KR101286586B1 - Hybrid communication network system based on Beam Division Multiple Access for efficient resource assignment and providing method thereof - Google Patents

Abstract

Disclosed are a BDMA based hybrid communication network system for efficient resource allocation, and a method of providing the same. The BDMA-based hybrid communication network system for efficient resource allocation may include at least the beam allocator of the base station for allocating beams of each of a base station and at least one repeater included in the BDMA-based hybrid communication network system. Compute the beam allocator of the base station to maximize the capacity of the base station without considering the interference of one repeater and the base station, and for the beam allocator of any one of the at least one repeater, The beam allocator of the repeater may be calculated based on the beam allocator.

Description

Hybrid communication network system based on Beam Division Multiple Access for efficient resource assignment and providing method

The present invention provides a frame structure and efficient resource allocation for solving interference problems occurring in a hybrid network environment in which a cellular division (BDMA) -based cellular network and an ad hoc network are mixed. The present invention relates to a hybrid communication network system that can be performed and a method of providing the same.

In the hybrid communication network, various methods for solving the interference problem of the infrastructure-based cellular network and the ad hoc network have been studied. One way to reduce interference is to allocate resources (eg, frequency, time slots, etc.) so that interference does not occur.

In this case, when using different resources, the spectral efficiency is reduced, and when using the same resources, interference problems occur.

That is, when the cellular network and the ad hoc network use the same resources in the hybrid communication network, high spectral efficiency can be achieved but interference problems may occur. Therefore, if the interference problem is not solved efficiently, the spectral efficiency of the entire hybrid communication network is reduced.

In the existing IEEE 802.16j, a frame structure and a resource allocation method using the same are proposed in consideration of an interference problem in a repeater-based cellular network. However, such a conventional technology does not consider a hybrid communication network environment in which a cellular network and an ad hoc network are mixed, and thus there is a problem in that it is difficult to apply the hybrid communication network directly. In addition, in the case of the hybrid communication network that performs the BDMA (Beam Division Multiple Access) communication, which is being studied with the fifth generation communication technology, the interference environment according to the communication characteristics is different from that of the traditional cellular network. There is a problem that is difficult to apply as it is.

Accordingly, in the hybrid communication network using the BDMA communication, a communication frame structure capable of suppressing interference and a hybrid communication network system capable of efficiently allocating resources (for example, beam allocation) in the frame structure. And a method of providing the same.

Accordingly, the technical problem to be achieved by the present invention is a frame structure that can increase the spectral efficiency in the entire hybrid communication network system by suppressing interference in a BDMA-based hybrid communication network environment and efficient when performing communication using the frame structure. It is to provide a resource allocation method.

In the BDMA-based hybrid communication network system for efficient resource allocation for solving the technical problem, a beam allocator of the base station for allocating beams of each of the base station and at least one repeater included in the BDMA-based hybrid communication network system. ), Calculate the beam allocator of the base station to maximize the capacity of the base station without considering the interference of the at least one repeater and the base station, and to the beam allocator of any one of the at least one repeater For example, the beam allocator of the repeater may be calculated based on the calculated base station beam allocator.

The BDMA-based hybrid network system is configured between the base station and a specific user connected to the base station to calculate the base station beam allocator that maximizes the capacity of the base station without considering interference of the at least one repeater and the base station. When one link is formed, the beam allocator of the base station may be calculated by calculating interference received by other second links formed by the base station.

Meanwhile, in the BDMA-based hybrid communication network system, when a third link is formed between the repeater and a specific user connected to the repeater to calculate the beam allocator of the repeater based on the calculated beam allocator of the base station. And calculating the interference received by the third link by the base station link according to the beam allocator of the base station and the interference received by the third link by the other fourth links of the repeater and based on the operation result. The beam allocator may be calculated.

The method for providing a BDMA-based hybrid communication network system for solving the technical problem includes the at least one repeater and the base station for a beam allocator of a base station included in the BDMA-based hybrid communication network system. Calculating a beam allocator of the base station to maximize the capacity of the base station without considering interference of the base station; and at least one repeater of the at least one repeater included in the BDMA based hybrid network system Calculating, for the beam allocator, the beam allocator of the repeater based on the calculated beam allocator of the base station.

Computing the beam allocator of the base station includes: when the first link is formed between the base station and a specific user connected to the base station, the first link is subjected to interference received by other second links formed by the base station. Computing the beam allocator of the base station based on the operation and the calculation result.

The calculating of the beam allocator of the repeater may include: when the third link is formed between the repeater and a specific user connected to the repeater, the third link is received by the base station link according to the beam allocator of the base station; Computing the interference received by the third link by the other fourth links of the repeater and calculating the beam allocator of the repeater based on the calculation result. The method for providing a BDMA based hybrid communication network system may be stored in a computer readable recording medium having recorded thereon a program for performing the method of claim 10.

