KR102099274B1 - System and method for control of load balanced transmission in wireless communication system - Google Patents

Abstract

In a communication environment of a distributed antenna structure in which one DU (Digital Unit) controls one or more Radio Units (RUs), a load balancing control system adjacent to a transmission load of a first RU transmitting a signal for providing a service to a terminal In order to distribute and process the RUs, when a load occurs in the first RU, load distribution to a plurality of RUs adjacent to the terminal is determined, a capacity to distribute the load is calculated, and a second load to be distributed among the plurality of adjacent RUs is distributed. After determining the RU, the resource for the second RU is allocated so that the resource for the first RU to be used for the service provided to the terminal and the time axis position do not overlap. And it controls to transmit using the resources allocated to the terminal through the first RU and the second RU.

Description

System and method for control of load balanced transmission in wireless communication system in a wireless communication system having a distributed antenna structure

The present invention relates to a load balancing control system and a load balancing method in a wireless communication system with a distributed antenna structure.

2. Description of the Related Art With the spread of smartphones, wireless data traffic is exploding exponentially due to the activation of wireless multimedia services, activation of SNS (Social Networking Service), and the expansion of wireless demand such as IoT communication. Accordingly, a big data environment, which is not easy to process using the existing data transmission method, has arrived.

In order to efficiently manage radio resources in accordance with the advent of the big data environment, a radio signal processing unit (a digital signal processing unit (hereinafter referred to as DU)), which is a single baseband base station, is a plurality of antenna modules connected optically ( The use of a wireless communication system with a distributed antenna structure capable of controlling a radio unit (hereinafter referred to as 'RU') is being considered. In addition, the Cloud RAN (Cloud RAN) system that integrates and controls multiple DUs is receiving attention as an effective solution for managing large data traffic by efficiently managing radio resources.

In the DU-RU distributed antenna structure, the link transmission capacity between the DU and the RU limits the maximum transmission capacity of the RU. Therefore, in order to increase the transmission capacity that the RU can transmit to the user, it is necessary to increase the link transmission capacity between DU-RUs, which causes an increase in installation and operation costs.

If a specific RU has a high PALR (Peak to Average Loading Ratio) of a cell serving a terminal, it is necessary to maintain a high transmission capacity of the DU-RU link in preparation for the maximum load situation of the cell, thereby inefficient installation and There will be operational problems. Therefore, in order to solve this problem, it is important to lower the transmission capacity between DU-RU links by lowering the PALR, thereby reducing the cost for establishing a link between DU-RUs.

In the DU-RU distributed antenna structure, since one DU controls a plurality of RUs, load balancing can be applied more efficiently, and many studies have been conducted in relation to load balancing. In the case of load balancing through association control between DU and RU, users of a heavily loaded cell are forcibly associated with an adjacent cell with less load, so that the load of the heavily loaded cell is moved to a cell with less load. do.

In the case of such a load balancing technique, since the users of other cells that are not actually in their coverage are associated, the received signal power of users is lowered. In addition, since there is a strong interference from the cell to which the original terminal itself belongs, interference control is necessary, and there is a problem that the complexity of a cell with a large load is greatly increased.

In contrast, when the load is distributed by changing the radius of the cell by adjusting the size of the transmission power, the cell radius is changed through cell breathing, unlike load distribution through association control. This reduces the RSSI (Received Signal Strength Indication) or interference problems compared to the associated control.

However, when the transmission power of one cell is changed, since the transmission power of all adjacent cells must be controlled, a problem arises in that the transmission power of all RUs must be changed like dominoes. Therefore, once the power is controlled for load balancing, it becomes difficult to control the power again for a while, and there is a problem that it is difficult to adaptively cope with changes in the instantaneous load.

Accordingly, the present invention provides a load balancing control system and a load balancing method in a wireless communication system having a distributed antenna structure capable of adaptively coping with an instantaneous load increase.

In a communication environment of a distributed antenna structure in which one DU (Digital Unit), which is one feature of the present invention, controls one or more Radio Units (RUs) to achieve the technical problem of the present invention, a load distribution control system is connected to a terminal. A method of distributing and processing a transmission load of a first RU transmitting a signal for providing a service among adjacent RUs,

Determining a load distribution to a plurality of RUs adjacent to the terminal when a load occurs in the first RU, and calculating a capacity to distribute the load; The second RU to distribute the load among the plurality of adjacent RUs is determined, and resources for the first RU to be used for services provided to the terminal are allocated to resources for the second RU so that time axis positions do not overlap. step; And controlling to transmit to the terminal through the first RU and the second RU using the allocated resource.

