KR20140006282A - Method and system of allocating radio resource in wireless communication system including at least one femtocell and macrocell - Google Patents

Abstract

In a radio resource allocation method in a wireless communication system including a macro cell and at least one femto cell, the radio resource allocation method includes a macro cell band allocated as a radio resource of the macro cell and a white space which is an empty radio resource. Identifying; Allocating radio resources from the macro cell band for neighbor cell discovery between the at least one femto cell in a normal resource allocation mode; And allocating radio resources from the idle band for data communication of each of the at least one femto cell in the normal resource allocation mode.

Description

TECHNICAL AND ALLOCATING RADIO RESOURCE IN WIRELESS COMMUNICATION SYSTEM INCLUDING AT LEAST ONE FEMTOCELL AND MACROCELL}

The present invention relates to a technique for supporting a base station in a wireless communication system including a macro cell and at least one femto cell, and more particularly, to wirelessly guarantee a user's data quality of service using a macro cell band and an idle band. Resource allocation technology.

Radio resource allocation techniques can be applied to efficiently use limited radio resources. The wireless communication system includes a macro cell and a femto cell, and the macro cell and the femto cell are allocated radio resources from a common macro cell band.

In addition, the radio resource allocation scheme applied in the wireless communication system can efficiently use limited radio resources using cognitive radio technology. In the cognitive radio resource allocation scheme, radio resources are allocated by using a common macro cell band and an idle band. The idle band may be a frequency band such as a TV white space band.

In a radio resource allocation method in a wireless communication system including a macro cell and at least one femto cell according to an embodiment of the present invention, the radio resource allocation method includes a macro cell band allocated to radio resources of the macro cell and an empty space; Identifying a white space that is a radio resource; Allocating radio resources from the macro cell band for neighbor cell discovery between at least one femto cell in a normal resource allocation mode; And allocating radio resources from the idle band for data communication of each of the at least one femto cell in the normal resource allocation mode.

The radio resource allocation method may further include a resource management center distinguished from the macro cell and the at least one femto cell, information related to the allocation of the macro cell band stored in the resource management center, The method may include identifying the macro cell band and the idle band based on information related to transmission power in the macro cell band, information related to whether the idle band is used, and information related to transmission power in the idle band. .

The radio resource allocation method may include information regarding a classification and an access method corresponding to each of the femtocells and information related to whether the idle band is used by a femtocell base station corresponding to the at least one femtocell in the normal resource allocation mode. And transmitting the radio resource to the resource management center in the macro cell band and allocating the radio resource from the macro cell band.

The radio resource allocation method includes a resource management center for the femto cell base station corresponding to the at least one femto cell in the normal resource allocation mode, information related to whether the idle band is used, and information related to transmission power in the idle band. And receiving the radio resources from the macro cell band from the macro cell band.

In the radio resource allocation method, a femto cell base station corresponding to the at least one femto cell in the normal resource allocation mode transmits information on a classification and an approach corresponding to each of the femto cells to the resource management center in the idle band. And allocating the radio resource from the idle band.

The radio resource allocation method may further include changing the normal resource allocation mode to a hybrid resource allocation mode.

The radio resource allocation method may be a step of changing the normal resource allocation mode to the hybrid resource allocation mode based on a required quality of service of each of the at least one femto cell in the idle band.

The radio resource allocation method includes selecting the radio resource from the macro cell band based on a required quality of service of each of the at least one femto cell in the hybrid resource allocation mode; And allocating the selected radio resource as a radio resource for data communication of each of the at least one femto cell in the hybrid resource allocation mode.

The radio resource allocation method may include information related to the allocation of the macro cell band stored in the resource management center in the hybrid resource allocation mode, information related to transmission power in the macro cell band, and information related to whether the idle band is used. The step of selecting the radio resource from the macro cell band based on.

The radio resource allocation method includes the resource management center in which the femto cell base station corresponding to the at least one femto cell corresponds to each of the femto cells in the macro cell band in the hybrid resource allocation mode. And allocating the radio resource from the macro cell band.

