KR20100037262A - Method for initiating handover in femto cell and system thereof - Google Patents

Abstract

PURPOSE: A method for initiating handover in a femto cell and a system thereof are provided to open a handover rapidly by receiving the system information from a femto cell base station in a persistent scheduling service. CONSTITUTION: A terminal enters a macro cell(S905), and initiates a reception measurement of system information according to an allocated measurement gap(S940). If the reception measurement of the system information is successful, the terminal transmits the successful message to a macro BS(Base Station)(S945,S950). The macro base station indicates the performance of handover to the terminal(S955), and the terminal initiates a handover process of a femto cell.

Description

Method for initiating handover in a femto cell and system thereof {METHOD FOR INITIATING HANDOVER IN FEMTO CELL AND SYSTEM THEREOF}

The present invention relates to a method and system for initiating handover in a femto cell. More specifically, the method and system for initiating handover of the present invention relates to an invention in which a terminal in a persistent scheduling service receives system information transmitted from a femtocell base station and quickly initiates handover.

Femto Cell (Femto Cell) is a small mobile communication base station connected to the mobile communication core network through a broadband network installed indoors, such as home or office. The name of a femto cell is a compound word of 'femto' which means 10 minus 15 wins (one hundredth of a trillion) and 'cell' which means the communication range of a mobile phone, and can provide coverage with a cell radius of 10 meters or less. Means a base station. Femtocells have various advantages to expand indoor coverage, improve call quality, and efficiently provide a variety of wired and wireless convergence services. Since femtocells aim to provide a higher level of data services to more users, they are attracting attention not only in existing 3rd generation mobile communication systems but also in next generation mobile communication systems such as 3GPP LTE (The 3rd Generation Partnership Project Long Term Evolution). Is getting.

Femto cells have very little cell coverage compared to macro cells and assume that they are installed directly where they are desired. As a result, a plurality of femto cells may be arbitrarily installed in one macro cell coverage, and a physical layer cell identifier (PCI), which is one of the identifiers for distinguishing them, may be used in the macro cell.

If the terminal intends to hand over from the macro cell to the femto cell, the femto cell does not know which femto cell to hand over due to the above characteristics. Therefore, the terminal needs to additionally receive an identifier that can more accurately identify the femto cell to be handed over in addition to the PCI. In this case, the additional identifier is a closed subscriber group ID (CSG ID) and a global cell ID (GCI). The CSG ID and the GCI may be obtained when the femtocell base station receives System Information Block 1 (SIB1) (hereinafter, 'system information') broadcasted through a broadcast channel.

In this case, the femto cell base station broadcasts the system information in a longer period than the transmission period of the PCI. However, when the terminal considers the data transmission due to the persistent scheduling service and the retransmission time by HARQ (Hybrid ARQ) during the persistent scheduling (or semi-persistent scheduling, hereinafter same) service from the macro base station, the additional identifier from the femtocell It is difficult to secure enough time to receive it.

Accordingly, there is a need for a method for a terminal to receive system information broadcast by a femto cell even during a persistent scheduling service.

The present invention has been made to solve the above problems, and provides a method for a terminal to enter a femto cell to quickly initiate a handover by receiving system information transmitted by the femto cell base station even during the persistent scheduling service. Its purpose is to.

In the femtocell of the present invention for achieving the above object, the method for initiating handover of a terminal reports a reception of a physical layer cell identifier transmitted from a home base station to a macro base station, and receives system information transmitted from the home base station. Allocating a time interval for measuring a value from the macro base station, measuring the reception of the system information in the allocated time interval, and initiating a handover to the femtocell when the system information is received. Characterized in that. In this case, the terminal is in a persistent scheduling service, and the time interval is allocated from the base station through the measurement gap (first embodiment) or through an operation period of the discontinuous reception mode of the terminal (second time). Example) is characterized in that.

In addition, a handover initiation system in a femto cell including a home base station, a macro base station, and a terminal of the present invention for achieving the above object is a home base station for transmitting a physical layer cell identifier and system information, and the terminal is the system. Reporting the reception of the macro base station and the physical layer cell identifier to the macro base station for allocating a time interval for measuring reception of the information, and measuring the reception of the system information in the time interval allocated from the macro base station; And a terminal for initiating handover to the femtocell upon receiving information.

According to the handover method in the femto cell of the present invention, the terminal attempting to enter the femto cell has an advantage that the handover can be started more quickly by receiving system information transmitted by the femtocell base station even during the persistent scheduling service. .

