KR20220061029A - Method and apparatus for hybrid beamforming in communication system - Google Patents

Abstract

Disclosed are a method and apparatus for hybrid beam formation in a communication system. A method of operating an AP in a communication system comprises the following steps of: calculating average effective channel energy with a plurality of pieces of UE to feed the same back to a CP; receiving information of UE groups determined based on the average effective channel energy from the CP; selecting a first UE group having the greatest sum of the average effective channel energy from among the UE groups, based on the information of the UE groups; allocating an analog beam to at least two pieces of UE belonging to the first UE group; and estimating an effective channel value through the analog beam to form a digital beam. Therefore, the present invention is capable of improving communication quality.

Description

Hybrid beamforming method and apparatus in a communication system

The present invention relates to a hybrid beamforming technology, and more particularly, to a user group-based hybrid beamforming technology of a cell-free massive multiple input multiple output (CFmMIMO) system.

An ultra-dense network (UDN) is a large-capacity mobile network capable of accommodating explosively increasing mobile traffic. With the increase in cell size and density, numerous access points are located close to the UE (user equipment). It may mean a new wireless coverage environment in which (access point, AP) exists. Since the average distance between the AP and the UE is very close, link performance is improved and network capacity may be further increased, but severe interference may occur between adjacent cells.

As a technology suitable for UDN, a CFmMIMO system, which is a technology for remarkably improving frequency and energy efficiency, can be considered by allowing a plurality of APs to simultaneously provide services to a plurality of UEs through the same time-frequency resource.

Hybrid beamforming technology can also be applied to the CFmMIMO system, and in the CFmMIMO system, the AP can design a phase shifter-based analog beamformer by using the channel covariance matrix, which is large-scale channel statistical information. However, since the AP determines the analog beam based on the average energy information of the effective channels of all UEs when designing the analog beamformer, orthogonality between the beams cannot be guaranteed, so there may be a problem in that interference between beams occurs within the AP.

An object of the present invention to solve the above problems is to provide a user group-based hybrid beamforming method and apparatus of a CFmMIMO system.

In the hybrid beamforming method performed by the AP according to the first embodiment of the present invention for achieving the above object, the effective channel average energy with a plurality of UEs is calculated and fed back to the CP, and the effective channel average energy is applied to the CP. Receives information on UE groups determined based on the CP, and selects a first UE group having the largest sum of effective channel average energy among the UE groups based on the information on the UE groups, and the first UE and allocating an analog beam to two or more UEs belonging to the group and estimating an effective channel value through the analog beam to form a digital beam.

According to the present application, the AP may select a suitable UE group and match analog beams to UEs belonging to the selected UE group. Inter-beam interference within the AP may be controlled according to UE grouping, and even if the AP allocates the same pilot to UEs belonging to a selected UE group, pilot pollution may be very low. Accordingly, communication quality may be improved through the UE group-based hybrid beamforming method.

1 is a conceptual diagram illustrating a first embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a conceptual diagram illustrating an embodiment of CFmMIMO in a communication system.
4 is a flowchart illustrating a hybrid beamforming method in a communication system.
5A is a conceptual diagram illustrating a first embodiment of a method for grouping UEs and allocating pilots in a communication system.
5B is a conceptual diagram illustrating a second embodiment of a method for grouping UEs and allocating pilots in a communication system.
5C is a conceptual diagram illustrating a third embodiment of a method for grouping UEs and allocating pilots in a communication system.
5D is a conceptual diagram illustrating a fourth embodiment of a method for grouping UEs and allocating pilots in a communication system.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

In embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B”. Also, in the embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B”.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

A communication system to which embodiments according to the present invention are applied will be described. The communication system to which the embodiments according to the present invention are applied is not limited to the content described below, and the embodiments according to the present invention can be applied to various communication systems. Here, a communication system may be used in the same sense as a communication network (network).

1 is a conceptual diagram illustrating a first embodiment of a communication system.

1, the communication system 100 is a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). A plurality of communication nodes 4G communication (eg, long term evolution (LTE), LTE-A (advanced)), 5G communication (eg, NR (new radio)) defined in the 3rd generation partnership project (3GPP) standard ) can be supported. 4G communication may be performed in a frequency band of 6 GHz or less, and 5G communication may be performed in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less.