Therefore, according to the hybrid communication network system and the method of providing the same according to an embodiment of the present invention, in consideration of the characteristics of the ad hoc network which can exist and operate in a distributed manner, the hybrid communication network system and the method of providing the hybrid communication network system according to the embodiment of the present invention are distinguished in time from the sub-frame performing cellular communication on a unit frame. By separately assigning the ad hoc subframes, and performing only the ad hoc communication in the ad hoc subframes, there is an effect of preventing interference between at least the cellular network and the ad hoc network.

In addition, the cellular network defines a frame structure in consideration of an environment in which a repeater exists, and obtains satisfactory communication efficiency while significantly reducing computation and load for resource allocation by using a heuristic resource allocation method on the defined frame structure. It can be effective.

BRIEF DESCRIPTION OF THE DRAWINGS A brief description of each drawing is provided to more fully understand the drawings recited in the description of the invention.
1 shows a schematic structure of a hybrid communication network according to an embodiment of the present invention.
2 to 4 are schematic diagrams illustrating an environment in which interference may occur in a hybrid communication network according to an exemplary embodiment of the present invention.
5 illustrates a frame structure used by a hybrid communication network system according to an embodiment of the present invention.
6 to 8 are diagrams for describing a method of performing a communication by a hybrid communication network system according to the frame structure shown in FIG. 5.
9 is a diagram schematically illustrating an optimal resource allocation method for a BDMA based hybrid communication network system according to an exemplary embodiment of the present invention.
FIG. 10 is a diagram schematically illustrating a heuristic resource allocation method in a BDMA based hybrid communication network system according to an embodiment of the present invention.
11 to 14 are diagrams showing simulation results for explaining performance of communication efficiency according to a resource allocation method of a BDMA based hybrid communication network system according to an exemplary embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Also, in this specification, when any one element 'transmits' data to another element, the element may transmit the data directly to the other element, or may be transmitted through at least one other element And may transmit the data to the other component.

Conversely, when one element 'directly transmits' data to another element, it means that the data is transmitted to the other element without passing through another element in the element.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

1 shows a schematic structure of a hybrid communication network according to an embodiment of the present invention.

Referring to FIG. 1, a hybrid communication network according to an exemplary embodiment of the present invention may be a communication network in which a cellular network and an ad hoc network coexist as shown in FIG. 1.

The cellular network may directly communicate with a base station (BS) and a mobile station (MS) using an existing cellular network infrastructure, or may perform multi-hop communication through a relay station (RS). .

The ad hoc network may perform direct communication between an MS (eg, 11) and another MS (eg, 12) or multi-hop communication through a predetermined gateway terminal (eg, 10). The ad hoc network may provide, for example, machine to machine (M2M) communication, peer to peer (P2P) communication, or short-range communication service.

In addition, the MS (eg, 11 or 12) may be provided with cellular network services through a gateway terminal (eg, 10) connected with the cellular network.

In addition, when the BS and the MS communicate with each other through RS in the cellular network, wireless backhaul communication may be performed between the BS, the RS, and the RS and the MS.

The communication between the BS and the MS, the communication between the BS and the RS, the communication between the RS and the MS, and the communication between the MS and the MS may perform communication in a bee division multiple access (BDMA) scheme.

The BDMA method may mean a communication method capable of increasing system capacity by performing communication by efficiently splitting not only frequency / time resources but also spatial resources by performing communication through beam forming. Such BDMA communication has been disclosed in the Republic of Korea Patent (10-0945880, "beam splitting multiple access system and method in a mobile communication system") filed by the applicant and registered as a reference herein.

When the hybrid communication network system according to the embodiment of the present invention uses the BDMA scheme to communicate, the directional signal is transmitted through beamforming instead of omni-directional signals as in the conventional cellular network. The interference environment is different from that of a cellular network.

Accordingly, the interference environment in the hybrid communication network in which the cellular network and the ad hoc network are mixed in the communication environment using the BDMA method is as shown in FIGS. 2 to 4.

2 to 4 are schematic diagrams illustrating an environment in which interference may occur in a hybrid communication network according to an exemplary embodiment of the present invention.

FIG. 2 illustrates an interference environment between cellular networks. When there is a terminal receiving a service from a repeater RS in a beam direction formed by the base station BS as shown in FIG. 2A, the BS performs a repeater RS. ) Can greatly interfere. On the contrary, when the terminal receiving the service from the base station BS exists in the beam direction formed by the repeater RS as shown in FIG. 2B, the repeater RS may interfere with the base station BS. have. In addition, as shown in FIG. 2C, even when the distance between the two repeaters RS is close, there may be interference between the two repeaters.

