Methods and apparatuses for compensating a movement of an antenna structure having an antenna

Abstract

A method (600) for compensating a movement of a first antenna structure (110) having a first antenna (120) mounted thereto. The first antenna (120) is configured to communicate with a second antenna (150) over a wireless communication channel. The method (600) comprises obtaining (610), from a radar (111) or a lidar attached to the first antenna structure (110), data indicative of an offset position of the radar (111) or the lidar relative to one or more fixed references (391, 392, 493) for the first antenna structure (110). The method further comprises estimating (640) the movement of the first antenna structure (110) by comparing the offset position of the radar (111) or the lidar to a set position of the radar (111) or the lidar relative to the one or more fixed references (391, 392, 493). The method also comprises controlling (660) a beam direction (121) of the first antenna (120) to compensate for the estimated movement of the first antenna structure (110).

Description

[0001] METHODS AND APPARATUSES FOR COMPENSATING A MOVEMENT OF AN ANTENNA STRUCTURE

[0002] HAVING AN ANTENNA

[0003] TECHNICAL FIELD

[0004] The present disclosure relates generally to the field of wireless communication. More particularly, the present disclosure relates to a method for compensating movement of an antenna structure having an antenna mounted thereto, a node performing the disclosed method, a computer program product for carrying out the disclosed method, and a computer program carrier carrying said computer program.

[0005] BACKGROUND

[0006] Point-to-point links at high frequencies, e.g., at E-band, W-band or D-band, need to rely on high-directivity antennas (e.g., >50 dBi) to get sufficient link gain to be able to reach large distances, high capacities, and / or high availability. High-directivity antennas have very narrow main beams (e.g. 0.5 degrees half-power beam width for a 60 cm 50 dBi E-band antenna). This makes a wireless communication channel between two directive antennas sensitive to antenna misalignment or movement (such as sway) of one or both of the antenna structures (such as masts) which the respective directive antennas are mounted onto. When an antenna structure moves, an antenna mounted onto that antenna structure also moves. Movement of the antenna in a longitudinal direction towards and away from the other node in the link and movement of the antenna in the form of rotation in the horizontal plane relative to the direction towards the other node in the link typically causes misalignment. Movement in the longitudinal direction may also be called tilt or rotation in the vertical plane. Rotation in the horizontal plane may also be called twist. The misalignment or movement causes fading dips that temporarily reduce link gain and hence a capability to sustain a certain communication rate (or fade margin necessary to achieve a targeted availability).

[0007] One way of mitigating the problem of movement of one or both of the antenna structures is to provide one or both of the directive antennas with a misalignment / movement compensation system. Such a system should be able to detect the sway or movement of the associated antenna structure, compute a required compensation, and take action such as redirecting the beam of the directive antenna mounted on the associated antenna structure.

[0008] Different approaches exist to detect and determine how much an antenna is moving or has rotated.

[0009] One approach is to rely on the antenna pattern to detect the angle of arrival, which is equivalent to the movement of the antenna in a fixed-service point-to-point system. The radio receiver is used as a sensor to detect the received signal strength (RSS), which is then used to determine the direction of the other node of the communication link.

[0010] One example of using the antenna pattern is a conical scanning system. In such a system, the beam of an antenna is rotated rapidly around the boresight direction. This generates an amplitude modulated signal which may be used to extract the angle of arrival of the antenna. If only lateral movement needs to be detected, for example a mast that only swings in the vertical plane including the two masts of the link, the system has to scan quickly up and down to find the direction of the transmitter at the other side of the communication link.

[0011] One example of using the antenna pattern is using a mono-pulse system. Such a system may track a target, or detect antenna movement, by means of multiple fixed beams. The system uses at least four feed antennas in combination with a feed network to sum and difference beams which are used to generate an error signal which in turn may be used to calculate the angle of arrival.

[0012] However, methods relying on RSS and a moving antenna pattern require fast beam scanning. This poses tough requirements on the durability of the antenna system, especially if the beam steering involves mechanically moving parts. In addition, any method that entails scanning the antenna pattern to find the direction of the receiver has the drawback that it will cause fluctuation of the RSS, which may reduce the link gain, which impacts link performance such as capacity, availability, and distance. Mono-pulse systems require multiple feed antennas, a comparator network and additional radio frequency (RF) circuity (e.g., downconverter, oscillators, etc.) to compute the error signals. These add significant cost, complexity, and losses.

[0013] Another approach to detect and determine how much an antenna is moving is using an inertial measurement unit (I MU) to detect antenna movement, and steering the beam of the antenna based on the motion sensor output.

[0014] However, IMUs with sufficiently fine resolution are expensive and may be overly sensitive to vibrations of the antenna or mounting pole. Sensor impairments such as sensor drift may make the beam steering unreliable.

[0015] Considering the disadvantages mentioned above, there is a need for improved ways of compensating for movement of an antenna structure having an antenna mounted thereto.

[0016] SUMMARY

[0017] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem. An object is to provide improved wireless communications networks. In particular, an object is to provide improved ways for compensating movement of an antenna structure having an antenna.

[0018] This object is obtained at least in part by a method for compensating a movement of a first antenna structure having a first antenna mounted thereto. The first antenna is configured to communicate with a second antenna over a wireless communication channel. The method comprises obtaining, from a radar or a lidar attached to the first antenna structure, data indicative of an offset position of the radar or the lidar relative to one or more fixed references for the first antenna structure. The method further comprises estimating the movement of the first antenna structure by comparing the offset position of the radar or the lidar to a set position of the radar or the lidar relative to the one or more fixed references. The method also comprises controlling a beam direction of the first antenna to compensate for the estimated movement of the first antenna structure. The data from the data from the radar or the lidar enables an accurate estimation of the movement of the first antenna structure. Consequently, an accurate compensation for the movement may be obtained. Therefore, the disclosed method provides improved wireless communications networks.

[0019] The estimated movement of the first antenna structure, via the data from the radar or the lidar, enables estimating a change of the beam direction of the first antenna relative to a reference direction (or desired direction) of the first antenna, which may be the direction that maximizes the link gain towards the second antenna, with relative high accuracy. With such information, the beam direction of the first antenna can be controlled (i.e., redirected) to maintain the maximum link gain. The beam direction of the first antenna may be controlled in a reactive fashion based on the estimated movement of the first antenna structure. For example, a current change in beam direction of the first antenna is estimated and the beam direction is thereafter controlled to compensate for that change. Alternatively, or in combination of, the beam direction of the first antenna may be controlled in a proactive fashion based on the estimated movement of the first antenna structure. For example, the estimated change of beam direction of the first antenna may include a change rate, where the beam direction is controlled to compensate for the change rate.

[0020] Using available radars and lidars, the accuracy of the estimated movement of the first antenna structure enables an accurate estimation of a change in the beam direction of the first antenna better than 0.1 degrees. Furthermore, the available radars and lidars enable a high time resolution of the estimated movement of the first antenna structure. Thus, the disclosed method enables compensation for both fast and slow changes of the movement of the first antenna structure. Slow changes may arise due temperatures variations caused by sunlight, and for fast changes may arise due to a wind load on the antenna structure.

[0021] The disclosed method does not require any inertial measurement units (IMUs) to estimate the movement of the first antenna structure. In some embodiments, however, an IMU is additionally comprised in the first antenna structure for complementing the estimation of the movement of the first antenna structure. The disclosed method enables relaxed requirements of such an IMU. For example, an inexpensive and less accurate IMUs may be used. In particular, slow movements of the first antenna structure may be estimated using the IMU and faster movements of the antenna structure may be estimated using the data from the radar or the lidar.