For example, a plurality of communication nodes for 4G communication and 5G communication is a CDMA (code division multiple access) based communication protocol, WCDMA (wideband CDMA) based communication protocol, TDMA (time division multiple access) based communication protocol, FDMA (frequency division multiple access) based communication protocol, OFDM (orthogonal frequency division multiplexing) based communication protocol, Filtered OFDM based communication protocol, CP (cyclic prefix)-OFDM based communication protocol, DFT-s-OFDM (discrete) Fourier transform-spread-OFDM) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (Non-orthogonal multiple access), GFDM (generalized frequency) Division multiplexing)-based communication protocol, FBMC (filter bank multi-carrier)-based communication protocol, UFMC (universal filtered multi-carrier)-based communication protocol, SDMA (Space Division Multiple Access)-based communication protocol, etc. can be supported. .

Also, the communication system 100 may further include a core network. When the communication system 100 supports 4G communication, the core network may include a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), and a mobility management entity (MME). there is. When the communication system 100 supports 5G communication, the core network may include a user plane function (UPF), a session management function (SMF), an access and mobility management function (AMF), and the like.

On the other hand, a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130- 4, 130-5, 130-6) may each have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2 , the communication node 200 may include at least one processor 210 , a memory 220 , and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240 , an output interface device 250 , a storage device 260 , and the like. Each of the components included in the communication node 200 may be connected by a bus 270 to communicate with each other.

However, each of the components included in the communication node 200 may not be connected to the common bus 270 but to the processor 210 through an individual interface or an individual bus. For example, the processor 210 may be connected to at least one of the memory 220 , the transceiver 230 , the input interface device 240 , the output interface device 250 , and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260 . The processor 210 may mean a central processing unit (CPU), a graphic processing unit (grAPhics processing unit, GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be configured as at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1 , the communication system 100 includes a plurality of base stations 110 - 1 , 110 - 2 , 110 - 3 , 120 - 1 and 120 - 2 , and a plurality of terminals 130 - 1, 130-2, 130-3, 130-4, 130-5, 130-6). Base stations 110-1, 110-2, 110-3, 120-1, 120-2 and terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 The comprising communication system 100 may be referred to as an “access network”. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. there is. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 is a NodeB (NodeB), an advanced NodeB (evolved NodeB), a BTS (base transceiver station), Radio base station (radio base station), radio transceiver (radio transceiver), access point (access point), access node (node), RSU (road side unit), RRH (radio remote head), TP (transmission point), TRP ( transmission and reception point), eNB, gNB, and the like.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is a user equipment (UE), a terminal, an access terminal, and a mobile Terminal (mobile terminal), station (station), subscriber station (subscriber station), mobile station (mobile station), portable subscriber station (portable subscriber station), node (node), device (device), IoT (Internet of Thing) It may be referred to as a device, a mounted device (such as a mounted module/device/terminal or on board device/terminal).

Next, a cell-free massive multiple input multiple output (CFmMIMO) system can be described. In a hybrid beamforming-based CFmMIMO system, M APs equipped with n _T antennas and L (< n _T ) radio frequency (RF) chains may be connected to a centralized processor (CP), and distributed It is possible to perform cooperative communication with the K UEs. Each of the K UEs may include a single antenna.

The millimeter-wave band technology, which utilizes the wide bandwidth of the millimeter-wave (mmWave) band, can be combined with large-scale MIMO to improve frequency efficiency. In particular, applying the mmWave technology to the CFmMIMO system where APs are densely distributed and enable cooperative communication can be very useful considering the limited communication range of the mmWave band. However, since the millimeter wave band technology requires a high power consumption level and high production cost, it is difficult to fully-digitize a large-scale MIMO structure, so in general, a hybrid digital-analog signal processing structure can be oriented. there is.

3 is a conceptual diagram illustrating an embodiment of CFmMIMO in a communication system.

