WO2014002946A1 - Dispositif formant station de base sans fil, procédé de contrôle de communication, et programme de contrôle de communication - Google Patents

Dispositif formant station de base sans fil, procédé de contrôle de communication, et programme de contrôle de communication Download PDF

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Publication number
WO2014002946A1
WO2014002946A1 PCT/JP2013/067242 JP2013067242W WO2014002946A1 WO 2014002946 A1 WO2014002946 A1 WO 2014002946A1 JP 2013067242 W JP2013067242 W JP 2013067242W WO 2014002946 A1 WO2014002946 A1 WO 2014002946A1
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WO
WIPO (PCT)
Prior art keywords
base station
radio
terminal device
radio base
wireless
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PCT/JP2013/067242
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English (en)
Japanese (ja)
Inventor
剛史 山本
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住友電気工業株式会社
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Publication of WO2014002946A1 publication Critical patent/WO2014002946A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/0085—Hand-off measurements
    • H04W36/0088—Scheduling hand-off measurements

Definitions

  • the present invention relates to a radio base station apparatus, a communication control method, and a communication control program, and in particular, a radio base station apparatus and communication control in a communication system in which a radio terminal apparatus can communicate with a plurality of radio base station apparatuses by performing a handover operation.
  • the present invention relates to a method and a communication control program.
  • a communication service is provided by a radio base station apparatus (hereinafter also referred to as a macro base station) that forms an area in which a cell having a radius of several hundred meters to several tens of kilometers, that is, a radio terminal apparatus can communicate. It was.
  • a radio base station apparatus hereinafter also referred to as a macro base station
  • This small base station is a femto base station forming a femto cell having a radius of about 10 meters, or a pico base station forming a pico cell having a radius of 100 to 200 meters.
  • femto base stations are out of the area of the macro cell (Macro Cell) formed by the macro base station, and in places such as indoor and underground shopping centers where it is difficult to install the macro base station. It can be used.
  • Non-Patent Document 1 a plurality of femto cells or pico cells are formed in a macro cell.
  • the number of small base stations such as femto base stations and pico base stations has been increasing.
  • the change in the received power is abrupt near the radio base station device, and the change in the received power at the cell edge of the cell formed by the radio base station is a femto base station or a pico base station rather than a macro base station.
  • the smaller base station is larger. For this reason, with the increase in the number of small base stations installed, the handover operation of the wireless terminal device is likely to occur.
  • the frequency of a radio signal used between a radio base station apparatus (hereinafter also referred to as a serving base station) that establishes a communication connection with the radio terminal apparatus and the radio terminal apparatus, and other than the serving base station
  • the frequency of the radio signal transmitted from the peripheral base station that is the radio base station apparatus may be different.
  • the radio terminal device is different from the frequency of the radio signal used between itself and the serving base station because an appropriate radio base station device is selected as a communication connection destination.
  • the frequency radio signal is intermittently measured and the measurement result is transmitted to the serving base station (see Non-Patent Document 2 (3GPP TS 36.133 V10.4.0)).
  • the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a radio that can suppress an increase in power consumption in a radio terminal apparatus in a measurement operation of radio signals transmitted from neighboring base stations.
  • a base station apparatus, a communication control method, and a communication control program are provided.
  • a radio base station apparatus provides a radio signal between radio terminal apparatuses that can communicate with a plurality of radio base station apparatuses by performing a handover operation.
  • the wireless terminal device is a wireless signal transmitted from a wireless base station device other than the serving base station that is the wireless base station device selected by itself as a communication partner.
  • the different frequency measurement operation for measuring a radio signal having a frequency different from the frequency of the radio signal used by the serving base station is intermittently performed, and the radio base station device should perform the different frequency measurement operation.
  • Different frequency measurement interval setting unit for setting the interval for the above-mentioned wireless terminal device, its own wireless base station device, and peripherals other than its own wireless base station device
  • a coverage area determining unit for determining whether a coverage area, which is an area where the device can communicate with the radio base station device, satisfies a predetermined condition, and the different frequency measurement interval setting unit includes: The interval is changed based on whether the predetermined condition is satisfied.
  • the situation where the coverage area satisfies the predetermined condition is, for example, a sufficiently large coverage area, and even if the wireless terminal device moves to some extent, the serving base station or the serving base station and the wireless terminal device In this situation, sufficient reception quality can be obtained for radio signals from neighboring base stations using the same frequency as the frequency of radio signals transmitted and received between them.
  • the different frequency measurement interval setting unit sets the interval longer when the coverage area satisfies the predetermined condition.
  • the power consumption of the wireless terminal device can be suppressed by reducing the number of times the wireless terminal device performs the different frequency measurement operation.
  • the radio base station apparatus further acquires a measurement result notification indicating a measurement result of reception power in a radio terminal apparatus of a radio signal transmitted from the radio base station apparatus, and the acquired measurement result notification
  • a coverage hole determination unit for determining whether or not the reception quality of the radio signal transmitted from the same frequency peripheral base station in the wireless terminal device satisfies a predetermined condition, and the coverage area determination unit includes: If the coverage hole determination unit determines that the reception quality does not satisfy the predetermined condition, it determines that the coverage area does not satisfy the predetermined condition.
  • the communication connection between itself and the serving base station is disconnected and a communication connection between itself and the neighboring base station is newly established
  • a notification indicating that the communication connection with the serving base station has been disconnected and the measurement result notification are transmitted to the newly established peripheral base station, and the coverage hole determining unit
  • the measurement result notification to be transmitted is acquired, and the acquired measurement result notification does not include the measurement result of the received power of the radio signal transmitted from the same frequency peripheral base station, or the measurement result notification If the measurement result of the received power at the wireless terminal device of the included radio signal transmitted from the same frequency peripheral base station does not satisfy the predetermined condition, the reception quality satisfies the predetermined condition. It is determined that it does not.
  • the reception quality in the radio terminal device is a predetermined condition.
  • the configuration for determining whether or not the condition is satisfied it is possible to accurately detect the situation where the reception quality does not satisfy the predetermined condition, and to appropriately set the interval of the different frequency measurement operation.
  • the radio base station apparatus further determines whether the radio terminal apparatus is located in a predetermined area among cell areas in which the radio terminal apparatus is predicted to be able to communicate with its own radio base station apparatus.
  • a terminal position determining unit for determining whether or not the different frequency measurement interval setting unit sets the predetermined area by the terminal position determining unit even when the coverage area does not satisfy the predetermined condition. When it is determined that the wireless terminal device is not located, the interval is set to be long.
  • a radio base station apparatus is provided between a radio terminal apparatus capable of communicating with a plurality of radio base station apparatuses by performing a handover operation.
  • a wireless base station device for transmitting and receiving wireless signals at the wireless base station device, wherein the wireless terminal device is transmitted from a wireless base station device other than the serving base station that is the wireless base station device selected by itself.
  • a different frequency measurement period capable of measuring a radio signal that is different from the frequency of the radio signal used by the serving base station is periodically provided, and the radio base station apparatus Among the peripheral base stations that are wireless base station devices other than the local wireless base station device and the local wireless base station device, the frequency of the radio signal transmitted and received between the wireless base station device and the wireless terminal device is the same. For determining whether or not a coverage area, which is an area formed by the same frequency peripheral base station using the frequency and in which the wireless terminal device can communicate with the wireless base station device, satisfies a predetermined condition Based on whether the coverage area determination unit and the coverage area satisfy the predetermined condition, a difference for instructing the wireless terminal device whether to measure the wireless signal in the different frequency measurement period.
  • a frequency measurement instruction unit For determining whether or not a coverage area, which is an area formed by the same frequency peripheral base station using the frequency and in which the wireless terminal device can communicate with the wireless base station device, satisfies a predetermined condition Based on whether the coverage area determination unit and the coverage area
  • Non-Patent Document 2 3GPP TS 36.133 V10.4.0
  • the interval between different frequency measurement periods is specified as 80 ms at maximum.
  • the interval at which the radio terminal apparatus should perform the different frequency measurement operation is appropriately set according to whether or not the coverage area satisfies the predetermined condition without changing the interval of the different frequency measurement period. Since it can be set, an increase in power consumption in the wireless terminal device can be suppressed in the measurement operation of the wireless signal transmitted from the neighboring base station.
  • a radio base station apparatus is provided between a radio terminal apparatus capable of communicating with a plurality of radio base station apparatuses by performing a handover operation.
  • a wireless base station device for transmitting and receiving wireless signals at the wireless base station device, wherein the wireless terminal device is transmitted from a wireless base station device other than the serving base station that is the wireless base station device selected by itself.
  • the radio base station apparatus intermittently performs a different frequency measurement operation for measuring a radio signal and a radio signal having a frequency different from the frequency of the radio signal used by the serving base station.
