JP5984507B2 - Base station apparatus and communication system - Google Patents

Description

  The present invention relates to a base station apparatus capable of wireless communication with a communication terminal apparatus by a plurality of communication methods and a communication system including the same.

  In the 3rd Generation Partnership Project (3GPP), which is a standardization body for mobile communication systems, Long Term Evolution (abbreviation): 3.9th generation (abbreviation: 3.9G) communication method. (LTE) system is defined. In addition, an LTE-advanced (LTE-Advanced) system that is an advanced version of the LTE system is also defined.

  The LTE system is an advanced version of the W-CDMA (Wideband Code division Multiple Access) system, which is one of the third generation (Third Generation; abbreviated name: 3G) communication systems (hereinafter sometimes referred to as “3G system”). It is. In the W-CDMA mobile communication system, circuit switched (abbreviation: CS) communication is provided. In the mobile communication system of the LTE or later communication system such as the LTE system and the LTE advanced system, a circuit is used. Switched communication is not provided.

  Therefore, for example, voice communication of a mobile communication terminal apparatus (hereinafter sometimes referred to as “communication terminal apparatus” or “communication terminal apparatus”) located in a mobile communication system of a communication system after LTE is changed to the W-CDMA system. However, when the communication terminal only supports the voice communication in the W-CDMA system, a process called CS Fallback (abbreviation: CSFB) is performed. With CSFB, communication in the communication system after LTE is switched to communication in the W-CDMA system, and circuit-switched communication becomes possible (see Non-Patent Documents 1 to 5).

  In a communication system corresponding to a plurality of communication systems, techniques for controlling switching of communication systems include techniques disclosed in Patent Documents 1 to 3, for example. In the technique disclosed in Patent Document 1, the power consumption of the wireless communication terminal is reduced by reducing the frequency of handoff of the wireless communication terminal corresponding to two different communication methods.

  In the technique disclosed in Patent Document 2, in a communication terminal that can be connected to a plurality of different wireless communication systems, only the first wireless communication system power supply is turned on among the plurality of wireless communication system power supplies when in a standby state. All other power sources for the wireless communication system are turned off, and notification of incoming calls is received via the first wireless communication system. As a result, power consumption during standby is reduced in the communication terminal.

  Patent Document 3 discloses a wireless terminal device and a base station that support a plurality of wireless systems, for example, both GSM (registered trademark) (Global System for Mobile) and W-CDMA systems. In the technique disclosed in Patent Document 3, when a wireless terminal device moves and belongs to a new neighboring cell of a wireless method that is not communicating, a wireless communication unit that supports a wireless method that is not communicating is provided. The power consumption of the wireless terminal device is suppressed by starting and acquiring information on the neighboring cells.

  The techniques disclosed in Patent Documents 1 to 3 are techniques for controlling switching of communication methods in a communication terminal corresponding to a plurality of communication methods. Patent Documents 1 to 3 do not disclose a technique for controlling switching of communication methods in a base station apparatus corresponding to a plurality of communication methods.

  A base station apparatus corresponding to a plurality of communication schemes, for example, a base station apparatus corresponding to both the 3G scheme and the LTE scheme, performs an independent peripheral cell search in each of the 3G scheme and the LTE scheme, and determines a cell radius in each scheme. (For example, refer to Patent Document 4).

  The handover of the communication terminal to the cell of the base station device is controlled by the base station control device (see, for example, Patent Document 5). The wireless network control device disclosed in Patent Document 5 relates to a mobile device that has entered the area of a prohibited cell that is prohibited from being used, and prohibits connection by the prohibited cell, and the mobile device within the prohibited cell area. The connection is made by the effective operation cell that covers the area including the current position. As a result, communication is maintained while avoiding the use of prohibited cells. The radio network controller corresponds to a base station controller. The mobile device corresponds to a communication terminal.

Japanese Patent No. 3916554 Japanese Patent No. 4190982 International Publication No. 2008/081548 Pamphlet JP 2010-161552 A JP 2009-118219 A

3GPP TS 23.060 V10.3.0 3GPP TS 23.401 V10.3.0 3GPP TS 23.221 V10.0.0 3GPP TS 24.008 V10.2.0 3GPP TS 23.272 V10.3.1

  As disclosed in the above-mentioned Patent Document 4, base station apparatuses that support a plurality of communication systems, for example, base station apparatuses that support both the 3G system and the LTE system, are independent peripheral cells in the 3G system and the LTE system, respectively. A search is performed to determine the cell radius for each method.

  When the base station apparatus is a base station apparatus that operates a femto cell (hereinafter sometimes referred to as a “femto cell base station”), depending on the macro cell environment, the femto cell radius may be 3G or LTE. It will be different. When CSFB is executed in this situation, a communication terminal communicating with the femtocell base station using the LTE method communicates with the macro cell using the 3G method, and there is a possibility that the connection with the femtocell base station is lost.

  For example, when the presence / absence of communication between a communication terminal and a femtocell base station is used for at-home confirmation, the position of the communication terminal is changed when the connection destination of the communication terminal is switched to the macro cell in accordance with the switching of the communication method of the communication terminal. Despite having not changed, there is a risk of being recognized as having changed from being at home to being absent.

  In this case, even if the technique disclosed in Patent Document 5 described above is applied, the communication terminal is handed over to a cell of a base station other than the prohibited cell. You cannot maintain communication with. Therefore, when the communication method of the communication terminal is switched to a different communication method, the communication terminal cannot maintain communication with the same base station, and the user continues a specific service from the same base station. There is a problem that you cannot receive.

  In addition, in a base station apparatus that supports a plurality of communication methods, such as the 3G method and the LTE method, the number of communication terminals that can be supported by each method, that is, the number of communication terminals that can simultaneously communicate with each method (hereinafter, “ If the number of users is different), the communication method cannot be switched as desired by all communication terminals. Specifically, the number of communication terminals that can simultaneously communicate with each method is the number of communication terminals that can simultaneously communicate with the communication means of each method.

  For example, in a base station apparatus that supports two communication methods, the number of users that can be handled by the first communication method is “2”, and the number of users that can be handled by the second communication method is “10”. think of. In this case, even if a communication terminal communicating with the second communication method attempts to switch to the first communication method to communicate, only two communication terminals can be switched to the first communication method.

  After the communication method of the two communication terminals is switched to the first communication method, if the third communication terminal desires to switch to the first communication method, the communication terminal The connection with the station apparatus is cut off, and communication with another base station apparatus corresponding to one communication method is made. Therefore, there is a possibility that the service received by the base station apparatus that originally communicated cannot be received.

  An object of the present invention is to provide a base station apparatus and a communication system that can prevent the connection with the communication terminal apparatus from being undesirably disconnected when the communication method of the communication terminal apparatus is switched.

A base station apparatus according to the present invention is a base station apparatus capable of wireless communication with a communication terminal apparatus using first and second communication systems different from each other, and communicates with the communication terminal apparatus using a first communication system. The first communication means, the second communication means for communicating with the communication terminal apparatus using a second communication method, and the first communication means communicating with the base station apparatus using the first communication method. Detection means for detecting that a switching request for switching the communication method from the first communication method to the second communication method is sent from the communication terminal device; and the first communication method by the first communication device. when the own base station apparatus and the communication terminal device is communicating in, when the switching request from the communication terminal device by said detecting means is detected to have been delivered, before Symbol second communication scheme the communication quality of the base station apparatus, pre In so that Do equals the communication quality of the base station apparatus in the first communication method, a transmission power determining means for determining a transmission power from the second communication unit to the communication terminal apparatus, the transmission power determining unit And control means for controlling the second communication means so as to obtain the transmission power determined by .

  The communication system of the present invention includes the base station apparatus of the present invention and a communication terminal apparatus capable of wireless communication with the base station apparatus of the present invention.

