阅读说明：本技术 极化信息共享的方法 (Polarization information sharing method ) 是由 O·赞德 F·卢塞克 E·本特松 于 2019-06-13 设计创作，主要内容包括：一种操作接入节点(20)以波束扫描(310)的多个波束(50-55)发送无线电信号的方法,所述方法包括以下步骤：-以具有第一波束方向的第一波束(54)利用第一极化来发送(605)第一无线电信号(301),以及-以沿所述第一波束方向的第二波束(55)利用不同于所述第一极化的第二极化来发送(605、607)第二无线电信号(302),其中,所述第一无线电信号的发送根据预定规则链接到所述第二无线电信号的发送。借助于这样的链接,通信设备(30)可以基于预定规则确定第一波束(54)和第二波束(55)具有共同的方向性,但是被配置为以不同的(优选地,正交的)极化进行发送。(A method of operating an access node (20) to transmit radio signals in a plurality of beams (50-55) of a beam sweep (310), the method comprising the steps of: -transmitting (605) a first radio signal (301) with a first polarization in a first beam (54) having a first beam direction, and-transmitting (605, 607) a second radio signal (302) with a second polarization different from the first polarization in a second beam (55) along the first beam direction, wherein the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule. By means of such a link, the communication device (30) may determine, based on a predetermined rule, that the first beam (54) and the second beam (55) have a common directivity, but are configured to transmit with different (preferably orthogonal) polarizations.)

1. A method of operating a communication device (30) to determine a beam report (620) to an access node (20) based on radio signals received in a plurality of beams (50-55) of an access node beam sweep (310), the method comprising the steps of:

-receiving (610) a first radio signal (301) of a first polarization in a first beam (54) having a first beam direction, and

-receiving (605, 607) second radio signals (302) of a second polarization in a second beam (55) in the first beam direction, the second polarization being different from the first polarization,

determining, based on a predetermined rule, that the first radio signal and the second radio signal are transmitted in different polarizations but in a common direction.

2. A method of operating an access node (20) to transmit radio signals in a plurality of beams (50-55) of a beam sweep (310), the method comprising the steps of:

-transmitting (605) a first radio signal (301) with a first polarization in a first beam (54) having a first beam direction, and

-transmitting (605, 607) second radio signals (302) with a second polarization in a second beam (55) in the first beam direction, the second polarization being different from the first polarization,

wherein the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule.

3. The method according to claim 1 or 2, wherein a first Beam Identity (BI) assigned to the first beam (54) is comprised in the first radio signal and a second Beam Identity (BI) assigned to the second beam (55) is comprised in the second radio signal.

4. The method according to any of the preceding claims, wherein the first beam (54) and the second beam (55) have a common beam identity (BI0), and wherein the first radio signal (301) is allocated a first set of radio resources and the second radio signal is allocated a second set of radio resources, wherein the predetermined rule links the first set of radio resources to the second set of radio resources.

5. The method according to any of the preceding claims, wherein the first radio signal and the second radio signal are transmitted in a common Beam Identity (BI) in consecutive transmissions in one beam sweep (310).

6. The method according to claim 3, wherein the predetermined rule links the first beam identity (BI0) to the second beam identity (BI 1).

7. The method of claim 2, wherein the step of transmitting is performed in a first beam sweep (310), wherein the predetermined rule comprises performing a second beam sweep (330), in which second beam sweep (330) the second beam identity (BI1) is assigned to the first beam (54) and the first beam identity (BI0) is assigned to the second beam (55).

8. The method according to claim 2, comprising the steps of:

receiving (608) a beam report (620) from a communication device (30) based on the transmitted radio signals, the communication device (30) being configured to identify a link between the first radio signal and the second radio signal according to the predetermined rule, wherein the beam report (620) comprises an indication of radio resource locations allocated to one or more transmission beams.

9. An access node (20), the access node (20) comprising:

-an antenna arrangement (22), the antenna arrangement (22) being for transmitting radio signals in a plurality of beams (50-55) of a beam sweep; and

-a logic (21), the logic (21) being coupled to the antenna device (22) and configured to:

transmitting (605) a first radio signal (301) with a first polarization in a first beam (54) having a first beam direction, an

Transmitting (605, 607) a second radio signal (302) with a second polarization in a second beam (55) in the first beam direction, the second polarization being different from the first polarization,

wherein the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule.

