Uplink beam reconfiguration

Abstract

Embodiments of the present disclosure relate to uplink beam reconfiguration. A method includes: determining at least one misalignment angle between an initial uplink beam and a downlink beam between a user equipment and a network node according to an indication that an initial uplink beam between the user equipment and a network node is misaligned relative to a downlink beam between the network node and the user equipment; and reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam.

Description

Technical Field

[0001] Various example embodiments are directed to methods, apparatus, and computer programs for uplink beam reconfiguration. Background Art

[0002] In wireless telecommunications networks such as 5G networks, uplink beams and downlink beams are formed between user equipment and network nodes to support communication between the user equipment and the network nodes. Although there are techniques for configuring these uplink and downlink beams, poor communication performance may occur between the user equipment and the network nodes. Therefore, it is desirable to provide an improved technique to support communication between the user equipment and the network nodes. Summary of the invention

[0003] The scope of protection sought by various embodiments of the present invention is set out by the independent claims. Embodiments and features described in this specification that do not fall within the scope of the independent claims, if any, should be interpreted as examples useful for understanding the various embodiments of the present invention.

[0004] According to various but not all embodiments of the present invention, a method is provided, comprising: determining at least one misalignment angle between an initial uplink beam and a downlink beam based on an indication that an initial uplink beam between a user equipment and a network node is misaligned relative to a downlink beam between the network node and the user equipment; and reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam.

[0005] The method may comprise: receiving, at the user equipment, an indication from a network node; and / or determining, within the user equipment, an indication.

[0006] The indication may be an indication of a power difference between an expected received power level at the network node and an actual received power level at the network node.

[0007] The indication may include at least one of: a message from the network node indicating a power level difference; a message from the network node requesting uplink realignment; and a message from the network node requesting a change in uplink power level.

[0008] The method may comprise determining the misalignment angle based on pre-stored information, the pre-stored information relating the indicated value to the value of the misalignment angle.

[0009] The pre-stored information may relate the indicated values ​​to the values ​​of the misalignment angles for a plurality of initial uplink beams.

[0010] The pre-stored information may indicate a plurality of different misalignment angles for indicating, and the method may include selecting a minimum misalignment angle among the plurality of different misalignment angles as the misalignment angle.

[0011] The method may include reconfiguring an uplink beam based on the misalignment angle to produce a reconfigured uplink beam that avoids a transmission null along the misalignment angle.

[0012] The method may include reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having increased gain along the misalignment angle compared to an initial uplink beam.

[0013] The method may include reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having increased gain along all directions of the misalignment angle compared to the initial uplink beam.

[0014] The method may include reconfiguring an uplink beam based on a misalignment angle to produce a reconfigured uplink beam by at least partially forming a cone by rotating the misalignment angle in space, thereby producing a reconfigured uplink beam having increased gain along the misalignment angle compared to an initial uplink beam.

[0015] The initial uplink beam may have a primary transmission direction, and the method may include reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having a reduced gain along the primary transmission direction.

[0016] The initial uplink beam may have a current primary transmission direction, and the method may include reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam that is null along the current primary transmission direction.

[0017] The method may include reconfiguring the uplink beam by retaining all of the antenna array elements used to generate the initial uplink beam and applying changed antenna array configuration values ​​of all of the antenna array elements based on the misalignment angle to generate a reconfigured uplink beam.

[0018] The method may include reconfiguring the uplink beam by applying a changed antenna array configuration value based on the misalignment angle to produce a reconfigured uplink beam.

[0019] The method may include reconfiguring the uplink beam by applying changed antenna array phase shifter values ​​based on the misalignment angle to produce a reconfigured uplink beam.

[0020] The method may include reconfiguring the uplink beam by applying changed antenna array values ​​based on the misalignment angle to produce a plurality of sub-array uplink beams to create a reconfigured uplink beam.

[0021] The method may include determining the changed antenna array value based on pre-stored information, the pre-stored information relating the value of the misalignment angle to the value of the gain of the changed antenna array value.

[0022] The pre-stored information may relate values ​​of the misalignment angle to values ​​of the gain of a plurality of changed antenna array values.

[0023] The method may include selecting an altered antenna array value from among the plurality of altered antenna array values ​​that achieves a maximum gain improvement for the misalignment angle.

[0024] The pre-stored information may associate different ranges of values ​​of the misalignment angle with corresponding multiple changed antenna array values ​​for the range, and the method may include determining into which value range of the misalignment angle the misalignment angle falls and selecting one of the multiple changed antenna array values ​​corresponding to the range.

[0025] The at least one misalignment angle comprises a group of misalignment angles.

[0026] According to various but not all embodiments of the present invention, a computer program is provided, the computer program comprising instructions for causing an apparatus to perform at least the following operations: determining at least one misalignment angle between an initial uplink beam and a downlink beam based on an indication that an initial uplink beam between a user equipment and a network node is misaligned relative to a downlink beam between the network node and the user equipment; and reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam.

[0027] The computer program may include instructions for causing an apparatus to execute the above method.

[0028] According to various but not all embodiments of the present invention, a device is provided, comprising: a component for determining at least one misalignment angle between an initial uplink beam and a downlink beam based on an indication that an initial uplink beam between a user equipment and a network node is misaligned relative to a downlink beam between the network node and the user equipment; and a component for reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam.

