KR101430317B1 - Method for selecting frequency band in femtocell and communication system including macrocell base and femtocell base using shared sub-band - Google Patents

Abstract

)를 결정하는 매크로셀 기지국(MeNB, 110) 및

개의 공유 부대역 중에서 기준 거리에 위치한 이웃 HeNB가 사용하는 이웃 공유 부대역을 선택하는 펨토셀 기지국(HeNB, 130)을 포함한다.The communication system 100 may determine the number of shared subbands that can be used by the femtocell base station (HeNB) 130

A macro cell base station (MeNB) 110 for determining

And a femtocell base station (HeNB) 130 that selects neighboring shared subbands used by neighboring HeNBs located at a reference distance from the shared subbands.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for selecting a frequency band of a femtocell, and a communication system using a shared subband by a macro-cell base station and a femtocell base station.

The following description relates to a method for selecting a frequency band for a femtocell in a communication system using a shared subband by a macro cell base station and a femtocell base station.

As the mobile terminal and the mobile communication system evolve, security service, wireless Internet service, and location tracking service are provided to subscribers. In addition, research is continuing to provide faster and more diverse services than current services.

One of the objects of the research is a femtocell service that further subdivides a cell serving as a service area of a mobile communication system and connects a mobile terminal located in the cell area to a broadband Internet network. A femtocell is a compound word of a femto which means 1 / 100th of a cell and a cell which is a unit of a service area of a mobile terminal. The femtocell is a combination of a femtocell AP (Femto Access Point) To provide a mobile communication service.

The femtocell is used mainly for the purpose of guaranteeing the quality of the mobile communication service in the area where the propagation of the macrocell is degraded or in the shaded area as in the home or the building, and the femtocell is provided at a low price As well as a means for measuring the temperature of the liquid. In addition, because femtocell uses general-purpose Internet line for connection with core network of mobile communication, installation cost and maintenance cost are low, and since an area where an Internet line is installed can be installed anywhere, .

In order to mitigate downlink interference between a macrocell and a femtocell in a heterogeneous cell network environment in which a macro cell and a femtocell are mixed, a transmission power adjustment technique and a frequency band division technique have been proposed.

The frequency band segmentation technique divides the entire frequency band into several subbands and assigns them to macro cells and femtocells. Frequency band segmentation is divided into Orthogonal Assignment and Partial Sharing. In the orthogonal assignment scheme, macrocells and femtocells can avoid mutual interference by selecting and using different subbands. However, the orthogonal allocation scheme can not efficiently use the frequency resources because only a part of the entire frequency band is used in both the macrocell and the femtocell. In the partial sharing scheme, a macro cell uses all the frequency bands and a femtocell uses only a part of the entire sub-bands with a macro cell. In the partial sharing scheme, the entire frequency band is divided into a shared subband, which is a frequency band used by a macrocell and a femtocell, and a dedicated subband, which can be used only in a macrocell.

The partial sharing scheme has a problem that a usable frequency band of a femtocell base station is reduced due to fragmentation of a shared subband for interference mitigation between a dedicated subband for a macro cell terminal and a femtocell base station. Also, the interference mitigation technique between the femtocell base stations using the femtocell base station gateway has a problem in that the complexity for obtaining optimal radio resource allocation results increases significantly as the number of femtocell base stations increases.

In the heterogeneous cell network environment, a macro cell and a femtocell use the entire frequency band as a shared band to expand a frequency band usable in a femtocell.

In addition, the technology described below adjusts the number of the shared subbands to be used by the femtocell base station adaptively to the change of the network environment, thereby providing the macrocell base station with the SIR higher than the threshold value set in advance for the macrocell terminal do.

In addition, the technique described below attempts to minimize the mutual interference between the macrocell terminal and the femtocell through the distributed HeNB clustering in which the femtocell base station performs only the self-measured channel information without exchanging information between the femtocell base stations.

The solutions to the technical problems described below are not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

)를 결정하는 단계 및 펨토셀 기지국(HeNB)이 기준 거리에 위치한 이웃 HeNB가

개의 공유 부대역 중에서 동일한 이웃 공유 부대역을 사용하도록 설정하는 단계를 포함한다.A method for selecting a frequency band of a femtocell according to the present invention is characterized in that in a communication system using a shared subband by a macro cell base station (MeNB) and a femtocell base station (HeNB), a macro cell base station (MeNB) Number of subbands (

) And determining whether the femtocell base station (HeNB)

And using the same neighbor shared subbands among the shared subbands.

)에 따른 메크로셀 단말(MUE) i의 SIR값과 문턱값을 비교하여 결정한다.The step of determining the number of shared subbands comprises determining the density of the femtocell base station (HeNB) using the common subbands

) Of the macrocell terminal (MUE) i with the threshold value.

