Patent Publication Number: US-2023145081-A1

Title: Aerial vehicle and control thereof

Description:
TECHNICAL FIELD 
     Embodiments presented herein relate to an aerial vehicle, a method, a controller, a computer program, and a computer program product for controlling the aerial vehicle. 
     BACKGROUND 
     Unmanned aerial vehicles (UAVs), also known as drones, are becoming more and more popular in daily life for private or professional applications. UAVs might utilize cellular mobile networks by acting as user equipment (UE) for control or relaying of data (such as video), or even serving as flying radio base stations serving UEs on the ground. Existing frequency bands as traditionally utilized for radio communication in cellular mobile networks might be reused to guide or operate UAVs and carry payload information to the UAVs. UAVs might be considered as operating at comparatively low altitudes, such as no more than 300 m from ground. For operating UAVs within cellular mobile networks, the frequency bands below 1.8 GHz, or even below 1 GHz, are of particular interest due to their potentially large coverage range. 
     In order to operate UAVs within cellular mobile networks, some issues must be resolved. One issue relates interference and/or blocking caused by UAVs towards other services that operate in nearby frequencies or frequency bands. Interference on other frequencies typically arises due to harmonics or intermodulation products (e.g. second order harmonic or possible intermodulation distortion (IMD)) due to transmitter non-linearities in the radio transceiver devices of the UAVs. Apart from interference, another issue is that services operating in nearby frequencies or frequency bands may be susceptible to transmission power in the frequency band used by the UAVs due to imperfect selectivity of the receivers used by these services. In turn, this might result in blocking. Further, UAVs might, due to not being based on the ground, have line of sight (LOS) conditions both to the communications device they are communicating with (e.g. a UE or a radio base station) as well as to radio receivers belonging to other services. 
     So-called coordination zones might be used in order to protect other ground services (e.g. radar stations, radio astronomy services, etc.). Within co-ordination zones, transmissions within certain frequency bands are forbidden in order to avoid the risk of interference and/or blocking towards the receivers of such ground services. Co-ordination zones are placed around these ground service receivers. Such coordination zones can be from a few kilometers wide in the case of a radar station and up to 100 km wide in the case of radio astronomy service (RAS) earth receiver stations. For UAVs such coordination zones may be a no-fly zone (exclusion zone). Alternatively, the UAVs might have additional and more stringent restrictions on transmit power and/or spurious emissions within the co-ordination zone, or a combination of no-fly zones and restricted limits. However, despite these measures, there is still a risk that the UAVs continue to cause interfere and/or blocking to other ground services. 
     Hence, there is still a need for an improved radio emission control of UAVs and other types of aerial vehicles. 
     SUMMARY 
     An object of embodiments herein is to provide efficient radio emission control of an aerial vehicle as well as an aerial vehicle that implements such efficient radio emission control. 
     According to a first aspect there is presented an aerial vehicle. The aerial vehicle comprises a radio transceiver device configured for radio transmission in a set of radiation directions. The aerial vehicle comprises a mechanical shield positioned to reduce power of the radio transmission in at least some of the radiation directions in the set of radiation directions. The aerial vehicle comprises a controller configured to control at least one of: movement of the aerial vehicle, movement of the mechanical shield, radio communication of the aerial vehicle via the radio transceiver device. 
     According to a second aspect there is presented a method for controlling an aerial vehicle according to the first aspect. The method comprises controlling, using the controller, at least one of: movement of the aerial vehicle, movement of the mechanical shield, radio communication of the aerial vehicle via the radio transceiver device. 
     According to a third aspect there is presented a controller for controlling an aerial vehicle according to the first aspect. The controller comprises processing circuitry. The processing circuitry is configured to cause the controller to control at least one of: movement of the aerial vehicle, movement of the mechanical shield, radio communication of the aerial vehicle via the radio transceiver device. 
     According to a fourth aspect there is presented a controller for controlling an aerial vehicle according to the first aspect. The controller comprises a control module configured to control at least one of: movement of the aerial vehicle, movement of the mechanical shield, radio communication of the aerial vehicle via the radio transceiver device. 