[0022] There is also disclosed herein a node for compensating a movement of a first antenna structure having a first antenna mounted thereto. The node is associated with the above-discussed advantages. The first antenna is configured to communicate with a second antenna over a wireless communication channel. The node comprises a processing circuitry and a memory. The processing circuitry is configured to obtain, from a radar or a lidar attached to the first antenna structure, data indicative of an offset position of the radar or the lidar relative to one or more fixed references for the first antenna structure. The processing circuitry is further configured to estimate the movement of the first antenna structure by comparing the offset position of the radar or the lidar to a set position of the radar or the lidar relative to the one or more fixed references. The processing circuitry is also configured to control a beam direction of the first antenna to compensate for the estimated movement of the first antenna structure. There is also disclosed herein a computer program product comprising instructions which, when executed on at least one processing circuitry, cause the at least one processing circuitry to carry out the method according to the discussion above. The computer program is associated with the above-discussed advantages.

[0023] There is also disclosed herein a computer program carrier carrying a computer program product according to the discussion above, wherein the computer program carrier is one of an electronic signal, optical signal, radio signal, or computer-readable storage medium. The computer program carrier is associated with the above-discussed advantages.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] With reference to the appended drawings, below follows a more detailed description of embodiments of the present disclosure cited as examples. In the drawings:

[0026] Figures 1 A and 1 B show schematic illustrations of different scenarios of a wireless communications network;

[0027] Figure 2 shows a schematic illustration of a wireless communications network;

[0028] Figure 3 illustrates an antenna structure with an antenna;

[0029] Figures 4A and 4B illustrate image content from a radar or a lidar at two respective time instances;

[0030] Figure 5 is a flow chart illustrating a method;

[0031] Figure 6 is a flow chart illustrating a method;

[0032] Figure 7 schematically illustrates a radio unit; and

[0033] Figure 8 schematically illustrates a remote data processing unit.

[0034] DETAILED DESCRIPTION

[0035] The present disclosure is described below with reference to the accompanying drawings, in which certain aspects of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects 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 present disclosure to those skilled in the art. Like numbers refer to like elements throughout the description.

[0036] It is to be understood that the present disclosure is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. Figures 1A and 1 B depict different scenarios of a wireless communications network 100 in which embodiments herein may operate. In some embodiments, the wireless communications network 100 may be a radio communications network, such as, 6G, NR or NR+ telecommunications network. However, the wireless communications network 100 may also employ technology of any one of 3 / 4 / 5G, LTE, LTE-Advanced, WCDMA, GSM / EDGE, WiMax, UMB, GSM, or any other similar network or system. The wireless communications network 100 may also employ technology transmitting on millimeter-waves (mmW), such as, e.g. an Ultra Dense Network, UDN. In some embodiments, the wireless communications network 100 may also employ transmissions supporting WiFi transmissions, e.g. the wireless communications standard IEEE 802.11 ad or similar, or other non-cellular wireless transmissions.

[0037] The wireless communications network 100 comprises a first radio unit 125 associated with a first antenna 120. The first antenna 120 is a directive antenna. A directive antenna is an antenna that radiates or receives a larger amount of radio wave power in a specific direction compared to other directions. A directive antenna may also be called a directional antenna, a beam antenna, or a high-gain antenna. In contrast to a low-gain antenna, which is an antenna with a broad beam width, a directive antenna has a relatively narrow beam width. As an example, a directive antenna may have a 0.1 to 10 degrees half-power beam width. Other beam widths are also possible.

[0038] In Figures 1A and 1 B, the first antenna 120 is configured to communicate with a second antenna 150 in the wireless communications network 100 via a wireless communication channel. The second antenna 150 is associated with a second radio unit 155. The first radio unit 125 is thus capable of communicating with the second radio unit 155 over a wireless communications channel (which may also be called a radio link). The first radio unit 125 may transmit and receive data over an air or radio interface to / from the second radio unit 155. Similarly, the second radio unit 155 may transmit and receive data over the air or radio interface to / from the first radio unit 125.

[0039] The first and / or the second radio units 125, 155 may be arranged to communicate with a remote data processing unit 170, e.g. via a core network of the wireless communications network 100 and / or via high-capacity backhaul links (such as fiber optic cables). The remote data processing unit 170 may e.g. be a remote standalone server, a cloud-implemented server, a distributed server, dedicated data processing resources in a server farm, or similar.

[0040] In Figures 1A and 1 B, the second antenna 150 is a directive antenna. However, in embodiments disclosed herein, the second antenna 150 may be any type of antenna. Compensating misalignment of the first antenna 120 is desired irrespective whether the second antenna 150 is directive or omnidirectional.

[0041] As is further shown in Figure 1 A, a beam direction 121 of the first antenna 120 points toward the second antenna 150 and is aligned with a beam direction 151 of the second antenna 150. The beam direction of a directive antenna is the axis of maximum gain (i.e. the axis of maximum radiated power) of the directive antenna. The beam direction may also be called the antenna boresight.

[0042] The first antenna 120 is mounted on a first antenna structure 110. The second antenna 150 is mounted on a second antenna structure 140. An antenna structure is a structure designed to support antennas for telecommunications. An antenna structure may e.g. be guyed or self-supporting structure. An antenna structure may e.g. be in the form of a mast or a tower.

[0043] In Figures 1A and 1 B, the first radio unit 125 is attached to the first antenna 120 and the second radio unit 155 is attached to the second antenna 150. In general, however, the first radio unit 125 may be attached anywhere on the first antenna structure 110 or be arranged separately from the first antenna structure 110. In any case, the first radio unit 125 is arranged to transmit and receive radio signals via the first antenna 120, e.g., by the means of cables. Similarly, the second radio unit 155 may be attached anywhere on the second antenna structure 140 or be arranged separately from the second antenna structure 140. In any case, the second radio unit 155 is arranged to transmit and receive radio signals via the second antenna 150, e.g., by the means of cables.

[0044] In Figure 1A, the first and the second antenna structures 110, 140 are stationary at intended positions that align the beam direction 121 of the first antenna 120 with the beam direction 151 of the second antenna 150. In Figure 1 B, the first antenna structure 110 has swayed, i.e. moved, relative to its intended position, e.g., due to wind. As a consequence, the beam direction 121 of the first antenna 120 is tilted by an angle <p relative to the beam direction 121 of the first antenna 120 in Figure 1A. Due to the tilt, the beam direction 121 of the first antenna 120 is no longer aligned with the beam direction 151 of the second antenna 150.

[0045] When the first antenna structure 110 moves back and forth in the direction towards the second antenna 150, i.e., moving in a longitudinal direction, the communication link between the first and the second antennas 120, 150 may experience sway-induced fading. Longitudinal movement of the first antenna structure 110 typically causes the first antenna 120 to tilt relative to the second antenna 150, which results in a varying gain towards the second antenna 150 as the first antenna structure 110 is moving. Sideways sway of the first antenna structure 110 has less impact since a lateral sideways movement has less impact on the beam direction of the first antenna 120. Hence, the link gain between the first antenna 120 and the second antenna 150 remains relatively constant during sideways sway of the first antenna structure 110.

[0046] Figure 2 shows the wireless communications network 100 of Figure 1 B, with additional antennas. In particular, Figure 2 shows a third antenna 130 mounted on the first antenna structure 110 provided with an associated third radio unit 135, and a fourth antenna 160 mounted on the second antenna structure 140 provided with an associated fourth radio unit 165. A beam direction 131 of the third antenna 130 is not aligned with a beam direction 161 of the fourth antenna 160 due to the movement of the first antenna structure 110. In particular, the beam direction 131 of the third antenna 130 is tilted by an angle a relative to a line-of-sight direction to the fourth antenna 120. In Figure 2, an estimated movement of the first antenna structure 110 may be used to control the beam direction of the first antenna 120 and the beam direction of the third antenna 130 to compensate for the movement of the first antenna structure 110. The first and the third antennas 120, 130 of Figure 2 may be part of a MIMO system. In that case, the first antenna 120 and the third antenna 130 may share a single radio unit. As a part of developing the embodiments disclosed herein, it has been realized that movement of the first antenna structure 110 may accurately be estimated using a radar 111 or a lidar mounted to the first antenna structure 110. In Figures 1A and 1 B, a radar 111 is mounted on the first antenna structure 110. However, in the embodiments disclosed herein, the radar 111 may equivalently be a lidar. The radar 111 or the lidar is mounted such that it detects one or more fixed references (such as buildings) in the near or far surroundings of the first antenna structure 110. By comparing the offset position of the radar 111 or the lidar to a set position of the radar or the lidar relative to the one or more fixed references, movement of the first antenna structure 110 by may be estimated. The beam direction of the first antenna 120 may subsequently be controlled to compensate for the estimated movement of the first antenna structure 110.

