CN115989640A

CN115989640A - Beam management

Info

Publication number: CN115989640A
Application number: CN202080103579.8A
Authority: CN
Inventors: 王文剑
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2023-04-18
Also published as: WO2022041118A1

Abstract

Embodiments of the present disclosure relate to beam management. The first device receives a first set of reference signals from the second device via a set of receive beams. The first set of reference signals corresponds to a second set of reference signals transmitted via a first set of transmit beams of a second device. The first device determines a target receive beam for receiving signals from the second device from among the set of receive beams based on at least information about the first set of transmit beams, information about the set of receive beams, the first set of reference signals, and the second set of reference signals. The first device sends an indication of a target receive beam to the second device. In this way, a target receive beam for receiving signals from the second device can be determined at the first device based on the reference signal with low complexity and low delay.

Description

Beam management

Technical Field

Embodiments of the present disclosure relate generally to the field of telecommunications, and in particular, to devices, methods, apparatuses, and computer-readable storage media for beam management.

Background

Terrestrial networks have difficulty providing communication coverage, such as fifth generation (5G) communication coverage, because resources and infrastructure in remote areas are always limited. Therefore, non-terrestrial networks (NTN) were introduced. One of the benefits of introducing NTN is the ability to provide ubiquitous 5G services to end devices (e.g., user equipment) by spreading connections in low population density areas where device density is extremely low. At the same time, the overall cost of deployment will be much lower than providing permanent infrastructure locally. Furthermore, the use of space-borne (space-borne) or airborne (air-borne) platforms can provide reliable coverage in remote areas, which has significant advantages. However, it also presents problems in other respects.

Disclosure of Invention

In general, example embodiments of the present disclosure provide a solution for beam management.

In a first aspect, a first device is provided. The first device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to: receiving a first set of reference signals from the second device via the set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second device; determining a target receive beam from the set of receive beams for receiving signals from the second device based at least on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and transmitting an indication of the target receive beam to the second device.

In a second aspect, a second apparatus is provided. The second device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the second apparatus to: transmitting a second set of reference signals to the first device via the first set of transmit beams, the second set of reference signals corresponding to the first set of reference signals received by the set of receive beams of the first device; and receiving an indication of a target receive beam from the first device.

In a third aspect, a method is provided. The method includes receiving, at a first device, a first set of reference signals from a second device via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second device; determining a target receive beam for receiving signals from the second device from the set of receive beams based on at least the information on the first set of transmit beams, the information on the set of receive beams, the first set of reference signals, and the second set of reference signals; and transmitting an indication of the target receive beam to the second device.

In a fourth aspect, a method is provided. The method includes transmitting, at the second device, a second set of reference signals to the first device via the first set of transmit beams, the second set of reference signals corresponding to the first set of reference signals received by the set of receive beams of the first device; and receiving an indication of a target receive beam from the first device.

In a fifth aspect, a first apparatus is provided that includes means for receiving a first set of reference signals from a second apparatus via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second apparatus; means for determining a target receive beam for receiving signals from the second apparatus from among the set of receive beams based at least on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and means for transmitting an indication of the target receive beam to the second apparatus.

In a sixth aspect, a second apparatus is provided that includes means for transmitting a second set of reference signals to the first apparatus via the first set of transmit beams, the second set of reference signals corresponding to a first set of reference signals received by a set of receive beams of the first apparatus; and means for receiving an indication of a target receive beam from the first apparatus.

In a seventh aspect, a computer readable medium comprising program instructions for causing an apparatus to perform at least a method according to any of the above third to fourth aspects.

It should be understood that this summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

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

FIG. 1 illustrates an example communication network in which example embodiments of the present disclosure may be implemented;

fig. 2 illustrates a signaling flow for beam selection according to some example embodiments of the present disclosure;

fig. 3A illustrates a diagram showing a process for indicating beam switching times, according to some example embodiments of the present disclosure;

fig. 3B illustrates an example of information about a switching time, according to some example embodiments of the present disclosure;

fig. 4 illustrates a flow chart of a method implemented at a terminal device, according to some example embodiments of the present disclosure;

fig. 5 illustrates a flow diagram of a method implemented at a network device, in accordance with some example embodiments of the present disclosure;

FIG. 6 shows a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

fig. 7 illustrates a block diagram of an example computer-readable medium, in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is understood that these examples are described merely to illustrate and assist those of ordinary skill in the art in understanding and practicing the disclosure, and are not intended to limit the scope of the disclosure in any way. The disclosure described herein may be implemented in various other ways than those described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

In the present disclosure, references to "one embodiment," an embodiment, "example embodiments," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be termed a second element, and, similarly, a second element may be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," "having," "has," "having," "includes" and/or "including," when used herein, specify the presence of stated features, elements, and/or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following:

(a) A purely hardware circuit implementation (such as an implementation using only analog and/or digital circuitry), and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combinations of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Hardware processor(s) with software (including digital signal processor (s)), software, and any portion of memory(s) that work together to cause a device, such as a mobile phone or server, to perform various functions, and

(c) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware)

The operation is performed but software may not exist when the operation is not needed.

The definition of circuitry is suitable for all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also encompasses implementations of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. For example, the term circuitry, if applicable to a particular claim element, also encompasses a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as Long Term Evolution (LTE), LTE-advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), high Speed Packet Access (HSPA), narrowband internet of things (NB-IoT), and so forth. Further, communication between the terminal device and the network device in the communication network may be performed according to any suitable generation communication protocol, including, but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, and/or any other protocol currently known or to be developed in the future. Embodiments of the present disclosure may be applied to various communication systems. Given the rapid development of communications, there will of course be future types of communication technologies and systems that may embody the present disclosure. The scope of the present disclosure should not be considered as being limited to the above-described systems.

As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. The network equipment may refer to a Base Station (BS) or an Access Point (AP), e.g., a NodeB (NodeB or NB), evolved NodeB (eNodeB or eNB), NR NB (also known as gNB), remote Radio Unit (RRU), radio Header (RH), remote Radio Head (RRH), relay, integrated Access and Backhaul (IAB) node, low power node (such as femto, pico), non-terrestrial network (NTN), or non-terrestrial network equipment (such as satellite network equipment, low Earth Orbit (LEO) satellite, and geosynchronous orbit (GEO) satellite), aircraft network equipment, and so forth, depending on the terminology and technology applied.