Meanwhile, FIG. 3 schematically illustrates a case in which interference between a cellular network and an ad hoc network occurs. As illustrated in FIG. 3A, a terminal MS (eg, located in a beam direction formed by a base station BS and / or a repeater RS) may be used. , 20, 21 may be subjected to ad hoc communication, the terminal (eg, 20, 21) may receive a large interference from the cellular network. In addition, as illustrated in FIG. 3B, when a terminal (eg, 31, 32) located in a beam direction formed by a predetermined terminal (eg, 30) is communicating with a cellular network, the terminal (eg, 31, 32 may be subject to significant interference from the ad hoc network.

In addition, FIG. 4 schematically illustrates a case where interference between ad hoc networks occurs. As shown in FIG. 4, a terminal (eg, 41) located in a beam direction formed by a specific terminal (eg, 40) is different from another terminal. Interference may occur when ad hoc communication is performed with (eg, 42).

Therefore, there is a need for a communication method, that is, a frame structure that can effectively remove such interference. In particular, the present invention provides a technical idea that can effectively prevent the interference between the cellular network and the ad hoc network as shown in FIG. When the interference between the cellular network and the ad hoc network is prevented according to the technical idea of the present invention, the interference between the cellular network or the interference between the ad hoc network may be efficiently allocated by using a predetermined method (eg, a beam resource). Interference may be reduced. Therefore, in the present invention, the technical idea that can prevent the interference between the cellular network and the ad hoc network will be presented first.

5 illustrates a frame structure used by a hybrid communication network system according to an embodiment of the present invention.

Referring to FIG. 5, a hybrid communication network system according to an exemplary embodiment of the present invention may perform communication in synchronization with a frame structure as shown in FIG. 5.

As shown in FIG. 5, the frame structure includes a cellular subframe and an ad hoc subframe. The cellular subframe and the ad hoc subframe may be implemented to use different time resources. That is, in the frame structure of FIG. 5, the x-axis may represent a time domain. In the time domain corresponding to the cellular subframe, the hybrid communication network system according to an embodiment of the present invention performs cellular communication and corresponds to an ad hoc subframe. In the time domain, the hybrid communication network system may be implemented to perform ad hoc communication. The hybrid communication network system may be implemented not to perform ad hoc communication in the time domain for performing cellular communication, and may be implemented not to perform cellular communication in the time domain for performing ad hoc communication. As shown in FIG. 5, in the frame structure according to the spirit of the present invention, a subframe for cellular communication and a subframe for ad hoc communication are exclusively configured in the time domain, thereby preventing interference between at least the cellular network and the ad hoc network. It can be implemented to prevent.

Although the ad hoc subframe is shown in FIG. 5 as being located behind the cellular subframe in the time domain, the ad hoc subframe may be positioned before the cellular subframe. According to an embodiment of the present invention, the present invention may be located between the cellular subframes (eg, between the cellular downlink subframe and the cellular uplink subframe), and may be located later in time than the frame header FH. It may be possible.

Meanwhile, the cellular subframe may be configured to include a cellular downlink (DL) subframe and an uplink (UL) subframe.

In the cellular downlink and uplink subframes, the base station and the repeater may be defined to reuse the same resource in consideration of the characteristics of the BDMA technology.

The cellular downlink subframe may include a general downlink subframe and a backhaul downlink subframe.

In the general downlink subframe, the base station BS and the repeater RS included in the hybrid communication network system may form at least one beam to the MSs connected thereto, thereby performing communication.

In this case, the relay RS operates in a BS mode, and may transmit data received from the BS to the MS in the backhaul downlink of the previous frame. That is, in the hybrid communication network system according to an embodiment of the present invention, the repeater RS may alternately perform a BS mode and a MS mode in a time domain. As illustrated in FIG. 6A, the hybrid network system performs communication in the general downlink subframe. In a situation as shown in FIG. 6A, there may be interference as described in FIG. 2. In this case, interference may be reduced by efficiently allocating a predetermined resource (eg, a beam resource).

Meanwhile, in the backhaul downlink subframe, data may be transmitted by forming a base station (BS) relay (RS) beam. In this case, the repeater RS may be switched from the base station mode to the terminal mode (MS mode). The relay RS switched to the terminal mode may receive data from the base station BS to be transmitted to the terminal MS in the general downlink of the next frame. 6B illustrates an example in which a hybrid network system performs communication in such a backhaul downlink subframe. As illustrated in FIG. 6B, in communication during backhaul downlink, interference may occur according to the position of the repeater RS, and the interference may be prevented by distributing the positions of the repeater RS so that the interference does not occur.