The calculating the capacity to distribute the load may include: calculating the capacity to distribute the load includes receiving a service request signal including a transmission requirement from the terminal; Confirming whether the first RU is capable of transmitting a signal to provide a service to the terminal through a DU-RU link between the first RU providing a service to the terminal and a DU controlling the first RU; And when it is determined that the first RU cannot transmit a signal to the terminal through the DU-RU link, determining a load distribution to one RU among a plurality of RUs adjacent to the terminal.

The determining of load distribution to one of the RUs may further include calculating load capacity to be distributed to any one RU among a plurality of RUs adjacent to the terminal.

In the step of checking whether the signal can be transmitted, the sum of the transmission capacity used in the DU-RU link and the transmission capacity to satisfy the transmission requirements of the terminal can be transmitted to the terminal through the DU-RU link. You can check whether it is larger or smaller than the maximum transmission capacity.

If it is determined that signal transmission is possible to the terminal through the DU-RU link, calculating a resource amount required to send a signal to the terminal based on a transmission capacity for satisfying the transmission requirement of the terminal; Calculating an available resource amount of the first RU that can be transmitted to the terminal; And comparing the required resource amount with the available resource amount of the transmittable first RU.

Comparing the available resource amount of the first RU comprises: providing a service to the terminal through the first RU if the available resource amount of the transmittable first RU is greater than the required resource amount; And if the available resource amount of the transmittable first RU is less than the required resource amount, determining a load distribution to one RU among a plurality of RUs adjacent to the terminal.

The determining of load distribution to one of the RUs may further include calculating load capacity to be distributed to any one RU among a plurality of RUs adjacent to the terminal.

The step of allocating resources for the second RU comprises: allocating a first resource for the first RU to transmit a signal to the terminal through the first RU; Determining a second RU capable of signal transmission to the terminal by the calculated load capacity to be distributed among the plurality of adjacent RUs; And allocating a second resource for the second RU to a position that does not overlap the time axis with the first resource to transmit a signal to the terminal through the second RU.

After the step of allocating the second resource, including the second RU identification information indicating that there is a signal to be transmitted from the second RU to the terminal, generating a synchronization signal to be transmitted from the first RU to the terminal ; Checking whether the number of receivers of the terminal is one; And if the number of receivers of the terminal is one, controlling the synchronization signal of the second RU to be transmitted to the terminal after transmitting the signal using the first resource from the first RU to the terminal. .

In a communication environment of a distributed antenna structure in which one digital unit (DU) which is another feature of the present invention for achieving the technical problem of the present invention controls one or more radio units (RUs), the DU is included in the terminal A system for controlling load balancing of RUs that transmit signals for providing services,

A transmission capacity calculator configured to confirm whether a service can be provided to the terminal through a DU-RU link between the RU interworking with the terminal and a DU controlling the RU; and a transmission capacity of the DU-RU link; If the transmission capacity calculator determines that the terminal can provide a service to the terminal through the DU-RU link, the amount of resources required to transmit a signal to the terminal and the amount of available resources that the RU can transmit a signal to the terminal A load determining unit to determine whether load balancing is necessary for the RU based on the; If the transmission capacity calculation unit determines that it cannot provide a service to the terminal through the DU-RU link, or if the load determination unit determines that load balancing is necessary for the RU. An adjacent RU resource identification unit determining resources of other RUs adjacent to the terminal and determining an adjacent RU that handles load balancing for the RU; And a resource allocator for allocating resources of the RU to a signal to be provided to the terminal and allocating resources for the adjacent RU determined by the adjacent RU resource identification unit at a position not overlapping with the time axis position of the allocated RU resource. do.

The resource allocation unit includes a synchronization signal including identification information of the adjacent RU indicating that there is a signal to be provided from the adjacent RU to the terminal in addition to a signal provided from the RU in a synchronization signal of a signal provided by the RU to the terminal. Can generate

The resource allocation unit may control the synchronization signal of the adjacent RU to be transmitted after the resource for the RU is transmitted to the terminal.

It may include a signal transmission unit for transmitting a signal to the adjacent RU and the arbitrary RU to provide a service to the terminal based on the resources allocated by the resource allocation unit.

According to the present invention, a load that can be processed among the user's load is processed through the RU that the existing terminal is interlocked with, and the amount of the remaining load can be solved through another adjacent RU, thereby more adapting to the change in the instantaneous load. Can cope with enemies.

