JP2012004721A - Terminal device, base station device, mobile communication system and different frequency measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform measurement of a target cell, which is a candidate for a handover destination, while maintaining measurement accuracy of a current cell, which is a handover source, in a different frequency/different system.SOLUTION: In a terminal device, a receiving unit receives a main-measurement channel (first main-measurement channel) transmitted by a base station device, which is a handover source base station device and currently communicatively connected, and a sub-measurement channel (second sub-measurement channel) transmitted by a base station device, which is a candidate base station device for a handover destination base station device. Here, the first main-measurement channel is transmitted by means of a main frequency band f1 allocated to the base station device. In addition, the second sub-measurement channel is transmitted by means of a sub frequency band f2 which is a portion of the main frequency band f1. A reception level measurement unit measures reception levels of the first main-measurement channel and the second sub-measurement channel.

Description

  The present invention particularly relates to a terminal device, a base station device, a mobile communication system, and a different frequency measurement method in a mobile communication system using different frequency measurement (Inter Frequency / Inter RAT (Radio Access Technology) Measurement) of a mobile communication terminal device. .

  In a mobile communication system such as LTE (Long Term Evolution), UMTS (Universal Mobile Telecommunications System), or GSM (Global System for Mobile Communications), a method (cell configuration) of covering a service area with a plurality of base stations is used. When a mobile communication terminal apparatus (hereinafter abbreviated as “terminal apparatus”) requires cell switching (handover) due to movement, a neighboring cell (that is, a handover destination) that is a candidate for a cell after switching (that is, a handover destination) ( (Hereinafter referred to as “target cell”) (measurement of communication status with the target cell) is performed, and a switching destination cell is selected based on the measurement result.

  When the frequency channel (hereinafter referred to as “own frequency”) used in the current cell of the handover source (hereinafter referred to as “current cell”) and the frequency channel used in the target cell are different (hereinafter referred to as “inter-frequency (Inter frequency)” Frequency ”)) or when the wireless access method used in the current cell is different from the wireless access method used in the target cell (hereinafter referred to as“ Inter-RAT (Radio Access Technology) ”). In this case, the terminal device needs to perform measurement by switching the frequency channel.

  In order to perform such different frequency measurement or different system measurement (hereinafter abbreviated as “different frequency / different system measurement”) for the target cell during communication with the current cell, a compressed mode or a gap ( A technique called GAP) measurement is used (for example, see Non-Patent Documents 1, 2, 3, and 4).

  Hereinafter, operations of different frequency measurement in a conventional terminal device and a terminal device in a mobile communication system will be described with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of a base station apparatus and a terminal apparatus in a conventional mobile communication system.

  In the base station apparatus 10, the own station measurement channel generation unit 14 generates a measurement channel for the own station. The transmission unit 13 transmits the measurement channel for the local station and the transmission data to the terminal device 20 via the antenna 11. The receiving unit 12 receives a signal received by the antenna 11 and obtains received data.

  In the terminal device 20, the receiving unit 22 receives a signal received by the antenna 21, and obtains received data. Further, the reception level measurement unit 24 measures the reception level of the measurement channel transmitted from the base station apparatus 10. The transmission unit 23 transmits the reception level measurement result of the measurement channel measured by the reception level measurement unit 24 together with the transmission data from the antenna 21 to the base station apparatus 10 side. The reception level measurement results are aggregated in a mobile communication control station (not shown) that controls the base station devices in a bundle, and are used for handover determination.

  FIG. 2 is a diagram for explaining the operation of the different frequency / different system measurement in the terminal device 20.

  The terminal apparatus 20 is designated by the base station apparatus 10 at a position and period (hereinafter referred to as a gap period) for performing different frequency / different system measurement. Then, the terminal device 20 performs different frequency / different system measurement according to the designated gap period. Specifically, the terminal device 20 switches and controls the reception level measurement unit 24 according to the gap period specified by the base station device 10, and performs its own frequency measurement and different frequency / different system measurement.

  For example, as illustrated in FIG. 2, the terminal device 20 performs communication / measurement in the current cell of the handover source except in the gap period, and switches the frequency to the frequency of the target cell that is the candidate of the handover destination in the gap period. Measure different frequency / different system.

3GPP TS 25.212 V9.2.0 (2010-03) 3GPP TS 25.215 V9.2.0 (2010-03) 3GPP TS 36.133 V9.3.0 (2010-03) 3GPP TS 36.300 V9.3.0 (2010-03)

  However, in the conventional terminal device and mobile communication system, when the gap period is increased, the measurement time of the target cell increases, while the communication / measurement time in the current cell decreases, and the measurement accuracy of the current cell deteriorates. On the other hand, if the gap period is reduced, the communication / measurement time of the current cell increases and the degradation of the measurement accuracy of the current cell can be suppressed, but the measurement time of the target cell decreases and the measurement accuracy of the target cell deteriorates. . Thus, there is a problem that there is a trade-off relationship between the measurement accuracy of the current cell and the measurement accuracy of the target cell.

  The present invention has been made in view of such a point, and in a different frequency / different system, a terminal capable of measuring a target cell that is a handover destination candidate while maintaining measurement accuracy of a current cell that is a handover source. An object is to provide a device, a base station device, a mobile communication system, and a different frequency measurement method.

  One aspect of the terminal apparatus of the present invention is transmitted from a first base station apparatus that is a handover source base station apparatus using a first frequency band assigned to the first base station apparatus, and A first main measurement channel used for determining a communication status between one base station apparatus and the own apparatus, and a second base station apparatus that is a candidate for a handover destination base station apparatus, Receiving means for receiving a sub-measurement channel used for determining a communication status between a base station apparatus and the own apparatus, and measuring means for measuring reception levels of the first main measurement channel and the sub-measurement channel; The sub-measurement channel is transmitted using a sub-frequency band that is a partial frequency band within the first frequency band.

  One aspect of the base station apparatus of the present invention is the first main measurement used for determining the communication status between the local station and the terminal apparatus in communication using the first frequency band assigned to the local station. A channel is transmitted, and a first sub frequency band that is a part of a second frequency band assigned to another station is used to determine a communication status between the other station and a terminal device in communication. Transmitting means for transmitting the first sub measurement channel to be used is provided.