  • a different frequency measurement interval setting unit for setting an interval to be performed for the wireless terminal device, and a cell area in which the wireless terminal device is predicted to be able to communicate with its own wireless base station device
  • a terminal position determination unit for determining whether or not the wireless terminal device is located in a predetermined area, and the different frequency measurement interval setting unit determines whether or not the wireless terminal device is located in the predetermined area. Based on this, the length of the interval is changed.
  • the wireless terminal device is transmitted from the neighboring base stations with a configuration in which the interval for performing the different frequency measurement operation by the wireless terminal device is appropriately set depending on whether or not the wireless terminal device is located in a predetermined area of the cell area.
  • the wireless signal measurement operation an increase in power consumption in the wireless terminal device can be suppressed.
  • the predetermined area is near the end of the cell area, and the different frequency measurement interval setting unit sets the interval long when the wireless terminal device is not located near the end of the cell area. To do.
  • the radio base station apparatus further includes a measurement result acquisition unit for acquiring a measurement result by the radio terminal apparatus of reception power of a radio signal transmitted by the radio base station apparatus, and the terminal position determination unit includes: When the received power indicated by the measurement result is greater than a predetermined threshold, it is determined that the wireless terminal device is not located in the predetermined area.
  • a communication control method provides a radio signal between radio terminal apparatuses that can communicate with a plurality of radio base station apparatuses by performing a handover operation.
  • the radio base station apparatus and the self radio base station are configured to intermittently perform a different frequency measurement operation for measuring a radio signal and a radio signal having a frequency different from the frequency of the radio signal used by the serving base station.
  • the same frequency as the frequency of the wireless signal transmitted and received between the own wireless base station device and the wireless terminal device is set.
  • a communication control method includes a wireless terminal device capable of communicating with a plurality of wireless base station devices by performing a handover operation.
  • a communication control method in a radio base station apparatus for transmitting and receiving radio signals wherein the radio terminal apparatus is from a radio base station apparatus other than a serving base station that is a radio base station apparatus selected by itself as a communication partner.
  • a different frequency measurement period capable of measuring a radio signal to be transmitted and having a frequency different from that of the radio signal used by the serving base station is provided.
  • the same frequency as the frequency of the wireless signal transmitted and received between the own wireless base station device and the wireless terminal device is set. Determining whether or not a coverage area, which is an area formed by the same frequency peripheral base station in use and is an area where the wireless terminal device can communicate with the wireless base station device, satisfies the predetermined condition; and Instructing the radio terminal device whether to measure the radio signal in the different frequency measurement period based on whether the coverage area satisfies the predetermined condition.
  • a communication control method includes a wireless terminal device capable of communicating with a plurality of wireless base station devices by performing a handover operation.
  • a communication control method in a radio base station apparatus for transmitting and receiving radio signals wherein the radio terminal apparatus is from a radio base station apparatus other than a serving base station that is a radio base station apparatus selected by itself as a communication partner.
  • the radio terminal device performs a different frequency measurement operation for measuring a radio signal to be transmitted and a radio signal having a frequency different from the frequency of the radio signal used by the serving base station.
  • the length of the interval is changed based on whether or not the wireless terminal device is located in the predetermined area.
  • the wireless terminal device is transmitted from the neighboring base stations with a configuration in which the interval for performing the different frequency measurement operation by the wireless terminal device is appropriately set depending on whether or not the wireless terminal device is located in a predetermined area of the cell area.
  • the wireless signal measurement operation an increase in power consumption in the wireless terminal device can be suppressed.
  • a communication control program provides a radio signal between radio terminal apparatuses capable of communicating with a plurality of radio base station apparatuses by performing a handover operation.
  • peripheral base stations that are wireless base station devices other than the own wireless base station device, transmission / reception is performed between the own wireless base station device and the wireless terminal device.
  • the coverage area which is an area formed by the same frequency peripheral base station using the same frequency as the frequency of the radio signal to be transmitted and in which the radio terminal apparatus can communicate with the radio base station apparatus, satisfies the predetermined condition.
  • a communication control program provides a communication between a radio terminal apparatus capable of communicating with a plurality of radio base station apparatuses by performing a handover operation.
  • a communication control program used in a radio base station apparatus for transmitting and receiving radio signals wherein the radio terminal apparatus is a radio base station other than a serving base station that is a radio base station apparatus selected by itself as a communication partner
  • the radio terminal apparatus is a radio base station other than a serving base station that is a radio base station apparatus selected by itself as a communication partner
  • a different frequency measurement period capable of measuring a radio signal transmitted from a device and having a frequency different from that of the radio signal used by the serving base station is provided, and the computer has its own radio base station.
  • the coverage area which is an area formed by the same frequency peripheral base station using the same frequency as the frequency of the radio signal to be transmitted and in which the radio terminal apparatus can communicate with the radio base station apparatus, satisfies a predetermined condition Instructing the radio terminal apparatus whether to measure the radio signal in the different frequency measurement period based on whether or not the coverage area satisfies the predetermined condition. Is a program for executing steps.
  • a communication control program provides a communication between a radio terminal device capable of communicating with a plurality of radio base station devices by performing a handover operation.
  • a communication control program used in a radio base station apparatus for transmitting and receiving radio signals wherein the radio terminal apparatus is a radio base station other than a serving base station that is a radio base station apparatus selected by itself as a communication partner
  • a radio signal transmitted from the apparatus, and a different frequency measurement operation for measuring a radio signal having a frequency different from the frequency of the radio signal used by the serving base station is intermittently performed.
  • the wireless terminal device is transmitted from the neighboring base stations with a configuration in which the interval for performing the different frequency measurement operation by the wireless terminal device is appropriately set depending on whether or not the wireless terminal device is located in a predetermined area of the cell area.
  • the wireless signal measurement operation an increase in power consumption in the wireless terminal device can be suppressed.
  • the present invention it is possible to suppress an increase in power consumption in the wireless terminal device in the measurement operation of the wireless signal transmitted from the neighboring base station.
  • the radio base station apparatus notifies the radio terminal apparatus of information about the cell and the neighboring cell that it forms, that is, the frequency of the radio signal and the ID (identification) of the neighboring cell.
  • the wireless terminal device detects and measures neighboring cells based on information notified from the wireless base station device.
  • the wireless terminal device starts moving to the neighboring cell based on the measurement result.
  • “movement” of the wireless terminal device means not only handover but also through which cell the wireless terminal device in an idle state starts communication in the future, that is, when a call or data communication is started. This means selecting whether to perform communication.
  • the destination of the wireless terminal device is determined by the wireless base station device or the higher-level device in the core network. For example, when the wireless terminal device is not communicating with the wireless base station device, the wireless terminal device determines the destination of the wireless terminal device.
  • handover means that a radio base station apparatus that is a communication partner of a radio terminal apparatus during a call or data communication is switched.
  • the wireless terminal device is located in a cell means that the wireless terminal device selects a wireless base station device forming the cell as a communication destination, that is, a communication connection destination, and communicates with the wireless base station device. It means a possible state or a state where communication is in progress.
  • a femto base station is a customer premises apparatus that connects a wireless terminal device connected via a wireless interface to a mobile communication carrier network using an IP backhaul.
  • the femto base station in the closed access mode provides a service only to the related CSG (Closed Subscriber Group) members.
  • the hybrid mode femto base station also provides services to the associated CSG members and CSG non-members.
  • the femto base station in the open access mode operates as a normal base station.
  • the macro base station and the pico base station are wireless base station devices that are under the control of the mobile communication carrier and can communicate with the wireless terminal devices that are contracted with the mobile communication carrier. Further, it is considered that the macro base station and the pico base station are basically not turned off.
  • the femto base station is a radio base station apparatus that is mainly installed in an individual or corporate building and may move or be turned off depending on user circumstances.
  • the femto base station operates in an access mode of open / hybrid / closed.
  • the closed access mode only registered members (terminals) can be connected.
  • the service is provided only to registered members.
  • the hybrid mode the service is provided to both registered members and unregistered members, that is, non-members.
  • the open access mode the same operation as that of the macro base station and the pico base station is performed.
  • FIG. 1 is a diagram illustrating a configuration of a communication system including a radio base station apparatus according to the first embodiment of the present invention.
  • the communication system is a mobile communication system that complies with LTE (Long Term Evolution) standardized by 3GPP, for example, and includes radio base station apparatuses 101A and 101B.
  • Radio base station apparatus 101A is, for example, a macro base station
  • radio base station apparatus 101B is, for example, a femto base station or a pico base station.
  • the wireless base station device 101A can communicate with the wireless terminal device 202 by forming a cell CA and transmitting / receiving a wireless signal of the frequency f1 to / from the wireless terminal device 202 existing in the cell CA.
  • the radio base station apparatus 101B forms a cell CB and can communicate with the radio terminal apparatus 202 by transmitting and receiving radio signals of the frequency f2 or frequency f3 to and from the radio terminal apparatus 202 existing in the cell CB. .
