Methods for beam sweeping in MIMO systems

Abstract

Invention relates to a method realized by a system comprising at least an access point (100) capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment (200) capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M. Synchronization Signal Blocks (SSB) transmitted by one access point (100) are arranged to include an identity information and reflected back from by user equipment (200) sweeping all UE beams and AP beams. In one embodiment, SSB are transmitted in bursts and in another embodiment SSB are transmitted one by one.

Description

[0001] DESCRIPTION

[0002] METHODS FOR BEAM SWEEPING IN MIMO SYSTEMS

[0003] TECHNICAL FIELD

[0004] Invention relates to methods realized by a system comprising at least an access point capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M.

[0005] PRIOR ART

[0006] To address the demands of 5G and beyond, certain critical aspects have been identified, particularly in millimeter wave (mmWave) bands. These bands enable high data rates crucial for future mobile broadband access networks, leveraging compact antenna sizes that allow the construction of large arrays (e.g., > 32 elements), enhancing gains through spatial multiplexing.

[0007] Despite these advancements, challenges arise in mmWave frequencies, such as high isotropic pathloss, necessitating highly directional transmissions for outdoor cellular links. This complexity is especially evident in the initial access (IA) process, where selecting suitable transmission directions poses a significant challenge. Unlike LTE systems, where IA occurs on omni-directional channels, mmWave IA procedures must carefully choose initial transmission directions, potentially causing delays in the cell search and access process.

[0008] Beam management, a critical innovation for 5G MIMO systems and beyond, encompasses PHY and MAC layer procedures to establish and retain an optimal beam pair for IA connectivity [1]. As defined in the IEEE 802.11ad standard [2,3,4], beam management includes beam sweep and measurement, beam determination, beam reporting, beam recovery, and beam switching.

[0009] For connection establishment, beam management involves three procedures [5]:

[0010] Procedure 1 (Synchronization Signal Block (SSB)-based beam sweeping): in this step, beam sweeping takes a place at both the first scheduling entity (e.g., base station (BS)) and the second scheduling entity (e.g., user equipment) to select the best beam pair based on the RSRP measurements. In general, the selected beams are wide and may not be an optimal beam pair for data transmission and reception. For N transmit beams and M receive beams in P1 , each of the N beams are transmitted M times from BS so that each transmit beam is received over the M receive beams.

[0011] Procedure 2 (CSI-RS based transmit-end beam refinement): After the initial beam is established, obtaining a unicast data transmission with high directivity and high gain requires a beam much finer than the SSB beam. Therefore, a set of reference signal resources are configured and transmitted in different directions by using finer beams within the angular range of the beam from the initial acquisition process. Then the user node measures all these beams by capturing the signals with a fixed receive beam. Finally, the best transmit beam is selected based on the RSRP measurements on all transmit beams. This procedure focuses on transmitend beam refinement, where the beam sweeping happens at the transmit end by keeping the receive beam fixed.

[0012] Procedure 3 (CSI-RS based receiver-end beam refinement): similar to the previous step, this procedure focuses on receive-end beam adjustment, where the beam sweeping happens at the receive end given the current transmit beam. This procedure can be done if the receive node capabilities allows for it.

[0013] During IA procedure, beam sweeping process poses significant challenges to the system. Sweeping multiple beams by both the BS and user introducing a substantial time overhead. If a user has M beams and the BS has N beams, each user beam requires the BS to sweep all N beams, resulting in M times N total sweeps. This contributes to prolonged connection setup times and increased complexity for users, who must synchronize and select the optimal beam meticulously.

[0014] With the focus on P1 beam sweeping process, two types are mainly distinguishing in the literature: exhaustive- and iterative search-based beam sweeping. Iterative search relies on a pre-determined information collected in the system while exhaustive search (as defined in the 3GPP 5G NR networks) scans the whole coverage area with a pre-defined beams allowing the received node (i.e., user) to detect, determine, and select the optimum beam pairs at both sides.