  According to these configurations, the terminal device can perform measurement of the target cell that is the candidate of the handover destination by using the frequency band of the current cell that is the handover source, while maintaining the measurement accuracy of the current cell, Measurement of the target cell can be performed.

  One aspect of the different frequency measurement method of the present invention is that a handover destination base station apparatus to which a terminal apparatus is connected for communication is moved from a first base station apparatus that is a handover source base station apparatus to which a first frequency band is allocated. , A different frequency measurement method used for handover determination to switch to a second base station apparatus to which a second frequency band is allocated, wherein the first base station apparatus uses the first frequency band to And transmitting a first main measurement channel used for determining a communication status between the base station apparatus and the terminal apparatus, and using a first sub-frequency band that is a part of the second frequency band. The first sub measurement channel is transmitted, and the second base station apparatus transmits the second main measurement channel using the second frequency band, and a part of the first frequency band. A second sub measurement channel used for determining a communication status between the second base station apparatus and the terminal apparatus is transmitted using a second sub frequency band which is a wave number band, and the terminal apparatus Receiving the first main measurement channel transmitted from the first base station apparatus in communication connection and the second sub measurement channel transmitted from the second base station apparatus; The reception level of one main measurement channel and the sub measurement channel is measured.

  According to this method, since the terminal apparatus can measure the target cell of the handover destination candidate using the frequency band of the current cell of the handover source, it can maintain the measurement accuracy of the current cell while maintaining the measurement accuracy of the current cell. Measurements can be made.

  According to the present invention, in a different frequency / different system, it is possible to measure the target cell of the handover destination candidate while maintaining the measurement accuracy of the current cell of the handover source.

The block diagram which shows the principal part structure of the conventional base station apparatus and a terminal device The figure for demonstrating the operation | movement of the conventional different frequency / different system measurement The figure which shows the structural example of the mobile communication system which concerns on Embodiment 1 of this invention. FIG. 3 is a block diagram showing a main configuration of the base station apparatus according to Embodiment 1. FIG. 3 is a block diagram showing a main configuration of the terminal apparatus according to Embodiment 1. The figure which shows the mode of the reception level of the main measurement channel and sub measurement channel transmitted from the base station apparatus of the own cell received from the terminal device, and the base station apparatus of another cell The figure which shows the main measurement channel transmitted from the present cell of a handover origin, and the sub measurement channel transmitted from the target cell of the candidate of a handover destination The block diagram which shows the principal part structure of the base station apparatus which concerns on Embodiment 2 of this invention. FIG. 3 is a block diagram showing a main configuration of a terminal apparatus according to Embodiment 2. The figure which shows the mode of the reception level of the main measurement channel and sub measurement channel transmitted from the base station apparatus of the own cell received from the terminal device, and the base station apparatus of another cell The figure which shows the structural example of the mobile communication system which concerns on Embodiment 3 of this invention. In the third embodiment, the main measurement channel (first main measurement channel) of the current cell as the handover source, the main measurement channel (second main measurement channel) and the sub measurement channel of the target cell # 2 as the handover destination candidate, The figure which shows the main measurement channel (3rd main measurement channel) and sub measurement channel of target cell # 3 of the candidate of a handover destination In the fourth embodiment of the present invention, the main measurement channel (first main measurement channel) of the current cell as the handover source, the main measurement channel (second main measurement channel) of the target cell # 2 as the handover destination candidate, and the sub measurement The figure which shows the main measurement channel (3rd main measurement channel) and sub measurement channel of target cell # 3 of the candidate cell of handover destination The figure which shows the main measurement channel (1st main measurement channel) of the present cell of a handover origin, and the sub measurement channel of the target cell of a candidate of a handover destination in Embodiment 5 of this invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 3 shows a configuration example of the mobile communication system according to the present embodiment. As illustrated in FIG. 3, the mobile communication system includes a base station device 100, a base station device 100A, and a terminal device 200. In FIG. 3, a base station apparatus 100 is a base station apparatus of a current cell that is a handover source with which a terminal apparatus 200 is connected for communication. In FIG. 3, base station apparatus 100A is a base station apparatus of a cell adjacent to the current cell with which terminal apparatus 200 is communicating. That is, the base station apparatus 100A is a base station apparatus of a target cell that is a candidate for a handover destination with which the terminal apparatus 200 may communicate, for example, a base station apparatus of an adjacent cell of the current cell.

  In the following, the frequency band (hereinafter referred to as “main frequency band”) assigned to the base station apparatus 100 of the current cell that is the handover source of the terminal apparatus 200 is f1, and the base station apparatus 100A of the target cell that is the candidate of the handover destination. A case will be described as an example where the assigned frequency band (main frequency band) is f2.

  FIG. 4 is a block diagram showing a main configuration of the base station apparatus according to the present embodiment. The configurations of base station apparatus 100 and base station apparatus 100A are the same. Therefore, the configuration of base station apparatus 100 will be described below.

  The base station apparatus 100 illustrated in FIG. 4 includes a local cell measurement channel generation unit 120, a sub measurement channel generation unit 130, a transmission unit 140, and a reception unit 150.

  The own cell measurement channel generation unit 120 generates a main measurement channel, and outputs the generated main measurement channel to the transmission unit 140. Here, the main measurement channel is a measurement channel that is used by a terminal device that is communicatively connected to its own station to determine the communication status in its own cell. As will be described later, the main measurement channel is transmitted using the main frequency band assigned to the own station. The main measurement channel will be described later.

  The sub measurement channel generation unit 130 generates a sub measurement channel and outputs the generated sub measurement channel to the transmission unit 140. Here, the sub-measurement channel is a measurement channel that is used by a terminal apparatus that is currently in communication connection with a station other than its own station to determine the communication status in its own cell. As will be described later, the sub measurement channel is transmitted using a part of the main frequency band allocated to other stations other than the own station (hereinafter also referred to as “sub frequency band”). The sub measurement channel will be described later.