Further, the communication system of the present invention includes a base station apparatus capable of performing wireless communication between a communication terminal apparatus and the communication terminal apparatus using different first and second communication schemes, and a base for controlling the base station apparatus A base station apparatus communicates with the communication terminal apparatus by a first communication method, and communicates with the communication terminal apparatus by a second communication method. Second communication means, and control means for controlling the first communication means and the second communication means, wherein the base station host apparatus uses the first communication means to perform the first communication method. Detecting means for detecting that a switching request for switching the communication method from the first communication method to the second communication method is transmitted from the communication terminal device communicating with the base station device ; Said first means by communication means; When the base station apparatus and the communication terminal device is communicating with Shin method, wherein the switching request is detected to have been sent from the communication terminal apparatus by said detection means, said second communication method The transmission power from the second communication means to the communication terminal apparatus is determined such that the communication quality of the base station apparatus in the first communication method is equal to the communication quality of the base station apparatus in the first communication method, Instruction means for instructing the control means of the base station apparatus so as to control the second communication means so as to obtain transmission power, the control means of the base station apparatus comprising: based on an instruction from said instruction means, said as the communication quality of the base station apparatus in the second communication method is equal to the communication quality of the base station apparatus in the first communication method a second communication hand Wherein determining the transmission power for the communication terminal apparatus, so that the such a the determined transmission power, and controls the second communication means from.

According to the base station apparatus of the present invention, when the own base station apparatus and the communication terminal apparatus are communicating with each other by the first communication means in the first communication system, the communication system is changed from the communication terminal apparatus in communication. When the detection means detects that a switching request for switching from the first communication method to the second communication method has been issued, the communication quality of the own base station device in the second communication method is the same as that in the first communication method. The transmission power from the second communication means to the communication terminal apparatus is determined by the transmission power determination means so as to be equal to the communication quality of the base station apparatus. So that the such a transmission power determined by the transmission power determination unit, second communication means is controlled by the control means. Thereby, it is possible to prevent undesired disconnection between the own base station apparatus and the communication terminal apparatus in accordance with the switching of the communication method of the communication terminal apparatus. Therefore, it is possible to prevent a communication terminal device connected to and communicating with its own base station device from being undesirably connected to and communicating with another base station device.

  In addition, according to the communication system of the present invention, as described above, the communication system is configured to include the excellent base station apparatus and communication terminal apparatus of the present invention. It is possible to prevent undesired disconnection between the base station apparatus and the communication terminal apparatus during communication. Therefore, it is possible to prevent a communication terminal device connected to and communicating with a certain base station device from being undesirably connected to and communicating with another base station device.

According to the communication system of the present invention , when the base station apparatus and the communication terminal apparatus are communicating with each other by the first communication means using the first communication means , the communication method is changed from the communication terminal apparatus in communication. When the detection means of the base station host apparatus detects that a switching request for switching from the first communication system to the second communication system has been issued, the base station apparatus is based on an instruction from the instruction means of the base station host apparatus The transmission power from the second communication means to the communication terminal apparatus so that the communication quality of the own base station apparatus in the second communication scheme is equal to the communication quality of the own base station apparatus in the first communication scheme. There are determined, so that the such a the determined transmission power, the second communication means is controlled. Thereby, it is possible to prevent the connection between the base station apparatus and the communication terminal apparatus from being undesirably disconnected when the communication method of the communication terminal apparatus is switched. Therefore, it is possible to prevent a communication terminal apparatus connected to and communicating with a base station apparatus from undesirably being connected to and communicating with another base station apparatus.

It is a block diagram which shows the structure of the base station apparatus 1 which is one Embodiment of this invention. FIG. 2 is a block diagram illustrating configurations of an LTE PF unit 45 and a 3G PF unit 62 illustrated in FIG. 1. It is a figure for demonstrating the communication area of a communication terminal device and the communication area of a femtocell base station apparatus at the time of CSFB from LTE system to 3G system. It is a figure for demonstrating the communication area of a communication terminal device and the communication area of a femtocell base station apparatus at the time of CSFB from LTE system to 3G system. 2 is a block diagram illustrating a configuration of a communication system 110 including a base station device 1. FIG. It is a sequence diagram which shows the procedure of an incoming call. It is a sequence diagram which shows the procedure of attachment. It is a sequence diagram which shows the procedure of the update of the combined tracking area (TA) and local area (LA). It is a sequence diagram which shows the procedure of an outgoing call. It is a block diagram which shows the structure of the PF part 45 for LTE. 2 is a block diagram illustrating a configuration of a communication system 130 including a base station device 1. FIG. It is a figure for demonstrating the connection condition of the base station apparatus and UE in a communication system. It is a figure for demonstrating the connection condition of the base station apparatus and UE in a communication system.

  FIG. 1 is a block diagram showing a configuration of a base station apparatus 1 according to an embodiment of the present invention. Base station apparatus 1 according to the present embodiment is a base station apparatus capable of wireless communication with communication terminal apparatuses using different first and second communication methods. In the present embodiment, the first communication method is the LTE method, and the second communication method is the 3G method, specifically the W-CDMA method. The communication terminal device is, for example, a mobile communication terminal device configured to be movable. However, the communication terminal device is not necessarily configured to be movable and may be used fixedly. Further, the mobile communication terminal device may be fixedly used.

  As shown in FIG. 5 to be described later, the base station apparatus 1 constitutes a communication system 110 together with a communication terminal apparatus 112. The communication system 110 is specifically a wireless communication system. When the communication terminal device 112 is a mobile communication terminal device, the communication system 110 is a mobile communication system.

  The base station apparatus 1 includes a radio frequency (abbreviation: RF) unit 11, an LTE circuit unit 13, a first antenna 17, a second antenna 18, and a 3G circuit unit 81.

  The RF unit 11 includes a first transmission / reception unit 21 and a second transmission / reception unit 22. The LTE circuit unit 13 includes an Orthogonal Frequency Division Multiple Access (abbreviation: OFDMA) unit 35, an LTE channel coding unit 36, and a single wave frequency division multiple access (abbreviation). SC-FDMA) unit 37, LTE channel decoding unit 38, LTE radio parameter acquisition unit 39, radio link control (abbreviation: RLC) / media access control (abbreviation: MAC) unit 40 Packet Data Convergence Protocol (abbreviation: PDCP) / General Packet Radio Service Tunneling Protocol-User (GTP-U) section 41 for user plane, LTE Internet Protocol (Internet) Protocol; Abbreviation: P) unit 42, LTE internet protocol security (IP Security; abbreviated: IPsec) unit 43, LTE application (abbreviated: AP) unit 44, LTE platform (abbreviated: PF) unit 45, and network parameter acquisition Part 46 is provided.

  The 3G circuit unit 81 includes a spreading modulation unit 50, a 3G channel coding unit 51, a despreading demodulation unit 52, a 3G channel decoding unit 53, and a medium for high speed downlink packet access (abbreviation: HSDPA). Medium access control-HSDPA (abbreviation: MAC-hs) section 54, medium access control-EUL (abbreviation: MAC-e) section 55 for enhanced uplink (abbreviation: EUL), FP Terminating unit 56, 3G wireless parameter acquisition unit 57, 3G IP unit 58, point-to-point protocol over Ethernet (registered trademark) via Ethernet (registered trademark) unit 60, AP for 3G Part 61 and 3G PF part 62 are provided.

  The RF unit 11 constitutes a wireless transmission / reception unit 71. The wireless transmission / reception unit 71 includes a circuit and an RF component mounted on an FPGA or ASIC.

  Of the LTE circuit unit 13, the OFDMA unit 35, the LTE channel coding unit 36, the SC-FDMA unit 37, the LTE channel decoding unit 38, the LTE radio parameter acquisition unit 39, the RLC / MAC unit 40, and the PDCP / GTP- The U unit 41 constitutes an LTE baseband unit 72.

  Of the LTE circuit unit 13, the LTE AP unit 44, the LTE PF unit 45, and the network parameter acquisition unit 46 constitute an evolved base station (abbreviation: eNB) control unit 73. The eNB control unit 73 controls a part that functions as an eNB that is a base station in an LTE communication system, and performs call processing, call processing monitoring, line setting and management, maintenance monitoring, state management, and the like regarding the LTE function.