     According to a fifth aspect there is presented a computer program for controlling an aerial vehicle according to the first aspect, the computer program comprising computer program code which, when run on a controller, causes the controller to perform a method according to the second aspect. 
     According to a sixth aspect there is presented a computer program product comprising a computer program according to the fifth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium. 
     Advantageously these aspects provide efficient radio emission control of the aerial vehicle. 
     Advantageously these aspects enable operation of the aerial vehicle within restricted zones, such as within co-ordination zones. 
     Advantageously, the mechanical shield is simple yet efficient to limit radiation from the radio transceiver device in defined direction(s), without explicit radiation, or emission, control of the radio transceiver device. 
     Advantageously, the mechanical shield is simple yet efficient to limit radiation from the radio transceiver device in defined direction(s), for example as a function of height and distance between the unmanned aerial vehicle and a victim radio transceiver device. 
     Advantageously these aspects are applicable for aerial vehicles acting as user equipment as well as radio access network nodes. 
     Advantageously these aspects are not limited to any particular frequency bands. 
     Advantageously these aspects are readily combined with existing mechanisms for radiation, or emission, limitations. 
     Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings. 
     Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, module, action, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, action, etc., unless explicitly stated otherwise. The actions of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which: 
         FIG.  1    is a schematic diagram illustrating a communication network according to embodiments; 
         FIG.  2    schematically illustrates an aerial vehicle according to an embodiment; 
         FIGS.  3  and  4    are flowcharts of methods according to embodiments; 
         FIG.  5    is a schematic diagram showing functional units of a controller according to an embodiment; 
         FIG.  6    is a schematic diagram showing functional modules of a controller according to an embodiment; and 
         FIG.  7    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 the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any action or feature illustrated by dashed lines should be regarded as optional. 
       FIG.  1    is a schematic diagram illustrating a communication network  100  where embodiments presented herein can be applied. 
     The communication network  100  comprises network access points  140  and a victim radio transceiver device  150 . Non-limiting examples of network access points  140  are radio access network nodes, radio base stations, base transceiver stations, node Bs, evolved node Bs, gNBs, access points, backhaul nodes, integrated access and backhaul nodes, repeater nodes, etc. The network access points  140  might thus define a cellular network. Non-limiting examples of victim radio transceiver devices  150  are radar stations, radio astronomy services, etc. A user equipment  160  is provided network access, and thus served, by at least one of the network access points  140  or by an aerial vehicle  200 . Further aspects of the aerial vehicle  200  will be provided below. 
     The communication network  100  is divided into three geographical zones; a normal limitation zone  110 ; a coordination zone  120 ; and an exclusion zone  130 . Each such zone is associated with its own set of restrictions regarding allowed transmission power levels, allowed frequency bands for communication, etc. Within the normal limitation zone  110  there are not any further restrictions than those commonly applied to a traditional cellular communication network. Within the co-ordination zone  120 , transmissions within certain frequency bands are forbidden in order to avoid the risk of interference and/or blocking towards the receivers of the victim radio transceiver device  150 . Within the exclusion zone  130  the same requirements as within the coordination zone  120  apply and in addition thereto, at least some aerial traffic is forbidden. 
     In  FIG.  1    is further illustrated an aerial vehicle  200 . In some examples the aerial vehicle  200  is an unmanned aerial vehicle (UAV), also known as a drone. According to a first example, the aerial vehicle  200  is operated autonomously without real-time connection to the cellular network. If the flight path of the aerial vehicle  200  is known, the flight path could be determined and programmed before flight takeoff. According to a second example, the aerial vehicle  200  is operated by being controlled over the cellular network. As an alternative, the aerial vehicle  200 , if acting as a network access point, might have its own scheduler which can make decisions regarding the flight path during flight time. 
     As noted above there is still a need for an improved radio emission control of UAVs and other types of aerial vehicles  200 . 
     Further in this respect, aerial vehicles  200 , such as UAVs, are limited in size and weight and therefore possibilities for filtering aimed at reducing interference and/or blocking caused by a radio transceiver device of the aerial vehicle  200  are more limited than for ground based radio equipment. 