  Transmitting section 140 transmits the main measurement channel using the main frequency band assigned to the own station (base station apparatus 100). In addition, the transmission unit 140 transmits the sub measurement channel using a partial frequency band (sub frequency band) of the main frequency band allocated to another station (base station apparatus 100A) of the target cell adjacent to the own cell. To do. Note that the sub-frequency band is specified in advance, for example, at a position away from the start frequency of the main frequency band in the target cell by a predetermined frequency. Further, the transmission unit 140 transmits transmission data and information related to handover control (handover control information) via the antenna 110. The handover control information will be described later.

  The receiving unit 150 receives a signal received via the antenna 110 and obtains received data.

  FIG. 5 is a block diagram showing a main configuration of the terminal apparatus according to the present embodiment.

  The terminal device 200 illustrated in FIG. 5 includes a reception unit 220, a reception level measurement unit 230, and a transmission unit 240.

  The receiving unit 220 receives a signal received via the antenna 210 and obtains received data. Then, receiving section 220 extracts information related to handover control (handover control information) from the received data, and identifies main frequency band f1 assigned to base station apparatus 100 of the current cell based on the extracted handover control information. . Furthermore, the receiving unit 220 specifies the sub frequency band f′2 used by the base station device 100A of the target cell adjacent to the current cell to transmit the sub measurement channel.

  The reception level measurement unit 230 measures the reception level of the main measurement channel transmitted from the base station apparatus 100 and the reception level of the sub measurement channel transmitted from the base station apparatus 100A. The reception level measurement unit 230 outputs the reception level measurement results of the main measurement channel and the sub measurement channel to the transmission unit 240.

  The transmission unit 240 transmits the transmission data, reception level measurement results of the main measurement channel and the sub measurement channel to the base station apparatus 100 via the antenna 210. The reception level measurement results are aggregated in a mobile communication control station (not shown) that controls the base station apparatuses 100 and 100A in a bundle, and are used for handover determination material.

  Operations of base station apparatus 100, base station apparatus 100A, and terminal apparatus 200 configured as described above will be described.

  The transmission unit 140 of the base station apparatus 100 transmits the main measurement channel generated by the own cell measurement channel generation unit 120 to the terminal apparatus 200 using the main frequency band f1. In addition, the transmission unit 140 of the base station device 100A transmits the sub measurement channel generated by the sub measurement channel generation unit 130 to the terminal device 200 using the sub frequency band f'2. Here, the sub-frequency band f'2 is a partial frequency band (specific narrow band) of the main frequency band f1 of the current cell.

  Note that base station apparatus 100 transmits a sub measurement channel using sub frequency band f'1. Here, the sub frequency band f′1 is a part of the main frequency band f2 assigned to the base station apparatus 100A of the target cell. In addition, the base station device 100A transmits the main measurement channel using the main frequency band f2.

  FIG. 6 is a diagram illustrating the reception levels of the main measurement channel and the sub measurement channel transmitted from the base station apparatus 100 and the base station apparatus 100A received by the terminal apparatus 200. In FIG. 6, the horizontal axis represents frequency and the vertical axis represents reception level. For the sake of brevity, the sub measurement channel transmitted from the base station apparatus 100 using the sub frequency band f'1 is omitted in FIG.

  The terminal apparatus 200 specifies the main frequency band f1 used for transmission of the main measurement channel based on the handover information notified from the base station apparatus 100, and also uses the sub frequency band f′2 used for transmission of the sub measurement channel. Is identified. Then, the receiving unit 220 of the terminal device 200 receives the main measurement channel transmitted from the base station apparatus 100 of the current cell using the main frequency band f1, and the sub frequency band f′2 from the base station apparatus 100A of the target cell. The sub-measurement channel transmitted using is received.

  As described above, since the sub frequency band f′2 in which the sub measurement channel is transmitted is within the band of the main frequency band f1 of the current cell, the terminal device 200 does not perform the frequency switching operation, and thus the target cell Can be measured. Thus, the terminal device 200 can perform the measurement of the target cell in parallel while continuing the measurement of the current cell. Therefore, base station apparatus 100 can continuously transmit the main measurement channel without providing a gap period as shown in FIG.

  Thus, in the present embodiment, base station apparatus 100 in the current cell of terminal apparatus 200 continuously transmits the main measurement channel using main frequency band f1 allocated to the own station. Further, the base station device 100A of the target cell uses a sub frequency band f′2 that is a part of the main frequency band f1 allocated to the base station device 100 of the current cell of the terminal device 200, Transmit sub measurement channel continuously. As a result, it is possible to suppress a decrease in the communication / measurement time of the current cell, so that the current cell measurement accuracy is improved. As a result, the handover operation is performed appropriately and quickly, and the communication quality can be improved. .

  In the terminal device 200, the transmission unit 240 transmits information on the reception levels of the main measurement channel and the sub measurement channel measured by the reception level measurement unit 230 to the base station device 100. The base station device 100 The mobile communication control station is notified of information on the reception level of the sub measurement channel. Then, the mobile communication control station performs handover control based on the reception levels of the main measurement channel and the sub measurement channel, and notifies the base station apparatus 100 of information related to handover (handover information).

  As described above, in the present embodiment, in terminal apparatus 200, receiving section 220 has a main measurement channel (first measurement channel) transmitted from base station apparatus 100 that is a base station apparatus that is currently connected for communication and is a handover source. Main measurement channel) and a sub measurement channel (second sub measurement channel) transmitted from the candidate base station device 100A of the handover destination base station device. Here, the first main measurement channel is transmitted using the main frequency band f1 assigned to the base station apparatus 100. Further, the second sub measurement channel is transmitted using the sub frequency band f'2, which is a part of the main frequency band f1. The reception level measurement unit 230 measures the reception levels of the first main measurement channel and the second sub measurement channel.

  In the base station apparatus 100, the transmission unit 140 transmits the main measurement channel (first main measurement channel) using the main frequency band f1 allocated to the own station, and is allocated to the base station apparatus 100A of another cell. The sub measurement channel (first sub measurement channel) is transmitted using the sub frequency band f′1, which is a part of the main frequency band f2. In base station apparatus 100A, transmission section 140 transmits a main measurement channel (second main measurement channel) using main frequency band f2 allocated to the own station, and is allocated to base station apparatus 100 of another cell. The sub measurement channel (second sub measurement channel) is transmitted using the sub frequency band f′2, which is a part of the frequency band in the frequency band f1.