  Among the 3G circuit unit 81, the spread modulation unit 50, the 3G channel coding unit 51, the despreading demodulation unit 52, the 3G channel decoding unit 53, the MAC-hs unit 54, the MAC-e unit 55, the FP termination unit 56, and The 3G wireless parameter acquisition unit 57 constitutes a 3G baseband unit 74. In the present embodiment, the 3G baseband unit 74 functions as a W-CDMA baseband unit.

  Of the 3G circuit unit 81, the 3G AP unit 61 and the 3G PF unit 62 constitute an NB control unit 75. The NB control unit 75 controls a part that functions as a NodeB (hereinafter also referred to as “NB”) that is a base station in a 3G communication system, and performs call control, call processing monitoring, line setting and management for 3G functions, Perform maintenance monitoring and status management. The eNB control unit 73 and the NB control unit 75 function as control means, transmission power determination means, analysis means, quality information acquisition means, identification means, and detection means.

  The LTE IP unit 42 and LTE IPsec unit 43 of the LTE circuit unit 13, and the 3G IP unit 58 and PPPoE unit 60 of the 3G circuit unit 81 constitute a wired-side termination unit 76. The wired-side termination unit 76 terminates Ethernet (registered trademark) and IP signals. The wired terminal unit 76 corresponds to an IPsec function, an operation system (abbreviation: OPS), an AP, a PF, and a device reset function.

  The first transmission / reception unit 21 of the RF unit 11 is connected to the first antenna 17. The first transmitting / receiving unit 21 is connected to the LTE baseband unit 72 and the 3G baseband unit 74. More specifically, the first transmission / reception unit 21 includes an OFDMA unit 35, an SC-FDMA unit 37 and an LTE radio parameter acquisition unit 39 of the LTE circuit unit 13, a spread modulation unit 50 of the 3G circuit unit 81, and a despread demodulation. Are connected to the unit 52 and the wireless parameter acquisition unit 57 for 3G.

  The first transmission / reception unit 21 converts a baseband transmission signal to be transmitted via the first antenna 17 from the LTE baseband unit 72 or the 3G baseband unit 74 into a radio frequency signal. The first transmission / reception unit 21 transmits the radio frequency signal to the communication terminal device via the first antenna 17. The first transmission / reception unit 21 converts the reception radio frequency signal received via the first antenna 17 into a reception baseband signal. The first transmission / reception unit 21 provides the reception baseband signal to the LTE baseband unit 72 or the 3G baseband unit 74.

  The second transmission / reception unit 22 of the RF unit 11 is connected to the second antenna 18. The second transmitting / receiving unit 22 is connected to the LTE baseband unit 72 and the 3G baseband unit 74. More specifically, the second transmitting / receiving unit 22 includes the OFDMA unit 35, the SC-FDMA unit 37 and the LTE radio parameter acquisition unit 39 of the LTE circuit unit 13, the spread modulation unit 50 of the 3G circuit unit 81, and the despread demodulation. Are connected to the unit 52 and the wireless parameter acquisition unit 57 for 3G.

  The second transmission / reception unit 22 converts a baseband transmission signal to be transmitted via the second antenna 18 from the LTE baseband unit 72 or the 3G baseband unit 74 into a radio frequency signal. The second transmission / reception unit 22 transmits the radio frequency signal to the communication terminal device via the second antenna 18. The second transmitting / receiving unit 22 converts the received radio frequency signal received via the second antenna 18 into a received baseband signal. The second transmitting / receiving unit 22 provides the received baseband signal to the LTE baseband unit 72 or the 3G baseband unit 74.

  The OFDMA unit 35, the LTE channel coding unit 36, the SC-FDMA unit 37, the LTE channel decoding unit 38, and the LTE radio parameter acquisition unit 39 are realized by the built-in DSP of the LTE circuit unit 13 and the L1 engine (Engine). The The built-in DSP is a digital signal processor built in the LTE circuit unit 13. The DSP is equipped with a software program and can execute processing suitable for digital signal processing. The L1 engine is a coprocessor that processes a layer 1 function defined in the following references 1 to 3.

Reference 1: 3GPP TS 36.211 V10.1.0
Reference 2: 3GPP TS36.212 V10.1.0
Reference 3: 3GPP TS36.213 V10.1.0
The OFDMA unit 35 performs modulation processing for OFDMA. The OFDMA unit 35 mainly has a modulation function defined in References 1 and 3. The LTE channel coding unit 36 performs channel coding, specifically, error correction coding. The SC-FDMA unit 37 performs demodulation processing for SC-FDMA. The SC-FDMA unit 37 mainly has a demodulation function defined in References 1 and 3. The LTE channel decoding unit 38 decodes the reception channel.

  The LTE radio parameter acquisition unit 39 acquires from at least one of the first antenna 17 and the second antenna 18 and down-converts the amplitude intensity of the downlink data obtained by the first transmission / reception unit 21 and the second transmission / reception unit 22. Measure power intensity. Further, the LTE radio parameter acquisition unit 39 demodulates and decodes data, and analyzes the contents of broadcast information and the like, thereby acquiring environment information of both 3G and LTE neighboring cells such as electric field strength from adjacent base stations. .

  The RLC / MAC unit 40 performs radio link control (RLC) and media access control (MAC). The PDCP / GTP-U unit 41 performs PDCP processing and GTP-U processing.

  The LTE IP unit 42 performs IP processing on the LTE signal. The IP processing is processing that analyzes information such as an IP header, removes the header based on the analysis result, and generates data. The LTE IP unit 42 provides the LTE IPsec unit 43 with data generated by performing IP processing on the LTE signal.

  The LTE IPsec unit 43 has a security function for encrypting data provided from the LTE IP unit 42. The LTE IPsec unit 43 provides the encrypted data to the 3G IP unit 58 and the PPPoE unit 60 of the 3G circuit unit 81.

  The LTE AP unit 44 has an application function for controlling the LTE-side function of the base station device 1. The LTE PF unit 45 has a platform function for controlling the LTE-side function of the base station apparatus 1.

  The network parameter acquisition unit 46 is higher in level than the interface between the base station apparatus 1 and a base station upper apparatus such as a mobility management entity (abbreviation: MME) and a serving gateway (abbreviation: SGW). It has a function to acquire network information.

  The MAC-hs unit 54 of the 3G circuit unit 81 has a layer 2 MAC scheduling function necessary when performing HSDPA. The MAC-e unit 55 has a layer-2 MAC scheduling function necessary for performing HSUPA (EUL).

  The FP termination unit 56 of the 3G circuit unit 81 performs FP termination processing. The FP termination unit 56 mainly has a function of framing the FP format defined in the following references 4 and 5 as FP termination processing, specifically, a function of creating an FP format and a function of canceling the FP format. Have. The 3G circuit unit 81 is configured by a 3G-LSI that is a 3G large scale integration circuit (abbreviation: LSI) realized by, for example, an FPGA or an ASIC.

Reference 4: 3GPP TS25.427 V10.0.1
Reference 5: 3GPP TS25.435 V10.1.0
The 3G radio parameter acquisition unit 57 measures the amplitude intensity or power intensity of downlink data acquired from the antenna, demodulates and decodes the data, and analyzes the content of the broadcast information, thereby analyzing the electric field intensity from the adjacent base station. To obtain environmental information of 3G-type neighboring cells.

  The 3G IP unit 58 has a function of processing layer 3 IP frame data (hereinafter also referred to as “framing”). The PPPoE unit 60 performs processing corresponding to the PPPoE protocol on the data given from the LTE IPsec unit 43. The PPPoE unit 60 is connected to the MME and the SGW via the S1 interface that is an interface on the LTE side. The PPPoE unit 60 is connected to a base station controller (Radio Network Controller; abbreviated as RNC) via an Iub interface or an Iuh interface that is an interface on the 3G side.

  The 3G AP section 61 has an application function for controlling the 3G function of the base station. The 3G PF unit 62 has a platform function for controlling the 3G function of the base station.

  The diffusion modulation unit 50 performs diffusion modulation processing. The 3G channel coding unit 51 performs channel coding, specifically, error correction coding. The despread demodulator 52 performs a despread demodulation process that demodulates by despread. The 3G channel decoding unit 53 decodes the reception channel.