The terminology of an embodiment of the present invention shall be in accordance with the 3GPP LTE system standard. Therefore, hereinafter, a femto cell base station is referred to as a home base station (Home-eNB), a macro cell base station as a macro base station (Macro-eNB), and a user terminal (User Equipment, UE).

Hereinafter, as a specific embodiment of the handover method of the present invention will be described separately into the first embodiment and the second embodiment. In this case, the first embodiment relates to a method in which the macro base station 140 explicitly allocates a measurement gap so that the terminal receiving the PCI receives system information from the home base station. In addition, in the second embodiment, instead of allocating the measurement gap of the first embodiment to the terminal by the macro base station 140, the discontinuous reception (DRX) mode of the terminal 150 corresponds to the measurement gap. It relates to a method of transmitting a DRX control signal for controlling the operation period of the.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted.

In this case, FIGS. 1 to 3 are commonly applied to the first embodiment and the second embodiment. 4 to 10 are views showing the first embodiment, and Figs. 11 to 15 are views showing the second embodiment.

1 is a conceptual diagram schematically illustrating a process of handing over to a home base station in a persistent scheduling service of a terminal in a femto cell system. A femtocell system according to an embodiment of the present invention includes a macro cell 110, a femto cell 120, a home base station 130, a macro base station 140, and a terminal 150.

The macro cell 110 includes a plurality of femto cells 120. Here, the femto cell 120 refers to a communication radius of a small mobile communication base station used indoors such as homes or offices. The femto cell 120 is assumed to be installed directly where users want.

The home base station 130 controls each femto cell 120. Here, the home base station 130 is a subscriber-only home base station that provides a service only for a femto cell dedicated subscriber subscribed to each femto cell 120 service. In other words, although the first terminal subscribed to the first home base station can receive the service through the first home base station, the first terminal cannot receive the service through the other home base station. Each home base station 130 is connected to a core network (not shown) through a femto cell controller (not shown).

The macro base station 140 is connected to a wireless network controller (not shown) and connected to a core network (not shown) to provide a mobile communication service to the terminal 150. In particular, the macro base station 140 according to the embodiment of the present invention retains information on the plurality of femto cells 120 present in its macro cell coverage.

When the macro base station 140 receives the PCI reception from the terminal 150 while providing the persistent scheduling service to the terminal 150, the macro base station 140 allocates the measurement gap to the terminal 150 to obtain system information. Then, the terminal 150 stops communication with the macro base station 140 during the time interval allocated through the received measurement gap and measures whether system information is received from the home base station 130 located nearby. . The terminal 150 receiving the system information acquires the CSG ID and the GCI from the system information. The terminal 150 reports this to the macro base station 140 and initiates a handover procedure. According to the second embodiment of the present invention, the macro base station 140 may transmit a DRX control signal for controlling the operation period of the DRX of the terminal 150 to correspond to the measurement gap.

The terminal 150 forms a communication link with the macro base station 140 or the home base station 130 to receive a normal mobile communication service. The femto cell is assumed to be installed directly where users want it. Accordingly, the terminal 150 includes a list of neighboring macro cells of the femto cell 120 to which the terminal 150 can connect, which is called a fingerprint.

In particular, the terminal 150 may initiate a handover to the home base station 130 to which it subscribes, among the persistent scheduling services. To this end, the terminal 150 is assigned a measurement gap from the macro base station 140 for receiving system information from the home base station 140, when receiving the PCI from the home base station 140. In addition, the terminal 150 stops communication with the macro base station 140 during a specific time allocated through the received measurement gap and measures whether system information is received from the home base station 130. When the terminal 150 receives the system information, the terminal 150 reports this to the macro base station 140 and initiates a handover procedure.

Hereinafter, referring to FIG. 1, a process of handing over a femto cell to which a terminal 150 according to an embodiment of the present invention subscribes is described.

First, it is assumed that the terminal 150 enters a specific femto cell A among the plurality of femto cells 120 in the macro cell 110. In this case, it should be assumed that the terminal 150 is subscribed to the specific femto cell A to enter. When the terminal 150 approaches the femto cell A to which it subscribes, it receives the PCI from the home base station of the femto cell A (① process). The PCI is composed of 9 bits, and is obtained when the terminal 150 receives a synchronization signal transmitted every 5 ms. However, as described above, since a plurality of femto cells may use the same PCI, it is not known exactly which femto cell to hand over to only by receiving the PCI.