The cellular uplink subframe may include a backhaul uplink subframe and a general uplink subframe as shown in FIG. 5.

In the backhaul uplink subframe, the repeater RS may form a beam to the base station BS to transmit data to the base station BS. In this case, the relay RS operates in the terminal mode and may transmit data received from the terminal MS to the base station BS in the general uplink subframe of the previous frame. An example of the hybrid network system performing communication in such a backhaul uplink subframe is illustrated in FIG. 7A. As shown in FIG. 7A, interference may occur according to the position of the repeater RS even in communication during the backhaul uplink, and interference may be prevented by distributing the positions of the repeater RS so that no interference occurs.

In the general uplink subframe, the terminal MS may transmit data by forming a beam to the base station BS or the repeater RS to which the terminal MS is connected. In this case, the relay RS may switch from the terminal mode to the base station mode and receive data from the terminal MS to be transmitted to the base station BS in the backhaul uplink of the next frame. FIG. 7B illustrates an example in which a hybrid network system performs communication in such a general uplink subframe. As shown in FIG. 7B, the interference as described with reference to FIG. 2 may also occur in communication during general uplink. In this case, the interference may be prevented or suppressed by a predetermined resource allocation rule.

Referring back to FIG. 5, the frame header FH may include a frame preamble indicating the start of a frame and control and schedule information. In addition, the backhaul frame header FH ′ may mean frame header information transmitted to the RS, and the same information or simplified information as the frame header FH may be transmitted.

As described above, the ad hoc subframe may be used as a resource for ad hoc communication between the MSs, and cellular communication may be prohibited. That is, as the number of terminals participating in the communication increases, the ad hoc network may be distributed and distributed irregularly. In consideration of this, the cellular network and the ad hoc are allocated by assigning different resources (eg, time slots) to the cellular network and the ad hoc network. The interference between the networks can be eliminated at the source. 8 illustrates an example in which a hybrid communication system performs communication in such an ad hoc subframe. As shown in FIG. 8, since the communication during the ad hoc subframe is communication between users, it is difficult to prevent interference at the source and cope with the interference through countermeasures (for example, communication priority, etc.) when the interference occurs. Could be

Information about the frame structure as shown in FIG. 5 may be stored in a predetermined recording medium. The recording medium may be a predetermined recording medium included in the base station (BS), the repeater (RS), and / or the terminal (MS) synchronized by the frame structure.

Meanwhile, in order to reduce interference between cellular networks, an efficient resource allocation method is required as described above.

In the BDMA-based hybrid communication network system according to an embodiment of the present invention, for resource allocation, that is, beam allocation, interference between beams formed by the base station, interference between beams formed by the base station and the repeater, interference between beams formed by one repeater, And interference between beams formed by different repeaters may be taken into consideration so that the base station and the plurality of repeaters each determine how to form the beam. However, in the case of such an optimal resource allocation method, there is a problem that resource complexity, that is, too much information to consider for beam allocation, is too complicated to calculate resource allocation, as described below.

Therefore, the technical idea of the present invention discloses a resource allocation method that can be guaranteed at least a certain level of spectral efficiency of the entire system while significantly lower complexity than the optimal resource allocation method.

This technical idea will be described with reference to FIGS. 9 and 10.

FIG. 9 is a diagram schematically illustrating an optimal resource allocation scheme for a BDMA based hybrid communication network system according to an embodiment of the present invention, and FIG. 10 is a heuristic in a BDMA based hybrid communication network system according to an embodiment of the present invention. A diagram for schematically explaining a resource allocation method.

9 and 10 illustrate a resource allocation scheme, that is, a beam allocation scheme in consideration of interference between cellular networks in a cellular downlink subframe. 9 and 10 illustrate an example in which a plurality of repeaters exist within the coverage of one base station.

First, referring to FIG. 9, it is necessary to consider interference between all beams that may occur in a BDMA based hybrid communication network system in which one base station and a plurality of repeaters exist in order to maximize an optimal resource allocation method, that is, spectral efficiency. desirable. That is, for the optimal resource allocation scheme (scheme), as shown in Figure 9, the base station itself interference (i.e., interference between a plurality of beams formed by the base station), between the base station and the beams formed by each of the plurality of repeaters Interference, interference between beams formed by each of the repeaters, and repeater itself interference (i.e., interference between a plurality of beams formed by one repeater) must all be considered when allocating resources (S10). As a result of performing the calculation, the beam allocation result of each base station and the plurality of repeaters, that is, a beam allocator, may be calculated (S11).