     Still further, the aerial vehicles  200  could use a frequency band that does not require any restrictions when the aerial vehicle  200  is located within the coordination zone or has less restrictive requirements in specification regarding out of band transmissions and spurious emissions. One issue here is the limitation of available frequency band for radio communication. This is especially true for the frequency bands below 1.8 GHz. 
     The embodiments disclosed herein therefore relate to an aerial vehicle  200  and mechanisms for controlling the aerial vehicle  200 . In order to obtain such mechanisms there is provided an aerial vehicle  200 , a controller  300 , a method performed by the controller  300 , a computer program product comprising code, for example in the form of a computer program, that when run on a controller  300 , causes the controller  300  to perform the method. 
     Reference is now being made to  FIG.  2    which schematically illustrates an aerial vehicle  200  according to an embodiment. 
     The aerial vehicle  200  comprises a radio transceiver device  210 . The radio transceiver device  210  is configured for radio transmission in a set of radiation directions. 
     The aerial vehicle  200  further comprises a mechanical shield  220 . The mechanical shield  220  positioned to reduce power of the radio transmission of the radio transceiver device  210  in at least some of the radiation directions in the set of radiation directions. In this respect, the aerial vehicle  200  might comprise either one single mechanical shield  220  or two or more such mechanical shields  220 ; the herein disclosed embodiments are not limited in this respect. However, for simplicity but without loss of generality, the aerial vehicle  200  will be described as having one mechanical shield  220 . 
     The aerial vehicle  200  further comprises a controller  300 . The controller  300  is configured to control at least one of: movement of the aerial vehicle  200 , movement of the mechanical shield  220 , radio communication of the aerial vehicle  200  via the radio transceiver device  210 . 
     Further aspects of the aerial vehicle  200  will be disclosed hereinafter with continued references to  FIG.  1    and  FIG.  2   . 
     There could be different types of radio transceiver devices  210 . In some examples, the radio transceiver device  210  is part of: a user equipment, a network access point, a backhaul node, an integrated access and backhaul node, or a repeater node, as provided in the aerial vehicle  200 . The aerial vehicle  200  might thereby act as either a user equipment or a network access point. When acting as a network access point, the aerial vehicle  200  might provided network access to another user equipment  160 . As will be further disclosed below, the mechanical shield  220  might be movable relative to the antenna of the radio transceiver device  210 . This also implies that in principle the antenna of the radio transceiver device  210  could be movable relative the mechanical shield  220 . In yet further aspects, the antenna of the radio transceiver device  210  is movably mounted on the aerial vehicle  200 . In yet further aspects, the radio transceiver device  210  comprises, or is operatively connected to, more than one antenna and the controller  300  is configured to selectively connect the radio transceiver device  210  to one or more of the antennas. Thereby, which one or more antenna is actually used for transmission (and/or reception) can be controlled by the controller  300  and this might also enable the power of the radio transmission of the radio transceiver device  210  to be reduced in at least some of the radiation directions in the set of radiation directions. Further in this respect, the receiver part of the radio transceiver device  210  might always be operatively connected to all the antennas of the radio transceiver device  210 . 
     In further aspects, the controller  300  might be mounted in a body  250  of the aerial vehicle  200 . The mechanical shield  220  might be attached to the body  250  by means of an arm  240  and a joint  230 . The arm  240  might be a telescope arm and thus be extendable and retractable. The controller  300  might further be configured to extend and retract the arm  240 . The joint  230  might be a ball joint or other type of joint. The joint  230  might be electrically controlled. The controller  300  might thereby control positioning of the mechanical shield  220  by interacting with the joint  230 . The aerial vehicle  200  further comprises rotors  260  that are controlled by one or more motors (not shown) enabling the aerial vehicle  200  to fly. The one or more motors might be electrically controlled. The controller  300  might thereby control manoeuvring of the aerial vehicle  200  by interacting with the one or more motors. According to the illustrative example of  FIG.  2   , the aerial vehicle  200  further comprises legs  270  for supporting the aerial vehicle  200  when located on ground. 
     Particular aspects relating to the mechanical shield  220  will now be disclosed. 
