HK1222049B - Method, apparatus and system for electrical downtilt adjustment in a multiple input multiple output system - Google Patents

Description

Method, device, and system for electronic downtilt adjustment in a multiple-input multiple-output system

Cross-reference to related applications

This application claims priority to U.S. Provisional Patent Application No. 61/863,902, filed on August 8, 2013, the entire disclosure of which is incorporated herein by reference in its entirety.

Technical Field

Embodiments of the present invention generally relate to the field of communications, and more particularly, to how to adjust electronic downtilt in a Multiple Input Multiple Output (MIMO) system.

Background Art

Multiple-Input Multiple-Output (MIMO) technology uses multiple antennas at one or more transmitters and one or more receivers. MIMO systems can be used to increase network data throughput and link reliability. Three-dimensional (3D) or full-dimensional (FD) MIMO systems can be used in MIMO networks to improve cellular performance by deploying antenna elements in both the horizontal and vertical dimensions (e.g., a two-dimensional (2D) antenna array).

In a conventional MIMO system, an evolved Node B (eNB) may have to use the same electronic downtilt angle for all data transmissions, which may also introduce interference to neighboring cells.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings wherein like references refer to similar elements.

FIG1 schematically illustrates a communication network deploying a two-dimensional (2D) antenna array in a three-dimensional (3D) or full-dimensional (FD) multiple-input multiple-output (MIMO) system according to various embodiments.

FIG2 schematically illustrates a distance and an elevation angle of departure (EoD) from a user equipment (UE) to an evolved Node B (eNB) in a communication network according to various embodiments.

FIG3 a schematically illustrates electronic downtilt and cell edge geometry in a communication network according to various embodiments.

FIG3 b schematically illustrates electronic downtilt and antenna array gain at 90 degrees EoD in a communication network according to various embodiments.

FIG4 schematically illustrates electrical downtilt and cell edge coupling loss in a communication network according to various embodiments.

FIG5 schematically illustrates a system for adjusting electronic downtilt in a communication network, according to various embodiments.

FIG6 schematically illustrates a method for adjusting electronic downtilt by an eNB in a communication network according to various embodiments.

FIG7 schematically illustrates an exemplary system according to various embodiments.

DETAILED DESCRIPTION

Illustrative embodiments of the present disclosure include, but are not limited to, methods, apparatus, and systems for electrical downtilt adjustment in three-dimensional (3D) or full-dimensional (FD) multiple-input multiple-output (MIMO) systems.

The various aspects of the illustrative embodiments will be described using the terms commonly used by those skilled in the art to convey the essence of their work to other persons skilled in the art. However, it will be apparent to those skilled in the art that a part of the described aspects can be used to put into practice some alternative embodiments. For the purpose of explanation, specific numbers, materials, and configurations have been set forth to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to those skilled in the art that alternative embodiments can be put into practice without these specific details. In other cases, known features may be omitted or simplified so that the illustrative embodiments are not clear.

Furthermore, the operations are described as multiple discrete operations in sequence in a manner that is most helpful in understanding the claimed subject matter; however, the order of description should not be construed as implying that these operations are necessarily order dependent. In particular, these operations may not be performed in the order presented.

The phrase "in one embodiment" is used repeatedly. The phrase generally does not refer to the same embodiment; however, it may refer to the same embodiment. The terms "including," "having," and "comprising" are synonymous unless the context indicates otherwise. The phrase "A/B" means "A or B." The phrase "A and/or B" means "(A), (B), or (A and B)." The phrase "at least one of A, B, and C" means "(A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C)." The phrase "(A)B" means (B) or (AB), i.e., A is optional.

Although specific embodiments have been shown and described herein, it will be appreciated by those skilled in the art that various alternative and/or equivalent implementations may be used as substitutes for the specific embodiments shown and described without departing from the scope of the embodiments of the present disclosure. This application is intended to include any adaptation or variation of the embodiments discussed herein. Therefore, it is expressly intended that the embodiments described herein be limited only by the claims and their equivalents.

As used herein, the terms "circuit," "module," or "logic" portion refer to or are part of a hardware component such as an application specific integrated circuit (ASIC), an electronic circuit, a logic circuit, a (shared, dedicated, or group) processor, and/or (shared, dedicated, or group) memory that is configured to provide the described functionality.