  As a result, the terminal device 200 continues to measure the main measurement channel (first main measurement channel) transmitted from the base station device 100 of the current cell using the main frequency band f1, while the base station device 100A of the target cell. The measurement of the sub measurement channel (second sub measurement channel) transmitted using the sub frequency band f′2 (a part of the frequency band f1) can be performed in parallel.

  As a result, as shown in FIG. 7, the main measurement channel (first main measurement channel) can be continuously transmitted without providing a gap period, thereby suppressing a decrease in communication / measurement time of the current cell. Measurement accuracy is improved, handover operation is performed appropriately and quickly, and communication quality can be improved.

(Embodiment 2)
In the first embodiment, the case has been described in which the gap mode is not provided and the continuous mode in which the base station apparatus of the current cell that is the handover source continuously transmits the main measurement channel (first main measurement channel) is used. In the present embodiment, a case will be described in which the base station apparatus of the current cell that is the handover source controls the frequency of providing the gap period based on the threshold determination result between the reception level of the sub measurement channel and a predetermined threshold.

  Since the configuration example of the mobile communication system according to the present embodiment is the same as that of the first embodiment, illustration and description thereof are omitted. Note that the mobile communication system according to the present embodiment includes base station apparatus 300, base station apparatus 300A, and terminal apparatus 400. The base station apparatus 300 is a base station apparatus of a current cell that is a handover source with which the terminal apparatus 400 is communicating, and the base station apparatus 300A is a base station apparatus of a cell that is close to the current cell with which the terminal apparatus 400 is communicating. It is. That is, the base station apparatus 300A is a base station apparatus of a target cell that is a candidate for a handover destination with which the terminal apparatus 400 may communicate, for example, a base station apparatus of an adjacent cell of the current cell.

  In the following, the frequency band (main frequency band) allocated to the base station apparatus 300 of the current cell that is the handover source of the terminal apparatus 400 is f1, and the frequency allocated to the base station apparatus 300A of the target cell that is the handover destination candidate. A case where the band (main frequency band) is f2 will be described as an example.

  FIG. 8 is a block diagram showing a main configuration of the base station apparatus according to the present embodiment. The configurations of base station apparatus 300 and base station apparatus 300A are the same. Therefore, hereinafter, the configuration of base station apparatus 300 will be described.

  In the base station apparatus 300 of FIG. 8, the same components as those of the base station apparatus 100 of FIG. 4 are denoted by the same reference numerals as those in FIG. The base station apparatus 300 in FIG. 8 has a configuration in which a transmission unit 320 is added instead of the transmission unit 140 and a mode determination unit 310 is added to the base station apparatus 100 in FIG.

  The mode determination unit 310 controls the presence / absence of a gap period based on the reception level of the sub measurement channel notified from the terminal device 400. Specifically, mode determination section 310 determines whether to continue the continuous mode or switch from the continuous mode to the gap based on the reception level of the sub measurement channel notified from terminal apparatus 400. Here, the continuous mode is a mode in which a main measurement channel is continuously transmitted without providing a gap period, and the gap mode is a mode in which a gap period is provided and the main measurement channel is not transmitted in the gap period.

  Note that after switching to the gap mode, the mode determination unit 310 may further determine whether to switch from the gap mode to the continuous mode based on the reception level of the sub measurement channel notified from the terminal device 400. In this way, the mode determination unit 310 controls the frequency of providing the gap period based on the reception level of the sub measurement channel notified from the terminal device 400. Mode determining section 310 outputs information related to the determined transmission mode (hereinafter referred to as “mode information”) to transmitting section 320.

  The transmission unit 320 transmits the main measurement channel according to the mode information. Specifically, when the mode information indicates the continuous mode, the transmission unit 320 continuously transmits the main measurement channel without providing a gap period. On the other hand, when the mode information indicates the gap mode, the transmission unit 320 provides a gap period, does not transmit the main measurement channel during the gap period, and transmits the main measurement channel only during the gap period.

  FIG. 9 is a block diagram showing a main configuration of the terminal apparatus according to the present embodiment. In the terminal device 400 of FIG. 9, the same components as those of the terminal device 200 of FIG. 9 has a reception unit 410 and a reception level measurement unit 420 instead of the reception unit 220 and the reception level measurement unit 230, and adds a mode determination unit 430 to the terminal device 400 of FIG. Adopted the configuration.

  The receiving unit 410 receives a signal received via the antenna 210 and obtains received data. Then, receiving section 410 extracts information related to handover control (handover control information) from the received data, and identifies main frequency band f1 assigned to base station apparatus 300 of the current cell based on the extracted handover control information. . Furthermore, receiving section 410 identifies sub frequency band f'2 used by base station apparatus 300A of the target cell, which is a cell around the current cell, to transmit a sub measurement channel.

  Furthermore, the reception unit 410 switches the reception frequency according to mode information notified from a mode determination unit 430 described later. Specifically, when the mode information indicates the continuous mode, the reception unit 410 adjusts the reception frequency to the main frequency band f1 and is transmitted from the base station apparatus 300 of the current cell (first main measurement channel). Are received continuously. On the other hand, when the mode information indicates the gap mode, the reception unit 410 adjusts the reception frequency to the main frequency band f1 and transmits the main measurement channel (first measurement channel) (first first) in the current cell except for the gap period. Main measurement channel) is continuously received, and during the gap period, the main measurement channel (second main measurement channel) transmitted from the base station apparatus 300A of the target cell is received in accordance with the main frequency band f2.

  The reception level measurement unit 420 measures the reception level as follows according to mode information notified from a mode determination unit 430 described later.

[When mode information indicates continuous mode]
When the mode information indicates the continuous mode, the reception level measurement unit 420 is the main measurement channel (first main measurement channel) transmitted from the base station device 300, as with the reception level measurement unit 230 of the first embodiment. And the reception level of the sub measurement channel (second sub measurement channel) transmitted from the base station apparatus 300A.

[When mode information indicates gap mode]
In the gap mode, except for the gap period, the main frequency band f1 is used to transmit the main measurement channel (first main measurement channel) from the base station apparatus 300, and the sub frequency band f ′ is transmitted from the base station apparatus 300A. 2 is used to transmit the sub-measurement channel. In the gap period, the main measurement channel (second main measurement channel) is transmitted from the base station device 300A using the main frequency band f2.

