JP2013201632A - Random access control device, radio base station device, management device, and random access control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a better communication system through proper configuration of a random access signal that is transmitted and received for adjusting the timing of transmission from a radio base station device to a radio terminal device before the communication connection is established between the radio terminal device and the radio base station device.SOLUTION: A random access control device 101 comprises: a random access signal selection section 12 for selecting one or more types of random access signals available for a radio terminal device 202 from multiple types of random access signals; a terminal mobile speed acquisition section 14 for acquiring mobile speed data of one or more radio terminal devices 202; and a selected range limit section 11 for limiting, on the basis of the mobility speed data, the range of random access signals that can be selected by the random access signal selection section 12.

Description

  The present invention relates to a random access control device, a radio base station device, a management device, and a random access control program, and in particular, a random access control device, a radio base station device, a management device, and a random access control for setting a random access signal. Regarding the program.

  Conventionally, in a mobile communication system, 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.

  In recent years, due to a dramatic increase in the number of subscribers of mobile communication services and an increase in the amount of communication traffic due to data communication, subscribers and communication traffic are distributed by forming smaller radius cells, and a certain level of communication It is desirable to provide speed to users in a stable manner. In addition, in order to deal with dead zones associated with the increase in the number of buildings, it is desired to install radio base station devices on the corporate floor and in ordinary households.

  Together with these demands, the processing capability of various devices used in the radio base station apparatus has been dramatically improved, and the miniaturization of the radio base station apparatus has progressed. Collecting.

  Since the radius of the femto cell (Femto Cell) formed by this small base station (hereinafter also referred to as a femto base station) is as small as about 10 meters, the femto base station is the macro cell (Macro Cell) formed by the macro base station. It may be used in places such as indoors and underground malls where it is out of service area and it is difficult to install macro base stations.

  In addition, since many femto base stations are installed in a specific area, it is difficult to connect the femto base stations directly to the core network. For this reason, it is conceivable that a large number of femto base stations installed in a specific area are once connected to a gateway device such as a HeNB-GW, and the femto base station and the core network are connected via the HeNB-GW.

  In addition to the femto base station, a pico base station that forms a pico cell having a radius of 100 to 200 meters, for example, has been developed based on a macro base station.

  Here, before the wireless terminal device establishes a communication connection with the wireless base station device, RACH (Random Access Channel) transmitted and received between the wireless terminal device and the wireless base station device is 3GPP TS 36.211 V10.4.0 2011.12 (Non-Patent Document 1). The radio base station apparatus adjusts the transmission timing from the radio terminal apparatus to itself using RACH, thereby enabling good communication between itself and the radio terminal apparatus.

3GPP TS 36.211 V10.4.0 2011.12

  A femto base station or a pico base station is often arranged unplanned compared to a macro base station, and activation and deactivation may be dynamically controlled according to increase or decrease of communication load in a communication system. . For this reason, optimal parameter settings regarding RACH, such as transmission timing and transmission power, are not constant and may change.

  If the RACH parameter setting is not appropriate, the wireless terminal device cannot establish a communication connection with the wireless base station device, a delay occurs in establishing the communication connection, and a delay occurs in the handover operation of the wireless terminal device Various problems arise.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to transmit and receive data from a radio base station apparatus that is transmitted and received prior to establishing a communication connection between the radio terminal apparatus and the radio base station apparatus. Random access control apparatus, radio base station apparatus, management apparatus, and random access control capable of constructing good communication system by appropriately setting random access signal for adjusting transmission timing to terminal apparatus Is to provide a program.

  (1) In order to solve the above-described problem, a random access control device according to an aspect of the present invention is configured to adjust the transmission timing from a wireless terminal device to a target base station that is a target wireless base station device. A random access signal detected by a base station and transmitted from the wireless terminal device prior to the wireless terminal device establishing a communication connection with the target base station, from among a plurality of types of random access signals, A random access signal selection unit for selecting one or a plurality of types of random access signals that can be used by the wireless terminal device; a terminal moving speed acquisition unit for acquiring the moving speed of one or more wireless terminal devices; Based on the moving speed, the random access signal selection unit limits the selectable range of the random access signal. And a fit of the selection restriction unit.

  With such a configuration, it is possible to set an optimal random access signal selectable range according to the moving speed of the wireless terminal device. Therefore, a good communication system can be constructed by appropriately setting a random access signal. In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  (2) Preferably, the random access control device further includes a cell radius information acquisition unit for acquiring cell radius information capable of evaluating a cell radius of the target base station, and the selection range restriction unit includes The restriction is provided based on the moving speed and the cell radius information.

  With such a configuration, it is possible to provide a more appropriate restriction on the selectable range of the random access signal based on the cell radius information of the target base station in addition to the moving speed of the wireless terminal device.

  (3) A random access control apparatus according to another aspect of the present invention includes a terminal moving speed acquisition unit for acquiring the moving speed of one or a plurality of radio terminal apparatuses, and a target base that is a target radio base station apparatus. A cell radius information acquisition unit for acquiring cell radius information capable of evaluating a cell radius of the station, and the radio detected by the target base station to adjust a transmission timing from a radio terminal device to the target base station Based on the moving speed and the cell radius information, the wireless terminal device can use a random access signal transmitted from the wireless terminal device before the terminal device establishes a communication connection with the target base station. A random access signal selection unit for selecting one or a plurality of types of random access signals.

  With such a configuration, it is possible to select an optimal random access signal according to the moving speed of the wireless terminal device and the cell radius of the target base station. Therefore, a good communication system can be constructed by appropriately setting a random access signal. In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  (4) Preferably, when the moving speed is larger than a predetermined threshold, the target base obtained from the random access signal based on the cell radius information when the moving speed is higher than a predetermined threshold. One or a plurality of types of random access signals corresponding to the cell radius of the station are selected.