1 schematically illustrates a communication network 100 deploying a two-dimensional (2D) antenna array 102 in a three-dimensional (3D) or full-dimensional (FD) multiple-input multiple-output (MIMO) system according to various embodiments.

In various embodiments, the 2D antenna array 102 may include multiple antenna elements 104 in one or more antenna columns 106 in a vertical direction. The 2D antenna array 102 may be installed at a transmission point (e.g., an evolved Node B (eNB) 114) having a coverage area 108 that includes a user equipment (UE) 116. In other embodiments, the 2D antenna array 102 may include one antenna column 106 in a vertical direction.

The vertical directivity provided by antenna array 102 can be depicted by two different beam direction geometries: a first beam direction geometry 118 and a second beam direction geometry 120. The beam direction geometries can depict areas of higher signal relative to a transmission point (e.g., eNB 114), although corresponding signals may also exist in other areas.

In a 3D MIMO system, the signal radiation pattern (or beamforming) of the antenna array 102 at the eNB 114 can be tilted along the vertical axis. The angle of vertical tilt, or tilt angle, can be measured relative to a reference horizontal plane. The tilt angle can be referred to as the electrical downtilt angle of the antenna array. The name electrical downtilt angle can be given relative to mechanical downtilt angle (which can refer to the angle between the antenna array and the vertical axis if the antenna array is physically tilted relative to the vertical direction).

FIG2 schematically illustrates the distance from a user equipment to an evolved Node B (eNB) in a communication network 100 and the departure elevation angle (EoD), according to various embodiments. The EoD may refer to the angle between a line of sight (LoS) and a reference direction. As shown in FIG2 , as the distance between a UE 116 and an eNB 114 increases (e.g., when the UE 116 reaches the cell edge of the eNB 114), the EoD may converge to 90 degrees.

FIG3 a schematically illustrates electrical downtilt angles and cell edge geometry in the communication network 100 according to various embodiments. For example, the cell edge geometry may be represented by a signal-to-noise ratio (SNR) at the cell edge of the eNB 114. As shown in FIG3 a , SNR peaks may occur at electrical downtilt angles such as 102 degrees, 114 degrees, 126 degrees, 78 degrees, 138 degrees, 66 degrees, 105 degrees, and 54 degrees.

3b schematically illustrates electrical downtilt angles and antenna array gain at 90 degrees EoD in communication network 100, according to various embodiments. For example, the combined antenna array gain at 90 degrees EoD (i.e., the combined antenna array gain when UE 116 reaches the cell edge of eNB 114) may generate nulling directions at electrical downtilt angles such as 102 degrees, 114 degrees, 126 degrees, 78 degrees, 138 degrees, 66 degrees, 105 degrees, and/or 54 degrees.

In some embodiments, the electrical downtilt angle may be adjusted to maximize signal strength (eg, SNR) and minimize interference leakage to neighboring cells.

4 schematically illustrates electrical downtilt angles and cell edge coupling loss in the communication network 100 according to various embodiments. For example, several cell edge coupling loss peaks may appear at electrical downtilt angles such as 109 degrees, 122 degrees, 118 degrees, 86 degrees, and/or other angles.

5 schematically illustrates a system for adjusting electrical downtilt in the communication network 100 according to various embodiments. In some embodiments, the eNB 114 may include a transceiver 502, a channel state information reference signal (CSIRS) configuration module 504, an electrical downtilt module 506, a codebook module 508, an antenna control module 510, and other components.

In various embodiments, the CSIRS configuration module 504 may generate CSIRS configuration information for use in CSI reporting to the UE 116. In some embodiments, the CSIRS configuration information may include the number of CSIRS antenna ports, a CSIRS pattern index corresponding to a particular CSIRS pattern, a duty cycle or period for CSIRS transmission, and/or other information. The transceiver 502 may transmit the CSIRS configuration information to the UE 116 and receive information related to a preferred antenna port from the UE 116. The information may include the preferred antenna port selected by the UE 116 based on the CSIRS configuration information and/or a precoding matrix indicator (PMI) estimated based on the CSIRS configuration (which may help the eNB 114 determine the antenna port to allocate to the UE 116).