1 is an exemplary diagram of a wireless communication system according to an embodiment of the present invention.
2 is an exemplary view of an environment including a load balancing control system according to an embodiment of the present invention.
3 is a structural diagram of a distributed control system according to an embodiment of the present invention.
4 is a flowchart of a method for determining instantaneous load balancing according to an embodiment of the present invention.
5 is a flowchart of a method for transmitting a signal to a terminal after a load balancing technique according to an embodiment of the present invention is applied.
6 is an exemplary diagram of a data frame according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part “includes” a certain component, this means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

In this specification, a terminal is a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a user device (User) Equipment, UE, access terminal (AT), or the like, or may include all or part of functions such as a mobile terminal, a subscriber station, a mobile subscriber station, and a user device.

In this specification, the base station (Base Station, BS) is an access point (Access Point, AP), a radio access station (Radio Access Station, RAS), Node B (Node B), a base transceiver station (Base Transceiver Station, BTS), MMR ( Mobile Multihop Relay) -BS, and may include all or part of functions such as an access point, a radio access station, a Node B, a transmitting and receiving base station, and an MMR-BS.

Hereinafter, a load balancing control system and method in a wireless communication system having a distributed antenna structure according to an embodiment of the present invention will be described with reference to the drawings. Load balancing according to an embodiment of the present invention is performed in a wireless communication system environment that provides a service by transmitting a frame-by-frame signal to a user terminal.

1 is an exemplary diagram of a wireless communication system according to an embodiment of the present invention.

The wireless communication system to which the instantaneous load balancing technique is applied according to an embodiment of the present invention will be described as an example in which the load balancing technique operates between two cells for convenience of description. However, expansion to a load balancing process between multiple cells can be easily explained.

As illustrated in FIG. 1, one DU 100 may simultaneously control a plurality of RUs 200-1 and 200-2. In addition, among the plurality of RUs 200-1 and 200-2, the user terminal 300 serviced by the first RU 200-1 includes a cell of the first RU 200-1 and a second RU 200- It is assumed that the cell of 2) exists at the overlapping cell boundary and is an instantaneous user terminal having a very large transmission capacity.

The DU 100 calculates a transmission capacity that can be transmitted to the user terminal 300 for each transmission frame, and provides a resource amount required to service the user terminal 300 through the first RU 200-1. Calculate The first RU (200-1) does not have the amount of available resources as necessary for serving the user terminal (300), or exceeds the link transmission capacity between the DU (100) and the RU (200-1), the user terminal ( It is assumed that there is a case in which transmission cannot be performed as much as the signal capacity required by 300).

In this case, the DU 100 uses the resources of the second RU 200-2 having an extra resource amount among the one or more RUs adjacent to the user terminal 300 and transmits it to the user terminal 300 by the insufficient transmission capacity. By doing so, it is possible to satisfy the signal capacity required by the user terminal 300. Through this transmission process, the DU 100 may satisfy the transmission requirement of the user terminal 300 without increasing the maximum transmission amount of the first RU 200-1.

In addition, the DU 100 controls the first RU 200-1 and the second RU 200-2 to allocate resources in the same data frame section. At this time, the resource for the second RU (200-2) is controlled so that the resource is allocated to a position that does not overlap on the time axis from the location where the resource for the first RU (200-1) is allocated.

In addition, the first RU 200-1 and the second RU 200-2 each provide a service to the user terminal 300 by using a frame to which resources are allocated. To this end, the user terminal 300 may transmit and receive signals from adjacent RUs 200-1 and 200-2 using a plurality of independent transceivers.

That is, in the embodiment illustrated in FIG. 1, the user terminal 300 transmits and receives signals by connecting to the first RU 200-1 and the second RU 200-2 using two independent transceivers, respectively. can do. However, this method may be required to increase the cost of the user terminal 300.

Therefore, in the embodiment of the present invention, when the user terminal 300 is provided with one transceiver, and when receiving a signal from a plurality of RU (200-1, 200-2) in the same data frame section using one transceiver Consider.

In other words, in the above embodiment, the DU 100 is configured so that the resource maps of the first RU 200-1 and the second RU 200-2 do not overlap each other on the time axis. Signals are transmitted by allocating necessary resources for signal transmission. The resource map will be described first with reference to FIG. 6.

6 is an exemplary diagram of a data frame according to an embodiment of the present invention.

As illustrated in FIG. 6, the user terminal 300 receives the signal from the first RU 200-1 first, and then transmits the second RU 200-2 from the second RU 200-2. After receiving the synchronization signal (preamble), the signal is transmitted using a commercial transmission method.

At this time, when operating in a load balancing mode between cells, unlike in the normal case, that is, unlike a case of transmitting a synchronization signal (preamble) only at the beginning of a data frame for data frame synchronization, the load balancing mode proposed in the embodiment of the present invention In the second RU 200-2 participating in load balancing, the synchronization signal is sent again before the data signal is transmitted to the user terminal 300 for synchronization with the user terminal 300.