Therefore, the terminal 150 should acquire a closed subscriber group ID (CSG ID) and a global cell ID (GCI) which are other identifiers for identifying the home base station in addition to the received PCI. The CSG ID and the GCI may be obtained when a home base station receives system information broadcasted through a broadcast channel.

However, the terminal 150 periodically receives data from the macro base station 140 during the persistent scheduling service. In addition, when retransmission of scheduling by HARQ occurs, the scheduling is dynamically transmitted, and there is a possibility that sufficient time for measuring system information transmitted from the home base station cannot be obtained.

Therefore, the terminal 150 should measure whether system information is transmitted from the home base station A to be handed over in a time interval not overlapped with the persistent scheduling service of the macro base station 140. The system information reception measurement of the terminal 150 is controlled by the macro base station 140. In other words, the macro base station 140 allocates a measurement gap to the terminal, which can avoid the ongoing scheduling service interval (step ②). According to the second embodiment of the present invention, a method of controlling the DRX operation period of the terminal 150 by the macro base station 140 is also possible.

Upon receiving the measurement gap, the terminal 150 stops communication with the macro base station 140 at a specific time interval allocated through the received measurement gap and measures whether system information is transmitted from the home base station 130 (③). step). Through this process, the terminal 150 may receive system information to obtain a CSG ID and a GCI. The terminal 150 reports the acquisition of the CSG ID and the GCI to the macro base station 140 and then initiates a handover procedure to the femto cell A. FIG.

FIG. 2 is a diagram illustrating a radio frame structure (hereinafter, referred to as a 'home base station radio frame') 205 transmitted by the home base station 130 in the femto cell system of the present invention.

When the terminal 150 intends to hand over to the femto cell to which it has subscribed, it does not know which femto cell to hand over with only the PCI transmitted from the home base station. Accordingly, it is necessary to obtain a CSG ID and a GCI for identifying a specific femto cell. The CSG ID and the GCI are transmitted through a home base station radio frame shown in FIG. 2.

The home base station radio frame has a length of 10ms and consists of 10 subframes of 1ms in length.

The most basic information about the femto cell system is included in a master information block (MIB) and transmitted through the PBCH of subframe # 0. In the master information block, the first transmission 210 occurs in a 40 ms period, and is repeatedly transmitted (220, 230, etc.) in a 10 ms period.

CSG ID and GCI, which are identifiers required for handover to a specific home base station, are transmitted through system information SIB1. In this case, system information is transmitted through the PDSCH of subframe # 5, which is a broadcast channel. The first transmission 230 is generated every 80ms, and the same information is repeatedly transmitted at intervals of 20ms, such as 240 and 250.

3 is a diagram illustrating a structure of a radio frame (hereinafter, referred to as a 'macro base station radio frame') 305 in which the macro base station 140 transmits persistent scheduling to the terminal 150.

Real time services that require similar amounts of resources periodically, such as Voice over Internet Protocol (VoIP), allocate resources by either persistent scheduling or semi-persistent scheduling. In the case of VoIP, since data is generated in the upper layer every 20ms, resource allocation is also performed in a 20ms period.

As can be seen in FIG. 3, the transmission of persistent scheduling occurs in the same subframe every two frames. In other words, after the first persistent scheduling is transmitted 310 in the second frame, the second persistent scheduling is transmitted 320 in the fourth frame, and this pattern is repeated every two frames (20 ms). .

In addition, the retransmission process by the HARQ operation is also shown in FIG. HARQ (Hybrid Automatic Repeat reQuest) refers to a transmission error control technique that attempts to correct an error on a received code and determines whether to retransmit using an error detection code. Data transmission 330 by the HARQ operation is made by dynamic scheduling, and is transmitted through any subframe.

<First Embodiment>

Hereinafter, a description will be given of a first embodiment in which the macro base station 140 explicitly allocates a measurement gap so that the terminal receiving the PCI receives system information from the home base station. The first embodiment is described in FIGS. 4 to 10.

4A is a diagram illustrating an example of a measurement gap pattern allocated to the terminal 150 by the macro base station 140 according to the first embodiment of the present invention. In FIG. 4A, a first measurement gap pattern 410, a second measurement gap pattern 420, a third measurement gap pattern 430, and a fourth measurement gap pattern 440 are illustrated.

Each measurement gap pattern has a length of 20 ms and is divided into first to fourth intervals based on 5 ms. In addition, the measurement gap pattern includes a gap duration. Here, the gap period refers to a time period during which the terminal 150 stops communication with the macro base station 140 and measures system information of the home base station 130. And the measurement gap consists of any combination of a plurality of measurement gap patterns.