  The spread modulation unit 50 and the despread demodulation unit 52 mainly have functions defined in the following references 6 to 8. The 3G channel coding unit 51 and the 3G channel decoding unit 53 mainly have functions defined in Reference Document 9 below.

Reference 6: 3GPP TS25.211
Reference 7: 3GPP TS 25.213
Reference 8: 3GPP TS25.214
Reference 9: 3GPP TS 25.212
The base station apparatus 1 shown in FIG. 1 is a shared base station apparatus (hereinafter sometimes referred to as “dual base station apparatus”) that supports both the 3G scheme, specifically the W-CDMA scheme and the LTE scheme. .

  In the base station apparatus 1, a part having a function corresponding to the 3G system (hereinafter sometimes referred to as “3G side functional part”) is the second antenna 18, the second transmitting / receiving unit 22 of the RF unit 11, and the 3G circuit unit 81. W-CDMA spread modulation unit 50, 3G channel coding unit 51, despread demodulation unit 52, 3G channel decoding unit 53, MAC-hs unit 54, MAC-e unit 55, FP termination unit 56, for 3G The wireless parameter acquisition unit 57, the 3G IP unit 58, the PPPoE unit 60, the 3G AP unit 61, and the 3G PF unit 62 are configured. The 3G side functional part corresponds to a second communication means.

  In the base station apparatus 1, a part having a function corresponding to the LTE system (hereinafter sometimes referred to as “LTE side functional part”) is the first antenna 17, the first transmission / reception part 21 of the RF part 11, and the LTE circuit part 13. OFDMA unit 35, LTE channel coding unit 36, SC-FDMA unit 37, LTE channel decoding unit 38, LTE radio parameter acquisition unit 39, RLC / MAC unit 40, PDCP / GTP-U unit 41, LTE IP Unit 42, LTE IPsec unit 43, LTE AP unit 44, LTE PF unit 45, and network parameter acquisition unit 46. The LTE-side functional part corresponds to the first communication means.

  In FIG. 1, the lines connecting the functional parts mainly indicate data signal lines. The LTE AP unit 44, the LTE PF unit 45, the 3G AP unit 61, and the 3G PF unit 62 should be connected to each function to be controlled, but signal lines are not shown. However, the signal line connecting the 3G PF unit 62 and the LTE PF unit 45 is a signal line for realizing a function related to the cooperative operation between the 3G function such as CS fallback and the LTE function, and thus omitted. Not done.

  The LTE circuit unit 13 in the base station apparatus 1 according to the present embodiment includes an OFDMA, SC-FDMA, a built-in DSP in the LTE circuit unit 13 suitable for arithmetic processing, and an L1 engine that is also mounted in the LTE circuit unit 13. This can be realized by implementing channel coding, channel decoding, a radio parameter acquisition function, and the like. Specifically, the L1 engine includes Fast Fourier Transform (abbreviation: FFT), Discrete Fourier Transform (abbreviation: DFT), Log Likelihood Ratio (abbreviation: LLR), cyclic It is a layer 1 function coprocessor such as a Cyclic Redundancy Checksum (abbreviation: CRC), a Turbo / Viterbi decoder. The wireless parameter acquisition function is performed by the LTE circuit unit 13 while both the 3G and LTE functions are out of service.

  FIG. 2 is a block diagram showing configurations of the LTE PF unit 45 and the 3G PF unit 62 shown in FIG. The LTE PF unit 45 and the 3G PF unit 62 perform a process of expanding or narrowing a communication area that is a range in which the base station apparatus 1 can communicate. The LTE PF unit 45 includes a CSFB detection unit 101 and an LTE transmission power / CQI information acquisition unit 102. The 3G PF unit 62 includes a transmission power determination unit 103, a 3G CQI information acquisition unit 104, and a 3G macro cell information acquisition unit 105.

  The CSFB detection unit 101 corresponds to an identification unit and a detection unit. The LTE transmission power / CQI information acquisition unit 102 corresponds to a quality information acquisition unit. The transmission power determination unit 103 corresponds to transmission power determination means and analysis means.

  The CSFB detection unit 101 detects CSFB. The CSFB detection unit 101 detects CSFB by detecting a message (hereinafter sometimes referred to as “CSFB message”) requesting the start of CSFB sent from the communication terminal device. The CSFB message corresponds to a switching request. When CSFB is detected, CSFB detection unit 103 provides information on the detected CSFB to LTE transmission power / CQI information acquisition unit 104.

  For example, the CSFB detection unit 101 receives a signal of any communication method on the basis of a result of cyclic redundancy check (abbreviation: CRC) obtained by decoding a signal transmitted from the communication terminal device. And detecting that the CSFB has been performed based on the identification result. Thus, the CSFB detection unit 101 can be realized with a simple configuration. Detecting that CSFB has been performed corresponds to detecting that a switching request has been sent from the communication terminal device. CRC is performed in the L1 engine of the LTE circuit unit 13 shown in FIG.

  LTE transmission power / CQI information acquisition section 101 acquires LTE transmission power information indicating transmission power from base station apparatus 1 to communication terminal apparatus in LTE communication. The LTE transmission power / CQI information acquisition unit 101 also provides channel quality indicator (abbreviation: CQI) information (hereinafter referred to as “LTE”) indicating the transmission quality of data from the base station apparatus 1 to the communication terminal apparatus in LTE communication. CQI information ”in some cases). When the LTE transmission power / CQI information acquisition unit 101 receives the CSFB information from the CSFB detection unit 103, the LTE transmission power / CQI information acquisition unit 101 acquires the LTE transmission power information and the LTE CQI information, and transmits the LTE transmission power information to the transmission power determination unit 103 of the 3G PF unit 62. Notice.

  The 3G macro cell information acquisition unit 105 of the 3G PF unit 62 acquires transmission power information (hereinafter sometimes referred to as “macro cell transmission power information”) of neighboring macro cells, and notifies the transmission power determination unit 103 of the transmission power information.

  Transmission power determining section 103 is based on LTE transmission power information and LTE CQI information provided from LTE transmission power / CQI information acquisition section 102, and macrocell transmission power information provided from 3G macrocell information acquisition section 105. Then, the downlink transmission power in 3G communication of the base station apparatus 1 after CSFB (hereinafter sometimes referred to as “3G downlink transmission power”) is determined.

  The transmission power determination unit 103 determines the 3G downlink transmission power so that the communication quality in the 3G scheme becomes equal to the communication quality in the LTE scheme. The transmission power determination unit 103 controls the 3G-side functional part, for example, the second transmission / reception unit 22 of the wireless transmission / reception unit 71 shown in FIG.

  The reason why the transmission power determination unit 103 acquires LTE CQI information from the LTE transmission power / CQI information acquisition unit 102 is that the communication terminal apparatus receives data from the base station apparatus 1 by LTE communication, This is because the communication terminal apparatus matches the reception level when data is received from the base station apparatus 1 by 3G communication with the same level.

  That is, the transmission power determination unit 103 receives the reception level when the communication terminal apparatus receives data from the base station apparatus 1 through LTE communication and the reception level when the communication terminal apparatus receives data from the base station apparatus 1 through 3G communication. To match the level to the same level, the transmission power is determined based on the LTE CQI information given from the LTE transmission power / CQI information acquisition unit 102 and the reception level obtained from the LTE CQI information.

  In other words, the communication terminal apparatus determines the transmission power based on the LTE CQI information given from the LTE transmission power / CQI information acquisition unit 102 and the reception level obtained from the LTE CQI information. The reception level when data is received from the base station apparatus 1 through LTE communication and the reception level when the communication terminal apparatus receives data from the base station apparatus 1 through 3G communication can be matched to the same level. Thereby, before and after CSFB, the communication quality of the base station apparatus 1 which is a femtocell base station corresponding to both the 3G system and the LTE system and the communication terminal apparatus can be maintained.

  The CQI information acquisition unit 104 for 3G uses CQI information from the base station apparatus 1 to the communication terminal apparatus in 3G communication (hereinafter referred to as “3G CQI information”) after CSFB, that is, after switching from LTE communication to 3G communication. Get). When the communication terminal apparatus receives data through 3G communication, the 3G CQI information acquisition unit 104 acquires 3G CQI information, which is CQI information indicating the transmission quality, from the communication terminal apparatus. The 3G CQI information acquisition unit 104 notifies the transmission power determination unit 103 of the acquired 3G CQI information.