[0015] Many algorithms are developed in the literature to reduce the latency time introduced by the exhaustive search-based beam sweeping procedures discussed before. [6] develops a learning algorithm namely the hierarchical beam alignment algorithm in the multipath channel to identify the optimal beam. [7] presents an Agile-Link platform (a phased array mmWave system) to find the correct alignment of the beams between a transmitter and a receiver order of magnitude faster than existing radios, while [8] present a FALP framework for Fast beam Alignment with Low-resolution Phase shifters. However, the aforementioned techniques suffer from processing overhead at the user node where the beam determination and selection are done at user side. Furthermore, a reporting process is needed between the nodes to establish the connection. These procedures have a significant impact on the time required for IA process. Therefore, our previous work [9] introduce a new concept where the beam determination and selection are done at the BS side which remove the need of reporting stage between the user and BS nodes. This is done by introducing the concept of triggering signal at user side where this signal is sent during the sweeping process to inform the BS about the user availability to establish a connection and determine an optimum beam for this connection. However, this method introduces different challenges; 1 - it suffers from multiple connectivity to different BS which introduces a significant interference and waste of spectral resources in the network, 2- it requires an extra radio resource at the user side which make it incompatible with low-cost devices such as loT devices.

[0016] The previous beam sweeping techniques in the 3GPP 5G NR networks introduce the following challenges: In the case where the beam determination and selection process are done at the user side, processing overhead is introduced to the user node while a beam reporting process is needed to inform the BS with the best beam pair to establish the connection. This reporting may fail to reach to the BS node, due to blockage or at the edge connection, which requires the network to repeat the sweeping process from the beginning. This complexity can be further compounded when users, situated at the cell edge or overlapping coverage zones of two BS beams, transmit acknowledgments specifying the beam index. Time and processing overhead are counted in this part.

[0017] In the case where the beam determination and selection are done at the BS side, an extra radio resources at the user side is needed which makes it incompatible with low-cost devices such as loT devices. Furthermore, simultaneously connectivity to different BSs may occur which introduces a significant interference and waste of spectral resources in the network especially at the cell-edge users. This simultaneous connection attempt in overlapping areas can lead to interference and collisions in the communication process.

[0018] All the problems mentioned above have made it necessary to make an innovation in the relevant technical field as a result. References

[0019] [1] Understanding 5G Beam Management, white paper, 2021 , MathWorks.

[0020] [2] Giordani, M., Polese, M., Roy, A., Castor, D. and Zorzi, M., 2018. A tutorial on beam management for 3GPP NR at mmWave frequencies. IEEE Communications Surveys & Tutorials, 21(1), pp.173-196.

[0021] [3] 3GPP, Beam Failure Detection and Beam Recovery Actions, document Tdoc RAN1#88- Bis, R1 -1705893, Ericsson, Spokane, WA, USA, Apr. 2017.

[0022] [4] NR and NG-RAN Overall Description — Release 15, 3GPP Standard TS 38.300, 2018.

[0023] [5] Li, Y.N.R., Gao, B., Zhang, X. and Huang, K., 2020. Beam management in millimeter-wave communications for 5G and beyond. IEEE Access, 8, pp.13282-13293.

[0024] [6] Wu, W., Cheng, N., Zhang, N., Yang, P., Zhuang, W. and Shen, X., 2019. Fast mmwave beam alignment via correlated bandit learning. IEEE Transactions on Wireless Communications, 18(12), pp.5894-5908.

[0025] [7] Abari, O., Hassanieh, H., Rodriguez, M. and Katabi, D., 2016, November. Millimeter wave communications: From point-to-point links to agile network connections. In Proceedings of the 15th ACM Workshop on Hot Topics in Networks (pp. 169-175).

[0026] [8] Myers, N.J., Mezghani, A. and Heath, R.W., 2019. FALP: Fast beam alignment in mmWave systems with low-resolution phase shifters. IEEE Transactions on Communications, 67(12), pp.8739-8753.

