠ,ଶൈ^ు,మ^ ^ ,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^8^ 5where ୠ^,ଶ is t e num er o erent roa cast eams, ଶ , , ୠ,ଶ s t e antennapattern of the ^ୠ,ଶth broadcast beam,ୖ^^,ଶ൫^ୠ,ଶ൯is the number of REs used for the ^ୠ,ଶth broadcast beam. ^ୖ ^,ଶ൫^ୠ,ଶ, ^ୖ^,ଶ൯ is the power used for the ^ୖ^,ଶth RE with the^ୠ,ଶth broadcast beam. Similarly for CSI-RS,10ത^തത^ത^തത^ത^௧,ଷ^^,^^ே^^^^^ ଷ൫^,^, ^ ൯ൌ ^ ୡ^^9^where ୡ^^^ i s e u e o ^^, ଶ^ co gu a o s co gu e or the sector carrier,^ଷ൫^,^, ^ୡ^^൯ is the antenna pattern of the ^ୡ^^th ^ ^^, ଶ^^ configuration, ୖ^^,ଷ^^ୡ^^^ is15 the number of REs used for the ^ୡ^^th ^ ^^, ଶ^^ configuration, and ^ୖ ^,ଷ൫^ୡ^^, ^ୖ^,ଷ൯ is thepower used for the ^ୖ^,ଷth RE with the ^ୡ^^th ^ ^^, ଶ^^ configuration.Different ways to generate the mapping weights ^^^^^, ^ଶ^^^, and ^ଷ^^^, such that ீభ൫ఏ,థ,^^ు,^^,భ൯ ீ^౬^౦^ఏ,థ^^ ^^^^^,ீమ൫ఏ,థ,^^,మ൯ ீ^౬^౦^ఏ,థ^^ ^ଶ^^^, andீయ൫ఏ,థ,^^^^൯ ீ^౬^౦^ఏ,థ^^ ^ଷ^^^ for all ^^,^^ ∈ ^thhus, in the following, 20 ^ ൌ ^^,^ଶ, or ^ଷ.Reference is here made to the flowchart of Fig.4 according to which the mapping weights for the gain mapping can be determined, depending on different types ofP111556WO0115downlink transmissions. It is here noted hat some of the steps do not need to be performed in the order listed here. For example, since Options 3, 4, 5, 8 all reply on a basic mapping table, this basic mapping table can be loaded right after step S202a. S201: The type of beam is identified. Step S202a is entered if the beam type is traffic 5 beams. Step S202b is entered if the beam type is broadcast beams. Step S202c is entered if the beam type is reference signal beams. S202a: It is checked whether a grid-of-beam traffic beam (GoB) or a reciprocity assisted transmission (RAT) beam is used. Step S203a is entered if a grid-of-beam traffic beam is used. Step S203b is entered if a reciprocity assisted transmission 10 beams traffic beam is used. S202b: The mapping vector ^ଶfrom Option 9 is selected. S202c: The mapping vector ^ଷfrom Option 10 is selected. S203a: It is checked whether the beam is used for transmission of downlink control information or not. If yes, step S204a is entered. If no, step S204b is entered. 15 S203b: The mapping vector ^^from either Option 6, Option 7, or Option 8, is selected. S204a: The mapping vector ^^from Option 6 is selected. S204b: A basic mapping table is loaded. The basic mapping table can be generated using Option 1 or Option 2 to generate a mapping vector ^^for grid-of-beam beams 20 as a basic mapping table. Here, Option 1 and Option 2 can use different types of information based on which the mapping vector ^^can be generated. For example, mapping vector ^^can be generated based on downlink transmissions with respect to at least one of: coverage shape, radio type, codebook configuration, antenna weights, Radio Access Network parameters, as disclosed above. 25 S205: It is checked whether the beam can be found in the basic mapping table or not. If yes, step S206a is entered. If no, step S206b is entered. S206a: The mapping vector ^^from the basic mapping table is selected.P111556WO0116S206b: The mapping vector ^^from either Option 3, option 4, or Option 5 is selected. In Fig.5 is schematically illustrated a decision tree 500 according to which the mapping weights for the gain mapping can be determined, depending on different types of downlink transmissions. For traffic beams there are eight different options; 5 six for GoB transmission (Option 1 to Option 6) and three for reciprocity assisted transmission (Option 6 to option 8), with Option 6 common for both alternatives. For broadcast beams there is one option (Option 9), and for CSI-RS transmission there is one option (Option 10). Examples of how the mapping weights can be determined for the different options in Fig.5. will be disclosed next. 10 Option 1: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed transmission, for broadcast signals, and for reference signals, the mapping weight per spatial segment 130a:130d is determined as a function of an antenna gain and an envelope of antenna radiation patterns of all possible traffic beams in the spatial 15 segment 130a:130d. In more detail, for GoB traffic beam downlink transmission, each UE reports a PMI (^^^, ^^ଶ, ^^ଷ) and a RI; for some ^ ^^, ଶ^^ configuration or RI, each UE only reports(^^^, ^^ଶ) or ^^^. For each PMI and RI combination, the mapping vector ^^^^^, ^ ൌ1,2,… ^^^^ can then be determined as20 ^^^^^ ൌ ^ఏ, mథ^a∈ஐx ^^^^,^,^^^,^^^^^^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^10. a^^^୪୮^^,^^b^w e e , , , s e a e a a a o pa e o e spec c a RI, ^^^^^,^,^^^,^^^ is the corresponding array factor, ^^^ ^୪୮^^,^^ is the envelope of themagnitude of array factors for all possible traffic beams. One advantage of using array 25 factor calculation is that the mapping vector can be calculated using the information of number of elements in the array, the separation distances between adjacent elements, the size of subarrays, frequency, P2A matrix, and the codebook defined in the aforementioned technical specification 3GPP TS 38.214 Section 5.2.2.2, and thusP111556WO0117without any information of the actually used (three-dimensional) antenna radiation pattern. The mapping table can be generated according to Equations (10.a) or (10.b) in real-time or can be stored in memory after generation rather than using hard- coded directional gain mapping table. 5 Equation (10.a) implies that the mapping weight should be determined by the maximum ratio between the antenna gain ^^^^,^,^^^,^^^and the envelope of antenna radiation patterns of all possible traffic beams ^^^୪୮^^,^^considering for all ^^,^^ in each segment. Equation (10.b) implies that such a ratio can also be calculated using the square of the absolute value of array factors. 