The gap period is allocated so as not to overlap with the location of the persistent scheduling transmitted from the macro base station 140. This is because if the location of the persistent scheduling and the gap interval of the measurement gap pattern overlap, the terminal 150 must stop the persistent scheduling service.

As shown in FIG. 4A, in the first measurement gap pattern 410, a gap section is assigned to the first section, and in the second measurement gap pattern 420, a gap section is assigned to the second section, and a third measurement gap is provided. In the pattern 430, a gap section is allocated in the third section, and in the fourth measurement gap pattern 440, a gap section is allocated in the fourth section.

FIG. 4B is a diagram illustrating an example of a measurement gap that arbitrarily combines the plurality of measurement gap patterns shown in FIG. 4A.

As described above, the measurement gap is a gap in which the measurement gap pattern shown in FIG. 4A is arbitrarily combined. Here, the first measurement gap 450 illustrated in FIG. 4B is a combination of the first measurement gap pattern 410, the second measurement gap pattern 420, and the third measurement gap pattern 430. Similarly, the second measurement gap 460 is a combination of the third measurement gap pattern 430, the first measurement gap pattern 410, and the second measurement gap pattern 420. The measurement gap may be generated by arbitrarily combining a plurality of measurement gap patterns under conditions that do not overlap with the location of the persistent scheduling in the above manner.

When the macro base station 140 receives the PCI reception from the terminal 150, the macro base station 140 allocates an arbitrary measurement gap to the terminal 150. Then, the terminal 150 stops communication with the macro base station 140 according to the gap period assigned to the measurement gap and measures the reception of system information.

5 is a diagram illustrating a method in which the terminal 150 of the present invention receives system information of a home base station according to a measurement gap allocated by the macro cell 140 among the persistent scheduling services.

The macro base station 140 provides a persistent scheduling service to the terminal 150 through the macro base station radio frame 305. In the persistent scheduling service, when the terminal 150 receives the PCI from the specific home base station 130, it reports to the macro base station 140. The macro base station 140 then allocates the measurement gap to the terminal 150. In this case, the macro base station radio frame 305 and the frame of the measurement gap are transmitted in synchronization with each other. This is because both radio frame 305 and measurement gap are transmitted from base station 140 with the same mark.

System information for the terminal 150 to identify a specific femto cell is transmitted to subframe # 5 of the home base station radio frame 205 transmitted from the home base station 130. In this case, the macro base station radio frame 305 and the measurement gap are not synchronized with the frame of the home base station radio frame 205. This is because the synchronization between base stations is not correct in the LTE system.

Meanwhile, FIG. 5 illustrates a terminal 150 in which the first measurement gap 450 in which the first measurement gap pattern 410, the second measurement gap pattern 420, and the third measurement gap pattern 430 are sequentially combined. Shows an example assigned to). The terminal 150 stops communication with the macro base station 140 in the gap period of the measurement gap allocated from the macro base station 140 and measures the reception of system information transmitted from the home base station 130.

As can be seen in FIG. 5, in this example, the gap period of the third measurement gap pattern 430 coincides with the transmission point of the system information of the home base station 130. Accordingly, the terminal 150 may receive the system information by avoiding the persistence scheduling time even during the persistence scheduling service. Then, the terminal 150 may correctly identify the femto cell to be handed over by obtaining the CSG ID and the GCI included in the system information.

 In FIG. 5, an example in which the macro base station 140 explicitly allocates a measurement gap to the terminal 150 has been described. However, such measurement gap allocation does not always guarantee the reception of system information of the terminal. Details thereof will be described with reference to FIG. 6.

6 is a diagram illustrating an example in which the terminal 150 of the present invention fails to obtain system information.

As shown in FIG. 6, when the persistent scheduling transmission time of the macro base station 140 and the system information transmission time of the home base station 130 are close to each other, the terminal 150 may fail to receive and receive system information. have. This is because the gap section is set by avoiding the transmission time point of the persistent scheduling. That is, when the persistent scheduling transmission time and the system information transmission time point are close, the terminal 150 avoids the system information transmission time and measures the reception of the system information. Therefore, the terminal 150 fails to measure the reception of the system information.

Therefore, when the base station 140 fails to measure the reception of the system information as described above, it is necessary to readjust the transmission timing of the persistent scheduling. This will be described in FIG. 7.