  In this way, by transmitting the 3G CQI information from the 3G CQI information acquisition unit 104 to the transmission power determination unit 103, the transmission power determination unit 103 causes the reception level in LTE communication and the reception level in 3G communication to increase. To match. The CQI and the reception level can be associated with each other by holding the correspondence table as a table or the like in the transmission power determination unit 103 in advance.

  As described above, the transmission power determination unit 103 determines the 3G downlink transmission power based on the transmission power value represented by the LTE transmission power information and the magnitude of the reception level obtained from the LTE CQI information.

  When 3G CQI information is not obtained and when 3G communication is performed for the first time, transmission power determining section 103 sets 3G downlink transmission power to the same value as the transmission power value represented by LTE transmission power information. After that, when CQI information in 3G communication is obtained from the communication terminal device via the 3G CQI information acquisition unit 104, the transmission power determination unit 103 receives the CQI in 3G communication in the LTE communication. Control is performed to increase or decrease the transmission power so that a reception level equal to the level can be obtained. The reception level may be, for example, a signal to interference plus noise power ratio (abbreviation: SINR).

  With such a configuration, it is possible to prevent undesired disconnection between the own base station device 1 and the communication terminal device in accordance with the switching of the communication method of the communication terminal device. As a result, it is possible to prevent a communication terminal apparatus that has been connected to and communicated with its own base station apparatus 1 from being undesirably connected to and communicated with another base station apparatus.

  Therefore, for example, when the presence / absence of communication between the communication terminal apparatus and the base station apparatus 1 is used for at-home confirmation, the connection destination of the communication terminal apparatus changes to another base station apparatus as the communication method of the communication terminal apparatus is switched. It is possible to prevent switching from being at home to being absent even though the position of the communication terminal device has not changed.

  Specifically, in the base station apparatus 1 according to the present embodiment, for example, when CSFB is detected when communicating with a communication terminal apparatus using the LTE scheme, the communication quality in the 3G scheme is The 3G downlink transmission power is determined so as to be equal to the communication quality, and the transmission power is controlled to be such a transmission power. This prevents a communication terminal apparatus that has been connected to the base station apparatus 1 that is a femtocell base station that supports both the 3G system and the LTE system from communicating with other base station apparatuses through the CSFB. be able to.

  Further, in the present embodiment, transmission power determination section 103 transmits transmission power based on LTE CQI information given from LTE transmission power / CQI information acquisition section 102 and the reception level obtained from the LTE CQI information. To decide. Thereby, the reception level when the communication terminal apparatus receives data from the base station apparatus 1 by LTE communication and the reception level when the communication terminal apparatus receives data from the base station apparatus 1 by 3G communication are set to the same level. Can be matched. Therefore, communication quality between the base station apparatus 1 that is a femtocell base station compatible with both the 3G scheme and the LTE scheme and the communication terminal apparatus can be maintained before and after the CSFB.

  3 and 4 are diagrams for explaining the communication area of the communication terminal device and the communication area of the femtocell base station device when CSFB is changed from the LTE method to the 3G method. FIG. 3 shows a state before the CSFB detection unit 101 shown in FIG. 2 detects CSFB, and FIG. 4 shows a state after the CSFB detection unit 101 detects CSFB.

  The base station apparatus 1 is a 3G / LTE shared femtocell base station apparatus (hereinafter sometimes referred to as a “femtocell base station”) shared by the 3G scheme and the LTE scheme, and includes a 3G femtocell area 113 and an LTE femtocell area. Assume that 114 is provided. Further, in the state before CSFB detection shown in FIG. 3, it is assumed that the communication terminal apparatus is located within LTE femtocell area 114 and 3G macrocell area 113 and outside 3G femtocell area 113.

  As shown in FIG. 3, when the communication terminal device 112 is located in the LTE femtocell area 114 and the 3G macrocell area 115 and outside the 3G femtocell area 113, the above-mentioned 3G PF unit 62 Consider a case where the communication method is switched from the LTE method to the 3G method without controlling the 3G downlink transmission power. In this case, the communication terminal device 112 does not communicate with the femtocell base station 1 but communicates with the macro cell. That is, when the communication terminal device 112 switches the communication method from the LTE method to the 3G method, communication between the communication terminal device and the femtocell base station 1 is disconnected.

  In contrast, in the present embodiment, when the CSFB detection unit 101 recognizes the CSFB message, the base station apparatus 1 that is a femtocell base station determines that CSFB has been detected, and the 3G cell radius is the LTE cell radius. The transmission power is controlled to be the same as.

  Specifically, when the communication terminal apparatus 112 is located in the LTE femtocell area 114 and the 3G macrocell area 115 and outside the 3G femtocell area 113, the base station apparatus 1 changes the communication method to LTE. When recognizing that the system has been switched to the 3G system, control is performed to increase the transmission power so that the 3G femtocell area 113 is expanded. As a result, the 3G femtocell area 113 is expanded as shown in FIG. 4, and the communication terminal device 112 that has been located outside the 3G femtocell area 113 is now located within the 3G femtocell area 113A. Therefore, the communication terminal apparatus 112 can continue communication with the femtocell base station 1.

  From the above, in this embodiment, a user who has been connected to a femtocell base station apparatus compatible with both 3G and LTE communication systems communicates with other base station apparatuses using CSFB. Can be prevented. In addition, before and after CSFB, it is possible to maintain the communication quality between the femtocell base station apparatus and the user corresponding to both 3G and LTE communication systems.

  When the user wants to communicate with the macro cell after CSFB, the transmission power base station apparatus 1 shown in FIG. 2 controls the transmission power so that the 3G cell radius is quickly reduced by the transmission power determination unit 103. The communication terminal apparatus is controlled to be handed over to the macro cell.

  FIG. 5 is a block diagram illustrating a configuration of a communication system 110 including the base station device 1. The communication system 110 includes a base station apparatus 1 according to the present embodiment, a base station host apparatus 117, and a communication terminal apparatus (hereinafter also referred to as “UE”) 112. The communication system 110 may include another base station device 116. FIG. 5 illustrates a case where the communication system 110 includes another base station device 116. In the following description, the base station apparatus may be referred to as “eNodeB”.

  As described above, when recognizing CSFB, base station apparatus 1 of the present embodiment controls transmission power so as to increase the communication area in the communication method after CSFB. As a result, it is possible to prevent the connection between the base station apparatus 1 and the UE 112 that are in communication from being undesirably disconnected when the communication method of the UE 112 is switched. Therefore, it is possible to prevent UE 112 that has been connected and communicating with base station apparatus 1 from being undesirably connected to and communicating with another base station apparatus 116 using CSFB.

  In this Embodiment, the base station apparatus 1 is comprised so that transmission power may be controlled based on the judgment of an own apparatus. In another embodiment of the present invention, the base station apparatus 1 is configured to control transmission power based on an instruction from the base station host apparatus 117 on the core network side such as an MME. Also good.

  In this case, the base station host apparatus 117 includes detection means and instruction means. When the detection means recognizes CSFB by the communication terminal apparatus, the base station apparatus 117 increases the transmission power so as to widen the communication area of the base station apparatus 1 in the communication system after CSFB. The base station apparatus 1 is instructed by the instructing means so as to increase. The base station apparatus 1 controls the transmission power by the transmission power determination unit 103 shown in FIG. 2 described above based on an instruction from the base station host apparatus 117. Thus, even when the control in the base station apparatus 1 is performed based on the instruction of the base station host apparatus 117, the same effect as in the present embodiment can be obtained.

  Hereinafter, transmission power control in the base station apparatus 1 of the present embodiment will be described more specifically.

  FIG. 6 is a sequence diagram showing an incoming call procedure. In step S11, an initial address message (abbreviation: IAM) is notified to a G-MSC (Gateway Mobile-services Switching Center).