     According to the illustrative example of  FIG.  2   , the mechanical shield  220  is exterior to the radio transceiver device  210  in the aerial vehicle  200 . That is, in some embodiments the mechanical shield  220  is positioned exterior to the radio transceiver device  210 . 
     As disclosed above, the mechanical shield  220  positioned to reduce power of the radio transmission of the radio transceiver device  210 . The mechanical shield  220  therefore reduces radio emission in those directions covered by the mechanical shield  220 . That is, in some embodiments, the mechanical shield  220  is positioned to reduce power of the radio transmission in the radiation directions covered by the mechanical shield  220 . 
     There could be different ways to mount the mechanical shield  220  in the aerial vehicle  200 . In some aspects, the mechanical shield  220  is fixed at a static position relative to the aerial vehicle  200 . That is, in some embodiments, the mechanical shield  220  is fixedly mounted in the aerial vehicle  200 . The aerial vehicle  200  can then rotate its flying position or adjust the flight route where needed to fulfill emission requirements in the direction towards the victim radio transceiver device  150  during flight time. In other aspects the mechanical shield  220  is movable around the antenna of the radio transceiver device  210 . That is, in some embodiments, the mechanical shield  220  is movably mounted in the aerial vehicle  200 . Movement of the mechanical shield  220  might then be controlled by the controller  300 . That is, the controller  300  might be configured to place the mechanical shield  220  in a certain position with respect to the antenna of the radio transceiver device  210 , potentially also at a certain distance from the antenna of the radio transceiver device  210 , etc. One purpose of adjusting the position of the mechanical shield  200  is to create different spatial radiation patterns of attenuated-radiation directions with respect to the direction towards the victim radio transceiver device  150 . 
     If, for example, the attenuation is realized using a ground plane as the mechanical shield  220 , then the mechanical shield  220  might be in the near-field electromagnetic field. That is, the radio transmission in the set of radiation directions might give rise to a near-field electromagnetic field and a far-field electromagnetic field, and in some embodiments the mechanical shield  220  is positioned to reduce power of the radio transmission in the near-field electromagnetic field. Alternatively, in some cases, the mechanical shield  220  might need to be placed further towards the far-field electromagnetic field, depending on the design of the mechanical shield  220 , the intended radiation pattern of the radio transceiver device  210 , and the physical restrictions of the aerial vehicle  200 . That is, in some embodiments, the mechanical shield  220  is positioned to reduce power of the radio transmission in the far-field electromagnetic field. 
     There could be different materials of the mechanical shield  220 . In some embodiments, the mechanical shield  220  is made of a radio emission absorbing material. The mechanical shield  220  could thus be constructed from absorbing materials. In this respect, the mechanical shield  220  could be constructed from sheet metal, a metal screen, and/or a metal foam. Any holes in the mechanical shield  220  are significantly smaller than the wavelength of the radiation that is intended to be reduced (i.e., to reduce power of the radio transmission of the radio transceiver device  210 ). Further, the mechanical shield  220  might comprise a ground plane. Apart from attenuating radiation in the direction of the victim radio transceiver device  150 , the mechanical shield  220  might be constructed to increase the radiation of the radio transceiver device  210  in the wanted direction (i.e. to create a directional radiation pattern), and thus act as a directional antenna. Alternatively, the mechanical shield  220  might reduce radiation in unwanted directions only. In some embodiments, the mechanical shield  220  is provided with a radio frequency selective surface, and the mechanical shield  220  is positioned for the radio frequency selective surface to face the radio transceiver device  210 . In this respect, frequency selective surfaces, such as resonators, wavetraps, high-impedance surfaces, might be mounted on the aerial vehicle  200 . The position of the frequency selective surfaces with respect to the antenna of the radio transceiver device  210  could be adjustable. One reason for having a frequency selective structure is to attenuate the radiated signal from the antenna of the radio transceiver device  210  at frequencies that would cause interference towards the victim radio transceiver device  150  whilst avoiding as far as possible attenuation of the signal transmitted in the operating frequency band of the aerial vehicle  200 . 
     Combinations of the above-disclosed embodiments are possible. 
     Particular aspects relating to how the controller  300  might be configured to reduce the impact of the transmission from the radio transceiver device  210  towards the victim radio transceiver device  150  will now be disclosed. 