10. A communication device (30), the communication device (30) comprising:

-an antenna (31, 32), the antenna (31, 32) being for receiving radio signals transmitted in a plurality of beams (50-55) of a beam sweep; and

-a logic (31), the logic (31) being coupled to an antenna arrangement (22) and configured to:

receiving (610) a first radio signal (301) of a first polarization with a first beam (54) having a first beam direction, an

Receiving (605, 607) second radio signals (302) of a second polarization in a second beam (55) in the first beam direction, the second polarization being different from the first polarization,

determining, based on a predetermined rule, that the first radio signal and the second radio signal are transmitted in different polarizations but in a common direction.

Technical Field

The present invention relates to a method for operating a wireless communication system, in particular to a method for operating an access node of a wireless communication system according to Multiple Input Multiple Output (MIMO) techniques. Furthermore, the invention relates to an access node and a wireless communication system supporting the method.

Background

The increased use of mobile voice and data communications may require more efficient use of available radio frequency resources. In order to improve data transmission performance and reliability, so-called Multiple Input Multiple Output (MIMO) technology may be used in a wireless telecommunication system to transmit information between devices (e.g., between a base station and a user equipment). User devices may include mobile devices such as mobile phones, mobile computers, tablet computers, or wearable devices, as well as stationary devices such as personal computers or cash registers. In a system using MIMO technology, a device may use multiple transmit and receive antennas. For example, the base station and the user equipment may each include multiple transmit and receive antennas. MIMO technology forms the basis of coding techniques that exploit the temporal and spatial dimensions to transmit information. The enhanced coding provided in MIMO systems may increase the spectral and energy efficiency of wireless communications.

The spatial dimension may be used by spatial multiplexing. Spatial multiplexing is a transmission technique in MIMO communication for transmitting independent and individually encoded data signals (i.e., so-called streams) from individual transmit antennas or combinations of transmit antennas of a plurality of transmit antennas. Thus, the spatial dimension is reused or multiplexed more than once.

By full-dimensional mimo (fdmimo) is meant a technique of arranging signals transmitted to antennas in a beam that can excite multiple receivers in three dimensions. For example, a base station may comprise a large number of active antenna elements in a two-dimensional grid, and the use of FDMIMO technology enables many spatially separated users to be supported simultaneously on the same time/frequency resource block. This may reduce interference from overlapping transmissions to other receivers and increase signal power. The beams may form virtual sectors, which may be static or dynamic from the base station perspective. The large number of antennas of the base station spatially concentrates radio energy in transmission, and directionally-sensitive reception, which improves spectral efficiency and radiation efficiency. In order to adjust the transmitted signal at each individual antenna of the base station according to the currently active receiving user equipment, the base station logic may need information about the radio channel properties between the user equipment and the base station antenna. Vice versa, in order to adjust the transmitted signal at each individual antenna of the user equipment, the user equipment logic may need information about the radio channel properties between the base station and the user equipment's antennas. For this purpose, so-called channel sounding may be performed to determine radio channel properties between the user equipment and the base station. Channel sounding may include transmitting predefined pilot signals, which may allow the base station and user equipment to set their configured antenna parameters to transmit signals to gather radio energy or to receive radio signals from a particular direction.

As the operating frequency increases and thus the wavelength decreases, the antenna aperture becomes smaller, and thus the received power can be increased using multiple antennas. In particular, in the case of high transmission frequencies, for example above 30GHz, and multiple antennas with small apertures, the reception sensitivity can depend significantly on the polarization of the transmitted radio-frequency signal. However, especially in case the user equipment is a mobile device, the polarization of the antenna of the user equipment may vary with respect to the antenna arrangement of the base station.

In evolving standards, such as in 3GPP RAN1 release 15, it is specified that base stations broadcast beamformed synchronization signals (so-called SS bursts). Different SS bursts for different directions or polarizations are distributed over both the time and frequency domains, so that each beam appears at each sub-band over time. The user equipment may listen to the SS bursts and may use the received signal to calibrate frequency and timing. To find the direction associated with the strongest SS burst, the user equipment may scan or adjust its receive beam. However, depending on the current arrangement of the antennas of the user equipment, the polarization of the SS burst signal may not be optimal for the user equipment.

