KR20140036737A - Method for allocating radio resource of small cell base station and small cell base station - Google Patents

Abstract

The present invention relates to a method for allocating wireless resources by considering the interference with the neighboring cells in a small cell base station. According to the present invention, disclosed is the wireless resource allocation method considering the interference with the neighboring small cells in a mobile communication system environment comprising: (a) a step of measuring the information of the neighboring small cell in the small cell base station; (b) a step of enabling the small base station to allocate the wireless resources for the data according to low interference areas and of exclusively allocating wireless resources for control based on the measured neighboring small cell information. [Reference numerals] (110) Detection module; (120) Allocation control module; (122) Wireless resource management unit; (124) Control resource allocation unit; (126) Data resource allocation unit; (AA) PCI/signal strength (RSCP); (BB) Sub-carrier wave; (CC) Separation setting (control/data); (DD) Grouping; (EE) Exclusive; (FF) Priority order

Description

Method for allocating a radio resource of a small cell base station considering interference and a small cell base station for the same {Method for allocating radio resource of small cell base station and small cell base station}

The present invention relates to a base station of a small cell, such as a femtocell, and more particularly, to a method for allocating radio resources in consideration of interference with neighboring cells in a small cell base station.

Conventionally, small cell base stations such as a femtocell base station, a picocell base station, a microcell base station, and the like have been mainly constructed and operated for the purpose of coverage compensation in a region where the signal of the macrocell is weak. However, in a situation in which data-oriented communication services are dominant in recent years, small cell base stations have been constructed and operated for data offload of macrocells.

Unlike a macro cell base station, such a femtocell has a limitation in applying cooperative communication technology between femtocells because it is difficult to exchange information between adjacent base stations. For this reason, interference problems occur when using radio resources (RB: Resource Block in LTE), such as between adjacent femtocells. In particular, interference in a control signal is the biggest factor that degrades femtocell performance.

As a conventional technique for solving the above problems, the Korean Patent Application Publication No. 2010-0125701 detects the signal strength of neighboring neighbor cell base station, and selectively reuses the frequency band having the lowest signal strength, A technical configuration for reducing the frequency interference of the is disclosed.

Looking at the above technique, by measuring the signal strength of the neighboring cell base station, by assigning and using the frequency region of the lowest signal strength, it is a technique to reduce the interference, a very common technique for avoiding interference.

However, the method of avoiding interference with neighboring cell base stations using only neighboring cell signal strength may not be an effective method in terms of efficient utilization of limited radio resources and guaranteeing performance of the base station itself.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and copes with the limitations of exchanging radio resource information with neighboring small cells (femtocells), utilizing information of neighboring small cells that can be obtained by itself, and for control and data. It is an object of the present invention to provide a method and a base station for allocating radio resources separately and allocating radio resources through different resource allocation algorithms.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Further, objects and advantages of the present invention can be realized by the means and the combination shown in the appended claims.

In order to achieve the above object, a radio resource allocation method of a small cell base station considering interference according to the present invention is a radio resource allocation method considering interference of neighboring small cells in a mobile communication system environment, (a) small cell base station Measuring information of adjacent neighboring small cells in a network; And (b) the small cell base station separately allocates the control radio resource and the data radio resource, and based on the measured neighboring small cell information, the control radio resource is allocated exclusively and the data radio resource has an interference level. Allocating the regions in descending order.

According to another aspect of the present invention, a small cell base station performing radio resource allocation processing considering interference of neighboring small cells in a mobile communication system environment, comprising: a detection module for measuring information of neighboring small cells; And separately assigning a control radio resource and a data radio resource, and based on the neighbor small cell information measured by the detection module, the control radio resource is exclusively allocated and the data radio resource is in the order of low interference level. There is provided a small cell base station comprising an allocation control module for allocating.

According to another aspect of the present invention, a recording medium on which a program for performing radio resource allocation processing in consideration of interference of neighboring small cells in a small cell base station in a mobile communication system environment is recorded, and a procedure for measuring information of adjacent neighboring small cells And allocating the control radio resource and the data radio resource separately, and based on the measured neighboring small cell information, the control radio resource is allocated exclusively and the data radio resource is allocated in the order of the region with the lowest interference level. A computer readable recording medium having recorded thereon a program to be executed is provided.