In various embodiments, the electrical downtilt module 506 may determine an electrical downtilt angle for the determined antenna port based on information received from the UE 116 (e.g., preferred antenna port, PMI, and/or other information). In various embodiments, the electrical downtilt module 506 may determine an angle that may correspond to a cell-edge UE geometry peak (as shown in FIG. 3 a ) or to a combined antenna array gain nulling direction at 90 degrees EoD (as shown in FIG. 3 b ). As described above, examples of electrical downtilt angles may include at least one of the group consisting of 102 degrees, 114 degrees, 126 degrees, 78 degrees, 138 degrees, 66 degrees, 105 degrees, 54 degrees, and/or other angles.

By determining the electrical downtilt angle corresponding to the peak of the cell edge geometry, corresponding to the direction where the combined antenna array gain is nulled, interference to neighboring cells may be minimized when UE 116 reaches the cell edge of eNB 114.

In various embodiments, the codebook module 508 may generate a codebook for the antenna elements of the antenna array 102, assuming that the antenna array 102 has antenna elements 104 in one or more antenna columns 106 in a vertical direction. The codebook may include multiple codewords. The codeword may include multiple vector elements, each vector element corresponding to one of the antenna elements 104. In various embodiments, the codeword may be represented by the following formula:

Where M represents the number of antenna elements 104, N represents the number of antenna ports (not shown in FIG. 5 ), w _i represents the weight of the antenna array 102 at the i-th antenna port, and α+θ _i represents the electrical downtilt angle, where α represents the angle of the mechanical downtilt angle and θ _i represents the angular offset relative to the mechanical downtilt angle. However, in other embodiments, the codebook may be pre-stored by the developer in a storage device (not shown in FIG. 5 ) of the eNB 116, and therefore, the codebook module 508 may not need to generate the codebook.

In various embodiments, the codebook module 508 may select a codeword corresponding to the antenna port selected by the UE 116 (e.g., the i-th antenna port), and further calculate the antenna array weights w _i by inputting the electrical downtilt angle determined by the electrical downtilt module 506 into the above codebook. In an embodiment, it may be desirable to have the electrical downtilt angle correspond to one of the cell edge UE geometry peaks (as shown in FIG. 3 a ), or to one of the combined antenna array gain nulling directions at 90 degrees EoD (as shown in FIG. 3 b ). Given this, if and M=10, N=8, then in another embodiment, it may be desirable to have the electrical downtilt angle correspond to one of the cell edge coupling loss peaks (as shown in FIG. 4 ). Given this, if and M=10, N=8, then

In various embodiments, N electrical downtilt angles (e.g., α + θ _i ) for N antenna ports may be determined, and these N electrical downtilt angles may correspond to any cell edge geometry peaks, any combined antenna array gain nulling directions at 90 degrees EoD, and/or any cell edge coupling loss peaks, etc. This may reduce interference to neighboring cells when the UE 116 reaches the cell edge of the eNB 114, or increase the geometry of the cell edge UE 116.

In various embodiments, the antenna control module 510 may control the antenna array 102 by mapping the antenna elements 104 of the antenna array 102 to the i-th antenna port having the antenna array weights calculated by the codebook module 508. In this manner, the antenna array 102 may receive or transmit data from or to the UE 116 at the i-th antenna port.

FIG6 schematically illustrates a method for adjusting electrical downtilt by an eNB in a communication network according to various embodiments. In an embodiment, at block 602, a CSIRS configuration module 504 or other device of the eNB 114 may generate CSIRS configuration information for CSI reporting to the UE 116. The CSIRS configuration information may include the number of CSIRS antenna ports, a CSIRS pattern index corresponding to a particular CSIRS pattern, a duty cycle or period of CSIRS transmission, and/or other information. At block 604, the transceiver 502 of the eNB 116 may transmit the CSIRS configuration information to the UE 116, and at block 606, receive information related to a preferred antenna port from the UE 116. The information may include the preferred antenna port selected by the UE 116 based on the CSIRS configuration information, and/or a precoding matrix indicator (PMI) estimated based on the CSIRS configuration (which may help the eNB 114 determine the antenna port to be allocated to the UE 116).

In an embodiment, at block 608, the electrical downtilt module 506 of the eNB 114 or another device thereof may determine an electrical downtilt angle for an antenna port based on information received from the UE 116 (e.g., preferred antenna port, PMI, and/or other information). The electrical downtilt module 506 may determine an angle that may correspond to a cell-edge UE geometry peak (as shown in FIG. 3 a ), or to a combined antenna array gain nulling direction at 90 degrees EoD (as shown in FIG. 3 b ). Alternatively, the electrical downtilt module 506 may determine an angle that may correspond to a cell-edge coupling loss peak (as shown in FIG. 4 ).