  When the IAM is notified in step S11, the G-MSC, in step S12, sends a home subscriber server (abbreviation: HSS) and a mobile switching center / local network subscriber management register (Mobile-services Switching Center). / Visitor Location Register (abbreviation: MSC / VLR) and SRI procedure (Send Routing Information procedure). The SRI procedure is a procedure related to a search for inquiring about the location of the communication terminal device. The SRI procedure is defined in 3GPP TS 23.018.

  In step S13, the G-MSC transmits the IAM to the MSC / VLR via the HSS. Sending an IAM is equivalent to calling in the 3G system. In step S14, the MSC / VLR that has received the IAM transmitted from the G-MSC sends it to the MME via the radio network controller / base station controller (abbreviation: RNC / BSC). , Send a paging request message.

  The MME that has received the paging request message transmitted from the MSC / VLR transmits the paging message to the eNodeB in step S15. The paging message transmitted to the eNodeB in step S15 includes a core network domain indicator.

  In Step S16, the eNodeB that has received the paging message transmitted from the MME transmits the paging message to the communication terminal device (User Equipment; abbreviated as UE). The paging message transmitted to the UE in step S16 includes a core network domain indicator.

  In step S17, the UE that has received the paging message transmitted from the eNodeB transmits an extended service request message to the eNodeB and the MME. The extended service request transmitted to the eNodeB and the MME in step S17 includes a CS fallback indicator.

  The extended service request includes an indicator that indicates that the communication terminal device is in the idle mode. In order to avoid the possibility that the calling side is in a silent state for a long time, an indicator indicating that the communication terminal apparatus is in the idle mode is used. It is assumed that the calling party waits for a long time.

  In step S18, the MME that has received the extended service request message transmitted from the communication terminal apparatus (UE) transmits an extended service request (Service Request) message to the MSC / VLR via the RNC / BSC. Receiving this extended service request stops the re-transmission of the paging message via the MSC SGs interface.

  In addition, the MME that has received the extended service request message transmitted from the UE transmits an initial UE context setup message to the eNodeB in step S19. The initial UE context setup message includes a CS fallback indicator.

  FIG. 7 is a sequence diagram showing an attachment procedure. In step S21, the UE transmits an attach request message to the MME. The attach request message includes a combined EPS / IMSI (Evolved Packet System / International Mobile Subscriber Identity) attach message and a CSFB communication terminal device capability (UE Capability).

  In step S22, the UE, MME, MSC / VLR, and HSS perform a first attach procedure (Attach Procedure (1)). Specifically, as the first attach procedure, the identification request and response between the new MME and the previous MME when the connected MME is changed, or the UE is not recognized by the new MME Authentication request and response between MME and UE, authentication and security between UE, MME and HSS, encryption request and response, session erase request and response, location update, and session creation request and response Etc. are performed. The first attach procedure corresponds to steps 3 to 16 of the attach procedure defined in 3GPP TS 23.401.

  In step S23, the MME acquires a VLR number. In step S24, the MME transmits a location update request message to the MSC / VLR.

  In step S25, the MSC / VLR generates an SGs association. In step S26, the MSC / VLR and HSS perform location update in the CS domain.

  In step S27, the MSC / VLR transmits a location update accept message to the MME.

  In step S28, the UE, MME, MSC / VLR, and HSS perform a second attach procedure (Attach Procedure (2)). Specifically, as the second attach procedure, an initial setting request, an attach accept message transmission, an RRC connection establishment, a bearer modification request and a response, and the like are performed. The second attach procedure corresponds to steps 17 to 26 of the attach procedure defined in 3GPP TS23.401.

  FIG. 8 is a sequence diagram showing a procedure for updating the combined tracking area (TA) and local area (LA). FIG. 8 shows a sequence when the LTE side, that is, the TA side is updated.

  In step S31, the UE determines to execute a tracking area update (abbreviation: TAU) for updating the tracking area. In step S32, the UE transmits a TAU request message to a newly connected MME (new MME). In the following description, a newly connected MME may be referred to as a “new MME”.

  In step S33, the UE, the new MME, the previously connected MME (old MME), the MSC / VLR, and the HSS perform a TAU procedure. The TAU procedure is specified in 3GPP TS 23.401. In the following description, a previously connected MME may be referred to as a “previous MME”.

  In step S34, the new MME transmits a location update request message to the MSC / VLR via the previous MME.

  In step S35, the MSC / VLR and the HSS perform location update in the CS domain.

  In step S36, the MSC / VLR transmits a location update accept message to the new MME via the previous MME.

  The new MME that has received the location update accept message transmitted from the MSC / VLR transmits a TAU accept message to the UE in step S37.

  In step S38, the UE that has received the TAU accept message transmitted from the new MME transmits a TAU Complete message to the new MME.

  FIG. 9 is a sequence diagram showing a procedure for making a call. In step S41, the UE / MS (Mobile Station) transmits an Extended Service Request message to the MME via the eNodeB.

  In step S42, the MME that has received the extended service request message transmitted from the UE / MS transmits an S1-AP (S1-Application Protocol) request message (Request message) including a CSFB indicator to the eNodeB.

  In step S43, the eNodeB that has received the S1-AP request message transmits an S1-AP response message to the MME.

  In step S44, the UE / MS, the eNodeB, and the base station subsystem / radio network subsystem (abbreviation: BSS / RNS) perform an arbitrary measurement report (Optional Measurement Report Solicitation).

  In step S45, the UE / MS, eNodeB, BSS / RNS, MME, MSC, and packet access control node (Serving GPRS Support Node; abbreviated as SGSN) perform handover (hereinafter referred to as a PS (Packet Switch) domain from LTE to 3G. (Sometimes referred to as “PS HO”). The PS HO process in step S45 corresponds to a PS HO preparation stage and an execution start stage. The PS HO process in step S45 is defined in 3GPP TS 23.401.

  In step S46, the UE / MS transmits a Suspend message to the SGSN.

  In step S47, the SGSN that has received the Suspend message receives the serving gateway (Serving GW) and the packet data network gateway / gateway general packet ratio service support node (abbreviation: P-GW). / GGSN) transmits an update bearer (Update Bearer (s)).

  In step S48, the UE / MS, eNodeB, BSS / RNS, MME and MSC perform a Location Area Update or a Combined Routing Area / Location Area (abbreviation: RA / LA) update ( Update).

  In step S49, the UE / MS transmits a Connection Management (abbreviation: CM) service request message to the BSS / RNS via the eNodeB.

  In step S50, the BSS / RNS that has received the CM service request message from the UE / MS sends an A / lu-cs message (A / lu-cs) including a CM service request message to the MSC via the MME. cs message).

  If the MSC has changed, the process of the next step S51 is performed. The process of step S51 includes each process of step S52 and step S53.

  In step S52, the MSC transmits a CM Service Reject message to the BSS / RNS via the MME, and also sends a CM Service Reject (CM) to the UE / MS via the BSS / RNS and the eNodeB. Service Reject message.

  In step S53, the UE / MS, eNodeB, BSS / RNS, MME, and MSC perform a location area update or a combined RA / LA update.

  In step S54, the UE / MS, eNodeB, BSS / RNS, MME and MSC perform a CS call establishment procedure.

  In step S55, the UE / MS, eNodeB, BSS / RNS, MME, MSC, SGSN and serving gateway perform PS HO. The PS HO process in step S55 corresponds to a PS HO execution continuation stage. The PS HO process in step S55 is defined in 3GPP TS 23.401.

  The extended service request is an CS fallback indicator (CS Fallback Indicator) that the communication terminal (UE) sends to the MME via the base station apparatus (eNB) in the sequences of FIGS. 6 and 9. The CS fallback indicator is an indication to the MME to perform CS fallback.

  The communication terminal transmits a CS fallback indicator to the MME only when it is attached to the CS domain by the combined EPS / IMSI attach message and cannot make a call via the IMS voice (IMS voice) session. For example, if the communication terminal is not a registered IMS or if the IMS voice service is not supported by a home public land mobile network (abbreviation: home PLMN) by an IP-CAN service, the communication terminal Sends a CS fallback indicator to the MME.