FIG. 7 is a diagram illustrating a method of measuring reception of system information by a terminal 150 reallocating a measurement gap after readjusting persistent scheduling.

When the terminal 150 fails to receive and measure the system information, the terminal 150 reports the measurement failure to the macro base station 140. The macro base station 140 then readjusts the persistent scheduling transmission time.

7 shows an example of readjustment of a persistent scheduling transmission time point. The macro base station 140 readjusts the persistent scheduling transmitted in the subframe of the second radio frame to the subframe of the first frame. Thereafter, the macro base station 140 transmits persistent scheduling in the same subframe every two frames based on the first frame.

The macro base station 140 must reassign the order of arranging the measurement gap patterns for the measurement gaps at the same time as the rescheduling of the persistent scheduling. In this case, the macro base station 140 reassigns the gap period of each measurement gap pattern and the transmission time point of the readjusted persistent scheduling when the reallocation does not overlap each other.

The terminal 150 then measures system information according to the rescheduled persistent scheduling and the reallocated measurement gap. As can be seen in FIG. 6, in the present example, the macro base station 140 measures a measurement generated by combining a third measurement gap pattern 430, a first measurement gap pattern 410, and a fourth measurement gap pattern 440. The gap is allocated to the terminal 150. Then, the gap period of the fourth measurement gap pattern 440 and the transmission point of the system information of the home base station 130 coincide with each other. Therefore, even if the first system information reception measurement fails, the terminal 1560 may succeed in the reception measurement of the next system information according to the readjustment of the persistent scheduling and the reallocation of the measurement gap.

8 is a flowchart illustrating a process in which the terminal 150 receives a measurement gap from a macro cell and measures reception of system information according to an embodiment of the present invention.

First, the terminal 150 enters the macro cell 110 including the plurality of femto cells 120 in step S805. The macro base station 150 retains information about the plurality of femto cells 120 existing within its macro cell 110 coverage. In addition, the plurality of femto cells 120 are premised on being directly installed where the users want.

In addition, the terminal 810 determines whether the PCI is received from the femto cell 120 in step S810. PCI is a basic identifier for identifying a femto cell and consists of a 9-bit stream, which is obtained when the terminal 150 receives a synchronization signal transmitted every 5 ms.

When the terminal 150 confirms the PCI reception, the terminal 150 reports the PCI reception to the macro base station 140 in step S815. The terminal 150 reporting the PCI reception determines whether the measurement gap received from the macro base station 140 is received in step S820. When the terminal 150 determines that the measurement gap has been received, the terminal 150 starts receiving measurement of the system information according to the measurement gap allocated in step S825. In other words, the terminal 150 stops communication with the macro base station 140 in the gap period of the measurement gap pattern listed in the measurement gap and measures the reception of system information transmitted from the home base station 130.

In step S830, the terminal 150 determines whether the measurement of the reception of the system information is successful, and if the measurement is successful, the terminal 150 reports the measurement success to the macro cell 150 in step S845. When the terminal 150 receives a handover instruction from the macro cell 150, the terminal 150 starts the handover procedure.

On the other hand, if the terminal 150 determines that the reception measurement of the system information failed in step S830, and reports the measurement failure to the macro base station 140 in step S835. In addition, the terminal 150 determines whether the measurement gap reallocated from the macro base station 140 is received. Upon receipt of the reallocated measurement gap, the terminal 150 returns to step S825 and repeats the steps below S825.

9 is a flowchart illustrating a procedure in which the terminal 150 exchanges signaling messages with the home base station 130 and the macro base station 140 in order to measure the reception of system information.

First, the terminal 150 enters the macro cell 110 including the plurality of femto cells 120 in step S905. Then, the terminal 150 registers the femto cell context (femto cell context) of the plurality of femto cells included in the macro cell 110 entered into the macro base station 140. In operation S915, the terminal 150 receives a persistent scheduling service through the macro base station 140. At the same time, in step S920, the terminal 150 receives a short measurement gap from the macro base station 140 for receiving a PCI transmitted from the femto cell. Then, the terminal 150 measures the PCI reception in the gap interval allocated through the short measurement gap.

When the terminal 150 receives the PCI in step S925, the terminal 150 reports the reception of the PCI to the macro base station 140 in step S930. Then, the macro base station 140 receiving the report transmits the measurement gap to the terminal 150 in which the plurality of measurement gap patterns are arbitrarily combined in step S935. In this case, the gap interval of the measurement gap is allocated so as not to overlap with the position of persistent scheduling.