)에 따른 펨토셀 기지국(HeNB)과 메크로셀 단말(MUE) i의 상호간섭을 연산하고, 연산과정마다 상호간섭을 기준으로 연산된 SIR값과 문턱값을 비교하여 SIR값이 문턱값보다 큰 경우의 임시 공유 부대역의 수를 공유 부대역의 수로 결정한다.The step of determining the number of shared subbands increases the number of temporary shared subbands from 1 to

(MUE) i of the femtocell base station (HeNB) according to the mutual interference of the femtocell base station (HeNB) and the macrocell terminal (MUE) i, and compares the SIR value calculated based on mutual interference with the threshold value The number of temporary shared subbands is determined by the number of shared subbands.

로 표현되는 밀집도(

)에 따른 상호간섭을 연산하는 단계, 상호간섭을 기준으로 메크로셀 단말(MUE) i의 SIR값(

)을 연산하는 단계 및

과 문턱값(

)을 비교하면서

>

이 되는 경우의

를 공유 부대역의 수로 결정하는 단계를 포함한다. 공유 부대역의 수가 결정될 때까지 자연수인

를 1부터 증가시키면서 상호간섭을 연산하는 단계, SIR값을 연산하는 단계 및 결정하는 단계를 반복한다.The step of determining the number of shared sub-

Dense density expressed as

Calculating a mutual interference according to the SIR value of the macrocell terminal (MUE) i based on the mutual interference;

); And

And threshold (

)

>

In the case of

As the number of shared subbands. Until the number of shared subbands is determined,

Calculating the mutual interference while increasing the value from 1, calculating and determining the SIR value are repeated.

The setting step measures the RSS in the shared subband determined by the HeNB and selects the neighbor shared subband satisfying the QoS condition of the femtocell terminal (HUE) using the RSS.

개의 공유 부대역 각각에서 RSS를 측정하는 단계, HeNB가 공유 부대역 각각에서 펨토셀 단말(HUE)의 QoS 조건을 만족하는 후보 공유 부대역을 선택하는 단계 및 HeNB가 후보 공유 부대역 중에서 이웃 공유 부대역을 선택하는 단계를 포함한다.The setting step is

Measuring the RSS in each of the shared subbands, selecting a candidate shared subband that meets the QoS requirements of the femtocell terminal (HUE) in each of the shared subbands, and selecting the candidate shared subbands among the candidate shared subbands .

)보다 낮은 지역(OA)을 추정하는 단계 및 HeNB가 전체 통신반경면적에서 낮은 지역(OA)이 차지하는 비율을 기준으로 후보 공유 부대역을 결정하는 단계를 포함한다.The step of selecting the candidate shared subband includes estimating the distance ( d _{k , l} ) between the HeNB (k) and the virtual HeNB (l), assuming that the RSS measured by the HeNB is received from the virtual HeNB, (d _{k, l)} estimating the SIR value of the femtocell UE (HUE) to use, and the SIR value of the threshold (

) And determining the candidate shared subband based on the proportion of the HeNB occupied by the low area (OA) in the total communication radius area.

In the step of determining QoS satisfaction, if the estimated ROA in the shared subband is 0 (zero), the shared subband is determined as the candidate shared subband.

개의 공유 부대역 중 임의의 하나를 이웃 공유 부대역을 선택한다.The step of selecting a neighbor shared sub-band selects a candidate shared sub-band having the highest RSS value in the candidate shared sub-band as a neighbor shared sub-band, and if there is no selected candidate shared sub-

And selects a neighboring shared subband for any one of the shared subbands.

)를 결정하는 매크로셀 기지국(MeNB) 및 공유 부대역 중에서 기준 거리에 위치한 이웃 HeNB가 사용하는 이웃 공유 부대역을 선택하는 펨토셀 기지국(HeNB)을 포함한다.The communication system using the shared subbands of the macro cell base station and the femtocell base station according to the present invention is able to use the number of shared subbands that can be used by the femtocell base station (HeNB)

And a femtocell base station (HeNB) for selecting neighboring shared subbands used by neighboring HeNBs located at a reference distance from the shared subbands.

)에 따른 펨토셀 기지국(HeNB)과 메크로셀 단말(MUE) i의 상호간섭을 연산하고, 연산과정마다 상호간섭을 기준으로 연산된 SIR값과 문턱값을 비교하여 SIR값이 문턱값보다 큰 경우의 임시 공유 부대역의 수를 공유 부대역의 수로 결정한다.The macro cell base station (MeNB) increases the number of temporary shared subbands from 1 to

(MUE) i of the femtocell base station (HeNB) according to the mutual interference of the femtocell base station (HeNB) and the macrocell terminal (MUE) i, and compares the SIR value calculated based on mutual interference with the threshold value The number of temporary shared subbands is determined by the number of shared subbands.

The HeNB measures the RSS in the determined shared subband and selects the neighbor shared subband satisfying the QoS condition of the femtocell terminal (HUE) using RSS.