  • the radio base station apparatuses 101A and 101B and the radio terminal apparatus 202 read out and execute a program including each step of the following sequences from a memory (not shown).
  • This program can be installed externally.
  • the installed program is distributed in a state stored in a recording medium, for example.
  • FIG. 2 is a diagram illustrating an example of a sequence of a handover operation in a communication system including the radio base station apparatus according to the first embodiment of the present invention.
  • wireless terminal apparatus 202 when wireless terminal apparatus 202 is located in cell CA and is in communication with wireless base station apparatus 101A, wireless terminal apparatus 202 moves in a direction approaching cell CB.
  • the radio base station apparatus 101A is also referred to as a serving base station 101A
  • the radio base station apparatus 101B is also referred to as a peripheral base station 101B.
  • a cell formed by the serving base station 101A is also referred to as a serving cell CA
  • a cell formed by the peripheral base station 101B is also referred to as a peripheral cell CB.
  • radio base station apparatus 101 ⁇ / b> A transmits to radio terminal apparatus 202 an inquiry about the radio signal reception capability of radio terminal apparatus 202 in communication with itself.
  • the wireless terminal device 202 acquires information such as the cell IDs of the serving cell CA and the neighboring cell CB from the serving base station 101A communicating with itself. Then, based on the acquired information, the wireless terminal device 202 measures the received power of the wireless signal transmitted from the serving base station 101A and the wireless signal transmitted from the neighboring base station 101B.
  • a radio signal having the frequency f1 is used between the serving base station 101A and the radio terminal device 202, and a radio signal having the frequency f2 or the frequency f3 is transmitted from the neighboring base station 101B.
  • the terminal device 202 cannot perform transmission / reception of a radio signal with the serving base station 101A and reception of a radio signal transmitted from the neighboring base station 101B in parallel. For this reason, the radio
  • the wireless terminal device 202 may include, for example, a plurality of communication units.
  • the plurality of communication units transmit and receive a radio signal of frequency f1 to and from the serving base station 101A,
  • the radio terminal apparatus 202 can perform these operations in parallel by sharing the reception of the radio signals of the frequencies f2 and f3 transmitted from the base station 101B.
  • the radio base station apparatus 101A is configured such that the radio terminal apparatus 202 transmits / receives a radio signal having a frequency f1 to / from the serving base station 101A and receives radio signals having frequencies f2 and f3 transmitted from the neighboring base station 101B.
  • the wireless terminal device 202 receives the terminal capability inquiry from the wireless base station device 101A, transmits / receives its own reception capability, that is, transmission / reception of a radio signal of the frequency f1 to / from the serving base station 101A, and from the neighboring base station 101B.
  • a terminal capability response indicating whether or not reception of radio signals of frequencies f2 and f3 to be transmitted can be performed in parallel is transmitted to radio base station apparatus 101A (step S12).
  • the wireless base station device 101A receives the terminal capability response from the wireless terminal device 202, and measures the interval of the different frequency measurement operation in the measurement of the received power by the wireless terminal device 202 according to the received terminal capability response.
  • the different frequency measurement operation is a measurement operation of a radio signal from a neighboring base station performed by the radio terminal device 202, and is a frequency different from the frequency used between the serving base station and the radio terminal device 202. This is an operation of intermittently measuring the radio signal.
  • FIG. 3 is a diagram illustrating a relationship between a communication period between a wireless terminal device and a serving base station and a different frequency measurement period in which a radio signal transmitted from a neighboring base station can be measured.
  • the wireless terminal device 202 when the wireless terminal device 202 includes only one communication unit, that is, the wireless terminal device 202 transmits / receives a wireless signal having the frequency f1 to / from the serving base station 101A and the frequency transmitted from the neighboring base station 101B. Assume that the radio signals f2 and f3 cannot be received in parallel. In this case, as illustrated in FIG. 3, the wireless terminal device 202 provides a different frequency measurement period (Gap) in which a different frequency measurement operation can be performed, and performs communication with the serving base station 101A during the period. The radio signals of the frequencies f2 and f3 transmitted from the peripheral base station 101B are received without performing the measurement, and the received power is measured.
  • Gap frequency measurement period
  • the radio base station apparatus 101A transmits / receives a radio signal of frequency f1 to / from the serving base station 101A from the radio terminal apparatus 202, and radio signals of frequencies f2 and f3 transmitted from the neighboring base station 101B.
  • the terminal capability response indicating that the reception of the terminal cannot be performed in parallel is received, it is determined to provide a different frequency measurement period, and for example, the interval of the different frequency measurement operation is set to 80 ms.
  • the radio base station apparatus 101A transmits / receives a radio signal of frequency f1 to / from the serving base station 101A from the radio terminal apparatus 202 and receives radio signals of frequencies f2 and f3 transmitted from the neighboring base station 101B.
  • the terminal capability response indicating that it can be performed in parallel is received, for example, it is possible not to provide the different frequency measurement period so that the different frequency measurement operation is not performed (step S13).
  • radio base station apparatus 101A transmits an RRC (Radio Resource Control) connection reconfiguration instruction (RRC Connection Reconfiguration) to wireless terminal apparatus 202.
  • RRC connection reconfiguration instruction includes the setting contents set in step S13 and the cell IDs of the neighboring cells (step S14).
  • the wireless terminal device 202 receives the RRC connection reconfiguration instruction and performs a different frequency measurement operation according to the setting content included in the RRC connection reconfiguration instruction. Then, the wireless terminal device 202 transmits a measurement result notification (Measurement Report) indicating the measurement result obtained by the different frequency measurement operation to the wireless base station device 101A (step S15).
  • a measurement result notification (Measurement Report) indicating the measurement result obtained by the different frequency measurement operation to the wireless base station device 101A (step S15).
  • the radio base station apparatus 101A acquires measurement information indicating the measurement result for each cell ID and stores it in a storage unit (not shown). Then, based on the measurement result notification received from the wireless terminal device 202, the wireless base station device 101A determines whether or not to perform the handover operation of the wireless terminal device 202, and should execute the handover operation. When the determination is made, reference is made to neighboring cell information, and for example, the radio base station apparatus 101B is determined as a handover destination radio base station apparatus (step S16).
  • the radio base station apparatus 101A transmits a handover request indicating the handover destination radio base station apparatus 101B to the radio base station apparatus 101B (step S17).
  • the radio base station apparatus 101B receives the handover request from the radio base station apparatus 101A, and transmits a handover response to the handover request to the radio base station apparatus 101A (step S18).
  • the radio base station apparatus 101A receives the handover response from the radio base station apparatus 101B, and transmits an RRC connection reconfiguration instruction to the radio terminal apparatus 202 (step S19).
  • the radio base station apparatus 101A transmits a status notification indicating its own communication status to the radio base station apparatus 101B (step S20).
  • the wireless terminal device 202 transmits an RRC connection reconfiguration completion notification (RRCRRConnection Reconfiguration Complete) to the wireless base station device 101B ( Step S21).
  • the radio base station apparatus 101B receives the RRC connection reconfiguration completion notification from the radio terminal apparatus 202 and transmits a handover completion notification to the radio base station apparatus 101A (step S22). And the operation
  • FIG. 4 is a diagram illustrating an example of a coverage hole due to interference in a communication system including the radio base station apparatus according to the first embodiment of the present invention.
  • the communication system is a mobile communication system that complies with LTE standardized by, for example, 3GPP, and wireless base station apparatus 101A that transmits and receives a radio signal of frequency f1 to and from wireless terminal apparatus 202. And radio base station apparatuses 101Ba, 101Bb, and 101Bc that perform transmission and reception of radio signals of frequency f2 with the radio terminal apparatus 202.
  • the wireless terminal device 202 is located in the cell CA formed by the wireless base station device 101A, and is formed in each of the wireless base station devices 101Ba, 101Bb, and 101Bc in a state of communicating with the wireless base station device 101A. Assume that the cell CBa, CBb, and CBc are moved to the overlapping area.
  • the wireless terminal device 202 when the wireless terminal device 202 moves toward the overlapping region of the cells CBa, CBb, and CBc, the wireless terminal device 202 enters a region where interference between radio waves transmitted from the wireless base station devices 101Ba, 101Bb, and 101Bc is large. . In this region, the difference between the received powers of the cells becomes small, and the magnitude relationship between the received powers of the cells changes with a short movement time. For this reason, sufficient reception quality is not obtained for radio waves from any of the radio base station apparatuses 101A, 101Ba, 101Bb, and 101Bc, and radio link disconnection (RLF: Radio Link Failure) occurs. In addition, an area in which sufficient reception quality is not obtained for radio waves from any of the radio base station apparatuses 101 is hereinafter also referred to as a coverage hole due to interference.