[0029] The apparatus may include means for receiving, at the user equipment, an indication from the network node.

[0030] The apparatus may include means for determining an indication within a user equipment.

[0031] The indication may be an indication of a power difference between an expected received power level at the network node and an actual received power level at the network node.

[0032] The indication may include at least one of: a message from the network node indicating a gain difference; a message from the network node requesting uplink realignment; and a message from the network node requesting a change in uplink power level.

[0033] The means for determining may determine the misalignment angle based on pre-stored information, the pre-stored information relating the indicated value to the value of the misalignment angle.

[0034] The pre-stored information may relate the indicated values ​​to the values ​​of the misalignment angles for a plurality of initial uplink beams.

[0035] The pre-stored information may indicate a plurality of different misalignment angles for indicating, and the means for determining may select a minimum misalignment angle among the plurality of different misalignment angles as the misalignment angle.

[0036] The means for reconfiguring may reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam that avoids a transmission null along the misalignment angle.

[0037] The means for reconfiguring may reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having an increased gain along the misalignment angle compared to an initial uplink beam.

[0038] The means for reconfiguring may reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having increased gain along all directions of the misalignment angle compared to the initial uplink beam.

[0039] The component for reconfiguring can reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam by at least partially forming a cone by rotating the misalignment angle in space, thereby producing a reconfigured uplink beam having an increased gain along the misalignment angle compared to the initial uplink beam.

[0040] The initial uplink beam may have a primary transmission direction, and the means for reconfiguring may reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam having a reduced gain along the primary transmission direction.

[0041] The initial uplink beam may have a current primary transmission direction, and the means for reconfiguring may reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam nulled along the current primary transmission direction.

[0042] The reconfiguration component may reconfigure the uplink beam by retaining all of the antenna array elements used to generate the initial uplink beam and applying changed antenna array configuration values ​​of all of the antenna array elements based on the misalignment angle to generate the reconfigured uplink beam.

[0043] The means for reconfiguring may reconfigure the uplink beam by applying a changed antenna array configuration value based on the misalignment angle to produce a reconfigured uplink beam.

[0044] The means for reconfiguring may reconfigure the uplink beam by applying changed antenna array phase shifter values ​​based on the misalignment angle to produce a reconfigured uplink beam.

[0045] The means for reconfiguring may reconfigure the uplink beam by applying changed antenna array values ​​based on the misalignment angle to produce a plurality of sub-array uplink beams to create a reconfigured uplink beam.

[0046] The means for reconfiguring may determine the changed antenna array value based on pre-stored information relating the value of the misalignment angle to the value of the gain of the changed antenna array value.

[0047] The pre-stored information may relate values ​​of the misalignment angle to values ​​of the gain of a plurality of changed antenna array values.

[0048] The means for reconfiguring may select a changed antenna array value from among the plurality of changed antenna array values ​​that achieves a maximum gain improvement for the misalignment angle.

[0049] The pre-stored information may associate different ranges of values ​​of the misalignment angle with corresponding multiple changed antenna array values ​​for the range, and the component for reconfiguring may determine into which value range of the misalignment angle the misalignment angle falls and select one of the multiple changed antenna array values ​​corresponding to the range.

[0050] The at least one misalignment angle comprises a group of misalignment angles.

[0051] According to various but not all embodiments of the present invention, a device is provided, comprising logic operable to: determine at least one misalignment angle between an initial uplink beam and a downlink beam based on an indication that an initial uplink beam between a user device and a network node is misaligned relative to a downlink beam between the network node and the user device; and reconfigure the uplink beam based on the misalignment angle to produce a reconfigured uplink beam.

[0052] The apparatus includes logic operable to correspond to the apparatus described above and embodiments thereof.

[0053] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations of features other than those explicitly set out in the claims.

[0054] Where an apparatus feature is described as being operable to provide a function, it will be understood that this includes apparatus features that provide that function or that are adapted or configured to provide that function. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0056] Figure 1 Uplink / downlink beam correspondence and misalignment are shown;

[0057] Figure 2 shows the impedance mismatch within the user equipment;

[0058] Figure 3 The main processing blocks performed by the user equipment are shown;

[0059] FIG4 illustrates information related to azimuth offset angle relative to power for different configurations of a user equipment antenna array;

[0060] Figure 5 shows the gain performance of different user equipment antenna array configurations at different azimuth angles;

[0061] FIG6 shows the gain performance of different user equipment antenna array configurations at different azimuth angles;

[0062] Figure 7 shows different gains for different user equipment antenna array configurations at different azimuth angles;

[0063] FIG8 shows different gains under different multiple non-overlapping simultaneously active sub-array configurations;

[0064] Fig. 9shows different gains for different user equipment antenna array configurations at different azimuth angles;

[0065] Fig.10 Components of a user device are shown; and

[0066] Fig.11 Processing blocks performed by a user device are shown. DETAILED DESCRIPTION