개의 공유 부대역 각각에서 RSS를 측정하는 RSS 측정부, 측정한 RSS를 가상 HeNB로부터 수신한 것으로 가정하고 HeNB(k)와 가상 HeNB(l) 사이의 거리(d _{k ,l})를 추정하는 거리 추정부, 거리(d _{k ,l})를 이용하여 펨토셀 단말(HUE)의 SIR 값을 추정하고, SIR 값이 문턱값(

)보다 낮은 지역(OA)을 추정하는 지역 추정부, 전체 통신반경면적에서 낮은 지역(OA)이 차지하는 비율(ROA)을 기준으로 QoS 만족 여부로 후보 공유 부대역을 선택하는 후보 선택부 및 후보 공유 부대역 또는 공유 부대역을 기준으로 이웃 공유 부대역을 선택하는 공유 부대역 선택부를 포함한다.HeNB

( D _{k , l} ) between the HeNB (k) and the virtual HeNB (l), assuming that the measured RSS is received from the virtual HeNB _, And the SIR value of the femtocell terminal HUE is estimated using the distance d _{k , l} and the SIR value is set to a threshold value

A candidate selector for selecting a candidate shared subband based on the satisfaction of the QoS based on the ratio (ROA) of the low area (OA) in the entire communication radius area, And a shared subband selection unit for selecting a neighboring shared subband based on the subband or shared subband.

If the ROA estimated from the shared subband is 0 (zero), the candidate selector determines that the shared subband is a candidate shared subband.

개의 공유 부대역 중 임의의 하나를 이웃 공유 부대역을 선택한다.The shared subband selector selects the candidate shared subband having the highest RSS value as the neighbor shared subband in the candidate shared subband and if there is no selected candidate shared subband

And selects a neighboring shared subband for any one of the shared subbands.

The technology described below can improve the radio capacity of a femtocell by extending a frequency band usable in a femtocell without setting a dedicated dedicated subband for the macrocell terminal.

The technique described below mitigates the mutual interference between the macro cell terminal and the femtocell base station in a frequency band not used by the femtocell base station by using the same shared subband by the neighboring femtocell base stations.

The technique described below selects the shared subband for clustering of the femtocell base station based on the SIR threshold value of the femtocell terminal, thereby minimizing the degradation of the femtocell performance by suppressing the mutual interference between the femtocell base stations.

The effects of the techniques described below are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 shows an example of interference between a macro cell terminal and a femtocell base station when a neighboring femtocell base station uses the same shared subband in a communication system in which a macrocell and a femtocell use the entire frequency band as a shared band.
2 is a schematic flowchart of a method of selecting a frequency band of a femtocell.
3 is a schematic flowchart of a step in which a macro cell base station determines the number of shared subbands usable by a femtocell base station.
4 (a) is a schematic flowchart of a step of setting a neighbor femtocell base station to use the same neighboring shared subband by the femtocell base station, FIG. 4 (b) is a diagram illustrating a candidate shared subband for selecting a neighbor shared subband FIG. 2 is a schematic flow diagram of a step of selecting a memory cell.
FIG. 5 is another flowchart illustrating a step in which the femtocell base station shown in FIG. 4 sets a neighbor femtocell base station to use the same neighbor shared subband.
6 is a diagram illustrating a process of assuming the strength of a signal received from one virtual femtocell base station in the step of measuring RSS in the femtocell base station.
FIG. 7 is an exemplary diagram illustrating a ratio of a low (Orthogonal Area) occupation in a total communication radius area in a femtocell base station.
8 is a schematic block diagram of a configuration of a communication system using a shared subband by the macro cell base station and the femtocell base station.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

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

As used herein, the singular " include "should be understood to include a plurality of representations unless the context clearly dictates otherwise, and the terms" comprises & , Parts or combinations thereof, and does not preclude the presence or addition of one or more other features, integers, steps, components, components, or combinations thereof.

Before describing the drawings in detail, it is to be clarified that the division of constituent parts in this specification is merely a division by main functions of each constituent part. That is, two or more constituent parts to be described below may be combined into one constituent part, or one constituent part may be divided into two or more functions according to functions that are more subdivided. In addition, each of the constituent units described below may additionally perform some or all of the functions of other constituent units in addition to the main functions of the constituent units themselves, and that some of the main functions, And may be carried out in a dedicated manner. Therefore, the existence of each of the components described in the present specification should be interpreted as a function, and for this reason, the macrocell base station and the femtocell base station of the present invention are not limited to the components of the communication system 100 using the shared sub- It is clear that the configuration can be different from that of Fig. 8 within the scope of achieving the object of the present invention.

Also, in performing a method or an operation method, each of the processes constituting the method may take place differently from the stated order unless clearly specified in the context. That is, each process may occur in the same order as described, may be performed substantially concurrently, or may be performed in the opposite order.

Hereinafter, a frequency band selection method of a femtocell and a communication system using a shared subband by a macro cell base station and a femtocell base station will be described in detail with reference to the drawings.

First, we will define abbreviations for the terms to be used first. Hereinafter, the macrocell base station (Macro eNode B) is referred to as MeNB, the macro user equipment as MUE, the femtocell base station (Home eNode B) as HeNB and the femtocell base station Equipment) is called 'HUE'.

1 shows an example of interference between a macro cell terminal and a femtocell base station when a neighboring femtocell base station (HeNB) uses the same shared subband in a communication system in which a macrocell and a femtocell use the entire frequency band as a shared band.

