Beam selection method for accessing a wireless network

Abstract

Beam selection method for accessing a wireless network. This description relates to a method for selecting beams from a base station (BS) to user equipment (UE1, UE2), the base station (BS) comprising a multi-source antenna array comprising subsets of elementary antennas, the method comprising the steps of emitting, by each subset of elementary antennas in successive stages, a beam, all beams having the same beamwidth, and, for each subset of elementary antennas, all beams emitted by said subset of elementary antennas pointing in directions different from each other and different from the directions of the first beams emitted by each other subset of elementary antennas;and reception by the base station (BS) of a signal emitted by each user equipment (UE1, UE2) indicating at which stage among the first stages the maximum power beam was received by said user equipment (UE1, UE2). Figure for the abbreviation: Fig. 2;

Description

Title of the invention: Beam selection method for accessing a wireless network. Technical field

[0001] This description relates generally to the field of wireless networks, in particular the initial access phase of a user equipment (UE) during which the base station (BS) and the user equipment attempt to achieve beam alignment. Previous technique

[0002] Some wireless networks include antenna arrays located at base stations to form directional beams. However, for effective communication between the base station and user equipment, the beams at the base station must be narrow (thus providing sufficient power gain in the pointing directions) and properly aligned.

[0003] The method of selecting the base station beams includes determining the orientation and width of the beams required to establish a physical link between the user equipment and the base station and is essential during the initial access phase of the user equipment to a wireless network.

[0004] It has been proposed to perform an exhaustive directional scanning process of the discretized angular space, particularly on the base station side, to test all possible beam directions for the base station-user equipment pairs, either randomly or systematically. This exhaustive directional scanning selection process can lead to a lengthy initial access phase.

[0005] This method has been improved by first transmitting from the base station side in several directions with a wide beam, and then iteratively refining the beam characteristics until a strong link in terms of SNR (signal-to-noise ratio) can be established. Such a beam selection method is called an iterative scanning selection method. However, the duration of the initial access phase can still be significant.

[0006] Furthermore, some base stations include multi-source antenna arrays adapted to simultaneously transmit two or more beams in different directions, thus enabling at least two user devices to communicate simultaneously with the base station. The beam selection process must then be implemented by the base station for each user device. Summary of the invention

[0007] An embodiment overcomes all or part of the drawbacks of known beam selection methods, particularly for access to a wireless network.

[0008] An object of an embodiment is that the method of beam selection for a pair of user equipment and base station, particularly during the initial phase of accessing a wireless network, converges more quickly than known methods.

[0009] One embodiment provides a method for selecting beams from a base station to user equipment, the base station comprising a multi-source antenna array including subsets of elementary antennas, the method comprising the following steps: a) emission, by each subset of elementary antennas, at successive stages, of a beam, all beams having the same beamwidth, and, for each subset of elementary antennas, all beams emitted by said subset of elementary antennas pointing in directions different from each other and different from the directions of the first beams emitted by each other subset of elementary antennas; and b) reception by the base station of a signal emitted by each user equipment indicating at which stage among the first stages the maximum power beam was received by said user equipment.

[0010] According to one embodiment, steps a) and b) are repeated, the width of the beams emitted at the second occurrence of step a) being less than the width of the beams emitted at the first occurrence of step a).

[0011] According to one embodiment, at the second occurrence of step a), the emitted beams are included in the beams emitted at the first occurrence of step a) and indicated by the signals emitted by the user equipment at the first occurrence of step b).

[0012] According to one embodiment, the method comprises, after the last occurrence of step b), a step c) of successively emitting by each subset of elementary antennas beams having the same beam width, and, for each subset of elementary antennas, all the beams emitted by said subset of elementary antennas pointing in directions different from each other and different from the directions of the beams emitted by each other subset of elementary antennas.

[0013] According to one embodiment, the width of the beams emitted in step c) is less than the width of the beams emitted in the last occurrence of step a).

[0014] According to one embodiment, in step c), the emitted beams are included in the beams emitted at the last occurrence of step a) and indicated by the signals emitted by the user equipment at the last occurrence of step b).

