KR101510485B1 - Femto base station and method for managing resource thereof - Google Patents

Abstract

According to another aspect of the present invention, there is provided a mobile communication system including: a transmission / reception unit for receiving frequency resource allocation information from neighboring femto base stations through an access terminal; A controller for determining whether a neighboring femto base station resource overlaps with its own radio resource based on the received frequency resource allocation information and transmitting the collision information to an external entity through the transmitter / And a femto base station.

Description

[0001] FEMTO BASE STATION AND METHOD FOR MANAGING RESOURCE THEREOF [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to a femto base station and a resource management method in a mobile communication system.

Second generation mobile communication refers to digital transmission and reception of voice, including CDMA and GSM. In addition to the GSM, GPRS has been proposed, which is a technique for providing a packet switched data service based on the GSM system.

Third Generation Partnership Project (3GPP) has developed a mobile communication system (IMT-2000) technology and developed a radio access technology (Radio Access) Technology: RAT). As such, the IMT-2000 technology and the radio access technology (RAT), for example, WCDMA, are collectively referred to as Universal Mobile Telecommunication System (UMTS) in Europe. UTRAN is an abbreviation of UMTS Terrestrial Radio Access Network.

Meanwhile, the third generation mobile communication has evolved into a fourth generation mobile communication.

The 4G mobile communication technology has been proposed as a Long-Term Evolution Network (LTE) technology standardized by 3GPP and IEEE 802.16 technology standardized by IEEE. In the LTE, the term Evolved-UTRAN (E-UTRAN) is used.

In the 4th generation mobile communication technology, Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) has been introduced. OFDM uses a plurality of orthogonal subcarriers. OFDM utilizes the orthogonality property between IFFT (inverse fast Fourier transform) and FFT (fast Fourier transform). The transmitter performs IFFT on the data and transmits it. The receiver performs an FFT on the received signal to recover the original data. The transmitter uses an IFFT to combine multiple subcarriers, and the receiver uses a corresponding FFT to separate multiple subcarriers.

Meanwhile, attempts have been made to increase the cell capacity to support high-capacity services and interactive services such as multimedia contents and streaming in the third or fourth generation mobile communication systems.

There has been an approach to increase the cell capacity by using higher frequency bands and decreasing the cell radius. When a cell having a small cell radius, such as a pico cell, is applied, a higher frequency band than that used in the conventional cellular system can be used, and more information can be transmitted. However, there is a disadvantage that it requires a lot of base stations in the same area, which is costly.

Recently, a femtocell has been proposed to increase the cell capacity by using such a small cell.

The femtocell means providing a small wireless environment by installing an ultra-small, low-power base station in a house / office. The femtocell can improve the quality of service by improving the indoor coverage area and capacity, and it is expected that the femtocell will completely settle the next generation mobile communication system through providing data service.

The femtocell is being standardized as Home eNodeB in 3GPP WCDMA and LTE group, and research on femtocell is underway in 3GPP2.

Various schemes have been proposed for implementing such a femtocell in an existing mobile communication network, as shown in Figs. 1 and 2. Fig.

1 is a diagram illustrating an example of a femtocell-based network structure according to the related art.

As shown in FIG. 1, a macro base station (M-BS) serving as a wide area and a plurality of femto-BS (f-BS) installed as a user base are displayed have.

The femto base station (f-BS) is connected to a femtocell control station (FNC) via the Internet and is controlled by the femto base station (f-BS).

The terminal measures a signal of neighboring cells and transmits the signal to its femto base station. The femto base station recognizes and manages the neighboring cell through the neighboring cell. The femto base stations exchange information through a direct link or an indirect link through the FNC. Information is exchanged between the femto base station and the macro base station through an FNC and an RNC (Radio Network Controller) or a Mobility Management Entity (MME) for controlling the femto base station in a mobile communication network.

2 is a view illustrating another example of a femtocell-based network structure according to the related art.

As shown in FIG. 2, the femto BSs (f-BSs) exchange information through a direct link or MME, unlike FIG. In addition, the macro base station (M-BS) and the femto base station (f-BS) exchange information through the MME.

3 shows an example of a frame structure used in a femtocell and a macrocell according to the related art.