  Therefore, when the mode information indicates the gap mode, the reception level measurement unit 420 switches the frequency band to be measured between the gap period and the gap period.

  Specifically, the reception level measurement unit 420 receives the reception level of the main measurement channel (first main measurement channel) transmitted from the base station apparatus 300 and the sub measurement transmitted from the base station apparatus 300A, except for the gap period. The reception level of the channel (second main measurement channel) is measured. On the other hand, in the gap period, reception level measuring section 420 measures the reception level of the main measurement channel (second main measurement channel) transmitted from base station apparatus 300A.

  That is, the receiving unit 410 switches the reception frequency before and after the gap period. Then, outside the gap period, the receiving unit 410 receives the main measurement channel (first main measurement channel) transmitted in the main frequency band f1 of the current cell, and transmits in the main frequency band f2 of the target cell in the gap period. Receiving the second main measurement channel.

  Then, the reception level measurement unit 420 switches the measurement frequency band according to the gap period. Specifically, the reception level measurement unit 420 receives the reception level of the main measurement channel (first main measurement channel) transmitted in the main frequency band f1 of the current cell and the sub frequency band of the target cell, except for the gap period. The reception level of the sub measurement channel (second sub measurement channel) transmitted at f′2 is measured. The reception level measurement unit 420 measures the reception level of the main measurement channel (second main measurement channel) transmitted in the main frequency band f2 of the target cell in the gap period.

  The mode determination unit 430 determines whether the main measurement channel (first main measurement channel) is transmitted in the continuous mode or the gap mode based on the reception level of the sub measurement channel. The transmission mode determination method in mode determination unit 430 will be described later. Mode determination section 430 outputs the determined transmission mode information (mode information) to reception section 410 and reception level measurement section 420.

  Operations of base station apparatus 300, base station apparatus 300A, and terminal apparatus 400 configured as described above will be described.

  FIG. 10 shows a main measurement channel (first main measurement channel) transmitted from the base station apparatus 300, a main measurement channel (second main measurement channel) transmitted from the base station apparatus 300A, and a sub received by the terminal apparatus 400. It is a figure which shows the mode of the reception level of a measurement channel. In FIG. 10, the horizontal axis represents time, and the vertical axis represents the reception level.

  As illustrated in FIG. 10, the transmission unit 320 of the base station device 300 uses the main frequency band f1 as the terminal device 400 using the main measurement channel (first main measurement channel) generated by the own cell measurement channel generation unit 120. Send continuously. Moreover, the transmission part 320 of base station apparatus 300A transmits the sub measurement channel produced | generated in the sub measurement channel production | generation part 130 to the terminal device 400 using sub frequency band f'2.

  Then, the terminal apparatus 400 identifies the frequency band f1 of the current cell and the sub-frequency band f′2 of the target cell based on the handover information notified from the base station apparatus 300, and is transmitted from the base station apparatus 300. The main measurement channel (first main measurement channel) in the frequency band f1 and the sub measurement channel in the sub frequency band f′2 transmitted from the base station apparatus 300A are received.

  At this time, similarly to the base station device 100A, the base station device 300A of the target cell is a part of the main frequency band f1 of the current cell, that is, the sub-frequency band f′2 that is a specific narrow band of the frequency band f1. Is used to transmit the sub measurement channel. Thus, since the sub frequency band f′2 in which the sub measurement channel is transmitted is a frequency band within the main frequency band f1 of the current cell, the terminal device 400 does not perform the frequency switching operation, and thus the target cell Can be measured.

  In terminal apparatus 400, transmission section 240 transmits the reception levels of the main measurement channel (first main measurement channel) and the sub measurement channel to base station apparatus 300.

  Then, in base station apparatus 300, mode determining section 310 continuously transmits the main measurement channel (first main measurement channel) based on the reception level of the sub measurement channel notified from terminal apparatus 400 (continuous mode). Then, it is determined whether to provide a gap period during which the main measurement channel (first main measurement channel) is not transmitted (gap mode).

  Moreover, in the terminal device 400, the mode determination unit 430 transmits the main measurement channel (first main measurement channel) in the continuous mode based on the reception level of the sub measurement channel. ) Is transmitted in the gap mode.

  Hereinafter, a mode determination method in mode determination unit 310 and a mode determination method in mode determination unit 430 will be described. Since the mode determination method in the mode determination unit 310 is the same as the mode determination method in the mode determination unit 430, the determination method of the mode determination unit 310 will be described below.

  The mode determination unit 310 determines the reception level of the sub measurement channel as a predetermined threshold value. Then, the mode determination unit 310 continuously transmits the main measurement channel (first main measurement channel) as follows based on the threshold determination result between the reception level of the sub measurement channel and the predetermined threshold (continuous). Mode) or whether to transmit with a gap period (gap mode).

[1] When the reception level of the sub measurement channel is less than the predetermined threshold When the reception level of the sub measurement channel is less than the predetermined threshold, even if the target cell is measured in the gap period by providing a gap period, It is likely that it is difficult to measure accurately. Therefore, when the reception level of the sub measurement channel is less than the predetermined threshold, the mode determination unit 310 determines to transmit the main measurement channel (first main measurement channel) in the continuous mode.

[2] When the reception level of the sub measurement channel is equal to or greater than a predetermined threshold When the reception level of the sub measurement channel is equal to or greater than the predetermined threshold, the target cell is measured by providing a gap period and measuring the target cell in the gap period. There is a high possibility that the measurement accuracy can be improved. Therefore, when the reception level of the sub measurement channel is equal to or higher than the predetermined threshold, mode determination section 310 determines to transmit the main measurement channel (first main measurement channel) in the gap mode.

  In this way, mode determination section 310 determines the transmission mode of the main measurement channel (first main measurement channel) based on the reception level of the sub measurement channel.

  Similarly, mode determination unit 430 determines the transmission mode of the main measurement channel (first main measurement channel) based on the reception level of the sub measurement channel.