Referring to FIG. 3 , in the CFmMIMO system, large-scale APs distributed in a coverage area are connected to one CP to provide a service to all UEs in a much smaller number than the APs through the same time/frequency resource.

은

일 수 있고, UE들의 집합

는

일 수 있다. AP는 최대 L개의 아날로그 빔들을 생성할 수 있고, 동일 AP는 서로 다른 빔들을 사용하여 서로 다른 UE들을 위한 빔을 형성할 수 있다. AP의 각 아날로그 빔이 하나의 UE만을 위해 매칭된다고 가정할 때, 활성(active) UE들의 개수(K)가 K

L이면 AP의 아날로그 빔으로 네트워크 내의 모든 UE들에 서비스를 제공할 수 있다. 활성 UE는 RRC(radio resource control) 연결(connected) 상태인 UE를 의미할 수 있다. 그러나 AP는 K>L이면 L개의 아날로그 빔에 매칭되는 UE를 선택하는 과정이 필요할 수 있다. set of APs

silver

may be, a set of UEs

Is

can be The AP may generate up to L analog beams, and the same AP may use different beams to form beams for different UEs. Assuming that each analog beam of the AP is matched for only one UE, the number of active UEs (K) is K

If it is L, it is possible to provide a service to all UEs in the network with an analog beam of the AP. Active UE may mean a UE in a radio resource control (RRC) connected (connected) state. However, if K>L, the AP may need to select a UE matching the L analog beams.

L일 수 있다. 따라서 K

로 가정할 수 있고, CP는 UE들의 대규모(large-scale) 전파 패턴을 파악하여 서로 위치적으로 충분히 떨어져 있는 L개의 UE들을 하나의 UE 그룹으로 그룹화(grouping)할 수 있다. 따라서 CP는 전체 활성 UE들을 다수의 UE 그룹들로 나눌 수 있고, 각 UE 그룹에 파일럿을 할당할 수 있다. 각 AP는 적절한 UE 그룹을 선택할 수 있고, 아날로그 빔을 선택한 UE 그룹에 속하는 UE들에 할당할 수 있다.However, in a UDN environment, in general, the number of active UEs (K) is K

can be L. So K

can be assumed, and the CP may group L UEs sufficiently far apart in location from each other into one UE group by identifying a large-scale propagation pattern of the UEs. Accordingly, the CP may divide all active UEs into multiple UE groups, and may allocate pilots to each UE group. Each AP may select an appropriate UE group and may allocate an analog beam to UEs belonging to the selected UE group.

4 is a flowchart illustrating a hybrid beamforming method in a communication system.

Referring to FIG. 4 , in the hybrid beamformer, a large number of antenna arrays can be connected to a limited number of RF chains through analog beamformers, and a low-dimensional baseband digital beamformer is used at the output end of the RF chain. It may be a structure that The digital beamformer may perform baseband signal processing for forming a digital beam by utilizing an effective channel value that may be generated by matching an analog beam. The communication node (eg, CP, AP, and/or UE) may include at least one of a hybrid beamformer, an analog beamformer, or a digital beamformer.

[Analog beamforming method]

의 고유 분해(eigen-value decomposition, EVD)를 통해 지배적인(dominant) 고유벡터

를 획득할 수 있다. 또한 APm은 원소의 위상각만으로

을 구성할 수 있고, 생성한 벡터

을 APm의 아날로그 빔형성 행렬을 구성할 후보 빔벡터로 설정할 수 있다. 각 APm은 K개의 후보벡터

를 가질 수 있다. The analog beamformer may be designed based on the statistical information of the channel, and it may be assumed that each AP knows the channel spatial covariance information. APm(m=1, ...,M) is the channel space covariance matrix of UEk(k=1, ...,K)

The dominant eigenvector through the eigen-value decomposition (EVD) of

can be obtained. In addition, APm is only the phase angle of the element.

can be constructed, and the vector generated

can be set as a candidate beam vector constituting the analog beamforming matrix of APm. Each APm has K candidate vectors

can have

를 이미 획득한 정보

,

를 이용하여 아래 수학식 1을 통해 계산할 수 있다(S401).Since APm can generate an effective channel by forming an analog beam, the average energy of the effective channel by each candidate vector (average Frobenius norm)

information that has already been acquired

,

It can be calculated using Equation 1 below (S401).