  In this way, particularly when the moving speed of the wireless terminal device is large, the configuration for selecting the random access signal corresponding to the cell radius of the target base station provides a limit on the selectable range of the random access signal in an appropriate situation, Further, an appropriate limit can be set according to the cell radius.

  (5) More preferably, the random access control device further includes a type of the random access signal and a maximum radius of the cell formed by the radio base station device that can detect the random access signal in the radio base station device. The random access signal selection unit is configured to store a plurality of types of the random access based on the information when the moving speed is greater than a predetermined threshold. One or a plurality of types of random access signals corresponding to the maximum radius that is larger than the cell radius of the target base station and is closest to the cell radius of the target base station, obtained from the cell radius information. select.

  Thus, a radio base station apparatus that forms a cell radius larger than the target base station by selecting a random access signal corresponding to the maximum radius closest to the cell radius of the target base station among the maximum radii in the above information It is possible to reduce the possibility that the selectable range of the random access signal is lost or limited.

  (6) In order to solve the above problem, a radio base station apparatus according to an aspect of the present invention includes the random access control apparatus according to (1) or (3).

  With such a configuration, random access signals can be set in each radio base station apparatus in the radio communication system, so that the processing load for setting the random access signals can be distributed.

  (7) Preferably, the terminal moving speed acquisition unit responds to a handover request from the other radio base station apparatus when a handover operation of the radio terminal apparatus from another radio base station apparatus to the target base station is performed. The moving speed of the included wireless terminal device is acquired.

  In this way, by obtaining the moving speed of the wireless terminal device from the handover source wireless base station device, for example, accurate statistics of the moving speed of the wireless terminal device including the moving speed in other wireless base station devices can be obtained. Can be acquired.

  (8) In order to solve the above-described problem, a management apparatus according to an aspect of the present invention manages one or a plurality of radio base station apparatuses, and the random access control apparatus according to (1) or (3) above. Prepare.

  With such a configuration, since the setting of the random access signal of each radio base station apparatus in the radio communication system can be performed collectively in the management apparatus, the setting related to the random access signal can be performed more efficiently.

  (9) In order to solve the above-described problem, a random access control program according to an aspect of the present invention is a random access control program used in a random access control device, and the target wireless base station is connected to a computer from a wireless terminal device. Detected by the target base station to adjust the transmission timing to the target base station, which is a station device, transmitted from the wireless terminal device prior to the wireless terminal device establishing a communication connection with the target base station A step of selecting one or a plurality of types of random access signals that can be used by the wireless terminal device from a plurality of types of the random access signals, and a moving speed of the one or more wireless terminal devices Based on the step, a step is provided to limit the selectable range of the random access signal. Is a program for executing and.

  With such a configuration, it is possible to set an optimal random access signal selectable range according to the moving speed of the wireless terminal device. Therefore, a good communication system can be constructed by appropriately setting a random access signal. In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  (10) A random access control program according to another aspect of the present invention is a random access control program used in a random access control device, and the step of acquiring a moving speed of one or a plurality of wireless terminal devices in a computer Obtaining cell radius information capable of evaluating the cell radius of the target base station that is the target radio base station device, and adjusting the transmission timing from the radio terminal device to the target base station. The random access signal transmitted from the wireless terminal device prior to the wireless terminal device establishing a communication connection with the target base station is detected based on the moving speed and the cell radius information. Step of selecting one or more types of random access signals that can be used by the wireless terminal device Is a program for executing the.

  With such a configuration, it is possible to select an optimal random access signal according to the moving speed of the wireless terminal device and the cell radius of the target base station. Therefore, a good communication system can be constructed by appropriately setting a random access signal. In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  According to the present invention, a random access signal for adjusting transmission timing from a radio base station apparatus to a radio terminal apparatus, which is transmitted / received prior to establishing a communication connection between the radio terminal apparatus and the radio base station apparatus, is transmitted. A suitable communication system can be constructed by appropriately performing the setting.

It is a figure which shows the structure of the radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows the structure of the radio base station apparatus which concerns on embodiment of this invention. It is a figure which shows the random access sequence in the radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows the structure of the control part in the radio base station apparatus which concerns on embodiment of this invention. It is the flowchart which defined an example of the operation | movement procedure at the time of the radio base station apparatus which concerns on embodiment of this invention setting a RACH parameter. In the radio base station apparatus which concerns on embodiment of this invention, it is a figure which shows the relationship between the largest cell radius which can detect a preamble set and RACH preamble in case the high speed flag is asserted. It is a figure which shows an example of the acquisition method of the cell radius of the radio base station apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the acquisition method of the cell radius of the radio base station apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the sequence in which the radio base station apparatus which concerns on embodiment of this invention acquires the moving speed of a radio | wireless terminal apparatus from another radio base station apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  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. Based on this measurement result, movement of the wireless terminal device to the neighboring cells is started. Here, “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.

  Specifically, in addition to meaning handover, for example, an idle radio terminal device described in 3GPP TS 36.304 V10.3.0 2011.10. This means cell reselection for selecting a radio base station apparatus to be a communication partner based on the measurement result of the radio signal from.

  For example, when the wireless terminal device is communicating with the wireless base station device, the destination of the wireless terminal device is determined by the wireless base station device or a 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.

  In addition, 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 “idle state” of a wireless terminal device is a state in which a wireless base station device has selected a wireless base station device as a communication partner and is not communicating with the wireless base station device. In addition, the “state where communication is not performed” is a state where an operation for transmitting some information to the radio base station apparatus is not performed.

  Note that the definition of “Idle Mode” defined in 3GPP may be used as the definition of the “idle state” of the wireless terminal device.