  • RLF Radio Link Failure
  • the wireless terminal device 202 searches for the reconnection destination wireless base station device by measuring the reception power of the wireless signal. For example, when the wireless terminal device 202 moves out of the cell CBb, CBc and into the cell CBa, the wireless base station device 101Ba is used as a reconnection-destination wireless base station device and the wireless base station device 101Ba A normal connection procedure is executed between the wireless base station apparatus 101, the communication connection with the radio base station apparatus 101Ba is established, and the communication is restored from the RLF.
  • FIG. 5 is a diagram illustrating an example of a coverage hole with low power in a communication system including the radio base station apparatus according to the first embodiment of the present invention.
  • the communication system is a mobile communication system that complies with LTE standardized by, for example, 3GPP, and wireless base station apparatus 101A that transmits and receives a radio signal of frequency f1 to and from wireless terminal apparatus 202. And a radio base station apparatus 101B that transmits and receives a radio signal of frequency f2 to and from the radio terminal apparatus 202.
  • the wireless terminal device 202 is located in the cell CA formed by the wireless base station device 101A, and moves to the cell CB formed by the wireless base station device 101B in a state where it is communicating with the wireless base station device 101A. Assume a case.
  • the radio terminal apparatus 202 performs a measurement on a radio signal having a frequency different from the frequency f1, that is, performs a different frequency measurement operation.
  • the radio base station apparatus 101B is selected as a reconnection destination radio base station apparatus.
  • the reception quality sufficient for the radio signal of the frequency f1 transmitted from the radio base station apparatus 101A by the radio terminal apparatus 202 before the connection procedure with the radio base station apparatus 101B as a new communication connection destination is executed.
  • RLF occurs when Too Late HO is performed with the timing of the handover operation being too late.
  • sufficient reception is performed for the radio signal having the same frequency as that of the radio signal used between the radio terminal device 202 and the radio base station device 101A having established communication connection with the radio terminal device 202.
  • an area where quality is not obtained is also referred to as a low power coverage hole.
  • wireless terminal apparatus 202 will reset from RLF, if the connection procedure between the radio base station apparatuses 101B is performed.
  • the wireless terminal device 202 moves and the wireless terminal device 202 and a communication connection with the wireless terminal device 202 are established.
  • the reception quality at the wireless terminal device 202 of the wireless signal having the same frequency as the frequency of the wireless signal used between the wireless base station devices 101A is not sufficient reception quality and RLF occurs. That is, in such a situation, in order to stabilize communication, it is desirable that the different frequency measurement operation by the wireless terminal device 202 be performed at a short interval compared to a situation where there is no coverage hole.
  • the radio base station apparatuses 101A and 101B set the measurement parameters for the different frequency measurement operation based on whether or not a coverage hole exists.
  • a detailed configuration of the radio base station apparatuses 101A and 101B will be described.
  • FIG. 6 is a diagram illustrating the configuration of the radio base station apparatus according to the first embodiment of the present invention.
  • radio base station apparatuses 101A and 101B include an antenna 91, a circulator 92, a radio reception unit 93, a radio transmission unit 94, a signal processing unit 95, and a control unit 98.
  • the signal processing unit 95 includes a reception signal processing unit 96 and a transmission signal processing unit 97.
  • the signal processing unit 95 and the control unit 98 are realized by a CPU (Central Processing Unit) or a DSP (Digital Signal Processing).
  • the circulator 92 outputs the radio signal from the radio terminal device 202 received by the antenna 91 to the radio reception unit 93 and outputs the radio signal received from the radio transmission unit 94 to the antenna 91.
  • the radio reception unit 93 converts the frequency of the radio signal received from the circulator 92 into a baseband signal or IF (Intermediate Frequency) signal, converts the frequency converted signal into a digital signal, and outputs the digital signal to the reception signal processing unit 96.
  • IF Intermediate Frequency
  • the reception signal processing unit 96 performs signal processing such as despreading in a CDMA (Code Division Multiple Access) system on the digital signal received from the wireless reception unit 93, and performs part or all of the digital signal after the signal processing.
  • the data is converted into a predetermined frame format and transmitted to the core network side.
  • the transmission signal processing unit 97 performs IFFT (Inverse Fast Fourier Transform) in the OFDM (Orthogonal Frequency Division Multiplex) method for communication data obtained by converting communication data received from the core network side into a predetermined frame format or communication data generated by itself.
  • IFFT Inverse Fast Fourier Transform
  • OFDM Orthogonal Frequency Division Multiplex
  • the wireless transmission unit 94 converts the digital signal received from the transmission signal processing unit 97 into an analog signal, converts the frequency of the converted analog signal into a wireless signal, and outputs the converted signal to the circulator 92.
  • the control unit 98 exchanges various types of information with each unit and the core network in the radio base station apparatuses 101A and 101B.
  • FIG. 7 is a diagram illustrating a configuration of a control unit in the radio base station apparatus according to the first embodiment of the present invention.
  • each of the radio base station apparatuses 101A and 101B is also referred to as a radio base station apparatus 101.
  • control unit 98 includes handover request unit 11, handover instruction unit 12, measurement result acquisition unit 15, coverage hole determination unit 16, coverage area determination unit 17, and different frequency measurement control unit. 18 (different frequency measurement interval setting unit and different frequency measurement instruction unit).
  • the measurement result acquisition unit 15 acquires a measurement result notification indicating the measurement result of the received power of the radio signal in the wireless terminal device 202, and communicates between the wireless base station device 101 and the wireless terminal device 202 from the acquired measurement result notification. Quality is obtained, and the communication quality is notified to the handover request unit 11, the handover instruction unit 12, and the coverage hole determination unit 16.
  • the handover request unit 11 makes a request for performing a handover operation of the radio terminal apparatus 202 from the radio base station apparatus 101 to another radio base station apparatus to another radio base station apparatus, that is, a handover request is made to another radio base station apparatus. Send to station device.
  • the handover request unit 11 makes the above request to another radio base station apparatus when a predetermined condition regarding communication quality between the radio base station apparatus 101 and the radio terminal apparatus 202 is satisfied.
  • the handover instruction unit 12 instructs the radio terminal apparatus 202 to perform a handover operation from the radio base station apparatus 101 to another radio base station apparatus. That is, an RRC connection reconfiguration instruction is transmitted to the wireless terminal device 202.
  • the coverage hole determination unit 16 causes interference between wireless signals transmitted by a plurality of wireless base station devices. It is determined whether or not there is a coverage hole due to interference.
  • the coverage hole determination unit 16 generates an RLF for a radio base station apparatus that has established communication connection with the radio terminal apparatus 202, and from the occurrence of this RLF until the radio terminal apparatus 202 newly establishes a communication connection.
  • the required time is longer than a predetermined threshold, it is determined that the cause of RLF is that there is a coverage hole due to interference and the wireless terminal device 202 has entered this coverage hole.
  • the coverage hole determination unit 16 acquires the measurement result notification from the measurement result acquisition unit 15, and determines whether there is a coverage hole due to low power based on the acquired measurement result notification.
  • a radio base station apparatus that uses the same frequency as the frequency of the radio signal transmitted and received between the radio base station apparatus 101 and the radio terminal apparatus 202 is used.
  • the same frequency peripheral base station it is referred to as the same frequency peripheral base station.
  • an area formed by the same frequency peripheral base station and in which the wireless terminal device 202 can communicate with the wireless base station device is hereinafter referred to as a coverage area.
  • the coverage hole determination unit 16 newly establishes a communication connection with the wireless terminal device 202 when the communication connection between the wireless terminal device 202 and its own wireless base station device 101 is disconnected.
  • the measurement result notification is acquired from the wireless base station device.
  • the coverage hole determination unit 16 determines whether or not the acquired measurement result notification includes the measurement result of the received power of the radio signal transmitted from the same frequency peripheral base station, and determines that it is not included. If so, it is determined that a coverage hole exists. Further, for example, even if the measurement result notification includes the measurement result of the received power of the radio signal transmitted from the same frequency peripheral base station, the coverage hole determination unit 16 does not have the same frequency periphery included in the acquired measurement result notification. It is determined whether or not the reception power of the wireless signal transmitted from the base station at the wireless terminal device 202 satisfies a predetermined condition, that is, sufficient reception quality. If it is determined that the reception power is not satisfied, it is determined that a coverage hole exists. . Then, the coverage hole determination unit 16 outputs the determination result to the coverage area determination unit 17.
  • the coverage area determination unit 17 acquires a determination result indicating whether a coverage hole exists from the coverage hole determination unit 16, and determines whether the coverage area satisfies a predetermined condition based on the acquired determination result.
  • the situation where the coverage area satisfies the predetermined condition is, for example, that the coverage area is a sufficiently wide area, and even if the wireless terminal device 202 moves a certain distance, the serving base station or the serving base station. This is a situation where sufficient reception quality can be obtained for a radio signal from a peripheral base station using the same frequency as that of a radio signal transmitted / received to / from the radio terminal apparatus.