  Then, when the reception level of the sub measurement channel is less than the predetermined threshold, as illustrated in FIG. 7, the base station apparatus 300 continuously transmits the main measurement channel without providing a gap period. On the other hand, when the reception level of the sub measurement channel is equal to or higher than the predetermined threshold, as shown in FIG. 10, the base station apparatus 300 provides a gap period, and the main measurement channel (first main measurement channel) in the gap period. Do not send. As described above, the mode determination unit 310 sets the gap period as much as necessary based on the reception level of the sub measurement channel.

  At this time, the base station apparatus 300A of the target cell uses a part of the main frequency band f1 of the current cell, that is, a sub-frequency band f′2, which is a specific narrow band of the main frequency band f1, to set a sub measurement channel. In addition to transmission, the main measurement channel (second main measurement channel) is transmitted using the main frequency band f2 of the own cell.

  Therefore, the terminal device 400 switches the reception frequency of the reception unit 410 and the measurement frequency of the reception level measurement unit 420 according to the mode information from the mode determination unit 430. Specifically, the reception frequency and the measurement frequency are set to the frequency band f1 except in the gap period, and are set to the frequency band f2 in the gap period.

  Then, the reception level measurement unit 420 measures the reception level of the main measurement channel (second main measurement channel) transmitted in the main frequency band f2 of the target cell in the gap period. In addition, during the period other than the gap period, the reception levels of the main measurement channel (first main measurement channel) of the current cell and the sub measurement channel of the target cell are measured.

  In this way, when the reception level of the sub measurement channel transmitted using the sub frequency band f′2 is equal to or higher than the predetermined threshold, the transmission mode is set to the gap mode and the gap period is provided. In the gap period, the reception level of the main measurement channel (second main measurement channel) transmitted using the main frequency band f2 of the target cell can be measured. Thereby, the measurement accuracy of the target cell can be improved.

  The reception level measurement unit 420 receives the main measurement channel (first main measurement channel) and sub measurement channel measured outside the gap period, or the main measurement channel (second main measurement channel) of the target cell measured in the gap period. The level is output to the transmission unit 240.

  The transmitter 240 receives the reception level of the main measurement channel (first main measurement channel) and the sub measurement channel measured outside the gap period, or the main measurement channel (second main measurement channel) of the target cell measured during the gap period. Information is transmitted to the base station apparatus 300, and the base station apparatus 300 notifies the mobile communication control station of information on these reception levels.

  Then, in the mobile communication control station, handover control is performed based on the information on the reception level, and information related to handover (handover information) is notified to the base station devices 300 and 300A.

  At this time, the reception level of the main measurement channel (second main measurement channel) of the target cell is a level measured in a state where the main measurement channel (first main measurement channel) of the current cell is not transmitted due to the gap period. Therefore, the measurement accuracy is improved as compared with the case where the target cell is measured using the sub measurement channel.

  As described above, when the reception level of the sub measurement channel using the sub frequency band f′2 is equal to or higher than the predetermined threshold, the target cell is optimal for the terminal device 400, and there is a possibility of triggering handover, the gap By providing a period and improving the measurement accuracy of the main measurement channel (second main measurement channel) of the target cell, appropriate handover control can be performed.

  As described above, in this embodiment, in base station apparatus 300 that is a handover source base station apparatus, mode determining section 310 performs main measurement channel (first main measurement channel) based on the reception level of the sub measurement channel. ) Is transmitted in the continuous mode or in the gap mode, and the presence or absence of the gap period is controlled.

  Then, in terminal apparatus 400, mode determination section 430 determines the presence or absence of a gap period during which the main measurement channel (first main measurement channel) is not transmitted, based on the reception level of the sub measurement channel. In the gap period, the receiving unit 410 transmits a main measurement channel (second main measurement channel) transmitted using the main frequency band f2 assigned to the base station device 300A from the base station device 300A of the target cell that is the handover destination candidate. The reception level measurement unit 420 measures the reception level of the main measurement channel (second main measurement channel) transmitted from the base station apparatus 300A of the target cell using the main frequency band f2 during the gap period. To do. Thereby, since the measurement accuracy of the target cell is improved, the handover operation is performed appropriately and quickly, and the communication quality can be improved.

  In the above description, a case has been described in which each of mode determination section 310 of base station apparatus 300 and mode determination section 430 of terminal apparatus 400 determines and determines the transmission mode based on the reception level of the sub measurement channel. However, it is not limited to this. For example, the mode determination unit 430 of the terminal device 400 may notify the base station device 300 of information regarding the determined transmission mode. Alternatively, the mode determination unit 310 of the base station device 300 may notify the terminal device 400 of information regarding the determined transmission mode. In this case, either the mode determination unit 310 or the mode determination unit 430 is not required, but signaling regarding the transmission mode is required. Therefore, from the viewpoint of throughput, it is preferable that the mode determination unit 310 of the base station device 300 and the mode determination unit 430 of the terminal device 400 each determine and determine the transmission mode based on the reception level of the sub measurement channel. .

(Embodiment 3)
In the present embodiment, a case will be described in which a main frequency band (second frequency band) allocated to a handover target candidate target cell is associated with a frequency band in which a sub measurement channel is transmitted.

  FIG. 11 shows a configuration example of a mobile communication system according to the present embodiment. In the mobile communication system of FIG. 11, the same reference numerals as those in FIG. As shown in FIG. 11, the mobile communication system according to the present embodiment includes base station apparatus 100, base station apparatus 100A, base station apparatus 100B, and terminal apparatus 200.

  The base station apparatus 100 is a base station apparatus of a current cell that is a handover source with which the terminal apparatus 200 is communicating, and the base station apparatuses 100A and 100B are base stations of cells that are close to the current cell with which the terminal apparatus 200 is communicating. It is a station device. That is, base station apparatuses 100A and 100B are base station apparatuses of target cells # 2 and # 3 that are candidates for handover destination with which terminal apparatus 200 may communicate. For example, base station apparatuses of adjacent cells of the current cell It is.

  In addition, since the structure of base station apparatus 100, 100A, 100B and the terminal device 200 is the same as that of Embodiment 1 or Embodiment 2, below, it demonstrates with reference to the structure of Embodiment 1. FIG.