  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 and can communicate with the wireless base station device. This means that communication is in progress.

  The femtocell and access mode are described in 3GPP (Third Generation Partnership Project) SPEC TS 22.22 as follows. That is, 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.

  Further, in the femtocell access mode, the femto base station in the closed access mode provides a service only to 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.

  Such a 3GPP definition may also be applied to the wireless communication system according to the embodiment of the present invention.

  Further, the following definitions can be applied together with or separately from the above definitions.

  The macro base station and the pico base station are wireless base station devices that are under the management of the operator and can communicate with the wireless base station device that has contracted with the operator. Further, it is considered that the macro base station and the pico base station are basically not turned off.

  A femto base station is a radio base station apparatus that is installed mainly in an individual or corporate building and may move or be turned off depending on the circumstances of the user.

  Further, the femto base station operates in one of open / hybrid / closed access modes. When the femto base station operates in the closed access mode, only registered members (terminals) can be connected. When operating in the closed access mode, the service is provided only to registered members. When operating in the hybrid mode, the service is provided to both registered members and unregistered members, that is, non-members. When operating in the open access mode, the same operation as that of the macro base station and the pico base station is performed.

[Basic configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a radio communication system according to an embodiment of the present invention.

  Referring to FIG. 1, a wireless communication system 301 is a mobile communication system that complies with, for example, LTE (Long Term Evolution) standardized by 3GPP (Third Generation Partnership Project), and includes femto base stations 101A, 101B, and 101C. A pico base station 101D, a macro base station 201, and a gateway device 203 are provided.

  Hereinafter, each of the femto base stations 101A, 101B, and 101C, the pico base station 101D, and the macro base station 201 may be referred to as a radio base station apparatus 101. In FIG. 1, one macro base station, one pico base station, and three femto base stations are representatively shown, but the combination and number thereof are not limited thereto.

  The femto base stations 101A, 101B, and 101C form femtocells FCA, FCB, and FCC having a radius of several tens of meters, for example. Further, the pico base station 101D forms a picocell PC having a radius of 100 meters to 200 meters. The macro base station 201 forms a macro cell MC having a radius of several kilometers, for example.

  The femto base stations 101A, 101B, and 101C are installed in places where it is difficult for the wireless terminal device 202 to receive radio signals from the macro base station 201 and the pico base station 101D, such as an underground mall, and are respectively located in the femtocells FCA, FCB, and FCC. It is possible to communicate with the wireless terminal device 202 by transmitting and receiving wireless signals to and from the existing wireless terminal device 202.

  The pico base station 101D can communicate with the radio terminal device 202 by transmitting and receiving radio signals to and from the radio terminal device 202 existing in the pico cell PC. The macro base station 201 can communicate with the wireless terminal device 202 by transmitting and receiving wireless signals to and from the wireless terminal device 202 existing in the macro cell MC.

  The gateway device 203 performs relay processing of various communication data transmitted between the femto base stations 101A, 101B, and 101C and the host device 205 in the core network 204.

  The host device 205 is, for example, an MME (Mobility Management Entity), and manages information on the entire wireless communication system 301. For example, the upper device 205 acquires and stores information on each radio base station device in the radio communication system 301.

  Here, the direction from the wireless terminal device 202 to the core network 204 is referred to as an uplink direction, and the direction from the core network 204 to the wireless terminal device 202 is referred to as a downlink direction.

  FIG. 2 is a diagram showing the configuration of the radio base station apparatus according to the embodiment of the present invention.

  Referring to FIG. 2, radio base station apparatus 101 includes antenna 91, circulator 92, radio reception unit 93, radio transmission unit 94, signal processing unit 95, and 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 Processor).

  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.

  Radio receiving section 93 converts the radio signal received from 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 received signal processing section 96.

  The received signal processing unit 96 performs signal processing such as despreading in the CDMA (Code Division Multiple Access) method on the digital signal received from the wireless receiving unit 93, and part or all of the digital signal after this signal processing is performed. 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 an OFDM (Orthogonal Frequency Division Multiplex) method on communication data obtained by converting communication data received from the core network side into a predetermined frame format or communication data generated by itself. The digital signal after the signal processing is output to the wireless transmission unit 94.

  The radio 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 radio signal, and outputs the radio signal to the circulator 92.

  The control unit 98 exchanges various information with each unit and the core network side in the radio base station apparatus 101.

  FIG. 3 is a diagram showing a random access sequence in the radio communication system according to the embodiment of the present invention.

  Referring to FIG. 3, first, radio base station apparatus 101, for example, the transmission timing and transmission frequency of a random access preamble (hereinafter also referred to as RACH preamble) described in Non-Patent Document 1, the number of usable RACH preambles. The transmission power of the RACH preamble is included in the broadcast information and transmitted to each wireless terminal device 202 (step S101).

  Next, based on the broadcast information received from the radio base station apparatus 101, the radio terminal apparatus 202 selects one of a plurality of types of RACH preambles designated by the radio base station apparatus 101 (Step S102). ), And transmits to the radio base station apparatus 101 (step S103).

  Next, the radio base station apparatus 101 detects the RACH preamble transmitted from the radio terminal apparatus 202, estimates the transmission timing shift of the radio terminal apparatus 202, and calculates a correction value for the transmission timing (step S104). ).

  Next, the radio base station apparatus 101 wirelessly transmits the calculated correction value, the detected RACH preamble number, a temporary C-RNTI (Cell Radio Network Temporary Identifier), and RACH control information indicating the timing at which the RACH message should be transmitted. It transmits to the terminal device 202 (step S105).

  Next, the wireless terminal device 202 corrects its own transmission timing based on the RACH control information received from the wireless base station device 101 (step S106).