[0067] Before discussing example embodiments in more detail, an overview will first be provided. Some embodiments provide a technique in which, typically after determining whether a trigger for misalignment has occurred, a misalignment of an uplink beam relative to a downlink beam between a user equipment and a network node is detected based on information available to the user equipment, a misalignment angle is determined based on the information, and the misalignment angle is then used by the user equipment to reconfigure the uplink beam to improve or mitigate the misalignment between the uplink beam and the downlink beam, thereby improving the transmission power received from the user equipment at the network node. The trigger may be provided externally, for example, by a message from the network node, or internally, for example, based on a timer or based on information within the user equipment. The misalignment angle may generally be considered to be a set of one or more misalignment angles, and typically two or more misalignment angles, oriented in different directions. For example, the misalignment angle may be determined, but the direction may be different based on the configuration of the antenna array; for a linear array, the misalignment may be in two possible directions, i.e., one side or the other side of the current beam configuration, but for a two-dimensional array such as a rectangular or square array, there may be more directions. The occurrence of the misalignment may be determined in a number of ways based on the indication of the misalignment, such as based on explicit messages received at the user equipment from the network node or other network nodes (such as other user equipment receiving transmissions from the user equipment) about the misalignment, based on existing messages from the network node about the strength and / or quality of the uplink, and / or based on information received or generated by the user equipment itself, for example, based on information about transmissions from other antenna arrays of the user equipment, or by measuring impedance mismatches in the user equipment. The user equipment typically stores information correlating or mapping indications received or generated by the user equipment to a set of possible misalignment angles, which is typically pre-stored by the user equipment or dynamically compiled by the user equipment through use. The stored information may then be used to determine a set of possible misalignment angles based on the received indications. The set of possible misalignment angles may then be used to reconfigure the uplink beam. Again, the user equipment typically stores information correlating or mapping the performance of different configurations of the antenna array of the user equipment at different azimuth angles (misalignment angles), which is typically pre-stored by the user equipment or dynamically compiled by the user equipment through use. The user equipment selects a different configuration of the antenna array of the user equipment so as to improve the directivity of the uplink beam towards the network node at the set of possible misalignment angles. This reconfiguration of the uplink beam at least attempts to avoid any transmission nulls along the set of possible misalignment angles towards the network node. The reconfiguration attempts to increase the gain of the uplink beam towards the network node. In some cases, this can be achieved by turning off some antenna elements to widen the uplink beam. In some cases, this can be achieved by reconfiguring the antenna array into sub-arrays.In some cases, this can be achieved by reducing power transmission or creating a null along the current transmission angle of the uplink beam (i.e., along the main transmission direction, typically 0° azimuth) and redeploying that power to increase power transmission along a set of possible misaligned angles and towards the network node. Thus, in some cases, rather than switching to a beamforming arrangement that uses fewer antennas to widen the uplink beam, all currently used antenna elements can continue to be used, but the shape of the beam is changed to redeploy the power more towards the misaligned angles. This significantly increases the amount of available power, which is particularly useful in power-constrained situations (such as when the user equipment is at the cell edge).

[0068] Uplink beam misalignment

[0069] Figure 1 Uplink / downlink beam correspondence and misalignment are shown. gNB 10 has uplink beam 15 and downlink beam 17. User equipment 20 has uplink beam 25 and downlink beam 27.

[0070] As in Figure 1 As can be seen in part (A) of FIG. 8 , uplink beam 25 and downlink beam 27 are corresponding (which means they are aligned and parallel), and they point to the corresponding uplink beam 15 and downlink beam 17 .

[0071] exist Figure 1 As can be seen in part (B) of the diagram, the beam correspondence of the user equipment is preserved because the uplink beam 25 and downlink beam 27 are still aligned and parallel, but now they are not pointing to the corresponding uplink beam 15 and downlink beam 17, which results in a suboptimal uplink and downlink with similar reduced gain on both the uplink and downlink.

[0072] Figure 1Part (C) in shows a misalignment between uplink beam 25 and downlink beam 27, because uplink beam 25 and downlink beam 27 are no longer aligned and parallel, but now uplink beam 25 and downlink beam 27 diverge at angle A. This misalignment may occur for various reasons and may occur dynamically in the field due to, for example, impedance changes of power amplifiers, low noise amplifiers and / or switches affected by temperature, design tolerances, operating power levels (which may cause small offsets), and power supply imbalances. In particular, mismatches towards the antenna or towards other amplifiers can affect the uplink and downlink directivities, causing the directivities of the beams towards the gNB 10 to be different. It will be appreciated that this is not limited to such a case and can include any type of undesirable change in the radio frequency (RF) performance of any component(s) associated with the antenna control circuitry(s), receiver chain(s), and transmitter chain(s). In addition, if the direction of the uplink beam 25 does not correspond to the downlink beam 27, power will ultimately not be received at the gNB 10. The beam misalignment problem is less severe for gNB 10 than for UE 20. This is because the degrees of freedom allocated to antenna design on gNB 10 are significantly higher than those on UE 10, where the mmWave antenna array will have to share volume with other electronic components and antennas for sub-6 GHz communications. Moreover, UE 10 has a number of constraints, such as supporting very large bandwidths for global coverage, and they are typically implemented with more cost-effective embedded components, compromising tolerance and resulting in impedance variations across different operating settings. As a result, the impedance of the receive and transmit chains may vary across different power and gain settings and vary in different ways, which means that even balancing the effects of any impedance mismatch will not help when the UE 20 adapts to the closed-loop power regulation of the gNB 10.