In 3GPP rel.15, the base station is specified to repeatedly perform beam scanning in dedicated resources. Each transmission beam includes a CSI-RS (pilot), synchronization information, and a beam identifier (beam ID). There is no explicit provision as to how different polarizations are to be treated, and different beam IDs are assigned by the base station to beams that differ only in polarization. On the other hand, this relaxed definition means that the UE cannot know which beams are associated from the perspective of the spatial direction. However, this is information that is useful for the user equipment to determine which beam(s) to select during initial access and when populating the candidate beam list.

In view of the foregoing, there is a need in the art for methods and apparatus that address at least some of the above-described shortcomings of conventional MIMO systems. In particular, there is a need in the art to improve the operation of devices in a wireless communication system to reduce power loss of wireless communication due to polarization misalignment (misalignment).

Disclosure of Invention

According to the invention, this object is achieved by the features of the independent claims. The dependent claims define embodiments of the invention.

According to a first aspect, there is provided a method of operating a communications device to determine a beam report to an access node based on radio signals received in a plurality of beams scanned in a beam of the access node, the method comprising the steps of:

-receiving a first radio signal of a first polarization in a first beam having a first beam direction, an

-receiving second radio signals of a second polarization in a second beam in the direction of the first beam, the second polarization being different from the first polarization,

determining, based on a predetermined rule, that the first radio signal and the second radio signal are transmitted in different polarizations but in a common direction.

According to a second aspect, there is provided a method of operating an access node to transmit radio signals in a plurality of beams of a beam sweep, the method comprising the steps of:

-transmitting a first radio signal with a first polarization in a first beam having a first beam direction, and

-transmitting second radio signals with a second polarization different from the first polarization in a second beam in the direction of the first beam,

wherein the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule.

In one embodiment, a first beam identity assigned to the first beam is included in the first radio signal and a second beam identity assigned to the second beam is included in the second radio signal.

In one embodiment, the first beam and the second beam have a common beam identity and wherein the first radio signals are transmitted using the first set of radio resources and the second radio signals are transmitted using the second set of radio resources, wherein the predetermined rule links the first set of radio resources to the second set of radio resources.

In one embodiment, the first radio signal and the second radio signal are transmitted with a common beam identity in consecutive transmissions in one beam sweep.

In one embodiment, the predetermined rule links the first beam identification to the second beam identification.

In one embodiment, the step of transmitting is performed in a first beam sweep, wherein the predetermined rule comprises performing a second beam sweep in which the second beam identification is assigned to the first beam and the first beam identification is assigned to the second beam.

In one embodiment, the method comprises transmitting (608) a beam report (620) from the access node and receiving in the communication device from a communication device (30) configured to identify a link between the first radio signal and the second radio signal according to the predetermined rule based on the transmitted radio signals, wherein the beam report (620) comprises an indication of radio resource locations allocated to one or more transmission beams.

According to a third aspect, there is provided an access node comprising

-antenna means for transmitting radio signals in a plurality of beams of a beam sweep; and

-logic coupled to the antenna arrangement and configured to:

transmitting a first radio signal with a first beam having a first beam direction with a first polarization, an

Transmitting second radio signals with a second polarization different from the first polarization in a second beam along the first beam direction,

wherein the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule.

In various embodiments, the logic of the communication device is configured to operate the communication device according to any of the embodiments described above.

According to a fourth aspect, there is provided a communication device comprising:

-an antenna for receiving radio signals transmitted in a plurality of beams of a beam sweep; and

-a logic coupled to the antenna arrangement and configured to:

receiving a first radio signal of a first polarization with a first beam having a first beam direction, an

Receiving a second radio signal of a second polarization different from the first polarization in a second beam along the first beam direction,

determining, based on a predetermined rule, that the first radio signal and the second radio signal are transmitted in different polarizations but in a common direction.

In various embodiments, the logic of the access node is configured to operate the communications device according to any of the embodiments described above.

Although specific features are described in the foregoing summary and in the following detailed description that are described in connection with specific embodiments and aspects of the invention, it should be understood that features of the exemplary embodiments and aspects may be combined with each other unless specifically noted otherwise.

Drawings

The invention will now be described in more detail with reference to the accompanying drawings.

Fig. 1 schematically illustrates a wireless communication system according to an embodiment.

Fig. 2 schematically illustrates signal transmission in two different beams of an access node configured to transmit in multiple beams.

Fig. 3-5 schematically illustrate various embodiments of beam configurations in beam scanning by an access node according to various predetermined rules.

Fig. 6 shows a flow diagram including method steps according to various embodiments.