[0027] [9] Turkish Patent Application: App. No: 2022 / 022022 by L. Afeef, P. Gunis, and H. Arslan, “System and beam management method for MIMO systems”

[0028]

[0010] 3GPP R1-1712221 - 3GPP TSG RAN WG1 Meeting #90 - DL Beam Management Framework, Huawei, August 2017.

[0029]

[0011] Giordani, M., M. Polese, A. Roy, D. Castor, and M. Zorzi. “A tutorial on beam management for 3GPP NR at mmWave frequencies.” IEEE Comm. Surveys & Tutorials, vol. 21 , No. 1 , Q1 2019

[0030]

[0012] L. Afeef, P. Gunis, and H. Arslan, “System and beam management method for MIMO systems” Dec. 31 ,2022, Turk Patent (EPATS), App. No: 2022 / 022022

[0031] BRIEF DESCRIPTION OF THE INVENTION

[0032] The present invention relates to a method and system to eliminate the above-mentioned disadvantages and bring new advantages to the relevant technical field. An object of the invention is to provide a method that reduces time and processing overhead in beam sweeping of initial access procedure.

[0033] Another object of the invention is to provide a method reduce the need of extra radio resources at the user equipment side and further reduces interference.

[0034] To achieve all the objects mentioned above and that will emerge from the following detailed description, the present invention relates to a method realized by a system comprising at least an access point capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M. Accordingly, it comprises the steps of: executing a sweeping process comprising the steps of:

[0035] - by one access point transmitting Synchronization Signal Blocks (SSB) using each AP beam;

[0036] - by the user equipment receiving SSBs through at least one UE beam;

[0037] - by the user equipment adding an information (ID) block to the end of the received SSB blocks comprising information relating to user equipment identity;

[0038] - by the user equipment reflecting back the SSBs and the information block over the same UE beam that the SSBs are received;

[0039] - by at least one access point receiving SSBs reflected by the user equipment with the same order of AP beams;

[0040] - by the at least one access point performing Received Signal Strength Indicator (RSSI) measurements on received SSBs;

[0041] - by the at least one access point, selecting an optimum AP beam having maximum RSSI measurement for receiving ID block;

[0042] - by the at least one access point, receiving ID block over selected optimum AP beam;

[0043] - by the at least one access point determining identity of transmitting access point and the user equipment based on received SSBs and the ID block; repeating the sweeping process for the rest of the UE beams; by the at least one access point selecting an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment; by the at least one access point transmitting information relating to selected user equipment beam to user equipment. Thus, the complexity and computational burden of processing the received beams shift to the access point side, eliminating the need for the user equipment to engage in the process. Consequently, the user equipment no longer requires a time guard to transmit the received signal back, leading to a reduction in the time needed for the overall initial access procedure in the network. Furthermore, since the access point identity is included in the reflected SBBs, the user equipment can identify whether the received SSB belong to him or to other APs in the network which reduces the possible interference that may occur as a result of connecting multiple APs to a single user equipment.

[0044] Invention is also a method realized by a system comprising at least an access point capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M. It is characterized in that comprising the steps of: by the user equipment selecting a UE beam for receiving Synchronization Signal Blocks (SSB); executing a sweeping process comprising the steps of:

[0045] - by one access point selecting an AP beam;

[0046] - by the one access point transmitting one Synchronization Signal Block (SSB) through the selected AP beam;

[0047] - by the user equipment receiving the one SSB using selected UE beam;

[0048] - by the user equipment adding an information (ID) block to the end of the received SSB block comprising information relating to user equipment identity;

[0049] - by the user equipment reflecting back the SSB over the selected UE beam SSB is received;

[0050] - by the at least one access point receiving SSB reflected by the user equipment using selected AP beam;

[0051] - by the at least one access point performing Received Signal Strength Indicator (RSSI) measurements on received SSB and determining identity (ID) of transmitting access point and user equipment based on SSB and ID block;

[0052] - by the one access point selecting another AP beam and repeating above steps until each AP beam is selected; by user equipment selecting another UE beam and executing sweeping process until each UE beam is selected; by the one access point selecting an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment; by the at least one access point transmitting information relating to selected UE beam to user equipment.