  Next, the radio terminal apparatus 202 adds the provisional C to the RACH message including a CR-ID (content reference identifier) for detecting a RACH preamble collision with another radio terminal apparatus 202 in the radio base station apparatus 101. -Transmit to the radio base station apparatus 101 with RNTI. In transmitting this RACH message, for example, HARQ (Hybrid Automatic Repeat Request) is used (step S107).

  Next, the radio base station apparatus 101 receives the RACH message from the radio terminal apparatus 202, and processing according to the upper layer such as registration processing of the radio terminal apparatus 202 is executed (step S108).

  Next, the radio base station apparatus 101 transmits RACH response information including the CR-ID received from the radio terminal apparatus 202, the official C-RNTI, and the like to the radio terminal apparatus 202 (step S109).

  Through the processing as described above, the random access sequence between the wireless terminal device 202 and the wireless base station device 101 is completed.

[Task]
For example, in LTE, there are 838 RACH preambles in total, and the radio base station apparatus 101 selects 64 of these and causes the radio terminal apparatus 202 to use them.

  More specifically, the radio base station apparatus 101 determines 64 RACH preambles that can be used by the radio terminal apparatus 202 and informs each radio terminal apparatus 202 with broadcast information. Specifically, for example, the radio base station apparatus 101 notifies each radio terminal apparatus 202 only of the heads of 64 consecutive indexes called “Logical root sequence number”.

  These RACH preambles have different bit patterns. For example, when the radio terminal apparatus 202 moves at a high speed, there are a bit pattern in which the radio base station apparatus 101 has good detection characteristics and a bit pattern in which the radio terminal apparatus 202 does not.

  Here, when the radio base station apparatus 101 is installed, the movement speed tendency of the radio terminal apparatus 202 in the cell formed by the radio base station apparatus 101 is often unknown, and an optimal RACH preamble is selected. Is difficult.

  If a type of RACH preamble suitable for the moving speed of the wireless terminal device 202 is not used, the wireless terminal device 202 cannot establish a communication connection with the wireless base station device 101, and a delay occurs in establishing the communication connection. And various problems such as a delay in the handover operation of the wireless terminal device 202 occur.

  Therefore, in the wireless communication system according to the embodiment of the present invention, the above-described problem is solved by the following configuration and operation.

[Configuration and operation]
FIG. 4 is a diagram showing a configuration of a control unit in the radio base station apparatus according to the embodiment of the present invention.

  Referring to FIG. 4, control unit 98 includes a selection range restriction unit 11, a random access signal selection unit 12, a cell radius information acquisition unit 13, a terminal moving speed acquisition unit 14, and a storage unit 15.

  The random access signal selection unit 12 selects one or a plurality of types of random access signals that can be used by the wireless terminal device 202 from a plurality of types of random access signals.

  Here, the random access signal is, for example, a RACH preamble, and is detected by the radio base station apparatus 101 to adjust the transmission timing from the radio terminal apparatus 202 to the radio base station apparatus 101. The radio terminal apparatus 202 is a radio base station. This signal is transmitted from the wireless terminal device 202 prior to establishing a communication connection with the device 101.

  The cell radius information acquisition unit 13 acquires cell radius information that can evaluate the cell radius of the own radio base station apparatus 101.

  The terminal moving speed acquisition unit 14 acquires the moving speed of one or more wireless terminal devices 202.

  The random access signal selection unit 12 uses one or a plurality of types that the wireless terminal device 202 can use based on the moving speed acquired by the terminal moving speed acquisition unit 14 and the cell radius information acquired by the cell radius information acquisition unit 13. Select random access signal.

  That is, the selection range restriction unit 11 performs random access signal selection by the random access signal selection unit 12 based on the movement speed acquired by the terminal movement speed acquisition unit 14 and the cell radius information acquired by the cell radius information acquisition unit 13. Limit the selectable range.

  More specifically, the cell radius information acquisition unit 13 can evaluate the cell radius of the own radio base station apparatus 101 from the system information registered in the own radio base station apparatus 101 by the communication carrier, for example. Get information, for example, your own maximum transmit power. The cell radius information may be the cell radius value itself.

  The terminal moving speed acquisition unit 14 acquires the moving speed of the wireless terminal device 202 located in a cell formed by the own wireless base station device 101 (hereinafter also simply referred to as its own cell). Here, the moving speed of the wireless terminal device 202 means a physical moving speed of the wireless terminal device 202, for example, speed [km / h].

  The terminal moving speed acquisition unit 14 obtains the moving speed of the wireless terminal device 202 from the staying time of the wireless terminal device 202 in its own cell and the cell radius of its own wireless base station device 101, for example. Specifically, the moving speed can be obtained by calculating (cell radius / staying time).

  Further, the terminal moving speed acquisition unit 14 may obtain the moving speed of the wireless terminal device 202 from the position information of the wireless terminal device 202. For example, GPS (Global Positioning System) can be used.

  Alternatively, it is possible to use LPP (LTE Positioning Protocol) defined by 3GPP. That is, in downlink LPP, first, a signal dedicated to LPP is transmitted from three or more radio base station apparatuses. 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 of the calculation result. Next, the radio base station apparatus 101 estimates the position of the radio terminal apparatus 202 based on the notified reception timing difference.

  In uplink LPP, first, the wireless terminal device 202 transmits a signal dedicated to LPP. Next, each radio base station apparatus calculates the reception timing of the signal. Next, 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.

  Alternatively, the terminal moving speed acquisition unit 14 receives a moving speed report from the wireless terminal device 202. More specifically, the wireless terminal device 202 detects its own moving speed based on, for example, its own number of handovers or cell reselection times during a predetermined time. Then, the wireless terminal device 202 reports its movement speed to the wireless base station device 101.