[0073] Therefore, uplink / downlink beam correspondence is preserved if the following conditions are met: the same antenna element weights for uplink and downlink result in the same beam gain and direction for uplink and downlink; the antenna element weights can be offset by pre-characterized values ​​to obtain the same beam gain and direction for uplink and downlink; two "codebooks" of beam weight vectors have been established, one for uplink and the other for downlink. Each beam weight vector in the uplink codebook is paired 1-1 with a beam weight vector in the downlink codebook so that a paired uplink beam weight vector and downlink beam weight vector have the same beam and gain direction. If these requirements are not met, the beam correspondence will be broken and the uplink will be misaligned, as shown in Figure 2. Figure 1 As shown in part (C) of FIG.

[0074] Impedance mismatch within the user equipment 20 may be Figure 2 See in more detail, Figure 2 is a simplified block diagram of the transmission and reception of the user equipment 20, showing different impedances towards the low noise amplifier and the power amplifier. The impedance at the individual elements in the antenna array Zant will vary depending on the required frequency and the configured main beam angular direction. In this way, each element will present a different impedance at any given time, which will affect the performance of the individual power amplifier PA and low noise amplifier LNA connected to that particular element. Compared with the low noise amplifier, the power amplifier is generally more sensitive to changes in load impedance, so the impact of changes in the power amplifier load impedance will not be captured in the beam alignment process because they only rely on the downlink, but as part of the calibration or configuration of the transmission beam, ensure that the control and configuration of the reception and transmission beam directions are aligned at the time of calibration / configuration. In addition, the improper behavior of the power amplifier is not only caused by changes in load impedance, but also related to power amplifier related factors, such as output power level, ambient temperature and potential gain mode. Therefore, the actual radiation pattern formed by the antenna array will be affected by the improper behavior of these different power amplifiers and low noise amplifiers, and even with the same array configuration (weight), it will result in different radiation patterns for the downlink and uplink. For some array / RF front-end configurations (line of sight at low power) these differences in radiation patterns may be negligible, while for other configurations (angular steering at high power) these differences in radiation patterns are severe and lead to beam non-correspondence when the configuration or calibration is insufficient for circuit conditions.

[0075] Despite the existence of an existing beam alignment process, this involves aligning downlink beam 17 with downlink beam 27 and then assuming that beam correspondence occurs at both gNB 10 and user equipment 20 because the optimal uplink beam alignment is considered to have been derived from the aligned downlink beams. However, as described above and shown in part (C) of the figure, even aligning downlink beam 17 with downlink beam 27 does not resolve the misalignment or mismatch of uplink beam 25 with uplink beam 15 because downlink beam 27 and uplink beam 25 are misaligned by a misalignment angle A. While the misalignment can be compensated for, this will potentially take a long time to perform and the overhead of attempting to realign all possibilities of uplink beam 25 may result in radio link failure. Therefore, some embodiments provide a simplified technique for realigning uplink beam 25 with downlink beam 27.

[0076] Uplink beam misalignment detection

[0077] Figure 3The main processing blocks performed by the user equipment 20 are shown, which automatically trigger asymmetric uplink downlink beamforming upon detection of misalignment of the uplink beam 25 and the downlink beam 27 in response to an internal or external trigger, to maximize the power of the uplink beam 25 received by the gNB 10 and reduce the risk of radio link failure. If no action is taken when misalignment is detected, it may result in significant gain loss and radio link failure.

[0078] Thus, after triggering, at block S10, an uplink beam 25 / downlink beam 27 misalignment or non-correspondence detection occurs. This detection may occur in a variety of different ways, for example, the user equipment 20 may receive a message from the gNB 10 that explicitly identifies that the uplink beam 25 is misaligned by a number of dB; the user equipment 20 may receive a message from the gNB 10 requesting uplink alignment by receiving a configuration for sounding reference signal (SRS) beam scanning, and the user equipment 20 interprets it as an indication that the uplink beam 25 is misaligned with the gNB 10, and in conjunction with the user equipment 20 applies an uplink beam 25 reconfiguration as a means for mitigating uplink loss and avoiding radio link failure; the user equipment 20 receives a message from one or more gNBs requesting uplink alignment. 10 autonomously interprets an indication (e.g., a power level request) regarding uplink beam 25 misalignment and, accordingly, initiates uplink beam 25 reconfiguration; user equipment 20 receives indications from other user equipments that they are receiving uplink beam 25; and / or user equipment 20 itself determines that uplink beam 25 is misaligned by analyzing, for example, information relating to transmissions from other antenna arrays of the user equipment 20 or by measuring impedance mismatches in the user equipment 20.

[0079] Misalignment Angle Determination

[0080] At block S20, the user equipment 20 converts the misalignment indicator (e.g., power difference or gain loss) into a set of possible misalignment angles A (usually in degrees). Typically, the set of possible misalignment angles A can be derived from pre-stored information that correlates the azimuth offset (misalignment) angles with different configurations of the user equipment antenna (such as Figure 4A and 4B The power of the Figure 4A shows the expected gain for a first configuration of the antenna array (in this example for an 8×8 antenna array) with respect to one possible azimuth angle (misalignment angle), while Figure 4B The expected gain is shown for one possible azimuth angle (misalignment angle) for a second configuration of the antenna array (in this example for a 4x4 antenna array).Such pre-stored information is typically provided for each different configuration of the antenna array.