[0015] According to one embodiment, the process comprises the following steps: - emission, by each subset of elementary antennas, at each first step of a succession of first steps, of a first beam pointing in a first direction and having a first beam width, all first beams having the same first beam width, and, for each subset of elementary antennas, all first beams emitted by said subset of elementary antennas pointing in first directions different from each other and different from the first directions of the first beams emitted by each other subset of elementary antennas; - reception by the base station of a first signal emitted by each user equipment indicating at which first stage, called the first maximum stage, among the first stages the first maximum power beam was received by said user equipment; - emission, by each subset of elementary antennas, at each second stage of a succession of second stages, of a second beam pointing in a second direction and having a second beamwidth less than the first beamwidth, all second beams having the same second beamwidth, and, for each subset of elementary antennas, all second beams emitted by said subset of elementary antennas being included in the first beams emitted at the first stages of maximum, pointing in second directions different from each other and different from the second directions of the second beams emitted by each other subset of elementary antennas;and - reception by the base station of a second signal emitted by each user device indicating at which second stage, called the second maximum stage, among the second stages the second maximum power beam was received by said user device. ;

[0016] According to one embodiment, the method further comprises the following steps: - successively, for each second beam emitted at the third maximum steps, by the subset of elementary antennas that emitted said second beam, at each third step of a succession of third steps, third beams pointing in third directions and having a third beamwidth less than the second beamwidth, all third beams having the same third beamwidth, and all third beams emitted by said subset of elementary antennas being included in said second beam, the third beams pointing in different third directions from each other and different from the third directions of the third beams emitted by each other subset of elementary antennas; and - reception by the base station of a third signal emitted by each user equipment indicating at which third stage, called the third maximum stage, among the third stages the third maximum power beam was received by said user equipment.

[0017] One embodiment also provides for a base station comprising a multi-source antenna array comprising subsets of elementary antennas, the base station being configured to implement a beam selection method to user equipment comprising the repetition of the following steps: - emission, by each subset of elementary antennas, at successive stages, of a beam, all beams having the same beamwidth, and, for each subset of elementary antennas, all beams emitted by said subset of elementary antennas pointing in directions different from each other and different from the directions of the first beams emitted by each other subset of elementary antennas; and - receipt of a signal from each user equipment indicating at which stage among the first stages the maximum power beam was received by said user equipment. Brief description of the drawings

[0018] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0019] Fig. 1 represents, in a partial and schematic way, a base station comprising a multi-source antenna array;

[0020] Figure 2 schematically illustrates the positions of a base station and two user devices in a wireless network;

[0021] [Fig.3] schematically represents beams that can be emitted by two subsets of elementary antennas of an antenna array;

[0022] [Fig.5], [Fig.6], and [Fig.7] schematically represent beams emitted by the two subsets of elementary antennas of the antenna array of [Fig.3] at successive stages of an embodiment of a beam selection method;

[0023] Figures 8, 9, 10, 11, 12, and 13, obtained by simulation, represent the electromagnetic power received by two pieces of equipment user at successive stages of the implementation of the beam selection process illustrated in [Fig.4], [Fig.5], and [Fig.6];

[0024] Figures 14 and 15, obtained by simulation, represent the electromagnetic power received by two user devices when the base station implements a comprehensive directional beam selection process; and

[0025] Figures 16, 17, and 18 each represent the number of steps required when implementing the beam selection method according to the embodiment illustrated in Figures 5, 6, and 7, of an exhaustive directional scanning selection method and an iterative scanning selection method for a multi-source antenna array comprising two, four, and eight subsets of elementary antennas, respectively, as a function of the square root of the number of elementary antennas in each subset of elementary antennas. Description of the embodiments

[0026] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0027] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0028] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0029] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures in a normal position of use.

[0030] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0031] Figure 1 represents a base station BS of a wireless network, comprising a multi-source antenna array 10, also called a multi-antenna array source.

[0032] The multi-source antenna array 10 comprises a set of elementary antennas 12. The base station BS further comprises an electronic control circuit 14 configured to control each elementary antenna 12 of the antenna array 10.

[0033] According to one embodiment, the electronic circuit 14 is configured to distribute all the elementary antennas 12 of the antenna array 10 into M subsets Sub-RISj of elementary antennas 12, where j is an integer from 1 to M, and M is an integer greater than or equal to 2. The number M depends, in particular, on the number of elementary antennas 12. The number M corresponds to the number of user devices, not shown in [Fig. 1], with which the base station must establish wireless communication. For example, in [Fig. 1], where M is equal to 2, the antenna array 10 comprises two subsets Sub-RIS1 and Sub-RIS2 of elementary antennas 12. Each Sub-RISj subset of elementary antennas 12 comprises a number NA*NA of elementary antennas 12.The electronic control circuit 14 is configured to independently control each Sub-RISj subset of elementary antennas 12 to emit a beam of electromagnetic waves pointing in a given direction. The pointing directions of the beams emitted by the Sub-RISj subsets of elementary antennas 12 can be different. In one embodiment, the antenna array 10 is implemented using Reconfigurable Intelligent Surfaces (RIS) technology. The frequency range of the electromagnetic waves in the beams depends on the intended applications.According to one embodiment, the frequency range of the electromagnetic waves of the beams corresponds for example to the frequency bands of the fifth generation (5G) mobile telephony network standard, for example the frequency band from 600 MHz to 900 MHz, the frequency band from 1.7 GHz to 4.7 GHz, in particular the 3.5 GHz band (3.4 GHz- 3.8 GHz), or the frequency band from 24 GHz to 47 GHz, in particular the 26 GHz band (24.25 GHz - 27.5 GHz).