[0047] The radar 111 or the lidar may be mounted anywhere on the first antenna structure 110. If the first antenna structure

[0048] 110 only comprises a single antenna mounted thereto, the radar 111 or the lidar is advantageously arranged on the single antenna or adjacent to the single antenna on the first antenna structure 110. This facilitates controlling the beam direction of the single antenna to compensate for movement of the first antenna structure 110.

[0049] The beam direction of the first antenna 120 may, e.g., be controlled by mechanically steering the first antenna 120. Controlling the beam direction may also be called sweeping the beam. The mechanical steering may e.g. be performed by controlling a two-dimensional rotating platform onto which the first antenna 120 is arranged. If the first antenna is a reflector antenna comprising a feed antenna illuminating a reflector (i.e., a metallic surface of some shape, such as parabolic), the mechanical steering may be performed by moving the feeder antenna relative to the reflector. Another way of mechanically steering a reflector antenna is to move the reflector or a sub-reflector in a multi-antenna system relative to the antenna structure.

[0050] Alternatively, or in combination of, if the first antenna 120 is in the form of an electronically steered array (ESA) antenna, the beam direction may, e.g., be controlled by controlling individual antenna elements in the ESA antenna. Herein, controlling the beam direction of the first antenna 120 in such an electronic way, without mechanical means, is referred to as electrically steering the first antenna 120.

[0051] The first radio unit 125 may estimate the movement and the antenna structure 110 and subsequently control the beam direction of the first antenna. Alternatively, the movement and the antenna structure 110 is estimated by the remote data processing unit 170, which thereafter communicates control signals for controlling the beam direction of the first antenna 120 to the first radio unit 125.

[0052] Figure 3 illustrates the first antenna structure 110 with the first antenna 120 and the third antenna 130. The radar

[0053] 111 is mounted on the first antenna 120. It should be noted that the radar 111 may equivalently be a lidar in the embodiments disclosed herein. In the vicinity of the first antenna structure 110 (more particularly within the detection range of the radar 11 1 or the lidar), there is a mountain 391 and a building 392. The mountain 391 and the building 392 are assumed to be stationary relative to the surroundings of the first antenna structure 110. When the first antenna structure 110 moves relative to its surroundings (such as sways or twists), the radar 111 or the lidar moves relative to the mountain 391 and the building 392. By observing the position of the radar 111 or the lidar relative to the mountain 391 and the building 392, movement of the first antenna structure 110 may be estimated. The mountain 391 and the building 392 are fixed references for the first antenna structure 110. The mountain 391 being a fixed reference may mean the whole mountain 391 , a part of the mountain 391 , or a point on the mountain 391 being used as a reference. The same applies for the building 392 or any object or structure used as a fixed reference. The fixed references can be high-reflective parts of the environment at the used radar operational frequency. Furthermore, a reflective reference part that have purposely been arranged in the surroundings of the first antenna structure 110 (such as on a building) can be used as a fixed reference. For example, a corner reflector attached to a building may be used as a fixed reference.

[0054] The radar 111 or the lidar may be configured to provide data indicative of an offset position of the radar 111 or the lidar relative to one or more fixed references for the first antenna structure 110. The offset position of the radar 111 or the lidar may be relative to a set position (which may also be called a reference position) of the radar 111 or the lidar, such as the positon the radar 111 or the lidar has when the first antenna structure 110 is not moving relative to the surroundings of the first antenna structure 110. Movement of the first antenna structure 110 may subsequently be estimated by comparing the offset position of the radar 111 or the lidar to the set position of the radar 111 or the lidar relative to the one or more fixed references.

[0055] In Figure 3, the radar 111 provides the data by transmitting electromagnetic energy towards the fixed references, and thereafter receiving electromagnetic energy that has been reflected by the fixed references. In particular, the radar transmits electromagnetic energy 381 towards the mountain 391 , and receives electromagnetic energy 382 that has been reflected from the mountain 391. Furthermore, the radar transmits electromagnetic energy 383 towards the building 392, and receives electromagnetic energy 384 that has been reflected from the building 392.

[0056] The radar 111 may comprise a plurality of sub radar units arranged to observe the surroundings of the first antenna structure 110 (e.g. in different directions). Similarly, the lidar may comprise a plurality of sub lidar units arranged to observe the surroundings of the first antenna structure 110 (e.g. in different directions). The different sub radar units and / or the different sub lidar units may be arranged such that they are directed towards different fixed references. However, some or all of the different sub radar units and / or the different sub lidar units may be arranged such that they are directed towards one or more of the same fixed references. The different sub radar units and / or the different sub lidar units may be arranged on different parts of the first antenna structure 110, which may improve the estimation of movement of the first antenna structure 110.

[0057] Figures 4A and 4B illustrate image data from a radar 111 at two respective time instances. In these figures, the radar is a so-called 4D radar, which maps object in a 3D environment. The fourth dimension refers to time observations used to determine relative speeds of the objects in the environment. A 4D radar typically uses an antenna array to detect relative positions and relative speeds of objects in the environment. In Figure 4A, the radar 111 is positioned in a first position relative to the surroundings of the first antenna structure 110, and the image shows observations of the environment at a first time instance. The radar 111 detects a first relative position 411 and first relative speed of a fixed reference 493 in the form of a tree. The image also shows detected bats 494.

[0058] In Figure 4B, the radar 111 is positioned in a second position relative to the surroundings of the first antenna structure 110, and the image shows observations of the environment at a second time instance. The radar 111 detects a second relative position 412 and second relative speed of the fixed reference 493. The image also shows the bats 494, which are located at a different position relative to the surroundings and the radar 111 compared to Figure 4A.

[0059] The scenario of Figure 4A may constitute a reference position of the first antenna structure 110, e.g., the case when there is no wind and the beam direction of the first antenna 120 in a direction maximizing link gain. To estimate the movement of the radar, and in turn the movement of the first antenna structure 110, the data comprised in the image of Figure 4B may be compared with the data comprised in the image of Figure 4A.

[0060] The detected bats 494 are preferably removed before estimating the movement of the first antenna structure 110 since they are not stationary relative to the surroundings of the first antenna structure 110. If multiple fixed references are detected in the radar image, the majority of the fixed references should indicate a movement in the same direction and magnitude. For example, any reference deviating from an average by more than a threshold may be removed.

[0061] Figure 5 illustrates a method 500 for compensating a movement of a first antenna structure 110 having a first antenna 120 mounted thereto. The method 500 may be performed by a radio unit 125 associated with the first antenna 120 as shown in Figures 1A, 1 B, and 2, or by a remote data processing unit 170 as shown in Figures 1A, 1 B, and 2. The method 500 may comprise a number of actions listed below.

[0062] Action 510. The method 500 comprises obtaining a present radar or lidar image. The image comprises one or more fixed references for the first antenna structure 110 points. The reference points may be defined during installation of the first antenna or by machine learning model trained to provide one or more fixed references based on data from the radar 111 or the lidar. The fixed references are continuously updated for each complete loop in the regulation loop. Multiple reference points enables a higher confidence of a movement compensation value. A high confidence is preferable when first antenna structure 110 moves such that the beam direction of the first antenna sways in the order of 2 degrees or more. Depending on antenna gain, 2 degrees or more constitute a difference between traffic is up and running and a traffic loss for many wireless communication links using directive antennas.