FIG. 1 shows an example of interference mitigation of a macrocell and a femtocell through clustering of HeNBs. In FIG. 1, HeNBs are grouped into HeNBs using the same shared subband. At this time, the intensity of the interference that a specific MUE receives from the HeNB in each subband is the lowest in the subband (C) used in the HeNB cluster which is distant from the MUE. 1, the interference between the MUE and the HeNB is lowered in order of A> B> C. Also, if the MeNB allocates a subband (C) used by an HeNB cluster that is far from the MUE, the MUE can avoid strong interference in adjacent HeNB communities.

The present invention is characterized in that neighboring HeNBs are allocated to use the same shared subband while MeNB and HeNB satisfy the SIR condition between MeNB and MUE in a communication system sharing the entire frequency band.

The present invention is based on a partial sharing scheme in which MeNB allocates radio resources to MUEs in the entire frequency band and each HeNB allocates radio resources to HUE in a specific shared subband.

)를 결정하는 단계(510) 및 펨토셀 기지국(HeNB)이 기준 거리에 위치한 이웃 HeNB가

개의 공유 부대역 중에서 동일한 이웃 공유 부대역을 사용하도록 설정하는 단계(520)를 포함한다.2 is a schematic flowchart of a method of selecting a frequency band of a femtocell. A method for selecting a frequency band of a femtocell according to the present invention is characterized in that in a communication system using a shared subband by a macro cell base station (MeNB) and a femtocell base station (HeNB), a macro cell base station (MeNB) Number of subbands (

(510) of the femtocell base station (HeNB) and a neighboring HeNB located at a reference distance

(520) the same neighbor shared subbands among the shared subbands.

개의 공유 부대역은 전체 주파수 대역을

개로 균등하게 분할한 것이다.In step 520

The shared subbands share the entire frequency band

It is divided equally into two.

)를 결정한다. MeNB는 공유 부대역의 수(

)의 정보를 주기적으로 방송메시지에 포함하여 이를 HeNB에 전달한다. The present invention grasps the number of HeNBs that are periodically using radio resources within their communication radius. After that, MeNB estimates the mutual interference with the HeNB to satisfy the SIR requirement of the MUE, and calculates the number of shared subbands to obtain the mutual interference with the desired HeNB

). MeNB is the number of shared subbands (

) In the broadcast message and transmits it to the HeNB.

The HeNB, which grasps the number of shared subbands, clusters the locally adjacent HeNBs to use the same subband to minimize mutual interference to the MUE. For clustering, the HeNB selects and uses high RSS subbands using a number of neighboring HeNBs. In addition, to prevent excessive clustering between HeNBs, the HeNB estimates the SIR of the HUE in each subband and does not select a shared subband with an SIR lower than a specific SIR.

)과 자신의 통신반경 내에 특정 부대역을 공유하는 HeNB의 밀집도를 고려하여 공유 부대역의 수를 결정하는 단계이다. HeNB의 밀집도(

)는 MeNB의 통신반경 내에서 동작 중인 HeNB의 수를 통신반경의 면적비를 통해 확인한다.The step 510 of determining the number of shared subbands by MeNB is based on the fact that the MeNB determines the SIR threshold of the MUE

And the number of shared subbands considering the density of the HeNBs sharing a specific subband within its own communication radius. Density of HeNB

) Confirms the number of HeNBs operating within the communication radius of the MeNB through the area ratio of the communication radius.

)에 따른 매크로셀 단말(MUE) i의 SIR값과 문턱값(

)을 비교하여 결정한다.The step 510 of determining the number of shared subbands may include determining the density of the femtocell base station (HeNB) using the common subbands

) Of the macro cell terminal (MUE) i and the threshold value (

).

)에 따른 펨토셀 기지국(HeNB)과 매크로셀 단말(MUE) i의 상호간섭을 연산하고(511), 연산과정마다 상호간섭을 기준으로 SIR 값을 연산하고(512), 연산된 SIR값과 문턱값(

)을 비교하여(513) SIR값이 문턱값(

)보다 큰 경우의 임시 공유 부대역의 수를 공유 부대역의 수로 결정한다(514).The step 510 of determining the number of shared subbands increases the number of temporary shared subbands from 1 to a dense

The interferences between the femtocell base station HeNB and the macrocell terminal MUE i according to mutual interference are computed 511. The SIR value is computed 512 based on mutual interference in each computation process, (

(513) and the SIR value is compared with a threshold value

) Is determined as the number of shared subbands (514).

3 is a schematic flowchart of a step in which a macro cell base station determines the number of shared subbands usable by a femtocell base station.

