KR101323663B1 - Method for communication in femtocell and method for access to femtocell base station - Google Patents

Abstract

In a communication method in a femtocell according to the present invention, the femtocell base station operates in either of an on mode, which is a mode for transmitting a broadcast channel (BCH) signal, or an off mode, which is a mode in which a BCH signal is not transmitted. Transmitting, by the femtocell base station, identification information indicating the on mode or the off mode; And transmitting, by the terminal receiving the identification information, a signal for requesting to transmit a BCH signal to the femtocell base station when the identification information indicates the off mode.

Description

Communication method in femtocell and method of accessing terminal to femtocell base station {Method for communication in femtocell and method for access to femtocell base station}

The present invention relates to a communication method in a femtocell and a method for accessing a terminal to a femtocell base station, and more particularly, to a communication method in a femtocell and a femtocell of a terminal for reducing power consumption of a femtocell base station and mitigating interference due to femtocell operation. A method for connecting to a base station.

Recently, femtocells have received a lot of attention as a way to solve the shadow area and provide high quality services in indoor environments such as homes or offices. Femtocells use lower transmit power than conventional macrocells and provide high quality services at a lower cost.

A femtocell base station is a small sized base station similar to a conventional wireless router. It uses a licensed frequency band, transmits at a low power of 10-100 mW, and transmits an existing terminal to an indoor DSL network or a cable broadband network. It is a base station connecting to the service provider's network through.

Since the femtocell base station is installed indoors by a user, the femtocell base station needs to receive power from a home or an office. In addition, due to the operation of femtocells, macrocells and femtocells are mixed, causing interference with each other. In particular, when femtocells use the same channel with macrocells, femtocells interfere with macrocell users, thereby significantly degrading performance of macrocell users. You can.

An object of the present invention is to provide a communication method in a femtocell and a method of accessing a terminal to a femtocell base station for reducing power consumption of a femtocell base station and mitigating interference due to femtocell operation.

In order to solve the above technical problem, in a femtocell communication method according to the present invention, a femtocell base station either one of a mode for transmitting a BCH (broadcast channel) signal or an off mode for a mode that does not transmit a BCH signal. And the method, the femtocell base station transmitting identification information indicating the on mode or the off mode; And transmitting, by the terminal receiving the identification information, a signal for requesting to transmit a BCH signal to the femtocell base station when the identification information indicates the off mode.

In the transmitting of the identification information, the identification information may be transmitted by including the identification information in a synchronization signal periodically transmitted by the femtocell base station.

The synchronization signal may include at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS).

The transmitting of the identification information may include the identification information by changing a phase of at least one of the PSS and the SSS.

The method may further include, by the femtocell base station, receiving the request signal and switching to the on mode when the terminal is a member of the femtocell to transmit a BCH signal.

The method may further include receiving, by the femtocell base station, the request signal and transmitting identification information indicating rejection of the terminal request when the terminal is not a member of the femtocell.

The transmitting of the identification information indicating the rejection of the terminal request may include the identification information in a synchronization signal periodically transmitted by the femtocell base station.

The synchronization signal may include at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS).

The transmitting of the identification information may include the identification information by converting a phase of at least one of the PSS and the SSS.

In order to solve the above technical problem, in a method of accessing a femtocell base station of a terminal from a femtocell according to the present invention, the femtocell base station is an on mode which is a mode for transmitting a broadcast channel (BCH) signal or an off mode that does not transmit a BCH signal. Operating in any one of modes, the method further comprising: receiving identification information indicating the on mode or the off mode from the femtocell base station; Determining whether the identification information indicates an on mode or an off mode; And transmitting a signal requesting to transmit a BCH signal to the femtocell base station when it is determined that the identification information indicates an off mode.

The identification information may be included in a synchronization signal periodically transmitted by the femtocell base station.

The synchronization signal may include at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS).

The identification information may be included in the synchronization signal by converting a phase of at least one of the PSS and the SSS.

The determining may include determining whether the identification information indicates an on mode or an off mode based on the correlation value of the PSS and the correlation value of the SSS.

According to the present invention described above, the femtocell base station operates in a mode for transmitting a broadcast channel (BCH) signal and a mode for not transmitting a BCH signal, thereby reducing power consumption of the femtocell base station and mitigating interference due to femtocell operation.