The user terminal 300 receiving the signal in the load balancing mode first receives the signal from the first RU 200-1, and then, when the signal transmission from the first RU 200-1 is completed, the second RU 200 -2) receives the synchronization signal transmitted from. Then, a signal is transmitted from the second RU 200-2.

In this environment, a system for controlling load balancing will be described with reference to FIG. 2. In an embodiment of the present invention, a system for controlling load balancing is included in the DU 100, and the RU 200 performs signal transmission through load balancing based on the control signal of the DU 100 as an example. However, it is not necessarily limited to this.

2 is an exemplary view of an environment including a load balancing control system according to an embodiment of the present invention.

As shown in FIG. 2, in the load balancing control system 100, the DU 100 controls a total of KRU RUs 200-1 and 200-2, and each RU 200-1 and 200-2 is It is assumed that NT antennas 109 and 110 are used. When the RUs 200-1 and 200-2 form signal signals to be transmitted using the signal generators 201 and 202, respectively, and generate signals to be transmitted through the beam formers 203 and 204, where the first RU ( 200-1) The received signal of the user terminal 300 receiving the service may be represented as follows.

인 가산성 백색 가우시안 잡음(adaptive white Gaussian noise)을 나타낸다.Here, α _{i, k} denotes a path loss from the first RU 200-1 to the user terminal 300, k, and h _{i , k} denotes a user terminal (from the first RU 200-1). (1 × N _T ) channel k to 300). v _{i , k} and x _{i , k} denote (N _T × 1) beam weight vectors and transmission signals transmitted by RU, respectively, and w _j and s _i are transmitted by adjacent second RUs 200-2 ( N _T × 1) means a beam weight vector and a transmission signal. And n _k has mean 0 and variance

Phosphorus represents an adaptive white Gaussian noise.

The structure of the distributed control system 100 for controlling load balancing of the RU in such an environment will be described with reference to FIG. 3.

3 is a structural diagram of a distributed control system according to an embodiment of the present invention.

As shown in FIG. 3, the distributed control system 100 includes a transmission capacity calculation unit 110, a load determination unit 120, an adjacent RU resource checking unit 130, a resource allocation unit 140, and a signal transmission unit ( 150).

When the transmission capacity calculator 110 is requested to provide a service from the user terminal 300, through the link between the RU forming the cell in which the user terminal 300 is located and the DU controlling the RU (DU-RU link) It is checked whether the user terminal 300 can provide the requested service. In the exemplary embodiment of the present invention, cases in which load balancing is required can be divided into two types, one is a case where the capacity of the DU-RU link is insufficient, and the other is a sufficient capacity of the DU-RU link but the amount of transmission resource of the RU This is the case.

If the transmission capacity of the DU-RU link is not sufficient to provide the service to the user terminal 300 through the DU-RU link, the adjacent RU resource checker 130 determines the capacity to distribute the load to the adjacent RUs. request. At this time, the service provision request signal transmitted from the user terminal 300 includes transmission request information.

When the load determination unit 120 determines that the transmission capacity of the DU-RU link is sufficient to transmit the service to the user terminal 300 through the DU-RU link based on the calculation of the transmission capacity calculation unit 110, the user terminal ( It is determined whether or not the resource amount of the RU providing the service to 300) is insufficient to provide the service. To this end, the load determination unit 120 calculates the frequency efficiency and total transmission capacity that can be transmitted to the user terminal 300, and based on this, determines whether a load occurs when the corresponding RU provides a service to the user terminal 300. do.

If the amount of available resources that can be used when the RU provides a service to the user terminal 300 is smaller than the amount of resources required to transmit a signal to the user terminal 300, only the corresponding RU requires the user terminal 300 If resources cannot be provided as much as the signal capacity, it is determined that a load balancing request is generated in the corresponding RU.

The adjacent RU resource checking unit 130 requests load balancing from the transmission capacity calculating unit 110 due to insufficient DU-RU link capacity, or the load determining unit 120 load balancing request due to insufficient resource amount of the RU. When this occurs, resources of one or more other adjacent RUs adjacent to the user terminal 300 are identified. And based on the amount of available resources that can be provided to the user terminal 300 of the adjacent neighboring RUs, an RU to provide a service together with an RU (hereinafter referred to as a first RU) that already provides a service to the user terminal 300 Hereinafter, referred to as a second RU) is determined. Here, when one or more adjacent RUs are located in a boundary area of a cell formed by each RU, the user terminal 300 identifies the RUs forming the cell as one or more adjacent RUs.