  • the coverage area determination unit 17 determines that the coverage area satisfies a predetermined condition and outputs the determination result to the different frequency measurement control unit 18. .
  • the coverage area determination unit 17 determines that the coverage area does not satisfy the predetermined condition and outputs the determination result to the different frequency measurement control unit 18. .
  • the different frequency measurement control unit 18 makes a terminal capability inquiry to the wireless terminal device 202. Further, the different frequency measurement control unit 18 (different frequency measurement interval setting unit) is configured so that the radio terminal device 202 transmits and receives radio signals to and from its own radio base station device 101 and between itself and its own radio base station device 101. When a terminal capability response indicating that radio signals having a frequency different from the frequency of the radio signal used in the radio signal cannot be received in parallel is received from the radio terminal device 202, a different frequency measurement operation may be performed. It is decided to provide a possible different frequency measurement period, for example, an interval at which the different frequency measurement operation is performed is set.
  • the different frequency measurement control unit 18 sets a long interval for performing the different frequency measurement operation. Then, the different frequency measurement control unit 18 transmits the set measurement parameter to the wireless terminal device 202.
  • the different frequency measurement control unit 18 (different frequency measurement instruction unit) performs the different frequency measurement operation in the different frequency measurement period in which the different frequency measurement operation can be performed based on whether or not the coverage area satisfies the predetermined condition. It is also possible to determine whether or not to execute and to instruct the wireless terminal device 202 of the determined content. For example, when the interval of the different frequency measurement period is defined in advance as 80 ms, the different frequency measurement control unit 18 performs the different frequency measurement every two different frequency measurement periods, that is, every 160 ms. It is also possible to determine that the operation is executed and to instruct the wireless terminal device 202 of the determination content. *
  • FIG. 8 shows coverage hole detection in a radio communication system including the radio base station apparatus according to the first embodiment of the present invention. It is a figure which shows an example of the sequence of operation
  • the wireless terminal device 202 is located in the cell CA and is communicating with the wireless base station device 101A.
  • step S31 to step S33 shown in FIG. 8 is the same as the operation from step S11 to step S13 shown in FIG. Will not repeat.
  • the wireless terminal device 202 moves to an area in which sufficient reception quality cannot be obtained for a wireless signal transmitted from the same frequency peripheral base station, that is, a coverage hole (step S34).
  • the RRC connection reconfiguration instruction (step S35) including the measurement parameter setting content transmitted from the wireless base station device 101A does not reach the wireless terminal device 202, and RLF occurs ( Step S36).
  • the radio terminal apparatus 202 searches for a neighboring radio base station apparatus by measuring the reception power of the radio signal and reconnects to the searched radio base station apparatus 101B.
  • a connection re-establishment request (RRC Connection Reestablishment Request) is transmitted (step S37).
  • the radio base station apparatus 101B receives an RRC connection re-establishment request from the radio terminal apparatus 202, and transmits an RRC connection re-establishment response to the radio terminal apparatus 202 (step S38). Thereby, an RRC connection is established between the wireless terminal device 202 and the wireless base station device 101B.
  • the wireless terminal device 202 transmits an RRC connection re-establishment completion notification (RRC Connection Reestablishment Complete) to the wireless base station device 101B (step S39).
  • RRC Connection Reestablishment Complete RRC Connection Reestablishment Complete
  • This RRC connection re-establishment completion notification includes a parameter “rlf-InfoAvailable”, for example.
  • the wireless terminal device 202 sets this parameter and transmits an RRC connection re-establishment completion notification.
  • the radio base station apparatus 101B recognizes that an RLF has occurred in the radio terminal apparatus 202.
  • the radio base station apparatus 101B transmits a terminal information request (UE Information Request) to the radio terminal device 202 in order to acquire detailed information of the RLF (step S40).
  • UE Information Request terminal information request
  • the wireless terminal device 202 receives the terminal information request from the wireless base station device 101B, and transmits a terminal information response (UE Information Response) including the RLF report to the wireless base station device 101B (step S41).
  • the RLF report includes the PCI (Physical Cell ID) of the radio base station device in which the RLF has occurred, the PCI and ECGI (E- UTRAN Cell Global Identifier) of the radio base station device in which the RRC connection has been reestablished, and the own radio terminal device.
  • C-RNTI Cell Radio Network Temporary Identifier
  • the PCI of the RLF occurrence is the ID of the serving base station 101A
  • the PCI and ECGI of the occurrence of RRC connection re-establishment are the IDs of the neighboring base station 101B
  • the C-RNTI is the ID assigned by the serving base station 101A.
  • the RLF report includes a measurement result notification indicating the measurement result of the received power of the radio signal transmitted from the serving base station 101A and the neighboring base station 101B in the wireless terminal device 202.
  • the radio base station apparatus 101B recognizes that RLF has occurred in the radio base station apparatus 101A by referring to the PCI of the RLF report received from the radio terminal apparatus 202.
  • the radio base station apparatus 101B then sends an RLF notification (RLFAINDICATION) including the content of the RLF report to the radio base station apparatus 101A via the X2 interface in order to notify that the RLF has occurred in the radio base station apparatus 101A. Transmit (step S42).
  • the radio base station apparatus 101A determines whether the measurement result notification included in the RLF notification received from the radio base station apparatus 101B includes the measurement result of the reception power of the radio signal transmitted from the same frequency peripheral base station. It is determined whether or not the measurement result notification indicates that sufficient reception quality is obtained for the radio signal transmitted from the same frequency peripheral base station. Then, the radio base station apparatus 101A determines that the measurement result notification does not include the measurement result of the reception power of the radio signal transmitted from the same frequency peripheral base station, or the measurement result notification If it is determined that sufficient reception quality is not obtained for the radio signal transmitted from the base station, it is determined that a coverage hole exists (step S43).
  • FIG. 9 is a sequence diagram illustrating an example of the RLF occurrence cause determination process in the wireless communication system according to the first embodiment of the present invention.
  • step S51 it is assumed that a communication connection is established between the wireless terminal device 202 and the wireless base station device 101A (step S51).
  • the wireless terminal device 202 starts a cell reselection procedure (Reestablishment Procedure) (step S53).
  • this cell reselection procedure for example, various types of information are exchanged between the wireless terminal device 202 and the wireless base station device 101B (step S54).
  • the cell reselection procedure includes transmission / reception of the RRC connection re-establishment request, the RRC connection re-establishment response, and the RRC connection re-establishment completion notification shown in FIG.
  • step S55 a communication connection is established between the wireless terminal device 202 and the wireless base station device 101B (step S55), and the wireless terminal device 202 transmits an RLF report to the wireless base station device 101B (step S56).
  • the wireless base station device 101B performs a process for determining the cause of occurrence of RLF (step S57).
  • the radio base station apparatus 101A may acquire the RLF report from the radio base station apparatus 101B and perform the process of determining the cause of RLF generation.
  • the determination process of the cause of RLF occurrence by the radio base station apparatus 101 will be described in detail.
  • FIG. 10 is a flowchart that defines a procedure for determining the cause of RLF occurrence by the radio base station apparatus according to the first embodiment of the present invention.
  • the coverage hole determination unit 16 of the radio base station apparatus 101 receives the RLF report from the radio terminal apparatus 202 via the measurement result acquisition unit 15 (step S58), and detects its own when the RLF occurs. It is confirmed from the RLF report whether the reception power of the radio signal from the radio base station apparatus 101 and the reception power of the radio signal from the neighboring base station are smaller than a predetermined threshold (step S59).
  • the coverage hole determination unit 16 has a case where the received power of the radio signal from the own radio base station apparatus 101 is smaller than a predetermined threshold and the received power of the radio signal from the neighboring base station is smaller than the predetermined threshold. (“YES" in step S59), it is determined that the cause of the RLF is that the wireless terminal device 202 has entered a coverage hole with low power (step S60).
  • the coverage hole determination unit 16 has a radio signal reception power from its own radio base station apparatus 101 larger than a predetermined threshold or a radio signal reception power from a neighboring base station is larger than a predetermined threshold.
  • a predetermined threshold a radio signal reception power from its own radio base station apparatus 101 larger than a predetermined threshold or a radio signal reception power from a neighboring base station is larger than a predetermined threshold.
  • these threshold values may be the same value or different values.
  • the coverage hole determination unit 16 determines that if the time required for establishing a communication connection is greater than a predetermined threshold, that is, if the time required until the wireless terminal device 202 establishes a communication connection after the occurrence of RLF is long ( If “YES” in step S61), it is determined that the cause of the RLF is that the wireless terminal device 202 has entered the coverage hole due to interference (step S62).