Detailed Description

Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

Additionally, it will be understood that any advantages, features, functions, devices, and/or operational aspects of any embodiment of the invention described and/or contemplated herein may be included in any other embodiment of the invention described and/or contemplated herein, and/or vice versa, where possible. Further, where possible, any term expressed in the singular herein is also intended to include the plural, and/or vice versa, unless explicitly stated otherwise. As used herein, "at least one" shall mean "one or more," and these phrases are intended to be interchangeable. Thus, the terms "a" and/or "an" should be taken to mean "at least one" or "one or more," even though the phrase "one or more" or "at least one" is also used herein. As used herein, unless the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. As used herein, a "set" of items is intended to imply the provision of one or more items.

It will also 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 could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Embodiments are described in the context of radio communications in a wireless communication system that typically operates by means of radio communications or other electromagnetic communications. As such, the wireless communication system includes at least one wireless communication device configured to communicate with a network via an access node. The network may include a core network and a plurality of access nodes connected to the core network. In various embodiments, the wireless system may comprise a cellular wireless network in which a plurality of access nodes may cover a contiguous area and be configured to hand over communications or connections from one access node to another as the wireless communication device moves from one cell to another. In such systems, the access nodes are often referred to as base stations. In 3GPP systems for LTE, the term eNB is used, and for 5G New Radio (NR), the term gNB has been adopted. Alternatively, the access nodes may form discontinuous or uncorrelated coverage and act as Wi-Fi access points or hotspots, e.g., under one or more 3GPP 802.11 specifications.

The term access node will be used herein to generally designate an entity of a wireless network that is used to establish and control an air interface for communicating with wireless communication devices. Further, the communication device will be the term for such a wireless device: the wireless device is configured to communicate with the access node and may communicate directly with the access node or via other communication devices. In the specifications under 3GPP, such a communication device is commonly referred to as a user equipment, UE.

Fig. 1 shows a wireless communication system 10 according to an embodiment. The wireless communication system 10 includes an access node 20 and a plurality of communication devices. In fig. 1, two communication devices 30 and 40 are shown. The access node 20 may support so-called multiple-input multiple-output (MIMO) technology, and thus the access node 20 may have a large number of antennas, e.g. tens or more than a hundred antennas.

The access node 20 comprises an antenna arrangement 22, which antenna arrangement 22 comprises a plurality of antennas, which are indicated by circles in fig. 1. One exemplary antenna of the plurality of antennas is indicated by reference numeral 23. The antennas 23 may be arranged on the carrier in a two-dimensional or three-dimensional antenna array. The access node 20 may further comprise an associated (not shown) transceiver for the antenna 23. The access node 20 also includes access node logic 21. The access node logic 21 is coupled to an antenna arrangement 22 and comprises, for example, a controller, computer or microprocessor. The logic 21 may also include or be connected to a data storage device configured to include a computer-readable storage medium. The data storage device may include memory and may be, for example, one or more of a buffer, flash memory, hard drive, removable media, volatile memory, non-volatile memory, Random Access Memory (RAM), or other suitable device. In a typical arrangement, the data storage device includes non-volatile memory for long-term data storage and volatile memory that functions as system memory for the control unit. The data storage device may exchange data with the processor of the logic section 21 through a data bus. The data storage device is considered to be a non-transitory computer-readable medium. One or more processors of logic 21 may execute instructions stored in a data storage device or a separate memory in order to perform the operations of access node 20, as described herein. The access node 20 may comprise further components, such as a power supply, but for clarity these are not shown in fig. 1. Although only one antenna arrangement 22 is shown in fig. 1, the access node 20 may comprise more than one antenna arrangement, e.g. two, three, four or even more, e.g. tens of antenna arrangements, which may cooperate with each other and which may be arranged close to or spaced apart from each other.

The antenna arrangement 22 may be configured to transmit radio frequency signals, or simply radio signals (referred to herein as beams), in a particular direction. Five of these beams are shown in fig. 1 and are indicated by reference numerals 50-54. The configuration of the beams may be static or dynamic. The transmission of radio frequency signals to a particular direction may be achieved by beamforming techniques known in the MIMO art. In connected mode, a communication device may be able to communicate with access node 20 through one beam or possibly more than one beam. However, the access node 20 may continuously advertise its beams through beam scanning, where the beams are advertised one at a time (e.g., one at a time) in different resources, and then provide the communications device with an opportunity to report to the access node 20 to indicate one or more detected beams. This may be referred to as beam scanning.

