KR20140022727A - Method for beamforming based on cluster - Google Patents

Abstract

Disclosed is a beamforming method based on a cluster, capable of improving the transmission performance of data by using a millimeter wave band. The beamforming method performed in a base station includes the steps of: transmitting control information to a plurality of terminals; receiving measurement information corresponding to the control information from the terminals; grouping the terminals into a plurality of groups based on the received measurement information; and transmitting the received measurement information to an upper base station by beamforming. Thereby, a high speed data transmission is performed through a small cell communication environment based on a beam using the millimeter wave band. [Reference numerals] (100) Central base station; (200) Relay base station; (300) Mobile terminal; (S210) Control information; (S220) Perform measurement from received control information; (S230) Measurement information; (S240) Mobile terminal grouping; (S250) Measurement information; (S260,270) Service request; (S280) Beamformed information; (S290) Service response

Description

Cluster-based beamforming method {METHOD FOR BEAMFORMING BASED ON CLUSTER}

The present invention relates to a data transmission technology, and more particularly, to a cluster-based beamforming method capable of transmitting data at high speed in a cellular wireless communication environment using a millimeter wave band.

The exponential increase in mobile data usage every year is expected to explode rapidly and increase to 1000 times in 2020.

On the other hand, the change in the characteristics of mobile usage shows that the usage of smart phones such as smartphones and tablets has increased by 24 times, and the mobile data rate has shifted from voice / text to video (66.4%, 2015). Tens to hundreds of times increased.

Mobile traffic is expected to increase rapidly in the future as mobile cloud services and mass media become more common. Specifically, a compressed ultra high definition (UHD) video service and a stable service in the cloud are expected to require at least 800 Mbps per user.

Therefore, the need for a technology that provides 1000 times the capacity of the existing LTE (Long Term Evolution) has emerged. Although technology is needed for mobile traffic, which is expected to increase rapidly by 1000 times by 2020, it is expected to be difficult to achieve with current technology.

In the case of 3GPP LTE, which is currently being serviced at home and abroad, the maximum bandwidth is 20 MHz, and the theoretical maximum transmission capacity per cell can be 150 Mbps (4 ㅧ 2 MIMO), and in reality it is within 100 Mbps.

LTE-Advanced technology, which is currently being standardized, uses CA (Carrier Aggregation) technology up to 100 MHz and transmits per cell even if 8 하더라도 8 Multiple Input Multiple Output (MIMO) and Coordinated Multi Point Transmission (CoMP) technologies are introduced. It is difficult to support more than 1 Gbps.

Even if the new frequency is secured by the photocatalog plan, it is not enough to meet the global agency's mobile traffic forecast (1000x by 2020). In particular, the European Union (EU) predicted that at least 1.2 GHz frequency band would be needed in 2015 and 2 GHz or higher frequency band would be needed in 2020.

Therefore, a new mobile communication network structure of the N-Throughput concept is needed, where the capacity of a cell increases as the number of users or relay terminals increases beyond the current cellular structure in which each user divides the total cell capacity as the number of users increases. Was done.

When the N-Throughput concept mobile communication system is implemented, each user can maintain the same quality of service experience regardless of the increase in the number of users, and thus it is expected to meet the explosive demand for mobile communication traffic.

At the time when high-speed large-capacity transmission (increase in cell capacity) is required to meet exponentially increasing data demands, research on applying technology to the cellular environment of the millimeter band instead of the existing cellular band is being conducted. Is not enough.

An object of the present invention is to provide a cluster-based beamforming method that can improve the performance of data transmission.

According to the cluster-based beamforming method according to an embodiment of the present invention for achieving the above object, the step of transmitting the control information to the mobile terminal, and receiving and receiving the measurement information corresponding to the control information from the mobile terminal Transmitting the measured information to the central base station using beamforming, transmitting a service request message received from the mobile terminal to the central base station using beamforming, and using the beamforming from the central base station Receiving information corresponding to a service request message and transmitting the received information to the mobile terminal using beamforming.

Here, the measurement information may include at least one of a cell ID of the base station and a beam ID to which the plurality of terminals are mapped.

The grouping of the plurality of terminals into a plurality of groups based on the received measurement information may include grouping terminals included in the same beam ID into the same group based on the beam IDs to which the plurality of terminals are mapped. Terminals included in the beam ID may be grouped into different groups.