  The sequence shown in FIGS. 6 and 9 is defined by 3GPP TS 23.272, 23.018, 23.401, and the like. According to this sequence, an extended service request message is transmitted to the MME via the base station apparatus (eNodeB). Accordingly, the base station apparatus knows that the communication terminal has transmitted the extended service request to the MME by performing processing for analyzing the extended service request message in the base station apparatus. Can do.

  Specifically, the base station apparatus 1 confirms that the communication terminal (UE) has transmitted an extended service request to the MME in the CSFB detection unit 101 of the LTE PF unit 45 shown in FIG. I can know. Thereby, the base station apparatus 1 can determine whether CSFB is going to be performed.

  In the attach sequence shown in FIG. 7 and the combined TA / LA update (Update) procedure shown in FIG. 8, there is no extended service request. In this case, the base station apparatus 1 waits for the outgoing or incoming call sequence to proceed, and then identifies the CS fallback (CS Fallback) based on the extended service request issued there. Alternatively, it may be identified using information of an attach sequence or a combined TA / LA update procedure.

  “Use attach sequence information” means, for example, use of attach type information included in the attach request in step S21 of FIG. The Attach Type information is information that can instruct the MME whether the communication terminal is dedicated to Short Message Service (abbreviation: SMS) or can use CS fallback.

  As described above, in this embodiment, the base station apparatus 1 includes the CSFB detection unit 101 and the LTE transmission power / CQI information acquisition unit 102 in the LTE PF unit 45, as shown in FIG. The 3G PF unit 62 is configured to include a transmission power determination unit 103, a 3G CQI information acquisition unit 104, and a 3G macro cell information acquisition unit 105. The base station apparatus 1 is not limited to this. The LTE AP unit 44 shown in FIG. 1 includes the CSFB detection unit 101 and the LTE transmission power / CQI information acquisition unit 102. The 3G AP unit 61 includes: The transmission power determination unit 103, the 3G CQI information acquisition unit 104, and the 3G macro cell information acquisition unit 105 may be provided.

  The base station apparatus 1 of this Embodiment comprises the communication system 130 with the communication terminal devices 131-132, as shown in FIG. 11 mentioned later. The communication system 130 is specifically a wireless communication system. When the communication terminal devices 131 to 132 are mobile communication terminal devices, the communication system 130 is a mobile communication system.

  FIG. 10 is a block diagram showing a configuration of the LTE PF unit 45. In the present embodiment, LTE PF unit 45 includes own base station communication maintenance control unit 126. The own base station communication maintenance control unit 126 corresponds to a determination unit. The own base station communication maintenance control unit 126 includes a special service using terminal identification unit 124 and a connection destination determination unit 125.

  The special service using terminal identifying unit 124 provides a service that is desirably communicated with the same base station apparatus, that is, the own base station apparatus 1, even if the communication terminal currently connected by the LTE system is switched over. Determine whether it is in use. Even if the communication method is switched, a service that is preferably communicated with the same base station apparatus is a service specific to the own base station apparatus 1, and this service may be referred to as a “special service” in the following description. is there. The special service using terminal identifying unit 124 provides the connection destination determining unit 125 with a determination result as to whether or not a communication terminal that is in communication connection is using the special service.

  When the number of communication terminals that can simultaneously communicate with the LTE-side functional part exceeds the number of communication terminals that can simultaneously communicate with the 3G-side functional part, the connection destination determination unit 125 is configured to communicate with a communication terminal that satisfies a predetermined maintenance condition. It is determined that communication during communication is maintained, and it is determined that communication during communication with a communication terminal that does not satisfy the maintenance condition is not maintained. The use of the special service by the communication terminal described above corresponds to the maintenance condition.

  Specifically, when the connection destination determining unit 125 determines that the communication terminal is using the special service based on the determination result given from the special service using terminal identifying unit 124, the communication method is changed from the LTE method. Even if it switches to 3G system, it determines that the communication in communication with the own base station apparatus 1 and a communication terminal is maintained, and controls the 3G side functional part in that way. When the connection destination determining unit 125 determines that the communication terminal is not using the special service based on the determination result given from the special service using terminal identifying unit 124, the communication method is switched from the LTE method to the 3G method. Control such as determining that communication during communication between the base station apparatus 1 and the communication terminal is not maintained, reducing the power of the transmission signal to the communication terminal, and handing over the communication terminal to another adjacent base station. I do.

  The 3G PF section 62 in the present embodiment is configured in the same manner as the LTE PF section 45 shown in FIG. That is, the 3G PF unit 62 includes a special service using terminal identification unit 124 and a connection destination determination unit 125. The special service using terminal identifying unit 124 of the 3G PF unit 62 provides a special service that it is desirable for the communication terminal currently connected to the 3G communication to continue to communicate with the base station apparatus 1 even if the communication method is switched. It is determined whether or not it is being used, and the determination result is given to the connection destination determination unit 125.

  If the connection destination determination unit 125 of the 3G PF unit 62 determines that the communication terminal is using the special service based on the determination result given from the special service use terminal identification unit 124, the communication method is the 3G method. Control is performed so as to continue communication with the base station apparatus 1 even when switching from LTE to LTE.

  Hereinafter, the communication system switching control in the base station apparatus 1 according to the present embodiment will be described more specifically. FIG. 11 is a block diagram illustrating a configuration of a communication system 130 including the base station device 1. The communication system 130 includes the base station device 1 according to the present embodiment, three UEs 131, 132, and 133, a base station host device 134, and another base station device 135. In the following description, the base station apparatus may be referred to as “eNodeB”.

  12 and 13 are diagrams for explaining a connection state between the base station apparatus and the UE in the communication system. FIG. 12 shows the case of base station apparatus 1 according to the present embodiment provided with own base station communication maintenance control section 126, and FIG. 13 shows the case of base station apparatus 140 not provided with own base station communication maintenance control section 126. Show.

  As shown in FIG. 12, base station apparatus 1 in the present embodiment is a base station apparatus shared by a plurality of communication systems, specifically two communication systems (hereinafter referred to as “multiple system shared base station”). Yes). In the following description, the two communication methods may be referred to as “first method” and “second method”. The two communication methods are the LTE method and the 3G method. In the present embodiment, a case will be described in which the first method is the LTE method and the second method is the 3G method.

  The base station apparatus 1 of this Embodiment is provided with the 1st system function part 141, the 2nd system function part 142, and the self-base station communication maintenance control part 126 shown in above-mentioned FIG. The first method function unit 141 is a part having a function corresponding to the first method. The second method function unit 142 is a part having a function corresponding to the second method. In the present embodiment, in the configuration of the base station apparatus 1 shown in FIG. 1 described above, the LTE-side functional part corresponds to the first method functional unit 141, and the 3G-side functional part corresponds to the second method functional unit 142. .

  In the present embodiment, the base station apparatus 1 determines whether or not the user needs to continue communication with the own base station apparatus 1 even if the communication method changes, and gives priority to the necessary base station apparatus 1 Control assigned to the station apparatus 1 is performed. In addition, the base station device 1 has a restriction such as a condition and a setting that the user must continue to communicate with the base station device 1 that is communicating even if the communication method is changed. The communication system switching request from the communication terminal is allowed, and control for rejecting the communication system switching request from the communication terminal without such restriction is performed. In addition, the base station apparatus 1 performs control to change the communication method to a higher transmission rate in the first method and the second method.

  For example, in FIG. 12 and FIG. 13, the other base station device 135 is a single mode base station that supports only a single communication mode, and three UEs of the first UE 131, the second UE 132, and the third UE 133 Assume that the stations 1 and 140 are all communicating with the second system. From this state, consider a case where the first UE 131 requests a transition to the first scheme, the second UE 132 requests a transition to the first scheme, and finally the third UE 133 requests a transition to the first scheme. In each of the multi-system shared base stations 1 and 140, the number of users that can be handled by the first system, that is, the number of communication terminals that can simultaneously communicate with the first system is “2”.

  As shown in FIG. 13, in the base station apparatus 140 that does not include the own base station communication maintenance control unit 126, the number of users that can be handled by the first scheme is “2”, so that the last scheme is requested to shift to the first scheme. The third UE 133 cannot maintain communication during communication with the base station 140, and performs handover so as to perform communication of the first scheme with other base stations 135.