The antenna arrangement 22 may be equipped with a dual polarized antenna and may therefore have the capability of transmitting and/or receiving signals having 30 any polarization (e.g., a first polarization and a second polarization), where the first polarization and the second polarization are orthogonal to each other. Furthermore, the antenna arrangement of the particular spatial distribution may be capable of transmitting radio frequency signals also having a third polarization orthogonal to the first polarization and orthogonal to the second polarization.

In the communication system 10, as shown in fig. 1, a plurality of communication devices, such as mobile phones, mobile and stationary computers, tablet computers, smart wearable devices, or smart mobile devices, may be provided. Two exemplary communication devices 30 and 40 are shown in fig. 1. Each of communication devices 30 and 40 may be configured to communicate with access node 20.

Hereinafter, the communication device 30 will be described in more detail. However, communication device 40 may include similar features as communication device 30 and may therefore function similarly. The communication device 30 includes one or more antennas. In the exemplary embodiment shown in fig. 1, the communication device 30 includes two antennas 32 and 33. For example, the antennas 32, 33 may each comprise an antenna panel or antenna array, or the antennas 32, 33 may be formed by an antenna array comprising a plurality of antennas. Further, the communication device 30 includes a logic section 31. The logic 31 may comprise, for example, a controller or microprocessor. The logic 31 may also include or be connected to a data storage device configured to include a computer-readable storage medium. The data storage device may include memory and may be, for example, one or more of a buffer, flash memory, hard drive, removable media, volatile memory, non-volatile memory, Random Access Memory (RAM), or other suitable device. In a typical arrangement, the data storage device includes non-volatile memory for long-term data storage and volatile memory that functions as system memory for the control unit. The data storage device may exchange data with the processor of the logic section 31 through a data bus. The data storage device is considered to be a non-transitory computer-readable medium. One or more processors of logic 31 may execute instructions stored in a data storage device or a separate memory in order to perform the operations of communication device 30, as described herein. Communication device 30 may include further components, such as a graphical user interface (gui) and a battery, but for clarity these components are not shown in fig. 1. The antennas 32, 33 of the communication device 30 may be arranged spaced apart from each other, e.g. the two antennas 32 and 33 may be arranged close to the edge at the top side of the communication device. Alternatively, one or more antennas may be arranged at the top side of the communication device 30, while some other antennas may be arranged at the bottom side of the communication device 30. The two or more antennas 32, 33 form an antenna arrangement whereby the communication device 30 may be configured to receive radio signals in multiple device beams 34, 35 (e.g., multiple receive beams and multiple transmit beams, referred to herein simply as device beams 34, 35). For example, one device beam 34 may be configured for receiving and/or transmitting radio signals with a first phase shift, while a second device beam 35 may be configured for receiving and/or transmitting radio signals with a second phase shift. In various embodiments, this may mean that the first beam 34 is configured to receive and/or transmit radio signals in a first direction, while the second beam is configured to receive and/or transmit radio signals in a second direction. The communication device 30 is thus configured to communicate with spatial directionality. These directions may be set by the antenna structure or by phase adjustment by means of one or more phase shifters connected to the antenna arrangements 32, 33. Since communication device 30 may be mobile and may rotate relative to access node 20, device beam adjustment and/or selection may be repeatedly required.

The above arrangement may be advantageously used in the following scenarios, for example. For example, the access node 20 may be capable of communicating in any polarization. The communication device 30 (e.g., in the form of a user device) may be limited to a single polarization or may be capable of distinguishing between different polarizations and selectively communicating in different polarizations. Further, at least one device may be mobile, such as communication device 30. Furthermore, the uplink and downlink antennas/antenna panels may be different and thus not be applicable to each other, or the number of uplink and downlink links may be different.

Fig. 2 illustrates the access node 20 of fig. 1. In addition to what is set forth with reference to fig. 1, the access node 20 may be configured to distinguish between polarizations in the device beams. This may be provided, for example, by means of a polarization port connected between the phase shifter and the antenna device 22. The access node 20 may be configured such that one beam 54 may be configured to receive and/or transmit radio signals 301 in a first polarization, while the other beam 55 may be configured to receive and/or transmit radio signals 302 in a second polarization different from the first polarization. More specifically, the first polarization and the second polarization may be orthogonal.