[0081] Assuming that the antenna array is currently configured as an 8×8 antenna array, then Figure 4A Line 1 in FIG. 1 shows the expected UE 20 antenna gain with respect to azimuth (misalignment angle), and therefore if the beam is aligned (as shown in part (A) of the figure), the maximum antenna gain of the UE 20 pointing to the gNB 10 is 16.9 dB. However, if it is determined in block S10 that the uplink power has dropped by 2.6 dB, and no power drop is recorded in the downlink, this may indicate that the UE antenna gain has dropped to 14.3 dB, according to Figure 4A , which indicates a misalignment angle A of 6°. Similarly, if the uplink power drops by 14.2dB, while no power drop is recorded in the downlink, this may indicate that the UE antenna gain has dropped to 2.75dB, which according to line 3 indicates a misalignment angle A of 12°. Finally, if the uplink power drops by 29dB, while no power drop is recorded in the downlink, this may indicate that the user equipment 20 antenna gain has dropped to -12.2dB, which according to line 4 indicates a misalignment angle A of 15°. Therefore, it can be seen that for any indicated drop in user equipment 20 antenna gain, it can be seen from Figure 4A The appropriate misalignment angle A is derived from the mapping shown. In the case where there may be multiple solutions to the same antenna gain degradation, at least in the first instance, the misalignment angle A may be assumed to be the minimum of the possible misalignment angles A. For example, if the user equipment 20 experiences an antenna gain degradation of 16.9 dB, the misalignment angle A may be assumed to be 13° instead of 16°. If the antenna array is currently configured as a 16×16 antenna array, then from Figure 4B To determine the misalignment angle A. For example, if the antenna gain of the user equipment 20 drops by 32 dB from 19.9 dB to -11.9 dB, the misalignment angle A is determined to be 7°.

[0082] from Figure 4A and Figure 4B It can be seen that the sensitivity of the antenna array to non-alignment of the uplink beam 25 depends on the array size. The larger the array, the narrower the beam and the higher the sensitivity to misalignment with the gNB 10 uplink beam 15. Thus, as the beam becomes narrower, the misalignment problem increases with frequency (and the need for high beam direction accuracy) to maintain a constant link budget, which ultimately affects throughput.

[0083] Furthermore, even when the misalignment angle is known, it is not known in which direction the misalignment occurs, e.g. Figure 4C and Figure 4D As shown, Figure 4C and Figure 4DIt is shown that the misalignment can be in any direction along the curve 80, where the curve 80 shows a set of possible misalignment angles. These curves can be circular, such as Figure 4C , where one value of the misalignment angle is sufficient, but they can also be elliptical, requiring multiple values ​​of the misalignment angle to reconfigure the optimal antenna array radiation pattern.

[0084] Once the set of possible misalignment angles A is determined at block S20 , processing proceeds to block S30 .

[0085] Uplink beam misalignment correction

[0086] At block S30, an improved uplink antenna configuration is determined for the calculated set of possible misalignment angles A. Again, this is typically determined by reference to pre-stored information within the user equipment 20 regarding the performance of different configurations of the antenna array at different misalignment angles A. The primary objective is to avoid an antenna radiation pattern configuration that exhibits a null in a direction aligned with the uplink beam 15 (offset from the current 0° azimuth by the misalignment angle A) and improves the gain and power transmission in a direction aligned with the uplink beam 15 (offset from the current 0° azimuth by the misalignment angle A) compared to the current configuration. The pre-stored information may have different granularities, ranging from a detailed understanding of the performance of each configuration to a lookup table that provides a single configuration for each of a range of misalignment angles A, which will be described in more detail below. As will now be described, a variety of different types of reconfigurations are possible.

[0087] Uplink beam misalignment correction – beam broadening

[0088] Figure 5 The gain performance of different configurations at different azimuth angles (misalignment angles) is shown. It can be seen that if the antenna array is currently configured as a 16×16 antenna array and is experiencing a misalignment where one of the angles in the set of possible angles A has an azimuth angle of 7° as reported at box S20, it can be determined that the antenna array exhibits a null in uplink beam 25 in the direction of uplink beam 15 toward gNB 10. However, by reconfiguring to an 8×8 antenna array, the gain loss of uplink beam 15 toward gNB 10 is only 9dB compared to 31dB, which provides a fast recovery improvement of 22dB. It can be seen that reconfiguring to an 8×8 antenna array can provide the best performance improvement for this misalignment angle A. For example, a reduction in the number of antenna elements used to widen the antenna array uplink beam 25 can be achieved simply by turning off some power amplifiers, such as Figure 5 This reconfiguration also reduces power consumption. Figure 5It can also be seen in FIG. 1 that instead of providing a detailed mapping of each possible configuration, a lookup table can be used which indicates the configuration required for each case for different ranges of possible misalignment angles A.

[0089] Uplink beam misalignment correction – phase shift reconfiguration

[0090] In some user equipment, if the phase shifter resolution allows, the antenna array can be reconfigured to maximize the gain in the direction aligned with the uplink beam 15 (which is offset from the current 0° azimuth by a possible misalignment angle set). This is shown in Figure 6, where the initial uplink beam 25 is at Fig. 6A It is shown in Figure 6B The reconfigured uplink beam 25 is shown in . It can be seen that by adjusting the values ​​of the phase shifters, the reconfigured uplink beam 25 maximizes the gain in all possible directions of the possible misalignment angle set A. In this method, all antennas of the array elements continue to be used and are moved to cover all possible tilt directions of the misalignment angles. The benefit of this method is that a null will appear along the misalignment angle (currently 0° azimuth, which points away from the GNB 10) and the power will be concentrated in the conical beam, thereby maximizing the power in all possible directions in the direction aligned with the uplink beam 15 (offset by the misalignment angle from the current 0° azimuth).