The term "terminal device" refers to any terminal device capable of wireless communication. By way of example, and not limitation, a terminal device may also be referred to as a communication device, user Equipment (UE), subscriber Station (SS), portable subscriber station, mobile Station (MS), or Access Terminal (AT). The end devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable end devices, personal Digital Assistants (PDAs), portable computers, desktop computers, image capture end devices (such as digital cameras), gaming end devices, music storage and playback devices, in-vehicle wireless end devices, wireless endpoints, mobile stations, notebook embedded devices (LEEs), notebook in-vehicle devices (LMEs), USB dongles, smart devices, wireless Customer Premises Equipment (CPE), internet of things (IoT) devices, watches or other wearable devices, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in an industrial and/or automated processing chain context), consumer electronics, devices operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

As mentioned above, the introduction of NTN also presents some problems in other respects. In particular, it is desirable to provide some physical layer process enhancement solutions that relate to NTN beam management. The inventors of the present disclosure note that beam switching occurs frequently in NTN networks. For example, in the Low Earth Orbit (LEO) case, a typical time period for beam switching is about 3 seconds. There are some problems to be solved in beam switching, whether based on inter-satellite switching or intra-satellite beam switching.

In one aspect, one of the problems is the high complexity and long training time of the beam training. In particular, a set of satellite parameters for the beamlet diameter is agreed, e.g., LEO-600 for the S band is 20km. Based on this assumption, the available service duration for each beam may be less than 3 seconds. With this assumption, beam switching can also be considered within a single satellite or even between different satellites for continuous service, since in some cases multiple satellites can serve a single UE. In this case, such beam switching is preferred within the framework of beam management. Therefore, one issue is how to implement fast single-satellite and/or multi-satellite beam management to obtain the best beam (e.g., target transmit beam(s) and/or target receive beam (s)) for communication, e.g., in single-satellite transmission and/or distributed multi-satellite transmission.

Thus, according to some example embodiments of the present disclosure, a solution for beam management is provided. In this solution, a first device receives a first set of reference signals from a second device via a set of receive beams. The first set of reference signals corresponds to a second set of reference signals transmitted via a first set of transmit beams of a second device. The first device determines a target receive beam for receiving signals from the second device from the set of receive beams based on at least information about the first set of transmit beams, information about the set of receive beams, the first set of reference signals, and the second set of reference signals. The first device transmits an indication of a target receive beam to the network device. In this way, a target receive beam for receiving information from the second device may be determined at the first device side with low complexity and low delay.

The principles and embodiments of the present disclosure will be described in detail below with reference to the drawings. Referring initially to fig. 1, fig. 1 illustrates an example communication system 100 in which embodiments of the present disclosure may be implemented.

Fig. 1 shows a schematic diagram of a communication system 100 in which embodiments of the present disclosure may be implemented. As shown, communication system 100, which may be part of a communication network, includes one or more terminal devices, such as terminal device 110-1, terminal device 110-2, and terminal device 110-3 (collectively or individually referred to as terminal device(s) 110 for ease of discussion). Terminal device 110 may be a terrestrial terminal device or an aerial terminal device. Although three terminal devices are shown, any other number of terminal devices 110 may be included in communication system 100, such as 1,2, 4, etc., and the disclosure is not limited in this respect.

Communication system 100 also includes one or more network devices, such as network device 120-1, network device 120-2 (collectively or individually referred to as "network device(s) 120" for ease of discussion). Network device 120 may be an off-the-air (air-bone) network device. For example, network device 120 may be implemented in or as a satellite. Although two network devices are shown, any other number of network devices 120 may be included in communication system 100, such as 1, 3, 4, etc., and the disclosure is not limited in this respect.

Communication system 100 may also include one or more other network devices, such as network device 150. The network device 150 may be a network device on the ground, such as an eNB or a gNB. Although one network device is shown, any other number of such above-ground network devices 150 may be included in the communication system 100, such as 2, 3, 4, etc., without limitation in this disclosure.

For purposes of illustration, terminal device 110 is sometimes referred to herein as a first device, and network device 120 is sometimes referred to herein as a second device 120. It should be understood that terminal device 110 and network device 120 are interchangeable. For example, processes or functions described as being implemented at a terminal device may also be implemented at a network device, and processes or functions described as being implemented at a network device may also be implemented at a terminal device.

In some example embodiments, the link from network device 120 to terminal device 110 may be referred to as a "downlink" and the link from terminal device 110 to network device 120 may be referred to as an "uplink".

In some example embodiments, in an NTN deployment, there are two possible scenarios. In one scenario, a network device (e.g., network device 120) may be implemented in or as a satellite. For example, the network device is mounted on a satellite and may therefore be referred to as a satellite network device. In another scenario, the network device (e.g., network device 150) may be on earth.

It should be understood that communication system 100 may also include other elements that have been omitted for clarity. It should be understood that the number of terminal devices 110, network devices 120, and networks 150 shown in fig. 1 are given for illustrative purposes and do not present any limitations.

Communications in communication system 100 may be implemented in accordance with any suitable communication protocol(s), including, but not limited to, first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G), and fifth-generation (5G) cellular communication protocols, wireless local network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and/or any other protocol currently known or developed in the future. Further, the communication may utilize any suitable wireless communication technology, including but not limited to: code Division Multiple Access (CDMA), frequency Division Multiple Access (FDMA), time Division Multiple Access (TDMA), frequency Division Duplex (FDD), time Division Duplex (TDD), multiple Input Multiple Output (MIMO), orthogonal Frequency Division Multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and/or any other technique now known or later developed.