Referring to FIG. 3, each superframe is divided into four radio frames having the same size. The superframe may include a superframe header. The superframe header contains essential control information that the UE must acquire during initial network entry or handover, and plays a similar role as the broadcast channel (BCH) in LTE technology. The super frame header can be allocated to a first radio frame among a plurality of radio frames constituting a super frame. The number of subframes constituting one frame may be changed to 5, 6, 7, or 8 according to the bandwidth or CP length of the system, and the number of symbols of OFDMA constituting one subframe may be 5, 6, 7, or 9, respectively. In FIG. 3, the case where the CP is 1 / 8Tb (Tb: Useful OFDMA symbol time) when the dual bandwidth is 5, 10, or 20 MHz is an example.

The frame structure illustrated in FIG. 3 may be applied to a time division duplexing (TDD) scheme or a frequency division duplexing (FDD) scheme. The TDD scheme uses the entire frequency band as an uplink or a downlink, and distinguishes uplink and downlink transmission in a time domain. In the FDD scheme, uplink and downlink transmissions occupy different frequency bands, .

Each subframe is divided into at least one frequency partition. Each frequency partition is composed of at least one physical resource unit (PRU). Each frequency section includes a Localized PRU and / or a Distributed PRU. Each frequency section can be used for purposes such as partial frequency reuse (FFR).

The physical resource unit (PRU) is a basic physical unit for resource allocation that includes N consecutive OFDM symbols and P consecutive subcarriers. A Localized Resource Unit (LRU) is a basic logical unit for distributed resource allocation and local resource allocation. The LRU includes P * N subcarriers. The LRU includes the pilots used in the PRU. Therefore, the number of suitable subcarriers in one LRU depends on the number of allocated pilots.

4 is a structure of one IEEE 802.16m (or Advanced Air Interface) synchronization channel (hereinafter, referred to as Advanced-Preamble, A-Preamble) among technologies of the fourth generation mobile communication system. Four primary or secondary preambles that extend one OFDMA symbol within a 20ms superframe are located, and the SFH to which the essential control information is transmitted is transmitted after the secondary preamble symbol. In case of PA-Preamble, it is transmitted in frequency reuse 1. In case of SA-Preamble, it is transmitted in frequency reuse 3. Accordingly, in the case of the SA-Preamble, segments are assigned to three 1-to-1 mappings according to three sector indexes.

In the above-mentioned prior art, a femto base station (BS) is installed by a user, has a smaller coverage than a macro base station, and provides services to a small number of predetermined users.

Therefore, the location distribution of the user greatly affects the interference relationship between the femto base stations. Unnecessary redundant installation and dense installation can be caused, and in the case of a residential / office concentrated area, there is a problem that the interval between the installed femto base stations is narrowed.

Also, in the case of a macro base station installed in an outdoor area, it is possible to calculate the distance between a macro base station installed in an upper RNC by using GPS information, that is, latitude and longitude, You can set the value of the resource.

However, since the neighbor relationship of the femto base station is irregular according to the types of the obstacles in the room, it is difficult to grasp only the GPS position information. Also, since the femto base station is installed indoors mainly in an office, a home, etc., it may be difficult to accurately determine an absolute position because reception of the GPS signal is difficult.

In addition, the environment in which the femto base station is installed has many obstacles such as walls, and the femto base station has an irregular cell structure due to a different path loss exponent depending on the type of the obstacle. .

In addition, when the femto base stations are distributed in a building or an apartment, a vertical up-and-down relationship may occur instead of a horizontal cell structure.

For the above reasons, it is difficult to set an effective resource to reflect the actual cell structure and the interference situation only by the location information in the resource setting to operate by avoiding interference that may occur between the base stations. In addition, it is difficult to set up an efficient resource only by grasping the neighbor relationship, and the user's location distribution in allocating resources must also be considered.

Accordingly, an object of the present invention is to solve the above-mentioned problems. That is, an object of the present invention is to enable a femto base station to efficiently perform resource allocation while avoiding interference.

In order to achieve the above object, according to the present invention, there is provided a mobile communication system comprising: a transmission / reception unit for receiving frequency resource allocation information from neighboring femto base stations through an access terminal; A controller for determining whether a neighboring femto base station resource overlaps with its own radio resource based on the received frequency resource allocation information and transmitting the collision information to an external entity through the transmitter / And a femto base station.

The frequency resource allocation information may include at least one of frequency resource information, time resource information, and an ID of the neighbor femto BS.