를 CP에 피드백할 수 있다(S402). CP는 APm로부터 모든 UE들의 유효채널 평균에너지

를 수신할 수 있다. CP는 APm로부터 전달받은 유효채널의 평균에너지 값을 이용하여 대규모 전파 패턴에 의한 UE들의 위치를 특정할 수 있고, 위치적으로 최대한 떨어져 있는 L개의 UE들로 구성된 다수의 UE 그룹들로 그룹화할 수 있다. CP는 UE들을 그룹화한 후, 각 UE 그룹들에게 파일럿을 할당할 수 있다(S403). CP는 UE 그룹 별로 서로 다른 파일럿을 할당할 수 있다. APm is the effective channel average energy of all UEs calculated through Equation 1 above.

may be fed back to the CP (S402). CP is the effective channel average energy of all UEs from APm

can receive The CP can specify the location of the UEs by the large-scale propagation pattern using the average energy value of the effective channel received from the APm, and can be grouped into a plurality of UE groups consisting of L UEs located as far apart as possible. there is. After grouping the UEs, the CP may allocate a pilot to each UE group (S403). The CP may allocate different pilots to each UE group.

The CP may transmit UE group information to the APm (S404). APm may receive UE group information from CP. In addition, the CP may transmit pilot assignment information to all UEs including UEk (S405). All UEs including UEk may receive pilot assignment information from the CP. Upon receiving the pilot assignment information from the CP, the UEk may be assigned a pilot according to the pilot assignment information. When the total number of UE groups is N, APm may select a UE group having the largest sum of effective channel average energies of the UEs from among the N UE groups, and allocate analog beams to UEs belonging to the UE group. can be (S406). The sum of the effective channel average energies of the UEs belonging to each UE group may be expressed as in Equation 2 below.

APm may select a UE group to which an analog beam is to be allocated through Equation 3 below.

로 나타낼 수 있다. 따라서 APm의 아날로그 빔형성 행렬

은 아래 수학식 4와 같이 벡터 값으로 나타낼 수 있다. Analog beamforming candidate vectors of UEs belonging to the selected UE group are

can be expressed as Thus, the analog beamforming matrix of APm

can be expressed as a vector value as in Equation 4 below.

[Digital Beamforming Method]

)을 추정할 수 있다. 유효채널은 아래 수학식 5와 같이 나타낼 수 있다.When the analog beamformer is set, APm receives the pilot signal from the UE and

) can be estimated. The effective channel can be expressed as in Equation 5 below.

In one embodiment, the digital beamforming operation may be performed locally at each AP using the effective channel estimate of Equation (5). In another embodiment, the CP may perform the digital beamforming operation globally by collecting effective channel estimates of all UEs from all APs (S407).

[UE grouping and pilot assignment]

는 UEk의 위치를 나타내는 특징 벡터(feature vector)일 수 있으며, CP는

를 이용하여 UE들을 분류할 수 있다. CP는 UE들을 위치에 따라 분류하기 위하여 자카드 유사도(Jaccard similarity)를 활용할 수 있다. 자카드 유사도는 자카드 계수(Jaccard coefficient)로 칭할 수도 있다. 자카드 유사도는 벡터의 각도 차이를 나타내는 코사인 유사도(cosine similarity)와 벡터의 길이 차이를 표현하는 유클리드 거리(Euclidean distance)를 모두 반영할 수 있다. 평균에너지 벡터들의 가상의 중심(centroid)을

라 할 때, CP는 모든 UE들에 대해 중심

에 대한 자카드 유사도를 아래 수학식 6을 통해 계산할 수 있다.The step of grouping the UEs by the CP of step S403 and allocating a pilot to each UE group may be described in more detail. Average energy of effective channels of all APs connected to UE k

may be a feature vector indicating the location of the UEk, CP is

can be used to classify UEs. The CP may utilize Jaccard similarity to classify UEs according to location. The jacquard similarity may be referred to as a Jaccard coefficient. The jacquard similarity may reflect both cosine similarity indicating a difference in angle between vectors and Euclidean distance indicating a difference in length between vectors. The imaginary centroid of the average energy vectors

, CP is the center for all UEs

The jacquard similarity to can be calculated through Equation 6 below.