[0034] Figure 2 schematically represents a base station BS and two user devices UE1 and UE2 within a cellular CN network, the base station BS having the structure shown in Figure 1. Figure 2 shows a beam Bi emitted by the Sub-RIS1 subset of the base station BS and directed towards the user device UE1, and a beam B2 emitted simultaneously by the Sub-RIS2 subset of base station 1 and directed towards the user device UE2. Each beam Bi, B2 corresponds to a beam direction D1, D2 and a beam width BW1, BW2.

[0035] According to one embodiment, each Sub-RISj subset of elementary antennas 12 can emit beams with different angular apertures. By way of example, each Sub-RISj subset of elementary antennas 12 can emit beams with large, medium, or small beamwidths.

[0036] Figure 3 schematically represents a CSub-RISi map of the large beamwidths that can be emitted by the first Sub-RISi subset of elementary antennas in the antenna array 10, and a CSub-RIS2 map of the large beamwidths that can be emitted by the second Sub-RIS2 subset of elementary antennas in the antenna array 10. Each beam is designated by the reference numeral B; j, where i is an integer from 1 to N, and j is an integer from 1 to M, M being the number of subsets, which, for example, is 2 in Figure 3. The integer N corresponds to the total number of beams that can be emitted by each Sub-RISi, Sub-RIS2 subset of elementary antennas. The number N depends, in particular, on the number NA. As an example, in [Fig.3], N is equal to 16.For each subset Sub-RISj, j within the range from 1 to M, each beam points in a different direction from the other beams Bkjj, where k is an integer other than i. Beams B1 to B1M point in the same direction. For each subset Sub-RISj, j within the range from 1 to M, the N beams B1 to B1j cover the entire portion of space in which the base station is likely to transmit. This is, for example, an angular sector with an azimuth in the range from -60° to 60° and an elevation in the range from -60° to 60°. For illustrative purposes, the N beams B1 to B1j are shown contiguous. In reality, each beam B1j partially overlaps with neighboring beams to cover the entire portion of space in which the base station is likely to transmit.

[0037] Figure 4 illustrates the formation of beams having angular apertures different by one of the Sub-RISj subsets of elementary antennas 12. For each large beamwidth Bij (schematically illustrated by a thick solid oval in [Fig. 4]), where i is an integer from 1 to N, and j is an integer from 1 to M, the elementary antennas 12 of the Sub-RISj subset can be controlled by the control circuit 14 to emit an integer O of medium beamwidth Brij (schematically illustrated by dashed ovals in [Fig. 4]), where r is an integer from 1 to 0, each having a beamwidth smaller than the large beamwidth of the Bij beam, the Bi, Bo, beams being substantially contained within the BLJ beam According to one embodiment, the beamwidth of the Brij beam is substantially halved in azimuth and halved in elevation compared to the beamwidth of the Bij beam, so that the number O is equal to 4. Similarly, for each beam with average beamwidth Brij, where i is an integer from 1 to N, j is an integer from 1 to M, and r is an integer from 1 to 0, the elementary antennas 12 of the Sub-RISij subset can be controlled by the control circuit 14 to emit a number P of small beamwidths Bsrij (schematically illustrated by thick solid ovals), where s is an integer from 1 to P, each having a beamwidth smaller than the average beamwidth of the Brij beam, the beams Br,ij to Br,ij being substantially contained within the beam Br. According to one embodiment, the beamwidth of the beam Bs r> is substantially halved in azimuth and halved in elevation relative to the beamwidth of the beam Br, so that P is equal to 4. Analogously to what has been indicated previously, for illustrative purposes, the O beams with average beamwidth Bi, ij to Bo, ij are shown contiguous. In reality, each beam with average beamwidth Br is partially superimposed with neighboring beams with average beamwidths to cover the entirety of the large beamwidth B^. Furthermore, the P beams with small beamwidths Bi>r, ij to BP>r, ij are shown contiguous. In reality,Each small beamwidth Bs r> is partially overlapped with neighboring small beamwidths to cover the entire medium beamwidth Br ;j. Each subset Sub-RISj can therefore emit N different large beamwidths, N*P different medium beamwidths, and N*P*O different small beamwidths. ,

[0038] According to one embodiment, the control circuit 14 establishes a codebook that depends on the number of user devices that need to communicate with the base station BS. The codebook includes the commands to be applied to the elementary antennas 12 so that each subset Sub-RISj of elementary antennas 12 can transmit the N wide-beams, the N*P medium-beams, and the N*P*O different narrow-beams. The number N*P*O of different narrow-beams that each subset Sub-RISj of elementary antennas 12 can transmit depends in particular on the number NA and can be equal to the number NA squared. The number M of Sub-RISj subsets of elementary antennas 12, and therefore the number NA, can be modified by the circuit command 14 depending on the number of user devices seeking to access wireless communication with the base station.