In addition, according to the present invention described above, the terminal can determine the operation mode of the femtocell base station, the switch to the mode for transmitting the BCH signal in a mode that does not transmit the BCH signal of the femtocell base station and the connection of the terminal to the femtocell base station The procedure can be carried out smoothly.

1 shows a configuration of a wireless communication system including a femtocell according to an embodiment of the present invention.
2 illustrates an operation mode of a femtocell base station according to an embodiment of the present invention.
3 is a diagram illustrating a form in which a synchronization signal is included in a downlink radio frame of a 3GPP LTE system.
4 shows an example of values multiplied by PSS and SSS to change the phase of the PSS and SSS.
5 shows an example of determining a mode of a femtocell base station based on a correlation value between PSS and SSS.
6 is a flowchart illustrating a communication method between a terminal and a femtocell base station in a femtocell and a method of accessing a terminal to a femtocell base station according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 shows a configuration of a wireless communication system including a femtocell according to an embodiment of the present invention.

As shown in FIG. 1, the macro cell base station 121 manages one macro cell 120. In addition, at least one femtocell 110 managed by the femtocell base station 111 may be located in the macrocell 120. A femtocell base station is called a Home Node B (HNB) in 3GPP and a Home evolved Node B (HeNB) in a Long Term Evolution (LTE) system.

Since the terminal 122 is located in the macro cell 120 but not in the femtocell 110, the terminal 122 accesses the macro cell base station 121 and performs communication. If the terminal 122 moves into the femtocell 110, the terminal 122 accesses the femtocell base station 111 and performs communication.

Since the terminal 112 is located in the femtocell 110, it connects to the femtocell base station 111 and performs communication. If the terminal 112 moves out of the femtocell 110, the terminal 112 accesses the macro cell base station 121 and performs communication.

The femtocell base station 111 operates based on the closed subscriber group (CSG). That is, the femtocell base station 111 is available only to terminals designated by the agreement of the installer of the femtocell base station and the mobile communication service provider. A terminal capable of using the femtocell base station 111 is called a member of the femtocell.

2 illustrates an operation mode of a femtocell base station according to an embodiment of the present invention.

Existing femtocell base station periodically transmits a BCH (Broadcast Channel) signal in a broadcast manner in order to inform its main system information to the terminal to receive the service. The BCH signal includes information about system bandwidth, antenna configuration, configuration of other control channels, and other major system configurations. In order to establish communication with the base station, the terminal must accurately detect the BCH signal of the base station.

2, a femtocell base station according to an embodiment of the present invention operates in an on mode off mode and can switch between modes. The on mode is a mode in which a femtocell base station transmits a BCH signal, and the off mode is a mode in which a femtocell base station does not transmit a BCH signal. That is, the BCH signal is periodically transmitted when the femtocell base station operates in the on mode, and the BCH signal is not transmitted when the femtocell base station operates in the off mode. The femtocell base station operates in the on mode when there is a member terminal in the femtocell, and operates in the off mode when there is no member terminal in the femtocell. When the femtocell base station receives a signal requesting to transmit a BCH signal from the terminal in the off mode, the femtocell base station switches to the on mode and transmits the BCH signal when the terminal is a member terminal. However, when the terminal is not a member terminal, the femtocell base station maintains the off mode and transmits identification information indicating 'denial' of the terminal request.

Since the femtocell base station does not transmit or transmit the BCH signal as necessary, power consumption of the femtocell base station is reduced, and interference with adjacent cells due to the transmission of the BCH signal is mitigated.

The terminal that wants to access the femtocell base station needs to identify whether the femtocell base station is on mode or off mode. Therefore, the femtocell base station transmits identification information indicating the on mode or the off mode. Typically, a femtocell base station periodically transmits a synchronization signal as a signal for synchronization and cell search. In one embodiment of the present invention, the femtocell base station transmits the sync signal by including identification information indicating an on mode or an off mode. Furthermore, the identification information indicating the denial of the terminal request is also included in the synchronization signal and transmitted. The terminal receiving the sync signal can identify whether the femtocell base station is on mode, off mode, or rejects the request (ie, it is not a member terminal) by detecting identification information from the sync signal.

3 is a diagram illustrating a form in which the synchronization signal is included in a downlink radio frame of a 3GPP LTE system. As shown, the radio frame consists of 10 subframes. The synchronization signal includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and the PSS and the SSS exist in the 0 th and 5 th subframes.