The transceiver may further transmit at least one of its own frequency resource allocation information and frequency resource allocation information of the neighbor femto BS.

In order to achieve the above object, the present invention provides a radio communication system including a transceiver for broadcasting frequency resource allocation information including its own radio resource and an ID to one or more entities and receiving information on allowed radio resources, And a processor for re-adjusting the radio resources of the femto base station based on the information about the radio resources. The information on the allowed radio resources may be based on information fed back by neighboring femto base stations.

The present invention enables a femto base station (f-BS) to appropriately respond to interference. The present invention allows a femto base station to allocate as much allocatable resources as possible according to the location distribution of a user equipment (UE). In addition, the present invention minimizes the interference problem that may occur by allocating resources redundantly between femto base stations.

The present invention is applied to a femtocell. However, the present invention is not limited to this and can be applied to all communication systems and methods to which the technical idea of the present invention can be applied.

It is noted that the technical terms used herein are used only to describe specific embodiments and are not intended to limit the invention. It is also to be understood that the technical terms used herein are to be interpreted in a sense generally understood by a person skilled in the art to which the present invention belongs, Should not be construed to mean, or be interpreted in an excessively reduced sense. Further, when a technical term used herein is an erroneous technical term that does not accurately express the spirit of the present invention, it should be understood that technical terms that can be understood by a person skilled in the art are replaced. In addition, the general terms used in the present invention should be interpreted according to a predefined or prior context, and should not be construed as being excessively reduced.

Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In the present application, the term "comprising" or "comprising" or the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

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

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like or similar elements throughout the several views, and redundant description thereof will be omitted. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings. The spirit of the present invention should be construed as extending to all modifications, equivalents, and alternatives in addition to the appended drawings.

Hereinafter, the term 'terminal' is used, but the terminal may be referred to as a UE (User Equipment), ME (Mobile Equipment), or MS (Mobile Station). The UE may be a portable device having a communication function such as a mobile phone, a PDA, a smart phone, a notebook, or the like, or may be a portable device such as a PC or a vehicle-mounted device.

Embodiments of the present invention will now be described with respect to resource allocation between a newly installed femto base station and a previously installed and operating femto base station. In addition, embodiments of the present invention describe transmission resource status messages. According to the embodiment of the present invention, since the arrangement of the femto base stations is difficult to accurately grasp, the FRSM (Femto Resource Status Message) is used to readjust the initially allocated resources according to the interference of the femto base stations. Further, the transmission resource status message (FRSM) is used for reordering the additional resource after allocating additional resources to a specific femto base station. In addition, the transmission resource status message (FRSM) is also used for receiving additional resources.

Hereinafter, the details will be described with reference to the drawings.

5 is an exemplary view showing a method according to the first embodiment of the present invention.

As shown in FIG. 5, the newly installed first femto base station (or first home node B) 201 acquires the information of the macro cell 300 in the initial operation. The macro cell information may be obtained from a control channel such as system information, a synchronization channel, and a broadcast channel transmitted from the macro base station 300. For this, the femto base station and the macro base station are wirelessly connected according to IEEE 802.16. Or the femto base station and the macro base station are connected through the core network shown in FIG.

The first femto BS 201 transmits information of the macrocell 300 when it registers with a femtocell control station (FNC) or a mobility management entity (MME) 530.

Then, the femtocell control station (FNC) or the MME 530 allocates an initial resource to the first femto BS 2011 based on the macro cell information.

After the initial resource is allocated, the first femto BS 201 transmits a message related to its own resource, for example, a resource status message (FRSM). That is, the first femto base station 201 broadcasts a resource status message (FRSM). The information about the resource includes a frequency and a time. Also, the resource status message includes the ID of the first femto BS and information on resources allocated thereto. At this time, the FNC / MME 530 may schedule transmission of the resource status message to prevent other femto BSs other than the first femto BS from simultaneously transmitting the resource status message (FRSM). This is because, as shown in FIG. 9, a terminal in a neighbor femtocell is in service and can not receive and read the resource status message (FRSM).

The terminal located in the first femto base station and the neighboring second femto base station transmits the resource related message to the neighboring second femto base station 202 and the second femto base station 202 transmits the resource related message Determine whether or not they overlap with their resources on a basis.

Then, when the second femto BS 202 overlaps its own resources with the resources of the first femto BS 201, the second femto BS 202 requests reallocation of resources to the femtocell control station FNC or the MME 530 .