The resource allocation unit 140 may provide the service to the user terminal 300 through the second RU determined by the adjacent RU resource identification unit 130 and the first RU that is already providing the service to the user terminal 300. Resource allocation to a data frame. At this time, as shown in FIG. 6, resources are overlapped in time in each RU data frame so as not to be allocated.

Then, the resource allocation unit 140 provides the allocated resource allocation information to each RU, and generates a synchronization signal to provide a service to the user terminal 300 at the corresponding location. Here, the synchronization signal for the first RU is generated by including identification information of the second RU. This is to enable the user terminal 300 to check the synchronization signal transmitted from the first RU, so that the RU providing the service to the user terminal 300 itself has a second RU in addition to the first RU. In addition, the resource allocation unit 140 sets a synchronization signal for the second RU to be transmitted after all data frames transmitted from the first RU to the user terminal 300 are transmitted.

When the resource allocation unit 140 allocates resources and generates a synchronization signal, the signal transmission unit 150 transmits the corresponding signals to the first RU and the second RU selected as targets for providing the service to the user terminal 300. . At this time, the signal transmission unit 150 may determine whether there is one or more receivers of the user terminal 300, and determine the beam weight when there is one receiver.

In the embodiment of the present invention, a case in which the receiver of the user terminal 300 is one will be described as an example, but considering the case where the number of receivers of the user terminal 300 is plural, the signal transmitter 150 determines the beam weight. . Determining the beam weight is to prevent interference from reaching other user terminals using resources allocated to transmit a signal to the user terminal 300, and the method for determining the beam weight may be provided in various ways. In the embodiment of the invention, it is not limited to any one method.

A method for instantaneously determining load distribution through the distribution control system 100 described above will be described with reference to FIG. 4. In an embodiment of the present invention, the RU for which the user terminal 300 is requested for the initial service is referred to as a first RU 200-1, adjacent to the first RU 200-1, and provided to the user terminal 300. The RU to provide the service together with the 1 RU 200-1 will be described as a second RU 200-2. In the embodiment of the present invention, when a load is generated in the first RU 200-1, the second RU 200-2 is selected as an example, but a load is also generated in the second RU 200-2. In this case, one or more other RUs may be simultaneously selected to provide a service to the user terminal 300.

4 is a flowchart of a method for determining instantaneous load balancing according to an embodiment of the present invention.

As illustrated in FIG. 4, the transmission capacity calculation unit 110 of the DU 100, that is, the distributed control system 100, receives a service provision request signal including transmission requirements of the user terminal 300 from an upper layer Then, the transmission capacity to be provided to the user terminal 300 is calculated (S100). Here, the upper layer is a known item, and detailed description is omitted in the embodiment of the present invention.

The transmission capacity calculation unit 110, which has calculated the transmission capacity by receiving the service provision request signal through step S100, checks whether the transmission capacity for the service to be provided to the user terminal 300 can be transmitted through the DU-RU link. . That is, when providing the service to the user terminal 300, the capacity of the DU-RU link is checked in order to confirm whether the service can be sufficiently provided through the DU-RU link. S110).

는 사용자 단말(300)이 요구하는 전송 용량을 나타낸다. 사용자 단말(300)이 요구하는 전송 용량은 S100 단계에서 수신한 서비스 제공 요청 신호에 포함된 전송 요구 사항을 통해 확인할 수 있다.Here, C _{T and max} denote the maximum transmission capacity that can be transmitted on the DU-RU link, and C _T denotes the transmission capacity currently used on the DU-RU link,

Indicates a transmission capacity required by the user terminal 300. The transmission capacity required by the user terminal 300 may be confirmed through transmission requirements included in the service provision request signal received in step S100.

The transmission capacity calculator 110 determines load distribution to neighboring RUs when it is determined that the capacity of the DU-RU link is insufficient to provide a service to the user terminal 300 through the calculation of Equation (2). (S170). However, if it is determined that the capacity of the DU-RU link is sufficient, the load determination unit 120 checks whether the resource amount of the first RU 200-1 to which the user terminal 300 is connected is insufficient, the user The amount of resources that can be transmitted to the terminal is calculated (S120).

In addition, the first RU 200-1 to which the user terminal 300 is currently receiving a service calculates the amount of resources required to provide the service to the user terminal 300 (S130). In an embodiment of the present invention, in order to calculate the required resource amount, the first RU 200-1 estimates the frequency efficiency of transmitting a signal to the user terminal 300.

Here, the transmission frequency efficiency can be predicted using user channel information such as a signal to interference plus noise ratio (hereinafter referred to as 'SINR') of the user terminal 300 that can be estimated using Equation 3 below. Can be.