  • step S61 when the time required for establishing a communication connection is shorter than a predetermined threshold, that is, when the time required for the wireless terminal device 202 to establish a communication connection from the occurrence of RLF is short ( In step S61, “NO”), the cause of the RLF is that before the handover operation starts, or during the handover process, an RLF is generated from the own radio base station apparatus 101, such as an RLF occurs for the handover source radio base station apparatus. It is determined that the timing is not appropriate for the handover operation to the station (step S63).
  • the coverage hole determination unit 16 of the radio base station apparatus 101 detects the presence or absence of a coverage hole by the method as described above.
  • the radio base station apparatus 101 can also acquire information indicating the presence / absence of a coverage hole in advance before RLF occurs.
  • the radio terminal device 202 measures received power for radio signals transmitted from neighboring base stations, and stores information such as received power, communication quality, measurement time or measurement location for radio signals from neighboring base stations. . Then, when the wireless terminal device 202 receives the request from the mobile communication carrier via the wireless base station device 101, the wireless base station device 101 receives the stored information such as received power, communication quality, measurement time or measurement location. Send to.
  • the mobile communication carrier acquires information such as the reception power, communication quality, measurement time, or measurement location of the wireless signal measured by the wireless terminal device 202 from the wireless base station device 101, and based on the acquired information.
  • the presence / absence of a coverage hole can be determined, and the detection result can be set in the radio base station apparatus 101 (3GPP TS 37.320 V10.4.0 Radio measurement measurement collection M for minimization M O drive Test M (Overall description); Stage 22).
  • FIG. 11 shows an interval setting operation for performing the different frequency measurement operation by the different frequency measurement control unit of the radio base station apparatus according to the first embodiment of the present invention.
  • 12 is a flowchart for explaining the flow
  • FIGS. 12A and 12B are diagrams illustrating intervals at which the different frequency measurement operation set by the setting operation shown in FIG. 11 is performed.
  • coverage area determination unit 17 of radio base station apparatus 101 which is the radio base station apparatus according to the first embodiment of the present invention receives, for example, an RLF notification acquired from neighboring base station 101B. Based on this, it is determined whether or not the coverage area satisfies a predetermined condition (step S71).
  • the different frequency measurement control unit 18 sets an interval for performing the different frequency measurement operation based on the determination result determined in step S71.
  • the different frequency measurement control unit 18 sets the interval L1 for performing the different frequency measurement operation to be longer as shown in FIG. (Step S72).
  • the different frequency measurement control unit 18 sets the interval for performing the different frequency measurement operation from L1 as shown in FIG. A short L2 is set (step S73).
  • the different frequency measurement control unit 18 transmits information indicating the interval for performing the different frequency measurement operation set in step S72 or step S73 to the wireless terminal device 202 (step S74).
  • wireless terminal apparatus 202 performs different frequency measurement operation
  • FIG. 13 shows different frequency measurement by the different frequency measurement control unit of the radio base station apparatus according to the first embodiment of the present invention.
  • FIG. 15 is a flowchart for explaining a flow of a setting operation for determining whether or not to execute an operation, and FIGS. 14A and 14B show timings at which the different frequency measurement operation set by the setting operation shown in FIG. 13 is executed.
  • FIG. 14A and 14B show timings at which the different frequency measurement operation set by the setting operation shown in FIG. 13 is executed.
  • coverage area determination unit 17 of radio base station apparatus 101 that is the radio base station apparatus according to the first embodiment of the present invention is based on, for example, an RLF notification acquired from a neighboring base station. Then, it is determined whether or not the coverage area satisfies a predetermined condition (step S81).
  • the different frequency measurement control unit 18 determines whether or not to execute the different frequency measurement operation in the periodically provided different frequency measurement period based on the determination result determined in step S81.
  • the different frequency measurement control unit 18 performs two different frequency measurement periods (Gap) as shown in FIG. Of these, settings are made so that the different frequency measurement operation by the wireless terminal device 202 is executed in one different frequency measurement period and the different frequency measurement operation is not executed in the remaining one different frequency measurement period. That is, when the interval (Gap Repetition Length) of the different frequency measurement period is defined in advance as 80 ms, the different frequency measurement control unit 18 sets 160 ms as the interval L3 at which the different frequency measurement operation is performed (step S82). .
  • the different frequency measurement control unit 18 performs the wireless terminal device at every different frequency measurement period as shown in FIG. 14B. It sets so that the different frequency measurement operation
  • the different frequency measurement control unit 18 transmits information indicating the interval at which the different frequency measurement operation set in step S82 or step S83 is performed to the wireless terminal device 202 (step S84).
  • wireless terminal apparatus 202 performs different frequency measurement operation
  • the number of small base stations such as femto base stations and pico base stations has been increasing.
  • the change in the received power is abrupt near the radio base station device, and the change in the received power at the cell edge of the cell formed by the radio base station is a femto base station or a pico base station rather than a macro base station.
  • the smaller base station is larger. For this reason, with the increase in the number of small base stations installed, the handover operation of the wireless terminal device is likely to occur.
  • the frequency of a radio signal used between a radio base station apparatus (hereinafter also referred to as a serving base station) that establishes a communication connection with the radio terminal apparatus and the radio terminal apparatus, and other than the serving base station
  • the frequency of the radio signal transmitted from the peripheral base station that is the radio base station apparatus may be different.
  • the radio terminal device is different from the frequency of the radio signal used between itself and the serving base station because an appropriate radio base station device is selected as a communication connection destination.
  • the frequency radio signal is intermittently measured, and the measurement result is transmitted to the serving base station (Non-patent Document 2 (3GPP TS 36.133 V10.4.0)).
  • the different frequency measurement control unit 18 sets the interval at which the different frequency measurement operation is performed by the radio terminal apparatus 202 to the radio terminal apparatus 202.
  • the coverage area determination unit 17 includes, among its own radio base station apparatus and peripheral base stations other than its own radio base station apparatus, the own radio base station apparatus and the radio terminal apparatus 202.
  • a coverage area which is an area formed by the same frequency peripheral base station using the same frequency as the frequency of the wireless signal transmitted / received between the wireless terminal device 202 and the wireless terminal device 202 can communicate with the wireless base station device. It is determined whether or not a predetermined condition is satisfied. And the different frequency measurement control part 18 changes the said space
  • the measurement operation of the radio signal transmitted from the neighboring base station is configured by appropriately setting the interval for performing the different frequency measurement operation by the radio terminal device 202 depending on whether or not the coverage area satisfies the predetermined condition. Therefore, an increase in power consumption in the wireless terminal device 202 can be suppressed.
  • the different frequency measurement control unit 18 sets the interval longer when the coverage area satisfies a predetermined condition.
  • the power consumption of the wireless terminal device 202 can be suppressed by reducing the number of times the wireless terminal device 202 performs the different frequency measurement operation.
  • the coverage hole determination unit 16 may cause a disconnection of the communication connection between the radio terminal apparatus 202 and the radio base station apparatus. It is determined whether or not there is interference between radio signals transmitted by the apparatus. Further, when the coverage area determination unit 17 determines that the cause of the disconnection of the communication connection in the coverage area is interference between radio signals by the coverage hole determination unit 16, the coverage area does not satisfy the predetermined condition. to decide.
  • the coverage hole determination unit 16 performs measurement indicating the measurement result of the received power in the radio terminal apparatus 202 of the radio signal transmitted from the radio base station apparatus.
  • a result notification is acquired, and based on the acquired measurement result notification, it is determined whether or not the reception quality at the wireless terminal device 202 of the wireless signal transmitted from the same frequency peripheral base station satisfies a predetermined condition.
  • the coverage area determination unit 17 determines that the reception quality does not satisfy the predetermined condition
  • the coverage area determination unit 16 determines that the coverage area does not satisfy the predetermined condition.
  • the reception quality of the radio signal transmitted from the base station around the same frequency in the radio terminal device 202 is not sufficient, and the different frequency measurement operation is high in a situation where the radio link is likely to be disconnected. Since it can be set to be performed at a frequency, the occurrence of a radio link disconnection can be prevented, and communication can be stabilized.
  • the coverage hole determining unit 16 acquires a measurement result notification transmitted from the peripheral base station, and the same frequency peripheral base station is included in the acquired measurement result notification.
  • the measurement result of the reception power of the wireless signal transmitted from the station does not include the measurement result of the reception power of the wireless signal transmitted from the station or the wireless signal transmitted from the same frequency peripheral base station included in the measurement result notification Does not satisfy the predetermined condition, it is determined that the reception quality does not satisfy the predetermined condition.
  • the reception quality in the radio terminal device 202 is With the configuration for determining whether or not the predetermined condition is satisfied, it is possible to accurately detect the situation where the reception quality does not satisfy the predetermined condition, and to appropriately set the interval of the different frequency measurement operation.