     In some aspects, the controller  300  is configured to reduce the impact by determining how to orient the mechanical shield  220  (for example with respect to the absolute position of the aerial vehicle  200 , the direction towards, or location of, the victim radio transceiver device  150 , and/or the elevation of the aerial vehicle  200 ). That is, some embodiments, the controller  300  is configured to determine how to orient the mechanical shield  220  upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. Upon having obtained the indication, the controller  300  might then orient the mechanical shield  220  accordingly. There could be different ways for the controller  300  to obtain this indication. In some aspects, and as will be disclosed below the indication is an internal indication of the aerial vehicle  200  whilst in other aspects the indication is an external indication with respect to the aerial vehicle  200 . 
     In some aspects, the controller  300  is configured to reduce the impact by reducing the radio transmission towards the victim radio transceiver device  150 . That is, in some embodiments, the radio transmission is to be reduced towards a victim radio transceiver device  150 , and the mechanical shield  220  is positioned in a direction from the radio transceiver device  210  towards the victim radio transceiver device  150 . If this is not the case, the controller  300  might then orient the mechanical shield  220  accordingly. 
     There could be different ways for the controller  300  to determine the direction towards the victim radio transceiver device  150 . 
     In some aspects the controller  300  uses information about the relative positions of the aerial vehicle  200  and the victim radio transceiver device  150  to determine the direction towards the victim radio transceiver device  150 . That is, in some embodiments, how to place the mechanical shield  220  is based on information of relative positions of the aerial vehicle  200  and the victim radio transceiver device  150 . Information of the relative positions of the aerial vehicle  200  and the victim radio transceiver device  150  might be obtained e.g. from a database. 
     In some aspects the controller  300  uses measurements to determine the direction towards the victim radio transceiver device  150 . That is, in some embodiments, how to place the mechanical shield  220  is based on measurements obtained by the controller  300 . The measurements might either be performed by the aerial vehicle  200  itself or be made available to the controller  300 , for example from a network access point  140 . The measurements could, for example, be based on cellular network signals, or geographical positioning signals, or barometric pressure signals. 
     In some aspects the controller  300  uses signalling to determine the direction towards the victim radio transceiver device  150 . That is, in some embodiments, in which direction to place the mechanical shield  220  is based on signalling from the victim radio transceiver device  150  or from a network access point  140 . 
     Particular aspects relating to how the controller  300  might be configured to determine whether or not the aerial vehicle  200  should take any action to avoid, or at least reduce, interference and/or blocking in the direction towards the victim radio transceiver device  150  will now be disclosed. Examples of such actions will be disclosed further below. 
     In some embodiments, the controller  300  is configured to determine whether the mechanical shield  220  is to be placed in a given position or not upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. In some embodiments, this given position corresponds to that the mechanical shield  220  is positioned in the direction from the radio transceiver device  210  towards the victim radio transceiver device  150 . 
     In some aspects the controller  300  is configured to determine whether or not the aerial vehicle  200  should take any action based on information of relative positions of the aerial vehicle  200  and the victim radio transceiver device  150 . That is, in some embodiments, whether the mechanical shield  220  is to be placed in this given position or not depends on information of relative positions of the aerial vehicle  200  and the victim radio transceiver device  150 . 
     In some aspects the controller  300  is configured to determine whether or not the aerial vehicle  200  should take any action based on the elevation of the aerial vehicle  200 . That is, in some embodiments, whether the mechanical shield  220  is to be placed in this given position or not depends on the vertical distance between the aerial vehicle  200  and ground. Instead of the vertical distance between the aerial vehicle  200  and ground, the difference in vertical distance between the aerial vehicle  200  and the victim radio transceiver device  150  can be used. 
     In some aspects the controller  300  is configured to determine whether or not the aerial vehicle  200  should take any action based on measurements. That is, in some embodiments, whether the mechanical shield  220  is to be placed in this given position or not depends on measurements obtained by the controller  300 . The measurements might be performed by the radio transceiver device  210  itself and then be provided to the controller  300  or be performed by one of the network access points  140  and then be provided to the controller  300  via the radio transceiver device  210 . In yet further examples the measurements are performed by the victim radio transceiver device  150  and then provided to the aerial vehicle  200 . In this respect, a network access point  140  either within or outside the coordination zone may signal to the aerial vehicle  200  that the radio transceiver device  210  needs to lower transmission power. The controller  300  might use such signalling to trigger placement of the mechanical shield  220  in a given position. 