The solution provided herein is based on the concept that it may be beneficial for the communication device 30 to obtain knowledge about which access node beams are associated, in the sense that such beams have very the same directionality but different polarizations. The communication device 30 may then determine the potential (potential) of the beam pair (i.e., one access node beam and one device beam) rather than just the determined link quality metric level for the receive beam with any polarization. In many scenarios, the environment may affect the transmission channel between the access node 20 and the communication device 30 in a manner that facilitates a single polarization. If the access node beam is not aligned with that polarization, the communication device 30 will not consider such a beam. It is therefore proposed herein that the access node 20 directs at least two different beams 54, 55 having opposite polarizations but the same settings to transmit in such a common direction and provides a means for the communication device 30 to know this. Thus, the communication device 30 can determine the potential performance that an access node beam with the best polarization will give.

If the access nodes 20 explicitly share the list of polarization-related beams, this will increase overhead and the overall throughput will decrease. This is also not a method suitable for use in initial access.

Therefore, a method and an access node 20 are proposed, wherein an implicit sharing of information of a polarization dependent beam is provided. In general, one aspect of the proposed solution relates to a method for operating an access node 20 to transmit radio signals in a plurality of beams 50-55 of a beam sweep.

In various embodiments, the beams 50-55 may be allocated to or associated with a particular set of radio resources, and the antenna arrangement 22 may be configured by means of the logic 21 to transmit the set of radio resources in a particular direction and with a particular polarization. The radio signals 301, 302 transmitted in a beam may be characterized by the information or data carried in the signal by means of the radio resources of the beam.

The method involves transmitting a first radio signal 301 from the access node 20 in a first beam 54 with a first polarization. The first beam 54 is configured to have a first beam direction by means of the antenna arrangement 22 of the access node 20. The method also includes transmitting a second radio signal 302 using a second polarization different from the first polarization. The second radio signals 302 are transmitted in a second beam 55, wherein the second beam 55 is configured to have the same first beam direction by means of the antenna arrangement 22 of the access node 20. In other words, the first radio signal 301 and the second radio signal 302 are configured with a common setting to have a common directivity (such as a common phase or phase shift), but different polarizations. In some embodiments, the first polarization and the second polarization are orthogonal. Further, the transmission of the first radio signal 301 is linked to the transmission of the second radio signal 302 according to a predetermined rule.

Various embodiments will now be described in connection with the method with reference to the accompanying drawings.

Fig. 3 schematically illustrates transmit and receive scheduling in a beam sweep associated with an access node 20 and will be used to describe various embodiments. It should be noted that the scheduling of fig. 3 is exemplary, and not exclusive.

When performing the first beam sweep 310, Downlink (DL) transmissions may be performed by the access node 20. In particular, radio signals may be transmitted in radio resources allocated to different beams having different beam indices BI. In the figure, the transmission in the individual beams is performed separately along an axis x, which may be time and/or frequency. At some point, typically after the completed DL scan 310, the communication device 30, 40 may be provided with an Uplink (UL) opportunity to send a beam report. Such a beam report may include at least an indication of a BI of DL transmissions received in one or more of the previous beam sweep periods 310 detected by the respective communication device. The beam report may form the basis for the access node to select the beam pair with which to communicate signals and data with the communication device 30. In period 330, a second beam sweep is performed in which radio signals may be transmitted again in radio resources allocated to a different beam having a different BI.

Among the beams used for transmitting radio signals, at least two beams are associated in the sense that they are transmitted in the same or related directions but with different polarizations. As an example, a first beam identity assigned to a first beam is included in a first radio signal transmitted in the beam, and a second beam identity assigned to a second beam is included in a second radio signal transmitted in the second beam.

In various embodiments, the predetermined rules may specify links between such direction-dependent beams having opposite or at least different polarizations. The link may be specified by the specification, for example, as a mandatory configuration of beams. In this way, the communication device 30, 40 configured to operate in a MIMO communication system also knows the desired beam configuration with respect to direction-dependent beams having different polarizations. In alternative embodiments, the specification may be mandatory in the specification, whereby only a communication device using such mandatory specification may be configured to obtain the following information: which beams are direction dependent with different polarizations. In yet another embodiment, the code transmitted in the transmitted signal 301, 302 or other broadcast signal may inform a communication device receiving such a signal: the access node 20 employs predetermined rules specified for the links of the beam configuration.