As described above, the first embodiment of the present invention resolves the interference problem when the femto base station is newly installed according to an arbitrary arrangement, and enables the resources to be allocated appropriately.

6 is an exemplary view showing a method according to a second embodiment of the present invention.

As shown in FIG. 6, when a second femto base station (or a second home node B) suddenly increases interference due to a new addition of the first femto base station 201, or when a wireless environment changes, And informs the femtocell control station (FNC) or the MME 530 of the change of the environment. Herein, the increase of the interference or the change of the wireless environment can be grasped by the terminal. That is, when the interference by the first femto base station increases and the wireless environment changes, the terminal 100 informs the second femto base station 202 of its own, and the second femto base station 202 transmits the notification to the femtocell control station (FNC) or the MME 530.

Then, the femtocell control station (FNC) or the MME 530 reallocates resources as needed.

As described above, the second embodiment of the present invention solves the interference problem caused by the arbitrary arrangement of the femto base stations.

7 is an exemplary view showing a method according to a third embodiment of the present invention.

7, the first femto base station 201, which requires additional resources, calculates necessary additional resources and transmits the additional resources to the femtocell control station (FNC) / MME 530 ).

The femtocell control station (FNC) / MME 530 allocates additional resources in response to the request.

Then, the first femto base station 201 transmits a message related to the allocated additional resource, for example, a resource status message (FRSM).

Then, the terminal 100 located within the coverage of the first femto base station 201 and the neighboring second femto base station 202 transmits the resource related message to the neighboring second femto base station 202, The second femto base station 202 determines whether or not it overlaps with its own resource based on the resource related message.

When the second femto BS 202 overlaps with its own resources, the second femto BS 202 requests reallocation of resources to the femtocell control station (FNC) / MME 202.

As described above, the third embodiment of the present invention solves the interference problem due to the arbitrary arrangement of the femto base stations, and enables the resources to be appropriately allocated.

8 is an exemplary view showing a method according to a fourth embodiment of the present invention.

As shown in FIG. 7, according to the fourth embodiment of the present invention, the first femto BS 201 requiring additional resources calculates a necessary additional resource and transmits a message related to the required additional resource, for example, a transmission resource status message (FRSM ).

The terminal 100 located in the coverage of the first femto BS 201 and the neighboring second femto BS 202 delivers the resource related message to the neighboring second femto BS.

The neighboring second femto base station 202 notifies the femtocell control station (FNC) / MME 530 of whether or not the neighboring second femto base station 202 overlaps with its own resource, together with the information on the desired additional resource of the first femto BS 201, Lt; / RTI >

Based on whether the femtocell control station (FNC) / MME 530 overlaps with the second femto BS 202 and the desired additional resource information of the first femto BS 201, (201).

9 is a diagram illustrating an example of a scenario related to transmission of a resource status message.

9 (a) shows a situation where all terminals can receive a resource status message. That is, the MSs MS1, MS2, and MS3 of the adjacent neighbor femtocell can detect the resource status message (FRSM) transmitted from the target femtocell.

The MSs MS1, MS2, and MS3 detect a resource status message (FRSM) as an idle state in which no service is provided and notify them to their serving femto base stations f-BS1, f-BS2, and f-BS3.

Each of the serving femto base stations f-BS1, f-BS2, and f-BS3 adds the serving femto base station if the target femto base station does not exist in its neighboring cell list. Each of the serving femto base stations f-BS1, f-BS2, and f-BS3 informs the FNC / MME when the target femtocell overlaps and uses the transmission resource in use.

After receiving the information from each femto base station, the FNC / MME notifies the neighbor cell list and the available transmission resources to the target femtocell by combining the neighbor cell list and the redundant transmission resource information.

Next, FIG. 9B shows a case where there is no terminal in the area of the resource status message (FRSM). If the FNC / MME does not receive a report from the neighboring femto BSs after a predetermined time elapses (i.e., when the timer expires) after transmitting the resource status message (FRSM), the target femto BS transmits a transmission resource Can be used.