The consideration of the interferences may mean that the interferences should be included as one parameter for calculating the beam allocator. Therefore, in order to consider all interferences as shown in FIG. 9, it may mean that a computation with a high complexity must be performed while all information for identifying the interferences is known. For example, assuming that the base station calculates beam allocators of each of the base station and the repeater, the base station is formed by each of the plurality of repeaters as well as information such as power and beam link of each of the beams formed by the base station. You need to know all the information about the link and power of one beam. Therefore, the operation is possible only when all of such various information is received in a backhaul subframe, etc., and even if the information is easily received, the complexity of the calculation itself becomes very large. Formulating this can be: Symbols used in the following formula can be defined as follows.

(중계기의 인덱스 r = 1, ..., R)Repeater R:

(Index r = 1, ..., R of repeater)

User K accessing the base station:

User K _r connected to repeater _r :

(B_max 는 기지국이 최대 형성할 수 있는 빔의 수)Base station beam B:

(B _max is the maximum number of beams that the base station can form)

(B_{r , max} 는 중계기 r이 최대 형성할 수 있는 beam의 수)Beam B _r of repeater _r :

(B _{r , max} is the maximum number of beams that can be formed by repeater r)

(타임슬롯 n에서 기지국의 beam b가 기지국에 접속한 사용자 k에 할당되면 1, 아니면 0),

where

Base station beam allocator:

(1 in timeslot n, 1 if beam b of base station is assigned to user k accessing base station)

where

(타임슬롯 n에서 중계기 r의 빔 b가 중계기에 접속한 사용자 k에 할당되면 1, 아니면 0),

where

Repeater r beam allocator:

(1 in timeslot n, or 1 if beam b of repeater r is assigned to user k connected to repeater),

where

(균등 파워(equal power) 할당시

, P_max 는 기지국의 최대 전송파워)Power allocated to the beam at the base station:

(Equal power allocation

, P _max is the maximum transmit power of the base station)

(균등 파워 할당시

, P_{r , max} 는 중계기 r의 최대 전송파워)Power allocated to the beam of repeater r:

(At the time of equal power allocation

, P _{r , max} are the maximum transmit powers of repeater r)

(

는 기지국의 빔 b의 방향과 기지국으로부터 사용자 k의 방향 사이의 각도)Channel gain of base station and user k:

(

Is the angle between the direction of beam b of the base station and the direction of user k from the base station)

(

는 중계기 r의 빔 b의 방향과 중계기 r로부터 사용자 k의 방향 사이의 각도)Channel gain of repeater r and user k:

(

Is the angle between the direction of beam b of repeater r and the direction of user k from repeater r)

Then, if the beam b of the base station is allocated to the user k of the base station in time slot n, the signal-to-interference-plus-noise of the link k of the base station (that is, the connection between the base station and the user k by the beam b) ratio) may be expressed as a function of power allocated to the beam of the base station as shown in Equation 1.

는 열 노이즈 파워(Thermal noise power)를 의미한다.here,

Means thermal noise power.

로써 기지국 자체 간섭 즉, 상기 기지국에 의해 형성되는 상기 link k 가 상기 기지국의 다른 링크로부터 받는 간섭을 의미한다.Also,

This means that the base station itself interference, that is, the interference received by the link k formed by the base station from another link of the base station.

로써 상기 링크 k 가 복수의 중계기들이 형성한 링크로부터 받는 간섭을 나타낼 수 있다.Also,

As a result, the link k may represent interference received from a link formed by a plurality of repeaters.

Then, the capacity of the link k of the base station can be expressed as a function of the power and beam allocator allocated to the beam of the base station by Equation 2 by the formula of Shannon.

Similar to the capacity of the base station, a function of the capacity of the repeater may also be derived.

When the beam b of the repeater _r is allocated to the user k _r of the repeater in time slot n, the SINR of the link k _r of the repeater r may be expressed as a function of the power allocated to the beam b of the repeater r as shown in Equation 3 below.

는 열 노이즈 파워(Thermal noise power)를 의미하며,Here too, as in Equation 1

Means thermal noise power,

는 중계기 r의 상기 링크 k_r이 기지국의 링크로부터 받는 간섭을 나타내며,

K _r is the link of the repeater r represents the received interference from the base station link,

는 중계기 r의 자체 ㄱ간섭 즉, 상기 링크 k_r 이 상기 중계기 r의 다른 링크로부터 받는 간섭 및 링크 k_r 이 다른 중계기가 형성하는 링크로부터 받는 간섭을 나타낸다.

Denotes the self-interference of the repeater r, that is, the link k _r receives from another link of the repeater r and the link k _r receives from the link formed by another repeater.

Then, the capacity of the link k _r of the repeater r can be expressed as a function of the power and beam allocator assigned to the beam of the repeater r as shown in Equation 4 by Shannon's formula. .