By determining an electrical downtilt angle corresponding to a cell edge geometry peak, a combined antenna array gain nulling direction at 90 degrees EoD, and/or a cell edge coupling loss peak, interference to neighboring cells may be reduced when UE 116 reaches the cell edge of eNB 114.

At block 610, codebook module 508 of eNB 114 or another device thereof may generate a codebook for the antenna elements of antenna array 102, assuming that antenna array 102 has antenna elements 104 arranged in one or more antenna columns 106 in a vertical direction. The codebook may include a plurality of codewords, each corresponding to one of the antenna ports (not shown in FIG. 5 ). The codeword may include a plurality of vector elements, each corresponding to one of antenna elements 104. However, in other embodiments, the codebook may be pre-stored by a developer in a storage device (not shown in FIG. 5 ) of eNB 116, and thus, codebook module 508 may not need to generate the codebook.

At block 612 , the codebook module 508 of the eNB 114 or other devices may select a codeword corresponding to the antenna port selected by the UE 116 (eg, the i-th antenna port), and further calculate antenna array weights w _i by inputting the electrical downtilt angle determined at block 608 into the codebook.

At block 614, the antenna control module 510 or other device at the eNB 114 may control the antenna array 102 by mapping the antenna elements 104 of the antenna array 102 to the i-th antenna port having the antenna array weights calculated by the codebook module 508. In this manner, at block 616, the antenna array 102 may receive or transmit data from or to the UE 116 at the i-th antenna port.

7 schematically illustrates an example system 700 according to various embodiments. In an embodiment, the system 700 may include one or more processors 704, system control logic 708 coupled to at least one of the processors 704, a system memory 712 coupled to the system control logic 708, a non-volatile memory (NVM)/storage device 716 coupled to the system control logic 708, and a network interface 720 coupled to the system control logic 708.

Processor(s) 704 may include one or more single-core or multi-core processors. Processor(s) 704 may include any combination of general-purpose processors and specialized processors (e.g., graphics processors, application processors, baseband processors, etc.). In one embodiment where system 700 implements eNB 114, processor(s) 704 may be configured to perform one or more of the embodiments shown in Figures 5-6 according to various embodiments.

System control logic 708 for one embodiment may include any suitable interface controller to provide any suitable interface to at least one of the processor(s) 704 and/or any suitable device or component in communication with system control logic 708 .

System control logic 708 for one embodiment may include one or more memory controllers to provide an interface to system memory 712. System memory 712 may be used to load and store data and/or instructions, for example, system 700. System memory 712 for one embodiment may include any suitable volatile memory, such as suitable dynamic random access memory (DRAM).

The NVM/storage 716 may include one or more tangible, non-transitory computer-readable media for storing data and/or instructions. The NVM/storage 716 may include, for example, any suitable non-volatile memory such as flash memory, and/or may include, for example, any suitable non-volatile storage device(s) such as one or more hard disk drives (HDD(s),) one or more compact disk (CD) drives, and/or one or more digital versatile disk (DVD) drives.

NVM/storage 716 may include storage resources that are physically part of the device on which system 700 is installed, but not necessarily part of the device. For example, NVM/storage 716 may be accessible via network interface 720 over a network.

The system memory 712 and the NVM/storage device 716 may respectively include, among other things, temporary and persistent copies of instructions 724. The instructions 724 may include instructions that, when executed by the processor(s) 704, cause the system 700 to perform the method described with reference to FIG6 . In various embodiments, the instructions 724, or a combination of hardware, firmware, and/or software thereof, may additionally or alternatively reside in the system control logic 708, the network interface 720, and/or the processor(s) 704.

The network interface 720 may include the CSIRS configuration module 504, the electronic downtilt module 506, the codebook module 508, the antenna control module 510, and/or other devices as shown in FIG5 to provide a radio interface for the system 700 for communication over one or more networks and/or communication with any other appropriate device. In various embodiments, the network interface 720 may be integrated with other components of the system 700. For example, the network interface may include a processor of the processor(s) 704, a memory of the system memory 712, an NVM/storage device of the NVM/storage device 716, and/or a firmware device (not shown) having instructions that, when executed by at least one of the processor(s) 704, causes the system 700 to perform the method described with reference to FIG6.