  Alternatively, the terminal moving speed acquisition unit 14 acquires the moving speed of the wireless terminal device 202 from the wireless base station device 101 that is the handover source of the wireless terminal device 202, and so on. The moving speed of the device 202 is acquired.

  And the terminal moving speed acquisition part 14 takes the statistics of the moving speed of the some radio | wireless terminal apparatus 202 in an own cell, for example. Specifically, for example, the maximum moving speed of each wireless terminal device 202 may be used, or the average value of the moving speeds of each wireless terminal device 202 may be used.

  For example, in LTE, a preamble set (restricted set), that is, a RACH preamble set for a radio terminal apparatus 202 moving at high speed is prepared. In the radio communication system according to the embodiment of the present invention, the RACH preamble used by the radio terminal apparatus 202 is optimally set using, for example, this preamble set.

  Specifically, the selection range restriction unit 11 asserts a high speed flag when there are many wireless terminal devices 202 moving at high speed in its own cell as a result of statistics by the terminal movement speed acquisition unit 14. In this case, the random access signal selection unit 12 uses the preamble set for high speed movement.

[Detailed operation]
Next, the operation when the radio base station apparatus according to the embodiment of the present invention sets the RACH parameter will be described with reference to the drawings.

  The radio base station apparatus and the radio terminal apparatus in the radio communication system according to the embodiment of the present invention read 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. 5 is a flowchart defining an example of an operation procedure when the radio base station apparatus according to the embodiment of the present invention sets the RACH parameters.

  When the moving speed acquired by the terminal moving speed acquiring unit 14 is larger than a predetermined threshold, the random access signal selecting unit 12 is obtained from a plurality of types of random access signals based on the cell radius information. One or a plurality of types of random access signals corresponding to the cell radius of the radio base station apparatus 101 are selected.

  Specifically, referring to FIG. 5, first, the RACH preamble used by radio base station apparatus 101 is initialized. For example, the communication carrier sets the RACH preamble of the newly installed radio base station apparatus 101 (step S1).

  Next, in the control unit 98 of the radio base station apparatus 101, the random access signal selection unit 12 transmits broadcast information indicating the setting contents to each radio terminal apparatus 202 via the transmission signal processing unit 97. Thereby, the RACH preamble according to the setting content is transmitted / received between the radio base station apparatus 101 and the radio terminal apparatus 202 (step S2).

  Next, the terminal movement speed acquisition unit 14 takes statistics of the movement speed of the wireless terminal device 202 in its own cell. When the statistical value by the terminal movement speed acquisition unit 14 is larger than a predetermined threshold (YES in step S3), the selection range restriction unit 11 asserts a high speed flag, specifically, sets the high speed flag to “true”. (Step S4).

  Next, since the high speed flag is asserted, the random access signal selection unit 12 resets the preamble set according to its own cell radius (step S6).

  Then, the random access signal selection unit 12 transmits broadcast information indicating the setting content to each wireless terminal device 202. Thereby, the RACH preamble according to the setting content is transmitted / received between the radio base station apparatus 101 and the radio terminal apparatus 202 (step S2).

  FIG. 6 is a diagram illustrating a relationship between a preamble set and a maximum cell radius capable of detecting a RACH preamble when the high speed flag is asserted in the radio base station apparatus according to the embodiment of the present invention. . FIG. 6 shows a part of the contents described in 3GPP TSG RAN WG1 # 50bis R1-0774514 “Way Forward Proposal on PRACH Sequence Ordering”.

  The storage unit 15 illustrated in FIG. 4 is information indicating a correspondence relationship between the type of the random access signal and the maximum radius of the cell formed by the radio base station apparatus 101 at which the radio base station apparatus 101 can detect the random access signal. Remember.

  Specifically, referring to FIG. 6, in radio communication system 301, for example, when the high speed flag is asserted, the maximum cell radius that can be set, that is, the maximum detectable RACH preamble for each preamble set. The cell radius is determined.

  More specifically, the maximum cell radius that can be set increases as the RACH preamble number increases, and is the maximum for RACH preambles from 384th to 455th. As the number increases from 456, the maximum cell radius that can be set decreases.

  Specifically, for example, when the RACH preambles from No. 24 to No. 29 are used, the maximum cell radius that can be set is about 2.25 km, and can be set when the RACH preambles from No. 384 to 455 are used. The maximum cell radius is about 35.5 km, and RACH preambles from 0 to 23 and RACH preambles from 820 to 837 cannot be used when the high speed flag is asserted. That is, the RACH preambles Nos. 24 to 819 correspond to the above-described high-speed moving preamble set.

  For example, when the assumed cell radius is about 15 km, it is necessary to use RACH preambles from 168 to 455 or preambles from 456 to 707. If the assumed cell radius is less than 2.25 km, the 24th to 819th preambles need to be used.

  When the high speed flag is asserted, the random access signal selection unit 12 resets the RACH preamble in consideration of the cell radius of its own radio base station apparatus 101. For example, the random access signal selection unit 12 is larger than the cell radius of its own radio base station apparatus 101 obtained based on the cell radius information from a plurality of types of random access signals based on the information shown in FIG. A preamble set corresponding to the maximum cell radius closest to the cell radius of its own radio base station apparatus 101, that is, one or a plurality of types of random access signals is selected.

  Referring to FIG. 5 again, on the other hand, if the statistical value of the moving speed of wireless terminal apparatus 202 in its own cell is equal to or lower than the predetermined threshold (NO in step S3), selection range restriction unit 11 is high. Set the speed flag to “false”. Here, the random access signal selection unit 12 resets a preamble set that cannot be selected when the high speed flag is asserted in the previous evaluation of the statistical value, for example, when the high speed flag is asserted. (Step S5).