10 Option 2: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed transmission, the mapping weights are quantized to predetermined values. In further detail, only a limited number, ^^^, of levels ^^ୋ୭^^^^௩^^, ^^^ ൌ 1,2, … ^^^ canbe used to create the entire mapping table (0 ^ ^ୋ୭^^^^௩^ ^ 1). For example, one15 condition could be that in the ^th segment, the mapping weight ^^^^^^for each PMI and RI needs to fulfill: ^^ ^^ୋ^^^^,^,^^^,^^^ 1^ ^^ ^ ൌ ^ୋ୭^ ^^^^ ^ ^ఏ, mథ^a∈ஐx^^^^^^୪୮^^,^^ 1^ Equation (11 q , pp g g g nded 20 up to a limited number of levels. One advantage of this is to simplify implementation and save memory. In general terms, creating a mapping table including mapping vectors for all possible PMIs can results in a very large size of mapping table. Therefore, it might be beneficial to create a basic mapping table containing a subset of all possible PMIs. 25 The mapping vectors for the rest of the PMIs can use simplified approaches to calculate using the mapping vectors in the basic mapping table. Options 3 to Options 5 show such approaches.P111556WO0118Option 3: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed transmission, the mapping weights are scaled down for a codebook configuration that has lower antenna gains than an envelope of antenna radiation patterns of all 5 possible traffic beams. In further detail, if an intermediate weight ^ୋ୭^^^^ is generated with respect to the envelope pattern of the corresponding ^ ^^, ଶ^^ configuration but not ^^^୪୮^^,^^, e.g.,^ୋ୭^^^^ for ^ ^^ ൌ 4, ଶ^ ൌ 1^ is generated normalized to the envelope pattern of alltraffic b with ^ ^^ ൌ 4, ଶ^ ൌ 1^ while ^^^୪୮^^,^^ is the envelope pattern for ^ ^^ ൌ10 8, ଶ^ ൌ 2^, the envelope pattern for this ^ ^^, ଶ^^ configuration is smaller (or partlysmaller) than ^^^୪୮^^,^^. An additional scaling weight ^^ଶ^,^or scaling vector ^^ଶ^,^^^^, ^ ൌ 1,2,… , ௌ^^^ can be applied to ^ୋ୭^^^^ for each ^, i.e., the mapping weightbecomes: ^^^^^ ൌ ^ୋ୭^^^^^^ଶ^,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^12.^^15 or ^^^^^ ൌ ^ୋ୭^^^^^^ଶ^,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^12. ^^equations (12.a) and (12.b) imply that the mapping vector for one ^ ^^, ଶ^^configuration that has lower antenna gains than ^^^୪୮^^,^^can be scaled down by another factor ^^ଶ^,^. 20 Option 4: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed transmission, the mapping weights for a codebook configuration are calculated based on a combination of mapping weights for at least one rank-1 beam. In further detail, for some^ ^^, ଶ^^ configurations, the mapping vector can be25 calculated based on the combination of mapping vector of one or a few rank-1 beams. In this case,P111556WO01193^ where ^^^^^ is calculated us g ^^ a ^ଷ o e o g a , a ^ , ^^^ ^^^, ^ ,^^ᇱ ൌ 1^ is the mapping wei ᇱ^ ^ଶ ght of another rank-1 beam (^^ ൌ 1). Further:^^^^^ ൌ ^ ^^^ mod^^, 2^ ൌ 0^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^ ^ ^^^^^ଷ^^^^^^ ^ ^ mod^^, 2^ ൌ 1^^^^^^^^^^14^ ^^^ 5 ^^^^^ may use ^^ଶrather than ^^^depending on the P2A mapping. The values for ^^and^^can be found in the aforementioned technical specification 3GPP TR 38.214, Table 5.2.2.2.1-2, Table 5.2.2.2.1-3, and Table 5.2.2.2.1-4. Option 5: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed 10 transmission, the mapping weights for a codebook configuration with rank indicator > 2, the mapping weights are calculated based on the element-wise maximum of the mapping vectors of at least two rank-1 beams with adjacent number of PMI indices. In further detail, for some ^ ^^, ଶ^^ configurations with RI > 2, the mapping vector canbe calculated based on the element-wise maximum of the mapping vectors of a few 15 rank-1 beams with adjacentୟ^number of ^^^indices. In this case: ^^^^^ ൌ ^ୋ୭^,୰ୟ୬୩^^^^ ൈ^∈^ି mேax ^^^^, ^^^ ൌ ^ଶ^^^, ^^ଶ,^^′ ൌ 1^^^^^^^^^^^^^^^15^^,…,ே^^^where ^ୋ୭ ^,୰ୟ୬୩ ୋ୭^,୰ୟ୬୩ s a sca g ac o a co s e s e gadifference between the rank-1 GoB beam and rank- ^^ GoB beam. One of the possible expressions for ^ଶ^^^ is:20 ^ଶ^^^ ൌ ^2^^^ ^ ^^^mod^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^16^Option 6: Traffic beam mapping In some embodiments, for traffic beams and grid-of-beams beamformed transmission, for traffic beams and reciprocity assisted transmission, or for trafficP111556WO0120beams in which a downlink control channel is transmitted, the mapping weight is unity (i.e., equal to 1) for all spatial segments 130a:130d. Here, different scenarios can be envisioned. In a first scenario, if a downlink control channel is transmitted using traffic beams, 5 for RI>1 transmission, the transmission point can randomly select from a few rank-1 traffic beams. In this case, the exact used traffic beam PMI may be difficult to know. In such a case, a conservative estimate of the contribution of the transmission power on the downlink control channel is: ^^^^^ ൌ 1^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^17^10 If the PMI used for the downlink control channel is available, ^^^^^ can be calculated in the same way as other options. Equation (17) implies that if a downlink control channel is transmitted in a traffic beam, the mapping weight is 1 for all spatial segments. This is a conservative estimation when the PMI of the used traffic beam for the downlink control channel is unknown to the controller device. 