In one embodiment of the present invention, the femtocell base station includes identification information indicating the on, off, rejection by changing the phase of the PSS and the SSS. 4 shows an example of values multiplied by PSS and SSS to change the phase of the PSS and SSS. Referring to FIG. 4, in the on mode, SSS and PSS of the 0 th subframe are multiplied by 1, 1, -1, and -1, respectively. In the off mode, the SSS and PSS of the 0 th subframe and the SSS and PSS of the 5 th subframe are multiplied by 1, -1, -1, and 1, respectively. In case of rejection, 1, -1, 1, -1 are multiplied by SSS and PSS of subframe 0 and SSS and PSS of subframe 5 respectively.

Upon receiving the synchronization signal including the PSS and the SSS whose phase is changed as described above, the UE may determine the mode of the femtocell base station using the coherent correlation of the PSS and the SSS. 5 shows an example of determining a mode of a femtocell base station based on a correlation value between PSS and SSS. In FIG. 5, S1, P1, S2, and P2 are phasers of the correlation values of the PSSs included in the 0 th subframe, respectively. , The detection value of the phaser (Phasor) of the correlation value of the SSS included in the fifth subframe, and the phaser (Phasor) of the correlation value of the PSS included in the fifth subframe. Here, the channel can be estimated through the PSS. The correlation value of the SSS is obtained after removing the phase of the channel experienced by the SSS.

Referring to FIG. 4, in the on mode, since the PSS of the 0th subframe and the PSS of the 5th subframe are inverted in phase, the detection value of the product of the complex conjugate of P1 and P2 becomes -1. In the off mode, since the PSS of the 0th subframe and the PSS of the 5th subframe are inverted in phase, the product of the complex conjugate of P1 and P2 becomes -1. However, in the case of rejection, since the PSS of the 0th subframe and the PSS of the 5th subframe have the same phase, the result is +1 when the product of the complex conjugate of P1 and P2 is detected.

The channel estimated through the PSS is a channel whose phase is converted according to the value multiplied by the PSS as shown in FIG. 4, and as described above, the correlation value of the SSS is obtained after removing the phase of the channel estimated through the PSS. The phaser of the correlation value of may correspond to the product of the value multiplied by SSS and the value multiplied by PSS. 4 and 5, in the on mode, S1 = (1) * (1) = 1 and S2 = (-1) * (-1) = 1. In the off mode, S1 = (1) * (-1) =-1 and S2 = (-1) * (1) =-1. In case of rejection, S1 = (1) * (-1) =-1 and S2 = (1) * (-1) =-1.

Accordingly, as shown in FIG. 5, when the detection value of the product of the complex conjugate of P1 and P2 is −1 and S1 = 1 and S2 = 1, it may be determined as the on mode. If the detected value of the product of the conjugate complex of P1 and P2 is -1 and S1 = -1 and S2 = -1, it can be discriminated to the off mode. If the detected value of the product of the conjugate complex of P1 and P2 is +1 and S1 = -1 and S2 = -1, it can be determined as rejection.

In the above description of the embodiment of the present invention, it is assumed that the detection of the phase ruler uses a method of detecting BPSK (Biphase Shift Keying).

As described above, in one embodiment of the present invention, identification information indicating on, off, and rejection may be included by changing the phases of the PSS and the SSS, and the identification information may be detected using the coherent correlation of the PSS and the SSS. . However, in other embodiments of the present invention, identification information may be included and detected in the synchronization signal in a different manner. For example, identification information indicating on, off, and rejection may be included by changing the phase of the SSS, and the identification information may be detected using differential correlation of the SSS.

6 is a flowchart illustrating a communication method between a terminal and a femtocell base station in a femtocell and a method of accessing a terminal to a femtocell base station according to an embodiment of the present invention. Referring to FIG. 6, a procedure indicated by a dashed dashed line according to a resource allocation method may be omitted in some cases.

When the femtocell base station transmits the synchronization signal in a broadcast manner, the terminal receives the synchronization signal (610). The synchronization signal includes identification information indicating whether the femtocell base station is on mode, off mode, or rejection of the BCH signal transmission request of the terminal. In one embodiment of the present invention, including the identification information in the synchronization signal may be performed as described above with reference to FIGS. 3 and 4.

The terminal determines whether the femtocell base station is on mode, off mode, or rejection of the BCH signal transmission request based on the identification information included in the synchronization signal (620). In an embodiment of the present invention, determining what identification information included in the synchronization signal may be performed as described above with reference to FIG. 5.