[0091] As in Figure 7 As can be seen in Figure 7 Comparing the gain of the original beam in line 1, the reconfiguration by adjusting the phase shifters in line 2, and the shutting down of certain power amplifiers in line 3, the reconfiguration of the phase shifters always provides greater gain and increases the power delivered to the gNB 10 for all configurations, which improves the uplink performance, especially in power-limited situations, such as when the user equipment 20 is located at the cell edge.

[0092] Uplink beam misalignment correction – multiple non-overlapping simultaneously active subarrays

[0093] Another approach (hybrid beamforming) for a user device 20 with multiple transceivers is to reconfigure the antenna array to provide multiple non-overlapping simultaneously active subarrays, each with a wider beam than when all elements are used. This results in a wider combined radiation pattern, over which a transparent transmit diversity scheme can be used to preserve the total transmit power of the user device 20 (assuming that in the architecture of the user device 20, the power amplifier is located behind each antenna element), which would result in a loss of transmit power when the element is turned off. Examples of transparent diversity schemes are delay diversity, random precoding, etc.

[0094] Fig. 8AThe case of dividing a 16×16 antenna array into four sub-arrays is shown, and the gain envelope of the resulting radiation pattern is shown for a configuration where all sub-arrays are active simultaneously. Figure 8B The division of a 16×16 antenna array into 16 sub-arrays is shown. Again, these gain patterns can be pre-stored and the configuration with the highest gain can be selected for each misalignment angle directly from the pre-stored information or from a lookup table that provides the best configuration at each different range of misalignment angles.

[0095] Fig. 9 Example mappings of gain to azimuth (misalignment angle) for four different configurations of the antenna array are shown. Table 1 shows the directivity across all array configurations and angles, as well as the highest gain for each misalignment angle.

[0096]

[0097] Table 1

[0098] According to Table 1, a lookup table 2 related to the misalignment of the optimal array configuration can be established, and then the table 2 can be stored in the memory of the user equipment 20 to save resources.

[0099] ΔRX-TX 0°-4° 5°-9° 10°-17° 18°+ Array Configuration Configuration 4 Configuration 3 Configuration 2 Configuration 1

[0100] Table 2

[0101] The resulting effective antenna gain then follows the envelope of all possible reconfigurations. Although the possible reconfigurations may be limited to one of the above techniques, the reconfiguration may also be compiled from any possible reconfiguration that the user equipment may perform, so the table may include: different reconfiguration techniques for reducing the number of antenna elements, for reconfiguring phase shifters, and / or for reconfiguring to multiple non-overlapping simultaneously active subarrays. In each case, the configuration that obtains the best gain within the range of the possible misalignment angle set will be provided in the lookup table shown in Table 2. In other words, the lookup table needs to contain all possible reconfigurations of the user equipment. The lookup table is implementation specific and depends on the phase shifter resolution, the number of transceivers, the array size, etc. The lookup table is built from the envelope of all configurations, and combinations are possible. Moreover, if the user equipment 20 knows the tilt direction, the user equipment may be able to simply access the codebook to realign the uplink beam 25. If the codebook does not contain an entry for a specific tilt (e.g., the resolution is too coarse), the specific direction may also be part of the lookup table for array reconfiguration.

[0102] Once the desired reconfiguration is selected, processing proceeds to block S40.

[0103] At block S40, the reconfiguration is applied to the antenna array.

[0104] Optionally, at block S50 , a full realignment process is performed.

[0105] In box S60, the communication between the user equipment 20 and the gNB 10 is restored.

[0106] User Equipment

[0107] Fig.10 The arrangement of the user equipment 20 is schematically illustrated. An application processor 21, a baseband processor 22 are provided, both of which communicate with an external memory 23. The baseband processor communicates with one or more transceivers 24. The baseband processor 22 runs a 5G new radio (NR) physical layer 26 with a beam management function 28. The beam management function 28 has: a correspondence checker 32 for checking indications for beam misalignment; a mapper 34 for mapping misalignment indicators (usually in dB, etc.) to a set of possible misalignment angles A (in degrees) with reference to information for mapping gain to misalignment for the above-mentioned current configuration. Reading the array reconfiguration table 36 provides the best reconfiguration for the determined set of possible misalignment angles A, and controlling the array 38 to reconfigure the antenna array to the best reconfiguration for the set of possible misalignment angles. Therefore, reading the array reconfiguration table 36 associates the uplink / downlink user equipment mismatch angle (e.g., in degrees) with the best array reconfiguration to maximize the user equipment uplink gain. The lookup table may be stored in a memory 40 of the user equipment 20. Furthermore, it may be a fixed table or a dynamic table, the latter meaning learning and storage capabilities over time using, for example, machine learning (e.g., updating values ​​or through adaptive granularity). The beam management function 28 takes the correspondence check output as input, then estimates the set of possible misaligned directions, and uses the read array reconfiguration table 36 stored in the memory 40 to select the best entry for optimal uplink power transmission. Finally, the control array 38 controls the array (e.g., turning on / off the power amplifier and / or adjusting the phase shifter and / or dividing the antenna array into sub-arrays) according to the selected table entry.