The network interface 720 may also include any suitable hardware and/or firmware, such as multiple antennas (e.g., antenna array 102) to provide a multiple-input multiple-output radio interface. In one embodiment, the network interface 720 may be, for example, a wired network adapter, a wireless network adapter, a telephone modem, and/or a wireless modem.

For one embodiment, at least one of the processor(s) 704 may be packaged together with the logic of one or more controllers of the system control logic 708. For one embodiment, at least one of the processor(s) 704 may be packaged together with the logic of one or more controllers of the system control logic 708 to form a system-in-package (SiP). For one embodiment, at least one of the processor(s) 704 may be integrated on the same die with the logic of one or more controllers of the system control logic 708. For one embodiment, at least one of the processor(s) 704 may be integrated on the same die with the logic of one or more controllers of the system control logic 708 to form a system-on-chip (SoC).

System 700 may also include input/output (I/O) devices 732. I/O devices 732 may include a user interface designed to enable user interaction with system 700, a peripheral component interface designed to enable peripheral components to interact with system 700, and/or sensors designed to determine environmental conditions and/or information related to system 700.

In various embodiments, the user interface can include, but is not limited to, a display (e.g., an LCD display, a touch screen display, etc.), a speaker, a microphone, one or more cameras (e.g., a still camera and/or a video camera), a flash (e.g., an LED flash), and a keyboard.

In various embodiments, the peripheral component interface may include, but is not limited to, a non-volatile memory port, a universal serial bus (USB) port, a headphone jack, and a power port.

In various embodiments, sensors may include, but are not limited to, gyroscope sensors, accelerometers, proximity sensors, ambient light sensors, and positioning units. The positioning unit may also be part of or interact with the network interface 720 to communicate with components of a positioning network such as global positioning system (GPS) satellites.

In various embodiments, system 700 may be an eNB, such as eNB 116. In various embodiments, system 700 may have more or fewer components and/or a different architecture.

The present disclosure may include various exemplary embodiments disclosed below.

In example embodiment 1, an apparatus may include: an electronic downtilt module for determining an electronic downtilt angle for an antenna port selected from a number of antenna ports based on information from a user equipment (UE); and a codebook module for selecting a codeword corresponding to the antenna port from a codebook and calculating an antenna array weight of an eNB by inputting the electronic downtilt angle into the codeword, wherein the codebook has a first number of codewords, each codeword has a second number of elements to represent a weight of the antenna array, and wherein each codeword corresponds to each antenna port, and each element corresponds to each antenna of the antenna array.

In Example Embodiment 2, the electronic downtilt angle according to Example Embodiment 1 may be determined to reduce the antenna array gain of the antenna array at a departure elevation angle (EoD) of 90 degrees.

In exemplary embodiment 3, the electronic downtilt according to any of exemplary embodiments 1-2 may be determined to increase the cell edge coupling loss for the UE.

In Example Embodiment 4, the codeword according to any one of Example Embodiments 1-3 may be expressed by the following formula:

Where M represents the number of antenna elements, N represents the number of antenna ports, w _i represents the weight of the antenna array at the i-th antenna port, and α + θ _i represents the electronic downtilt angle.

In example embodiment 5, the information according to any one of example embodiments 1-4 may include: a precoding matrix indicator (PMI) or an antenna port associated with an antenna port selected by the UE from among some antenna ports based on channel state information reference signal (CSIRS) configuration information received from the eNB.

In Example Embodiment 6, the antenna control module according to any one of Example Embodiments 1-5 may control the antenna array based on the weights calculated by the codebook module.

In Example Embodiment 7, the apparatus according to any one of Example Embodiments 1-6 may further include a transceiver configured to send CSIRS configuration information to a UE and receive information related to antenna ports from the UE.

Although certain embodiments have been illustrated and described herein for purposes of illustration, it is contemplated that a wide variety of alternative and/or equivalent embodiments or implementations that achieve the same purpose may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to include any adaptation or variation of the embodiments discussed herein. Therefore, the embodiments described herein are expressly intended to be limited only by the claims and their equivalents.