  FIG. 12 shows the main measurement channel (first main measurement channel) of the current cell, the main measurement channel (second main measurement channel) and sub measurement channel of the target cell # 2, and the main measurement channel (first measurement channel) of the target cell # 3. FIG. 3 is a diagram showing (3 main measurement channels) and sub measurement channels.

  As shown in FIG. 12, the base station apparatus 100 of the current cell transmits the main measurement channel (first main measurement channel) using the main frequency band (first frequency band) f1. The base station device 100A of the target cell # 2 transmits the main measurement channel (second main measurement channel) of the target cell # 2 using the main frequency band (second frequency band) f2, and performs sub-measurement of the target cell # 2. The channel is transmitted using the sub-frequency band f′2. Further, the base station device 100A of the target cell # 3 transmits the main measurement channel (third main measurement channel) of the target cell # 3 using the main frequency band (third frequency band) f3, and The sub measurement channel is transmitted using the sub frequency band f′3.

  At this time, in the present embodiment, the base station apparatus of the target cell #i (i = 2, 3) has a sub-frequency band (i-th sub-frequency band) associated with the main frequency band (i-th frequency band) fi. ) Use f′i to transmit the sub measurement channel. For example, a frequency band that is separated from the main frequency band fi allocated to the base station apparatus of the target cell #i (i = 2, 3) by a predetermined frequency difference is set as the sub frequency band f′i of the sub measurement channel. Thereby, the reception level measurement unit 230 can measure the target cell #i having the main frequency band fi based on the reception level of each frequency band f'i in the main frequency band f1 of the current cell.

  As described above, in the present embodiment, the sub frequency band (i th sub frequency band) f′i of the sub measurement channel of the target cell #i and the main frequency band (i th frequency) assigned to the target cell #i. Band) fi. Thereby, the terminal device 200 measures the reception level of the sub measurement channel transmitted in a predetermined frequency band f′i that is a part of the main frequency band f1 of the current cell, thereby measuring the corresponding target cell. be able to.

(Embodiment 4)
In Embodiment 3, the sub-frequency band (i-th sub-frequency band) f′i of the sub-measurement channel of the target cell #i that is the handover destination candidate, and the main frequency band (i-th frequency) assigned to the target cell #i A case has been described in which band) fi is associated with one-to-one.

  In the present embodiment, the sub-frequency position fs of the sub-measurement channel is shared by a plurality of target cells that are handover destination candidates, and each target cell transmits the sub-measurement channel using the sub-frequency position fs in a time-sharing manner. The case will be described.

  Since the configurations of the mobile communication system, the base station apparatus, and the terminal apparatus according to the present embodiment are the same as those of the third embodiment, the configuration of the third embodiment will be described below.

  FIG. 13 shows the main measurement channel (first main measurement channel) of the current cell, the main measurement channel (second main measurement channel) and sub measurement channel of the target cell # 2, and the main measurement channel (first measurement channel) of the target cell # 3. FIG. 3 is a diagram showing (3 main measurement channels) and sub measurement channels.

  As illustrated in FIG. 13, the base station apparatus 100 of the current cell transmits the first main measurement channel using the main frequency band f1. The base station device 100A of the target cell # 2 transmits the second main measurement channel of the target cell # 2 using the main frequency band f2. The base station device 100B of the target cell # 3 transmits the third main measurement channel of the target cell # 3 using the main frequency band f3.

  Furthermore, in the present embodiment, base station apparatus 100A of target cell # 2 and base station apparatus 100B of target cell # 3 use sub-frequency band fs in a time-sharing manner, and target cells # 2 and # 3 Transmit sub measurement channels. Here, the sub frequency band fs is a partial frequency band of the main frequency band f1 of the current cell. Information such as time division timing (hereinafter referred to as “time division information”) is notified from the mobile communication control station to the base station apparatuses 100A and 100B.

  The terminal device 200 receives the reception level of the sub measurement channel transmitted in time division from each target cell using the sub frequency band fs according to the time division information notified from the mobile communication control station or the base station devices 100A and 100B. Measure.

  As described above, in the present embodiment, since a plurality of sub measurement channels are transmitted in a time-sharing manner, the interference that the main measurement channel (first main measurement channel) of the current cell receives by the sub measurement channel is limited. Therefore, it is possible to suppress degradation of measurement accuracy of the current cell.

  As described above, in the present embodiment, in base station apparatuses 100A and 100B of a plurality of target cells, transmission section 140 transmits some frequency bands fs within main frequency band f1 of base station apparatus 100 of the current cell. Each sub measurement channel is transmitted in a time division manner. And in the terminal device 200, the receiving part 220 receives the sub measurement channel transmitted by time division from base station apparatus 100A, 100B which is a target cell.

  As a result, since a plurality of sub measurement channels are transmitted in a time-sharing manner, the interference received by the sub measurement channel on the main measurement channel (first main measurement channel) of the current cell can be limited. It is possible to suppress deterioration of the measurement accuracy of the cell.

(Embodiment 5)
In Embodiments 1 to 4, the case where the sub measurement channel is transmitted in the continuous mode has been described. That is, the case where the sub measurement channel is always transmitted from the base station apparatus of the target cell that is the candidate for the handover destination has been described. In the present embodiment, a case will be described in which the sub measurement channel is transmitted in the gap mode, that is, there is a period in which the sub measurement channel is not transmitted.

  Note that the gap period during which the sub measurement channel is not transmitted is set to a different time zone from the gap period during which the main measurement channel is not transmitted as described in the second embodiment. Hereinafter, in order to distinguish from the gap period in which the main measurement channel is not transmitted, the gap period in which the sub measurement channel is not transmitted is referred to as a sub-gap period.

  The configurations of the mobile communication system, the base station apparatus, and the terminal apparatus according to the present embodiment are the same as those in Embodiments 1 and 2, and will be described below with reference to the configuration of Embodiment 1.

  FIG. 14 is a diagram illustrating a main measurement channel (first main measurement channel) of the current cell and a sub measurement channel of the target cell.