[0039] The present embodiment comprises a number Q of scanning phases. Each scanning phase comprises a number Z of successive steps, and during each step, each Sub-RISj subset of elementary antennas 12 of the base station emits a beam. According to one embodiment, for each scanning phase, and for each step of the scanning phase, the beam emitted by each Sub-RISj subset of elementary antennas 12 during each step is different from the beams emitted during all other steps by all the Sub-RISj subsets. In the following description, an exponent u,v is added to the beam reference, where u is an integer in the range from 1 to Z and v is an integer in the range from 1 to Q.According to one embodiment, for each scanning phase, and for each Sub-RISj subset of elementary antennas 12, all beams emitted during the steps of the scanning phase have the same beamwidth. According to another embodiment, for each scanning phase, all beams emitted during the steps of the scanning phase by the Sub-RISj subset of elementary antennas 12 are different from the beams emitted during the steps of the scanning phase by the other Sub-RISw subsets of elementary antennas 12, where w is different from j.

[0040] According to one embodiment, at the end of each scan phase, each user device transmits a message to the base station indicating at which stage of the scan phase it received the beam with the maximum power. The beam with the maximum power corresponds to the beam emitted by the base station whose direction points most directly towards the position of the user device. The user device does not know which subset of elementary antennas 12 (Sub-RISj) emitted the received beam with the maximum power, and therefore it only indicates the stage of the scan phase at which it received the beam with the maximum power. The base station determines, for each stage at which one of the user devices indicated having received a beam with the maximum power, which beam was emitted by each subset of elementary antennas 12 (Sub-RISj).

[0041] According to one embodiment, in the first scanning phase of the process, each Sub-RISj subset of elementary antennas 12 of the base station emits, during each step of the first scanning phase, a large beamwidth B; / '1. All large beamwidths B; / 1 to B; / 1 emitted during the Z steps of the first scanning phase by the Sub-RISj subset of elementary antennas 12 are different from the large beamwidths emitted during the steps of the first scanning phase by the other sub- Sub-RISw sets of elementary antennas 12 where w is different from j. Each large beamwidth beam B; / 1 to B; / 1 is therefore transmitted only once during the first scanning phase by one of the Sub-RISj subsets of elementary antennas 12. At each step of the first scanning phase, the M Sub-RISj subsets of elementary antennas 12 therefore simultaneously emit large beamwidth beams.

[0042] At the end of the first scanning phase, each user device indicates to the base station at which stage, called the maximum stage, it received the maximum-power, large-beamwidth beam. The base station determines, for each maximum stage, which large-beamwidth beam was emitted by each subset of elementary antennas 12.

[0043] In the second scanning phase, successively for each maximum step determined in the first scanning phase, each Sub-RISj subset of elementary antennas 12 successively emits the P medium-width beams contained within the large-width beam emitted at the maximum step determined in the first scanning phase. At each step of the second scanning phase, the M Sub-RISj subsets of elementary antennas 12 therefore simultaneously emit medium-width beams.

[0044] At the end of the second scanning phase, each user device indicates to the base station at which stage, called the maximum stage, it received the maximum power average beamwidth beam. The base station determines, for each maximum stage, which average beamwidth beam it had emitted from each subset of elementary antennas 12.

[0045] In the third scanning phase, successively for each maximum step determined in the second scanning phase, each Sub-RISj subset of elementary antennas 12 successively emits the O small beamwidths contained in the medium beamwidth that it had emitted at the maximum step determined in the second scanning phase. At each step of the third scanning phase, only one small beamwidth is therefore emitted by one of the Sub-RISj subsets of elementary antennas 12.

[0046] At the end of the third scanning phase, each user device indicates to the base station at which stage it received the maximum-power small beamwidth beam. The base station determines, for each stage at which one of the user devices indicated having received a maximum-power beam, which small beamwidth beam was emitted by each Sub-RIS j subset of elementary antennas 12. This is the small beamwidth beam pointing towards the user device that can be used by one of the Sub- RISj of 12 elementary antennas to communicate with the user equipment afterwards.