로 표현되는 밀집도(

)에 따른 상호간섭을 연산하는 단계, 상호간섭을 기준으로 매크로셀 단말(MUE) i의 SIR값(

)을 연산하는 단계 및

과 문턱값(

)을 비교하면서

>

이 되는 경우의

를 공유 부대역의 수(

)로 결정하는 단계를 포함한다.Specifically, the step of determining the number of shared subbands

Dense density expressed as

Calculating a mutual interference according to the SIR value of the macrocell terminal (MUE) i based on mutual interference;

); And

And threshold (

)

>

In the case of

The number of shared subbands (

). ≪ / RTI >

를 1부터 증가시키면서 상호간섭을 연산하는 단계, SIR값을 연산하는 단계 및 결정하는 단계를 반복하여 수행한다. 여기서

는 임시 공유 부대역의 수이고, 최종적인 공유 부대역의 수는

이다.Until the number of shared subbands is determined,

Calculating the SIR value, and determining the SIR value are repeatedly performed. here

Is the number of temporary shared subbands, and the number of final shared subbands is

to be.

The SIR value of the MUE can be expressed as Equation (1) below.

Here, x _i is the distance between MUE i and MeNB, h is the channel gain, α is the signal attenuation index, P _m is the transmit power of MeNB, P _f is the transmit power of the HeNB, φ _f is the HeNB and MUE i.

)에 의해 결정된다. HeNB가 전체 시스템 주파수 대역을 다수의 공유 부대역으로 나누고 그 중 하나를 선택하여 이용할 때, MeNB와 특정 부대역을 공유하는 HeNB의 밀집도(

)는 무선자원을 사용하는 전체 HeNB의 밀집도(

)와 공유 부대역 개수(

)의 비(

)로 얻어진다.The mutual interference between the HeNB and the MUE depends on the density of the HeNB sharing MeNB and a particular subband (

). When the HeNB divides the entire system frequency band into a number of shared subbands and selects one of them, the density of the HeNBs sharing the specific subband with the MeNB

) Is the density of the entire HeNB using radio resources (

) And the number of shared subbands (

) Ratio

).

)는 MUE에 상호간섭을 주는 HeNB 수를 결정한다. 상기 수학식 1에서 상호관섭과 관련된 수식은

이다. 이 식에서 밀집도(

)가 낮을 경우 φ_f에 포함된 원소의 개수가 적기 때문에 상호간섭이 줄어들고, 밀집도(

)가 높은 경우에는 φ_f에 포함된 원소의 개수가 많아져 상호간섭이 증가하게 된다.
Concentration of HeNB using cooperative subband (

) Determines the number of HeNBs giving mutual interference to the MUE. In Equation (1), the equation relating to mutual interference

to be. In this equation,

) Is low, mutual interference is reduced because the number of elements contained in? _F is small, and density

) Is high, the number of elements included in? _F increases and mutual interference increases.

4 (a) is a schematic flowchart of a step of setting a neighbor femtocell base station to use the same neighboring shared subband by the femtocell base station, FIG. 4 (b) is a diagram illustrating a candidate shared subband for selecting a neighbor shared subband FIG. 2 is a schematic flow diagram of a step of selecting a memory cell.

The setting step measures the RSS in the shared subband determined by the HeNB and selects the neighbor shared subband satisfying the QoS condition of the femtocell terminal (HUE) using the RSS.

개의 공유 부대역 각각에서 RSS를 측정하는 단계, HeNB가 공유 부대역 각각에서 펨토셀 단말(HUE)의 QoS 조건을 만족하는 후보 공유 부대역을 선택하는 단계 및 HeNB가 후보 공유 부대역 중에서 이웃 공유 부대역을 선택하는 단계를 포함한다.As shown in Fig. 4 (a), the setting step is performed by the HeNB

Measuring the RSS in each of the shared subbands, selecting a candidate shared subband that meets the QoS requirements of the femtocell terminal (HUE) in each of the shared subbands, and selecting the candidate shared subbands among the candidate shared subbands .

)보다 낮은 지역(Orthogonal Area, 이하 'OA'라 함)을 추정하는 단계, HeNB가 전체 통신반경면적에서 낮은 지역(OA)이 차지하는 비율(ROA)을 기준으로 후보 공유 부대역을 결정하는 단계를 포함한다.As shown in FIG. 4B, the step of selecting the candidate shared subband includes receiving the RSS measured by the HeNB from the virtual HeNB and calculating the distance d _{k , k} between the HeNB (k) and the virtual HeNB (l) _the HeNB estimates the SIR value of the femtocell terminal HUE using the distance d _{k , l} , and the SIR value is the threshold value

Estimating an Orthogonal Area (hereinafter, referred to as 'OA') lower than the total communication radius area, and determining a candidate shared subband based on the ratio (ROA) .

The SIR value of the HUE can be expressed as Equation (2) below.

Where P _f is the transmit power of the HeNB, h is the channel gain, α is the signal attenuation index, and x and y are the coordinate positions of HUE.

) 및 HUE의 SIR 문턱값(

)은 서비스 품질에 의해 사전에 결정되는 것이다. 이동통신서비스의 품질은 이동통신사업자가 결정하거나 또는 통신정책에 따라 결정될 수 있다.
The SIR threshold value of the above-mentioned MUE (

) And the SIR threshold value of HUE (

) Is determined in advance by the quality of service. The quality of the mobile communication service may be determined by the mobile communication carrier or may be determined according to the communication policy.

In the step of determining QoS satisfaction, if the estimated ROA in the shared subband is 0 (zero), the shared subband is determined as the candidate shared subband.