1 is a diagram illustrating a method of operating a radio resource of a femtocell according to an embodiment of the present invention.
2 is a diagram illustrating a radio resource use of a femto cell according to an embodiment of the prior art.
3 is a view showing the structure of a mobile wireless access system according to an embodiment of the present invention.
4 is a diagram illustrating a radio resource use mode of a femto cell base station according to an embodiment of the present invention.
5 is an operation flowchart illustrating an initial network access procedure of a terminal to a CR-deactivated femtocell in a wireless access system according to an embodiment of the present invention.
6 is a flowchart illustrating an initial network access procedure of a terminal to a CR-enabled femtocell in a wireless access system according to an embodiment of the present invention.
7 is a flowchart illustrating a handover procedure of a terminal to a CR-deactivated femtocell in a wireless access system according to an embodiment of the present invention.
8 is a flowchart illustrating a handover procedure of a terminal to a CR-enabled femto cell in a wireless access system according to an embodiment of the present invention.
9 is a flowchart illustrating an idle channel switching procedure in a wireless access system according to an embodiment of the present invention.
10 is a flowchart illustrating a resource allocation procedure between a resource management center and a femtocell base station in a wireless access system according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The femto cell base station / terminal according to the present invention supports the same function as a conventional macro cell base station / terminal and simultaneously uses a CR (cognitive radio) function in an unlicensed band such as an industrial scientific and medical (ISM) band or TV idle band. Can be operated. However, in the embodiment of the present invention described below, it is assumed that the TV idle band is a target frequency band.

First, the structure of the wireless access system according to the present invention will be described. Referring to FIG. 3, a wireless communication system according to an embodiment of the present invention includes a terminal, a femto cell / macro cell base station, and a resource management center (RMC). A macro cell base station is a base station that manages a macro cell and provides general cellular service to a user in a licensed band (hereinafter referred to as a 'macro cell band'). Femto cell base stations are small base stations that provide a high level of data service to indoor users. In an embodiment of the present invention, since the radio access system uses the TV idle band as the target frequency band in addition to the macro cell band, the radio access system interworks with a TV band database system unlike a femtocell network. The TV band database system is a system for storing / managing the geographical location and activity of the PU in the TV band. The resource management center is a device that manages configuration settings of all femtocells in a network.1) Manages femtocell operation radio resources and configuration settings for a group of femtocell base stations located within a transmission range of one macro cell, or 2 Manage operational radio resources and configuration settings of femto cell base stations within multiple macro cell transmission ranges. Specifically, the resource management center accesses the TV band database system to obtain a TV idle band channel list that can be used within each macro cell coverage managed by the resource management center, and manages the following femto cell configuration settings.

Management of TV idle band channel usage by femtocell: operation TV idle band channel list, transmission power

Radio resource management in the macro cell band: allocation radio resource information, transmission power

Sensing management of each femtocell base station and TV idle band channel state information management for obtaining TV idle band channel state information

According to the present invention, a femtocell base station operates to allocate and use a radio resource of a macro cell band when a service QoS cannot be guaranteed to a user through an active TV idle band channel. To this end, the resource management center allocates radio resources in the macro cell band in cooperation with the macro cell base station and the corresponding femto cell base station. In addition, the resource management center manages / controls the sensing of the femtocell base station to detect heterogeneous systems using TV idle band channels. Each femto cell base station measures the channel status of TV idle band channels according to the command of the resource management center and reports the result to the resource management center. Based on the result, the resource management center monitors the TV by location in the macro cell. Stores idle band channel state information. The resource management center may be built in the macro cell base station or through a separate device outside the macro cell base station. Resource management centers, macro cell base stations and femto cell base stations are connected via a wired backhaul link.

Here, it should be noted that the resource management center manages the operation channel list in the ISM band when the mobile radio access system uses the ISM band as the target frequency band together with the macro cell band.