As shown in fig. 1, network device 120-1 (e.g., a satellite) uses a set of transmit beams of network device 120-1 to serve respective areas, referred to as cell 130-1, cell 130-2, and cell 130-3. Network device 120-2 uses another set of transmit beams for network device 120-2 to serve respective areas, referred to as cell 140-1, cell 140-2, and cell 140-3. For ease of discussion, cell 130-1, cell 130-2, and cell 130-3 may be referred to collectively or individually as cell 130, and cell 140-1, cell 140-2, and cell 140-3 may be referred to collectively or individually as cell 140. It should be understood that the number of transmit beams in a group and the number of cells of network device 120 are not limited to the numbers shown in fig. 1, and may have any other suitable number of transmit beams. The scope of the present disclosure is not limited thereto.

In this disclosure, the transmit beams of the network devices described herein may be used to transmit information to the terminal device, or may be used to both transmit and receive information to and from the terminal device (e.g., in a TDD scenario where uplink and downlink channel conditions are similar).

In some example embodiments, terminal device 110-1 may be an over-the-air terminal device served by network device 120-1. In some example embodiments, terminal device 110-2 may be an over-the-air terminal device served by both network device 120-1 and network device 120-2. That is, terminal device 110-2 is served by two network devices 120 by applying appropriate techniques such as multiple transmission points (TRPs). It should be understood that the number of network devices 120 serving terminal device 110 may be any other suitable number and is not limited to the number shown in fig. 1.

Further, terminal device 110 may have a set of receive beams for receiving signals from network device 120. In one example, terminal device 110 (e.g., terminal device 110-1) may receive a transmission from network device 120-1 using one of the set of receive beams. In addition, terminal device 110 (e.g., terminal device 110-2) may also receive transmissions from another network device 120-2 using another receive beam of the set of receive beams. It should be understood that the number of receive beams in a group owned by a network device is not limited to the number shown in fig. 1, and that any other suitable number of receive beams may exist for terminal device 110.

As used herein, a receive beam of a terminal device may be used to receive information from a network device or may be used to both receive signals from and transmit information to a network device. In other words, the scope of the present disclosure is not limited thereto.

Further, as shown in FIG. 1, network device 120-1 and network device 120-2 may communicate with each other, e.g., via an Xn interface over an inter-satellite link (ISL).

Referring now to fig. 2, fig. 2 illustrates a signaling flow 200 for beam selection according to some example embodiments of the present disclosure. For purposes of discussion, the signaling flow 200 will be described with reference to fig. 1. Signaling flow 200 may involve terminal device 110 (e.g., any of terminal device 110-1 through terminal device 110-3) and one or more network devices 120 (e.g., network device 120-1 and/or network device 120-2) in fig. 1. It should be appreciated that although signaling flow 200 is described with reference to communication system 100 of fig. 1, the process is equally applicable to other communication scenarios in which different network devices are co-deployed to provide respective serving cells.

In signaling flow 200, terminal device 110 receives 202 a set of reference signals from network device 120 (e.g., network device 120-1) via a set of receive beams of terminal device 110. In some example embodiments, the set of reference signals may include channel state information reference signals (CSI-RS). Alternatively, the set of reference signals may include demodulation reference signals (DMRS). Other types of reference signals are also suitable.

The set of reference signals corresponds to the set of reference signals transmitted via the set of transmit beams of network device 120-1. In an example, the reference signals are transmitted via respective transmit beams of network device 120-1. Each transmit beam in the set of transmit beams may have an index of the transmit beam. Thus, the reference signals correspond to respective indices of the transmission beams.

After receiving the set of reference signals, terminal device 110 transmits via the transmission beam based on at least information on the set of transmission beams, information on the set of reception beamsThe set of reference signals sent, and the set of reference signals received by terminal device 110, determine 204 a target receive beam for receiving signals from network device 120-1. For example, as will be discussed in more specific examples below, the set of reference signals received by terminal 110 may be Y _i . The set of reference signals transmitted via the network device may be X _i 。

In some example embodiments, information about the set of receive beams for terminal device 110 is known at terminal device 110. In some other example embodiments, information about the set of receive beams may be configured to terminal device 110 via some other network device. It should be understood that the manner in which information regarding the set of receive beams is obtained may vary and is not limited to that described herein.

In some example embodiments, the information about the set of receive beams may include a set of angles associated with the set of receive beams. In some example embodiments, the information about the set of receive beams may include a set of amplitudes associated with the set of receive beams. Alternatively, the information about the set of receive beams may include a set of phases associated with the set of receive beams.

In some example embodiments, information regarding the set of transmit beams for network device 120-1 may be received by terminal device 110 from network device 110. However, it should be understood that terminal device 110 may also obtain information about the set of transmit beams for network device 120-1 by other methods. Scope of the disclosure not limited thereto.

In some example embodiments, the information about the set of transmit beams may include a set of angles associated with the set of transmit beams. In some example embodiments, the information about the set of transmit beams may include a set of amplitudes associated with the set of transmit beams. Alternatively or additionally, the information about the set of transmit beams may include a set of phases associated with the set of transmit beams.

In some example embodiments, terminal device 110 may obtain information regarding the set of reference signals transmitted by network device 120-1, e.g., through a default configuration. In some example embodiments, terminal device 110 may also obtain information about the set of reference signals transmitted by the network node via higher layer signaling, e.g., from network device 120-1. In such an example embodiment, after obtaining information about the set of reference signals, terminal device 110 may determine a target receive beam for receiving signals from the second device based on the received information.

In some examples, the information about the set of reference signals may be a matrix (e.g., matrix X) _i Which will be discussed in equation (2) below), which represents the set of reference signals transmitted by network device 120-1. In some other examples, the information about the set of reference signals may be a sequence, or may be in other forms. The scope of the present disclosure is not limited thereto.

In some example embodiments, based on the information about the set of transmit beams, the information about the set of receive beams, the set of reference signals received by terminal device 110, and the set of reference signals transmitted by network device 120-1, terminal device 110 may determine information about an original channel between terminal device 110 and network device 120-1. Terminal device 110 may then determine a target receive beam based on the information of the original channel. This procedure will be described in the following section more specific examples are provided.

In this way, the target receive beam can be determined, only requiring knowledge of the information about the set of transmit beams and the original channel information estimated based on the configured reference signals.