     In some aspects the controller  300  is configured to determine whether or not the aerial vehicle  200  should take any action based on information of the victim radio transceiver device  150 . That is, in some embodiments, whether the mechanical shield  220  is to be placed in the given position or not depends on information pertaining to the victim radio transceiver device  150 . Such information might pertain to during which hours of the victim radio transceiver device  150  is operating, other pieces of information pertaining to the activity level of the victim radio transceiver device  150 , and/or information specifying the geographical location of the victim radio transceiver device  150 . Such information might indicate to the controller  300  as to when in time the mechanical shield  220  needs to be enabled and/or at which geographical location the mechanical shield  220  is to be placed. Having determined the direction towards the victim radio transceiver device  150  and that an action is needed to reduce interference towards the victim radio transceiver device  150 , the mechanical shield  220  may thus be placed accordingly. 
     Since the radiation is by the mechanical shield  220  only attenuated in certain directions, it might be necessary to further adjust the way in which transmissions to/from the radio transceiver device  210  of the aerial vehicle  200  is handled. Such adjustment might, for example, pertain to which network access point  140  is serving the radio transceiver device  210  of the aerial vehicle  200 , and mobility procedures performed by the radio transceiver device  210  of the aerial vehicle  200 . That is, in some embodiments, the controller  300  is configured to instruct the radio transceiver device  210  to perform at least one network-related action upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. 
     Examples of network-related actions will be provided next. 
     According to a first example, the radio transceiver device  210  is forced even before reaching the coordination zone to be subjected to handover and thus establish an operative connection to a new network access point  140  for continued network service. 
     According to a second example, the radio transceiver device  210  is operatively connected to different network access points  140  in the transmit direction and in the receive direction, respectively, so that transmission in the direction towards the victim radio transceiver device  150  is avoided whilst reception remains to be from the network access point  140  with highest power or quality (such as highest RSRP or RSRQ). This can be achieved by mechanisms such as dual connectivity (DC) connections. Further, in case time division duplexing (TDD) is used, attenuation by the mechanical shield  220  needs only to be enabled when transmission from the radio transceiver device  210  is enabled such that attenuation caused by the mechanical shield  220  is synchronized with the transmission periods of the radio transceiver device. 
     According to a third example, the radio transceiver device  210  reduces its transmit power based on the distance between itself and the victim radio transceiver device  150 . The attenuation of the transmit power might further be dependent on the actual vertical distance to ground, or elevation, of the aerial vehicle  200 , and/or the relative vertical distance between the aerial vehicle  200  and the victim radio transceiver device  150 . For example, when placed on the ground, the aerial vehicle  200  might act as a regular UE. 
     According to a fourth example, the radio transceiver device  210  adjusts its use of physical resource blocks or frequency carriers within its transmission bandwidth such that interference and harmonics do not fall into the receive frequency band of the victim radio transceiver device  150 . 
     According to a fifth example, the frequency carrier or frequency band used for communication with the radio transceiver device  210  is changed. 
     In some examples the at least one network-related action thus pertains to any of: switch a network connection of the radio transceiver device  210  from one network access point  140  to another network access point  140 ; operatively connect the radio transceiver device  210  to one network access point  140  in transmit direction and another network access point  140  in receive direction; reduce transmission power of the radio transmission; adjust use of physical resource blocks and/or carriers within a transmission bandwidth used by the radio transceiver device  210  for the radio transmission; adjust carrier frequency and/or frequency band used by the radio transceiver device  210  for the radio transmission. 
     The aerial vehicle  200  might further be instructed by the controller  300  to adjust the flight height in order to change the condition for the mechanical shield  220  and the radiation towards the victim radio transceiver device  150 . That is, in some embodiments, the controller  300  is configured to instruct the aerial vehicle to adjust its vertical distance to ground upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. 