The terminal 150 starts receiving measurement of system information according to the measurement gap allocated in step S940. When the terminal 150 receives the system information transmitted from the home base station 130, the terminal 150 may acquire a CSG ID and a GCI for identifying a femto cell to be handed over. If the terminal succeeds in receiving measurement of the system information in step S945, and transmits it to the macro base station 140 in step S950. Then, the macro base station 140 instructs the terminal 150 to perform handover (RRC reconfiguration) in step S955. Upon receiving the indication, the terminal initiates a handover procedure to the femtocell in step S960.

FIG. 10 is a flowchart illustrating a signaling message exchange procedure for receiving measurement of next system information according to readjustment of persistent scheduling and reallocation of measurement gap after the terminal 150 fails to receive measurement of initial system information.

First, steps S1005 to S1040 in which the terminal 150 enters the macro cell to measure reception of system information for the first time correspond to steps S905 to S940 in FIG. 9, and thus detailed description thereof will be omitted.

If the terminal 150 fails to measure the reception of the system information from the home base station 130 within the time set in step S1045, it determines that the reception measurement of the system information has failed. In operation S1050, the terminal 150 reports the failure of receiving measurement of system information to the macro base station 140. The macro base station 140 that reports the measurement failure readjusts the transmission timing of the persistent scheduling. For example, the macro base station 140 may readjust the persistent scheduling transmitted in the subframe of the conventional second radio frame to the subframe of the first radio frame. In addition, the macro base station 140 also reassigns the order of arranging the measurement gap patterns with respect to the measurement gaps at the same time as the persistent scheduling.

The macro base station 140 retransmits the measurement gap reassigned in step S1060 to the terminal 150. The terminal 150 starts receiving measurement of system information according to the measurement gap reallocated in step S1065. If the terminal 150 succeeds in the reception measurement of the system information transmitted from the home base station 130 in step S1070, it transmits it to the macro base station 140 in step S1075. Then, the macro base station 140 instructs the terminal 150 to perform handover in step S1080 (RRC reconfiguration). Upon receiving the indication, the terminal initiates a handover procedure to the femtocell in step S1085.

Second Embodiment

Hereinafter, a second embodiment in which the macro base station 140 transmits a DRX control signal for controlling a DRX operation cycle of the terminal 150 to correspond to the measurement gap of the first embodiment will be described.

FIG. 11 is a diagram illustrating a method for measuring reception of system information transmitted from a femtocell by a terminal of the present invention using a DRX operation cycle.

In general, the DRX mode is mainly used to increase a standby time of an idle terminal. That is, the terminal wakes up from the activation section, monitors a predetermined channel for a set time, and repeats the operation of entering the sleep mode again in the sleep section.

The terminal 150 of the present invention communicates with the macro base station 140 in the activation section 1110 of the DRX, and stops communicating with the macro base station 140 in the sleep sections 1120, 1130, and 1140 of the DRX, It is measured whether system information is transmitted from the base station 130. In this case, the sleep interval should be allocated so as not to overlap with the persistent scheduling transmission time transmitted from the macro base station 140 as in the case of the first embodiment. The DRX operation cycle of the terminal 150 is controlled by the macro base station 140, which will be described below with reference to FIG.

12 is a diagram illustrating an example of a DRX operation cycle that the terminal 150 receives from the macro base station 140.

In the first embodiment of the present invention, a method in which the macro base station 140 explicitly allocates the measurement gap to the terminal 150 has been described. In this case, the measurement gap allocated by the macro base station 140 to the terminal 150 is repeatedly illustrated in FIG. 12.

In contrast, in the second embodiment of the present invention, as shown in FIG. 12, the macro base station 140 controls the DRX operation cycle of the terminal 150 to correspond to the measurement gap of the first embodiment. In the present invention, the macro base station 140 controls the DRX operation cycle of the terminal 150 to implicitly allocate the gap period, which is called a scheduled gap.

As can be seen in FIG. 12, the sleep section of the second embodiment corresponds to the gap section of the first embodiment. In addition, the activation section of the second embodiment corresponds to sections other than the gap section of the first embodiment. Therefore, the terminal 150 according to the second embodiment stops communication with the macro base station 140 in the sleep period and measures the reception of system information.