  Then, the random access signal selection unit 12 transmits broadcast information indicating the setting content to each wireless terminal device 202. Thereby, the RACH preamble according to the setting content is transmitted / received between the radio base station apparatus 101 and the radio terminal apparatus 202 (step S2).

  Here, as a method for the radio base station apparatus 101 to acquire its own cell radius, for example, external information of the radio base station apparatus 101, internal information of the radio base station apparatus 101 such as the system information described above, or neighboring cells From this measurement result, a method of acquiring the own cell radius is conceivable.

  FIG. 7 is a diagram illustrating an example of a cell radius acquisition method of the radio base station apparatus according to the embodiment of the present invention.

  Referring to FIG. 7, information related to a mobile communication service area is usually managed by a communication carrier. Therefore, the radio base station apparatus 101 acquires cell radius information from the communication carrier.

  Specifically, in the control unit 98 of the radio base station apparatus 101, the cell radius information acquisition unit 13 regularly accesses the server 206 of the communication carrier, and cell radius information of its own radio base station apparatus 101. To get.

  Alternatively, when the cell radius of the radio base station apparatus 101 is changed, the server 206 notifies the radio base station apparatus 101 of the changed cell radius.

  Alternatively, the cell radius information acquisition unit 13 acquires and stores information on the tilt angle of the transmission antenna of the radio base station apparatus 101 and the transmission power of the radio signal. Then, the cell radius information acquisition unit 13 periodically acquires information on the tilt angle and transmission power from the server 206, for example, and compares the information with the stored information. It is determined that the cell radius of base station apparatus 101 has been changed.

  FIG. 8 is a diagram illustrating an example of a cell radius acquisition method of the radio base station apparatus according to the embodiment of the present invention.

  Referring to FIG. 8, in signal processing unit 95 of radio base station apparatus 101, received signal processing unit 96 measures received power of a radio signal transmitted by a neighboring base station. The cell radius information acquisition unit 13 is a difference between the transmission power of the radio signal transmitted by the neighboring base station and the received power of the radio signal transmitted by the neighboring base station in the cell formed by the own radio base station apparatus 101. Based on the path loss, the inter-base station distance between its own radio base station apparatus 101 and neighboring base stations is estimated and stored.

  The cell radius information acquisition unit 13 periodically acquires the transmission power of the neighboring base stations and obtains the measurement results of the neighboring base stations by the reception signal processing unit 96 to obtain the path loss, and estimates the distance between the base stations. The cell radius information acquisition unit 13 compares the newly estimated inter-base station distance with the stored inter-base station distance, and determines that the cell radius has been changed if there is a change.

  Specifically, as shown in FIG. 8, when the cell radius is changed, when the femto base station 101F is newly installed in a state where the femto base stations 101A, 101B, and 101C are installed, For example, the transmission power of the femto base stations 101A, 101B, and 101C is changed by the communication carrier, and the path loss changes. As a result, the radii of the cells FCA, FCB, FCC of the femto base stations 101A, 101B, 101C are changed.

  FIG. 9 is a diagram illustrating an example of a sequence in which the wireless base station device according to the embodiment of the present invention acquires the moving speed of the wireless terminal device from another wireless base station device.

  The terminal moving speed acquisition unit 14 is included in the handover request from the other radio base station apparatus 101 when the handover operation of the radio terminal apparatus 202 from the other radio base station apparatus 101 to the own radio base station apparatus 101 is performed. The moving speed of the wireless terminal device 202 is acquired.

  Specifically, referring to FIG. 9, first, terminal A, which is wireless terminal apparatus 202, measures its own moving speed using the method described above (step S11).

  Next, terminal A reports its own moving speed to radio base station apparatus 101 that is the handover source, that is, the handover source base station that is the radio base station apparatus 101 with which it has established a communication connection (step S12). .

  Next, the handover source base station performs statistical processing of the movement speed of each past wireless terminal device 202 including the movement speed reported from the terminal A (step S13).

  Next, the handover source base station receives a measurement result notification indicating the measurement result of the received power of the radio signal transmitted from each radio base station apparatus 101 including itself from the terminal A, and based on the measurement result notification, It is determined whether or not the handover operation of terminal A is to be executed, and if it is determined that the handover operation is to be executed, a certain radio base station apparatus 101 is determined as a handover destination with reference to neighboring cell information (step S14). ).

  Next, the handover source base station transmits a handover request to the handover destination base station that is the radio base station apparatus 101 that is the handover destination of the terminal A. The handover source base station includes the moving speed of the terminal A in this handover request (step S15).

  Next, various information for establishing a communication connection between the terminal A and the handover destination base station is transmitted and received between the terminal A and the handover destination base station (step S16).

  Next, the handover destination base station performs statistical processing of the movement speed of each past wireless terminal device 202 including the movement speed of the terminal A indicated by the handover request received from the handover source base station (step S17).

  Next, as in the flowchart shown in FIG. 5, when the statistical value obtained by the statistical processing is larger than a predetermined threshold (YES in step S18), the handover destination base station asserts the high speed flag, and RACH Preamble setting processing is performed (step S19).

  By the way, a femto base station or a pico base station is often arranged unplanned compared to a macro base station, and the start and stop are dynamically controlled according to increase or decrease of communication load in a communication system. There is also. For this reason, optimal parameter settings regarding RACH, such as transmission timing and transmission power, are not constant and may change. If the RACH parameter setting is not appropriate, the wireless terminal device cannot establish a communication connection with the wireless base station device, a delay occurs in establishing the communication connection, and a delay occurs in the handover operation of the wireless terminal device Various problems arise.