       FIG.  3    is a flowchart illustrating embodiments of methods for controlling an aerial vehicle  200  as disclosed above. The methods are performed by the controller  300 . The methods are advantageously provided as computer programs  720 . 
     S 102 : The controller  300  controls at least one of: movement of the aerial vehicle  200 , movement of the mechanical shield  220 , radio communication of the aerial vehicle  200  via the radio transceiver device  210 . 
     Embodiments relating to further details of controlling an aerial vehicle  200  as performed by the controller  300  will now be disclosed. 
     As disclosed above, the controller  300  might determine how to orient the mechanical shield  220 . That is in some embodiment, the controller  300  is configured to perform (optional) action S 102   a  as part of the control in action S 102 : 
     S  102   a : The controller  300  determines how to orient the mechanical shield  220  upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. The controller  300  then initiates movement of the mechanical shield  220  accordingly. 
     As disclosed above, the controller  300  might determine whether the mechanical shield  220  is to be placed in a given position or not. That is in some embodiment, the controller  300  is configured to perform (optional) action S 102   b  as part of the control in action S 102 : 
     S 102   b : The controller  300  determines whether the mechanical shield  220  is to be placed in a given position or not upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. The controller  300  then initiates movement of the mechanical shield  220  accordingly. 
     As disclosed above, the controller  300  might instruct the radio transceiver device  210  to perform at least one network-related action. That is in some embodiment, the controller  300  is configured to perform (optional) action S 102   c  as part of the control in action S 102 : 
     S 102   c : The controller  300  instructs the radio transceiver device  210  to perform at least one network-related action upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. 
     As disclosed above, the controller  300  might instruct the aerial vehicle  200  to adjust its vertical distance to ground. That is in some embodiment, the controller  300  is configured to perform (optional) action S 102   c  as part of the control in action S 102 : 
     S 102   c : The controller  300  instructs the aerial vehicle  200  to adjust its vertical distance to ground upon obtaining an indication that the power of the radio transmission needs to be reduced in at least some of the radiation directions in the set of radiation directions. 
       FIG.  4    is a flowchart illustrating one particular embodiment of a method for controlling an aerial vehicle  200  based on at least some of the above disclosed embodiments. 
     S 202 : Operation of the aerial vehicle  200  is initiated. In this respect, the aerial vehicle  200  is certified for operating in specific frequency bands and is provided with a mechanical shield  220  to avoid radio transmission, or emission, in certain direction(s). The controller  300  is aware of the radiation pattern of the antennas of the the radio transceiver device  210  and is configured to adjust the radiation by placing the mechanical shield  220  in a certain position. The aerial vehicle  200  might be calibrated and certified before takeoff to follow license requirements, which may add additional restrictions in some areas. 
     S 204 : The route of the aerial vehicle  200  is kept track of during flight. In this respect, the location of the aerial vehicle  200  is kept track of either by the controller  300  or by one or more of the network access points  140 . Either the controller  300  or one or more of the network access points  140  has access to a database of victim radio transceiver devices  150  which need protection, and/or coordination zones for these victim radio transceiver devices  150 , and/or exclusion zones for these victim radio transceiver devices  150 . Either the controller  300  or one or more of the network access points  140  might track the activity level of these victim radio transceiver devices  150  that need protection and/or other factors, such as time of day etc. 
     S 206 : The controller  300  determines how to orient the mechanical shield  220  to reduce radiation, or emission, of the radio transmission device  210  in the direction towards the victim radio transceiver devices  150 . In this respect, if the aerial vehicle  200  comes close to a victim radio transceiver device  150  or a coordination zone and the controller  300  or one or more of the network access points  140  determines that transmission from the radio transceiver device  210  of the aerial vehicle  200  might cause harmful interference and/or blocking, radiation in that or those direction(s) can be limited by means of placing the mechanical shield  220  appropriately. 
     S 208 : It is checked whether the radiation, or emission, of the radio transmission device  210  in the direction towards the victim radio transceiver devices  150  exceeds a threshold value, such as a maximum interference threshold. If no, action S 206  is entered again. If yes, action S 210  is entered. 