The macro base station 140 adjusts the scheduling of the macro base station radio frame so that the sleep interval of the schedule gap does not overlap with the HARQ retransmission. In other words, since retransmission of the scheduling by the HARQ is performed dynamically, the macro base station 140 may adjust the scheduling of the HARQ so that the scheduling of the HARQ and the sleep interval of the schedule gap allocated to the terminal do not overlap each other.

 The terminal 150 of the second embodiment stops communication with the macro base station 140 in the sleep intervals 1210, 1220, and 1230 of the schedule gap, and measures reception of system information transmitted from the home base station 130. Therefore, the process of measuring the reception of the system information through the schedule gap according to the second embodiment can be easily understood by those skilled in the art with reference to the processes of FIGS. Let's do it.

13 is a flowchart illustrating a process in which a terminal 150 receives a schedule gap from a macro cell 140 and measures reception of system information according to an exemplary embodiment of the present invention.

The terminal 150 according to the second exemplary embodiment receives a schedule gap, which is a DRX operation cycle control signal, from the macro cell 140 and measures reception of system information.

In this case, except for steps S1320, S1325, and S1340, the same description as that described with reference to FIG. 8 is omitted. In step S1320, step S1325, and step S1340, the terminal 150 receives a schedule gap from the macro base station 140 instead of the measurement gap.

14 is a flowchart illustrating an order in which the terminal 150 exchanges signaling messages with the home base station 130 and the macro base station 140 in order to measure the reception of system information according to an embodiment of the present invention.

Likewise, except for steps S1435 and S1440, the description is the same as that described with reference to FIG. 9, and thus a detailed description thereof will be omitted. The terminal 150 receives the schedule gap instead of the measurement gap in step S1435. The terminal 150 starts measurement according to the schedule gap allocated from the macro base station 140 in step S1440.

15 is a flowchart illustrating a signaling message exchange procedure for receiving measurement of next system information according to readjustment of persistent scheduling and reallocation of a schedule gap after the terminal 150 fails to receive measurement of initial system information.

Similarly, except for the steps S1535, S1540, S1560, and S1565, the description is the same as that described with reference to FIG. In operation S1535, the terminal 150 receives a schedule gap instead of a measurement gap. In operation S1540, the terminal 150 starts measurement according to the schedule gap allocated from the macro base station 140.

In addition, the terminal 150 receives the reassigned schedule gap in step S1560, and starts measurement according to the schedule gap reassigned from the macro base station 140 in step S1565.

The embodiments of the present invention disclosed in the present specification and drawings are merely illustrative of specific embodiments of the present invention and are not intended to limit the scope of the present invention in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

1 is a conceptual diagram schematically illustrating a process of handing over to a home base station in a persistent scheduling service of a terminal in a femto cell system;

2 illustrates a radio frame structure 205 transmitted by a home base station 130 in a femtocell system of the present invention.

3 is a diagram illustrating a structure of a radio frame 305 in which the macro base station 140 of the present invention transmits persistent scheduling to the terminal 150. FIG.

4A is a diagram illustrating an example of a measurement gap pattern allocated to the terminal 150 by the macro base station 140 according to the first embodiment of the present invention.

FIG. 4B shows an example of a measurement gap that arbitrarily combines the plurality of measurement gap patterns shown in FIG. 4A. FIG.

5 is a diagram illustrating a method in which a terminal 150 of the present invention receives system information of a home base station according to a measurement gap allocated by a macro cell 140 among persistent scheduling services.

6 illustrates an example in which the terminal 150 of the present invention fails to obtain system information.

FIG. 7 is a diagram illustrating a method for measuring reception of system information by a terminal 150 reallocating a measurement gap after readjusting persistent scheduling. FIG.

8 is a flowchart illustrating a process in which the terminal 150 receives a measurement gap from a macro cell and measures reception of system information according to an exemplary embodiment of the present invention.

9 is a flowchart illustrating an order in which a terminal 150 exchanges signaling messages with a home base station 130 and a macro base station 140 to measure reception of system information according to an embodiment of the present invention.

10 is a flowchart illustrating a signaling message exchange procedure for reception measurement of next system information according to readjustment of persistent scheduling and reallocation of a measurement gap after the terminal 150 fails to measure initial system information.

FIG. 11 is a diagram illustrating a method of measuring reception of system information transmitted from a femto cell by a terminal of the present invention using a DRX operation cycle. FIG.

12 shows an example of a DRX operation cycle that the terminal 150 receives from the macro base station 140.

FIG. 13 is a flowchart illustrating a process in which a terminal 150 receives a schedule gap from a macro cell 140 and measures reception of system information according to an exemplary embodiment of the present invention.