15 In a second scenario, the contribution from a UE for which reciprocity assisted transmission is used can be conservatively mapped to all spatial segments using Equation (17) when the antenna patterns are not known to the controller device in real time. Option 7: Traffic beam mapping 20 In some embodiments, for traffic beams and reciprocity assisted transmission, the mapping weights are scaled down from unity (i.e., scaled down from 1) according to the antenna pattern indicator for all spatial segments 130a:130d accounting for gain difference between antenna patterns for traffic beams and reciprocity assisted transmission and an envelope of antenna radiation patterns of all possible traffic 25 beams. In further detail, if data, e.g., baseband traces, events, or counters, collected from the network proves that the time-averaged value ^^^^,^^ ^^^୪୮^^,^^ P111556WO0121for a UE for which reciprocity assisted transmission is used is statistically lower than a certain level, ^ୖ^^^^^^^^^^, the mapping weight can be set as: ^^^^^ ൌ ^ୖ^^^^^ୟ^^୰^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^18^where ^^ୟ^^୰can be equal to a ca a so e e u e o aye s e a s ss on 5 point is actually using for downlink transmission. ^ୖ^^൫^^ୟ^^୰^൯ can be different fixed values for different ^^ୟ^^୰ and 0 ^ ^ୖ^^൫^^ୟ^^୰^൯ ^ 1.Option 8: Traffic beam mapping In some embodiments, for traffic beams and reciprocity assisted transmission, the mapping vector is calculated based on the mapping vector or the element-wise 10 maximum of mapping vectors of at least one traffic beam using grid-of-beams beamformed transmission, depending on the antenna pattern indicators reported by the UEs 140a:140f, and where a minimum value is set for the mapping weights to account for sidelobe levels for traffic beams and reciprocity assisted transmission. In further detail, using empirical antenna pattern data for reciprocity assisted 15 transmission collected from simulations or field operation, e.g., baseband traces, events, or counters, ^^^^^ for reciprocity assisted transmission may be possibly determined based on the UE reported PMI and RI. For a given PMI and RI combination, ^^^^^ can be derived based on the empirical antenna patterns used for reciprocity assisted transmission while providing a statistically conservative 20 overestimation of ^ ^^,^^ maxୖ^^^ఏ,థ^∈ஐ^^^^^^୪୮^^,^^where ^ୖ^^^^,^^ is the antenna pa e use o eciprocity assisted transmission. From the empirical antenna patterns used for reciprocity assisted transmission, the mapping vector can be calculated using the rank-1 GoB mapping vector. For the ^th 25 segment, the intermediate vector is calculated as: ^ୖ^^^^^ ൌ^∈^ି mேax ^^^^, ^^^ ൌ ^ଷ^^^, ^^ଶ,^^′ ൌ 1^^^^^^^^^^^^^^^^^^19^^,…,ே^^^ P111556WO0122where ^^^^, ^^^ ൌ ^ଷ^^^, ^^ଶ,^^′ ൌ 1^ is the mapping weight of GoB UE with ^^^ ൌ^ଷ^^^, ^^ଶ,^^′ ൌ 1. One of the possible expressions for ^ଷ^^^ is^ଷ^^^ ൌ ^ ^^^^ ^ ^^^mod^ ^^ ^^^ ^^ ൌ 1^or^2^2^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^20^ ^^ ^ ^^^mod^ ^^ ^^^ ^^ ^ 2Equations ( a py aୖ^^s e a u o e app g vecos o 52^ ^ 1 number of rank-1 GoB beams element-wise.For RI>2, ^ୖ^^^^^ can also be calculated based on the mapping vectors of GoB UE for the same RI: ^ୖ^^^^,^^^,^^^ ൌ^∈^ି mேax ^^^^, ^^^ ൌ ^ସ^^^, ^^ଶ, ^^ଷ,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^21^^,…,ே^^^where ^, ^^ ସ , ^ଶ, ^ଷ, s e app g veco o o w ^^10 ^ସ^^^, ^^ଶ, ^^ଷ,^^, and ସ^^^^ ^ ^^^mod^ ^^ ^^ / 2^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^22^Equations (21) and (22) imply that ^ୖ^^can be the maximum of the mapping vectors of 2^ ^ 1 number of rank-RI GoB beams element-wise.The final mapping weight for a UE for which reciprocity assisted transmission is used 15 can be determined as: ^^ୖ^^,୰ୟ୬୩^^^^^ୖ^^^^^ if^^ୖ^^^^^ ^ ^ோ^்^^^^ ൌ ^ ,ௌ^^ otherw ^^^^^^^^^^^^23^ ୖ^^ୗ^ise where ^ୖ^^ ,ୗ^s a conserva ve es mae o e s eo e eves or suc Es determined based on different PMIs and RIs. ^ୖ^^,୰ୟ୬୩^^^^ ^ 1 is a scaling factor thataccounts for the gain difference between reciprocity assisted transmission and 20 ^^^୪୮^^,^^. Equation (23) implies that for those spatial segments considered as main l ributions, the weight ^ୖ^^^^^ ^^^ should apply. For other spatial ^^,୰ୟ୬୩ ୖ^^segments, a conservative estimate of sidelobe contributions ^ୖ^^,ୗ^should apply. Further, ^ୖ^^,୰ୟ୬୩^^^^^ୖ^^^^^should be larger than ^ୖ^^,ୗ^.Option 9: Broadcast beam mappingP111556WO0123In this alternative, the mapping vector ^ଶ^^ for the ^ୠ,ଶth broadcast beam is determined based on the following criteria: ^^,^, ^ ^ଶ 1^ ^ ^^ ଶ൫ ୠ,ଶ൯ ห ^ଶ൫^,^, ^ୠ,ଶ൯หଶ ^ ^^ఏ mథ^a∈ஐx^^^^ ^^^^ൌ^ఏ mథ^a∈xஐ^^^ ଶ^^^^^^^^^^^^24^ where ଶ, , ୠ,ଶ s t e ୠ,ଶt roa cast eam pattern an ଶ , , ୠ,ଶ s the5 corresponding array factor. There can be only one broadcast beam. Equation (24) implies that the mapping weight should be determined by the maximum ratio between the antenna gain ^ଶ൫^,^, ^ୠ,ଶ൯ and the envelope of antennaradiation patterns of all possible traffic beams ^^^୪୮^^,^^ considering for all ^^,^^ in each spatial segment. The weight can also be calculated using the square of the 10 absolute value of array factors. One advantage of using array factors is that the controller device does not need to know the embedded antenna element patterns, but only antenna weights. Option 10: CSI-RS mapping In this alternative, the mapping vector for CSI-RS ^ଷ^^^ for the ^ୡ^^th ^ ^^, ଶ^^15 configuration is determined based on the following criteria: ^൫^,^, ^ ൯ ห^^൫^,^, ^ଶ ଷ^^ ଷ ୡ^^ ଷ ୡ^^൯ห1 ^ ^ ^ ^^ m^ax^^^ ൌ^m^ax^^ ଶ^^^^^^^^^^^^25^ ^ ^^^^^where ଷ, , ୡ^^ s t e ୡ^^t - eam pattern an ଷ , , ୡ^^ s t ecorresponding array factor. Because antenna gain for CSI-RS commonly is much lower than ^^^୪୮^^,^^, a fixed value ^ଷcan be applied to all spatial segments for all20 used ^ ^^, ଶ^^ configurations. Equation (25) implies that the mapping weight could bedetermined by the maximum ratio between the antenna gain ^ଷ൫^,^, ^ୡ^^൯ and theenvelope of antenna radiation patterns of all possible