[0063] Action 520. The method 500 comprises comparing the present image with the fixed references from the previous regulation loop (i.e., Action 570). During Action 520, the latest obtained image at Action 510 is compared to the stated reference points at Action 570. If there is no difference from the reference points at Action 510 and the reference points at Action 570, then no movement has occurred and a new image data is captured at Action 510. If there is a difference between the reference points at Action 510 and the he reference points at Action 570, the method proceeds to Action 530.

[0064] The majority of the fixed references should indicate a movement in the same direction and magnitude. If only one fixed reference is moving, it is likely that the one fixed reference is moving (relative to the surroundings of the first antenna structure 110) and not the first antenna structure 110. References that are moving relative to the surroundings of the first antenna structure 110 may be classified as a moving objects, and should preferably be removed from the image data.

[0065] Action 530. The method 500 comprises removing moving objects. Information from stochastic moving objects is removed in order not to interfere the later calculations. Note that a point in the image may be

[0066] Action 540. The method 500 comprises estimating compensation values for the first antenna to compensate for the estimated movement of the first antenna structure 110. The compensation values includes a change in azimuth angle and altitude angle relative to a beam direction of the first antenna that provides maximum gain, as well as change rates of such angles. The compensation values are estimated based on the present radar or lidar image. The compensation values may be seen as a parametrization of the movement of the first antenna structure 110.

[0067] The usage of the speed and direction change (that is included in the radar image) opens for prediction and a proactive compensation for the movement of the first antenna structure 110. Furthermore, by using several sub radars units and / or sub lidar units, it is possible to increase the accuracy of the compensation values. Alternatively, or in combination of, it is possible to use IMUs to further enhance the accuracy of the compensation values.

[0068] The radar or lidar image may be used to estimate compensation values for multiple antennas on the first antenna structure 110.

[0069] The radar or lidar image may capture of the second antenna 150 of the wireless communication channel. In that case, movement of the second antenna 150 can be detected, and compensation values for the second antenna 150 can be estimated and communicated to the second antenna 150 from the first antenna 120.

[0070] Action 550. The method 500 comprises setting a needed motion, where the compensation values from Action 540 are used provided to compensation equipment (e.g., electric motors redirecting the beam of the first antenna 120).

[0071] Action 560. The method 500 comprises detecting fixed references, where one or more fixed references are detected in the image for usage in future loops of the method. This may be done via a machine-learning model. It has been found that a suitable number of fixed references for accurate compensation is more than six.

[0072] Action 570. The method 500 comprises stating fixed reference points, where fixed references from Action 5602 are selected, e.g., by using noise cancellation in order to get accurate reference points. The stating fixed reference points shall be considered as calibration scenario and may be initiated during a stable scenario of the first antenna structure 110 (i.e., only minor movements of the first antenna structure 110) with a stable connection between the first antenna and the second antenna (which may be determined using available data rate). Furthermore, the compensation equipment for the alignment may be associated with a certain range of possible compensation values (e.g. a possible of azimuth angles). Therefore, in the case the compensation equipment often operates near to a limit, an alarm may be triggered that indicates that a new manual realignment of the antenna should be performed.

[0073] Figure 6 illustrates a method 600 for enabling compensation of a movement of a first antenna structure 110 having a first antenna 120 mounted thereto. The first antenna 120 is configured to communicate with a second antenna 150 over a wireless communication channel. The method 600 may be performed by a radio unit 125 associated with the first antenna 120 as shown in Figures 1 A, 1 B, and 2, or by a remote data processing unit 170 as shown in Figures 1 A, 1 B, and 2. The method 600 may comprise a number of actions listed below.

[0074] The method 600 is particularly suitable when at least the first antenna 120 is a directive antenna. However, in practice, most antennas have a non-constant radiation pattern and may benefit to some extent if it is directed to compensate movement of the first antenna structure 110 such that the link gain is maximized. As mentioned, the second antenna 150 may be a directive antenna or an omnidirectional antenna.

[0075] Action 610. The method 600 comprises obtaining, from a radar 111 or a lidar attached to the first antenna structure 110, data indicative of an offset position of the radar 111 or the lidar relative to one or more fixed references 391, 392, 493 for the first antenna structure 110.

[0076] A radar is a type of radiolocation system utilizing radio waves to determine parameters such as distance, angle, and velocity of objects relative to the radar. Lidar is an acronym for "light detection and ranging", and uses electromagnetic waves (e.g. at wavelengths in the range 500 - 1500 nanometers) to determine parameters such as distance and angle of objects relative to the lidar.

[0077] The radar 1 11 or the lidar may be attached to the first antenna structure 110 in a stationary fashion. In that case, the radar 111 or the lidar may be directed to observe a portion of the surroundings of the first antenna structure 110. However, the radar 111 or the lidar may comprise mechanical means for redirecting (such as rotating) the radar 111 or the lidar relative to the first antenna structure 110 such that different portions of the surroundings of the first antenna structure 110 may be observed. The radar 110 may further, or alternatively, be electronically steerable (e.g., using beam steering of an array antenna of the radar 111).

[0078] The radar 111 may comprise a plurality of sub radar units arranged to observe the surroundings of the first antenna structure 110 in different directions. Similarly, the lidar may comprise a plurality of sub lidar units arranged to observe the surroundings of the first antenna structure 110 in different directions. For example, the radar 111 may comprise two sub radar units arranged such their respective boresights are perpendicular.

[0079] The radar 111 or the lidar attached to the first antenna structure 110 may be a so-called "active” radar or lidar. Thus, in some embodiments, the obtaining 610 data comprises Actions 611 and 612. Action 611. The method 600 may comprise transmitting electromagnetic energy, by the radar 111 or the lidar, towards the one or more fixed references 391 , 392, 493 for the first antenna structure 110.

[0080] Action 612. The method 600 may comprise receiving electromagnetic energy, by the radar 111 or the lidar, as reflected and / or scattered by the one or more fixed references 391 , 392, 493 for the first antenna structure 110. The reflected and / or scattered electromagnetic energy comprises the transmitted electromagnetic energy as reflected and / or scattered by the one or more fixed references 391 , 392, 493.

[0081] In some embodiments, the data from the radar 111 or the lidar is indicative of respective distances of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar, where the movement of the first antenna structure 110 is estimated based on the respective distances of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar.

[0082] If only a single fixed references is observed, the relative distance between that single fixed references can be observed and compared to a reference value to obtain a rough estimation of the movement of the first antenna structure 110. However, if two or more fixed references are observed, their respective relative distance may be used to obtain a more accurate estimation of the movement of the first antenna structure 110. It has been found that a suitable number of fixed references for accurate compensation is more than six.

[0083] In some embodiments, the data from the radar 111 or the lidar is indicative of respective angles of the one or more fixed references 391 , 392, 493 relative to the radar 1 11 or the lidar, where the movement of the first antenna structure 110 is estimated based on the respective angles of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar.

[0084] In some embodiments, the data from the radar 111 or the lidar is indicative of respective velocities of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar, where the movement of the first antenna structure 110 is estimated based on the respective velocities of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar.

[0085] The respective velocities may, e.g., be obtained by observing relative distances the one or more fixed references 391 , 392, 493 over time.

[0086] The relative distances of the one or more fixed references 391 , 392, 493 enable an estimation of a current position of the first antenna structure 110 in its movement. Such an estimation may be used to control the beam direction of the first antenna to reactively compensate for the movement of the first antenna structure 110. The relative velocities of the one or more fixed references 391 , 392, 493 enable an estimation of a change rate of the position of the first antenna structure 110 in its movement. Such an estimation may be used to control the beam direction of the first antenna to proactively compensate for the movement of the first antenna structure 110.