는 제1 RU(200-1)와 사용자 단말(300) 사이의 채널의 순시적인 SINR을 나타내며,

는 제1 RU(200-1)와 사용자 단말(300) 사이의 채널의 평균적인 SINR이고,

는 제2 RU(200-2)와 사용자 단말(300) 사이의 채널의 평균적인 SINR을 나타낸다. here

Denotes an instantaneous SINR of a channel between the first RU 200-1 and the user terminal 300,

Is the average SINR of the channel between the first RU 200-1 and the user terminal 300,

Denotes an average SINR of a channel between the second RU 200-2 and the user terminal 300.

When a signal is transmitted to the user terminal 300 using a modulation coding set (hereinafter referred to as 'MCS'), the transmission frequency efficiency is expressed by Equation 4 below through the channel SINR of the user estimated through Equation 3: Can be predicted as

Here, f _MCS (·) denotes an MCS function. That is, f _MCS (·) is a function for predicting the transmission frequency efficiency of transmitting a signal to the user terminal 300 through the MCS determined according to the SINR estimated through Equation (3).

When the load determination unit 120 predicts the transmission frequency efficiency to the user terminal 300 through Equation 3 and Equation 4, the load determination unit 120 may include the first RU 200-1 to the user terminal 300. You can calculate the amount of resources needed to deliver the signal. The amount of resources required for the first RU 200-1 to transmit a signal to the user terminal 300 may be calculated through Equation (5).

Here, R _{k , i} denotes a transmission frequency efficiency in which the first RU 200-1 transmits a signal to the user terminal 300.

을 비교한다(S140). S140 단계를 통한 비교 결과, 사용자의 요구 사항을 만족시키기 위해 필요한 자원 양이 제1 RU(200-1)의 가용 자원 양보다 작은 경우, 부하를 분산하지 않고 제1 RU(200-1) 만을 사용하여 신호를 사용자 단말(300)에 전송하도록 자원 할당부(140)에 자원 할당을 요청한다(S150).The load determination unit 120 is capable of transmitting a signal to the user terminal 300 calculated through step S120, the amount of resources B _{k , i} and the required resource amount of the first RU 200-2 calculated through step S130.

Compare (S140). As a result of the comparison through step S140, when the amount of resources required to satisfy the user's requirements is less than the amount of available resources of the first RU 200-1, only the first RU 200-1 is used without distributing the load. To request a resource allocation to the resource allocation unit 140 to transmit the signal to the user terminal 300 (S150).

However, when the amount of resources to satisfy the user's requirements is greater than the amount of available resources of the first RU 200-1, the load determination unit 120 determines the load distribution by applying an instantaneous load balancing technique ( S160).

Then, the adjacent RU resource checking unit 130 determines the transmission capacity ΔC _k for distributing the load according to the determination in steps S160 and S170. In step S170, since the transmission capacity of the DU-RU link is insufficient according to the determination of step S110, load balancing is determined. Therefore, it is necessary to distribute the capacity obtained through calculation of the following equation (6) to adjacent RUs.

On the other hand, if it is determined in step S140 that the load distribution is determined because the amount of available resources of the first RU 200-1 is insufficient, the adjacent RU resource checking unit 130 uses the capacity calculated through Equation 7 below. 300) is determined to be distributed to the adjacent RU.

Here, C _{k , i} means a transmission capacity that can be transmitted to the user terminal 300 using the amount of available resources of the first RU 200-1, and is predicted as B _{k , i} × R _{k , i} , B _{k , i} means the amount of resources available to the user terminal 300.

In the wireless communication system to which the instantaneous load balancing technique is applied according to the embodiment of the present invention through the procedure described above, when the application of the load balancing technique is determined through the process of FIG. 4, the user terminal 300 is installed with one transceiver. The process of transmitting the signal will be described with reference to FIG. 5.

5 is a flowchart of a method for transmitting a signal to a terminal after a load balancing technique according to an embodiment of the present invention is applied.

As shown in FIG. 5, when the distributed control system 100 determines the capacity of the load to be distributed to the adjacent RU 200-2 through the process of FIG. 4 (S200), the resource allocation unit 140 is adjacent to the RU Resources are allocated to transmit the remaining capacity other than the transmission capacity to be distributed to (200-2) to the user terminal 300 through the first RU (200-1) (S210). After the resource allocation unit 140 allocates resources to the first RU 200-1 through step S210, the adjacent RU resource identification unit 130 load balance calculated through step S160 or step S170 of FIG. 3. The RU to be transmitted to the user terminal 300 is determined by the determined capacity (S220). Here, the method for distributing the load is as shown in Equation 8 below.

Here, B _l represents the amount of available resources of the second RU 200-2, which is an adjacent RU, and R _{k , i} is the transmission frequency efficiency when the second RU 200-2 transmits a signal to the user terminal 300. It can be predicted using Equation (4).