[0108] Example Operation

[0109] Fig.11 The operation of the user equipment 20 is described in more detail. At block S100, the correspondence checker 32 is activated to perform a beam correspondence check.

[0110] At block S110 , a mismatch threshold is determined.

[0111] At box S120, it is determined whether the misalignment or beam correspondence mismatch is greater than a threshold (this is detected autonomously or assisted by information provided by the gNB 10, typically indicated by a reduction in gain or expected power received by the gNB, although other indications are possible as described above).

[0112] If the misalignment is less than the threshold, processing proceeds to box S160, where another trigger is awaited to perform the misalignment check. The triggers can be of different types; for example, two types of triggers, Trigger 1 and Trigger 2. Trigger 1 initiates the beam correspondence check and can be initiated or assisted by the gNB 10, while Trigger 2 autonomously initiates the array reconfiguration. Trigger 1 can be the full process, i.e., the correspondence mismatch calculation (involving the gNB 10 evaluating the difference in dB between the downlink beam 27 and the uplink beam 25, referred to as ΔRX-TX). Trigger 1 can be based on a local event to the user equipment 20 or an event external to the user equipment 20. Local examples of Trigger 1 can be a power amplifier input power change, a temperature change, a beam realignment (i.e., a change in a codebook entry), or an internal trigger, such as Fig.11 An external example of trigger 1 could be a correspondence check requested by the gNB 10.

[0113] Trigger 2 directly initiates array reconfiguration. The user equipment 20 autonomously determines that beam correspondence is broken, deduces that it may be in a direction of reduced antenna gain or even in a null direction, and decides to reconfigure the array to increase gain.

[0114] Returning now to block S120 , if the misalignment is greater than the threshold amount, processing proceeds to block S130 .

[0115] At block S130 , the mapper 34 refers to the radiation pattern of the current configuration to map the gain reduction to the set of possible misalignment angles A. The process then proceeds to block S140 .

[0116] At block S140, the read array reconfiguration table 36 is read to determine the best reconfiguration for the set of possible misalignment angles determined at block S130. Processing then proceeds to block S150.

[0117] At block S150, control array 38 programs the antenna using the new configuration provided by reading array reconfiguration table 36. Processing then proceeds to block S160 to await the next trigger.

[0118] Therefore, once a trigger occurs, and once the severity of the misalignment is known to the user equipment 20, the user equipment 20 initiates a fast array reconfiguration only in the uplink to limit the gain degradation effect from beam misalignment. This results in asymmetric uplink-downlink beams to address the beam misalignment issue and avoid possible radio link failures. Once the uplink beams are optimized, the user equipment 20 may attempt a full realignment procedure such as described in 3GPP TR 38.802 section 6.1.6 and TS 38.214 section 5.2. Otherwise, if a full array alignment procedure is not possible (e.g., phase shifter resolution is too coarse or there is an unknown tilt), the user equipment 20 may maintain the reconfiguration as the best uplink option. In addition, it may periodically attempt to restore the original antenna configuration and reconfirm beam correspondence based on changes in operating conditions or upon request by the gNB 10 to be able to quickly recover from temporary dynamic misalignment events. Therefore, once the UE 20 has reached the array reconfiguration to resume power transmission, it will remain in that state until Trigger 1 or Trigger 2 causes a change such as a new correspondence mismatch procedure or autonomous reconfiguration or a beam check is triggered every frame or based on a timer (fixed or adaptive). If the UE 20 is at maximum transmit power, the gNB 10 can compensate for the residual loss in the uplink gain budget by increasing its receive antenna gain if possible.

[0119] Using only uplink reconfiguration is a very powerful tool to resolve transmit / receive misalignment issues, since full beam realignment is not only very expensive in terms of resources and throughput, but also very time consuming and may even result in radio link failure (uplink disappears, e.g. 30dB link loss at 7 degrees of misalignment on a 16×16 array). The main advantage is that only the uplink mode is adapted using this procedure, e.g. reducing power consumption, interference and avoiding radio link failures. This allows the user equipment 20 to quickly resolve misalignments and avoid radio link failures.

[0120] Although a full realignment can be attempted directly when a beam mismatch is detected, this is a lengthy process that can itself result in radio link failures. If the process alternates with the current antenna state (i.e., misalignment), the process will be further slowed down and may also result in radio link failures. Another solution is to blindly reconfigure the array to the minimum array configuration. Although, this will not necessarily provide the best available gain, and may not even provide enough gain to compensate for the propagation losses. Similarly, reconfiguring to the next smaller array configuration (e.g., from 16×16 to 8×8) will not guarantee that nulls are avoided. Therefore, a process of mapping gain losses to an optimal array configuration is a better way to react quickly to beam mismatches. Therefore, some embodiments first reconfigure the antenna to an optimal configuration to optimize uplink gain under misaligned conditions before attempting a full realignment process. The advantages of this approach from the UE 20 perspective are: rapid reaction to misalignment detection by reconfiguring the array, avoiding radio link failure; avoiding radio link failure by delaying the lengthy and expensive full realignment process until after the optimized configuration is applied; optimizing gain towards the gNB 10 under misaligned conditions, and avoiding unnecessary power consumption increases. The advantage of this approach from the network perspective is lower interference. Misalignment can increase cell interference, thereby reducing capacity for neighboring UEs. With this implementation, interference is greatly reduced as we redirect gain towards the serving cell.