Then, the optimal resource allocation scheme, considering all interferences between cellular networks, is a beam allocation scheme that maximizes the capacity of the BDMA based hybrid communication network system according to an embodiment of the present invention, that is, the beam allocator and the plurality of repeaters of the base station. It may be defined as an optimization problem for calculating each beam allocator, which may be expressed as Equation 5 below.

At this time, the optimization problem of Equation 5 is the same as the equation (6).

Here, the constraint represented by Equation (6) can be divided into constraints that the base station has, namely (B.1) to (B.3) and constraints that the repeater has, that is, (R.1) to (R.3). In more detail, constraints (B.1) and (R.1) may mean that one beam of a base station or repeater should be assigned to only one user MS, respectively. Further, constraints (B.2) and (R.2) may mean that the number of beams allocated by the base station or repeater, respectively, should be less than the maximum number of beams that can be formed, and the constraints (B.3) and (R .3) may mean that the value of each beam allocator of the base station or repeater should have a value of 0 or 1.

As a result, an optimal resource allocation scheme of the BDMA based hybrid communication network system may be defined as calculating a beam allocator of each of the base station and the repeaters to maximize the sum of the capacities of the base station and the repeaters as defined in Equation 5. That is, considering the base station itself interference, the interference between the base station and the repeaters, the interference of the repeater itself, and the interference between the repeaters, each of the base station and the repeater assigned a beam to any of the users connected to it This may be defined as an optimization problem that determines whether the capacity of the BDMA-based hybrid communication network system according to the embodiment of the present invention can be maximized.

However, in order to calculate such an optimization problem, as shown in Equations 1 to 5, the base station itself interference, the interference between the base station and the repeaters, the interference of the repeater itself, and all the information necessary to calculate the interference between the repeaters Since the base station needs to know the link information and the power information for each beam, the time and resources required to receive necessary information from the repeaters are consumed. Moreover, even if all of this information can be efficiently received, there is a problem that the complexity of the operation is too great.

Accordingly, the resource allocation method according to another embodiment of the present invention can be simplified by dividing and defining the optimization problem as shown in Equation 5 in at least two stages based on heuristics, while significantly lowering the complexity of the calculation, It can provide a technical idea that can provide capacity.

According to the technical concept of the present invention, the BDMA-based hybrid network system does not simultaneously calculate the beam allocator of each of the base station and the plurality of repeaters in consideration of all possible interferences, but first calculates the beam allocator of the base station in the first step. In the second step, the technical idea of calculating the beam allocator of each of the plurality of repeaters is included.

Referring to FIG. 10, when the BDMA-based hybrid communication network system calculates the beam allocator of the base station, it is assumed that there is no interference from the repeater in order to reduce the complexity of the operation. Only considering the beam allocator of the base station can be calculated (S100, S110). As such, even when the optimal beam allocator of the base station is calculated without considering the interference with the beams formed by the repeater, the beam allocation of the repeater may be allocated using the beam allocation result of the base station. As a result, the degradation of overall system performance may not be significant. In addition, since it is not necessary to consider the interference with the beams formed by the repeaters, since the information necessary for the calculation of the interference is not received from the repeater, the calculation efficiency of the beam allocator of the base station may be remarkably high.

When considering only the self-interference of the base station, the calculation of the beam allocator of the base station may be defined as an optimization problem as shown in Equation (7).

Equation 7 may have the same constraints as Equation 8.

Since it is assumed that there is no interference received by the base station from the repeater, the SINR of the predetermined link k formed by the base station may be defined as shown in Equation (9).

일 수 있다. 하지만, 수학식 9에는 수학식 1과 달리 다른 중계기로부터의 간섭에 대한 텀(term)이 분모에 포함되어 있지 않음을 알 수 있다.Here, the interference that the link k receives from another link is as described in Equation 1

Lt; / RTI > However, in Equation 9, unlike Equation 1, a term for interference from another repeater is not included in the denominator.

Then, the capacity of the link k can be expressed as in Equation 10.

Then, the beam allocator of the base station in the heuristic resource allocation scheme according to the embodiment of the present invention can be obtained as shown in Equation (11).

이고

이다.here,

ego

to be.

When the beam allocator of the base station is obtained as described above, the BDMA-based hybrid communication network system may calculate the beam allocator of the repeater in the second step. After the base station calculates the beam allocator of the repeater, the information may be transmitted to the repeater, or the repeater may directly calculate the information after receiving the information about the beam allocator of the base station.

In the BDMA-based hybrid communication network system according to an exemplary embodiment of the present invention, it is assumed that one relay r among a plurality of repeaters does not have interference from another repeater, and the relay r assumes that only interference by beams formed by a base station exists. The beam allocator may be calculated (S120 and S130).