According to the present invention, when allocating a radio resource in a small cell base station, a control radio resource and a data radio resource are separated and used in different areas. By assigning priority to each other and assigning control resources exclusively so that they do not overlap with the area allocated by neighboring cells, it is possible to efficiently avoid interference of neighboring cells while ensuring the performance of the small cell base station. to provide.

In addition, even when the radio resource scheduling information is not shared between neighboring small cells in real time, the interference by neighboring small cells can be avoided by using information secured by the small cell itself, so that a low cost-high performance small cell can be constructed. have.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention below, And should not be construed as limiting.
1 is a diagram illustrating a structure in which small cell base stations according to an embodiment of the present invention are installed and operated adjacent to each other.
2 is a diagram illustrating a configuration of a small cell base station according to an embodiment of the present invention.
3 is a diagram illustrating a configuration in which radio resources are grouped into a plurality of groups and separated for control and data in a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.
4 is a diagram illustrating a configuration in which a radio resource for control is allocated in a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.
5 is a diagram illustrating an example of a graph measuring signal strength of neighboring small cells in a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.
6 is a view showing the ranking of the neighboring cells according to the signal strength measured in the radio resource allocation method of the small cell base station considering the interference according to an embodiment of the present invention.
7 is a diagram illustrating a configuration in which a radio resource for data is allocated in a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.
8 is a flowchart illustrating a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

1 is a diagram illustrating a structure in which small cell base stations according to an embodiment of the present invention are installed and operated adjacent to each other.

As shown in FIG. 1, the small cell base station 100 according to the present invention is installed and operated in various relative positions with other small cell base stations 101, 102, 103, 104 already installed in the vicinity. Here, referring to the small cell base station A (100), the small cell base station B (101), small cell base station C (102), small cell base station D (103), in order of distance from the small cell base station A (100), The small cell base station E104 is provided. Concentric circles shown in the figure is a guide line for indicating the relative distance with respect to the small cell base station A (100).

In a typical communication system, a macrocell serviced by a macrocell base station and a small cell serviced by the small cell base station 100 exist together. Here, the small cell may include a femto cell, a pico cell, a micro cell, or the like.

In addition, the coverage of the small cell base station 100 is present in the coverage areas 210 and 220 of the macro cell base station 200, and the small cell base station 100 is installed in an indoor or outdoor shadow area to improve service quality or service coverage. Or, it may be used for data offload in congested areas or areas where macrocell capacity saturation occurs.

The femto base station of the small cell base station 100 includes a Home NodeB (HNB) in a 3rd Generation Partnership Project (3GPP) Universal Mobile Telecommunications System (UMTS) or a Home eNodeB (HeNB) in a 3GPP Long Term Evolution (LTE). can do.

According to an embodiment of the present invention, the small cell base station 100 performs a process of allocating radio resources to minimize interference in consideration of interference with neighboring small cell base stations 101, 102, 103, 104 according to the installed location. Such a detailed configuration of the small cell base station 100 according to an embodiment of the present invention will be described later through additional drawings.

In general, as shown in the figure, the small cell base stations 101 and 102 that are close in distance to each other based on the small cell base station A 100 will be severely interfered with each other, and the small cell base stations 103 and 104 in which the distance is relatively low. This is simply a case of considering interference proportional to distance, and in addition, interference may occur between small cells according to various environmental factors. Therefore, the signal strength between the small cells is measured to accurately identify the influence of the interference between the small cells.

In the drawing, although the small cell base stations are illustrated as a distance concept, the following description assumes that the signal strength is also proportional to the distance.

As such, the small cell base station 100 is given identification information to reduce interference as much as possible in the communication system in consideration of interference with the neighbor small cell base stations 101, 102, 103, 104. That is, if four pieces of identification information can be given, four pieces of identification information are assigned to the small cell base stations 101, 102 and 103 having the closest distances and the largest signal strengths based on the small cell base station A 100 as shown in the drawing. Will be given.

The identification information provided to the small cells may include, for example, physical cell identity (PCI) information. That is, as shown in the three small cell base station B, C, D (101, 102, 103), including the small cell base station A (100), which has the most interference with the small cell base station A (100), PCI # 1 , PCI # 3, PCI, # 0, PCI # 2 are assigned. Since the small cell base station E 104 has the fourth lowest interference level to the small cell base station A 100, PCI # 1 is given again because only four pieces of identification information can be given. Through this, it is possible to avoid duplication of identification information with the small cell base station with the farthest interference level.