는 0~1의 값을 가질 수 있으며, 0은 완전 비유사도, 1은 완전 유사도를 의미할 수 있다. 따라서 자카드 유사도

가 0에 가까울수록 비유사하고, 1로 가까울수록 유사함을 의미할 수 있다.

를 오름차순으로 배열할 때, UE들 간의 대규모 전파 패턴 기반의 위치가 유사할수록 해당 UE들은 배열상 가까운 위치에 있다고 볼 수 있다. CP는 배열상 최대로 떨어져 있는 L개의 UE들로 하나의 UE 그룹을 만들 수 있다. 예를 들어, K=LN이라 하면 총 N개의 UE 그룹들 중 n 번째 UE 그룹은 자카드 유사도에 따라 오름차순 배열된 UE들을 N 간격으로 선택한 UE들의 집합일 수 있고, 아래 수학식 7과 같이 L개의 자카드 유사도 집합으로 나타낼 수 있다.Jacquard Similarity

may have a value of 0 to 1, 0 may mean complete dissimilarity, and 1 may mean complete similarity. Therefore, the jacquard similarity

The closer to 0, the more dissimilar, and the closer to 1, the more similar.

When arranging in ascending order, the more similar the locations based on the large-scale propagation pattern between the UEs, the closer the UEs can be seen in the arrangement. The CP can make one UE group with L UEs that are at most spaced apart in the array. For example, if K=LN, the n-th UE group among the total N UE groups may be a set of UEs in which UEs arranged in ascending order according to the jacquard similarity are selected at N intervals, and L jacquard as shown in Equation 7 below. It can be expressed as a set of similarities.

라 하면 N=

일 때, CP는 모든 UE 그룹들에 직교 파일럿을 할당할 수 있으므로 파일럿 오염이 발생하지 않을 수 있다.UEs belonging to a UE group may share the same pilot because they are geographically distant from each other. length of the pilot sequence.

If N=

, since the CP can allocate orthogonal pilots to all UE groups, pilot pollution may not occur.

5A is a conceptual diagram illustrating a first embodiment of a method for grouping UEs and allocating pilots in a communication system. 5B is a conceptual diagram illustrating a second embodiment of a method for grouping UEs and allocating pilots in a communication system. 5C is a conceptual diagram illustrating a third embodiment of a method for grouping UEs and allocating pilots in a communication system. 5D is a conceptual diagram illustrating a fourth embodiment of a method for grouping UEs and allocating pilots in a communication system.

)에 기반하여 다양한 UE 그룹화가 가능하다. a 및 b를 mod 함수와 floor 함수로 정의할 수 있다. 즉,

라 할 때, CP는 UE 그룹들의 개수 N이 N=a+b가 되도록 UE들을 그룹화하고 각 UE 그룹에 파일럿을 할당할 수 있다. 도 5a 내지 5d는

=4, L=3일 때, UE 그룹화 및 파일럿 할당 방법의 실시예들을 나타낼 수 있고, 각 실시예에서 K개의 UE들의 배열 순서는 오름차순 배열의 자카드 유사도에 따라 나열한 것일 수 있다.5A to 5D, according to the number K of active UEs in the network, the pilot sequence length (

), various UE groupings are possible. A and b can be defined as mod and floor functions. in other words,

In this case, the CP may group UEs such that the number N of UE groups becomes N=a+b, and may allocate pilots to each UE group. 5a to 5d are

When =4, L=3, embodiments of the UE grouping and pilot assignment method may be shown, and the arrangement order of K UEs in each embodiment may be arranged according to the jacquard similarity of the ascending arrangement.