If it is determined in step 620 that the femtocell base station is in the on mode, the femtocell base station is transmitting a BCH signal, the terminal decodes the received BCH signal to obtain necessary information (690). The terminal may perform an access or handover procedure to the femtocell base station based on the obtained information.

If it is determined in step 620 that the femtocell base station is in the rejected state, it means that a terminal other than itself has requested a BCH signal transmission, but the terminal is not a member terminal. Accordingly, the terminal waits for the next synchronization signal and repeats step 620 when the next synchronization signal is received.

If it is determined in step 620 that the femtocell base station is in the off mode, the terminal transmits an uplink signal requesting to transmit the BCH signal to the femtocell base station (650). The uplink signal includes identification information for identifying whether the terminal is a member of the femtocell.

In a system for allocating femtocell resources in a macrocell base station according to a resource allocation scheme, the terminal requests resource allocation from the macrocell base station (630), the macrocell base station allocates resources, and then responds to the resource allocation request. The process 640 may be additionally performed.

In operation 650, the femtocell base station that receives the uplink signal of the terminal determines whether the terminal is a member of the femtocell (660).

If it is determined in step 660 that the terminal is not a member of the femtocell, the femtocell base station transmits identification information indicating denial to the terminal. In an embodiment of the present invention, as described above with reference to FIGS. 3 and 4, identification information indicating rejection may be included in the synchronization signal. After confirming the 'deny' of the femtocell base station, the UE recognizes that it is not a member of the femtocell, and no longer performs an access or handover procedure to the femtocell base station.

If it is determined in step 660 that the terminal is a member of the femtocell, the femtocell base station switches to the on mode. Accordingly, the femtocell base station includes the identification information indicating the on mode in the synchronization signal and transmits it, and starts transmission of the BCH signal (680). Upon receiving the synchronization signal, the terminal determines that the femtocell base station is in the on mode.

The terminal receiving the BCH signal decodes the received BCH signal to obtain necessary information (690). The terminal may perform an access or handover procedure to the femtocell base station based on the obtained information.

So far I looked at the center of the preferred embodiment for the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (14)

In a communication method in a femtocell,
The femtocell base station operates in one of an on mode, a mode in which a broadcast channel (BCH) signal is transmitted, or an off mode, a mode in which a BCH signal is not transmitted,
Transmitting, by the femtocell base station, identification information indicating the on mode or the off mode; And
And receiving, by the terminal receiving the identification information, a signal for requesting to transmit a BCH signal to the femtocell base station when the identification information indicates the off mode.
In the transmitting of the identification information, the identification information is transmitted by including the identification information in a synchronization signal periodically transmitted by the femtocell base station.
The synchronization signal includes at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS),
The transmitting of the identification information includes the identification information by changing a phase of at least one of the PSS and the SSS. delete delete delete The method of claim 1,
And receiving the request signal from the femtocell base station and switching to the on mode when the terminal is a member of the femtocell to transmit a BCH signal. The method of claim 1,
Receiving the request signal by the femtocell base station and transmitting identification information indicating rejection of the terminal request when the terminal is not a member of the femtocell. The method according to claim 6,
The transmitting of the identification information indicating the rejection of the terminal request comprises the identification information in a synchronization signal periodically transmitted by the femtocell base station. The method of claim 7, wherein
The synchronization signal includes at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). 9. The method of claim 8,
The transmitting of the identification information includes the identification information by converting a phase of at least one of the PSS and the SSS. In a method of accessing a femtocell base station of a terminal from a femtocell,
The femtocell base station operates in one of an on mode, a mode in which a broadcast channel (BCH) signal is transmitted, or an off mode, a mode in which a BCH signal is not transmitted,
Receiving identification information indicating the on mode or the off mode from the femtocell base station;
Determining whether the identification information indicates an on mode or an off mode; And
Transmitting a signal requesting to transmit a BCH signal to the femtocell base station when it is determined that the identification information indicates an off mode,
The identification information is included in a synchronization signal periodically transmitted by the femtocell base station,
The synchronization signal includes at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS),
And the identification information is included in the synchronization signal by converting a phase of at least one of the PSS and the SSS. delete delete delete The method of claim 10,
The determining may include determining whether the identification information indicates an on mode or an off mode based on the correlation value of the PSS and the correlation value of the SSS.

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