Here, after the step of transmitting the received measurement information to a higher base station using beamforming, receiving a service request message from a plurality of terminals, transmitting the received service request message to a higher base station, and Receiving information corresponding to the service request message from an upper base station and transmitting the information to the plurality of groups using beamforming based on a beam ID included in the information corresponding to the service request message. can do.

Here, the step of transmitting the information to the plurality of groups using beamforming based on the beam ID included in the information may include: Frequency Division Multiplexing for terminals belonging to the same group among the plurality of groups. , FDM) can be transmitted using beamforming.

The transmitting of the information to the plurality of groups using beamforming based on the beam ID included in the information may include time division multiplexing for terminals belonging to another group of the plurality of groups. TDM) may transmit the information using beamforming.

Here, the information corresponding to the service request message may include a beam ID corresponding to the information corresponding to the service request message.

Here, the step of transmitting the information to the plurality of groups using beamforming based on the beam ID included in the information corresponding to the service request message may include analog or digital information corresponding to the service request message. (digital) can be transmitted to a plurality of mobile terminals through beamforming.

Here, the step of transmitting the information by beamforming to the plurality of groups based on the beam ID included in the information corresponding to the service request message, amplify the information corresponding to the service request message, The amplified information may be forwarded to the plurality of mobile terminals 300.

Here, the step of transmitting the information to the plurality of groups using beamforming based on the beam ID included in the information corresponding to the service request message includes: decoding and decoding the information corresponding to the service request message. May be transmitted to the plurality of mobile terminals based on the beam index included in the information corresponding to the service request message.

According to the cluster-based beamforming method according to an embodiment of the present invention as described above, the measurement information corresponding to the control information transmitted from the mobile terminal is received and transmitted to the central base station, and the service request message received from the mobile terminal After transmitting to the central base station, information corresponding to the service request message is transmitted from the central base station to the mobile terminal through beamforming.

Therefore, high-speed data transmission is possible through a beam-based small cell communication environment using a millimeter wave band.

1 illustrates a cluster-based beamforming system in which a cluster-based beamforming method is performed according to an embodiment of the present invention.
2 is a flowchart illustrating a process of performing a cluster-based beamforming method according to an embodiment of the present invention.
3 is a flowchart illustrating a process performed in a central base station in a cluster-based beamforming method according to an embodiment of the present invention.
4 is a flowchart illustrating a process performed in a relay base station in a cluster-based beamforming method according to an embodiment of the present invention.
5 is a conceptual diagram illustrating control information beamformed and transmitted according to an embodiment of the present invention.
FIG. 6 is a flowchart for describing in detail step 460 of the steps illustrated in FIG. 4.
7 is a conceptual diagram illustrating a configuration for analog beamforming according to an embodiment of the present invention.
8 is a flowchart illustrating a process performed in a mobile terminal in a cluster-based beamforming method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

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

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or 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 commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, a mobile terminal is a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a mobile phone, a smart phone capable of communication. , e-book readers, portable multimedia players (PMPs), portable game consoles, navigation devices, digital cameras, digital multimedia broadcasting (DMB) players, digital audio recorders, digital voice players ( and a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player, and the like.

In addition, the base station used in the present application generally refers to a fixed or mobile point for communicating with a mobile terminal, and includes a base station, a Node-B, an eNode-B, BTS (base transceiver system), access point, access point, receive point, receive point, remote radio head (RRH), remote radio element (RRE), remote radio unit (RRU), relay (relay) and femto-cell (femto-cell) may be a generic term.

Hereinafter, a cluster-based beamforming method will be described with reference to the drawings.

1 illustrates a cluster-based beamforming system in which a cluster-based beamforming method is performed according to an embodiment of the present invention.

Referring to FIG. 1, a cluster-based beamforming system according to an embodiment of the present invention includes a clustered mobile terminal group including a central base station 100, a relay base station 200, and a plurality of mobile terminals 300. It may include.

The central base station 100 obtains and stores information about a plurality of mobile terminals 300 distributed in a cell, and one in a cell, and is responsible for scheduling.

In this case, the cell refers to an area subdivided into a small area in order to use the frequency efficiently. In general, a base station is installed in the center of a cell to relay a plurality of mobile terminals 300, and a cell refers to a service area provided by one base station.