In some example embodiments, after determining the target receive beam, terminal device 110 sends 206 an indication of the target receive beam to network device 120-1. For example, the indication may be a corresponding index of the target receive beam.

In some example embodiments, after receiving the indication of the target receive beam from terminal device 110, network device 120-1 may determine 208 a target transmit beam for additional transmissions from network device 120-1 to terminal device 110 based on the indication of the target receive beam.

In some example embodiments, after determining the target transmission beam, network device 120 may transmit 210 an indication of the target transmission beam to terminal device 110 for additional communication. In some examples, the indication of the target transmit beam may be an index of the target transmit beam. As such, when network device 120 is to switch from an original transmission beam (e.g., beam a) to a target transmission beam (e.g., beam B) and notify terminal device 110 of the switch, terminal device 110 may receive the transmitted signal from the indicated target transmission beam after the switch (details regarding the exact beam switch time will be discussed in the following section).

In some other example embodiments, network device 120-1 may also receive an indication of the target transmit beam from another network device (e.g., network device 150) for use in another transmission. In one example, network device 120 may be a satellite that is unable to determine a target transmit beam for additional transmissions. In such an example, a network device on the ground (e.g., network device 150) may determine a target transmit beam and indicate it to network device 120-1 in the satellite. In this way, network device 120-1 may forward the target transmit beam received from network device 150 on the ground to terminal device 110.

According to some example embodiments of the present disclosure, a pair of best beams (i.e., a target transmit beam and a target receive beam) for communication between a terminal device and a network device is determined such that fast beam alignment can be achieved. In this solution, the terminal device only needs to acquire the transmission beam information and the original channel information estimated based on the configured reference signal.

More specific examples will be described below. In this example, assume that network device 120-1 has Mi transmit antenna elements and terminal device 110 has N antenna elements. As a result, the downlink channel

It is assumed that different reference signals (e.g., transmitted on CSI-RS resources) are used for different beams to identify a beam index. It may also be assumed that the set of transmit beams Φ at network device 120-1 is T _i And the terminal deviceThe set of receive beams Θ at device 110 is S. In this way, terminal device 110 may collect all received reference signals from network device 120-1 as follows:

Y _i ＝Q _i H _i P _i X _i +N _i (1)

wherein the matrix Y _i Representing a set of reference signals received from network device 120-1, matrix Q _i Representing a set of receive beams, P, for terminal device 110 for a link between network device 120-1 and terminal device 110 _i Represents a set of transmit beams, X, at network device 120-1 _i Represents a set of reference signals transmitted from network device 120-1 that may be used by terminal device 110 to identify a beam index, matrix N _i Is a noise matrix.

To accurately express the equation and find the input-output relationship, equation (1) is extended to the following equation (2):

according to equation (2), if the information Φ is known at the terminal device 110, H _i Can be estimated as:

wherein A is ^- And A ⁺ Is the inverse and pseudo-inverse of A, which may be Q _i 、X _i Or P _i 。X _i May be indicated from a higher layer or by a default configuration. To obtain a matrix H _i Can use equation (3). Terminal device 110 may then obtain the complete downlink channel matrix

And the best transmit beam pair for the link may be determined by:

in the case of the equation (4),

and &>

Are the respective functions of a general singular value decomposition (gsvd) used to obtain the left and right principal singular vectors of the input matrix to which the dimensions are aligned for each link transmission requirement. As a result, a target transmit beam and a target receive beam (i.e., an optimal beam pair) may be determined for the link, respectively

i＝1)。

In some example embodiments, for distributed multi-network device (e.g., multi-satellite device) transmissions, terminal device 110 (e.g., terminal device 110-2) may be served by two or more network devices 120 (e.g., both network device 120-1 and network device 120-2). In this case, terminal device 110 may consider groups of receive beams from two or more network devices 120 jointly in order to compress some of the channel interference and improve the quality of the effective channel. In this case, in addition to receiving the set of reference signals from network device 120-1 as described above, terminal device 110 may also receive 203 a set of reference signals from another network device 120-2 via the set of receive beams of terminal device 110. The set of reference signals corresponds to the set of reference signals transmitted via network device 120-2. For example, the reference signals may be transmitted via respective transmit beams of network device 120-2. Each beam in the respective set of transmit beams may have a corresponding beam index. Thus, the reference signals correspond to respective indices of the transmit beams of network device 120-2.

In some example embodiments, after receiving sets of reference signals from both network device 120-1 and network device 120-2, terminal device 110 may determine a target receive beam for receiving signals from network device 120-1 based on information about the set of transmit beams for network device 120-1 and the set of transmit beams for network device 120-2, information about the set of receive beams, the set of reference signals transmitted via the transmit beam for network device 120-1 and the set of reference signals transmitted via the transmit beam for network device 120-2, and the two sets of reference signals received by terminal device 110.

In some example embodiments, after determining the target receive beam, an indication of the target receive beam may be transmitted to network device 120-1. The following process is similar to the above process and thus will not be described in detail herein.

With the above solution, a low complexity and low delay beam alignment scheme can be achieved. In addition, cooperative beam management implementations between multiple network devices 120 (e.g., multiple satellites) may be avoided. Furthermore, the network device 120 only needs to know information about the transmission beam and the reference signal. In addition, by jointly considering each set of receive beams, the quality of the effective channel can be improved.

In some example embodiments, terminal device 110 may also have respective sets of receive beams for network device 120-1 and network device 120-2. In this case, terminal device 110 may determine a target receive beam for receiving signals from network device 120-1 based on information about the two sets of transmit beams for network device 120-1 and network device 120-2, information about the two sets of receive beams, two sets of reference signals transmitted via the transmit beams for network device 120-1 and network device 120-2, and two sets of reference signals received by terminal device 110.

In some example embodiments, terminal device 110 (e.g., terminal device 110-2) may determine information about two or more channels, including, for example, the channel between terminal device 110 and network device 120-1 and the channel between terminal device 110-2 and network device 120-2, as described above with reference to equation (3). That is, using equation (3), terminal device 110 may obtain the complete downlink channel matrix

And &>

And the best transmit beam pair for each link can be found according to equation (5):

in this way, the best beam pair for each link can be obtained

i =1,2, a low complexity and low delay beam alignment scheme can be achieved, as described above.