[0047] The method may include additional scanning phases when beams with a beamwidth less than the small beamwidth can be emitted by the Sub-RISj subset of elementary antennas 12.

[0048] Figures 5 to 7 illustrate successive scanning phases of an embodiment of a beam selection method for accessing a wireless network.

[0049] Figure 5 illustrates a CISub-RISi map of large beamwidth beams emitted by the first Sub-RISi subset of elementary antennas of the antenna array 10, and a ClSub-RIS2 map of large beamwidth beams emitted by the second Sub-RIS2 subset of elementary antennas of the antenna array 10 during the first scanning phase of the process in which the number M of elementary antenna subsets is equal to 2, the number N of large beamwidth beams per elementary antenna subset is equal to 16, and the number Z of steps is equal to 8. This means that, during the first scanning phase, the first and second Sub-RISi and Sub-RIS2 subsets of elementary antennas 12 each successively emit 8 large beamwidth beams. It is assumed that there are two user devices wishing to communicate with the base station.

[0050] In [Fig. 5], the large beamwidth beams not emitted by each Sub-RISi and Sub-RIS2 subset of elementary antennas 12 are represented by black ovals. The first subset Sub-RISi successively emits the large beamwidth beams Bi, i', B3, i2', B5, i3', B7, i', B9, i5', Bu, i6, En, i, and B15, i8, and the second subset Sub-RIS2 successively emits the large beamwidth beams B2, 2*', B4, 22', B6, 23', B8, 24', Bi0, 25, R6, 1, R7, 1, R8, 1, 12, 2, 14, 2, Cl, X, 16, 2

[0051] By way of example, it is assumed that the maximum power beam received by the first user device is beam B5ji31 emitted by the first Sub-RISi subset of elementary antennas 12, and that the maximum power beam received by the second user device is beam Bi6j281 emitted by the second Sub-RIS2 subset of elementary antennas 12. At the end of the first scanning phase, the first user device transmits a message to the base station indicating that the maximum power beam was received in the third stage, and the second user device transmits a message to the base station indicating that the maximum power beam was received in the eighth stage. For the third stage, there is therefore an indeterminacy between beam B5131 emitted by the first Sub-RISi subset of elementary antennas 12 and beam B6 2 31 emitted by the second subset Sub-RIS2 of elementary antennas 12. For the eighth step, there is therefore an indeterminacy between the Bis / '1 beam emitted by the first subset Sub-RISi of elementary antennas 12 and the Big / '1 beam emitted by the second subset Sub-RIS2 of elementary antennas 12.

[0052] Figure 6 illustrates a C2Sub-RISi map of the medium-beamwidth beams emitted by the first Sub-RISi subset of elementary antennas of the antenna array 10, and a C2Sub-RIS2 map of the medium-beamwidth beams emitted by the second Sub-RIS2 subset of elementary antennas of the antenna array 10 during the second scanning phase of the process, in which the number O of medium-beamwidth beams per large-beamwidth beam is equal to 4. This means that, during the second scanning phase, the first and second Sub-RISi and Sub-RIS2 subsets of elementary antennas 12 each successively emit 8 medium-beamwidth beams. The first Sub-RISi subset successively emits the four medium-beamwidth beams covering the large-beamwidth beam B5ji31 and then the four medium-beamwidth beams covering the large-beamwidth beam Bn / '1.The second subset Sub-RIS2 successively emits the four medium-width beams covering the large-width beam B6 23 1 and then the four medium-width beams covering the large-width beam Bi6>28,1. More precisely, the first subset Sub-RISi successively emits the medium-width beams Bi 5, i ' , B25 j ' , B35 4 ' , B45 / '2, B115 i5'2, B2>i5 i6'2, B2>i5 i7'2, and B415 i8'2, and the second subset Sub-RIS2 successively emits the medium-width beams Bij6 ,2*'2 , B2 6 >22' . 2 D 3, 2 ü 4, 2 p 5, 2 p 6, 2 p 7, 2 fp 8, 2 9 ^>3,6,2? ^>4,6,2? ^1,16,2? &2, 16, 2? ^3.16.2? ^4.16.2

[0053] By way of example, it is assumed that the maximum power beam received by the first user equipment is the Bi 5 / '2 beam emitted by the first subset Sub-RISi of elementary antennas 12, and that the maximum power beam received by the second user equipment is the B2 6>26 '2 beam emitted by the second subset Sub-RIS2 of elementary antennas 12. At the end of the second scanning phase, the first user equipment transmits a message to the base station indicating that the average beamwidth beam having the maximum power was received in the first stage and the second user equipment transmits a message to the base station indicating that the average beamwidth beam having the maximum power was received in the sixth stage.For the first step, there is therefore an indeterminacy between the Bi s i1'2 beam emitted by the first subset Sub-RISi of elementary antennas 12 and the Bi>6>2 beam. 1,2 emitted by the second subset Sub-RIS2 of elementary antennas 12. For the sixth step, there is therefore an indeterminacy between the beam 62,15,26,2 emitted by the first subset Sub-RISi of elementary antennas 12 and the beam B2,6,26,2 emitted by the second subset Sub-RIS2 of elementary antennas 12.