  In addition, if the operator sets the RACH parameters for each femto base station when installing the femto base station, considerable work and cost are required. Further, every time a femto base station is newly installed and the number of femto base stations is increased, not only newly installed femto base stations but also existing surrounding femto base stations must be reset.

  On the other hand, in the radio base station apparatus according to the embodiment of the present invention, the terminal moving speed acquisition unit 14 acquires the moving speed of one or a plurality of radio terminal apparatuses 202. The cell radius information acquisition unit 13 acquires cell radius information that can evaluate the cell radius of the own radio base station apparatus 101. The random access signal selection unit 12 can use the wireless terminal device 202 based on the moving speed acquired by the terminal moving speed acquisition unit 14 and the cell radius information acquired by the cell radius information acquisition unit 13. Select multiple types of random access signals.

  With such a configuration, it is possible to select an optimal random access signal according to the moving speed of the wireless terminal device 202 and the cell radius of its own wireless base station device 101.

  Therefore, the radio base station apparatus according to the embodiment of the present invention can construct a good communication system by appropriately setting the random access signal.

  In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  Also, in the radio base station apparatus according to the embodiment of the present invention, the random access signal selection unit 12 can select a plurality of types of random access signals when the moving speed acquired by the terminal moving speed acquisition unit 14 is greater than a predetermined threshold. One or a plurality of types of random access signals corresponding to the cell radius of the own radio base station apparatus 101 obtained based on the cell radius information are selected from the access signals.

  In this way, particularly when the moving speed of the wireless terminal device 202 is high, the configuration in which the random access signal corresponding to the cell radius of its own wireless base station device 101 is selected, and the selectable range of random access signals in an appropriate situation In addition, an appropriate limit can be set according to the cell radius.

  Further, in the radio base station apparatus according to the embodiment of the present invention, the storage unit 15 stores the random access signal in the radio base station apparatus 101 of the type of the random access signal and the cell formed by the radio base station apparatus 101. Information indicating a correspondence relationship with the maximum detectable radius is stored. Then, when the moving speed acquired by the terminal moving speed acquisition unit 14 is larger than a predetermined threshold, the random access signal selection unit 12 selects a cell radius from a plurality of types of random access signals based on the above information. One or a plurality of types of random access signals that are larger than the cell radius of the own radio base station apparatus 101 obtained based on the information and that correspond to the maximum radius closest to the cell radius of the own radio base station apparatus 101 are selected.

  Thus, a cell larger than its own radio base station apparatus 101 can be obtained by selecting a random access signal corresponding to the maximum radius closest to the cell radius of its own radio base station apparatus 101 among the maximum radii in the above information. The possibility that the selectable range of the random access signal in the radio base station apparatus 101 forming the radius is eliminated or restricted can be reduced.

  In the radio base station apparatus according to the embodiment of the present invention, the terminal moving speed acquisition unit 14 performs the handover operation of the radio terminal apparatus 202 from another radio base station apparatus 101 to its own radio base station apparatus 101. In this case, the moving speed of the wireless terminal device 202 included in the handover request from the other wireless base station device 101 is acquired.

  As described above, by acquiring the moving speed of the wireless terminal device 202 from the handover source wireless base station device 101, for example, the moving speed of the wireless terminal device 202 including the moving speed in the other wireless base station device 101 is accurately determined. Statistical values can be obtained.

  In the radio base station apparatus according to the embodiment of the present invention, the random access signal selection unit 12 can use one or a plurality of radio terminal apparatuses 202 that can be used based on the cell radius information of its own radio base station apparatus 101. Although the configuration is such that a random access signal of a type is selected, the present invention is not limited to this. The random access signal selection unit 12 does not use the cell radius information of its own radio base station apparatus 101, and when the high speed flag is asserted by the selection range restriction unit 11 and when the high speed flag is not asserted. Any configuration that selects a random access signal within a limited range may be used.

  That is, as a modification of the radio base station apparatus according to the embodiment of the present invention, the following configuration can be adopted. That is, the random access signal selection unit 12 selects one or a plurality of types of random access signals that can be used by the wireless terminal device 202 from a plurality of types of random access signals. Then, the selection range restriction unit 11 restricts the selection range of the random access signal by the random access signal selection unit 12 based on the movement speed of the one or more wireless terminal devices 202 acquired by the terminal movement speed acquisition unit 14. Is provided.

  With such a configuration, it is possible to set an optimal random access signal selectable range according to the moving speed of the wireless terminal device 202. Therefore, a good communication system can be constructed by appropriately setting a random access signal.

  In addition, since the parameters related to the RACH of femto base stations and pico base stations that are often installed unplanned can be automatically set, CAPEX (Capital Expenditure), that is, the cost required for arrangement of radio base station apparatuses, and OPEX (Operational Expenditure), that is, the cost for operating the radio base station apparatus can be reduced.

  Further, in this modification, the cell radius information acquisition unit 13 acquires cell radius information that can evaluate the cell radius of the own radio base station apparatus 101. Then, the selection range restriction unit 11 provides the restriction based on the movement speed acquired by the terminal movement speed acquisition unit 14 and the cell radius information acquired by the cell radius information acquisition unit 13.

  With such a configuration, it is possible to provide a more appropriate restriction on the selectable range of the random access signal based on the cell radius information of the own radio base station apparatus 101 in addition to the moving speed of the radio terminal apparatus 202. .

  In the radio communication system according to the embodiment of the present invention, radio base station apparatus 101 operates as a random access control apparatus. That is, although the radio base station apparatus 101 is configured to select a random access signal based on the moving speed of the radio terminal apparatus 202, the present invention is not limited to this. The random access control device may be a management device for managing one or a plurality of radio base station devices 101. Specifically, a management apparatus for managing the radio base station apparatus 101, such as the gateway apparatus 203 and the host apparatus 205, may be configured to select a random access signal based on the moving speed of the radio terminal apparatus 202. .