     S 210 : The controller  300  takes a further action to further reduce the radiation, or emission, of the radio transmission device  210  in the direction towards the victim radio transceiver devices  150 . In this respect, if the threshold value is determined to still be exceeded, then the controller  300  needs to take a further action, for example to instruct the aerial vehicle  200  to maintain sufficient flight distance to the victim radio transceiver device  150 , or change the direction of the transmission from the radio transceiver device  210  to another direction, for example by performing a handover, or instruct the radio transceiver device  210  to change its operating frequency. 
       FIG.  5    schematically illustrates, in terms of a number of functional units, the components of a controller  300  according to an embodiment. Processing circuitry  310  is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product  710  (as in  FIG.  7   ), e.g. in the form of a storage medium  330 . The processing circuitry  310  may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). 
     Particularly, the processing circuitry  310  is configured to cause the controller  300  to perform a set of operations, or steps, as disclosed above. For example, the storage medium  330  may store the set of operations, and the processing circuitry  310  may be configured to retrieve the set of operations from the storage medium  330  to cause the controller  300  to perform the set of operations. The set of operations may be provided as a set of executable instructions. 
     Thus the processing circuitry  310  is thereby arranged to execute methods as herein disclosed. The storage medium  330  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  300  may further comprise a communications interface  320  at least configured for communications with other components of the aerial vehicle  200 , such as the mechanical shield  220  and the radio transceiver device  210 . As such the communications interface  320  may comprise one or more transmitters and receivers, comprising analogue and digital components. The processing circuitry  310  controls the general operation of the controller  300  e.g. by sending data and control signals to the communications interface  320  and the storage medium  330 , by receiving data and reports from the communications interface  320 , and by retrieving data and instructions from the storage medium  330 . Other components, as well as the related functionality, of the controller  300  are omitted in order not to obscure the concepts presented herein. 
       FIG.  6    schematically illustrates, in terms of a number of functional modules, the components of a controller  300  according to an embodiment. The controller  300  of  FIG.  6    comprises a control module  310   a  configured to perform action S 102 . The controller  300  of  FIG.  6    may further comprise a number of optional functional modules, such as any of a determine module  310   b  configured to perform action S 102   a , a determine module  310   c  configured to perform action S 102   b , an instruct module  310   d  configured to perform action S 102   c , and an instruct module  310   e  configured to perform action S 102   d . In general terms, each functional module  310   a - 310   e  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  330  which when run on the processing circuitry makes the controller  300  perform the corresponding actions mentioned above in conjunction with  FIG.  6   . 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  310   a - 310   e  may be implemented by the processing circuitry  310 , possibly in cooperation with the communications interface  320  and/or the storage medium  330 . The processing circuitry  310  may thus be configured to from the storage medium  330  fetch instructions as provided by a functional module  310   a - 310   e  and to execute these instructions, thereby performing any actions as disclosed herein. 
     The controller  300  may be provided as a standalone device or as a part of at least one further device. For example, the controller  300  may be integrated with, part of, or collocated with, other circuitry of the aerial vehicle  200 . Further, a first portion of the instructions performed by the controller  300  may be executed in a first device, and a second portion of the of the instructions performed by the controller  300  may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the controller  300  may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a controller  300  residing in a cloud computational environment. Therefore, although a single processing circuitry  310  is illustrated in  FIG.  5    the processing circuitry  310  may be distributed among a plurality of devices, or nodes. The same applies to the functional modules  310   a - 310   e  of  FIG.  6    and the computer program  720  of  FIG.  7   . 
       FIG.  7    shows one example of a computer program product  710  comprising computer readable storage medium  730 . On this computer readable storage medium  730 , a computer program  720  can be stored, which computer program  720  can cause the processing circuitry  310  and thereto operatively coupled entities and devices, such as the communications interface  320  and the storage medium  330 , to execute methods according to embodiments described herein. The computer program  720  and/or computer program product  710  may thus provide means for performing any actions as herein disclosed. 
     In the example of  FIG.  7   , the computer program product  710  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  710  could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program  720  is here schematically shown as a track on the depicted optical disk, the computer program  720  can be stored in any way which is suitable for the computer program product  710 . 
     The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.