In addition, the central base station 100 performs a backhauling function and information exchange using a beamforming technique in a millimeter wave (mmW) band with a fixed relay base station 200.

Here, the millimeter wave is a radio wave having a wavelength between 1 millimeter and 10 millimeters and corresponds to a radio frequency between 3 GHz and 300 GHz.

According to the International Telecommunication Union (ITU), these frequencies belong to the Extremely High Frequency (EHF) band, and these radio waveforms have unique propagation characteristics.

For example, millimeter waves have higher propagation loss compared to lower frequency radio waves, and do not penetrate well through objects such as buildings, walls, and tree trunks, and are absorbed in the atmosphere and refracted by particles such as rain drops in the atmosphere. And more sensitive to diffraction. On the other hand, due to the short wavelength of the millimeter wave, more antennas can be concentrated in a relatively small area. This enables the implementation of a small form of high gain antenna.

At least one relay base station 200 may be distributed in one cell, and may transmit and receive data to and from the base station 100 using beamforming in a millimeter wave band.

In addition, the relay base station 200 decodes a part of the information received from the central base station 100, and when the switch includes a plurality of antenna beamforming.

In addition, the relay base station 200 may cluster terminals mapped to the same beam ID and group them in the same group, or group the terminals mapped to different beam IDs and group them in different groups (310, 320). , 330).

In addition, the relay base station 200 applies frequency division multiplexing to the mobile terminals 310, 320, and 330 mapped to the same beam ID and clustered into the same group, thereby providing information corresponding to the service request message to the mobile terminals in the same group. 321, 322, and 323.

Alternatively, the relay base station 200 may apply time division multiplexing to mobile terminals mapped to different beam IDs and clustered into different groups to transmit information corresponding to the service request message to mobile terminals belonging to different groups.

In addition, the relay base station 200 transmits the received measurement information to the central base station 100 when measurement information corresponding to the control information is received from the plurality of mobile terminals 300.

The mobile terminal 300 is included in the relay base station 200 and measures necessary information from the received control information to perform cluster-based beamforming, and feeds back the measured information to the relay base station 200. .

Here, the measurement information may include a cell ID of the relay base station 200 and a beam ID of the relay base station 200 to which the mobile terminal 300 belongs, and if the mobile terminal 300 is connected to the central base station 100. In this case, the cell ID of the central base station 100 and the beam ID of the central base station 100 to which the mobile terminal 300 belongs may be included.

Hereinafter, a cluster-based beamforming process according to an embodiment of the present invention will be described with reference to FIG. 2.

2 is a flowchart illustrating a process of performing a cluster-based beamforming method according to an embodiment of the present invention.

Although the plurality of mobile terminals 300 may receive beamformed control information from the central base station 100 or the relay base station 200, it is assumed that the plurality of mobile terminals 300 are connected to the relay base station 200. For example, it will be described as receiving the beamformed control information from the relay base station 200.

Referring to FIG. 2, the relay base station 200 transmits control information to the plurality of mobile terminals 300 using beamforming (S210).

Here, the number of beams used when the relay base station 200 transmits control information to the plurality of mobile terminals 300 may be set to an appropriate number according to the size of the cell and the beam width of the array antenna.

When the plurality of mobile terminals 300 receives beamformed control information from the relay base station 200 through step 210, the plurality of mobile terminals 300 performs measurement from the received control information (S220).

Thereafter, the plurality of mobile terminals 300 transmits measurement information, which is a measurement result, to the relay base station 200 (S230).

Here, the measurement information may include the cell ID of the relay base station 200 and the beam ID of the relay base station 200, if the plurality of mobile terminal 300 is connected to the central base station 100, the central base station 100 Cell ID) and the beam ID of the central base station 100.

The relay base station 200 groups the plurality of mobile terminals based on the received measurement information when the measurement information is received through step 230. That is, the relay base station 200 groups mobile terminals having the same beam ID into the same group, and mobile terminals having different beam IDs into different groups (S240).

Thereafter, the relay base station 200 transmits the measurement information received from the plurality of mobile terminals 300 to the central base station 100 (S250).