[0087] The offset position of the radar 111 or the lidar relative to the one or more fixed references 391 , 392, 493 for the first antenna structure 110 is called "offset” since it is relative to set position of the radar 111 or the lidar relative to the one or more fixed references 391 , 392, 493 for the first antenna structure 110. The set position may also be called a reference position. Furthermore, the offset position of the radar 111 or the lidar is a position of the radar 111 or the lidar during the movement of the first antenna structure 110 relative to the set position. The set position of the radar 111 or the lidar may be the position the radar 111 or the lidar has when the first antenna structure 110 is not moving. The set position of the radar 111 or the lidar may be defined during installation of the first antenna structure 110, the first antenna 120, and / or the radar 111 or the lidar. Alternatively, or in combination of, the set position of the radar 111 or the lidar may be determined by observing the one or more fixed references 391 , 392, 493 over time.

[0088] If the data is indicative of an offset position of the radar 111 or the lidar relative to a plurality of fixed references 391 , 392, 493 for the first antenna structure 110, the data may be in the form of image data comprising a mapping of the plurality of fixed references 391 , 392, 493 in a 3D environment.

[0089] The one or more fixed references 391 , 392, 493 for the first antenna structure 110 are preferably stationary with respect to the surroundings of the first antenna structure 110. The mountain 391 and the building 392 of Figure 3 are examples of fixed references. Other examples are stationary infrastructure objects such as bridges, road signs, traffic lights etc. A fixed reference may include an object, a part of the object, or a point on the object.

[0090] In some embodiments, the at least one of the one or more fixed references 391 , 392, 493 comprises a retroreflector. A retroreflector is a surface or device that reflects electromagnetic energy back to its source with minimum scattering. A corner reflector is an example of a retroreflector. The retroreflector may be arranged in the surroundings of the first antenna structure 110 during installment of the radar 111 or the lidar. A retroreflector enables obtaining an accurate estimation of the offset position of the radar 111 or the lidar.

[0091] In general, the one or more fixed references 391 , 392, 493 for the first antenna structure 110 may be defined during installment of the radar 111 or the lidar. For example, a fixed reference may be selected by pointing a lidar such that it only observes that fixed reference during installment of that lidar.

[0092] Alternatively, or in combination of, the one or more fixed references 391 , 392, 493 for the first antenna structure 110 are obtained from a machine-learning model trained to provide one or more fixed references 391 , 392, 493 based on data from the radar 111 or the lidar. The machine-learning model may, e.g., be trained using reinforcement learning. In that case, an IMU may be used to provide reference values of the movement of the first antenna structure 110, and the machine-learning model may be trained to identify fixed references 391 , 392, 493 such that the offset position of the radar 111 or the lidar relative to the identified fixed references 391 , 392, 493 enables an estimation of the movement of the first antenna structure 110 that corresponds to the reference values.

[0093] Action 620. The first antenna structure 110 may be provided with an IMU. In that case, the method 600 may comprise obtaining 620 a signal indicative the movement of the first antenna structure 110 from the IMU. The signal from the IMU may be used as additional input to the controlling of the beam direction 121 of the first antenna 120, which is discussed in further detail below. The IMU may measure and report any of the unit's specific force, angular rate, and possibly orientation. The IMU may in general comprise any of an accelerometer, a gyroscope, and a magnetometer. Actions 631, 632, and 633. The method may comprise: identifying 631 a set of one or more fixed references 391, 392, 493 for the first antenna structure 110 in the data from the radar 111 or the lidar; estimating 632 respective velocities of the identified set of one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar; and selecting 633 a subset of one or more fixed references 391 , 392, 493 from the identified set of one or more fixed references 391 , 392, 493 based on the estimated respective velocities.

[0094] A majority of the fixed references should indicate a movement in the same direction and magnitude. If only one fixed reference is moving, it is likely that such a fixed reference is moving and not the first antenna structure 110. Thus, the subset of one or more fixed references may be selected based on whether their estimated respective velocities are within a threshold value from an average or median velocity of all velocities. Furthermore, fixed references may be determined to be stochastic moving references / objects, and may be omitted from the subset.

[0095] Action 640. The method 600 comprises estimating the movement of the first antenna structure 110 by comparing the offset position of the radar 111 or the lidar to a set position of the radar 111 or the lidar relative to the one or more fixed references 391 , 392, 493. In some examples, the estimated movement of the first antenna structure 110 is relative to when the first antenna structure 110 is stationary. The estimated movement of the first antenna structure 110 may be used for redirecting respective beams of one or more antennas mounted onto the first antenna structure 110.

[0096] Action 641. When the method comprises Actions 631 , 632, and 633, which includes selecting a subset of one or more fixed references, the estimating 640 the movement of the first antenna structure 110 may comprise comparing 641 the offset position of the radar 111 or the lidar relative to the subset of one or more fixed references 391 , 392, 493 to the set position of the radar 111 or the lidar relative to the subset of one or more fixed references 391 , 392, 493. In this way, a more accurate estimation of the movement of the first antenna structure 110 is obtained.

[0097] Action 650. The method 600 may comprise estimating an angle of the beam direction 121 of the first antenna 120 relative to a reference direction based on the estimated movement of the first antenna structure 110.

[0098] The angle may comprise an azimuth and / or an elevation angle of the of the beam direction 121 of the first antenna 120 relative to a reference direction. The angle may, e.g., be estimated from the movement of the first antenna structure 110 using trigonometry based on the dimensions of the first antenna structure 110, the position of the first antenna, and the position of the radar 111 or the lidar. However, more complex models of the antenna structure, which e.g. captures non-linear behavior of the angle versus movement of the first antenna structure 110, may be alternatively be used. In particular, the angle may be estimated from an empirical or a physical model describing the angle of the beam direction 121 of the first antenna 120 relative to the reference direction versus movement of the first antenna structure 110. An empirical model is a model formed by observation and experiment. A physical model is model based on physical properties of the antenna structure, such as dimensions, antenna placement, bending properties of the antenna structures etc. The empirical or a physical model takes the movement of the first antenna structure 110 as input, and outputs the angle. How the angle is affected by the movement of the first antenna structure 110 may depend, e.g., on temperature differences in the first antenna structure 110. Consequently, the empirical or the physical model used to determine the angle may also depend on an estimated temperature of the first antenna structure 110 and / or its surroundings, and / or temperature differences in the first antenna structure 110. In some embodiments, sensors are used to determine temperature or temperature differences. Alternatively, or in combination of, an ambient temperature is signaled by the network based on whether reports.

[0099] The reference direction may be a line of sight from first antenna 120 to the second antenna 150. However, the reference direction may in general be the direction that yields the highest link gain, which may be different from the line of sight due to ducting and / or refractivity in the atmosphere. Refractivity in the atmosphere may bend the beam either up or down relative to the line of sight. This phenomenon is usually expressed by the so-called K-factor. In any case, the reference direction may be obtained from one or more previously received signals by the first antenna 120 transmitted from the second antenna 150. The one or more previously received signals may be selected based on their respective received signal strength. For example, a previously received signal with maximum received signal strength may be selected. In this way, the estimated angle may be used subsequently to redirect the beam direction of the first antenna 120 towards the direction providing maximum link gain.

[0100] Action 660. The method 600 comprises controlling a beam direction 121 of the first antenna 120 to compensate for the estimated movement of the first antenna structure 110. In this way, a higher link gain may be obtained. The beam direction 121 of the first antenna 120 may controlled in a reactive fashion, i.e., to compensate for a current state of the first antenna structure 110 in its movement, or in a proactive fashion, i.e., to compensate for a current state change rate of the first antenna structure 110 in its movement.

[0101] Action 661. If the angle of the beam direction 121 of the first antenna 120 is estimated according to Action 650, the controlling 660 of the beam direction 121 of the first antenna 120 may comprise controlling 661 the beam direction 121 of the first antenna 120 based on the estimated angle.

[0102] The estimated angle may be used to tilt the beam direction by an amount corresponding to the estimated angle, but with an opposite sign.

[0103] In some embodiments, the relation between movement of the antenna structure and the estimated angle is known from, e.g., a physical model of the first antenna structure 110. This may be used to directly control the beamsteering of the first antenna 120. In an optional subsequent step, fine tuning of the beam direction of the first antenna 120 may be done based on a received signal strength scan.