[0054] Figure 7 illustrates a C3Sub-RISi map of small beamwidths emitted by the first Sub-RISi subset of elementary antennas of the antenna array 10, and a C3Sub-RIS2 map of small beamwidths emitted by the second Sub-RIS2 subset of elementary antennas of the antenna array 10 during the third scanning phase of the embodiment of the method, in which the number P of small beamwidths per medium beamwidth is equal to 4. This means that, during the third scanning phase, the first and second Sub-RISi and Sub-RIS2 subsets of elementary antennas 12 each successively emit 8 small beamwidths. The first Sub-RISi subset successively emits the four small beamwidths covering the medium beamwidth B1511'2.Next, the second subset Sub-RIS2 successively emits the four small beamwidth beams covering the medium beamwidth beam Bi,6,21,2. Next, the first subset Sub-RISi successively emits the four small beamwidth beams covering the medium beamwidth beam B2,i5,i6,2. Next, the second subset Sub-RIS2 successively emits the four medium beamwidth beams covering the large beamwidth beam B2,i6,2 6'2.More specifically, the first subset Sub-RISi successively emits the small beamwidth beams Bi,1,5,1', B2,1,5,1', B3,1,5,1', and B4,1,5,1', then the second subset Sub-RIS2 successively emits the small beamwidth beams Bi,i,6,2', B2,1,6,2', B3,i,6,2', and B4,i,6,2', then the first subset Sub-RISi successively emits the small beamwidth beams B12,i5,i5'3, 637383 • • vs. B2,2,15,l', B3,2,15,l' and B4,2,15,l', and finally the second subset Sub-RIS2 emits 5 3 6 3 7 3 successively the small beamwidth beams Bi,i,i6,2 ', B2,1,16,2 ', B3,i,i6,2 ', and ü 8,3 ^4,1,16,2 •

[0055] At the end of the third scanning phase, the first user device transmits a message to the base station indicating at which stage the small beamwidth beam with maximum power was received, and the second user device transmits a message to the base station indicating at which stage the small beamwidth beam with maximum power was received in the sixth stage. The base station can thus determine which small beamwidth beam is pointing towards the first user device and which will be used in the continuation of the communication with one of the first user equipment by one of the first subset Sub-RISi and the second subset Sub-RIS2 and which small beamwidth beam points towards the second user equipment and which will be used in the continuation of the communication with the second user equipment by the other of the first subset Sub-RISi and the second subset Sub-RIS2.

[0056] Figures 8, 9, 10, 11, 12, and 13, obtained by simulation, represent the electromagnetic power PW, expressed in watts (W), received by the user equipment as a function of azimuth (0 on the x-axis) and elevation (q on the y-axis) at successive scanning phases of the beam selection method embodiment illustrated in Figures 5, 6, and 7. For Figures 8 to 13, the base station is located at a position with coordinates (0, 0, 5) in an orthonormal coordinate system. The first user equipment is located at a position with coordinates (5, -5, 1, 2) in the orthonormal coordinate system. The second user equipment is located at a position with coordinates (5, 3, 1) in the orthonormal coordinate system. Each Sub-RISj subset comprises 200 elementary antennas 12.

[0057] Fig. 8 and Fig. 9, obtained by simulation, represent the electromagnetic power received by the first user equipment (Fig. 8) and by the second user equipment (Fig. 9) at the first scanning phase of the embodiment of the beam selection process illustrated in Fig. 5.

[0058] Fig. 10 and Fig. 11, obtained by simulation, represent the electromagnetic power PW received by the first user equipment (Fig. 10) and by the second user equipment (Fig. 11) at the second scanning phase of the embodiment of the beam selection process illustrated in Fig. 6.

[0059] Fig. 12 and Fig. 13, obtained by simulation, represent the electromagnetic power PW received by the first user equipment (Fig. 12) and by the second user equipment (Fig. 13) at the second scanning phase of the embodiment of the beam selection process illustrated in Fig. 7.