The resource allocation method of the heuristic repeater according to an embodiment of the present invention may be defined as an optimization problem of Equation 12 as follows.

Equation 12 may have the same constraint as Equation 13.

In this case, since it is assumed that there is no interference from other repeaters, when considering only interference received from the base station, the SINR of the predetermined link k _r of the repeater r may be defined as follows.

At this time, the interference of the transfer link k _r r received from the base station link is defined as follows: which may be the same as described in equation (3).

In this case, the beam allocator of the base station may use a result that has been already calculated.

In addition, the self-interference of the repeater r, that is, the interference received by the link k _r from another link formed by the repeater r may be defined as in the following equation.

That is, unlike Equation 16, Equation 16 does not consider interference from other repeaters. Therefore, the complexity of Equation 14 may be significantly lowered.

Then, the capacity of the link kr of the repeater r can be defined as follows,

Then, solving equation 12 in the heuristic-based resource allocation scheme according to an embodiment of the present invention can be obtained as follows.

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to be.

As a result, the heuristic-based resource allocation scheme according to the embodiment of the present invention has a much smaller complexity than the optimization-based resource allocation scheme, and the base station knows its own state information of all the relays, that is, the information necessary to calculate the interference. The beam allocator can be calculated, and the repeater can calculate its own beam allocator without knowing the status information of other repeaters, thereby increasing the efficiency of the calculation. In addition, since each of the repeaters do not need to know the status information of the other repeaters can be distributed and calculate their beam allocator at the same time, there is an effect that the speed of operation and thus the performance of the entire system can be significantly increased.

In addition, in the foregoing description, a case in which the powers of beams formed by each of the base station or the repeater are equally allocated is described as an example. Of course, it can be obtained similarly to one.

11 to 14 are diagrams showing simulation results for explaining performance of communication efficiency according to a resource allocation method of a BDMA based hybrid communication network system according to an exemplary embodiment of the present invention.

11 to 14 show simulation results in an environment in which two repeaters are installed in the coverage of one base station. The cell sizes of the base station and repeater are 500m and 100m, respectively, and the maximum transmit power is set to Pmax = 43dBm and Pr, max = 40dBm, respectively. The maximum number of beams that can be formed by the base station is 4, the maximum number of beams that can be formed by the repeater is 2, and the beam width is set to 30 degrees, respectively. The distance between the base station and each repeater was fixed at 250m, and the performance was examined while changing the distance between the repeaters at 500m and 50m.

In FIGS. 11 to 14, the optimization scheme represents a resource allocation scheme according to the optimization scheme as described in FIG. 9, and the heuristic scheme is a heuristic according to the embodiment of the present disclosure as described in FIG. 10. Represents the resource allocation method based on In addition, a random scheme represents a case of randomly allocating resources (beams), and a conventional scheme represents an optimal beam allocation scheme in an environment in which only a base station exists.

11 and 12 are the distance between the repeater is 500m, Figure 11 shows the results of the simulation while increasing the number of users of the base station after fixing the number of users of each repeater to 4, Figure 12 is the number of users of the base station After fixing 6 to 6, increase the number of users of each repeater and show the result of simulation.

11 and 12, it can be seen that the optimal solution exhibits the best spectral efficiency compared to other methods. On the other hand, it can be seen that the heuristic scheme maintains relative spectral efficiency, that is, (efficiency of the heuristic scheme / efficiency of the optimal scheme) * 100 close to 92% compared to the optimal scheme. Random rooms, on the other hand, can maintain a relative spectral efficiency of 76%.

As a result, the heuristic scheme according to the embodiment of the present invention can show the performance close to the optimal scheme, despite the fact that the complexity and the fast computational speed and distributed computation can be performed significantly. This is because the capacity of the base station in the heuristic scheme is slightly reduced compared to the optimal scheme because the base station allocates beams with only some information, but the repeater can maintain almost the same efficiency as in the results of FIGS. 11 and 12. This result can be seen that the case of fixing the number of users of the repeater as shown in FIG. 11 or the case of fixing the number of users of the base station as shown in FIG.

On the other hand, Figures 13 and 14 set the distance between the two repeaters to 50m, respectively, when the number of users of the repeater is fixed to 4 and the number of users of the base station to 6 after the number of users of the base station and the number of users of the repeater The results of the simulation are shown while increasing.

In this case, it can be seen that the relative spectral efficiencies for the heuristic and random methods are reduced to 89% and 72%, respectively. The reason is that as the interference between the repeaters increases like the heuristic scheme, the capacity of the base station and the repeater may all decrease compared to the optimal scheme when the base station performs beam allocation with only some information. However, even in such a case, it can be seen that the heuristic scheme exhibits relatively close performance, and similar simulation results are obtained in both FIGS. 13 and 14.