  • the coverage area determination unit 17 is a local base station that is its own radio base station apparatus and a radio base station apparatus other than its own radio base station apparatus An area formed by the same frequency peripheral base station using the same frequency as the frequency of the radio signal transmitted and received between the own radio base station apparatus and the radio terminal apparatus 202, It is determined whether or not a coverage area, which is an area where apparatus 202 can communicate with a radio base station apparatus, satisfies a predetermined condition. Further, the different frequency measurement control unit 18 instructs the wireless terminal device 202 whether or not to measure a radio signal in the different frequency measurement period based on whether or not the coverage area satisfies a predetermined condition.
  • FIG. 15 is a diagram illustrating a configuration of a control unit in the radio base station apparatus according to the second embodiment of the present invention.
  • control section 98 of radio base station apparatus 101 includes handover request section 11, handover instruction section 12, measurement result acquisition section 15, different frequency A measurement control unit 18 (different frequency measurement interval setting unit and different frequency measurement instruction unit) and a terminal position determination unit 20 are included.
  • the measurement result acquisition unit 15 acquires a measurement result notification indicating the measurement result of the received power of the radio signal in the wireless terminal device 202, and communicates between the wireless base station device 101 and the wireless terminal device 202 from the acquired measurement result notification. Quality is obtained, and the communication quality is notified to the handover request unit 11, the handover instruction unit 12, and the terminal location determination unit 20.
  • the terminal location determination unit 20 determines whether or not the wireless terminal device 202 is located in a cell area that is predicted to be able to communicate with its own wireless base station device 101, that is, in a predetermined area of the cells CA and CB.
  • the predetermined area is, for example, near the end of the cell area.
  • the terminal position determination unit 20 acquires the measurement result notification from the measurement result acquisition unit 15, and the reception power of the radio signal transmitted from its own radio base station apparatus 101 indicated by the measurement result notification is predetermined. If it is larger than the threshold value, it is determined that the wireless terminal device 202 is not located near the end of the cell area.
  • the terminal position determination unit 20 can also estimate the position of the wireless terminal device 202 by using another method.
  • the terminal position determination unit 20 can use GPS (Global Positioning System).
  • the terminal location determination unit 20 can use LPP (LTE Positioning Protocol) defined by 3GPP. That is, in the downlink LPP, first, three or more radio base station apparatuses transmit LPP dedicated signals. Next, the wireless terminal device 202 calculates a difference in reception timing of the signal from each wireless base station device, and notifies the wireless base station device 101 that has established communication connection with the wireless terminal device 202 of the calculation result. Next, the terminal location determination unit 20 of the radio base station apparatus 101 estimates the position of the radio terminal apparatus 202 based on the notified difference in reception timing, and determines whether the radio terminal apparatus 202 is located near the end of the cell area. Judge whether or not.
  • LPP LTE Positioning Protocol
  • radio terminal apparatus 202 transmits a signal dedicated to LPP to each radio base station.
  • each radio base station apparatus calculates the reception timing of the signal.
  • the host device of each radio base station apparatus acquires the reception timing calculated in each radio base station apparatus, and estimates the position of the radio terminal apparatus 202 based on these timing differences.
  • the terminal position determination unit 20 determines whether or not the wireless terminal device 202 is located near the end of the cell area based on the position of the wireless terminal device 202 estimated by the host device.
  • the terminal position judgment part 20 outputs the judgment result which shows whether the radio
  • the different frequency measurement control unit 18 makes a terminal capability inquiry to the wireless terminal device 202. Further, the different frequency measurement control unit 18 (different frequency measurement interval setting unit) is configured so that the radio terminal device 202 transmits and receives radio signals to and from its own radio base station device 101 and between itself and its own radio base station device 101. When a terminal capability response indicating that radio signals having a frequency different from the frequency of the radio signal used in the radio signal cannot be received in parallel is received from the radio terminal device 202, a different frequency measurement operation may be performed. It is decided to provide a possible different frequency measurement period, for example, an interval at which the different frequency measurement operation is performed is set.
  • the wireless terminal device 202 when the wireless terminal device 202 is located near the center of the serving cell formed by the wireless base station device that has established communication connection with itself, the wireless terminal device 202 is located near the end of the serving cell. Compared to the above, it is unlikely that RLF will occur in the radio base station apparatus, and it is not necessary to perform the different frequency measurement operation by the radio terminal apparatus 202 at a high frequency.
  • the different frequency measurement control unit 18 receives the determination result indicating that the wireless terminal device 202 is not located in a predetermined area of the cell area, that is, near the end of the cell area, from the terminal position determination unit 20. Set a longer interval for frequency measurement operation. Then, the different frequency measurement control unit 18 transmits the set measurement parameter to the wireless terminal device 202.
  • the different frequency measurement control unit 18 can perform different frequency measurement operation based on whether or not the wireless terminal device 202 is located in a predetermined area of the cell area. In the period, it is also possible to determine whether or not to perform the different frequency measurement operation and to instruct the wireless terminal device 202 of the determination content.
  • FIG. 16 is a diagram illustrating an interval setting operation for performing the different frequency measurement operation by the different frequency measurement control unit of the radio base station apparatus according to the second embodiment of the present invention. It is a flowchart explaining a flow.
  • terminal location determination section 20 of radio base station apparatus 101 is based on, for example, a measurement result notification of radio signal reception power in radio terminal apparatus 202. Then, it is determined whether or not the wireless terminal device 202 is located in a predetermined area of the cells CA and CB, that is, near the ends of the cells CA and CB (step S91).
  • the different frequency measurement control unit 18 sets an interval for performing the different frequency measurement operation based on the determination result determined in step S91.
  • the different frequency measurement control unit 18 of the radio base station apparatus 101 performs the different frequency measurement operation when the radio terminal apparatus 202 is not located near the ends of the cells CA and CB ("No" in step S91). Is set longer (see FIG. 12A) (step S92).
  • the different frequency measurement control unit 18 sets L2 shorter than L1 as an interval for performing the different frequency measurement operation. Setting is performed (see FIG. 12B) (step S93).
  • the different frequency measurement control unit 18 transmits information indicating an interval for performing the different frequency measurement operation set in step S92 or step S93 to the wireless terminal device 202.
  • wireless terminal apparatus 202 performs different frequency measurement operation
  • FIG. 17 shows different frequency measurement by the different frequency measurement control unit of the radio base station apparatus according to the second embodiment of the present invention. It is a flowchart explaining the flow of determination operation
  • terminal position determination unit 20 of radio base station apparatus 101 is based on, for example, a measurement result notification of radio signal reception power in radio terminal apparatus 202. Then, it is determined whether or not the wireless terminal device 202 is located in a predetermined area of the cells CA and CB, that is, near the ends of the cells CA and CB (step S111).
  • the different frequency measurement control unit 18 determines whether or not to execute the different frequency measurement operation in the periodically provided different frequency measurement period based on the determination result determined in step S111.
  • the different frequency measurement control unit 18 of the radio base station apparatus 101 when the radio terminal apparatus 202 is not located near the ends of the cells CA and CB (“No” in step S111), The different frequency measurement operation by the wireless terminal device 202 is executed in one different frequency measurement period in the different frequency measurement period (Gap), and the different frequency measurement operation is not executed in the remaining one different frequency measurement period.
  • the different frequency measurement operation by the wireless terminal device 202 is executed in one different frequency measurement period in the different frequency measurement period (Gap), and the different frequency measurement operation is not executed in the remaining one different frequency measurement period.
  • the different frequency measurement control unit 18 sets 160 ms as the interval L3 at which the different frequency measurement operation is performed (FIG. 14 ( a) Reference) (step S112).
  • the different frequency measurement control unit 18 performs the different frequency measurement by the wireless terminal device 202 every different frequency measurement period. Set the action to be executed. That is, when the interval of the different frequency measurement period is defined in advance as 80 ms, the different frequency measurement control unit 18 sets 80 ms shorter than L3 as the interval L4 at which the different frequency measurement operation is executed (FIG. 14B). (Refer to step S113).
  • the different frequency measurement control unit 18 transmits information indicating the interval at which the different frequency measurement operation set in step S112 or step S113 is performed to the wireless terminal device 202 (step S114).
  • wireless terminal apparatus 202 performs different frequency measurement operation
  • the frequency at which the different frequency measurement control unit 18 performs the different frequency measurement operation by the radio terminal apparatus 202 is set to the radio terminal apparatus 202.
  • the terminal location determination unit 20 determines whether or not the wireless terminal device 202 is located in a predetermined area among cell areas in which the wireless terminal device 202 is predicted to be able to communicate with its own wireless base station device.
  • the different frequency measurement control part 18 changes the length of the said space
  • the wireless terminal device is transmitted from the neighboring base stations with a configuration in which the interval for performing the different frequency measurement operation by the wireless terminal device is appropriately set depending on whether or not the wireless terminal device is located in a predetermined area of the cell area.