[0060] Figures 14 and 15, obtained by simulation, represent the electromagnetic power PW received by the first user equipment (Fig. 14) and by the second user equipment (Fig. 15) for a beam selection process comprising exhaustive directional scanning by each subset Sub-RISi and Sub-RIS2 of all beams with small beamwidth Bs > r, ij, where s is in the range from 1 to P, r is in the range from 1 to 0, i is in the range from 1 to N, and j is equal to 1 for the first subset Sub-RISi and equal to 2 for the second subset Sub-RIS2. Figure 14 is substantially identical to Figure 12, which This illustrates that the small beamwidth beam pointing towards the first user device obtained by the beam selection method according to the embodiment described above in relation to Figures 8, 10, and 12 is the same as the small beamwidth beam pointing towards the user device obtained by the exhaustive directional scanning method. Similarly, [Fig. 15] is substantially identical to [Fig. 13], which illustrates that the small beamwidth beam pointing towards the second user device obtained by the beam selection method according to the embodiment described above in relation to Figures 9, 11, and 13 is the same as the small beamwidth beam pointing towards the second user device obtained by the exhaustive directional scanning method.

[0061] Tests were carried out to compare the number of beam emission steps required when implementing the PI beam selection method according to the embodiment illustrated in [Fig. 5], [Fig. 6], and [Fig. 7] with the number of beam emission steps required when implementing a first comparison beam selection method PCI and a second comparison beam selection method PC2. The first comparison method PCI corresponds to the exhaustive directional scanning selection method. The second comparison method PC2 corresponds to an iterative scanning selection method.

[0062] Fig. 16, Fig. 17, and Fig. 18 each represent the number Z of steps required during the implementation of the beam selection process according to the embodiment illustrated in Fig. 5, Fig. 6, and Fig. 7, during the implementation of the beam selection process PI according to the embodiment illustrated in Fig. 5, Fig. 6, and Fig. 7, of the first comparison process PCI, and of the second comparison process PC2 for a multi-source antenna array 10 comprising Sub-RISj subsets of elementary antennas 12 as a function of the number NA which corresponds to the square root of the number of elementary antennas 12 of each Sub-RISj subset of elementary antennas 12.

[0063] In [Fig. 16], the multi-source antenna array 10 comprises two Sub-RISj subsets of elementary antennas 12. In [Fig. 17], the multi-source antenna array 10 comprises four Sub-RISj subsets of elementary antennas 12. In [Fig. 18], the multi-source antenna array 10 comprises eight Sub-RISj subsets of elementary antennas 12.

[0064] Figures 16, 17, and 18 show that the number of beam emission steps in the PI beam selection process according to the embodiment illustrated in [Fig. 5], [Fig. 6], and [Fig. 7] is less than the number of beam emission steps in the first PCI comparison method, and the number of beam emission steps of the second PC2 comparison method.

[0065] Figures 16, 17, and 18 allow for a comparison of the performance of three different selection processes. The graphs show the number of steps required to find the best beam with a variable number of user devices and a variable number of Sub-RISj subsets of elementary antennas 12.

[0066] In the scenario with two user devices ([Fig. 16]), the number of steps required for beam optimization is shown for different NA numbers corresponding to the square root of the number of elementary antennas 12 per Sub-RISj subset (10, 20, 40, and 80) (which corresponds to 100, 400, 1600, and 6400 elementary antennas 12 per Sub-RISj subset). The selection process according to the present embodiment has the fewest steps in all configurations of the number of Sub-RISj subsets, indicating an efficient beam selection process. The exhaustive directional scanning selection process generally requires more steps, reflecting the structured nature of the scanning and beam refinement.The iterative scanning selection process lies between the two, showing improved efficiency compared to the exhaustive directional scanning selection process but a reduction in steps not as significant as the selection process according to the present embodiment.

[0067] In the case of four user devices, [Fig. 17] shows an increase in the number of steps for all processes compared to the scenario with two user devices, which is expected since a larger number of user devices generally introduces more complexity into the system. The selection process according to the present embodiment again demonstrates the smallest number of steps required for optimization.

[0068] In a more complex network environment with user equipment, the tendency for increasing the number of steps required for beam optimization with more Sub-RISj subsets of elementary antennas 12 is evident for all methods. Figure 18 shows that the selection process according to the present embodiment consistently requires the fewest steps, demonstrating robustness to the added complexity of numerous simultaneous user equipment connections. This reflects the ability of the selection process according to the present embodiment to efficiently handle a dense user environment. In comparison, the exhaustive directional scanning and iterative scanning selection processes require a significantly higher number of steps, with the exhaustive directional scanning process exhibiting the highest number.This indicates that as the number of user devices increases, the benefits of the... selection process according to this embodiment in terms of reducing optimization steps become more pronounced, resulting in better performance in areas with high user density.