Next, a radio resource operating method of a femto cell base station according to an embodiment of the present invention will be described. A femtocell base station according to an embodiment of the present invention uses a macro cell band and a TV idle band channel at the same time. As shown in FIG. 4, a 'normal resource allocation mode' and a 'hybrid resource allocation mode' are shown. mode) is operated in two radio resource allocation modes. In the normal resource allocation mode, the radio resources of the minimum macro cell band are used to support neighbor cell discovery of the same terminal as in the conventional macro cell network. In the TV idle band channel, the control signal after the terminal enters the femto cell And transmit and receive data. The hybrid resource allocation mode is a mode in which a femtocell is operated when a service QoS cannot be guaranteed to a user through an idle TV idle band channel. The hybrid resource allocation mode is used to transmit and receive control signals and data by allocating a portion of radio resources of a macro cell band. Mode. For the hybrid resource allocation mode, the resource management center allocates radio resources in the macro cell band in cooperation with the macro cell base station and the corresponding femto cell base station.

A femtocell according to an embodiment of the present invention operates in the following channel structure in a macro cell band and a TV idle band channel. First, in the macro cell band, a minimum control signal procedure for femto cell discovery and TV idle band channel configuration information broadcasting is performed, and in the TV idle band channel, a control signal procedure and CR related signaling procedures and data for other cellular services are performed. Perform the transfer. In the mobile radio access system, each base station transmits a preamble including cell type and cell identifier information located in the first symbol section of a transmission frame to support network entry and handover of the terminal. The terminal receives a preamble transmitted from a neighbor base station and performs a neighbor cell discovery operation. Accordingly, the femto cell base station according to the embodiment of the present invention broadcasts the following femto cell configuration information in the macro cell band.

division Femtocell configuration information, including Preamble Transmission Cell delimiter (Cell ID)
Femto cell approach (open / closed / hybrid) System information broadcasting Femto cell base station identifier (BS ID and CSG ID)
Action TV idle band channel configuration information
CR enabled / disabled
-TV idle band channel information in operation (optional)
Uplink control channel configuration information in the macro cell band (optional)
TV idle band channel switching notification (optional)
-TV idle band channel information to change
Channel switching start time

In the table, the 'CR-activated / deactivated state' is an indicator indicating whether the femtocell base station is operating the CR function on a TV idle band channel. If the femto cell base station is CR-enabled, the femto cell base station includes operating TV idle band channel information in a system information message. When the femto cell base station is in the CR-deactivation state, the terminal initially entering the network should attempt initial network entry through the uplink control channel of the macro cell band in the same manner as in the existing macro cell network. do. Accordingly, the femtocell base station in the CR-deactivation state includes 'uplink control channel configuration information in the macro cell band' in the system information message. Meanwhile, when the femto cell operates in the hybrid resource allocation mode, the radio resources of the allocated macro cell band are used for transmitting and receiving control signals and data.

Femtocell control information transmitted through the TV idle band channel is shown in the following table.

division Femtocell configuration information, including Cellular service related All system information except system information transmitted in the macro cell band
Unicast control message between femtocell and terminal
Frame composition information CR behavior related Sensing control message
Quiet period assignment message
Channel switching confirmation message

Referring to the table, all femtocell system information messages except for the system information message broadcast in the macro cell band are transmitted in the TV idle band channel, and all unicast control messages are exchanged between the femtocell and the user terminal. In addition, as shown in Table 2, control messages for CR operation are exchanged in the TV idle band channel.