2 is a diagram illustrating a configuration of a small cell base station according to an embodiment of the present invention.

2, the small cell base station 100 according to the present invention includes a detection module 110, an allocation control module 120, and the like.

First, the small cell base station 100 of the present invention will be described assuming a femtocell base station operated under the control of the 3GPP LTE network system.

The small cell base station 100 according to an embodiment of the present invention groups a subcarrier, which is a radio frequency resource used by the base station, into a plurality of groups, and allocates radio resources to each group to perform a communication service. At this time, in consideration of interference with other small cell base stations adjacent to each other, the radio resources are allocated to minimize the interference. The radio resources for control and data radio resources used for the communication service are separated into independent areas. Assign. In addition, the control radio resources are allocated exclusively (orthogonally) to neighboring small cells so that interference can be thoroughly eliminated in the control radio resource region that is separated and dedicated. On the other hand, the data radio resource is allocated with priority to a radio resource group (RB) having a low level of interference so as to allow redundancy in a data radio resource area allocated exclusively, but to minimize interference.

In this way, the control radio resource and the data radio resource are used separately and different allocation algorithms are applied to each area, so that signals aiming for accurate transmission, such as control signals, can be minimized through exclusive resource allocation. Reduced, relatively non-critical signals, such as data signals, may allow some redundancy depending on the level of interference, ensuring maximum capacity within limited radio resources. In other words, it is possible to allocate efficient radio resources to satisfy both the accuracy to guarantee the radio quality and the performance improvement to increase the frequency reuse rate.

The detection module 110 detects information of small cell base stations (femtocell base stations) adjacent to the periphery. The detection module 110 detects identification information (PCI information) and relative signal strength (RSCP) information of neighboring small cell base stations. The identification information of the small cell base station may include PCI information, and the signal strength may include a reference signal received power (RSCP) measurement value and a carrier to interference-plus-noise ratio (CINR) measurement value. In addition, the detection module 110 may detect the information of the neighbor small cell base station through the sniff function used in the 3GPP LTE system.

The allocation control module 120 performs a process of allocating radio resources in consideration of interference with neighboring small cell base stations. The allocation control module 120 includes a radio resource management unit 122, a control resource allocation unit 124, a data resource allocation unit 126, and the like.

The radio resource manager 122 manages radio resources used for providing a communication service. A subcarrier is used among the radio resources, and the subcarriers to be used are grouped into a plurality of groups, and an area in which control radio resources and data radio resources are allocated is separately set in a plurality of groups. The plurality of grouped groups in which radio resources are actually allocated are referred to as resource blocks (RBs) in the example of the LTE system. An example of a subcarrier in which a control radio resource and a data radio resource are set separately will be described with reference to the additional drawings.

3 is a diagram illustrating a configuration in which radio resources are grouped into a plurality of groups and separated for control and data in a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.

As shown in FIG. 3, four control radio resources are grouped and separated in the central region a of the subcarriers, and two data resources are grouped and separated in two side regions b. The radio resource region for control / data set separately in this way is equally applicable to other small cell base stations (femtocell base stations).

In general, a smaller number of cell lists that can be assigned to small cells is given compared to macro cells. In a communication system, a cell identifier (PCI) is assigned to identify a cell. The PCI for a small cell (femtocell) generally allocates some of the PCI list exclusively for femto to prevent collision with a macrocell. . For example, PCI # 0 ~ 3 can be allocated for femto only. This makes femtocells vulnerable to PCI interference, and the operator will choose a PCI allocation algorithm to maximize the separation of femtocells using the same PCI (see Figure 1), and use this PCI information for radio resource group allocation. .

If four radio resource groups are grouped as in the example in the figure, if the number of PCIs dedicated to femto is also four, then the PCI number is used as the radio resource group number. As such, when the PCI is mapped to the radio resource group, since the PCI allocation itself is allocated to minimize interference with each other, there is an advantage that the radio resource allocation considering the interference with the neighboring PCI can be easily processed. Here, in the present embodiment, it is assumed that the number of PCI is assumed to be four, but can be expanded to eight, twelve, etc. according to the network design and the choice of the operator.