It should be understood that there may be two or more network devices 120 serving terminal device 110, and the scope of the present disclosure is not limited in this respect.

In some example embodiments, there may be three network devices 120 serving one terminal device 110 (not shown). Thus, the optimal transmit beam and optimal receive beam pair for each link may be determined according to equation (6) below:

in some example embodiments, if there are n network devices serving one terminal device 110, the optimal transmit beam and optimal receive beam pair for each link may be determined according to equation (7) below:

in addition to beam selection, on the other hand, once the best beam pair is selected, when beam switching occurs on the terminal device 110 side and the network device 120 side is another issue that needs to be considered for the NTN scenario.

In particular, for example, table 1 below shows the maximum coverable distance of NTN satellites according to assumptions and round-trip time delays in the 3GPP specifications.

TABLE 1 NTN scenarios satellite Earth distance and round trip time

As indicated above, the signal propagation time between the satellite and the ground or air terminal equipment 110 in the NTN is known to be very long. For example, in a regenerated payload for a service link only, the maximum round trip time delay (RTD) would exceed 12.88ms for a satellite at an altitude of 600 km. The specific value depends on the altitude of the satellite and its elevation at the UE.

Furthermore, when network device 120 (e.g., a satellite) decides a new beam to switch to, terminal device 110 must know the new beam. Network device 120 may send a message (e.g., a MAC-CE command) to notify terminal device 110 of the beam switch. As a result, once the message including the processing time of terminal device 110 is correctly and fully decoded, terminal device 110 may determine that a beam switch has occurred. Therefore, over-reliability must be ensured during this time, otherwise the transmission will fail unnecessarily, violating system performance. Thus, both network device 120 (e.g., a gNB) and terminal device 110 (e.g., a UE) should know which beam network device 120 is using for transmission and on which beam terminal device 110 is attempting to receive signals at any given time.

However, the MAC-CE commands are not discussed in detail based on the selected beam to be switched at the satellite network device within or between satellites, e.g., for the beam switching protocol between the UE and the gNB in the NTN. In other words, due to the long propagation delay in the NTN, a beam selection mechanism with strict synchronization between the network device 120 and the terminal device 110 is required.

Thus, a beam switching mechanism with strict synchronization between the network device 120 and the terminal device 110 is provided. Fig. 3A illustrates a diagram showing a diagram 300A for indicating beam switching times, according to some example embodiments of the present disclosure. For ease of discussion, the process 300A will be described with reference to fig. 1.

As shown in fig. 3A, in some example embodiments, network device 120 may decide to switch from beam a to beam B at time 303 in time period 302. Then, in some example embodiments, network device 120 may determine the switch time by taking into account the long propagation delay. In one example, as shown in table 1 above, it is known that for a typical LEO regenerated payload of 600km, the maximum round trip time delay (RTD) is about 12.88ms, and thus the one-way delay is about 6.44ms. Network device 120 may account for such propagation delays. For example, as shown in fig. 3A, network device 120 may determine information of the switching time of time 305 in time period 306.

In some example embodiments, network device 120 may send information to terminal device 110 for a switch time for network device 120 to switch to the target transmit beam and for terminal device 110 to switch to the target receive beam. As described above, the target transmission beam is used for further transmissions from the network device 120 to the terminal device 110. Similarly, the target receive beam is used at terminal device 110 and is used to receive additional transmissions from network device 120.

Accordingly, in some example embodiments, network device 120 performs a handover to the target transmission beam based on the information of the handover time, rather than performing the handover during time period 304 during which time period 304 terminal device 110 may not have successfully received and decoded a packet including an indication of the target transmission beam.

In some example embodiments, the information of the switching time may include an indication of a frame. In some example embodiments, the information of the switching time may comprise an indication of a subframe. In some example embodiments, the information of the switching time may comprise an indication of the time slot. Alternatively, the information of the switching time may comprise an indication of the symbol.

Fig. 3B illustrates an example of information 300B regarding a switching time, according to some example embodiments of the present disclosure. For ease of discussion, an example of information 300B will be described with reference to fig. 1.

As shown in fig. 3B, the information of the switching time may include a frame indicator 310, a subframe indicator 320, a slot number 330, and a symbol number 340, which may be included in one octet (i.e., eight bits).

For example, among the eight bits, the frame indicator may occupy one bit. In such an example, when the value is set to zero, the switching will be applied within the same frame, otherwise when the value is set to 1, the switching will occur in the next frame, rather than the current frame in which the information is sent. Five bits may be used to jointly represent the number of sub-frame indicators and slots in a frame in which a beam switch (e.g., a beam switch from beam a to beam B) occurs. In some examples, # # # #0 and # # #1 may be reserved as slot #0 and slot #1. The number of symbols in the slot in which the beam switching occurs can be expressed in a granularity of three symbols using two bits. Although a specific example is provided above, it should be understood that the information of the switching time may not be limited to this example and may also be represented in other possible ways.

In some example embodiments, after receiving the information of the switching time, terminal device 110 may perform switching to the target beam based on the information of the switching time. In this way, it is ensured that terminal device 110 and network device 120 are able to have exactly the same understanding of when beam switching occurs, so that they can perform switching at the same time, thereby avoiding packet failures and potential beam misalignments.

As described above, it is known that for a typical LEO regeneration payload of 600km, the maximum RTD is about 12.88ms, and therefore the one-way delay is about 6.44ms. Even though the common delay can be compensated, the differential delay is about 390km, which is equivalent to 4.186ms delay. As a result, the frame indicator, the subframe and the slot indicator need to have high resolution, and a symbol indicator having three symbol granularities (0.1 ms resolution) is sufficient to cover the NTN scene.

In some example embodiments, the information of the switching time may be included in a medium access control element (MAC-CE) message. For example, enhanced MAC-CE octets may be provided to indicate the exact timing of beam switching in the NTN.

It should be understood that the above-described handoff solutions may be used for both single and multi-satellite transmission systems, and the scope of the present application should not be limited thereto.