Hereinafter, an operation procedure of a femtocell base station and a terminal according to the present invention configured as described above will be described with reference to the drawings. 5 and 6 are flowcharts illustrating an initial network entry operation of a terminal. The femtocell base station powers off the CR transceiver to prevent PU protection and interference to neighboring femtocells and other systems when there is no UE connected to it. The operation procedure when the UE initially accesses the CR-inactive femto cell is shown in FIG. 5. The femto cell base station broadcasts the preamble and system information message in the macro cell band as in the macro cell base station. Upon detecting the femto cell, the terminal transmits an initial network connection request message, and the femto cell base station receiving the femto cell allocates radio resources of a TV idle band channel from a resource management center to activate a CR transceiver. Subsequently, the femto cell base station broadcasts the TV idle band channel information through its macro band and transmits a network connection response message including the TV idle band channel information to the accessing terminal. The terminal receiving the network connection response message powers on the CR transceiver, sets the terminal according to the received TV idle band channel information, and starts data transmission. On the other hand, the femtocell base station, which is CR-active (CR-active) because one or more terminals are already connected, broadcasts the operation TV idle band channel information in a system information message transmitted in the macro cell band (see FIG. 6). . Upon receiving this, the terminal immediately powers on the CR transmitter and proceeds with an initial network entry signal procedure through the received TV idle band channel.

 7 and 8 illustrate a handover procedure of a terminal connected to a macro cell to a femtocell. The terminal, which has determined handover to the CR-deactivated femto cell, transmits a handover request message to the macro cell base station to which it is connected. Subsequently, the macro cell base station transmits a handover request message to the target femto cell base station in the same manner as the existing handover procedure, and the received femto cell base station is allocated radio resources of the TV idle band channel from the resource management center and receives the CR transceiver. It activates and delivers the operating TV idle band channel information to the serving macro cell base station through a handover response message. The macro cell base station transmits the received TV channel information of the target femto cell base station in the handover command message. Then, the terminal powers on the CR transceiver, sets according to the received TV idle band channel information, and starts the access signal procedure and data transmission to the target femtocell. The femto cell base station hands over to a neighbor cell (macro cell or femto cell) and powers off the CR transceiver when there is no terminal connected to it. The femto cell base station reports the suspension of the operation TV idle band channel to the resource management center. . The UE also powers off the CR transceiver to reduce power consumption after handover from the femto cell to the macro cell.

9 shows a TV idle band channel switching operation procedure. The femtocell base station, which has decided to change the TV idle band channel due to the appearance of the PU or the deterioration of the operating TV idle band channel, requests the resource management center to allocate a new TV idle band channel. The femtocell base station, which has been allocated a new TV idle band channel (CH 10 in FIG. 9) from the resource management center, transmits a channel switching request message including channel information to be changed and an action time through the macro band to the terminal. At this time, for reliable transmission of the channel switching request message, the channel switching request message is transmitted through the macro cell band instead of the current operating channel (CH 3 in FIG. 9), and the channel switching response message is also transmitted through the macro cell band. After the terminal completes channel switching to the new TV idle band channel (CH 10 in FIG. 9), the terminal transmits a channel switching complete message to the new TV idle band channel and performs data transmission and reception. However, as shown in the example of FIG. 9, when the femtocell base station is using one TV idle band channel, service connection is disconnected during the channel switching period. If a femtocell user is in real-time traffic service, this disconnection of service leads to poor quality of service. Therefore, in the mobile radio access system according to the present invention, when the resource management center allocates a new TV idle band channel, it temporarily assigns radio resources of a macro cell band that can be used by the femtocell base station during the TV idle band channel change period. .

Next, a radio resource allocation procedure between a resource management center and a femto cell base station according to an embodiment of the present invention will be described. The femtocell base stations under resource management center management request radio resource allocation to the resource management center when the following event occurs.

Request CR activation on TV idle band channel due to terminal initial network entry or handover

The channel situation of the current operating TV idle band channel deteriorated, requiring changing the TV idle band channel

Request additional TV idle band channel assignments to ensure service QoS for femtocell users

In addition, the resource management center may reallocate radio resources of a plurality of femto cells using the TV idle band channel at a time when it is necessary to stop transmission on the TV idle band channel due to the appearance of the PU. However, in the embodiment of the present invention described below, the radio resource allocation procedure will be described by focusing on the resource allocation request event of the femto cell base station. Referring to FIG. 10, the femtocell base station transmits its CR capability by turning on the CR transceiver and transmitting a 'CR-Activation Request' message to the resource management center and using TV idle at the current location from the resource management center. Obtain band channel information. At this time, the 'CR-Activation Request' message structure is shown in Table 3.