Next, FIG. 9 (c) shows a situation where some UEs in service can not detect a resource status message (FRSM). A terminal capable of detecting a resource status message (FRSM) among the terminals operates as shown in FIG. 9 (a). In case of a terminal that can not detect the resource status message (FRSM) due to service, if the interference level increases, CQI (Channel Quality Information) is fed back to the serving femto base station, The base station reports this to the FNC / MME. That is, since a mobile terminal receiving a service in the indoor environment can be assumed to have low mobility, a sudden decrease in SINR (change in service quality) may determine that there is a femto base station sending a resource status message (FRSM) in the vicinity.

Since the FNC / MME schedules transmission of the resource status message in order to prevent a plurality of femto base stations from simultaneously generating a resource status message (FRSM), the FNC / MME may notify the neighboring cell list of the target femto BS and the serving femto BS neighbor cell list, and notifies the femto base station of the available transmission resources again.

The method according to the present invention described so far can be implemented in software, hardware, or a combination thereof. For example, a method in accordance with the present invention may be implemented in software (e.g., flash memory, hard disk, etc.) that can be stored in a storage medium And may be implemented as codes or instructions within the program. This will be described with reference to FIG.

10 is a configuration block diagram of a terminal 100 and a femto base station 200 according to the present invention.

As shown in FIG. 9, the terminal 100 includes a storage unit 110, a controller 120, and a transmission / reception unit 130. The femto base station 200 includes a storage unit 210, a controller 220, and a transmission / reception unit 230.

The storage means 110 and 220 store the method according to the first to fourth embodiments shown in Figs.

The controllers 120 and 220 control the storage units 110 and 210 and the transceivers 130 and 230. Specifically, the controllers 120 and 220 execute the methods stored in the storage means 110 and 210, respectively. The controllers 120 and 220 transmit the above-described signals through the transceivers 130 and 230, respectively.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, May be modified, modified, or improved.

FIG. 1 illustrates an example of a conventional femtocell-based network structure. Referring to FIG.

2 is a view illustrating another example of a femtocell-based network structure according to the related art.

3 shows an example of a frame structure used in a femtocell and a macrocell according to the related art.

4 shows a superframe structure according to the prior art.

5 is an exemplary view showing a method according to the first embodiment of the present invention.

6 is an exemplary view showing a method according to a second embodiment of the present invention.

7 is an exemplary view showing a method according to a third embodiment of the present invention.

8 is an exemplary view showing a method according to a fourth embodiment of the present invention.

9 is a diagram illustrating an example of a scenario related to transmission of a resource status message.

10 is a configuration block diagram of a terminal 100 and a femto base station 200 according to the present invention.

Claims (15)

A method for managing resources in a first femto base station, The first femto base station transmits additional resource allocation information from a second femto base station requiring additional resources to a terminal located at a position including a part of a coverage of the first femto base station and a part of the area of the second femto base station Wherein the terminal receives the additional resource allocation information from the second femto base station and transmits the received additional resource allocation information to the first femto base station, ) Information and time information of additional resources needed by the second femto base station; Determining whether an additional resource required by the second femto base station overlaps with a radio resource of the first femto base station based on the additional resource allocation information received by the first femto base station through the terminal; And When the radio resource of the first femto base station overlaps with the additional resource required by the second femto base station, the first femto base station controls the first femto base station and the second femto base station And requesting the second femto base station to allocate a resource to the second femto base station excluding the overlapped resources among the additional resources required by the second femto base station Wherein the first femto base station comprises a first femto base station and a second femto base station. delete The method of claim 1, wherein the external entity Wherein the femto base station is a femtocell control station (FNC) or a mobility management entity (MME). delete Receiving additional resource allocation information from a second femto base station requiring additional resources through a terminal at a location including a part of a coverage of a first femto base station and a part of an area of the second femto base station, Receives the additional resource allocation information from the second femto base station and transmits the additional resource allocation information to the first femto base station, and the additional resource allocation information includes frequency information of additional resources required by the second femto base station, The base station including at least one of time information of additional resources required by the base station; And And a processor for determining whether the additional resources required by the second femto base station and the radio resources of the first femto base station are overlapped based on the additional resource allocation information received by the first femto base station through the terminal, If the radio resource of the first femto base station overlaps with the additional resource required by the second femto base station, the transceiving unit may transmit an indicator for instructing resource overlap to an external entity controlling the first femto base station and the second femto base station the second femto base station transmits a request to the second femto base station to allocate a resource to the second femto base station excluding resources overlapping the second femto base station. delete delete delete delete delete delete delete delete delete delete

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