Here, the central base station 100 may be a relay base station ID to which the plurality of mobile terminals 300 are connected and beam IDs of the relay base station to which the plurality of mobile terminals 300 are mapped, through the measurement information received through step 250. All relevant information can be obtained. That is, the central base station 100 may check which of the N beams of the plurality of mobile terminals 300 are mapped to the relay base station 200.

Thereafter, the plurality of mobile terminals 300 transmits the service request message to the relay base station 200 based on the input signal (S260).

When the service request message is received through step 260, the relay base station 200 transmits the received service request message to the central base station 100 through beamforming (S270).

If the base station 100 receives the service request message through step 270, the central base station 100 transmits information corresponding to the received service request message to the relay base station 200 through beamforming (S280).

Here, the information corresponding to the service request message may include a beam ID corresponding to the information.

When the base station 200 receives information corresponding to the service request message through beamforming from the central base station 100 through step 280, the relay base station 200 transmits the information to the plurality of mobile terminals 300 in response to the service request message. (S290)

Here, the relay base station 200 corresponds to the service request message by applying frequency division multiplexing (FDM) when the plurality of mobile terminals 300 to transmit the information on the received service request message belong to the same group. Information can be sent. Alternatively, if the plurality of mobile terminals 300 to transmit the information on the received service request message belong to different groups, the relay base station 200 may apply time division multiplexing (TDM) to provide information corresponding to the service request message. Can transmit

Hereinafter, a cluster-based beamforming process performed by each of the central base station 100, the relay base station 200, and the plurality of mobile terminals 300 will be described in detail with reference to FIGS. 3 to 6.

3 is a flowchart illustrating a process performed in a central base station in a cluster-based beamforming method according to an embodiment of the present invention.

Hereinafter, it is assumed that the plurality of mobile terminals 300 are connected to the relay base station 200, and the central base station 100 and the relay base station 200 have a fixed fixed beam set in the cell. Assume it is assumed.

Referring to FIG. 3, the central base station 100 receives measurement information through beamforming from the relay base station 200 and stores the received measurement information (S310).

Here, the measurement information may include a cell ID of the relay base station 200 and a beam ID of the relay base station 200 to which the plurality of mobile terminals 300 are mapped.

Thereafter, the central base station 100 determines whether a service request message is received from the relay base station 200 (S320).

When the service request message is received in step 320, the central base station 100 obtains information corresponding to the received service request message and transmits the obtained information to the relay base station 200 using beamforming (S330).

Here, the information corresponding to the service request message may include a beam ID corresponding to the information, and the central base station 100 may transmit the obtained information through time division multiplexing (TDM) when transmitting the obtained information to the relay base station 200. have.

Therefore, according to the cluster-based beamforming method according to an embodiment of the present invention, by applying a beamforming technology and providing a new network topology incorporating the beam-based small cell concept, the exponentially increasing data demand is increased. High speed large capacity transmission is possible.

4 is a flowchart illustrating a process performed by a relay base station in a cluster-based beamforming method according to an embodiment of the present invention, and FIG. 5 is a conceptual diagram illustrating control information transmitted and beamformed according to an embodiment of the present invention. to be.

4 and 5, the relay base station 200 transmits control information to the plurality of mobile terminals 300 using beamforming (S401).

Thereafter, the relay base station 200 determines whether measurement information corresponding to the control information is received from the plurality of mobile terminals 300 (S403).

Here, the measurement information may include a cell ID of the relay base station 200 and a beam ID of the relay base station 200.

When the measurement information is received through step 420, the relay base station 200 groups the plurality of mobile terminals based on the received measurement information (S405). That is, the relay base station 200 may cluster the terminals mapped to the same beam ID among the received measurement information and group them into the same group, or group the terminals mapped to different beam IDs into different groups. have.

The relay base station 200 transmits the measurement information received from the plurality of mobile terminals 300 to the central base station 100 through beamforming (S407).

Thereafter, the relay base station 200 determines whether a service request message is received from the plurality of mobile terminals 300 (S409).

When the service request message is received from the mobile terminal 300 through step 409, the relay base station 200 transmits the received service request message to the central base station 100 using beamforming (S411).

Thereafter, the relay base station 200 receives information corresponding to the service request message transmitted from the central base station 100 (S413).