Information element Description Femto bs location Geographic location of femtocell base station Maximum number of supportable channels Maximum number of TV idle band channels that can be supported by a femtocell base station

In the table, 'maximum number of supportable channels' is determined according to the number of TWVS transceivers installed in the femto cell base station and the capability of each CR transceiver.

Receiving the 'CR-Activation Request' message from the femtocell base station, the resource management center accesses the TV band database system and displays a list of TV idle band channels available at the location of the femtocell base station and the maximum possible transmit power information of the femtocell base station. Acquire. Subsequently, the resource management center transmits a 'CR-Activation Response' message including the information of Table 4 to the femtocell base station.

Information element Description Number of available TV idle band channels Number of TV idle band channels available (N) Available TV Idle Band channel information list

 TV idle band channel index TV idle band channel separator  -Expiration time Expiration time of TV idle band channel  -Tx. power limit Transmit Power Limit of Femto Cell Base Station

Upon receiving the 'CR-Activation Response' message, the femtocell base station measures the channel state for the available TV idle band channels. At this time, since the femtocell base station has not been allocated radio resources of the TV idle band, the TV idle band transmitter maintains the turn-off state. At this time, the femtocell base station completes the CR activation procedure before the terminal enters (or handovers) the femtocell in order to shorten the handover time of the terminal and increase the accuracy of channel measurement. Channel measurements may be performed beforehand. Subsequently, when the femto cell base station receives the handover request message of the terminal from the macro cell base station, it transmits a 'Resource Allocation Request' message including the following information to the resource management center and requests radio resource allocation.

Information element Description Required cell capacity Cell transfer capacity required Number of TV idle band channels

Channel measurement reports

 TV idle band channel index TV idle band channel separator  Average RSS (received signal strength) Average of RSS Measures

In the table, 'required cell capacity' is a cell transmission capacity required for a femto cell requesting resource allocation to provide a data service to a lower terminal.

The resource management center receiving the 'Resource Allocation Request' message allocates radio resources of the TV idle band channel and the macro cell band to the corresponding femto cell base station and transmits a 'Resource Allocation Response' message including the allocation information to the femto cell base station. . The message structure of 'Resource Allocation Response' is shown in Table 6.

Information element Description Resource allocation mode 0: Normal 1: Hybrid Number of allocated TV idle band channels

TV idle band channel allocation information list

 TV idle band channel index TV idle band channel separator  -Tx. Power Transmit Power in TV Idle Band Channels Macrocellular resource allocation information Optional, only if 'Resource allocation mode' = 1  Allocated resource information Resource information allocated in the macro band  -Tx. Power Transmit power Action time Start time of use of the allocated radio resource

The resource management center may instruct the structure change of the surrounding femtocell to reduce interference to the femtocell requested during the radio resource allocation process. In this case, the resource management center transmits a 'CR Reconfiguration Command' message including the information in Table 7 below to related neighboring femto cell base stations, and the femto cell base station receiving the message transmits a 'CR Reconfiguration Response' message. After that, change the channel setting at 'action time'.

Information element Description Number of reconfigured TV idle band channels

TV idle band channel reconfiguration info.

 Current TV idle band channel index TV idle band channel identifier currently in use  TV idle band channel change indication 0: tx. power adjustment only
1: operating TV idle band channel switching  New TV idle band channel index Optional, only if 'TV idle band channel change indication' = 1  -Tx. power Transmit Power in TV Idle Band Channels Action time Start time for applying changed radio resources

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (1)

A radio resource allocation method in a wireless communication system including a macro cell and at least one femto cell,
Identifying a macro cell band allocated as a radio resource of the macro cell and a white space which is an empty radio resource;
Allocating radio resources from the macro cell band for neighbor cell discovery between the at least one femto cell in a normal resource allocation mode; And
Allocating radio resources from the idle band for data communication of each of the at least one femto cell in the normal resource allocation mode
And allocating a radio resource to the radio resource.

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