The method of providing a BDMA based hybrid communication network system according to an exemplary embodiment of the present invention may be implemented as computer readable codes on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a hard disk, a floppy disk, an optical data storage device, and the like in the form of a carrier wave (for example, . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. And functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers skilled in the art to which the present invention pertains.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (13)

In the BDMA (Beam Division Multiple Access) based hybrid communication network system,
The BDMA-based hybrid communication network system,
In order to allocate a beam of each of the base station and at least one repeater included in the BDMA-based hybrid network system,
For the beam allocator of the base station, calculating the beam allocator of the base station to maximize the capacity of the base station without considering the interference of the at least one repeater and the base station,
For the beam allocator of any one of the at least one repeater, the beam allocator of the repeater is calculated based on the calculated base station beam allocator. .
The method of claim 1, wherein the BDMA-based hybrid network system,
To calculate the base station beam allocator that maximizes the capacity of the base station without considering interference of the at least one repeater and the base station,
When a first link is formed between the base station and a specific user connected to the base station,
BDMA-based hybrid communication network system for efficient resource allocation for calculating the beam allocator of the base station by calculating the interference received by the second link formed by the second link to the base station.
3. The BDMA based hybrid communication network system according to claim 2, wherein the interference received by other second links formed by the base station is expressed by the following equation.

Where a is the index of the beam, m is the index of the user,

Is the power of beam b in timeslot n,

Is the channel gain in timeslot n,

Denotes a beam allocating value in timeslot n, n is an index of a timeslot, k is an index of the first link, B is a set of beams of the base station, K is a set of users connected to the base station, θ _a represents the angle between the direction of beam a of the base station and the direction of the first link.
4. The BDMA based hybrid communication network system according to claim 3, wherein the beam allocator of the base station is expressed by the following equation.

here,

A capacity function of the first link is represented, and p * represents a power of a beam formed by the base station.
5. The BDMA based hybrid communication network system according to claim 4, wherein the capacity function of the first link is expressed by the following equation.

here

Is the signal-to-interference-plus-noise ratio (SINR) of the first link,

Indicates.

The method of claim 1, wherein the BDMA-based hybrid network system,
To calculate the beam allocator of the repeater based on the calculated beam allocator of the base station,
When a third link is formed between the repeater and a specific user connected to the repeater,
Compute the interference received by the third link by the base station link according to the beam allocator of the base station and the interference received by the third link by the other fourth links of the repeater, and based on the calculation result, the beam of the repeater BDMA-based Hybrid Network System for Efficient Resource Allocation for Allocator.
7. The method of claim 6, wherein the interference received by the third link by the base station link according to the beam allocator of the base station and the interference received by the third link by the other fourth links of the repeater are as follows. Hybrid communication network system for efficient resource allocation, characterized in that the representation.

Here, r is the index of the repeater, k _r is the index of the third link.
8. The BDMA-based hybrid communication network system according to claim 7, wherein the beam allocator of the repeater is expressed by the following equation.

here,

The capacity function of the third link is represented, and p _r * represents the power of a beam formed by the base station.
9. The BDMA-based hybrid communication network system according to claim 8, wherein the capacity function of the third link is expressed by the following equation.

here

Is SINR,

Indicates.
The BDMA-based hybrid network system, with respect to the beam allocator of the base station included in the BDMA-based hybrid network system, without considering the interference of the base station and at least one relay included in the BDMA-based hybrid network system Computing a beam allocator of the base station to maximize the capacity of the base station; And
And calculating, by the BDMA-based hybrid communication network system, the beam allocator of the repeater based on the calculated beam allocator of the base station for the beam allocator of any one of the at least one repeaters. A method of providing a BDMA based hybrid communication network system for efficient resource allocation.
The method of claim 10, wherein calculating the beam allocator of the base station comprises:
Calculating a interference received by other second links formed by the base station when the first link is formed between the base station and a specific user connected to the base station; And
A method of providing a BDMA-based hybrid communication network system for efficient resource allocation, comprising calculating a beam allocator of the base station based on a result of the calculation.
The method of claim 10, wherein the calculating of the beam allocator of the repeater,
When a third link is formed between the repeater and a specific user connected to the repeater, the third link is received by the base station link according to the beam allocator of the base station, and the third link is another fourth of the repeater. Calculating interference received by the links; And
Comprising a step of calculating the beam allocator of the repeater based on the result of providing a BDMA-based hybrid communication network system for efficient resource allocation.
A computer-readable recording medium having recorded thereon a program for performing the method according to any one of claims 10 to 12.

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