traffic beams ^^^୪୮^^,^^ considering for all ^^,^^ in each spatial segment. The mapping weight can also be calculated using the square of the absolute value of array factors. One advantage of 25 using array factors is that the controller device does not need to know the embedded antenna element patterns, but only antenna weights.P111556WO0124Yet further aspects, embodiments, and eamples of step S104 will be disclosed next. The terms ∑ ே^ు,భ^^^ు^ ^^ు,భୀ^^ୖ ^,^൫^^^, ^ୖ^,^൯, d 5 in Equations (7), (8) and ( cae e u e o s used by the UE and then weighted with power-boosting / deboosting factor for the^^^^UE, the ^ୠ,ଶth broadcast beam, and the ^ୡ^^th CSI-RS, respectively. These terms can be expressed as: ∑ ே^ు,భ^^^ు^ ^^ు,భୀ^^ୖ ^,^൫^^^, ^ୖ^,^൯ൌ ோ^ா,^^^^^^∆ ோ^ா,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^26^ 10 7^ 8^ where ∆ ோ^ா,^ ^^ s e ave age powe oos g e- oos g aco o e ^^ ,∆ ோ^ா,ଶ൫^ୠ,ଶ൯ is the average power boosting / de-boosting factor for the ^ୠ,ଶth broadcastbeam and ∆ ோ^ா,ଷ൫^ୡ^^൯ is the average power boosting / de-boosting factor for the ^ୡ^^th15 configuration of CSI-RS. If REs are used by the transmission point creating artificial load through traffic beam, broadcast beam, and CSI-RS transmission rather than the traffic and other channels used by UE, all aforementioned gain mapping and EIRP calculation can also be applied with the used power levels, and mapping vectors.P111556WO0125As such, for each Δ^, the average EIRP for the ^th spatial segment can be estimated as: ே ^^௧ ^^ ൌ1ೆಶ^ ^ ^^^^,^^^^^^ா^,^^^^^ா^^ ோ^ா^^^^^^∆ ோ^ா^^^^^^5 Equation p es a e௧s e weg e su o ,ଶ, and ^ଷ^^^. This ensures that ^^௧^^^ ^^ఏ, mథ^a∈ஐx^^^ത^തത^ത^തത^ത^௧^^,^^.For each given d , malized EIRP averaged over this given discrete time interval can be expressed as: ே 1^^10ത ^തത^ത^തത^തୌ^^^ ൌ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^30^ where ^^௧ is th e u e o pe sc ee e e va. . s a e e ghof one discrete time interval is 600 ms, then ^^௧ ൌ 1200.Two scenarios relating thereto will be disclosed next. A first scenario relates to adaptive EIRP limitation. In this scenario, in case the 15 transmission point is configured to control the peak EIRP for all channels or the peak EIRP for only the downlink data channel, the transmission point can reduce the power for MIMO transmission with lower number of ranks but allows the maximum configured transmit power for higher number of ranks. The transmission point can achieve this by reducing the transmitted power for lower number of ranks. In this20 case, an additional power de-boosting factor can be applied to ∆ ோ^ா,^^^^^^,∆ ோ^ா,ଶ൫^ୠ,ଶ൯, or ∆ ோ^ா,ଷ൫^ୡ^^൯ according to the MIMO rank or the type of beam. Forwer spectral density (PSD) limit is ^^dBm / MHz, and the P111556WO0126transmitted power PSD corresponding to the maximum configured transmit power is ^ଶ dBm / MHz, and the antenna gain for rank-1 transmission is ^^ dBi. If ^ଶ ^ ^^ ^ ^^,the adaptive EIRP control will reduce the transmitted power PSD by ∆^ dB for the ^rank-1 traffic beam, such that ^ଶ ^ ^^ െ ∆^^ ^ ^^. In this case, an additional scaling5 factor (in linear scale) 10ି∆௫భ / ^^ ld b pplied to ∆ ோ^ா,^^^^^^, while for highernumber of MIMO rank, such as rank-4, a lower reduction, such as 10^ି∆௫భାଷ^ / ^^can be applied to ∆ ோ^ா,^^^^^^. Such reduced power compensation can also be applied instep S102. A second scenario relates to massive MIMO sleep or MIMO sleep. In this scenario, in 10 case the transmission point uses massive MIMO sleep or MIMO sleep, only part of the antenna ports is activated for transmission. A new mapping table can be constructed in accordance with the embodiments disclosed herein. Also, the transmit power can be reduced. Therefore, there can be a static scaling factor ୟ^ୡ^୧^^^^ / ୟ^୪୪^^,whereୟ^ୡ^୧^^^^is the number of active transmitters during the sleep time andୟ^୪୪^^is 15 the total number of transmitters can be applied to Equation (28). Yet further aspects, embodiments, and examples of steps S106, S108, and S110 will be disclosed next. The normalized EIRP averaged over the complete series of discrete time intervals can be expressed as: ே 1ి^20ത ^തത^ത^തത^തୟ^^^^ ൌ ^ ത ^തത^ത^തത^തୌ^^,^ୌ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^30^ whereେ^ୗis t e num er o scre e me n erva s w n e mov ng-average me window ^. For example, if ^ ൌ 6^min^and the length of one discrete time interval is600 ms, then େ^ୗ ൌ 1500. The value of ത ^തത^ത^തത^തୟ^^^^ for this discrete time interval andthose calculated in the previous number of discrete time intervals, e.g.,େ^ୗ, can be 25 stored in the bins as the input for the controller device 110. Some (radio) access network architectures define network nodes (or gNBs) comprising multiple component parts or nodes: a central unit (CU), one or more distributed units (DUs), and one or more radio units (RUs). The protocol layer stackP111556WO0127of the network node is divided between the CU, the DUs and the RUs, with one or more lower layers of the stack implemented in the RUs, and one or more higher layers of the stack implemented in the CU and / or DUs. The CU is coupled to the DUs via a fronthaul higher layer split (HLS) network; the CU / DUs are connected to the 5 RUs via a fronthaul lower-layer split (LLS) network. The DU may be combined with the CU in some embodiments, where a combined DU / CU may be referred to as a CU or simply a baseband unit. A communication link for communication of user data messages or packets between the RU and the baseband unit, CU, or DU is referred to as a fronthaul network or interface. Messages or packets may be transmitted from the 10 network node in the downlink (i.e., from the CU to the RU) or received by the network node in the uplink (i.e., from the RU to the CU). Fig. 6 schematically illustrates, in terms of a number of structural units, the components of a controller device 600 according to an embodiment. Processing circuitry 610 is provided using any combination of one or more of a suitable central 15 processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 810 (as in Fig.8), e.g. in the form of a storage medium 630. The processing circuitry 610 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). 