[0053] BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a drawing illustrating schematic view of the system. Figure 2 depicts a flow chart of the first embodiment.

[0055] Figure 3 depicts a flow chart of the second embodiment.

[0056] Figure 4 is a graphic showing average sweeping time for initial access in a conventional method, the first embodiment and the second embodiment.

[0057] Figure 5 is a graphic showing average error vs SNR of the first, second embodiment and conventional methods.

[0058] REFERENCE NUMBERS GIVEN IN THE FIGURE

[0059] 100 Access point 200 User equipment

[0060] DETAILED DESCRIPTION OF THE INVENTION

[0061] In this detailed description, the subject matter is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

[0062] Present invention is a method to enhance the beam sweeping procedure to reduce initial access (IA) time overhead and complexity. Referring to figure 1 , the method is realized by a system comprising a user equipment (200), and at least one access point (100).

[0063] The user equipment (200) may be any device that tries to connect to the network through one of the access points (100). Access point (100) can be a device such as a base station, a radio head, a transmission / reception point, a New Radio, a 5thgeneration (5G) Node B (gNB), high- cost scheduling utility, etc, with multiple antenna elements and L_RF radio-frequency (RF) chains. The antenna array elements at the access point / s (100) are located in a uniform array (linear, planar, hexagonal, etc.) with inter-element spacing of half-wavelength d=A / 2 at all dimensions. Access points (100) are capable of transmitting and receiving N beams over different azimuth and elevation angles, where each transmitted signal over each beam contains one synchronization signal block (SSB) (each SSB contains four Orthogonal Frequency-Division Multiplexing (OFDM) symbols: Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS) and two Physical Broadcast Channel (PBCH)) of the cell identity (ID) and beam ID. The user equipment (200) may have single antenna or multiple antenna array with capability of transmitting and receiving over M beams where N is larger than M.

[0064] The user equipment (200) is capable of functioning as an intelligent relay known in the 5G communication. User equipment (200) may comprise antennas and beamforming means for transmitting and receiving signals. Radio frequency front-end elements such as amplifiers and filters. It may comprise a processor for processing the signal and controller for controlling the procedures. Mentioned components and working principle of the intelligent relays are well known in the art. Thus, they are not explained in mora detail herein.

[0065] Invention is a method for enhanced beam sweeping aimed at optimizing and expediting Initial Access (IA) process in Multiple Input Multiple Output (MIMO) systems in 5G NR networks realized by the above mentioned system.

[0066] In summary access point (100) initiates sweeping across all possible beams, while the user equipment (200) functions as an intelligent relay. The user equipment (200) receives the beam signal throughout the sweeping duration and promptly reflects the signal back. Before the signal reflection, the user end augments a specific frame, consisting of user equipment (200) identity (ID) and transmit beam index. The invention comprises two alternative methods. One of the methods access point (100) realizes sweeping in burst of SSBs, then UE reflects the burst of SSBs adding an ID block. In the other method, access point (100) realizes sweeping by sending SSBs one by one for each beam while user equipment (200) reflects each SSB one by one.

[0067] Referring to figure 2, in a first embodiment the system realizes a sweeping process. In sweeping process, an access point (transmitting access point) transmits Synchronization Signal Blocks (SSB) using each AP beam of N AP beams. The user equipment (200) receives SSBs through at least one UE beam of M UE beams. The user equipment (200) adds an information (ID) block to the end of the received SSB blocks comprising information relating to user equipment (200) identity. User equipment (200) reflects back the SSBs and the information block over the same UE beam that the SSBs are received. At least one access point (100) receives SSBs reflected by the user equipment (200) with the same order of AP beams. The at least one access point (100) performs Received Signal Strength Indicator (RSSI) measurements on received SSBs. A transmit access point transmits SSBs, but the same access point (100) or some of the other access points (100) may receive and process the reflected SSBs.