That is, as shown in FIG. 3, four radio resource groups are allocated to the control radio resource allocation area a, and PCI numbers are mapped and assigned to each. Similarly, four radio resource groups are allocated to the data radio resource allocation area b, and each is assigned a number by mapping PCI information.

The control resource allocator 124 allocates a control radio resource to the control radio resource allocation area (a). When allocating a control radio resource, an exclusive (orthogonal) allocation process is performed. As shown in FIG. 4, the control radio resource is allocated to a neighboring small cell in a mutually exclusive area. That is, the control radio resource allocation area (a) is divided into four groups, and each of them is assigned a number according to the peripheral small cell PCI information, so that the control (a1) corresponding to the PCI number assigned to it is used for control. Allocates radio resources. In this exclusive assignment, since the area does not overlap with neighboring small cells, interference can be prevented at the source. This is because the control signal is a signal requiring accuracy, so that only one of the four available radio resource groups is always used, so as to sacrifice radio resource capacity and block interference for accuracy.

The data resource allocator 126 allocates data radio resources to the data radio resource allocation area b. The reason why the control radio resource allocation area is located at the center of the data radio resource allocation area is that the control signal is more important than the data signal and requires accuracy as described above. In other words, the center is less concerned about the signal damage than both sides.

When allocating data radio resources, the interference level according to the signal strength of the neighboring femtocells is determined, and the interference levels are assigned to radio resource groups in order of priority. That is, as shown in FIG. 5, the signal strength of the surrounding femtocells is measured through the detection module 110, and as shown in FIG. 6, the priority of the neighboring femtocells is determined in the order of low signal strength. Referring to the drawings, PCI 1 has the lowest signal strength, followed by PCI 2, PCI 0, PCI 3 in the strongest signal strength.

When the signal strength priority is determined in this way, the radio resource for data is allocated according to the priority. In this case, as shown in FIG. 7, the determined priority ranking is set in the PCI 1 region b1 assigned to the PCI and the radio resource group to which the neighboring PCI is mapped. That is, since PCI 1 is the first rank, the radio resource for data is allocated to the area corresponding to control # 1 at the first priority. The radio resource group for data is set to be redundant, and when additional resource allocation is required, additional resource allocation is performed according to the set priority. Since the priority assigned to each radio resource group is a low-interference with the neighboring femtocells, when the radio resources for data are allocated according to the corresponding order, the resources can be efficiently reused while minimizing the interference.

8 is a flowchart illustrating a radio resource allocation method of a small cell base station considering interference according to an embodiment of the present invention.

Referring to FIG. 8, the small cell base station according to the present invention performs a procedure for monitoring small cells adjacent to each other using a sniff function. As such, the monitoring procedure may be repeated at predetermined time intervals, or may be real time or one-time.

Next, a process of identifying cell identification information (PCI information) of the neighboring cell and measuring the signal strength of the identified cell is performed along with monitoring the neighboring cell. In this case, the signal strength is measured using RSCP or CINR information through signal information received from the identified cell.

In addition, a procedure for separating and setting radio resources (subcarriers) to be used as communication services in a small cell base station for control and data is performed. In addition to this, the radio resources grouped separately are set to be divided into a plurality of radio resource groups (RBs), and each radio resource group is mapped and assigned with a number according to PCI information.

Thus, after the radio resources are separated for control and data, a procedure for allocating the control radio resources to the control-only radio resource allocation area separated for control is performed. At this time, as described above, a control radio resource is allocated exclusively (orthogonally).

At the same time, a procedure for allocating a radio resource for data to the data dedicated radio resource allocation area separated for data is performed. In this case, according to the above-described data radio resource allocation algorithm, radio resources are allocated to the data radio resource allocation region by giving priority to PCI having a low interference level based on the neighbor cell signal strength. In addition, when a radio resource for data is additionally allocated, the radio resource is allocated to an area set to the second priority.

Through this procedure, a limited cost-effective femtocell can be constructed that efficiently utilizes limited radio resources and allocates resources to guarantee performance while ensuring wireless quality.

The method of the present invention as described above may be embodied as a program and stored in a computer-readable recording medium (such as a CD-ROM, a RAM, a ROM, a floppy disk, a hard disk, or a magneto-optical disk).