Finally, the HeNBs sharing the same shared sub-band, the neighbor shared sub-band, are determined by the ROA value. That is, grouping of adjacent HeNBs is determined by ROA. When a group of HeNBs that are locally adjacent are grouped together and an HeNB newly determines their group in an environment using common subband A, the corresponding HeNB estimates the ROA value for the common subband A used by the adjacent HeNBs, Only when the value of ROA is 0, select the group and use co-subband A. If the number of HeNBs included in the HeNB group using the common sub-band A is large and the interference between the HeNBs in the group is large, the value of ROA estimated from the common sub-band A becomes larger than 0, and the HeNB no longer selects the corresponding group No more grouping is done.

개의 공유 부대역 중 임의의 하나를 이웃 공유 부대역을 선택한다.
The step of selecting neighboring shared subbands for neighboring HeNBs selects a candidate shared subband with the highest RSS value in the candidate shared subband as the neighbor shared subband, and if there is no selected candidate shared subband

And selects a neighboring shared subband for any one of the shared subbands.

FIG. 5 is another flowchart illustrating a step in which the femtocell base station shown in FIG. 4 sets a neighbor femtocell base station to use the same neighbor shared subband. Although FIG. 5 shows a flowchart, at the same time, a kind of pseudo code is described.

는 HeNB가 사용할 수 있는 공동 부대역의 수이고,

는 HUE의 SIR 문턱값이고, S는 후보 공유 부대역의 집합이고, FBS는 가상 펨토셀 기지국(HeNB)이고, s _i는 i번째 부대역이고, Ω_k,l.i는 s _i에서 HeNB(k)와 가상 HeNB(l) 사이의 거리(d _{k ,l})에 따른 ROA값을 의미한다.5

Is the number of common subbands available to the HeNB,

Is a SIR threshold value of the HUE, S is the set of candidate shared sub-band, and FBS are virtual femtocell base station (HeNB), and, s _i is the i th sub-band, Ω _{k, li} is HeNB (k) in s _i Denotes the ROA value according to the distance ( d _{k ,} l) between the virtual HeNBs l.

개가 될 때까지 각 공유 부대역에 대해서 RSS를 측정하여 ROA를 연산하는 과정을 반복한다. 모든 공유 부대역에 대하여 ROA를 측정하고, ROA가 0인 경우 S에 해당 공유 부대역(s _i)을 추가한다. 최종적으로 S가 공집합이 아니라면 RSS가 가장 높은 값을 갖는 후보 공유 부대역을 이웃 공유 부대역으로 선택하고, 만약 S가 공집합이라면

개의 공유 부대역 중 임의의 하나를 이웃 공유 부대역을 선택한다.
Overall, i starts at 1

Repeat the process of calculating the ROA by measuring RSS for each shared subband until it becomes a dog. Measure the ROA for all shared subbands, and add the corresponding shared subbands ( s _i ) to S if ROA is zero. Finally, if S is not an empty set, RSS selects the candidate shared subband with the highest value as the neighbor shared subband, and if S is empty

And selects a neighboring shared subband for any one of the shared subbands.

6 is an exemplary diagram illustrating a process of assuming the strength of a signal received from one virtual femtocell base station (HeNB) in the step of measuring RSS by the femtocell base station.

)와 동일하다.As shown in FIG. 6, RSS is measured in a shared subband and is recognized as the strength of a signal received from one virtual HeNB that is not received from a plurality of HeNBs using the same shared subband. The virtual HeNB is introduced to calculate the ROA in each shared subband. The number of virtual HeNBs that interfere with one HeNB depends on the number of shared subbands (

).

FIG. 7 is an exemplary diagram illustrating a ratio of a low (Orthogonal Area) occupation in a total communication radius area in a femtocell base station.

)보다 낮은 영역은 사선으로 빗금친 OA(ψ)영역이다.
Assuming that the distance between the HeNB (HeNB _k ) and the virtual HeNB (HeNB _l ) is d _{k , l} and the HUE is located at an arbitrary coordinate ( x , y ) as shown in FIG. 7, the HeNB _{calculates the} distance d _k ), the distance d _l between the virtual HeNB and the HUE is calculated, and the SIR of the HUE is estimated as shown in Equation (2). HeNB _k has a communication radius (Q) with a radius r _k , and at S the SIR threshold (

) Is an OA (ψ) region shaded by an oblique line.

8 is a schematic block diagram of a configuration of a communication system 100 in which a macro cell base station 110 and a femtocell base station 130 use a shared subband.

The following description of the communication system 100 using the shared subband by the macro cell base station 110 and the femtocell base station 130 will be omitted or briefly explained in the frequency band selection method of the femtocell described above.

)를 결정하는 매크로셀 기지국(MeNB, 110) 및 공유 부대역 중에서 기준 거리에 위치한 이웃 HeNB가 사용하는 이웃 공유 부대역을 선택하는 펨토셀 기지국(HeNB, 130)을 포함한다.The communication system 100 according to the present invention calculates the number of shared subbands that can be used by the femtocell base station (HeNB) 130

And a femtocell base station (HeNB) 130 for selecting neighboring shared subbands used by neighboring HeNBs located at a reference distance from the shared subbands.