[0068] The at least one access point (100), selects an optimum AP beam having maximum RSSI measurement for receiving ID block. The at least one access point (100), receives ID block over selected optimum AP beam. The at least one access point (100) determines identity of transmitting access point and the user equipment (200) based on received SSBs and the ID block.

[0069] System repeats the sweeping process for the rest of the UE beams. At least one access point (100) selects an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment (200). The at least one access point (100) transmits information relating to selected UE beam to user equipment (200).

[0070] Access point (100) transmits optimum UE beam of the user equipment over modulated CSI- RS (channel state information-reference signal).

[0071] The identity block has the same structure as the Synchronization Signal block (SSB) of a given access point (100) in the standard [10,11], However, the cell identity carried in the Primary Synchronization Signal (PSS), Physical Broadcast Channel (PBCH) and Secondary Synchronization Signal (SSS) is replaced with the user equipment (200) identity.

[0072] Assume that the time required to sweep one SSB (out of N) is Ts while the time of sweeping N SSBs is TN. The sweeping process is repeated after TB second. This process is repeated M times to cover all the M beams at the UE side. Hence, the overall sweeping procedure at both AP and UE is done within M*TB seconds.

[0073] In a possible version of the first embodiment; multiple access points (100) may receive SSBs and measured RSSI levels may be similar at both access point (100). This may occur when the reflecting user equipment (200) is at the cell-edge. Access points (100) select the best beam with its corresponding access point (100) for the initial access, then SSBs that have RSSI values near to the selected one are saved in access point (100) database for a possible handover process after the connection starts for the given user equipment (200). This early handover can be done using several approaches from literature with the merging of this prior information. Hence, the handover failure rate and the ping pong rate can be reduced for such cases. Referring to figure 3, in a second embodiment one user equipment (200) selects a UE beam for receiving Synchronization Signal Blocks (SSB). The system executes a sweeping process that has the following steps: One access point (transmitting access point) selects an AP beam. The access point (100) transmits one Synchronization Signal Block (SSB) through the selected AP beam.

[0074] The user equipment (200) receives the one SSB using selected UE beam. The user equipment (200) adds an information (ID) block to the end of the received SSB block comprising information relating to user equipment (200) identity. The user equipment (200) reflects back the SSB over the selected UE beam SSB is received. The at least one access point (100) receives SSB reflected by the user equipment (200) using selected AP beam. The at least one access point (100) performs Received Signal Strength Indicator (RSSI) measurements on received SSB and determines identity (ID) of transmitting access point and user equipment (200) based on SSB and ID block. The one access point (100) selects another AP beam and repeats above sweeping steps until each AP beam is selected.

[0075] The user equipment (200) selects another UE beam and executes sweeping process until each UE beam is selected. The one access point (100) selects an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment (200). The at least one access point (100) transmits information relating to selected UE beam to user equipment (200).

[0076] Access point (100) transmits optimum UE beam of the user equipment over modulated CSI- RS (channel state information-reference signal).

[0077] In a possible version of the second embodiment; multiple access points (100) may receive SSBs and measured RSSI levels may be similar at both access point (100). This may occur when the reflecting user equipment (200) is at the cell-edge. Access points (100) select the best beam with its corresponding access point (100) for the initial access, then SSBs that have RSSI values near to the selected one are saved in access point (100) database for a possible handover process after the connection starts for the given user equipment (200). This early handover can be done using several approaches from literature with the merging of this prior information. Hence, the handover failure rate and the ping pong rate can be reduced for such cases. In a possible version of the second embodiment; K number of AP beams may be selected and K (N>K) number of SSBs may be transmitted for K number of AP beams. User equipment (200) receives K number of SSBs, adds ID block at the end of SSBs then reflects them back in the same order. Access point (100) receives SSBs in the same order.