Claims (12)

1. An apparatus for an evolved Node B, i.e., an eNB, comprising: An electrical downtilt module is configured to determine an electrical downtilt angle for an antenna port selected from a set of antenna ports based on information received from a user equipment (UE), wherein the information includes: an antenna port selected by the UE from the set of antenna ports based on channel state information reference signal (CSIRS) configuration information received from the eNB, or a precoding matrix indicator (PMI) associated with the selection of that antenna port; and A codebook module is configured to select codewords corresponding to the antenna ports from a codebook and calculate the antenna array weights of the eNB by inputting the electrical downtilt angle into the codewords. The codebook has a first number of codewords, each codeword has a second number of elements representing the weights of the antenna array, and each codeword corresponds to each antenna port, and each element corresponds to each antenna of the antenna array. The electrical downtilt angle is determined to reduce the antenna array gain of the antenna array at the 90-degree takeoff elevation angle (EoD), or it is determined to increase cell edge coupling loss for the UE. 2. The apparatus of claim 1, wherein the codeword is represented by the following formula: Where M represents the number of antenna elements, N represents the number of antenna ports, w_{_i} represents the weight of the antenna array at the i-th antenna port, and α+θ _{_i} represents the electrical downtilt angle. 3. The apparatus of claim 1, further comprising: An antenna control module controls the antenna array based on weights calculated by the codebook module. 4. The apparatus of claim 1, further comprising: A transceiver is used to send the CSIRS configuration information to the UE and receive information related to the antenna port from the UE. 5. A method for an evolved Node B (eNB), comprising: Based on information received from the User Equipment (UE), an electrical downtilt angle is determined for an antenna port selected from a set of antenna ports, wherein the information includes: an antenna port selected by the UE from the set of antenna ports based on Channel State Information Reference Signal (CSIRS) configuration information received from the eNB, or a precoding matrix indicator (PMI) associated with the selection of that antenna port; and The codeword corresponding to the antenna port is selected from the codebook, and the antenna array weight of the eNB is calculated by inputting the electrical downtilt angle into the codeword, wherein the codebook has a first number of codewords, each codeword has a second number of elements to represent the weight of the antenna array, and wherein each codeword corresponds to each antenna port, and each element corresponds to each antenna of the antenna array. The electrical downtilt angle is determined to reduce the antenna array gain of the antenna array at the 90-degree takeoff elevation angle (EoD), or it is determined to increase cell edge coupling loss for the UE. 6. The method of claim 5, wherein the codeword is represented by the following formula: Where M represents the number of antenna elements, N represents the number of antenna ports, w_{_i} represents the weight of the antenna array at the i-th antenna port, and α+θ _{_i} represents the electrical downtilt angle. 7. The method of claim 5, further comprising: The antenna array is controlled based on the calculated weights. 8. The method of claim 5, further comprising: The CSIRS configuration information is sent to the UE, and information related to the antenna port is received from the UE. 9. A computer-readable storage medium storing computer-executable instructions, which, when executed, cause a processor of an evolved Node B (eNB) to perform operations including: Based on information received from the User Equipment (UE), an electrical downtilt angle is determined for an antenna port selected from a set of antenna ports, wherein the information includes: an antenna port selected by the UE from the set of antenna ports based on Channel State Information Reference Signal (CSIRS) configuration information received from the eNB, or a precoding matrix indicator (PMI) associated with the selection of that antenna port; and The codeword corresponding to the antenna port is selected from the codebook, and the antenna array weight of the eNB is calculated by inputting the electrical downtilt angle into the codeword, wherein the codebook has a first number of codewords, each codeword has a second number of elements to represent the weight of the antenna array, and wherein each codeword corresponds to each antenna port, and each element corresponds to each antenna of the antenna array. The electrical downtilt angle is determined to reduce the antenna array gain of the antenna array at the 90-degree takeoff elevation angle (EoD), or it is determined to increase cell edge coupling loss for the UE. 10. The computer-readable storage medium of claim 9, wherein the codeword is represented by the following formula: Where M represents the number of antenna elements, N represents the number of antenna ports, w_{_i} represents the weight of the antenna array at the i-th antenna port, and α+θ _{_i} represents the electrical downtilt angle. 11. The computer-readable storage medium of claim 9, wherein the operation further comprises: The antenna array is controlled based on the calculated weights. 12. The computer-readable storage medium of claim 9, wherein the operation further comprises: The CSIRS configuration information is sent to the UE, and information related to the antenna port is received from the UE.