That is, the adjacent RU resource checking unit 130 not only has the transmission capacity of the DU-RU link capable of transmitting the transmission capacity calculated by Equation 6 to the user terminal 300, but also transmits the corresponding transmission capacity. Among the one or more adjacent RUs adjacent to the user terminal 300 having the resource block, the RU having the largest free resource is selected as the second RU 200-2. If it is not possible to transmit a signal to the user terminal 300 through one adjacent RU, signals may be transmitted using a plurality of adjacent RUs. Then, the RU capable of being transmitted to the user terminal 300 by the transmission capacity calculated through Equation 7 is selected as the second RU 200-2.

The adjacent RU resource checking unit 130 calculates in step S160 or step S170 in order for the second RU 200-2 to distribute the load of the first RU 200-1 to provide service to the user terminal 300. It operates repeatedly from step S200 to step S220 until adjacent RUs capable of transmitting a transmission capacity requiring one load balancing instead are identified. At the same time, when allocating resources in step S210, the resource allocating unit 140 allocates resources that do not overlap with resources allocated by the previously selected first RU 200-1.

When the procedure up to step S220 is completed, the signal transmission unit 150 checks whether the user terminal 300 has a plurality of receivers or only one receiver (S230). If there is a plurality of receivers, the user terminal 300 may receive signals simultaneously transmitted from the first RU 200-1 and the second RU 200-2. At this time, when transmitting a signal to another user terminal using the resources allocated to provide a service to the user terminal 300 in the second RU 200-2 under load distribution, interference with the user terminal 300 The beam weight is formed so as not to reach (S250). Then, the signal transmission unit 150 transmits a signal to the user terminal in each allocated resource (S260).

However, if the signal transmission unit 150 confirms in step S230 that the user terminal 300 has one receiver, the user terminal 300 is the first RU (200-1) and the second RU (200-2) ), To control the transmission of separate synchronization signals for each of the first RU 200-1 and the second RU 200-2 (S240). To this end, the resource allocation unit 140 includes the identification information of the second RU (200-2) to generate a synchronization signal transmitted to the user terminal 300 through the first RU (200-1).

This means that the user terminal 300 that has received the signal transmitted through the first RU 200-1 may transmit the signal transmitted to itself in the second RU 200-2 in addition to the first RU 200-1. This is to inform you in advance. If the service is provided to the user terminal 300 through another RU in addition to the second RU 200-2, a synchronization signal is generated including all identification information of the corresponding RUs.

For example, when the load is distributed through two RUs 200-1 and 200-2 as shown in FIG. 6, the signal transmission unit 150 is a synchronization signal transmitted in a data frame of the first RU 200-1. In the second RU (200-2) is transmitted to include information indicating that there is a synchronization signal to be transmitted to the user terminal (300). Accordingly, the user terminal 300 receiving signals from multiple RUs can sequentially synchronize the synchronization of the signals transmitted by the RUs 200-1 and 200-2 by using the synchronization signals, and thus can receive the signals. .

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (14)

In a communication environment of a distributed antenna structure in which a single DU (Digital Unit) controls a plurality of Radio Units (RUs), a load distribution control system implemented in the one DU transmits a signal for providing a service to a terminal. A method for distributing and processing a transmission load of 1 RU among adjacent RUs,
Checking whether a load is generated in the first RU based on a transmission capacity of a DU-first RU link formed between the one DU and the first RU and a resource amount of the first RU,
Determining a load distribution of the first RU among a plurality of RUs adjacent to the terminal when a load occurs in the first RU, and calculating a capacity to distribute the load;
The second RU to distribute the load of the first RU among the plurality of adjacent RUs is determined, and time axis positions do not overlap in the same frame as the resource to be used by the first RU to provide services to the terminal. Allocating resources for the second RU; And
Controlling to transmit a service using the allocated resource to the terminal through the first RU and the second RU by transmitting a synchronization signal including the second RU identification information of the second RU to the first RU step
Load balancing method comprising a. According to claim 1,
The step of calculating the capacity to distribute the load is,
Receiving a service request signal including a transmission request from the terminal;
Confirming whether the first RU is capable of transmitting a signal to provide a service to the terminal through a DU-RU link between the first RU providing a service to the terminal and a DU controlling the first RU; And
If it is determined that the first RU is unable to transmit a signal to the terminal through the DU-RU link, determining a load distribution to one RU among a plurality of RUs adjacent to the terminal.
Load balancing method comprising a. According to claim 2,
Determining the load distribution to any one of the RU,
Calculating a load capacity to be distributed to any one RU among a plurality of RUs adjacent to the terminal
Further comprising,
The load capacity to be distributed is,