20 Particularly, the processing circuitry 610 is configured to cause the controller device 600 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 630 may store the set of operations, and the processing circuitry 610 may be configured to retrieve the set of operations from the storage medium 630 to cause the controller device 600 to perform the set of operations. The set of operations 25 may be provided as a set of executable instructions. Thus the processing circuitry 610 is thereby arranged to execute methods as herein disclosed. The storage medium 630 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 controller device 600 30 may further comprise a communications (comm.) interface 620 at least configured for communications with other entities, functions, nodes, and devices, as in Fig.1. As such the communications interface 620 may comprise one or more transmitters andP111556WO0128receivers, comprising analogue and digita components. The processing circuitry 610 controls the general operation of the controller device 600 e.g. by sending data and control signals to the communications interface 620 and the storage medium 630, by receiving data and reports from the communications interface 620, and by retrieving 5 data and instructions from the storage medium 630. Other components, as well as the related functionality, of the controller device 600 are omitted in order not to obscure the concepts presented herein. Fig. 7 schematically illustrates, in terms of a number of functional modules, the components of a controller device 700 according to an embodiment. The controller 10 device 700 of Fig.7 comprises a number of functional modules; a map module 710 configured to perform step S102, an estimate module 720 configured to perform step S104, a determine module 740 configured to perform step S108, and a configure module 750 configured to perform step S110. The controller device 700 of Fig.7 may further comprise a number of optional functional modules, such as an obtain module 15 730 configured to perform step S106. In general terms, each functional module 710:750 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 630 which when run on the processing circuitry makes the controller device 600 perform the corresponding steps 20 mentioned above in conjunction with Fig 7. 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 710:750 may be implemented by the processing circuitry 610, 25 possibly in cooperation with the communications interface 620 and / or the storage medium 630. The processing circuitry 610 may thus be configured to from the storage medium 630 fetch instructions as provided by a functional module 710:750 and to execute these instructions, thereby performing any steps as disclosed herein. The controller device 110, 600, 700 may be provided as a standalone device or as a 30 part of at least one further device. For example, the controller device 110, 600, 700 may be provided in a node of a (radio) access network or in a node of a core network. Alternatively, functionality of the controller device 110, 600, 700 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, mayP111556WO0129either be part of the same network part (such as the (radio) access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the sector than instructions that are not 5 required to be performed in real time. Thus, a first portion of the instructions performed by the controller device 110, 600, 700 may be executed in a first device, and a second portion of the of the instructions performed by the controller device 110, 600, 700 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 10 by the controller device 110, 600, 700 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a controller device 110, 600, 700 residing in a cloud computational environment. Therefore, although a single processing circuitry 610 is illustrated in Fig.6 the processing circuitry 610 may be distributed among a plurality of devices, or nodes. 15 The same applies to the functional modules 710:750 of Fig.7 and the computer program 820 of Fig.8. Fig. 8 shows one example of a computer program product 810 comprising computer readable storage medium 830. On this computer readable storage medium 830, a computer program 820 can be stored, which computer program 820 can cause the 20 processing circuitry 610 and thereto operatively coupled entities and devices, such as the communications interface 620 and the storage medium 630, to execute methods according to embodiments described herein. The computer program 820 and / or computer program product 810 may thus provide means for performing any steps as herein disclosed. 25 In the example of Fig.8, the computer program product 810 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 810 could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable 30 programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 820 is here schematically shown as a track on the depicted opticalP111556WO0130disk, the computer program 820 can be s ored in any way which is suitable for the computer program product 810. The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other 5 embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