  The base station apparatus 100A of the target cell transmits the sub measurement channel in the gap mode using the sub frequency band f'2 that is a part of the main frequency band f1 of the current cell. That is, base station apparatus 100A of the target cell provides a gap section (subgap period) in which the sub measurement channel is not transmitted. The subgap period during which the sub measurement channel is not transmitted may be set, for example, every predetermined period. Further, the base station apparatus 100A of the target cell may set the subgap period according to the transmission request for the sub measurement channel.

  The base station apparatus 100 of the current cell changes the frequency band for transmitting the main measurement channel according to the subgap period during which the sub measurement channel is not transmitted. Specifically, the base station apparatus 100 has a main measurement channel (first main measurement channel) in a frequency band other than the frequency band f′2 in which the sub measurement channel is transmitted in the main frequency band f1 during the subgap period. Send. On the other hand, the base station apparatus 100 transmits the main measurement channel (first main measurement channel) using the entire frequency band of the main frequency band f1 in the subgap period.

  As described above, in the present embodiment, a subgap period in which the sub measurement channel of the target cell is not transmitted is provided. Outside the subgap period, the main measurement channel (first main measurement channel) of the current cell uses a frequency band other than the frequency band f′2 used for transmission of the sub measurement channel in the main frequency band f1. Sent. That is, in the subgap period in which the sub measurement channel is transmitted, the main measurement channel (first main measurement channel) is not transmitted in the sub frequency band f′2 used for transmitting the sub measurement channel. Therefore, the sub measurement channel does not receive the interference of the main measurement channel (first main measurement channel), so that the measurement accuracy can be improved.

  In addition, during the period in which the sub measurement channel is transmitted, the main measurement channel (first main measurement channel) is transmitted only in the frequency band other than the sub frequency band f′2, and thus a part of the main frequency band. However, in the time domain, the main measurement channel (first main measurement channel) is continuously transmitted, so that no gap period occurs. For this reason, it is possible to suppress deterioration in measurement accuracy of the main measurement channel even during a period in which the sub measurement channel is transmitted.

  The terminal device, base station device, mobile communication system, and different frequency measurement method according to the present invention are useful as a terminal device or the like in a different frequency / different system.

100, 100A, 100B, 300, 300A Base station device 110, 210 Antenna 120 Own cell measurement channel generation unit 130 Sub measurement channel generation unit 140, 240, 320 Transmission unit 150, 220, 410 Reception unit 200, 400 Terminal device 230, 420 reception level measurement unit 310 mode determination unit 430 mode determination unit

Claims (12)

Transmitted from the first base station apparatus, which is the handover source base station apparatus, using the first frequency band assigned to the first base station apparatus, and between the first base station apparatus and the own apparatus. Transmitted from the first main measurement channel used to determine the communication status of the second base station apparatus and the second base station apparatus that is a candidate for the handover destination base station apparatus, and between the second base station apparatus and the own apparatus. Receiving means for receiving a sub-measurement channel used for determining the communication status;
Measuring means for measuring the reception level of the first main measurement channel and the sub measurement channel,
The sub measurement channel is transmitted using a sub frequency band that is a partial frequency band in the first frequency band.
Terminal device. Determination means for determining the presence or absence of a gap period during which the first main measurement channel is not transmitted based on the reception level of the sub measurement channel;
The measuring means includes
When there is the gap period, in the gap period, a second main measurement channel transmitted from the second base station apparatus using the second frequency band assigned to the second base station apparatus is received, Measuring the reception level of the second main measurement channel;
The terminal device according to claim 1. The sub frequency band and the second frequency band are associated with each other.
The terminal device according to claim 1. The sub measurement channel is transmitted in a time division manner from a plurality of candidates of the second base station device using the sub frequency band.
The terminal device according to claim 1. In the time zone in which the sub measurement channel is transmitted, the first main measurement channel is transmitted using a frequency band other than the sub frequency band in the first frequency band.
The terminal device according to claim 1. Using the first frequency band assigned to the local station, transmitting the first main measurement channel used for determining the communication status between the local station and the terminal device in communication;
A first sub frequency band used to determine a communication status between the other station and a terminal device in communication using a first sub frequency band that is a part of a second frequency band assigned to the other station. A transmission means for transmitting the measurement channel;
A base station apparatus comprising: The second sub measurement used for determining the communication status between the other station and the terminal device, transmitted from the other station using the second sub frequency band, which is a part of the first frequency band. Receiving means for receiving information on the reception level of the channel from the terminal device;
Determining means for determining whether to provide a gap period during which the first main measurement channel is not transmitted based on the reception level of the second sub measurement channel;
The transmission means includes
When the gap period is provided, the first main measurement channel is not transmitted in the gap period.
The base station apparatus according to claim 6. The first sub-frequency band and the first frequency band are associated with each other.
The base station apparatus according to claim 6. The transmission means includes
Transmitting the first sub measurement channel using the first sub-frequency band in a time-sharing manner with other stations;
The base station apparatus according to claim 6. The transmission means includes
A second sub measurement channel used for determining a communication status between the other station and the terminal device from the other station using a second sub frequency band that is a part of the first frequency band. In the time zone to be transmitted, the first main measurement channel is transmitted using a frequency band other than the second sub-frequency band in the first frequency band.
The base station apparatus according to claim 6. A plurality of base station devices according to claim 6;
A terminal device according to claim 1;
A mobile communication system comprising: The second base station to which the second frequency band is allocated from the first base station apparatus that is the handover source base station apparatus to which the first frequency band is allocated is assigned to the handover destination base station apparatus to which the terminal apparatus is connected for communication. A different frequency measurement method used for handover determination to switch to a station device,
The first base station device uses the first frequency band to transmit a first main measurement channel used for determining a communication status between the first base station device and the terminal device, and Transmitting a first sub measurement channel using a first sub frequency band, which is a partial frequency band of the second frequency band;
The second base station apparatus transmits a second main measurement channel using the second frequency band, and uses a second sub frequency band that is a partial frequency band of the first frequency band, Transmitting a second sub measurement channel used for determining a communication status between the second base station apparatus and the terminal apparatus;
The terminal apparatus is configured to transmit the first main measurement channel transmitted from the first base station apparatus currently in communication connection, the second sub measurement channel transmitted from the second base station apparatus, and And measuring reception levels of the first main measurement channel and the sub measurement channel,
Different frequency measurement method.

Images