here

Is a transmission capacity to satisfy the transmission requirements of the terminal k, C _{T, max} is the maximum transmission capacity that can be transmitted to the DU-RU link, C _T is the transmission capacity currently used in the DU-RU link
Load balancing method calculated by. According to claim 2,
Checking whether the signal can be transmitted,
Check whether the sum of the transmission capacity used in the DU-RU link and the transmission capacity to satisfy the transmission requirements of the terminal is larger or smaller than the maximum transmission capacity that can be transmitted to the terminal through the DU-RU link. Load balancing method. The method of claim 4,
If it is determined that signal transmission is possible to the terminal through the DU-RU link,
Calculating the amount of transmittable resources capable of sending a signal to the terminal based on the transmission capacity to satisfy the transmission requirements of the terminal
Calculating a required resource amount of the first RU capable of being transmitted to the terminal; And
Comparing the amount of transmittable resources with the amount of required resources of the first RU
Load balancing method comprising a. The method of claim 5,
Calculating the required resource amount of the first RU,

Where R _{k , i} is the transmission frequency efficiency of the first RU for the terminal
Load balancing method to calculate through. The method of claim 5,
Comparing the amount of resources that can be transmitted and the amount of required resources of the first RU,
Providing a service to the terminal through the first RU when the available resource amount of the transmittable first RU is greater than the required resource amount; And
Determining a load distribution to one RU among a plurality of RUs adjacent to the terminal when the available resource amount of the transmittable first RU is less than the required resource amount
Load balancing method comprising a. The method of claim 7,
Determining the load distribution to any one of the RU,
Calculating a load capacity to be distributed to any one RU among a plurality of RUs adjacent to the terminal
Further comprising,
The load capacity to be distributed is,

Here, C _{k , i} is the transmission capacity that the first RU predicted to be B _ki , × R _{k , i} can transmit to the terminal k, and B _{k , i} is the amount of transmission resources available to the terminal.
Load balancing method calculated by. According to claim 1,
The step of allocating resources for the second RU,
Allocating a first resource for the first RU to transmit a signal to the terminal through the first RU;
Determining a second RU capable of signal transmission to the terminal by the calculated load capacity to be distributed among the plurality of adjacent RUs; And
In order to transmit a signal to the terminal through the second RU, allocating a second resource for the second RU to a position that does not overlap the time base with the first resource.
Load balancing method comprising a. The method of claim 9,
After the step of allocating the second resource,
Generating synchronization signals to be transmitted from the first RU to the terminal, including second RU identification information indicating that there is a signal to be transmitted from the second RU to the terminal;
Checking whether the number of receivers of the terminal is one; And
If the number of receivers of the terminal is one, controlling the synchronization signal of the second RU to be transmitted to the terminal after transmitting the signal using the first resource from the first RU to the terminal
Load balancing method comprising a. In a communication environment of a distributed antenna structure in which a single digital unit (DU) controls a plurality of radio units (RUs), any one of the plurality of RUs included in the DU and transmitting a signal for providing a service to a terminal In the system for controlling the load distribution of the target RU,
A transmission capacity calculator configured to check whether a service can be provided to the terminal through a DU-RU link between the target RU interworking with the terminal and a DU controlling the target RU; and a transmission capacity of the DU-RU link;
If it is determined that the service can be provided to the terminal through the DU-RU link, it is determined whether load balancing is required for the target RU based on the amount of resources required to transmit a signal to the terminal and the available resource amount of the target RU. Load determination unit;
If the service cannot be provided to the terminal through the DU-RU link, or if the target RU needs load balancing. An adjacent RU resource identification unit determining resources of other RUs adjacent to the terminal among the plurality of RUs to determine an adjacent RU that processes load balancing for the target RU; And
Resource allocation unit for allocating resources of the target RU to the signal to be provided to the terminal, and allocating resources for the adjacent RU at a position that does not overlap the time axis position of the assigned target RU resource
Load balancing control system comprising a. The method of claim 11,
The resource allocation unit includes identification information of the adjacent RU indicating that there is a signal to be provided from the adjacent RU to the terminal in addition to a signal provided from the target RU in a synchronization signal of a signal provided by the target RU to the terminal. Load balancing control system that generates synchronous signals. The method of claim 12,
The resource allocation unit is a load balancing control system for controlling the synchronization signal of the adjacent RU is transmitted after the resource for the target RU is transmitted to the terminal. The method of claim 11,
Signal transmission unit for transmitting a signal to the neighbor RU and the target RU to provide a service to the terminal based on the resources allocated by the resource allocation unit
Load balancing control system comprising a.

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