The relay base station 200 determines whether the plurality of mobile terminals 300 belong to the same group based on the information received through step 413 (S415).

Here, the information corresponding to the service request message may include the beam ID of the relay base station 200 to which the plurality of mobile terminals 300 belong.

When the plurality of mobile terminals 300 belong to the same group through step 415, the relay base station 200 transmits the received information to the plurality of mobile terminals 300 in a frequency division multiplexing manner (S417).

Alternatively, when the plurality of mobile terminals 300 belong to different groups through step 415, the relay base station 200 transmits the received information to the plurality of mobile terminals 300 in a time division multiplexing manner (S419).

Therefore, according to the cluster-based beamforming method according to an embodiment of the present invention, by applying a beamforming technology and providing a new network topology incorporating the beam-based small cell concept, the exponentially increasing data demand is increased. High speed large capacity transmission is possible.

6 is a conceptual diagram illustrating a configuration for analog beamforming according to an embodiment of the present invention.

Referring to FIG. 6, when the base station 200 receives information corresponding to the service request message from the central base station 100 through a single antenna, the relay base station 200 transmits the received information through analog or digital beamforming. Transmit to the plurality of mobile terminals 300.

Here, in order to transmit the received information to the plurality of mobile terminals 300 through analog beamforming, the relay base station 200 may have a configuration as shown in FIG. 6, and amplify the received information and amplify the received information. Information may be forwarded to the plurality of mobile terminals 300.

Alternatively, when the information corresponding to the service request is received through the plurality of antennas, the relay base station 200 decodes the received information and based on the beam index included in the received information, the plurality of mobile terminals. Send to 300.

Here, when the relay base station 200 transmits the information received from the central base station 100 to the plurality of mobile terminals 300, the plurality of mobile terminals mapped to the same beam ID of the relay base station 200 and clustered into the same group For, the information corresponding to the service request message may be transmitted by applying frequency division multiplexing (FDM). Alternatively, time division multiplexing (TDM) may be applied to a plurality of mobile terminals mapped to different beam IDs of the relay base station and clustered into different groups to transmit information corresponding to the service request message.

In addition, the number of beams that the relay base station 200 can transmit at a specific time point t ₁ is not limited. However, when the maximum transmission power of the relay base station 200 is P, the smaller the number of beams simultaneously transmitted, the more beams can be allocated to the beam. Power may increase.

Therefore, according to an embodiment of the present invention, high-speed data transmission is possible through a beam-based small cell communication environment.

7 is a flowchart illustrating a process performed in a mobile terminal in a cluster-based beamforming method according to an embodiment of the present invention.

Referring to FIG. 7, the plurality of mobile terminals 300 receives control information from the relay base station 200 (S710).

When the control information is received in step 710, the plurality of mobile terminals 300 performs measurement on the received control information (S720).

The plurality of mobile terminals 300 transmits the measurement information measured in step 720 to the relay base station 200 (S730).

Here, the measurement information may include a cell ID of the relay base station 200 and a beam ID of the relay base station 200, and then may be used when the relay base station 200 clusters.

Thereafter, the plurality of mobile terminals 300 determines whether there is a user input (S740).

When it is determined that there is a user input in step 740, the plurality of mobile terminals 300 generates a service request message based on the input and transmits the generated service request message to the relay base station 200 (S750).

Thereafter, the plurality of mobile terminals 300 receives information corresponding to the service request message from the relay base station 200 (S760).

Here, the downlink between the relay base station 200 and the plurality of mobile terminals 300 uses a beamforming technique, and the plurality of mobile terminals 300 may transmit or receive beamforming or may not perform beamforming. .

Therefore, according to the cluster-based beamforming method according to an embodiment of the present invention, by applying a beamforming technology and providing a new network topology incorporating the beam-based small cell concept, the exponentially increasing data demand is increased. High speed large capacity transmission is possible.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

100: central base station 200: relay base station
300: a plurality of mobile terminals 310, 320, 330: mobile terminal group
321, 322, 323: mobile terminal

Claims (1)

In the beamforming method performed at the base station,
Transmitting control information to the plurality of terminals;
Receiving measurement information corresponding to the control information from the plurality of terminals;
Grouping the plurality of terminals into a plurality of groups based on the received measurement information; And
And transmitting the received measurement information to a higher base station using beamforming.

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