)=0일 때, CP는 UE들을 그룹화하기 위해, 전체 UE들 중에 동일한 n=mod(k,b)값을 갖는 UE들을 UE 그룹

에 포함시킬 수 있고, 전체 N(=b)개의 UE 그룹들

(예를 들어,

)을 생성할 수 있다. CP는 동일한 mod(n,

)를 갖는 UE 그룹

에는 동일한 파일럿을 할당할 수 있고, 서로 다른 mod(

,

)를 갖는 UE 그룹

에는 직교 파일럿을 할당할 수 있다.Referring to Figure 5a, a = 0, mod (b,

) = 0, the CP groups UEs having the same n=mod(k,b) value among all UEs to group the UEs into a UE group.

Can be included in the total N (=b) UE groups

(for example,

) can be created. CP is the same mod(n,

) group of UEs with

can be assigned the same pilot, and different mod(

,

) group of UEs with

may be assigned an orthogonal pilot.

)=0일 때, K₁

K-a, k₁=1, ..., K₁, k₂=K₁+1, ..., K(예를 들어,K₁=24, k₁=1, ..., 24, k₂=25,26)라 할 수 있다. CP가 k₁을 그룹화하는 방법으로, CP는 K₁개의 UE들 중에 동일한 n₁=mod(k₁,b) 값을 갖는 UE들을 UE 그룹

에 포함시킬 수 있고, 전체 N₁(=b)개의 UE 그룹들

(예를 들어,

)을 생성할 수 있다. CP가 k₁의 파일럿을 할당하는 방법으로, 동일한 mod(n₁,

)를 갖는 UE 그룹

에는 동일한 파일럿을 차례로 할당할 수 있고, 서로 다른 mod(

,

)를 갖는 UE 그룹

에는 직교 파일럿을 차례로 할당할 수 있다.Referring to Figure 5b, a>0, mod(b,

When )=0, K ₁

Ka, k ₁ =1, ..., K ₁ , k ₂ =K ₁ +1, ..., K (eg, K ₁ =24, k ₁ =1, ..., 24, k ₂ =25,26). In a way that the CP groups k ₁ , the CP groups UEs having the same n ₁ =mod(k ₁ ,b) value among K ₁ UEs into a UE group.

Can be included in the total N ₁ (=b) UE groups

(for example,

) can be created. How the CP allocates a pilot of k ₁ , the same mod(n ₁ ,

) group of UEs with

can be assigned the same pilot in turn, and different mod(

,

) group of UEs with

may be sequentially assigned orthogonal pilots.

) 중에 배열 간격이 충분히 큰 (L-1)개의 UE들을 랜덤하게 선택하여 k₂와 함께 UE 그룹

에 포함하여 a개의 UE 그룹

(예를 들어,

및

)을 생성할 수 있다. 이 과정을 통해 전체 N(a+b)개(예를 들어, 전체 10개)의 UE 그룹들이 생성될 수 있다.As a method in which the CP allocates a pilot of k ₂ and groups UEs, a pilot may be randomly assigned to any one UE in k ₂ so as not to overlap with an adjacent UE, and k ₁ to which the same pilot as k ₂ is allocated (<K ₁ -

) by randomly selecting (L-1) UEs with a sufficiently large arrangement interval among k ₂ together with a UE group

a group of UEs including

(for example,

and

) can be created. Through this process, a total of N(a+b) (eg, a total of 10) UE groups may be generated.

)>0 일 때, UE들을 그룹화하는 방법은 도 5a와 마찬가지로 CP는 전체 UE들 중에 동일한 n=mod(k,b) 값을 갖는 UE들을 UE 그룹

에 포함시킬 수 있고, 전체 N(=b)개의 UE 그룹들

(예를 들어,

)을 생성할 수 있다. 다만, 파일럿 할당 방법에서 CP는 먼저

인 경우, 동일한 mod(n,

)를 갖는 UE 그룹

에는 동일한 파일럿을 차례로 할당할 수 있고, 서로 다른 mod(

,

)를 갖는 UE 그룹

에는 직교 파일럿을 차례로 할당할 수 있다. 그리고 CP는 n>N-mod(b,

) 인 UE 그룹에 파일럿이 인접 UE와 중복되지 않도록 랜덤하게 할당(예를 들어,

의 파일럿은 3)할 수 있다. Referring to FIG. 5c , a=0 and mod(b,

When ) > 0, the method of grouping UEs is similar to FIG. 5a , in which CP groups UEs having the same n=mod(k,b) value among all UEs into a UE group.