)에 따른 펨토셀 기지국(HeNB, 130)과 매크로셀 단말(MUE, 120) i의 상호간섭을 연산하고, 연산과정마다 상호간섭을 기준으로 연산된 SIR값과 문턱값을 비교하여 SIR값이 문턱값보다 큰 경우의 임시 공유 부대역의 수를 공유 부대역의 수로 결정한다. 여기서 SIR 값은 상기 수학식 1에 해당한다.The macro cell base station (MeNB) 110 increases the number of temporary shared subbands from 1 to

(HeNB) 130 and the macrocell terminal (MUE, 120) i according to the interfering signal, and compares the SIR value calculated on the basis of mutual interference with the threshold value every calculation process, The number of temporary shared subbands in the case of larger subbands is determined by the number of shared subbands. Here, the SIR value corresponds to Equation (1).

The HeNB 130 measures the RSS in the determined shared subband and selects neighboring shared subbands satisfying the QoS condition of the femtocell terminal (HUE 140) using RSS.

개의 공유 부대역 각각에서 RSS를 측정하는 RSS 측정부(131), 측정한 RSS를 가상 HeNB로부터 수신한 것으로 가정하고 HeNB(k)와 가상 HeNB(l) 사이의 거리(d _{k ,l})를 추정하는 거리 추정부(132), 거리(d _{k ,l})를 이용하여 펨토셀 단말(HUE)의 SIR 값을 추정하고, SIR 값이 문턱값(

)보다 낮은 지역(OA)을 추정하는 지역 추정부(133), 전체 통신반경면적에서 낮은 지역(OA)이 차지하는 비율(ROA)을 기준으로 QoS 만족 여부로 후보 공유 부대역을 선택하는 후보 선택부(134) 및 후보 공유 부대역 또는 공유 부대역을 기준으로 이웃 공유 부대역을 선택하는 공유 부대역 선택부(135)를 포함한다. HUE의 SIR 값은 상기 수학식 2로 표현된다.The HeNB 130

( D _{k , l} ) between the HeNB (k) and the virtual HeNB (l), assuming that the measured RSS is received from the virtual HeNB _, Estimates the SIR value of the femtocell terminal HUE using the distance estimator 132 and the distance d _{k ,}

, A region estimator 133 for estimating a region OA lower than the region OA that is lower than the region OA in the entire communication radius area, And a shared sub-band selection unit 135 for selecting a neighboring shared sub-band based on the candidate shared sub-band or the shared sub-band. The SIR value of the HUE is expressed by Equation (2).

The candidate selector 134 determines that the shared subband is a candidate shared subband when the ROA estimated from the shared subband is 0 (zero).

개의 공유 부대역 중 임의의 하나를 이웃 공유 부대역을 선택한다.The shared subband selector 135 selects the candidate shared subband having the highest RSS value as the neighbor shared subband in the candidate shared subband and if there is no selected candidate shared subband

And selects a neighboring shared subband for any one of the shared subbands.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. It will be understood that variations and specific embodiments which may occur to those skilled in the art are included within the scope of the present invention.

100: communication system 110: macro cell base station (MeNB)
120: macro cell terminal (MUE) 130: femtocell base station (HeNB)
131: RSS measurement 132: Distance estimation unit
133: area estimator 134: candidate selector
135: Shared subband selection unit 140: Femtocell UE (HUE)

Claims (20)

In a communication system in which a macro cell base station (MeNB) and a femtocell base station (HeNB) use a shared subband
The number of the shared subbands that the macro cell base station MeNB can use by the femtocell base station HeNB

); And
When the femtocell base station (HeNB) determines that the neighboring HeNB located at the reference distance

And using the same neighbor shared subbands among the shared subbands,
Wherein the step of determining the number of shared subbands comprises: determining a density of the femtocell base station (HeNB) using the common subband

) Of the macro cell terminal (MUE) i with a threshold value,
Wherein the HeNB measures the RSS in the determined shared subband and selects the neighbor shared subband satisfying the QoS condition of the femtocell terminal (HUE) using the RSS. delete The method according to claim 1,
Wherein determining the number of shared subbands comprises:
Increasing the number of temporary shared subbands from 1 to

) Of the femtocell base station (HeNB) and the macrocell terminal (MUE) i according to the mutual interference, calculates the mutual interference of the femtocell base station (HeNB) and the macrocell terminal Wherein the number of the shared subbands is larger than the threshold value. The method according to claim 1,
Wherein determining the number of shared subbands comprises:

(Denoted by < RTI ID = 0.0 >

Calculating a mutual interference according to the interference signal;
(SIR) value of the macrocell terminal (MUE) i based on the mutual interference

); And
remind

And the threshold value

)

>

In the case of

The number of shared subbands (

), ≪ / RTI >
Until the number of the shared subbands is determined,

Calculating the SIR value, and repeating the determining. The method of claim 1, further comprising:
(here,

Is the area ratio of the MeNB communication radius to the number of HeNBs located within the MeNB communication radius,

Is the number of temporary shared sub-bands) The method according to claim 3 or 4,
Wherein the SIR value is expressed by the following equation.