P111556WO0131C AIMS 1. A method for directional power back-off in a wireless communication network (100), wherein the method is performed by a controller device (110, 600, 700), and wherein the method comprises: 5 mapping (S102) a normalized gain to at least one spatial segment (130a:130d) within a sector served by a transmission point (120), wherein the normalized gain is based on reported antenna pattern indicators from user equipments, UEs (140a:140f), in the sector, and wherein the mapping is based on downlink transmissions in the sector through different types of antenna patterns at the 10 transmission point (120); estimating (S104) normalized equivalent isotropically radiated power, EIRP, for each spatial segment (130a:130d) over a time period by assessing an average power used for each UE (140a:140f) and multiplying it by the normalized gain in each spatial segment (130a:130d); 15 determining (S108) a power reduction level for each spatial segment (130a:130d) using an average of the estimated EIRP for each spatial segment (130a:130d); and performing (S110) the directional power back-off by configuring the transmission point (120) with a highest of the determined power reduction levels to 20 be used during transmission from the transmission point (120) to the UEs (140a:140f).

2. The method according to claim 1, wherein the antenna pattern indicators are Precoding Matrix Indicators and / or Rank Indicators.

3. The method according to claim 1 or 2, wherein the mapping is based on the 25 downlink transmissions with respect to at least one of: coverage shape, radio type, codebook configuration, antenna weights, Radio Access Network parameters.