[0104] Action 662, 663, and 664. The method 600 may comprise tuning the beam direction of the first antenna 120 based on a received signal strength scan. The controlling 660 of the beam direction 121 of the first antenna 120 may iteratively comprise: receiving 662, by the first antenna 120, a signal transmitted from the second antenna 150; estimating 663 a received signal strength of the signal; and controlling 664 the beam direction 121 of the first antenna 120 based on the estimated received signal strength. The signal may be a reference signal. Such a reference signal may comprise a pilot sequence. The second antenna 150 may continuously send reference signals to the first antenna 120 that may be used to scan the beam direction of the first antenna 120 to find maximum received signal strength. In other words, the beam of the first antenna may be scanned until a maximum received signal level is obtained.

[0105] Action 665. The first antenna 120 may be mechanically steerable. In that case, the controlling 660 of the beam direction 121 of the first antenna 120 may comprise controlling 665 the beam direction 121 of the first antenna 120 by mechanically steering the first antenna 120.

[0106] Action 666. The first antenna 120 may be electronically steerable. In that case, the controlling 660 of the beam direction 121 of the first antenna 120 may comprise controlling 666 the beam direction 121 of the first antenna 120 by electrically steering the first antenna 120.

[0107] The first antenna 120 may also be an antenna being both mechanically and electronically steerable.

[0108] Action 667. If the signal from the IMU is obtained according to Action 620, the controlling of the beam direction 121 of the first antenna 120 may comprise controlling 667 the beam direction 121 of the first antenna 120 based on the obtained signal from the IMU. The signal from the IMU enables a more accurate estimation of movement of the first antenna structure 110. Furthermore, an inexpensive and less accurate IMUs may be used relative to a case where only an IMU is used to estimate motion of the first antenna structure 110 (without using the radar 111 or the lidar). Alternatively, or in combination of, slow movements of the first antenna structure 110 may be estimated using the IMU and faster movements of the antenna structure may be estimated using the radar 111 or the lidar.

[0109] The radar 111 or the lidar may at least partly be directed towards the second antenna 150 such that the data from the radar 111 or the lidar is indicative of an offset position of the second antenna 150 relative to the radar 111 or the lidar. In that case, the method 600 may comprise Actions 670 and 680.

[0110] Action 670. The method may comprise estimating the movement of the second antenna 150 using the estimated movement of the first antenna structure 110 and by comparing the offset position of the second antenna 150 to a set position of the second antenna 150 relative to the radar 111 or the lidar. The movement of the second antenna is relative to a set position of the second antenna (which may also be called a reference position), such as the position the second antenna has when its corresponding antenna structure is not moving. The movement of the first antenna structure 110 may be factored out from the offset position of the second antenna 150 relative to the radar 111 or the lidar to obtain the movement of the second antenna is relative to its set position.

[0111] Action 680. The method may comprise communicating the estimated movement of the second antenna 150 to the second antenna 150 over the wireless communication channel.

[0112] If the estimated movement of the second antenna has high enough resolution, the movement of the second antenna 150 may be compensated for, e.g., by controlling a beam direction of the second antenna based on the communicated movement of the second antenna. Thus, link gain may be improved. Alternatively, the estimated movement of the second antenna 150 may be communicated to the second antenna in the form of an alarm that indicates that the second antenna is misaligned.

[0113] There is also disclosed herein a node 125, 170 for enabling compensation of a movement of a first antenna structure 110 having a first antenna 120 mounted thereto. The first antenna is configured to communicate with a second antenna 150 over a wireless communication channel. The node may, e.g., be the first radio unit 125 or the remote data processing unit 170.

[0114] Figure 7 shows a schematic block diagram of embodiments of a first radio unit 125 and Figure 8 shows a schematic block diagram of embodiments of a remote data processing unit 170. The embodiments of the node 125, 170 may be considered as independent embodiments or may be considered in any combination with each other. It should also be noted that, although not shown in Figures 7 and 8, the node 125, 170 may comprise known conventional features for such devices, such as a power source like a battery or mains connection, or an antenna arrangement.

[0115] The node 125, 170 may comprise processing circuitry 710, 810 and a memory 720, 820. The processing circuitry

[0116] 710, 810 may comprise a receiving module 711 , 811 and a transmitting module 712, 812. The receiving module

[0117] 711 , 811 and the transmitting module 712, 812 may comprise radio frequency circuitry and baseband processing circuitry capable of transmitting and receiving a radio signal in the wireless communications network 100. The receiving module 711 , 811 and the transmitting module 712, 812 may also form part of a single transceiver. It should also be noted that some or all of the functionality described in the embodiments above as being performed by the node 125, 170 may be provided by the processing circuitry 710, 810 executing instructions stored on a computer-readable medium, such as, e.g. the memory 720, 820 shown in Figures 7 and 8, respectively. Alternative embodiments of the node 125, 170 may comprise additional components, such as, an obtaining module 713, 813, a estimating module 714, 814, and / or an controlling module 715, 815, responsible for providing functionality to support the embodiments of the node described herein.

[0118] The node 125, 170, the processing circuitry 710, 810, or the obtaining module 713, 813 is configured to obtain, from a radar 111 or a lidar attached to the first antenna structure 110, data indicative of an offset position of the radar 111 or the lidar relative to one or more fixed references 391 , 392, 493 for the first antenna structure 110.

[0119] The node 125, 170, the processing circuitry 710, 810, or the estimating module 714, 814 is configured to estimate the movement of the first antenna structure 110 by comparing the offset position of the radar 111 or the lidar to a set position of the radar 111 or the lidar relative to the one or more fixed references 391 , 392, 493.

[0120] The node 125, 170, the processing circuitry 710, 810, or the controlling module 715, 815 is configured to control a beam direction 121 of the first antenna 120 to compensate for the estimated movement of the first antenna structure 110.

[0121] In some embodiments, the node 125, 170, the processing circuitry 710, 810, or the estimating module 714, 814 is configured to estimate an angle of the beam direction 121 of the first antenna 120 relative to a reference direction based on the estimated movement of the first antenna structure 110. In that case, the node 125, 170, the processing circuitry 710, 810, or the controlling module 714, 814 may be configured to control of the beam direction 121 of the first antenna 120 by controlling the beam direction 121 of the first antenna 120 based on the estimated angle.

[0122] In some embodiments, the angle is estimated from an empirical or a physical model describing the angle of the beam direction 121 of the first antenna 120 relative to the reference direction versus movement of the first antenna structure 110.

[0123] In some embodiments, the reference direction is a line of sight from first antenna 120 to the second antenna 150.

[0124] In some embodiments, the reference direction is obtained from one or more previously received signals by the first antenna 120 transmitted from the second antenna 150.

[0125] In some embodiments, the node 125, 170, the processing circuitry 710, 810, or the obtaining module 713, 813 is configured to obtain the data by transmitting electromagnetic energy, by the radar 111 or the lidar, towards the one or more fixed references 391 , 392, 493 for the first antenna structure 110, and receiving electromagnetic energy, by the radar 111 or the lidar, as reflected and / or scattered by the one or more fixed references 391 , 392, 493 for the first antenna structure 110.

[0126] In some embodiments, the data from the radar 111 or the lidar is indicative of respective distances of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar, where the movement of the first antenna structure 110 is estimated based on the respective distances of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar.

[0127] In some embodiments, the data from the radar 111 or the lidar is indicative of respective velocities of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar, where the movement of the first antenna structure 110 is estimated based on the respective velocities of the one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar.

[0128] In some embodiments, the one or more fixed references 391 , 392, 493 for the first antenna structure 110 are obtained from a machine-learning model trained to provide one or more fixed references 391 , 392, 493 based on data from the radar 111 or the lidar.