(Where, x _i is the distance, h is the channel gain, α the signal attenuation factor, P _m is the transmit power, P _f of MeNB is the transmission power, φ _f is a HeNB which the mutual interference of the HeNB between MUE i and MeNB and MUE i is the distance set) The method according to claim 1,
The shared sub-band may include the entire frequency band

And selecting the frequency band of the femtocell. delete The method according to claim 1,
The setting step
The HeNB

Measuring RSS in each of the shared subbands;
Selecting the candidate shared subband satisfying the QoS condition of the femtocell terminal (HUE) in each of the shared subbands; And
And the HeNB selecting the neighbor shared subband among the candidate shared subbands. 9. The method of claim 8,
The step of selecting the candidate shared sub-
Estimating a distance ( d _{k , l} ) between the HeNB (k) and the virtual HeNB (l), assuming that the HeNB has received the measured RSS from the virtual HeNB;
The HeNB is using the distances (d _{k, l)} to estimate the SIR value of the femtocell UE (HUE), that the SIR threshold value (

Estimating an area (OA) that is lower than the area (OA);
Determining whether the QoS is satisfied based on a ratio (ROA) occupied by the low area (OA) in the entire communication radius area of the HeNB. 10. The method of claim 9,
Wherein the SIR value is expressed by the following equation.

(Where P _f is the transmit power of the HeNB, h is the channel gain ,? Is the signal attenuation index, and x and y are the coordinate positions of the HUE) 10. The method of claim 9,
The step of determining whether the QoS is satisfied
And determining the shared subband as the candidate shared subband if the ROA estimated in the shared subband is zero. 12. The method of claim 11,
Wherein selecting the neighbor shared subband comprises:
Selects a candidate shared subband having the highest RSS value in the candidate shared subband as the neighbor shared subband, and if there is no candidate shared subband selected

And selecting any one of the shared subbands for the neighboring shared subbands. A communication system including a macro cell base station (MeNB) and a femtocell base station (HeNB)
The number of shared subbands that can be used by the femtocell base station (HeNB)

A macro cell base station (MeNB) for determining a transmission power of the macro cell; And
And a femtocell base station (HeNB) for selecting neighboring shared subbands used by neighboring HeNBs located at a reference distance from the shared subbands,
The macro cell base station MeNB increases the number of temporary shared subbands from 1 to 1,

) Of the femtocell base station (HeNB) and the macrocell terminal (MUE) i according to the mutual interference, and compares the SIR value calculated on the basis of the mutual interference with the threshold value for each calculation process, Determining the number of the temporary shared subbands when the number of the shared subbands is greater than the threshold,
The HeNB measures the RSS in the determined shared subband and selects the neighbor shared subband satisfying the QoS condition of the femtocell terminal (HUE) using the RSS, and the macro cell base station and the femtocell base station use the shared subband Lt; / RTI > delete 14. The method of claim 13,
Wherein the SIR value is expressed by the following equation, wherein the macro cell base station and the femtocell base station use a shared subband.

(Where, x _i is the distance, h is the channel gain, α the signal attenuation factor, P _m is the transmit power, P _f of MeNB is the transmission power, φ _f is a HeNB which the mutual interference of the HeNB between MUE i and MeNB and MUE i is the distance set) delete 14. The method of claim 13,
The HeNB
remind

RSS measuring unit for measuring RSS in each of the shared subbands
A distance estimator for estimating a distance ( d _{k , l} ) between the HeNB (k) and the virtual HeNB (l) on the assumption that the measured RSS is received from the virtual HeNB;
The distances (d _{k, l)} to estimate the SIR using the value of the femtocell UE (HUE), the SIR value is a threshold value (

A region estimator for estimating a region (OA) lower than the region (OA);
A candidate selecting unit for selecting a candidate shared subband based on the QoS satisfaction based on a ratio (ROA) occupied by the low area (OA) in the entire communication radius area; And
And a shared sub-band selector for selecting the neighbor shared sub-band based on the candidate shared sub-band or the shared sub-band, wherein the macro-cell base station and the femtocell base station use the shared sub-band. 18. The method of claim 17,
Wherein the SIR value is expressed by the following equation, wherein the macro cell base station and the femtocell base station use a shared subband.

(Where P _f is the transmit power of the HeNB, h is the channel gain ,? Is the signal attenuation index, and x and y are the coordinate positions of the HUE) 18. The method of claim 17,
The candidate selector
Wherein the macro cell BS and the femtocell BS determine that the shared subband is the candidate shared subband if the ROA estimated by the shared subband is 0 (zero). 18. The method of claim 17,
The shared sub-
Selects a candidate shared subband having the highest RSS value in the candidate shared subband as the neighbor shared subband, and if there is no candidate shared subband selected

Wherein the macro cell BS and the femtocell BS select any one of the shared subbands using the shared subband.

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