[0078] The proposed methods are analyzed in terms of sweeping time overhead and Averaged Error. Table 1 summarizes the results of sweeping time overhead of a single UE beam.

[0079] The results show a comparison between conventional beam sweeping process, first embodiment, second embodiment where a single beam sweep at the AP side has same sweeping time in all methods with a total of 8 beams sweep at AP side. However, it is noticed that the total sweeping time can be less than 5ms in proposed second embodiment due to its applicability to have a place in context aware-based beam sweeping methods where a prior information can be used during the beam sweeping with feedback between AP and UE which further reduces the sweeping time overhead.

[0080] In contrast with the conventional case, first and second embodiment shifts the beam processing from the UE side to the AP side thus the time needed for the UE to process the received beams is 0. In the proposed approaches, the UE has to embed one ID block per transmission and only reflect the received SSBs which can be done directly at the analog part of the device without digital signal processing as compared to the conventional method. Hence, the overall beam sweeping time overhead is reduced in the proposed first and second embodiment.

[0081] Next, the proposed approaches are analyzed in terms of average sweeping time over different signal to noise ratio (SNR) levels. Average sweeping time is defined as the time needed for a UE to correctly select the correct beam for initializing the accessing with the target AP which is given as: where Q is the total possible initial access process that the access point (100) can sweep over time and q is number of the successful initial access that the user equipment (200)-access point (100) can get over time (q<Q). This analysis is shown in Figure 4. It is noticed from the figure that the proposed approaches provide faster initial access compared to conventional method as the SNR level increases. However, this enhancement comes at the cost of slight increase in selection error with (5.9)% especially at low signal to noise ratio (SNR) level. This selection error is shown in figure 5 where the average error rate is defined as total number of wrongly selected beams with its corresponding access point (100) over the total number of possible initial access process that the access point (100) can sweep over time. This error occurs due to the double fading (received and then reflect from the user equipment (200) side) that the SSBs face before processing them at the access point (100) side in the proposed approaches compared to the conventional method where the SSBs face single fading over the channel between access point (100) and user equipment (200).

[0082] Both approaches reduce the beam sweeping time employed during initial access by user equipment (200) and access point (100), where in conventional method, access point (100) transmits N beams in all directions as N SSB each SSB spans Ts window and a full SSB burst spans TN window with a period of TB. User equipment (200) receives the SS burst by M receive beams to decode the signal and sends back a report within the period TB thus the total sweeping process takes M X TBor equivalent to 4MTN. However, in first embodiment the user equipment (200) does not need a processing time window (TB- TN), user equipment (200) needs just TN(2N + 1) / N to transmit back the SSB blocks and a ID block so in total the sweeping time will be MTN(2 + ^) thus the total time will be reduced by MTN(2 - i). In the second embodiment, the UE transmits back ID block in each received SSB block thus the time required for one UE beam is 3TSand the total sweeping time will be 3MNTS= 3MTNthus the sweeping time will be reduced by MTN.

[0083] In both embodiments, Interference between access points (100) will be canceled in compared with

[0012] : in

[0012] , the UE sends a trigger signal which can be received by many access points (100) thus multi-access point connectivity with one user may occur. In first embodiment and second embodiment the UE sends back the received SSBs with his own ID block which inherently allows only one selected access point (100) to be connected with the user equipment (200).

[0084] Both embodiments reduce user equipment’s (200) requirement to be more complex by shifting the beam measurement and selection process from user equipment (200) side to access point (100) side. In addition, since the beam determination and selection are done at the access point (100) rather than the user equipment (200) side there is no need for reporting process which reduces the overall initial access time overhead.