4. The method according to any preceding claim, wherein the types of antenna patterns pertain to at least one of: antenna pattern for traffic beams, antenna pattern for broadcast signals, antenna pattern for reference signals, antenna pattern forP111556WO0132multiple-input and multiple-output transmission, antenna pattern for grid-of-beams beamformed transmission, antenna pattern for reciprocity assisted transmission.

5. The method according to any preceding claim, wherein the normalized gain is a mapping weight for each spatial segment (130a:130d). 5 6. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, for broadcast signals, and for reference signals, the mapping weight per spatial segment (130a:130d) is determined as a function of an antenna gain and an envelope of antenna radiation patterns of all possible traffic beams in the spatial segment (130a:130d). 10 7. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, the mapping weights are quantized to predetermined values.

8. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, the mapping weights are scaled down for a codebook 15 configuration that has lower antenna gains than an envelope of antenna radiation patterns of all possible traffic beams.

9. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, the mapping weights for a codebook configuration are calculated based on a combination of mapping weights for at least one rank-1 beam. 20 10. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, the mapping weights for a codebook configuration with rank indicator > 2, the mapping weights are calculated based on an element-wise maximum of mapping vectors of at least two rank-1 beams with adjacent number of PMI indices. 25 11. The method according to claim 5, wherein, for traffic beams and grid-of-beams beamformed transmission, for traffic beams and reciprocity assisted transmission, or for traffic beams in which a downlink control channel is transmitted, the mapping weight is unity for all spatial segments (130a:130d).P111556WO013312. The method according to claim 5, w erein, for traffic beams and reciprocity assisted transmission, the mapping weights are scaled down from unity according to the antenna pattern indicator for all spatial segments (130a:130d) accounting for gain difference between antenna patterns for traffic beams and reciprocity assisted 5 transmission and an envelope of antenna radiation patterns of all possible traffic beams.

13. The method according to claim 5, wherein, for traffic beams and reciprocity assisted transmission, the mapping weights are calculated based on the mapping weights or an element-wise maximum of mapping vectors of at least one traffic beam 10 using grid-of-beams beamformed transmission, depending on the antenna pattern indicators reported by the UEs (140a:140f), and where a minimum value is set for the mapping weights to account for sidelobe levels for traffic beams and reciprocity assisted transmission.