[0129] In some embodiments, the node 125, 170 or the processing circuitry 710, 810 is configured to: identify a set of one or more fixed references 391, 392, 493 for the first antenna structure 110 in the data from the radar 111 or the lidar; estimate respective velocities of the identified set of one or more fixed references 391 , 392, 493 relative to the radar 111 or the lidar; and select a subset of one or more fixed references 391 , 392, 493 from the identified set of one or more fixed references 391 , 392, 493 based on the estimated respective velocities. In that case, the node 125, 170, the processing circuitry 710, 810, or the estimating module 714, 814 may be configured to estimate the movement of the first antenna structure 110 by comparing the offset position of the radar 111 or the lidar relative to the subset of one or more fixed references 391 , 392, 493 to the set position of the radar 111 or the lidar relative to the subset of one or more fixed references 391 , 392, 493. In some embodiments, the radar 111 or the lidar is at least partly directed towards the second antenna 150 such that the data from the radar 111 or the lidar is indicative of an offset position of the second antenna 150 relative to the radar 111 or the lidar. In that case, the node 125, 170, the processing circuitry 710, 810, or the estimating module 714, 814 may be configured to estimate the movement of the second antenna 150 using the estimated movement of the first antenna structure 110 and by comparing the offset position of the second antenna 150 to a set position of the second antenna 150 relative to the radar 111 or the lidar. The node 125, 170 or the processing circuitry 710, 810 may further be configured to communicate the estimated movement of the second antenna 150 to the second antenna 150 over the wireless communication channel.

[0130] In some embodiments, the at least one of the one or more fixed references 391 , 392, 493 comprises a retroreflector.

[0131] In some embodiments, the node 125, 170, the processing circuitry 710, 810, or the controlling module 715, 815 is configured to control the beam direction 121 of the first antenna 120 by iteratively: receiving, by the first antenna 120, a signal transmitted from the second antenna 150; estimating a received signal strength of the signal; and controlling the beam direction 121 of the first antenna 120 based on the estimated received signal strength.

[0132] In some embodiments, the first antenna 120 is mechanically steerable, and the node 125, 170, the processing circuitry 710, 810, or the controlling module 715, 815 is configured to control the beam direction 121 of the first antenna 120 by mechanically steering the first antenna 120.

[0133] In some embodiments, the first antenna 120 is electronically steerable, and the node 125, 170, the processing circuitry 710, 810, or the controlling module 715, 815 is configured to control the beam direction 121 of the first antenna 120 by electrically steering the first antenna 120.

[0134] In some embodiments, the first antenna structure 110 is provided with an I MU . In that case, the node 125, 170, the processing circuitry 710, 810, or the obtaining module 713, 813 may be configured to obtain a signal indicative the movement of the first antenna structure 110 from the IMU. The node 125, 170, the processing circuitry 710, 810, or the controlling module 715, 815 may further be configured to control of the beam direction 121 of the first antenna 120 based on the obtained signal from the IMU.

[0135] The methods disclosed herein may be implemented through one or more processors, such as the processing circuitry 710 in the first radio unit 125 depicted in Figure 7 or the processing circuitry 810 in the remote data processing unit 170 depicted in Figure 8, together with computer program code for performing the functions and actions of the embodiments herein. The program code may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 710, 810 in the node 125, 170. The computer program code may e.g. be provided as pure program code in the node 125, 170 or on a server and downloaded to the node 125, 170. Thus, it should be noted that the modules of the node 125, 170 may in some embodiments be implemented as computer programs stored in memory, e.g. in the memory 720 or 820 in Figures 7 and 8, respectively, for execution by processors or processing modules, e.g. the processing circuitry 710 or 810 of Figures 7 and 8, respectively. Those skilled in the art will also appreciate that the processing circuitry 710, 810 and the memory 720, 820 described above may refer to a combination of analog and digital circuits, and / or one or more processors configured with software and / or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processing circuitry 710, 810 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

[0136] The description of the example embodiments provided herein have been presented for purposes of illustration. The description is not intended to be exhaustive or to limit example embodiments to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various alternatives to the provided embodiments. The examples discussed herein were chosen and described in order to explain the principles and the nature of various example embodiments and its practical application to enable one skilled in the art to utilize the example embodiments in various manners and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be appreciated that the example embodiments presented herein may be practiced in any combination with each other.

[0137] It should be noted that the word "comprising” does not necessarily exclude the presence of other elements or steps than those listed and the words "a” or "an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example embodiments may be implemented at least in part by means of both hardware and software, and that several "means”, "units” or "devices” may be represented by the same item of hardware.

[0138] It should also be noted that the various example embodiments described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

[0139] The embodiments herein are not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be construed as limiting.

Claims

CLAIMS1. A method (600) for compensating a movement of a first antenna structure (110) having a first antenna (120) mounted thereto, wherein the first antenna (120) is configured to communicate with a second antenna (150) over a wireless communication channel, the method (600) comprising: obtaining (610), from a radar (111) or a lidar attached to the first antenna structure (110), data indicative of an offset position of the radar (111) or the lidar relative to one or more fixed references (391 , 392, 493) for the first antenna structure (110); estimating (640) the movement of the first antenna structure (110) by comparing the offset position of the radar (111) or the lidar to a set position of the radar (111) or the lidar relative to the one or more fixed references (391 , 392, 493); and controlling (660) a beam direction (121) of the first antenna (120) to compensate for the estimated movement of the first antenna structure (110).

2. The method (600) according to claim 1 , comprising estimating (650) an angle of the beam direction (121) of the first antenna (120) relative to a reference direction based on the estimated movement of the first antenna structure (110), and wherein the controlling (660) of the beam direction (121) of the first antenna (120) comprises controlling (661) the beam direction (121) of the first antenna (120) based on the estimated angle.

3. The method (600) according to claim 2, wherein the angle is estimated from an empirical or a physical model describing the angle of the beam direction (121) of the first antenna (120) relative to the reference direction versus movement of the first antenna structure (110).

4. The method (600) according to claim 2 or 3, wherein the reference direction is a line of sight from first antenna (120) to the second antenna (150).

5. The method (600) according to claim 2 or 3, wherein the reference direction is obtained from one or more previously received signals by the first antenna (120) transmitted from the second antenna (150).

6. The method (600) according to any previous claim, wherein the obtaining (610) data comprises: transmitting (611) electromagnetic energy, by the radar (111) or the lidar, towards the one or more fixed references (391 , 392, 493) for the first antenna structure (110); and receiving (612) electromagnetic energy, by the radar (111) or the lidar, as reflected and / or scattered by the one or more fixed references (391 , 392, 493) for the first antenna structure (110).

7. The method (600) according to any previous claim, wherein the data from the radar (111) or the lidar is indicative of respective distances of the one or more fixed references (391 , 392, 493) relative to the radar (111) orthe lidar, and wherein the movement of the first antenna structure (110) is estimated based on the respective distances of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar.

8. The method (600) according to any previous claim, wherein the data from the radar (111) or the lidar is indicative of respective velocities of the one or more fixed references (391, 392, 493) relative to the radar (111) or the lidar, and wherein the movement of the first antenna structure (110) is estimated based on the respective velocities of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar.

9. The method (600) according to any previous claim, wherein the one or more fixed references (391 , 392, 493) for the first antenna structure (110) are obtained from a machine-learning model trained to provide one or more fixed references (391 , 392, 493) based on data from the radar (111) or the lidar.

10. The method (600) according to any previous claim, comprising identifying (631) a set of one or more fixed references (391 , 392, 493) for the first antenna structure (110) in the data from the radar (111) or the lidar; estimating (632) respective velocities of the identified set of one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar; and selecting (633) a subset of one or more fixed references (391 , 392, 493) from the identified set of one or more fixed references (391, 392, 493) based on the estimated respective velocities, wherein the estimating (640) the movement of the first antenna structure (110) comprises comparing (641) the offset position of the radar (111) or the lidar relative to the subset of one or more fixed references (391 , 392, 493) to the set position of the radar (111) or the lidar relative to the subset of one or more fixed references (391 , 392, 493).