Fig. 4 illustrates a flowchart of an example method 400 implemented at a first device, according to some example embodiments of the present disclosure. For purposes of discussion, the method 400 will be described with reference to fig. 1 from the perspective of the first device.

At block 410, a first device (e.g., terminal device 110 in fig. 1) receives a first set of reference signals from a second device (e.g., network device 120-1) via a set of receive beams. The first set of reference signals corresponds to a second set of reference signals transmitted via a first set of transmit beams of a second device. At block 420, the first device determines a target receive beam from the set of receive beams for receiving signals from the second device based at least on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals. At block 430, the first device transmits an indication of a target receive beam to the second device.

In some example embodiments, determining the target receive beam comprises: determining information about a channel between the first device and the second device based on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and determining a target receive beam based on the information about the channel.

In some example embodiments, the method 400 further comprises: receive a third set of reference signals from a third device (e.g., network device 120-2 in fig. 1) via the set of receive beams, the third set of reference signals corresponding to a fourth set of reference signals transmitted via a second set of transmit beams of the third device, and determining a target receive beam comprises: the target receive beam is determined based on the information about the first and second sets of transmit beams, the information about the set of receive beams, and the first, second, third, and fourth sets of reference signals.

In some example embodiments, determining the target receive beam comprises: determining information about a first channel between the first device and the second device and information about a second channel between the first device and the third device based on the information about the first set of transmission beams and the second set of transmission beams, the information about the set of reception beams, and the first set of reference signals, the second set of reference signals, the third set of reference signals, and the fourth set of reference signals; and determining a target reception beam based on the information on the first channel and the information on the second channel.

In some example embodiments, the method 400 further comprises: receiving, from the second device, an indication of a target transmit beam for further transmissions from the second device to the first device, the target transmit beam being determined from the first set of transmit beams based on the indication of the target receive beam.

In some example embodiments, the method 400 further comprises: receiving information about the first set of transmit beams from the second device, and the information about the first set of transmit beams includes at least one of: a set of angles associated with the first set of transmit beams, a set of amplitudes associated with the first set of transmit beams, and a set of phases associated with the first set of transmit beams.

In some example embodiments, the method 400 further comprises: obtaining information about a second set of reference signals from a second device; and determining a second set of reference signals based on the received information.

In some example embodiments, the information about the set of receive beams comprises at least one of: a set of angles associated with the set of receive beams, a set of amplitudes associated with the set of receive beams, and a set of phases associated with the set of receive beams.

In some example embodiments, the method 400 further comprises: receiving, from the second device, information for a handover of the second device to a target transmit beam and a handover time for the handover of the first device to a target receive beam, the target transmit beam being used for further transmissions from the second device to the first device; and performing a handover to the target reception beam based on the information of the handover time.

In some example embodiments, the information of the switching time comprises at least one of: an indication of a frame, an indication of a subframe, an indication of a slot, and an indication of a symbol.

In some example embodiments, receiving the information of the switching time comprises: the information of the switching time is received via enhanced medium access control element signaling.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

Fig. 5 illustrates a flowchart of an example method 500 implemented at a second device (e.g., network device 120), in accordance with some example embodiments of the present disclosure. For purposes of discussion, the method 500 will be described with reference to fig. 1 from the perspective of the second device.

At block 510, the second device transmits a second set of reference signals to the first device via the first set of transmit beams. The second set of reference signals corresponds to the first set of reference signals received through the set of receive beams of the first device. At block 520, the second device receives an indication of a target receive beam from the first device.

In some example embodiments, the method 500 further comprises: determining, based on the indication of the target receive beam, a target transmit beam from the first set of transmit beams for further transmission from the second device to the first device; and transmitting an indication of the target transmit beam to the first device.

In some example embodiments, the method 500 further comprises: an indication of a target transmit beam for additional transmissions from the second device to the first device is received from a fourth device (e.g., network device 150 in fig. 1). In some example embodiments, the second device transmits an indication of the target transmit beam to the first device.

In some example embodiments, the method 500 further comprises: information is transmitted to the first device regarding a first set of transmit beams of the second device. The information about the first set of transmit beams includes at least one of: a set of angles associated with the first set of transmit beams, a set of amplitudes associated with the first set of transmit beams, and a set of phases associated with the first set of transmit beams.

In some example embodiments, the method 500 further comprises: transmitting information about the second set of reference signals to the first device via higher layer signaling.

In some example embodiments, the information about the set of receive beams includes at least one of: a set of angles associated with the set of receive beams, a set of amplitudes associated with the set of receive beams, and a set of phases associated with the set of receive beams.

In some example embodiments, the method 500 further comprises: information for a second device to switch to a target transmit beam and for a switch time for the first device to switch to a target receive beam is transmitted to the first device. The target transmit beam is used for further transmissions from the second device to the first device. In some example embodiments, the second device performs the handover to the target transmission beam based on the information of the handover time.

In some example embodiments, sending the information of the switching time comprises: the information of the switching time is sent via enhanced medium access control element signaling.

In some example embodiments, a first apparatus (e.g., terminal device 110) capable of performing any of method 400 may include means for performing the respective steps of method 400. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

In some example embodiments, the first apparatus comprises: means for receiving a first set of reference signals from the second apparatus via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second apparatus; means for determining a target receive beam for receiving signals from the second apparatus from the set of receive beams based on at least the information on the first set of transmit beams, the information on the set of receive beams, the first set of reference signals, and the second set of reference signals; and means for transmitting an indication of the target receive beam to the second apparatus.

In some example embodiments, the means for determining a target receive beam comprises: means for determining information about a channel between the first apparatus and the second apparatus based on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and means for determining a target receive beam based on the information about the channel.

In some example embodiments, the first apparatus further comprises: means for receiving a third set of reference signals from the third apparatus via the set of receive beams, the third set of reference signals corresponding to a fourth set of reference signals transmitted via a second set of transmit beams of the third apparatus, and means for determining a target receive beam comprising: means for determining a target receive beam based on the information about the first and second sets of transmit beams, the information about the set of receive beams, and the first, second, third, and fourth sets of reference signals.