Can be included in the total N (=b) UE groups

(for example,

) can be created. However, in the pilot allocation method, the CP is first

If , the same mod(n,

) group of UEs with

can be assigned the same pilot in turn, and different mod(

,

) group of UEs with

may be sequentially assigned orthogonal pilots. And CP is n>N-mod(b,

) randomly assigned to the UE group so that pilots do not overlap with neighboring UEs (eg,

The pilot of 3) can.

)>0 일 때, K₁

K-a, k₁=1, ..., K₁, k₂=K₁+1, ..., K(예를 들어,K₁=27, k₁=1, ..., 27, k₂=28,29)라 할 수 있다. k₁의 그룹화 방법은 도 5b와 마찬가지로 CP는 K₁개의 UE들 중에 동일한 n₁=mod(k₁,b) 값을 갖는 UE들을 UE 그룹

에 포함시킬 수 있고, 전체 N₁(=b) 개의UE 그룹들

(예를 들어,

)을 생성할 수 있다. k₁의 파일럿 할당 방법으로, CP는 생성된 N₁(=b)개의 UE 그룹들 중에 n₁

N₁-mod(b,

)인 경우, 동일한 mod(n₁,

)를 갖는 UE 그룹

에는 동일한 파일럿을 차례로 할당할 수 있고, 서로 다른 mod(

,

)를 갖는 UE 그룹

에는 직교 파일럿을 차례로 할당할 수 있다. CP는 n₁>N₁-mod(b,

)인 UE 그룹은 파일럿을 인접 UE와 중복되지 않도록 랜덤하게 할당(예를 들어,

의 파일럿은 2)할 수 있다.Referring to Figure 5d, a>0, and mod(b,

When )>0, K ₁

Ka, k ₁ =1, ..., K ₁ , k ₂ =K ₁ +1, ..., K (eg, K ₁ =27, k ₁ =1, ..., 27, k ₂ =28,29). In the grouping method of k ₁ , as in FIG. 5B , the CP is a UE group for UEs having the same n ₁ =mod(k ₁ ,b) value among K ₁ UEs.

Can be included in the total N ₁ (=b) UE groups

(for example,

) can be created. With the pilot allocation method of k ₁ , the CP is n ₁ among the generated N ₁ (=b) UE groups.

N ₁ -mod(b,

), the same mod(n ₁ ,

) group of UEs with

can be assigned the same pilot in turn, and different mod(

,

) group of UEs with

may be sequentially assigned orthogonal pilots. CP is n ₁ >N ₁ -mod(b,

) is randomly assigned pilots so as not to overlap with neighboring UEs (e.g.,

The pilot of 2) can.

)인 UE 그룹에 할당된 파일럿과 중복되지 않을 뿐 아니라 k₂의 인접 UE의 파일럿과 중복되지 않도록 랜덤하게 할당할 수 있다. 또한 CP는 k₂와 동일한 파일럿을 할당 받은 k₁(<K₁-

) 중에 배열 간격이 충분히 큰 (L-1)개의 UE들을 랜덤하게 선택하여 k₂와 함께 UE 그룹

에 포함하여 a개의 UE 그룹들

(예를 들어,

및

)을 생성할 수 있다. 이 과정을 통해 생성된 전체

개(예를 들어, 전체 11개)의 UE 그룹들이 생성될 수 있다.In a way that the CP allocates a pilot of k ₂ and groups UEs, the CP is n ₁ >N ₁ -mod(b,

_. Also, CP is k _{1 (<K 1 -}

) by randomly selecting (L-1) UEs with a sufficiently large arrangement interval among k ₂ together with a UE group

a UE groups including

(for example,

and

) can be created. The whole created through this process

A number of (eg, 11 in total) UE groups may be created.