14 is a flowchart illustrating a procedure in which a terminal 150 exchanges signaling messages with a home base station 130 and a macro base station 140 to measure reception of system information according to an embodiment of the present invention.

15 is a flowchart illustrating a signaling message exchange procedure for receiving measurement of next system information according to readjustment of persistent scheduling and reallocation of a schedule gap after the terminal 150 fails to receive measurement of initial system information.

Claims (24)

A method for initiating handover of a terminal in a femto cell, Reporting the reception of the physical layer cell identifier transmitted from the home base station to the macro base station; Allocating a time interval from the macro base station for measuring reception of system information transmitted from the home base station; Measuring reception of the system information in the allocated time interval; And Initiating a handover to the femtocell upon receiving the system information. The method of claim 1, And the terminal is in a persistent scheduling service. The method of claim 2, The time interval is a handover start method of the terminal, characterized in that allocated through a measurement gap (measurement gap). The method of claim 3, The measurement gap is composed of any combination of one or more measurement gap patterns including a gap period for stopping communication with the macro base station and measuring reception of system information transmitted from the home base station. Over start method. The method of claim 4, wherein The gap period does not overlap with the transmission time point of the persistent scheduling. The method of claim 5, Reporting failure of the reception of the system information to the macro base station; Rescheduling, by the macro base station, the transmission timing of the persistent scheduling; And And reassigning the measurement gap by changing the order of combining the measurement gap patterns by the macro base station. The method of claim 6, The gap period of the reassigned measurement gap and the transmission time of the readjusted persistent scheduling do not overlap. The method of claim 2, The time interval is handover start method of the terminal, characterized in that allocated through the operation period of the discontinuous reception mode of the terminal. The method of claim 8, The operation period of the discontinuous reception mode includes a sleep period for interrupting communication with the macro base station and measuring reception of system information transmitted from the home base station. 10. The method of claim 9, The sleep period is a handover initiation method of the terminal, characterized in that not overlap with the transmission time of the persistent scheduling. The method of claim 10, Reporting failure of the reception of the system information to the macro base station; Rescheduling, by the macro base station, the transmission timing of the persistent scheduling; And And adjusting, by the macro base station, the sleep interval to readjust the operation period of the discontinuous reception mode of the terminal. The method of claim 11, And the rescheduled sleep interval and the transmission time of the rescheduled persistent scheduling do not overlap. The method of claim 1, The system information includes at least one of a CSG ID and a GCI. A handover initiation system in a femtocell comprising a home base station, a macro base station, and a terminal, A home base station for transmitting a physical layer cell identifier and system information; A macro base station for allocating a time interval for the terminal to measure reception of the system information; And A terminal for reporting the reception of the physical layer cell identifier to the macro base station, measuring the reception of the system information in a time interval allocated from the macro base station, and initiating a handover to the femtocell upon receiving the system information; Handover initiation system in the femto cell, characterized in that. The method of claim 14, The terminal is a persistent scheduling service, characterized in that the handover initiation system in a femto cell. The method of claim 15, And wherein the macro base station allocates the time interval through a measurement gap. The method of claim 16, Wherein the measurement gap is comprised of any combination of one or more measurement gap patterns including a gap period for interrupting communication with the macro base station and measuring reception of system information transmitted from the home base station. Handover initiation system. The method of claim 17, The gap period does not overlap with the transmission time point of the persistent scheduling, the handover initiation system in the femto cell. The method of claim 18, When the macro base station fails to receive the system information of the terminal, the macro base station readjusts the transmission timing of the persistent scheduling, and reassigns the measurement gap in which the order of combining the measurement gap patterns is changed to the terminal. Handover initiation system. The method of claim 15, The macro base station allocates the time interval through an operation period of the discontinuous reception mode of the terminal, the handover initiation system in the femto cell. The method of claim 20, The operation period of the discontinuous reception mode includes a sleep period for stopping communication with the macro base station and measuring the reception of system information transmitted from the home base station. The method of claim 21, The sleep period is not overlapped with the transmission time point of the persistent scheduling handover initiation system in the femto cell. The method of claim 22, When the macro base station fails to receive the system information of the terminal, the macro base station readjusts the transmission time point of the persistent scheduling, and changes the sleep interval to readjust the operation period of the discontinuous reception mode of the terminal. Handover Initiation System. The method of claim 14, The system information includes at least one of a CSG ID and GCI handover initiation system in the femto cell.

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