While the specification contains many features, such features should not be construed as limiting the scope of the invention or the scope of the claims. In addition, the features described in the individual embodiments herein may be combined and implemented in a single embodiment. Conversely, various features described herein in a single embodiment may be implemented in various embodiments individually or in a suitable subcombination.

It is to be understood that, although the operations have been described in a particular order in the figures, it should be understood that such operations are performed in a particular order as shown, or that a series of sequential orders, or all described operations, . In some circumstances, multitasking and parallel processing may be advantageous. It should also be understood that the division of various system components in the above embodiments does not require such distinction in all embodiments. The above-described program components and systems can generally be implemented as a single software product or as a package in multiple software products.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. The present invention is not limited to the drawings.

100: small cell base station 110: detection module
120: allocation control module

Claims (15)

A radio resource allocation method considering interference of neighboring small cells in a mobile communication system environment,
(a) measuring information of neighboring small cells in the small cell base station; And
(b) The small cell base station separately allocates a control radio resource and a data radio resource, and allocates a control radio resource exclusively and a data radio resource has a low level of interference based on the measured neighboring small cell information. Allocating in order of area; Radio resource allocation method of a small cell base station considering the interference. The method of claim 1,
In the step (a)
The information of the peripheral small cell,
A method of allocating a radio resource of a small cell base station in consideration of interference, characterized in that it includes identification information of neighboring small cells and signal strength information of the identified small cells. 3. The method of claim 2,
The identification information of the small cell is PCI (Physical Cell Identity) information, the radio resource allocation method of the small cell base station considering the interference. 3. The method of claim 2,
The measurement of the peripheral small cell information,
A radio resource allocation method of a small cell base station considering interference, which is performed through a sniff function. The method of claim 1,
The small cell base station,
A radio resource allocation method of a small cell base station in consideration of interference, characterized in that the available radio resources are grouped and operated as a plurality of radio resource groups. The method of claim 5, wherein
And when the number of the radio resource groups is the same as the number allocated to the small cells of the cell list, the small cell identification information is used as the number of the radio resource group. 3. The method of claim 2,
In the step (b)
Control radio resource allocation method of a small cell base station considering the interference, characterized in that allocating exclusively with the neighboring small cells in an independent separate area so as not to overlap with the neighboring small cells. 3. The method of claim 2,
In the step (b)
The radio resource for data can be overlapped with the neighboring small cells, but the radio resource allocation of the small cell base station considering the interference characterized by allocating the region with the lowest interference level with the neighboring small cells based on the measured signal strength order. Way. The method of claim 1,
The mobile communication system is a 3GPP LTE network system, and the small cell base station is a femto cell base station (femto cell) base station radio resource allocation method considering the interference, characterized in that. A small cell base station for performing radio resource allocation processing in consideration of interference of neighboring small cells in a mobile communication system environment,
A detection module for measuring information of adjacent neighboring small cells; And
The control radio resources and data radio resources are separately allocated and allocated, and based on the neighbor small cell information measured by the detection module, the control radio resources are allocated exclusively and the data radio resources are allocated in the order of the region with the lowest interference level. Small cell base station comprising; an allocation control module. 11. The method of claim 10,
Information of the surrounding small cell measured by the detection module,
Small cell base station comprising the identification information of the adjacent small cell and the signal strength information of the identified small cell. The method of claim 11,
The allocation control module,
The control cell is a small cell base station characterized in that allocating exclusively with the neighboring small cells in an independent separate area so as not to overlap with the neighboring small cells. The method of claim 11,
The allocation control module,
The radio resource for data can be overlapped with the neighboring small cells, the small cell base station characterized in that the allocation level in the order of low interference level with the neighboring small cells based on the measured signal strength order. 11. The method of claim 10,
The allocation control module,
Groups the available radio resources to operate as a plurality of radio resource groups, and when the number of the radio resource groups is equal to the number allocated to the small cells only in the cell list, the small cell identification information is used as the number of the radio resource group. Small cell base station. A recording medium on which a program for performing radio resource allocation processing in consideration of interference of neighboring small cells in a small cell base station of a mobile communication system environment is recorded.
A procedure for measuring information of adjacent neighboring small cells, and
Separates and allocates the control radio data and the data radio resources, and based on the measured neighboring small cell information, the control radio resources are allocated exclusively and the data radio resources are allocated in the order of the region with the lowest interference level. A computer-readable recording medium having a program recorded thereon.

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