11. The method (600) according to any previous claim, wherein the radar (111) or the lidar is at least partly directed towards the second antenna (150) such that the data from the radar (111) or the lidar is indicative of an offset position of the second antenna (150) relative to the radar (111) or the lidar, the method (600) comprising: estimating (670) the movement of the second antenna (150) using the estimated movement of the first antenna structure (110) and by comparing the offset position of the second antenna (150) to a set position of the second antenna (150) relative to the radar (111) or the lidar; and communicating (680) the estimated movement of the second antenna (150) to the second antenna (150) over the wireless communication channel.

12. The method (600) according to any previous claim, wherein the at least one of the one or more fixed references (391, 392, 493) comprises a retroreflector.

13. The method (600) according to any previous claim, wherein the controlling (660) of the beam direction (121) of the first antenna (120) iteratively comprises: receiving (662), by the first antenna (120), a signal transmitted from the second antenna (150);estimating (663) a received signal strength of the signal; and controlling (664) the beam direction (121) of the first antenna (120) based on the estimated received signal strength.

14. The method (600) according to any previous claim, wherein the first antenna (120) is mechanically steerable, and wherein the controlling (660) of the beam direction (121) of the first antenna (120) comprises: controlling (665) the beam direction (121) of the first antenna (120) by mechanically steering the first antenna (120).

15. The method (600) according to any previous claim, wherein the first antenna (120) is electronically steerable, and wherein the controlling (660) of the beam direction (121) of the first antenna (120) comprises: controlling (666) the beam direction (121) of the first antenna (120) by electrically steering the first antenna (120).

16. The method (600) according to any previous claim, wherein the first antenna structure (110) is provided with an inertial measurement unit, I MU, wherein the method (600) comprises: obtaining (620) a signal indicative the movement of the first antenna structure (110) from the IMU, wherein the controlling of the beam direction (121) of the first antenna (120) comprises controlling (667) the beam direction (121) of the first antenna (120) based on the obtained signal from the IMU.

17. A node (125, 170) for compensating a movement of a first antenna structure (110) having a first antenna (120) mounted thereto, wherein the first antenna (120) is configured to communicate with a second antenna (150) over a wireless communication channel, and wherein the node (125, 170) comprises a processing circuitry (710, 810) and a memory (720, 820), wherein the processing circuitry (710, 810) is configured to obtain, from a radar (111) or a lidar attached to the first antenna structure (110), data indicative of an offset position of the radar (111) or the lidar relative to one or more fixed references (391 , 392, 493) for the first antenna structure (110), estimate the movement of the first antenna structure (110) by comparing the offset position of the radar (111) or the lidar to a set position of the radar (111) or the lidar relative to the one or more fixed references (391 , 392, 493), and control a beam direction (121) of the first antenna (120) to compensate for the estimated movement of the first antenna structure (110).

18. The node (125, 170) according to claim 17, wherein the processing circuitry (710, 810) is configured to estimate an angle of the beam direction (121) of the first antenna (120) relative to a reference direction based on the estimated movement of the first antenna structure (110), and wherein the processing circuitry (710, 810) is configured to control of the beam direction (121) of the first antenna (120) by controlling the beam direction (121) of the first antenna (120) based on the estimated angle.

19. The node (125, 170) according to claim 18, wherein the angle is estimated from an empirical or a physical model describing the angle of the beam direction (121) of the first antenna (120) relative to the reference direction versus movement of the first antenna structure (110).

20. The node (125, 170) according to claim 18 or 19, wherein the reference direction is a line of sight from first antenna (120) to the second antenna (150).

21. The node (125, 170) according to claim 18 or 19, wherein the reference direction is obtained from one or more previously received signals by the first antenna (120) transmitted from the second antenna (150).

22. The node (125, 170) according to any of claims 17-21 , wherein the processing circuitry (710, 810) is configured to obtain the data by transmitting electromagnetic energy, by the radar (111) or the lidar, towards the one or more fixed references (391 , 392, 493) for the first antenna structure (110), and receiving electromagnetic energy, by the radar (111) or the lidar, as reflected and / or scattered by the one or more fixed references (391 , 392, 493) for the first antenna structure (110).

23. The node (125, 170) according to any of claims 17-22, wherein the data from the radar (111) or the lidar is indicative of respective distances of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar, and wherein the movement of the first antenna structure (110) is estimated based on the respective distances of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar.

24. The node (125, 170) according to any of claims 17-23, wherein the data from the radar (111) or the lidar is indicative of respective velocities of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar, and wherein the movement of the first antenna structure (110) is estimated based on the respective velocities of the one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar.

25. The node (125, 170) according to any of claims 17-24, wherein the one or more fixed references (391 , 392, 493) for the first antenna structure (110) are obtained from a machine-learning model trained to provide one or more fixed references (391 , 392, 493) based on data from the radar (111) or the lidar.

26. The node (125, 170) according to any of claims 17-25, wherein the processing circuitry (710, 810) is configured to identify a set of one or more fixed references (391 , 392, 493) for the first antenna structure (110) in the data from the radar (111) or the lidar, estimate respective velocities of the identified set of one or more fixed references (391 , 392, 493) relative to the radar (111) or the lidar, and select a subset of one or more fixed references (391 , 392, 493) from the identified set of one or more fixed references (391 , 392, 493) based on the estimated respective velocities, wherein the processing circuitry (710, 810) is configured to estimate the movement of the first antenna structure (110) bycomparing the offset position of the radar (111) or the lidar relative to the subset of one or more fixed references (391 , 392, 493) to the set position of the radar (111 ) or the lidar relative to the subset of one or more fixed references (391 , 392, 493).

27. The node (125, 170) according to any of claims 17-26, wherein the radar (111) or the lidar is at least partly directed towards the second antenna (150) such that the data from the radar (111) or the lidar is indicative of an offset position of the second antenna (150) relative to the radar (111) or the lidar, wherein the processing circuitry (710, 810) is configured to estimate the movement of the second antenna (150) using the estimated movement of the first antenna structure (110) and by comparing the offset position of the second antenna (150) to a set position of the second antenna (150) relative to the radar (111 ) or the lidar, and communicate the estimated movement of the second antenna (150) to the second antenna (150) over the wireless communication channel.

28. The node (125, 170) according to any of claims 17-27, wherein the at least one of the one or more fixed references (391, 392, 493) comprises a retroreflector.

29. The node (125, 170) according to any of claims 17-28, wherein the processing circuitry (710, 810) is configured to control the beam direction (121) of the first antenna (120) by iteratively: receiving, by the first antenna (120), a signal transmitted from the second antenna (150); estimating a received signal strength of the signal; and controlling the beam direction (121) of the first antenna (120) based on the estimated received signal strength.

30. The node (125, 170) according to any of claims 17-29, wherein the first antenna (120) is mechanically steerable, and wherein the processing circuitry (710, 810) is configured to control the beam direction (121) of the first antenna (120) by mechanically steering the first antenna (120).

31. The node (125, 170) according to any of claims 17-30, wherein the first antenna (120) is electronically steerable, and wherein the processing circuitry (710, 810) is configured to control the beam direction (121) of the first antenna (120) by electrically steering the first antenna (120).

32. The node (125, 170) according to any of claims 17-31 , wherein the first antenna structure (110) is provided with a inertial measurement unit, IMU, wherein the processing circuitry (710, 810) is configured to obtain a signal indicative the movement of the first antenna structure (110) from the IMU, wherein the processing circuitry (710, 810) is configured to control of the beam direction (121) of the first antenna (120) based on the obtained signal from the IMU.

33. The node (125, 170) according to any of claims 17-32, wherein the node is a radio unit (125) associated with the first antenna (120).

34. The node (125, 170) according to any of claims 17-32, wherein the node is a remote data processing unit (170).

35. A computer program product comprising instructions which, when executed on at least one processing circuitry (710, 810), cause the at least one processing circuitry (710, 810) to carry out the method (600) according to any of claims 1-16.

36. A computer program carrier carrying a computer program product according to claim 35, wherein the computer program carrier is one of an electronic signal, optical signal, radio signal, or computer-readable storage medium.

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