[0069] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0070] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Method for selecting beams from a base station (BS) to user equipment (UE1, UE2), the base station (BS) comprising a multi-source antenna array comprising subsets (Sub-RISi, Sub-RIS2) of elementary antennas (12), the method comprising the following steps: a) emission, by each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), in successive emission steps, of a beam, all beams having the same beamwidth, and, for each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), all beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) pointing in directions different from each other and different from the directions of the beams emitted by each other subset (Sub-RISi, Sub-RIS2) of elementary antennas (12);and b) reception by the base station (BS) of a signal emitted by each user equipment (UE1, UE2) indicating at which transmission stage among the transmission stages the maximum power beam was received by said user equipment (UE1, UE2).

2. A method according to claim 1, wherein steps a) and b) are repeated up to a final implementation, the width of the beams emitted at the second implementation of step a) being less than the width of the beams emitted at the first implementation of step a).

3. A method according to claim 2, wherein, in the second implementation of step a), the emitted beams are included in the beams emitted in the first implementation of step a) and indicated by the signals emitted by the user equipment in the first implementation of step b).

4. A method according to claim 2 or 3, comprising, after the last implementation of step b), a step c) of successively emitting by each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) beams having the same beamwidth, and, for each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), all beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) pointing in directions different from each other and different from the directions of the beams emitted by each other subset (Sub-RISi, Sub-RIS2) of elementary antennas (12).

5. A method according to claim 4, wherein the width of the beams emitted in step c) is less than the width of the beams emitted in the last implementation of step a).

6. A method according to claim 5, wherein, in step c), the emitted beams are included in the beams emitted in the last implementation of step a) and indicated by the signals emitted by the user equipment in the last implementation of step b).

7. A method according to any one of claims 1 to 6, wherein the emission steps comprise a succession of first emission steps and a succession of second emission steps, the method comprising the following steps: - emission, by each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), at each first emission step of the succession of first emission steps, of a first beam pointing in a first direction and having a first beamwidth, all first beams having the same first beamwidth, and, for each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), all first beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) pointing in first directions different from each other and different from the first directions of the first beams emitted by each other subset (Sub-RISi,Sub-RIS2) of elementary antennas (12); - reception by the base station (BS) of a first signal emitted by each user equipment (UE1, UE2) indicating at which first transmission stage, called the first maximum transmission stage, among the first transmission stages, the first maximum power beam was received by said user equipment (UE1, UE2); - transmission, by each subset (Sub-RIS1, Sub-RIS2) of elementary antennas (12), at each second transmission stage of the succession of second transmission stages, of a second beam pointing in a second direction and having a second beamwidth less than the first beamwidth, all second beams having the same second beamwidth, beam, and, for each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), all second beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) being included in the first beams emitted at the first maximum emission stages, pointing in second directions different from each other and different from the second directions of the second beams emitted by each other subset (Sub-RISi, Sub-RIS2) of elementary antennas (12); and - reception by the base station (BS) of a second signal emitted by each user equipment (UE1, UE2) indicating at which second emission stage, called second maximum emission stage, among the second emission stages the second maximum power beam was received by said user equipment (UE1, UE2).

8. A method according to claim 7, wherein the emission steps further comprise a succession of third emission steps, the method further comprising the following steps: - emission, successively for each second beam emitted at the second maximum emission steps, by the subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) having emitted said second beam, at each third emission step of the succession of third emission steps, of third beams pointing in third directions and having a third beamwidth less than the second beamwidth, all third beams having the same third beamwidth, and all third beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) being included in said second beam,the third beams pointing in different third directions from each other and different from the third directions of the third beams emitted by each other subset (Sub-RIS1, Sub-RIS2) of elementary antennas (12); and - reception by the base station (BS) of a third signal emitted by each user equipment (UE1, UE2) indicating at which third transmission stage, called the maximum third transmission stage, among the third transmission stages was received the, third maximum power beam by said user equipment (UE1, UE2).

9. Base station (BS) comprising a multi-source antenna array comprising subsets (Sub-RISi, Sub-RIS2) of elementary antennas (12), the base station being configured to implement a beam selection method to user equipment (UE1, UE2) comprising the repetition of the following steps: - emission, by each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), at successive emission steps, of a beam, all beams having the same beamwidth, and, for each subset (Sub-RISi, Sub-RIS2) of elementary antennas (12), all beams emitted by said subset (Sub-RISi, Sub-RIS2) of elementary antennas (12) pointing in directions different from each other and different from the directions of the beams emitted by each other subset (Sub-RISi, Sub-RIS2) of elementary antennas (12);and - reception of a signal from each user equipment (UE1, UE2) indicating at which transmission stage among the transmission stages the maximum power beam was received by said user equipment (UE1, UE2).;

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