In one embodiment, the predetermined rules may specify that the beams are associated with a beam id (bi) pair-wise polarization. As an example, beams with BI of [0 and 1] are associated, [2 and 3] and [4 and 5], and so on. This method may be any other ID pair. Another example may be that a BI exceeding a certain number is associated with a beam having a BI minus the number. Thus, [0 and 64], [1 and 65], [ k and (k +64) ], etc. For each such pair, one beam 55 having a first direction and a first polarization is uniquely linked to a second beam 56 having the same or related direction but a different polarization. Thus, the predetermined rule links the first beam identification with the second beam identification. The receiving communication device 30 may obtain the link based on the BI detected in the received radio signal 301, 302.

This embodiment provides efficient mapping of direction-associated beams without the need for additional communication of the configuration. Furthermore, it is easy to implement since it is linked to the BI (which is however preferably comprised in the transmission of the radio signals 301, 302 of the beam). For the same reason, the communication device 30, 40 also easily obtains the link by reading or decoding the received radio signal 301, 302.

Fig. 4 shows another embodiment similar to the embodiment of fig. 3. However, in the embodiment of fig. 4, the access node 20 is configured to use the same BI for beams having common directivity but different polarizations. Preferably, such beams are allocated to different sets of radio resources in time and/or frequency. In particular, the first beam 54 and the second beam 55 have a common beam identification, e.g., BI 0. The first radio signal 301 is transmitted using a first set of radio resources and the second radio signal is transmitted using a second set of radio resources, both in a beam labeled BI 0. If two radio signals 301, 302 are received in the communication device 30 in one beam sweep, the communication device may be configured to infer that the two radio signals 301, 302 represent beams having a common directivity that differs in polarization by means of a predetermined rule linking the first set of radio resources to the second set of radio resources.

In addition to the benefits outlined with respect to the previous embodiments, the embodiment described with reference to fig. 4 has the additional technical effect that the predetermined rules do not restrict the use of beam indices. If a total of, for example, 126 Bi are available, all of the Bi can be used in this embodiment, rather than only half.

As shown in fig. 4, such associated transmissions with a common beam index BI may be provided in consecutive pairs (i.e., 0, 1, 2, etc.). In alternative embodiments, transmissions with a common beam index BI in a common direction but with different polarizations may be provided in other types of pairs configured in the scan. As an example, in the scanning, the radio signal may be first transmitted in a first polarization in all provided BIs, and then may be transmitted in a second polarization in all provided BIs.

According to this embodiment, the communication device 30 will be able to detect the same ID in different resources and know directly that they are different but (e.g. by orthogonality) related to polarization. As noted, this approach also has the additional advantage that it does not increase the beam count.

Fig. 5 illustrates another embodiment, which generally overlaps the embodiments of fig. 3 and 4. However, different rules are provided for linking the associated beams (i.e. a first beam 55 transmitting radio signals of a first polarization and a second beam 56 transmitting radio signals of a second polarization, and wherein the first beam 55 and the second beam 56 have a common directivity). This embodiment is based on the following concept: the beams of access node 20 are typically scanned in a pattern that repeats over time. The BI is then typically assigned to a predetermined radio resource location. In the embodiment of fig. 5, the access node 20 is configured to exchange resource locations between the associated beam and the BI. As shown in the example diagram of fig. 5, the BI of at least the first two radio signals have exchanged locations. In other words, in the first scan 310, the receiving communication device 30 may detect BI #0 in the first resource location and BI #1 in the second resource location. In a subsequent scan 330, the same receiving communications device 30 may detect BI #0 at the second resource location and BI #1 at the first resource location. Since both the resource location and the BI are obtained by the communication device, the exchange will be easily detected. This identifies the two beams as being associated with a common directivity but opposite polarization according to a predetermined rule. The predetermined rule may thus comprise performing a second beam sweep, wherein the second beam identification is assigned to the first beam and the first beam identification is assigned to the second beam.

In various embodiments, the communication device 30 may be configured to transmit the beam report in the UL, e.g., at 320. Even though the access node 20 may be configured to transmit radio signals in multiple beams, the communication device will typically detect only a subset of those beams. As mentioned, the communication device may be further configured to receive radio signals in a plurality of device beams 34, 35. The beam report may comprise an identification of beam pairs, each pair comprising a combination of one receive beam 50-55 (identified by its BI) from the access node and possibly an identification of the device beams 34, 35. The access node 20 may be configured to receive such beam reports from the communication device 30 based on the transmitted radio signals. In particular, based on a combination of implicit notifications of associated DL beams from an access node (as described herein in accordance with many different rules for linking such DL beams), a communication device may be configured to identify a link between a first radio signal and a radio signal having a common directionality but different polarizations. This information may be used by the communication device 30 in selecting a beam pair to report. For example, the communication device 30 may determine the potential performance that one or more access node beams with the best polarization will give and thus include or only include the BI of the majority of beams that provide the best potential in terms of radio link quality or strength.