14. The method according to any preceding claim, wherein the normalized EIRP for 15 each spatial segment (130a:130d) is estimated over a time period of one transmission time interval.

15. The method according to any preceding claim, wherein the method further comprises: obtaining (S106) the average of the estimated normalized EIRP for each spatial 20 segment (130a:130d) by averaging the normalized EIRP for each spatial segment (130a:130d) over a series of discrete time intervals within a time window.

16. The method according to claim 15, wherein the power reduction level for each spatial segment (130a:130d) is determined using time-averaged bins of the normalized EIRP over the discrete time intervals. 25 17. The method according to claim 16, wherein determining the power reduction levels comprises running one control loop for each spatial segment (130a:130d) to calculate the power reduction level for each spatial segment (130a:130d) using the time-averaged bins.P111556WO013418. The method according to any prece ng claim, wherein determining the power reduction levels comprises comparing the average of the estimated EIRP for each spatial segment (130a:130d) to a reference EIRP level.

19. The method according to any preceding claim, wherein performing the 5 directional power back-off comprises at least one of: reducing number of available resource blocks for the transmission, reducing transmission power per resource block in the transmission, reducing power spectral density of the transmission, turning-off some antenna ports for transmission.

20. A controller device (110, 600, 700) for directional power back-off in a wireless 10 communication network (100), the controller device (110, 600, 700) comprising processing circuitry (610), the processing circuitry being configured to cause the controller device (110, 600, 700) to: map a normalized gain to at least one spatial segment (130a:130d) within a sector served by a transmission point (120), wherein the normalized gain is based on 15 reported antenna pattern indicators from user equipments, UEs (140a:140f), in the sector, and wherein the mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point (120); estimate normalized equivalent isotropically radiated power, EIRP, for each spatial segment (130a:130d) over a time period by assessing an average power used 20 for each UE (140a:140f) and multiplying it by the normalized gain in each spatial segment (130a:130d); determine a power reduction level for each spatial segment (130a:130d) using an average of the estimated EIRP for each spatial segment (130a:130d); and perform the directional power back-off by configuring the transmission point 25 (120) with a highest of the determined power reduction levels to be used during transmission from the transmission point (120) to the UEs (140a:140f).

21. A controller device (110, 600, 700) for directional power back-off in a wireless communication network (100), the controller device (110, 600, 700) comprising:P111556WO0135a map module (710) configured to map a normalized gain to at least one spatial segment (130a:130d) within a sector served by a transmission point (120), wherein the normalized gain is based on reported antenna pattern indicators from user equipments, UEs (140a:140f), in the sector, and wherein the mapping is based on 5 downlink transmissions in the sector through different types of antenna patterns at the transmission point (120); an estimate module (720) configured to estimate normalized equivalent isotropically radiated power, EIRP, for each spatial segment (130a:130d) over a time period by assessing an average power used for each UE (140a:140f) and multiplying it 10 by the normalized gain in each spatial segment (130a:130d); a determine module (740) configured to determine a power reduction level for each spatial segment (130a:130d) using an average of the estimated EIRP for each spatial segment (130a:130d); and a configure module (750) configured to perform the directional power back-off 15 by configuring the transmission point (120) with a highest of the determined power reduction levels to be used during transmission from the transmission point (120) to the UEs (140a:140f).

22. The controller device (110, 600, 700) according to claim 20 or 21, further being configured to perform the method according to any of claims 2 to 19. 20 23. A computer program (820) for directional power back-off in a wireless communication network (100), the computer program comprising computer code which, when run on processing circuitry (610) of a controller device (110, 600, 700), causes the controller device (110, 600, 700) to: map (S102) a normalized gain to at least one spatial segment (130a:130d) within 25 a sector served by a transmission point (120), wherein the normalized gain is based on reported antenna pattern indicators from user equipments, UEs (140a:140f), in the sector, and wherein the mapping is based on downlink transmissions in the sector through different types of antenna patterns at the transmission point (120); estimate (S104) normalized equivalent isotropically radiated power, EIRP, for 30 each spatial segment (130a:130d) over a time period by assessing an average powerP111556WO0136used for each UE (140a:140f) and multip ying it by the normalized gain in each spatial segment (130a:130d); determine (S108) a power reduction level for each spatial segment (130a:130d) using an average of the estimated EIRP for each spatial segment (130a:130d); and 5 perform (S110) the directional power back-off by configuring the transmission point (120) with a highest of the determined power reduction levels to be used during transmission from the transmission point (120) to the UEs (140a:140f).

24. A computer program product (810) comprising a computer program (820) according to claim 23, and a computer readable storage medium (830) on which the 10 computer program is stored.

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