  • the wireless signal measurement operation an increase in power consumption in the wireless terminal device can be suppressed.
  • the predetermined area is near the end of the cell area
  • the different frequency measurement control unit 18 includes the radio terminal apparatus 202 near the end of the cell area. When not positioned, the interval is set longer.
  • the measurement result acquisition unit 15 acquires the measurement result by the radio terminal apparatus 202 of the received power of the radio signal transmitted by itself. Also, the terminal position determination unit 20 determines that the wireless terminal device 202 is not located in the predetermined area when the received power indicated by the measurement result is larger than the predetermined threshold.
  • a third embodiment of the present invention will be described.
  • the different frequency measurement control unit 18 of the radio base station apparatus 101 sets measurement parameters in the different frequency measurement operation based on whether or not the coverage area satisfies a predetermined condition. did.
  • the different frequency measurement control unit 18 of the radio base station apparatus 101 further determines the position of the radio terminal apparatus 202 when the coverage area does not satisfy the predetermined condition. The case where the measurement parameter in the different frequency measurement operation is set based on the determination result will be described.
  • FIG. 18 is a diagram illustrating a configuration of a control unit in the radio base station apparatus according to the third embodiment of the present invention.
  • control section 98 of radio base station apparatus 101 includes handover request section 11, handover instruction section 12, measurement result acquisition section 15, coverage hole. It includes a determination unit 16, a coverage area determination unit 17, a different frequency measurement control unit 18 (different frequency measurement interval setting unit, different frequency measurement instruction unit), and a terminal position determination unit 20.
  • the coverage hole determination unit 16 causes interference between wireless signals transmitted by a plurality of wireless base station devices. It is determined whether or not there is a coverage hole due to interference.
  • the coverage hole determination unit 16 acquires the measurement result notification from the measurement result acquisition unit 15 and, based on the acquired measurement result notification, of its own radio base station apparatus 101 and its own base station The reception quality at the wireless terminal device 202 of the wireless signal transmitted from the wireless base station device using the wireless signal having the same frequency as the wireless signal used between the device 101 and the wireless terminal device 202 does not satisfy the predetermined condition. It is determined whether or not there is a coverage hole due to low power that cannot obtain sufficient reception quality in the area, that is, the wireless terminal device 202. Then, the coverage hole determination unit 16 outputs the determination result to the coverage area determination unit 17.
  • the coverage area determination unit 17 acquires a determination result indicating whether a coverage hole exists from the coverage hole determination unit 16, and determines whether the coverage area satisfies a predetermined condition based on the acquired determination result.
  • the coverage area determination unit 17 determines that the coverage area satisfies a predetermined condition and outputs the determination result to the different frequency measurement control unit 18. .
  • the coverage area determination unit 17 determines that the coverage area does not satisfy the predetermined condition, and outputs the determination result to the terminal position determination unit 20.
  • the terminal position determination unit 20 acquires a determination result indicating that the coverage area does not satisfy the predetermined condition from the coverage area determination unit 17, the terminal position determination unit 20 acquires the measurement result notification of the reception power of the radio signal in the wireless terminal device 202. Whether the wireless terminal device 202 is predicted to be communicable with its own wireless base station device 101 based on the measurement result notification, that is, whether it is located in a predetermined area of the cells CA and CB. Judging. Then, the terminal position determination unit 20 outputs a determination result indicating whether or not the wireless terminal device 202 is located in a predetermined area of the cells CA and CB, that is, near the end of the cell area, to the different frequency measurement control unit 18.
  • the different frequency measurement control unit 18 makes a terminal capability inquiry to the wireless terminal device 202. Further, the different frequency measurement control unit 18 (different frequency measurement interval setting unit) is configured so that the radio terminal device 202 transmits and receives radio signals to and from its own radio base station device 101 and between itself and its own radio base station device 101. When a terminal capability response indicating that radio signals having a frequency different from the frequency of the radio signal used in the radio signal cannot be received in parallel is received from the radio terminal device 202, a different frequency measurement operation may be performed. It is decided to provide a possible different frequency measurement period, for example, an interval at which the different frequency measurement operation is performed is set.
  • the different frequency measurement control unit 18 sets a long interval for performing the different frequency measurement operation.
  • the measurement control unit 18 sets the interval at which the different frequency measurement operation is performed long as described above.
  • the different frequency measurement control unit 18 sets the interval at which the different frequency measurement operation is performed to be short. Then, the different frequency measurement control unit 18 transmits the set measurement parameter to the wireless terminal device 202.
  • FIG. 19 is a flowchart for explaining a flow of an interval setting operation for performing different frequency measurement operation by the different frequency measurement control unit of the radio base station apparatus according to the third embodiment of the present invention.
  • coverage area determining section 17 of radio base station apparatus 101 sets a predetermined coverage area based on, for example, an RLF notification acquired from a neighboring base station. It is determined whether or not the condition is satisfied (step S121).
  • the terminal position determination unit 20 determines whether the wireless terminal device 202 is located in the predetermined area of the cell area (step S122). ).
  • the different frequency measurement control unit 18 performs an interval for performing the different frequency measurement operation. Is set short (step S123).
  • the different frequency measurement control unit 18 sets a longer interval for performing the different frequency measurement operation. Moreover, even if the coverage area does not satisfy the predetermined condition (“No” in step S121), the different frequency measurement control unit 18 causes the terminal position determination unit 20 to change the wireless terminal device 202 to a predetermined area of the cell area. Similarly, when it is determined that the position is not located (“No” in step S122), the interval for performing the different frequency measurement operation is set longer (step S124).
  • the different frequency measurement control unit 18 transmits information indicating the interval at which the different frequency measurement operation set in step S123 or step S124 is performed to the wireless terminal device 202 (step S125).
  • wireless terminal apparatus 202 performs different frequency measurement operation
  • the different frequency measurement control unit 18 is different from the different frequency measurement control unit 18 of the radio base station apparatus according to the first embodiment of the present invention and the radio base station apparatus according to the second embodiment of the present invention. Similarly to the frequency measurement control unit 18, it is possible to set whether or not to execute the different frequency measurement operation in the different frequency measurement period in which the different frequency measurement operation can be performed.
  • the terminal location determination unit 20 includes the cell areas that are predicted that the radio terminal apparatus 202 can communicate with its own radio base station apparatus. It is determined whether or not the wireless terminal device is located in the predetermined area. Moreover, even if the coverage area does not satisfy the predetermined condition, the different frequency measurement control unit 18 determines that the wireless terminal device 202 is not located in the predetermined area by the terminal position determination unit 20. Set a longer interval.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention se rapporte : à un dispositif formant station de base sans fil ; à un procédé de contrôle de communication ; et à un programme de contrôle de communication. Le dispositif, le procédé et le programme selon l'invention sont aptes à supprimer une augmentation de la consommation de puissance par un dispositif formant terminal sans fil, quand une mesure de signaux sans fil qui sont transmis à partir d'une station de base périphérique est exécutée. Le dispositif formant station de base sans fil selon l'invention comprend : un module de contrôle de mesure de fréquence différente (18) qui définit les intervalles auxquels une mesure de fréquence différente doit être exécutée par le dispositif formant terminal sans fil (202) ; et un module de détermination de zone de couverture (17) qui détermine si une zone de couverture remplit, ou non, des conditions prescrites. Ladite zone de couverture est une zone formée par le dispositif formant station de base sans fil et par une station de base périphérique de même fréquence, parmi les dispositifs formant stations de base périphériques, qui utilise la même fréquence que la fréquence qui est utilisée pour des signaux sans fil qui sont transmis et reçus entre le dispositif formant station de base sans fil et le dispositif formant terminal sans fil (202). Par ailleurs, ladite zone de couverture est une zone dans laquelle le dispositif formant terminal sans fil (202) peut communiquer avec le dispositif formant station de base sans fil. Le module de contrôle de mesure de fréquence différente (18) modifie lesdits intervalles sur la base du fait que la zone de couverture remplit, ou non, les conditions prescrites.
PCT/JP2013/067242 2012-06-26 2013-06-24 Dispositif formant station de base sans fil, procédé de contrôle de communication, et programme de contrôle de communication WO2014002946A1 (fr)

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JP2012142895A JP6040588B2 (ja) 2012-06-26 2012-06-26 無線基地局装置、通信制御方法および通信制御プログラム
JP2012-142895 2012-06-26

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JP6726628B2 (ja) * 2017-01-24 2020-07-22 株式会社Ｋｄｄｉ総合研究所 制御装置、通信装置、制御方法、及びプログラム
WO2020196124A1 (fr) 2019-03-25 2020-10-01 京セラ株式会社 Procédé de commande de transfert intercellulaire

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JP2014007633A (ja) 2014-01-16

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