In some example embodiments, the means for determining the target receive beam comprises: means for determining information about a first channel between the first apparatus and the second apparatus and information about a second channel between the first apparatus and the third apparatus based on the information about the first set of transmit beams and the second set of transmit beams, the information about the set of receive beams, and the first set of reference signals, the second set of reference signals, the third set of reference signals, and the fourth set of reference signals; and means for determining a target receive beam based on the information about the first channel and the information about the second channel.

In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, an indication of a target transmit beam for further transmissions from the second apparatus to the first apparatus, the target transmit beam being determined from the first set of transmit beams based on the indication of the target receive beam.

In some example embodiments, the first apparatus further comprises: means for receiving information about the first set of transmit beams from the second apparatus. The information about the first set of transmit beams includes at least one of: a set of angles associated with the first set of transmit beams, a set of amplitudes associated with the first set of transmit beams, and a set of phases associated with the first set of transmit beams.

In some example embodiments, the first apparatus further comprises: means for obtaining information about a second set of reference signals from a second apparatus; and means for determining a second set of reference signals based on the received information.

In some example embodiments, the first apparatus further comprises means for receiving, from the second apparatus, information for handover of the second apparatus to a target transmit beam and a handover time for handover of the first apparatus to the target receive beam, the target transmit beam being for further transmissions from the second apparatus to the first apparatus; and means for performing a handover to the target receive beam based on the information of the handover time.

In some example embodiments, the means for receiving information of a switching time comprises: means for receiving information of a handover time via enhanced media access control element signaling.

In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

In some embodiments, a second apparatus (e.g., network device 120) capable of performing any of method 500 may include means for performing the respective steps of method 500. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

In some example embodiments, the second apparatus comprises: means for transmitting a second set of reference signals to the first apparatus via the first set of transmit beams, the second set of reference signals corresponding to the first set of reference signals received through the set of receive beams of the first apparatus; and means for receiving an indication of a target receive beam from the first apparatus.

In some example embodiments, the second apparatus further comprises means for determining, based on the indication of the target receive beam, a target transmit beam from the first set of transmit beams for further transmission from the second apparatus to the first apparatus; and means for transmitting an indication of the target transmit beam to the first apparatus.

In some example embodiments, the second apparatus further comprises: means for receiving, from the fourth apparatus, an indication of a target transmit beam for further transmission from the second apparatus to the first apparatus; and means for transmitting an indication of the target transmit beam to the first apparatus.

In some example embodiments, the second apparatus further comprises: means for transmitting information about a first set of transmit beams of a second apparatus to a first apparatus. The information about the first set of transmit beams includes at least one of: a set of angles associated with the first set of transmit beams, a set of amplitudes associated with the first set of transmit beams, and a set of phases associated with the first set of transmit beams.

In some example embodiments, the second apparatus further comprises: means for transmitting information about the second set of reference signals to the first apparatus via higher layer signaling.

In some example embodiments, the second apparatus further comprises: means for transmitting information to the first apparatus for a handover of the second apparatus to a target transmit beam and a handover time for the handover of the first apparatus to a target receive beam, the target transmit beam being for a further transmission from the second apparatus to the first apparatus; and means for performing a handover to the target transmit beam based on the information of the handover time.

In some example embodiments, the means for transmitting information of the switching time comprises: means for sending information of a handover time via enhanced medium access control element signaling.

Fig. 6 is a simplified block diagram of a device 600 suitable for implementing embodiments of the present disclosure. Device 600 may be provided to implement a communication device, such as terminal device 110, network device 120 shown in fig. 1. As shown, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processors 610, and one or more communication modules 640 coupled to the processors 610.

The communication module 640 is used for bidirectional communication. The communication module 640 has at least one antenna to facilitate communication. A communication interface may represent any interface necessary for communication with other network elements.

The processor 610 may be of any type suitable for a local technology network, and may include, by way of non-limiting example, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs) and processors based on a multi-core processor architecture. The device 600 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock that is synchronized to the main processor.

The memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read Only Memory (ROM) 624, electrically Programmable Read Only Memory (EPROM), flash memory, a hard disk, a Compact Disk (CD), a Digital Video Disk (DVD), and other magnetic and/or optical storage. Examples of volatile memory include, but are not limited to, random Access Memory (RAM) 622 and other volatile memory that does not persist through power outages.

The computer programs 630 include computer-executable instructions that are executed by the associated processor 610. The program 630 may be stored in the ROM 624. The processor 610 may perform any suitable actions and processes by loading the program 630 into the RAM 622.

Embodiments of the disclosure may be implemented by programs 630 such that device 600 may perform any of the processes of the disclosure discussed with reference to fig. 2-5. Embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

In some example embodiments, program 630 may be tangibly embodied in a computer-readable medium, which may be included in device 600 (such as in memory 620) or in other storage devices accessible to device 600. The device 600 may load the program 630 from the computer-readable medium into the RAM 622 for execution. The computer readable medium may include any type of tangible, non-volatile memory, such as ROM, EPROM, flash memory, a hard disk, a CD, a DVD, etc. Fig. 7 shows an example of a computer readable medium 700 in the form of a CD or DVD. The computer readable medium has program 630 stored thereon.

In general, the various embodiments of the disclosure may be implemented using hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product comprises computer executable instructions, such as instructions comprised in program modules, that are executed in a device on a target real or virtual processor to perform the method 600 described above with reference to fig. 2-5. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. Machine-executable instructions of program modules may be executed within local or distributed devices. In a distributed arrangement, program modules may be located in both local and remote memory storage media.

Program code for performing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of this disclosure, computer program code or related data may be carried by any suitable carrier, to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of a carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are described in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Also, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device, comprising:

at least one processor; and

at least one memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to:

receiving a first set of reference signals from a second device via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second device;

determining a target receive beam from the set of receive beams for receiving signals from the second device based at least on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and

transmitting an indication of the target receive beam to the second device.

2. The first device of claim 1, wherein the first device is caused to determine the target receive beam by:

determining information about a channel between the first device and the second device based on the information about the first set of transmit beams, the information about the set of receive beams, the first set of reference signals, and the second set of reference signals; and

determining the target receive beam based on the information about the channel.