  In this case, in the management device, the terminal moving speed acquisition unit acquires the moving speed of one or more wireless terminal devices 202. The cell radius information acquisition unit acquires cell radius information that can evaluate the cell radius of the target base station that is the target radio base station apparatus 101. Then, the random access signal selection unit is configured to use one or a plurality of types of radio terminals 202 that can be used based on the moving speed acquired by the terminal moving speed acquisition unit and the cell radius information acquired by the cell radius information acquisition unit. Select a random access signal.

  Alternatively, in the management device, the terminal moving speed acquisition unit acquires the moving speed of one or a plurality of wireless terminal devices 202. The random access signal selection unit selects one or more types of random access signals that can be used by the wireless terminal device 202 from among a plurality of types of random access signals. Then, the selection range restriction unit places a restriction on a selectable range of the random access signal by the random access signal selection unit based on the movement speed acquired by the terminal movement speed acquisition unit.

  With such a configuration, since the setting of the random access signal of each radio base station apparatus 101 in the radio communication system 301 can be performed collectively in the management apparatus, the setting related to the random access signal can be performed more efficiently. it can.

  On the other hand, with the configuration in which the random access control apparatus is the radio base station apparatus 101 as in the radio communication system according to the embodiment of the present invention, the setting of the random access signal in the radio communication system 301 is performed by each radio base station apparatus 101. Since this can be done, it is possible to disperse the processing load of the setting relating to the random access signal.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 11 Selection range restriction | limiting part 12 Random access signal selection part 13 Cell radius information acquisition part 14 Terminal movement speed acquisition part 15 Memory | storage part 91 Antenna 92 Circulator 93 Radio | wireless reception part 94 Radio | wireless transmission part 95 Signal processing part 96 Reception signal processing part 97 Transmission signal Processing unit 98 Control unit 101 Wireless base station device 101A, 101B, 101C Femto base station 101D Pico base station 201 Macro base station 202 Wireless terminal device 203 Gateway device 204 Core network 205 Host device 301 Wireless communication system

Claims (10)

In order to adjust the transmission timing from the wireless terminal device to the target base station that is the target wireless base station device, the target base station detects, and the wireless terminal device establishes a communication connection with the target base station. A random access signal for selecting one or a plurality of types of random access signals that can be used by the radio terminal device from a plurality of types of random access signals for a random access signal transmitted from the radio terminal device in advance. A selection section;
A terminal moving speed acquisition unit for acquiring the moving speed of one or more wireless terminal devices;
A random access control device comprising: a selection range restriction unit for providing a restriction on a selectable range of the random access signal by the random access signal selection unit based on the moving speed. The random access control device further includes:
A cell radius information acquisition unit for acquiring cell radius information capable of evaluating the cell radius of the target base station;
The random access control apparatus according to claim 1, wherein the selection range restriction unit provides the restriction based on the moving speed and the cell radius information. A terminal moving speed acquisition unit for acquiring the moving speed of one or more wireless terminal devices;
A cell radius information acquisition unit for acquiring cell radius information capable of evaluating a cell radius of a target base station which is a target radio base station device;
Detected by the target base station to adjust the transmission timing from the radio terminal device to the target base station, from the radio terminal device prior to the radio terminal device establishing a communication connection with the target base station A random access signal selection unit for selecting one or a plurality of types of random access signals that can be used by the wireless terminal device based on the moving speed and the cell radius information for the random access signal to be transmitted; Random access control device.   The random access signal selection unit may select a cell radius of the target base station obtained based on the cell radius information from a plurality of types of the random access signals when the moving speed is greater than a predetermined threshold. The random access control apparatus according to claim 2 or 3, wherein one or a plurality of types of corresponding random access signals are selected. The random access control device further includes:
A storage unit for storing information indicating a correspondence relationship between a type of the random access signal and a maximum radius of the cell formed by the radio base station device that can detect the random access signal in the radio base station device; ,
When the moving speed is higher than a predetermined threshold, the random access signal selection unit is configured to obtain the target base based on the cell radius information from a plurality of types of the random access signals based on the information. The random access control apparatus according to claim 4, wherein one or a plurality of types of random access signals corresponding to the maximum radius that is larger than a cell radius of a station and closest to a cell radius of the target base station are selected.   A radio base station apparatus comprising the random access control apparatus according to claim 1.   The terminal moving speed acquisition unit includes the wireless terminal device included in a handover request from the other wireless base station device when a handover operation of the wireless terminal device from another wireless base station device to the target base station is performed. The radio base station apparatus according to claim 6, which acquires a moving speed of   A management apparatus that manages one or a plurality of radio base station apparatuses and includes the random access control apparatus according to claim 1. A random access control program used in a random access control device, the computer,
In order to adjust the transmission timing from the wireless terminal device to the target base station that is the target wireless base station device, the target base station detects, and the wireless terminal device establishes a communication connection with the target base station. Selecting one or a plurality of types of random access signals that can be used by the wireless terminal device from a plurality of types of random access signals for a random access signal transmitted from the wireless terminal device in advance;
A random access control program for executing a step of limiting a selectable range of the random access signal based on a moving speed of one or a plurality of wireless terminal devices. A random access control program used in a random access control device, the computer,
Obtaining a moving speed of one or more wireless terminal devices;
Obtaining cell radius information capable of evaluating a cell radius of a target base station that is a target radio base station device; and
Detected by the target base station to adjust the transmission timing from the radio terminal device to the target base station, from the radio terminal device prior to the radio terminal device establishing a communication connection with the target base station Random access control for causing a random access signal to be transmitted to select one or more types of random access signals that can be used by the wireless terminal device based on the moving speed and the cell radius information program.

Images