In one embodiment, a set of radio resources is allocated to each beam of the beam sweep. However, the communication device 30 is configured to report resource locations, rather than reporting BI. In such embodiments, where the beam report includes radio resource locations of one or more transmit beams and preferably does not include a BI, the method would enable further reduction of overhead. In such embodiments, the different resource locations are preferably polarization dependent in the following manner: the predetermined rules uniquely link a pair of resource locations to beams having different polarizations but having common directionality.

Fig. 6 illustrates steps and signals transmitted and received in an embodiment of the present invention. On the left side, the steps performed by the access node 20 of the wireless communication network are shown. On the right side, steps performed by the communication device 30 are shown. The steps shown and described are consistent with the description provided throughout this specification with reference to fig. 1-5.

In various embodiments, a method is provided for operating an access node 20 to transmit radio signals in a plurality of beams 50-55 of one or more beam sweeps 310, 330. Further, a method of operating the communication device 30 to determine a beam report 620 to the access node 20 based on radio signals received in the plurality of beams 50-55 of the access node beam sweep 310 is provided.

In step 605 of the first beam sweep 310, the access node 20 transmits a first radio signal (301) with a first polarization in a first beam (54) having a first beam direction and a second radio signal 302 with a second polarization. The polarizations between the first radio signal and the second radio signal are different, preferably orthogonal. However, they are transmitted in beams 54, 55 having a common direction. Further, the transmission of the first radio signal is linked to the transmission of the second radio signal according to a predetermined rule.

In step 610, the communication device 30 receives at least some radio signals transmitted by the access node 20, including the first signal 301 and the second signal 302. The received radio signals may comprise a beam index BI related to the beam 54, 55 carrying the first radio signal 301 and the second radio signal 302.

In step 607, which is performed for some embodiments described above with reference to fig. 5, a second beam sweep 330 is performed in which the polarization between the first beam 54 and the second beam 55 is exchanged.

In step 612 (which is performed if step 607 is performed), the communications device receives radio signals in beams 54, 55, whereby beam indices BI0 and BI1 are received in alternating resource locations in steps 610 and 612.

In step 614, the communication device 30 may determine that the first radio signal 301 and the second radio signal 302 are transmitted from the access node 20 in different polarizations but with a common directivity based on a predetermined rule linking the transmissions of these radio signals. In other words, the communication device may be configured to determine, based on a predetermined rule, that the first radio signal and the second radio signal are transmitted in different polarizations but in a common direction.

In step 616, the communication device may be configured to determine one or more receive beams 54, 55 for uplink reporting or a pair of beams configured by a set of antennas 32, 33 of the communication device 30, each comprising one receive beam and one device beam. This step may include selecting a beam or beam pair that provides a satisfactory link quality (e.g., as determined by signal strength measurements of the received radio signals 301, 302).

In step 618, the communication device 30 may transmit a beam report 620 based on the received radio signals 301, 302 and indicate the selected beam (e.g., as determined in step 616). This may occur during a period 320 between a first beam sweep 310 and a second beam sweep 330 of an access node transmission in multiple beams. Since the communication device 30 is configured to identify the link between the first radio signal and the second radio signal according to the predetermined rule, the beam report may be configured to include an indication (such as BI) of reception beams having a common directionality and different polarizations, even if one or both of the associated radio signals 301, 302 are not received with the best or satisfactory signal strength. In some embodiments, the beam report 620 may include radio resource locations of one or more transmit beams with the respective beams 54, 55 of the beam sweep 310 being allocated a set of radio resources. In particular, the beam report may include an indication of the location of the resource instead of the beam index BI.

In step 608, the access node 20 receives a beam report 620 from the communication device 30 based on the transmitted radio signals 301, 302, the communication device 30 being configured to identify a link between the first radio signal and the second radio signal according to said predetermined rule.

Step 609 indicates that the beam sweep is a repeated or recurring event and that the period of beam sweep transmission 310, 330 may begin again after period 320, which provides the communication device 30 with an opportunity to transmit in the UL (e.g., for transmitting beam reports).