  On the other hand, the base station apparatus 1 of this Embodiment is provided with the own base station communication maintenance control part 126, as shown in FIG. The base station device 1 determines to maintain communication during communication with the own base station device 1 only for the third UE 133 that uses a service specific to the own base station device 1, and the base station device 1 Switch to one-mode communication. Then, the base station apparatus 1 determines that the communication during communication with the own base station apparatus 1 is not maintained for the first and second UEs 131 and 132 that do not use the service unique to the own base station apparatus 1, The first and second UEs 131 and 132 are instructed to execute a handover so as to communicate with the base station apparatus 135 in the first scheme.

  As described above, according to the present embodiment, the base station apparatus 1 maintains communication during communication with the own base station apparatus 1 for the third UE 133 that uses a service specific to the own base station apparatus 1. It judges and switches to the communication of the 1st system in the own base station apparatus 1. FIG. Thereby, the base station apparatus 1 can maintain communication during communication with a UE that uses a service specific to the base station apparatus even if the communication method changes. Therefore, even if the communication method changes, a special service for the UE can be maintained.

  In addition, in the base station apparatus 1 of the present embodiment, when the number of users that can be handled for each communication method is different, it is determined that communication during communication with the UE that satisfies the maintenance condition is maintained, and the UE that does not satisfy the maintenance condition It is determined that the communication during the communication is not maintained. For example, when the UE uses a service specific to the base station apparatus 1, the base station apparatus 1 determines to maintain communication during communication with the base station apparatus 1, and the UE When the service unique to the device 1 is not used, it is determined that the communication during communication with the own base station device 1 is not maintained.

  As a result, for a UE that uses a service specific to its own base station apparatus 1, communication during communication with its own base station apparatus 1 can be maintained even if the communication method changes. Therefore, it is possible to prevent the service specific to the base station apparatus 1 from being invalidated by CSFB.

  Moreover, in this Embodiment, the base station apparatus 1 performs control which changes a communication system to the one where transmission speed is higher by the 1st system and the 2nd system. Therefore, since the transmission rate at which the user can communicate can be maintained in an optimum state, the optimum service can be supplied to the user of the UE.

  In this Embodiment described above, the base station apparatus 1 is comprised so that switching control may be performed based on a judgment of an own apparatus. In another embodiment of the present invention, the base station device 1 is configured to perform switching control based on an instruction from the base station host device 134 on the core network side such as an MME. Also good.

  In this case, the base station host apparatus 134 determines whether or not the user needs to continue communication with the same base station apparatus 1 even if the communication method changes, and gives priority to the necessary base station apparatus. The control assigned to 1 is performed. Also, the base station host apparatus 134 rejects the communication system change request when there are restrictions such as conditions and settings that the user must continue to communicate with the base station apparatus 1 in communication even if the communication system changes. Take control. In addition, the base station host apparatus 134 performs control to change the communication method to a higher transmission rate in the first method and the second method.

  As described above, in the present embodiment, as shown in FIG. 10 described above, base station apparatus 1 includes LTE base station communication maintenance control section 126 in LTE PF section 45 and 3G PF section 62. Composed. The base station apparatus 1 is not limited to this, and may be configured to include the own base station communication maintenance control unit 126 in the LTE AP unit 44 and the 3G AP unit 61 illustrated in FIG. 1 described above.

  In the above embodiment, since the CSFB from the LTE system to the 3G system is described, the LTE-side functional part corresponds to the first communication means, and the 3G-side functional part corresponds to the second communication means. The LTE-side functional part may correspond to the second communication unit, and the 3G-side functional part may correspond to the first communication unit. In this case, the LTE method corresponds to the second communication method, and the 3G method corresponds to the first communication method.

  DESCRIPTION OF SYMBOLS 1 Base station apparatus, 45 LTE PF part, 62 3G PF part, 101 CSFB detection part, 102 LTE transmission power / CQI information acquisition part, 103 Transmission power determination part, 104 3G CQI information acquisition part, 105 3G use Macro cell information acquisition unit, 124 special service use terminal identification unit, 125 connection destination determination unit, 126 own base station communication maintenance control unit.

Claims (8)

A base station apparatus capable of wireless communication with a communication terminal apparatus using different first and second communication methods,
First communication means for communicating with the communication terminal device in a first communication method;
Second communication means for communicating with the communication terminal device by a second communication method;
A switching request for switching the communication method from the first communication method to the second communication method is transmitted from the communication terminal device communicating with the base station device in the first communication method by the first communication means. Detecting means for detecting
The switching request is sent from the communication terminal device by the detection unit when the base station device and the communication terminal device are communicating by the first communication unit by the first communication unit. Once detected, the communication quality of the base station apparatus in the prior SL second communication scheme, the Do so that equal to the communication quality of the base station apparatus in the first communication method, from the second communication means Transmission power determining means for determining transmission power to the communication terminal device, and control means for controlling the second communication means so that the transmission power is determined by the transmission power determining means. A characteristic base station apparatus. The control means includes
Quality information acquisition means for acquiring quality information representing signal reception quality in the communication terminal device;
And a analysis means for determining the reception level from the quality information acquired by the quality information acquiring unit,
The transmission power determining means determines the transmission power based on the reception level obtained from the quality information by the analyzing means and the quality information obtained by the quality information obtaining means. The base station apparatus according to claim 1. The control means includes
When the detection unit detects that the switching request is transmitted from the communication terminal device, the determination unit determines whether or not to maintain communication during communication between the base station device and the communication terminal device. With steps ,
The second communication so that the transmission power determined by the transmission power determination means becomes equal to the second communication when the determination means determines to maintain the communication during communication between the own base station apparatus and the communication terminal apparatus. The base station apparatus according to claim 1 or 2, wherein the means is controlled . Before SL determining means, the number of the first available communication terminal device simultaneously communication means, if it exceeds the number of available communication terminal device simultaneously in the second communication unit, satisfies the maintenance conditions specified in advance to determines that maintaining the communication during communication with the communication terminal apparatus, according to claim 3, characterized in that determines not to maintain communication in the communication with the communication terminal apparatus that does not satisfy the maintenance condition Base station device. The maintenance condition, the communication terminal apparatus, base station apparatus according to claim 4, characterized in der Rukoto that utilizes a unique service to the base station apparatus. Based on the cyclic redundancy check result obtained by decoding the signal transmitted from the communication terminal device, the communication terminal device can select any one of the first communication method and the second communication method. An identification means for identifying whether a signal is received,
Said detecting means, based on the identification result by the identifying means, from the communication terminal apparatus according to any one of claims 1-5, characterized that you detecting that the switching request has been sent Base station device. Communication system comprising: the base station apparatus, wherein the said base station apparatus capable of wireless communication with the communication terminal apparatus in any one of 請 Motomeko 1-6. A communication terminal device, with the communication terminal device, passing Ru comprises capable of wireless communication with the base station apparatus at different first and second communication scheme with each other, and a base station host apparatus that controls the base station apparatus Communication system ,
The base station device
First communication means for communicating with the communication terminal device in a first communication method;
Second communication means for communicating with the communication terminal device by a second communication method;
Control means for controlling the first communication means and the second communication means,
The base station host apparatus is
A switching request for switching the communication method from the first communication method to the second communication method is sent from the communication terminal device communicating with the base station device in the first communication method by the first communication unit. Detecting means for detecting
The switching request is transmitted from the communication terminal device by the detection unit when the base station device and the communication terminal device are communicating with each other by the first communication unit by the first communication unit. When detected, from the second communication means to the communication terminal apparatus so that the communication quality of the base station apparatus in the second communication scheme is equal to the communication quality of the base station apparatus in the first communication scheme. An instruction means for instructing the control means of the base station apparatus to determine the transmission power to the base station apparatus and to control the second communication means to be the determined transmission power,
The control means of the base station apparatus determines that the communication quality of the base station apparatus in the second communication scheme is based on an instruction from the instruction means of the base station host apparatus in the first communication scheme. Determining the transmission power from the second communication means to the communication terminal apparatus so as to be equal to the communication quality of the station apparatus, and controlling the second communication means so as to be the determined transmission power. A featured communication system .

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