3. The first device of claim 1, wherein the first device is further caused to:

receive a third set of reference signals from a third device via the set of receive beams, the third set of reference signals corresponding to a fourth set of reference signals transmitted via a second set of transmit beams of the third device, and

wherein the first device is caused to determine the target receive beam by:

determining the target receive beam based on information about the first and second sets of transmit beams, the information about the set of receive beams, and the first, second, third, and fourth sets of reference signals.

4. The first device of claim 3, wherein the first device is caused to determine the target receive beam by:

determining information about a first channel between the first device and the second device and information about a second channel between the first device and the third device based on information about the first set of transmit beams and the second set of transmit beams, the information about the set of receive beams, and the first set of reference signals, the second set of reference signals, the third set of reference signals, and the fourth set of reference signals; and

determining the target receive beam based on the information about the first channel and the information about the second channel.

5. The first device of claim 1, wherein the first device is further caused to:

receiving, from the second device, an indication of a target transmit beam for further transmissions from the second device to the first device, the target transmit beam being determined from the first set of transmit beams based on the indication of the target receive beam.

6. The first device of claim 1, wherein the first device is further caused to:

receiving information about the first set of transmit beams from the second device, the information about the first set of transmit beams comprising at least one of:

a set of angles associated with the first set of transmit beams,

a set of amplitudes associated with said first set of transmit beams, and

a set of phases associated with the first set of transmit beams.

7. The first device of claim 1, wherein the first device is further caused to:

obtaining information about the second set of reference signals from the second device; and

determining the second set of reference signals based on the received information.

8. The first device of claim 1, wherein the information about the set of receive beams comprises at least one of:

a set of angles associated with the set of receive beams,

a set of amplitudes associated with the set of receive beams, and

a set of phases associated with the set of receive beams.

9. The first device of claim 1, wherein the first device is further caused to:

receiving, from the second device, information for a switch time for the second device to switch to a target transmit beam and for the first device to switch to the target receive beam, the target transmit beam being used for further transmissions from the second device to the first device; and

performing a handover to the target receive beam based on the information of the handover time.

10. The first device of claim 9, wherein the information of the switching time comprises at least one of:

an indication of the frame that the user is attempting to access,

an indication of a sub-frame is provided,

an indication of a time slot, and

an indication of a symbol.

11. The first device of claim 9, wherein the first device is caused to receive the information of a switching time by:

receiving the information of the switching time via enhanced media access control element signaling.

12. The first device of claim 1, wherein the first device comprises a terminal device and the second device comprises a network device.

13. A second device, comprising:

at least one processor; and

at least one memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the second apparatus to:

transmitting a second set of reference signals to a first device via a first set of transmit beams, the second set of reference signals corresponding to a first set of reference signals received through a set of receive beams of the first device; and

receiving an indication of a target receive beam from the first device.

14. The second device of claim 13, wherein the second device is further caused to:

determining, based on the indication of the target receive beam, a target transmit beam from a first set of transmit beams for further transmissions from the second device to the first device; and

transmitting an indication of the target transmit beam to the first device.

15. The second device of claim 13, wherein the second device is further caused to:

receiving, from a fourth device, an indication of a target transmit beam for further transmissions from the second device to the first device; and

transmitting an indication of the target transmit beam to the first device.

16. The second device of claim 13, wherein the second device is further caused to:

transmitting information about the first set of transmit beams of the second device to the first device, the information about the first set of transmit beams including at least one of:

a set of angles associated with the first set of transmit beams,

a set of amplitudes associated with said first set of transmit beams, and

a set of phases associated with the first set of transmit beams.

17. The second device of claim 13, wherein the second device is further caused to:

transmitting information about the second set of reference signals to the first device via higher layer signaling.

18. The second device of claim 13, wherein the information about the set of receive beams comprises at least one of:

a set of angles associated with the set of receive beams,

a set of amplitudes associated with the set of receive beams, and

a set of phases associated with the set of receive beams.

19. The second device of claim 13, wherein the second device is further caused to:

transmitting, to the first device, information for a switch time for the second device to switch to a target transmit beam and for the first device to switch to the target receive beam, the target transmit beam being used for further transmissions from the second device to the first device; and

performing a handover to the target transmission beam based on the information of the handover time.

20. The second device of claim 19, wherein the information of the switching time comprises at least one of:

an indication of the frame that the user is attempting to access,

an indication of the sub-frame or sub-frames,

an indication of a time slot, and

an indication of a symbol.

21. The second device of claim 19, wherein the second device is caused to transmit the information of the switching time by:

sending the information of the switching time via enhanced media access control element signaling.

22. The second device of claim 13, wherein the first device comprises a terminal device and the second device comprises a network device.

23. A method, comprising:

receiving, at a first device, a first set of reference signals from a second device via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second device;

determining a target receive beam from the set of receive beams for receiving signals from the second device based at least on the information on the first set of transmit beams, the information on the set of receive beams, the first set of reference signals, and the second set of reference signals; and

transmitting an indication of the target receive beam to the second device.

24. A method, comprising:

transmitting, at a second device, a second set of reference signals to a first device via a first set of transmit beams, the second set of reference signals corresponding to a first set of reference signals received through a set of receive beams of the first device; and

receiving an indication of a target receive beam from the first device.

25. A first apparatus, comprising:

means for receiving a first set of reference signals from a second apparatus via a set of receive beams, the first set of reference signals corresponding to a second set of reference signals transmitted via a first set of transmit beams of the second apparatus;

means for determining a target receive beam from the set of receive beams for receiving signals from the second apparatus based at least on the information on the first set of transmit beams, the information on the set of receive beams, the first set of reference signals, and the second set of reference signals; and

means for transmitting an indication of the target receive beam to the second apparatus.

26. A second apparatus, comprising:

means for transmitting a second set of reference signals to a first apparatus via a first set of transmit beams, the second set of reference signals corresponding to a first set of reference signals received by a set of receive beams of the first apparatus; and

means for receiving an indication of a target receive beam from the first apparatus.

27. A computer readable medium comprising program instructions for causing an apparatus to at least perform the method of claim 23 or 24.