[UE group and analog beam update]

를 획득할 수 있다. APm은 원소의 위상각만으로

을 구성할 수 있고, 생성한 벡터

와 채널 공분산 행렬을 이용해서 유효채널의 평균에너지

를 계산할 수 있다(S409). APm은 계산한 유효채널의 평균에너지

를 CP에 피드백할 수 있다(S410). CP는 APm로부터

를 수신할 수 있다.When a new UE (eg, UE k′) wants to receive a service by entering the network, it may transmit a service request message to all APs ( S408 ). All APs may receive the service request message from the new UE (eg, UE k′) and estimate the channel covariance matrix using the large-scale propagation pattern. APm is the dominant eigenvector through EVD

can be obtained. APm is only the phase angle of the element.

can be constructed, and the vector generated

and the average energy of the effective channel using the channel covariance matrix

can be calculated (S409). APm is the calculated average energy of the effective channel

may be fed back to the CP (S410). CP from APm

can receive

를 이용하여 상술한

를 아래 수학식 8에 따라 업데이트할 수 있다.CP is a feature vector indicating a location with the average energy of a new UE (eg, UE k′) collected from all APs.

described above using

can be updated according to Equation 8 below.

와

를 통해 자카드 유사도

를 계산할 수 있고, 기존의

과 비교하여 가장 근사한 값을 갖는 UE(예를 들어,

)를 찾아낼 수 있다. 가장 근사한 값을 갖는 UE(예를 들어,

)에 서비스를 제공하고 있는 AP들의 집합(예를 들어,

)이 구성될 수 있다. UE들(예를 들어, k'와

) 간의 유효채널 평균 에너지를 비교하여

를 만족할 경우, CP는 기존의

과 비교하여 가장 근사한 값을 갖는 UE(예를 들어,

)의 UE 그룹을 새로운 UE 그룹으로 업데이트할 수 있다. CP는 UE 그룹을 업데이트 한 후, 새로운 UE(예를 들어, k')에게 파일럿을 할당할 수 있다(S411). CP

Wow

Jacquard similarity through

can be calculated, and the existing

UE with the closest value compared to (e.g.,

) can be found. UE with the closest value (e.g.,

) a set of APs providing services (eg,

) can be configured. UEs (eg, k' and

) by comparing the effective channel average energy between

is satisfied, the CP is

UE with the closest value compared to (e.g.,

) may be updated with a new UE group. After updating the UE group, the CP may allocate a pilot to a new UE (eg, k′) ( S411 ).

The CP may transmit pilot assignment information to a new UE (eg, k') (S412). The new UE (eg, k′) may receive pilot assignment information from the CP, and a pilot may be assigned to the new UE (eg, k′) according to the pilot assignment information.

및

)할 수 있다. 상술한 조건(예를 들어,

)이 만족되지 않을 경우, CP는 근사값을 갖는 다른 UE에 대해 상술한 과정(즉, 단계 S411 및 S412)을 수행할 수 있다(S413). 그리고 상술한 단계 S407과 마찬가지로 각 AP 또는 CP가 디지털 빔형성기를 업데이트할 수 있다(S414). 여러 개의 새로운 UE들이 서비스를 제공받기를 원하는 경우, APm은 전체 UE들의 개수 K를 업데이트하여 상술한 업데이트 절차(즉, 단계 S409 내지 S414)를 수행할 수 있다.The CP updates the set of APs and the analog beam vector (eg,

and

)can do. The conditions described above (e.g.,

) is not satisfied, the CP may perform the above-described process (ie, steps S411 and S412) for another UE having an approximate value (S413). And, similarly to the above-described step S407, each AP or CP may update the digital beamformer (S414). If several new UEs want to receive the service, APm may update the total number of UEs K and perform the above-described update procedure (ie, steps S409 to S414).

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software.

Examples of computer-readable media include hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a setting computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

Although it has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. will be able

Claims (1)

As an operating method of an access point (AP) in a communication system,
calculating effective channel average energy with a plurality of user equipments (UEs) and feeding them back to a centralized processor (CP);
receiving information on UE groups determined based on the effective channel average energy from the CP;
selecting a first UE group having the largest sum of effective channel average energies from among the UE groups based on the information on the UE groups;
allocating an analog beam to two or more UEs belonging to the first UE group; and
and forming a digital beam by estimating an effective channel value through the analog beam.

Images