[0085] Both embodiments can handle cell-edge user interference with multiple access points (100) and support for the user equipment (200) possible handover. For example, in case a user equipment (200) reflects SSBs from multiple access points (100) with similar RSSI level, the access points (100) will consider this user equipment (200) at the cell edge and has the opportunity to have a handover as soon as it gets the connection, thus the selected access point (100) may provide earlier handover process to handle the situation and reduce the handover failure rate and the ping pong rate.

[0086] In another possible embodiment

[0087] The proposed methods can be extended to UE localization during / after beam sweeping processing enhancement. The UE localization can be done as follow: for a system with multiple APs, if there are more than two APs, when the UE reflect multiple SSBs comes from multiple APs (more than two APs), each carrying distinct beam IDs with different codes (i.e. , each beam has its own unique index over these multiple APs) received at different times, the received SSBs at the APs can be used for UE localization. Specifically, APs can utilize these reflected beams to localize the UE by leveraging the time difference of arrival and triangulation techniques.

[0088] The proposed methods can be extended to enhance initial access in any directional scenario such as WIFI networks.

[0089] The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.

Claims

CLAIMS1. A method realized by a system comprising at least an access point (100) capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment (200) capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M characterized in that comprising the steps of: executing a sweeping process comprising the steps of:- by one access point (100) transmitting Synchronization Signal Blocks (SSB) using each AP beam;- by the user equipment (200) receiving SSBs through one UE beam;- by the user equipment (200) adding an information (ID) block to the end of the received SSB blocks comprising information relating to user equipment (200) identity;- by the user equipment (200) reflecting back the SSBs and the information block over the same UE beam that the SSBs are received;- by at least one access point (100) receiving SSBs reflected by the user equipment (200) with the same order of AP beams;- by the at least one access point (100) performing Received Signal Strength Indicator (RSSI) measurements on received SSBs;- by the at least one access point (100), selecting an optimum AP beam having maximum RSSI measurement for receiving ID block;- by the at least one access point (100), receiving ID block over selected optimum AP beam;- by the at least one access point (100) determining identity of transmitting access point and the user equipment (200) based on received SSBs and the ID block; repeating the sweeping process for the rest of the UE beams; by the at least one access point (100) selecting an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment (200); by the at least one access point (100) transmitting information relating to selected UE beam to user equipment (200).

2. A method realized by a system comprising at least an access point (100) capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment (200) capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M characterized in that comprising the steps of:by the user equipment (200) selecting a UE beam for receiving Synchronization Signal Blocks (SSB); executing a sweeping process comprising the steps of:- by one access point (100) selecting an AP beam;- by the one access point (100) transmitting one Synchronization Signal Block (SSB) through the selected AP beam;- by the user equipment (200) receiving the one SSB using selected UE beam;- by the user equipment (200) adding an information (ID) block to the end of the received SSB block comprising information relating to user equipment (200) identity;- by the user equipment (200) reflecting back the SSB over the selected UE beam SSB is received;- by the at least one access point (100) receiving SSB reflected by the user equipment (200) using selected AP beam;- by the at least one access point (100) performing Received Signal Strength Indicator (RSSI) measurements on received SSB and determining identity (ID) of transmitting access point and user equipment (200) based on SSB and ID block;- by the one access point (100) selecting another AP beam and repeating above steps until each AP beam is selected; by user equipment (200) selecting another UE beam and executing sweeping process until each UE beam is selected; by the one access point (100) selecting an optimum AP beam and an optimum UE beam based on RSSI measurements to serve the user equipment (200); by the at least one access point (100) transmitting information relating to selected UE beam to user equipment (200).

3. A system comprising at least an access point (100) capable of transmitting and receiving N number of AP (access point) beams and at least a user equipment (200) capable of transmitting and receiving M number of UE (user equipment) beams where N is larger than M, characterized in that the system is configured to realize one of the methods in claim 1 or claim 2.

Images