[0121] Those skilled in the art will readily recognize that the various blocks of the above methods can be executed by a programmed computer.Herein, some embodiments are also intended to cover program storage devices, such as digital data storage media, which are machine or computer readable and encode machine executable or computer executable programs of instructions, wherein the above instructions execute some or all of the blocks of the above methods.The program storage device can be, for example, a digital memory, a magnetic storage medium such as a disk and a tape, a hard drive, or an optically readable digital data storage medium.The embodiments are also intended to cover computers programmed to perform the above blocks of the above methods.Those skilled in the art will also recognize that the illustration of a particular order of blocks does not necessarily mean that the blocks have a desired or preferred order, and that the order can be changed.In addition, those skilled in the art will recognize that one or more blocks can be omitted.

[0122] Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

[0123] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

[0124] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0125] Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

[0126] While an effort has been made to call attention in the foregoing description to features of the present invention regarded as particularly important, it should be understood that the applicant claims protection for any patentable feature or combination of features heretofore referenced and / or shown in the accompanying drawings, whether or not specifically emphasized.

Claims

1. A method performed by a user equipment, comprising: determining, based on an indication that an initial uplink beam (25) between the user equipment and the network node is misaligned relative to a downlink beam (27) between the network node and the user equipment, at least one misalignment angle between the initial uplink beam and the downlink beam; as well as reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam; Wherein the determining comprises determining the misalignment angle according to pre-stored information, the pre-stored information relating the value of the indication to the value of the misalignment angle.

2. The method according to claim 1, comprising at least one of the following: receiving the indication at the user equipment from the network node; and determining the indication within the user equipment, wherein the indication is an indication of a power difference between an expected received power level at the network node and an actual received power level at the network node.

3. A method according to claim 1 or 2, wherein the reconfiguration includes reconfiguring the uplink beam based on the misalignment angle to produce at least one of the following: the reconfigured uplink beam that avoids a transmission zero position along the misalignment angle, and the reconfigured uplink beam that has an increased gain along the misalignment angle compared to the initial uplink beam.

4. A method according to claim 1 or 2, wherein the reconfiguration includes reconfiguring the uplink beam in the following manner: retaining all of the antenna array elements used to generate the initial uplink beam, and applying the changed antenna array configuration values ​​of all of the antenna array elements based on the misalignment angle to generate the reconfigured uplink beam.

5. The method according to claim 1 or 2, wherein the reconfiguration comprises: The uplink beam is reconfigured by applying a changed antenna array configuration value based on the misalignment angle to produce the reconfigured uplink beam.

6. The method according to claim 1 or 2, wherein the reconfiguration comprises: The uplink beam is reconfigured by applying changed antenna array phase shifter values ​​based on the misalignment angle to produce the reconfigured uplink beam.

7. The method according to claim 1 or 2, wherein the reconfiguration comprises: The uplink beam is reconfigured by applying changed antenna array values ​​based on the misalignment angle to produce a plurality of sub-array uplink beams to create the reconfigured uplink beam.

8. The method of claim 7, wherein the reconfiguring comprises: The changed antenna array value is determined according to pre-stored information relating the value of the misalignment angle to a value of gain for the changed antenna array value.

9. The method of claim 8, wherein the pre-stored information relates values ​​of the misalignment angle to values ​​of gain for a plurality of changed antenna array values, and wherein the reconfiguring comprises: Selecting one of the plurality of altered antenna array values ​​that achieves a maximum gain improvement for the misalignment angle.

10. The method of claim 8 or 9, wherein the pre-stored information relates different ranges of values ​​of the misalignment angle to corresponding multiple changed antenna array values ​​for the ranges, and the reconfiguring comprises: It is determined within which range of values ​​of the misalignment angle the misalignment angle falls, and one of the plurality of changed antenna array values ​​corresponding to the range is selected.

11. A computer program product comprising instructions for causing a user device to perform at least the following operations: determining, based on an indication that an initial uplink beam (25) between the user equipment and the network node is misaligned relative to a downlink beam (27) between the network node and the user equipment, at least one misalignment angle between the initial uplink beam and the downlink beam; as well as reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam; Wherein the determining comprises determining the misalignment angle according to pre-stored information, the pre-stored information relating the value of the indication to the value of the misalignment angle.

12. An apparatus for communication, comprising: means for determining at least one misalignment angle between an initial uplink beam (25) between a user equipment and a network node and a downlink beam (27) between the network node and the user equipment based on an indication that the initial uplink beam (25) is misaligned relative to the downlink beam (27) between the network node and the user equipment; as well as means for reconfiguring the uplink beam based on the misalignment angle to produce a reconfigured uplink beam; Wherein the determining comprises determining the misalignment angle according to pre-stored information, the pre-stored information relating the value of the indication to the value of the misalignment angle.

13. A user equipment comprising the apparatus for communication according to claim 12.

14. A user equipment, wherein the user equipment is configured to execute the method according to any one of claims 1 to 10.

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